A device and operation method for producing steam by heat storage oxidation of low-concentration coal mine gas

Abstract

The present invention relates to the technical field of application of low-concentration mine gas, and particularly relates to a device and an operation method for producing steam by low-concentration coal mine gas through regenerative oxidation. The device includes two-stage gas concentration adjustment units, a gas regenerative oxidation unit, a once-through waste heat recovery steam production unit, and a control system. Low-concentration gas is safely mixed with medium- and high-concentration gas to meet the requirements of regenerative oxidation combustion. The device can effectively utilize the excess heat of regenerative oxidation to produce steam and recover gas resources. The operation method of the device includes a device startup stage and a normal operation stage, ensuring that the exhaust gas concentration entering the regenerative oxidizer is far from the methane gas explosion limit, and the oxidation combustion process is stable, safe, and controllable. In the present invention, the two-stage gas concentration adjustment units, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit are operationally controlled through the control system. Each unit can operate independently or be associated for operation control, and has a safety interlock protection function.

Description

Technical Field

[0001] The present invention relates to the technical field of application of low-concentration mine gas, and particularly relates to a device and an operation method for producing steam by regenerative oxidation of low-concentration coal mine gas. Background Art

[0002] At present, for low-concentration gas, such as mine ventilation air with a concentration below 1% and medium-concentration gas with a concentration in the range of 3-9%V, it is usually impossible to directly burn and utilize due to its low concentration. Currently, for safety reasons, it is generally directly vented, which will cause a large amount of resource waste and environmental pollution. Therefore, it is necessary to recycle this type of gas. For this type of low-concentration gas, a relatively efficient utilization method is to produce steam using safe combustion technology. However, due to the low concentration of this type of gas and the presence of air in the gas, conventional gas boilers cannot directly and safely burn and utilize it. The commonly used method is to use regenerative heat exchange technology to increase the temperature of the low-concentration gas entering the combustion chamber, thereby increasing the activation energy of the low-concentration gas and realizing the safe oxidation and combustion utilization of the low-concentration gas.

[0003] Currently, during the process of regenerative oxidation and utilization of low-concentration gas, in order to improve the gas utilization rate and energy density, and at the same time safely avoid the lower explosion limit of the gas, medium- and low-concentration gas is usually mixed for concentration adjustment to meet the safe intake conditions of the regenerative oxidation equipment. However, the current concentration adjustment system is not perfect. When the intake gas concentration and gas volume fluctuate, there is a safety hazard that the concentration may exceed the standard and may reach the lower explosion limit of the gas. Moreover, when the intake gas concentration and gas volume fluctuate, problems such as incomplete oxidation and combustion, unstable combustion process, low equipment efficiency, and excessive carbon monoxide and nitrogen oxides may also occur.

[0004] Chinese Patent with Application No. CN202011195475.2 discloses a system for producing saturated steam by high-temperature regenerative oxidation of low mine gas, including a gas mixing unit, a gas oxidation unit, and a steam boiler unit connected in sequence. The gas mixing unit includes a gas mixer, an air-gas mixer, a first gas concentration detector, a second gas concentration monitor, a safety relief valve, a safety flame arrester, a pipeline relief valve, a cut-off valve, and a second gas concentration detector; the gas oxidation unit includes a first fan, a switching valve, a first regenerative chamber, a second regenerative chamber, an oxidation chamber, a burner, and a low-temperature flue gas discharge pipeline; the steam boiler unit includes a high-temperature flue gas regulating valve, a steam boiler, a feed water preheater, a feed water system, a second fan, a smoke exhaust pipeline, and a steam output pipeline. This system for producing saturated steam by high-temperature regenerative oxidation of mine gas can effectively oxidize low-concentration gas, make full use of the huge heat released by gas oxidation, produce saturated steam, and replace the original coal-fired boilers in mines. However, the heat energy generated during its oxidation and combustion process uses a natural evaporation boiler, which has problems such as a large volume, slow startup speed, and great safety hazards. Summary of the Invention

[0005] The object of the present invention is to solve the problems that the existing gas concentration regulation system is not perfect enough, incomplete oxidation combustion may occur when the inlet gas concentration and gas volume fluctuate, the combustion process is unstable, there is a safety hazard of reaching the lower explosion limit of gas, and the existing low-concentration coal mine gas regenerative oxidation system for producing saturated steam uses a natural evaporation boiler, which has the technical problems of large volume and slow startup speed. A low-concentration coal mine gas regenerative oxidation steam production device and an operation method are provided. The two-stage gas concentration regulation unit, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit are operated and controlled through a control system. Each unit can operate independently or be associated for operation and control, and has a safety interlock protection function.

[0006] The technical solution adopted by the present invention to achieve the above object is: a low-concentration coal mine gas regenerative oxidation steam production device, including a two-stage gas concentration regulation unit, a gas regenerative oxidation unit, a once-through waste heat recovery steam production unit, and a control system connected in sequence.

[0007] The two-stage gas concentration regulation unit includes a low-concentration gas pipeline, a medium-concentration gas pipeline, a first-stage mixer, and a second-stage mixer. The low-concentration gas pipeline is divided into three paths after passing through the low-concentration gas extraction equipment. The first branch is connected to the first gas inlet end of the first-stage mixer, the second branch is connected to the first gas inlet end of the second-stage mixer, and the third branch is connected to the low-concentration gas return pipeline. The medium-concentration gas pipeline is connected to the second gas inlet end of the first-stage mixer through the medium-concentration gas extraction equipment. The gas outlet end of the first-stage mixer is connected to the second gas inlet end of the second-stage mixer through a pipeline. The gas outlet end of the second-stage mixer is connected with a second-stage mixed concentration detector and a conveying and venting switching valve group through a pipeline.

