KR102063250B1 - A Fuel Pellet Manufacturing Method Using Coffee Grounds, Cashew Net, Sawdust And A Fuel Pellet With Thereof - Google Patents

Abstract

The purpose of the present invention is to provide a method of manufacturing a fuel pellet, which manufactures the fuel pellet having good formability, enables high calorific heating, and can be utilized as an eco-friendly alternative energy by appropriately mixing coffee grounds, sawdust, and cashew nut shell, thereby maximizing merits of the respective components; and the fuel pellet manufactured thereby. The method according to the present invention comprises: a first pulverizing and sorting step of sorting the pulverized sawdust to a predetermined first size after obtaining pulverized sawdust by allowing a first pulverizer to pulverize sawdust generated from wood processing or sawdust obtained by pulverizing hardwood or miscellaneous tree; a drying step of obtaining a predetermined moisture content from the sawdust completing the first pulverizing and sorting step; a second pulverizing and sorting step of sorting the pulverized sawdust to a predetermined second size after obtaining pulverized sawdust by allowing a second pulverizer to pulverize the sawdust completing the drying step so that the sawdust can be formed and mixed well; a storage step of storing the sawdust completing the second pulverizing and sorting step in a sawdust storage room; a roasting and drying step of drying the roasted cashew nut obtained after allowing a roaster to roast cashew nut which has been harvested and dried; a peeling and cooling step of allowing a sheller to peel hull of the roasted and dried cashew nut and cooling the hull-peeled cashew nut; an inner skin pulverizing step of allowing a peeler to peel an inner skin of the cashew nut completing the peeling and cooling step, and preparing a cashew nut inner skin powder by allowing a pulverizer to pulverize the inner skin; a storage step of sorting the cashew nut inner skin powder completing the inner skin pulverizing step and storing the sorted cashew nut inner skin powder in a powder storage room; a sorting step of allowing a sorter to sort coffee grounds collected after completing a coffee manufacturing process; a drying step of obtaining a predetermined moisture content from the sorted coffee grounds; a storage step of storing the sorted and dried coffee grounds in a powder storage room; a step of injecting the sawdust, cashew nut inner skin powder, and coffee grounds which are stored in the respective storage rooms to a predetermined ratio into a mixer, thereby mixing the sawdust, cashew nut inner skin powder, and coffee grounds; and a step of manufacturing the pellet by compressing the mixed sawdust, cashew nut inner skin powder, and coffee grounds.

Description

Fuel Pellet Manufacturing Method Using Coffee Grounds, Cashew Net, Sawdust And A Fuel Pellet With Thereof}

The present invention relates to a fuel pellet manufacturing method using coffee grounds, cashew nuts, sawdust and fuel pellets prepared by the method, and in particular, having a high heat content that can be sufficiently used for thermal power generation and excellent moisture resistance This advantageous, and relates to a pellet manufacturing method using the coffee grounds, cashew nuts, sawdust and the fuel pellet produced by the method to increase the utilization of environmentally friendly future alternative energy using coffee grounds generated after coffee production.

In general, the combustion process of coal, which is a solid fuel, begins to decompose when coal reaches a certain temperature and releases volatile gas, which is preferentially diffused and burned when mixed with air, and the remaining carbon (fixed carbon) is surface burned. Will be

Here, diffusion combustion is performed by diffusing (supplying) air outside the generated volatile gas.

Extinguishing is called diffusion combustion.

In this way, air is diffused into the combustible gas without mixing the gas and the air in advance.

It is called diffusion combustion. In addition, when volatiles are released from coal, fixed carbon

But when air comes into contact with the surface of carbon, combustion

It will turn out. This is called surface combustion, and char combustion is a representative example.

Here, the diffusion combustion of the coal volatile matter is a small carbon number that is a gas phase material

Since it is a hydrocarbon, it is combustible and the combustion speed is very fast, so it is combustible.

On the other hand, surface combustion of fixed carbon is a solid fuel with poor ignition and

It is slow and has a bad combustibility.

