Gasification method and device

Abstract

The present invention relates to the technical field of coal gasification, and discloses a gasification method and device. The gasification method includes: introducing a first fuel and a first gasifying agent into a first reaction unit, so as to generate semicoke, as well as a mixture of first coal gas and first residual carbon after a first reaction occurs at a first reaction temperature; introducing the mixture of first coal gas and first residual carbon into a circulating fluidized bed gasification unit to generate a mixture of second coal gas and second residual carbon; introducing the mixture of second coal gas and second residual carbon into a secondary gas-solid separation unit for gas-solid separation to obtain product gas and second residual carbon; introducing the second residual carbon and air into a residual carbon combustion unit, so as to generate combustion heat after a combustion reaction occurs in the residual carbon combustion unit; wherein the combustion heat is used to be transferred to the first reaction unit to provide heat for the first reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of coal gasification, and particularly to a gasification method and device. Background Art

[0002] Coal gasification technology is an important part of China's clean coal technology, one of the main ways to efficiently and cleanly utilize coal, and has become the core technology of many modern energy and chemical systems. The coal gasification technology fully realizes the utilization of coal energy, and gasifies and extracts the easily gasifiable part of the coal as high-value-added coal gas.

[0003] Currently, the main problems existing in coal gasification technology include how to solve the problem of tar in coal gas, the problem of energy waste caused by incomplete combustion, and the problem of treatment of fly ash and residual carbon, etc. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In view of this, the present invention provides a gasification method and device to at least partially solve the above technical problems.

[0006] (II) Technical Solutions

[0007] One aspect of the present invention provides a gasification method, including:

[0008] Feeding a first fuel and a first gasifying agent into a first reaction unit, so that after the first fuel and the first gasifying agent undergo a first reaction in the first reaction unit at a first reaction temperature, semi-coke, and a mixture of first coal gas and first residual carbon are generated;

[0009] Feeding the mixture of first coal gas and first residual carbon into a circulating fluidized bed gasification unit, so that after the mixture of first coal gas and first residual carbon undergoes tar removal and primary gas-solid separation in the circulating fluidized bed gasification unit under tar removal reaction conditions, a mixture of second coal gas and second residual carbon is generated; wherein, the tar removal reaction conditions include: a second reaction temperature condition and a semi-coke catalyst condition, and the circulating fluidized bed gasification unit and the first reaction unit are independently arranged respectively;

[0010] Feeding the mixture of second coal gas and second residual carbon into a secondary gas-solid separation unit for gas-solid separation to obtain product gas and second residual carbon;

[0011] Feeding the second residual carbon and air into a residual carbon combustion unit, so that after the second residual carbon and air undergo a combustion reaction in the residual carbon combustion unit, combustion heat is generated; wherein the combustion heat is used to be transferred to the first reaction unit to provide heat for the first reaction.

[0012] According to an embodiment of the present invention, the above method further includes: introducing a second fuel and a second gasifying agent into the circulating fluidized bed gasification unit, so that after the second fuel and the second gasifying agent undergo a gasification reaction in the circulating fluidized bed gasification unit, semi-coke catalyst is generated and heat is released to provide the reaction conditions for tar removal, wherein the second gasifying agent includes at least one of the following: air, a mixture of air and steam.

[0013] According to an embodiment of the present invention, wherein:

[0014] The circulating fluidized bed gasification unit includes a riser, a primary gas-solid separation device, and a return device;

[0015] The second fuel and the second gasifying agent enter from the bottom of the riser;

[0016] A mixture of the first coal gas and the first residual carbon is introduced into the middle and lower part of the riser.

[0017] According to an embodiment of the present invention, the above method further includes:

[0018] After tar removal is performed on the mixture of the first coal gas and the first residual carbon in the middle and lower part of the riser, a mixture of the second coal gas, the second residual carbon, and the first residual carbon is generated;

[0019] After the mixture of the second coal gas, the second residual carbon, and the first residual carbon is subjected to gas-solid separation through the primary gas-solid separation device, a mixture of the second coal gas and the second residual carbon, and circulating ash particles are generated;

[0020] The circulating ash particles are returned to the riser through the return device.

[0021] According to an embodiment of the present invention, wherein:

[0022] The first gasifying agent uses an oxygen-containing gasifying agent or a non-oxygen-containing gasifying agent;

[0023] In the case where the first gasifying agent is a non-oxygen-containing gasifying agent, the first reaction is the pyrolysis reaction of the first fuel;

[0024] In the case where the first gasifying agent is an oxygen-containing gasifying agent, the first reaction is the partial gasification reaction of the first fuel.

