Installation of automation systems should be carried out in accordance with the working documentation, taking into account the requirements of enterprises - manufacturers of devices, automation equipment, aggregate and computer systems, provided for by the technical specifications or operating instructions for this equipment.
Installation work should be carried out by the industrial method using small-scale mechanization, mechanized and electrified tools and devices that reduce the use of manual labor.
Work on the installation of automation systems should be carried out in two stages (stages):
At the first stage, it is necessary to carry out: preparation of mounting structures, assemblies and blocks, electrical wiring elements and their pre-assembly outside the installation area; checking the presence of embedded structures, openings, holes in building structures and elements of buildings, embedded structures and selective devices on process equipment and pipelines, the presence of a grounding network; laying in the foundations under construction, walls, floors and ceilings of pipes and blind boxes for hidden wiring; route marking and installation of supporting and supporting structures for electrical and pipe wiring, actuators, devices.
At the second stage, it is necessary to carry out: laying pipe and electrical wiring according to established structures, installing shields, cabinets, consoles, instruments and automation equipment, connecting pipe and electrical wiring to them, individual tests.
Mounted devices and automation equipment for the electrical branch of the State Instrumentation System (SSE), panels and consoles, structures, electrical and pipe wiring to be grounded according to the working documentation, must be connected to the ground loop. If there are requirements of enterprises - manufacturers, the means of aggregate and computer systems must be connected to the ground loop. If there are requirements of enterprises - manufacturers, the means of aggregate and computer systems must be connected to a special ground loop.
Devices and means of automation
Devices and automation equipment, checked with the execution of the relevant protocols, should be accepted for installation.
In order to ensure the safety of instruments and equipment from breakage, dismantling and theft, their installation must be carried out after the written permission of the general contractor (customer).
Testing of devices and automation equipment is carried out by the customer or specialized organizations involved by him, performing work on setting up devices and automation equipment using the methods adopted in these organizations, taking into account the requirements of the instructions of the State Standard and manufacturers.
Instruments and automation equipment accepted for installation after verification must be prepared for delivery to the installation site. Movable systems must be caged, connecting devices are protected from moisture, dirt and dust.
Along with devices and automation equipment, special tools, accessories and fasteners included in their kit, necessary for installation, must be transferred to the installation organization.
The placement of instruments and automation equipment and their relative position should be carried out according to the working documentation. Their installation should ensure the accuracy of measurements, free access to the instruments and their shut-off and adjustment devices (taps, valves, switches, adjustment knobs, etc.).
In places where devices and automation equipment are installed, which are inaccessible for installation and maintenance, the construction of ladders for wells and platforms must be completed before the start of installation in accordance with the working documentation.
Instruments and automation equipment must be installed at ambient temperature and relative humidity specified in the installation and operating instructions of manufacturers.
Connection of external pipe wiring to the devices must be carried out in accordance with the requirements of GOST 25164 - 82 and GOST 10434 - 82, GOST 25154 - 82, GOST 25705 - 83, GOST 19104 - 79 and GOST 23517 - 79.
Fixing devices and automation equipment to metal structures (shields, cabinets, stands, etc.) should be carried out in the ways provided for by the design of devices and automation equipment and the parts included in their kit. If fasteners are not included in the set of individual devices and automation equipment, then they must be fixed with normalized fasteners.
In the presence of vibrations in the places of installation of devices, threaded fasteners must have devices that exclude their spontaneous unscrewing (spring washers, lock nuts, cotter pins, etc.).
The openings of devices and automation equipment intended for connecting pipe and electrical wiring must remain plugged until the wiring is connected.
Cases of devices and automation equipment must be grounded in accordance with the requirements of the instructions of manufacturers and SNiP 3.05.06-85.
The sensitive elements of liquid thermometers, temperature alarms, manometric thermometers, thermoelectric converters (thermocouples), resistance thermocouples should, as a rule, be located in the center of the measured medium flow. At pressures over 6 MPa (60 kgf/cm2) and steam flow rates of 40 m/s and water flow rates of 5 m/s, the depth of immersion of sensitive elements into the measured medium (from the inner wall of the pipeline) should be no more than 135 mm.
The working parts of surface thermoelectric transducers (thermocouples) and resistance thermocouples must fit snugly against the controlled surface.
Before installing these devices, the place of their contact with pipelines and equipment must be cleaned of scale and cleaned to a metallic sheen.
Thermoelectric converters (thermocouples) in porcelain fittings may be immersed in the high temperature zone for the length of the porcelain protective tube.
Thermometers, in which protective covers are made of different metals, must be immersed in the measured medium to a depth not exceeding that indicated in the manufacturer's passport.
It is not allowed to lay the capillaries of manometric thermometers on surfaces whose temperature is higher or lower than the ambient air temperature.
If it is necessary to lay capillaries in places with hot or cold surfaces, there must be air gaps between the latter and the capillary to protect the capillary from heating or cooling, or appropriate thermal insulation must be laid.
Along the entire length of the gasket, the capillaries of manometric thermometers must be protected from mechanical damage.
In case of excess length, the capillary should be rolled into a coil with a diameter of at least 300 mm; the bay must be tied in three places with non-metallic bandages and securely fastened to the device.
Instruments for measuring vapor or liquid pressure should, if possible, be installed at the same level as the pressure tap; if this requirement is not feasible, the working documentation should define a constant correction to the instrument readings.
Liquid U - figurative manometers are established strictly vertically. The fluid filling the pressure gauge must be clean and free of air bubbles.
Spring pressure gauges (vacuum gauges) must be installed in a vertical position.
Separation vessels are installed according to the standards or working drawings of the project, as a rule, near the points of sampling of impulses. Separation vessels must be installed so that the control openings of the vessels are at the same level and can be easily serviced by operating personnel.
For piezometric level measurement, the open end of the measuring tube must be set below the minimum measurable level. The gas or air pressure in the measuring tube must allow the gas (air) to pass through the tube at the maximum liquid level. The flow rate of gas or air in piezometric level gauges must be adjusted to a value that provides coverage of all losses, leaks and the required speed of the measuring system.
The installation of instruments for physical and chemical analysis and their selective devices must be carried out in strict accordance with the requirements of the instructions of the enterprises - manufacturers of instruments.
When installing indicating and recording devices on a wall or on racks attached to the floor, the scale, diagram, shut-off valves, adjustment and control elements of pneumatic and other sensors should be at a height of 1-1.7 m, and the shut-off valve controls should be in the same plane with instrument scale.
Installation of aggregate and computer complexes of automated process control systems should be carried out according to the technical documentation of manufacturers.
All devices and automation equipment installed or built into process equipment and pipelines (restriction and selective devices, meters, rotameters, level gauge floats, direct-acting regulators, etc.) must be installed in accordance with the working documentation and with the requirements specified in mandatory annex 5.
Operation of devices and automation equipment
During the operation of devices, a partial loss of operability of measuring and automation instruments occurs, caused both by the duration of their operation and by the influence of the surrounding and measured environments. To ensure the trouble-free operation of measuring instruments (hereinafter referred to as SI) and automation, restoring their resource, maintenance is required.
Maintenance is a complex of operations to maintain the operability and serviceability of measuring instruments, automation and automation equipment, and SB and ESD circuits. It is carried out by instrumentation and instrumentation technicians at technological installations of OAO NORSI.
Guiding materials for the technical operation of devices are:
Order No. 325 dated 11/1/99. “On changing the duration of overhaul cycles for instrumentation and A of technological installations”;
Manufacturer's instructions;
Rules for the operation of consumer electrical installations (PEEP);
Rules for the installation of electrical installations (PUE);
Real instruction.
1. The task of automation of chemical industry facilities.Automation is the use of a set of tools that make it possible to carry out production processes without the direct participation of a person, but under his control. Automation of production processes creates certain technical and economic advantages in all sectors of the modern national economy of the country.
First of all, the nature and conditions of work in production are changing. The labor costs of a person are reduced to a minimum, the psychological load is reduced, and only the functions of reconfiguring automatic systems to new modes and participating in repair and adjustment work remain on their share. The number of service personnel and the cost of its maintenance are reduced. With the introduction of automation tools, labor productivity inevitably increases. The introduction of automation in various industries gives an increase in labor productivity by an average of 2 ... 2.5 times. As a result of automation, the cost of products is reduced, output is increased, its quality is increased, defects and production waste are reduced, costs for wages, raw materials, materials, etc. are reduced. In this case, the decisive factor is the reduction in fuel consumption, heat and electricity. The use of automation tools increases the reliability of equipment, production accuracy, and labor safety. It becomes possible to use highly efficient technological processes and devices, the nature of which excludes human participation (nuclear energy, chemical production, etc.). But, perhaps, the main thing is that automation increases the efficiency and orderliness of production. The control process resists disorder, and in this respect the use of automation decisively stabilizes production. The introduction of automation also brings an indirect effect, since an increase in equipment productivity, resource savings are equivalent to the construction of additional production capacities. Saving labor allows for a more rational use of labor resources, and improving product quality helps save fuel, energy, materials, etc. The most important issue of automation is the establishment of its rational level and volume, which must be carefully economically justified, and the definition of methods and means of automation .
Automation is a branch of theoretical and applied knowledge about devices and systems that operate without direct human participation. Automatic (from the Greek automates - self-acting) - an independently operating device (or a set of devices) that performs various processes according to a given program without direct human participation. Automated system - a set of managed object and automated control devices. At the same time, part of the management functions is performed by a person. The automated system receives information from the control object, transmits, converts and processes it, generates control commands and executes them on the controlled object. A person determines the goals and criteria of management, corrects them if conditions change. An automatic system is a set of a controlled object and automatic measuring and control devices. Unlike an automated system, it is carried out without human intervention (except for the stages of launching and setting up the system).
^ 2. Scope and degree of automation
The success of automation is largely determined by the right choice of degree and amount of automation. According to the degree of automation, objects with partial, complex and full automation are distinguished. Partial automation is the first stage of automation, in which individual machines, mechanisms and installations that do not have external connections with other production processes are transferred to remote or automatic control. Partial automation does not allow you to use all the advantages of automation, since non-automated processes remain in the technological chain. Integrated automation is the second stage of automation, in which the entire range of production operations, as well as auxiliary operations, are carried out according to pre-developed programs and modes using various automatic devices united by a common control system. At the same time, human functions are reduced to monitoring the progress of the process, analyzing its indicators and choosing the operating modes of the equipment. Full automation is the final stage of production automation, in which the system of automatic machines performs, without direct human participation, the entire range of operations of the production process, including the selection and establishment of operating modes that provide the best performance under given conditions. The scope of automation is determined by the number of operations, processes and devices that are controlled by automation. The level of automation is understood as the degree of perfection of the technical means by which automation is carried out. The degree of automation, its volume and level are chosen for each facility with the justification of technical and economic efficiency and the possibility of eliminating difficult and harmful working conditions for maintenance personnel.
^ 3. Classification of automation subsystems
In the course of managing complex and simple objects, it is necessary to carry out many functionally different operations that are performed by different subsystems that are part of the overall object automation scheme. Information includes subsystems of technological control and telemetry, technological and telesignaling. The result of the actions of these subsystems is addressed to the operator, and his task is to make a decision. Protective subsystems include means of technological and emergency protection, technological and emergency blocking, which protect technological equipment from the consequences of improper operation. Managers include telecontrol subsystems, including remote control, telemechanical subsystems, dispatching, automatic control and regulation. The main functions of the technological control subsystem: a) obtaining quantitative and qualitative indicators of the technological process - all types of measurements using control and measuring instruments (CIP); b) monitoring the progress of the technological process. The difference in the functions lies in the fact that in the second case, the nature of the change in values is fixed. To implement the functions of technological control, devices of local and remote action, as well as devices with registration, are used. Similar functions for the process signaling subsystem. For it, the same devices and technical means are used, only the form of information presentation in the form of a corresponding signal differs. These are light, sound, color (paint color changes), odorization (smell appears) alarm. Form of signaling - continuous and discrete (flashing). It is very important that the signal is not frightening and monotonous (habitual). Sound signals are given by calls, sirens, howlers, buzzers, sometimes shots, light signals - by lamps, scoreboards, mnemonic diagrams. Information should be transmitted without delays and distortions, and, preferably, in an alternative form (yes - no). The main requirement for signals is sufficient information content. According to the functional features, the signaling subsystems are divided into command, control, warning, emergency and positions (to notify that devices have reached extreme or intermediate positions). A very important role is played by technological protection and blocking subsystems, the purpose which consists in the protection of process equipment from emergencies and violations of the regime due to improper operation of jointly working objects. The main reasons for the violation of the regime are: the cessation of the supply of raw materials or energy, as well as the failure to comply with the synchronism of the installations. These subsystems, of course, are automatic and carry out prompt intervention to stop the operation of the object as a whole or part of it by stopping or transferring to idle. Thus, a blocking effect is carried out. Unblocking action - restart after elimination of the cause of violation of the mode. Distinguish object locks (automatic protection) and interobject (synchronous protection). The former include the action of various kinds of safety devices - valves, fuses, etc. An example of inter-object blocking can be a well-known sequence of operations when starting radial pumps: closing the shut-off valve, starting the pump, then opening the line. A special type of blocking is emergency protection, when the access of energy, raw materials, product to the object is automatically terminated in order to exclude its inevitable failure. This often includes automatic fire extinguishing and smoke removal subsystems. The level of equipping the automation object with various subsystems depends on the specific operating conditions and regulatory documents that determine the minimum required level of automation.
