Gasification method and production method of semi-carbonized fuel material

Abstract

To provide a gasification method and a production method of a semi-carbonized fuel material capable of efficiently gasifying a semi-carbonized fuel material obtained by semi-carbonizing at least one of a wood-based material and a herbaceous material.SOLUTION: A gasification method comprises a semi-carbonization step of superheating a wood-based material and a herbaceous material with superheated steam V to produce a semi-carbonized fuel S, and a gasification step of gasifying the semi-carbonized fuel S by using a gasification system 2 that feeds the semi-carbonized fuel S from below and discharges a product gas G from above.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gasification method for gasifying torrefied fuel material obtained by torrefying at least one of wood-based material and herbaceous material, and a method for producing torrefied fuel material. [Background technology]

[0002] As environmental issues have been receiving increasing attention in recent years, research is underway into methods for efficiently obtaining gas as an energy source from naturally derived biomass fuels, instead of using fossil fuels such as oil and coal for power generation.

[0003] For example, Patent Document 1 discloses a so-called updraft type gasification apparatus as a gasification apparatus for gasifying biomass fuel, in which biomass fuel is introduced from above a reaction tower and gas generated from the biomass fuel inside the reaction tower is discharged from above.

[0004] However, in the gasification method using the gasification apparatus, when biomass fuel such as woody or herbaceous materials is used, there is a possibility that ash that is not completely gasified may accumulate inside the reaction tower, and the ash remaining inside the reaction tower may melt and form clinker, which may reduce the gasification efficiency inside the reaction tower. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-101215 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a gasification method and a method for producing torrefied fuel material that can efficiently gasify torrefied fuel material obtained by torrefying at least one of wood-based material and herbaceous material. [Means for solving the problem]

[0007] This invention is characterized by a gasification method that includes a torrefaction process in which at least one of wood-based material and herbaceous material is superheated with superheated steam to produce torrefied fuel material, and a gasification process in which the torrefied fuel material is input and gasified using a gasification device that releases gas. The present invention is also characterized by a method for producing torrefied fuel material, in which at least one of wood-based material and herbaceous material is superheated with superheated steam to torrefy it, thereby producing torrefied fuel material.

[0008] The wood-based materials are organic resources of biological origin consisting of wood, and include, for example, coniferous trees, broad-leaved trees, deciduous trees, fruit tree prunings, bamboo, fast-growing trees, and driftwood. The herbaceous materials are organic resources derived from non-tree-forming plants, and include, for example, sorghum, bamboo, coffee grounds, rice husks, weeds, reeds, and grasses.

[0009] The torrefied fuel material is woody or herbaceous material that has been torrefied by superheating it with superheated steam, or woody and herbaceous material that has been torrefied by superheating it with superheated steam. In other words, the torrefied fuel material is torrefied by superheating it with superheated steam, and does not include woody or herbaceous material that has been torrefied by superheating it with superheated steam, or the other woody or herbaceous material that has not been torrefied.

[0010] The semi-carbonized fuel material refers to fuel material made by heating at least one of wood-based material and herbaceous material with superheated steam at a predetermined temperature (approximately 250 to 350°C) in an oxygen-blocked state, resulting in a material with a high carbon content and reduced oxygen content. The gasification apparatus may be of the so-called updraft type or downdraft type, and the torrefied fuel material may be fed from below or above.

[0011] According to this invention, it is possible to efficiently gasify torrefied fuel material obtained by torrefying at least one of wood-based material and herbaceous material. Specifically, because the superheated steam penetrates at least one of the woody material and the herbaceous material, components that cause clinker formation, such as potassium contained in the woody material and the herbaceous material, can be hydrolyzed and released. As a result, in the torrefaction process, torrefied fuel material with high energy density can be obtained from which most of the potassium contained in the woody material and the herbaceous material has been removed. Therefore, in the gasification process, the ash and potassium remaining from the gasified torrefied fuel material can be prevented from forming clinker, allowing for stable and continuous gasification in the gasification device.

[0012] Furthermore, during the torrefaction process, minerals such as potassium contained in woody and herbaceous materials are hydrolyzed and released, producing porous torrefied fuel material. This increases the surface area of ​​the torrefied fuel material. This allows the torrefied fuel material to be efficiently pyrolyzed in the gasification device. Therefore, during the gasification process, the torrefied fuel material can be efficiently and stably gasified, and char, tar, and other materials can be easily pyrolyzed and gasified, increasing the gas yield.

[0013] Furthermore, by torrefying at least one of the woody material and the herbaceous material with superheated steam in the torrefaction step, the yield of gas obtained by pyrolysis can be increased, i.e., the gasification efficiency in the gasification apparatus can be improved.

[0014] In one aspect of the present invention, in the semi-carbonization step, at least one of the wood-based material and the herbaceous material may be superheated with the superheated steam at 300 degrees. According to the present invention, the yield of gas obtained by pyrolysis can be further increased, that is, the gasification efficiency in the gasification apparatus can be further improved.

[0015] In another aspect of the present invention, the gasification apparatus comprises a feeding mechanism that feeds the torrefied fuel material from below, and a reaction tower that gasifies the torrefied fuel material, the feeding mechanism comprising a tubular vertical transport path that transports the torrefied fuel material from the bottom of the reaction tower to the inside, the reaction tower having a discharge pipe at the top that discharges gas produced from the torrefied fuel material, the vertical transport path being erected in the up-down direction and comprising a tubular vertical transport pipe connected to an insertion hole at the bottom of the reaction tower, and a vertical screw blade that is attached to the vertical transport pipe, spirally formed in the vertical direction, and rotatable around an axis that runs along the vertical direction as a rotation axis, the vertical screw blade protruding above the vertical transport pipe and exposed above the bottom of the reaction tower so as to circulate the torrefied fuel material that has fallen to the bottom of the reaction tower without being gasified.

