Manufacturing method for solid fuel, manufacturing device of solid fuel, and solid fuel

Abstract

To provide a manufacturing method for solid fuel that is highly productive and has a high compression strength.SOLUTION: The manufacturing method for solid fuel comprises a pressing step in which rice husks are pressed at a pressure of 100 MPa or higher using a forming cylinder equipped with a piston.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing solid fuel, an apparatus for producing solid fuel, and solid fuel. [Background technology]

[0002] A batch method is known as one of the conventional methods for producing solid fuels such as bio-coke. As a batch method, for example, a bio-coke production method is known in which biomass granules are filled into a bottomed cylindrical reaction vessel, and the biomass granules are press-molded while being heated in a substantially dense state within a temperature and pressure range to obtain semi-carbonized or semi-carbonized solids, and then cooled to produce bio-coke (see, for example, Patent Documents 1 and 2). Also known is a method for producing biomass solids, which includes the steps of crushing a biomass raw material, filling a cylinder with the crushed biomass raw material, heating the biomass raw material and pressurizing it with a pressure piston, cooling the biomass raw material, and drying the biomass raw material (see, for example, Patent Document 3). Furthermore, a bio-coke production method is known that includes a filling step of filling a reaction vessel with biomass raw materials and a reaction step of pressurizing and molding the biomass raw materials using a pressure head while heating the biomass raw materials in the reaction vessel and then cooling the biomass raw materials. The method is characterized in that the angle between the central axis of the reaction vessel and the axis of motion of the pressure head and the horizontal direction is set to a range of 30° to 75°, and the biomass raw materials are filled by repeatedly charging the biomass raw materials, inserting the pressure head into the reaction vessel, and applying pressure (see, for example, Patent Document 4).

[0003] However, conventional batch-type methods have the problem of low processing capacity and low productivity of solid fuel because they require the loading of biomass feedstock, which is also the case when rice husks are used as a feedstock.

[0004] Furthermore, when producing solid fuel from biomass materials such as rice husks, the moisture contained in the husks is pressurized and heated in a sealed cylinder, reaching a subcritical state, decomposing and softening components such as cellulose, hemicellulose, and lignin. By cooling while applying pressure, the decomposed and softened components combine to produce solid fuel. If cooling while applying pressure is not performed, the subcritical moisture will turn into steam, causing steam explosions or cracking due to steam eruptions, resulting in the solid fuel being unable to be molded or significantly reducing its compressive strength. Conventional manufacturing methods prevent cracking and a decrease in compressive strength of the solid fuel by using a cooling process in which the solid fuel is cooled while applying pressure, but this method also results in reduced productivity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-100812 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-100815 [Patent Document 3] International Publication No. 2006 / 078023 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-246414 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to solve the above-mentioned problems in the prior art and to achieve the following object: That is, the present invention aims to provide a method for producing solid fuel that has high productivity and is capable of producing solid fuel having high compressive strength. [Means for solving the problem]