Therefore, when the volatile content of coal is high, the diffusion of volatile matter with good combustibility

The energy obtained from combustion aids in the combustion of fixed carbon surfaces with poor combustibility.

Overall combustibility can be improved.

However, in the combustion theory of coal, when volatiles help combustion,

Although the most flammable among fossil fuels is coal fuel, solid fuel

to be.

Fossil fuels are generally classified into gaseous fuels, liquid fuels and solid fuels.

Typical fuels include LNG and LPG, while liquid fuels include petroleum, which is made by refining crude oil.

Solid fuel is coal.

Gas fuels are small in size and contain less than about six carbon atoms in hydrocarbons,

Because of its presence as a substance, the combustion reaction is explosive due to rapid mixing with air.

In the case of liquid fuels as well, the number of carbon atoms is 1025, which is relatively small,

When evaporated, they exhibit the same behavior as gaseous fuels, so they are relatively combustible.

On the other hand, the hydrocarbon structure of coal, which is a solid fuel, has tens to thousands of carbon atoms.

Volatilized on coal, which is composed of a large structure

Only burned carbon remains, and combustion is carried out by surface combustion.

It is known to be good.

Therefore, when coal is burned, the combustibility is poor and zones are burned without burning in coal ash.

The product contains a large amount of unburned carbon.

In order to solve the combustible defects of coal, in the boiler,

Various technical problems, such as increasing the length of stay in coal and

However, its effectiveness is limited to some extent, especially the global temperature.

Due to concerns about warming and depletion of fossil resources, biomass is attracting attention as an alternative energy source.

In addition, as shown in Figures 1 and 2 coffee grounds generated after the coffee production

Coffee grounds as alternative energy sources such as biodiesel, bioethanol, bio pellets

Giga is emerging as a bio pellet raw material. Coffee grounds are wood pellets or other materials

Produces higher calories.

However, it is difficult to make pellets because there is no adhesiveness with only coffee grounds. Wood

Biomass has low sulfur content, which is an eco-friendly fuel that can reduce SO2 generation

Alkalis contained in biomass, especially when mixed with high sulfur coal

The material can be expected to remove SO2, and the nitrogenous properties of biomass

Powder is used to reduce and remove NO because it is transferred to NH radicals during combustion.

Therefore, it is reported to have a NOx removal effect.

Therefore, in case of using coal fuel in thermal power plant, additionally SO2

Eco-friendly fuels are used to reduce generation.

Korea Patent 10-1635974 Korea Patent 10-1343470 Korea Patent 10-1621268 Korea Patent 10-1655914 Korea Patent 10-1579115

The present invention is to improve the above problems, the sawdust for making the adhesive effect when making the pellets for the heat, many coffee grounds, ligni (Lignin) components that must be recycled after the coffee production due to the rapid spread of coffee culture, Due to the high calorific value and the transition to NH radicals during the combustion process, the cashew cells with strong NO reduction characteristics are properly mixed to maximize the advantages of each component, resulting in good formability, high calorific heat generation, and eco-friendly Provided is a method for producing fuel pellets and fuel pellets by the method, which can be utilized as alternative energy.

As a means for achieving the above object,

A first grinding screening step of crushing sawdust generated from wood processing or solid wood or lumber in a first crusher to sort the sawdust into a predetermined first size;

A drying step of obtaining a constant water content of the sawdust after the first grinding screening step;

A second grinding screening step of grinding the sawdust after the drying step with a second grinding machine to form and mix well, and sorting the sawdust into a predetermined second size;

A storage step of storing the sawdust having finished the second grinding step in a sawdust storage room;

Roasting drying step of drying after harvesting dried cashew nuts roasted with a roaster;

A peeling cooling step of peeling and cooling the roasted and dried cashew nuts with a sheller;

An endothelial grinding step of peeling the endothelial with the filler to finish the peeling cooling step and pulverizing the endothelial with a grinder to make the cashew nut endothelial powder;

A storage step of selecting the cashew nut endothelial powder after the endothelial grinding step and storing in the powder storage;

A sorting step of sorting the collected coffee grounds after finishing coffee production using a sorting machine;

A drying step of obtaining a predetermined moisture content of the selected coffee grounds;

A storage step of storing the sorted and dried coffee grounds in a powder reservoir;

Mixing coffee grounds, cashew nut endothelial powder, and sawdust stored in each of the reservoirs in a mixer at a predetermined ratio;

Compressing the mixed coffee grounds, cashew nuts endothelial powder, sawdust in a pellet maker to produce a pellet.

