Hydrolyzed lignin - an excellent high-calorie fuel and easily accessible renewable raw material for the production of fuel pellets and briquettes.
Currently, the relevance of the issue of producing alternative energy sources is constantly increasing. There are a number of reasons for this.
1. Traditional energy resources - gas, coal, oil - are becoming more and more difficult to extract every year, and this leads to a constant increase in their cost. As is known, the issue of the cost of imported gas is of particular relevance for Ukraine.
2. Reserves of traditional energy resources are rapidly depleting, which makes the production of alternative energy resources a very promising business area.
3. The production of alternative energy sources is stimulated by the Governments of all developed countries, including Ukraine.
Lignin Lignin storage facility is on fire
Lignin pellets Pini&Key lignin briquettes
The new law On promoting the production and use of biological fuels "Enterprises producing biofuels, including fuel pellets and briquettes, are exempt from profit taxation until January 2020. There are also a number of economic, environmental and social prerequisites that contribute to the expansion of the biofuel market in general, and fuel pellets and briquettes in particular But many businessmen who have directed their efforts and capital into this promising segment of the economy have encountered unexpected problems.
The main competition in this industry does not lie in sales- there are no problems with it, and, basically, all products are shipped for export to the countries of the European Union - and in the field of providing raw materials. The fact is that many enterprises that have installed briquetting or biomass granulation equipment are currently not operating at full capacity, and are often completely idle due to lack of raw materials. This is primarily due to the seasonality of the availability of certain types of raw materials (sunflower husks, straw, cereal crop waste, corn processing waste, other types of agricultural raw materials), incorrect choice of equipment installation location (for example, distance from potential sources of raw materials), high logistics costs for the delivery of raw materials , which, as a rule, has a very low bulk weight (for example, the bulk weight of sunflower husks is 100 kg/m3).
In such a situation, lignin is a good alternative to agricultural waste as a raw material, since its reserves are available in sufficiently large quantities regardless of the processing season, lignin lends itself well to granulation and briquetting due to its excellent binding properties, and has a fairly large bulk weight (up to 700 kg/m3) , which makes it profitable to transport it over considerable distances even not in granular form, has a good calorific value comparable to coal, with a much lower ash content, and the price of the raw material, lignin, is relatively low. Due to the special properties of lignin, in the technology of its preparation for further use, special importance is attached to the issue of drying lignin.
If consider lignin from a physicochemical point of view, then in its original form this substance is a complex sawdust-like mass, the moisture content of which reaches up to seventy percent. In fact, lignin is a unique complex of substances that consists of polysaccharides, a special group of substances belonging to the so-called lignohumic complex, monosaccharides, various mineral and organic acids of various saturations, as well as a certain part of ash. Hydrolyzed lignin is a sawdust-like mass with a moisture content of approximately 55-70%. In terms of its composition, it is a complex of substances, which includes the lignin of the plant cell itself, part of the polysaccharides, a group of substances of the lignohumic complex, mineral and organic acids not washed after hydrolysis of the monosaccharide, ash and other substances. The content of lignin itself in lignin ranges from 40-88%, polysaccharides from 13 to 45%, resinous substances and lignohumic complex substances from 5 to 19%, and ash elements from 0.5 to 10%. The ash of hydrolysis lignin is mainly alluvial. Hydrolytic lignin is characterized by a large pore volume approaching the porosity of charcoal, high reactivity compared to traditional carbonaceous reducing agents and twice the solid carbon content compared to wood, reaching 30%, that is, almost half the carbon of charcoal.
Hydrolytic lignin is distinguished by its ability to transform into a viscoplastic state when pressure of about 100 MPa is applied. This circumstance predetermined one of the promising areas for using hydrolytic lignin in the form of briquetted material. It has been established that lignobriquettes are a high-calorie, low-smoke household fuel, a high-quality reducing agent in ferrous and non-ferrous metallurgy, replacing coke, semi-coke and charcoal, and can also be used for the production of coal such as charcoal and carbon sorbents. Research and experimental work of a number of organizations have shown that o briquetted hydrolytic lignin can be a valuable raw material for the metallurgical, energy and chemical sectors of the country's national economy, as well as high-grade municipal fuel.
