A coal fluidized bed partial gasification cogeneration device and process

Abstract

The present invention relates to the field of partial gasification and multi-production of coal, and discloses a fluidized bed partial gasification and co-production device for coal. In the device of the present invention, the fluidized bed gasifier is provided with a feeding device, a gasifying agent inlet, a furnace bottom coke removal device and a coke cooler, and the gas outlet at the top is externally connected to a cyclone separator; the cyclone separator is sequentially connected to a waste heat recovery device, a high-temperature dust collector, a tar condensation device and an electric tar collector, and a tar pool is connected to the bottom of the tar condensation device and the electric tar collector. The process of the present invention is to pyrolyze and partially gasify coal particles in a fluidized bed gasifier to produce semi-coke products and gasified gas, and the gasified gas is processed by the device to obtain tar and coal gas. The device of the present invention can use coal particles with particles less than 10 mm as raw materials, and partially gasify and co-produce a variety of products such as semi-coke, tar and high-quality coal gas, which can effectively reduce the emission of pollutants and realize the efficient and clean resource utilization of coal rich in volatile matter.

Description

Technical Field

[0001] The invention relates to the field of partial gasification and cogeneration of coal, and in particular to a fluidized bed partial gasification and cogeneration device and process for coal. Background Art

[0002] my country is a country rich in coal, poor in oil and little in gas. Coal has long been the main energy resource, but coal utilization has always been in a single development of coal production. The main way to utilize coal is direct combustion. Direct combustion not only fails to effectively utilize the hydrogen-rich components in coal, but also in the process of small-scale industrial kilns or civilian scattered burning, due to the rapid precipitation of coal volatiles, combustion is prone to produce small particulate pollutants such as carbon black. At the same time, the sulfur and nitrogen contained in it are also easy to generate pollution sources such as sulfur oxides and nitrogen oxides, producing a large amount of pollutants. If coal is used for a single purpose, in order to achieve a high conversion rate, the conversion process often requires complex processes and high operating costs, and the overall energy utilization efficiency is not high. Therefore, the multi-generation system of coal came into being.

[0003] The essence of coal polygeneration technology is to use coal as raw material, integrate various coal conversion technologies organically according to the different reactivity characteristics of different coal components and different conversion stages, and obtain a variety of high value-added chemical products, a variety of clean secondary energy and other products, which can simplify coal polygeneration technology, thereby reducing investment, reducing costs, and reducing the problem of removing pollutants from coal. The coal polygeneration system considers multiple coal production processes as a system, improves the utilization rate of coal resources from the perspective of overall utilization efficiency, pursues the maximization of overall production benefits and the minimization of pollutant emissions, and can better solve the resource and environmental problems faced.

[0004] At present, the main technologies for the multi-generation of coal include coal pyrolysis multi-generation technology, coal complete gasification multi-generation technology and coal partial gasification multi-generation technology. The multi-generation technology for coal pyrolysis is to first add coal into the pyrolysis gasification furnace to separate the volatiles through thermal cracking. The pyrolysis gas produced can be used as industrial gas and domestic gas. The pyrolysis gas and tar can also be used to obtain chemical raw materials through further processes. The semi-coke produced by pyrolysis can be directly sent to the combustion furnace as a fuel to burn and generate steam for power generation and heating. However, this technology is based on coal pyrolysis, and the gas obtained is mainly dry distillation gas. The gas output is low and the coal gasification share is low, which limits the further improvement of the coal utilization efficiency of the cogeneration system.

[0005] The coal complete gasification multi-generation technology is to completely convert coal in the gasification unit and convert solid carbon fuel into synthesis gas. The synthesis gas can be used as fuel, chemical raw material and combined cycle power generation and heating and refrigeration fields to achieve the co-production of a variety of high-quality products. This technology can achieve near-zero emissions of the system, and the particulate matter, SO2, NO in the system xPollutants such as solid waste can be effectively controlled, but this technology is mainly for gas phase products, which often require high temperature, high pressure and long residence time to obtain, which increases the technical difficulty and the equipment investment cost is high.

[0006] The partial coal gasification polygeneration technology implements the graded conversion of coal pyrolysis, gasification and combustion based on the different reactivity characteristics of different coal components and different conversion stages, so as to simplify the operation technology, reduce investment and reduce costs. The partial gasification reaction does not pursue the high conversion rate of coal. Coal can be partially gasified in a gasifier with relatively low requirements. The semi-coke that is not gasified can be directly burned as fuel or produced as a semi-coke product. According to different user needs, partial gasification can produce corresponding coal gas components; in addition, various other by-products can be obtained by adjusting the appropriate production process.

