Biomass gasification reactor
The compact biomass gasifier addresses inefficiencies in existing furnaces by integrating pyrolysis and gasification within a double-cylinder structure, enhancing fuel gas quality through external heating and internal combustion, and using modifiers to improve gas composition.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SINTOKOGIO LTD
- Filing Date
- 2022-09-16
- Publication Date
- 2026-06-30
Smart Images
Figure 0007882066000006 
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Figure 0007882066000002
Abstract
Description
Technical Field
[0001] The present invention relates to a biomass gasification furnace.
Background Art
[0002] Fuel gas generated from biomass raw materials is used as fuel for purposes such as power generation. The fuel gas is generated by heating and gasifying the biomass raw materials in a biomass gasification furnace.
[0003] As such a biomass gasification furnace, for example, Patent Document 1 discloses a configuration of a biomass gasification apparatus including a pyrolysis section of an externally heated rotary kiln type and a gasification section. The pyrolysis section indirectly heats and pyrolyzes the raw biomass to generate pyrolysis gas containing tar components and char. The gasification section introduces an oxidizing gas to the pyrolysis gas containing tar components and char extracted from the pyrolysis section to pyrolyze the tar components and gasify the char.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] In the configuration of Patent Document 1, when realizing the pyrolysis section and the gasification section, they are configured to be independent and individual devices, resulting in large-scale equipment. Further, in the gasification section of the configuration of Patent Document 1, since heat is not supplied from the outside, there is a possibility that the generation of fuel gas is not sufficiently promoted. Therefore, the efficiency of generating fuel gas is not high. If heat is to be supplied to the gasification section in the configuration of Patent Document 1, the equipment will become even larger. Furthermore, when no external heat is supplied to the gasification section, a larger amount of oxygen is required to decompose the tar components generated in the pyrolysis section. In biomass gasification plants, it is desirable for the fuel gas produced to contain a large amount of carbon monoxide (CO) and hydrogen (H2). However, if a large amount of oxygen is supplied, these carbon monoxide and hydrogen react with the excess oxygen (O2) to produce carbon dioxide (CO2) and water (H2O), which can reduce the amount of carbon monoxide and hydrogen in the fuel gas. Also, supplying a large amount of oxygen increases the oxygen concentration in the fuel gas, relatively decreasing the concentrations of carbon monoxide and hydrogen. For these reasons, the heat content per unit volume of the fuel gas may decrease, potentially degrading the quality of the fuel gas.
[0006] The objective of the present invention is to provide a biomass gasification furnace that can efficiently produce high-quality fuel gas and can be realized with a compact configuration. [Means for solving the problem]
[0007] To solve the above problems, the present invention employs the following means. In other words, the biomass gasifier of the present invention is a biomass gasifier that heats woody biomass raw material to gasify it and produce fuel gas, comprising: an outer cylinder provided with an axis extending in the vertical direction; an inner cylinder provided inside the outer cylinder with an axis extending in the vertical direction and its lower end located above the lower end of the outer cylinder; and a reaction furnace that heats the outer cylinder from the outside, wherein a combustion air supply unit is provided inside the inner cylinder, spaced apart from the lower end of the inner cylinder, to supply combustion air. Inside the inner cylinder, there is a deposit section in which the biomass raw material is accumulated up to a position above the portion where the combustion air supply section is provided, In the deposit section, the fuel gas is generated, and the generated fuel gas fills the space between the inner cylinder and the outer cylinder. The system further comprises a fuel gas modifier supply unit configured to supply, after being guided upward and then discharged, either or both of an oxidizer and a fuel gas reformer as modifiers to the space between the inner cylinder and the outer cylinder from top to bottom, the fuel gas modifier supply unit comprising a plurality of supply pipes extending from the top of the outer cylinder to the space between the inner cylinder and the outer cylinder. . [Effects of the Invention]
[0008] According to the present invention, it is possible to provide a biomass gasifier that can efficiently produce high-quality fuel gas and can be realized with a compact configuration. [Brief explanation of the drawing]
[0009] [Figure 1] This is a cross-sectional view showing the configuration of a biomass gasification furnace according to an embodiment of the present invention. [Modes for carrying out the invention]
[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows a cross-sectional view illustrating the configuration of a biomass gasification furnace according to an embodiment of the present invention. The biomass gasifier 1 heats woody biomass raw material F to gasify it and produce fuel gas G. The biomass gasifier 1 mainly consists of an outer cylinder 10, an inner cylinder 20, a reactor 30, a combustion air supply unit 40, a fuel gas regulator supply unit 50, and a control unit 80.
[0011] The outer cylinder 10 is provided such that its axis C extends in the vertical direction. The outer cylinder 10 integrally comprises a cylindrical tubular portion 11 extending vertically along the axis C, a top plate portion 12 that closes the upper end of the tubular portion 11, and a bottom plate portion 13 that closes the lower end of the tubular portion 11.