[0016] This invention allows to transport torrefied fuel material from the bottom to the top in the reaction tower, and torrefied fuel material that falls without being gasified at the upper end of the vertical screw blade can be transported again to the top of the reaction tower together with new torrefied fuel material that is added to the reaction tower.

[0017] This allows the torrefied fuel material that was not sufficiently gasified to be gasified together with new torrefied fuel material. In other words, the torrefied fuel material that was not gasified inside the reaction tower can be circulated and reused, allowing the torrefied fuel material to be gasified more efficiently and suppressing the generation of clinker.

[0018] Furthermore, the torrefied fuel material that has fallen to the bottom can be transported upward again by the vertical screw blades, so that the torrefied fuel material that has fallen from above and piled up can be broken down, thereby eliminating bridges that would otherwise form from piles of torrefied fuel material.

[0019] Furthermore, in the gasification process, the torrefied fuel material is fed from the lower side of the gasifier, opposite to the upper side where endothermic reactions can occur, which prevents the internal temperature of the gasifier from dropping, thereby stabilizing the internal temperature of the gasifier and enabling stable gasification of the torrefied fuel material.

[0020] In another aspect of the present invention, carbon dioxide may be introduced as a gasifying agent into the reaction tower in the gasification step. The introduction of carbon dioxide as a gasifying agent mentioned above includes a case where carbon dioxide prepared in advance is introduced into the reaction tower as a gasifying agent, a case where carbon dioxide generated inside the reaction tower is circulated and introduced into the reaction tower, and the like.

[0021] This invention efficiently promotes the gasification of torrefied fuel materials using carbon dioxide introduced as a gasifying agent, while preventing a decrease in the concentration of the gas produced. Furthermore, because the majority of minerals, such as potassium, are removed by superheated steam, the ash remaining from the gasified torrefied fuel materials can be burned at approximately 800°C. Therefore, the ash can be burned at a low temperature, and the melting of the ash and the generation of clinker can be more reliably prevented.

[0022] In another embodiment of the present invention, the carbon dioxide may be introduced from the bottom of the reaction tower. This invention makes it possible to efficiently supply carbon dioxide as a gasifying agent to the pyrolysis layer formed below the reaction tower, where the pyrolysis of the semi-carbonized fuel material progresses, thereby promoting the pyrolysis reaction more efficiently. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a gasification method and a method for manufacturing torrefied fuel material that can efficiently gasify torrefied fuel material obtained by torrefying at least one of wood-based material and herbaceous material. [Brief explanation of the drawings]

[0024] [Figure 1] Schematic diagram of torrefaction equipment. [Figure 2] Schematic diagram of a gasification device. [Figure 3] 1 is a graph showing the change in gas yield over time when torrefied fuel material is gasified in a gasification device. [Figure 4] Schematic diagram of an electric heater tubular pyrolysis gasification furnace. [Figure 5] Graph showing the change in mass of torrefied fuel material versus temperature inside the quartz tube. [Figure 6] 1 is a graph showing the yield of gas produced by pyrolysis versus the temperature inside the quartz tube. [Figure 7] Graph showing the mass change of various torrefied fuel materials versus the temperature inside the quartz tube. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention relates to a gasification method in which a biomaterial O is torrefied using a torrefaction system 1 to produce torrefied fuel S, which is then gasified using a gasification system 2. One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic diagram of the torrefaction system 1, FIG. 2 shows a schematic diagram of the gasification system 2, and FIG. 3 shows a correlation diagram of the amount of produced gas G versus time when torrefied fuel S torrefied in the torrefaction system 1 is gasified in the gasification system 2. FIG. 4 shows a schematic diagram of the electric heater tubular pyrolysis gasifier 40. FIG. 5 is a graph showing the change in mass of torrefied fuel S versus the change in the internal temperature of the quartz tube 41. FIG. 6 is a graph showing the change in the yield of lab-produced gas Gr generated by pyrolysis versus the change in the internal temperature of the quartz tube 41. FIG. 7 is a graph showing the change in mass of various torrefied fuels S versus the change in the internal temperature of the quartz tube 41.

[0026] The torrefaction system 1 is an apparatus for producing torrefied fuel S from bio-raw material O, and is composed of a storage tank 11 for storing the bio-raw material O, a drying rotary kiln 12 for drying the bio-raw material O, a torrefaction rotary kiln 13 for torrefying the dried bio-raw material O, a superheated steam generator 14 for producing superheated steam V to be introduced into the torrefaction rotary kiln 13, and a cooling conveying section 15 for cooling the torrefied fuel S produced in the torrefaction rotary kiln 13.

[0027] The storage tank 11 is a container for storing bio-raw material O made from finely cut two-year-old bamboo, and has an outlet at the bottom for transporting the bio-raw material O to the drying rotary kiln 12. The storage tank 11 is configured to be controllable so that the stored bio-raw material O can be supplied to the drying rotary kiln 12 in an appropriate amount.

[0028] Here, the bio-raw material O is two-year-old bamboo, but it is not limited to that age and may be, for example, bamboo that is five years or older. Furthermore, instead of bamboo, the bio-raw material O may be herbaceous materials such as sorghum, coffee grounds, rice husks, weeds, reeds, and grasses, which are organic resources derived from plants that do not grow into trees. Furthermore, the bio-raw material O may be, in addition to herbaceous materials, organic resources derived from living organisms, such as wood, including wood-based materials such as coniferous trees, broad-leaved trees, deciduous trees, fruit tree prunings, fast-growing trees, and driftwood.

