Methods and devices for the cascade utilization of waste heat from coal mine gas power generation

Abstract

This invention belongs to the field of waste heat utilization technology in mine gas power generation, and relates to a method and apparatus for the cascade utilization of waste heat from mine gas power generation flue gas. The apparatus includes a primary heat exchanger, a primary closed-loop water system, a secondary heat exchanger, a tap water supply device, a conversion and heating device, a secondary closed-loop water system, mine auxiliary shaft heating equipment, and a heat source regulating and transferring station. The method for the cascade utilization of waste heat from mine gas power generation flue gas includes steps such as primary heat exchange, secondary heat exchange, and conversion and heating. The method or apparatus provided by this invention can efficiently recover waste heat from the high-temperature flue gas of mine gas generator sets. The recovered heat energy is first used to heat the mine auxiliary shaft and then to provide hot water for bathing centers, achieving efficient cascade utilization of flue gas waste heat. This ensures complete recovery and no waste of the recovered heat energy, achieving full utilization of waste energy and significant energy saving and emission reduction benefits.

Description

Technical Field

[0001] This invention belongs to the field of waste heat utilization technology in mine gas power generation, specifically, it relates to a method and device for cascade utilization of waste heat from mine gas power generation flue gas. Background Technology

[0002] Coalbed methane, commonly known as "gas," is mainly composed of CH4 (methane) and is a by-product gas primarily found in coal mines. It is a high-calorific-value, pollution-free new energy source, often used for combustion in mine gas generator sets. During operation, mine gas generator sets emit high-temperature flue gas with significant waste heat content. Direct emission would result in substantial heat loss. Conventional methods for utilizing this waste heat primarily involve heat exchangers installed within the flue to exchange heat between the flue gas and water. This heated tap water is then mixed with cold water for use in bathhouses. However, this process is problematic. Firstly, the poor quality of tap water can cause scale buildup on the heat exchanger's inner wall after heating, affecting its safe operating cycle and heat exchange efficiency. Secondly, the hot water supply is unstable due to variations in generator load and operational stability. Low generator load or shutdown for maintenance significantly impacts the hot water supply, while full-load operation results in a large volume of hot water, leading to unused hot water in the mine bathhouses, hindering efficient waste heat utilization.

[0003] Therefore, there is an urgent need to develop new methods and devices for the cascade utilization of waste heat from mine gas power generation, so as to achieve more efficient and reliable utilization of waste heat from mine gas power generation. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems and to propose a new method and device for the cascade utilization of waste heat from coal mine gas power generation.

[0005] Based on one objective of this invention, the technical solution is: a method for cascade utilization of waste heat from coal mine gas power generation, comprising the following steps:

[0006] S1. Primary heat exchange: The high-temperature flue gas of 280-300℃ emitted by the mine gas generator set is introduced into the primary heat exchange equipment in the flue and indirectly exchanged with the primary softened water medium from the primary closed-loop circulating water system, so that the temperature of the primary softened water medium is raised to above 80℃.

[0007] S2. Secondary heat exchange: The primary softened water medium at a temperature of 80°C or above is introduced into the secondary heat exchange equipment to exchange heat indirectly with the tap water medium from the tap water supply device. The tap water medium is raised to a temperature of 60°C or above and then used as a heat source for conversion and heating.

[0008] S3. Heating conversion: The heat source is introduced into two heat storage chambers in the heat source regulating and transfer station. The heat source regulating and transfer station also includes a remote DCS control system, a hot water pump, and two heat distribution chambers. The remote DCS control system controls the hot water pump as needed to send the heat source in the heat storage chamber to the conversion and heating device, so that the heat source and the secondary softened water medium from the secondary closed-loop circulating water system in the conversion and heating device can exchange heat indirectly. The secondary softened water medium is heated by 15°C and then supplied to the mine auxiliary shaft for heating. After the heat source and the secondary softened water medium exchange heat, the temperature of the tap water drops to 45-50°C and is returned to the two heat distribution chambers. The remote DCS control system controls the distribution pumps matched with the two heat distribution chambers as needed to supply the 45-50°C tap water to the bathing center in the mining area.

