Coal mine gas extraction variable-temperature displacement concentration and power generation coupling system and method

Abstract

The invention discloses a coal mine gas extraction variable-temperature displacement concentration and power generation coupling system and method, the system comprises a gas generator, a fan, a waste heat boiler, a heat exchanger, a drying tower and a variable-temperature displacement concentration subsystem, and high-temperature flue gas generated by the gas generator passes through the waste heat boiler; flue gas discharged from the waste heat boiler enters the heat exchanger to heat air conveyed by the fan, and the heated air enters the variable temperature displacement concentration subsystem to promote desorption and regeneration of an adsorbent; the flue gas containing carbon dioxide discharged by the heat exchanger is dried and then enters a variable temperature displacement concentration subsystem to promote desorption and produce high-concentration methane; after desorption and regeneration of the adsorbent are completed, gas raw material gas is introduced into the variable temperature displacement concentration subsystem, O2 and N2 are adsorbed, and methane is concentrated; high-concentration methane can be produced in the adsorption stage and the displacement stage, and concentrated and enriched methane enters a gas generator through a product gas outlet. The system can realize efficient coupling of gas variable-temperature displacement concentration and gas power generation.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine gas extraction and concentration improvement, and particularly relates to a variable-temperature displacement concentration and power generation coupling system for coal mine extracted gas and a method for variable-temperature displacement concentration and power generation coupling of coal mine extracted gas. Background Art

[0002] Coal mine gas, also known as coalbed methane, is an important unconventional natural gas resource, and China has very rich coal mine gas reserves. Affected by mining activities, there are a large number of air leakage fissures in underground coal seams. Under the action of negative pressure extraction, a large amount of air enters the extraction boreholes along the fissures, resulting in generally low concentrations of underground gas extraction. At present, low-concentration gas with a methane concentration higher than 8% can be utilized through internal combustion engine power generation technology, but gas with a methane concentration lower than 8% is difficult to utilize and is directly discharged into the atmosphere, causing huge energy waste and atmospheric greenhouse effects. In addition, low-concentration gas with a methane concentration of 5% - 16% has explosion hazards and has potential safety hazards of combustion and explosion during the transmission process of the gas extraction pipeline. Taking corresponding technical measures to increase the concentration of underground extracted gas is beneficial to improving the gas utilization rate, thereby avoiding the waste of clean energy and the emission of methane greenhouse gases. To improve the utilization value of low-concentration gas, currently, a gas concentration improvement system is mainly established on the ground to increase the methane concentration in the gas. For example, "A method for separating and purifying methane in coalbed methane in a mine area by using pressure swing adsorption" disclosed in Chinese Patent Application No. CN103205297A, "Enriching methane in coal mine gas by pressure swing adsorption" disclosed in Chinese Patent Application No. CN85103557, and "A method for pressure swing adsorption fractional concentration of low-concentration gas" disclosed in Chinese Patent Application No. CN101596391A all establish large-scale centralized pressure swing adsorption systems on the ground, and configure additional booster pumps or vacuum pumps to provide pressure swing adsorption power. This method has huge investment, high energy consumption and poor fault tolerance. A failure in a certain part of the system will cause the entire system to shut down, and there are relatively high safety hazards in treating a large amount of low-concentration gas concentrated in a small area.

[0003] In contrast, although the traditional pressure swing adsorption technology can effectively concentrate gas, its energy consumption is relatively high, resulting in a relatively low overall efficiency. After the adsorbent is saturated, this method requires a high-pressure desorption gas flow to regenerate the adsorbent, which not only consumes energy but also adds additional operation steps and equipment, affecting the overall operation efficiency of the system. Therefore, there is an urgent need for a method that can both increase the gas concentration and generate electricity efficiently to make full use of gas resources and reduce the demand for additional energy. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, the first object of the present invention is to provide a coupled system for variable-temperature displacement enrichment and power generation of coal mine gas drainage, which can achieve efficient coupling of variable-temperature displacement enrichment and power generation of gas, eliminate additional energy input, and effectively solve the problems of difficult effective utilization of ultra-low-concentration gas and high energy consumption of traditional pressure swing adsorption for gas enrichment.

[0005] The second object of the present invention is to provide a method for coupled variable-temperature displacement enrichment and power generation of coal mine gas drainage.