[0012] The inner cylinder 20 is provided at a distance from the outer cylinder 10, radially inward, around axis C. The inner cylinder 20 is formed in a cylindrical shape such that axis C extends in the vertical direction. As a result, the outer cylinder 10 and the inner cylinder 20 form a double-cylinder structure centered on the same axis C. Inside the inner cylinder 20, a cylindrical internal space S1 extending in the vertical direction is formed. The lower end 20b of the inner cylinder 20 is positioned above the lower end 10b of the outer cylinder 10. The upper part 20t of the inner cylinder 20 protrudes upward, penetrating the top plate portion 12 of the outer cylinder 10.
[0013] An opening 20h is formed at the upper end of the inner cylinder 20, opening upward. The opening 20h is the supply port for the biomass raw material F. The biomass gasifier 1 is equipped with a biomass raw material supply unit, such as a conveyor (not shown), above the opening 20h. The biomass raw material F is supplied by the biomass raw material supply unit from above the opening 20h into the internal space S1 inside the inner cylinder 20. The supplied biomass raw material F accumulates between the lower end 10b of the outer cylinder 10 and the lower end 20b of the inner cylinder 20, and inside the inner cylinder 20, forming an accumulation section 100.
[0014] A rotating tube 41 is provided inside the inner cylinder 20. The rotating tube 41 is provided so as to extend cylindrically in the vertical direction along the axis C, which is the same axis C as the outer cylinder 10 and the inner cylinder 20. The upper part 41t of the rotating tube 41 extends above the lower end 20b of the inner cylinder 20 and terminates inside the inner cylinder 20. The upper end of the rotating tube 41 is closed by a top plate portion 41f. The lower end portion 41b of the rotating tube 41 protrudes downward through the bottom plate portion 13 of the outer cylinder 10. The rotating tube 41 is rotated in the circumferential direction around axis C by a rotation mechanism (not shown) equipped with a motor or the like, which is provided below the bottom plate portion 13.
[0015] The combustion air supply unit 40 is formed in the upper part 41t of the rotating pipe 41. The combustion air supply unit 40 is located inside the inner cylinder 20. The combustion air supply unit 40 has a plurality of air circulation holes 42. The plurality of air circulation holes 42 are spaced apart above the lower end 20b of the inner cylinder 20. The plurality of air circulation holes 42 are formed in the portion above the lower end 20b of the inner cylinder 20 so as to penetrate the inside and outside of the rotating pipe 41. The plurality of air circulation holes 42 are located in the side wall 41s of the rotating pipe 41. Combustion air A is supplied into the rotating pipe 41 from the outside. The combustion air supply unit 40 supplies the combustion air A supplied into the rotating pipe 41 to the radially outer accumulation portion 100 centered on the axis C through the plurality of air circulation holes 42. By rotating the rotating pipe 41 in the circumferential direction around the axis C and blowing combustion air A from the combustion air supply unit 40, the combustion air A can be supplied evenly over the entire circumference of the accumulation unit 100. Here, it is preferable to use highly purified oxygen (pure oxygen) as the combustion air A. Although air can be used as combustion air A, the nitrogen contained in large quantities in the air is introduced into the biomass gasifier 1, and this nitrogen, which is not used in the various reactions described later, mixes with the generated fuel gas G, thereby diluting the fuel gas G. In contrast, by increasing the purity of the oxygen used in the various reactions as the combustion air A, the dilution of the fuel gas G can be suppressed.
[0016] Between the inner cylinder 20 and the outer cylinder 10, a circular space S is formed when viewed from above. This space S extends continuously in the vertical direction from the lower end 20b of the inner cylinder 20 to the top plate portion 12 of the outer cylinder 10. Below the lower end 20b of the inner cylinder 20, a circular bottom space S3 is formed inside the outer cylinder 10 when viewed from above. The bottom space S3 is formed below the internal space S1 and space S. The internal space S1 and space S are in communication with each other via the bottom space S3. In the internal space S1 of the inner cylinder 20, the fuel gas G generated from the deposit section 100 is drawn in by the fan 17, which will be described later, and guided towards the outer periphery via the bottom space S3, rising through the space S between the inner cylinder 20 and the outer cylinder 10.
[0017] The reactor 30 heats the outer cylinder 10 from the outside. The reactor 30 is formed so as to surround the cylindrical portion 11 of the outer cylinder 10 from the outside in the radial direction of the outer cylinder 10. The reactor 30 integrally has an outer peripheral wall portion 31, an upper wall portion 32, and a bottom wall portion 33. The outer peripheral wall portion 31 is provided at an interval with respect to the cylindrical portion 11 of the outer cylinder 10. The outer peripheral wall portion 31 is formed in a cylindrical shape extending in the vertical direction. The cross-sectional shape of the outer peripheral wall portion 31 when viewed from above may be any shape such as a circular shape, an elliptical shape, or a polygonal shape. The upper wall portion 32 is disposed below the upper end of the cylindrical portion 11 of the outer cylinder 10. The upper wall portion 32 closes the space between the upper end of the outer peripheral wall portion 31 and the cylindrical portion 11 of the outer cylinder 10 from above. The bottom wall portion 33 is disposed at substantially the same height as the bottom plate portion 13 of the outer cylinder 10. The bottom wall portion 33 closes the space between the lower end of the outer peripheral wall portion 31 and the cylindrical portion 11 of the outer cylinder 10 from below. The entire reactor 30 is configured to be covered with a heat insulating material not shown in the figure.