^ 4. Basic concepts of management
Industrial production is usually divided into a number of technological processes. A technological process is understood as a set of mechanical, physical, chemical and other processes of purposeful processing of raw materials in order to obtain finished products. Each technological process is characterized by certain technological parameters that can change over time. In chemical technology, such parameters are the consumption of material and energy flows, chemical composition, temperature, pressure, and the level of substance in technological apparatuses. The set of technological parameters that fully characterize a given technological process is called the technological regime. Any technological process is subject to the action of various factors, random in nature, which cannot be foreseen in advance. Such factors are called perturbations. These include, for example, random changes in the composition of raw materials, the temperature of the coolant, the characteristics of process equipment. Disturbing influences on the technological process cause changes in the technological regime, which, in turn, leads to a change in such technical and economic indicators of the process as productivity, product quality, consumption of raw materials and energy. Therefore, to ensure the given (required) technical and economic indicators, it is necessary to compensate for fluctuations in the technological regime caused by the action of disturbances. Such a purposeful impact on the technological process is a process of management. The set of requirements implemented in the management process is called the goal of management. The controlled technological process itself, together with the technological equipment in which it takes place, is the object of control. The control object and the devices necessary for the implementation of the control process are called the control system.
^ 5. Hierarchy of industrial enterprise management
Modern chemical engineering processes are very complex and are characterized by a large number of technological parameters that directly or indirectly affect their technical and economic performance. Therefore, the management of chemical-technological processes is organized according to the so-called hierarchical principle. The hierarchical principle of management consists in a multi-stage organization of the management process, where each level of management has its own objects and goals of management. The management structure of a modern industrial enterprise is characterized by three levels of the management hierarchy (Fig. 1.). The lower level (I) is a local control system, the functions of which are reduced to the stabilization of individual technological parameters. Such simple tasks are solved by automatic devices without human intervention, and therefore the control systems of the lower hierarchical level are called automatic control systems (ACS). The objects of regulation at this level are elementary processes with the corresponding technological devices.
Fig 1. Hierarchy of enterprise management
The next hierarchical level (II) is formed by process control systems. The objects of control at this level are already entire technological processes, together with technological equipment and local ACS. Here, the tasks of optimizing the technological regimes of processes are solved. In addition, the control functions at this level include the identification and elimination of abnormal (emergency) modes, the switching of equipment in technological schemes, the calculation of technical and economic indicators of processes, etc. These control functions are relatively complex and cannot be entirely assigned to automatic devices . Therefore, in process control systems, control computer complexes (CCUs) are used. Such control systems are called automated process control systems (APCS). Process control systems are designed to develop and implement control actions on a technological control object in accordance with the accepted control criterion (optimality) and with the help of modern means of collecting and processing information (primarily computer technology). At the top hierarchical level (III) the entire enterprise is managed. The object of control here is all production and equipment, as well as process control systems of the previous hierarchical level. Here, the tasks of managing the entire production as a whole with the use of computers and the participation of operators are solved. At the same time, the tasks of not only technological management of individual industries, but also planning and economic tasks are solved, and the efficiency of the entire enterprise is ensured. The control system of this level is called the automated enterprise management system (APCS). From the foregoing, the role of local automated control systems of the lower hierarchical level in the overall process of managing an industrial enterprise is visible: they are peripheral controls through which decisions made in the management process at higher hierarchical levels are implemented .
^ 6. Basic principles of management
The theory of automatic control studies the principles of building automatic control systems (ACS) and methods for studying processes in these systems; solves the problems of synthesis, analysis, correction, experimental research and adjustment of automatic control systems. An automatic system that for a long time in the required way changes or maintains any physical quantities unchanged (coordinates of a moving object, speed, electrical voltage, frequency, temperature, pressure and etc.) in a controlled process or system is called an automatic control system. ACS performs control without human intervention and generates influences that provide the required mode of operation of the control object - a change in output values characterizing the state of the control object in accordance with a given law or ensuring the constancy of any output value. ACS consists of control devices (CU) and a control object (OC). The values characterizing the state of the OS are called output or controlled. The actions arriving at the input of the control unit are called master. The actions generated by the control device and directly changing the state of the control device are called control. Actions that cause unauthorized deviation of the controlled value from the set value are called disturbing actions. The driving and disturbing influences are combined into a group of input actions. The task of control, in essence, consists in the formation of such a law for changing the control action, which provides a given algorithm in the presence of disturbing influences. To solve this problem, three fundamental control principles are used: open-loop control, disturbance control (compensation principle) and closed-loop control (feedback principle or deviation control). The essence of the open-loop control principle is that control is built only on the basis of a given functioning algorithm and is not controlled by the actual value of the controlled variable, that is, the current state of the OS is not taken into account when generating control actions. The process of the system operation does not directly depend on the result of its impact on the control object. The setter of the algorithm for the functioning of the ZAP supplies the master action x(t), which is converted by the control devices into the control action z(t). Under the influence of control, the state of the control object of the CO, characterized by the controlled value y(t), changes so that the value y(t) is equal to the required value, the value of which is determined by the setting input x(t). The presence of a disturbing influence f(t) leads to the fact that the actual value of the controlled variable y(t) differs from the specified one, that is, a control error appears. If the action of disturbances is constant or periodic, the control error accumulates and, in the limit, a system failure may occur. Thus, the open-loop control principle is inapplicable under conditions of significant interference and disturbances. In the absence of disturbances, the reproduction of a given value is ensured by the rigidity of the characteristics of the devices that make up the circuit. Open-loop control in its pure form is rarely used and only in simple circuits. When implementing control by deviation, the control action on the OS is generated as a function of the deviation of the controlled variable from the set value. The control circuit contains feedback, that is, the controlled value from the output of the system is fed to its input (Fig. 3.). The deviation control system is thus closed. At the system input, the ES comparison element subtracts x(t)-y(t)=e(t). The value of e(t) is called the mismatch. The control devices of the control unit operate in such a way as to reduce the mismatch to zero all the time. Feedback of this type is called negative. The versatility and efficiency of the deviation control principle lies in the fact that it allows implementing a given law of change of the controlled variable y(t) regardless of whether the change in which of the input actions - the setting x(t) or the disturbing f(t) - caused the mismatch to occur. The ACS by deviation responds to an integrated external influence, which manifests itself in a change in the controlled (measured) controlled variable. The advantages of ACS in terms of deviation include the simplicity of technical implementation and high control accuracy. The disadvantages of systems with feedback include insufficient efficiency, due to the fact that the system is aimed at eliminating the mismatch. That is, the ACS first allows a change in the controlled variable under the influence of external or internal disturbances, and then eliminates it. When controlling by deviation, the influence of disturbing influences on the output value is significantly weakened, but not eliminated. In the case when a change in the state of the OS under the action of one or several certain disturbances is unacceptable, the principle of control by disturbance is used. The essence of the principle is that the disturbance measured by the sensor is converted into an action applied to the control unit, which forms the control action z(t) taking into account the disturbing action. z(t) is applied to the input of the op-amp in order to compensate (prevent) the influence of this disturbance on the controlled value y(t). .e. the main perturbing action, and its transformation into a control action. The advantages of automatic control systems implemented according to the principle of perturbation include greater efficiency compared to OS systems. The disadvantage of perturbation control systems is that they compensate for the influence of one or several predetermined disturbances and cannot prevent the influence of other perturbations on the controlled value. In this case, the control error occurs even when all perturbations are taken into account, since the system cannot resist changes in the internal properties of the CU and OC. Improving the quality of control under the action of disturbances can be achieved using combined control. In combined control systems, the input of control devices, in addition to the mismatch calculated from the master action and the feedback signal, receives a signal obtained by measuring disturbing actions. Usually, in combined circuits, only the main disturbance is measured, the influence of other disturbances is taken into account through the feedback loop. The class of automatic systems built on the basis of the principle of closed control is called automatic control systems (ACS).
^
7. General concepts about ATS systems. Functional diagram of a closed automatic
control systems (SAR).Automatic regulation
is called maintaining a constant of some given value characterizing the process, or changing it according to a given law, carried out by measuring the state of an object under perturbations acting on it.Automatic control system
(SAR) is called a closed dynamical system, in which a constant value is maintainedone or more quantities characterizing the proteorunning a process for a long time at
arbitrarily changing external disturbing factors.Each automatic regulator, working on a specificobject, forms with it a system (loop) of regulation. Thus, the automatic control system consists ofect regulation and automatic regulator.In the process of regulation, the regulator and the object of regulationinterrelated and, therefore, the quality of regulation dependsboth from the properties of the given object, and from the properties and characteristicsapplicable regulator and regulatory body.The control device processes the information received through the measuring and converting devices (sensors and amplifiers) according to a certain control algorithm (law) embedded in it and through the actuator (for example, an electric motor) acts on the object with the help of an adjustable body (valve, valve).
automatic control systems
^ 8. The concept of feedback. Classification (CAP). Depending on the main goal, the control tasks of the ACS are classified as follows: stabilization systems, program control system, tracking systems. AT stabilization systems the operating parameter of the object (controlled value) is maintained constant over time at a constant .V program control systems the operating parameter of the object changes in time according to a previously known law, in accordance with which the task changes. tracking systems the operating parameter of the object changes in time according to a previously unknown law, which is determined by some external independent process. Depending on the nature of the action of the various elements included in the control system, systems are distinguished continuous and discrete actions. Continuous the automatic control system consists only of continuous action links, the output value of which changes with a smooth change in the input value. Discrete system contains at least one link of discrete action, the output value of which changes in jumps (discretes) with a smooth change in the input value. Discrete systems in turn, they can be relay, pulse or digital. Due to the rapid development of microelectronics, digital control systems, which, first of all, have high accuracy, have become widespread. An important property is also the behavior of the system parameters over time. If the parameters are unchanged during the operation period, then the system is considered stationary , otherwise - non-stationary. In addition, systems with distributed parameters are especially distinguished, i.e. such systems that contain elements distributed in space, for example, long electrical lines, etc. According to the method of mathematical description, control systems are divided into linear and non-linear .Depending on the nature of external influences (setting and disturbing), there are deterministic and stochastic systems. In deterministic ACS, external influences have the form of constant functions of time. In stochastic systems, external influences have the form of random functions. In the future, only deterministic systems will be considered. According to the properties of the error (deviation) in the steady state, they distinguish static and astatic systems . A system in which the magnitude of the steady-state error depends on the magnitude of the perturbation at a constant setting is called static in perturbation. If the steady-state error does not depend on the magnitude of the perturbation, then the system is astatic of the 1st order. If the steady-state error does not depend on the first derivative of the perturbing action, then the system is astatic of the 2nd order.
^ 9. Concepts of multi-loop automatic control systems and extreme regulation.
According to the number of signal paths, the ACP is divided into: single-loop (if it consists of one control loop) and multi-loop . Multiloop ACPs can also be used to control one value in order to improve the quality of the transient process. According to the number of adjustable values distinguish one-dimensional and multidimensional automatic control systems. In turn, multidimensional ACS are divided into systems unrelated and related regulation. Characteristic for the former is that the regulators in them do not have a direct connection with each other and interact only through the object of regulation. In coupled control systems, controllers of various parameters of the same object have direct interconnections in addition to links through the control object. Along with the considered automatic control systems, they are also used extreme systems. The optimal operating mode of an object is characterized by an extreme (maximum or minimum) value of the efficiency indicator of the process taking place in the object. Due to the influence of disturbances, the optimal mode of operation of objects is violated. Stabilization systems are not able to compensate for such deviations. To find the optimal mode, extreme systems . This problem is solved by automatic search for such values of control actions that correspond to the extreme value of the process efficiency indicator. Systems that automatically search for several control variables of an object in order to provide an extreme value of the efficiency indicator of the process occurring in it are called optimal. In practice, the optimized value of the object often depends not on several, but on one control variable; such optimal systems are called extreme systems.
^ 10. Mathematical description of ACS and their elements The purpose of considering automatic control systems can be to solve one of two problems - tasks of system analysis or synthesis . In the first case, there is a system, its parameters are known, it is required to determine the properties of the system, for example, the quality of transient processes, stability, accuracy. In the second case, on the contrary, the properties of the system are set and it is necessary to create a system that satisfies these properties. This task, as a rule, is ambiguous and much more difficult than the task of analysis. In the most general form, the procedure for studying the control system includes a mathematical description of the system, the study of steady and transient modes. Under mathematical description understand a differential equation or a system of high-order differential equations describing a control system. To simplify the mathematical description, the system is divided into separate elements - links, each of which perform their own functions . They are described either analytically in the form of differential equations not higher than the 2nd order, or graphically in the form of characteristics connecting the input and output values of the link. The main requirement that the links of the regulatory system must satisfy is the requirement focus actions. Link directional action is called a link that transmits the action in only one direction - from the input to the output, so that with a serial connection X links, a change in the state of the next link does not affect the state of the previous link. As a result, when the system is divided into links of directional action, a mathematical description of each link can be compiled without taking into account its connections with other links. In this case, the mathematical description of the entire control system can be obtained as a set of differential equations or characteristics of individual links, supplemented by the equations of communication between the links.