[0006] To achieve the above object, the first aspect of the embodiments of the present invention provides a coupled system for variable-temperature displacement enrichment and power generation of coal mine gas drainage, including: a gas generator, a fan, a waste heat boiler, a heat exchanger, a drying tower, and a variable-temperature displacement enrichment subsystem. Among them, the flue gas pipeline of the gas generator is connected to the flue gas inlet of the waste heat boiler, the flue gas outlet of the waste heat boiler is connected to the heat source inlet of the heat exchanger, the heat source outlet of the heat exchanger is connected to the inlet of the drying tower, the outlet of the drying tower is connected to the displacement gas inlet of the variable-temperature displacement enrichment subsystem, the cold source inlet of the heat exchanger is connected to the fan, the cold source outlet of the heat exchanger is connected to the regeneration gas inlet of the variable-temperature displacement enrichment subsystem, the gas raw material gas inlet of the variable-temperature displacement enrichment subsystem is connected to the coal mine gas output pipeline, and the product gas outlet of the variable-temperature displacement enrichment subsystem is connected to the intake pipeline of the gas generator;

[0007] The high-temperature flue gas generated by the gas generator generates steam through the waste heat boiler for heating; the flue gas discharged from the waste heat boiler enters the heat exchanger to heat the air conveyed by the fan, and the heated air enters the variable-temperature displacement enrichment subsystem to promote the desorption and regeneration of the adsorbent in the variable-temperature displacement enrichment subsystem; the flue gas containing carbon dioxide discharged from the heat exchanger enters the variable-temperature displacement enrichment subsystem after being dried by the drying tower to displace methane and / or oxygen adsorbed by the adsorbent, producing high-concentration methane; after the desorption and regeneration of the adsorbent is completed, gas raw material gas is introduced into the variable-temperature displacement enrichment subsystem, and oxygen and / or nitrogen in the gas raw material gas are selectively adsorbed by the adsorbent to enrich methane; the high-concentration methane produced in the displacement and adsorption stages enters the gas generator through the product gas outlet to enable the gas generator to generate electricity.

[0008] In addition, the coupled system for variable-temperature displacement enrichment and power generation of coal mine gas drainage according to the above embodiments of the present invention may also have the following additional technical features:

[0009] According to an embodiment of the present invention, the temperature-variable displacement enrichment subsystem includes: a first adsorption tower and a second adsorption tower. Adsorbents are provided inside both the first adsorption tower and the second adsorption tower. Among them, the bottom of the first adsorption tower is respectively connected to the gas raw material gas inlet, the regeneration gas inlet, and the displacement gas inlet through pipelines. A first gas inlet valve for gas is provided on the pipeline between the gas raw material gas inlet and the first adsorption tower. A first regeneration gas inlet valve is provided on the pipeline between the regeneration gas inlet and the first adsorption tower. A first displacement gas inlet valve is provided on the pipeline between the displacement gas inlet and the first adsorption tower. The bottom of the second adsorption tower is respectively connected to the gas raw material gas inlet, the regeneration gas inlet, and the displacement gas inlet through pipelines. A second gas inlet valve for gas is provided on the pipeline between the gas raw material gas inlet and the second adsorption tower. A second regeneration gas inlet valve is provided on the pipeline between the regeneration gas inlet and the second adsorption tower. A second displacement gas inlet valve is provided on the pipeline between the displacement gas inlet and the second adsorption tower. The top of the first adsorption tower is respectively connected to the product gas outlet and the exhaust gas outlet through pipelines. A first product gas control valve is provided on the pipeline between the product gas outlet and the first adsorption tower. A first exhaust valve is provided on the pipeline between the exhaust gas outlet and the first adsorption tower. The top of the second adsorption tower is respectively connected to the product gas outlet and the exhaust gas outlet through pipelines. A second product gas control valve is provided on the pipeline between the product gas outlet and the second adsorption tower. A second exhaust valve is provided on the pipeline between the exhaust gas outlet and the second adsorption tower.

[0010] According to an embodiment of the present invention, the cycle process of the temperature-variable displacement enrichment subsystem for enriching the coal mine drainage gas by temperature-variable displacement includes:

[0011] Step S1, the first adsorption tower adsorbs and produces gas, and the second adsorption tower is desorbed at high temperature: Open the first gas inlet valve for gas and the first product gas control valve. The coal mine drainage gas is introduced into the first adsorption tower from the bottom at a preset pressure. Oxygen and nitrogen are adsorbed on the adsorbent, and the enriched methane product gas flows out from the top of the first adsorption tower. At the same time, open the second regeneration gas inlet valve and the second exhaust valve. High-temperature air enters the second adsorption tower to heat the adsorbent bed layer. The oxygen and / or nitrogen adsorbed on the adsorbent bed layer is desorbed at high temperature and discharged from the second adsorption tower. After the high-temperature desorption is completed in the second adsorption tower, close the regeneration gas inlet valve and the second exhaust valve. Among them, the range of the preset pressure is 3-10 kPa;

[0012] Step S2, the first adsorption tower adsorbs to produce gas, and the second adsorption tower displaces and desorbs to produce gas: The enriched methane product gas is produced at the top of the first adsorption tower. After the first adsorption tower finishes adsorbing and producing gas, control the first gas intake valve and the first gas production control valve to close; at the same time, open the second displacement gas intake valve and the second gas production control valve. The flue gas containing carbon dioxide enters the second adsorption tower. Under the displacement action of carbon dioxide, the adsorbed methane and oxygen on the adsorbent are further desorbed and discharged from the second adsorption tower. After the displacement is completed, close the second displacement gas intake valve and the second gas production control valve;