[0007] The means for solving the above problems of the present invention are as follows. <1> This is a method for producing solid fuel, characterized by including a pushing step in which rice husks are pushed at a pressure of 100 MPa or more using a molding cylinder equipped with a piston. <2> In the pushing step, the rice husks are pushed using a forming cylinder having a diameter of 40 mm or more and 120 mm or less, with a pushing length of 150 mm or more and 200 mm or less. <1> 1. A method for producing a solid fuel according to claim 1. <3> In the pushing step, the piston in the molding cylinder is driven at a rotation speed of 300 rpm or more. <1> from <2> 10. The method for producing a solid fuel according to claim 9, wherein the solid fuel is a hydroxybenzoic acid. <4> In the pushing step, the molding cylinder is heated to 120°C or higher and 200°C or lower. <1> from <3> 10. The method for producing a solid fuel according to claim 9, wherein the solid fuel is a hydroxybenzoic acid. <5> The method further includes a crushing step of crushing the rice husks to a particle size of 2 mm or less before the pushing step. <1> from <4> 10. The method for producing a solid fuel according to claim 9, wherein the solid fuel is a hydroxybenzoic acid. <6> The method includes a drying step of drying the rice husks so that the moisture content of the rice husks is 3% by mass or more and 10% by mass or less before the crushing step. <5> 1. A method for producing a solid fuel according to claim 1. <7> This is a solid fuel manufacturing device characterized by having a pushing means capable of pushing rice husks inside a molding cylinder at a pressure of 100 MPa or more. <8> The molding cylinder has a diameter of 40 mm or more and 120 mm or less, and a pushing length of 150 mm or more and 200 mm or less. <7> 2. The solid fuel manufacturing apparatus according to claim 1. <9> A crushing means for crushing the rice husks to a particle size of 2 mm or less is provided. <7> from <8> 10. The solid fuel manufacturing apparatus according to claim 9, wherein the solid fuel is a fuel having a diameter of 100 mm or less. <10> A drying means for drying the rice husks so that the moisture content of the rice husks is 10% by mass or less is provided. <7> from <9> 10. The solid fuel manufacturing apparatus according to claim 9, wherein the solid fuel is a fuel having a diameter of 100 mm or less. <11> <1> from <6> A solid fuel obtained by the method for producing a solid fuel according to any one of the above. The solid fuel is characterized by an apparent specific gravity of 1.25 or more and 1.40 or less, and a compressive strength of 50 MPa or more and 70 MPa or less. [Effects of the Invention]

[0008] According to the present invention, the above-mentioned problems of the prior art can be solved and the following object can be achieved: That is, the present invention can provide a method for producing solid fuel with high productivity and capable of producing solid fuel having high compressive strength. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an overall schematic view showing an example of a solid fuel production apparatus according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a process of forming solid fuel by a thrusting means of a solid fuel manufacturing apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Solid fuel manufacturing method and solid fuel manufacturing device) The method for producing a solid fuel of the present invention includes a pushing step, and may further include other steps such as a crushing step and a drying step, as required. The solid fuel manufacturing apparatus of the present invention includes a thrusting means, and may further include other means such as a crushing means and a drying means as required. The pushing step can be performed by the pushing means, the crushing step can be performed by the crushing means, and the drying step can be performed by the drying means.

[0011] FIG. 1 is a schematic overall view showing an example of an apparatus for producing solid fuel according to one embodiment of the present invention. The solid fuel manufacturing device 100 has an inlet 10 for feeding rice husks, a screw 20 as a means for feeding the rice husks, a piston 30A and a molding cylinder 30B as a pushing means, and a discharge outlet 40 for discharging the solid fuel.

[0012] FIG. 2 is a schematic diagram showing the process up to the formation of solid fuel by the thrusting means of the solid fuel manufacturing device according to one embodiment of the present invention. The rice husks introduced through the introduction port 10 shown in FIG. 1 are supplied by a screw 20 to a molding cylinder 30B serving as a thrusting means, as shown in FIG.

[0013] The rice husks fed into the forming cylinder 30B are pushed by the piston 30A at a pressure of 100 MPa or more, which causes the water contained in the rice husks to become subcritical, and the subcritical water temporarily decomposes the cellulose, hemicellulose, lignin, and other components contained in the rice husks.

[0014] The rice husks are pushed out by the piston 30A and temporarily decomposed, and as they move towards the outlet 40 formed at the end of the forming cylinder 30B, their temperature drops and they solidify, becoming a solid fuel with high compressive strength.

[0015] <Pushing process and pushing means> The pushing step is not particularly limited and can be appropriately selected depending on the purpose. For example, the rice husks can be pushed at a pressure of 100 MPa or more using a piston and a molding cylinder.

