PL249185B1 - Mixed pellets with plant-based ingredients - Google Patents

Abstract

The subject of the application are mixed pellets with the content of plant ingredients, according to the present invention, containing sawdust from coniferous wood and cereal straw, refined with an additive improving their mechanical strength, which are characterized in that as an additive improving their mechanical strength they contain carbon obtained in the process of methane pyrolysis, and the composition of the pellets includes: from 98.5% (m/m) to 99.5% (m/m), calculated on the total weight of the mixed pellets with the content of plant ingredients, refined with an additive improving their mechanical strength, of component I, which consists of sawdust from coniferous wood in an amount of from 49% to 51% (m/m) and cereal straw in an amount of from 49% to 51% (m/m); and from 0.5% (m/m) to 1.5% (m/m) calculated on the total mass of pellets mixed with cereal straw, refined with an additive improving their mechanical strength, component II, which is carbon obtained in the methane pyrolysis process carried out in a quartz flow reactor placed in a horizontal tubular furnace, through which a mixture of nitrogen and methane is continuously passed in a volume ratio of 1:1 at a rate of 400 ml/min, and the produced carbon is extracted from the reactor periodically; components I and II are mixed together and thoroughly homogenized, and then subjected to the agglomeration process.

Description

The subject of the invention is a pellet mixed with plant ingredients, refined with an additive that improves the mechanical strength of the pellet.

STATE OF THE ART

Biofuels are fuels that are less likely to produce hazardous pollutants, and their combustion has a more favorable carbon dioxide balance than fossil fuels.

Pellets produced in the agglomeration process from biomass components are characterized by too low mechanical strength, they crumble during transport and feeding into the furnace or boiler, generating losses, pollution and a fire hazard.

Document PL439171 describes a method for producing wood pellets with increased mechanical strength. The authors provide a detailed description of the production steps for these pellets, including: drying the wood material, crushing the raw material, sifting, refining with additives, and pellet production. Gelatin or sucrose were used as additives to improve the strength of the final product, in amounts ranging from 0.3% to 0.5% by weight.

Patent application WO202005392 describes a method for obtaining biomass pellets characterized by high mechanical strength. The strength was improved by incorporating waste clay into the pellet composition in amounts ranging from 2% by weight to 16% by weight.

Document CN105969441A discloses a method for obtaining biomass briquettes with high compressive strength through the use of an additive. The substance added to the pellets, in addition to increasing mechanical strength, positively impacts the combustion process. The prepared biomass briquettes are characterized by a low flash point, low volatile content, high combustion rate, good thermal stability, high strength, and low dust content after combustion. The authors do not disclose the composition of the additive used.

In the article by Wang R, Zhang J, Liu Z, Li Y, Xu C. “Effect of CaO and MgO additives on the compressive strength of pellets: Exploration on the decisive stage during induration,” Powder Technol. 2021; 390: 496-503, the influence of calcium oxide and magnesium oxide on pellet strength is described. The authors noted that magnesium oxide negatively affects this property, while calcium oxide can eliminate this negative effect.

The article by Wang R, Zhang J, Liu Z, Liu X, Xu C, Li Y. “Interaction between iron ore and magnesium additives during induration process of pellets”, Powder Technol. 2020; 361: 894-902, describes the use of iron ores and their effect on the strength of biomass pellets.

In addition to adding additives, pellet strength can be improved at the production stage through process modifications; this method for improving the mechanical strength of pellets is described in patent RU2671824. The technology presented in the aforementioned document is based on pre-treating the wood material to enrich it with lignin and then subjecting it to the pelleting process. Lignin is a natural agent that improves the formation of pellets with high mechanical strength.

According to the description of RU2671824, on the one hand, sawdust is subjected to thermal pre-treatment, which improves its strength by increasing the density of carbon particles, further increasing the heat value, and reducing the amount of volatile substances in the resulting fuel. A similar method is described in numerous patent documents, including WO201267795, EP3184613,

US201305563, WO20170255 and KR102289529.

Sarker TR, Nanda S, Meda V, Dalai AK. "Pelletization of torrefied canola residue: Effects of microwave power, residence time and bio-additives on fuel pellet quality", Fuel 2022; 312: 122728, described a method for torrefaction of pellets using microwaves.

