Fluidized bed gasification self-circulation system combining cold wall and hot wall

Abstract

The present application relates to a kind of cold hot wall combination's fluidized bed gasification self-circulation system of coal, biomass, garbage and other carbon-containing substance gasification technical field, comprising: semi-water cold wall gasification furnace, front gas pipe, adiabatic high-temperature cyclone separator, rear gas pipe, waste heat recovery boiler, adiabatic return pipe, material seal valve.Reaction material is after completing gasification reaction in the dense phase adiabatic reaction section of semi-water cold wall gasification furnace into dilute phase radiation heat recovery section, high-temperature dust-containing crude coal gas produced by reaction carries out preliminary cooling and carries out heat recovery in this section, while dust carries out settlement separation in this space.After preliminary cooling and dust settlement, high-temperature dust-containing crude coal gas is removed after large particle dust by adiabatic high-temperature cyclone separator, then enters waste heat recovery boiler by rear gas pipe to carry out further heat recovery and cooling, dust particle captured by cyclone separator enters material seal valve by adiabatic return pipe, and then, rely on the pressure generated by material level height difference and send into gasification furnace to carry out reaction again.

Description

Technical Field

[0001] This invention relates to the field of gasification technology for carbonaceous materials such as coal, biomass, and waste. Background Technology

[0002] Currently, all core reaction equipment in domestically operating fluidized bed gasification technology is of the hot-wall type. This type of structure consists of a steel shell lined with a refractory insulation layer to ensure the pressure-bearing metal shell does not overheat, thus guaranteeing equipment safety. However, this type of structure has the following drawbacks: First, it results in significant heat loss from the furnace wall, leading to energy inefficiency. To prevent dew point corrosion of the furnace wall under a certain pressure, the working wall temperature of the pressure-bearing metal shell must be increased. For example, at a gasification pressure of 4.0 MPa, the minimum required metal working wall temperature is above 200°C. Second, it is uneconomical. The higher the design temperature of the pressure-bearing metal wall, the lower the strength of the metal material. Under the same pressure, diameter, and material conditions, a thicker metal layer is required. Third, maintenance costs are high. After a period of service, the chemical composition and microstructure of the refractory material change, increasing its thermal conductivity and decreasing its insulation performance. Therefore, the entire refractory material must be replaced. Typically, the cost of furnace construction is comparable to, or even slightly higher than, the manufacturing cost of the equipment metal. Fourth, there are uncertain safety risks. The reliability of the refractory lining depends too much on the construction quality. The construction of the lining structure is inevitably subject to space constraints, making it impossible to achieve uniform quality. In other words, during operation, the refractory lining may suddenly crack in a certain part of the equipment, and in severe cases, a large area may fall off, causing local overheating and strength failure of the equipment, which is difficult to predict.

[0003] Chinese Patent Publication No. CN 218058906 U, published on December 16, 2022, is an invention patent entitled "Water-Cooled Wall Pressurized Fluidized Bed Gasifier." This patent discloses a water-cooled wall pressurized fluidized bed gasifier, in which the lower part of the gasifier, the dense phase reaction section, adopts a water-cooled wall structure. This structure poses certain safety risks. Within the reaction section, a large number of material particles are in a fluidized boiling state, while a large amount of high-speed gas is ejected from the central tube. As the gas overcomes the resistance of the reaction section bed, it continuously accumulates, grows, and ruptures during its ascent, creating vibrations. This vibrations cause the membrane water-cooled wall of the reaction section to vibrate as well. Since the water-cooled wall is fixed inside the gasifier by suspension or a few supports, the force generated by these vibrations cannot be transmitted to the outside and is borne by the water-cooled wall structure. Ultimately, this leads to fatigue and cracking failure at the weak points in the metal of the water-cooled wall. Summary of the Invention

[0004] This invention addresses the shortcomings of current technologies by reducing furnace wall heat loss, reducing total equipment tonnage, lowering subsequent equipment maintenance costs, and reducing the probability of risks. It provides a more energy-efficient, low-investment, low-maintenance, and safer and more reliable fluidized bed gasification self-circulation system that combines hot and cold walls.

