Coal gas production system and coal gas production method

Abstract

The invention discloses a coal gas production system and a coal gas production method, and belongs to the technical field of coal gas production. The production system comprises a gas generator, a separator, a dust remover and a cooler which are sequentially communicated, wherein the cooler is provided with a first gas outlet and a second gas outlet; wherein the first coal gas outlet is connected with output equipment; the second coal gas outlet is divided into two paths, one path of high-pressure coal gas is conveyed to the dust remover to serve as a reverse blowing gas source of the dust remover, and therefore the purpose of cleaning dust of the dust remover is achieved. And the other path of high-pressure coal gas is conveyed to the material returning device to serve as a material returning power source of the material returning device, and the generated gas-solid mixture is conveyed to the coal gas producer to participate in the reaction again. According to the invention, the clean coal gas is used as a power source for injection and material returning, so that on one hand, resource waste caused by using nitrogen as an injection and material returning medium is saved, and on the other hand, the reaction probability of solid carbon and CO2 in the coal gas is increased, and the calorific value of the coal gas is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal gas production, and more specifically, relates to a coal gas production system and a coal gas production method. Background Art

[0002] my country is a country rich in coal, short of oil and gas. This energy structure background determines that coal will remain the main energy source of my country for a long time in the future and an important pillar of my country's economic development. In the current industrial system, there are generally two ways to use coal. One is to generate heat through coal combustion and then use it in other ways after heat exchange. The other is to produce coal gas through coal gasification; the produced coal gas is used as fuel or chemical synthesis gas.

[0003] However, in the process of producing coal gas, gas is generally used as the return medium of the return device and the blowing medium of the bag filter. The separated solid impurities are returned to the furnace for further conversion to improve the overall system utilization efficiency. In the prior art, inert gas is generally used as the blowing medium, although it can well complete the operation of returning the material to the furnace. However, the additional blowing medium not only causes a waste of resources, but also increases the production cost.

[0004] After searching, the application with Chinese patent publication number CN107557074A discloses a method for producing coal gas. The coal gas production method of this application includes the following steps: using a nitrogen generator to produce nitrogen and oxygen-rich gas; adding coal powder, water vapor, air and oxygen-rich gas produced by the nitrogen generator to the pulverized coal gasifier, and reacting to generate coal gas under high temperature and high pressure; the coal gas produced by the pulverized coal gasifier passes through a cyclone separator, a heat exchanger, a bag filter, and a desulfurization device to obtain product coal gas; the nitrogen produced by the nitrogen generator is used for the injection of the bag filter system. This application adds the oxygen-rich gas generated by the nitrogen generator to the pulverized coal gasifier, and intensifies the combustion of the pulverized coal gasifier by enriching the oxygen, which can effectively increase the calorific value of the coal gas.

[0005] For another example, the application with Chinese patent publication number CN109777521A discloses a coal gasification system and gasification process. The application includes a gasifier, a dust removal device and a fly ash burner. The air inlet end of the dust removal device is connected to the coal gas outlet of the gasifier, and the fly ash burner includes a gasifier channel, a steam channel and a pulverized coal channel; the inlet end of the gasifier channel is connected to the gas source, the inlet end of the steam channel is connected to the steam device, and the inlet end of the pulverized coal channel is connected to the discharge port of the dust removal device; the outlet ends of the gasifier channel, the steam channel and the pulverized coal channel are connected to the premixing zone of the fly ash burner, and the premixing zone is connected to the return port of the gasifier. The application can collect the fly ash in the coal gasification reaction and fully mix it with the reaction medium before returning to the gasifier, which greatly improves the reaction efficiency after the fly ash returns to the gasifier and avoids the formation of coking. However, in this application, nitrogen is also used as the injection medium.

[0006] Both of the above-mentioned documents involve technical improvements in coal gas production methods, but nitrogen is used as the injection medium in both documents, so there is still room for improvement. The industry has never stopped research on the technology of coal gas production. Summary of the invention

[0007] 1. Problems to be solved

[0008] In view of at least some of the problems existing in the above-mentioned prior art, the present invention proposes a gas production system and a gas production method, which aims to solve the problem that in the existing gas production process, additional injection medium is required for backblowing, thereby causing waste of resources and increased costs.