[0008] The gas regenerative oxidation unit includes an induced draft fan, a regenerative oxidizer, and an exhaust stack. The intake end of the induced draft fan is connected to the transfer and vent switching valve group through a pipeline. The outlet end of the induced draft fan is connected to the inlet header of the inlet and outlet switching and lifting valve through an intake connection pipe. The outlet header of the inlet and outlet switching and lifting valve is connected to an outlet connection pipe and is connected to the exhaust stack through an outlet exhaust stack pipeline. The inlet and outlet switching and lifting valve is arranged at both lower ends of the regenerative oxidizer. A valve cavity capable of communicating with the inlet header, the outlet header, and the regenerative chamber is provided inside the inlet and outlet switching and lifting valve. A valve plate is arranged in the valve cavity. A driving assembly for driving the valve plate to block the valve openings of the inlet header or the outlet header is arranged at the upper end of the inlet and outlet switching and lifting valve. A regenerative bed is arranged in the regenerative chamber. A rectifying plate and gradually inclined guide vanes are arranged below the regenerative bed. A gas burner and a flame monitoring system are arranged on the oxidation chamber. The ignition ends of the gas burner and the flame monitoring system are located inside the oxidation chamber. A deep oxidation and temperature equalizing regenerative bed is arranged at the upper part of the regenerative oxidizer. A hot flue gas outlet is arranged at the top of the regenerative oxidizer. The hot flue gas outlet is located above the deep oxidation and temperature equalizing regenerative bed. The hot flue gas outlet is connected to a flue gas discharge pipe;

[0009] The once-through waste heat recovery steam production unit includes a once-through waste heat recovery furnace body, steam extraction heat pipes, a direct exhaust stack, a fan extraction exhaust stack, and an induced draft fan. Steam extraction heat pipes are arranged inside the once-through waste heat recovery furnace body. Steam is introduced into the once-through waste heat recovery furnace body through the steam extraction heat pipes. The intake end of the once-through waste heat recovery furnace body is connected to the flue gas discharge pipe. The exhaust end of the once-through waste heat recovery furnace body is respectively connected to the direct exhaust stack and a fan inlet pipeline. Switching regulating valves are arranged on both the direct exhaust stack and the fan inlet pipeline. An induced draft fan is arranged on the fan inlet pipeline. The induced draft fan is connected to the fan extraction exhaust stack. Exhaust stack waste heat extraction heat pipes are arranged inside the fan extraction exhaust stack;

[0010] The control system is electrically connected to the low-concentration gas induced draft equipment, the medium-concentration gas induced draft equipment, the post-secondary mixing concentration detector, the transfer and vent switching valve group, the induced draft fan, the driving assembly, the gas burner and the flame monitoring system, the switching regulating valve, and the induced draft fan respectively.

[0011] Further, the steam extraction heat pipe includes a steam extraction coil and a steam inlet pipe and a steam outlet pipe connected to both ends thereof. The steam extraction coil is located inside the once-through waste heat recovery furnace body. A softened water feed pump, a second temperature sensor, a flow meter, and a flow regulating valve are sequentially arranged on the steam inlet pipe. A pressure control valve and a steam-water separator are sequentially arranged on the steam outlet pipe. A second pressure sensor is arranged on the steam-water separator. The softened water feed pump, the second temperature sensor, the flow meter, the flow regulating valve, the pressure control valve, and the second pressure sensor are electrically connected to the control system respectively.

[0012] Further, a low-concentration gas dust and fog remover, a low-concentration pressure detector, a low-concentration detector, a low-concentration flowmeter, and a low-concentration flow regulating valve are provided on the low-concentration gas pipeline. The low-concentration gas dust and fog remover is arranged at the front end of the low-concentration gas extraction device, and the low-concentration pressure detector, the low-concentration detector, the low-concentration flowmeter, and the low-concentration flow regulating valve are sequentially arranged at the rear end of the low-concentration gas extraction device. The low-concentration pressure detector, the low-concentration detector, the low-concentration flowmeter, and the low-concentration flow regulating valve are respectively electrically connected to the control system.

[0013] Further, a medium-concentration gas dust and fog remover, a medium-concentration pressure detector, a medium-concentration detector, a medium-concentration flowmeter, and a medium-concentration flow regulating valve are provided on the medium-concentration gas pipeline. The medium-concentration gas dust and fog remover is arranged at the front end of the medium-concentration gas extraction device, and the medium-concentration pressure detector, the medium-concentration detector, the medium-concentration flowmeter, and the medium-concentration flow regulating valve are sequentially arranged at the rear end of the medium-concentration gas extraction device. The medium-concentration pressure detector, the medium-concentration detector, the medium-concentration flowmeter, and the medium-concentration flow regulating valve are respectively electrically connected to the control system.

[0014] Further, a primary shunt flowmeter and a primary flow regulating valve are provided on the first branch, a secondary shunt flowmeter and a secondary flow regulating valve are provided on the second branch, a low-concentration gas return control valve is provided on the third branch, a low-concentration gas concentration detector after primary mixing and a low-concentration gas flowmeter after primary mixing are provided on the connecting pipeline between the primary mixer and the secondary mixer. The primary shunt flowmeter, the primary flow regulating valve, the secondary shunt flowmeter, the secondary flow regulating valve, the low-concentration gas return control valve, the low-concentration gas concentration detector after primary mixing, and the low-concentration gas flowmeter after primary mixing are respectively electrically connected to the control system.

[0015] Further, a flame arrester is provided on the pipeline between the transfer and vent switching valve group and the induced draft fan, and an air inlet pipeline is communicated with the pipeline between the transfer and vent switching valve group and the flame arrester. An air inlet regulating valve is provided on the air inlet pipeline, and the air inlet regulating valve is electrically connected to the control system.

[0016] Further, a gas inlet flowmeter is provided on the inlet connecting pipe, and an exhaust flowmeter is provided on the outlet exhaust pipe. The gas inlet flowmeter and the exhaust flowmeter are respectively electrically connected to the control system.

[0017] Further, a first pressure sensor and a first temperature sensor are provided in the oxidation chamber. The first pressure sensor and the first temperature sensor are respectively electrically connected to the control system.

[0018] Further, a flue gas temperature sensor is provided on the flue gas discharge pipe, a third temperature sensor is provided on the direct exhaust stack, and a fourth temperature sensor is provided on the fan extraction exhaust stack. The flue gas temperature sensor, the third temperature sensor, and the fourth temperature sensor are respectively electrically connected to the control system.

[0019] An operation method of a low-concentration coal mine gas regenerative oxidation steam production device includes the following steps:

[0020] S1: Device startup stage: First, start the two-stage gas concentration adjustment unit, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit respectively.

[0021] After the two-stage gas concentration adjustment unit is started, first, through concentration detection and control of the high and low concentration gas flow ratio by the regulating valve, the primary mixing of low-concentration gas and medium-concentration gas is achieved through the primary mixer. After the primary mixing, the gas concentration is controlled at about 3%V. The gas after the primary mixing is then mixed with low-concentration gas through concentration detection and control of the high and low concentration gas flow ratio by the regulating valve and enters the secondary mixer for mixing. After the secondary mixing, the gas concentration is controlled at about 1.2%V. The low-concentration gas after being adjusted through two stages is temporarily vented or enters the gas regenerative oxidation unit for treatment by the control of the transfer and vent valve group.