^
11. Methods for obtaining mathematical models of statics and dynamics. Concepts about linear elements.
The properties of automatic control systems are determined by the static and dynamic characteristics of the links included in the system, and the control object is considered as a component of the control system. Static
the characteristic of an element (technical device) is the dependence of its output value on the input value in equilibrium states, that is: 
The static characteristic can be represented by an equation, graph or table. With a graphical representation of a static characteristic, the values of the input quantity are plotted along the abscissa axis 
, and along the y-axis - the values of the output quantity 
. A static characteristic is called linear if the relationship between and is linear (graphically it is a straight line). An element with this characteristic is also called linear
.If a characteristic is described by a non-linear equation or a system of equations, and its graph is a curve or a broken line, then such a characteristic is called non-linear, and the element is called non-linear. Possible characteristics of linear and non-linear elements are shown in Fig.6.
Rice. 6 - Static characteristics of elements:
A - linear, b, c, d, e, f - non-linear.
The equation of a linear static characteristic has the form:
Where 
- the coefficient of proportionality, called the gain.
For non-linear elements, the mathematical notation of the static characteristic may be different depending on the type of non-linearity.
Most of the elements that make up the ATS are non-linear to a greater or lesser extent.
Considering that ACS calculations are made for relatively small deviations of variables from their basic values ( 
, 
), so the equations are written not in the absolute values of the variables, but in their absolute deviations:
Non-linear elements with smoothly varying characteristics can be considered as having a linear static characteristic. In this case, the linearization of the static characteristic can be performed not over the entire range of input and output values, but in a small area in the vicinity of the point corresponding to the equilibrium state.
In Fig.6. (c) a small section of the non-linear characteristic near the point A (base values and ) can be considered linear. It coincides with the tangent drawn to the curve at this point. The gain of the linear section of the characteristic is defined here as the tangent of the slope angle 
tangent to the x-axis:
In the future, we will consider elements whose characteristics are linear or can be linearized with an acceptable degree of accuracy.
Control systems consisting of such elements are called linear (or linearized).
^ 12. Dynamic characteristics of dynamic elements, transfer functions. Since ACS are dynamic systems, knowledge of the static properties of ACS elements alone is not enough. It is necessary to know the dynamic properties of the ACS elements, estimated by the dynamic characteristics. dynamic the characteristic of an element is the dependence of the change in time of the output value on the change in the input in the transient mode, i.e. during the transition from one state to another; the nature of the change in the input value can be different. The dynamic properties of the elements (and ACS as a whole) can be represented by differential equations, which describe the transient processes in the elements. Therefore, the task of determining the dynamic characteristics of one or another element of the system is reduced to compiling its differential equation on the basis of knowledge of the principle of operation and the physical laws underlying the operation of the element. Consider the diagram of the link shown in Fig. 7. The description of the link is a differential equation that relates the output value Y and input X . Let, for example, the relationship between X and Y is expressed by the equation of the 2nd
^ 13. Transient processes. Indicators of the quality of the transition process.
14. Frequency characteristics of systems. In addition to equations, the dynamic properties of linear links can be described by two types of graphical characteristics: transient and frequency. Transient, or time response f (t) is a graph of the change in time of the output value of the link, caused by the supply of a single step action to its input. If a harmonic disturbance is applied to the input of the link, then the study of the dynamics is carried out by frequency methods using frequency characteristics of the main types: amplitude-frequency (AFC), phase-frequency (PFC), amplitude-phase (AFC), real frequency (HF), and imaginary frequency (MF). Frequency characteristics describe steady forced oscillations at the output of the link when applied to its input harmonic effect: It should be noted that for linear links there is an unambiguous relationship between the differential equation, the time and frequency characteristics of the link. This means that, knowing the differential equation (or transfer function) of the link, it is possible to construct the transient or amplitude-phase characteristic of the link and vice versa.
^ 15. Typical links of the ACS (amplifying, aperiodic, integrating, delay, oscillatory). Dynamic characteristics of links. A typical dynamic link of the ACS is an integral part of the system, which is described by a differential equation not higher than the second order. A link usually has one input and one output. According to the dynamic properties, typical links are divided into the following varieties:
10. Operation of automation equipment
Operation of a chamber diaphragm type DKS-10-150
The diaphragm is installed in a pipeline through which a liquid or gaseous substance flows to narrow the local flow.
The workmanship of orifice devices, and especially their correct installation, are of decisive importance for obtaining accurate flow measurement results.
The outer diameter depends on the connecting dimensions of the pipeline.
The narrowing devices are periodically cleaned by opening the valve. Purging is carried out until the ejection of sediments accumulated in the chamber sampling holes from the narrowing device stops.
At the time of purge, the differential pressure gauge is turned off, since when one output of the narrowing device communicates with the atmosphere, the static pressure in the pipeline will act on the second output on the differential pressure gauge many times higher than the pressure limit.
Operation of differential pressure gauge type DM
Before installation, the differential pressure gauge must be filled with the measured liquid. To do this, a rubber hose with a vessel with a capacity of 0.005-0.001 m 3 filled with the measured liquid is alternately put on the valves of the standard and impulse vessels. At least once a day, check the zero point, open the equalizing valve for verification.
If the measurement result is in doubt, a control verification is carried out at the workplace.
Take readings of the measured liquid parameter the next day after turning on the differential pressure gauge, periodically tapping on the connecting impulse lines between the diaphragm and the differential pressure gauge to completely remove air bubbles.
If the differential pressure gauge is designed to measure gas parameters at negative ambient temperatures (up to -30 0 C), its working chambers must be thoroughly blown with dry compressed air.
Pressure gauges must be kept clean.
Operation of the BPS-90P power supply
The current maintenance of the unit consists in daily checking the correctness of its operation using the RMT recording device.
Every month it is necessary to check the reliability of the tightening of the contact screws with the power supply disconnected from the device.
During the overhaul of the process unit, a laboratory check of the output parameters of the unit should be carried out with the preparation of a protocol.
Operation of Metran-100 Converter
All pressure and vacuum instruments provide readings for a long time if normal conditions are met.
The converter consists of a measuring unit and an electronic unit. Converters of various parameters have a unified electronic device and differ only in the design of the measuring unit. Before turning on the converters, you need to make sure that they are properly installed and mounted.
30 minutes after switching on the power supply, check and, if necessary, adjust the output signal values of the converter. Corresponding to the lower value of the measured parameter. The installation is carried out using the "zero" adjustment elements with an accuracy of no worse than 0.2 Dx, without taking into account the error of the controlled means. The control of the output signal value can also be carried out using a DC millivoltmeter connected to terminals 3-4 of the electronic converter. When choosing a millivoltmeter, it must be borne in mind that the voltage drop across it should not exceed 0.1V. Setting the output signal for Metran-100 should be carried out after applying and relieving excess pressure, which is 8-10% of the upper measurement limit.
The Metran-100 transducer withstands the impact of one-sided overload with operating overpressure equally, both from the side of the plus and minus chambers. In some cases, one-sided overload by operating excess pressure of the normal characteristics of the converter. To connect this, it is necessary to strictly follow a certain sequence of operations when turning on the converter in operation, when purging the working chambers and draining the condensate.
Operation of TSP-1088
Each shift is carried out a visual inspection of resistance thermocouples of the TSP-1088 type. At the same time, check that the covers on the heads are tightly closed and that there are gaskets under the covers. The asbestos cord for sealing the wire leads must be tightly pressed with a fitting. In places of possible draft of the product, it should be prevented from getting on the protective fittings and heads of the thermal converter. The presence and condition of the filming layer of thermal insulation is checked, which reduces the heat removal from the sensitive element through the protective cover to the environment. In winter, on outdoor installations, the formation of ice deposits on protective fittings and outgoing wires should not be allowed, as they can lead to damage to resistance temperature converters. At least once a month, inspect and clean the electrical contacts in the heads of the resistance thermocouples.
Maintenance of the device is reduced to the following periodic operations: replacing the chart disk, wiping the glass and cover of the device, filling ink, washing the inkwell and pen, lubricating bearings and rubbing parts of the mechanism. Long-term with frequent movement of the contact along the rheochord can lead to clogging of the contact surface of the rheochord with contact wear products, precipitation, therefore, periodically it is necessary to clean the rheochord with a brush dipped in gasoline or alcohol.
Replacing the chart disc is as follows: remove the pointer, take it by the outer clip and, pressing from yourself to the stop, turn the pointer counterclockwise until it disengages. Then remove the chart disk after removing the spring washer. The ink tank is refilled with special ink. During prolonged use of the device, periodically clean and lubricate the moving parts.
11. Economic calculation
Calculation of funds required for project development
When developing a scientific and technical project, one of the important stages is its feasibility study. It allows you to highlight the advantages and disadvantages of the development, implementation and operation of this software product in terms of economic efficiency, social significance and other aspects.
The purpose of this section is to calculate the cost of developing educational and methodological support for the discipline "Technical means of automation systems".
Organization and planning of work
One of the main goals of work planning is to determine the total duration of their implementation. The most convenient, simple and visual way for these purposes is to use a line chart. To build it, we define events and compile Table 6.
List of events
Table 6
| Event | The code |
| Formulation of the problem | 0 |
| Preparation of terms of reference | 1 |
| Selection and study of literature | 2 |
| Project development | 3 |
| Information base formation | 4 |
| A set of teaching aids | 5 |
| Examination | 6 |
| Analysis of results | 7 |
| Tool testing | 8 |
| Preparation of reporting documentation on the work done | 9 |
| Drawing up an explanatory note | 10 |
| Delivery of the finished project | 11 |
To organize the development process of the tool, the method of network planning and management was used. The method allows you to graphically present a plan for the implementation of upcoming work related to the development of the system, its analysis and optimization, which makes it possible to simplify the solution of tasks, coordinate time resources, labor and the consequences of individual operations.
We will compile a list of works and the correspondence of works to their performers, the duration of these works and summarize them in table 7.
Labor costs for research
Table 7
| Stage | Performers | Duration works, days | Duration works, people - days |
||||
| tmin | tmax | tozh | TRD | TKD | |||
| 1 Problem statement | Supervisor, | 1 | 2 | 1,4 | |||
| Supervisor, | 3 | 4 | 3,4 | ||||
| Student | 10 | 15 | 12 | 100 | 12 | 17 | |
| 4 Project development | Supervisor, | 25 | 26 | 25,4 | |||
| Supervisor, | 28 | 30 | 28,8 | ||||
| Student | 10 | 11 | 1,4 | 100 | 1,4 | 2 | |
| 7 Check | Supervisor, | 3 | 5 | 3,8 | |||
| 8Analysis of results | Supervisor, | 2 | 3 | 2,4 | |||
| Student | 5 | 7 | 5,8 | 100 | 5,8 | 9 | |
| Student | 7 | 10 | 8,2 | 100 | 8,2 | 12 | |
| Student | 4 | 5 | 4,4 | 100 | 4,4 | 7 | |
| 12 Delivery of the finished project | Student | 1 | 2 | 1,4 | 100 | 1,4 | 2 |
| TOTAL | |||||||
Calculation of the complexity of the stages
Various methods of economic planning are used to organize scientific research (R&D). Work carried out in a team with high human costs is calculated using the network planning method.
This work has a small staff of performers (supervisor and software engineer) and is carried out at low cost, so it is advisable to use a linear planning system with a linear graph.
To calculate the duration of the work, we will use the probable method.
Currently, to determine the expected value of the duration of work tzh, a variant based on the use of two estimates tmax and tmin is used.
where tmin is the minimum labor intensity, man/day;
tmax is the maximum labor input, man/day.
The terms tmin and tmax are set by the manager.
To perform the above work, the following specialists will be required -
a) software engineer (IP);
b) scientific supervisor (NR).
Based on Table 7, we will build an employment diagram in Figure 2 and a linear schedule for the performance of work by performers in Figure 2.
Rice. 2 - Employment percentage
To build a line chart, you need to convert the duration of work into calendar days. The calculation is carried out according to the formula:
where TC is the coefficient of calendaring.
(1)
where TKAL - calendar days, TKD=365;
TVD - days off, TVD=104;
TPD - holidays, TPD=10.
The work is carried out by a supervisor and an engineer.
Substituting numerical values into formula (1) we find .
Calculation of the increase in the technical readiness of work
The value of the increase in the technical readiness of the work shows how many percent of the work is done
where tn is the increasing duration of the work from the moment the topic was developed, days;
to is the total duration, which is calculated by the formula.
To determine the specific weight of each stage, we use the formula
where tОЖi is the expected duration of the i-th stage, calendar days;
tO - total duration, calendar days.
| Stages | TKD, days | UVi, % | Gi, % | March | April | May | June | ||||||||
| 1 Problem statement | 3 | 0,89 | 1,91 | ||||||||||||
| 2 Preparation of terms of reference | 6 | 2,16 | 5,73 | ||||||||||||
| 3 Selection and study of literature | 17 | 7,64 | 16,56 | ||||||||||||
| 4 Project development | 43 | 16,17 | 43,94 | ||||||||||||
| 5 Formation of the information base | 46 | 18,34 | 73,24 | ||||||||||||
| 6 Toolkit | 2 | 0,89 | 74,52 | ||||||||||||
| 7 Check | 6 | 2,42 | 78,34 | ||||||||||||
| 8Analysis of results | 4 | 1,52 | 80,86 | ||||||||||||
| 9 Testing the tool | 9 | 3,69 | 86,96 | ||||||||||||
| 10 Registration of reporting documentation on the work done | 12 | 5,22 | 94,26 | ||||||||||||
| 11 Drawing up an explanatory note | 7 | 2,80 | 98,72 | ||||||||||||
| 12 Delivery of the finished project | 2 | 0,89 | 100 | ||||||||||||
Supervisor Student
Rice. 3 - Student and teacher employment schedule
Calculation of development and implementation costs
Planning and accounting for the cost of the project is carried out according to cost items and economic elements. Classification by costing items allows you to determine the cost of individual work.