[0009] In addition, when the heat source is sufficient, a portion can be diverted directly to the underfloor heating or radiators in the mining area office area for heating. The return water from the underfloor heating or radiators can be sent back to the tap water supply device of the secondary heat exchange equipment to supplement the tap water consumption.

[0010] Preferably, in steps S1 and S2, the temperature of the softened water medium after the initial heating is 80-85°C. Controlling the temperature at 80-85°C can prevent the generation of a large amount of water vapor in the pipes of the primary heat exchanger, thus improving the safety of the device. More preferably, the temperature of the softened water medium after the initial heating is 80°C.

[0011] Preferably, in steps S2 and S3, the temperature of the heat source is 60-65°C, more preferably, the temperature of the heat source is 60°C.

[0012] Based on another objective of the present invention, the technical solution is as follows: a cascade utilization device for waste heat from flue gas in mine gas power generation, comprising a primary heat exchanger, a primary closed-loop circulating water system, a secondary heat exchanger, a tap water supply device, a conversion and heating device, a secondary closed-loop circulating water system, a mine auxiliary shaft heating device, and a heat source regulating and transfer station. The primary heat exchanger adopts a stainless steel turbulence-inducing heat exchanger, specifically, a Kaishan Purification KSYQ-360 type stainless steel turbulence-inducing heat exchanger. The primary closed-loop circulating water system includes a primary circulating water pipeline, a primary circulating water tank, and a primary circulating water pump. The secondary heat exchanger and the conversion and heating device both adopt plate heat exchangers. The secondary closed-loop circulating water system includes a secondary circulating water pipeline and a secondary circulating water pump. The mine auxiliary shaft heating device includes a surface heat exchanger, a secondary circulating water tank, and a secondary circulating water pump. The heat source regulating and transfer station is a grid-structured overflow transfer station.

[0013] Preferably, the grid-shaped overflow transfer station includes a remote DCS control system and a water storage tank. The water storage tank is an insulated water tank with an insulated cover on top. A cross-shaped insulating partition divides the water storage tank into four independent water storage chambers. The two water storage chambers at the front of the water storage tank are heat distribution chambers, and the two water storage chambers at the rear of the water storage tank are heat storage chambers. Several overflow pipes are provided between the corresponding heat storage chambers and heat distribution chambers. The overflow pipes are located at the top of the cross-shaped insulating partition and contain a one-way valve that allows heat from the heat storage chambers to flow unidirectionally to the heat distribution chambers. The hot water inlet of the heat storage chamber is connected to the refrigerant outlet of the secondary heat exchanger, and the hot water outlet of the heat storage chamber is connected to the heat medium inlet of the conversion and heating device. The water inlet of the heat distribution chamber is connected to the heat medium outlet of the conversion and heating device.

[0014] Preferably, the cross-shaped heat insulation partition adopts a vacuum structure or has a cavity inside, which is filled with heat insulation material to ensure the heat preservation effect of each heat storage chamber and heat diversion chamber.

[0015] Preferably, each heat storage chamber has a hot water inlet and a hot water outlet on its side wall. The hot water inlet is located above the hot water outlet, and the hot water outlet is located at the bottom of the heat storage chamber. Each heat distribution chamber has a water inlet and a water outlet on its side wall. The water inlet is located above the water outlet, and the water outlet is located at the bottom of the heat distribution chamber. A hot water inlet pipe is connected to the outside of the hot water inlet, a hot water outlet pipe is connected to the outside of the hot water outlet, a water inlet pipe is connected to the outside of the water inlet, and a water outlet pipe is connected to the outside of the water outlet. Each hot water inlet pipe is equipped with an electric valve one, each hot water outlet pipe is equipped with an electric valve two, and each water inlet pipe is equipped with a... An electric valve three is provided, and an electric valve four is provided on each outlet pipe near the heat distribution chamber. The hot water outlet pipes of the two heat storage chambers converge into a hot water outlet header, and a hot water pump is provided at the end of the hot water outlet header away from the two hot water outlet pipes. The ends of the hot water inlet pipes of the two heat storage chambers away from the heat storage chambers are respectively connected to a hot water inlet header. The ends of the inlet pipes of the two heat distribution chambers away from the heat distribution chambers are both connected to an inlet manifold header. A diversion pump is provided on each of the two outlet pipes. The hot water pump, diversion pump, electric valve one, electric valve two, electric valve three, and electric valve four are all electrically connected to a remote DCS control system.