[0018] The reactor 30 further includes a fluid inlet 34 and a fluid outlet 35. The fluid inlet 34 is formed at the lower part of the reactor 30. The fluid inlet 34 is for sending the high-temperature fluid H supplied from the outside of the reactor 30 into the reactor 30. As the high-temperature fluid H, for example, a gas at 1000 °C or higher is used. The high-temperature fluid H sent into the reactor 30 from the fluid inlet 34 heats the outer cylinder 10 from the outside. The thermal energy of the high-temperature fluid H that heats the outer cylinder 10 is also propagated from the outer cylinder 10 to the inner cylinder 20 through the space S by radiation heat transfer or the like, and heats the inner cylinder 20 from the outside. The fluid outlet 35 is formed at the upper part of the reactor 30. The fluid outlet 35 is for discharging the high-temperature fluid H sent into the reactor 30 to the outside of the reactor 30. The surplus thermal energy of the high-temperature fluid H after being used for the reaction process and discharged from the fluid outlet 35 can be utilized, for example, by an appropriate boiler, heat exchanger, or the like.
[0019] The outer cylinder 10 further includes a fuel gas discharge portion 15 and a deposit discharge portion 16. The fuel gas discharge part 15 is formed above (upper part) of the outer cylinder 10 so that the space S between the inner cylinder 20 and the outer cylinder 10 communicates with the outside of the outer cylinder 10. The fuel gas discharge part 15 discharges the fuel gas G in the space S to the outside of the outer cylinder 10. A fan 17 is provided outside the fuel gas discharge part 15. The fan 17 is rotationally driven by a drive source (not shown) such as a motor. The fan 17 is provided so as to generate a negative pressure in the space S to suck the fuel gas G in the space S and guide it to the fuel gas discharge part 15. With such a configuration, the fuel gas G is discharged through the space S between the inner cylinder 20 and the outer cylinder 10. More specifically, the fuel gas G is discharged after being guided upward through the space S between the inner cylinder 20 and the outer cylinder 10. The fuel gas discharge part 15 is connected to an external duct (not shown). The fuel gas G discharged from the fuel gas discharge part 15 to the duct is dust-removed by a high-temperature filter and cooled to, for example, 40°C or lower by a gas cooler. The cooled fuel gas G is supplied to an appropriate downstream facility such as an internal combustion engine.
[0020] The sediment discharge part 16 is provided at the lower end 10b of the outer cylinder 10. The sediment discharge part 16 has a cylindrical shape extending obliquely downward from the bottom plate part 13 of the outer cylinder 10. The sediment discharge part 16 has an upper end opening 16h. The upper end opening 16h opens upward in the outer cylinder 10 at the bottom plate part 13. Through the sediment discharge part 16, the sediment T located at the lower end of the sedimentation part 100 is discharged to the outside of the outer cylinder 10 as the discharge Z.
[0021] The biomass gasifier 1 is equipped with a discharge promotion unit 18 at the lower end (bottom) of the outer cylinder 10. The discharge promotion unit 18 guides the sediment T located at the lower end (bottom) of the outer cylinder 10 to the sediment discharge unit 16 and promotes the discharge of the sediment T through the sediment discharge unit 16. This discharge promotion unit 18 has, for example, a swivel blade 19 joined to the outer circumferential surface of a rotating pipe 41. The swivel blade 19 extends radially outward from the outer circumferential surface of the rotating pipe 41 around the axis C. Multiple swivel blades 19 (for example, four) are arranged in the circumferential direction around the axis C. As will be explained later, the sediment T is carbonized and fluidized at the lower end of the sediment section 100. The swivel blade 19 rotates circumferentially around the axis C together with the rotating pipe 41, pushing the fluidized sediment T at the bottom of the outer cylinder 10 downward. The sediment T that is pushed downward is discharged to the outside of the outer cylinder 10 through the upper end opening 16h and the sediment discharge section 16.
