RU2733947C1 - Method of producing fuel briquette - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method of producing a fuel briquette from plant biomass, comprising steps of: i) providing a biomass of plant origin; ii) pyrolysis of vegetal origin biomass to obtain carbonised biomass and pyrolysis liquid; iii) separating the pyrolysis liquid into a water-containing fraction and a resin fraction, wherein the resin fraction is immiscible with the water-containing fraction; iv) forming the mixture by mixing the carbonised biomass with the water-containing fraction and the resinous fraction of the pyrolysis liquid; v) moulding charge into briquette; vi) annealing the charge briquette, wherein at stage iv) forming the charge comprises: mixing carbonized biomass with water-containing fraction of pyrolysis liquid to obtain a first mixture; mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge.

EFFECT: technical result of present invention consists in production by ecologically and economically effective method of vegetal origin biomass briquette, having proper mechanical strength and calorific capacity, capable of replacing traditional coke based on hard coal.

18 cl, 3 dwg, 5 tbl, 8 ex

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of the fuel and energy industry, in particular, to a method for producing a fuel briquette obtained from renewable raw materials. The invention can be applied in fuel, smelting furnaces for melting and / or recovery of mineral raw materials of natural and / or technogenic origin.

LEVEL OF TECHNOLOGY

In connection with the ever-growing needs of modern industry for energy resources, as well as the tightening of measures for carbon dioxide emissions into the atmosphere, there is a need to search for new energy sources, alternative to minerals. Renewable sources of raw materials of plant origin can become such an alternative. Since the processing of raw materials of plant origin without participation in the conversion process of additional chemical reagents is inherently a technology with a zero carbon balance, that is, all potentially emitted carbon dioxide is absorbed by plants during photosynthesis during their growth, the advantage of processing renewable raw materials of plant origin in comparison with processing minerals, during which carbon dioxide is also released, becomes evident.

In addition, the processing of waste of raw materials of plant origin into a useful source of energy, in addition to expanding the raw material base for obtaining energy resources, also solves issues related to the costs of storing and disposing of such waste.

Thus, in the modern scientific and technical community, searches are underway to identify and use new energy resources, as well as, if possible, obtain them in a stable form that does not change their characteristics during transportation. In particular, for fuel briquettes, pellets and other types of molded fuel, an important characteristic is the strength of the resulting fuel product along with maintaining the necessary calorific value for the possibility of using this type of solid fuel for its intended purpose. Calorific value is understood as the heat of complete combustion of a unit mass of a substance.

From the prior art, methods are known for producing fuel briquettes obtained from various raw material sources, including plant biomass.

There is a known method of manufacturing fuel briquettes from biomass (patent RU 2484125 C1, 06/10/2013), in which biomass is used as a raw material in the form of peat, sawdust, which is subjected to heat treatment without air access at a temperature of 200-500 ° C, obtaining carbonaceous residue and pyrolysis condensate, in which dextrin is dissolved, thus obtaining a binder, which is mixed with a carbon residue to form a fuel briquette from the resulting mixture and dried at room temperature for 2-5 days.

The disadvantage of this method is the use of a chemical reagent in the form of dextrin to form a binder, which leads to an increase in the cost of the fuel product and the complexity of the process as a whole, as well as a low heat of combustion of the briquette, which lies in the range of 7300 - 20,000 kJ / kg.

There is a known method of obtaining moisture-resistant briquettes (patent US5244473A, 09/14/1993), in which particles such as coal, coke and / or brown coal are mixed with phenol-formaldehyde resin and polyisocyanate in the presence of a catalyst containing organic nitrogen, and the mixture is subjected to continuous briquetting with the formation of these particles of briquettes, bonded and coated with phenol-urethane polymer.

The disadvantage of this method is the use of reagents for the formation of a binder, which leads to an increase in the cost of the resulting briquettes and the complexity of the process as a whole.

There is a known method for the manufacture of briquette fuel (patent RU 2375414 C1, 10.12.2009), which discloses the use of low-temperature semi-coking resin obtained at temperatures up to 650 ^° C during coal pyrolysis, to obtain heat-resistant briquettes in an oxidizing environment at temperatures of 150-300 ^{° C.} mixed with a binder carbonaceous raw material in the form of coke breeze, and / or pitch coke breeze, and / or petroleum coke breeze, and / or anthracite breeze, and / or coal breeze.

The disadvantage of this method is a narrow raw material base for the manufacture of briquettes, which does not solve the problem of utilization of substandard waste of lignocellulosic material, formed both as a result of agricultural activities and in the forest industry.

Thus, in the prior art, there is a problem of obtaining a fuel briquette of proper quality from renewable sources of raw materials of plant origin, capable of replacing the coke currently used in fuel, smelting furnaces, without deteriorating the environmental situation in terms of carbon dioxide emissions.

DISCLOSURE OF THE INVENTION

To solve the above problems and overcome the disadvantages in the existing inventions of the prior art, the authors of the present invention have identified a number of problems requiring attention to change the current situation in the art for the better.

The objectives of the present invention are:

- expansion of the raw material base for the manufacture of fuel briquettes for use in fuel furnaces,

- reduction of technological production costs,

- obtaining environmentally friendly fuel from available waste.

The technical result of the present invention consists in obtaining a fuel briquette from biomass of plant origin with characteristics that allow it to be used in fuel, smelting furnaces to create the necessary conditions for melting and / or recovery of mineral raw materials of natural and / or technogenic origin.

Also, one of the technical results of the present invention is to provide a new method for producing a fuel briquette from biomass of plant origin, which is economically beneficial from the point of view of obtaining finished briquettes and environmentally friendly.

One of the technical results of the present invention is also to obtain a fuel briquette from biomass of plant origin, having good strength and calorific value.

Another of the technical results of the present invention is the production of a fuel briquette from plant biomass having sufficient hot strength for use in a fuel / melting furnace, for example a cupola furnace.

Achievement of the claimed technical results is provided by a method for producing a fuel briquette from biomass of plant origin according to the present invention.

According to the present invention, there is provided a method for producing a fuel briquette from biomass of plant origin, comprising the steps of:

i) provide biomass of plant origin

ii) pyrolysis of biomass of plant origin to obtain carbonized biomass and pyrolysis liquid;

iii) separating the pyrolysis liquid into a water-containing fraction and a resinous fraction, the resinous fraction being immiscible with the water-containing fraction;

iv) form a charge by mixing the carbonized biomass with a water-containing fraction and a resinous fraction of the pyrolysis liquid;

v) forming the charge into a briquette;

vi) annealing the charge briquette,

and at stage iv) the formation of the charge includes:

- mixing the carbonized biomass with the aqueous fraction of the pyrolysis liquid to obtain the first mixture;

- mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge.

In one embodiment, there is provided a method further comprising drying the briquette at room temperature prior to step vi) for a period of 72 to 170 hours.

According to another embodiment, a method is provided in which, in step v), the charge is formed into a briquette by pressing.

According to another embodiment, a method is provided, in which the pyrolysis liquid in step ii) contains condensed vapors of a vapor-gas mixture obtained by pyrolysis of biomass of plant origin.

According to another embodiment, a method is provided in which the resinous and water-containing fractions of the pyrolysis liquid obtained in step iii) contain organic substances released during the pyrolysis of biomass of plant origin. At the same time, the content of organic matter in the resinous fraction is greater than the content of organic matter in the water-containing fraction.

According to another embodiment, there is provided a method, in which in step iii) the separation of the pyrolysis liquid into a water-containing fraction and a resinous fraction is carried out by settling. In this case, the settling is carried out within 24-48 hours.