[0029] The drying rotary kiln 12 is a heating furnace for drying the biomaterial O transported from the storage tank 11. Specifically, the drying rotary kiln 12 is a hollow cylinder equipped with a heater 121 capable of adjusting the internal temperature. It has an inlet on the upstream side for introducing the biomaterial O discharged from the storage tank 11 and an outlet on the downstream side for discharging the biomaterial O. The drying rotary kiln 12 also contains a drying screw feeder 122 that transports the biomaterial O introduced from the inlet to the outlet while stirring it. The drying rotary kiln 12 thus configured is configured to supply superheated steam V for heating the torrefaction rotary kiln 13, and is configured so that the internal temperature can be adjusted by the supplied superheated steam V.

[0030] The torrefaction rotary kiln 13 is a heating furnace for torrefying the biomaterial O dried in the drying rotary kiln 12, and is connected downstream of the drying rotary kiln 12. More specifically, the torrefaction rotary kiln 13 is a hollow cylinder, similar to the drying rotary kiln 12, and has an inlet on the upstream side for introducing the biomaterial O dried in the drying rotary kiln 12, and an outlet on the downstream side for discharging the torrefied fuel S produced by torrefying the biomaterial O. The torrefaction rotary kiln 13 also contains a torrefaction screw feeder 131 that transports the biomaterial O introduced from the upstream inlet to the outlet while torrefying it.

[0031] In addition, the semi-carbonization rotary kiln 13 configured in this manner has a supply port 132 at the downstream end for supplying superheated steam V, and an electric heater 133 for adjusting the internal temperature is provided along the longitudinal direction of the semi-carbonization rotary kiln 13.

[0032] The superheated steam generator 14 is a device that produces superheated steam V to be supplied from the supply port 132 into the interior of the torrefaction rotary kiln 13. The superheated steam generator 14 can produce superheated steam V at 250°C to 700°C, and can supply an appropriate amount of superheated steam V to the torrefaction rotary kiln 13 in accordance with the internal temperature of the torrefaction rotary kiln 13. The superheated steam generator 14 is also configured to be able to appropriately adjust the amount of superheated steam supplied to the torrefaction rotary kiln 13 in accordance with, for example, the color, weight, and other conditions of the biomaterial O to be torrefied inside the torrefaction rotary kiln 13.

[0033] The cooling conveying section 15 is a hollow container for cooling the torrefied fuel S produced in the torrefaction rotary kiln 13, and has an inlet on the upstream side for feeding the torrefied fuel S produced in the torrefaction rotary kiln 13, and an outlet on the downstream side for discharging the cooled torrefied fuel S. In addition, a screw feeder is provided inside the cooling conveying section 15 for transporting the torrefied fuel S fed from the inlet to the outlet on the downstream side.

[0034] 2, the gasification system 2 is an apparatus in which the torrefied fuel S produced in the torrefaction system 1 is introduced from the bottom upward into a reaction tower 21, which is a substantially cylindrical vertical container, and the torrefied fuel S is gasified in the reaction tower 21. The generated gas G (carbon monoxide, hydrogen, etc.) generated by this gasification is sent from a discharge pipe 22 provided above the reaction tower 21. The sent generated gas G is used, for example, as fuel for power generation in a power generation device not shown.

[0035] The structure of the gasification system 2 and gasification of the torrefied fuel S using the gasification system 2 will be described below. As shown in Figure 2, the gasification system 2 is composed of a gasification device 20 that gasifies the torrefied fuel S, and a transport device 30 that transports the torrefied fuel S, which is the raw material for gasification, to the gasification device 20.

[0036] The gasification device 20 is of the so-called updraft type, in which the semi-carbonized fuel S is gasified by pyrolysis, combustion, and reduction, and the generated gas G is collected from above. Such a gasification apparatus 20 includes a reaction tower 21 that gasifies the torrefied fuel S, and a discharge pipe 22 that discharges the product gas G generated in the reaction tower 21. A gasifying agent supply port 23 that supplies a gasifying agent H is provided at the bottom of the reaction tower 21. Further, inside the reaction tower 21, a reaction tower heater 24 that increases the internal temperature of the reaction tower 21, a temperature sensor 25 that detects the internal temperature of the reaction tower 21, and a storage amount detection sensor 26 that detects the amount of torrefied fuel S stored inside the reaction tower 21 are provided. Further, outside the reaction tower 21, a gasifying agent supply unit 27 that supplies the gasifying agent H to the reaction tower 21 is provided.

[0037] The reaction tower 21 is a substantially cylindrical vertical vessel, and its bottom portion is configured as a cone-shaped vessel tapering downward. An insertion hole is provided at the apex of this cone for connection to a vertical transfer pipe 331, which will be described later. In addition, an ash discharge section (not shown) is provided at the bottom of the reaction tower 21 for scraping out residue and ash that remain when the torrefied fuel S is not completely gasified.

[0038] The temperature inside the reaction tower 21 can be increased by using the reaction tower heater 24. The reaction tower 21, which has been heated using the reaction tower heater 24, has multiple reaction zones T for gasifying the torrefied fuel S. More specifically, the reaction tower 21 has three reaction zones T formed in this order from bottom to top: a pyrolysis zone T1 for pyrolyzing the torrefied fuel S, a combustion zone T2 for causing a combustion reaction of the gas produced in the pyrolysis zone T1, and a reduction zone T3 for causing a reduction reaction of the gas produced in the pyrolysis zone T1 and the combustion zone T2 (see FIG. 2).

[0039] The discharge pipe 22 is a pipe for discharging the product gas G generated inside the reaction tower 21 to the outside, and is provided at the top of the reaction tower 21. A cyclone (not shown) for removing foreign matter from the generated gas G is connected to the tip of the discharge pipe 22. A part of the discharge pipe 22 is branched off, and a gas analyzer (not shown) for analyzing the components of the generated gas G is attached. If the generated gas G does not have the desired component ratio, the generated gas G is discharged without being sent downstream.