[0022] After the gas regenerative oxidation unit is started, first confirm that the low-concentration gas transfer valve is in the closed state, open the air intake regulating valve. The air is preheated through heat exchange by the air supply fan, the left side inlet and outlet switching and lifting valve, and the left side regenerative bed, and then enters the upper oxidation chamber for heating by the burner, releasing heat and transferring the heat to the right side regenerative bed. The oxidized waste gas is discharged to the atmosphere through the right side inlet and outlet switching and lifting valve, the exhaust pipe, and the exhaust stack. After a certain period, the two inlet and outlet switching and lifting valves are switched to raise the temperature of both regenerative beds above 700°C. Repeat this cycle. After the gas regenerative oxidation unit operates stably and the oxidation chamber maintains an appropriate temperature, the system enters the standby state, waiting for the entry of low-concentration gas from the two-stage concentration adjustment unit.

[0023] After the once-through waste heat recovery steam production unit is started, first start the water-steam circulation system. The switching regulating valve on the direct exhaust stack and the switching regulating valve on the fan inlet pipeline are both in the closed state. When the softened water forms a stable circulation, the system enters the standby waiting state, waiting for the high-temperature flue gas discharged from the previous gas regenerative oxidation unit to enter.

[0024] S2: Normal operation stage: After the two-stage gas concentration adjustment unit, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit operate independently and stably, according to needs, the three units are put into linkage operation.

[0025] First, gradually close the low-concentration vent valve on the pipeline at the rear end of the two-stage gas concentration adjustment unit and gradually open the low-concentration transfer valve. The waste gas gradually enters the gas regenerative thermal oxidation unit. As the temperature in the oxidation chamber rises, reduce the burner load. As the waste gas concentration and volume increase, when the temperature in the oxidation chamber further rises to a certain control temperature, the regenerative thermal oxidizer enters the thermal self-balanced stable state, and the burner maintains the minimum ignition state. As the waste gas concentration and flow rate increase, when the temperature in the oxidation chamber continues to rise to a certain higher control temperature, open the switching regulating valve on the direct exhaust pipe of the once-through waste heat recovery steam production unit. Part of the excess hot flue gas enters the once-through waste heat recovery steam production unit under its own pressure. The softened water is vaporized after heating to produce steam. The remaining part of the flue gas in the oxidation chamber of the regenerative thermal oxidizer transfers heat to the regenerator through another regenerative bed and is discharged through the exhaust pipe. When the self-pressure of the flue gas in the oxidation chamber is insufficient, open the switching regulating valve on the inlet pipeline of the fan, close the switching regulating valve on the direct exhaust pipe, start the induced draft fan for flue gas extraction, and further recover the waste heat of the flue gas through the waste heat extraction pipe on the exhaust pipe at the fan outlet to produce hot water or preheat the softened water inlet.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) The low-concentration coal mine gas regenerative thermal oxidation steam production device of the present invention adopts two-stage gas concentration adjustment, realizes the safety mixing concentration control of low-concentration gas with medium- and high-concentration gas, can adjust the gas concentration to about 1.2%V, meets the requirements of safe and stable entry into the subsequent regenerative thermal oxidation combustion, ensures that the waste gas concentration entering the regenerative thermal oxidizer is far from the methane gas explosion limit, and the oxidation combustion process is stable, safe, and controllable. At the same time, the device can effectively utilize the excess heat of regenerative thermal oxidation to produce steam, realizes environmental protection, low-carbon emission reduction, and recovers gas resources. The device can flexibly select to produce steam or hot water according to user needs, and realizes uses such as heat supply, power generation, and refrigeration.

[0028] (2) A rectifying plate and gradually inclined guide vanes are arranged at the lower part of the regenerator of the regenerative thermal oxidizer of the present invention, which can make the gas enter the regenerator more evenly, enable the regenerator to fully absorb heat or preheat the gas, make the temperature field of the regenerator more balanced, enable the gas entering the regenerative thermal oxidizer to be evenly distributed, evenly heated, fully oxidized, improve the oxidation rate, thereby improving the waste heat utilization of the regenerator, and improving the safety and reliability of the regenerative thermal oxidizer.

[0029] (3) A deep oxidation and temperature-equalizing regenerative bed is arranged at the upper part of the regenerative thermal oxidizer of the present invention. The deep oxidation and temperature-equalizing regenerative bed mainly plays the role of preserving a part of the heat in the oxidation chamber, can improve the heating rate of the oxidation chamber, enable the regenerative thermal oxidizer to quickly reach the thermal self-balanced stable state, improve the regenerative thermal oxidation efficiency of the regenerative thermal oxidizer, and further reduce the control difficulty of the control system.

[0030] (4) The operation control method of the low-concentration coal mine gas regenerative oxidation steam production device of the present invention. The two-stage gas concentration adjustment unit, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit are operationally controlled through a control system. Each unit can operate independently or be associated for operation control. The control system is provided with three different control units and has a safety interlock protection function. The operation interface is respectively provided with three unit process control interfaces, making the operation control clearer and more convenient.

[0031] (5) The operation control method of the low-concentration coal mine gas regenerative oxidation steam production device of the present invention can achieve the concentration mixing adjustment of the two-stage gas concentration adjustment unit through the associated control of concentration detection and flow adjustment, the associated control of the inlet and outlet gas switching frequency of the gas regenerative oxidation unit with the exhaust gas temperature and the heat storage recovery efficiency, the associated control of the temperature of the oxidation chamber with the inlet gas concentration, flow rate, burner load, top exhaust gas volume, and bottom exhaust gas volume, and the associated control of the steam flow rate and pressure of the once-through waste heat recovery steam production unit with the flue gas temperature and flow rate. Description of the Drawings

[0032] Figure 1 It is a structural diagram of the low-concentration coal mine gas regenerative oxidation steam production device of the present invention.