According to another embodiment, there is provided a method in which in step iii) the separation of the pyrolysis liquid into a water-containing fraction and a resinous fraction is carried out by settling with simultaneous cooling of the pyrolysis liquid. In this case, the cooling of the pyrolysis liquid is carried out to the temperature of the pyrolysis liquid in the range from 20 to 40 ° C.

According to another embodiment, there is provided a method in which in step iv) the ratio of the amount of the hydrous fraction of the pyrolysis liquid to the amount of the resinous fraction of the pyrolysis liquid is from 4: 1 to 7: 1 by weight.

According to another embodiment, there is provided a method in which in step iv) the ratio of the amount of carbonized biomass to the amount of hydrous fraction of the pyrolysis liquid is from 0.76: 1 to 0.86: 1 by weight.

According to another embodiment, there is provided a method in which in step iv) the ratio of the amount of carbonized biomass to the amount of resinous fraction of the pyrolysis liquid is from 3.2: 1 to 6.1: 1 by weight.

According to another embodiment, there is provided a method in which in step v) a briquette is formed into a cube, wherein a through hole is formed in the central part of the cube. At the same time, the briquette is molded in the form of a cube with a side length in the range of 90-125 mm.

According to another embodiment, a method is provided, wherein step vi) sequentially comprises:

- keeping the briquette at a temperature of 150 ° C - 250 ° C for 18 hours;

- keeping the briquette at a temperature of 300 ° C for 5-6 hours;

- keeping the briquette at a temperature of 500 ° C for 2-3 hours;

- keeping the briquette at a temperature of 650-700 ° C for 2-5 hours.

According to another embodiment, a method is provided further comprising compacting the charge in step iv). In this case, the compaction of the charge is carried out in a roller mixer.

According to another embodiment, a method is provided, in which in step ii) the pyrolysis liquid is obtained by condensing the vapor of a vapor-gas mixture obtained by pyrolysis of biomass of plant origin. In this case, the condensation of the vapor of the vapor-gas mixture is carried out in a scrubber, and the scrubbing liquid in the scrubber is a pyrolysis liquid.

According to another embodiment, a method is provided wherein step iv) is carried out in a paddle mixer.

According to another embodiment, there is provided a method in which, in step ii), the vapor of the vapor-gas mixture is pre-cooled with recycle gases, the recycle gases being the non-condensable part of the vapor-gas mixture leaving the scrubber.

According to another embodiment, there is provided a method in which in step iv) 5-15 wt.%, Preferably 5-10 wt.%, Of coke chips are added to the carbonized biomass before mixing with the aqueous and resinous fraction, based on the total weight of the carbonized biomass, and coke chips.

According to another embodiment, there is provided a method in which in step vi) the briquette is annealed in a temperature range of 150-900 ° C.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 illustrates the surface microstructure of carbonized biomass after annealing.

Figure 2 illustrates the microstructure of carbonized husk biomass.

Figure 3 illustrates the microstructure of carbonized biomass from wheat straw.

DETAILED DESCRIPTION OF THE INVENTION

The inventors of the present invention have surprisingly found that by separating the pyrolysis liquid obtained from the pyrolysis of plant biomass into a water-containing fraction and a resinous fraction that does not mix with the water-containing fraction, and using the obtained fractions of the pyrolysis liquid to form a charge, it is possible to obtain a fuel briquette having necessary strength, hot strength and calorific value for use in fuel, smelting furnaces. Also, in view of the fact that the method uses pyrolysis products to form a charge without the use of separate reagents for binders, it is possible to obtain an economically advantageous method for producing a fuel briquette from biomass of plant origin. Further, in view of the fact that the method uses and utilizes a pyrolysis liquid, which is traditionally a waste of the pyrolysis / carbonization process, it becomes possible to develop a method for producing a fuel briquette from biomass of plant origin, which has a minimal impact on the environment. At the same time, according to the present method, there is no need for the disposal of the pyrolysis liquid, which also makes it possible to obtain an economically advantageous method for obtaining a fuel briquette from biomass of plant origin.

Any known plant biomass can be used as starting material. These materials can be supplied by enterprises of forestry or agriculture, or enterprises of any other industry where biomass of plant origin is produced or found. In particular, a source of plant biomass of natural origin can be the waste of the oil industry - the husk of sunflower seeds, as well as the outer shells of the grain, which are obtained as a result of the hulling or peeling of grains and seeds of other plant crops. Wood chips, wood chips, straw and husks of wheat, rapeseed, rye, oats, barley, rice, corn, etc. can also be used as a starting material.

It is characteristic of the proposed method that a low-grade and low-calorie material can be supplied at the input of the technological process, while the output is a high-quality product with an increased calorific value in comparison with the starting material.

The claimed method for producing a fuel briquette from biomass of plant origin is as follows:

i) provide biomass of plant origin

ii) pyrolysis of biomass of plant origin to obtain carbonized biomass and pyrolysis liquid;

iii) separating the pyrolysis liquid into a water-containing fraction and a resinous fraction, the resinous fraction being immiscible with the water-containing fraction;

iv) form a charge by mixing the carbonized biomass with a water-containing fraction and a resinous fraction of the pyrolysis liquid;

v) forming the charge into a briquette;

vi) annealing the charge briquette,

and at stage iv) the formation of the charge includes:

- mixing the carbonized biomass with the aqueous fraction of the pyrolysis liquid to obtain the first mixture;

- mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge.

For the implementation of the method in stage ii) is the pyrolysis of biomass of plant origin at a temperature of 450-500 ° C. Thermal decomposition under oxygen-deficient conditions is a known technique for producing a carbonized solid and a pyrolysis liquid. Therefore, it will not be difficult for a person skilled in the art to carry out this step of the method, and therefore this step is not discussed in detail in the present invention. However, it should be noted that it is precisely due to pyrolysis that it becomes possible to obtain a fuel briquette with a proper calorific value.

The pyrolysis liquid was obtained by condensation of the vapor of a vapor-gas mixture formed as a result of the thermal decomposition of the raw material of plant origin in the condensation system with the formation of liquid pyrolysis products (pyrolysis liquid) and non-condensable gases. By condensing the vapor of the vapor-gas mixture, a pyrolysis liquid is obtained, which is then used as a material for binding the carbonized biomass, which subsequently makes it possible to form a charge and obtain a fuel briquette with proper strength and proper calorific value. The authors of the present invention have found that from the point of view of obtaining a pyrolysis liquid, it is preferable to use a scrubber for condensing the vapor of a vapor-gas mixture. A part of the previously obtained pyrolysis liquid can be used as a scrubbing liquid, due to which it is possible to additionally avoid an increase in the cost of the process due to the absence of the need to use an additional refrigerant, avoid waste generation and additionally enrich the pyrolysis liquid obtained in the scrubber with organic carbon-containing compounds.

In one embodiment, the vapor-gas mixture is further pre-cooled before entering the scrubber. Pre-cooling is carried out by passing the recirculated gases through the steam-gas mixture obtained as a result of pyrolysis of biomass of plant origin. At the same time, the recirculated gases represent the non-condensable part of the vapor-gas mixture leaving the scrubber, which was cooled in the scrubber, but did not undergo condensation, but remained in the form of non-condensable gases. This non-condensable part of the steam-gas mixture in the form of recirculated gases is taken from the scrubber and sent to the preliminary cooling of the vapor of the steam-gas mixture obtained after pyrolysis. By using the non-condensable part of the vapor-gas mixture as recycle gases for pre-cooling the vapor of the vapor-gas mixture, it is possible to further achieve improved condensation of the vapor of the vapor-gas mixture to obtain a better yield of the pyrolysis liquid. Since the recycle gases leaving the scrubber are by-products of the process, an improved process from an environmental and economic point of view can be achieved through their reuse.