[0040] The gasifying agent supply port 23 is an opening for supplying the gasifying agent H from the outside into the reaction tower 21, and is provided at the bottom of the reaction tower 21 as shown in FIG. The reaction tower heater 24 is a heating device for increasing the temperature inside the reaction tower 21. It may also be used to increase the internal temperature of the reaction tower 21 when the product gas G is being generated, based on the temperature detection result by the temperature sensor 25.

[0041] The temperature sensor 25 detects the internal temperature of the reaction tower 21. Based on the set temperature inside the reaction tower 21 and the temperature change inside the reaction tower 21 detected by the temperature sensor 25, the reaction tower heater 24 can be controlled to adjust the internal temperature of the reaction tower 21 to a temperature suitable for gasifying the torrefied fuel S.

[0042] The storage amount detection sensor 26 detects the amount of torrefied fuel S accumulated inside the reaction tower 21. Specifically, it detects whether the accumulated torrefied fuel S inside the reaction tower 21 is lower or higher than a desired height, specifically, a height corresponding to the combustion zone T2 in the reaction tower 21.

[0043] The gasifying agent supply unit 27 is a supply unit that stores carbon dioxide and supplies the carbon dioxide to the reaction tower 21 as a gasifying agent H. The gasifying agent supply unit 27 is provided with a gasifying agent supply pipe 271 that is connected to a gasifying agent supply port 23 provided at the bottom of the reaction tower 21, and carbon dioxide is supplied to the reaction tower 21 as a gasifying agent H through the gasifying agent supply pipe 271. The gasifying agent supply unit 27 is configured to be able to adjust the supply amount of the gasifying agent H.

[0044] The conveying device 30 is composed of a surge tank 31 that stores the torrefied fuel S to be transported to the gasification device 20, an upstream conveying path 32 that transports the torrefied fuel S from the surge tank 31 to the gasification device 20, and a vertical conveying path 33 that transports the torrefied fuel S to the reaction tower 21.

[0045] The surge tank 31 is composed of a surge tank main body 311 for storing torrefied fuel S, a supply pipe 312 connected to the lower end of the surge tank main body 311, and a rotary valve 313 installed between the surge tank main body 311 and the supply pipe 312 (see Figure 2).

[0046] The supply pipe 312 is a tubular transport path, one end of which is connected via a rotary valve 313 to a fuel inlet provided at the lower end of the tapered surge tank main body 311, and the other end of which is connected to the upstream transport path 32.

[0047] As shown in Figure 2, the upstream conveying path 32 is composed of a tubular upstream conveying pipe 321, an upstream screw blade 322 installed inside the upstream conveying pipe 321, and an upstream rotary motor 323 that rotates and drives the upstream screw blade 322.

[0048] The upstream conveying pipe 321 is a tubular body that is erected in the vertical direction and has a curved tip that faces the reaction tower 21. An inlet that connects to the tip of the supply pipe 312 is provided on the side of the upstream conveying pipe 321, and the torrefied fuel S is fed from the supply pipe 312. The tip of the upstream conveying pipe 321 is connected to a vertical conveying pipe 331 that constitutes the vertical conveying path 33, and the torrefied fuel S can be fed to the tip side. An upstream rotary motor 323 that rotates the upstream screw blade 322 is provided at the upper end of the upstream conveying pipe 321.

[0049] The upstream screw blade 322 is a blade used in a so-called spring conveyor that is formed in a spiral shape and can rotate while bending, and extends along the upstream conveying pipe 321 from the upper end to the center of the upstream conveying pipe 321.

[0050] The vertical conveying path 33 is composed of a tubular vertical conveying pipe 331, a vertical screw blade 332 installed inside the vertical conveying pipe 331, and a downstream rotary motor 333 that drives the vertical screw blade 332 to rotate. The vertical transport pipe 331 is a tubular body that stands upright in the vertical direction, and is disposed below the reaction tower 21. The vertical transport pipe 331 is connected to the side of the central part thereof so as to be perpendicular to the tip of the upstream transport pipe 321.

[0051] The vertical screw blade 332 installed inside the vertical conveying pipe 331 is a so-called screw feeder that is formed in a spiral shape along the vertical direction and rotates around an axis that also extends along the vertical direction. The lower end of this vertical screw blade 332 is connected to a downstream rotation motor 333 provided at the lower end of the vertical conveying pipe 331, and can rotate freely inside the vertical conveying pipe 331.

[0052] The vertical conveying path 33 configured in this manner is arranged below the reaction tower 21, and the upper end of the vertical conveying pipe 331 is connected to the insertion hole of the reaction tower 21, so that the torrefied fuel S stored in the surge tank 31 can be conveyed into the reaction tower 21. The upper end of the vertical screw blade 332 installed inside the vertical conveying pipe 331 is exposed so as to protrude upward from the bottom of the reaction tower 21.

[0053] The torrefaction system 1 and gasification system 2 configured in this manner can torrefy the bio-raw material O to produce torrefied fuel S and efficiently generate generated gas G from the torrefied fuel S. Below, we will explain the torrefaction process in which the torrefaction system 1 produces torrefied fuel S, and the gasification process in which the gasification system 2 produces generated gas G from the torrefied fuel S.

[0054] First, two-year-old bamboo harvested from a bamboo forest is cut and processed into cutting chips. The resulting bio-raw material O is then placed in a storage tank 11 for storage, and the temperature inside the torrefaction rotary kiln 13 is increased by an electric heater 133. In addition, superheated steam V generated by a superheated steam generator 14 is supplied to the torrefaction rotary kiln 13. This allows the internal temperature of the torrefaction rotary kiln 13 to be adjusted within the range of 250 to 400°C.

[0055] Furthermore, the heater 121 raises the temperature inside the drying rotary kiln 12, and the superheated steam V supplied to the torrefaction rotary kiln 13 is supplied to the drying rotary kiln 12 via the torrefaction rotary kiln 13. This allows the internal temperature of the drying rotary kiln 12 to be adjusted within the range of 150 to 250°C.