[0009] 2. Technical solution

[0010] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0011] A coal gas production method of the present invention comprises the following steps:

[0012] The gasifying agent and the pulverized coal enter the gasifier through their respective feed ports for gasification reaction to generate raw coal gas;

[0013] The raw coal gas undergoes preliminary gas-solid separation in the separator; the separated semi-coke enters the return device, and the separated coal gas enters the waste heat recovery device for heat exchange and cooling; the superheated steam generated during the heat exchange process is used as a gasifying agent.

[0014] The cooled coal gas enters the dust collector for gas-solid separation again to produce clean coal gas;

[0015] After the clean gas is cooled by the cooler, part of it is sent out through the first gas outlet for use, and the other part enters the compressor through the second gas outlet for pressurization to produce high-pressure gas;

[0016] The high-pressure gas is divided into two paths. One path is sent to the dust collector as the injection gas source to achieve the dust removal purpose of the dust collector.

[0017] Another high-pressure gas is sent to the return device as the return power source of the return device, and the generated gas-solid mixture is sent to the gas generator to participate in the reaction again.

[0018] In some embodiments, the high-pressure coal gas accounts for 10% to 15% of the clean coal gas.

[0019] In some embodiments, the high-pressure coal gas has a temperature of 35-45° C. and a pressure of 0.25-0.3 MPa.

[0020] In some embodiments, the separation efficiency of the separator is ≥95%, and the dust content in the clean coal gas is ≤10 mg / Nm 3 .

[0021] In some embodiments, the gasifying agent consists of air and steam.

[0022] The present invention also provides a coal gas production system, comprising a coal gas generator, a separator, a dust collector and a cooler connected in sequence, wherein the slag discharge port of the separator is connected to the coal gas generator through a material return device;

[0023] The cooler is provided with a first gas outlet and a second gas outlet; wherein,

[0024] The first gas outlet is connected to an external transmission device;

[0025] The second gas outlet is divided into two paths, one of which is connected to the dust collector for back-blowing the dust collector; the other is connected to the gas source inlet of the returner to return the gas-solid mixture in the returner to the gas generator.

[0026] In some embodiments, the second gas outlet is connected to a compressor, and the gas is transported to the dust collector and the return device after being pressurized.

[0027] In some embodiments, a waste heat recovery device is provided between the separator and the dust collector.

[0028] In some embodiments, the coal gasifier is provided with a feed port, which includes a gasifying agent inlet and a coal powder inlet.

[0029] In some embodiments, the separator is a cyclone separator, and the dust collector is a bag dust collector.

[0030] 3. Beneficial effects

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] A coal gas production method of the present invention is provided with a first coal gas outlet and a second coal gas outlet on the cooler; wherein part of the clean coal gas is sent out for use through the first coal gas outlet, and part of the coal gas is connected to the dust collector through the second coal gas outlet, and is used to back-blow the dust collector, thereby achieving the purpose of dust removal. The present invention directly uses clean coal gas as the back-blow gas source, which can save the waste of resources caused by providing additional blowing medium, and is beneficial to reducing production costs. At the same time, the slag discharge port of the separator is connected to the gas generator through a return device, and the gas source inlet of the return device is connected to the second coal gas outlet; through this design, on the one hand, clean coal gas can be used as the return power source of the return device; on the other hand, the reaction probability of solid carbon and CO2 in the coal gas is increased, which is beneficial to improve the calorific value of the coal gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a working flow chart of a coal gas production system.

[0034] In the figure: 1. Gasifier; 2. Separator; 3. Waste heat recovery device; 4. Dust collector;

[0035] 5. Cooler; 51. First gas outlet; 52. Second gas outlet; 6. Pressurizer; 7. Returner. DETAILED DESCRIPTION

[0036] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings.

[0037] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] The present invention is further described below in conjunction with specific embodiments.

[0039] Example 1

[0040] like Figure 1 As shown, a coal gas production system of this embodiment includes a coal gas generator 1, a separator 2, a dust collector 4 and a cooler 5 which are connected in sequence.

[0041] The gasifier 1 is provided with a feed port, which includes a gasifier inlet and a coal powder inlet. The gasifier and coal powder enter the gasifier 1 through their respective inlets to participate in the gasification reaction. The gasifier is composed of air and steam.

[0042] Preferably, the gasifying agent needs to be preheated before entering the gasifier 1 .

[0043] The cooler 5 is provided with a first gas outlet 51 and a second gas outlet 52. The first gas outlet 51 is connected to an external transmission device (not shown in the figure) to transmit the gas.