Technological developments that make it possible to obtain the following briquetted ligno products can be recommended for implementation:
- lignobriquettes to replace traditional carbon metallurgical reducing agents and lump charge in the production of crystalline silicon and ferroalloys;
- low-smoke fuel lignobriquettes;
- briquetted lignin coal instead of wood in the chemical industry;
- carbon sorbents from lignobriquettes for purification of industrial wastewater and sorption of heavy and noble metals;
- energy briquettes from a mixture with coal screenings.
Lignin fuel briquettes are high-quality fuel with a calorific value of up to 5500 kcal/kg and low ash content. When burned, lignin briquettes burn with a colorless flame without emitting a smoky smoke plume. The density of lignin is 1.25 - 1.4 g/cm3. The refractive index is 1.6.
Hydrolyzed lignin has a calorific value, which for absolutely dry lignin is 5500-6500 kcal/kg for a product with 18-25% moisture content, 4400-4800 kcal/kg for lignin with 65% moisture content, 1500-1650 kcal/kg for lignin with a moisture content of more than 65%. According to its physicochemical characteristics, lignin is a three-phase polydisperse system with particle sizes ranging from several millimeters to microns or less. Studies of lignins obtained at various plants have shown that their composition is characterized on average by the following content of fractions: with a size greater than 250 microns - 54-80%, with a size less than 250 microns - 17-46%, and with a size less than 1 micron - 0.2- 4.3%. In structure, a particle of hydrolytic lignin is not a dense body, but is a developed system of micro- and macropores; the size of its internal surface is determined by humidity (for wet lignin it is 760-790 m2/g, and for dry lignin only 6 m2/g).
As shown by many years of research and industrial testing carried out by a number of research, educational and industrial enterprises, valuable types of industrial products can be obtained from hydrolytic lignin. For the energy sector, briquetted municipal and fireplace fuel can be produced from the original hydrolyzed lignin, and briquetted energy fuel can be produced from a mixture of lignin with coal enrichment screenings.
The process of lignin combustion in technological furnaces without direct heat transfer has significant differences compared to the furnaces of steam boilers. They do not have a beam-receiving surface, and therefore, in order to avoid slagging of ash, it is necessary to carefully calculate the aerodynamic modes of the process. The temperature of the flame core, due to the lack of direct heat transfer, turns out to be higher and is concentrated in a smaller volume than in the furnaces of steam boilers. To burn lignin, it is most advisable to use a flare furnace of the Shershnev system, which provides sufficiently high efficiency for fuels with a high degree of dispersion.
Lignin can be effectively used as fuel for combustion in a heat generator of a drying complex for drying sawdust or other biomass in lines for the production of fuel granules, pellets and fuel briquettes. Carefully prepared pulverized fuel is close to liquid fuel in terms of burnout rate and combustion completeness. Complete combustion in a torch is ensured with a lower excess air ratio and, consequently, with a higher temperature. When conducting the combustion process with a small excess of air, explosion-proof operating conditions for the drying complex are ensured, which positively distinguishes drying with the direct use of flue gases from the drying method with heated air.
Thus, lignin is an excellent, high-calorie fuel and an easily accessible renewable raw material for the production of fuel pellets and briquettes.
Application of powdered lignin.
Powdered lignin is suitable as an active additive in road asphalt concrete, as well as for adding fuel oil when used in energy and metallurgy. Hydrolyzed lignin, used as a mineral powder, allows:
1.
To increase the quality of asphalt concrete (strength - by 25%, water resistance - by 12%, crack resistance (fragility) - from -14°C to -25°C) through additional modification of petroleum bitumen.
2.
Save road construction materials: a) petroleum bitumen by 15-20%; b) lime mineral powder 100%.
3.
Significantly improve the environmental situation in the waste storage area.
4.
Return fertile lands currently occupied by dumps.
Thus, studies conducted on the use of technological hydrolytic lignin (THL) in the production of asphalt concrete show that there are opportunities to significantly expand the raw material base of materials for the construction of modern roads (republican, regional and urban), while simultaneously improving the quality of their coating by modifying petroleum bitumen with hydrolytic lignin and complete replacement of expensive mineral powders.
In 2017, the Bionet company made the first industrial shipment of a batch of fuel pellets from hydrolytic lignin to Europe. According to the general director of the company, Vyacheslav Pyshny, Bionet is the only manufacturer of lignin-based pellets in the world, and its owner, Gazprombank, intends to replicate similar production.