[0013] Step S3, the first adsorption tower is desorbed at high temperature, and the second adsorption tower adsorbs to produce gas: Open the first regeneration gas intake valve and the first exhaust valve. High-temperature air enters the first adsorption tower to heat the adsorbent bed layer. The adsorbed oxygen and / or nitrogen are desorbed at high temperature and discharged from the first adsorption tower. After the first adsorption tower finishes desorbing at high temperature, close the first regeneration gas intake valve; at the same time, open the second gas intake valve for coal mine drainage gas and the second gas production control valve. The coal mine drainage gas is introduced into the second adsorption tower from the bottom under a preset pressure. Oxygen and nitrogen are adsorbed on the adsorbent, and the enriched methane product gas flows out from the top of the second adsorption tower;

[0014] Step S4, the first adsorption tower displaces and desorbs to produce gas, and the second adsorption tower adsorbs to produce gas: Open the first displacement gas intake valve and the first gas production control valve. The flue gas containing carbon dioxide enters the first adsorption tower. Under the displacement action of carbon dioxide, the adsorbed methane and oxygen on the adsorbent are further desorbed and discharged from the first adsorption tower. After the displacement is completed, close the first displacement gas intake valve and the first gas production control valve; The enriched methane product gas is produced at the top of the second adsorption tower. After the second adsorption tower finishes adsorbing and producing gas, close the second gas intake valve and the second gas production control valve.

[0015] According to an embodiment of the present invention, the external parts of the regeneration gas pipeline, the first regeneration gas intake valve, the second regeneration gas intake valve, the first adsorption tower and the second adsorption tower are all wrapped with heat-insulating and heat-preserving materials.

[0016] According to an embodiment of the present invention, the adsorbent filled in the first adsorption tower and the second adsorption tower includes any one or more of carbon molecular sieve, zeolite molecular sieve, and activated carbon.

[0017] According to an embodiment of the present invention, the drying tower is filled with a desiccant, and the desiccant includes any one or more of activated alumina, silica gel, and calcium chloride.

[0018] According to an embodiment of the present invention, the relative humidity of the flue gas after passing through the drying tower is lower than 10%.

[0019] According to an embodiment of the present invention, the concentration of methane in the coal mine gas drainage is 2% to 8%.

[0020] According to an embodiment of the present invention, the temperature of the flue gas output by the gas generator is 150°C to 200°C after passing through the waste heat boiler, and the heat exchanger heats the air conveyed by the fan to 60°C to 120°C.

[0021] To achieve the above object, a method for coupling the variable temperature displacement enrichment and power generation of coal mine gas drainage of the system in the above embodiment is proposed in the second aspect embodiment of the present invention. The method includes:

[0022] The high-temperature flue gas generated by the gas generator generates steam through the waste heat boiler;

[0023] The flue gas discharged from the waste heat boiler enters the heat exchanger to heat the air conveyed by the fan. The heated air enters the variable temperature displacement enrichment subsystem to promote the desorption and regeneration of the adsorbent in the variable temperature displacement enrichment subsystem;

[0024] The flue gas containing carbon dioxide discharged from the heat exchanger enters the variable temperature displacement enrichment subsystem after being dried by the drying tower to displace methane and / or oxygen adsorbed by the adsorbent;

[0025] After the desorption and regeneration of the adsorbent is completed, raw gas is introduced into the variable temperature displacement enrichment subsystem. Oxygen and / or nitrogen in the raw gas are selectively adsorbed by the adsorbent to concentrate methane;

[0026] The concentrated methane enters the gas generator through the product gas outlet to enable the gas generator to generate electricity.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the present invention, the high-temperature flue gas generated by the gas generator is heated by the waste heat boiler to generate steam, and then enters the heat exchanger to heat the air. After increasing the air temperature, it enters the adsorption tower to drive the high-temperature desorption and regeneration of oxygen and / or nitrogen adsorbents therein. The flue gas containing carbon dioxide also enters the adsorption tower after drying treatment, and the displacement effect of carbon dioxide is used to further promote the desorption of methane and / or oxygen, producing high-concentration methane; subsequently, low-concentration gas is introduced, and oxygen and / or nitrogen therein are adsorbed by the adsorbent, while the high-concentration methane in the gas is concentrated into the high-concentration methane product gas at the top of the adsorption tower. High-concentration methane can be produced in both the displacement desorption and adsorption stages, which can be used for power generation by the gas generator, thereby realizing the efficient coupling of variable temperature displacement enrichment and power generation of gas, eliminating the need for additional energy input, and effectively solving the problems of difficult effective utilization of ultra-low-concentration gas and high energy consumption of traditional pressure swing adsorption for gas enrichment.