The initial data for calculating costs is the work plan and the list of required equipment, equipment and materials.
Project costs are calculated according to the following items of expenditure:
1. Salary.
2. Payroll contributions (to the pension fund, social insurance, health insurance).
3. The cost of materials and components.
4. Depreciation expenses.
5. Electricity costs.
6. Other expenses.
7. Total cost.
Payroll preparation
This item of expenditure is planned and takes into account the basic wages of engineering and technical workers directly involved in the development, additional payments for regional coefficients and bonuses.
where n is the number of participants in the i-th work;
Ti - labor costs required to perform the i-th type of work, (days);
Сзпi is the average daily wage of an employee performing the i-th type of work, (rubles/days).
The average daily wage is determined by the formula:
where D is the monthly salary of an employee, defined as D=Z*Ktar;
W - minimum wage;
Ktar - coefficient according to the tariff scale;
Мр - the number of months of work without vacation during the year (with vacation 24 days
Мр=11.2, with a vacation of 56 days Мр=10.4;
K - coefficient taking into account the coefficient on premiums Kpr \u003d 40%, regional coefficient Krk \u003d 30% (K \u003d Kpr + Krk \u003d 1 + 0.4 + 0.3 \u003d 1.7);
F0 - the actual annual fund of the employee's working time, (days).
The minimum wage at the time of development was 1200 rubles.
Then the average monthly salary of a manager who has the thirteenth category on the tariff scale is
D1 \u003d 1200 * 3.36 \u003d 4032.0 rubles
The average monthly salary of an engineer of the eleventh category is
D2 \u003d 1200 * 2.68 \u003d 3216.0 rubles.
The results of calculating the actual annual fund are listed in table 8.
Table 8 - The actual annual fund of working hours of employees
Taking into account the fact that F01 = 247 and F02 = 229 days, the average daily wages will be -
a) supervisor - Szp1 = (4032.0 * 1.7 * 11.2) / 229 = 335.24 rubles;
b) software engineer - Сзп2 = (3216.0 * 1.7 * 10.4) / 247 = 230.20 rubles.
Considering that the supervisor was busy with development for 11 days, and the software engineer for 97 days, we find the basic salary and summarize it in table 9.
Table 9 - Basic salary of employees
| Development participants | Szpi , rub | ti , days | Cosnz/p, rub |
| HP | 411 | 11 | 3687,64 |
| IP | 250,20 | 97 | 22329,4 |
| Total | 27309,04 | ||
Sosnz / n \u003d 11 * 335.24 + 97 * 230.2 \u003d 27309.04 rubles.
Calculation of deductions from wages
Here, contributions to extra-budgetary social funds are calculated.
Deductions from wages are determined by the following formula:
Ssotsf \u003d Ksotsf * Sosn
where Ksotsf is a coefficient that takes into account the amount of deductions from the salary. fees.
The coefficient includes the costs for this item, which are made up of social contributions (26% of the total salary).
The amount of deductions will be 6764.43 rubles.
Calculation of costs for materials and components
Reflects the cost of materials, taking into account transportation and procurement costs (1% of the cost of materials) used in the development of the software tool. Let's summarize the costs of materials and components in table 10
Table 10 - Consumables
| Name of materials | Unit price, rub | Quantity | Amount, rub |
| CD/RW disc | 45,0 | 2 pcs | 90,0 |
| printed paper | 175,0 | 2 pack | 350,0 |
| Printer Cartridge | 450,0 | 1 PC | 450,0 |
| Stationery | 200,0 | 200,0 | |
| Software | 500 | 1 PC | 500,0 |
| Total | 1590,0 | ||
According to table 10, the cost of materials is:
Smat \u003d 90.0 + 350.0 + 450.0 + 200.0 + 500.0 \u003d 1590.0 rubles.
Calculation of depreciation expenses
The article depreciation on used equipment calculates depreciation over the time the work is performed for equipment that is available.
Depreciation deductions are calculated for the time of using the PC according to the formula:
C A = 
,
where Na is the annual depreciation rate, Na = 25% = 0.25;
Tsob - equipment price, Tsob = 45,000 rubles;
FD - actual annual working time fund, FD=1976 hours;
trm - VT operation time when creating a software product, trm = 157 days or 1256 hours;
n is the number of PCs involved, n=1.
SA \u003d (0.25 * 45,000 * 1256) / 1976 \u003d 7150.80 rubles.
Table 11 - Special equipment
| Name | Quantity | Tsob, rub | On, % | FD, hour | SA, rub |
| A computer | 1 PC. | 30000 | 25 | 1976 | 4767,20 |
| a printer | 1 PC. | 15000 | 25 | 1976 | 2383,60 |
| Total: | 7150,80 |
Electricity costs
The amount of electricity required is determined by the following formula:
E \u003d R * Tsen * Fsp, (2)
where P is the power consumption, kW;
Tsen - tariff price for industrial electricity, rub./kWh;
Fsp - the planned time of using the equipment, hour.
E \u003d 0.35 * 1.89 * 1976 \u003d 1307.12 rubles.
Cost estimates of the needs for material and technical resources are determined taking into account wholesale prices and tariffs for energy carriers by means of their direct conversion.
Tariffs for energy carriers in each of the regions of Russia are established and reviewed by decisions of executive authorities in the manner established for natural monopolies.
Calculation of other expenses
The article “other expenses” reflects the expenses for the development of the tool, these include postal, telegraph expenses, advertising, i.e. all those expenses that are not taken into account in the previous articles.
Other expenses amount to 5-20% of the one-time costs for the implementation of the software product and are carried out according to the formula:
Spr \u003d (Sz / n + Smat + Ssotsf + Ca + Se) * 0.05,
Sp \u003d (26017.04 + 1590.0 + 6764.43 + 7150.80 + 1307.12) * 0.05 \u003d 42829.39 rubles.
Project cost
The cost of the project is determined by the sum of articles 1-5 table 12.
Table 12 - Cost estimate
| No. p \ p | Article name | Costs, rub | Note |
| 1 | Wage | 26017,04 | Table 6.5 |
| 2 | Payroll accruals | 6764,43 | 26% of item 1 |
| 3 | Material costs | 1590,0 | Table 6.6 |
| 4 | Depreciation expenses | 7150,80 | Table 6.7 |
| 5 | Electricity costs | 1307,12 | Formula (2) |
| 6 | other expenses | 2102,57 | 5% amount st.1-5 |
| 7 | Total | 44931,96 |
Project efficiency assessment
The most important result of R&D is its scientific and technical level, which characterizes the extent to which the work has been completed and whether scientific and technological progress is being ensured in this area.
Assessment of the scientific and technical level
Based on the estimates of the novelty of the results, their value, the scale of implementation, the indicator of the scientific and technical level is determined by the formula
,
where Ki is the weight coefficient of the i -th sign of the scientific and technical effect;
ni - quantitative assessment of the i -th attribute of the scientific and technical level of work.
Table 13 - Signs of scientific and technical effect
A quantitative assessment of the level of novelty of R&D is determined on the basis of the scores in Table 14.
Table 14 - Quantification of the level of novelty of R&D
| Novelty level Developments | Points | |
| Fundamentally new | Research results open a new direction in this field of science and technology | 8 - 10 |
| New | Known facts, patterns are explained in a new way or for the first time | 5 - 7 |
| Relatively new | Research results systematize and summarize the available information, determine the ways for further research | 2 - 4 |
| Table 14 continued | ||
| Novelty level Developments | Characteristics of the level of novelty | Points |
| Novelty level Developments | Characteristics of the level of novelty | Points |
| Traditional | The work was performed according to the traditional method, the results of which are for informational purposes. | 1 |
| No novelty | The result was obtained, which was previously known | 0 |
The theoretical level of the obtained results of research is determined on the basis of the scores given in table 15.
Table 15 - Quantification of the theoretical level of R&D
| Theoretical level of the obtained results | Points |
| Establishment of the law; development of a new theory | 10 |
| Deep development of the problem: multidimensional analysis of relationships, interdependence between facts with the presence of an explanation | 8 |
| 6 | |
| Elementary analysis of relationships between facts with the presence of a hypothesis, a simplex forecast, a classification, an explanatory version or practical recommendations of a private nature | 2 |
| Description of individual elementary facts (things, properties and relationships); presentation of experience, observations, measurement results | 0,5 |
The possibility of realizing scientific results is determined on the basis of the scores in Table 16.
Table 16 - The possibility of implementing scientific results
Note: Time and scale scores are added together.
The results of the feature scores are shown in Table 17.
Table 17 - Quantification of the signs of research
| Sign of the scientific and technical effect of research | Characteristic sign of research | Ki | Pi |
| 1 novelty level | systematize and summarize information, determine ways for further research | 0,6 | 1 |
| 2 Theoretical level | Development of a method (algorithm, program of activities, device, substance, etc.) | 0,4 | 6 |
| 3 Possibility of implementation | Implementation time during the first years | 0,2 | 10 |
| Implementation scale - enterprise | 2 |
Using the initial data on the main features of the scientific and technical effectiveness of R&D, we determine the indicator of the scientific and technical level:
Ht \u003d 0.6 1 + 0.4 6 + 0.2 (10 + 2) \u003d 5.4
Table 18 - Assessment of the level of scientific and technical effect
In accordance with table 18, the level of scientific and technical effect of this work is medium.
The cost estimate for the development of this system and the cost estimate for its annual operation are calculated. The cost of creating the system is 44931.96 rubles.
Calculation of funds required for implementation
Capital investments in modernization are, first of all, the cost of electrical equipment and the cost of installation work.
The estimate is a document that determines the final and marginal cost of the project. The estimate serves as the initial document of the capital investment, which determines the costs necessary to complete the full scope of the necessary work.
The initial materials for determining the estimated cost of improving the facility are project data on the composition of equipment, the volume of construction and installation work; price lists for equipment and building materials; norms and prices for construction and installation works; freight rates; overhead rates and other regulatory documents.
The calculation is made on the basis of contractual prices. Initial data and costs are summarized in tables.
After the approval of the technical project, a working draft is developed, that is, working drawings, on the basis of which the final cost is determined.
Equipment costs
Table 4
| No. p / p | Device name | Qty | Price | Total |
| 1 | Metran-100 | 23 | 15000 r. | 345000 r. |
| 2 | BPS-90P/K | 23 | 14000 r. | 322000 r. |
| 3 | RS-29 | 10 | 5000 r. | 50000 r. |
| 4 | U29.3M | 10 | 6000 r. | 60000 r. |
| 5 | Siemens SIPART | 10 | 10000 r. | 100000 r. |
| 6 | RMT-69 | 5 | 50000 r. | 500000 r. |
| 7 | Other (cables, connectors, cables, transport costs) | 50000 r. | 50000 r. | |
| total | 81 | 1427000 r. |
payroll fund
Let's determine the number of persons required for the work, and summarize this information in a table:
Workers involved in modernization and their salary.
Table 5
| Position | Monthly salary | Number of months | Employee's salary for the whole time of work |
| Chief Engineer | 30000 | 1 | 30000 |
| Chief metrologist | 30000 | 2 | 60000 |
| Deputy chief metrologist | 25000 | 2 | 50000 |
| Section chief | 15000 | 4 | 60000 |
| Mechanic of instrumentation and automation | 10000 | 1 | 10000 |
| Mechanic of instrumentation and automation | 10000 | 1 | 10000 |
| Mechanic of instrumentation and automation | 10000 | 1 | 10000 |
| Mechanic of instrumentation and automation | 10000 | 1 | 10000 |
| An electrician | 10000 | 1 | 10000 |
| locksmith | 10000 | 1 | 10000 |
| Operator (operator) | 10000 | 1 | 10000 |
| Premium 30% | 81000 | ||
| total | 351000 |
The cost of installation work and the wages of the people who carried out all the calculations, i.e. engineering and technical workers amounted to 351,000 rubles.
On the example of one device - Metran-100, the amount of labor costs is shown. We take into account that in the place where it should be, there is another sensor that needs to be upgraded.
This calculation did not include the time required for the delivery of welding equipment, preparation for work, etc.
The amount of labor for Metran-100
Table 6
| No. p / p | Action name | Number of minutes |
| 1 | Dismantling wires, disconnecting pulses, unscrewing the device | 30 |
| 2 | Cable pulling, including through the terminal box | 120 |
| 3 | Digesting fasteners, sizing | 60 |
| 4 | Wiring, connecting impulses, screwing the device | 30 |
| 5 | Marking | 30 |
| Total | 270 minutes or 4.5 hours |
The following table shows the labor costs for some jobs.
