JPWO2018181919A1 - Biomass solid fuel and method for producing the same - Google Patents

Abstract

An object of the present invention is to provide a biomass solid fuel having excellent pulverizability, high yield, and reduced manufacturing cost. The present invention relates to a biomass solid fuel having an air-dry base fuel ratio (fixed carbon / volatile matter) of 0.1 to 0.5.

Description

  The present invention relates to a solid fuel obtained by subjecting biomass to hydrothermal carbonization and a method for producing the solid fuel.

  As one of the measures to prevent global warming, biomass as a biofuel is used as an energy source. For example, biomass is used as a partial substitute fuel for coal in coal-fired power generation facilities. In order to use biomass in a coal-fired power generation facility, it is necessary to pulverize the biomass to improve combustion efficiency. Since the coal-fired power generation facility has a coal crusher for crushing coal, biomass is crushed by the coal crusher together with coal, and the crushed biomass and pulverized coal are mixed and burned (co-firing).

  In addition, since biomass generally has a high porosity and is poor in energy transportability, and has a high water content, it has a low thermal energy density and has a small calorific value when used as a fuel as it is. Therefore, the biomass is used by being dried and crushed to be pelletized, or the biomass is carbonized.

  However, it is not easy to finely pulverize biomass with a coal pulverizer, the pulverizability is worse than that of coal, and there is a problem that it cannot be sufficiently pulverized. Patent Document 1 describes a solid fuel obtained by dry-heating a shell obtained by squeezing kernel oil from palm fruit seeds with a rotary kiln or the like to carbonize the shell.

WO2012 / 023479

  However, the solid fuel described in Patent Document 1 has a problem that it causes a cost increase because of a high carbonization temperature.

  One aspect of the present invention relates to the following items.

  1. A biomass solid fuel having an air-dry base fuel ratio (fixed carbon / volatile matter) of 0.1 to 0.5.

2. Using the shell after squeezing the kernel oil from the seeds of the palm fruit,
The biomass solid fuel according to the above 1, wherein the proportion of K ₂ O in the anhydrous base ash is 0.50 to 3.00 wt%.

3. Using the shell after squeezing the kernel oil from the seeds of the palm fruit,
3. The biomass solid fuel according to 1 or 2 above, wherein the content of Na ₂ O in the anhydrous base ash is 0.79 wt% or less.

4. Using the shell after squeezing the kernel oil from the seeds of the palm fruit,
1 to 3 above, characterized in that the fuel ratio is 0.26 to 0.50 on an air dry basis, the higher heating value on an anhydrous basis is 5100 to 6000 kcal / kg, and the ball mill grindability index is 30 or more. The described biomass solid fuel.

5. A step of hydrothermally carbonizing the shell after squeezing the kernel oil from the seeds of the palm fruit, at a temperature of 190 to 250 ° C. and a pressure of 1.0 to 4.0 MPa (G).
5. The method for producing a biomass solid fuel according to any one of 2 to 4 above.

6. Made from crushed bamboo,
The biomass solid fuel according to the above 1, wherein the ratio of K ₂ O in the anhydrous base ash is 3.00 to 21.50 wt%.

7. Using EFB as a raw material,
The biomass solid fuel according to the above 1, wherein the proportion of K ₂ O in the anhydrous base ash is 0.10 to 40.00 wt%.

  According to the present invention, it is possible to provide a biomass solid fuel having excellent pulverizability, high yield, and reduced manufacturing cost.

3 is a photograph showing a part of an apparatus for applying a stress to observe a fracture surface of a palm kernel shell (PKS). It is a SEM photograph of the fracture surface of PKS. (A) shows the raw PKS before the hydrothermal carbonization treatment, and (b) shows the PKS after the hydrothermal carbonization treatment. It is the figure which further expanded the SEM photograph of FIG. (A) shows the raw PKS before the hydrothermal carbonization treatment, and (b) shows the PKS after the hydrothermal carbonization treatment. It is a figure which shows the composition of the biomass component of PKS before and after a hydrothermal carbonization process. The relationship between the heating temperature of PKS and the pressure in a container is shown. The relationship between the heating temperature of PKS and the pulverizability of solid fuel is shown. The relationship between the heating temperature of PKS and the solid yield of solid fuel (anhydrous basis) and volatile matter (anhydrous ashless basis) is shown. The relationship between the heating temperature of PKS and the energy yield (anhydrous basis) of solid fuel is shown.