[0022] The fuel gas regulator supply unit 50 supplies a regulator V into the space S between the inner cylinder 20 and the outer cylinder 10. The fuel gas regulator supply unit 50 is equipped with a plurality of supply pipes 51. The plurality of supply pipes 51 are arranged in the space S between the inner cylinder 20 and the outer cylinder 10 at intervals in the circumferential direction around the axis C. Each supply pipe 51 extends in the vertical direction, penetrating the top plate portion 12 of the outer cylinder 10 from top to bottom and extending into the space S. The regulator V is supplied to each supply pipe 51 from a regulator supply source (not shown) provided outside the outer cylinder 10. The regulator V supplied to each supply pipe 51 is ejected from the lower end of the supply pipe 51 into the space S between the inner cylinder 20 and the outer cylinder 10 from top to bottom. As the modifier V, for example, either an oxidizer or a fuel gas G reformer, or both, can be used. The oxidizer mainly promotes the oxidation of tar components contained in the fuel gas G in the space S. As the oxidizer, combustion air A similar to that supplied by the combustion air supply unit 40 may be used. The fuel gas G reformer increases the amount of carbon monoxide and hydrogen contained in the fuel gas G, thereby improving the quality of the fuel gas G. As the reformer, for example, superheated steam can be used.
[0023] The control unit 80 controls the operation of the biomass gasifier 1. The biomass gasifier 1 is equipped with a sensor 81. The sensor 81 detects the height of the accumulation section 100 inside the inner cylinder 20, that is, the position of the upper end of the accumulation section 100. Based on the height of the accumulation section 100 detected by the sensor 81, the control unit 80 controls the operation of the biomass raw material supply unit and the discharge promotion unit 18. If the height of the accumulation section 100 detected by the sensor 81 is below a predetermined height threshold located above the combustion air supply unit 40, the control unit 80 stops the discharge promotion unit 18 and supplies biomass raw material F from the biomass raw material supply unit. If the height of the accumulated material T detected by the sensor 81 exceeds the height threshold, the control unit 80 stops the supply of biomass raw material F from the biomass raw material supply unit and activates the discharge promotion unit 18.
[0024] In such a biomass gasifier 1, biomass raw material F is supplied from above the opening 20h. The biomass raw material F is, for example, woody material such as branches, leaves, and bark. Prior to being supplied to the biomass gasifier 1, the biomass raw material F is crushed into small pieces. The biomass raw material F can be of any size as long as it can be supplied from the opening 20h. If the biomass raw material F is granular, for example, a particle size of about 50 mm, which is commonly used for papermaking, may be used. However, the finer the biomass raw material F is, the larger the overall surface area, and therefore the higher the efficiency of fuel gas G production. For this reason, it is preferable that the biomass raw material F has a particle size distribution such that, for example, particles with a particle size of about 10 mm are the most numerous. Also, if it is a long, slender shape, so-called pin tip, it is preferable that the maximum length be about 50 mm.
[0025] The biomass raw material F supplied from the opening 20h into the internal space S1 inside the inner cylinder 20 accumulates in the bottom space S3 between the lower end 10b of the outer cylinder 10 and the lower end 20b of the inner cylinder 20, and in the internal space S1 of the inner cylinder 20, forming an accumulation section 100.
[0026] The deposit section 100 is formed by depositing material from the bottom plate portion 13 of the outer cylinder 10 up to a position above the upper end of the rotating pipe 41 of the combustion air supply section 40. The deposit section 100 is formed so that different reaction portions, a pyrolysis layer 101, an oxidation layer 102, and a reduction layer 103, are sequentially stacked from top to bottom. The deposit T located at the lower end of the deposit section 100 inside the outer cylinder 10 is guided to the deposit discharge section 16 by the discharge promotion section 18 and sequentially discharged to the outside of the outer cylinder 10. As a result, the deposit T forming the deposit section 100 sequentially descends (sediments) from top to bottom. Consequently, as the height of the deposit section 100 decreases, biomass raw material F is supplied from the biomass raw material supply section. In this way, the biomass raw material F supplied to the internal space S1 inside the inner cylinder 20 is discharged after sequentially passing through the pyrolysis layer 101, the oxidation layer 102, and the reduction layer 103.
[0027] The space S between the inner cylinder 20 and the outer cylinder 10, the internal space S1 inside the inner cylinder 20, and the bottom space S3 are heated by the heat of a high-temperature fluid H, for example, 1000°C or higher, supplied into the reactor 30. The pyrolysis layer 101 is the portion of the deposition section 100 above the combustion air supply section 40. In the pyrolysis layer 101, the biomass raw material F is heated to, for example, about 400°C by the heat of the high-temperature fluid H, and is pyrolyzed while being dried. The pyrolysis of the biomass raw material F produces carbon (C)-containing products, carbon monoxide (CO), hydrogen (H2), etc. Examples of carbon-containing products include methane (CH4) and ethane (C2H6). Furthermore, carbon-containing products include tar components, which are high-molecular-weight hydrocarbons. When cooled and liquefied, these tar components become viscous. Therefore, if the fuel gas G produced by the biomass gasifier 1 contains a large amount of tar components, the tar components may adhere to the mechanical drive components of downstream equipment that uses the fuel gas G, potentially causing malfunctions in those components. For this reason, it is desirable to have a small amount of tar components in the fuel gas G.