The pyrolysis liquid obtained as a result of pyrolysis was used to bind the carbonized biomass. However, when using all the pyrolysis liquid, the authors of the present invention failed to obtain fuel briquettes of proper quality, since it was not possible to obtain a homogeneous mass of the charge, and the briquettes obtained as a result of molding and annealing of the resulting charge were subject to severe cracking.

As a result of numerous studies, the authors of the present invention found that it is expedient to separate the pyrolysis liquid obtained as a result of pyrolysis into fractions - a water-containing fraction and a resinous fraction immiscible with the water-containing fraction, by settling with cooling to the temperature of the pyrolysis liquid in the range from 20 to 40 ° C. ... Moreover, the output of the water-containing fraction is 27-38% wt., And the resinous fraction, respectively, 10-21% wt. in relation to the mass of the original plant material (calculated on dry matter). In this case, the yield of carbonized biomass is 25-36% wt. The rest falls on gaseous products, the yield of which can be about 20-23% wt.

The content of the identified classes of chemical compounds was determined by gas chromatography-mass spectrometry in the aqueous and resinous fractions of pyrolysis liquids.

The water-containing fraction is an aqueous solution containing organic / carbon-containing substances / compounds of a predominantly acidic nature: acids, phenols. Also, this fraction contains a small amount of ketones, alcohols, heterocyclic compounds.

The resinous fraction of the pyrolysis liquid is an organic high-carbon phase, mainly enriched in aromatic, phenolic, ester compounds, as well as higher carboxylic acids.

The obtained data are consistent with literature sources (Kuzmina R.I. Pyrogenetic processing of some wood waste and seed peeling waste / R.I. Kuzmina, S.N. Shtykov, K.E. Pankin, Yu.V. Ivanova, T.G. Panina // Chemistry of vegetable raw materials. - 2010. - No. 3. - P. 61-65.), Where it is noted that materials of wood and non-wood origin in similar technological conditions give a set of pyrolysis products that are similar in composition.

Thus, the water-containing and resinous fractions are characterized by the presence of carbon-containing compounds, which can additionally enrich the resulting fuel briquette with carbon to increase its calorific value / calorific value.

To assess the amount of coke residue formed from the pyrolysis liquid, formed by thermal action on the pyrolysis liquid, a thermogravimetric analysis of the resinous fraction of the pyrolysis liquid was carried out, due to the higher content of carbon-containing compounds in it in comparison with the water-containing fraction.

During thermal decomposition, the carbonized residue of the resinous fraction of the pyrolysis liquid is 7-10% of the initial mass of the resinous fraction. The total weight loss of the resinous fraction during pyrolysis at 600 ° C is 90-93% wt.

To assess the possibility of using a pyrolysis liquid in the charge without lowering the calorific value / heat of combustion of the fuel briquette, the heat of combustion of the batch samples obtained by mixing the resinous fraction of the pyrolysis liquid with carbonized biomass without briquetting and pressing was determined.

Samples of the charge were prepared with different contents of the resinous fraction of the pyrolysis liquid in 10, 30, 50, 70, 100% wt. followed by annealing in ceramic crucibles to a temperature of 900 ° C.

The experimental results are presented in table 1.

Table 1. Physicochemical indicators of samples of the charge with the resinous fraction of the pyrolysis liquid of the husk of sunflower seeds.

Resinous fraction content of pyrolysis liquid,% Ash content, mass. %. Calorific value (calorific value), kJ / kg, ten 8.9-9.1 28950-29010 50 7.1-7.5 29640-29705 70 6.1-6.7 30000-30070 100 2.0-2.6 29360-29420

As can be seen from table 1, the resinous fraction of the pyrolysis liquid does not lead to a deterioration in the calorific value of the sample. In addition, Table 1 shows that the introduction of a resinous fraction of the pyrolysis liquid can lead to a decrease in the ash content of the sample, which is an important factor for the use of a fuel briquette in fuel and smelting furnaces.

Moreover, the inventors have found that due to the fact that the resinous fraction contains a large amount of carbon-containing compounds, it becomes possible to generally obtain the proper calorific value of the carbonized biomass and, as a consequence, the fuel briquette by adding a resinous fraction of the pyrolysis liquid to the biomass.

Table 2 shows the results of tests to determine the main parameters characterizing the properties of carbonized biomass obtained as a result of pyrolysis.

Table 2. Physicochemical indicators of carbonized biomass

Indicator name Test result value Ash content * based on thermogravimetry results when heated to 900 ° C at a heating rate of 10K / min 10.3-10.9% Calorific value (calorific value) ** 29953-31827 kJ / kg Humidity* 2.1-2.8% Volatile content 9.8-10.5%

* parameter values can be determined by any known method in the art, for example, according to GOST 33625

** calorific value was determined using an IKA 5000 bomb calorimeter.

The specified data refer to the carbonized biomass from sunflower husk obtained by pyrolysis. At the same time, it should be noted that the indicators for other sources of biomass will be comparable.

Comparison of the data from Tables 1 and 2 indicates the comparability of the results in terms of calorific value and indicates the possibility of using the pyrolysis liquid in the formation of a fuel briquette with obtaining the proper calorific value.

When obtaining a fuel briquette by briquetting a charge consisting of carbonized biomass and only a resinous fraction of a pyrolysis liquid, the authors of the present invention found that the addition of only a resinous fraction of a pyrolysis liquid to the carbonized biomass does not lead to a uniform redistribution of this fraction among the particles of carbonized biomass due to its high viscosity ... As a result, the formation of a uniformly mixed batch does not occur, and the batch is essentially not formed into briquettes. However, if a molded product is nevertheless obtained from such a non-uniform batch, the resulting product has very low and unsatisfactory strength due to the heterogeneity of the starting material.

The present inventors have found that in addition to the resinous fraction, it is also possible to add the aqueous fraction of the pyrolysis liquid to the carbonized biomass. Since the aqueous fraction of the pyrolysis liquid, as already mentioned above, also contains organic / carbon-containing compounds in its composition, which can further contribute to increasing the yield of the fuel briquette due to the carbonization of organic compounds, the authors of the present invention added the aqueous fraction to the carbonized biomass, thereby introducing it the composition of the charge.

In the course of numerous studies, the authors of the present invention have found that to obtain a fuel briquette containing a water-containing fraction and a resinous fraction of a pyrolysis liquid, which is of decisive importance for the formation of a final fuel briquette with a homogeneous structure formed after its annealing, the order of mixing the fractions of the pyrolysis liquid plays a role. the presence of both factions. As already mentioned above, the presence of only the resinous fraction does not lead to the formation of a product of adequate strength. For example, when drying at room temperature, crumbling of the briquette edges is observed, and during annealing, even a collapse of its edges. The authors of the invention see the reason for this phenomenon in the uneven mixing of the mixture due to the adhesion of the resinous fraction to the working elements of the mixer.

Mixing the carbonized biomass only with the hydrous fraction of the pyrolysis liquid leads to the possibility of forming the charge into briquettes, but the strength of the briquettes after annealing does not correspond to the required strength. According to the authors, this may be caused by a different coefficient of thermal expansion of the organic / carbon-containing mass of carbonized biomass and water with dissolved organic / carbon-containing substances contained in the water-containing fraction, which can lead to the initiation of cracks that increase during the passage of the entire annealing stage, and as a result of obtaining a briquette of insufficient strength.