The first size of the sawdust includes 4 to 5 mm.

The second size of the sawdust includes less than 2mm.

The size of the cashew nut endothelial powder includes 2 mm or less.

The constant moisture content of the sawdust includes less than 10%.

The manufactured pellets include those having a diameter of 6 mm or less and a length of 19 mm or less.

The predetermined ratio of mixing the coffee grounds, cashew nuts endothelial powder, sawdust preferably includes coffee grounds 5-7, cashew nuts endothelial powder 1.5-2, sawdust 1.5-3.

As a means for achieving the above object,

A first grinding screening step of crushing sawdust generated from wood processing or solid wood or lumber in a first crusher to sort the sawdust into a predetermined first size;

A drying step of obtaining a constant water content of the sawdust after the first grinding screening step;

A second grinding screening step of grinding the sawdust after the drying step with a second grinding machine to form and mix well, and sorting the sawdust into a predetermined second size;

A storage step of storing the sawdust having finished the second grinding step in a sawdust storage room;

Roasting drying step of drying after harvesting dried cashew nuts roasted with a roaster;

A peeling cooling step of peeling and cooling the roasted and dried cashew nuts with a sheller;

An endothelial grinding step of peeling the endothelial with the filler to finish the peeling cooling step and pulverizing the endothelial with a grinder to make the cashew nut endothelial powder;

A storage step of selecting the cashew nut endothelial powder after the endothelial grinding step and storing in the powder storage;

A sorting step of sorting the collected coffee grounds after finishing coffee production using a sorting machine;

A drying step of obtaining a predetermined moisture content of the selected coffee grounds;

A storage step of storing the sorted and dried coffee grounds in a powder reservoir;

Mixing coffee grounds, cashew nut endothelial powder, and sawdust stored in the respective reservoirs in a mixer at a predetermined weight ratio;

The mixed sawdust, cashew nut endothelial powder, and coffee grounds include pellets for fuel made by compression in a pellet maker.

The coffee grounds, cashew nut endothelial powder, sawdust is preferably mixed with coffee grounds 5-7, cashew nut endothelial powder 1.5-2, sawdust 1.5-3 weight ratio.

According to the present invention as described above, due to the rapid spread of coffee culture coffee grounds, ligni (Lignin) adhesive components that must be recycled after the production of coffee, there is a lot of sawdust, the calorific value of the adhesive effect when making pellets for fuel Since it is transferred to NH radicals during the combustion process, the cashew cells with strong NO reducing properties are properly mixed to maximize the advantages of each component, and have good moldability, high heat dissipation, and excellent moisture resistance. Pellets for fossil fuels can be obtained that can be easily stored and transported and can be used as environmentally friendly alternative energy.

In addition, it is possible to smoothly solve the rapidly increasing problem of coffee grounds to clean the urban environment of each region.

