Raw materials for pellets: main types and requirements. Pellets from wood processing waste (hydrolytic lignin) and the method of their production Comparison of pellets from lignin and wood

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Pellets are high-energy granules used as solid fuel for domestic boilers and low-power industrial boiler houses.

Initially, designs for creating pellets from plant waste straw were used in the production of feed for livestock needs.

Later, the same equipment began to be used to create fuel pellets, and the area of ​​raw materials for their production expanded significantly, including all solid waste that can burn.

What are fuel pellets made from?

The best and most common raw materials for making pellets are waste wood species: pine needles and larch.

In industrial production, everything is used: sawdust, microchips and slabs, as well as any waste from woodworking production.

The main types of raw materials for the production of fuel pellets:

• substances after wood processing;
• substances and debris from agriculture: straw, corn stalks, seed husks and rice hulls;
• substances of large furniture production.

Stages of pellet production

The complete technological process for producing pellets can be divided into six stages:

1. Preparation of raw materials and crushing. Wood raw materials are divided into 2 categories - pure elements and bark. This is required to produce granules of different quality compositions. Initially, the raw materials are chopped to the level of chips, and then the granules are brought to 4 mm using a hammer chopper.
2. Drying the crushed material. It is sent to the drying drum, where the humidity is reduced from 50% to 15%. The process takes place under the influence of hot air with a temperature of 400C. This stage is very critical; if the permissible T is exceeded, destruction of an important component of wood - lignin, which is responsible for the strength parameters of energy granules, can occur.
3. Hydration. The ingredients are compressed into pellets through mechanical interlocking and lignin polymerization. This requires the presence of conditions such as pressure, temperature, moisture in the form of steam.
4. Granulation. The granulator device is the basic one in the pellet complex and consists of a motor, flat or drum dies, rollers for squeezing out granules, and knives for cutting them.
5. Cooling of granules. As a result of friction, the granules in the pelletizer are heated to 100 C, the technological process involves their cooling, after which they acquire the necessary hardness.
6. Package. The resulting pellets are packaged in huge bags - “big bags”, with a capacity of 500 to 1000 kg, and in consumer packaging - bags of 25 kg. Wholesale purchasing for industrial purposes involves dispensing granules in bulk into specialized receivers.

Where are pellets used, which ones are better and how to store them

A large area of ​​application for pellets is household heat power. Due to their high energy properties, they can be burned in any solid fuel boilers.

Western and domestic industry have developed long-burning boilers specifically for this type of fuel with full automation of thermal engineering processes for generating thermal energy for heating and hot water needs.

The ash content of the granules is relatively low; after the combustion process, cinders remain, which have found their use as a natural fertilizer.

Therefore, fuel pellets do not have a large amount of mineral impurities, and during production, care is taken to ensure that they do not contain metal inclusions.

Pellets can be distinguished by quality based on their color, which is influenced by raw material waste:

1. Black color is obtained with a high content of bark, rot and non-compliance with technology.
2. Gray granules come out of unbarked wood.
3. Light, made from good wood. They have the greatest heat transfer, do not break down to the same extent, and have a higher price than the first two granule options.

Pellets should be stored in dry, ventilated areas. Indoor air temperature does not matter. The most important thing is that the bags of granules do not come into contact with the soil or concrete. The best location is on wooden pallets.

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 biofuel.

– 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.

03/16/2016 — Miscellaneous

The main material for the production of pellets is wood. But now many enterprises are switching to the use of other types of raw materials. Thus, in the Arkhangelsk region, the first plant in Russia for the production of fuel pellets from lignin was commissioned. In terms of its purpose, the final product is similar to traditional wood pellets. The pellets will be used as fuel for industrial boilers, heat and electricity generation. The enterprise is organized on the basis of a former hydrolysis plant and is one of the largest in Europe. Lignin is a by-product of wood processing in the pulp and paper and hydrolysis industries. It is a homogeneous mass with a moisture content of 50 - 70%, the main element of which is sawdust. Leading world experts have long agreed that lignin is an excellent raw material for the production of biofuel. When burned, it emits little smoke, serves as an excellent substitute for charcoal and coke, and is used as a reducing agent in ferrous and non-ferrous metallurgy. In Russia, in most cases, lignin, as a by-product, was simply not used anywhere. Mostly it was stored and sent to landfills. With the new pellet production plant, this raw material will get a second chance at life, and the country’s bioenergy industry will be another incentive for further development. If you are looking for a promising line of business, pay attention to the biofuel production sector. The industry is developing rapidly, is actively supported by the Russian government, and is considered a promising area of ​​the economy. All necessary equipment for the production of pellets can be purchased in Russia on favorable terms at Doza-Gran. The company is an expert in the bioenergy industry and occupies a leading position in the country's market.