– How did the idea of creating the Bionet company come about?
– The idea of using hydrolyzed lignin as fuel appeared back in Soviet times at an existing hydrolysis plant.
At that time, this enterprise generated a large amount of waste from the production of ethyl alcohol, which had to be stored or processed. After conducting a series of laboratory studies and analyses, workers at the hydrolysis plant came to the conclusion that this waste could be used as fuel in their own boiler house. The experiments were constantly accompanied by failures that prevented the development of technological solutions. Soon the hydrolysis plant ceased to exist. But the lignin dumps have not gone away, and the Bionet team, picking up the idea, began developing technological solutions.
The company was founded in 2009, and from the very beginning it was created to produce biofuels. The sole shareholder of the company is JSC Gazprombank. Investments in this project amounted to about 30 million euros. Payback period is 6–8 years. Today we produce unique products under the Black pellets Bionet brand. We are the world's only manufacturer of hydrolytic lignin fuel pellets. Currently the company has one plant. But, as far as I know, the shareholder plans, based on the positive outcome of the Bionet pilot, to consider the issue of replicating such enterprises.
– What tasks have your shareholders set for you for 2017?
– Reach the design power levels. Last year we completed commissioning work and produced more than 20 thousand tons of pellets. In the first half of 2017, the re-equipment of the plant was completed. While commissioning work was underway, new innovative solutions appeared, which we tried to apply at our enterprise, and at the moment we have produced 7.3 thousand tons of granules from hydrolytic lignin. We do not stop working on honing the technological process: we strive to take into account all the innovations in production solutions and equipment in our segment at our plant. The line is now up and running at full capacity. At the moment we are in a state of contract with more than seven consumers of our products. It is important to understand that the work is carried out for the client, and based on the results of the signed contract, we receive a figure that is the final figure, like a reference point towards which we are moving. Of the deliveries that we have already made, the revenue amounted to about 40 million rubles. Over the next three years, we intend to earn 30 million euros.
– Who was the supplier of the equipment?
– These are large foreign manufacturers. The plant is equipped with drying equipment from VetterTec (Germany). The Italian manufacturer Pal supplied a fine air purification system at the entire production stage - from the preparation of input raw materials to the granulation section. Press granulators for the production of pellets were supplied to us by Salmatec (Germany).
– What is the technology for producing pellets from hydrolytic lignin?
– The production technology is the intellectual property of the enterprise, so I cannot disclose it. In general terms, the uniqueness of the technology lies in the fact that the drying of the input raw materials is carried out at low temperatures. The raw materials are also moved in a special way, and the preparation of the raw materials for granulation differs from the generally accepted one.
– What is the advantage of hydrolyzed lignin pellets over conventional wood pellets?
– Lignin pellets belong to innovative products. They are non-hygroscopic and can be stored outdoors with little or no cover. They are not exposed to sunlight and are not saturated with moisture: if granules from hydrolytic lignin are immersed in liquid, they can lie there for a long time and their structure will not change. Ordinary wood pellets in such conditions will simply turn into mush. Lignin pellets have increased calorific value. If ordinary wood pellets have a lower calorific value of about 17 GJ/t, then ours have a lower calorific value of 20.5 GJ/t.
– Is the cost of producing lignin pellets higher than conventional granules?
– The production of lignin pellets is cheaper, since there is no need to purchase special additives. Mainly energy costs. The entire technological process is automated, the operator only exercises control. Potentially, our enterprise model can provide 244 jobs. Currently the company employs 151 people. Since the production is high-tech and requires certain skills from the staff - knowledge of specialized software systems, human participation in the software - we do not recruit people without training. And once every two months, employees are examined for suitability for the position they hold.
– How do Black pellets Bionet differ from “black” torrefied pellets?
– “Black” pellets are a new direction on the market, and so far we indicate in the certificates that we belong to this segment. Mainly producers of “black” wood pellets are companies from the USA and Canada. We relate less and less to this segment and will eventually move away from the Black pellets Bionet brand. We are now developing a trademark that will correspond and fully characterize our product. The production is devoid of such an energy-intensive process as torrefaction, or pyrolysis, of wood.
– Does the company provide itself with raw materials?