[0007] Patent CN 107841346A discloses a coal-air partial gasification heat, electricity and gas cogeneration device and method, which includes a circulating fluidized bed combustion furnace and a circulating fluidized bed gasification furnace. The flue gas at the top of the former is connected to the gas discharge pipeline, flue gas heat exchanger and steam generator to achieve heat or steam power generation; the top gas of the latter is connected to the gas discharge pipeline after separation; the separated materials and semi-coke at the bottom of the two are returned to the combustion furnace through the return device, combining the fluidized bed gasification technology and the semi-coke combustion technology to improve the overall efficiency of the coal utilization system. However, the process of double fluidized bed cogeneration of heat, electricity and gas adopted by it is complicated, the gasification furnace uses high temperature (900-1000℃), the coordinated and stable operation between the two fluidized beds is difficult to control, and the investment and operation cost is relatively high. Summary of the invention

[0008] In order to overcome the deficiencies in the above-mentioned prior art, the present invention provides a coal fluidized bed partial gasification co-production device and process, in which only a single fluidized bed gasifier is used to achieve the co-production of semi-coke, tar and high-quality coal gas, thereby reducing the difficulty of process control and investment and operating costs.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A coal fluidized bed partial gasification cogeneration device, comprising a fluidized bed gasifier, a feeding device, a furnace bottom coke removal device, a coke cooler, a cyclone separator, a high-temperature dust collector, a waste heat recovery device, a tar condensing device, an electric tar collector and a tar pool;

[0011] The bottom or lower part of the fluidized bed gasification furnace is provided with a furnace bottom coke removal device, the lower part is provided with a gasifying agent inlet, the middle and lower part is provided with a feeding device, and the top gas outlet is externally connected to a cyclone separator; the cyclone separator is connected in sequence to a waste heat recovery device, a high-temperature dust collector, a tar condensing device and an electric tar collector; the bottoms of the tar condensing device and the electric tar collector are connected to a tar pool; the furnace bottom coke removal device and the cyclone separator are both provided with a coke cooler.

[0012] Preferably, the cyclone separator comprises a first cyclone separator and a second cyclone separator connected in series, so as to further reduce the solid content in the fuel gas and improve the cleanliness of the coal gas.

[0013] The inlet and outlet of the above-mentioned furnace bottom coke discharge device are both provided with high temperature valves, which can discharge the semi-coke in a centralized manner as required.

[0014] The above-mentioned high-temperature dust collector is an electrostatic dust collector, which can improve the dust removal efficiency and obtain a gas product with higher purity.

[0015] The present invention also provides a coal fluidized bed partial gasification co-production process, which uses the above-mentioned coal fluidized bed partial gasification co-production device and specifically includes the following process steps:

[0016] (1) Coal particles are added into the fluidized bed gasifier from the feeding device in the lower part of the gasifier, and the gasifying agent is introduced into the lower part of the fluidized bed gasifier; the oxygen-coal ratio in the furnace is controlled to be no greater than 0.3 Nm 3 / Kg, coal particles undergo pyrolysis combustion and partial gasification reaction in the gasifier, producing gasified coal gas and semi-coke particles; coarser semi-coke particles are discharged from the coke discharge device at the bottom of the furnace into the coke cooler, and are sent out as semi-coke products after cooling;

[0017] (2) The gasified coal gas produced in the fluidized bed gasifier in step (1) carries the semi-coke particles into a cyclone separator for gas-solid separation; the separated semi-coke particles are discharged into a coke cooler and sent out as a semi-coke product after being cooled;

[0018] (3) The gasified gas separated in step (2) enters a waste heat recovery device for cooling; the cooled gasified gas enters a high-temperature dust removal device for dust removal, and then enters a tar condensation device for cooling; the condensed tar and liquid water are discharged into a tar pool, and the tar after oil-water separation is delivered as a product;

[0019] (4) The coal gas produced in step (3) enters the electrostatic precipitator to further remove tar mist and water mist, and the obtained clean coal gas is delivered as a product; the tar and water captured by the electrostatic precipitator are discharged into the tar pool, and the tar after oil-water separation is delivered as a product.