Labor costs for some devices
Table 7
| Job Title | List of required actions | number of people for one operation | Number of man-hours |
| Installation of the DCS | disassembly, replacement, assembly, tightening | 2 | 2 |
| Installation of Metran-100 | Dismantling the previous device, adjusting the connecting impulses, connecting adapters, | 2 | 4,5 |
| Installation of BPS90 | Preparing the location, connecting the wires, setting up | 1 | 3 |
| Installation of a wave level gauge | Dismantling of the old level gauge, installation of a new location using welding equipment, connection of a new device, connection of wires, adjustment. | 2 | 5 |
| Mounting the Siemens positioner | Dismantling the old positioner, attaching a new one, setting | 1 | 5 |
It can be seen that a lot of time is spent on the installation of imported devices. This is due to the fact that the devices are new and there is no experience with them. In fact, installation will take much longer due to unforeseen circumstances, lack of experience, and other circumstances.
The design process takes much more time than installation, because every detail needs to be thought through, because the boiler plant is a very important link in the monomer production process. That is why designing takes most of the time. All works are divided into parts and summarized in the table.
Work plan
Table 8
| List of performed works | Performers | Number of people | Amount of days |
| Familiarization with the terms of reference, development of an action plan, distribution of work | Engineer, chief metrologist, deputy chief metrologist | 3 | 14 days |
| Development of the scheme, technical and economic calculation of the scheme, ordering materials and parts | Engineer, chief metrologist, deputy chief metrologist, head of section | 4 | 14 days |
| Preparation of the place of work, organizational work | Deputy chief metrologist, head of section, instrumentation and instrumentation fitter | 5 | 14 days |
| After the boiler is stopped for overhaul, the main work begins | |||
| Dismantling of old equipment | Mechanic of instrumentation and automation, electrician | 5 | 7 days |
| Installation of equipment (in parallel on all sites) | Mechanic of instrumentation and automation, electrician | 5 | 20 days |
| Checking the operation of equipment, operation of settings. | Mechanic of instrumentation and automation, electrician | 5 | 2 days |
| Delivery of the finished scheme, running-in with imitation of working situations | Chief engineer, head of section, apparatchik, instrumentation and automation fitter, | 11 | 1 day |
| Boiler plant start-up | operator, instrumentation fitter, electrician | 7 | 1 day |
| Eliminate minor bugs | Mechanic of instrumentation and automation, electrician | 5 | 1 day |
Total costs for the re-equipment of the boiler plant: wage fund 351,000 rubles + costs for the purchase of equipment 1,427,000 rubles = 1,778,000 rubles.
Economic effect from implementation
The introduction of automated process control systems of this kind, as world practice shows, leads to savings in fuel burned by 1-7%.
1. With a natural gas consumption of 500 m3/hour on one operating boiler, this savings can be 5-35 m3/hour or 43800-306600 m3/year. At a price of 2,500 rubles per 1,000 m3, the economic effect will be from 40,646 rubles per year. But since gas is constantly becoming more expensive, this amount will increase.
2. The same savings occur in the reduction of the cost of transport rail delivery. If we take an average saving of 150,000 m 3 /year, and a tank capacity of 20,000 m 3, then transportation of almost 8 tanks is saved. The cost of diesel fuel for a diesel locomotive, depreciation, wages for drivers, etc. is about 1,000 rubles per 100 kilometers per 1 tank. The gas station is located at a distance of 200 km, so the cost will be about 20,000 rubles. But given the cost of fuel, these costs can increase significantly in a year.
Those. net payback will occur in 20 years. Given the rise in fuel prices and wage increases, this period may be reduced to 5 years.
But if the plant is stopped or even destroyed by old equipment that has failed, the losses can amount to millions of rubles.
12. Safety and environmental friendliness of work
Analysis of harmful and dangerous factors
The production of monomers, which includes a distillation unit for aromatic hydrocarbons, is associated with the use and processing of large quantities of flammable substances in a liquefied and gaseous state. These products may form explosive mixtures with air. Of particular danger are low places, wells, pits, where accumulation of explosive mixtures of hydrocarbons with air is possible, since hydrocarbon vapors are generally heavier than air.
The most dangerous are those places that are considered difficult to control by external inspection, where there may be increased gas contamination, and which, due to the nature of the work, the apparatchik visits infrequently
Particularly dangerous factors during the operation of this unit are:
High pressure and temperature during the operation of the equipment of the installation for obtaining high-pressure steam;
Formation of explosive concentrations of natural gas (methane) during ignition and operation of the boiler;
The possibility of obtaining chemical burns and poisoning when preparing a solution of hydrazine hydrate and ammonia water.
The most dangerous places
1. Fuel gas distribution system.
2. High and medium pressure steam lines.
3. Steam reduction units.
4. Department for the preparation of reagents.
5. Wells, manholes, low places, pits, where accumulation of explosive mixtures of hydrocarbons with air is possible.
The technological process of generating high-pressure superheated steam is associated with the presence of explosive fuel gas, fuel gas combustion products, as well as high pressure and high temperatures of steam and water. In addition, toxic substances such as hydrazine hydrate, ammonia, trisodium phosphate are used for water treatment.
The main conditions for the safe conduct of the process of obtaining steam and generating electricity are:
Compliance with the norms of the technological regime;
Compliance with the requirements of the instructions for the workplace, OHS rules during operation, start-up and shutdown of individual pieces of equipment and the entire boiler room;
Carrying out timely and high-quality repairs of equipment;
Carrying out, according to the schedules, control checks of instrumentation and automation, alarm and interlock systems, safety devices.
During operation of the auxiliary boiler room, equipment and communications are under pressure from combustible gases, water and steam. Therefore, in case of violation of the normal technological regime, as well as violations of densities in the joints of apparatuses and units, the following may occur:
Gas breakthrough followed by fire and explosion;
Formation of local explosive concentrations of natural gas;
Poisoning due to the presence of gases containing components (CH 4, NO 2, CO 2, CO);
Poisoning with reagents for corrective treatment of feed and boiler water, in case of non-compliance with the rules for handling them and neglecting personal protective equipment;
Thermal burns in case of breaks in pipelines of flue gases, water vapor and condensate;
Electric shock due to malfunctions of electrical equipment and electrical networks, as well as as a result of non-compliance with electrical safety rules;
Mechanical injuries in case of violations in the maintenance of machines, mechanisms and other equipment;
Ignition of lubricating and sealing oils and cleaning materials in case of non-compliance with the rules for their storage and violation of fire safety standards;
Unsatisfactory purging of pipelines and apparatuses, which can cause the formation of explosive concentrations and, under certain conditions, an explosion;
Hazards associated with the operation of equipment operating under high pressure, work in pits, wells, vessels and handling hazardous substances (ammonia, hydrazine hydrate).
Industrial sanitation
Microclimate. For normal and high-performance work in industrial premises, it is necessary that the meteorological conditions (temperature, humidity and air velocity), i.e. microclimate, were in certain proportions.
The required air condition of the working area is ensured by the implementation of certain measures, including:
Mechanization and automation of production processes and their remote control;
The use of technological processes and equipment that exclude the formation of harmful substances or their entry into the working area;
Reliable sealing of equipment containing harmful substances;
Protection from sources of thermal radiation;
Ventilation and heating device;
The use of personal protective equipment.
The air temperature in laboratories ranges from 20 to 25 degrees.
Lighting: Lighting in the premises complies with the regulations. All objects with which you often have to work are well lit. In the main hall there is a sufficient number of window openings, which is necessary during the day. Workers who have to deal with working in dark places (electricians, instrumentation fitters) have special lights - miners, which provide sufficient illumination of any detail.
Noise and vibration. The main noise control measures are:
Eliminate or reduce the causes of noise at its source;
Isolation of the noise source from the environment by means of sound insulation and sound absorption;
Protection against the action of ultrasound is performed in the following ways:
The use of higher operating frequencies in equipment, for which the permissible sound pressure levels are higher;
The use of sources of ultrasonic radiation in a soundproof design such as casings. Such casings are made of sheet steel or duralumin (1 mm thick) with rubber or ruberoid pasting, as well as getinax (5 mm thick). The use of casings reduces the level of ultrasound by 60 ... 80 dB;
Shielding;
In the main workshop, the noise level reaches 100 dB. When working, workers use earplugs or simply plug their ears with their fingersJ.
Safety
A worker allowed to operate a boiler house must be trained in a special program and pass an exam by a qualification commission. Before admission to work, each entering the workshop must be familiarized with the head of the workshop or his deputy for safety, with the general rules for conducting work, after which the foreman instructs the entrant at the workplace.
At the same time, the worker must be familiar with the features of work at this workplace, with equipment and tools. After the briefing at the workplace, the worker is allowed to internship and training at the workplace under the guidance of an experienced worker, about which an order is issued in the workshop. A worker should be allowed to work independently only after the end of the internship period established for a given workplace and after testing knowledge by a commission appointed by order for the workshop. The worker is obliged to firmly know the dangerous moments of his workplace and methods for eliminating them.
Persons hired to service thermal and mechanical equipment must undergo a preliminary medical examination and subsequently undergo it periodically within the time limits established for the personnel of the power enterprise.
Persons servicing the equipment of workshops of power plants and heating networks must know and comply with the safety regulations applicable to their position. personnel using electrical protective equipment in their work must know and follow the rules for the use and testing of protective equipment used in electrical installations. All personnel must be provided with overalls, footwear and other protective equipment in accordance with the current standards in accordance with the characteristics of the work performed, and must use them during work. All production personnel should be practically trained in the methods of releasing a person who has been under voltage from the action of an electric current and providing him with first aid, as well as the methods of providing first aid to victims in other accidents. Each employee must clearly know and comply with the requirements of the fire safety rules and the emergency regime at the facility, and not allow actions that could lead to a fire or fire.
Smoking is prohibited in the installation area, with the exception of designated smoking areas equipped with special fire fighting equipment
During the operation of boilers, the reliability and safety of the operation of all main and auxiliary equipment must be ensured; the possibility of achieving the nominal productivity of boilers, parameters and water quality, economical mode of operation. It is forbidden to work on process equipment if the pipeline to which the impulse lines are connected remains under pressure. The absence of pressure in the disconnected impulse line must be checked by connecting it to the atmosphere. It is forbidden to work on existing electrical equipment without the use of electrical protective equipment. When working without the use of electrical protection equipment, the electrical equipment must be turned off.
Safety in emergency situations.
The most probable emergency in the boiler room is a fire, due to high temperatures, the use of gas and a large amount of electrical equipment.
The person responsible for the fire safety of the boiler house is the foreman, who is obliged to monitor the implementation of fire safety requirements. All production sites are provided with fire-fighting equipment and primary fire extinguishing equipment.
To prevent emergency situations in the boiler room, it is prohibited:
1. store flammable and combustible substances;
2. block up passages between boilers, vestibules and approaches to fire-fighting equipment;
3. kindling boilers without ventilation of furnaces and gas ducts, as well as using liquid fuel for ignition;
4. check the tightness of gas pipelines with an open fire;
5. use faulty appliances and power supply;
6. use fire extinguishing agents for other purposes.
In the event of a fire, service personnel must:
1. Immediately call the fire brigade by phone.
2. start extinguishing the fire with the available fire extinguishing equipment, without stopping monitoring the boilers.
Measures for environmental protection
Environmental protection is a global problem. Measures for environmental protection are aimed at preserving and restoring natural resources, rational use of natural resources and preventing the harmful effects of the results of economic activities of society on nature and human health. The essence of environmental protection lies in the establishment of a constant dynamic harmony between a developing society and nature, serving it both as a sphere and a source of life. Every day, millions of tons of various gaseous wastes are thrown out, water bodies are polluted with billions of cubic meters of sewage. When solving the problem of reducing environmental pollution, the main thing is the creation and implementation of fundamentally new, waste-free technological processes.
In the boiler house, the products formed during combustion transfer part of the heat to the working fluid, and the other part, together with the combustion products (CO2, CO, O2, NO), is released into the atmosphere. In the atmosphere, gaseous combustion products as a result of secondary chemical reactions with the participation of oxygen and water vapor form acids, as well as various salts. Air pollutants, together with precipitation, fall on the surface of soil and water bodies, causing their chemical pollution. To reduce the emission of harmful substances and environmental pollution, sealed technological equipment, gas and dust collecting installations, high pipes are installed in boiler rooms.
Automation of the boiler house ensures economical use of fuel, as well as the completeness of its combustion. The project controls the O2 content in the flue gases and regulates the air flow with a correction for the oxygen content in the flue gases, which makes it possible to ensure the complete combustion of the fuel.
Conclusion
In this thesis work, the issues of automation of the boiler plant for the production of monomers were considered.
Since all equipment is morally and physically obsolete, the relevance of this issue is very high.
In the course of this work, devices of imported and domestic production were considered. It was revealed that some domestic devices occupy a worthy place in the market of automation and electronics devices. Since the cost of domestic devices is much lower than imported counterparts, and the reliability, functionality and other parameters are the same, preference was given to them. The only exceptions are Siemens positioners and Rosemount positioners.
Each modernization must be economically justified, therefore, an economic calculation of the cost of the entire modernization was carried out. The total cost was 1,778,000 rubles. For the production of monomers, and for the entire enterprise as a whole, this is a lot of money, but the damage from a sudden equipment failure can be much higher.
At the end of the thesis, in the part “Requirements for labor protection”, the main measures and requirements that must be met for the safe performance of work were derived.
Conclusion
The possibility of automation of boiler plant for monometer producing was reviewed in this qualified paper.
Since all the equipment morally and physically became out of date the importance of this issue is very high.