<Biomass solid fuel>
The biomass solid fuel (hereinafter, also simply referred to as “solid fuel”) of the present embodiment preferably has an air-dry base fuel ratio (fixed carbon / volatile matter) of 0.1 to 0.5. When the air-dry base fuel ratio is 0.1 to 0.5, a solid fuel having excellent pulverizability and high calorie can be obtained.

  The raw material of the biomass solid fuel of the present embodiment is not particularly limited, but for example, shells obtained by squeezing kernel oil from the seeds of palm fruit (hereinafter, also referred to as “palm kernel shell” or “PKS”), bamboo, EFB (Empty Fruit Bunches: empty fruit bunch of palm oil processing residue) is mentioned, and PKS is preferable among these. PKS can be made into a solid fuel by performing hydrothermal carbonization treatment in its original shape without crushing or crushing, etc., and since the shell remains in its original form even after hydrothermal carbonization treatment, it is easy to handle. Excellent in.

  The biomass solid fuel of the present embodiment is obtained through a hydrothermal carbonization treatment step in which raw material biomass is heated in pressurized hot water and carbonized. In the hydrothermal carbonization treatment, it is preferable that water and raw material biomass are charged into a closed container and heated to a predetermined temperature. Here, the weight ratio (liquid / solid ratio) represented by (water used for hydrothermal carbonization / biomass of raw material) is not particularly limited, but is preferably 1 to 50, and more preferably 1 to 5. . In this specification, hydrothermal carbonization treatment is also referred to as “wet”.

  The conditions of the hydrothermal carbonization treatment are not particularly limited, but for example, the temperature is preferably 150 ° C. or higher, more preferably 190 ° C. or higher, and preferably 250 ° C. or lower, more preferably 230 ° C. or lower. The rate of temperature increase is not particularly limited, but is preferably 1 to 10 ° C./minute, more preferably 1 to 5 ° C./minute from the atmospheric temperature to the desired heating temperature.

  The pressure in the hydrothermal carbonization treatment is preferably 1.3 to 4.1 MPa (G), more preferably 1.3 to 3.7 MPa (G), and further preferably 2.9 to 3.7 MPa (G). . When hydrothermal carbonization treatment is performed in a closed container, the pressure is determined by the heating temperature, but because the decomposition gas of biomass is also generated by heating, the pressure inside the container is the saturated steam pressure of water at the heating temperature and the decomposition gas of water. It is the sum of the vapor pressure. As an example, FIG. 5 shows the relationship between the heating temperature and the pressure when PKS is used as the raw material in Example A described later. As shown in FIG. 5, the generation of decomposition gas tends to remarkably increase as the heating temperature increases.

  The hydrothermal carbonization time is preferably 10 minutes to 40 minutes, more preferably 20 minutes to 40 minutes, and further preferably 30 minutes to 40 minutes after reaching the desired heating temperature. After that, it is cooled and opened.

  The apparatus used for the hydrothermal carbonization treatment is not limited, but it is preferable to use, for example, an autoclave.

  In the present embodiment, by performing the hydrothermal carbonization treatment on the raw material, the heat transfer efficiency is higher than that in the case of the dry carbonization treatment, so that it is possible to obtain the solid fuel excellent in pulverizability by heating at a low temperature. Therefore, the manufacturing cost can be reduced. Furthermore, since the solid fuel of the present embodiment is manufactured at a lower heating temperature than the dry carbonization process, the energy loss due to the carbonization process can be suppressed and the yield (solid yield and energy yield) is excellent (FIG. 7). And FIG. 8).