[0025] According to an embodiment of the present invention, wherein:

[0026] When the combustion heat is sufficient to maintain the first reaction temperature, the first gasifying agent uses a non-oxygen-containing gasifying agent;

[0027] When the combustion heat is not sufficient to maintain the first reaction temperature, the first gasifying agent uses an oxygen-containing gasifying agent.

[0028] According to an embodiment of the present invention, wherein:

[0029] The oxygen-free gasifying agent includes at least one of the following: cold gas, steam;

[0030] The oxygen-containing gasifying agent includes at least one of the following: air, a mixture of air and steam.

[0031] According to an embodiment of the present invention, wherein:

[0032] After the second residual carbon and air undergo a combustion reaction in the residual carbon combustion unit, flue gas is also generated:

[0033] The above method further includes: passing the flue gas into a waste heat recovery system so as to carry out waste heat recovery and utilization of the flue gas in the waste heat recovery system.

[0034] According to an embodiment of the present invention, wherein:

[0035] The first reaction temperature is 500 - 900 °C;

[0036] The second reaction temperature is 900 - 1050 °C.

[0037] According to an embodiment of the present invention, wherein:

[0038] The combustion heat is transferred to the first reaction unit in a way of indirect heat exchange through a partition wall.

[0039] According to an embodiment of the present invention, wherein passing air into the residual carbon combustion unit includes:

[0040] Passing air into the residual carbon combustion unit in a way of staged feeding.

[0041] Another aspect of the present invention provides a gasification device, including:

[0042] A first reaction unit, for a first fuel and a first gasifying agent to undergo a first reaction in the first reaction unit at the first reaction temperature, and then generate semicoke, as well as a mixture of first coal gas and first residual carbon;

[0043] A circulating fluidized bed gasification unit, for the mixture of first coal gas and first residual carbon to carry out tar removal and primary gas-solid separation in the circulating fluidized bed gasification unit under tar removal reaction conditions, and then generate a mixture of second coal gas and second residual carbon; wherein, the tar removal reaction conditions include: a second reaction temperature condition and a semicoke catalyst condition, the circulating fluidized bed gasification unit and the first reaction unit are independently arranged respectively, and the circulating fluidized bed gasification unit and the first reaction unit are connected through a gradually narrowing constriction, wherein the small-diameter part of the constriction is connected to the circulating fluidized bed gasification unit, and the large-diameter part of the constriction is connected to the first reaction unit;

[0044] A secondary gas-solid separation unit, for carrying out gas-solid separation on the mixture of second coal gas and second residual carbon to obtain product gas and second residual carbon;

[0045] The residual carbon combustion unit is used for the second residual carbon and air to generate combustion heat after a combustion reaction occurs in the residual carbon combustion unit; the combustion heat is used to be transferred to the first reaction unit to provide heat for the first reaction.

[0046] According to an embodiment of the present invention, wherein:

[0047] The circulating fluidized bed gasification unit includes a riser, a primary gas-solid separation device, and a return device;

[0048] Among them, the riser is used for the mixture of the first coal gas and the first residual carbon to generate a mixture of the second coal gas, the second residual carbon, and circulating ash particles after tar removal in the lower part of the riser;

[0049] The primary gas-solid separation device is used for gas-solid separation of the mixture of the second coal gas, the second residual carbon, and the circulating ash particles to generate a mixture of the second coal gas and the second residual carbon, and carbon-containing particle fly ash;

[0050] The return device is used for returning the carbon-containing particle fly ash to the riser.

[0051] According to an embodiment of the present invention, the above device further includes: a heat exchange heat pipe, arranged between the residual carbon combustion unit and the first reaction unit, and used for transferring the combustion heat to the first reaction unit.

[0052] According to an embodiment of the present invention, wherein: the residual carbon combustion unit is embedded in the first reaction unit.

