System and method for recovering gas in banking period of gas heating furnace based on hydrogen-rich carbon circulating oxygen blast furnace

Abstract

The invention belongs to the technical field of gas heating furnaces, and particularly discloses a system and method for recovering gas in a banking period of a gas heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace. The system comprises the gas heating furnace and a chimney, the gas heating furnace is communicated with a flue and a furnace burning gas pipe, the flue is communicated with the chimney, and a flue valve is arranged on the flue; the flue is communicated with a connecting pipe, the connecting pipe is provided with a stop valve, the connecting pipe is communicated with a recovery pipe, the recovery pipe is provided with a recovery valve, one end of the recovery pipe is communicated with a purification buffer tank, the outlet end of the purification buffer tank is communicated with a gas pipe, the gas pipe is communicated with a burning furnace gas pipe, and one end, close to an inlet of the purification buffer tank, of the recovery pipe is provided with a first pressure regulating valve; and a second pressure regulating valve is arranged on the gas pipe. The problem that when the gas heating furnace is switched to the banking state, energy waste and environment pollution are caused is solved. The high-pressure hydrogen-rich gas in the banking state is recycled to the furnace burning gas pipe for cyclic utilization, energy waste is reduced, and closed-loop utilization of energy is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas heating furnaces, and in particular to a gas recovery system and method during the stewing period of a gas heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace. Background Art

[0002] The steel industry is currently facing increasingly stringent environmental regulations and fierce market competition. Enterprises must achieve energy conservation, emission reduction, cost reduction, and efficiency improvement through technological innovation. With the advancement of global carbon reduction policies, carbon emissions from traditional blast furnace processes are becoming increasingly prominent. The Hydrogen-Enriched Carbon Recycled Oxygen Blast Furnace (HyCROF) technology, which injects hot coal gas into the tuyere of a gas-fired furnace after heating it, achieves efficient recycling of the chemical and thermal energy of the coal gas, becoming a key direction for industry transformation and upgrading. During the conversion of the gas-fired furnace to a simmering furnace, the residual 0.30 MPa high-pressure hydrogen-rich coal gas (H2 ≥ 35%, CO ≥ 45%) is typically combusted in a flare tower before being discharged.

[0003] Every time the gas heating furnace switches to the stewing state, about 20,000 to 30,000 cubic meters of high-calorific value gas is directly burned and released. The annual cumulative release volume is as high as 12 million cubic meters, which is equivalent to the loss of 15,000 tons of standard coal, resulting in energy waste. At the same time, in actual operation, incomplete combustion of gas will cause CO emission concentration to exceed the standard, which is easy to cause environmental pollution. Summary of the Invention

[0004] The purpose of the present invention is to provide a gas recovery system and method for the stewing period of a gas heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace, so as to solve the problems of energy waste and environmental pollution when the gas heating furnace is switched to the stewing state.

[0005] In order to achieve the above-mentioned purpose, the basic scheme provided by the present invention is: a coal gas recovery system for the coal gas heating furnace during the stewing period based on a hydrogen-rich carbon circulating oxygen blast furnace, comprising a coal gas heating furnace, a chimney and a flare tower, wherein the coal gas heating furnace is respectively connected with a flue, a furnace gas pipe, a cold coal gas inlet pipe and a hot coal gas exhaust pipe, the furnace gas pipe, the cold coal gas inlet pipe and the hot coal gas exhaust pipe are all provided with a switch valve, a thermocouple and a pressure sensor are respectively provided in the coal gas heating furnace, the flue is connected with the chimney, a flue valve is provided on the flue, the flue is connected with a connecting pipe, a stop valve is provided on the connecting pipe, the connecting pipe is respectively connected with a vent pipe and a recovery pipe, the vent pipe and the recovery pipe are A relief valve and a recovery valve are respectively provided on the pipes. The relief pipe is connected to the flare tower. One end of the recovery pipe is connected to a purification buffer tank. The outlet end of the purification buffer tank is connected to a gas pipe. The gas pipe is connected to the furnace gas pipe. A first pressure regulating valve and a second pressure sensor are provided at one end of the recovery pipe close to the inlet of the purification buffer tank. A second pressure regulating valve, a third pressure sensor and a flow meter are provided on the gas pipe. The thermocouple, the first pressure sensor, the first flue valve, the stop valve, the relief valve, the recovery valve, the first pressure regulating valve, the second pressure sensor, the second pressure regulating valve, the third pressure sensor and the flow meter are all electrically connected to a PLC controller, and the PLC controller is electrically connected to the main unit in the central control room.

