Thermal decomposition gasification method

Abstract

To provide a thermal decomposition gasification method capable of enhancing a targeted yield of thermal decomposition products by controlling a temperature within a thermal decomposition furnace.SOLUTION: A thermal decomposition gasification method includes: thermally decomposing a material in a thermal decomposition furnace 1 by using heat of a fluid medium comprising a mixture of large diameter particles and small diameter particles having different mean particle diameters; collecting the small diameter particles included in thermal decomposition gas discharged from the thermal decomposition furnace 1 by using a solid-gas separation device 6; heating the small diameter particles collected by the solid-gas separation device 6 by using a heating device 12; and returning the small diameter particles heated by the heating device 12 to the thermal decomposition furnace 1 through a particle return line 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pyrolysis gasification method in which a raw material is pyrolyzed in a pyrolysis furnace, and more particularly to a technique for controlling the temperature in the pyrolysis furnace. [Background technology]

[0002] Patent Documents 1 and 2 disclose fluidized-bed furnaces as processing systems for pyrolyzing and gasifying raw materials such as municipal solid waste and industrial waste. The interior of the fluidized-bed furnaces described in these patent documents is divided into a pyrolysis furnace and a media regeneration furnace by a partition wall, and a fluidizing medium circulates between the pyrolysis furnace and the media regeneration furnace. Such fluidized-bed furnaces are known as internally circulating fluidized-bed gasification systems.

[0003] From the perspective of preventing global warming, there is a growing demand for recovering oil from waste plastics through thermal decomposition (Patent Documents 3 and 4). However, it is difficult to recover oil with a high yield, and the reality is that there have been few commercially successful examples. The above-mentioned internal circulating fluidized bed gasification system is expected to be a technology that can heat and pyrolyze waste plastics in a pyrolysis furnace and recover organic compounds that are liquid at room temperature and pressure, i.e., oil, as a pyrolysis product.

[0004] In particular, fluidized bed gasification systems with a structure that separates the pyrolysis furnace and media regeneration furnace are capable of recovering highly concentrated pyrolysis products. Specifically, the raw material fed into the pyrolysis furnace is pyrolyzed in the fluidized bed and separated into volatile matter and residue (such as carbonized material). The residue is transported to the media regeneration furnace along with the fluidized media, where it is combusted by air fed from the bottom of the media regeneration furnace. The fluidized media heated in the media regeneration furnace is then transferred back to the pyrolysis furnace, where it functions as a heat source for the pyrolysis reaction. The volatile matter generated in the pyrolysis furnace can be recovered as a product without including the combustion exhaust gas generated in the media regeneration furnace, making it possible to recover highly concentrated pyrolysis products.

[0005] From the perspective of preventing global warming, the widespread use of chemical recycling, which uses the recovered pyrolysis products as chemical raw materials, is expected. However, a challenge with chemical recycling is the yield of compounds. Generally, the types of compounds required as chemical raw materials are limited, so it is necessary to increase the yield of the desired compounds.

[0006] On the other hand, the composition of pyrolysis products is primarily determined by the raw material, temperature, and residence time. When waste materials such as waste plastics are used as raw materials, the raw material contains a variety of compounds. As a result, the products obtained by pyrolysis are also diverse, reducing their value as chemical raw materials. Therefore, it is necessary to control the product composition by controlling the temperature and residence time. A pyrolysis furnace consists of a dense layer containing a high concentration of bed material, a splash zone above the dense layer where bed material and a large amount of gas coexist, and a freeboard above the splash zone that contains almost no bed material and is mainly gas. To control the pyrolysis temperature, the temperature of the dense layer in the pyrolysis furnace is controlled. Temperature control of the dense layer can be achieved mainly by adjusting the amount of heat transferred from the bed material regeneration furnace to the pyrolysis furnace, i.e., the amount of bed material circulated. Residence time control can be achieved by changing the amount of fluidizing gas supplied to the pyrolysis furnace.

[0007] To maintain a constant composition of the pyrolysis product, it is necessary to maintain a constant temperature for a certain period of time. However, as the endothermic pyrolysis reaction progresses in the freeboard, the temperature drops, making it difficult to maintain that temperature. As a result, it is difficult to improve the yield of compounds desired as chemical raw materials. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4243919 [Patent Document 2] Patent No. 6935482 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-129169 [Patent Document 4] Patent No. 3611306 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the present invention provides a pyrolysis gasification method that can increase the yield of the target pyrolysis product by controlling the temperature inside the pyrolysis furnace. [Means for solving the problem]

[0010] In one aspect, there is provided a pyrolysis gasification method for pyrolyzing a feedstock, the method comprising: pyrolyzing the feedstock in a pyrolysis furnace using heat from a fluidized medium comprising a mixture of large-diameter particles and small-diameter particles having different average particle sizes; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator; heating the small-diameter particles collected by the solid-gas separator using a heating device; and returning the small-diameter particles heated by the heating device to the pyrolysis furnace through a particle return line.