[0016] In the above scheme, the heat source from the secondary heat exchange equipment can be stored in the corresponding heat storage tank by controlling the electric valve one on each hot water inlet pipe. The heat source in each heat storage tank can be transported to the conversion and heating device by the hot water supply pump as needed by controlling the electric valve two on each hot water outlet pipe through the remote DCS control system. After the heat source exchanges heat with the refrigerant (secondary softened water medium) in the conversion and heating device, it is cooled to 45-50℃ and transported to the heat distribution tank through the inlet water manifold. Then, it is pumped to the bathing centers in the mining area by two distribution pumps for use as bathing water. The refrigerant in the conversion and heating device is heated by about 15℃ after heat exchange with the heat source and is used for heating at the auxiliary shaft of the mine.

[0017] Preferably, a connecting pipe is provided between the outlet pipes of the two hot water distribution chambers, and an electric connecting valve is installed on the connecting pipe. The electric connecting valve is electrically connected to a remote DCS control system. When the water storage in one of the hot water distribution chambers is insufficient, hot water from the other hot water distribution chamber can be replenished into the water-deficient hot water distribution chamber or directly pumped to the corresponding bathing center or bathing device by operating the electric connecting valve and the corresponding electric valve, so as to ensure the continuous and stable use of each bathing center or bathing device.

[0018] Preferably, each heat distribution compartment is provided with an overflow port at the top of its side wall, and an overflow discharge pipe is connected to the overflow port. When the water level in the heat distribution compartment is higher than the overflow port, it can be discharged through the overflow discharge pipe, and the discharged overflow water can be used as a refrigerant for the secondary heat exchange equipment.

[0019] Preferably, each heat storage chamber and heat distribution chamber is equipped with a level sensor and a temperature sensor, and each heat storage chamber and heat distribution chamber is equipped with an electric drain valve at its bottom. The level sensor, temperature sensor, and electric drain valve are electrically connected to a remote DCS control system. The level sensor and temperature sensor are used to monitor the water level and temperature in each heat storage chamber and heat distribution chamber, facilitating timely adjustment of water replenishment and discharge as needed. The electric drain valve allows for periodic drainage or drainage during maintenance.

[0020] This invention also includes other steps, components, or devices that enable its normal use. These other steps, components, or devices are all conventional means in the art. In addition, devices or components not limited in this invention, such as plate heat exchangers, surface heat exchangers, stainless steel turbulent heat exchangers, various electric valves, electric connecting valves, electric drain valves, hot water pumps, diversion pumps, insulated water tanks, insulated covers, level sensors, temperature sensors, remote DCS control systems, etc., all adopt existing technologies in the art. Those skilled in the art can select the specifications and models of the corresponding components or devices according to actual needs.

[0021] The working principle of this invention is as follows: a primary softened water medium is used as the refrigerant in the primary heat exchange equipment in the high-temperature flue of a mine gas generator set. After the high-temperature flue gas and the primary softened water medium exchange heat indirectly in the primary heat exchange equipment, the temperature of the primary softened water medium is quickly raised to above 80°C. The primary softened water medium above 80°C is then introduced into a secondary heat exchange equipment, where it exchanges heat with tap water flowing through it, raising the temperature of the tap water to above 60°C. The tap water above 60°C is then sent to a heat storage chamber for storage as a heat source. The cooled primary softened water medium is then circulated in a closed loop back to the primary heat exchange equipment to exchange heat with the high-temperature flue gas again, achieving efficient absorption of waste heat from the flue gas. The remote DCS control system controls the hot water pump to send the heat source in the heat storage tank to the conversion and heating device, which converts and heats the secondary softened water medium. After the secondary softened water medium is heated by about 15°C, it is used to heat the auxiliary shaft opening of the mine. The heat source is cooled to 45-50°C in the conversion and heating device and then sent to the heat distribution tank for storage and backup. The hot water in the heat distribution tank is transported to various bathing centers in the mine area by the distribution pump and mixed with tap water for use as bathing water for employees. When the amount of tap water after heat exchange in the secondary heat exchange equipment is large, and the water level in the heat storage tank exceeds the overflow pipe at the top of the cross-shaped insulation partition, the hot water in the heat storage tank will flow into the corresponding heat distribution tank through the corresponding one-way valve to increase the water temperature and increase the water volume in the heat distribution tank, so as to make full use of heat energy. It is understandable that when the water temperature in the heat distribution tank rises, more cold water can be added for bathing without affecting normal use.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the method or device provided by the present invention can efficiently recover the waste heat in the high-temperature flue gas of the mine gas generator set, and the recovered heat energy is used to first heat the mine auxiliary shaft and then provide hot water for bathing centers. This realizes the efficient cascade utilization of the waste heat of the flue gas, so that the recovered heat energy can be fully recovered without waste, and the waste energy can be completely utilized, resulting in significant energy saving and emission reduction benefits. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process principle of the present invention in an embodiment.

