Bottom slag treatment device and bottom slag treatment method for fluidized bed gasifier

Abstract

The present invention provides a bottom ash treatment device (2) for a fluidized bed gasifier, the bottom ash treatment device (2) having a hot slag inlet and a cold slag outlet, the hot slag inlet is used to connect to the gasifier (1) to receive hot slag (D), the cold slag outlet is used to discharge cold slag (K), and the bottom ash treatment device (2) is configured to reburn and cool the hot slag (D). The present invention also provides a bottom ash treatment method for a fluidized bed gasifier. According to the bottom ash treatment device and bottom ash treatment method for a fluidized bed gasifier of the present invention, the bottom ash has a low carbon content, is not easy to slag, has high efficiency, and can save energy and reduce consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of gasification, and in particular to a bottom ash treatment device and a bottom ash treatment method for a fluidized bed gasifier. Background Art

[0002] As an efficient and clean clean coal technology, gasification technology is the main way to convert solid primary energy such as coal into gaseous clean secondary energy. This technology is mainly used in chemical and metallurgical industries such as synthetic ammonia, synthetic methanol, hydrogen production, blast furnace reduction ironmaking, combined cycle power generation, and industrial and civil gas fields.

[0003] According to the movement state of solid fuel, modern gasification processes mainly include fixed bed gasification, entrained bed gasification and fluidized bed gasification. Fluidized bed gasification technology is one of the earliest industrialized gasification processes. The process is to blow a gasifying agent with a certain pressure from the bottom of the bed through the air distribution plate to lift the broken coal on the bed. When the gasifying agent rises, the coal particles move in a suspended state, rolling up and down, and fully contacting with the gasifying agent to undergo a gasification reaction. This type of technology includes traditional fluidized bed gasification technology and circulating fluidized bed gasification technology developed in recent years.

[0004] At present, fluidized bed gasification technology has been industrialized and has achieved good environmental, economic and social benefits. However, from the operation of existing fluidized bed gasifiers, there are the following problems:

[0005] (1) The carbon content of the bottom ash is high, especially for coals with low reactivity, the carbon content of the bottom ash is ≥15%;

[0006] (2) The slag discharge system has low operational flexibility and is prone to slagging during the slag discharge process. Once slagging occurs, hot coal gas can easily escape from the slag discharge system, posing a serious safety hazard and affecting the long-term stable operation of the gasifier.

[0007] (3) The energy and water consumption of the cooling slag system is high, and the sensible heat of the hot slag (temperature greater than 900°C) cannot be fully recovered. Summary of the invention

[0008] The object of the present invention is to at least partially overcome the defects of the prior art and to provide a bottom ash treatment device and a bottom ash treatment method for a fluidized bed gasifier.

[0009] The present invention also aims to provide a bottom ash treatment device and a bottom ash treatment method for a fluidized bed gasifier, so as to solve the problem of high carbon content in the bottom ash of the existing fluidized bed gasifier and improve the cold gas efficiency.

[0010] The present invention also aims to provide a bottom ash treatment device and a bottom ash treatment method for a fluidized bed gasifier, so as to ensure smooth slag discharge of the fluidized bed gasifier, reduce potential safety hazards, and achieve long-term stable operation.

[0011] The present invention also aims to provide a bottom slag treatment device and a bottom slag treatment method for a fluidized bed gasifier, so as to solve the problem of slagging easily during the slagging process.

[0012] The present invention also aims to provide a bottom ash treatment device and a bottom ash treatment method for a fluidized bed gasifier, which can reasonably utilize the sensible heat of the hot slag to achieve the purpose of energy saving and consumption reduction.

[0013] To achieve the above purpose or one of the purposes, the technical solution of the present invention is as follows:

[0014] A bottom ash treatment device for a fluidized bed gasifier, the bottom ash treatment device having a hot slag inlet and a cold slag outlet, the hot slag inlet is used to connect to the gasifier to receive the hot slag, the cold slag outlet is used to discharge the cold slag, and the bottom ash treatment device is configured to reburn and cool the hot slag.