[0011] In one aspect, there is provided a pyrolysis gasification method for pyrolyzing a feedstock, the method comprising: pyrolyzing the feedstock in a pyrolysis furnace using the heat of a fluidized medium consisting of a mixture of large-diameter particles and small-diameter particles with different average particle sizes; burning the feedstock residue in a media regeneration furnace while fluidizing the fluidized medium; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a first solid-gas separator; returning the small-diameter particles collected by the first solid-gas separator to the media regeneration furnace through a first particle return line; collecting the small-diameter particles contained in the combustion exhaust gas discharged from the media regeneration furnace using a second solid-gas separator; and returning the small-diameter particles collected by the second solid-gas separator to the pyrolysis furnace through a second particle return line.

[0012] In one aspect, there is provided a pyrolysis gasification method for pyrolyzing a feedstock, the method comprising: pyrolyzing the feedstock in a pyrolysis furnace using the heat of a fluidized medium consisting of a mixture of large-diameter particles and small-diameter particles having different average particle sizes; burning the residue of the feedstock in a media regeneration furnace while fluidizing the fluidized medium; transferring the fluidized medium from the media regeneration furnace to the pyrolysis chamber through a media settling chamber; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator; and returning the small-diameter particles collected by the solid-gas separator to the media settling chamber through a particle return line.

[0013] In one aspect, there is provided a pyrolysis gasification method for pyrolyzing a raw material, the method comprising: pyrolyzing the raw material in a pyrolysis furnace using the heat of a fluidized medium consisting of a mixture of large-diameter particles and small-diameter particles having different average particle sizes; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator; and returning the small-diameter particles collected by the solid-gas separator to the pyrolysis furnace through a particle return line, the particle return line extending through the interior of the media regeneration furnace to the pyrolysis furnace; and heating the small-diameter particles in the particle return line by burning the residue of the raw material in the media regeneration furnace. [Effects of the Invention]

[0014] According to the above-described embodiment, the small-diameter particles heated by the heating device are returned to the pyrolysis furnace. The high-temperature small-diameter particles are raised in the pyrolysis furnace by the fluidizing gas that fluidizes the bed material, and quickly reach the freeboard. Therefore, the temperature in the freeboard is maintained at a high temperature, allowing the pyrolysis reaction to proceed in the freeboard. As a result, the yield of the target pyrolysis product can be increased.

[0015] According to the above-described embodiment, the small-diameter particles returned to the media regeneration furnace are heated by combustion in the media regeneration furnace. The heated small-diameter particles are stirred up in the media regeneration furnace by the fluidizing gas that fluidizes the bed material and are discharged from the media regeneration furnace together with the combustion exhaust gas. The high-temperature small-diameter particles contained in the combustion exhaust gas are collected by the second solid-gas separator and returned to the pyrolysis furnace. The high-temperature small-diameter particles are stirred up in the pyrolysis furnace by the fluidizing gas that fluidizes the bed material and quickly reach the freeboard. Therefore, the temperature in the freeboard is maintained at a high temperature, allowing the pyrolysis reaction to proceed in the freeboard. As a result, the yield of the desired pyrolysis product can be increased.

[0016] According to the above-described embodiment, the small-diameter particles returned to the media settling chamber are mixed with and heated by the high-temperature fluidized medium sent from the media regeneration furnace. The heated small-diameter particles are sent to the pyrolysis furnace together with the fluidized medium. The small-diameter particles in the fluidized medium are stirred up in the pyrolysis furnace by the fluidizing gas that fluidizes the fluidized medium, and quickly reach the freeboard. Therefore, the temperature in the freeboard is maintained at a high temperature, allowing the pyrolysis reaction to proceed in the freeboard. As a result, the yield of the desired pyrolysis product can be increased.

[0017] According to the above-described embodiment, small particles collected by the solid-gas separator are heated by combustion in the media regeneration furnace while being transported through the particle return line. The heated small particles are returned to the pyrolysis furnace through the particle return line. The high-temperature small particles are lifted up in the pyrolysis furnace by the fluidizing gas that fluidizes the bed material, and quickly reach the freeboard. This maintains a high temperature in the freeboard, allowing the pyrolysis reaction to proceed in the freeboard. As a result, the yield of the desired pyrolysis product can be increased. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram illustrating one embodiment of a pyrolysis gasification system for pyrolyzing a feedstock. [Figure 2]FIG. 2 is a cross-sectional view showing an example of a latent heat storage microcapsule. [Figure 3] FIG. 2 is a schematic diagram showing another embodiment of a pyrolysis gasification system. [Figure 4] FIG. 10 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. [Figure 5] FIG. 10 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. [Figure 6] FIG. 10 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. [Figure 7] FIG. 10 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing one embodiment of a pyrolysis gasification system for pyrolyzing a feedstock. The pyrolysis gasification system includes a pyrolysis furnace 1 that pyrolyzes the feedstock using the heat of a bed material. The pyrolysis furnace 1 holds a bed material therein. In this embodiment, the bed material is composed of a mixture of large and small particles with different average particle sizes.