[0028] The oxide layer 102 is formed below the pyrolysis layer 101. The oxide layer 102 includes a portion in the vertical direction where the combustion air supply unit 40 is provided. In the oxide layer 102, combustion air A is supplied to the deposit 100 from multiple air circulation holes 42 of the combustion air supply unit 40. Various components produced by pyrolysis in the pyrolysis layer 101 pass through the oxide layer 102 as the deposit T settles from top to bottom through the oxide layer 102. In the oxide layer 102, carbon-containing products such as tar components among the various components undergo oxidation reactions with oxygen in the supplied combustion air A.
[0029] The carbon (C) contained in tar components undergoes oxidation reactions in the oxide layer 102, resulting in the chemical reactions shown in equations (1) and (2) below.
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number
[0030] Furthermore, in the oxidation layer 102, the oxidation reaction of hydrogen (H2) produced in the pyrolysis layer generates water vapor (H2O) as shown in equation (3) below, releasing 286 kJ of thermal energy.
number
[0031] The reducing layer 103 is formed below the oxidizing layer 102. The reducing layer 103 is formed in a portion below the combustion air supply section 40. In the reducing layer 103, carbon monoxide (CO) and hydrogen (H2), which are the main components of the fuel gas G, are produced by a gasification reaction. In the reducing layer 103, the carbon (C) component that was not reacted in the oxidizing layer 102 is reduced by the carbon dioxide produced in the oxidizing layer 102, as shown in equation (4) below, to produce flammable carbon monoxide (CO).
number
number
[0032] In this way, fuel gas G is produced as the biomass raw material F passes sequentially through the pyrolysis layer 101, the oxidation layer 102, and the reduction layer 103. The produced fuel gas G contains carbon monoxide (CO) obtained in the oxidation layer 102 according to equation (2) above, and carbon monoxide (CO) and hydrogen (H2) obtained in the reduction layer 103 according to equations (4) and (5) above. It is desirable for fuel gas G to contain a larger amount of these combustible carbon monoxide (CO) and hydrogen (H2).
[0033] The generated fuel gas G is sucked in by the fan 17 at the lower end of the deposit T in the deposit section 100, guided radially outward, and rises from bottom to top through the space S between the inner cylinder 20 and the outer cylinder 10. During this process, the fuel gas G undergoes reactions similar to the oxidation reaction in the oxidation layer 102, such as the decomposition of tar components, and similar to the reduction reaction in the reduction layer 103, such as the generation of carbon monoxide (CO) and hydrogen (H2). The fuel gas regulator V is supplied to the space S between the inner cylinder 20 and the outer cylinder 10 from multiple supply pipes 51 of the fuel gas regulator supply unit 50. The regulator V is ejected from the lower end of the supply pipes 51 into the space S between the inner cylinder 20 and the outer cylinder 10 from above, downwards. When an oxidizing agent is used as the modifier V, the tar components contained in the fuel gas G rising from bottom to top within the space S undergo oxidation reactions as shown in equations (1) and (2) above, and the decomposition of the tar components is promoted. Furthermore, when used as a modifier V, superheated steam (reformant), carbon monoxide and hydrogen are produced by the reaction shown in equation (5) above. This increases the amount of carbon monoxide and hydrogen contained in the fuel gas G, thereby improving the quality of the fuel gas G.
[0034] As the material passes through the pyrolysis layer 101, oxidation layer 102, and reduction layer 103 in sequence, and reactions appropriate to each layer occur, the sediment T located at the lower end of the sediment section 100 becomes carbonized and fluidized. The discharge promotion section 18 pushes the fluidized sediment T downward and discharges it to the outside of the outer cylinder 10 through the sediment discharge section 16. As a result, the entire sedimentation section 100 descends. By repeating this process, the supplied biomass raw material F moves sequentially through the pyrolysis layer 101, the oxidation layer 102, and the reduction layer 103. As the entire accumulation section 100 moves downward, the height of the accumulation section 100 decreases. Sensor 81 continuously detects the height of the accumulation section 100, and when the height of the accumulation section 100 falls below a predetermined height threshold, control unit 80 stops the discharge promotion unit 18 to stop the discharge of the accumulated material T, and supplies biomass raw material F from the biomass raw material supply unit until the height of the accumulation section 100 rises above the predetermined height threshold. When the height of the accumulation section 100 exceeds the predetermined height threshold, control unit 80 stops the supply of biomass raw material F from the biomass raw material supply unit, activates the discharge promotion unit 18, and discharges the accumulated material T.