[0056] Next, the biomaterial O stored in the storage tank 11 is transported to the drying rotary kiln 12. Specifically, the biomaterial O is introduced from the outlet of the storage tank 11 to the inlet of the drying rotary kiln 12. The biomaterial O introduced into the drying rotary kiln 12 is transported from the inlet to the outlet of the drying rotary kiln 12 as the drying screw feeder 122 rotates. As a result, the biomaterial O transported downstream inside the drying rotary kiln 12 is dried while passing through the drying rotary kiln 12, whose internal temperature is set to 200°C. The amount of biomaterial O transported to the outlet of the drying rotary kiln 12 can be adjusted by adjusting the rotation speed of the drying screw feeder 122. That is, the drying time of the biomaterial O can be adjusted by adjusting the rotation speed of the drying screw feeder 122.

[0057] The biomaterial O dried in the drying rotary kiln 12 is fed into the torrefaction rotary kiln 13 through an inlet provided in the torrefaction rotary kiln 13. Here, superheated steam V from the superheated steam generator 14 is supplied into the torrefaction rotary kiln 13 through a supply inlet 132, and the internal temperature is adjusted to 300°C or 350°C.

[0058] Therefore, the bio-raw material O dried in the drying rotary kiln 12 passes through the inside of the torrefaction rotary kiln 13 along the torrefaction screw feeder 131. This allows the superheated steam V supplied from the downstream side to the upstream side to come into uniform contact with the bio-raw material O moving from the upstream side to the downstream side.

[0059] Therefore, the biomaterial O is heated with superheated steam V at a predetermined temperature (300°C or 350°C) in an oxygen-blocked state, and becomes torrefied fuel S with a high carbon content and reduced oxygen content. The amount of superheated steam V supplied from the supply port 132 and the electric heater 133 are controlled so that the weight of the torrefied fuel S is 60 to 80% of the weight of the biomaterial O.

[0060] The torrefied fuel S, which is produced by torrefying the biomaterial O with the superheated steam V in this way, is cooled while being transported inside the cooling transport section 15 and is discharged from the outlet of the cooling transport section 15. The torrefied fuel S produced in this way by the torrefaction system 1 is then crushed to a predetermined size and stored in the surge tank 31.

[0061] Next, a gasification method in the gasification system 2 will be described. First, the internal temperature of the reaction tower 21 is raised to a desired temperature (800°C), and then the upstream screw blade 322 installed in the upstream transfer pipe 321 and the upstream rotary motor 323 installed in the vertical transfer pipe 331 are rotated. As a result, the torrefied fuel S introduced from the surge tank main body 311 into the upstream transfer pipe 321 is introduced into the reaction tower 21 from the bottom thereof while being pulverized inside the upstream transfer pipe 321 and the vertical transfer pipe 331.

[0062] In this way, the torrefied fuel S introduced into the reaction tower 21 from the transport device 30 is gasified inside the heated reaction tower 21. More specifically, by introducing the torrefied fuel S from the bottom of the reaction tower 21 in a state in which the gasifying agent H is introduced from the gasifying agent supply unit 27 through the gasifying agent supply port 23, a pyrolysis reaction occurs in the pyrolysis zone T1 and a combustion reaction occurs in the combustion zone T2. Furthermore, a reduction reaction occurs in the reduction zone T3, and a high-temperature product gas G containing carbon monoxide, carbon dioxide, hydrogen, methane, and other lower hydrocarbons as main components is produced from the torrefied fuel S (see FIG. 2).

[0063] The product gas G generated inside the reaction tower 21 is sent downstream through a discharge pipe 22 provided above the reaction tower 21 (see FIG. 2). The product gas G sent from the discharge pipe 22 is analyzed for its components by a gas analyzer provided in the discharge pipe 22, and when the product gas G does not have the desired components, such as at the beginning of the reaction, it is discharged to the outside.

[0064] In this way, the yield of the generated gas G obtained by gasifying the torrefied fuel S in the gasification apparatus 20 was measured against the operating time of the gasification system 2. Figure 3 is a graph showing the yield of the generated gas G obtained from the torrefied fuel S against the operating time of the gasification system 2.

[0065] The samples for which the yield of the generated gas G was measured were torrefied fuel S (referred to as the first torrefied fuel Sa) torrefied at 300°C using the torrefaction system 1, torrefied fuel S (referred to as the second torrefied fuel Sb) torrefied at 350°C using the torrefaction system 1, and torrefied fuel S (referred to as the third torrefied fuel Sx) obtained by introducing the second torrefied fuel Sb into the reaction tower 21 without using the conveying device 30.

[0066] As described above, the first torrefied fuel Sa and the second torrefied fuel Sb are charged into the reaction tower 21 from the bottom of the reaction tower 21 while being pulverized inside the upstream conveying pipe 321 and the vertical conveying pipe 331. From the first torrefied fuel Sa and the second torrefied fuel Sb charged into the reaction tower 21 while being pulverized in this manner, a generated gas G is generated in approximately proportion to each other immediately after the start, as shown in FIG.

[0067] On the other hand, the third semi-carbonized fuel Sx, which is introduced into the reaction tower 21 without using the transport device 30, i.e., introduced into the reaction tower 21 without being pulverized, can generate the generated gas G at the same rate as the first semi-carbonized fuel Sa, etc., immediately after the start of the reaction. However, after about 50 minutes have passed, the amount of generated gas G only increases slowly.

[0068] Furthermore, the first semi-carbonized fuel Sa, which was semi-carbonized at 300°C using superheated steam V, produced a larger amount of generated gas G than the second semi-carbonized fuel Sb, which was semi-carbonized at 350°C using superheated steam V, and was therefore gasified more efficiently (see Figure 3). The yield of generated gas G from the first semi-carbonized fuel Sa was also the best, more than 1.8 times that of the second semi-carbonized fuel Sb.