[0033] In the figure: 1. Low-concentration gas pipeline, 2. Medium-concentration gas pipeline, 3. Low-concentration gas return pipeline, 4. Low-concentration gas dust and fog eliminator, 5. Low-concentration gas air-intake equipment, 6. Low-concentration pressure detector, 7. Low-concentration detector, 8. Low-concentration flowmeter, 9. Low-concentration flow regulating valve, 10. Primary shunt flowmeter, 11. Primary flow regulating valve, 12. Secondary shunt flowmeter, 13. Secondary flow regulating valve, 14. Low-concentration gas return control valve, 15. Medium-concentration gas dust and fog eliminator, 16. Medium-concentration gas air-intake equipment, 17. Medium-concentration pressure detector, 18. Medium-concentration detector, 19. Medium-concentration flowmeter, 20. Medium-concentration flow regulating valve, 21. Primary mixer, 22. Low-concentration gas concentration detector after primary mixing, 23. Low-concentration gas flowmeter after primary mixing, 24. Secondary mixer, 25. Concentration detector after secondary mixing, 26. Low-concentration gas conveying valve, 27. Low-concentration gas vent valve, 28. Air intake regulating valve, 29. Flame arrester, 30. Air-intake fan, 31. Gas intake flowmeter, 32. Intake connecting pipe, 33. Outlet connecting pipe, 34. Left outlet pipe box, 35. Left valve plate, 36. Left inlet pipe box valve port, 37. Left inlet pipe box, 38. Left valve rod support bearing, 39. Left driving cylinder, 40. Left rectifying plate flow equalizing section, 41. Right rectifying plate flow equalizing section, 42. Rectifying plate, 43. Guide vane, 44. Right driving cylinder, 45. Right valve rod support bearing, 46. Right inlet pipe box, 47. Right valve plate, 48. Right outlet pipe box valve port, 49. Right outlet pipe box, 50. Regenerative oxidizer, 51. Oxidation chamber, 52. First pressure sensor, 53. First temperature sensor, 54. Gas burner and flame monitoring system, 55. Natural gas inlet pipeline, 56. Flame-retardant air inlet pipeline, 57. Exhaust flowmeter, 58. Exhaust stack, 59. Flue gas discharge pipe, 60. Flue gas temperature sensor, 61. Once-through waste heat recovery furnace body, 62. Steam inlet pipe, 63. Softened water inlet water pump, 64. Second temperature sensor, 65. Flowmeter, 66. Flow regulating valve, 67. Steam heat extraction coil, 68. Steam-water separator, 69. Second pressure sensor, 70. Pressure control valve, 71. Steam outlet pipe, 72. Third temperature sensor, 73. Direct exhaust stack, 74. Fan inlet pipeline, 75. First switching regulating valve, 76. Second switching regulating valve, 77. Induced draft fan, 78. Fan air extraction and exhaust stack, 79. Waste heat extraction pipe, 80. Fourth temperature sensor. Detailed implementation mode

[0034] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the specific embodiments.

[0035] As Figure 1A low-concentration coal mine gas regenerative oxidation steam production device shown in the figure includes two-stage gas concentration adjustment unit A, gas regenerative oxidation unit B, once-through waste heat recovery steam production unit C, and control system CS connected in sequence. The control system CS is provided with an operation interface.

[0036] The two-stage gas concentration adjustment unit A includes a low-concentration gas pipeline 1, a medium-concentration gas pipeline 2, a first-stage mixer 21, and a second-stage mixer 24. The low-concentration gas pipeline 1 is divided into three paths after passing through a low-concentration gas dust and fog remover 4 and a low-concentration gas air extraction device 5. The first branch is connected to the first air inlet end of the first-stage mixer 21, and a first-stage shunt flowmeter 10 and a first-stage flow regulating valve 11 are arranged on the first branch; the second branch is connected to the first air inlet end of the second-stage mixer 24, and a second-stage shunt flowmeter 12 and a second-stage flow regulating valve 13 are arranged on the second branch; the third branch is connected to the low-concentration gas return pipeline 3, and a low-concentration gas return control valve 14 is arranged on the third branch; the medium-concentration gas pipeline 2 is connected to the second air inlet end of the first-stage mixer 21 after passing through a medium-concentration gas dust and fog remover 15 and a medium-concentration gas air extraction device 16. The air outlet end of the first-stage mixer 21 is connected to the second air inlet end of the second-stage mixer 24 through a pipeline. A low-concentration gas concentration detector 22 and a low-concentration gas flowmeter 23 after the first-stage mixing are arranged on the connecting pipeline between the first-stage mixer 21 and the second-stage mixer 24. The air outlet end of the second-stage mixer 24 is connected with a concentration detector 25 and a conveying and venting switching valve group after the second-stage mixing through a pipeline. The conveying and venting switching valve group includes a low-concentration gas conveying valve 26 and a low-concentration gas venting valve 27.

[0037] The low-concentration gas dust and fog remover 4, the low-concentration gas air extraction device 5, the first-stage shunt flowmeter 10, the first-stage flow regulating valve 11, the second-stage shunt flowmeter 12, the second-stage flow regulating valve 13, the low-concentration gas return control valve 14, the medium-concentration gas dust and fog remover 15, the medium-concentration gas air extraction device 16, the low-concentration gas concentration detector 22 after the first-stage mixing, the low-concentration gas flowmeter 23 after the first-stage mixing, the concentration detector 25 after the second-stage mixing, and the conveying and venting switching valve group are respectively electrically connected to the control system.

[0038] In this embodiment, a low-concentration pressure detector 6, a low-concentration detector 7, a low-concentration flowmeter 8, and a low-concentration flow regulating valve 9 are further provided on the low-concentration gas pipeline 1 at the rear end of the low-concentration gas extraction device 5. The low-concentration pressure detector 6, the low-concentration detector 7, the low-concentration flowmeter 8, and the low-concentration flow regulating valve 9 are respectively electrically connected to the control system; a medium-concentration pressure detector 17, a medium-concentration detector 18, a medium-concentration flowmeter 19, and a medium-concentration flow regulating valve 20 are further provided on the medium-concentration gas pipeline 2 between the medium-concentration gas extraction device 16 and the primary mixer 21. The medium-concentration pressure detector 17, the medium-concentration detector 18, the medium-concentration flowmeter 19, and the medium-concentration flow regulating valve 20 are respectively electrically connected to the control system.

[0039] In this embodiment, the low-concentration gas dust and mist eliminator 4 and the medium-concentration gas dust and mist eliminator 15 are of multi-tube structure and are provided with backwashing and condensate and dust discharging structural members; the primary and secondary mixers are of internal member turbulent flow type or Venturi tube type; the low-concentration gas extraction device 5 and the medium-concentration gas extraction device 16 are of safe explosion-proof structure, which can be a water-ring type vacuum or other similar gas extraction devices, and the pump outlet is provided with a separation tank and a mist eliminator.