In the course of this paper the import and domestic producing devices were reviewed. During this reviewing it was clear up that some domestic devices take the worth place in the market of automation and electronics devices. As the price of domestic devices is much lower than import counterpart and reliability, functionality and other parameters are the same, so the preference was given to them. The exclusions were the positioners of Siemens and the gages of Rosemount.
Every enhancement should be economically proven, that is why economical calculation of the price of all enhancements was carried. The total cost is 1778000 rubles. For producing monometers and for the whole enterprise it’s big money, but the loss from the unexpected breakdown of equipment can be much higher.
At the end of the qualified paper in the part "Protection of labor request" the main actions and requirements were introduced, which should be followed for the safe work.
Literature
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4. Itskovich A.M. Boiler installations. M.: Nasits, 1958, 226 p.
5. Kazmin P.M. Installation, adjustment and operation of automatic devices for chemical production. Moscow: Chemistry, 1979, 296 p.
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7. Kupalov M.V. Technical measurements and instruments for chemical industries. M.: Mashinostroenie, 1966.
8. Lokhmatov V.M. Automation of industrial boilers. Leningrad: Energy, 1970, 208 p.
9. Installation of measuring instruments and automation. Ed. Ktoeva A.S. Moscow: Energoizdat, 1988, 488 p.
10. Murin T.A. Thermotechnical measurements. M.: Energy, 1979. 423 p.
11. Mukhin V.S., Sakov I.A. Control devices and means of automation of thermal processes. M.: Higher school. 1988, 266 p.
12. Pavlov I.F., Romankov P.P., Noskov A.A. Examples and tasks in the course of processes and apparatuses of chemical technologies. Moscow: Chemistry, 1976.
13. Devices and means of automation. Catalog. Moscow: Informpribor, 1995, 140 p.
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16. Rappoport B.M., Sedanov L.A., Yarkho G.S., Rudintsev G.I. Devices for automatic regulation and protection of boiler houses of mining enterprises. Moscow: Nedra, 1974, 205 p.
17. Stollker E.B. Reference book for the operation of gas boilers. L.: Nedra, 1976. 528 p.
18. Feuershtein V.S. Reference book on the automation of boiler rooms. Moscow: Energy, 1972, 360 p.
19. Fanikov V.S. , Vitaliev V.P. Automation of heating points. Reference manual. M.: Energoizdat, 1989. 256 p.
20. Shevtsov E.K. Reference book on verification and adjustment of devices. L.: Tekhnika, 1981, 205 p.
... ± 0.035 V. The error in determining the volumetric fuel consumption does not exceed 60 10-6 m3/s. Thus, the use of the developed method for measuring fuel consumption significantly improves the quality of control along the “Solid fuel consumption” loop, which saves energy and increases the efficiency of boiler plants. etc. Automation of production processes and automated control systems
When developing and implementing automation systems for chemical processes and industries, the same approaches are used that are used in other industries. At the same time, the conditions of chemical production and the production process itself have a number of features, which we will consider in this article.
A typical block diagram of chemical processes is as follows:
raw material → raw material preparation → chemical synthesis → product isolation → product
At the input of any chemical process, there is always a feedstock that must be stored and, to some extent, prepared for further processing. The next step is the production process itself. At this stage, a chemical product is obtained from pre-prepared raw materials using special apparatus (mixers, separators, columns, reactors, etc.) and / or substances (catalysts). Typically, devices for obtaining one product are combined into technological installations. Further, the resulting product undergoes separation and purification processes. Automation of chemical production can reduce the cost of each of these stages.
Consider some of the features of chemical industries.
Continuity
Basically, all chemical industries are characterized by continuity, i.e. the technological process is carried out in a steady state. There are also chemical industries with a periodic nature, where the sequence of operations for loading and preparing raw materials, chemical synthesis, isolation and purification of products has a finite duration.
The continuity of chemical production imposes special requirements on the development of automation systems, such as redundancy of field equipment, controllers, communication channels, workstations and servers, organization of backup power for equipment, etc.
distribution
One of the features of chemical production is the placement of technological installations and equipment in open areas, which occupy a large area. A typical chemical plant is located on an area from a few square kilometers to several tens of square kilometers. All this must be taken into account when designing automation systems. As a rule, in such cases, geographically distributed automated systems are used. High-speed communication channels, including those based on optical lines, are also of great importance. not all interfaces and communication protocols provide an acceptable data exchange rate over long distances.
During the work of chemical industry enterprises, various hazardous substances are constantly present in the working area, technological processes in the apparatuses take place at high 
pressures and temperatures. This is especially true for petrochemical, cracking, resin and carbon production enterprises. All this imposes increased requirements on the automation systems of chemical processes. As a rule, control cabinets with controllers, workplaces and servers are placed in special rooms with forced supply of purified air. Field equipment is selected in a special design in accordance with the operating conditions. All this helps to reduce the harmful effects of hazardous substances on automation equipment.
In order to reduce the harmful effects of hazardous substances on operational personnel, the automation of chemical production should also include automated warning systems for the presence in the working area of maximum concentrations of substances hazardous to humans.
Explosiveness
Most chemical plants, and especially petrochemical plants, have hazardous areas. The use of conventional automation tools in such cases is prohibited. Explosion-proof automation tools are used. Pneumatic actuators are widely used in such areas. The level of explosion protection of automation equipment must correspond to the explosion hazard class of the zone where it will be installed.
Large energy consumption
Chemical production, as a rule, is characterized by significant energy consumption. Depending on the type of production, it can be electricity, coal, fuel oil, natural gas, steam. At large enterprises, electricity and steam are generated at their own thermal power plants. In this regard, the problem of accounting for energy carriers is acute. Therefore, the automation of chemical production should include an automated system for the integrated accounting of energy carriers.
Conclusion
As already mentioned, the automation of chemical production occurs in the same way as in other industries.
Automation of chemical production allows you to improve product quality, reduce costs, reduce the number of operating personnel, increase labor productivity and improve production culture.
But the conditions of chemical production and the production process itself have a number of features that were discussed in this article.
Enterprises "Automated Systems", which has extensive experience in the automation of chemical production, will help you automate your chemical production, develop and coordinate all the necessary design and estimate documentation, develop software, perform installation and commissioning.
annotation
The purpose of this course project is to acquire practical skills in the analysis of the technological process, the choice of automatic control tools, the calculation of measuring circuits of instruments and controls, as well as teaching the student independence in solving engineering and technical problems of constructing automatic control circuits for various technological parameters.
Introduction
Automation is the use of a set of tools that allow production processes to be carried out without the direct participation of a person, but under his control. Automation of production processes leads to an increase in output, a reduction in cost and an improvement in product quality, reduces the number of maintenance personnel, increases the reliability and durability of machines, saves materials, improves working conditions and safety.
automation and monitoring of their action. If automation facilitates the physical labor of a person, then automation aims to facilitate mental labor as well. The operation of automation equipment requires high technical qualifications from the service personnel.
In this case, the generation of heat and electricity at any time must correspond to the consumption (load). Almost all operations at thermal power plants are mechanized, and transient processes in them develop relatively quickly. This explains the high development of automation in the thermal power industry.
Automating parameters provides significant benefits:
1) ensures a decrease in the number of working personnel, i.e., an increase in the productivity of its labor,
3) increases the accuracy of maintaining the parameters of the generated steam,
Steam generator automation includes automatic control, remote control, process protection, thermal control, process interlocks and alarms.
Automatic control ensures the course of continuously occurring processes in the steam generator (water supply, combustion, steam overheating, etc.)
Remote control allows on-duty personnel to start and stop the steam generator set, as well as switch and regulate its mechanisms at a distance, from the console where the control devices are concentrated.
flowing in the steam generator installation, or are connected to the measurement object by service personnel or an information computer. Thermotechnical control devices are placed on panels, control panels, as convenient as possible for observation and maintenance.
eliminate incorrect operations during maintenance of the steam generator set, ensure shutdown of the equipment in the required sequence in the event of an accident.
emergency condition of the steam generator and its equipment. Sound and light alarms are used.
The operation of boilers must ensure reliable and efficient generation of steam of the required parameters and safe working conditions for personnel. To fulfill these requirements, operation must be carried out in strict accordance with legal provisions, rules, norms and guidelines, in particular, in accordance with the “Rules for the Design and Safe Operation of Steam Boilers” of Gosgortekhnadzor, “Rules for the Technical Operation of Power Plants and Networks”, “Rules for the Technical operation of heat-using installations and heating networks ".
A steam boiler is a set of units designed to produce water vapor. This complex consists of a number of heat exchange devices interconnected and serving to transfer heat from the products of fuel combustion to water and steam. The initial carrier of energy, the presence of which is necessary for the formation of steam from water, is fuel.
The main elements of the workflow carried out in the boiler plant are:
1) the process of fuel combustion,
2) the process of heat exchange between the products of combustion or the burning fuel itself with water,
3) the process of vaporization, consisting of heating water, its evaporation and heating the resulting steam.
During operation, two flows interacting with each other are formed in the boiler units: the flow of the working fluid and the flow of the coolant formed in the furnace.
As a result of this interaction, steam of a given pressure and temperature is obtained at the outlet of the object.
One of the main tasks arising during the operation of the boiler unit is to ensure equality between the produced and consumed energy. In turn, the processes of vaporization and energy transfer in the boiler unit are uniquely related to the amount of substance in the flows of the working fluid and coolant.
Fuel combustion is a continuous physical and chemical process. The chemical side of combustion is the process of oxidation of its combustible elements with oxygen. passing at a certain temperature and accompanied by the release of heat. The intensity of combustion, as well as the efficiency and stability of the fuel combustion process, depend on the method of supplying and distributing air between fuel particles. Conventionally, the process of fuel combustion is divided into three stages: ignition, combustion and afterburning. These stages generally proceed sequentially in time, partially overlapping one another.
The calculation of the combustion process usually comes down to determining the amount of air in m3 required for the combustion of a unit mass or volume of fuel, the quantity and composition of the heat balance and determining the combustion temperature.
The value of heat transfer lies in the heat transfer of thermal energy released during the combustion of fuel, water, from which it is necessary to obtain steam, or steam, if it is necessary to increase its temperature above the saturation temperature. The process of heat transfer in the boiler goes through water-gas-tight heat-conducting walls, called the heating surface. Heating surfaces are made in the form of pipes. Inside the pipes there is a continuous circulation of water, and outside they are washed by hot flue gases or perceive thermal energy by radiation. Thus, all types of heat transfer take place in the boiler unit: thermal conductivity, convection and radiation. Accordingly, the heating surface is divided into convective and radiation. The amount of heat transferred through a unit of heating area per unit of time is called the thermal stress of the heating surface. The voltage value is limited, firstly, by the properties of the material of the heating surface, and secondly, by the maximum possible intensity of heat transfer from the hot coolant to the surface, from the heating surface to the cold coolant.
The intensity of the heat transfer coefficient is the higher, the higher the temperature difference of the heat carriers, the speed of their movement relative to the heating surface and the higher the surface cleanliness.
lies in the fact that individual molecules of the liquid, located near its surface and having high speeds, and therefore, greater kinetic energy compared to other molecules, overcoming the force effects of neighboring molecules, which create surface tension, fly out into the surrounding space. As the temperature increases, the rate of evaporation increases. The reverse process of vaporization is called condensation. The liquid formed during condensation is called condensate. It is used to cool metal surfaces in superheaters.
The steam generated in the boiler unit is divided into saturated and superheated. Saturated steam, in turn, is divided into dry and wet. Since superheated steam is required at thermal power plants, a superheater is installed to superheat it, in which heat obtained from the combustion of fuel and exhaust gases is used to superheat the steam. The resulting superheated steam at a temperature of T=540 C and a pressure of P=100 atm. goes to technological needs.
The principle of operation of the boiler plant is to transfer the heat generated during the combustion of fuel, water and steam. In accordance with this, the main elements of boiler plants are the boiler unit and the combustion device. The combustion device is the most economical way for fuel and the conversion of the chemical energy of the fuel into heat. The boiler unit is a heat exchange device in which heat is transferred from the combustion products of fuel to water and steam. Steam boilers produce saturated steam. However, during transportation over long distances and use for technological needs, as well as at thermal power plants, the steam must be superheated, since in a saturated state, when cooled, it immediately begins to condense. The boiler includes: a furnace, a superheater, a water economizer, an air heater, brickwork, a frame with stairs and platforms, as well as fittings and a headset. Auxiliary equipment includes: draft and feed devices, water treatment equipment, fuel supply, as well as instrumentation and automation systems. The boiler plant also includes:
1. Tanks for collecting condensate.
2. Plants for chemical water treatment.
3. Deaerators for removing air from chemically treated water.
4. Feed water pumps.
5. Installations for gas pressure reduction.
6. Fans for supplying air to the burners.
Smoke exhausters for removing flue gases from furnaces. Consider the process of obtaining steam with specified parameters in a gas-fired boiler house. Gas from the gas distribution point enters the boiler furnace, where it burns, releasing the appropriate amount of heat. The air necessary for fuel combustion is blown by a blower fan into the air heater located in the last flue of the boiler. To improve the process of fuel combustion and increase the efficiency of the boiler, the air can be preheated by flue gases and an air heater before being fed into the furnace. The air heater, perceiving the heat of the flue gases and transferring it to the air, firstly, reduces the heat loss with the flue gases, and secondly, improves the conditions for fuel combustion by supplying heated air to the boiler furnace. This increases the combustion temperature and the efficiency of the installation. Part of the heat in the furnace is given off to the evaporative surface of the boiler - the screen covering the walls of the furnace. Flue gases, having given up part of their heat to the radiation heating surfaces located in the combustion chamber, enter the convective heating surface, cool down and are removed by a smoke exhauster through the chimney into the atmosphere. Water continuously circulating in the screen forms a steam-water mixture, which is discharged into the boiler drum. In the drum, the steam is separated from the water - the so-called saturated steam is obtained, which enters the main steam line. The flue gases leaving the furnace are washed by the serpentine economizer, in which the feed water is heated. Heating water in the economizer is expedient from the point of view of fuel economy. A steam boiler is a device that operates under difficult conditions - at high temperature in the furnace and significant steam pressure. Violation of the normal operation of the boiler installation can cause an accident. Therefore, each boiler plant has a number of devices that give a command to stop the fuel supply to the boiler burners under the following conditions:
1. When the pressure in the boiler rises above the permissible level;
2. When the water level in the boiler drops;
3. With a decrease or increase in pressure in the fuel supply line to the boiler burners;
4. When the air pressure in the burners decreases;
To control the equipment and control its operation, the boiler room is equipped with control and measuring devices and automation devices.