[0029] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a schematic structural diagram of a variable-temperature displacement enrichment and power generation coupling system for coal mine gas drainage according to an embodiment of the present invention;

[0031] Figure 2 FIG. is a schematic diagram showing the concentration changes of the produced gas O2, CH4, and CO2 during the adsorption stage according to an embodiment of the present invention;

[0032] Figure 3 FIG. is a schematic diagram showing the concentration changes of the produced gas O2, CH4, and CO2 during the displacement stage according to an embodiment of the present invention.

[0033] REFERENCE SIGNS:

[0034] 1, gas generator; 2, fan; 3, waste heat boiler; 4, heat exchanger; 5, drying tower; 6, variable-temperature displacement enrichment subsystem; 61, first adsorption tower; 62, second adsorption tower; In-1, gas raw material gas inlet; In-2, regeneration gas inlet; In-3, displacement gas inlet; Out-1, product gas outlet; Out-2, exhaust gas outlet; I-1, first gas inlet valve; I-2, first regeneration gas inlet valve; I-3, first displacement gas inlet valve; I-4, first gas production control valve; I-5, first exhaust valve; II-1, second gas inlet valve; II-2, second regeneration gas inlet valve; II-3, second displacement gas inlet valve; II-4, second gas production control valve; II-5, second exhaust valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0036] The variable-temperature displacement enrichment and power generation coupling system and the variable-temperature displacement enrichment and power generation coupling method for coal mine gas drainage proposed by the embodiments of the present invention will be described below with reference to the drawings.

[0037] It may include: a gas generator 1, a fan 2, a waste heat boiler 3, a heat exchanger 4, a drying tower 5, and a variable-temperature displacement enrichment subsystem 6.

[0038] Among them, the exhaust gas pipeline of the gas generator 1 is connected to the flue gas inlet of the waste heat boiler 3, the flue gas outlet of the waste heat boiler 3 is connected to the heat source inlet of the heat exchanger 4, the heat source outlet of the heat exchanger 4 is connected to the inlet of the drying tower 5, the outlet of the drying tower 5 is connected to the displacement gas inlet In-3 of the variable temperature displacement concentration subsystem 6, the cold source inlet of the heat exchanger 4 is connected to the fan 2, the cold source outlet of the heat exchanger 4 is connected to the regeneration gas inlet In-2 of the variable temperature displacement concentration subsystem 6, the gas raw material inlet In-1 of the variable temperature displacement concentration subsystem 6 is connected to the coal mine gas output pipeline, and the product gas outlet Out-1 of the variable temperature displacement concentration subsystem 6 is connected to the intake pipeline of the gas generator 1.

[0039] Specifically, the high-temperature flue gas generated by the gas generator 1 generates steam through the waste heat boiler 3 for heating; the flue gas discharged from the waste heat boiler 3 enters the heat exchanger 4 to heat the air conveyed by the fan 2, and the heated air enters the variable temperature displacement concentration subsystem 6 to promote the desorption and regeneration of the adsorbent in the variable temperature displacement concentration subsystem 6; the flue gas containing carbon dioxide discharged from the heat exchanger 4 enters the variable temperature displacement concentration subsystem 6 after being dried by the drying tower 5 to displace methane and / or oxygen adsorbed by the adsorbent, producing high-concentration methane; after the desorption and regeneration of the adsorbent is completed, gas raw material gas is introduced into the variable temperature displacement concentration subsystem 6, and oxygen and / or nitrogen in the gas raw material gas are selectively adsorbed by the adsorbent to concentrate methane; the high-concentration methane produced in the displacement and adsorption stages enters the gas generator 1 through the product gas outlet to enable the gas generator 1 to generate electricity. Among them, the concentration range of the high-concentration methane is 9-20%.

[0040] Specifically, the gas generator 1 uses the concentrated and enriched methane to generate electricity. When the gas generator 1 operates, it will generate high-temperature flue gas, and these flue gases first enter the waste heat boiler 3 to generate steam using its heat. Subsequently, the flue gas discharged from the waste heat boiler 3 flows into the heat exchanger 4. The temperature of the flue gas discharged from the waste heat boiler 3 is 150°C - 200°C, and it exchanges heat with the air conveyed by the fan 2 to heat the air, heating the air conveyed by the fan 2 to 60°C - 120°C. The heated air is sent into the variable temperature displacement concentration subsystem 6 to help the adsorbent in it complete the desorption and regeneration process. At the same time, the flue gas containing carbon dioxide discharged from the heat exchanger 4 also enters the variable temperature displacement concentration subsystem 6 after being dried by the drying tower 5, and is used to displace oxygen and / or nitrogen adsorbed on the adsorbent. Among them, the relative humidity of the flue gas is less than 10% after passing through the drying tower 5. When the desorption and regeneration of the adsorbent is completed, gas raw material gas is introduced into this subsystem, and oxygen and / or nitrogen in the gas raw material gas will be selectively adsorbed by the adsorbent, so that methane can be concentrated. Among them, the gas raw material gas is coal mine extracted gas, and the methane concentration in it is 2% - 8%. Finally, the concentrated and enriched methane returns to the gas generator 1 through the product gas outlet and continues to be used for power generation.