[0040] The gas regenerative oxidation unit B includes an induced draft fan 30, a regenerative oxidizer 50, and an exhaust stack 58. The intake end of the induced draft fan 30 is connected to the conveying and venting switching valve group through a pipeline. A flame arrester 29 is provided on the pipeline between the conveying and venting switching valve group and the induced draft fan 30. The flame arrester 29 adopts a dry-type flame arrester. An air intake pipeline is communicated with the pipeline between the conveying and venting switching valve group and the flame arrester 29. An air intake regulating valve 28 is provided on the air intake pipeline. The induced draft fan 30 and the air intake regulating valve 28 are respectively electrically connected to the control system; the outlet end of the induced draft fan 30 is connected to the inlet pipe boxes of two inlet and outlet switching and lifting valves through a gas intake flowmeter 31 and an intake connecting pipe 32. The outlet pipe boxes of the two inlet and outlet switching and lifting valves are connected to an outlet connecting pipe 33 and are connected to the exhaust stack 58 through an outlet exhaust stack pipeline. An exhaust flowmeter 57 is provided on the outlet exhaust stack pipeline. The gas intake flowmeter 31 and the exhaust flowmeter 57 are respectively electrically connected to the control system.

[0041] Two inlet and outlet switching lift valves are respectively arranged at both lower ends of the regenerative oxidizer 50. A valve cavity capable of communicating with the inlet pipe box, the outlet pipe box and the regenerative chamber is provided in the inlet and outlet switching lift valve. A valve plate is arranged in the valve cavity. A driving assembly for driving the valve plate to block the valve openings of the inlet pipe box or the outlet pipe box is arranged at the upper end of the inlet and outlet switching lift valve. The driving assembly is a driving cylinder or a hydraulic cylinder. In this embodiment, the inlet and outlet switching lift valve includes a left inlet and outlet switching lift valve and a right inlet and outlet switching lift valve. The left inlet and outlet switching lift valve includes a left inlet pipe box 37, a left outlet pipe box 34, a left valve plate 35 and a left driving cylinder 39. The left driving cylinder 39 is provided with a left valve rod, and the left valve rod passes through the left valve rod support bearing 38 and is connected with the left valve plate 35. Similarly, the right inlet and outlet switching lift valve includes a right inlet pipe box 46, a right outlet pipe box 49, a right valve plate 47 and a right driving cylinder 44. The right driving cylinder 44 is provided with a right valve rod, and the right valve rod passes through the right valve rod support bearing 45 and is connected with the right valve plate 47. The left driving cylinder 39 and the right driving cylinder 44 are respectively electrically connected to the control system.

[0042] There are heat storage beds made of porous medium materials installed in the heat storage chambers on both sides of the regenerative thermal oxidizer 50. The heat storage beds can be composed of honeycomb ceramics, multi-layer stacked ceramic components, ceramic Intalox saddles, porcelain balls, etc. alone or in combination. A flow rectifying plate 42 and gradually inclined guide vanes 43 are arranged at the lower part of the heat storage bed. The flow rectifying plate 42 can be a perforated plate or a wire mesh, or a stacked structure of porous materials. The left guide vanes are arranged in a gradually inclined manner in the flow equalizing section 40 of the left flow rectifying plate, and the right guide vanes are arranged in a gradually inclined manner in the flow equalizing section 41 of the right flow rectifying plate. The arrangement of the flow rectifying plate 42 and the gradually inclined guide vanes 43 can make the gas enter the heat storage body more evenly, enable the heat storage body to fully absorb heat or preheat the gas, make the temperature field of the heat storage body more balanced, so that the gas entering the regenerative thermal oxidizer 50 can be evenly distributed, evenly heated, fully oxidized, improve the oxidation rate, thereby improving the waste heat utilization of the heat storage body and enhancing the safety and reliability of the regenerative thermal oxidizer; a gas burner and a flame monitoring system 54 are installed on the oxidation chamber 51. The gas burner and the flame monitoring system 54 are connected to a natural gas inlet pipeline 55 and a combustion-supporting air inlet pipeline 56. The ignition end of the gas burner and the flame monitoring system 54 is located inside the oxidation chamber 51. The burner can be a gas or oil combustion type burner. A first pressure sensor 52 and a first temperature sensor 53 are installed inside the oxidation chamber 51. The gas burner and the flame monitoring system 54, the first pressure sensor 52 and the first temperature sensor 53 are respectively electrically connected to the control system. A deep oxidation and honeycomb ceramic temperature equalizing heat storage bed TB is arranged at the upper part of the regenerative thermal oxidizer 50. A hot flue gas outlet is arranged at the top of the regenerative thermal oxidizer 50. The hot flue gas outlet is located above the deep oxidation and honeycomb ceramic temperature equalizing heat storage bed TB. The hot flue gas outlet is connected to a flue gas discharge pipe 59. The arrangement of the deep oxidation and temperature equalizing heat storage bed mainly serves to store a part of the heat in the oxidation chamber, can increase the heating rate of the oxidation chamber 51, enable the regenerative thermal oxidizer 50 to quickly reach the thermal self-equilibrium stable state, improve the heat storage and oxidation efficiency of the regenerative thermal oxidizer 50, and further reduce the control difficulty of the control system.

[0043] The once-through waste heat recovery steam production unit includes an once-through waste heat recovery furnace body 61, steam heat extraction pipes, a direct exhaust stack 73, a fan extraction exhaust stack 78, and an induced draft fan 77. Steam heat extraction pipes are arranged inside the once-through waste heat recovery furnace body 61. Steam is connected to the once-through waste heat recovery furnace body 61 through the steam heat extraction pipes. The steam heat extraction pipes include a steam heat extraction coil 67 and a steam inlet pipe 62 and a steam outlet pipe 71 connected to both ends thereof. The steam heat extraction coil 67 is located inside the once-through waste heat recovery furnace body 61. A softened water feed pump 63, a second temperature sensor 64, a flow meter 65, and a flow regulating valve 66 are sequentially arranged on the steam inlet pipe 62. A pressure control valve 70 and a steam-water separator 68 are sequentially arranged on the steam outlet pipe 71. A second pressure sensor 69 is arranged on the steam-water separator 68. The softened water feed pump 63, the second temperature sensor 64, the flow meter 65, the flow regulating valve 66, the pressure control valve 70, and the second pressure sensor 69 are respectively electrically connected to the control system.

[0044] The air inlet end of the once-through waste heat recovery furnace body 61 is connected to a flue gas discharge pipe 59. A flue gas temperature sensor 60 is arranged on the flue gas discharge pipe 59. The exhaust end of the once-through waste heat recovery furnace body 61 is respectively connected to the direct exhaust stack 73 and a fan inlet pipeline 74. A third temperature sensor 72 is arranged on the direct exhaust stack 73. Switching regulating valves are arranged on both the direct exhaust stack 73 and the fan inlet pipeline 74. The switching regulating valves include a first switching regulating valve 75 and a second switching regulating valve 76. The first switching regulating valve 75 is arranged on the direct exhaust stack 73. The second switching regulating valve 76 is arranged on the fan inlet pipeline 74. An induced draft fan 77 is arranged on the fan inlet pipeline 74. The induced draft fan 77 is connected to the fan extraction exhaust stack 78. A fourth temperature sensor 80 is arranged on the fan extraction exhaust stack 78. An exhaust stack waste heat extraction pipe 79 is arranged inside the fan extraction exhaust stack 78. The flue gas temperature sensor 60, the third temperature sensor 72, the first switching regulating valve 75, the second switching regulating valve 76, the induced draft fan 77, and the fourth temperature sensor 80 are respectively electrically connected to the control system.