1. Reducing the pressure of the gas coming from the hydraulic fracturing;
2. Reducing the vacuum in the boiler furnace;
3. Increasing the steam pressure in the boiler drum;
5. Extinction of the torch in the furnace.
3. The choice of means for measuring technological parameters and their comparative characteristics
3.1 Selection and justification of control parameters
The choice of controlled parameters provides obtaining the most complete measurement information about the technological process, about the operation of the equipment. Temperature and pressure are controlled.
4. Selection of monitoring and control parameters
The control system must ensure the achievement of the control goal due to the specified accuracy of technological regulations in any production conditions, while observing the reliable and trouble-free operation of the equipment, the requirements of explosion and fire hazard.
The purpose of power consumption management is: reduction of specific power consumption for production; rational use of electricity by technological services of divisions; proper planning of electricity consumption; control of consumption and specific costs of electricity per unit of output in real time.
The main task in the development of the control system is the selection of the parameters involved in the control, that is, those parameters that need to be controlled, regulated, and by analyzing the change in the values of which it is possible to determine the pre-emergency state of the technological control object (TOU).
Those parameters are subject to control, according to the values of which the operational control of the technological process (TP), as well as the start and stop of technological units, is carried out.
4.1 Pressure measurement
pressure-vacuum meters; pressure gauges (for measuring small (up to 5000 Pa) excessive pressures); draft gauges (for measuring small (up to hundreds of Pa) discharges); thrust gauges; differential pressure gauges (to measure the pressure difference); barometers (to measure atmospheric pressure). According to the principle of operation, the following devices for measuring pressure are distinguished: liquid, spring, piston, electric and radioactive.
For measuring gas and air pressure up to 500 mm w.c. Art. (500 kgf/m2) use a glass U-shaped liquid manometer. The pressure gauge is a glass U-shaped tube attached to a wooden (metal) panel, which has a scale with divisions in millimeters. The most common pressure gauges with scales 0-100, 0-250 and 0-640 mm. The pressure value is equal to the sum of the heights of the liquid levels lowered below and raised above zero.
In practice, pressure gauges with a double scale are sometimes used, in which the division value is halved and the numbers from zero go up and down with an interval of 20:0-20-40-60, etc., while there is no need to indicate the heights of the liquid levels , it is enough to measure the pressure gauge readings at the level of one knee of the glass tube. Measurement of small pressures or vacuums up to 25 mm w.c. Art. (250 Pa) single-tube or U-tube liquid pressure gauges lead to large errors when reading the measurement results. To increase the scale of the readings of a single-tube manometer, the tube is tilted. This is the principle of operation of TNZh liquid thrust gauges, which are filled with alcohol with a density of r=0.85 g/cm3. in them, liquid from a glass vessel is forced out into an inclined tube, along which there is a scale graduated in mm of water. Art. When measuring vacuum, the impulse is connected to a fitting that is connected to an inclined tube, and when measuring pressure, to a fitting that is connected to a glass vessel. Spring gauges. To measure pressure from 0.6 to 1600 kgf/cm2, spring pressure gauges are used. The working element of the manometer is a curved tube of elliptical or oval section, which is deformed under pressure. One end of the tube is sealed, and the other is connected to a fitting, which is connected to the measured medium. The closed end of the tube is connected through a rod to a gear sector and a central gear wheel, on the axis of which an arrow is mounted.
The pressure gauge is connected to the boiler through a siphon tube in which steam is condensed or water is cooled and the pressure is transmitted through the chilled water, which prevents damage to the mechanism from the thermal action of steam or hot water, and the pressure gauge is also protected from hydraulic shocks.
In this process, it is advisable to use the Metran-55 pressure sensor. The selected sensor is ideal for measuring the flow of liquid, gas, steam. This sensor has the required measurement limits - min. 0-0. 06 MPa to max. 0-100 MPa. Provides the required accuracy of 0.25%. It is also very important that this sensor has an explosion-proof design, the output signal is unified - 4-20 mA, which is convenient when connecting a secondary device, since it does not require additional installation of an output signal converter. The sensor has the following advantages: 10:1 changeover range, continuous self-diagnostics, built-in RFI filter. Microprocessor electronics, the possibility of simple and convenient setting of parameters with 2 buttons.
The measured pressure is fed into the working cavity of the sensor and acts directly on the measuring membrane of the strain gauge, causing its deflection.
The sensitive element is a single-crystal sapphire plate with silicon film strain gauges. Connected to the metal plate of the strain gauge. Strain gauges are connected in a bridge circuit. Deformation of the measuring membrane leads to a proportional change in the resistance of strain gauges and unbalance of the bridge circuit. The electrical signal from the output of the bridge circuit of the sensors enters the electronic unit, where it is converted into a unified current signal.
The sensor has two modes of operation:
Pressure measurement mode; - mode of installation and control of measurement parameters.
In the pressure measurement mode, the sensors provide constant monitoring of their work and, in the event of a malfunction, form a message in the form of a decrease in the output signal below the limit.
4. 2 Temperature measurement
One of the parameters that must not only be controlled, but also signal the maximum allowable value is temperature.
resistance thermometers and radiation pyrometers.
In boiler rooms for measuring temperature, devices are used, the principle of operation of which is based on the properties exhibited by substances when heated: Change in volume - expansion thermometers; Change in pressure - manometric thermometers; Appearance of thermoEMF – thermoelectric pyrometers;
Change in electrical resistance - resistance thermometers.
extensions are used for local measurements of temperatures ranging from -190 to +6000C. The main advantages of these thermometers are simplicity, low cost and accuracy. These instruments are often used as reference instruments. Disadvantages - the impossibility of repair, the lack of automatic recording and the possibility of transmitting readings over a distance. The measurement limits of bimetallic and dilatometric thermometers are from -150 to +700 0С, the error is 1-2%. Most often they are used as sensors for automatic control systems.
Manometric thermometers. Used for remote temperature measurement. The principle of their operation is based on the change in pressure of liquids, gas or steam in a closed volume depending on temperature.
The type of working substance determines the type of manometric thermometer:
Gas - inert gas (nitrogen, etc.)
Their advantage is the simplicity of design and maintenance, the possibility of remote measurement and automatic recording of readings. Also, the advantages include their explosion safety and insensitivity to external magnetic and electric fields. Disadvantages - low accuracy, significant inertia and a relatively small distance of remote transmission of readings.
Thermoelectric pyrometer. It is used to measure temperatures up to 16000C, as well as to transfer readings to a heat shield and consists of a thermocouple, connecting wires and a measuring device.
A thermocouple is a connection of two conductors (thermoelectrodes) made of various metals (platinum, copper) or alloys (chromel, copel, platinum-rhodium), isolated from each other by porcelain beads or tubes. Some ends of thermoelectrodes are soldered, forming a hot junction, while others remain free.
For ease of use, the thermocouple is placed in a steel, copper or quartz tube.
When the hot junction is heated, a thermoelectromotive force is formed, the magnitude of which depends on the temperature of the hot junction and the material and material of the thermoelectrodes.
electrical resistance of conductors or semiconductors when the temperature changes. Resistance thermocouples: platinum (RTC) are used for long-term measurements in the range from 0 to +650 0С; copper (TCM) for measuring temperatures in the range from -200 to +200 0С. As secondary devices, automatic electronic balanced bridges are used, with an accuracy class of 0.25 to 0.5. Semiconductor resistance thermometers (thermistors) are made from oxides of various metals with additives. The most widespread are cobalt-manganese (CMT) and copper-manganese (MMT) semiconductors used to measure temperatures in the range from -90 to +300 0С. Unlike conductors, the resistance of thermistors decreases exponentially with increasing temperature, due to which they have high sensitivity. However, it is almost impossible to manufacture thermistors with exactly the same characteristics, so they are calibrated individually. Resistance thermal converters complete with automatic electronic balanced bridges allow measuring and recording temperature with high accuracy, as well as transmitting information over long distances. with measurement limits from - 20 to + 1300 0С; chromel-copel (TXA) transducers with measurement limits from -50 to + 600 0С and chromel-alumel (TXA) transducers with measurement limits from -50 to + 1000 0С. For short-term measurements, the upper temperature limit for the TXK transducer can be increased by 200 0С, and for the TPP and TXA transducers by 300 0С. To measure the temperature on pipelines and boilers, I decided to choose thermoelectric converters of the TXK type - the choice of these particular converters is due to the fact that in the measurement range from -50 to +600 0C it has a higher sensitivity than the TXA converter. The main characteristics of the thermoelectric converter type TKhK - 251 manufactured by CJSC PG "Metran":
· Appointment: for measurement of temperatures of gaseous and liquid environments;
· Range of measured temperatures: from – 40 to +600 0С;
· The length of the mounting part of the converter 320 mm;
· Material of a protective cover; stainless steel, brand 12X18H10T, and its diameter is 10 mm;
· Average service life not less than 2 years;
· Sensitive element: thermocouple cable KTMS-KhK TU16-505. 757-75;
4. 3 Level measurement
The level is the height of filling the technological apparatus with a working medium - a liquid or a granular body. The level of the working environment is a technological parameter, information about which is necessary to control the operating mode of the technological apparatus, and in some cases to control the production process.
By measuring the level, you can get information about the mass of liquid in the tank. The level is measured in units of length. Measuring instruments are called level gauges.
There are level gauges designed to measure the level of the working environment; measurements of the mass of liquid in the process apparatus; signaling of the limit values of the level of the working medium - level detectors.
According to the measuring range, there are level gauges of wide and narrow ranges. Wide range level gauges (with measurement limits of 0.5 - 20 m) are designed for inventory operations, and narrow range level gauges (measurement limits (0÷ ±100) mm or (0÷ ±450) mm) are usually used in automatic control systems.
At present, level measurement in many industries is carried out with level gauges of various operating principles, of which float, buoy, hydrostatic, electric, ultrasonic and radioisotope are widely used. Visual measuring instruments are also used.
Indicating or level glasses are made in the form of one or more chambers with flat glasses connected to the apparatus. The principle of operation is based on the property of communicating vessels. Used for local level measurement. The glass length does not exceed 1500 mm. The advantages include simplicity, high accuracy: the disadvantages are fragility, the impossibility of transmitting readings over a distance.
When calculating float level gauges, such design parameters of the float are selected that provide the state of equilibrium of the “float-counterweight” system only at a certain depth of the float immersion. If we neglect the gravity force of the cable and friction in the rollers, the equilibrium state of the "float-counterweight" system is described by the equation
where Gr, Gp are the gravity forces of the counterweight and float; S is the area of the float; h1 is the depth of the float; pzh is the density of the liquid.
An increase in the liquid level changes the immersion depth of the float and an additional buoyancy force acts on it.
The advantage of these level gauges is their simplicity, sufficiently high measurement accuracy, the ability to transmit over a distance, and the ability to work with aggressive liquids. A significant disadvantage is the sticking of a viscous substance to the float, which affects the measurement error.
The principle of operation of capacitive level gauges is based on a change in the capacitance of the transducer due to a change in the level of the controlled medium. The measurement limits of these level gauges are from 0 to 5 meters, the error is not more than 2.5%. Information can be transmitted over a distance. The disadvantage of this method is the impossibility of working with viscous and crystallizing liquids.
The principle of operation of hydrostatic level gauges is based on the measurement of pressure, which creates a liquid column. Hydrostatic pressure measurement is carried out:
· a manometer connected at a height corresponding to the lower limit value of the level;
measuring the pressure of a gas pumped through a tube lowered into the liquid filling the tank at a fixed distance.
In our case, the most suitable is a water indicator with round and flat glass, lowered level indicators and water test taps. Water-indicating devices with round glass are installed on boilers and tanks with pressure up to 0.7 kgf/cm2. glass height can be from 200 to 1500 mm, diameter - 8-20 mm, glass thickness 2.5-3.5 mm. Flat glass can be smooth or grooved. Corrugated glass "Klinger" on the inside has vertical prismatic grooves, on the outside it is polished. In such glass, the water appears dark and the steam appears light. If the taps of the water-indicating device are not dirty during the operation of the steam boiler, then the water level in it fluctuates slightly.
4. 4 Flow measurement
One of the most important parameters of technological processes is the consumption of substances flowing through pipelines. High accuracy requirements are imposed on the means of measuring the consumption and quantity of substances during commodity accounting operations.