[0020] A fluidizing gas G1 is supplied into the pyrolysis furnace 1 from the bottom thereof to fluidize the bed material. The bed material is fluidized by the fluidizing gas G1, forming a fluidized bed in the pyrolysis furnace 1. A dense layer 2 is formed below the fluidized bed, where large particles contained in the bed material exist at a high density. A free board 3 is formed above the fluidized bed, where small particles contained in the bed material exist. In this embodiment, as will be described later, the pyrolysis reaction proceeds not only in the dense layer 2 but also in the free board 3.

[0021] The raw material to be processed is fed into the pyrolysis furnace 1. The raw material is agitated by the swirling flow of the bed material in the pyrolysis furnace 1, receives heat from the bed material, and undergoes pyrolysis. The raw material to be processed by the pyrolysis gasification system is not particularly limited, but includes, for example, organic matter such as waste plastics. The pyrolysis furnace 1 is operated under oxygen-lean conditions to promote the pyrolysis of the raw material. Therefore, the raw material does not burn in the pyrolysis furnace 1.

[0022] The pyrolysis gasification system further includes a solid-gas separator 6 that collects small-diameter particles of the bed material contained in the pyrolysis gas discharged from the pyrolysis furnace 1. The solid-gas separator 6 is connected to the pyrolysis furnace 1 by a pyrolysis gas transfer line 8. When the feedstock is pyrolyzed, pyrolysis gas is generated. This pyrolysis gas is transferred from the pyrolysis furnace 1 to the solid-gas separator 6 through the pyrolysis gas transfer line 8. The solid-gas separator 6 is located downstream of the pyrolysis furnace 1 in the flow direction of the pyrolysis gas. The solid-gas separator 6 is configured to collect small-diameter particles (bed material) contained in the pyrolysis gas.

[0023] In this embodiment, the bed material contains large and small particles, with the small particles having a smaller average particle size than the large particles. The fluidization state of the bed material depends on the supply flow rate of the fluidizing gas G1 and the particle size of the bed material. The flow rate of the fluidizing gas G1 is adjusted to optimize the fluidization state of the particles in the fluidized bed. Generally, the narrower the particle size distribution of the bed material, the more uniform the particle behavior. In contrast, in this embodiment, a bed material containing large and small particles with different average particle sizes is used, which causes the large and small particles to exhibit different flow behaviors in the fluidized bed due to the difference in particle size. That is, the large particles contribute to mixing, stirring, and heat transfer in the dense layer 2, while the small particles contribute to scattering and heat transfer to the freeboard 3.

[0024] To promote mixing, stirring, and heat transfer in the fluidized bed, it is necessary to increase the flow rate of the fluidizing gas G1 supplied from the bottom of the pyrolysis furnace 1 and increase the fluidization speed. Therefore, the large-diameter particles have an average particle size that makes them less likely to scatter to the freeboard 3 even when the fluidization speed is increased. In one embodiment, the large-diameter particles have an average particle size in the range of 300 μm to 600 μm. On the other hand, the small-diameter particles have an average particle size that makes them easily scatter to the freeboard 3. In one embodiment, the small-diameter particles have an average particle size in the range of 20 μm to 40 μm.

[0025] The solid-gas separator 6 is configured to capture particles with particle diameters of 20 μm to 40 μm in order to capture small particles contained in the pyrolysis gas discharged from the pyrolysis furnace 1. Specific examples of the solid-gas separator 6 include a cyclone, a bag filter, and an electrostatic precipitator. While bag filters and electrostatic precipitators can capture particles with a diameter of 1 μm or less, they are not necessarily optimal in terms of equipment cost and equipment reliability and maintainability. On the other hand, the limit particle diameter for a cyclone to capture is approximately 10 μm, but cyclones have a simple structure and are excellent in reliability and maintainability. Therefore, in this embodiment, a cyclone is used as the solid-gas separator 6. However, the solid-gas separator 6 is not limited to a cyclone as long as it is capable of capturing particles with a diameter of 20 μm to 40 μm.

[0026] The pyrolysis gasification system further includes a heater 12 that heats the small-diameter particles collected by the solid-gas separator 6, and a particle return line 15 that returns the small-diameter particles heated by the heater 12 to the pyrolysis furnace 1. The heater 12 is connected to the solid-gas separator 6 and the particle return line 15, and the particle return line 15 is connected to the pyrolysis furnace 1. The heater 12 is disposed between the solid-gas separator 6 and the particle return line 15. The particle return line 15 extends from the heater 12 to the pyrolysis furnace 1.

[0027] Examples of the heating device 12 include an electric heater and a heat exchanger (e.g., a shell-and-tube heat exchanger, a jacketed tube). The heat source of the heat exchanger can be the combustion exhaust gas generated in the process of regenerating the fluidized medium, or high-temperature steam.