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 found that the ash content of 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 more and more high-molecular 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

CHEMISTRY AND TECHNOLOGY OF WOOD PROCESSING

V. S. Boltovsky, Doctor of Technical Sciences, Professor (BSTU)

COMPOSITION OF HYDROLYZED LIGNIN FROM DAMPS OF JSC "BOBRUISK BIOTECHNOLOGY PLANT"

AND RATIONAL DIRECTIONS FOR ITS USE

The composition of hydrolytic lignin from the dumps of OJSC “Bobruisk Biotechnology Plant” was studied. It was shown that as a result of long-term storage, there was a decrease in the total content of polysaccharides with significantly less degradation of lignin itself. The main areas of use of hydrolytic lignin are considered and recommendations are given on the most promising and rational areas of its utilization: obtaining fuel briquettes and pellets, organo-mineral fertilizers, sorbents.

The composition of a hydrolytic lignin from dumps of JSC Bobruisk Plant of Biotechnologies is under investigation. It is shown that long storage of lignin resulted in the reduction of the total content of polysaccharides at significantly smaller degradation of the actual lignin. The main directions of use of a hydrolytic lignin are considered, and recommendations about the most perspective and rational directions of its utilization are made: receiving fuel briquettes and pellets, organo-mineral fertilizers and sorbents.

Introduction. Lignin of cellular tissue of plant biomass is a high-molecular natural polymer of aromatic structure, which, during hydrolytic processing as a result of polycondensation transformations, forms a three-dimensional network structure and is a complex complex, including secondary aromatic structures (lignin itself, significantly changed during hydrolysis), part of non-hydrolyzed polysaccharides and non-washed monosaccharides , substances of the lignohumic complex, mineral and organic acids, ash elements and other substances.

The problem of recycling hydrolytic lignin has existed since the creation of the industry, and has not been fundamentally solved to this day, despite numerous methods of its processing, including those implemented in industry.

The main directions for processing hydrolytic lignin are: use in its natural form (in ferrous and non-ferrous metallurgy, in the production of lightweight refractory products - as a burn-out additive, in the production of household fuel, as an adsorbent, etc.), after thermal processing (production of lignin, active and granulated coals), after chemical processing (production of nitrolignin and its modifications, collactivite, biologically active substances - ammonium salts of polycar-

bonic acids and lignostimulating fertilizers, medicinal lignin and “polyphepane”, used as an enterosorbent for the prevention and treatment of diseases of the gastrointestinal tract of animals and humans instead of activated carbon), as well as as an energy fuel.

On the territory of the Republic of Belarus, in dumps that occupy significant areas and pose a danger to the environment, a significant amount of hydrolytic lignin has accumulated, sufficient for industrial processing.

Information published in the literature characterizes the chemical composition and properties of hydrolytic lignin obtained after hydrolytic processing of plant raw materials. For a qualified decision on the most rational ways to use lignin from dumps, it is necessary to determine its properties and select the most promising directions for its processing.

Main part. For the analysis, we used samples of hydrolytic lignin selected in accordance with the requirements of TU BY 004791190. 005-98 from the dump of the Bobruisk Biotechnology Plant OJSC, located in the village of Titovka at the pilot industrial site for field drying of lignin.

Determination of the component chemical composition of samples of hydrolyzed lignin and briquettes and pellets made from it was carried out

analysis methods adopted in wood and cellulose chemistry and hydrolysis production.

Thermogravimetric analysis of samples of pine, birch wood and hydrolytic lignin was carried out on a TA-4000 METTLER TOLEDO device (Switzerland) under the following conditions: sample weight 30 mg, temperature rise rate 5°C/min in the range 25-5 00°C, air blowing 200 ml/min.