[0024] Figure 2 This is a schematic diagram of the overall structure of the grid-shaped overflow transfer station in the embodiment.

[0025] Figure 3 for Figure 2 A schematic diagram of the structure after the insulation cover is removed.

[0026] Figure 4 for Figure 3 A schematic diagram of the dorsal side structure. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Embodiment 1:

[0029] As Figure 1 shown, the method for cascaded utilization of waste heat in flue gas of mine gas power generation proposed in this embodiment includes the following steps:

[0030] S1. Primary heat exchange: The high-temperature flue gas at about 290 °C (290 ± 10 °C) discharged from the mine gas generator set is introduced into the primary heat exchange device 1 (in this embodiment, the Kaishan purification KSYQ-360 type stainless steel turbulator heat exchanger is used) in the flue duct for indirect heat exchange with the primary softened water medium from the primary closed-loop water system, so that the primary softened water medium is heated to 80 - 85 °C; the primary closed-loop water system includes a primary circulation water pipeline 2, a primary circulation water tank 3, and a primary circulation water pump 4. It can be understood that a water injection port is provided on the primary circulation water tank.

[0031] S2. Secondary heat exchange: The primary softened water medium at 80 - 85 °C is introduced into the secondary heat exchange device 5 (a plate heat exchanger) for indirect heat exchange with the tap water medium from the tap water supply device, and the tap water medium is heated to 60 - 65 °C and used as the heat source for conversion and heat increase; the tap water supply device includes a tap water pipeline 6, a tap water pump 7, a tap water tank 8, and a tap water make-up pipe 9.

[0032] S3. Conversion heating: The heat source is introduced into two heat storage bins (respectively the heat storage bin A 10 and the heat storage bin B 11) in the heat source regulation transfer station. The heat source regulation transfer station is a cross-shaped overflow transfer station, including a remote DCS control system (not shown in the figure), a hot water supply pump 12, and two heat diversion bins (respectively the heat diversion bin C

[0033] Please see Figure 2 , Figure 3 In this embodiment, the grid-shaped overflow transfer station includes a water storage tank 21, which is an insulated water tank. The top of the water storage tank is provided with an insulated cover plate 22. The water storage tank is provided with a cross-shaped heat insulation partition 23, which divides the water storage tank into four independent water storage chambers. The two water storage chambers on the front side of the water storage tank are heat diversion chambers, and the two water storage chambers on the rear side of the water storage tank are heat storage chambers. Specifically, the interior of the cross-shaped heat insulation partition adopts a vacuum structure to ensure the heat insulation effect of each heat storage chamber and heat diversion chamber. Several overflow pipes 28 are provided between the corresponding heat storage chambers and heat distribution chambers. The overflow pipes are located at the top of the cross-shaped insulation partition and are equipped with one-way valves that allow the heat source in the heat storage chamber to flow unidirectionally to the heat distribution chamber. To facilitate the inspection and maintenance of the one-way valves, multiple hinged inspection doors 35 are provided at the corresponding positions on the insulation cover. The hot water inlet of the heat storage chamber is connected to the refrigerant outlet of the secondary heat exchange equipment, and the hot water outlet of the heat storage chamber is connected to the heat medium inlet of the conversion and heating device. The water inlet of the heat distribution chamber is connected to the heat medium outlet of the conversion and heating device.