[0015] According to a preferred embodiment of the present invention, the bottom ash treatment device includes an oxidant inlet, a coolant inlet and a return gas outlet, the oxidant inlet is used to introduce the oxidant into the bottom ash treatment device, the coolant inlet is used to introduce the coolant into the bottom ash treatment device, and the return gas outlet is used to return the return gas to the gasification furnace.

[0016] According to a preferred embodiment of the present invention, the vertical position of the oxidant inlet is higher than that of the coolant inlet, and the vertical position of the return gas outlet is higher than that of the oxidant inlet.

[0017] According to a preferred embodiment of the present invention, the bottom ash processing device further comprises a sealing gas inlet for introducing sealing gas into the bottom ash processing device, and the sealing gas inlet is located vertically lower than the coolant inlet.

[0018] According to a preferred embodiment of the present invention, the bottom ash processing device includes a vertical extension section and an inclined section located above the vertical extension section, the inclined section is inclined toward one side of the vertical extension section relative to the longitudinal axis of the vertical extension section, wherein the inclined section is connected to the gasifier, and the lower end of the vertical extension section forms an inclined surface that is not perpendicular to the longitudinal axis of the vertical extension section.

[0019] According to a preferred embodiment of the present invention, the oxidant inlet is arranged on the inclined section, and the coolant inlet is arranged on the vertically extending section.

[0020] According to a preferred embodiment of the present invention, the bottom ash treatment device further comprises a gas collecting pipe, which is arranged inside the bottom ash treatment device and is connected to the return furnace gas outlet.

[0021] According to a preferred embodiment of the present invention, the bottom ash treatment device is of a substantially cylindrical structure, and the gas collecting pipe is arranged at the center of the bottom ash treatment device so that the central axis of the gas collecting pipe is coaxial with the central axis of the bottom ash treatment device.

[0022] According to a preferred embodiment of the present invention, the bottom ash processing device includes an upper tapered section, a lower tapered section and a barrel section between the upper tapered section and the lower tapered section, and the oxidant inlet, the coolant inlet and the sealing gas inlet are all arranged on the barrel section.

[0023] According to a preferred embodiment of the present invention, the bottom ash processing device further comprises an air lock, and the air lock is arranged at the bottom of the bottom ash processing device.

[0024] According to another aspect of the present invention, a bottom ash treatment method for a fluidized bed gasifier is provided. The bottom ash treatment method uses the bottom ash treatment device for a fluidized bed gasifier according to any one of the preceding claims.

[0025] In the bottom ash treatment device and bottom ash treatment method for a fluidized bed gasifier of the present invention, the hot slag of the gasifier can be sent to a bottom ash treatment (including reburning and cooling) device to react with an oxidant to generate hot flue gas rich in CO2 or rich in CO and H2, which effectively reduces the carbon content in the hot slag; at the same time, the reduction reaction of carbon in the bottom ash and the direct heat exchange between the coolant and the hot slag can effectively reduce the hot slag temperature; the bottom ash outlet pressure of the gasifier and the pressure of the bottom ash treatment device can be configured to effectively prevent the gasifying agent from being carried into the bottom In the slag treatment device or the bottom ash reburning unit, the existing slag discharge methods avoid slagging and gas cross-flow and other problems, eliminate the hidden dangers of operation safety, and ensure the long-term stable operation of the fluidized bed gasifier; the hot flue gas and the steam superheated by the hot slag or the steam generated by the cooling water heated by the hot slag are returned to the gasification unit to promote the gasification reaction and improve the cold gas efficiency of the system; in addition, the temperature of the hot slag can be reduced to below 100°C, and the equipment such as the slag cooler can be eliminated, and the hot slag can be directly transported by a conveyor belt, saving investment and operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a flow chart of a fluidized bed gasification system according to the present invention;

[0027] Figure 2 is a schematic structural diagram of a bottom ash treatment device for a fluidized bed gasifier according to an embodiment of the present invention; and

[0028] Figure 3 It is a schematic structural diagram of a bottom ash treatment device for a fluidized bed gasification furnace according to another embodiment of the present invention. DETAILED DESCRIPTION

[0029] Exemplary embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements. In addition, in the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the disclosed embodiments. However, it is apparent that one or more embodiments may also be implemented without these specific details. In other cases, known structures and devices are embodied in a schematic manner to simplify the accompanying drawings.