[0053] (III) Beneficial effects

[0054] According to an embodiment of the present invention, product semicoke is generated through the first reaction unit, tar in the coal gas is removed through the circulating fluidized bed gasification unit, residual carbon is separated through the secondary gas-solid separation unit, and combustion heat is generated through the residual carbon combustion unit and the combustion heat is transferred to the first reaction unit to provide heat for the first reaction. It can be seen that through the method of the embodiment of the present invention, on the premise of realizing the production of semicoke products and high-calorie and tar-free coal gas products, the effective treatment of residual carbon and the energy recycling of fly ash residual carbon are also realized. The combustion heat of the fly ash residual carbon is supplied to the first reaction unit to meet the heat demand of its reaction, realizing the integrated treatment of residual carbon and improving the energy utilization rate. According to an embodiment of the present invention, by setting the circulating fluidized bed gasification unit, the fluidized bed reaction conditions are mild. Utilizing the characteristics of the riser of the circulating fluidized bed being rich in high-carbon semicoke, the problem of tar in the coal gas can be effectively solved, and at the same time, it has the advantage of wide fuel adaptability.

[0055] According to an embodiment of the present invention, the circulating fluidized bed gasification unit and the first reaction unit are separately and independently arranged. Such an arrangement can physically isolate the two reaction units, preventing the semicoke catalyst in the circulating fluidized bed gasification unit from entering the first reaction unit, so as not to reduce the content of high-carbon semicoke in the circulating fluidized bed gasification unit and affect the tar removal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a flowchart of implementing the gasification method of an embodiment of the present invention by using the gasification device of an embodiment of the present invention;

[0057] Figure 2 is a flowchart of implementing the gasification method of another embodiment of the present invention by using the gasification device of an embodiment of the present invention;

[0058] Figure 3 is a flowchart of implementing the gasification method of another embodiment of the present invention by using the gasification device of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further describes the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0060] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0061] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0062] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0063] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression (for example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression (for example, "a system having at least one of A, B, or C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0064] In coal gasification, partial gasification of coal realizes the hierarchical utilization of coal by utilizing the different reaction characteristics of different components of coal. The easily gasifiable part of the coal is gasified and extracted as high-value-added gas, and the residue after partial gasification - coke can be used as an important raw material or fuel for metallurgy, machinery, and chemical industry. The target products of the coal partial gasification technology are to obtain high-value-added gas without tar and semi-coke products.

[0065] In the process of implementing the present invention, it is found that: for the removal of tar in the gas, the method of passing the gas through a fixed-bed high-temperature semi-coke bed layer can be adopted. However, this method, on the one hand, requires creating a high-temperature environment and has high requirements for the equipment material, and on the other hand, it is difficult to scale up the fixed bed. For the problem of residual carbon treatment, the cooled residual carbon can be collected by a dust collector and then directly burned in a residual carbon furnace or mixed with coal for combustion. However, there are problems such as the relatively high cost of supporting the residual carbon furnace and the difficulty in igniting the low-temperature residual carbon.

[0066] In view of this, the present invention provides a gasification method to produce high-value-added gas and semi-coke products under mild reaction conditions, while effectively reducing the tar content in the gas and realizing the efficient recycling of the energy of fly ash residual carbon on the basis of effectively treating coal residual carbon.

[0067] Figure 1 It is a flow chart of implementing the gasification method of the embodiments of the present invention by using the gasification device of the embodiments of the present invention.

[0068] As Figure 1 shown, the gasification method includes:

[0069] The first fuel A (solid combustible, mainly coal) and the first gasifying agent C (which can be air, steam, a mixture of air and steam, or cold gas) are introduced into the first reaction unit 1 so that after the first fuel A and the first gasifying agent C undergo a first reaction in the first reaction unit 1 at the first reaction temperature (500 - 900 °C), a product semicoke E in larger particles, as well as a mixture F of the first gas and the first residual carbon (including fine particle semicoke) are generated; among them, the semicoke E is directly discharged from the first reaction unit 1 as a product and used as an important raw material or fuel for metallurgy, machinery, and chemical industry. Among them, the first gas is the gas before tar removal, which contains tar and is a high-calorific value gas.

[0070] After that, the mixture F of the first gas and the first residual carbon is introduced into the circulating fluidized bed gasification unit 2 so that after the mixture F of the first gas and the first residual carbon undergoes tar removal and primary gas-solid separation in the circulating fluidized bed gasification unit 2 under tar removal reaction conditions, a mixture J of the second gas (the gas after tar removal, without tar or containing trace amounts of tar) and the second residual carbon is generated; among them, the tar removal reaction conditions include: the second reaction temperature condition (the second reaction temperature is 900 - 1050 °C) and the semicoke catalyst condition. Among them, the second reaction temperature in this reaction stage is higher than the first reaction temperature in the previous reaction stage.