[0034] Specifically, please refer to Figure 3 , Figure 4 Each heat storage chamber has a hot water inlet and a hot water outlet on its side wall. The hot water inlet is located above the hot water outlet, and the hot water outlet is located at the bottom of the heat storage chamber. Each heat distribution chamber has a water inlet and a water outlet on its side wall. The water inlet is located above the water outlet, and the water outlet is located at the bottom of the heat distribution chamber. A hot water inlet pipe 24 is connected to the outside of the hot water inlet, a hot water outlet pipe 25 is connected to the outside of the hot water outlet, a water inlet pipe 26 is connected to the outside of the water inlet, and a water outlet pipe 27 is connected to the outside of the water outlet. Each hot water inlet pipe is equipped with an electric valve one, each hot water outlet pipe is equipped with an electric valve two, and each water inlet pipe is equipped with a... An electric valve three is provided, and an electric valve four is provided on each water outlet pipe near the heat distribution chamber. The hot water outlet pipes of the two heat storage chambers converge on a hot water outlet header 29, and a hot water supply pump is provided at the end of the hot water outlet header away from the two hot water outlet pipes. The ends of the hot water inlet pipes of the two heat storage chambers away from the heat storage chambers are respectively connected to a hot water inlet header 30. The ends of the inlet pipes of the two heat distribution chambers away from the heat distribution chambers are both connected to an inlet manifold header 31. A diversion pump is provided on each of the two water outlet pipes. The hot water supply pump, diversion pump, electric valve one, electric valve two, electric valve three, and electric valve four are respectively electrically connected to a remote DCS control system.

[0035] In the above scheme, the heat source from the secondary heat exchange equipment can be stored in the corresponding heat storage tank by controlling the electric valve one on each hot water inlet pipe. The heat source in each heat storage tank can be transported to the conversion and heating device by the hot water supply pump as needed by controlling the electric valve two on each hot water outlet pipe through the remote DCS control system. After the heat source exchanges heat with the refrigerant (secondary softened water medium) in the conversion and heating device, it is cooled to 45-50℃ and transported to the heat distribution tank through the inlet water manifold. Then, it is pumped to the bathing centers in the mining area by two distribution pumps for use as bathing water. The refrigerant in the conversion and heating device is heated by about 15℃ after heat exchange with the heat source and is used for heating at the auxiliary shaft of the mine.

[0036] In this embodiment, a connecting pipe 32 is provided between the outlet pipes of the two heat distribution chambers. An electric connecting valve is installed on the connecting pipe and is electrically connected to a remote DCS control system. When the water level in one heat distribution chamber is insufficient, hot water from the other heat distribution chamber can be added to the chamber or directly pumped to the corresponding bathing center by operating the electric connecting valve and the corresponding electric valve, ensuring continuous and stable operation of each bathing center. Each heat distribution chamber has an overflow port at the top of its side wall, and an overflow discharge pipe 33 is connected to the overflow port. When the water level in the heat distribution chamber is higher than the overflow port, it can be discharged through the overflow discharge pipe. The discharged overflow water can be used as refrigerant for the secondary heat exchange equipment. Each thermal storage chamber and thermal distribution chamber is equipped with a level sensor (not shown in the figure) and a temperature sensor (not shown in the figure). Each thermal storage chamber and thermal distribution chamber also has an electric drain valve 34 at its bottom. The level sensor, temperature sensor, and electric drain valve are electrically connected to a remote DCS control system. The level sensor and temperature sensor are used to monitor the water level and temperature in each thermal storage chamber and thermal distribution chamber, facilitating timely adjustment of the water supply and discharge as needed. The electric drain valve allows for periodic drainage or drainage during maintenance.

[0037] It is understood that the plate heat exchanger, stainless steel turbulence heat exchanger, various electric valves, electric connecting valves, electric drain valves, hot water pumps, diversion pumps, insulated water tanks, insulated covers, level sensors, temperature sensors, remote DCS control systems, etc. in this embodiment all adopt existing technologies in the field. Those skilled in the art can select the specifications and models of the corresponding components or devices according to actual needs.