[0028] The small-diameter particles heated by the heater 12 are returned to the pyrolysis furnace 1 through the particle return line 15. The high-temperature small-diameter particles are raised in the pyrolysis furnace 1 by the fluidizing gas G1 that fluidizes the bed material, and quickly reach the freeboard 3. Therefore, the temperature in the freeboard 3 is maintained at a high temperature, allowing the pyrolysis reaction to proceed in the freeboard 3. As a result, the yield of the desired pyrolysis product can be increased.

[0029] The pyrolysis gasification system further includes a gas seal device 18 that prevents backflow of gas from the pyrolysis furnace 1. The gas seal device 18 is attached to the particle return line 15. The gas seal device 18 is provided to prevent a decrease in pyrolysis yield and particles from scattering downstream of the solid-gas separator 6. Examples of the gas seal device 18 include, but are not limited to, a loop seal, a rotary valve, and a trickle valve.

[0030] By properly adjusting the operating conditions of the pyrolysis gasification system, the majority of the pyrolysis reaction (50% or more) will proceed in dense layer 2. If most of the pyrolysis reaction proceeds in dense layer 2 (90% or more), adding small-diameter particles to the fluidized bed is not appropriate because there is little benefit and it would increase capital investment. The amount of pyrolysis reaction in dense layer 2 is affected by the raw material and operating mode. By adding small-diameter particles to large-diameter particles in accordance with the proportion of unreacted particles in dense layer 2, the small-diameter particles will contribute to the pyrolysis reaction in freeboard 3.

[0031] In one embodiment, when the large and small particles are made of the same material (heat capacity), the weight ratio of the large and small particles is 9:1 to 5:5. This corresponds to a thermal decomposition reaction in which the amount of thermal decomposition in the dense layer 2 is 50 to 90% and the amount of thermal decomposition in the freeboard 3 is 10 to 50%. In other words, to promote thermal decomposition in the freeboard 3, 10 to 50% of the reaction heat is supplied to the freeboard 3. The materials for the large and small particles are not particularly limited, but silica sand, for example, is used.

[0032] The large and small particles that make up the fluid medium may be made of different materials. In one embodiment, the large particles may be made of silica sand, and the small particles may be made of latent heat storage microcapsules, as described below.

[0033] Figure 2 is a cross-sectional view showing an example of a latent heat storage microcapsule. A latent heat storage microcapsule is a heat storage particle that utilizes the latent heat required for a phase change of a material. As shown in Figure 2, the latent heat storage microcapsule has a latent heat storage material 20 and a shell 21 that covers the latent heat storage material 20.

[0034] The latent heat storage material 20 is a material that, when it absorbs heat and changes from a solid phase to a liquid phase, stores the absorbed heat as latent heat, and at the same time, releases the stored heat and changes from the liquid phase to a solid phase. Examples of such latent heat storage material 20 include metals such as aluminum and aluminum-based alloys. The shell 21 is made of a material having a higher melting point than the latent heat storage material 20. Examples of materials for the shell 21 include ceramics such as aluminum oxide.

[0035] Latent heat storage microcapsules have a very large heat capacity at the phase change temperature. Therefore, when latent heat storage microcapsules are used as small-diameter particles of the fluid medium, they can supply the reaction heat necessary for thermal decomposition in the freeboard 3, significantly improving the temperature controllability of the freeboard 3. Specifically, by using latent heat storage microcapsules, the amount of fluid medium used can be reduced while the amount of heat supplied to the freeboard 3 can be improved. In particular, while the phase change of the latent heat storage material 20 is occurring, the temperature of the freeboard 3 can be maintained constant at the phase change temperature (e.g., 500°C). In other words, by using latent heat storage microcapsules, not only can the amount of fluid medium used be significantly reduced, but the large heat capacity allows the freeboard 3 to be maintained at a high temperature, and the operating temperature of the freeboard 3 can be controlled constant in accordance with the phase change temperature.

[0036] Fig. 3 is a schematic diagram showing another embodiment of the pyrolysis gasification system. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 1, and therefore, redundant description will be omitted.

[0037] The pyrolysis gasification system is equipped with a media regeneration furnace 31 that combusts the raw material residue while fluidizing the bed material. In the pyrolysis furnace 1, the fluidization state can deteriorate due to the adhesion of coke to the bed material and the accumulation of residue. Therefore, the media regeneration furnace 31 is installed next to the bed material to combust the coke and residue and remove them from the bed material. In the media regeneration furnace 31, the bed material is heated by the heat of combustion of the carbon contained in the feed material, and this heat is used to heat the bed material.

[0038] The pyrolysis gasification system further includes a solid-gas separator 6 that collects small particles contained in the pyrolysis gas discharged from the pyrolysis furnace 1, a particle return line 37 that returns the small particles collected by the solid-gas separator 6 to the media regeneration furnace 31, a solid-gas separator 43 that collects small particles contained in the combustion exhaust gas discharged from the media regeneration furnace 31, and a particle return line 45 that returns the small particles collected by the solid-gas separator 43 to the pyrolysis furnace 1. In this embodiment, the heating device 12 shown in FIG. 1 is not provided.