[0020] The coal particles in step (1) of the above-mentioned coal fluidized bed partial gasification co-production process have a particle size of less than 10 mm. At present, in the coal production process, the crushed coal particles less than 10 mm account for more than 70% of the total coal production. The present invention can avoid the limitation of the particle size of the raw coal.

[0021] In step (1) of the above-mentioned coal fluidized bed partial gasification co-production process, the gasifying agent is pure O2, O2 / CO2 mixed gas or air. Using air as the gasifying agent can control the production cost of coal gas and obtain low-cost fuel gas with a high nitrogen content; using a small amount of pure oxygen or O2 / CO2 mixed gas as the gasifying agent can obtain high-quality synthesis gas with a low nitrogen content.

[0022] The fluidized bed gasifier of the above-mentioned coal fluidized bed partial gasification co-production process operates under normal pressure or pressure, and the operating temperature is 500-800° C. The use of normal pressure and lower temperature for partial gasification can not only obtain high-value tar products, but also reduce the difficulty of device operation and reduce operating costs.

[0023] In the above step (3), the temperature of the gasified gas cooled by the waste heat recovery device is 400-500°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention can utilize crushed coal particles smaller than 10 mm, which is different from the limitation of existing fixed bed coal pyrolysis or gasification technology that requires lump coal raw materials larger than 10 mm, thereby greatly reducing the cost of raw materials.

[0026] (2) The present invention partially gasifies volatile-rich coal to produce semi-coke, tar and high-quality coal gas. The produced coal gas and tar can be used to produce clean natural gas, liquid fuel or high-value chemicals, thereby improving the utilization value and efficiency of coal. The produced semi-coke has low volatile matter content and low sulfur and nitrogen content, so it can be used as an alternative fuel for small-scale loose coal combustion, which can effectively reduce pollutant emissions, thereby realizing efficient and clean resource utilization of volatile-rich coal.

[0027] (3) The present invention improves the carbon conversion rate and overall efficiency of the coal co-production system, and reduces the complexity of the equipment, the difficulty of process control and the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the coal fluidized bed partial gasification cogeneration device of the present invention.

[0029] Among them, 1. fluidized bed gasification furnace; 2. feeding device; 3. coke removal device at the bottom of the furnace; 4. coke cooler; 5. first cyclone separator; 6. second cyclone separator; 7. waste heat recovery device; 8. high-temperature dust collector; 9. tar condensation device; 10. electric tar collector; 11. tar pool. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0031] like Figure 1 As shown, the coal fluidized bed partial gasification cogeneration device of the present invention includes a fluidized bed gasification furnace 1, a feeding device 2, a furnace bottom coke removal device 3, a coke cooler 4, a first cyclone separator 5, a second cyclone separator 6, a waste heat recovery device 7, a high-temperature dust collector 8, a tar condensing device 9, an electric tar collector 10 and a tar pool 11.

[0032] A bottom coke removal device 3 is provided at the bottom or lower part of the fluidized bed gasifier 1, a gasifying agent inlet is provided at the lower part, a feeding device 2 is provided at the middle and lower part, and a fuel gas outlet at the top is externally connected to a first cyclone separator 5; the first cyclone separator 5 is connected in sequence to a second cyclone separator 6, a waste heat recovery device 7, a high-temperature dust collector 8, a tar condensation device 9 and an electric tar collector 10; the bottoms of the tar condensation device 9 and the electric tar collector 10 are connected to a tar pool 11; the bottom coke removal device 3, the first cyclone separator 5 and the second cyclone separator 6 are all provided with a coke cooler 4; the inlet and outlet of the bottom coke removal device 3 are all provided with high-temperature valves.

[0033] Embodiment The device is operated according to the above description, and the coal type is bituminous coal with a particle size of less than 10 mm.