[0071] According to an embodiment of the present invention, the circulating fluidized bed gasification unit 2 needs to be rich in high-carbon semicoke, which is a high-carbon region, and its reaction temperature is 900 - 1050 °C. Under the action of high temperature and semicoke catalysis, the tar in the gas will crack into small molecule gases, effectively improving the effective gas components in the gas while removing tar.

[0072] According to an embodiment of the present invention, it further includes: introducing the second fuel B and the second gasifying agent D into the circulating fluidized bed gasification unit 2 so that after the second fuel B and the second gasifying agent D undergo a gasification reaction in the circulating fluidized bed gasification unit 2, a semicoke catalyst is generated and heat is released to provide tar removal reaction conditions, where the second gasifying agent D uses an oxygen-containing gasifying agent and can include at least one of the following: air, a mixture of air and steam.

[0073] According to an embodiment of the present invention, the circulating fluidized bed gasification unit 2 and the first reaction unit 1 are independently arranged respectively.

[0074] Then, the mixture J of the second gas and the second residual carbon is introduced into the secondary gas-solid separation unit 3 for gas-solid separation to obtain the product gas G and the second residual carbon L;

[0075] Finally, the second residual carbon L and air K are introduced into the residual carbon combustion unit 4 so that a combustion heat H is generated after the second residual carbon L and air K undergo a combustion reaction in the residual carbon combustion unit 4; wherein, the combustion reaction temperature is greater than 800 °C, and the combustion heat H is used to be transferred to the first reaction unit 1 to provide heat for the first reaction.

[0076] According to an embodiment of the present invention, a product semicoke is generated through the first reaction unit, the removal of tar in the coal gas is realized through the circulating fluidized bed gasification unit, the second residual carbon is separated through the secondary gas-solid separation unit, and the combustion heat is generated through the residual carbon combustion unit and the combustion heat is transferred to the first reaction unit to provide heat for the first reaction. It can be seen that through the method of the embodiment of the present invention, on the premise of realizing the production of semicoke products and high calorific value and tar-free coal gas products, the effective treatment of residual carbon and the energy recycling of fly ash residual carbon are also realized. The combustion heat of the fly ash residual carbon is supplied to the first reaction unit to meet the heat demand of its reaction, realizing the integrated treatment of residual carbon and improving the energy utilization rate. According to an embodiment of the present invention, by arranging the circulating fluidized bed gasification unit, the fluidized bed reaction conditions are mild, and by utilizing the characteristics of the circulating fluidized bed riser rich in high-carbon semicoke, the problem of tar in the coal gas can be effectively solved, and at the same time, it has the advantage of wide fuel adaptability.

[0077] According to an embodiment of the present invention, the circulating fluidized bed gasification unit and the first reaction unit are respectively and independently arranged. Such an arrangement can physically isolate the two reaction units and prevent the semicoke catalyst in the circulating fluidized bed gasification unit from entering the first reaction unit, so as not to reduce the content of high-carbon semicoke in the circulating fluidized bed gasification unit and affect the tar removal effect.

[0078] According to an embodiment of the present invention, wherein: the first gasifying agent C uses an oxygen-containing gasifying agent or a non-oxygen-containing gasifying agent; when the first gasifying agent C is a non-oxygen-containing gasifying agent, the first reaction is the pyrolysis reaction of the first fuel A; when the first gasifying agent C is an oxygen-containing gasifying agent, the first reaction is the partial gasification reaction of the first fuel A.

[0079] According to an embodiment of the present invention, whether to select an oxygen-containing gasifying agent or a non-oxygen-containing gasifying agent for the first gasifying agent C can be selected according to the actual operation conditions, wherein:

[0080] When the combustion heat H is sufficient to maintain the first reaction temperature, the first gasifying agent C uses a non-oxygen-containing gasifying agent, and the first reaction in the first reaction unit 1 is the pyrolysis reaction of the first fuel A. All the heat required for the pyrolysis reaction comes from the combustion heat H of the second residual carbon L; wherein, the non-oxygen-containing gasifying agent can adopt at least one of the following: cold coal gas, water vapor. Under the pyrolysis reaction conditions, the carbon consumption in the product semicoke E is less and its semicoke quality is better.