[0044] The second gas outlet 52 is connected to the dust collector 4 and is used for back-spraying the dust collector 4, thereby achieving the purpose of back-spraying dust removal.

[0045] Specifically in this embodiment, the separator 2 is a cyclone separator, and the dust collector 4 is a bag dust collector.

[0046] A coal gas production system of this embodiment divides the coal gas outlet into two routes, namely, a first coal gas outlet 51 and a second coal gas outlet 52, so that part of the clean coal gas can be delivered for use through the first coal gas outlet 51, and part of the coal gas can enter the dust collector 4 through the second coal gas outlet 52 as a back-blowing gas source for back-blowing and cleaning the dust collector 4. This can effectively save the waste of resources caused by providing additional blowing media, and is conducive to reducing production costs.

[0047] Example 2

[0048] A coal gas production system of this embodiment is further provided with a returner 7 on the basis of embodiment 1. The returner 7 is used to collect the solid semi-coke separated by the separator 2 and return it to the coal gasifier 1 for reaction to improve the utilization rate of coal powder.

[0049] refer to Figure 1 As shown, the feed port of the return device 7 is connected to the slag discharge port of the separator 2, and the discharge port thereof is connected to the gasifier 1.

[0050] The returner 7 is also provided with a gas source inlet, which is connected to the second gas outlet 52. The clean gas from the second gas outlet 52 is used as the power source for returning the material, and the gas-solid mixture produced in the returner 7 is sent to the gas generator 1 to participate in the reaction again.

[0051] As we all know, for the coal gasification reaction, the reaction in the gasifier is

[0052] C+O2→CO2

[0053] CO2+C→2CO

[0054] H2O+C→H2+CO

[0055] If air is used as the return or injection medium, there will be a risk of combustion or explosion. Nitrogen is usually used as the return or injection medium in the industry, which will increase the ineffective components in the gas and reduce the calorific value of the gas. However, the use of gas circulation return and injection can make the CO2 and H2O in the gas circulate and react with the carbon in the gasifier, thereby increasing the calorific value of the gas.

[0056] The second gas outlet 52 is connected to a compressor 6 , and the gas is transported to the dust collector 4 and the return device 7 after being pressurized.

[0057] Preferably, the compressor 6 is a multi-stage centrifugal compressor. The amount of pressurized gas is 10% to 15% of the clean gas, which reduces the loss of clean gas while meeting the return of the return device and the gas demand of the bag filter. At the same time, the pressure of the pressurized clean gas is controlled at 0.25 to 0.3 Mpa to meet the cleaning effect of the bag filter.

[0058] In addition, a waste heat recovery device 3 is provided between the separator 2 and the dust collector 4 to further improve the utilization rate of heat energy in the system.

[0059] A coal gas production system of this embodiment is connected with the second coal gas outlet 52 through the gas source inlet of the return device 7. On the one hand, clean coal gas can be used as the return power source of the return device 7; on the other hand, the reaction probability of solid carbon and CO2 in the coal gas is increased, which is beneficial to improve the calorific value of the coal gas.

[0060] Example 3

[0061] A coal gas production method of this embodiment includes the following steps:

[0062] The gasifying agent enters the gasifier 1 through the gasifying agent inlet, and the pulverized coal enters the gasifier 1 through the pulverized coal inlet, and both participate in the gasification reaction in the furnace body to eventually generate raw coal gas.

[0063] The reaction in the gas generator 1 is a self-heating reaction, and the heat generated by the combustion reaction in the furnace provides the heat required for gasification of the entire system.

[0064] The gasifying agent is composed of air and steam, which is preheated to 700-750°C before being introduced into the gasifier 1 to recover the heat in the system to the maximum extent, thereby reducing the degree of combustion reaction in the gasifier. The coal powder is at room temperature and is delivered to the gasifier 1 by a coal pusher.

[0065] The crude coal gas undergoes preliminary gas-solid separation in the separator 2, and the separation efficiency of the separator 2 is ≥95%. The separated semi-coke enters the return device 7 and is used as return material.

[0066] The separated coal gas enters the waste heat recovery device 3 for waste heat recovery, and the temperature of the raw coal gas is reduced to 160-180°C, while superheated steam is generated. The steam here can be used as a gasification agent and system heating, and the surplus steam can be supplied to other systems.