At the same time, it was found that mixing the carbonized biomass with the water-containing fraction, and only the subsequent mixing of the resulting mixture with the resinous fraction leads to less adhesion of the resinous fraction to the working elements of the mixer, more homogeneous mixing of the mixture, which is confirmed by the data obtained as a result of studying the surface of the fuel briquette under microscopes obtained after annealing, where there is a uniform distribution of the resinous fraction between the particles of the carbonized biomass, which cannot be achieved without the participation of the aqueous fraction of the pyrolysis liquid. As a result, such a mixing and in this order of the aqueous and resinous fractions with the carbonized biomass leads to the production of a fuel briquette with a homogeneous structure, and with indicators of mechanical strength and heating value suitable for use in fuel, smelting furnaces.

Additionally, it was found that the possibility of obtaining a homogeneous plastic mass capable of being molded into briquettes is influenced by a certain amount of added aqueous fraction and resinous fraction of the pyrolysis liquid to the carbonized biomass at the stage of charge formation.

In the course of the experiments, the preferred briquette formulation was found, which allows molding the charge into briquettes, followed by obtaining briquettes with the proper mechanical strength and calorific value:

- the content of carbonized biomass is 38-43 wt. %;

- the content of the resinous fraction of the pyrolysis liquid is 7-12 wt. %;

- the content of the aqueous fraction of the pyrolysis liquid is 45-55 mass. %, more preferably 50 wt. %.

The content of each component of the charge is given based on the total weight of the charge.

Also, in order to ensure the molding of the charge into briquettes with the subsequent receipt of briquettes with proper mechanical strength and calorific value, it is preferable to use the following ratios:

the ratio of the amount of the aqueous fraction of the pyrolysis liquid to the amount of the resinous fraction of the pyrolysis liquid at the stage is from 4: 1 to 7: 1 by weight;

the ratio of the amount of carbonized biomass to the amount of the hydrous fraction of the pyrolysis liquid is from 0.76: 1 to 0.86: 1 by weight;

the ratio of the amount of carbonized biomass to the amount of resinous fraction of the pyrolysis liquid is from 3.2: 1 to 6.1: 1 by weight.

Such a composition of the charge contributes not only to obtaining a homogeneous plastic mass for briquetting and reducing the emission of dust during mixing, but also reduces the adhesion of the charge to the working elements of the mixer, which may be due to the formation of a colloidal system from the components of the mixture, which limits the contact of adhering particles with the working elements of the mixer.

The authors of the present invention have also found that to obtain a briquette with the required hot strength, coke chips can be added to the carbonized biomass at the stage of batch formation in an amount of 5-15 wt.%, Preferably 5-10 wt.%, Based on the total weight of the carbonized biomass. and coke chips. Along with an increase in the strength of the briquette, coke crumbs can additionally affect its reactivity, leading to its decrease. Also, the present inventors have found that the addition of coke chips (eg, coal-based coke coke) has a positive effect on the hot briquette strength, since the coal-based coke has a high strength value at elevated temperatures. At the same time, it was found that the addition of coke chips (for example, coke coke based on coal) is higher than 15% wt. leads to a decrease in the homogeneity of the charge after mixing the carbonized biomass with fractions of the pyrolysis liquid, which as a result leads to deterioration in the formation of the charge into a briquette.

Coke crumbs are added to the carbonized biomass before the addition of the aqueous fraction of the pyrolysis liquid, so that upon subsequent mixing with the aqueous fraction of the pyrolysis liquid to obtain the first mixture and mixing the first mixture with the resinous fraction of the pyrolysis liquid, a homogeneous charge is obtained in which the coke crumb is evenly distributed throughout the mass. As coke crumb, for example, coke crumb of coke based on coal, metallurgical coke can be used.

The inventors of the present invention have found that from the point of view of obtaining a separate aqueous and resinous fraction of the pyrolysis liquid, the separation of the pyrolysis liquid into a water-containing fraction and a resinous fraction is preferably carried out by settling. The separation can be carried out by other suitable methods, however, the use of the method of settling the pyrolysis liquid for its separation is economically feasible and makes it possible to separate the pyrolysis liquid into the water-containing fraction and the resinous fraction of the pyrolysis liquid, immiscible with the water-containing fraction of the pyrolysis liquid, which are subsequently used to obtain a fuel briquette with proper strength and calorific value. Additionally, the inventors of the present invention have found that for better separation of the pyrolysis liquid into these fractions, it is possible to settle the pyrolysis liquid with simultaneous cooling. In this case, even more preferable from the point of view of fractionation is cooling the pyrolysis liquid to a temperature in the range from 20 to 40 ° C. Also, it is preferable to settle the pyrolysis liquid for 24-48 hours for better separation.

According to the present invention, a pyrolysis liquid is obtained by condensation of vapors of a vapor-gas mixture obtained by pyrolysis of biomass of plant origin. This method of obtaining a pyrolysis liquid is the most efficient in terms of time and resource costs. The authors of the present invention have found that the most effective way to condense the vapor of a steam-gas mixture to obtain a pyrolysis liquid of the proper composition is condensation using a scrubber. Meanwhile, the scrubbing liquid in the scrubber is preferably a pyrolysis liquid that has been previously produced. By using a pyrolysis liquid as a scrubbing liquid, it is possible to avoid an increase in the cost of the process, while obtaining at the outlet of the scrubber a pyrolysis liquid having the proper composition for subsequent separation and mixing with the carbonized mass. At the same time, the inventors of the present invention have also found that the use of the pyrolysis liquid as a scrubbing liquid leads to an additional enrichment of the pyrolysis liquid obtained in the scrubber with organic / carbon-containing compounds, i.e. additional enrichment with carbon, which in turn makes it possible to obtain a fuel briquette with the required heating value.

According to the present invention, the vapor of the vapor-gas mixture formed during pyrolysis is also subjected to pre-cooling with recycle gases, and the recycle gases represent the non-condensable part of the vapor-gas mixture leaving the scrubber. By using the non-condensable part of the steam-gas mixture leaving the scrubber as cooling recycle gases, it is possible to provide a recycle process, which improves the environmental friendliness of the process as a whole. Also, the use of the non-condensable part of the vapor-gas mixture as cooling recirculated gases allows avoiding the rise in the cost of the process, since there is no need to use other refrigerants. At the same time, the preliminary cooling of the vapor of the vapor-gas mixture makes it possible to further improve the condensation of the vapor to obtain a pyrolysis liquid of the required composition.

Without limiting themselves by theory, the authors of the present invention believe that due to the presence in the fractions of the pyrolysis liquid organic / carbon-containing compounds / substances released during the pyrolysis of biomass of plant origin, it is possible to obtain a briquette with the necessary mechanical strength and calorific value. In the context of the present invention, the term “water-containing fraction” means a fraction of the pyrolysis liquid having an increased water content and a lower content of organic / carbon-containing compounds / substances in comparison with the resinous fraction of the pyrolysis liquid. In the context of the present invention, the term “resinous fraction” means a fraction of the pyrolysis liquid which is substantially free of water and has an increased content of organic / carbonaceous compounds / substances in comparison with the aqueous fraction of the pyrolysis liquid. The term "substantially free of water" means that the water content of the resinous fraction is 1 to 5% by weight. These fractions of the pyrolysis liquid do not mix with each other or essentially do not mix with each other without the application of mechanical force and at temperatures below 40 ° C. The term "calorific value" refers to the heat of complete combustion of a unit mass of a substance. By "organic / carbonaceous substances / compounds" is meant organic carbonaceous compounds. Hot strength is understood as the ability of the briquette to withstand temperatures up to 800 ° C when a load is applied to it without destruction for 40-60 minutes under the conditions of the cupola's operation.