[0041] According to an embodiment of the present invention, as Figure 1 shown, the temperature-variable displacement concentration subsystem 6 includes: a first adsorption tower 61 and a second adsorption tower 62. Adsorbents are provided inside both the first adsorption tower 61 and the second adsorption tower 62. Among them, the bottom of the first adsorption tower 61 is connected through pipelines to a gas raw material gas inlet In-1, a regeneration gas inlet In-2, and a displacement gas inlet In-3 respectively. A first gas inlet valve I-1 is provided on the pipeline between the gas raw material gas inlet In-1 and the first adsorption tower 61, a first regeneration gas inlet valve I-2 is provided on the pipeline between the regeneration gas inlet In-2 and the first adsorption tower 61, and a first displacement gas inlet valve I-3 is provided on the pipeline between the displacement gas inlet In-3 and the first adsorption tower 61; the bottom of the second adsorption tower 62 is connected through pipelines to the gas raw material gas inlet In-1, the regeneration gas inlet In-2, and the displacement gas inlet In-3 respectively. A second gas inlet valve II-1 is provided on the pipeline between the gas raw material gas inlet In-1 and the second adsorption tower 62, a second regeneration gas inlet valve II-2 is provided on the pipeline between the regeneration gas inlet In-2 and the second adsorption tower 62, and a second displacement gas inlet valve II-3 is provided on the pipeline between the displacement gas inlet In-3 and the second adsorption tower 62; the top of the first adsorption tower 61 is connected through pipelines to a product gas outlet Out-1 and an exhaust gas outlet Out-2 respectively. A first product gas control valve I-4 is provided on the pipeline between the product gas outlet Out-1 and the first adsorption tower 61, and a first exhaust valve I-5 is provided on the pipeline between the exhaust gas outlet Out-2 and the first adsorption tower 61; the top of the second adsorption tower 62 is connected through pipelines to the product gas outlet Out-1 and the exhaust gas outlet Out-2 respectively. A second product gas control valve II-4 is provided on the pipeline between the product gas outlet Out-1 and the second adsorption tower 62, and a second exhaust valve II-5 is provided on the pipeline between the exhaust gas outlet Out-2 and the second adsorption tower 62.

[0042] It should be noted that in the temperature-variable displacement concentration subsystem 6 of the present invention, multiple adsorption towers can be provided. The setting of the first adsorption tower 61 and the second adsorption tower 62 in the temperature-variable displacement concentration subsystem 6 is only for illustrative purposes and should not be construed as a limitation to this application. When multiple adsorption towers are provided in the temperature-variable displacement concentration subsystem 6, multiple adsorption towers can be connected through corresponding components according to the relevant descriptions in the above embodiments, which will not be elaborated here.

[0043] Furthermore, according to an embodiment of the present invention, the cycle process of the temperature-variable displacement concentration subsystem 6 for performing temperature-variable displacement concentration on the coal mine extracted gas includes:

[0044] Step S1, the first adsorption tower 61 adsorbs to produce gas, and the second adsorption tower 62 undergoes high-temperature desorption: Open the first gas intake valve I-1 and the first gas production control valve I-4, and introduce the coal mine extracted gas into the first adsorption tower 61 from the bottom under a preset pressure. Oxygen and nitrogen are adsorbed on the adsorbent, and the enriched methane product gas flows out from the top of the first adsorption tower 61. At the same time, open the second regeneration gas intake valve II-2 and the second exhaust valve II-5. High-temperature air enters the second adsorption tower 62 to heat the adsorbent bed layer. The adsorbed oxygen and / or nitrogen are desorbed at high temperature and discharged from the second adsorption tower 62. After the high-temperature desorption in the second adsorption tower 62 is completed, close the second regeneration gas intake valve II-2 and the second exhaust valve II-5. Among them, the range of the preset pressure is 3-10 kPa;

[0045] Step S2, the first adsorption tower 61 adsorbs to produce gas, and the second adsorption tower 62 undergoes displacement desorption: The enriched methane product gas is produced at the top of the first adsorption tower 61. After the first adsorption tower 61 completes gas production by adsorption, control the first gas intake valve I-1 and the first gas production control valve I-4 to close. At the same time, open the second displacement gas intake valve II-3, and the flue gas containing carbon dioxide enters the second adsorption tower 62. Under the displacement action of carbon dioxide, the adsorbed oxygen and nitrogen on the adsorbent are further desorbed and discharged from the second adsorption tower 62. After the displacement is completed, close the second displacement gas intake valve II-3 and the second gas production control valve II-4;