  The raw material of the biomass includes components such as potassium component, sodium component and chlorine component that cause the problem of boiler corrosion, but the solid fuel of the present embodiment has a small content of these components. It is speculated that this is because the above components are eluted into water during the hydrothermal carbonization treatment.

  The suitable range of the properties of the biomass solid fuel and the method for producing the same may be determined depending on the type of biomass used as the raw material. Hereinafter, one example thereof will be described, but the present invention is not limited thereto. The industrial analysis value, elemental analysis value, and higher heating value in this specification are based on JIS M 8812, 8813, 8814. Details of the method for measuring the ball mill crushing index (BMI) will be described in Examples below. Further, the air-dry base refers to the solid weight measured by the method for preparing an air-dry sample described in Japanese Industrial Standard JIS M8811.

<Solid Fuel A: Biomass Solid Fuel Made from PKS>
As one aspect of the present invention, a biomass solid fuel (also referred to as “solid fuel A”) using PKS as a raw material will be described. The PKS as a raw material preferably has a water content of 40% by mass or less, and more preferably a water content of 15% by mass or less. The preferable aspects of the properties of the solid fuel A are as follows.

  The solid fuel A preferably has a fuel ratio (fixed carbon / volatile matter) of 0.26 to 0.50 on an air-dry basis. When the fuel ratio is within the above range, it is possible to obtain a solid fuel having excellent pulverizability while suppressing a decrease in volatile matter. The air-dry base fixed carbon of the solid fuel A is preferably 18 to 50% by weight, more preferably 20 to 35% by weight, and further preferably 24.1 to 28% by weight. The volatile content (air-dry basis) is preferably 60 to 70% by weight, more preferably 60 to 68% by weight, and further preferably 60 to 64.9% by weight. The volatile matter contained in the solid fuel is, for example, a part aromatic.

  The proportion of ash on an anhydrous basis in the solid fuel A is preferably 5.0% by weight or less, more preferably 4.0% by weight or less. The lower limit is not particularly limited, but is preferably 1.9% by weight or more, more preferably 2.2% by weight or more. The air-dry base ash content in the solid fuel A is preferably 4.5% by weight or less, more preferably 3.5% by weight or less. The lower limit is not particularly limited, but is preferably 1.8% by weight or more, more preferably 2.0% by weight or more.

In the solid fuel A, the proportion of K ₂ O in the anhydrous base ash is preferably 0.50 to 3.00 wt%, more preferably 0.50 to 2.00 wt%, and further 0.50 to 1.50 wt%. Preferably, 0.50 to 1.00 wt% is even more preferable. Too much potassium component in the solid fuel may cause problems such as corrosion of the boiler when used as a fuel. Although PKS as a raw material contains a potassium component, it is presumed that in the present embodiment, the potassium component is dissolved in water during the hydrothermal carbonization treatment, and the potassium component contained in the solid fuel can be reduced.

In the solid fuel A, the proportion of Na ₂ O in the anhydrous base ash is preferably 0.79 wt% or less, more preferably 0.75 wt% or less, and further preferably 0.70 wt% or less. It may be 0 wt%. If the solid fuel contains too much sodium, it may cause problems such as corrosion of the boiler when used as a fuel. Although PKS as a raw material contains a sodium component, it is presumed that in the present embodiment, the sodium component is dissolved in water during the hydrothermal carbonization treatment, and the sodium component contained in the solid fuel can be reduced.

  The anhydrous base high heating value is preferably 5100 to 6000 kcal / kg, more preferably 5510 to 6000 kcal / kg.

The ball mill grindability index (BMI ₂₀ ) is preferably 30 or more, more preferably 80 or more. BMI ₂₀ can be measured by the method described in Examples below.

  The solid fuel A has almost the same particle size as that of raw PKS, and the pulverization during handling is suppressed. Therefore, when transporting the solid fuel after hydrothermal carbonization, there is no contamination of the surroundings due to dust generation. The average particle size of raw PKS is usually about 5 mm, and the average particle size of solid fuel A is also about 5 mm. Here, the average particle diameter as referred to in the present invention means a median diameter, and is determined by the particle size test method described in JIS M8801.