[0069] In this experiment, the bio-raw material O was torrefied using non-superheated steam and the torrefied material was gasified in the gasification system 2, but the generated gas G was not obtained in a measurable amount. This shows that the torrefied fuel S torrefied with superheated steam V can continuously and stably generate the generated gas G compared to torrefied material torrefied with non-superheated steam. It is also clear that the torrefied fuel S can be gasified more efficiently by feeding it into the reaction tower 21 while pulverizing it.

[0070] In this way, the torrefied fuel S produced by torrefying the bio-raw material O with superheated steam V has the superheated steam V permeating the bio-raw material O, causing most of the minerals, such as potassium, to be hydrolyzed and leaked out. As a result, the torrefied fuel S is porous, increasing its surface area. Therefore, it can be efficiently pyrolyzed in the gasification system 2, and it is believed that the torrefied fuel S can be stably gasified.

[0071] Furthermore, when the torrefied fuel S is gasified in the gasification system 2, components that cause clinker, such as potassium, are hydrolyzed and most of them leak out, so it is possible to prevent clinker from being generated from the ash and potassium that are residues of the gasified torrefied fuel S. This allows the generated gas G to convect inside the reaction tower 21, which allows the torrefied fuel S to be gasified more stably, and also prevents a decrease in the internal temperature of the reaction tower 21.

[0072] Furthermore, since the torrefied fuel S can be stably gasified in the gasification system 2, the generation of char, tar, etc. can be suppressed, and the frequency of replacing the filter installed downstream of the gasification device 20 can be reduced. Therefore, gasification can be carried out continuously using the gasification device 20, and productivity can be improved.

[0073] Below, we will explain using the results of laboratory tests that show that generated gas G can be stably produced from torrefied fuel S. The laboratory experiment was carried out using an electric heater tubular pyrolysis gasifier 40, as shown in Figure 4. The electric heater tubular pyrolysis gasifier 40 is composed of a hollow quartz tube 41, an electric heating unit 42 that adjusts the internal temperature of the quartz tube 41, a laboratory gasifying agent supply unit 43 that supplies carbon dioxide into the quartz tube 41, and a gas pack 44 that collects the gas generated in the quartz tube 41.

[0074] The quartz tube 41 is a tubular body made of quartz and is configured to accommodate approximately 100 mg of torrefied material to be pyrolyzed inside. A weighing scale (not shown) for measuring the mass of the torrefied material accommodated inside the quartz tube 41 is also provided inside the quartz tube 41. One end of the quartz tube 41 is connected to a tube connected to a laboratory gasifying agent supply unit 43, and the other end of the quartz tube 41 is connected to a tube that sends gas generated inside the quartz tube 41 to a gas pack 44. The electric heating unit 42 is an electric heater for raising the temperature of the quartz tube 41 from the outside of the quartz tube 41, and is controlled so that the temperature inside the quartz tube 41 can be raised at 400° C. / hour.

[0075] The laboratory gasifying agent supply unit 43 is a cylinder filled with carbon dioxide, which is introduced as a gasifying agent into the quartz tube 41. The flow rate of carbon dioxide introduced from the laboratory gasifying agent supply unit 43 into the quartz tube 41 is controlled to be constant.

[0076] A method for generating lab-produced gas Gr from torrefied material such as torrefied fuel S using the electric heater tubular pyrolysis gasification furnace 40 configured as described above will now be described in detail. First, the semi-carbonized material was pulverized to particles of 100 μm or less using a Wonder Blender pulverizer, and 100 mg±10 mg of the pulverized material was filled into a quartz tube 41. The quartz tube 41 was connected to a laboratory gasifying agent supply unit 43 filled with carbon dioxide to be introduced into the quartz tube 41, and the flow rate of the carbon dioxide to be introduced into the quartz tube 41 was set.

[0077] Next, the electric heating unit 42 is controlled to raise the temperature inside the quartz tube 41. The temperature raising rate of the quartz tube 41 is set to about 400°C / hour. By raising the internal temperature of the quartz tube 41 in this manner, the torrefied material is thermally decomposed in the quartz tube 41, and lab-produced gas Gr is generated. The lab-produced gas Gr generated in the quartz tube 41 is air-cooled in the furnace core tube and tube (not shown), and is collected as fly ash components in a strainer (not shown), and then collected in a gas pack 44.

[0078] Using the above-mentioned method, the change in mass of the torrefied material contained in the quartz tube 41 with respect to temperature change and the yield of the lab-produced gas Gr collected in the gas pack 44 with respect to temperature change were investigated (see Figures 5 and 6). The change in mass of the torrefied material and the yield of the lab-produced gas Gr were measured up to 800°C at intervals of 50°C when the internal temperature of the quartz tube 41 was changed.

[0079] The samples used in the above experiment were the first torrefied fuel Sa, which was obtained by torrefying bio-based feedstock O at 300°C using torrefaction system 1, the second torrefied fuel Sb, which was obtained by torrefying bio-based feedstock O at 350°C using torrefaction system 1, and the fourth torrefied fuel Sy, which was obtained by torrefying bio-based feedstock O using non-superheated steam. Note that for the fourth torrefied fuel Sy, there was variability in the mass change and the yield of lab-produced gas Gr, so multiple data points are shown in Figure 5.

[0080] As shown in Fig. 5, the first semi-carbonized fuel Sa, the second semi-carbonized fuel Sb, and the fourth semi-carbonized fuel Sy gradually decrease in mass between 0°C and 300°C, and then rapidly decrease in mass between 300°C and 400°C. Then, the mass gradually decreases between 400°C and 800°C. That is, the mass decrease curves of the first semi-carbonized fuel Sa, the second semi-carbonized fuel Sb, and the fourth semi-carbonized fuel Sy contained in the quartz tube 41 versus the internal temperature of the quartz tube 41 become inverted S-shaped as the temperature increases.