[0046] Step S3, the first adsorption tower 61 undergoes high-temperature desorption, and the second adsorption tower 62 adsorbs to produce gas: Open the first regeneration gas intake valve I-2 and the first exhaust valve I-5. High-temperature air enters the first adsorption tower 61 to heat the adsorbent bed layer. The adsorbed oxygen and / or nitrogen are desorbed at high temperature and discharged from the first adsorption tower 61. After the first adsorption tower 61 completes high-temperature desorption, close the first regeneration gas intake valve I-2. At the same time, open the second gas intake valve II-1 and the second gas production control valve II-4, and introduce the coal mine extracted gas into the second adsorption tower 62 from the bottom under a preset pressure. Oxygen and nitrogen are adsorbed on the adsorbent, and the enriched methane product gas flows out from the top of the second adsorption tower 62;

[0047] Step S4, the first adsorption tower 61 undergoes displacement desorption to produce gas, and the second adsorption tower 62 adsorbs to produce gas: Open the first displacement gas intake valve I-3 and the first gas production control valve I-4. The flue gas containing carbon dioxide enters the first adsorption tower 61. Under the displacement action of carbon dioxide, the adsorbed methane and oxygen on the adsorbent are further desorbed and discharged from the first adsorption tower 61. After the displacement is completed, close the first displacement gas intake valve I-3 and the first gas production control valve I-4. The enriched methane product gas is produced at the top of the second adsorption tower 62. After the second adsorption tower 62 completes gas production by adsorption, close the second gas intake valve II-1 and the second gas production control valve II-4.

[0048] Figure 2 and Figure 3 are the experimental results of temperature-variable displacement enrichment of low-concentration gas. As Figure 2 shown, when the raw gas is low-concentration gas with 5% CH4, the concentration change of the gas produced in the adsorption stage is presented. It can be seen from this figure that the CH4 concentration can be increased from 5% to 12.5%. Figure 3 After desorption at 100 °C, the concentration change of the gas produced in the CO2 displacement stage is shown. It can be seen from this figure that the highest CH4 concentration in the produced gas can reach 20%. The above experimental results show that high-concentration CH4 product gas can be produced in both the adsorption and displacement stages of the temperature-variable displacement of the present invention.

[0049] According to an embodiment of the present invention, the external parts of the regeneration gas pipeline, the first regeneration gas inlet valve I-2, the second regeneration gas inlet valve II-2, the first adsorption tower 61, and the second adsorption tower 62 are all wrapped with heat-insulating and heat-preserving materials. Thus, the system can be heat-insulated to prevent heat loss of the system.

[0050] According to an embodiment of the present invention, the adsorbent filled in the first adsorption tower 61 and the second adsorption tower 62 includes any one or more of carbon molecular sieve, zeolite molecular sieve, and activated carbon. Carbon molecular sieve, zeolite molecular sieve, activated carbon, etc. can preferentially adsorb non-methane gases.

[0051] According to an embodiment of the present invention, a desiccant is filled in the drying tower 5, and the desiccant includes any one or more of activated alumina, silica gel, and calcium chloride.

[0052] Corresponding to the above embodiment, the present invention also provides a method for coupling temperature-variable displacement enrichment of coal mine extracted gas with power generation.

[0053] The method for coupling temperature-variable displacement enrichment of coal mine extracted gas with power generation according to the embodiment of the present invention based on the system of the foregoing embodiment may include the following steps:

[0054] High-temperature flue gas generated by a gas generator generates steam through a waste heat boiler;

[0055] The flue gas discharged from the waste heat boiler enters a heat exchanger to heat the air conveyed by a fan, and the heated air enters the temperature-variable displacement enrichment subsystem to promote desorption and regeneration of the adsorbent in the temperature-variable displacement enrichment subsystem;

[0056] The flue gas containing carbon dioxide discharged from the heat exchanger enters the temperature-variable displacement enrichment subsystem after being dried by the drying tower to displace methane and / or oxygen adsorbed by the adsorbent;

[0057] After the desorption and regeneration of the adsorbent are completed, raw gas is introduced into the temperature-variable displacement enrichment subsystem, and oxygen and / or nitrogen in the raw gas are selectively adsorbed by the adsorbent to enrich methane;

[0058] The concentrated methane enters the gas generator through the product gas outlet, enabling the gas generator to generate electricity.

[0059] It should be noted that for the details not disclosed in the method for coupling temperature-variable displacement enrichment and power generation of coal mine extracted gas in the embodiments of the present invention, please refer to the details disclosed in the system for coupling temperature-variable displacement enrichment and power generation of coal mine extracted gas in the embodiments of the present invention, which will not be elaborated here specifically.