In the publication by Xia X, Zhang K, Xiao H, Xiao S, Song Z, Yang Z. “Effects of additives and hydrothermal pretreatment on the pelleting process of rice straw: Energy consumption and pellets quality”, Ind. Crops. Prod. 2019; 133: 178-84, two methods of increasing pellet strength were compared: by introducing additives (glycerin or paraffin) into their composition and by pretorrefaction. It was concluded that better results were obtained with the use of additives.

In the publication by Garcia R, Gil M V, Fanjul A, Gonzalez A, Majada J, Rubiera F, et al., “Residual pyrolysis biochar as additive to enhance wood pellets quality,” Renew Energy 2021; 180: 850-9, the effect of biochar addition obtained from eucalyptus pyrolysis on the quality of pine wood pellets was investigated.

Biochar was added to the fuel in the amount of 5% - 20%, it was shown that the addition of this material improves the quality of the produced pellets, but its effect on their strength was not tested.

The aim of this invention was to solve the technical problem of too low mechanical strength of pellets made from biomass.

Problems related to the low strength of pellets can be reduced by transporting and burning pellets enriched with additives dedicated to use with solid fuels produced from biomass.

Unexpectedly, it turned out that the set goal can be achieved by developing a fuel composition containing plant ingredients, in the form of mixed pellets, refined with an additive improving the mechanical strength of the pellets, which pellets after the process of agglomeration of plant ingredients containing the additive are characterized by higher mechanical strength than pellets without this additive.

It was surprisingly found that such desirable properties are possessed by pellets mixed with plant ingredients, in accordance with the present invention, enriched with an additive improving its mechanical strength, i.e. carbon obtained in the methane pyrolysis process, which after the agglomeration process is characterized by higher mechanical strength than pellets obtained solely from plant ingredients not containing this additive.

THE ESSENCE OF THE INVENTION

Pellets mixed with plant components, according to the present invention, containing sawdust from coniferous trees and cereal straw, refined with an additive improving its mechanical strength, are characterized in that they contain carbon obtained in the methane pyrolysis process as an additive improving its mechanical strength, and the pellets contain:

- from 98.5% (m/m) to 99.5% (m/m), calculated on the total mass of pellets mixed with the content of plant ingredients, refined with an additive improving its mechanical strength of component I, which consists of sawdust from coniferous trees in the amount of 49% to 51% (m/m) and cereal straw in the amount of 49% to 51% (m/m);

and

- from 0.5% (m/m) to 1.5% (m/m), calculated on the total mass of pellets mixed with the content of plant ingredients, refined with an additive improving its mechanical strength, component II, which is carbon obtained in the methane pyrolysis process carried out in a quartz flow reactor placed in a horizontal tubular furnace, through which a mixture of nitrogen and methane is continuously passed in a volume ratio of 1:1 at a rate of 400 ml/min.

The produced coal is extracted from the reactor periodically.

Components I and II are mixed together and thoroughly homogenized, and then subjected to the agglomeration process.

For the purposes of this invention, agglomeration is understood to mean the process of densification or compaction to obtain pellets.

It turned out during the research that adding an additive consisting of carbon obtained in the methane pyrolysis process to the plant ingredients subjected to the agglomeration process allows for an improvement in the mechanical strength of the pellets from about 0.5% to about 4% in relation to the level of mechanical strength of pellets obtained from plant ingredients without the additive consisting of carbon obtained in the methane pyrolysis process.

The present invention is presented in Examples 1 to 5, which illustrate the composition, production method, and effectiveness of improving the mechanical strength of pellets produced by the agglomeration process through the use of an additive consisting of carbon obtained by methane pyrolysis, in test trials. Therefore, they cannot be considered as limiting the scope of the invention, as they are merely illustrative. Example 1 is a comparative example, and Examples 2 to 5 illustrate the invention.

EXAMPLES

Example 1 - comparative example

500 g of coniferous sawdust with the properties given in Table 1 and 500 g of cereal straw with the properties given in Table 2 were weighed, then the ingredients were thoroughly mixed and granulated in a ZLSP-150B pelleting machine from Haven Polska Sp. z o.o. using a matrix with a mesh diameter of 6 mm.