[0005] The technical solution adopted in this invention is as follows:

[0006] A fluidized bed gasification self-circulation system combining hot and cold walls includes: a semi-water-cooled wall gasifier, a front-end gas delivery pipe, an insulated high-temperature cyclone separator, a rear-end gas delivery pipe, a waste heat recovery boiler, an insulated return pipe, and a material sealing valve. The high-temperature, dust-laden crude gas generated by the semi-water-cooled wall gasifier passes through the front-end gas delivery pipe, then through the insulated high-temperature cyclone separator to remove large dust particles, and finally through the rear-end gas delivery pipe into the waste heat recovery boiler for further heat recovery and cooling. Dust particles collected by the cyclone separator enter the material sealing valve through the insulated return pipe and are then fed back into the gasifier by the pressure generated by the material level difference for further reaction.

[0007] A further improvement is made to the semi-water-cooled wall gasifier, comprising: a dense-phase adiabatic reaction section, a dilute-phase radiative heat recovery section, and a steam chamber. The dense-phase adiabatic reaction section consists of a pressure-bearing steel shell lined with refractory material, where the reactants undergo a fluidized boiling reaction after being piled to a certain height. The dilute-phase radiative heat recovery section is composed of a water-cooled wall cylinder concentrically installed with a pressure-bearing steel shell and steel pipes, where the high-temperature, dust-laden crude gas generated in the dense-phase adiabatic reaction section undergoes preliminary heat recovery and dust settling separation. The steam chamber is located at the bottom of the gasifier and provides the gasifying agent required for the reaction.

[0008] A further improvement is made to the dense-phase adiabatic reaction section, which includes: a hot-walled cylinder, a feed inlet for the reactants, and a return inlet for dust collection by a cyclone separator. The hot-walled cylinder is composed of a pressure-bearing steel shell lined with refractory material; the feed inlet's axis forms an angle of 35° to 75° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section, near the bottom; the return inlet's axis forms an angle of 30-60° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section, near the bottom.

[0009] A further improvement is made to the dilute phase radiative heat recovery section, which includes: an enlarged section water-cooled wall located above the transition section water-cooled wall; an expansion joint connecting and sealing the transition section water-cooled wall and the enlarged section water-cooled wall; an intermediate fixed support for supporting the enlarged section water-cooled wall; displacement guide frames arranged uniformly along different heights and circumferentially; a protective gas ring pipe installed in the annular cavity between the water-cooled wall and the pressure-bearing steel shell; a sealing ring for preventing high-temperature crude gas from entering the annular cavity and for supporting the transition section water-cooled wall; and water-cooled wall ash removal vibrators arranged uniformly along different heights and circumferentially.

[0010] A further improvement is made to the gas chamber, which includes: a gas distribution plate for supporting the reactants, a gasifying agent inlet, and a slag-falling annular cavity formed by a central pipe providing an oxygen channel and a slag-falling pipe concentrically installed.

[0011] A further improvement is made to the front-end gas delivery pipe, which is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell and a steel pipe, concentrically installed. It includes a lower vertical gas delivery pipe water-cooled wall and an upper vertical gas delivery pipe water-cooled wall connected by an expansion joint. The bottom end of the lower vertical gas delivery pipe water-cooled wall is inserted into the conical or circular constriction at the upper part of the water-cooled wall of the gasifier expansion section. The amount of protective gas passing through is adjusted by controlling the size of the gap ring formed by the two sections, maintaining a stable pressure difference between the ring cavity and the inner cavity enclosed by the water-cooled wall. The lower and upper vertical sections... The water-cooled wall of the gas pipeline is supported by a fixed support connected to the steel shell; a guide frame is used to limit the displacement direction of the water-cooled wall; a sealing expansion joint is used to prevent high-temperature crude gas from entering the annular cavity and also has a displacement compensation function; a soot blower is used to purge the ash accumulated at the bottom of the water-cooled wall of the horizontal gas pipeline; a flexible sealing partition is used to isolate the protective gas in the annular cavity from the water-cooled wall of the semi-water-cooled gasifier and the steel shell of the gasifier, limiting the volume of the protective gas in the annular cavity, which is beneficial for differential pressure control; and a protective gas inlet for the annular cavity is set near the flexible sealing partition.