[0034] Example

[0035] A coal fluidized bed partial gasification co-production process comprises the following process steps:

[0036] (1) Coal raw materials are fed into the fluidized bed gasifier 1 through the feeding device 2, and an O2 / CO2 mixed gas is introduced into the lower part of the fluidized bed gasifier 1. The coal undergoes a partial gasification reaction in the furnace to produce gasification gas and semi-coke particles; the fluidized bed gasifier operates at normal pressure, the operating temperature is controlled to be 500-800°C, and the oxygen-coal ratio is not greater than 0.3Nm 3 / Kg, the coarser semi-coke particles are discharged from the coke discharge device 3 at the bottom of the furnace, enter the coke cooler 4 for cooling and are then sent out as semi-coke products;

[0037] (2) The gasification gas produced by the fluidized bed gasifier 1 carries the semi-coke particles into the first cyclone separator 5 and the second cyclone separator 6, and the semi-coke particles are separated and discharged to the coke cooler 4, and then sent out as semi-coke products after being cooled;

[0038] (3) The separated gasified gas enters the waste heat recovery device 7 and is cooled to 400-500°C. The cooled gasified gas is then dedusted by the high-temperature dust collector 8 and enters the tar condensation device 9. The high-temperature dust collector 8 uses an electrostatic dust collector and the operating temperature is controlled at about 500°C. The tar in the gasified gas is condensed and precipitated into the tar pool 11. The tar obtained after oil-water separation is sent out as a product. The tar can be further processed into gasoline, diesel or other chemical products.

[0039] (4) The coal gas from which tar gas has been removed is further purified by an electrostatic precipitator 10, wherein a small amount of tar mist and water mist are captured by the electrostatic precipitator and collected into a tar pool 11, and the remaining coal gas is clean coal gas and directly supplied to the outside as a product; the tar and water captured by the electrostatic precipitator are discharged into the tar pool, and the tar obtained after oil-water separation is delivered as a product.

[0040] The feed rate of this device is 20t / h, the semi-coke yield is about 11t / h, the tar yield is about 1.6t / h, and the gas output is about 6000Nm 3 / h.

Claims

1. A coal fluidized bed partial gasification co-production process, characterized in that: The coal fluidized bed partial gasification cogeneration device used includes a fluidized bed gasifier, a feeding device, a furnace bottom coke removal device, a coke cooler, a first cyclone separator, a second cyclone separator, a waste heat recovery device, a high-temperature dust collector, a tar condensation device, an electric tar collector and a tar pool; The bottom or lower part of the fluidized bed gasifier is provided with a furnace bottom coke discharge device, the lower part is provided with a gasifying agent inlet, the middle and lower part is provided with a feeding device, and the top gas outlet is externally connected to the first cyclone separator; the first cyclone separator is connected in sequence to the second cyclone separator, the waste heat recovery device, the high-temperature dust collector, the tar condensation device and the electric tar collector; the bottom of the tar condensation device and the electric tar collector are connected to the tar pool; the furnace bottom coke discharge device, the first cyclone separator and the second cyclone separator are all equipped with a coke cooler; the inlet and outlet of the furnace bottom coke discharge device are all provided with a high-temperature valve; The coal fluidized bed partial gasification co-production process specifically includes the following process steps: (1) Coal raw materials are fed into the fluidized bed gasifier through a feeding device, and an O2 / CO2 mixed gas is introduced into the lower part of the fluidized bed gasifier. The coal undergoes a partial gasification reaction in the furnace to produce gasification gas and semi-coke particles. The fluidized bed gasifier operates at normal pressure, the operating temperature is controlled to be 500-800℃, and the oxygen-coal ratio is not greater than 0.3Nm 3 / Kg, the coarser semi-coke particles are discharged from the coke discharge device at the bottom of the furnace, enter the coke cooler for cooling and are then sent out as semi-coke products; (2) The gasification gas produced by the fluidized bed gasifier carries the semi-coke particles into the first cyclone separator and the second cyclone separator, and the semi-coke particles are separated and discharged to the coke cooler, and then sent out as semi-coke products after cooling; (3) The separated gasification gas enters the waste heat recovery device and is cooled to 400-500°C. The cooled gasification gas is then dedusted by a high-temperature dust collector and enters the tar condensation device. The high-temperature dust collector uses an electrostatic dust collector and the operating temperature is controlled at 500°C. The tar in the gasification gas is condensed and precipitated into the tar pool. The tar obtained after oil-water separation is sent out as a product. The tar can be further processed to synthesize gasoline, diesel or other chemical products. (4) The coal gas from which tar gas has been removed is further purified by an electrostatic precipitator, wherein a small amount of tar mist and water mist are captured by the electrostatic precipitator and collected in a tar pool, and the remaining coal gas is clean coal gas and directly supplied to the outside as a product; the tar and water captured by the electrostatic precipitator are discharged into the tar pool, and the tar obtained after oil-water separation is delivered as a product; The particle size of the coal particles described in step (1) is less than 10 mm.

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