[0060] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0061] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0062] In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A variable-temperature displacement enrichment and power generation coupling system for coal mine gas drainage, characterized in that, Including: A gas generator, a fan, a waste heat boiler, a heat exchanger, a drying tower, and a temperature-variable displacement enrichment subsystem. Among them, The exhaust gas pipeline of the gas generator is connected to the flue gas inlet of the waste heat boiler. The flue gas outlet of the waste heat boiler is connected to the heat source inlet of the heat exchanger. The heat source outlet of the heat exchanger is connected to the inlet of the drying tower. The outlet of the drying tower is connected to the displacement gas inlet of the temperature-variable displacement enrichment subsystem. The cold source inlet of the heat exchanger is connected to the fan. The cold source outlet of the heat exchanger is connected to the regeneration gas inlet of the temperature-variable displacement enrichment subsystem. The gas raw material gas inlet of the temperature-variable displacement enrichment subsystem is connected to the coal mine gas output pipeline. The product gas outlet of the temperature-variable displacement enrichment subsystem is connected to the intake pipeline of the gas generator; The high-temperature flue gas generated by the gas generator generates steam through the waste heat boiler for heating. The flue gas discharged from the waste heat boiler enters the heat exchanger to heat the air conveyed by the fan. The heated air enters the temperature-variable displacement enrichment subsystem to promote the desorption and regeneration of the adsorbent in the temperature-variable displacement enrichment subsystem. The flue gas containing carbon dioxide discharged from the heat exchanger enters the temperature-variable displacement enrichment subsystem after being dried by the drying tower to displace methane and / or oxygen adsorbed by the adsorbent to produce high-concentration methane. After the desorption and regeneration of the adsorbent are completed, gas raw material gas is introduced into the temperature-variable displacement enrichment subsystem, and oxygen and / or nitrogen in the gas raw material gas are selectively adsorbed by the adsorbent to concentrate methane. The high-concentration methane produced in the displacement and adsorption stages enters the gas generator through the product gas outlet to enable the gas generator to generate electricity.

2. The coal mine gas drainage variable temperature displacement enrichment and power generation coupling system according to claim 1, wherein, The temperature-variable displacement enrichment subsystem includes: a first adsorption tower and a second adsorption tower. Adsorbents are provided inside both the first adsorption tower and the second adsorption tower. Among them, The bottom of the first adsorption tower is respectively connected to the gas raw material gas inlet, the regeneration gas inlet, and the displacement gas inlet through pipelines. A first gas inlet valve for gas is provided on the pipeline between the gas raw material gas inlet and the first adsorption tower. A first regeneration gas inlet valve is provided on the pipeline between the regeneration gas inlet and the first adsorption tower. A first displacement gas inlet valve is provided on the pipeline between the displacement gas inlet and the first adsorption tower; The bottom of the second adsorption tower is respectively connected to the gas raw material gas inlet, the regeneration gas inlet, and the displacement gas inlet through pipelines. A second gas inlet valve for gas is provided on the pipeline between the gas raw material gas inlet and the second adsorption tower. A second regeneration gas inlet valve is provided on the pipeline between the regeneration gas inlet and the second adsorption tower. A second displacement gas inlet valve is provided on the pipeline between the displacement gas inlet and the second adsorption tower; The top of the first adsorption tower is respectively connected to the product gas outlet and the discharge gas outlet through pipelines. A first product gas control valve is provided on the pipeline between the product gas outlet and the first adsorption tower. A first exhaust valve is provided on the pipeline between the discharge gas outlet and the first adsorption tower; The top of the second adsorption tower is respectively connected to the product gas outlet and the exhaust gas outlet through pipelines. A second product gas control valve is provided on the pipeline between the product gas outlet and the second adsorption tower, and a second exhaust valve is provided on the pipeline between the exhaust gas outlet and the second adsorption tower.