[0012] A further improvement is made to the insulated high-temperature cyclone separator, which consists of a pressure-bearing steel shell with a high-temperature wear-resistant lining and a water-cooled wall center cylinder. The water-cooled wall center cylinder is formed by spirally winding 1 to 4 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel. The surface in contact with the dust-containing crude coal gas is coated with a wear-resistant layer with a thickness of 10-50mm that is resistant to high temperature and has a high thermal conductivity. The bottom of the water-cooled wall center cylinder is 50-150mm lower than the lower edge of the gas inlet of the cyclone separator.

[0013] A further improvement is made to the rear gas transmission pipe, which is concentrically assembled from a pressure-bearing steel shell cylinder and a water-cooled wall cylinder formed by steel pipes. This includes: an upward vertical gas transmission pipe water-cooled wall, a horizontal front section gas transmission pipe water-cooled wall and a horizontal rear section gas transmission pipe water-cooled wall connected by expansion joints, a downward vertical gas transmission pipe water-cooled wall, and a protective gas inlet. The upward vertical gas transmission pipe water-cooled wall can be integrated with the central water-cooled wall pipe or segmented and connected by expansion joints. At the bottom of the upward vertical gas transmission pipe water-cooled wall, a sealing expansion joint with displacement compensation function is installed to prevent high-temperature crude gas from entering the annular cavity. A soot blower is installed at the bottom of the horizontal section gas transmission pipe for purging ash accumulated at the bottom of the water-cooled wall. The protective gas inlet is located near the sealing expansion joint.

[0014] A further improvement is that, in the waste heat recovery boiler, the crude gas outlet is located on the upper side of the lower cone of the waste heat recovery boiler, and an ash discharge port is provided at the bottom of the cone.

[0015] A further improvement is that the insulated return pipe has a high-temperature wear-resistant lining inside the pressure-bearing steel shell, providing a conveying channel for the particulate matter collected by the cyclone, while not reducing the initial temperature of the particulate matter entering the furnace for reaction.

[0016] A further improvement is made to the aforementioned material sealing valve, which has a high-temperature wear-resistant lining inside a pressure-bearing steel shell and consists of a vertical section and two parallel inclined sections. The axis of the inclined section makes an angle of 30-60° with the horizontal; the two sides of the inclined section are respectively connected to the lower end of the return pipe and the return port of the gasifier.

[0017] The beneficial effects of this invention are:

[0018] The dilute phase section and gas transmission pipe section of the gasifier adopt a water-cooled wall radiant heat absorption structure, which can replace the evaporation section of the waste heat recovery boiler. Although this increases the investment cost of the gasifier to some extent, it significantly reduces the investment cost of the waste heat boiler and the subsequent maintenance cost of refractory materials in terms of overall system investment. In terms of process performance, the significantly reduced temperature of the high-temperature dust-laden gas entering the cyclone separator improves cyclone separation efficiency and reduces the structural size of the cyclone separator, thus reducing the load on the subsequent dust removal system and lowering investment. This invention is an energy-saving, low-investment, low-maintenance, and low-risk fluidized bed gasification system. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 This is a schematic diagram of a fluidized bed gasification self-circulation system that combines hot and cold walls. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0022] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Example

[0026] like Figure 1 As shown, this invention provides a fluidized bed gasification self-circulation system combining hot and cold walls, comprising: a semi-water-cooled wall gasifier 001, a front-end gas delivery pipe 002, an insulated high-temperature cyclone separator 003, a rear-end gas delivery pipe 004, a waste heat recovery boiler 005, an insulated return material pipe 006, and a material sealing valve 007. The high-temperature, dust-laden crude gas generated by the semi-water-cooled wall gasifier 001 passes through the front-end gas delivery pipe 002, then passes through the insulated high-temperature cyclone separator 003 to remove large dust particles, and then enters the waste heat recovery boiler 005 through the rear-end gas delivery pipe 004 for further heat recovery and cooling. The dust particles collected by the cyclone separator enter the material sealing valve 007 through the insulated return material pipe 006, and are then fed back into the gasifier for further reaction based on the pressure generated by the material level difference.