In addition, it was revealed that the shape of the briquette also plays a role in obtaining a durable product with a given calorific value. It was experimentally found that flaky briquettes, the width or thickness of which is more than two to three times less than the length, such as the shape of a brick, do not lead to a product with the required mechanical strength. This shape of the briquette at the stage of annealing leads to cracking of the briquette. Experimentally, the most optimal shape of a briquette in the form of a cube with a side length in the range of 90-125 mm was established, which is achieved by pressing the charge with an effort on the press rod from 1 to 2 tons, as a result of which the volume of the briquette is reduced by 30%, followed by annealing in temperature range 150-700 ° C. Also, for a more uniform thermal effect at the annealing stage, a hole is provided in the central part of the cube. The role of the hole in the briquette cube is as follows:

- firstly, the presence of a hole promotes uniform heating of the briquette, which can reduce the stress at the contact areas between the particles of carbonized biomass due to the uniform thermal expansion of the charge components during the heating of the briquette. As a result, due to the absence of a thermal expansion difference within the briquette, cracking is prevented, since a more uniform shrinkage occurs, thus the shape also affects the production of a strong briquette.

- secondly, the perforation of briquettes will reduce emissions into the atmosphere due to an increase in the completeness of combustion of briquettes during their use, which contributes to the production of an environmentally friendly fuel product.

At the same time, it was found that making the hole in the fuel briquette such that the diameter of the hole to the side of the cube is 1: 4 makes it possible to obtain an additionally stronger and more environmentally friendly fuel product, as mentioned above.

Additionally, it has been found that the annealing of the fuel briquette should preferably be carried out in the temperature range of 150-900 ° C, more preferably 150-700 ° C to obtain a briquette of the required quality having proper mechanical strength and heating value.

Thus, mixing the carbonized biomass with the aqueous fraction of the pyrolysis liquid to obtain the first mixture and then mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge, which is molded, preferably formed into a cube, and subjected to annealing at a temperature of 150-900 ° C, more preferably at a temperature of 150-700 ° C, even more preferably at a temperature of 700 ° C, results in a durable fuel briquette with the required fuel calorific value.

It should be noted that the annealing of the briquette in the range of 700-900 ° C leads to an increase in the hot strength of the briquette, which expands the range of application of the briquette in cupolas with an increased volume of charge loading. However, this temperature range of annealing leads to an increase in energy consumption for briquette formation, which is not always acceptable.

To obtain a charge with a uniform distribution of the fractions of the pyrolysis liquid between the particles of carbonized biomass, the process of forming the charge is carried out as follows:

- mixing the carbonized biomass with the aqueous fraction of the pyrolysis liquid to obtain the first mixture, while the mixing can be carried out at a mixer rotation speed of 10-20 rpm, preferably 15 rpm;

- mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge.

The mixing of the carbonized mass with the aqueous and resinous fraction of the pyrolysis liquid can be carried out in any mixer suitable for these purposes. However, the present inventors have found that from the point of view of obtaining an additionally more homogeneous mixture of carbonized biomass particles with hydrous and resinous fractions of pyrolysis resin and, as a consequence, proper briquette strength, a paddle mixer can be used for mixing.

The authors of the present invention have also found that it is possible to further improve the strength of the briquette by compacting the resulting batch. Compaction can be carried out by 10-fold puncturing for uniform impregnation, crushing, air removal and giving the charge a plastic structure. For these purposes, any mixer can be used that ensures the homogenization of the batch. The present inventors have found that a roll mixer with a roll speed of 90-110 rpm is the most preferred equipment for this purpose.

The resulting impregnated charge can be molded on a press with a design force on the rod from 1 to 2 tons, which makes it possible to obtain a briquette with the proper mechanical strength. During pressing, the volume of the briquette is reduced by 20-30%. It was experimentally found that the most preferred shape of the briquette to improve heat transfer, improve strength and facilitate the release of volatile substances is a shape close to cubic with cube sides 90-125 mm with a through hole in the central part of the cube.

The obtained raw briquettes were dried in air at room temperature for a period from 72 to 170 hours, as a result of which excess fractions of the pyrolysis liquid were removed, which, in turn, made it possible to obtain an additional more uniform and durable briquette structure after subsequent annealing.

Subsequently, the charge formed into briquettes is subjected to annealing to obtain fuel briquettes. The annealing process is carried out at temperatures of 150-700 ° C. By using these temperatures, it is possible to obtain a fuel briquette having proper mechanical strength and heating value.

The inventors of the present invention have found that, in terms of improving the mechanical strength of the briquette, the annealing process can be carried out as follows:

- drying: 150 ° С - 6 hours, 200 ° С - 6 hours, 250 ° С - 6 hours, in total 24 hours, taking into account the exit to the set temperature;

- temperature rise up to 300 ° С with keeping at a given temperature for 5-6 hours;

- bringing the temperature to 500 ° C at a rate of 25 ° C / h and keeping it at a given temperature for 2-3 hours;

- pyrolysis at 650-700 ° C for 2-5 hours;

- unloading of briquettes after annealing into a hermetically sealed container for stabilization.

Unloading briquettes into a sealed container contributes to less cracking of briquettes, since, due to the cessation of smoldering briquettes, they are less susceptible to oxidation.

The briquettes obtained by the method according to the present invention have the physicochemical characteristics shown in Table 3.

Table 3. Physical and chemical parameters of a fuel briquette based on sunflower seed husk.

Parameter Dry value ** Working condition value * Total moisture,%, according to ISO 579 - 4.0 Ash,%, according to ISO 1171 10.7 10.2 Volatile matter yield,%, according to ISO 562 6.5 6,3 Gross calorific value (calorific value) ***, kcal / kg, according to ISO 1928 7277 (30447kJ / kg) 6985 (29225 kJ / kg) Net calorific value (calorific value) ****, kcal / kg, according to ISO 1928 6881 (28790 kJ / kg) Total sulfur,%, according to ISO 19579 0.13 0.12 Hydrogen,%, according to ISO 29541 1.73 1.66

* - operating condition of the fuel - the condition of the fuel with the same total moisture content and ash content with which it is shipped or used

** - dry state of fuel - state of fuel that does not contain total moisture

*** - the amount of heat released during complete combustion of a unit mass of a fuel product in a compressed oxygen environment under specified conditions;

**** - amount of heat equal to the highest heat of combustion minus the heat of evaporation of water released during combustion of the fuel product

Also, the mechanical strength of the obtained briquette was determined by dropping it from a height of no more than 3 m. When falling, the briquette broke into no more than 3 parts, that is, the briquette is characterized by high strength.

The average values of the physicochemical characteristics of the fuel briquette obtained according to the method according to the present invention from plant raw materials, in comparison with coke, are presented in Table 4.

Table 4. Physicochemical characteristics of a fuel briquette obtained from biomass of plant origin in comparison with coke.