[0039] The bed material used includes large and small particles with different average particle sizes, as in the embodiment described with reference to FIG. 1. The small particles may be latent heat storage microcapsules. The medium regeneration furnace 31 is connected to the pyrolysis furnace 1 through a medium transfer passage 47 and a medium transfer passage 48. The raw material is agitated by the swirling flow of the bed material in the pyrolysis furnace 1, receives heat from the bed material, and is pyrolyzed. The raw material residue, together with a portion of the bed material, is sent to the medium regeneration furnace 31 through the medium transfer passage 48. A fluidizing gas G2 for fluidizing the bed material is supplied to the medium regeneration furnace 31.

[0040] The raw material residue is burned while swirling together with the bed material in the media regeneration furnace 31. As the raw material residue is burned, it releases thermal energy, heating the bed material while generating combustion exhaust gas. A portion of the heated bed material is sent to the pyrolysis furnace 1 through the media transfer passage 47. The heated bed material provides the heat required for pyrolysis, which causes the pyrolysis of the raw material to proceed in the pyrolysis furnace 1. The bed material can be transported through the media transfer passages 47 and 48 by gravity, a conveyor, or pressure feed using air or an inert gas, but there is no particular limitation as long as the bed material can be transported.

[0041] The solid-gas separator 6 is connected to the pyrolysis furnace 1 by a pyrolysis gas transfer line 8. When the feedstock is pyrolyzed, pyrolysis gas is generated. This pyrolysis gas is transferred from the pyrolysis furnace 1 to the solid-gas separator 6 through the pyrolysis gas transfer line 8. The solid-gas separator 6 is disposed downstream of the pyrolysis furnace 1 in the flow direction of the pyrolysis gas. The configuration of the solid-gas separator 6 is the same as that of the solid-gas separator 6 in the embodiment described with reference to FIG. 1. A particle return line 37 extends from the solid-gas separator 6 to the media regeneration furnace 31. Small particles collected by the solid-gas separator 6 are sent to the media regeneration furnace 31 through the particle return line 37.

[0042] The solid-gas separator 43 is connected to the media regeneration furnace 31 by a flue gas transfer line 38. The flue gas generated in the media regeneration furnace 31 is transferred from the media regeneration furnace 31 to the solid-gas separator 43 through the flue gas transfer line 38. The solid-gas separator 43 is disposed downstream of the media regeneration furnace 31 in the flow direction of the flue gas. The configuration of the solid-gas separator 43 is the same as the solid-gas separator 6 in the embodiment described with reference to FIG. 1. A particle return line 45 extends from the solid-gas separator 43 to the pyrolysis furnace 1. The small-diameter particles collected by the solid-gas separator 43 are sent to the pyrolysis furnace 1 through the particle return line 45.

[0043] The pyrolysis gasification system of this embodiment operates as follows. The raw material is fed into the pyrolysis furnace 1 and thermally decomposes under the heat of the bed material. Small particles contained in the bed material are sent to the solid-gas separator 6 along with the pyrolysis gas produced by pyrolysis. The solid-gas separator 6 captures the small particles contained in the pyrolysis gas. The captured small particles are sent to the media regeneration furnace 31 via the particle return line 37. The small particles are heated in the media regeneration furnace 31 by combustion of the raw material residue. The heated small particles are stirred up in the media regeneration furnace 31 by the fluidizing gas G2 that fluidizes the bed material and are discharged from the media regeneration furnace 31 together with the combustion exhaust gas. The high-temperature small particles contained in the combustion exhaust gas are collected by the solid-gas separator 43 and returned to the pyrolysis furnace 1 via the particle return line 45. The high-temperature small particles are stirred up in the pyrolysis furnace 1 by the fluidizing gas G1 that fluidizes the bed material and quickly reach the freeboard 3. Therefore, the temperature inside the freeboard 3 is maintained at a high temperature, and the thermal decomposition reaction can proceed in the freeboard 3. As a result, the yield of the target thermal decomposition product can be increased.

[0044] The pyrolysis gasification system of this embodiment further includes a gas sealing device 51 that prevents backflow of gas from the media regeneration furnace 31, and a gas sealing device 52 that prevents backflow of gas from the pyrolysis furnace 1. The gas sealing device 51 is attached to the particle return line 37, and the gas sealing device 52 is attached to the particle return line 45. Gas sealing devices 53 and 54 are also attached to the media transfer passages 47 and 48. Examples of the gas sealing devices 51 and 52 and the gas sealing devices 53 and 54 include, but are not limited to, loop seals, rotary valves, and trickle valves.

[0045] The gas sealing devices 51, 52 and 53, 54 are provided for the following purposes: The pyrolysis furnace 1 is operated in an oxygen-depleted, flammable gas atmosphere to promote pyrolysis. On the other hand, the media regeneration furnace 31 is operated in an oxygen (air) atmosphere to burn the residue remaining after pyrolysis. Therefore, if the gas in the pyrolysis furnace 1 mixes with the gas in the media regeneration furnace 31, safety issues such as fire or explosion may occur. Therefore, the gas sealing devices 51, 52 and 53, 54 are provided to reliably prevent gas mixing (backflow). Note that the gas sealing devices 53, 54 may be omitted for the media transfer passages 47, 48 if the installed fluidized medium transfer means can reliably prevent gas mixing (backflow).