  In the method for producing the solid fuel A, the condition for hydrothermal carbonizing the raw material PKS is not particularly limited, but the heating temperature is preferably 190 to 250 ° C, more preferably 190 to 230 ° C, and the pressure is The pressure is preferably 1.0 to 4.0 MPa (G), more preferably 1.3 to 3.7 MPa (G), and further preferably 2.9 to 3.7 MPa (G).

<Solid fuel B: Biomass solid fuel made from bamboo>
As one embodiment of the present invention, a biomass solid fuel (also referred to as “solid fuel B”) made from bamboo will be described. The bamboo is preferably crushed bamboo.

  The solid fuel B preferably has a fuel ratio (fixed carbon / volatile matter) of 0.10 to 0.50 on an air-dry basis.

  The proportion of ash on an anhydrous basis in the solid fuel B is preferably 1.3% by weight or less, more preferably 1.0% by weight or less. The lower limit is not particularly limited, but is preferably 0.6% by weight or more. The air-dry base ash content in the solid fuel B is preferably 1.2% by weight or less, more preferably 1.0% by weight or less. The lower limit is not particularly limited, but is preferably 0.5% by weight or more.

  The proportion of chlorine in the solid fuel B is preferably 0.15 wt% or less, more preferably 0.10 wt% or less, even more preferably 0.07 wt% or less, and may be 0 wt%. Raw bamboo, which is a raw material of the solid fuel B, contains a chlorine component, and when the chlorine component is too much, the problem such as the corrosion of the boiler occurs. However, the solid fuel B of the present embodiment has a chlorine component content. Few. It is speculated that this is because the chlorine component is eluted in the water during the hydrothermal carbonization treatment.

In the solid fuel B, the proportion of K ₂ O in the anhydrous base ash is preferably 3.00 to 21.50 wt%, more preferably 3 to 20 wt%, and 4 to 19 wt%. More preferably, 5 to 18 wt% is even more preferable. Too much potassium component in the solid fuel may cause problems such as corrosion of the boiler when used as a fuel. Although the raw material bamboo contains a potassium component, it is presumed that the potassium component is eluted into the water during the hydrothermal carbonization treatment in the present embodiment, and the potassium component contained in the solid fuel can be reduced.

  The anhydrous base high heating value is preferably 5000 to 6000 kcal / kg.

The ball mill grindability index (BMI ₂₀ ) is preferably 30 or more, and more preferably 60 or more. BMI ₂₀ can be measured by the method described in Examples below.

  In the method for producing the solid fuel B, the condition for hydrothermal carbonizing raw bamboo as a raw material is not particularly limited, but the temperature is preferably 190 ° C to 220 ° C, more preferably 190 ° C to 210 ° C, The pressure is preferably 0.9 to 2.4 MPa (G).

<Solid Fuel C: Biomass Solid Fuel Made from EFB>
As one aspect of the present invention, a biomass solid fuel (also referred to as “solid fuel C”) using EFB as a raw material will be described. The properties of the solid fuel C are as follows.

  The solid fuel C preferably has a fuel ratio (fixed carbon / volatile matter) of 0.1 to 0.5 on an air-dry basis.

  The proportion of ash on an anhydrous basis in the solid fuel C is preferably 2.3% by weight or less, more preferably 1.9% by weight or less, still more preferably 1.7% by weight or less. The lower limit is not particularly limited, but is preferably 0.6% by weight or more. The air-dry base ash content in the solid fuel C is preferably 2% by weight or less, more preferably 1.8% by weight or less, and further preferably 1.5% by weight or less. The lower limit is not particularly limited, but is preferably 0.5% by weight or more.

  Raw EFB, which is a raw material of the solid fuel C, contains a chlorine component, and if the chlorine component is too much, there is a problem such as corrosion of the boiler. However, in the solid fuel C of the present embodiment, the content of the chlorine component is Few. It is speculated that this is because the chlorine component is eluted in the water during the hydrothermal carbonization treatment. The proportion of chlorine in the solid fuel C is preferably 0.2 wt% or less, more preferably 0.01 wt% or less, even more preferably 0.008 wt% or less, and may be 0 wt%.