The results of determining the content of the main components in samples of hydrolyzed lignin from the dump are given in Table. 1.

Comparison of the results of the analysis of hydrolytic lignin from dumps with the average composition of lignin obtained directly after hydrolytic processing of wood (Table 2) shows that as a result of long-term storage, there was a decrease in the total content of polysaccharides with significantly less degradation of lignin itself.

At the same time, hydrolyzed lignin contains the same main components as wood (Table 3), but a smaller amount of polysaccharides and a larger amount of lignin itself that is not hydrolyzed during hydrolytic treatment, i.e. it is wood after hydrolysis treatment (plant biomass).

The results of thermogravimetric analysis of wood and hydrolytic lignin (mass loss and differential thermo-gravimetry characterizing the rate of mass loss) showed that thermal decomposition

pine and birch wood and lignin hydrolysis occur similarly:

In the temperature range of 25-100°C, free moisture is removed (weight loss of pine and birch wood is 6.26.4%, respectively, hydrolytic lignin - 3.8-4.2%);

At temperatures above 100 and up to 300°C, desorption of bound water occurs with a loss of wood mass of 4.2-4.3% and hydrolytic lignin 4.1-5.5%;

The maximum rate of wood mass loss, accompanied by its active thermal decomposition and mass loss, is observed at a temperature of 300°C, hydrolytic lignin -280°C, i.e. the main components of the original wood and wood after hydrolysis treatment (hydrolytic lignin) burn in almost the same temperature range ;

With a further increase in temperature, deeper destruction, weight loss and carbonization occurs with the formation of carbon residue in the amount of 2.3-5.5% when burning wood and 3.9-5.9% - hydrolytic lignin.

The results of thermogravimetric analysis confirm the results and conclusions made based on the determination of the chemical component composition of wood and hydrolytic lignin that hydrolytic lignin is wood after hydrolysis treatment and is similar in properties to wood during combustion.

Table 1

% by weight of absolutely dry matter

Name of component Average values ​​in samples taken at depth, m

Total polysaccharides, including: 21.51 19.61 17.67

Easily hydrolyzed 1.63 1.65 1.80

Difficult to hydrolyze 19.88 17.96 15.87

Cellulose 18.86 17.04 19.95

Lignin 47.94 52.71 49.32

Ash 9.56 5.65 10.61

Acidity (in terms of H2SO4) 0.1 0.1 0.1

table 2

Polysaccharides 12.6-31.9 19.9

Lignin itself 48.3-72.0 57.1

Acidity (in terms of H2SO4) 0.4-2.4 -

Ash content 0.7-9.6 -

Note. The paper presents data on the determination of hydrolytic lignin at the Bobruisk hydrolysis plant; as polysaccharides - contains only cellulose.

Chemical composition of wood of various species

Table 3

Name of component Content, % by weight of absolutely dry matter

Spruce Pine Birch Aspen

Total polysaccharides, including: 65.3 65.5 65.9 64.3

Easily hydrolyzed 17.3 17.8 26.5 20.3

Difficult to hydrolyze 48.0 47.7 39.4 44.0

Cellulose 46.1 (44.2) 44.1 (43.3) 35.4 (41.0) 41.8 (43.6)

Lignin 28.1 (29.0) 24.7 (27.5) 19.7 (21.0) 21.8 (20.1)

Ash 0.3 0.2 0.1 0.3

* Cellulose content without hemicelluloses and lignin is given in parentheses according to the source.

The uses of hydrolytic lignin are varied. Promising for industrial production are, for example, products based on its high sorption properties (sorbents, including enterosorbents for medical purposes - medicinal lignin and polyphepane), activated carbons, long-acting fertilizers and other products) and its calorific value (in quality of fuel). The calorific value of hydrolytic lignin at a moisture content of 60% is 7750 kJ/kg, at 65% - 6150 kJ/kg and at 68% - 5650 kJ/kg. The average calorific value of absolutely dry lignin is 24,870 kJ/kg.