– Yes, raw materials are our property. Lignin is a waste product from hydrolysis production, and we, in addition to producing biofuel, are also a recycling company - we free the earth from the negative impact of previously created waste. The existing volume of lignin at the landfill will ensure production operation for 15–20 years.
– How is logistics organized?
– Geographically, we are located away from the main trade routes and logistics centers. But at the same time, the company has its own railway line, which runs through the territory of the enterprise and connects us with the main highways. Therefore, we can deliver finished products to the buyer on time. We have the ability to ship finished products directly at the plant; there are hard-surfaced areas, ramps, and convenient storage locations. Together with the administration of the Arkhangelsk region. We are exploring the possibility of creating a quay wall, port equipment, and infrastructure in Onega. The Onega River, on the banks of which the plant is located, flows into the White Sea. Our company has its own logistics department. By rail, the granules are sent to logistically advantageous ports in the north-west of the country for subsequent transshipment into ships and continue their journey, depending on which country the delivery is going to. Pellets come to European countries by sea.
– What are the company’s main markets?
– Our clients are large energy companies from Central Europe and Benelux. Don't forget about the north of Europe - this is Finland. In connection with the idea of replicating our factories, we began to study the markets of China, Korea and Japan. We also consider Northern Kazakhstan as a potential consumer. We do not refuse any proposals and are ready to move forward. Nowadays in Asia there is a tendency to build large energy complexes. Many countries are moving away from gas pollution and excess emissions. If Russia does this too, it will be great! After all, our plans are to sell 10–15% of all manufactured products in the north-west of the country.
– What share of the Asian and European markets do you plan to occupy?
– The Asian market is huge. I think that our share in it will be about 3%. We will be ready to supply 100 thousand tons of pellets to this market, that is, 90% of all manufactured products. In Europe we will be able to occupy about 10% of the pellet market.
– Are you planning to expand production?
– Now we are already in the expansion stage. We are planning to launch a line for the production of briquettes from our production waste generated as a result of the preparation of raw materials before the granulation stage. In order not to create a landfill from this waste, we conducted a series of laboratory tests and came to the conclusion that they can be used as raw materials for the production of briquettes. To do this, you will need to install one or two more granulator presses. These products will be aimed at the domestic market. In addition, we plan to use briquettes for our own needs, as well as sell them in the region to generate thermal energy not only in Onega, but also at fuel and energy plants in the region. Construction of the line should be completed in January 2018, and in February we will begin production.
– Who are the consumers of your pellets?
– The Russian pellet market is represented by private organizations. This is heating cottages, or, at most, small gyms. People don't understand what pellets are. Our fuel can be used at all kinds of facilities - both to generate electricity at thermal power plants and to heat industrial premises. I am sure that Russia needs pellets like ours. And not only because they emit a lot of heat, which is important for a northern country. On the territory of the Russian Federation there is a large amount of waste, which, when stored, has a negative impact on the environment. We are a recycling company - by removing one thing, we make fuel that people need.
– How do you assess the potential of lignin dumps in the country?
– Over the period of existence of hydrolysis plants, a colossal amount of waste has been accumulated. According to various estimates, there are about 50 sites in the country with lignin dumps of approximately 4.5 million tons each. Their recycling primarily solves the environmental problem associated with littering large areas. At the same time, being a good fuel, it is also economically profitable, which makes the further development of the project very promising.
– What will stimulate the demand for pellets within the country?
– To do this, we need to go a long way – to start forming this market. Without this, there will be only private purchases for heating homes, nothing more. Of course, biofuel in Russia will not be able to displace the coal sector. Manufacturers of fuel pellets simply will not be able to cover all the needs that are currently covered by coal or gas. To develop the pellet market, laws and programs are needed to stimulate the pellet sector, as, for example, in Europe. There, the use of high-emitting fuels, which have a negative impact on the environment, is completely prohibited. In addition, subsidies are developed in Europe: if an enterprise switches to using fuel pellets, it receives various preferences, which ultimately reimburses its costs for purchasing pellets. I think that in Europe by 2018 the number of enterprises using biofuels will be about 98%. All energy-intensive enterprises will be switched to running on biofuels.
– Will pellets made from hydrolytic lignin be in demand in Europe?