1 is a picture showing the various uses of coffee grounds.
Figure 2 is a comparison table of bio-pellets calorific value made of coffee grounds and other raw materials.
Figure 3 is a process chart showing a fuel pellet manufacturing method using coffee grounds, cashew nuts, sawdust of the present invention.
Figure 4 is a photograph showing a sawdust made by some processes of the present invention.
5 is a photograph showing the cashew nut structure, which is some process material of the present invention.
6 is a photograph showing coffee grounds made by some processes of the present invention.
Figure 7 is a photograph showing the main parts of the pellet manufacturing machine for making fuel pellets using coffee grounds, cashew nuts, sawdust of the present invention.
Figure 8 is a fuel pellet photo made by the method for producing fuel pellets using coffee grounds, cashew nuts, sawdust of the present invention.
9 is a quality test result of the solid fuel pellets made by the applicant of the present invention in the same process as the present invention.
FIG. 10 is a report showing a quality test result of a sample of solid fuel pellets prepared by the applicant of the present invention in the same process as that of the present invention.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing the embodiments of the present invention, and the embodiments of the present invention may be embodied in various forms. It should not be construed as limited to the embodiments described in.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in the text. However, this is not intended to limit the present invention to the specific form disclosed, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for the components.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between. Other expressions describing the relationship between components, such as "between" and "immediately between," or "neighboring to," and "directly neighboring to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof that has been described, and that one or more of them is present. It is to be understood that it does not exclude in advance the possibility of the presence or addition of other features or numbers, steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described a preferred embodiment of the present invention. The same reference numerals are used for the same elements in the drawings, and duplicate descriptions of the same elements are omitted.

Figure 3 is a process chart showing a fuel pellet manufacturing method using coffee grounds, cashew nuts, sawdust of the present invention.

Referring to Figure 3, the present invention is because the material is coffee grounds, cashew nuts, sawdust, each part of the material is made and stored in a predetermined proportion after mixing and molding the pellets produced by the manufacturing process and the packaging is manufactured by such a process Pellets for fuel.

Sawdust manufacturing steps (S100a, S100b), the sawdust generated in the sawmill or woodworking factory, or the process of grinding the wood or lumber to make sawdust made in the sawdust maker.

Sawdust combines the individual materials during compression molding with the combined lignin (ligign) when making pellets. When pellets are made from sawdust alone, it produces 3000 to 4000 Kcal / kg of calories.

In the first grinding selection step (S110, S120), since the sawdust obtained in the sawdust manufacturing step may be different in size or some foreign matter depending on the process, a predetermined first size (4 ~ 5cm for convenience of work) Pulverize into) and select in the first sorter. The first sorter is the size of the sawdust and also screens foreign matters that cause problems such as vinyl.

In order to remove the moisture of the sawdust after the first grinding screening step, the drying step (S130) is carried out through a dryer to make the moisture of the sawdust to 10% or less. The lower the moisture of the sawdust is, the better, but when the pellets are mixed with each other in the future, a certain amount of moisture must be present for the molding to be performed.

In the second crushing selection step (S140, S150), the dried sawdust is pulverized again to make a second size (2 mm or less) size of each material is good to mix molding and select. 4 is a photograph showing the sawdust being selected.

The size of the selected sawdust 100 after the second crushing selection step is less than 2mm, the moisture content is less than 10% and stored in a dry cool sawdust storage. (S160)

5 is a photograph showing the cashew nut structure, which is some process material of the present invention.

The cashew nut used in the present invention is an edible seed of the cashew tree belonging to the family Sumac. Cashewnet used in the present invention refers to only the endothelial 220 from which the seed 200 is removed and the outer shell 210 is also removed as shown in FIG. 5. The cashew net has a calorific value of about 6000 kcal / kg, which is much higher than that of a general wood 3000 to 4000 Kcal / kg.

Cashewnet inner shell 220 is a hydrophobic material having excellent moisture resistance and extremely low hygroscopicity, so it is convenient to store and transport for a long time, and does not absorb the surrounding moisture at the time of storage, thereby preventing the lowering of calorific value and mixing with other materials to pellet fuel for fuel. It is very good for the thermal power plant which is used in large scale because of high calorific value and easy storage management.

Referring again to Figure 4, the cashew net processing process, cashew nuts are distributed in Central and South America as the origin of the tropical region, but recently developed as a raw material of biomass as well as edible, it is rapidly spread in Asia and Vietnam with coffee It produces intensively.

Harvesting is carried out the roasting drying step (S210, S220) to dry after roasting the cashew nuts (S200) after the natural drying process to a roaster. Roasting and drying is a general process for separating the seed and the inner skin well.

Peeling the roasted and dried cashew nut sheller (Sheller) and peeling the cooling step (S230, S240) proceeds, and the peeled cashew nuts after the peeling cooling step peeled the endothelial from the kernel seed (Peeler), endothelial Grinding with a grinder to proceed with the end grinding step (S250, S260) to make the cashew nut endothelial powder.