[0081] In the case where the combustion heat H is insufficient to maintain the first reaction temperature, the first gasifying agent C is an oxygen-containing gasifying agent, and the first reaction in the first reaction unit 1 is the partial gasification reaction of the first fuel A; the heat required for the partial gasification reaction comes from the combustion heat H of the second residual carbon L and the partial combustion heat of the first fuel A. The oxygen-containing gasifying agent can be at least one of the following: air, a mixture of air and steam. Under the partial gasification reaction conditions, there is a small amount less carbon in the product semicoke E, and the quality of the semicoke is not as good as that produced under the pyrolysis reaction conditions, but the tar content in the first gas (gas before tar removal) is less, and the subsequent tar removal treatment pressure is smaller.

[0082] According to an embodiment of the present invention, after the second residual carbon L and air K undergo a combustion reaction in the residual carbon combustion unit (4), flue gas Y is also generated. The above method further includes: introducing the flue gas Y into a waste heat recovery system so as to carry out waste heat recovery and utilization of the flue gas Y in the waste heat recovery system, further improving the energy utilization rate of the system.

[0083] According to an embodiment of the present invention, after the second residual carbon L and air K undergo a combustion reaction in the residual carbon combustion unit 4 to generate combustion heat H, the combustion heat H can be transferred to the first reaction unit (1) by means of wall-to-wall heat exchange.

[0084] According to an embodiment of the present invention, the above wall-to-wall heat exchange can adopt heat pipe heat exchange. The wall-to-wall heat exchange has a large heat transfer area and good heat transfer effect. By adopting the wall-to-wall heat exchange method, the heat transfer medium will not be mixed, and the indirect heat transfer effect between the first reaction unit 1 and the residual carbon combustion unit 4 is improved, and the heat utilization rate is improved.

[0085] According to an embodiment of the present invention, when introducing air K into the residual carbon combustion unit 4, air K can be introduced into the residual carbon combustion unit 4 by means of staged feeding. In this way, the temperature distribution in the residual carbon combustion unit 4 can be ensured to be more uniform, which is beneficial to heat exchange between the residual carbon combustion unit 4 and the first reaction unit 1.

[0086] Figure 2 It is a flow chart of implementing the gasification method of another embodiment of the present invention by using the gasification device of the embodiment of the present invention. Figure 2 The illustrated embodiment is substantially the same as Figure 1 the illustrated embodiment, the difference being:

[0087] The circulating fluidized bed gasification unit 2 includes a riser 21, a primary gas-solid separation device 22 and a return device 23; according to an embodiment of the present invention, using this device, the above method further includes:

[0088] After the mixture F of the first gas (gas before tar removal) and the first residual carbon undergoes tar removal in the middle and lower part of the riser 21, a mixture M of the second gas (gas after tar removal), the second residual carbon, and circulating ash particles is generated;

[0089] After the mixture M of the second coal gas, the second residual carbon, and the circulating ash particles is subjected to gas-solid separation by the primary gas-solid separation device 22, a mixture J of the second coal gas and the second residual carbon, and the circulating ash particles N are generated;

[0090] The circulating ash particles N are returned to the riser 21 through the return device 23.

[0091] According to an embodiment of the present invention, by providing the primary gas-solid separation device 22 and the return device 23, the circulating ash particles N can be returned to the riser 21 for reuse, further improving the carbon conversion rate of the system.

[0092] According to an embodiment of the present invention, the first reaction unit 1 can adopt a gasifier 11, the residual carbon combustion unit 4 can adopt a combustion furnace 41, and the secondary gas-solid separation unit 3 can adopt a secondary gas-solid separation device 31.

[0093] According to an embodiment of the present invention, pulverized coal particles are fed into the upper part of the gasifier 11, and a pyrolysis reaction or a partial gasification reaction occurs. The reaction temperature is 500 to 900 °C, and the superficial gas velocity is 0 to 1 m / s. The heat required for the pyrolysis reaction comes from the indirect heat exchange with the combustion furnace 41. When a partial gasification reaction occurs, the heat required comes from the indirect heat exchange with the combustion furnace 41 and the partial combustion heat of the coal. The mixture F of the first coal gas and the first residual carbon then enters the middle and lower part of the riser 21. The reaction temperature of the riser 21 is 900 to 1050 °C, and the superficial gas velocity is 2.5 to 5 m / s. The second fuel B and the second gasifying agent D enter from the bottom of the riser 21. The riser 21 is rich in high-carbon semicoke and is a high-carbon region. Under the action of high temperature and semicoke catalysis, the tar in the coal gas will crack and become small-molecule gases and enter the mixture J of the second coal gas and the second residual carbon, effectively increasing the effective gas components in the coal gas.