[0027] The semi-water-cooled wall gasifier 001 mainly consists of a dense-phase adiabatic reaction section 011, a dilute-phase radiative heat recovery section 012, and a steam chamber 013. The dense-phase adiabatic reaction section 011 is composed of a pressure-bearing steel shell lined with refractory material. After the reactants are piled to a certain height, a fluidized boiling reaction occurs in this section. The dilute-phase radiative heat recovery section 012 is composed of a water-cooled wall cylinder concentrically installed with a pressure-bearing steel shell and steel pipes. The high-temperature, dust-laden crude gas generated in the dense-phase adiabatic reaction section 011 undergoes preliminary heat recovery and dust settling separation in this section. The steam chamber 013 is located at the bottom of the gasifier and provides the gasifying agent required for the reaction.

[0028] like Figure 1As shown, the dense-phase adiabatic reaction section 011 includes: a hot-wall cylinder 113, a feed inlet 111 for the reactants, and a return inlet 112 for dust collection by a cyclone separator. The hot-wall cylinder 113 is composed of a pressure-bearing steel shell lined with refractory material; the axis of the feed inlet 111 forms an angle of 35° to 75° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section near the bottom; the axis of the return inlet 112 forms an angle of 30-60° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section 011 near the bottom.

[0029] like Figure 1 As shown, the further improvement is that the dilute phase radiative heat recovery section 012 includes: an enlarged section water-cooled wall 122 located above the transition section water-cooled wall 121; an expansion joint 123 connecting and sealing the transition section water-cooled wall and the enlarged section water-cooled wall; an intermediate fixed support 124 for supporting the enlarged section water-cooled wall; a displacement guide frame 125 evenly arranged circumferentially at different heights; a protective gas ring pipe 126 set in the annular cavity between the water-cooled wall and the pressure-bearing steel shell; a sealing ring 127 for isolating high-temperature crude coal gas from entering the annular cavity and supporting the transition section water-cooled wall; and water-cooled wall ash removal vibrators 128 evenly arranged circumferentially at different heights.

[0030] A further improvement is that the transition section water-cooled wall 121 is formed by spirally winding 1-8 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by combining them; the diameter of the large end cylinder formed by the transition section water-cooled wall is 1.2 to 1.6 times the diameter of the small end cylinder, and the cone angle is 30°-60°.

[0031] A further improvement is that the enlarged section water-cooled wall 122 is formed by spirally winding 1-8 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by combining them; the upper part has a conical or circular opening to form a gas outlet channel, and the diameter of the lower water-cooled wall forming a cylinder can be greater than, less than or equal to the diameter of the large end cylinder formed by the transition section water-cooled wall.

[0032] A further improvement is that the protective gas ring pipe 126 is connected to the pressure-bearing steel shell by a semi-circular annular steel pipe. Protective gas distribution holes are equidistantly spaced along the circumference of the ring pipe, and the ring pipe is positioned close to the sealing ring that prevents high-temperature crude coal gas from entering the annular cavity. The protective gas in the annular cavity is an inert gas, or it can be a purified synthetic gas. The pressure of the protective gas is slightly higher than the internal pressure of the dilute phase radiative heat recovery section, achieving positive pressure sealing. If an inert gas is used as the protective gas, a room-temperature gas can be used to keep the pressure-bearing shell in a cold-wall state.

[0033] like Figure 1 As shown, the vapor chamber 013 includes: a gas distribution plate 131 for supporting the reactants, a gasifying agent inlet 132, and a slag discharge ring cavity 135 formed by a central pipe 134 providing an oxygen channel and a slag discharge pipe 133 concentrically installed.

[0034] A further improvement is that the gas distribution plate 131 is a conical gas distribution plate formed by rolling steel plate, with a cone angle in the range of 60°-120°. Small holes for passing through the gasifying agent are opened at equal intervals on the distribution plate, and the angle between the axis of the small hole and the axis of the cone of the distribution plate is in the range of 30°-60°. A high-temperature wear-resistant heat insulation layer with a thickness of 20mm-100mm can be applied to the surface of the distribution plate in contact with the reactants.