Peel the endothelium from the kernel seeds, and squeeze the endothelium into oil before crushing the endothelium with a grinder. The separated kernel seeds also undergo a process to be milked or used for food. However, kernel seeds are not used in the present invention and no further mention is made. The oiled endothelium is dried at 65-75 ° C. The oil residues on the endothelium during the drying process at 65-75 ° C naturally evaporate away. Cashewnet oil is difficult to make pellets because of its incompatibility with water because it does not form when the oily lining is mixed with other materials.

After the endothelial grinding step, the cashew nut endothelial powder is selected and stored in a powder storage step (S270, S280).

After the coffee production, the collected coffee grounds (S300) proceeds to the screening step (S310) for sorting using a sorting machine to pick up coffee grounds without foreign matter and without lumps.

After the step of drying the selected coffee grounds to have a constant moisture content (S320) and proceeds to the storage step (S330) for storing the screened and dried coffee grounds in a powder reservoir to produce a coffee ground (300). 6 coffee grounds pictures)

The coffee grounds may have different particle size or moisture content depending on the coffee maker. Therefore, the coffee grounds are sorted through the screening process and the water content is controlled to less than 10% through the drying process. If the water content is too high, it is difficult to mix with other materials and drying process is prolonged after the molding of the pellets. Therefore, it is better to manage the water content of coffee grounds, cashewnet endothelial powder and sawdust to 10% or less.

The calorific value specification for wood pellets supplied to a typical thermal power plant requires more than 3900 kcal / kg. The BioSRF (Waste Solid Fuel) calorific value specification is 4300 kcal / kg.

As a result of measuring the calorific value by making pellets with only the coffee grounds obtained in the present invention, an average of 5000-5500 kcal / kg was obtained.

Only the cashew nut endothelial powder obtained in the present invention was pelleted, and the calorific value was measured. On average, 5000-6000 kcal / kg was obtained.

As a result of measuring the calorific value of pellets made only with the sawdust obtained in the present invention was able to obtain 3000-4500kcal / kg on average.

Each component was mixed and passed through BioSRF (Waste Solid Fuel) calorific value specification 4300kcal / kg, and the optimum mixing ratio considering economic efficiency was studied.

Pros and cons of each material are listed in a table.

Table 1: Comparison of the pros and cons of coffee grounds cashew nuts endothelial powder

In consideration of the advantages and disadvantages of each material, the experiment was made by mixing ratios.

Table 2: Coffee grounds Cashew nuts  Endothelial Powder Sawdust Mixing Ratio Experimental group  Compare results

When analyzing the result data of each experimental group, the critical point is that the coffee grounds should have at least 5 weight ratio in consideration of economic efficiency, and sawdust should have at least 1 weight ratio in consideration of moldability. In terms of distribution, cashew nut endothelial powder should have a weight ratio of 1 or more.

From this point of view, the third experimental group, the fourth experimental group, and the fifth experimental group are in the range. (The second experimental group had a satisfactory range but it was not economical because the cashew net weight ratio was high)

However, the present invention should be corrected for hydrophilic properties in the fifth experimental group, considering that it is consumed in large quantities and must be resistant to moisture during storage distribution because it must be used for delivery to a thermal power plant rather than a commonly used biosrf (waste solid fuel). .

Therefore, if you look for the range of available correction mix ratio (weight ratio) by extracting the optimum value from each experimental group, you can get 5-7 coffee grounds, 1.5-2 for cashew nut inner powder, and 1.5-3 weight for sawdust.

Coffee grounds 5-7, cashew nuts endothelial powder 1.5-2, sawdust 1.5-3 put into the mixer in a weight ratio and mix (S400). Depending on the moisture content of each material at the time of mixing can be mixed with a little moisture in order to facilitate molding.

Coffee grounds 5-7, cashew nuts endothelial powder 1.5-2, sawdust 1.5-3 by weight in a mixer after mixing in a pellet maker to form a pellet and cooled (S410, S420).