[0046] Fig. 4 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 3, and therefore, redundant description will be omitted.

[0047] The pyrolysis gasification system further includes a media settling chamber 55 connecting the pyrolysis furnace 1 and the media regeneration furnace 31. The media settling chamber 55 is located between the pyrolysis furnace 1 and the media regeneration furnace 31. The pyrolysis furnace 1, the media regeneration furnace 31, and the media settling chamber 55 are formed within a single fluidized bed furnace 60. That is, the fluidized bed furnace 60 includes the pyrolysis furnace 1, the media regeneration furnace 31, and the media settling chamber 55 therein. A first partition wall 61 is provided between the pyrolysis furnace 1 and the media settling chamber 55, and a second partition wall 62 is provided between the media regeneration furnace 31 and the media settling chamber 55. In this embodiment, the media settling chamber 55 is provided with a gas seal function.

[0048] 4, the media transfer passage 48 is depicted schematically, but the media transfer passage 48 is also located inside the fluidized bed furnace 60. In addition, the pyrolysis furnace 1, the media regeneration furnace 31, and the media settling chamber 55 are depicted in plan view in FIG. 4, but in reality, the pyrolysis furnace 1, the media regeneration furnace 31, and the media settling chamber 55 have a three-dimensional shape, and the pyrolysis furnace 1 can also be disposed adjacent to both the media regeneration furnace 31 and the media settling chamber 55. Therefore, the media transfer passage 48 may simply consist of an opening.

[0049] The bed material used includes large and small particles with different average particle sizes, as in the embodiment described with reference to FIG. 1. The small particles may be latent heat storage microcapsules. The medium regeneration furnace 31 is connected to the pyrolysis furnace 1 through the medium settling chamber 55 and the medium transfer passage 48. The raw material is agitated by the swirling flow of the bed material in the pyrolysis furnace 1, receives heat from the bed material, and is pyrolyzed. The raw material residue, together with a portion of the bed material, is sent to the medium regeneration furnace 31 through the medium transfer passage 48. A fluidizing gas G2 for fluidizing the bed material is supplied to the medium regeneration furnace 31.

[0050] The raw material residue is burned while swirling together with the bed material in the media regeneration furnace 31. As the raw material residue burns, it releases thermal energy, heating the bed material while generating combustion exhaust gas. A portion of the heated bed material flows over the second partition wall 62 into the bed material settling chamber 55 and then descends within the bed material settling chamber 55. The bed material is then sent to the pyrolysis furnace 1 through the lower opening of the first partition wall 61. The heated bed material provides the heat required for pyrolysis, which causes the pyrolysis of the raw material to proceed within the pyrolysis furnace 1. The fluidized bed furnace 60, in which the bed material circulates through the pyrolysis furnace 1, the media regeneration furnace 31, and the bed material settling chamber 55, is called an internal circulating fluidized bed gasification system.

[0051] The pyrolysis gasification system of this embodiment operates as follows. The raw material is fed into the pyrolysis furnace 1 and thermally decomposes under the heat of the bed material. Small particles contained in the bed material are sent to the solid-gas separator 6 along with the pyrolysis gas produced by pyrolysis. The solid-gas separator 6 captures the small particles contained in the pyrolysis gas. The captured small particles are sent to the media regeneration furnace 31 via the particle return line 37. The small particles are heated in the media regeneration furnace 31 by combustion of the raw material residue. The heated small particles are stirred up in the media regeneration furnace 31 by the fluidizing gas G2 that fluidizes the bed material and are discharged from the media regeneration furnace 31 together with the combustion exhaust gas. The high-temperature small particles contained in the combustion exhaust gas are collected by the solid-gas separator 43 and returned to the pyrolysis furnace 1 via the particle return line 45. The high-temperature small particles are stirred up in the pyrolysis furnace 1 by the fluidizing gas G1 that fluidizes the bed material and quickly reach the freeboard 3. Therefore, the temperature inside the freeboard 3 is maintained at a high temperature, and the thermal decomposition reaction can proceed in the freeboard 3. As a result, the yield of the target thermal decomposition product can be increased.

[0052] Fig. 5 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 4, and therefore, redundant description will be omitted.

[0053] The pyrolysis gasification system includes a particle return line 65 extending from the solid-gas separator 6 to the media settling chamber 55 and a gas seal device 66 that prevents backflow of gas from the media settling chamber 55. The gas seal device 66 is attached to the particle return line 65. Examples of the gas seal device 66 include, but are not limited to, a loop seal, a rotary valve, and a trickle valve. The gas seal device 66 serves the same purpose as the gas seal devices 51, 52, 53, and 54 in the embodiment described with reference to FIG. 3. In this embodiment, the solid-gas separator 43, the particle return lines 37 and 45, and the gas seal devices 51 and 52 shown in FIG. 3 are not provided. The media settling chamber 55 is provided with a gas seal function.