Physicochemical parameter Fuel briquette Coal-derived coke Humidity, mass. %, according to GOST R 53357 0.1-3.7 0.7 Ash content, mass. %, according to GOST R 53357 6.0-10.1 9.2 Volatile matter content, wt. %, according to GOST R 53357 4.9-9.0 0,4 Non-volatile carbon, wt. %, according to GOST R 53357 82.1-89.0 89.7 Calorific value (calorific value), kJ / kg, according to ISO 1928 30447-32615 29780

Table 4 clearly shows that the values of the physicochemical parameters for the fuel briquette obtained from raw materials of plant origin and for coke are comparable, which indicates that according to the method according to the present invention, it is possible to obtain a fuel briquette with the required heat of combustion. Also, the mechanical strength of the fuel briquette, defined as breaking into no more than 3 parts when dropped from a height of 3 m, indicates the strength of the fuel briquette, and the possibility of its use, including in furnaces with vertical loading.

To assess the changes that occurred with the carbonized product after annealing, the microstructure of the surface of the briquetted fuel product after its annealing, as well as the microstructure of the carbonized product obtained after pyrolysis of plant biomass, were studied.

Figures 1-3 clearly show that the structure has changed, which is due to the fact that the resinous fraction of the pyrolysis liquid (lighter areas in Fig. 1) filled the space between the particles of carbonized biomass, which indicates good mixing of the carbonized biomass with the pyrolysis liquid, which was carried out by sequential mixing of the carbonized biomass with the aqueous fraction of the pyrolysis liquid to obtain the first mixture, which in turn was mixed with the resinous fraction of the pyrolysis liquid to obtain a charge.

Thus, a certain sequence of mixing the fractions of the pyrolysis liquid to the carbonized biomass with subsequent molding of the charge contributes to the production of a briquetted fuel product with the required characteristics in terms of calorific value, as well as the production of fuel briquettes of the required mechanical strength.

Examples of

Comparative example A with resinous fraction

To 760 g of carbonized biomass (based on dry matter), obtained as a result of pyrolysis of sunflower husk, 300 g of resinous fraction was added. The ratio of carbonized biomass to resinous fraction is 2.5: 1. Mixing was carried out in a paddle mixer with a mixer rotation frequency of 15 rpm. Uniform mixing did not occur, the resinous part adhered to the surface of the mixer blade. Attempts have been made to mold the resulting mass on a hand press with a design force on the rod up to 2 tons into a cube shape with a through hole. However, molding the resulting mixture into a predetermined shape did not lead to the production of a tightly adhered briquette. Keeping the briquettes at room temperature for 170 hours led to a partial collapse of the cube edges, and upon further heating, in some cases, the cube edges. The resulting briquetted forms were subjected to annealing at the following temperature conditions: 150 ° C - 6 hours, 200 ° C - 6 hours, 250 ° C - 6 hours, for a total of 24 hours, taking into account reaching the set temperature; raising the temperature to 300 ° C with holding at a given temperature for 5 hours, raising the temperature to 500 ° C at a rate of 25 ° C / h and holding at a given temperature for 3 hours; rise in temperature to 650-675 ° С within 3 hours.

After annealing in order to prevent smoldering of the obtained forms, they were placed in a hermetically sealed container.

Physicochemical characteristics of the obtained product: heat of combustion 29280 kJ / kg, humidity 1.5% wt., Ash content 10.2% wt., Content of volatile substances 6.8% wt., Content of non-volatile carbon 81.5% wt. The cold strength test — dropping the fuel briquette from a height of 3 m — was not carried out, since the briquette was not molded into a given shape.

Comparative example B with a water-containing fraction

To 500 g of carbonized biomass (based on dry matter) obtained as a result of pyrolysis of sunflower husk, add 500 g of an aqueous fraction of pyrolysis liquid obtained as a result of settling after pyrolysis of sunflower husk. The ratio of carbonized biomass to water-containing fraction is 1: 1. The amount of the water-containing fraction is increased compared to the resinous fraction in Comparative Example A due to the content in the water-containing fraction of less organic matter in comparison with the resinous part, which could lead to strengthening of the briquette when heated. Mixing was carried out in a paddle mixer with a mixer rotation frequency of 15 rpm, no sticking occurred. The resulting mixture was mixed and compacted in a roller mixer, in which the mixture was rubbed between the rollers to obtain a homogeneous mixture. The resulting impregnated charge was molded on a hand press with a design force on the rod up to 2 tons into a cube shape with a through hole. The briquette with the shape of a cube was annealed at the following temperature conditions: 150 ° C - 6 hours, 200 ° C - 6 hours, 250 ° C - 6 hours, 24 hours in total, taking into account the exit to the set temperature; raising the temperature to 300 ° C with holding at a given temperature for 5 hours, raising the temperature to 500 ° C at a rate of 25 ° C / h and holding at a given temperature for 3 hours; rise in temperature to 650-675 ° С within 3 hours.

After annealing, the briquettes were unloaded into a hermetically sealed container for stabilization.

Physicochemical characteristics of the obtained product: heat of combustion 29200 kJ / kg, humidity 4.0% wt., Ash content 10.1% wt., Content of volatile substances 5.8% wt., Content of non-volatile carbon 80.1% wt. When dropping a fuel briquette from a height of 3 m, it breaks down into more than 3 parts, namely, into 5 large parts with the splitting off of many small pieces.

Example 1 without following the briquette recipe

To 1000 g of carbonized biomass (based on dry matter) obtained as a result of pyrolysis of sunflower husks, 500 g of an aqueous fraction of pyrolysis liquid obtained as a result of settling after pyrolysis of sunflower seed husks was added. Mixing was carried out in a paddle mixer with a mixer rotation frequency of 15 rpm. To the resulting first mixture was added 500 g of a resinous fraction of a pyrolysis liquid immiscible with water, obtained as a result of settling after pyrolysis of sunflower husks. The ratio of the carbonized biomass with the water-containing fraction and the resinous fraction was 1: 0.5: 0.5. The adhesion of the resinous fraction to the surface of the mixer blade was less evident, but persisted. The resulting mixture was mixed and compacted in a roller mixer. In view of the remaining adhesion of the resinous fraction to the surface of the mixer blade, uniform mixing was not achieved. The resulting impregnated charge was molded on a hand press with a design force on the rod up to 2 tons into a cube shape with a through hole. The briquette with the shape of a cube was annealed at the following temperature conditions: 150 ° C - 6 hours, 200 ° C - 6 hours, 250 ° C - 6 hours, 24 hours in total, taking into account the exit to the set temperature; raising the temperature to 300 ° C with holding at a given temperature for 5 hours, raising the temperature to 500 ° C at a rate of 25 ° C / h and holding at a given temperature for 3 hours; rise in temperature to 650-675 ° С within 3 hours.

After annealing, the briquettes were unloaded into a hermetically sealed container for stabilization.

Physicochemical characteristics of the resulting product: heat of combustion 30080 kJ / kg, moisture 2.6% wt., Ash content 9.8% wt., Volatile matter content 6.2% wt., Non-volatile carbon content 81.4% wt. When dropping a fuel briquette from a height of 3 m, it breaks into more than 3 parts, namely into 4 parts, and 3 parts were stronger, and one part was cracked.