[0030] According to the overall concept of the present invention, there is provided a bottom ash treatment device for a fluidized bed gasifier, the bottom ash treatment device having a hot slag inlet and a cold slag outlet, the hot slag inlet being used to connect with the gasifier to receive the hot slag, the cold slag outlet being used to discharge the cold slag, and the bottom ash treatment device being configured to perform reburning and cooling treatment on the hot slag.

[0031] Figure 1 is a general schematic diagram of a fluidized bed gasification system according to the present invention, as shown in Figure 1 As shown, the fluidized bed gasification system includes a gasifier 1 and a bottom ash treatment device 2. The gasifier 1 includes a fuel inlet, a gasifying agent inlet, a coal gas and fly ash outlet, a hot slag outlet and a return gas inlet, wherein the fuel inlet is used to introduce fuel A (such as coal) into the gasifier 1, the gasifying agent inlet is used to introduce the gasifying agent into the gasifier 1, the coal gas and fly ash C generated by the gasifier 1 are led out from the coal gas and fly ash outlet, the hot slag outlet is used to lead out the hot slag D, and the return gas inlet is used to connect with the return gas outlet described below to receive the return gas E.

[0032] The bottom ash treatment device 2 is provided with a hot slag inlet, a cold slag outlet, an oxidant inlet, a coolant inlet, a sealing gas inlet and a return gas outlet. Among them, the hot slag inlet is directly or indirectly connected to the bottom ash outlet of the gasifier 1 to receive the hot slag D; the cold slag outlet is used to discharge the cold slag K; the oxidant inlet is used to pass the oxidant F into the bottom ash treatment device 2, and the coolant inlet is used to pass the coolant G into the bottom ash treatment device 2; the sealing gas inlet is used to pass the sealing gas H into the bottom ash treatment device 2; the return gas outlet is directly or indirectly connected to the return gas inlet of the gasifier 1 (or gasification unit) to return the return gas E to the gasifier 1.

[0033] By providing an oxidant inlet and a coolant inlet, an oxidant F and a coolant G can be introduced into the bottom ash treatment device 2 to perform reburning and cooling treatment on the hot slag D. Figure 1The working process of the fluidized bed gasification system according to the present invention is described. Specifically, the working process of the fluidized bed gasification system includes the following steps:

[0034] a) Fuel (coal as an example) A and gasifying agent B are introduced into a gasifier 1 for gasification to generate coal gas, fly ash C and hot slag D; the coal gas and fly ash C leave the system; the hot slag D discharged from the bottom of the furnace of the gasifier 1 enters the bottom slag treatment device 2;

[0035] b) introducing the oxidant F and the coolant G into the bottom slag treatment device 2, the hot slag D reacts with the oxidant F to generate hot flue gas; the coolant G and the hot slag D are directly contacted for heat exchange, so that the temperature of the hot slag is reduced to the allowable temperature for slag transport, and cold slag K is formed;

[0036] c) The hot flue gas generated by the reaction of the oxidant F and the hot slag D and the coolant G after absorbing heat are returned to the gasifier 1 as return gas E;

[0037] d) The generated cold slag K leaves the system.