[0035] like Figure 1 As shown, the front section gas transmission pipe 002 is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell and a steel pipe, which are concentrically installed. It includes a lower section vertical gas transmission pipe water-cooled wall 021 and an upper section vertical gas transmission pipe water-cooled wall 022 connected by an expansion joint. The bottom end of the lower section vertical gas transmission pipe water-cooled wall 021 is inserted into the conical or circular constriction at the upper part of the gasifier expansion section water-cooled wall 122. The amount of protective gas passing through is adjusted by controlling the size of the gap ring formed by the two sections, maintaining a stable pressure difference between the ring cavity and the inner cavity enclosed by the water-cooled wall. The lower and upper sections of the vertical gas transmission pipe are water-cooled... The wall is supported by a fixed support 029 connected to the steel shell; a guide frame 024 is used to limit the displacement direction of the water-cooled wall; a sealing expansion joint 025 is used to isolate high-temperature crude gas from entering the annular cavity and also has a displacement compensation function; a soot blower 026 is used to purge the ash accumulated at the bottom of the water-cooled wall 023 of the horizontal gas transmission pipe; a flexible sealing partition 028 is used to isolate the protective gas in the annular cavity from the water-cooled wall of the semi-water-cooled gasifier and the steel shell of the gasifier, limiting the volume of the protective gas in the annular cavity, which is beneficial to differential pressure control; and a protective gas inlet 027 for the annular cavity is set near the flexible sealing partition.

[0036] A further improvement is that the lower vertical gas transmission pipe water-cooled wall 021, the upper vertical gas transmission pipe water-cooled wall 022, and the horizontal gas transmission pipe water-cooled wall 023 are formed by spirally winding 1-6 sets of steel pipes, or they can be formed by bending steel pipes in parallel and connecting them with flat steel, or they can be combined. A wear-resistant layer with a thickness of 10-50mm is laid on the side of the water-cooled wall that is in contact with the high-temperature dusty crude gas.

[0037] like Figure 1 As shown, the insulated high-temperature cyclone separator 003 consists of a pressure-bearing steel shell with a high-temperature wear-resistant lining and a water-cooled wall central tube 031. The water-cooled wall central tube 031 is formed by spirally winding 1-4 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel. The surface of the side in contact with the dust-containing crude coal gas is coated with a wear-resistant layer with a thickness of 10-50mm that is resistant to high temperature and has a high thermal conductivity. The bottom of the water-cooled wall central tube 031 is 50-150mm lower than the lower edge of the gas inlet 032 of the cyclone separator.

[0038] like Figure 1As shown, the rear section gas transmission pipe 004 is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell and a steel pipe, which are concentrically installed. Its features include: an upward vertical gas transmission pipe water-cooled wall 041, a horizontal front section gas transmission pipe water-cooled wall 042 and a horizontal rear section gas transmission pipe water-cooled wall 043 connected by expansion joints, a downward vertical gas transmission pipe water-cooled wall 044, and a protective gas inlet 045. The upward vertical gas transmission pipe water-cooled wall 041 can be integrated with the water-cooled wall center pipe 031, or it can be segmented and connected by expansion joints. At the bottom of the upward vertical gas transmission pipe water-cooled wall, a sealing expansion joint 046 with displacement compensation function is provided to prevent high-temperature crude gas from entering the annular cavity. At the bottom of the horizontal section gas transmission pipe, a soot blower 047 is provided for blowing away ash accumulated at the bottom of the water-cooled wall. The protective gas inlet 045 is located near the sealing expansion joint.

[0039] A further improvement is that the upward vertical gas transmission pipe water-cooled wall 041, the horizontal front section gas transmission pipe water-cooled wall 042, the horizontal rear section gas transmission pipe water-cooled wall 043, and the downward vertical gas transmission pipe water-cooled wall 044 are formed by spirally winding 1 to 6 sets of steel pipes, or they can be formed by bending steel pipes in parallel and connecting them with flat steel, or they can be combined. A 10 to 50 mm high-temperature resistant and high thermal conductivity wear-resistant layer is laid on the side of the water-cooled wall that is in contact with the high-temperature dusty crude gas.

[0040] like Figure 1 As shown, the waste heat recovery boiler 005 has a crude gas outlet 051 located on the upper side of the lower cone of the waste heat recovery boiler, and an ash discharge port 052 located at the bottom of the cone.

[0041] like Figure 1 As shown, the pressure-bearing steel shell of the insulated return pipe 006 is lined with a high-temperature wear-resistant lining.