Example 2 - according to the invention

To 760 g of carbonized biomass (based on dry matter) obtained as a result of pyrolysis of sunflower husk, add 1000 g of an aqueous fraction of pyrolysis liquid obtained as a result of settling after pyrolysis of sunflower seed husk. Mixing was carried out in a paddle mixer with a mixer rotation frequency of 15 rpm. To the resulting first mixture was added 240 g of a resinous fraction of a pyrolysis liquid immiscible with water, obtained as a result of settling after pyrolysis of sunflower husks. The ratio of carbonized biomass with water-containing fraction and resinous fraction is 1: 1.3: 0.3. There was a uniform mixing of the charge. The resulting charge was mixed and compacted in a roller mixer, in which the charge was rubbed between the rollers, as a result of which there was mixing, grinding and homogenization of the charge. The resulting impregnated charge was molded on a hand press with a design force on the rod up to 2 tons into a cube shape with a through hole. The briquette with the shape of a cube was dried for 168 hours at room temperature, then annealed at the following temperature conditions: 150 ° С - 6 hours, 200 ° С - 6 hours, 250 ° С - 6 hours, 24 hours in total, taking into account the exit to the set temperature; raising the temperature to 300 ° C with holding at a given temperature for 5 hours, raising the temperature to 500 ° C at a rate of 25 ° C / h and holding at a given temperature for 3 hours; rise in temperature to 650-675 ° С within 3 hours.

After annealing, the briquettes were unloaded into a hermetically sealed container for stabilization.

Physicochemical characteristics of the obtained product: heat of combustion 30447 kJ / kg, moisture 1.6% wt., Ash content 10.1% wt., Volatile matter content 6.0% wt., Content of non-volatile carbon 82.3% wt. When dropping a fuel briquette from a height of 3 m, it does not break into more than 3 parts.

Example 3 - according to the invention

Similar to example 1, but to obtain carbonized biomass and pyrolysis liquid in the form of a settled water-containing fraction and resinous fraction, wheat straw was used. Carbonized biomass was taken in an amount of 800 g (based on dry matter), the water-containing fraction of liquid pyrolysis products was used in an amount of 1000 g, the resinous fraction of the pyrolysis liquid obtained as a result of pyrolysis of wheat straw was used in an amount of 200 g. The ratio of carbonized biomass to the water-containing fraction and the gum fraction was 1: 1.25: 0.25. There was a homogeneous mixing of the charge. The briquette with the shape of a cube was dried for 144 hours at room temperature, then annealed at the following temperature conditions: 150 ° С - 6 hours, 200 ° С - 6 hours, 250 ° С - 6 hours, 24 hours in total, taking into account the exit to the set temperature; raising the temperature to 300 ° C with holding at a given temperature for 6 hours, raising the temperature to 500 ° C at a rate of 25 ° C / h and holding at a given temperature for 3 hours; temperature rise to 650-675 ° C within 3.5 hours.

Physicochemical characteristics of the obtained product: heat of combustion 32000 kJ / kg, humidity 1.5% wt., Ash content 10.1% wt., Content of volatile substances 6.0% wt., Content of non-volatile carbon 88.4% wt. When dropping a fuel briquette from a height of 3 m, it does not break into more than 3 parts.

Example 4 according to the invention

Similar to example 1, but to obtain carbonized biomass and pyrolysis liquid in the form of settled water-containing fraction and resinous fraction, sawdust of birch wood was used. Carbonized biomass was taken in the amount of 840 g (based on dry matter), the water-containing fraction of liquid pyrolysis products was used in the amount of 1000 g, the resinous fraction of the pyrolysis liquid was used in the amount of 160 g. The ratio of carbonized biomass with the water-containing fraction and the resinous fraction was 1: 1 , 2: 0.2. There was a homogeneous mixing of the charge. The briquette with the shape of a cube was dried for 80 hours at room temperature, then annealed at the following temperature conditions: 150 ° C - 6 hours, 200 ° C - 6 hours, 250 ° C - 6 hours, 24 hours in total, taking into account the exit to the set temperature; raising the temperature to 300 ° C with holding at a given temperature for 6 hours, raising the temperature to 500 ° C at a rate of 25 ° C / h and holding at a given temperature for 3 hours; temperature rise to 650-675 ° C within 5 hours.

Physicochemical characteristics of the obtained product: heat of combustion 32115 kJ / kg, moisture 2.1% wt., Ash content 9.9% wt., Volatile matter content 5.9% wt., Content of non-volatile carbon 88.4% wt. When dropping a fuel briquette from a height of 3 m, it does not break into more than 3 parts.

Analysis of the data obtained as a result of the experiments carried out indicates that the use of only the resinous fraction of the pyrolysis liquid does not lead to the formation of the charge into briquettes due to the impossibility of uniform distribution of the viscous resinous fraction among the particles of carbonized biomass due to its adhesion to the mixer elements, which does not allow to obtain a homogeneously mixed mixture. As a result, a part of the carbonized biomass remains not at all mixed with the resinous fraction, which does not allow molding the charge into a briquette of the required shape and with the specified strength characteristics.

The use of a water-containing fraction leads to the formation of a briquette, but does not allow obtaining a briquette with the desired strength characteristics, which may be due to the fact that water and organic substances contained in the water-containing fraction differ from the organic mass of carbonized biomass by the coefficient of thermal expansion, which results in to obtain a briquette of insufficient strength.

The presence of a briquette, including a water-containing fraction and a resinous fraction, of greater strength may be due to the fact that the resinous fraction contains thermally stable hydrocarbon compounds that contribute to the binding of particles of carbonized biomass. At the same time, to obtain a homogenized mixture, it is necessary to observe the sequence of mixing the fractions of the pyrolysis liquid, namely, the initial mixing of the carbonized biomass with the water-containing fraction, followed by the addition of the resinous fraction, which contributes to less adhesion of the resinous fraction to the mixer elements. To achieve the least sticking of the resinous fraction on the mixer elements, and as a result of eliminating the loss of the resinous fraction, it is additionally necessary to take into account the ratio of the amount of the added water-containing fraction and the resinous fraction, which can be in the range from 4: 1 to 7: 1 by weight, which results in to a uniform distribution of the resinous fraction between the particles of carbonized biomass, as can be clearly seen in Fig. 1. The colloidal system probably formed during mixing of the components of the carbonized biomass, the water-containing fraction and the resinous fraction contributes to the fact that the mixture can be uniformly mixed, minimizing the contact of the viscous resinous fraction with the mixer elements, and thus contributing to a more uniform distribution of the resinous fraction between the particles of the carbonized biomass, which results in a durable product with the required heating value.

Analysis of the calorific value of the comparative examples and the examples according to the invention shows that the calorific value of the resulting product is approximately the same. Apparently, the comparable calorific value of comparative example A and comparative example B is due to the fact that in the first case, the additional amount of carbon contributes to the calorific value, which can be formed from the resinous fraction when the briquette is annealed with a temperature rise from 150 ° C to 700 ° C. The retention of the calorific value in comparative example B comparable to the calorific value in comparative example A can be due to the release of hydrogen, which can contribute to the total calorific value of the briquette, and which can be formed as a result of the interaction of carbon with water retained in the pores of the fuel briquette, according to the reaction:

C + H ₂ O = H ₂ + CO

under conditions of water shortage due to its evaporation during annealing at temperatures from 150 ° C to 700 ° C.

In this case, the comparability of the values of non-volatile carbon in all examples may be due to the fact that the resinous fraction that is part of the briquette in comparative example A and examples 1-4 during annealing from 150 ° C to 700 ° C additionally contributes to carbon due to the resulting coke part, and in the case of comparative example B, as well as examples 1-4, the water-containing fraction included in the briquette will lead to the formation of water vapor, which, along with the tar released during heating and decomposition gases, will lead to the creation of a protective atmosphere cloud. In this case, the combustion of the evolved gases and vapors will be carried out at the periphery of the gas cloud. Thus, ashing of coal particles with atmospheric oxygen is minimized, which ensures the required level of carbon content, thereby increasing the calorific value of coke. In addition, the formation of a protective atmosphere cloud prevents an increase in the ash content of the fuel as a result of the loss of a part of the combustible component by the fuel.