[0038] Wherein, the hot slag D in step a) is a solid slag discharge product with a temperature in the range of 800°C-1300°C; the oxidant F in step b) is air, oxygen-enriched air or pure oxygen, or a combination of one of the above three and water vapor; the maximum reaction temperature of the hot slag D and the oxidant F in step b) can be adjusted to be 150°C lower than the softening temperature of the fuel A by adjusting the oxygen content or steam content in the oxidant F, so as to avoid fuel slagging and ensure smooth solid slag discharge. For example, by reducing the oxygen content of the oxidant F, the heat released by the combustion of the hot slag is less, and the reaction temperature of the hot slag D and the oxidant F is reduced, so that it is not easy to slag.

[0039] Furthermore, the hot flue gas in step b) can be made into a gas rich in CO2 or rich in CO and H2 by adjusting the feeding amount of the oxidant F. The coolant G in step b) is water or water vapor.

[0040] In step b), a sealing gas H may be introduced into the bottom ash treatment device 2. While playing a sealing role, the sealing gas H and the coolant G work together to reduce the temperature of the hot slag D to the allowable temperature for slag transport; at the same time, the sealing gas H is also returned to the gasifier 1 as part of the return gas E. The sealing gas H is an inert gas such as CO2 or nitrogen. The feeding amount of the sealing gas H is a function of the amount of hot slag and the structural size of the bottom ash treatment device.

[0041] Preferably, in the step a), the pressure P0 at the bottom ash outlet of the gasifier 1 is lower than the pressure P1 in the bottom ash processing device 2 to avoid gas leakage.

[0042] Figure 2FIG. 1 is a schematic structural diagram of a bottom ash treatment device for a fluidized bed gasifier according to an embodiment of the present invention. Figure 2 As shown, the gasifier 1 is provided with a fuel inlet, a gasifying agent inlet, and a coal gas and fly ash outlet. It should be noted that the gasifier 1 also includes a return gas inlet, which can be arranged above the gasifying agent inlet of the gasifier 1, because the return gas E after combustion and heat exchange in the bottom ash treatment device 2 has a higher temperature and can directly participate in the reaction in the gasifier 1.

[0043] exist Figure 2 In the embodiment, the bottom ash treatment device 2 includes a vertical extension section and an inclined section located above the vertical extension section, wherein the inclined section is inclined toward one side of the vertical extension section relative to the longitudinal axis of the vertical extension section, wherein the inclined section is connected to the gasifier 1, and the lower end of the vertical extension section forms an inclined surface that is not perpendicular to the longitudinal axis of the vertical extension section. The oxidant inlet and the return gas outlet are arranged on the inclined section, the return gas outlet is higher than the oxidant inlet, and the coolant inlet is arranged on the vertical extension section. In this way, the position of the oxidant inlet in the vertical direction is higher than the position of the coolant inlet in the vertical direction, and the position of the return gas outlet in the vertical direction is higher than the position of the oxidant inlet in the vertical direction. In this way, the hot slag first contacts the oxidant and then contacts the coolant during the falling process, rather than the other way around, which ensures that the hot slag reacts with the oxidant at a higher temperature, which is conducive to the reaction.

[0044] The oxidant inlet and the coolant inlet may include a plurality of inlets, respectively. Preferably, the plurality of oxidant inlets are evenly arranged in the circumferential direction, and the plurality of coolant inlets are evenly arranged in the circumferential direction. Preferably, the oxidant inlet is configured as a plurality of oxidant inlets arranged in multiple rows, and the oxidant inlets in any row of oxidant inlets are staggered with the oxidant inlets in the adjacent row of oxidant inlets, and the coolant inlet is configured as a plurality of coolant inlets arranged in multiple rows, and the coolant inlets in any row of coolant inlets are staggered with the coolant inlets in the adjacent row of coolant inlets.

[0045] exist Figure 2 In the embodiment of the present invention, the bottom slag processing device 2 further comprises an air lock 22, which is arranged at the bottom of the bottom slag processing device 2. The air lock 22 is used to control the slag discharge while preventing the gas from escaping from the cold slag outlet. During the working process, the air lock 22 can seal the cold slag outlet, lock the gas, and prevent gas leakage.