[0045] An operation method of a low-concentration coal mine gas regenerative oxidation steam production device of the present invention includes the following steps:

[0046] S1: Device startup stage: First, start the three units of the two-stage gas concentration adjustment unit A, the gas regenerative oxidation unit B, and the once-through waste heat recovery steam production unit C respectively.

[0047] After the two-stage gas concentration adjustment unit A is started, first, through concentration detection and control of the high and low concentration gas flow ratio by the regulating valve, the gas is first mixed at the high-efficiency static first-stage mixer 21 to achieve the first-stage mixing of 0.3-1%V low-concentration gas and 3-9%V medium-concentration gas. After the first-stage mixing, the gas concentration is controlled at about 3%V. The gas after the first-stage mixing is then mixed with 0.3-1%V low-concentration gas again through concentration detection and control of the high and low concentration gas flow ratio by the regulating valve, and enters the high-efficiency static second-stage mixer 24 for second-stage mixing. After the second-stage mixing, the gas concentration reaches 1.2%V, meeting the intake conditions for subsequent gas regenerative thermal oxidation combustion, ensuring that the exhaust gas concentration entering the regenerative thermal oxidizer RTO50 is far from the methane gas explosion limit, and the oxidation combustion process is stable, safe, and controllable. As needed, the low-concentration gas that has been adjusted in two stages is controlled by the transfer and vent switching valve group to be temporarily vented or enter the next regenerative thermal oxidation unit B for treatment;

[0048] After the gas regenerative thermal oxidation unit B is started, first confirm that the low-concentration gas delivery valve 26 is in the closed state, open the air intake regulating valve 28. The air is preheated through heat exchange by the air supply fan 30, the left side inlet and outlet switching lift valve LPV, the left side inlet pipe box valve port 36, and the left side regenerative bed LB, and then enters the upper oxidation chamber 51 to be heated by the burner. The oxidation releases heat and transfers the heat to the right side regenerative bed RB. The exhaust gas after oxidation is discharged to the atmosphere through the right side inlet and outlet switching lift valve RPV, the right side outlet pipe box valve port 48, the exhaust pipeline, and the exhaust stack 58. After a certain period (generally 30S-120S), the two inlet and outlet switching lift valves are switched to raise the temperature of both regenerative beds to above 700°C. This cycle is repeated. After the low-concentration gas regenerative thermal oxidation unit B operates stably and the oxidation chamber 51 maintains an appropriate temperature, the system can enter the standby state and wait for the low-concentration gas from the previous two-stage gas concentration adjustment unit A to enter;

[0049] After the once-through waste heat utilization steam production unit C is started, first start the water-steam circulation system, start the softened water feed pump 63. The softened water is measured for temperature by the second temperature sensor 64, measured for flow by the flow meter 65, and adjusted by the flow regulating valve 66, and then enters the steam heat extraction coil in the once-through waste heat recovery furnace body 61, and then flows into the steam outlet steam-water separator 68 to form a softened water cycle; at this time, the switching regulating valves on the direct exhaust stack 73 and the fan inlet pipeline 74 are both in the closed state. When the softened water forms a stable cycle, the system enters the standby waiting state and waits for the high-temperature flue gas discharged from the previous regenerative thermal oxidation unit B to enter;

[0050] S2: Normal operation stage:

[0051] After the two-stage gas concentration adjustment unit A, the gas regenerative oxidation unit B, and the once-through waste heat recovery steam production unit C are started separately and can operate stably independently, the three units are put into linkage operation according to needs.

[0052] First, gradually close the low-concentration gas vent valve 27 on the pipeline at the rear end of the two-stage gas concentration adjustment unit A and gradually open the low-concentration gas delivery valve 26. The waste gas gradually enters the gas regenerative oxidation unit B. As the temperature of the oxidation chamber 51 rises, control and adjust to reduce the burner load through the control system CS. As the waste gas concentration and gas volume increase, when the temperature of the oxidation chamber 51 further rises to a certain control temperature, at this time, the regenerative thermal oxidizer RTO50 enters the thermal self-balanced stable maintenance state, and the burner maintains the minimum ignition state. Through this regenerative heat exchange, more than 95% of the combustion heat of the gas is efficiently recovered. As the waste gas concentration and flow rate increase, when the temperature of the oxidation chamber 51 continues to rise to a certain higher control temperature, the first switching regulating valve 75 on the direct exhaust pipe 73 in the once-through waste heat recovery steam production unit C is opened, and part of the excess hot flue gas enters the once-through waste heat recovery steam production unit C under self-pressure. The softened water is vaporized after heating to produce steam. The remaining part of the flue gas in the oxidation chamber 51 transfers heat to the heat storage body through another heat storage bed and is discharged through the exhaust pipe 58 of the regenerative oxidation unit. In the above process, the heat of the oxidized flue gas is distributed in a suitable proportion. Part of the excess hot flue gas is used to produce steam, and the other part of the hot flue gas is used to maintain the normal operation of the regenerative thermal oxidizer RTO50 self-sustainably; when the self-pressure of the flue gas is insufficient, the second switching regulating valve 76 on the pipeline at the inlet of the fan 74 in the once-through waste heat recovery steam production unit C can also be opened, the first switching regulating valve 75 is closed, and the induced draft fan 77 is started for flue gas induction. At this time, the waste heat of the flue gas can be further recovered through the waste heat extraction pipe 79 on the exhaust pipe at the outlet of the fan to produce hot water or preheat the softened water inlet.

[0053] The low-concentration coal mine gas regenerative oxidation steam production device of the present invention adopts two-stage gas concentration adjustment, realizes the safety mixing concentration control of low-concentration gas and medium- and high-concentration gas. After the gas is mixed through the aforementioned two-stage mixer, the gas concentration can be adjusted to about 1.2%V, which can meet the requirements for safe and stable subsequent regenerative oxidation combustion. The device has a simple structure, a small scale, and higher safety. At the same time, it can effectively utilize the excess heat of regenerative oxidation to produce steam, recover the gas resources while achieving environmental protection and low-carbon emission reduction. The device can flexibly select to produce steam or hot water according to user needs, and realize uses such as heat supply, power generation, and refrigeration.