Currently, the enterprise subordinate to JSC Bobruisk Biotechnology Plant has mastered the production of fuel briquettes (TU BY700068910.019-2008) and pellets from hydrolytic lignin.

The results of determining the content of the main components of briquettes and pellets made from hydrolytic lignin are given in table. 4.

As can be seen from the table. 4 results, in terms of the content of the main components, briquettes and pellets practically do not differ from the hydrolytic lignin from which they are made, and from wood, but have a lower content of polysaccharides and more lignin.

The large-scale use of hydrolytic lignin in agriculture is promising as an organic fertilizer (in its natural form), organo-mineral fertilizer

niya (in a mixture with mineral components or waste from the microbiological industry - waste cultural liquid after fermentation of microorganisms, or in a mixture with various mineral substances after composting - vermicompost), lignostimulating fertilizer (after modification by oxidative destruction in various ways with simultaneous enrichment with nitrogen and microelements ).

The use of fertilizers based on hydrolytic lignin provides:

Improving the physical properties of the soil and the conditions for the development of saprophytic fungi;

Creation of a loose surface layer that ensures normal water-air exchange;

Activation of nitrification processes in the soil;

Prolonged action, creating conditions for the retention of nutrients (due to the high adsorption capacity of lignin) and their gradual consumption by the root system of plants and preventing their rapid leaching by precipitation and soil waters;

Accelerating the growth and increasing the yield of agricultural plants (for example, adding lignin in a mixture with ammonia or urea increases the yield of winter rye by 1617%, lignostimulating fertilizer in the amount of 0.4 t/ha leads to an increase in potato yield by 15-30%).

Table 4

Component name Briquettes Pellets

Total polysaccharides, including 19.25 19.67

Easily hydrolyzed 2.13 2.17

Difficult to hydrolyze 17.12 17.50

Cellulose 15.90 16.81

Lignin 46.41 44.73

Ash 8.97 9.30

Acidity (in terms of H2SO4) 0.1 0.1

Sorbents obtained on the basis of hydrolytic lignin have the following advantages:

They have a high sorption capacity. The specific surface area of ​​the original hydrolyzed lignin containing 15.2% cellulose is 10.14 mg/g, and the enterosorbent for medical use (medicinal lignin) obtained on its basis after appropriate processing is 16.3 mg/g, the pore volume of the original lignin is 0.651 cm3/g, medicinal lignin -0.816 cm3/g. The total pore volume of polyphe-pan is 0.8-1.3 cm3/g. The distribution coefficients of cesium and strontium between their model solutions and the enterosorbent reach 400900, and the sorption of microorganisms from culture media is 108 cells/g of preparation;

They have a low cost, because they are a residue after hydrolytic processing of plant biomass;

They are natural plant biomass;

They have low ash content when burned.

Possible applications:

Purification of technogenic solutions, industrial and storm water;

Use for medical purposes as an enterosorbent;

Sorption of liquid low- and medium-level radioactive waste;

Use in purifying gases from radionuclides and heavy metals;

Use in installations for individual and collective use for water purification;

Isolation of rare earth, precious and non-ferrous metals;

Other areas of application are as natural phytosorbents.

The most rational from the point of view of large-scale processing of hydrolytic lignin in the Republic of Belarus, in addition to the production of briquettes and pellets for use as fuel, is the production of sorbents, including for the treatment of industrial wastewater, and organic or organo-mineral fertilizers.

Literature

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2. Waste-free production in the hydrolysis industry / A. Z. Evilevich [et al.]. M.: Lesnaya prom-st, 1982. 184 p.

3. Epshtein Ya. V., Akhmina E. I., Raskin M. N. Rational directions for the use of hydrolytic lignin // Wood chemistry, 1977. No. 6. P. 24-44.

4. Obolenskaya A.V., Elnitskaya Z.P., Leonovich A.A. Laboratory work on the chemistry of wood and cellulose. M.: Ecology, 1991. 320 p.

5. Emelyanova I.Z. Chemical and technical control of hydrolysis production. M.: Lesnaya prom-st, 1976. 328 p.

6. Bogomolov B. D. Chemistry of wood and the basics of chemistry of high-molecular compounds. M.: Forest industry, 1973. 400 p.