Let's consider the main types of flowmeters: flowmeters of variable differential pressure, flowmeters of constant differential pressure, tachometric flowmeters, velocity head flowmeters, electromagnetic (induction) flowmeters, ultrasonic ones.
One of the most common principles for measuring the flow of liquids, gases and steam is the variable differential pressure principle.
The principle of operation of constant differential pressure flowmeters is based on the movement of the sensing element vertically depending on the flow rate of the substance, while the flow area changes so that the pressure drop across the sensing element remains constant. The main condition for a correct reading is a strictly vertical installation of the rotameter.
Flow meters. Flowmeters belong to a large group of flowmeters, also called constant differential pressure flowmeters. In these flowmeters, the streamlined body perceives a force effect from the oncoming flow, which increases with an increase in flow rate and moves the streamlined body, as a result of which the moving force decreases and is again balanced by the opposing force. The counteracting force is the weight of the streamlined body when the flow moves vertically from the bottom up or the force of the counteracting spring in the case of an arbitrary flow direction. The output signal of the considered flow transducers is the displacement of the streamlined body. To measure the flow of gases and liquids on process flows, rotameters are used, equipped with transducer elements with an electric or pneumatic output signal.
The outflow of liquid from the vessel occurs through an opening in the bottom or in the side wall. Vessels for receiving liquids are cylindrical or rectangular.
a thin disk (washer) with a cylindrical hole, the center of which coincides with the center of the section of the pipeline, the pressure drop measuring device and the connecting pipes. The summing device determines the flow rate of the medium by the rotational speed of the impeller or rotor installed in the housing.
For gas and steam applications, I opted for the Rosemount Type 8800DR Intelligent Vortex Flow Meter with built-in cone adapters that reduce installation costs by 50%. The principle of operation of a vortex flowmeter is based on determining the frequency of vortices formed in the flow of the medium being measured when flowing around a body of a special shape. The vortex frequency is proportional to the volume flow. It is suitable for liquid, steam and gas flow measurement. For digital and pulse outputs, the basic error limit is ±0. 65%, and additionally ±0 for current. 025%, output signal 4-20 mA. The advantages of this sensor include a non-clogging design, the absence of impulse lines and seals increases reliability, increased resistance to vibration, the ability to replace sensors without stopping the process, and a short response time. Possibility to simulate verification, there is no need to narrow the pipeline during operation. A-100 can be used as a secondary device. To measure the water flow, we use the correlation water flow sensor DRK-4. The sensor is designed to measure the flow and volume of water in completely filled pipelines. Main advantages:
no resistance to flow and pressure loss;
· Possibility of installation of primary converters on the pipeline at any orientation concerning its axis;
correction of readings taking into account inaccuracies in the installation of primary transducers;
· non-spill, simulation method of verification;
Intercheck interval - 4 years;
· unified current signal 0-5.4-20 mA;
· self-diagnosis;
temperature of liquid fuel in a common pressure line; steam pressure in the line for spraying liquid fuel; pressure of liquid or gaseous fuel in common pressure lines; consumption of liquid or gaseous fuel as a whole for the boiler house. The boiler room should also provide for the registration of the following parameters: the temperature of superheated steam intended for technological needs; water temperature in the supply pipelines of the heating network and hot water supply, as well as in each return pipeline; steam pressure in the supply manifold; water pressure in the return pipeline of the heating network; steam flow in the supply manifold; water consumption in each supply pipeline of the heating network and hot water supply; consumption of water used to feed the heating network. Deaerator-feeding installations are equipped with indicating instruments for measuring: water temperature in accumulator and feed tanks or in the corresponding pipelines; steam pressure in deaerators; feed water pressure in each line; water pressure in the suction and pressure nozzles of the feed pumps; water level in accumulator and nutrient tanks.
| Controlled parameter | The presence of indicating devices on the boilers | |||
| <0,07 | >0,07 | <115 | >115 | |
|
4. Flue gas temperature behind the boiler 6. Steam pressure in the boiler drum 7. Steam (water) pressure after the superheater (after the boiler) 8. Steam pressure supplied to the fuel oil spraying 9. Water pressure at the boiler inlet 11. Air pressure after blower 12. Air pressure in front of the burners (after the control dampers) 15. Vacuum in front of the damper of the smoke exhauster or in the flue 16. Vacuum in front of and behind the tail heating surfaces 18. Water flow through the boiler (for boilers with a capacity of more than 11.6 MW (10 Gcal / h)) 19. Level in the boiler drum |
||||
* For boilers with a capacity of less than 0.55 kg / s (2 t / h) - pressure in the common feed line 6. Basic information about fuel.
Fuels are combustible substances that are burned to produce heat. According to the physical state, the fuel is divided into solid, liquid and gaseous. Gaseous gas includes natural gas, as well as various industrial gases: blast furnace, coke, generator and others. High quality fuels include hard coal, anthracites, liquid fuels and natural gas. All types of fuel consist of combustible and non-combustible parts. The combustible part of the fuel includes: carbon C, hydrogen H2, sulfur S. The non-combustible part includes: oxygen O2, nitrogen N2, moisture W and ash A. The fuel is characterized by working, dry and combustible masses. Gas fuel is most convenient for mixing it with air, which is necessary for combustion, since fuel and air are in the same state of aggregation.
5. Physical and chemical properties of natural gases
Natural gases are colorless, odorless and tasteless. The main indicators of combustible gases that are used in boiler rooms are: composition, calorific value, density, combustion and ignition temperature, explosive limits and flame propagation speed. Natural gases from purely gas fields consist mainly of methane (82-98%) and other heavier hydrocarbons. The composition of any gaseous fuel includes combustible and non-combustible substances. Combustibles include: hydrogen (H2), hydrocarbons (CmHn), hydrogen sulfide (H2S), carbon monoxide (CO2), non-combustible - carbon dioxide (CO2), oxygen (O2), nitrogen (N2) and water vapor (H2O). The calorific value is the amount of heat that is released during the complete combustion of 1 m3 of gas, measured in kcal / m3 or kJ / m3. A distinction is made between the higher calorific value Qvc, when the heat released during the condensation of water vapor, which are in the flue gases, and the lower Qнc, when this heat is not taken into account, are taken into account. When performing calculations, Qvc is usually used, since the temperature of the flue gases is such that condensation of water vapor from the combustion products does not occur. The density of a gaseous substance pr is determined by the ratio of the mass of the substance to its volume. Density unit kg/m3. The ratio of the density of a gaseous substance to the density of air under the same conditions (pressure and temperature) is called the relative density of the gas pо. Gas density pr = 0.73 - 0.85 kg / m3 (po = 0.57-0.66) The combustion temperature is the maximum temperature that can be reached with complete combustion of the gas, if the amount of air required for combustion exactly chemical formulas of combustion, and the initial temperature of the gas and air is 0 ° C, and this temperature is called the heat output of the fuel. The combustion temperature of individual gases is 2000-2100 o C. The actual combustion temperature in boiler furnaces is much lower, it is 1100-1600 o C and depends on the combustion conditions. The ignition temperature is the temperature at which fuel combustion begins without the influence of an ignition source; for natural gas, it is 645-700 ° C. Explosive limits. The gas-air mixture, in which the gas is up to 5% - does not burn; from 5 to 15% - explodes; more than 15% - burns when air is supplied. The flame propagation speed for natural gas is 0.67 m/s (CH4 methane). The use of natural gas requires special precautions, since it can leak through leaks at the junction of the gas pipeline with gas fittings. The presence of more than 20% of the gas in the room causes suffocation, its accumulation in a closed volume from 5 to 15% can lead to an explosion of the gas-air mixture, with incomplete combustion carbon monoxide CO is released, which even at a low concentration has a toxic effect on the human body.
6. Description of the scheme of automatic control of technological parameters
6. 1 Functional diagram of automatic control of technological parameters
The principle of building a control system for this process is two-level. The first level consists of devices located in the field, the second - devices located on the operator's board.
Table 2.
Name and technical characteristics of equipment and materials. Manufacturer |
Type, brand of equipment. Symbol Document and Questionnaire No. | Unit measurements |
Quantity |
|
| Pipeline temperature control | ||||
| 1a | Gas temperature in the pipeline Thermoelectric converter |
THC-251-02-320-2-I-1-N10-TB-T6-U1. 1-PG |
PC. | 1 |
| 1b | Secondary indicating registering device, speed 5 s, time of one revolution 8 h | DISK250-4131 | PC. | 1 |
| 2a |
PG "Metran", Chelyabinsk |
ТСМ254-02-500-В-4-1- |
PC. | 1 |
| 2b | PC. | 1 | ||
| 2v | PRB-2M | PC. | 1 | |
| 2g | Actuator, power supply 220V, frequency 50Hz | MEO-40/25-0.25 | 1 | |
| 3a | Copper resistance thermal converter nominal static characteristic 100M |
ТСМ254-02-500-В-4-1- TU 422700-001-54904815-01 |
1 | |
| 3b | Electromagnetic transducer, flow rate 5l/min, output signal 20-100 kPa | EPP | 1 | |
| 3v | 1 | |||
| 3g | PR 3. 31-M1 | 1 | ||
| 3d | Actuator, nominal pressure 1.6 MPa | 25h30nzh | 1 | |
| Pipeline Flow Control | ||||
| 4a | Chamber diaphragm, nominal pressure 1.6 MPa | DK 16-200 | 1 | |
| 4b | Differential transducer, error 0.5%, measurement limit 0.25 MPa | Sapphire 22DD-2450 | 1 | |
| 4c | Secondary indicating recording device. Speed 5s, time of one revolution 8h. | DISC 250-4131 | 1 | |
| Flow control | ||||
| 5a | IR-61 | 1 | ||
| 5 B |
PG "Metran", Chelyabinsk Self-recording, 2-channel, percentage scale. Cl. t. 0. 5, speed 1s. |
Rosemount 8800DR A100-BBD,04. 2, TU 311--00226253. 033-93 |
1 | |
| 5v | Non-contact reversing starter, discrete input signal 24V, power supply 220V, 50Hz | PBR-2M | 1 | |
| 5g | Actuator, power supply 220V, frequency 50Hz | 1 | ||
| Level control | ||||
| 6a | Equalizer, upper measurement limit 6m, maximum allowable overpressure 4 MPa, supply pressure 0.14 MPa, pneumatic output signal 0.08 MPa | UB-PV | 1 | |
| 6b | Pressure gauge, power supply 220V, power 10 W | EKM-1U | 1 | |
| 6c | Secondary pneumatic indicating and self-recording instrument, with control station. Air consumption 600 l/h | PV 10. 1E | 1 | |
| 6g | 25h30nzh | 1 | ||
| Pressure measurement |
7. Basic principles of automation of boiler plants
The volume of boiler plant automation systems depends on the type of boilers installed in the boiler room, as well as on the presence of specific auxiliary equipment in its composition. Boiler plants include the following systems: automatic control, safety automation, thermal control, signaling and control of electric drives. Automatic control systems. The main types of automated control systems for boiler installations: for boilers - regulation of combustion and power processes; for deaerators - water level control and steam pressure. Automatic control of combustion processes should be provided for all boilers operating on liquid or gaseous fuels. When using solid fuel, ASR of combustion processes is provided in cases of installation of mechanized combustion devices.
ASR fuel is not provided.
Power regulators are recommended to be installed on all steam boilers. For boiler plants operating on liquid fuel, it is necessary to provide ACP for fuel temperature and pressure. Boilers with a steam superheat temperature of 400 0C and above must be equipped with an ACP for superheated steam temperature. Security automation. Safety automation systems for gaseous and liquid fuel boilers must be provided. These systems ensure that the fuel supply is cut off in emergency situations.
Table3.
| Parameter deviation | Stopping the fuel supply for boilers | |||
| Steam with steam pressure piz, MPa | Water heating with water temperature, 0С | |||
| <0,07 | >0,07 | <115 | >115 | |
1. Increasing the steam pressure in the boiler drum 2. Increasing the temperature of the water behind the boiler 3. Air pressure reduction 4. Gas pressure reduction 5. Increasing gas pressure 6. Reducing the water pressure behind the boiler 7. Reducing the rarefaction in the furnace 8. Lowering or raising the level in the boiler drum 9. Reducing water flow through the boiler 10. Extinction of the torch in the boiler furnace 11. Malfunction of safety automation equipment |
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Conclusion
During the implementation of the course project, practical skills were acquired in the analysis of the technological process, the choice of automatic control tools according to the tasks set, the calculation of measuring circuits for instruments and controls. The skills of designing a system for automatic control of technological parameters were also obtained.
Literature
1. A. S. Boronikhin Yu. S. Grizak “Fundamentals of production automation and instrumentation at the enterprises of the building materials industry” M. Stroyizdat 1974 312s.
2. V. M. Tarasyuk “Operation of boilers”, a practical guide for boiler house operators; edited by B. A. Sokolov. - M.: ENAS, 2010. - 272 p.
3. V. V. Shuvalov, V. A. Golubyatnikov “Automation of production processes in the chemical industry: Textbook. For technical schools. - 2nd ed. revised and additional - M.: Chemistry, 1985. - 352 p. ill.
4. Makarenko VG, Dolgov KV Technical measurements and devices: Guidelines for course design. South -Ros. state tech. un-t. Novocherkassk: YuRGTU, 2002. - 27p.
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