[0054] The operation control method of the low-concentration coal mine gas heat storage oxidation steam production device of the present invention. The two-stage gas concentration adjustment unit, the gas heat storage oxidation unit, and the once-through waste heat recovery steam production unit are operationally controlled through a control system. Each unit can operate independently or be operationally controlled in association. The control system is provided with three different control units and has a safety interlock protection function. The operation interface is respectively provided with three unit process control interfaces, making the operation control clearer and more convenient. It can realize the concentration mixing adjustment of the two-stage gas concentration adjustment unit through the associated control of concentration detection and flow adjustment, the associated control of the inlet and outlet gas switching frequency of the gas heat storage oxidation unit with the exhaust temperature and the heat storage recovery efficiency, the associated control of the temperature of the oxidation chamber with the inlet gas concentration, flow rate, burner load, top exhaust volume, and bottom exhaust volume, and the associated control of the steam flow rate and pressure of the once-through waste heat recovery steam production unit with the flue gas temperature and flow rate.

[0055] The above content is a further detailed description of the present invention in combination with the preferred technical solutions, and it cannot be determined that the specific implementation of the invention is limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, simple deductions and substitutions can also be made, which should all be regarded as the protection scope of the present invention.

Claims

1. A low-concentration coal mine gas heat storage oxidation steam production device, characterized in that: It includes two-stage gas concentration adjustment units, a gas regenerative oxidation unit, a once-through waste heat recovery steam production unit, and a control system that are connected in sequence. The two-stage gas concentration adjustment units include a low-concentration gas pipeline, a medium-concentration gas pipeline, a first-stage mixer, and a second-stage mixer. The low-concentration gas pipeline is divided into three branches after passing through low-concentration gas extraction equipment. The first branch is connected to the first intake end of the first-stage mixer, the second branch is connected to the first intake end of the second-stage mixer, and the third branch is connected to the low-concentration gas return pipeline. The medium-concentration gas pipeline is connected to the second intake end of the first-stage mixer through medium-concentration gas extraction equipment. The outlet end of the first-stage mixer is connected to the second intake end of the second-stage mixer through a pipeline. The outlet end of the second-stage mixer is connected with a post-secondary mixing concentration detector and a conveying and venting switching valve group through a pipeline. The gas regenerative oxidation unit includes an induced draft fan, a regenerative oxidizer, and an exhaust stack. The intake end of the induced draft fan is connected to the conveying and venting switching valve group through a pipeline. The outlet end of the induced draft fan is connected to the inlet header of the inlet and outlet switching lift valve through an intake connection pipe. The outlet header of the inlet and outlet switching lift valve is connected to an outlet connection pipe and is connected to the exhaust stack through an outlet exhaust stack pipeline. The inlet and outlet switching lift valve is arranged at both lower ends of the regenerative oxidizer. A valve cavity capable of communicating with the inlet header, the outlet header, and the regenerative chamber is provided inside the inlet and outlet switching lift valve. A valve plate is arranged inside the valve cavity. A driving component for driving the valve plate to block the valve openings of the inlet header or the outlet header is arranged at the upper end of the inlet and outlet switching lift valve. A regenerative bed is arranged inside the regenerative chamber. A rectifying plate and gradually inclined guide vanes are arranged at the lower part of the regenerative bed. An oxidation chamber is arranged inside the regenerative oxidizer. A gas burner and a flame monitoring system are arranged on the oxidation chamber. The ignition end of the gas burner and the flame monitoring system is located inside the oxidation chamber. A deep oxidation and temperature-uniforming regenerative bed is arranged at the upper part of the regenerative oxidizer. A hot flue gas outlet is arranged at the top of the regenerative oxidizer. The hot flue gas outlet is located above the deep oxidation and temperature-uniforming regenerative bed. The hot flue gas outlet is connected with a flue gas discharge pipe. The once-through waste heat recovery steam production unit includes a once-through waste heat recovery furnace body, steam extraction pipes, a direct exhaust stack, a fan extraction exhaust stack, and an induced draft fan. Steam extraction pipes are arranged inside the once-through waste heat recovery furnace body. Steam is introduced into the once-through waste heat recovery furnace body through the steam extraction pipes. The intake end of the once-through waste heat recovery furnace body is connected to the flue gas discharge pipe. The exhaust end of the once-through waste heat recovery furnace body is respectively connected to the direct exhaust stack and a fan inlet pipeline. Switching regulating valves are arranged on both the direct exhaust stack and the fan inlet pipeline. An induced draft fan is arranged on the fan inlet pipeline. The induced draft fan is connected to the fan extraction exhaust stack. Exhaust stack waste heat extraction pipes are arranged inside the fan extraction exhaust stack. The control system is electrically connected to the low-concentration gas extraction equipment, the medium-concentration gas extraction equipment, the post-secondary mixing concentration detector, the conveying and venting switching valve group, the induced draft fan, the driving component, the gas burner and the flame monitoring system, the switching regulating valve, and the induced draft fan respectively.

2. The steam production device for low-concentration coal mine gas by regenerative oxidation according to claim 1, wherein: The steam heat extraction pipe includes a steam heat extraction coil and a steam inlet pipe and a steam outlet pipe connected to both ends thereof. The steam heat extraction coil is located inside a once-through waste heat recovery furnace. A softened water feed pump, a second temperature sensor, a flowmeter, and a flow regulating valve are sequentially arranged on the steam inlet pipe. A pressure control valve and a steam-water separator are sequentially arranged on the steam outlet pipe. A second pressure sensor is arranged on the steam-water separator. The softened water feed pump, the second temperature sensor, the flowmeter, the flow regulating valve, the pressure control valve, and the second pressure sensor are respectively electrically connected to a control system.

3. A low-concentration coal mine gas regenerative oxidation steam production device according to claim 1, characterized in that: A low-concentration gas dust and fog remover, a low-concentration pressure detector, a low-concentration detector, a low-concentration flowmeter, and a low-concentration flow regulating valve are arranged on the low-concentration gas pipeline. The low-concentration gas dust and fog remover is arranged at the front end of the low-concentration gas extraction device. The low-concentration pressure detector, the low-concentration detector, the low-concentration flowmeter, and the low-concentration flow regulating valve are sequentially arranged at the rear end of the low-concentration gas extraction device. The low-concentration pressure detector, the low-concentration detector, the low-concentration flowmeter, and the low-concentration flow regulating valve are respectively electrically connected to a control system.