[0016] The pressure of the piston in the thrusting step is 100 MPa or more, preferably 100 MPa or more and 250 MPa or less, and more preferably 200 MPa or more and 250 MPa or less. In the pushing process, the rice husks are pushed with a pressure of 100 MPa or more, generating impact heat and frictional heat inside the forming cylinder. This pressure causes the moisture contained in the rice husks to become subcritical, and the subcritical moisture temporarily decomposes the cellulose, hemicellulose, lignin, and other components contained in the rice husks, which then solidify, resulting in a solid fuel with higher compressive strength.

[0017] The diameter of the forming cylinder is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 40 mm to 120 mm, more preferably 60 mm to 120 mm, even more preferably 70 mm to 100 mm, and particularly preferably 75 mm to 100 mm. With such a cylinder diameter, the impact heat and frictional heat generated in the pushing step are transmitted to the rice husks present in the center of the forming cylinder, where they can be decomposed, and the produced solid fuel tends to have high compressive strength.

[0018] Furthermore, the pushing length of the molding cylinder is preferably 150 mm or more and 200 mm or less, and more preferably 160 mm or more and 180 mm or less. If the pushing length is within this range, frictional heat and impact heat generated in the pushing step tend to be generated efficiently. If the pushing length is less than 150 mm, it is difficult to obtain the desired impact heat and frictional heat, and if it exceeds 200 mm, the load on the equipment may become too great and it may not be suitable for continuous production.

[0019] Typically, the pushing process is a process in which rice husks are pushed using a molding cylinder with a diameter of 40 mm or more and 75 mm or less, with a pushing length of 150 mm or more and 200 mm or less, and can be carried out by a pushing means.

[0020] The molding cylinder is not particularly limited in shape, material, etc., as long as it has a cylindrical shape, and can be appropriately selected depending on the purpose. The molding cylinder may have a partially tapered structure as required.

[0021] In addition, in the pushing process, it is preferable to drive the piston in the molding cylinder at a rotation speed of 300 rpm or more, and more preferably 300 rpm to 350 rpm. If the rotation speed is 300 rpm or more, impact heat and frictional heat can be efficiently generated when pushing the rice husks, and the moisture contained in the rice husks can be brought to a subcritical state. In other words, in the pushing process, not only pushing but also hitting the rice husks can be performed to generate impact heat, and the moisture can be more efficiently brought to a subcritical state. Here, the rotation speed of the piston means, for example, the rotation speed of the crank 50 shown in Figure 2.

[0022] In the pushing step, it is preferable to heat the molding cylinder. The heating means at this time is not particularly limited as long as it can heat the molding cylinder to a desired temperature or higher, and can be appropriately selected depending on the purpose. The heating temperature is preferably 120°C or higher and 200°C or lower. This temperature range can promote decomposition, which occurs when the moisture contained in the rice husks is brought into a subcritical state by impact heat and frictional heat. On the other hand, temperatures below 120°C tend to make it difficult to promote the subcritical state, resulting in a decrease in compressive strength, while temperatures above 200°C are undesirable because they can cause gasification of the rice husks. The heating temperature refers to the temperature of the outer skin of the forming cylinder.

[0023] <Crushing process and crushing means> Before the pushing step, it is preferable to carry out a step of crushing the rice husks so that the particle size of the rice husks is 2 mm or less, which can be carried out by a crushing means. By preliminarily setting the grain size of the rice husks to 2 mm or less, the rice husks can be compressed more densely in the subsequent ramming process, resulting in a solid fuel with higher compressive strength. In addition, poor decomposition of the rice husks can be suppressed, improving the strength. From the viewpoint of improving compressive strength, it is preferable to adjust the particle size to the above-mentioned range, but the method for producing a solid fuel of the present invention can be applied even if the rice husks are not crushed.

[0024] The crushing means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a cutter mill and a hammer mill.