PL 249185 Β1

Table 1. Characteristics of coniferous wood sawdust used for testing

Name of the marking, test method Unit Value. Appearance — characteristic Moisture content % 11.2 Ash content % 0.3 Calorific value MJ/kg 16.56

Table 2. Characteristics of cereal straw used for research

Name of the marking, test method Unit Value Appearance — characteristic Moisture content % 7.60 Ash content % 5.0 Calorific value MJ/kg 16.26

Example 2

We weighed 497.5 g of coniferous sawdust with the properties in Table 1, 497.5 g of cereal straw with the properties in Table 2, and 5 g of methane pyrolysis carbon with the properties in Table 3. The carbon was obtained in a quartz flow reactor located in a horizontal tube furnace, through which a mixture of nitrogen and methane was continuously passed in a 1:1 volume ratio at a rate of 400 ml/min. The ingredients were then thoroughly mixed and granulated in a ZLSP-150B pelletizing machine from Haven Polska Sp. z o.o. using a 6 mm mesh die.

Table 3. Characteristics of the coal obtained in the methane pyrolysis process used for the research

Name of the marking, test method Unit .Value Appearance — shimmering powder Carbon content % 100 Calorific value MJ/kg 32.88

Example 3

We weighed 495 g of coniferous sawdust with the properties in Table 1, 495 g of cereal straw with the properties in Table 2, and 10 g of methane pyrolysis carbon with the properties in Table 3. This carbon was obtained in a quartz flow reactor located in a horizontal tube furnace, through which a mixture of nitrogen and methane was continuously passed in a 1:1 volume ratio at a rate of 400 ml/min. The ingredients were then thoroughly mixed and granulated in a ZLSP-150B pelletizing machine from Haven Polska Sp. z o.o. using a 6 mm mesh die.

PL 249185 Β1

Example 4

We weighed 492.5 g of coniferous sawdust with the properties in Table 1, 492.5 g of cereal straw with the properties in Table 2, and 15 g of methane pyrolysis carbon with the properties in Table 3. The carbon was obtained in a quartz flow reactor located in a horizontal tube furnace, through which a mixture of nitrogen and methane was continuously passed in a 1:1 volume ratio at a rate of 400 ml/min. The ingredients were then thoroughly mixed and granulated in a ZLSP-150B pelletizing machine from Haven Polska Sp. z o.o. using a 6 mm mesh die.

Example 5

The mechanical strength of the products from examples 1 to 4 was tested. The tests were performed according to the PN-EN ISO 17831-1:2016-02 method (Solid biofuels - Determination of the mechanical strength of pellets and briquettes - Part 1: Pellets) in the "PELTEST" apparatus manufactured by TESTCHEM.

The test involved placing approximately 500 g of test pellets, screened through a 3.15 mm mesh sieve, into a steel cuboid rotating at 50 rpm. After 10 minutes, the crushed pellets were separated again on the same sieve and the residue on the sieve was weighed. The following equation was used to calculate the strength of the tested pellet sample.

DU=(mA/mE) 100 where:

DU - mechanical strength, % mA - sample mass after the test, g mE - sample mass before the test, g

The obtained mechanical strength test results are presented in Table 4.

Table 4. Mechanical resistance according to PN-EN ISO 17831-1:2016-02

Tested sample Mechanical resistance [%1] Product from Example 1 (comparative example) 90.6 Product from example 2 91.2 Product from example 3 93.6 Product from example 4 94.0

The above examples present the composition of the mixed pellet according to the invention, containing plant ingredients, enriched with an additive improving mechanical strength, and demonstrate the effectiveness in improving mechanical strength by using the additive in test samples, proving the industrial applicability of the invention.

The mechanical strength of the mixed pellets according to the invention, containing plant ingredients and refined with an additive, was compared with the mechanical strength of the pellets without the additive.

Claims (1)

1. Pellets mixed with plant ingredients, containing sawdust from coniferous trees and cereal straw, refined with an additive improving its mechanical strength, characterized in that it contains carbon obtained in the methane pyrolysis process as an additive improving its mechanical strength, and the pellets consist of: - from 98.5% (m/m) to 99.5% (m/m), calculated on the total mass of pellets mixed with the content of plant ingredients, refined with an additive improving its mechanical strength of component I, which consists of sawdust from coniferous trees in the amount of 49% to 51% (m/m) and cereal straw in the amount of 49% to 51% (m/m); and - from 0.5% (m/m) to 1.5% (m/m), calculated on the total mass of pellets mixed with the content of plant ingredients, refined with an additive improving its mechanical strength, component II, which is carbon obtained in the methane pyrolysis process carried out in a quartz flow reactor placed in a horizontal tubular furnace, through which a mixture of nitrogen and methane is continuously passed in a volume ratio of 1:1 at a rate of 400 ml/min.