– Some of the consumers will switch to this type of granules. However, we, naturally, will not be able to provide all customers with our products alone. In addition, local producers of conventional pellets have a strong position in this market. Since we are at the beginning of our journey, we do not consider them competitors. We are different. And as far as possible, we inform the public and especially energy producers about what our products are. Our granules have passed all the necessary laboratory tests, and their quality is confirmed by various certificates, and therefore they can be used in Europe, in particular the Benelux countries.
– How do you assess the investment attractiveness of the Russian biofuel market?
- She's huge! But for its further development it is necessary to attract investors, those companies that already pay great attention to environmental friendliness of production and understand the advantages of using fuel pellets.
– What production and financial indicators do you plan to achieve in 2017?
– We have a meeting of the investment committee with our shareholder scheduled for November 2017, at which we will have to come to the final figures. The enterprise's capacity allows it to produce 100–150 thousand tons of finished products. The production line is designed to produce 12–12.5 thousand tons of granules monthly. But their cost and connection to the economy depend on market prices. By the way, our boiler house also runs on our own biofuel; we do not use fossil fuels at all. This is extremely important for us and for those companies that issue us certificates for our products. Each biofuel plant must operate on the fuel it produces.
– Where do you see the company in five years?
– I think that during this time we will go through the stage of replication and we will have at least three enterprises producing fuel products. We are ready to develop the production of fuel pellets from hydrolytic lignin and move forward with various technology improvements and cost reductions. Our other segment is briquettes. I think in every economic model we will consider these two lines so that they run in parallel, with overlap and complete waste disposal.
Biography:
Vyacheslav Pyshny was born on July 29, 1968. He graduated from the Moscow Institute of Public Utilities and Construction with a degree in hydraulic engineering. He has headed the Bionet company since March 1, 2017. Before that, from September 12, 2016, he held the position of acting CEO.
Reference
The Bionet company was created in 2009 to implement a project for the construction of plants for the production of biofuel (industrial pellets) from waste from the hydrolysis industry. The design capacity of the pilot plant, located in Onega, Arkhangelsk region, is 150 thousand tons of pellets per year.
Traditionally, coniferous wood waste is used in the production of wood fuel pellets. However, coniferous wood is an expensive raw material, in demand in the woodworking industry, and its waste is used in a number of other industries. As a result, the resources of coniferous wood are constantly decreasing, and for the production of pellets it is necessary to use low-value and cheap hardwood, which is not as widely used in industrial production as coniferous wood.
In relation to pellet production technology, the main difference between hardwood and coniferous species is the low lignin content: 14-25% versus 23-28%. The high temperature and pressure of pressing wood raw materials activate the lignin contained in its cells and bring it into a plastic state. Lignin acts in this process as an internal binder, ensuring the strength of the pellets. Granules made from hardwood are less durable due to the lower lignin content. And to achieve the required strength, various additives or steam treatment of raw materials are used, which will be discussed below.
Also, when producing pellets, the hardness of the wood matters. Harder deciduous wood is more difficult to press into pellets than coniferous wood; high loads are created on the equipment, especially on consumable parts - the matrix and press rollers. But the heat of combustion of some hardwoods, primarily beech and oak, is higher in comparison with this parameter of conifers.
To meet the ever-growing demand for high-quality wood pellets in Europe, hardwoods are increasingly being used for their production. The question is whether such granules comply with ENplus and DIN+ standards.
Active use of hardwood raw materials for the production of pellets would reduce tensions in the market for softwood waste, which is widely used in board production and other industries, which undoubtedly creates very high competition for pellet producers. However, the ash content in hardwood pellets is higher than in softwood pellets, and in most cases corresponds to the ENplus A2 standard (ash content no more than 1.5%). By the way, a change in the new version of the ENplus A2 standard prescribes an ash content of no more than 1.2% (EN ISO 17225-2). In the future, it is quite possible to further reduce the permissible ash content according to ENplus standards. Nevertheless, all manufacturers of so-called premium pellets (or household pellets, as they are commonly called in the EU), for economic reasons, are trying to bring the characteristics of their products to the ENplus A1 standard (their cost is higher than class A2 and industrial pellets). It is worth noting that the requests for ENplus A2 quality granules in Europe are minimal, since for small boiler houses or mini-thermal power plants, for which this standard was developed, industrial granules are quite suitable, the price of which is lower, production volumes are much higher, and they only differ ash content (up to 1.5%) and, indirectly, color value.