In the solid fuel C, the proportion of K ₂ O in the anhydrous base ash content is preferably 0.10 to 40.00 wt%, more preferably 1.0 to 25 wt%, and 1.0 to 20 wt%. Is more preferable, and 1.0 to 18 wt% is even more preferable. Too much potassium component in the solid fuel may cause problems such as corrosion of the boiler when used as a fuel. EFB as a raw material contains a potassium component, but in the present embodiment, it is presumed that the potassium component is eluted into water during the hydrothermal carbonization treatment, and the potassium component contained in the solid fuel can be reduced.

In the solid fuel C, the proportion of Na ₂ O in the anhydrous base ash content is preferably 1.0 wt% or less, more preferably 0.70 wt% or less, and further preferably 0.5 wt% or less. , May be 0 wt%. If the solid fuel contains too much sodium, it may cause problems such as corrosion of the boiler when used as a fuel. Although EFB as a raw material contains a sodium component, it is presumed that in the present embodiment, the sodium component is dissolved in water during the hydrothermal carbonization treatment, and the sodium component contained in the solid fuel can be reduced.

  The anhydrous base high heating value is preferably 4510 to 6500 kcal / kg, more preferably 4590 to 6500 kcal / kg.

The ball mill grindability index (BMI ₃ ) is preferably 15 or more. BMI ₃ can be measured by the method described in Examples below.

  In the method for producing the solid fuel C, the conditions for hydrothermal carbonization of raw EFB as a raw material are not particularly limited, but the temperature is preferably 150 ° C to 250 ° C, more preferably 200 ° C to 250 ° C, and the pressure. Is preferably 0.3 to 4.2 MPa (G), and more preferably 0.4 to 4.1 MPa (G).

  The solid fuel of the present invention is used as an energy source of heat utilization equipment by being supplied to the heat utilization equipment and burned. In particular, the solid fuel of the present invention is preferably supplied to a heat utilization facility and burned as a partial substitute fuel for coal.

  The heat utilization equipment in which the solid fuel of the present invention is used is not limited, and existing heat utilization equipment can be used, for example, a pulverized coal burning boiler, a rotary kiln of a cement clinker manufacturing facility, and a cement clinker. Examples thereof include a calcination furnace for manufacturing equipment, a cokes furnace for steel manufacturing equipment, a blast furnace, and the like. Among these, a pulverized coal burning boiler, a rotary kiln for cement clinker manufacturing equipment, and a calcining furnace are preferable.

  The solid fuel of the present invention may be pulverized and then supplied to the heat utilization facility in order to improve combustion efficiency. The degree of this pulverization depends on the heat utilization equipment to which the solid fuel is supplied, but it is usually good to pulverize it so that the average particle diameter is 1,000 μm or less, and the average particle diameter is 750 μm or less. Is more preferable.

  The solid fuel of the present invention has excellent pulverizability and can be easily pulverized with a vertical roller mill, a tube mill, a hammer mill, a fan type mill, and the like. It can also be easily milled with coal in a machine. Further, it is possible to supply the solid fuel together with coal to a heat utilization facility for combustion.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

  The methods for measuring the properties of solid fuels in Examples and Comparative Examples are as follows.

<Solid yield, energy yield>
The solid yield and energy yield were calculated by the following formulas.

Solid yield (anhydrous basis) (% by weight) = 100 × solid weight after hydrothermal carbonization (anhydrous basis) / solid weight before hydrothermal carbonization (anhydrous basis)
Energy yield (anhydrous basis) (cal%) = solid higher calorific value after hydrothermal carbonization (anhydrous basis) x solid yield (anhydrous basis) (wt%) / solid higher calorific value before hydrothermal carbonization ( Anhydrous base)

<XRF analysis of ash>
Using a fluorescent X-ray analyzer (EDX-720 manufactured by Shimadzu Corporation), the weight ratio of the compounds shown in Tables 2 and 4 contained in the anhydrous base ash was measured.