[0081] Furthermore, the masses of the first semi-carbonized fuel Sa and the second semi-carbonized fuel Sb decrease to approximately 30% of their original mass at 400°C, whereas the mass of the fourth semi-carbonized fuel Sy remains at approximately 70% of its original mass at 400°C (see Figure 5). Note that the masses of the first semi-carbonized fuel Sa and the second semi-carbonized fuel Sb are approximately the same at 400°C, whereas the mass of the fourth semi-carbonized fuel Sy at 400°C varies between 60 and 85% of its original mass.

[0082] 6, the first semi-carbonized fuel Sa and the second semi-carbonized fuel Sb show a stable increase in the amount of lab-produced gas Gr produced between 300° C. and 500° C. In contrast, the fourth semi-carbonized fuel Sy shows an increase in the amount of lab-produced gas Gr produced as the temperature rises, but with large variations, and the amount of lab-produced gas Gr produced is unstable.

[0083] From this, it can be seen that the torrefied fuel S, which is obtained by torrefying the biomaterial O with superheated steam V, can efficiently and stably generate the lab-produced gas Gr by heating it inside the quartz tube 41. Therefore, it is considered that the torrefied fuel S can also efficiently and stably generate the produced gas G in the reaction tower 21.

[0084] Furthermore, using the electric heater tubular pyrolysis gasifier 40, woody and herbaceous materials were torrefied with superheated steam V, and the mass change of the torrefied materials was investigated in the same manner as in the above experiment (see Figure 7). Here, chestnut, paulownia, fast-growing trees, coffee grounds, sorghum, bamboo, driftwood, and konara were used as woody and herbaceous materials.

[0085] As shown in Figure 7, the mass of these torrefied wood-based and herbaceous materials torrefied with superheated steam V gradually decreases from 0°C to 300°C, and then decreases rapidly between 300°C and 400°C. The mass also decreases between 400°C and 800°C. That is, the mass loss curves of these torrefied materials versus the internal temperature of the quartz tube 41 all form an inverted S-shape as the temperature increases.

[0086] As shown above, the mass loss curves for all woody and herbaceous materials have a similar inverted S-shape, which suggests that the gasification process is similar even for different raw materials. In other words, different raw materials can be treated in the same way as torrefied materials.

[0087] This gasification method includes a torrefaction process in which such woody and herbaceous materials are superheated with superheated steam V to produce torrefied fuel S, and a gasification process in which the torrefied fuel S is gasified using a gasification system 2 that feeds the torrefied fuel S from below and releases the generated gas G from above, making it possible to efficiently gasify torrefied fuel S obtained by torrefaction processing of woody and herbaceous materials.

[0088] More specifically, the superheated steam V penetrates the woody and herbaceous materials, hydrolyzing and dissolving components that cause clinker formation, such as potassium, contained in the woody and herbaceous materials. This allows a solid fuel with high energy density to be obtained in the torrefaction process, from which most of the potassium contained in the woody and herbaceous materials has been removed. Therefore, in the gasification process, the ash and potassium remaining from the gasified torrefied fuel S can be prevented from forming clinker, enabling stable and continuous gasification in the gasification system 2.

[0089] Furthermore, in the torrefaction process, minerals such as potassium contained in the woody and herbaceous materials are hydrolyzed and released, thereby producing porous torrefied fuel S. In other words, the surface area of ​​the torrefied fuel S can be increased. This allows the torrefied fuel S to be efficiently pyrolyzed in the gasification system 2. Therefore, in the gasification process, the torrefied fuel S can be efficiently and stably gasified, and char, tar, etc. can be easily pyrolyzed and gasified, increasing the gas yield.

[0090] Furthermore, in the gasification process, the torrefied fuel S is introduced from the lower side, opposite to the upper side where an endothermic reaction may occur in the gasification system 2, thereby preventing a decrease in the internal temperature of the gasification system 2. This stabilizes the internal temperature of the gasification system 2, allowing the torrefied fuel S to be stably gasified.

[0091] Furthermore, in the semi-carbonization step, by semi-carbonizing the woody material and herbaceous material with superheated steam V, the yield of the generated gas G obtained by pyrolysis can be increased. In other words, the gasification efficiency in the gasification system 2 can be improved.

[0092] Furthermore, in the semi-carbonization process, the yield of the generated gas G obtained by pyrolysis can be further increased by superheating the woody material and herbaceous material with superheated steam V at 300 degrees. In other words, the gasification efficiency in the gasification system 2 can be further improved.

[0093] Furthermore, the gasification system 2 is equipped with a conveying device 30 into which semi-carbonized wood chips are fed, and a reaction tower 21 that gasifies the wood chips. The conveying device 30 is equipped with a vertical tubular longitudinal conveying path 33 that conveys the wood chips from the bottom to the inside of the reaction tower 21. Furthermore, a discharge pipe 22 is provided above the reaction tower 21, through which gas produced from the wood chips is discharged. In addition, the vertical conveying path 33 is erected in the vertical direction and is equipped with a tubular vertical conveying pipe 331 connected to an insertion hole provided at the bottom of the reaction tower 21, and a vertical screw blade 332 that is installed inside the vertical conveying pipe 331, is formed in a spiral shape along the vertical direction, and is rotatable around an axis along the vertical direction as the rotation axis, and the vertical screw blade 332 protrudes upward from the vertical conveying pipe 331 and is exposed above the bottom of the reaction tower 21 so as to circulate wood chips that have fallen to the bottom of the reaction tower 21 without being gasified.

[0094] This allows the torrefied fuel S to be transported from the bottom to the top in the reaction tower 21, and the torrefied fuel S that falls without being gasified at the upper end of the vertical screw blade 332 can be transported again to the top of the reaction tower 21 together with the torrefied fuel S that is newly added to the reaction tower 21.