[0038] The working principle of this invention is as follows: a primary softened water medium is used as the refrigerant in the primary heat exchange equipment in the high-temperature flue of a mine gas generator set. After the high-temperature flue gas and the primary softened water medium exchange heat indirectly in the primary heat exchange equipment, the temperature of the primary softened water medium is quickly raised to 80-85°C. The primary softened water medium at 80-85°C is then introduced into a secondary heat exchange equipment, where tap water is introduced to exchange heat and raise its temperature to 60-65°C. The tap water at 60-65°C is then sent to a heat storage chamber for storage as a heat source. The cooled primary softened water medium is then circulated in a closed loop back to the primary heat exchange equipment to exchange heat with the high-temperature flue gas again, thereby achieving efficient absorption of waste heat from the flue gas. The remote DCS control system controls the hot water pump to send the heat source in the heat storage tank to the conversion and heating device, which converts and heats the secondary softened water medium. After the secondary softened water medium is heated by about 15°C, it is used to heat the auxiliary shaft opening of the mine. The heat source is cooled to 45-50°C in the conversion and heating device and then sent to the heat distribution tank for storage and backup. The hot water in the heat distribution tank is transported to various bathing centers in the mine area by the distribution pump and mixed with tap water for use as bathing water for employees. When the amount of tap water after heat exchange in the secondary heat exchange equipment is large, and the water level in the heat storage tank exceeds the overflow pipe at the top of the cross-shaped insulation partition, the hot water in the heat storage tank will flow into the corresponding heat distribution tank through the corresponding one-way valve to increase the water temperature and increase the water volume in the heat distribution tank, so as to make full use of heat energy. It is understandable that when the water temperature in the heat distribution tank rises, more cold water can be added for bathing without affecting normal use. The method or apparatus provided by this invention can efficiently recover waste heat from the high-temperature flue gas of a mine gas generator set. The recovered heat energy is used to first heat the mine's auxiliary shaft and then provide hot water for bathing centers. This achieves efficient cascade utilization of flue gas waste heat, ensuring that all recovered heat energy is fully recovered without waste. This fully utilizes the waste energy, resulting in significant energy conservation and emission reduction benefits.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for cascade utilization of mine gas power generation flue gas waste heat, characterized in that, It comprises the following steps: S1. Once heat exchange, the high-temperature flue gas of 280~300℃ discharged by mine gas generating set is introduced into the once heat exchange equipment in the flue to exchange heat with the once softened water medium from the once closed circulation water system, so that the once softened water medium is heated to above 80℃; S2. Secondary heat exchange, the once softened water medium above 80℃ is introduced into the secondary heat exchange equipment to exchange heat with the tap water medium from the tap water supply device, and the tap water medium is heated to above 60℃ and used as the heat source for conversion heating; S3. Conversion heating, the heat source is introduced into the two heat storage bins in the heat source adjusting transfer station, the heat source adjusting transfer station is a field type overflow transfer station, comprising a remote DCS control system, a water storage tank, a heating water pump and two heat shunt bins, the water storage tank is a heat preservation tank, and the top of the water storage tank is provided with a heat preservation cover plate, the water storage tank is provided with a cross-shaped heat insulation partition plate, the cross-shaped heat insulation partition plate divides the water storage tank into four independent water storage cavities, two water storage cavities on the front side of the water storage tank are heat shunt bins, and two water storage cavities on the back side of the water storage tank are heat storage bins, a plurality of overflow pipes are arranged between the corresponding heat storage bins and heat shunt bins, the overflow pipes are arranged at the top end of the cross-shaped heat insulation partition plate, and a one-way valve is arranged in the overflow pipe to enable the heat source in the heat storage bin to flow to the heat shunt bin in one direction; the remote DCS control system controls the heating water pump to send the heat source in the heat storage bin to the conversion heating device according to needs, so that the heat source exchanges heat with the secondary softened water medium from the secondary closed circulation water system in the conversion heating device, the secondary softened water medium is heated by 15℃, and then supplied to the mine auxiliary shaft mouth for heating; the temperature of the tap water is reduced to 45~50℃ after the heat exchange between the heat source and the secondary softened water medium, and then returned to the two heat shunt bins, and the remote DCS control system controls the shunt pump matched with the two heat shunt bins to supply the tap water at 45~50℃ to the bath center in the mining area.

2. The mine gas power generation flue gas waste heat cascade utilization method according to claim 1, characterized in that: In steps S1 and S2, the temperature of the once softened water medium after heating is 80~85℃.