Research in Austria and Germany
To expand the knowledge base on the ash content of pellets made from hardwood, a series of research studies were carried out in Austria to evaluate the feasibility of using hardwood for the production of ENplus pellets. For the largest series of tests, birch, beech, oak and ash were chosen, since these species, along with conifers, are already used in the production of pellets in Austria and Germany. Using a special thermogravimetric analyzer TGA, more than 80 samples were examined for ash content at a temperature of 550°C according to the Austrian standard Önorm EN 14 775. It was established that the ash content in sapwood and other good hardwood timber does not exceed 0.7% (in some cases and when mixing different hardwoods reaches 1-1.5%), and in bark the maximum ash content is up to 10%. Additionally, samples of poplar wood were analyzed; the ash contents were similar.
According to statistics from the German Pellet Institute (DEPI), in Germany, since 2014, the use of hardwood wood has been recorded in the production of pellets, on average up to 10% of the total volume of raw materials (that is, 90% - coniferous, 10% - deciduous). Markus Mann, founder and director of the pellet plant Westerwälder Holzpellets GmbH in Langenbach (Upper Bavaria), experimented in his production with a mixture of 10-15% beech and birch wood and 85-90% coniferous wood. With this ratio, the resulting pellets had an ash content of less than 0.5% and fully complied with ENplus A1 standards. For pelletizing, a matrix with a pressing channel length of 39 mm was used, rather than the standard 45 mm used for coniferous species. To pelletize only beech sawdust, the pressing channel was shortened by another 10 mm - to 29 mm. As a result of experiments, it was found that poplar wood ash has a low sintering temperature, since poplar usually grows on sandy and clay soils; its wood, and especially its bark, contains a lot of silicate compounds. This, by the way, is also typical for a number of other deciduous trees, in particular those artificially planted for protection from unfavorable natural and anthropogenic factors.
In this regard, we can mention the Russian company - CJSC AlT-BioT from the Krasnodar Territory, which in 2009 at the international exhibition Interpellets in Stuttgart presented pellets made from deciduous wood (ash, acacia, oak, beech, maple) obtained after sanitary felling of protective forest plantings in the area of the village of Pavlovskaya. With an ash content below 0.7%, the pellets had a high calorific value - 18 MJ/kg. The company's pellet plant was named "Victoria", investments in the enterprise amounted to 600 million rubles. Investor Alexander Dyachenko announced his intention to build at least 20 similar pellet plants in southern Russia by 2015.
The plant never reached its design capacity (10 tons per day, or 70 thousand tons per year), the maximum productivity of 7 tons per hour was achieved. Products were exported mainly to Europe. In two neighboring areas, boiler houses of several schools were converted to use pellets. The then Deputy Prime Minister Viktor Zubkov, who visited the enterprise in 2009, highly appreciated this project and especially the prospect of its replication in other regions of Russia. The author of the article, as part of a delegation that included representatives of a pellet buyer from the Netherlands, visited this pellet plant in 2010. The Dutch highly appreciated both the quality of the granules and the production. But, alas, in the same year the plant was stopped, the employees were fired, the investor’s brother Nikolai Dyachenko, the head of the regional branch of Rosselkhozbank OJSC in the Krasnodar Territory, who financed the AlTBioTa project, was arrested, and the investor himself went on the run. But that's a completely different story.