Figure 7 is a photograph showing the main parts of the pellet manufacturing machine for making fuel pellets using cashew nuts, sawdust, coffee grounds of the present invention.

The mixture of coffee grounds 5-7, cashew nut endothelial powder 1.5-2, sawdust 1.5-3 weight ratio is put in a pellet maker into a pellet maker and molded by applying pressure. In pellet makers with multiple holes as shown in the picture, fuel pellets are produced and cut to maintain the model.

After cutting to the appropriate size, the cooled fuel pellets are dried and packed and shipped. (S430)

8 is a fuel pellet photograph made of a method for preparing fuel pellets using coffee grounds, cashew nut endothelial powder, and sawdust according to the present invention.

The manufactured pellets 400 shown in the picture are 6 mm or less in diameter and 19 mm or less in length, and their main purpose is pellets for thermal power plant fuel.

9 is a quality test result of the solid fuel pellets made by the applicant of the present invention in the same process as the present invention.

FIG. 10 is a report showing a quality test result of a sample of solid fuel pellets prepared by the applicant of the present invention in the same process as that of the present invention.

Applicant of the present invention has already produced a solid fuel pellet using only sawdust and cashew nut endothelial powder through the same process as the present invention and finished the patent registration of Korea Patent 10-1635974 and environmental evaluation and quality at Korea Environment Corporation (Waste Resources Center) Passed the inspection, it is supplied to the thermal power plant as fuel pellets with quality stability and excellent calorific value.

As mentioned at the beginning of the present invention, a new solid fuel pellet was prepared by using coffee grounds to be recycled after coffee production due to the rapid spread of coffee culture.

As described above, those skilled in the art have been described with reference to the preferred embodiments of the present invention, various modifications of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be understood that this can be changed.

The present invention is not limited to the method for producing fuel pellets using coffee grounds, cashew nuts, sawdust and manufactured by the method, but can be applied to various other projects to make fuel pellets.

100: sawdust 200: cashew nut seed
210: cashew shell 220: casnet inner
300: coffee ground 400: pellet for fuel

Claims (6)

A first grinding screening step of crushing sawdust generated from wood processing or sawdust made by pulverizing wood or lumber in a first crusher to select the first size of 4 to 5 mm;
A drying step of obtaining a water content of 10% or less of the sawdust after the first grinding screening step;
A second grinding screening step of grinding the sawdust after the drying step with a second grinding machine to form and mix well, and sorting the sawdust into a second size of 2 mm or less;
A storage step of storing the sawdust having finished the second grinding step in a sawdust storage room;
Roasting drying step of drying after harvesting dried cashew nuts roasted with a roaster;
A peeling cooling step of peeling and cooling the roasted and dried cashew nuts with a sheller;
The endothelial grinding step of peeling the endothelial using the filler to finish the peeling cooling step and pulverizing the endothelial powder with a grinder having a size of the endothelial powder 2 mm or less to make the cashew nut endothelial powder;
A storage step of selecting the cashew nut endothelial powder after the endothelial grinding step and storing in the powder storage;
A sorting step of sorting the collected coffee grounds after finishing coffee production using a sorting machine;
A drying step of obtaining water content of 10% or less of the selected coffee grounds;
A storage step of storing the sorted and dried coffee grounds in a powder reservoir;
The materials stored in the respective reservoirs are mixed into the mixer at a weight ratio of 5-7, cashew nut endothelial powder 1.5-2, sawdust 1.5-3 by weight so as to have good moldability, high calorific value, high water resistance and economic efficiency. step;
The mixed mixture is compressed in a pellet manufacturing machine having a plurality of molding holes, so that the calorific value is 4300 kcal / kg or more, and pellets for thermal power plant fuels are 6 mm or less in diameter and 19 mm or less in length. Pellet production method. delete delete delete delete Pellets for thermal power plant fuel pellets produced by the method according to claim 1, wherein the calorific value is 4300 kcal / kg or more, and the pellets are 6 mm or less in diameter and 19 mm or less in length.

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