3. The mine gas power generation flue gas waste heat cascade utilization method according to claim 1, characterized in that: In steps S2 and S3, the temperature of the heat source is 60~65℃.

4. The device for the cascade utilization of mine gas power generation flue gas waste heat according to any one of claims 1-3, characterized in that: It comprises a once heat exchange equipment, a once closed circulation water system, a secondary heat exchange equipment, a tap water supply device, a conversion heating device, a secondary closed circulation water system, a mine auxiliary shaft mouth heating device and a heat source adjusting transfer station, the once heat exchange equipment adopts a stainless steel spoiler heat exchanger, the once closed circulation water system comprises a once circulation water pipeline, a once circulation water tank and a once circulation water pump, the secondary heat exchange equipment and the conversion heating device both adopt a plate heat exchanger, the secondary closed circulation water system comprises a secondary circulation water pipeline and a secondary circulation water pump, and the mine auxiliary shaft mouth heating device comprises a surface heat exchanger, a secondary circulation water tank and a secondary circulation water pump.

5. The mine gas power generation flue gas waste heat cascade utilization device according to claim 4, characterized in that: The hot water inlet of the heat storage bin is in communication with the cold medium outlet of the secondary heat exchange equipment, and the hot water outlet of the heat storage bin is in communication with the hot medium inlet of the conversion heating device, and the water inlet of the heat shunt bin is in communication with the hot medium outlet of the conversion heating device.

6. The mine gas power generation flue gas waste heat cascade utilization device according to claim 5, characterized in that: The cross-shaped heat insulation partition plate is internally provided with a vacuum structure or a cavity filled with heat insulation material.

7. The mine gas power generation flue gas waste heat cascade utilization device according to claim 5, characterized in that: The side wall of each heat storage bin is provided with a hot water inlet and a hot water outlet, the hot water inlet is arranged above the hot water outlet, and the hot water outlet is arranged at the bottom of the heat storage bin; the side wall of each heat distribution bin is provided with a water inlet and a water outlet, the water inlet is arranged above the water outlet, and the water outlet is arranged at the bottom of the heat distribution bin; the outside of the hot water inlet is connected with a hot water inlet pipe, the outside of the hot water outlet is connected with a hot water outlet pipe, the outside of the water inlet is connected with a water inlet pipe, and the outside of the water outlet is connected with a water outlet pipe; each hot water inlet pipe is respectively provided with an electric valve one, each hot water outlet pipe is respectively provided with an electric valve two, each water inlet pipe is respectively provided with an electric valve three, and each water outlet pipe is respectively provided with an electric valve four near the heat distribution bin; the hot water outlet pipes of the two heat storage bins are connected to a hot water outlet main pipe, and the hot water outlet main pipe is provided with a hot water pump at the end away from the two hot water outlet pipes; the hot water inlet pipes of the two heat storage bins are respectively connected to a hot water inlet main pipe at the end away from the heat storage bins; the water inlet pipes of the two heat distribution bins are connected to a water inlet main pipe at the end away from the heat distribution bins; the two water outlet pipes are respectively provided with a distribution pump; and the hot water pump, the distribution pump, the electric valve one, the electric valve two, the electric valve three and the electric valve four are respectively electrically connected with a remote DCS control system.

8. The mine gas power generation flue gas waste heat cascade utilization device according to claim 7, characterized in that: The two water outlet pipes of the heat distribution bins are provided with a communication pipe, and the communication pipe is provided with an electric communication valve, and the electric communication valve is electrically connected with the remote DCS control system.

9. The mine gas power generation flue gas waste heat cascade utilization device according to claim 5, characterized in that: The top of the side wall of each heat distribution bin is provided with an overflow port, and the overflow port is connected with an overflow discharge pipe.

10. The mine gas power generation flue gas waste heat cascade utilization device according to any one of claims 5-9, characterized in that: Each heat storage bin and heat distribution bin is respectively provided with a liquid level sensor and a temperature sensor, and the bottom of each heat storage bin and heat distribution bin is respectively provided with an electric blowdown valve, and the liquid level sensor, the temperature sensor and the electric blowdown valve are respectively electrically connected with the remote DCS control system.

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