[0046] The air lock 22 can be constructed as a valve, and the valve is opened when the slag is discharged. Alternatively, the air lock 22 includes an inlet, a first chamber, a second chamber, an intermediate chamber and an outlet, the intermediate chamber is between the first chamber and the second chamber, the inlet is arranged on the first chamber, the outlet is arranged on the second chamber, the first valve is arranged between the first chamber and the intermediate chamber, and the second valve is arranged between the intermediate chamber and the second chamber. When working, the second valve can be closed and the first valve can be opened, so that the bottom slag discharged from the cold slag outlet directly enters the intermediate chamber through the inlet and the first chamber, and when the bottom slag in the intermediate chamber accumulates to a certain extent, the first valve is closed and the second valve is opened, so that the bottom slag can enter the second chamber and can be discharged from the outlet connected to the second chamber, and after the bottom slag in the intermediate chamber is emptied, the second valve is closed and the first valve is opened. In this way, gas leakage can be avoided.

[0047] According to the fluidized bed gasification system of this embodiment, fuel (coal as an example) A and gasifying agent B are introduced into the gasifier 1 for gasification to generate coal gas, fly ash C and hot slag D; the coal gas and fly ash C leave the system, and the hot slag D discharged from the bottom of the furnace of the gasifier 1 enters the bottom slag processing device 2, and first undergoes a gasification reaction with the oxidant F to generate hot flue gas rich in CO and H2 and hot slag with low carbon content. The hot slag with low carbon content is then cooled to below 100°C by the coolant G to form cold slag K, and the coolant F is heated (or overheated) to high-temperature steam. The hot flue gas and high-temperature steam return to the gasifier 1 from the middle of the furnace of the gasifier as return gas E to participate in the gasification reaction, and the cold slag K leaves the system after passing through the air lock 22 of the bottom slag material device 2.

[0048] Figure 3 FIG. 1 is a schematic structural diagram of a bottom ash treatment device for a fluidized bed gasifier according to an embodiment of the present invention. Figure 3 As shown, the gasifier 1 and Figure 2 The embodiments shown are substantially the same. Figure 3 In the embodiment of the present invention, the bottom ash treatment device 2 is a substantially cylindrical structure, including an upper tapered section, a lower tapered section, and a barrel section between the upper tapered section and the lower tapered section. The barrel section of the bottom ash treatment device 2 has an equivalent diameter smaller than that of the gasifier 1. Here, the equivalent diameter refers to the diameter of a cylinder or the diameter of a cylinder having the same hydraulic radius as a non-cylindrical body. Therefore, in the case of a non-circular or non-cylindrical body, the diameters mentioned herein all refer to equivalent diameters.

[0049] The bottom ash treatment device 2 also includes a sealed gas inlet, and the oxidant inlet, coolant inlet and sealed gas inlet are all arranged on the barrel section. Among them, the vertical position of the oxidant inlet is higher than the vertical position of the coolant inlet, the vertical position of the sealed gas inlet is lower than the vertical position of the coolant inlet, and the vertical position of the return gas outlet is higher than the vertical position of the oxidant inlet. In this way, the hot slag first contacts the oxidant and then contacts the coolant during the falling process, rather than the other way around, which ensures that the hot slag reacts with the oxidant at a higher temperature, which is beneficial to the reaction; at the same time, it can ensure that the gas will not leak from the bottom.

[0050] The sealing gas inlet may be multiple, and the multiple sealing gas inlets are evenly arranged along the circumferential direction of the barrel section. Alternatively, the multiple sealing gas inlets may not be arranged on the barrel section, but on the inclined circumferential surface of the lower tapered section, and the multiple sealing gas inlets are evenly arranged along the circumferential direction of the lower tapered section, so as to blow the sealing gas at an angle relative to the central axis of the barrel section, which is beneficial to sealing. The sealing gas inlet may also be constructed as an inlet ring that is continuous in the circumferential direction, so as to facilitate the uniform blowing of the sealing gas.