[0094] Some fine particles in the riser 21 are returned to the riser 21 through the gas-solid separation device 22 and the return device 23. The mixture J of the second coal gas and the second residual carbon passes through the secondary gas-solid separation device 31 to obtain the product coal gas G and the second residual carbon L. The second residual carbon L enters the combustion furnace 41 and undergoes a combustion reaction with the air K to release heat H. The reaction temperature is 800 °C or above. The heat H is transferred to the gasifier 11 by indirect heat exchange to provide heat for the pyrolysis / partial gasification reaction. The flue gas Y then enters the subsequent waste heat recovery system. The product gas G passes through the subsequent coal gas waste heat recovery system and the coal gas purification system to achieve the recovery and purification of the coal gas waste heat.

[0095] According to an embodiment of the present invention, second fuel B and second gasifying agent D enter from the bottom of riser 21; a mixture F of first coal gas and first residual carbon before tar removal is introduced into the middle and lower part of riser 21. Since the dense phase region at the bottom of riser 21 has a high carbon content and is an enrichment region of high-carbon semicoke, introducing the mixture F of first coal gas and first residual carbon into the middle and lower part of riser 21 can enable the first coal gas before tar removal to be in full contact with the semicoke catalyst, improving the tar removal effect.

[0096] Figure 3 It is a flowchart of a gasification method according to another embodiment of the present invention implemented by using the gasification device of the embodiment of the present invention.

[0097] Figure 3 The illustrated embodiment is Figure 2 basically the same as the illustrated embodiment, with the difference being that the residual carbon combustion unit 4 is embedded in the first reaction unit 1, and the high-temperature heat pipe can be arranged to surround the residual carbon combustion unit 4. Such a design can increase the heat transfer area between the residual carbon combustion unit 4 and the first reaction unit 1 and enhance the heat exchange effect between the two.

[0098] On the other hand, the present invention provides a gasification device, which can be referred to Figure 1 to understand the structure of the gasification device of this embodiment of the present invention.

[0099] As Figure 1 shown, the device includes a first reaction unit 1, a circulating fluidized bed gasification unit 2, a secondary gas-solid separation unit 3, and a residual carbon combustion unit 4.

[0100] Among them, the first reaction unit 1 is used for first fuel A and first gasifying agent C to undergo a first reaction in the first reaction unit 1 at the first reaction temperature, generating semicoke E, as well as a mixture F of first coal gas and first residual carbon.

[0101] The circulating fluidized bed gasification unit 2 is connected to the first reaction unit 1 and is used for the mixture F of first coal gas and first residual carbon to undergo tar removal and primary gas-solid separation in the circulating fluidized bed gasification unit 2 under tar removal reaction conditions, generating a mixture J of second coal gas and second residual carbon; among them, the tar removal reaction conditions include: a second reaction temperature condition and a semicoke catalyst condition. The circulating fluidized bed gasification unit 2 and the first reaction unit 1 are independently arranged, and the circulating fluidized bed gasification unit 2 and the first reaction unit 1 are connected through a gradually narrowing constriction. The small-diameter part of the constriction is connected to the circulating fluidized bed gasification unit 2, and the large-diameter part of the constriction is connected to the first reaction unit 1. Such a setting can physically isolate the two reaction units, and the constriction structure can prevent the semicoke catalyst in the circulating fluidized bed gasification unit from entering the first reaction unit, so as not to reduce the content of high-carbon semicoke in the circulating fluidized bed gasification unit and affect the tar removal effect.

[0102] A circulating fluidized bed gasification unit 2 is provided with an inlet for a second fuel B (a solid combustible, mainly coal) and an inlet for a second gasifying agent D. In order to introduce the second fuel B and the second gasifying agent D into the circulating fluidized bed gasification unit 2, an endothermic gasification reaction occurs in the circulating fluidized bed gasification unit 2 to generate a char catalyst and release heat, so as to provide reaction conditions for tar removal. The second gasifying agent D is an oxygen-containing gasifying agent, which may include at least one of the following: air, a mixture of air and steam.

[0103] A secondary gas-solid separation unit 3 is configured to perform gas-solid separation on a mixture J of the second coal gas after tar removal and the second residual carbon to obtain a product gas G and a second residual carbon L.