<Ball mill grindability (BMI ₂₀ )>
The crushing time for each biomass solid fuel was set to 20 minutes, and the weight ratio under the 150 μm sieve after 20 minutes was used as the crushing point. It should be noted that the ball mill used is in accordance with JIS M4002, and a cylindrical container having an inner diameter of 305 mm and an axial length of 305 mm is provided with a standard grade ball bearing (Φ36.5 mm × 43 pieces, Φ30.2 mm × 67 pieces) defined in JIS B1501. (Φ24.4 mm × 10 pieces, Φ19.1 mm × 71 pieces, Φ15.9 mm × 94 pieces) were put and rotated at a speed of 70 rpm for measurement. The higher the value, the better the pulverizability. It was confirmed that the pulverization point was increased by performing the hydrothermal carbonization treatment.

<Ball mill grindability (BMI ₃ )>
Measurement was carried out by the same method as in BMI ₂₀ except that the crushing time of the biomass solid fuel was 3 minutes, and the weight ratio under the 150 μm sieve was used as the crushing point.

<Example A: PKS>
(Example A1: wet type)
The PKS was dried in the sun to a water content of 12% by mass, and had a particle size of 1 to 16 mm and an average particle size of 5 mm. 280 g of this dried PKS and 840 g of water (solid-liquid ratio 3) were put into a 1.95 L autoclave and heated from ambient temperature to 190 ° C. at a temperature rising rate of 3.6 ° C./min. After the heating temperature reached 190 ° C. and the pressure reached 1.3 Mpa (G), the temperature was maintained for 30 minutes for hydrothermal carbonization treatment, and then cooled to room temperature to obtain a solid fuel. The properties of the obtained solid fuel are shown in Tables 1 and 2.

(Examples A2 to A5: wet type)
A solid fuel was produced in the same manner as in Example A1 except that the conditions of the hydrothermal carbonization treatment were changed as shown in Table 1. The properties of the obtained solid fuel are shown in Tables 1 and 2.

(Comparative Example A1)
The properties of the solid fuel made of raw PKS before hydrothermal carbonization are shown in Tables 1 and 2.

(Comparative Example A2: Dry type)
The same dried PKS as in Example A1 was used as the raw material. 4 kg of this PKS is put into a sample case having an inner diameter of 600 mm and a length of 500 mm, and the whole sample case is attached to an external heat type rotary kiln, and a temperature rising rate from the atmospheric temperature to 290 ° C. while circulating nitrogen gas which is an inert gas. Heated at 2 ° C / min. The standard heating temperature was the temperature of the gas phase atmosphere in the central portion of the center of the axis of the sample case. In the rotary kiln, the temperature of the vapor phase atmosphere and the temperature of the heat-treated solid are the same. After the heating temperature reached 290 ° C., the temperature was maintained at 290 ° C. for 1 minute, and then quickly cooled to 160 ° C. After that, the sample case was taken out from the rotary kiln, and the sample was taken out into the atmosphere and cooled to room temperature.

(Comparative Examples A3 to A7: Dry type)
A solid fuel was produced by the same method as in Comparative Example A2 except that the heating temperature was changed to the temperature shown in Table 1. The properties of the obtained solid fuel are shown in Tables 1 and 2.

(Heating temperature and pressure)
FIG. 5 shows the relationship between the heating temperature of PKS and the pressure. The higher the heating temperature, the greater the generation of decomposition gas. The decomposition gas was mainly composed of CO ₂ , and further contained a small amount of water gas (H ₂ , CO).

(Comparison of wet type and dry type)
A solid fuel obtained by subjecting the raw material PKS to wet treatment (hydrothermal carbonization treatment) as in Examples A1 to A5 and dry treatment (heat treatment in a gas phase) as in Comparative Examples A2 to A7. 6 to 8 show the results of comparing the pulverizability and the like of the solid fuels obtained as described above.