[0067] The cooled coal gas enters the dust collector 4 for gas-solid separation again to produce clean coal gas. The dust content of the clean coal gas after the secondary separation is ≤10mg / Nm 3 .

[0068] The clean coal gas passes through the cooler 5, where its temperature is further reduced to 35-40°C.

[0069] After cooling, part of the clean coal gas is sent out through the first coal gas outlet 51 for use; part of it enters the compressor 6 through the second coal gas outlet 52 for pressurization to produce high-pressure coal gas. At this time, the temperature of the high-temperature coal gas is 35-45°C, the pressure is 0.25-0.3Mpa, and the high-pressure coal gas accounts for 10%-15% of the total clean coal gas.

[0070] The high-pressure gas is divided into two paths. One path is sent to the dust collector 4 as a back-blow gas source of the dust collector 4, thereby achieving the purpose of cleaning the dust collector 4.

[0071] Another high-pressure coal gas is sent to the return device 7 as the return power source of the return device 7, and the generated gas-solid mixture is transported to the gas generator 1 to participate in the reaction again.

[0072] A coal gas production method of this embodiment uses high-pressure coal gas as the power source for injection and return, which saves the resource waste caused by nitrogen as the injection and return medium, and at the same time increases the reaction probability of solid carbon and CO2 in the coal gas, thereby improving the calorific value of the coal gas.

[0073] The present invention and its embodiments are described schematically above, and the description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and designs a structural method and an embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A method for producing coal gas, characterized in that: It includes the following steps: The gasifying agent and the pulverized coal enter the gasifier (1) through their respective feed ports to undergo a gasification reaction to generate a raw coal gas; The raw coal gas is initially separated into gas and solid in the separator (2); the separated semi-coke enters the return device (7), and the separated coal gas enters the waste heat recovery device (3) for heat exchange and cooling; the superheated steam generated during the heat exchange process is used as a gasifying agent. The cooled coal gas enters the dust collector (4) for gas-solid separation again to produce clean coal gas; After the clean coal gas is cooled by the cooler (5), a portion of it is sent out for use through the first coal gas outlet (51), and the other portion enters the compressor (6) through the second coal gas outlet (52) for pressurization to generate high-pressure coal gas; The high-pressure coal gas is divided into two paths, one of which is sent to the dust collector (4) as a spray gas source to achieve the dust removal purpose of the dust collector (4); Another high-pressure coal gas is sent to the return device (7) as the return power source of the return device (7), and the generated gas-solid mixture is sent to the gas generator (1) to participate in the reaction again.

2. A method for producing coal gas according to claim 1, characterized in that: The high-pressure coal gas accounts for 10% to 15% of the clean coal gas.

3. A method for producing coal gas according to claim 2, characterized in that: The temperature of the high-pressure coal gas is 35-45° C., and the pressure is 0.25-0.3 MPa.

4. A method for producing coal gas according to any one of claims 1 to 3, characterized in that: The separation efficiency of the separator (2) is ≥95%, and the dust content in the clean coal gas is ≤10mg / Nm 3 .

5. A method for producing coal gas according to claim 4, characterized in that: The gasifying agent consists of air and steam.

6. A coal gas production system, comprising a coal gas generator (1), a separator (2), a dust collector (4) and a cooler (5) connected in sequence, characterized in that: The slag discharge port of the separator (2) is connected to the gas generator (1) through a material return device (7); The cooler (5) is provided with a first gas outlet (51) and a second gas outlet (52); wherein: The first gas outlet (51) is connected to an external transmission device; The second gas outlet (52) is divided into two paths, one of which is connected to the dust collector (4) for back-blowing the dust collector (4); and the other is connected to the gas source inlet of the return device (7) for returning the gas-solid mixture in the return device (7) to the gas generator (1).

7. A coal gas production system according to claim 6, characterized in that: The second gas outlet (52) is connected to a compressor (6), and the gas is transported to the dust collector (4) and the return device (7) after being pressurized.

8. A coal gas production system according to claim 6, characterized in that: A waste heat recovery device (3) is provided between the separator (2) and the dust collector (4).

9. A coal gas production system according to any one of claims 6 to 8, characterized in that: The coal gas generator (1) is provided with a feed inlet, which includes a gasifying agent inlet and a coal powder inlet.

10. A coal gas production system according to claim 9, characterized in that: The separator (2) is a cyclone separator, and the dust collector (4) is a bag dust collector.

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