[0104] A residual carbon combustion unit 4 is configured to generate combustion heat H after a combustion reaction occurs between the second residual carbon L and air K in the residual carbon combustion unit 4; the combustion heat H is used to be transferred to the first reaction unit 1 to provide heat for the first reaction.

[0105] According to an embodiment of the present invention, the above gasification device further includes: a heat exchange heat pipe disposed between the residual carbon combustion unit 4 and the first reaction unit 1 for transferring the combustion heat H to the first reaction unit 1.

[0106] According to an embodiment of the present invention, reference may be made to Figure 2 to understand the structure of the gasification device according to another embodiment of the present invention. Different from the device of the Figure 1 illustrated embodiment, as Figure 2 illustrated, the circulating fluidized bed gasification unit 2 includes a riser 21, a primary gas-solid separation device 22, and a return device 23. The first reaction unit 1 may adopt a gasifier 11, the residual carbon combustion unit 4 may adopt a combustion furnace 41, and the secondary gas-solid separation unit 3 may adopt a secondary gas-solid separation device 31.

[0107] Among them, the riser 21 is configured to generate the second coal gas after tar removal, the second residual carbon, and M after tar removal of a mixture F of the first coal gas and the first residual carbon in the lower part of the riser 21 before tar removal.

[0108] The primary gas-solid separation device 22 is configured to perform gas-solid separation on a mixture M of the second coal gas after tar removal, the second residual carbon, and circulating ash particles to generate a mixture J of the second coal gas and the second residual carbon, and circulating ash particles N.

[0109] The return device 23 is configured to return the circulating ash particles N to the riser 21.

[0110] According to an embodiment of the present invention, by providing the primary gas-solid separation device 22 and the return device 23, the circulating ash particles N can be returned to the riser 21 for reuse, further improving the system carbon conversion rate.

[0111] According to an embodiment of the present invention, reference may be made to Figure 3 understand the structure of the gasification device according to another embodiment of the present invention. Different from the Figure 2 device of the illustrated embodiment, as Figure 3 shown, the residual carbon combustion unit 4 is embedded in the first reaction unit 1, and the high-temperature heat pipe can be arranged around the residual carbon combustion unit 4. With such a design, the heat transfer area between the residual carbon combustion unit 4 and the first reaction unit 1 can be increased, and the heat exchange effect between the two can be enhanced.

[0112] The specific embodiments described above further elaborate on the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A gasification method, comprising: Introduce a first fuel and a first gasifying agent into a first reaction unit (1) so that after the first fuel and the first gasifying agent undergo a first reaction in the first reaction unit (1) at a first reaction temperature, semicoke, and a mixture of first coal gas and first residual carbon are produced; Introduce the mixture of the first coal gas and the first residual carbon into a circulating fluidized bed gasification unit (2) so that after the mixture of the first coal gas and the first residual carbon undergoes tar removal and primary gas-solid separation in the circulating fluidized bed gasification unit (2) under tar removal reaction conditions, a mixture of second coal gas and second residual carbon is produced; wherein, the tar removal reaction conditions include: a second reaction temperature condition and a semicoke catalyst condition, and the circulating fluidized bed gasification unit (2) and the first reaction unit (1) are respectively and independently arranged; After introducing the mixture of the second coal gas and the second residual carbon into a secondary gas-solid separation unit (3) for gas-solid separation, product gas and second residual carbon are obtained; Introduce the second residual carbon and air into a residual carbon combustion unit (4) so that after the second residual carbon and the air undergo a combustion reaction in the residual carbon combustion unit (4), combustion heat is generated; wherein the combustion heat is used to be transferred to the first reaction unit (1) so as to provide heat for the first reaction.

2. The method according to claim 1, further comprising: Introduce a second fuel and a second gasifying agent into the circulating fluidized bed gasification unit (2) so that after the second fuel and the second gasifying agent undergo a gasification reaction in the circulating fluidized bed gasification unit (2), a semicoke catalyst is generated and heat is released to provide the tar removal reaction conditions, wherein the second gasifying agent includes at least one of the following: air, a mixture of air and steam.

3. The method according to claim 2, wherein: The circulating fluidized bed gasification unit (2) includes a riser (21), a primary gas-solid separation device (22), and a return device (23); The second fuel and the second gasifying agent enter from the bottom of the riser (21); The mixture of the first coal gas and the first residual carbon is introduced into the middle and lower part of the riser (21).