[0051] The bottom ash processing device 2 also includes a gas collecting pipe 21, which is arranged inside the bottom ash processing device 2 and is connected to the return furnace gas outlet. The gas collecting pipe 21 is arranged at the center of the bottom ash processing device 2 so that the central axis of the gas collecting pipe 21 is coaxial with the central axis of the bottom ash processing device 2.

[0052] The gas collecting pipe 21 can be constructed in the form of a row of pipes or a circular pipe group. For example, the gas collecting pipe 21 is a row of pipes, which includes three rows of pipes, which intersect each other so that the row of pipes is in a "M" shape along a cross section perpendicular to the longitudinal axis, or the row of pipes includes two rows of pipes, which intersect each other so that the row of pipes is in a "X" shape along a cross section perpendicular to the longitudinal axis. Alternatively, the gas collecting pipe 21 can be a circular pipe group, which is formed by combining multiple circular pipes in close proximity to form a circle.

[0053] The bottom surface of the gas collecting pipe 21 is open, and a plurality of through holes may be provided on the outer peripheral surface of the gas collecting pipe 21, so that the gas can enter the gas collecting pipe through the bottom surface opening and the through holes and be guided to the return gas outlet.

[0054] Alternatively, the return gas outlet may be arranged on the upper tapered section, which is also conducive to the discharge of the return gas E.

[0055] According to the fluidized bed gasification device of this embodiment, the fuel (coal as an example) A and the gasifying agent B are introduced into the gasifier 1 for gasification to generate coal gas, fly ash C and hot slag D; the coal gas and fly ash C leave the system, and the hot slag D discharged from the bottom of the furnace of the gasifier 1 enters the bottom ash treatment device 2. In the case of low carbon content in the bottom ash, the hot slag D in the bottom ash treatment device 2 undergoes combustion reaction with the oxidant F to generate hot flue gas rich in CO2 and hot slag with low carbon content, and the hot slag with low carbon content is then cooled to below 200°C by the coolant G to form cold slag K, while the coolant F is heated (or overheated) to high-temperature steam. The hot flue gas and high-temperature steam are collected and guided upward by the gas collecting pipe 21 placed in the bottom ash treatment device 2, and returned to the gasifier 1 as return gas E to participate in the gasification reaction, and the cold slag K enters the pressurized lock hopper through the low-temperature valve and is discharged through the lock hopper.

[0056] exist Figure 3 In the embodiment shown, the return gas E first enters the gas collecting pipe disposed inside the bottom ash treatment device, is collected, and then guided out and returned to the gasifier. The return gas can return to the gasifier from the bottom of the gasifier furnace or other positions of the gasifier (such as the upper part of the furnace, the return feeder, etc.).

[0057] According to another aspect of the present invention, a bottom ash treatment method for a fluidized bed gasifier is provided. The bottom ash treatment method uses the bottom ash treatment device for a fluidized bed gasifier according to any one of the preceding claims.

[0058] The bottom ash treatment device and bottom ash treatment method for a fluidized bed gasifier provided by the present invention have the following advantages compared with the prior art:

[0059] (1) The carbon content in the bottom ash is reduced by reburning the bottom ash; the return gas is returned to the gasifier to participate in the gasification reaction, effectively improving the system carbon conversion rate and cold gas efficiency;

[0060] (2) Make full use of the sensible heat of the bottom ash to produce steam or superheat the steam to improve system efficiency;

[0061] (3) Make full use of the sensible heat of the bottom ash to preheat the gasifying agent entering the gasifier to improve system efficiency;

[0062] (4) The pressure of the bottom ash treatment device is higher than the pressure at the bottom ash outlet of the gasifier, which effectively prevents the gasifier gasifier from being carried into the bottom ash treatment device, avoids the problems of slagging and gas blowby in the existing slag discharge method, eliminates the hidden dangers of operation safety, and ensures the long-term stable operation of the fluidized bed gasifier;

[0063] (5) When the temperature of the hot slag is reduced to below 100°C, equipment such as slag coolers can be eliminated, saving investment and operation and maintenance costs;

[0064] (6) In the pressurized gasification process, the hot slag is cooled and then discharged through the lock bucket, which can greatly reduce the material grade of the lock bucket valve and improve the reliability of the system.