[0025] <Drying process and drying means> Prior to the crushing step, it is preferable to carry out a step of drying the rice husks so that the moisture content of the rice husks is 10% by mass or less, more preferably 3% by mass or more and 10% by mass or less, and this can be carried out by a drying means. By keeping the moisture content of rice husks within the above range, an appropriate amount of water can be brought into a subcritical state, resulting in decomposition and high strength. If the moisture content is less than 3% by mass, the amount of water used may be insufficient to achieve the decomposition effect due to the subcritical state. If the moisture content exceeds 10% by mass, excess moisture may cause a decrease in compressive strength.

[0026] The drying means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include an electric heater. The drying temperature is not particularly limited and can be appropriately selected depending on the purpose, and can be, for example, 110° C. or higher and 200° C. or lower. The drying temperature refers to the surface temperature of the drying means.

[0027] (solid fuel) The solid fuel obtained by the above-described method for producing a solid fuel of the present invention has an apparent specific gravity of 1.25 or more and 1.40 or less, and a compressive strength of 50 MPa or more and 70 MPa or less. The solid fuel can be produced by the solid fuel production method and the solid fuel production apparatus of the present invention.

[0028] The method for measuring the apparent specific gravity is not particularly limited and can be appropriately selected depending on the purpose. For example, the apparent specific gravity can be measured using a liquid immersion method. Specifically, prepare a measuring cylinder filled with liquid and pour the solid fuel into the measuring cylinder. The calculation is performed based on the increased liquid volume and liquid specific gravity.

[0029] The method for measuring the compressive strength is not particularly limited and can be appropriately selected depending on the purpose. For example, the compressive strength can be measured using a compressive strength tester or a universal testing machine. Specifically, a metal jig for pressure is attached to a compression tester or a universal testing machine, and a load (N) is applied to the solid fuel to measure the maximum load (N) at which it collapses. The obtained results and the contact area (m 2 ) to obtain the compressive strength. [Explanation of symbols]

[0030] 10 Inlet 20 screws 30A Piston 30B molding cylinder 40 Outlet 50 crank 100 Solid fuel manufacturing equipment

Claims

1. A method for producing a solid fuel, comprising a step of pushing rice husks at a pressure of 100 MPa or more using a molding cylinder equipped with a piston.

2. 2. The method for producing a solid fuel according to claim 1, wherein the shoving step uses a molding cylinder having a diameter of 40 mm to 120 mm, and shoves the rice husks at a shoving length of 150 mm to 200 mm.

3. The method for producing a solid fuel according to claim 1 , wherein in the pushing step, the piston in the molding cylinder is driven at a rotation speed of 300 rpm or more.

4. The method for producing a solid fuel according to claim 1 or 2, wherein the molding cylinder is heated to 120°C or higher and 200°C or lower in the pushing step.

5. 3. The method for producing a solid fuel according to claim 1, further comprising, before the pushing step, a crushing step of crushing the rice husks so that the particle size of the rice husks is 2 mm or less.

6. The method for producing a solid fuel according to claim 5, further comprising, before the crushing step, a drying step of drying the rice husks so that the moisture content of the rice husks is 3% by mass or more and 10% by mass or less.

7. A solid fuel manufacturing device characterized by having a pushing means capable of pushing rice husks inside a molding cylinder at a pressure of 100 MPa or more.

8. 8. The solid fuel manufacturing apparatus according to claim 7, wherein the molding cylinder has a diameter of 40 mm to 120 mm and a pushing length of 150 mm to 200 mm.

9. 8. The solid fuel manufacturing apparatus according to claim 7, further comprising crushing means for crushing the rice husks to a particle size of 2 mm or less.

10. 10. The solid fuel production device according to claim 7, further comprising a drying means for drying the rice husks so that the moisture content of the rice husks is 10% by mass or less.

11. A solid fuel obtained by the method for producing a solid fuel according to any one of claims 1 and 2, A solid fuel characterized by an apparent specific gravity of 1.25 or more and 1.40 or less and a compressive strength of 50 MPa or more and 70 MPa or less.

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