Let us return, however, to Austria and Germany. Experts from the Austrian research association BioUP consider the main disadvantage of using hardwood for the production of pellets to be its high ash content compared to coniferous wood. Andreas Haider, a specialist at the Austrian Federal Forestry Research Center, explained that from deciduous wood it is possible to produce not only pellets of the ENplus A2 and industrial classes, but also pellets that fully meet the ENplus A1 and DIN+ standards. It all depends on what part of the hardwood is used as raw material. For example, the ash content of poplar sapwood differs significantly from the ash content of the core of the trunk. The ash content also varies greatly depending on the time of felling and the quality of the soil, that is, on the growing zone of the tree. There is a lot of data on the content of ash substances in wood, but they differ even for the same species. It has been experimentally established that when absolutely dry wood is calcined in a crucible, the average ash residue ranges from 0.3 to 1.0%. Moreover, 10-25% of the residue dissolves in water, this is soda and potash (in the past it was obtained in industrial quantities from wood ash). The most important insoluble components of wood ash - lime and various magnesium and iron salts - account for 75-90%. Haider noticed that in the south of Europe, in the Balkans, especially in the republics of the former Yugoslavia - Croatia, Montenegro, Serbia and Bosnia and Herzegovina - there are a lot of deciduous trees in the forests. And neighboring Italy today ranks first in the European Union in terms of consumption of premium pellets: more than 3 million tons per year. The geographical location provides favorable conditions (logistics) for the export of pellets from these Balkan countries to Italy. For reference: in Germany, according to data at the beginning of 2018, in 2017, 98.9% of pellets were produced from coniferous wood, and only 1.1% from hardwood.
Research in Belarus and Russia
In 2012, at the Department of Chemical Wood Processing of the Belarusian State Technical University in Minsk, pellets were made in laboratory conditions from the main forest-forming species of the Republic of Belarus: birch, alder and pine. Granule samples were obtained at a pressing temperature of 110°C for 15 minutes. The humidity of the dried sawdust used for the study was 8-11%. The task was set to compare the physical and mechanical characteristics of the resulting granules: moisture content, ash content, density, mechanical strength and lower calorific value. It has been established that the lower calorific value of pellets made from birch and alder wood is comparable to the lower calorific value of pine pellets (Table 1). But the ash content of hardwood pellets is 3.5 times higher than the ash content of softwood pellets. The tests carried out confirmed the fundamental possibility of producing pellets from softwood. In terms of ash content, they at least meet the standards for industrial wood pellets (up to 1.5%) and ENplus A2 class pellets. But pellets made from alder and birch wood are characterized by reduced mechanical strength (lower than the strength of pine pellets by 11 and 18%, respectively). To achieve the mechanical strength characteristic of pellets made from softwood, pre-treatment of hardwood raw materials with saturated steam is necessary.
Experimental production of pellets from hardwood treated with saturated steam before granulation was established by Vitebskdrev OJSC. The composition of the raw materials is as follows: birch - 35%, alder - 20%, aspen - 40%, pine - 5%. A matrix with an effective pressing channel length of 33 mm (instead of the usual 45 mm) was used, since heat treatment of deciduous wood takes less time than the processing of coniferous wood (due to this, energy consumption was reduced). As a result, it was found that the density of pellets from the hardwood composition is comparable to the density of pellets from pine wood (Table 2). Here it is appropriate to quote from the test report: “The action of saturated steam led to the activation of wood components, the creation of new functional groups that enhance adhesive interactions during the formation of pellets. Additional moistening of the wood particles occurred, as a result of which the temperature in the press granulator increased from 110 to 120°C. The high pressing temperature contributed to the rapid occurrence of reactions and the accumulation of an increasing number of high molecular weight compounds, mainly due to highly reactive hemicellulose. Melted and softened components filled the voids between the fibers and the capillary and submicrocapillary systems of the cell walls. At the same time, the number of cross-links between the molecules of wood components increased, including spatial ones, which ensured the formation of durable products.”
To increase the strength of hardwood pellets, various additives are often used, such as starch and lignin. The Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of Sciences of the Russian Federation studied the effect of additives when granulating hardwood. Thus, soda, lime, fish oil, vegetable oils, coffee grounds improve the properties of pellets or briquettes: they reduce the percentage of dropouts, increase resistance to breakage during transportation and supply to a warehouse or boiler. Crushed charcoal increases the calorific value of pellets and briquettes.
Raw materials for pellet production
In Europe, so-called fast-growing plantation plants are increasingly used for the production of pellets, the ash content of which is often much higher than the ash content of deciduous wood. Expert and consultant of DIN CERTCO - a worldwide accredited German certification center for organizations, services, products, including DIN+ standards; FSC/PEFC, SBP - Erwin Heffele clarified that some fast-growing plantation plants, such as miscanthus and bamboo, are not included in the register of raw materials suitable for the production of wood pellets, since they are not classified as wood, but are classified as grass. That is, it is impossible to obtain ENplus and DIN+ certificates for pellets made from miscanthus and bamboo.