[0065] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of application of the present invention is defined by the appended claims and their equivalents.

[0066] List of reference numerals:

[0067] 1 Gasifier

[0068] 2 Bottom slag treatment device

[0069] 21 Gas collector

[0070] 22 Air lock

[0071] A. Fuel

[0072] B Gasifier

[0073] C Gas and fly ash

[0074] D Hot slag

[0075] E Return gas

[0076] F Oxidants

[0077] G Coolant

[0078] H Sealing gas

[0079] K Cold slag.

Claims

1. A bottom slag treatment device (2) for a fluidized bed gasifier, the bottom slag treatment device (2) comprising a hot slag inlet and a cold slag outlet, the hot slag inlet being used to connect to the gasifier (1) to receive hot slag (D), the cold slag outlet being used to discharge cold slag (K), characterized in that: The bottom slag treatment device (2) is configured to perform reburning and cooling treatment on the hot slag (D); The bottom ash treatment device (2) comprises an oxidant inlet, a coolant inlet and a return gas outlet, wherein the oxidant inlet is used to introduce an oxidant (F) into the bottom ash treatment device (2), the coolant inlet is used to introduce a coolant (G) into the bottom ash treatment device (2), and the return gas outlet is used to return the return gas (E) to the gasifier (1); the oxidant inlet is located at a higher position in the vertical direction than the coolant inlet is located at a higher position in the vertical direction; The bottom ash processing device (2) further comprises a sealing gas inlet for introducing a sealing gas (H) into the bottom ash processing device (2), and the sealing gas inlet is located at a lower position in the vertical direction than the coolant inlet is located at a lower position in the vertical direction; The bottom ash processing device (2) is of a generally cylindrical structure, comprising an upper tapered section, a lower tapered section and a cylinder section between the upper tapered section and the lower tapered section; the return gas outlet is arranged on the upper tapered section.

2. The bottom ash treatment device (2) for a fluidized bed gasifier according to claim 1, characterized in that: The vertical position of the return gas outlet is higher than the vertical position of the oxidant inlet.

3. The bottom ash treatment device (2) for a fluidized bed gasifier according to claim 1, characterized in that: The bottom ash processing device (2) further comprises a gas collecting pipe (21), wherein the gas collecting pipe (21) is arranged inside the bottom ash processing device (2) and is connected to a return furnace gas outlet.

4. The bottom ash treatment device (2) for a fluidized bed gasifier according to claim 3, characterized in that: The bottom ash processing device (2) has a substantially cylindrical structure, and the gas collecting pipe (21) is arranged at the center of the bottom ash processing device (2) so that the central axis of the gas collecting pipe (21) is coaxial with the central axis of the bottom ash processing device (2).

5. The bottom ash treatment device (2) for a fluidized bed gasifier according to claim 1, characterized in that: The bottom ash processing device (2) comprises an upper tapered section, a lower tapered section and a barrel section between the upper tapered section and the lower tapered section, and an oxidant inlet, a coolant inlet and a sealing gas inlet are all arranged on the barrel section.

6. The bottom ash treatment device (2) for a fluidized bed gasifier according to any one of claims 1 to 5, characterized in that: The bottom ash processing device (2) further comprises an air lock (22), wherein the air lock (22) is arranged at the bottom of the bottom ash processing device (2).

7. A method for treating bottom ash of a fluidized bed gasifier, characterized in that: The bottom ash treatment method uses a bottom ash treatment device (2) for a fluidized bed gasification furnace according to any one of claims 1 to 6.

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