[0054] The pyrolysis gasification system of this embodiment operates as follows. The raw material is fed into the pyrolysis furnace 1 and thermally decomposed by the heat from the bed material. Small particles contained in the bed material are sent to the solid-gas separator 6 along with the pyrolysis gas produced by pyrolysis. The solid-gas separator 6 captures the small particles contained in the pyrolysis gas. The captured small particles are sent to the media settling chamber 55 via the particle return line 65. The small particles returned to the media settling chamber 55 are mixed with the high-temperature bed material sent from the media regeneration furnace 31 and heated. The heated small particles are sent to the pyrolysis furnace 1 along with the bed material. The small particles in the bed material are lifted up within the pyrolysis furnace 1 by the fluidizing gas G1, which fluidizes the bed material, and quickly reach the freeboard 3. This maintains a high temperature within the freeboard 3, allowing the pyrolysis reaction to proceed within the freeboard 3. As a result, the yield of the desired pyrolysis product is increased.

[0055] Fig. 6 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 4, and therefore, redundant description will be omitted.

[0056] The pyrolysis gasification system has a particle return line 70 that extends from the solid-gas separator 6 to the pyrolysis furnace 1 via the media regeneration furnace 31, and a gas seal device 71 that prevents backflow of gas from the pyrolysis furnace 1. The gas seal device 71 is attached to the particle return line 70. The gas seal device 71 is provided to prevent a decrease in pyrolysis yield and the scattering of particles downstream of the solid-gas separator 6.

[0057] The particle return line 70 extends through the interior of the media regeneration furnace 31 to the pyrolysis furnace 1. Because a portion of the particle return line 70 is located inside the media regeneration furnace 31, the small-diameter particles collected by the solid-gas separator 6 are heated by the combustion of the raw material residue in the media regeneration furnace 31 while being transported through the particle return line 70. In this embodiment, the solid-gas separator 43, particle return lines 37 and 45, and gas seal devices 51 and 52 shown in Figure 3 are not provided. The media settling chamber 55 is provided with a gas seal function.

[0058] The pyrolysis gasification system of this embodiment operates as follows. The raw material is introduced into the pyrolysis furnace 1 and thermally decomposes under the heat of the bed material. Small particles contained in the bed material are sent to the solid-gas separator 6 along with the pyrolysis gas produced by pyrolysis. The solid-gas separator 6 captures the small particles contained in the pyrolysis gas. The captured small particles are heated by combustion in the media regeneration furnace 31 while transported through the particle return line 70. The heated small particles are returned to the pyrolysis furnace 1 through the particle return line 70. The high-temperature small particles are lifted up within the pyrolysis furnace 1 by the fluidizing gas G1, which fluidizes the bed material, and quickly reach the freeboard 3. This maintains a high temperature within the freeboard 3, allowing the pyrolysis reaction to proceed within the freeboard 3. As a result, the yield of the desired pyrolysis product can be increased.

[0059] Fig. 7 is a schematic diagram showing yet another embodiment of the pyrolysis gasification system. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Figs. 1 and 4, and therefore, redundant description will be omitted.

[0060] Similar to the embodiment described with reference to FIG. 1, the pyrolysis gasification system includes a solid-gas separator 6 that collects small particles contained in the pyrolysis gas discharged from the pyrolysis furnace 1, a heater 12 that heats the small particles collected by the solid-gas separator 6, a particle return line 15 that returns the small particles heated by the heater 12 to the pyrolysis furnace 1, and a gas seal device 18 attached to the particle return line 15. The configurations of the heater 12, particle return line 15, and gas seal device 18 are the same as those in the embodiment described with reference to FIG. 1. In this embodiment, the solid-gas separator 43, particle return lines 37 and 45, and gas seal devices 51 and 52 shown in FIG. 3 are not provided. The media settling chamber 55 is provided with a gas seal function.

[0061] The pyrolysis gasification system of this embodiment operates as follows. The raw material is fed into the pyrolysis furnace 1 and thermally decomposed by receiving heat from the bed material. Small particles contained in the bed material are sent to the solid-gas separator 6 along with the pyrolysis gas produced by pyrolysis. The solid-gas separator 6 captures the small particles contained in the pyrolysis gas. The captured small particles are heated by the heater 12. The heated small particles are returned to the pyrolysis furnace 1 through the particle return line 15. The high-temperature small particles are lifted up within the pyrolysis furnace 1 by the fluidizing gas G1 that fluidizes the bed material and quickly reach the freeboard 3. This maintains a high temperature within the freeboard 3, allowing the pyrolysis reaction to proceed in the freeboard 3. As a result, the yield of the desired pyrolysis product can be increased.