3. The coal mine gas drainage variable-temperature displacement enrichment and power generation coupling system according to claim 2, wherein The cyclic process of the temperature-variable displacement enrichment subsystem for enriching coal mine extracted gas by temperature-variable displacement includes: Step S1, the first adsorption tower adsorbs and produces gas, and the second adsorption tower desorbs at high temperature: Open the first gas inlet valve and the first product gas control valve, and introduce coal mine extracted gas into the first adsorption tower from the bottom under a preset pressure. Oxygen and nitrogen are adsorbed on the adsorbent, and the enriched methane product gas flows out from the top of the first adsorption tower. At the same time, open the second regeneration gas inlet valve and the second exhaust valve, and high-temperature air enters the second adsorption tower to heat the adsorbent bed layer. The oxygen and / or nitrogen adsorbed on the adsorbent bed layer desorbs at high temperature and is discharged from the second adsorption tower. After the high-temperature desorption of the second adsorption tower is completed, close the regeneration gas inlet valve and the second exhaust valve. Among them, the range of the preset pressure is 3-10 kPa. Step S2, the first adsorption tower adsorbs and produces gas, and the second adsorption tower desorbs and produces gas by displacement: The enriched methane product gas is produced from the top of the first adsorption tower. After the first adsorption tower completes the adsorption and gas production, control the first gas inlet valve and the first product gas control valve to close. At the same time, open the second displacement gas inlet valve and the second product gas control valve, and the flue gas containing carbon dioxide enters the second adsorption tower. Under the displacement action of carbon dioxide, the methane and oxygen adsorbed by the adsorbent are further desorbed and discharged from the second adsorption tower. After the displacement is completed, close the second displacement gas inlet valve and the second product gas control valve. Step S3, the first adsorption tower desorbs at high temperature, and the second adsorption tower adsorbs and produces gas: Open the first regeneration gas inlet valve and the first exhaust valve, and high-temperature air enters the first adsorption tower to heat the adsorbent bed layer. The adsorbed oxygen and / or nitrogen desorbs at high temperature and is discharged from the first adsorption tower. After the high-temperature desorption of the first adsorption tower is completed, close the first regeneration gas inlet valve. At the same time, open the second gas inlet valve and the second product gas control valve, and introduce coal mine extracted gas into the second adsorption tower from the bottom under a preset pressure. Oxygen and nitrogen are adsorbed on the adsorbent, and the enriched methane product gas flows out from the top of the second adsorption tower. Step S4, the first adsorption tower desorbs and produces gas by displacement, and the second adsorption tower adsorbs and produces gas: Open the first displacement gas inlet valve and the first product gas control valve, and the flue gas containing carbon dioxide enters the first adsorption tower. Under the displacement action of carbon dioxide, the methane and oxygen adsorbed by the adsorbent are further desorbed and discharged from the first adsorption tower. After the displacement is completed, close the first displacement gas inlet valve and the first product gas control valve. The enriched methane product gas is produced from the top of the second adsorption tower. After the second adsorption tower completes the adsorption and gas production, close the second gas inlet valve and the second product gas control valve.

4. The coal mine gas drainage variable-temperature displacement enrichment and power generation coupling system according to claim 2, wherein, The external parts of the regeneration gas transmission pipeline, the first regeneration gas inlet valve, the second regeneration gas inlet valve, the first adsorption tower and the second adsorption tower are all wrapped with heat-insulating and heat-preserving materials.

5. The coal mine gas drainage variable temperature displacement enrichment and power generation coupling system according to claim 2, characterized in that, The adsorbent filled in the first adsorption tower and the second adsorption tower includes any one or more of carbon molecular sieve, zeolite molecular sieve, and activated carbon.

6. The coal mine gas drainage variable temperature displacement enrichment and power generation coupling system according to claim 1, wherein The drying tower is filled with a desiccant, and the desiccant includes any one or more of activated alumina, silica gel, and calcium chloride.

7. The temperature-variable displacement enrichment and power generation coupling system for coal mine gas drainage according to claim 1, characterized in that The relative humidity of the flue gas is lower than 10% after passing through the drying tower.

8. The coal mine gas drainage variable-temperature displacement enrichment and power generation coupling system according to claim 1, wherein The concentration of methane in the coal mine extracted gas is 2% - 8%.

9. The coal mine gas drainage variable temperature displacement enrichment and power generation coupling system according to claim 1, characterized in that The temperature of the flue gas output by the gas generator is 150°C - 200°C after passing through the waste heat boiler, and the heat exchanger heats the air transported by the fan to 60°C - 120°C.

10. A method for coupling temperature-variable displacement enrichment and power generation of coal mine gas drainage based on the system described in any one of claims 1 to 9, characterized in that, The method includes: The high-temperature flue gas generated by the gas generator generates steam through the waste heat boiler; The flue gas discharged from the waste heat boiler enters the heat exchanger to heat the air transported by the fan, and the heated air enters the temperature-variable displacement enrichment subsystem to promote the desorption and regeneration of the adsorbent in the temperature-variable displacement enrichment subsystem; The carbon dioxide-containing flue gas discharged from the heat exchanger enters the temperature-variable displacement enrichment subsystem after being dried by the drying tower to displace the methane and / or oxygen adsorbed by the adsorbent; After the desorption and regeneration of the adsorbent is completed, the gas raw material gas is introduced into the temperature-variable displacement enrichment subsystem, and the oxygen and / or nitrogen in the gas raw material gas are selectively adsorbed by the adsorbent to enrich methane; The enriched methane enters the gas generator through the product gas outlet to enable the gas generator to generate electricity.

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