[0035] The biomass gasifier 1 described above is a biomass gasifier 1 that heats and gasifies woody biomass raw material F to produce fuel gas G. The biomass gasifier 1 comprises an outer cylinder 10 with an axis C extending in the vertical direction, an inner cylinder 20 installed inside the outer cylinder 10 with an axis C extending in the vertical direction and its lower end 20b positioned above the lower end 10b of the outer cylinder 10, and a reactor 30 that heats the outer cylinder 10 from the outside. Inside the inner cylinder 20, spaced apart from the lower end 20b of the inner cylinder 20, is a combustion air supply unit 40 that supplies combustion air A. The biomass raw material F is supplied from above into the inner cylinder 20 so as to form a deposit section 100 that is accumulated from the lower end 10b of the outer cylinder 10 up to a position above the combustion air supply unit 40 inside the inner cylinder 20, and fuel gas G is produced in this deposit section 100. The generated fuel gas G is discharged through the space S between the inner cylinder 20 and the outer cylinder 10. In this type of biomass gasifier 1, the biomass raw material F is supplied from above to the inside of the inner cylinder 20. The supplied biomass raw material F accumulates from the lower end 10b of the outer cylinder 10 up to a position above the combustion air supply section 40 inside the inner cylinder 20, forming a deposit section 100. Here, sufficient heat is supplied to the deposit section 100 by a reactor 30 located outside the outer cylinder 10. As a result, in the part of the deposit section 100 above the combustion air supply section 40, where the biomass raw material F has been supplied for a short time, the biomass raw material F is thermally decomposed to produce carbon-containing products, carbon monoxide, and hydrogen. In the thermal decomposition, tar components are also produced as carbon-containing products. In the part below where the thermal decomposition takes place, where the combustion air supply section 40 is located, an oxidation reaction occurs due to the oxygen contained in the combustion air supplied from the combustion air supply section 40. This oxidation reaction decomposes carbon-containing products such as tar components produced in the thermal decomposition, producing carbon monoxide, carbon dioxide, water, etc. Then, in the portion below the combustion air supply section 40, a reduction reaction occurs in which the carbon dioxide and water generated as described above are reduced. This reduction reaction produces carbon monoxide and hydrogen, which are the main components of fuel gas G. The deposition section 100, where the above-described reaction proceeds, is mainly located inside the inner cylinder 20. The inner cylinder 20 is heated from the outside by the reactor 30, with the outer cylinder 10 in between. As a result, the efficiency of fuel gas G generation is increased in the deposition section 100 inside the inner cylinder 20. Furthermore, since the deposition section 100 is heated and the efficiency of the reaction is increased, the amount of oxygen required for the reaction is reduced. Therefore, the amount of combustion air A supplied from the combustion air supply section 40 can be reduced. As a result, carbon monoxide and hydrogen, which are the main components of the generated fuel gas G, are prevented from being lost due to excessive reaction with oxygen, and the deterioration of the quality of the fuel gas G can be suppressed. The generated fuel gas G then passes from the accumulation section 100 through the space between the lower end 20b of the inner cylinder 20 and the lower end 10b of the outer cylinder 10, and is discharged through the space S between the inner cylinder 20 and the outer cylinder 10. During this process, the fuel gas G is also heated by the reactor 30 located outside the outer cylinder 10. This promotes the decomposition of tar components and other substances in the fuel gas G, thereby improving the quality of the fuel gas G. The combined effects of these factors enable the efficient production of high-quality fuel gas G. Furthermore, it has a double-cylinder structure consisting of an inner cylinder 20 and an outer cylinder 10, and all of the various reactions necessary to produce fuel gas G are carried out inside the double-cylinder structure. For this reason, there is no particular need to install any additional equipment related to the production of fuel gas G outside the biomass gasifier 1, and the configuration of the biomass gasifier 1 can be made simple and compact. As a result, it becomes possible to provide a biomass gasifier 1 that can efficiently produce high-quality fuel gas G and can be realized in a compact configuration.
[0036] Generally, methods for generating fuel gas G by burning biomass raw materials F can be broadly classified into two types: partial combustion gasification and external heat gasification. The partial combustion gasification method involves placing biomass raw material F inside a container and burning a portion of the biomass raw material F to gasify it using the resulting heat. In the partial combustion gasification method, the amount of tar components in the fuel gas G is reduced, but because it utilizes the natural heat generated by the biomass raw material F, it requires biomass raw material F with controlled quality in terms of size and moisture content. The external heat gasification method is a method of gasifying biomass raw material F placed inside a container by applying heat from the outside. While the external heat gasification method can produce fuel gas G with a high calorific value per unit volume regardless of the quality of the biomass raw material F, it results in a higher concentration of tar components in the fuel gas G. Furthermore, the equipment used in the external heat gasification method tends to be larger. In contrast, the biomass gasifier 1 described in this embodiment is configured to have both the characteristics of a partial combustion gasification method, in which heat is applied to the biomass raw material F from the inside by heat from the combustion air supply unit 40, and the characteristics of an external heat gasification method, in which heat is applied to the biomass raw material F from the outside by heat from the reactor 30. As a result, as described above, it is possible to efficiently produce high-quality fuel gas G and realize it in a compact configuration.