[0062] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0063] 1 Pyrolysis furnace 2. Rich layer 3 Freeboard 6. Solid-gas separator 8. Pyrolysis gas transfer line 12 Heating device 15 Particle return line 18 Gas seal device 20 Latent heat storage material 21 Shell 31 Media regeneration furnace 37 Particle return line 38 Flue Gas Transfer Line 43 Solid-gas separator 45 Particle return line 47 Media transfer passage 48 Media transfer passage 51,52 Gas seal device 53,54 Gas seal device 55 Media Settling Chamber 60 Fluidized bed furnace 61 First Partition Wall 62 Second Partition Wall 65 Particle return line 66 Gas seal device 70 Particle return line 71 Gas seal device G1, G2 fluidizing gas

Claims

1. A pyrolysis gasification method for pyrolyzing a feedstock, comprising: Pyrolyzing the raw material in a pyrolysis furnace using heat from a fluidized medium consisting of a mixture of large particles and small particles with different average particle sizes; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator; heating the small diameter particles collected by the solid-gas separator with a heating device; The small-diameter particles heated by the heating device are returned to the pyrolysis furnace through a particle return line.

2. The large particles have an average particle size in the range of 300 μm to 600 μm, 2. The pyrolysis gasification method according to claim 1, wherein the small particles have an average particle size in the range of 20 μm to 40 μm.

3. 2. The pyrolysis gasification method according to claim 1, wherein the large diameter particles and the small diameter particles are made of the same material, and the weight ratio of the large diameter particles to the small diameter particles is 9:1 to 5:

5.

4. The pyrolysis gasification method according to claim 1 , wherein the small-diameter particles are latent heat storage microcapsules.

5. A pyrolysis gasification method for pyrolyzing a feedstock, comprising: Pyrolyzing the raw material in a pyrolysis furnace using heat from a fluidized medium consisting of a mixture of large particles and small particles with different average particle sizes; While fluidizing the bed material, the residue of the raw material is combusted in a bed material regeneration furnace; collecting the small diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a first solid-gas separator; Returning the small-diameter particles collected by the first solid-gas separator to the media regeneration furnace through a first particle return line; The small diameter particles contained in the combustion exhaust gas discharged from the medium regeneration furnace are collected by a second solid-gas separator; the small-diameter particles collected by the second solid-gas separator are returned to the pyrolysis furnace through a second particle return line.

6. The large particles have an average particle size in the range of 300 μm to 600 μm, 6. The pyrolysis gasification method according to claim 5, wherein the small particles have an average particle size in the range of 20 μm to 40 μm.

7. 6. The pyrolysis gasification method according to claim 5, wherein the large diameter particles and the small diameter particles are made of the same material, and the weight ratio of the large diameter particles to the small diameter particles is 9:1 to 5:

5.

8. The pyrolysis gasification method according to claim 5 , wherein the small-diameter particles are latent heat storage microcapsules.

9. A pyrolysis gasification method for pyrolyzing a feedstock, comprising: Pyrolyzing the raw material in a pyrolysis furnace using heat from a fluidized medium consisting of a mixture of large particles and small particles with different average particle sizes; While fluidizing the bed material, the residue of the raw material is combusted in a bed material regeneration furnace; transferring the fluidized medium from the medium regeneration furnace to the pyrolysis chamber through a medium settling chamber; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator; The pyrolysis gasification method, wherein the small-diameter particles collected by the solid-gas separator are returned to the media settling chamber through a particle return line.

10. The large particles have an average particle size in the range of 300 μm to 600 μm, 10. The pyrolysis gasification method according to claim 9, wherein the small particles have an average particle size in the range of 20 μm to 40 μm.

11. 10. The pyrolysis gasification method according to claim 9, wherein the large diameter particles and the small diameter particles are made of the same material, and the weight ratio of the large diameter particles to the small diameter particles is 9:1 to 5:

5.

12. The pyrolysis gasification method according to claim 9 , wherein the small-diameter particles are latent heat storage microcapsules.

13. A pyrolysis gasification method for pyrolyzing a feedstock, comprising: Pyrolyzing the raw material in a pyrolysis furnace using heat from a fluidized medium consisting of a mixture of large particles and small particles with different average particle sizes; collecting the small-diameter particles contained in the pyrolysis gas discharged from the pyrolysis furnace using a solid-gas separator; The small particles collected by the solid-gas separator are returned to the pyrolysis furnace through a particle return line; A pyrolysis gasification method, wherein the particle return line extends through the interior of the media regeneration furnace to the pyrolysis furnace, and the small-diameter particles in the particle return line are heated by combustion of the raw material residue in the media regeneration furnace.

14. The large particles have an average particle size in the range of 300 μm to 600 μm, 14. The pyrolysis gasification method according to claim 13, wherein the small particles have an average particle size in the range of 20 μm to 40 μm.

15. 14. The pyrolysis gasification method according to claim 13, wherein the large diameter particles and the small diameter particles are made of the same material, and the weight ratio of the large diameter particles to the small diameter particles is 9:1 to 5:

5.

16. The pyrolysis gasification method according to claim 13, wherein the small-diameter particles are latent heat storage microcapsules.

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