[0095] Therefore, the torrefied fuel S that has not been sufficiently gasified can be gasified together with new torrefied fuel S. That is, the torrefied fuel S that has not been gasified inside the reaction tower 21 can be circulated and reused, which makes it possible to more efficiently gasify the torrefied fuel S and suppress the generation of clinker.

[0096] Furthermore, the torrefied fuel S that has fallen to the bottom can be transported upward again by the vertical screw blades 332, so that the torrefied fuel S that has fallen from above and piled up can be broken down. This makes it possible to eliminate bridges formed by the piled torrefied fuel S.

[0097] In addition, by introducing carbon dioxide as a gasifying agent H into the reaction tower 21 in the gasification process, the carbon dioxide introduced as the gasifying agent H can efficiently promote the gasification of the semi-carbonized fuel S and prevent the concentration of the generated gas G from decreasing.

[0098] In addition, because the majority of minerals such as potassium have been removed by the superheated steam V, the ash, which is the residue of the gasified torrefied fuel S, can be burned at around 800°C. This allows the ash to be burned at a low temperature, and more reliably prevents the ash from melting and producing clinker.

[0099] Furthermore, carbon dioxide is introduced from the bottom of the reaction tower 21. This allows carbon dioxide to be efficiently supplied as the gasifying agent H to the pyrolysis layer formed below the reaction tower 21, where the pyrolysis of the torrefied fuel S progresses, thereby more efficiently promoting the pyrolysis reaction.

[0100] In correspondence with the configuration of the present invention and the above-mentioned embodiment, Superheated steam corresponds to superheated steam V, and similarly, Semi-carbonized fuel material corresponds to Semi-carbonized Fuel S, The gas corresponds to the product gas G, The gasifier corresponds to the gasification system 2, The input mechanism corresponds to the conveying device 30, The reaction tower corresponds to the reaction tower 21, The vertical conveying path corresponds to the vertical conveying path 33, The discharge pipe corresponds to the discharge pipe 22, The vertical conveying pipe corresponds to the vertical conveying pipe 331; The longitudinal screw flight corresponds to the longitudinal screw flight 332, but the present invention is not limited to the configuration of the above-mentioned embodiment, and many embodiments can be obtained.

[0101] For example, in this embodiment, the bio-material O is dried in the drying rotary kiln 12 and then semi-carbonized in the semi-carbonization rotary kiln 13 using superheated steam V at 300°C or 350°C. However, the temperature in the semi-carbonization rotary kiln 13 is not limited to 300°C or 350°C and may be changed as appropriate.

[0102] In addition, in this embodiment, the carbon dioxide stored in the gasifying agent supply unit 27 is supplied to the reaction tower 21 as the gasifying agent H, but the present invention is not limited to this configuration. For example, the carbon dioxide generated in the reaction tower 21 may be circulated and introduced into the reaction tower 21 as the gasifying agent H. Furthermore, in this embodiment, carbon dioxide is used as the gasifying agent H, but it is not limited to carbon dioxide and may be air, water vapor, or the like.

[0103] Furthermore, in this embodiment, the gasification system 2 gasifies bamboo that has been torrefied with superheated steam V as the torrefied fuel S, but as described above, at least one of woody materials and herbaceous materials can be used. That is, for example, the torrefied fuel S may be obtained by torrefying one or more of the woody materials and herbaceous materials, such as "chestnut," "paulownia," "fast-growing trees," "coffee grounds," "sorghum," "driftwood," and "konara" (Japanese oak) with superheated steam V.

[0104] In this embodiment, the gasification system 2 is of a so-called updraft type, in which the discharge pipe 22 is provided above the reaction tower 21, but it may also be of a downdraft type. Furthermore, the torrefied fuel S may be introduced from above, not from below. [Explanation of symbols]

[0105] 2. Gasification system 21...Reaction tower 22...Emission tube 30...Transportation device 33...Vertical conveying path 33...Vertical conveying pipe 332...Vertical screw blade V: Superheated steam S…Semi-carbonized fuel G: Produced gas

Claims

1. a torrefaction step of heating at least one of a woody material and a herbaceous material with superheated steam to produce torrefied fuel material; The torrefied fuel material is introduced, and a gasification step is carried out in which the torrefied fuel material is gasified using a gasification device that emits gas. Gasification method.

2. In the semi-carbonization step, at least one of the wood-based material and the herbaceous material was heated with the superheated steam at 300 degrees. The gasification method according to claim 1 .

3. The gasification apparatus includes an input mechanism that inputs the torrefied fuel material from below, and a reaction tower that gasifies the torrefied fuel material, The input mechanism includes: a vertical tubular longitudinal conveying path for conveying the torrefied fuel material from the bottom of the reaction tower to the inside thereof; The reaction column contains a discharge pipe for discharging gas generated from the torrefied fuel material is provided at the top, The longitudinal conveying path is a tubular vertical conveying pipe that is erected along the vertical direction and connected to an insertion hole provided at the bottom of the reaction tower; a vertical screw blade that is installed inside the vertical conveying pipe, is formed in a spiral shape along the vertical direction, and is rotatable around an axis that is along the vertical direction; The longitudinal screw flights are The torrefied fuel material that has fallen to the bottom of the reaction tower without being gasified is circulated by a vertical transport pipe that protrudes upward from the vertical transport pipe and is exposed above the bottom of the reaction tower. The gasification method according to claim 1 .

4. In the gasification step, Carbon dioxide is introduced into the reaction tower as a gasifying agent. The gasification method according to claim 3.

5. The carbon dioxide is introduced from the bottom of the reaction tower. The gasification method according to claim 4.

6. At least one of wood-based material and herbaceous material is heated with superheated steam to semi-carbonize it, thereby producing semi-carbonized fuel material. Manufacturing method for semi-carbonized fuel material.

7. The temperature of the superheated steam is 300 degrees. The method for producing the torrefied fuel material according to claim 6.

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