In general, limiting the ash content of raw materials is a purely abstract and relative requirement. For example, at power plants in the Netherlands, Belgium, Denmark, Poland and other countries, pellets from straw and sunflower husks, olive pits, shells of nuts and coffee beans and other biomass, the ash content of which was several times higher than the ash content of wood pellets, were burned together with coal. Another example: the Bionet company from the Arkhangelsk region produces lignin pellets (see LPI No. 3 (133), 2018). This is the first project implemented in Russia for the disposal of hydrolysis production waste - lignin. Lignin granules, in comparison with classic wood granules, are characterized by high calorific value (21-22 MJ/kg), but also by high ash content - 2.4%. This, however, did not prevent Gazprombank, the beneficiary of the project, from starting sales of these pellets to Denmark and France after a presentation in Copenhagen at a business meeting at the Trade Representation of the Russian Federation in Denmark in the spring of 2018.
The high ash content of granules used in low-power boilers requires only frequent extraction of ash from the ash pit, which, as a rule, serves as fertilizer for the garden.
And when pellets are burned together with coal at large thermal power plants, high strength is not required, since they, like coal, are first passed through crushers and fed into the combustion zone of the boiler in a fine fraction. So the high strength of the granules will only increase energy costs.
As practice shows, it is possible to produce pellets of the highest quality from hardwood or a mixture with coniferous wood. Mixed raw materials in a certain proportion allows us to achieve pellet quality that meets ENplus A1 standards. Additives and steam pre-treatment can also be used or omitted. The effect will depend on the quality and type of raw materials used, technological equipment in production and, of course, on the professionalism of the technologist and other specialists.
Sergey Perederi, s.perederi@ eko-pellethandel.de
IAA "Infobio" learned about this based on information received at the Technical University of Cottbus. The project is financed by the European Union
A project for the production of a new type of biofuel - fuel pellets from lignin - was launched in Germany at the Technical University of Cottbus together with the Biomass Research Center in Leipzig and one company producing technological equipment.
According to experts, the new project will finally make it possible to produce high-quality fuel granules (pellets) or briquettes from hydrolyzed lignin on an industrial scale.
The pilot project will be launched in June 2013. Funding is provided by EU grants under the environmental protection program.
For many years, hundreds of scientific organizations around the world have been engaged in research and development in the field of utilization of hydrolytic lignin. Many of them have already been introduced into industry over the years. Recently, these works have become relevant due to the increased interest in solving environmental problems and in the industrial use of biomass in general in the energy sector. But without serious government support, most likely “the dump will still be there.”
Russia
As for Russia, the reserves of hydrolytic lignin in the Russian Federation, amounting to tens of millions of tons, are comparable to other waste from wood processing - bark, sawdust, etc.
It is interesting that lignin differs from wood waste in its greater homogeneity and, most importantly, in greater concentration (for example, dumps near hydrolysis plants). Due to the almost complete absence of its disposal, problems are created from an environmental point of view and with its storage.
At most hydrolysis and biochemical plants, lignin is disposed of in dumps and pollutes large areas.
Many European experts, visiting such plants, emphasize that nowhere in Europe have they seen such a colossal concentration of unused energy raw materials.
According to the data available in the literature, the use of hydrolytic lignin as a chemical raw material in the CIS does not exceed 5%. And according to the International Lignin Institute, no more than 2% of technical lignins are used in the world for industrial, agricultural and other purposes. The rest is burned in power plants or disposed of in dumps.
Problem
The problem of recycling hydrolytic lignin has been the main one for the industry since the 30s. And although scientists and practitioners have long proven that excellent fuel, fertilizers and much more can be obtained from lignin, over the many years of the existence of the hydrolysis industry in both the USSR and the CIS, it has not been possible to use lignin in full.
The difficulty of industrial processing of lignin is due to the complexity of its nature, as well as the instability of this polymer, which irreversibly changes its properties as a result of chemical or thermal effects. The waste from hydrolysis plants does not contain natural lignin, but largely modified lignin-containing substances or mixtures of substances that have high chemical and biological activity. In addition, they are contaminated with other substances.
Some processing technologies, for example, the decomposition of lignin into simpler chemical compounds (phenol, benzene, etc.), with comparable quality of the resulting products, are more expensive than their synthesis from oil or gas.
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