FIG. 6 shows the relationship between the heating temperature of PKS and pulverizability. The BMI ₂₀ (weight ratio under the 150 μm sieve) was used as an index of pulverizability. BMI ₂₀ = 94% was used as the threshold for the crushing point, and the threshold was reached at about 220 ° C. for the wet type and at about 310 ° C. for the dry type. That is, the wet type showed equivalent pulverizability at a temperature about 90 ° C. lower than that of the dry type. Therefore, when the solid fuel is manufactured by the hydrothermal carbonization treatment, the heating temperature can be set low and the manufacturing cost can be reduced.

FIG. 7 shows the relationship between PKS heating temperature and solid yield (anhydrous basis) and volatiles (anhydrous ashless basis). The solid yields of the solid fuels obtained by the wet process (heating temperature 220 ° C.) and the dry process (heating temperature 310 ° C.) when the grindability point BMI ₂₀ = 94% are 70% and 53%, respectively. The solid yield was higher. The solid yield depends on the amount of volatile matter thermally decomposed, and the wet type can obtain a solid fuel with excellent pulverizability at a lower temperature than the dry type, so the amount of volatile matter thermally decomposed is also suppressed. It was assumed that the solid yield was also high.

  FIG. 8 shows the relationship between the heating temperature of PKS and the energy yield (anhydrous basis). The solid fuel obtained by the wet method maintained the energy yield at about 80%, but the energy yield of the solid fuel obtained by the dry method decreased to 70% by heating. It is considered that this is because the energy yield is affected by the solid yield, and it was shown that the wet type can suppress the energy loss.

<Example B: Bamboo>
(Examples B1 to B4)
A solid fuel was produced in the same manner as in Example A1 except that bamboo was used as the raw material instead of PKS and the hydrothermal carbonization treatment was performed under the conditions shown in Table 3. The properties of the obtained solid fuel are shown in Tables 3 and 4.

(Comparative Example B1)
The properties of the solid fuel made of raw bamboo before the hydrothermal carbonization treatment are shown in Tables 3 and 4.

<Example C: EFB>
(Examples C1 to C3)
A solid fuel was produced in the same manner as in Example A1 except that EFB was used as the raw material instead of PKS and the hydrothermal carbonization treatment was performed under the conditions shown in Table 3. The properties of the obtained solid fuel are shown in Tables 3 and 4.

(Comparative Example C1)
Table 3 and Table 4 show the properties of the solid fuel composed of raw EFB before the hydrothermal carbonization treatment of Example C1.

  In the table below, AD is an air-dry base, dry is an anhydrous base, and Daf is an anhydrous ashless base.

  As described above, the biomass solid fuel after the hydrothermal carbonization treatment has improved pulverizability (improved BMI value) as compared with the raw material. In order to elucidate this mechanism, the present inventors compared the solid fuel obtained by hydrothermal carbonization of PKS (solid fuel of Example A4) with the raw PKS (solid fuel of Comparative Example A1), Detailed analysis was performed.

(Observation of surface condition of fracture surface)
In order to observe the surface condition of the fracture surface of PKS before and after hydrothermal carbonization, a jig was attached to the Kiya type hardness meter and stress (tensile / shear) perpendicular to the fiber direction of PKS was applied (see Fig. 1). A fracture surface orthogonal to the fiber direction was obtained. The load required for breaking (loading speed: 10 mm / min) was 517 N in the raw PKS before the hydrothermal carbonization treatment (Comparative Example A1), but was 54 N in the PKS after the hydrothermal carbonization treatment (Example A4). , Was reduced to about 1/10.