[0037] Furthermore, the generated fuel gas G is guided upward through the space S between the inner cylinder 20 and the outer cylinder 10 before being discharged. In this configuration, when the fuel gas G is discharged to the outside, it is guided upward through the space S between the inner cylinder 20 and the outer cylinder 10. Therefore, even if foreign matter such as soot or dust is mixed in the fuel gas G, the foreign matter will naturally fall downward, making it easier to separate from the fuel gas G. This suppresses the mixing of foreign matter into the fuel gas G. Furthermore, since the fuel gas G is guided upward through the space S between the inner cylinder 20 and the outer cylinder 10, the fuel gas G is heated by the reactor 30 located outside the outer cylinder 10 during this process. As a result, the fuel gas G is heated for a longer period of time, promoting the decomposition of tar components and other substances in the fuel gas G, thereby improving the quality of the fuel gas G.
[0038] Furthermore, the biomass gasifier 1 is further equipped with a fuel gas regulator supply unit 50 that supplies either or both of the oxidizer and the fuel gas G reformer as a regulator V to the space S between the inner cylinder 20 and the outer cylinder 10 from above downwards. With this configuration, the fuel gas regulator supply unit 50 supplies the regulator V from above to below into the space S between the inner cylinder 20 and the outer cylinder 10. This prevents foreign matter contained in the fuel gas G, which is guided upward within the space S, from rising along with the fuel gas G. Therefore, the mixing of foreign matter into the fuel gas G can be suppressed more reliably. Furthermore, if the modifier is an oxidizing agent, it can promote the decomposition of tar components in the fuel gas G through oxidation. Also, if the modifier is a reforming agent, it can modify the fuel gas G and improve its quality.
[0039] Furthermore, the portion of the deposition section 100 above the combustion air supply section 40 is a pyrolysis layer 101 in which the biomass raw material F is pyrolyzed. The portion of the deposition section 100 where the combustion air supply section 40 is provided is an oxidation layer 102 in which the tar components produced by pyrolysis are decomposed by an oxidation reaction. The portion of the deposition section 100 below the combustion air supply section 40 is a reduction layer 103 in which carbon dioxide and water vapor produced in the pyrolysis layer 101 and the oxidation layer 102 are reduced to produce fuel gas G containing carbon monoxide and hydrogen. In this configuration, the biomass raw material F is thermally decomposed in the thermal decomposition layer 101 of the pile section 100. The tar components produced by the thermal decomposition of the biomass raw material F are decomposed by oxidation in the oxidation layer 102 below the thermal decomposition layer 101. Carbon dioxide and water vapor are generated in the thermal decomposition layer 101 and the oxidation layer 102. From the generated carbon dioxide and water vapor, carbon monoxide and hydrogen are produced by reduction reactions in the reduction layer 103 below the oxidation layer 102. This produces fuel gas G containing carbon monoxide and hydrogen.
[0040] Furthermore, the biomass gasifier 1 includes a sediment discharge section 16 provided at the lower end 10b of the outer cylinder 10 from which the sediment T located at the lower end of the sediment section 100 is discharged, and a discharge promotion section 18 provided at the lower end 10b of the outer cylinder 10 to guide the sediment T located at the lower end to the sediment discharge section 16 and promote discharge. With this configuration, the sediment T located at the lower end of the sediment section 100 is guided to the sediment discharge section 16 by the discharge promotion section 18. The guided sediment T is then discharged from the sediment discharge section 16 to the outside of the outer cylinder 10. This allows the sediment T in the sediment section 100 to settle sequentially downwards through thermal decomposition, oxidation, and reduction reactions.
[0041] Furthermore, the biomass gasifier 1 is equipped with a sensor 81 for detecting the height of the pile section 100. The biomass gasifier 1 is also equipped with a control unit 80 that stops the discharge promotion unit 18 when the height of the pile section 100 is below a height threshold located above the combustion air supply unit 40, and activates the discharge promotion unit 18 when the height of the pile section 100 exceeds the height threshold. With this configuration, if the height of the accumulation section 100 is below a height threshold, the discharge promotion section 18 is stopped, thereby preventing the discharge of the accumulated material T from the accumulated material discharge section 16 when the height of the accumulation section 100 is insufficient and there is a shortage of accumulated material T for the generation of fuel gas G.
[0042] In this way, the height of the depositional portion 100 is maintained, so that the pyrolysis layer 101, oxidation layer 102, and reduction layer 103 are constantly formed in the depositional portion 100, and the corresponding reactions can proceed continuously in each of these layers.
[0043] Furthermore, the biomass gasifier 1 includes a fuel gas discharge section 15 provided on the upper side of the outer cylinder 10 for discharging the fuel gas G that has been guided upward to the outside, and a fan 17 provided on the outside of the fuel gas discharge section 15 for guiding the fuel gas G towards the fuel gas discharge section 15. With this configuration, the fuel gas G guided upward within the outer cylinder 10 is discharged to the outside of the outer cylinder 10 by the fuel gas discharge section 15. The fan 17 guides the fuel gas G to the fuel gas discharge section 15, enabling efficient discharge of the fuel gas G to the outside.