[0042] like Figure 1 As shown, the material sealing valve 007 has a high-temperature wear-resistant lining inside its pressure-bearing steel shell and consists of a vertical section and two parallel inclined sections. The angle between the axis of the inclined section and the horizontal is 30°-60°, preferably 45°; the two sides of the inclined section are respectively connected to the lower end of the insulated return pipe 006 and the gasifier return port 112.

[0043] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A fluidized bed gasification self-circulation system combining hot and cold walls, comprising: The system comprises a semi-water-cooled wall gasifier, a front-end gas delivery pipe, an insulated high-temperature cyclone separator, a rear-end gas delivery pipe, a waste heat recovery boiler, an insulated return pipe, and a material sealing valve. The high-temperature, dust-laden crude gas generated by the semi-water-cooled wall gasifier passes through the front-end gas delivery pipe, then passes through the insulated high-temperature cyclone separator to remove large dust particles before entering the waste heat recovery boiler through the rear-end gas delivery pipe for further heat recovery and cooling. Dust particles collected by the cyclone separator enter the material sealing valve through the insulated return pipe and are then fed back into the gasifier by the pressure generated by the material level difference for further reaction.

2. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 1, characterized in that, The semi-water-cooled wall gasifier, the front gas pipeline, and the rear gas pipeline all include water-cooled walls.

3. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 2, characterized in that, The water-cooled wall is formed by spirally winding 1-8 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or a combination of both.

4. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 2, characterized in that, The semi-water-cooled wall gasifier includes: a dense-phase adiabatic reaction section, a dilute-phase radiative heat recovery section, and a steam chamber; the dense-phase adiabatic reaction section is composed of a pressure-bearing steel shell lined with refractory material; the dilute-phase radiative heat recovery section is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell cylinder and steel pipes, which are concentrically installed; the steam chamber is located at the bottom of the gasifier.

5. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 4, characterized in that, The dense-phase adiabatic reaction section includes a hot-walled cylinder, a feed inlet for the reactants, and a return inlet for dust collection by a cyclone separator. The hot-walled cylinder is composed of a pressure-bearing steel shell lined with refractory material. The feed inlet's axis forms an angle of 35°-75° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section, near the bottom. The return inlet's axis forms an angle of 30-60° with the horizontal plane and is also located in the lower part of the dense-phase adiabatic reaction section, near the bottom.

6. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 4, characterized in that, The dilute phase radiative heat recovery section includes: an enlarged section water-cooled wall located above the transition section water-cooled wall; an expansion joint connecting and sealing the transition section water-cooled wall and the enlarged section water-cooled wall; an intermediate fixed support for supporting the enlarged section water-cooled wall; displacement guide frames arranged evenly along the circumference at different heights; a protective gas ring pipe installed in the annular cavity between the water-cooled wall and the pressure-bearing steel shell; a sealing ring used to prevent high-temperature crude gas from entering the annular cavity and also supporting the transition section water-cooled wall; and water-cooled wall ash removal vibrators arranged evenly along the circumference at different heights.

7. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 6, characterized in that, The diameter of the large-end cylinder formed by the water-cooled wall of the transition section is 1.2 to 1.6 times the diameter of the small-end cylinder, and the cone angle is 30°-60°.

8. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 6, characterized in that, The protective gas ring pipe is connected to a pressure-bearing steel shell cylinder by a semi-circular annular steel pipe. Protective gas distribution holes are opened at equal intervals along the circumference of the ring pipe. The ring pipe is located close to the sealing ring that prevents high-temperature crude coal gas from entering the ring cavity. The protective gas in the ring cavity is an inert gas or a purified synthetic gas. The pressure of the protective gas ring pipe is higher than the internal pressure of the dilute phase radiative heat recovery section.

9. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 4, characterized in that, The vapor chamber includes a gas distribution plate for supporting the reactants, a gasifying agent inlet, and a slag-falling ring cavity formed by a central pipe providing an oxygen channel and a slag-discharge pipe concentrically installed.

10. The fluidized bed gasification self-circulation system combining hot and cold walls according to claim 1, characterized in that, The pressure-bearing steel shell of the material sealing valve is lined with a high-temperature wear-resistant lining and consists of a vertical section and two parallel inclined sections. The axis of the inclined section makes an angle of 30-60 degrees with the horizontal. The two sides of the inclined section are connected to the lower end of the return pipe and the return port of the gasifier, respectively.

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