[0006] The working principle of the present invention is as follows: when the temperature of the heating gas transported by the gas heating furnace to the hydrogen-rich carbon circulating oxygen blast furnace is lower than 1250°C and the pressure is lower than 0.25 MPa, and the switch valves of the cold gas inlet pipe and the hot gas exhaust pipe are closed, the gas heating furnace is switched from the air supply state to the furnace stewing state, and then the main host of the central control room shuts down the flue valve, opens the stop valve and the recovery valve, and the gas in the gas heating furnace enters the recovery pipe through the flue and the connecting pipe. Then the main host of the central control room calculates the openings of the first pressure regulating valve and the second pressure regulating valve according to the gas pressure state in the furnace gas pipe. After the calculation is completed, the main host of the central control room adjusts the openings of the first pressure regulating valve and the second pressure regulating valve to the calculated values ​​so that the pressure of the recovered gas is equal to the pressure of the furnace gas. The recovered gas in the recovery pipe enters the furnace gas pipe through the purification buffer tank and the gas pipe for recovery. When the pressure in the gas heating furnace drops to 10 kPa, the gas recovery is completed, the main host of the central control room closes the stop valve and the recovery valve, and opens the flue valve.

[0007] The beneficial effects of the present invention are: 1. By recycling the high-pressure hydrogen-rich coal gas in the stewing state to the furnace burning gas pipe for recycling, energy waste is reduced, and the recycled coal gas has a high calorific value and can be directly used for combustion in the heating furnace, thereby realizing closed-loop energy utilization; 2. It can also avoid the problem of CO exceeding the standard caused by traditional torch combustion emissions and eliminate the environmental pollution risk caused by incomplete combustion; 3. Through the linkage of the PLC controller with the pressure sensor and the pressure regulating valve, the main host in the central control room dynamically calculates the valve opening, adjusts the recovered coal gas pressure in real time, reduces the pressure fluctuation of the recovered coal gas and the furnace burning gas, and ensures the safe and stable operation of the system.

[0008] Option 2 is the preferred option of the basic option. The recovery pipe is connected to a nitrogen pipe, one end of which is connected to a nitrogen tank, and a purge valve is provided on the nitrogen pipe. By setting up the nitrogen pipe and the nitrogen tank, nitrogen is used to drive out the gas in the recovery pipe and the purification buffer tank, so that the gas can be fully recovered.

[0009] Option three is the preferred option of the basic option. A bag dust collector is provided on the recovery pipe; dust in the coal gas is removed by the bag dust collector.

[0010] Scheme 4: A method for recovering gas during the simmering period of a gas-fired heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace, comprising the following steps: S1. When the temperature of the heating gas supplied by the gas heating furnace to the hydrogen-rich carbon circulating oxygen blast furnace is lower than 1250°C and the pressure is lower than 0.25 MPa, and the on-off valves on the cold gas inlet pipe and the hot gas exhaust pipe are closed, the gas heating furnace switches from the air supply state to the furnace stewing state; S2. After the gas heating furnace is switched to the stewing state, the main control room shuts down the flue valve, opens the stop valve and the recovery valve, and the gas in the gas heating furnace flows into the recovery pipe through the flue and the connecting pipe; S3. The host computer in the central control room calculates the opening of the first and second pressure regulating valves according to the gas pressure status in the furnace gas pipe; S4. After the calculation is completed, the host computer in the central control room adjusts the openings of the first and second pressure regulating valves to the calculated values, so that the pressure of the recovered gas is equal to the pressure of the boiler gas. The recovered gas in the recovery pipe enters the boiler gas pipe through the purification buffer tank and the gas pipe, thereby being recovered; S5. When the pressure in the gas heating furnace drops to 10kPa, the gas recovery is completed, close the stop valve and recovery valve, and open the flue valve.

[0011] Solution 5, which is a preferred solution of Solution 4, in S3, the calculation formula for the opening of the first pressure regulating valve is as follows: in: Where: is the opening of the first pressure regulating valve; is the maximum flow rate when the first pressure regulating valve is fully open; The flow rate required by the first pressure regulating valve in the current working condition; Indicates the volume flow rate upstream of the first pressure regulating valve; is the pressure drop of the first pressure regulating valve; is the mass at the outlet of the first pressure regulating valve; is the density before the first pressure regulating valve; is the absolute pressure at the outlet of the first pressure regulating valve; is the gas constant; is temperature; is the flow rate at the outlet of the first pressure regulating valve; The absolute pressure of the purification buffer tank; is the downstream pressure of the second pressure regulating valve; is the pressure drop of the second pressure regulating valve; is the flow rate at the outlet of the second pressure regulating valve; It is the maximum flow rate when the second pressure regulating valve is fully open.