[0044] Furthermore, the inner cylinder 20 is provided with a rotating pipe 41 that extends vertically in a cylindrical shape along the axis C and rotates circumferentially around the axis C, with the upper end of the rotating pipe 41 being closed, and the combustion air supply unit 40 is provided with a plurality of air circulation holes 42 formed in the side wall 41s of the rotating pipe 41 so as to communicate the inside and outside of the rotating pipe 41, and combustion air A is sent into the rotating pipe 41 from the outside and supplied to the accumulation unit 100 through the plurality of air circulation holes 42. With this configuration, multiple air circulation holes 42 are formed in the side wall 41s of the rotating pipe 41, which is provided to extend vertically in a cylindrical shape along the axis C and rotate circumferentially around the axis C. Combustion air A is supplied to the accumulation section 100 from the multiple air circulation holes 42, so that the combustion air A can be supplied evenly around the combustion air supply section 40.
[0045] Furthermore, multiple air circulation holes 42 are formed in the side wall 41s of the rotating pipe 41. If multiple air circulation holes 42 are provided in the top plate portion 41f that closes the upper end of the rotating pipe 41, and combustion air A is supplied upward from the rotating pipe 41, the flow of combustion air A may disturb the boundary between the pyrolysis layer 101 and the oxidation layer 102, potentially preventing sufficient reaction in each layer. In contrast, with the above configuration, since the multiple air circulation holes 42 are formed in the side wall 41s of the rotating tube 41, disturbance of the boundary between the pyrolysis layer 101 and the oxidation layer 102 is suppressed, and the reactions in each layer can be carried out stably. [Explanation of Symbols]
[0046] 1. Biomass gasification reactor 10 Outer cylinder 10b Bottom end 15 Fuel gas exhaust section 16 Sediment discharge section 17 Fans 18 Emission Promotion Department 20 Inner cylinder 20b bottom end 30 Reactors 40 Combustion air supply unit 50 Fuel gas regulator supply unit 80 Control Unit 81 Sensors 100 Deposition section 101 Pyrolysis layer 102 Oxide layer 103 Reduction layer A Combustion air C axis F Biomass raw materials G Fuel gas S space T deposit V Adjusting Agent
Claims
1. A biomass gasifier that heats woody biomass raw materials to gasify them and produce fuel gas, An outer cylinder provided so that its axis extends in the vertical direction, Inside the outer cylinder is an inner cylinder provided such that its axis extends vertically and its lower end is located above the lower end of the outer cylinder. A reaction furnace that heats the outer cylinder from the outside, Equipped with, A combustion air supply unit is provided inside the inner cylinder, spaced apart from the lower end of the inner cylinder, to supply combustion air. Inside the inner cylinder, there is a deposit section where the biomass raw material is deposited up to a position above the portion where the combustion air supply section is provided, and the fuel gas is generated in this deposit section. The generated fuel gas is guided upward through the space between the inner cylinder and the outer cylinder before being discharged. The space between the inner cylinder and the outer cylinder further comprises a fuel gas modifier supply unit configured to supply either or both of the oxidizer and the fuel gas reformer as modifiers from above downwards, The biomass gasification furnace comprises a fuel gas regulator supply unit which includes a plurality of supply pipes extending from the upper part of the outer cylinder into the space between the inner cylinder and the outer cylinder.
2. The portion of the deposit section above the combustion air supply section is a pyrolysis layer in which the biomass raw material is thermally decomposed. The portion of the deposition area where the combustion air supply unit is provided is an oxide layer in which tar components produced by thermal decomposition are decomposed by an oxidation reaction. The biomass gasification furnace according to claim 1, wherein the portion of the deposition section below the combustion air supply section is a reduction layer in which carbon dioxide and water vapor produced in the pyrolysis layer and the oxidation layer are reduced to produce the fuel gas containing carbon monoxide and hydrogen.
3. A sediment discharge section is provided at the lower end of the outer cylinder, from which sediment located at the lower end of the sediment section is discharged, The biomass gasification furnace according to claim 1 or 2, further comprising: an discharge promoting unit provided at the lower end of the outer cylinder for guiding the sediment located at the lower end to the sediment discharge unit and promoting discharge.
4. The system includes a sensor that detects the height of the accumulation area, The biomass gasifier according to claim 3, further comprising a control unit that stops the discharge promotion unit when the height of the accumulation section is below a height threshold located above the combustion air supply unit, and activates the discharge promotion unit when the height of the accumulation section exceeds the height threshold.
5. A fuel gas discharge section is provided on the upper side of the outer cylinder and discharges the fuel gas that has been guided upward to the outside, The biomass gasification furnace according to claim 1, further comprising: a fan provided on the outside of the fuel gas discharge section and provided to guide the fuel gas toward the fuel gas discharge section.