4. A low-concentration coal mine gas regenerative oxidation steam production device according to claim 1, characterized in that: A medium-concentration gas dust and fog remover, a medium-concentration pressure detector, a medium-concentration detector, a medium-concentration flowmeter, and a medium-concentration flow regulating valve are arranged on the medium-concentration gas pipeline. The medium-concentration gas dust and fog remover is arranged at the front end of the medium-concentration gas extraction device. The medium-concentration pressure detector, the medium-concentration detector, the medium-concentration flowmeter, and the medium-concentration flow regulating valve are sequentially arranged at the rear end of the medium-concentration gas extraction device. The medium-concentration pressure detector, the medium-concentration detector, the medium-concentration flowmeter, and the medium-concentration flow regulating valve are respectively electrically connected to a control system.

5. A low-concentration coal mine gas regenerative oxidation steam production device according to claim 1, characterized in that: A primary shunt flowmeter and a primary flow regulating valve are arranged on the first branch. A secondary shunt flowmeter and a secondary flow regulating valve are arranged on the second branch. A low-concentration gas reflux control valve is arranged on the third branch. A low-concentration gas concentration detector after primary mixing and a low-concentration gas flowmeter after primary mixing are arranged on the connecting pipeline between the primary mixer and the secondary mixer. The primary shunt flowmeter, the primary flow regulating valve, the secondary shunt flowmeter, the secondary flow regulating valve, the low-concentration gas reflux control valve, the low-concentration gas concentration detector after primary mixing, and the low-concentration gas flowmeter after primary mixing are respectively electrically connected to a control system.

6. A low-concentration coal mine gas heat storage oxidation steam production device according to claim 1, characterized in that: A flame arrester is arranged on the pipeline between the transfer and vent switching valve group and the induced draft fan. An air inlet pipeline is communicated with the pipeline between the transfer and vent switching valve group and the flame arrester. An air inlet regulating valve is arranged on the air inlet pipeline. The air inlet regulating valve is electrically connected to a control system.

7. A low-concentration coal mine gas heat storage oxidation steam production device according to claim 1, characterized in that: A gas inlet flowmeter is arranged on the inlet connecting pipe. An exhaust flowmeter is arranged on the outlet exhaust chimney pipeline. The gas inlet flowmeter and the exhaust flowmeter are respectively electrically connected to a control system.

8. A low-concentration coal mine gas heat storage oxidation steam production device according to claim 1, characterized in that: A first pressure sensor and a first temperature sensor are arranged inside the oxidation chamber. The first pressure sensor and the first temperature sensor are respectively electrically connected to a control system.

9. A low-concentration coal mine gas heat storage oxidation steam production device according to claim 1, characterized in that: A flue gas temperature sensor is provided on the flue gas discharge pipe, a third temperature sensor is provided on the direct exhaust stack, and a fourth temperature sensor is provided on the fan exhaust stack. The flue gas temperature sensor, the third temperature sensor, and the fourth temperature sensor are respectively electrically connected to the control system.

10. An operation method of a low-concentration coal mine gas heat storage oxidation steam production device according to any one of claims 1 to 9, characterized in that: It includes the following steps: S1: Device startup phase: First, start the three units of the two-stage gas concentration adjustment unit, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit respectively. After the two-stage gas concentration adjustment unit is started, first, through concentration detection and control of the high and low concentration gas flow ratio by the regulating valve, the primary mixing of low concentration gas and medium concentration gas is achieved through the primary mixer. After the primary mixing, the gas concentration is controlled at about 3%V. The gas after the primary mixing is then mixed with the low concentration gas through concentration detection and control of the high and low concentration gas flow ratio by the regulating valve and enters the secondary mixer for mixing. After the secondary mixing, the gas concentration is controlled at about 1.2%V. The low concentration gas that has been adjusted in two stages is controlled by the transfer and vent switching valve group to be temporarily vented or enter the gas regenerative oxidation unit for treatment. After the gas regenerative oxidation unit is started, first confirm that the low concentration gas transfer valve is in the closed state, open the air intake regulating valve. The air is preheated through heat exchange through the air supply fan, the left side inlet and outlet switching lift valve, and the left side regenerative bed, and then enters the upper oxidation chamber to be heated by the burner, releasing heat and transferring the heat to the right side regenerative bed. The oxidized waste gas is discharged to the atmosphere through the right side inlet and outlet switching lift valve, the exhaust pipe, and the exhaust stack. After a certain period, the two inlet and outlet switching lift valves are switched to raise the temperature of both regenerative beds above 700°C. This cycle is repeated. After the gas regenerative oxidation unit operates stably and the oxidation chamber maintains an appropriate temperature, the system enters the standby state, waiting for the low concentration gas from the two-stage concentration adjustment unit to enter. After the once-through waste heat recovery steam production unit is started, first start the water-steam circulation system. The switching regulating valve on the direct exhaust stack and the switching regulating valve on the fan inlet pipeline are both in the closed state. When the softened water forms a stable circulation, the system enters the standby waiting state, waiting for the high-temperature flue gas discharged from the previous gas regenerative oxidation unit to enter. S2: Normal operation phase: After the three units of the two-stage gas concentration adjustment unit, the gas regenerative oxidation unit, and the once-through waste heat recovery steam production unit operate independently and stably, according to the need, the three units are put into linkage operation. First, gradually close the low-concentration vent valve and gradually open the low-concentration transfer valve on the pipeline at the rear end of the two-stage gas concentration adjustment unit. The waste gas gradually enters the gas regenerative thermal oxidation unit. As the temperature in the oxidation chamber rises, reduce the burner load. As the concentration and volume of the waste gas increase, when the temperature in the oxidation chamber further rises to a certain control temperature, the regenerative thermal oxidizer enters the thermal self-balanced stable state, and the burner maintains the minimum ignition state. As the concentration and flow rate of the waste gas increase, when the temperature in the oxidation chamber continues to rise to a certain higher control temperature, open the switching regulating valve on the direct exhaust stack of the once-through waste heat recovery steam production unit. Part of the excess hot flue gas enters the once-through waste heat recovery steam production unit under self-pressure. The softened water is vaporized after heating to produce steam. The remaining part of the flue gas in the oxidation chamber of the regenerative thermal oxidizer transfers heat to the regenerator through another regenerative bed and is discharged through the exhaust stack. When the self-pressure of the flue gas in the oxidation chamber is insufficient, open the switching regulating valve on the inlet pipeline of the fan, close the switching regulating valve on the direct exhaust stack, start the induced draft fan for flue gas induction, and further recover the waste heat of the flue gas through the waste heat extraction pipe on the exhaust stack at the fan outlet to produce hot water or preheat the softened water inlet.

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