4. The method according to claim 3, further comprising: After the mixture of the first coal gas and the first residual carbon undergoes tar removal in the middle and lower part of the riser (21), a mixture of second coal gas, second residual carbon, and circulating ash particles is produced; After the mixture of the second coal gas, the second residual carbon, and the circulating ash particles is subjected to gas-solid separation through the primary gas-solid separation device (22), a mixture of the second coal gas and the second residual carbon, and circulating ash particles are produced; The circulating ash particles are returned to the riser (21) through the return device (23).

5. The method according to claim 1, wherein: The first gasifying agent uses an oxygen-containing gasifying agent or a non-oxygen-containing gasifying agent; When the first gasifying agent is a non-oxygen-containing gasifying agent, the first reaction is the pyrolysis reaction of the first fuel; When the first gasifying agent is an oxygen-containing gasifying agent, the first reaction is the partial gasification reaction of the first fuel.

6. The method according to claim 5, wherein: When the combustion heat is sufficient to maintain the first reaction temperature, the first gasifying agent uses a non-oxygen-containing gasifying agent; When the combustion heat is not sufficient to maintain the first reaction temperature, the first gasifying agent uses an oxygen-containing gasifying agent.

7. The method according to claim 5, wherein: The oxygen-free oxidant includes at least one of the following: cold gas, steam; The oxygen-containing oxidant includes at least one of the following: air, a mixture of air and steam.

8. The method according to claim 1, wherein: The second residual carbon and the air undergo a combustion reaction in the residual carbon combustion unit (4) to generate flue gas: The method further includes: introducing the flue gas into a waste heat recovery system so as to carry out waste heat recovery and utilization of the flue gas in the waste heat recovery system.

9. The method according to claim 1, wherein: The first reaction temperature is 500 - 900 °C; The second reaction temperature is 900 - 1050 °C.

10. The method according to claim 1, wherein: The combustion heat is transferred to the first reaction unit (1) by means of wall-to-wall heat exchange.

11. The method according to claim 1, wherein, Introducing the air into the residual carbon combustion unit (4) includes: Introducing the air into the residual carbon combustion unit (4) in a staged feeding manner.

12. A gasification device, comprising: The first reaction unit (1) is used for the first fuel and the first gasifying agent to undergo a first reaction in the first reaction unit (1) at the first reaction temperature, and then generate semicoke, and a mixture of first gas and first residual carbon; The circulating fluidized bed gasification unit (2) is used for the mixture of the first gas and the first residual carbon to carry out tar removal and primary gas-solid separation in the circulating fluidized bed gasification unit (2) under tar removal reaction conditions, and then generate a mixture of second gas and second residual carbon; wherein, the tar removal reaction conditions include: a second reaction temperature condition and a semicoke catalyst condition, the circulating fluidized bed gasification unit (2) and the first reaction unit (1) are respectively and independently arranged, and the circulating fluidized bed gasification unit (2) and the first reaction unit (1) are connected through a gradually shrinking neck, wherein the small-diameter part of the neck is connected to the circulating fluidized bed gasification unit (2), and the large-diameter part of the neck is connected to the first reaction unit (1); The secondary gas-solid separation unit (3) is used for gas-solid separation of the mixture of the second gas and the second residual carbon to obtain product gas and second residual carbon; The residual carbon combustion unit (4) is used for the second residual carbon and air to generate combustion heat after undergoing a combustion reaction in the residual carbon combustion unit (4); wherein the combustion heat is used to be transferred to the first reaction unit (1) so as to provide heat for the first reaction.

13. The gasification device according to claim 12, wherein: The circulating fluidized bed gasification unit (2) includes a riser (21), a primary gas-solid separation device (22) and a return device (23); Among them, the riser (21) is used for the mixture of the first gas and the first residual carbon to carry out tar removal in the lower part of the riser (21), and then generate a mixture of second gas, second residual carbon, and circulating ash particles; The primary gas-solid separation device (22) is used for gas-solid separation of the mixture of the second gas, the second residual carbon, and the circulating ash particles to generate a mixture of the second gas and the second residual carbon, and circulating ash particles; The return device (23) is used for returning the circulating ash particles to the riser (21).

14. The gasification device according to claim 12, further comprising: The heat exchange heat pipe is arranged between the residual carbon combustion unit (4) and the first reaction unit (1) and is used to transfer the combustion heat to the first reaction unit (1).

15. The gasification device according to claim 12, wherein: The residual carbon combustion unit (4) is embedded in the first reaction unit (1).

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