  Before and after the hydrothermal carbonization treatment, the fracture surface of each PKS was observed with an electron microscope (SEM). SEM photographs of the fracture surface are shown in FIG. 2 (200 times enlarged view) and FIG. 3 (1000 times enlarged view). 2 (a) and 3 (a) are photographs of raw PKS (Comparative Example A1) before hydrothermal carbonization treatment, and FIGS. 2 (b) and 3 (b) show after hydrothermal carbonization treatment. 3 is a photograph of the PKS of Example (Example A4). In the SEM photograph of the fracture surface, the raw PKS (Comparative Example A1) had irregularities, whereas the hydrothermal carbonized PKS (Example A4) had a smooth surface (FIG. 3). In the raw PKS (Comparative Example A1), the fibers are gently bonded due to the binder component in the raw material, and therefore it is considered that the fibers are pulled out when the load is applied and the stress is dispersed, resulting in an uneven fracture surface. On the other hand, in the hydrothermally carbonized PKS (Example A4), it is considered that the binder component is solubilized so that the fibers are firmly bonded and the stress is concentrated under load, so that the fracture surface is linear.

  Further, the unevenness of the SEM photograph is considered to be a cell wall because of its size (FIGS. 2 and 3). In general, those that are difficult to break tend to have uneven surface, and those that are easy to break tend to be straight (smooth). That is, since the raw PKS (Comparative Example A1) has a high cell wall strength, breakage that penetrates the wall is unlikely to occur and the breakage occurs along the cell wall surface, whereas the PKS subjected to hydrothermal carbonization treatment (Example A4). ), It is considered that the fracture of the cell wall occurred because the strength of the cell wall decreased. It is assumed that the same applies to the other Examples A1 to A3.

(Analysis of biomass component composition)
The composition of the biomass component of each PKS was analyzed by the method described in Table 5 before and after the hydrothermal carbonization treatment. The results are shown in Table 5 and FIG. In Table 5, "%" means "% by weight".

In the analysis of the biomass component composition, hemicellulose was 23.4 wt% in the raw PKS (Comparative Example A1), but decreased to 8.9 wt% in the hydrothermal carbonized PKS (Example A4). At this time, the decomposition rate of hemicellulose considering the solid yield was 73 wt%. Here, the decomposition rate of hemicellulose is represented by the following formula:
Decomposition rate (%) = 100- [hemicellulose composition (%) of hot-water treated PKS x yield (%)] / [(hemicellulose composition of raw PKS (%) x 100 (%)] x 100
It was calculated by The decomposition rates of the other components were calculated in the same manner.

  From the above results, the pulverizability of PKS subjected to hydrothermal carbonization including Example A4 is that hemicellulose, which plays an important role in maintaining the strength of the biomass skeleton such as the cell wall during hydrothermal carbonization, is decomposed. It was suggested that it was improved by.

Claims (7)

  A biomass solid fuel having an air-dry base fuel ratio (fixed carbon / volatile matter) of 0.1 to 0.5. The biomass solid fuel according to claim 1, wherein
Using the shell after squeezing the kernel oil from the seeds of the palm fruit,
A biomass solid fuel, wherein the proportion of K ₂ O in the anhydrous base ash is 0.50 to 3.00 wt%. The biomass solid fuel according to claim 1 or 2, wherein
Using the shell after squeezing the kernel oil from the seeds of the palm fruit,
A biomass solid fuel, characterized in that the proportion of Na ₂ O in the anhydrous base ash is 0.79 wt% or less. The biomass solid fuel according to any one of claims 1 to 3,
Using the shell after squeezing the kernel oil from the seeds of the palm fruit,
A biomass solid fuel having an air dry base fuel ratio of 0.26 to 0.50, an anhydrous base high heating value of 5100 to 6000 kcal / kg, and a ball mill grindability index of 30 or more. It is a manufacturing method of the biomass solid fuel according to any one of claims 2 to 4,
A step of hydrothermally carbonizing the shell after crushing the kernel oil from the seeds of the fruit of the palm at a temperature of 190 to 250 ° C. and a pressure of 1.0 to 4.0 MPa (G).
Biomass solid fuel manufacturing method. The biomass solid fuel according to claim 1, wherein
Made from crushed bamboo,
A biomass solid fuel, wherein the proportion of K ₂ O in the anhydrous base ash is 3.00 to 21.50 wt%. The biomass solid fuel according to claim 1, wherein
Using EFB as a raw material,
A biomass solid fuel, characterized in that the proportion of K ₂ O in the anhydrous base ash is 0.10 to 40.00 wt%.