PL249548B1 - Mixed pellets with grass plants - Google Patents

Abstract

The subject of the application is mixed pellets with the participation of grass plants, containing sawdust from coniferous trees and miscanthus, refined with an additive improving their mechanical strength, being biochar obtained in the process of pyrolysis of biomass, which are characterized in that they contain: from 98.5% (m/m) to 99.5% (m/m), calculated on the total weight of mixed pellets with the participation of grass plants, refined with an additive improving their mechanical strength, of component I, which consists of sawdust from coniferous trees in an amount of from 49% to 51% (m/m) and miscanthus in an amount of from 49% to 51% (m/m), which biocomponents are mixed with each other and thoroughly homogenized; and from 0.5% (m/m) to 1.5% (m/m) calculated on the total mass of mixed pellets with the participation of grass plants, refined with an additive improving their mechanical strength, component II, which is carbon obtained in the process of pyrolysis of cereal straw carried out in a microwave reactor at a temperature of 600°C, during 10 minutes, in a flow of 16 l/h of inert gas; components I and II are mixed together and thoroughly homogenized, and then subjected to the agglomeration process.

Description

Description of the invention

FIELD OF TECHNOLOGY

The subject of the invention is a pellet mixed with grass plants, refined with an additive improving its mechanical strength.

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.

Patent application PL439171 describes a method for producing wood pellets with increased mechanical strength. The authors describe in detail 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 resulting 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.

Patent application 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, also 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 modification. 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 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 patent description RU2671824, sawdust is subjected to thermal pretreatment, which improves its strength by increasing the density of carbon particles, further increasing its heat value, and reducing the amount of volatile substances in the resulting fuel. A similar method is described in numerous patent documents, including EP3184613 and KR102289529.

Sarker TR, Nanda S, Meda V, Dalai AK. “Pelletization of torrefied canola residue: Effects of microwave power, residence time and bioadditives 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 an additive to enhance wood pellet quality,” Renew Energy 2021; 180: 850-9, the effect of biochar from eucalyptus pyrolysis on the quality of pine pellets was investigated. Biochar was added to the fuel at a rate of 5%–20% and was shown to improve the quality of pellets, but its effect on their strength was not assessed.

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

Problems related to pellet strength can be mitigated by transporting and burning pellets enriched with additives designed for use with solid fuels produced from biomass. Surprisingly, it turned out that this goal could be achieved by developing a fuel composition in the form of pellets mixed with grass plants, enriched with an additive that improves the pellets' mechanical strength. After agglomeration of the biomass components containing the additive, these pellets exhibit higher mechanical strength than pellets without the additive.

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

THE ESSENCE OF THE INVENTION

The pellet mixed with grass plants, according to the present invention, containing sawdust from coniferous trees and miscanthus, enriched with an additive improving its mechanical strength, being biochar obtained in the process of biomass pyrolysis, is characterized in that it contains:

- from 98.5% (m/m) to 99.5% (m/m), calculated on the total mass of pellets mixed with grass plants, refined with an additive improving its mechanical strength, component I, which consists of sawdust from coniferous trees in the amount of 49% to 51% (m/m) and miscanthus 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 grass plants, refined with an additive improving its mechanical strength, component II, constituting an additive improving the mechanical strength of the pellets, which is carbon obtained in the process of pyrolysis of cereal straw carried out in a microwave reactor at a temperature of 600°C, for 10 minutes, in a flow of 16 l/h of inert gas.

The biocomponents of component I are mixed together and thoroughly homogenized.

Components I and II are mixed and thoroughly homogenized, and then subjected to an 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 pyrolysis of cereal straw to the biomass components subjected to the agglomeration process allows for an improvement in the mechanical strength of the pellets from over 5% to over 10% compared to the level of mechanical strength of pellets obtained from biomass components without the additive consisting of carbon obtained in the pyrolysis of cereal straw.

The present invention is presented in embodiment examples 1 to 5, illustrating the composition, method of production and effectiveness of improving the mechanical strength of pellets produced in the agglomeration process by using an additive being carbon obtained in the pyrolysis process of cereal straw, in test trials, and therefore cannot be considered as limiting the essence of the invention, as they are only of illustrative nature.

Example 1 is a comparative example.

EXAMPLES

Example 1 - comparative example

500 g of coniferous sawdust with the properties given in Table 1 and 500 g of miscanthus 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 249548 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 the Miscanthus used for testing.

Name of the marking, test method Unit Value Appearance — characteristic Contents of the % 11.9 Ash content % 1.4 Calorific value MJ/kg 15.73

Example 2

We weighed 497.5 g of coniferous sawdust with the properties in Table 1, 497.5 g of miscanthus with the properties in Table 2, and 5 g of carbon obtained by pyrolysis of cereal straw with the properties in Table 3. This carbon was obtained by pyrolysis of cereal straw in a microwave reactor at 600°C for 10 minutes, under a flow of 16 l/h of inert gas. The ingredients were then thoroughly mixed and granulated in a ZLSP-150B pelletizing device from Haven Polska Sp. z o.o. using a matrix with a mesh diameter of 6 mm.

Table 3. Characteristics of the carbon obtained in the pyrolysis process of cereal straw used for the research.

Name of the marking, test method Unit Value Appearance — black powder Carbon content % 73.17 Calorific value MJ/kg 24.77

Example 3

We weighed 495 g of coniferous sawdust with the properties in Table 1, 495 g of miscanthus with the properties in Table 2, and 10 g of carbon obtained by pyrolysis of cereal straw with the properties in Table 3. This carbon was obtained by pyrolysis of cereal straw in a microwave reactor at 600°C for 10 minutes, under a flow of 16 l/h of inert gas. 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 4

492.5 g of coniferous wood sawdust with the properties given in Table 1, 492.5 g of miscanthus with the properties given in Table 2, and 15 g of carbon obtained in the pyrolysis of cereal straw with the properties given in Table 3, which was obtained in the pyrolysis of cereal straw carried out in the reactor were weighed.

PL 249548 Β1 microwave at 600°C for 10 minutes, in a flow of 16 l/h of inert gas. The ingredients were then thoroughly mixed and granulated in a ZLSP-150B pelletizing machine from Haven Polska Sp. z o.o. using a matrix with a mesh diameter of 6 mm.

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 [l%]

Product from example 1 (comparative example)85.0

Product, from example 289.4

Product from example 392.2

Product from example 494.0

The above examples present the composition of mixed pellets with the participation of grass plants, enriched with an additive improving the mechanical strength of the pellets according to the invention, and demonstrate the effectiveness in improving the mechanical strength by using the additive in test samples, proving the industrial applicability of the invention.

The mechanical resistance of mixed pellets containing grass plants and enriched with an additive was compared with the mechanical resistance of pellets without the additive.

Claims (1)

Patent claim 1. Pellet mixed with grass plants, containing sawdust from coniferous trees and miscanthus, refined with an additive improving its mechanical strength, being biochar obtained in the biomass pyrolysis process, characterized in that it contains: - from 98.5% (m/m) to 99.5% (m/m), calculated on the total mass of pellets mixed with grass plants, refined with an additive improving its mechanical strength, of component I, which consists of sawdust from coniferous trees in an amount of 49% to 51% (m/m) and miscanthus in an 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 grass plants, refined with an additive improving its mechanical strength, component II, constituting an additive improving the mechanical strength of the pellets, which is carbon obtained in the process of pyrolysis of cereal straw carried out in a microwave reactor at a temperature of 600°C, for 10 minutes, in a flow of 16 l/h of inert gas.