It should be noted that a slightly increased value of the ash content in comparative example A may be due to the fact that it was not possible to achieve dense molding of the briquette, and the annealing occurred to a greater extent due to the looseness of the resulting shape, which led to a slight decrease in the carbon component, and, as a consequence, an increase in ash content.

Thus, mixing the carbonized biomass with the water-containing fraction of the pyrolysis liquid to obtain the first mixture and then mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge that is subjected to annealing leads to the production of a durable fuel briquette with the required heating value of the fuel, which allows the use of the fuel briquette in fuel , smelting furnaces for melting and / or recovery of mineral raw materials. At the same time, the method for producing such a fuel briquette is environmentally friendly and economically profitable, due to the use of pyrolysis by-products and the absence of the need for waste disposal.

Estimation of the hot strength of a fuel briquette

From the fuel briquette obtained according to Example 2, rectangular samples with dimensions of 100x40x30 mm were cut by sawing. Then, the fracture force of the sawn-off specimens was measured in compression at temperatures of 600 ° C and 800 ° C with holding for 60 minutes.

Received a fuel briquette according to Example 2 with the addition of crumbs of coal coke to the carbonized biomass before mixing with the aqueous fraction of the pyrolysis liquid. From the obtained fuel briquette, rectangular samples of 100x40x30 mm in size were obtained by sawing out. Then, the fracture force of the sawn-off specimens was measured in compression at temperatures of 600 ° C and 800 ° C with holding for 60 minutes.

Table 5

No. Sample type Compression fracture force, kN 600 ^o C 800 ^o C 1 Example 2 fifteen thirteen 2 Example 2 and 5% of the mass. coal coke crumbs sixteen fourteen 3 Example 2 and 10% of the mass. coal coke crumbs eighteen sixteen 4 Example 2 and 15% of the mass. coal coke crumbs 20 eighteen

Analysis of the data obtained as a result of the experiments carried out indicates that the fuel briquette of the present invention has sufficient hot strength for its use in fuel / smelting furnaces (eg cupola). Also, based on the data obtained, it can be concluded that the addition of coal coke crumb to the carbonized biomass improves the hot strength of the fuel briquette.

Comparative example of obtaining mineral wool using coal coke

The cupola was loaded with 203 kg of coal coke, 1500 kg of mineral raw materials (basalt, dolomite). During the process, the raw material moves along the height of the furnace to the combustion zone, into which oxygen-enriched air is fed through the tuyeres. Under the influence of heat, a melt of stone material is formed, which is then used to obtain stone wool.

It was determined that the temperature of the melt is 1401-1417 ° C, the relative viscosity of the melt is 18-21 cm.

An example of producing mineral wool using a briquette according to the invention

The cupola was loaded with 158 kg of coal coke, 50 kg of a fuel briquette from biomass of plant origin, 1500 kg of mineral raw materials (basalt, dolomite). The raw material moves along the height of the furnace to the combustion zone, into which oxygen-enriched air is fed through the tuyeres. Under the influence of heat, a melt of stone material is formed, which is then used to obtain stone wool.

It was determined that the temperature of the melt is 1363-1392 ° C, the relative viscosity of the melt is 18 cm.

Determination of the relative viscosity was carried out as follows: a sample of the melt was taken into a viscometer, which was poured into the tube, after solidification, the distance over which the sample spread was measured. The relative viscosity was determined in centimeters.

The fact that the temperature of the melt obtained from the stone material using the fuel briquette according to the invention is comparable to the melting temperature of the stone material obtained using the coal coke indicates that the hot strength of the fuel briquette is acceptable for use in the cupola.

This effect can be achieved only if the fuel briquette enters the combustion zone without destruction, where the fuel briquette can give its thermal energy to the stone material sufficiently to melt the latter.

Claims (31)

1. A method of obtaining a fuel briquette from biomass of plant origin, comprising the stages at which: i) provide biomass of plant origin; ii) pyrolysis of biomass of plant origin to obtain carbonized biomass and pyrolysis liquid; iii) separating the pyrolysis liquid into a water-containing fraction and a resinous fraction, the resinous fraction being immiscible with the water-containing fraction; iv) form a charge by mixing the carbonized biomass with a water-containing fraction and a resinous fraction of the pyrolysis liquid; v) forming the charge into a briquette; vi) annealing the charge briquette, and at stage iv) the formation of the charge includes: - mixing the carbonized biomass with the aqueous fraction of the pyrolysis liquid to obtain the first mixture; - mixing the first mixture with the resinous fraction of the pyrolysis liquid to obtain a charge. 2. The method of claim 1, further comprising, prior to step vi), drying the briquette at room temperature for a period of 72 to 170 hours. 3. A method according to claim 1, wherein in step v) the charge is formed into a briquette by pressing. 4. The method according to claim. 1, in which the pyrolysis liquid in step ii) contains condensed vapors of a vapor-gas mixture obtained by pyrolysis of biomass of plant origin. 5. The method according to claim 1, wherein the resinous and water-containing fractions of the pyrolysis liquid obtained in step iii) contain organic carbon-containing compounds released during the pyrolysis of plant biomass. 6. The method according to claim 5, wherein the content of organic carbon-containing compounds in the resinous fraction is greater than the content of organic carbon-containing compounds in the aqueous fraction. 7. The method according to claim 1, wherein in step iii) the separation of the pyrolysis liquid into a water-containing fraction and a resinous fraction is carried out by settling. 8. The method according to claim 1, wherein in step iv) the ratio of the amount of the aqueous fraction of the pyrolysis liquid to the amount of the resinous fraction of the pyrolysis liquid is from 4.16: 1 to 6.25: 1 by weight. 9. The method according to claim 1, wherein in step iv) the ratio of the amount of carbonized biomass to the amount of hydrous fraction of the pyrolysis liquid is from 0.76: 1 to 0.86: 1 by weight. 10. A method according to claim 1, wherein in step iv) the ratio of the amount of carbonized biomass to the amount of resinous fraction of the pyrolysis liquid is from 3.16: 1 to 5.25: 1 by weight. 11. A method according to claim 1, wherein in step v) the briquette is formed into a cube, wherein a through hole is formed in the central part of the cube. 12. The method of claim 1, wherein step vi) sequentially comprises: - keeping the briquette at a temperature of 150–250 ° С for 18 hours; - keeping the briquette at a temperature of 300 ° C for 5-6 hours; - keeping the briquette at a temperature of 500 ° C for 2-3 hours; - keeping the briquette at a temperature of 650-700 ° C for 2-5 hours. 13. The method of claim 1, further comprising compacting the charge in step iv). 14. The method according to claim 18, wherein the compaction of the charge is carried out in a roller mixer. 15. The method according to claim. 1, in which in step ii) the pyrolysis liquid is obtained by condensation of vapors of a vapor-gas mixture obtained by pyrolysis of biomass of plant origin. 16. The method of claim 1, wherein step iv) is carried out in a paddle mixer. 17. The method according to claim 1, wherein in step iv) 5-15 wt.%, Preferably 5-10 wt.%, Of coke chips are added to the carbonized biomass before mixing with the aqueous and resinous fractions, based on the total weight of the carbonized biomass and coke chips. 18. The method according to claim 1, in which in step vi) the annealing of the briquette is carried out in the temperature range 150-900 ° C, preferably 150-700 ° C.

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