[0012] Solution 6, which is a preferred solution of Solution 5, in S3, the calculation formula for the opening of the second pressure regulating valve is as follows: Where: is the opening of the second pressure regulating valve; is the maximum flow rate when the second pressure regulating valve is fully open; The flow rate required by the second pressure regulating valve in the current working condition.

[0013] Option 7 is the preferred option of Option 4. In S5, when the pressure in the gas heating furnace drops to 10kPa, the main engine in the central control room opens the purge valve, and the nitrogen in the nitrogen tank enters the purification buffer tank through the nitrogen pipe, driving the residual gas into the furnace gas pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a structural schematic diagram of a coal gas recovery system during the stewing period of a coal gas heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below through specific embodiments: The figure marks in the drawings of the specification include: 1. gas heating furnace; 2. chimney; 3. flare tower; 4. flue; 5. furnace gas pipe; 6. cold gas inlet pipe; 7. hot gas exhaust pipe; 8. switch valve; 9. thermocouple; 10. pressure sensor 1; 11. flue valve; 12. connecting pipe; 13. stop valve; 14. vent pipe; 15. recovery pipe; 16. vent valve; 17. recovery valve; 18. purification buffer tank; 19. gas pipe; 20. first pressure regulating valve; 21. second pressure regulating valve; 22. second pressure regulating valve; 23. third pressure sensor; 24. flow meter; 25. nitrogen pipe; 26. nitrogen tank; 27. purge valve; 28. bag filter.

[0016] Example 1 like Figure 1 As shown: A coal gas heating furnace stewing period coal gas recovery system based on a hydrogen-rich carbon cycle oxygen blast furnace, comprising a coal gas heating furnace 1, a chimney 2 and a flare tower 3, the coal gas heating furnace 1 is respectively connected with a flue 4, a furnace gas pipe 5, a cold coal gas inlet pipe 6 and a hot coal gas exhaust pipe 7, the furnace gas pipe 5, the cold coal gas inlet pipe 6 and the hot coal gas exhaust pipe 7 are each provided with a switch valve 8, a thermocouple 9 and a pressure sensor 10 are respectively provided in the coal gas heating furnace 1, the flue 4 is connected with the chimney 2, a flue valve 11 is provided on the flue 4, the flue 4 is connected with a connecting pipe 12, a stop valve 13 is provided on the connecting pipe 12, the connecting pipe 12 is respectively connected with a vent pipe 14 and a recovery pipe 15, a vent valve 16 and a recovery valve 17 are respectively provided on the vent pipe 14 and the recovery pipe 15, the vent pipe 14 is connected with the flare tower 3, and one end of the recovery pipe 15 is connected with a purification buffer Tank 18, the outlet end of the purification buffer tank 18 is connected with a gas pipe 19, the gas pipe 19 is connected with the furnace gas pipe 5, and the end of the recovery pipe 15 near the inlet of the purification buffer tank 18 is provided with a first pressure regulating valve 20, a second pressure sensor 21 and a bag dust collector 28. The recovery pipe 15 is connected with a nitrogen pipe 25, one end of the nitrogen pipe 25 is connected with a nitrogen tank 26, and a purge valve 27 is provided on the nitrogen pipe 25. The gas pipe 19 is provided with a second pressure regulating valve 22, a third pressure sensor 23 and a flow meter 24. The thermocouple 9, pressure sensor 10, flue valve 11, stop valve 13, bleed valve 16, recovery valve 17, the first pressure regulating valve 20, the second pressure regulating valve 21, the second pressure regulating valve 22, the third pressure sensor 23 and the flow meter 24 are all electrically connected to the PLC controller, and the PLC controller is electrically connected to the host computer in the central control room.

[0017] Through the present invention, the monthly gas recovery volume can reach 300,000 cubic meters (under standard conditions), which is converted into a monthly energy recovery price of 94,500 yuan; by recycling and reusing the blast furnace equalized pressure gas, it can not only effectively reduce dust, gas and noise pollution, meet the environmental protection requirements of clean production, but also help increase energy utilization and improve the economic benefits of the factory.

[0018] The implementation method of this embodiment is as follows: when the temperature of the heating gas delivered by the gas heating furnace 1 to the hydrogen-rich carbon circulating oxygen blast furnace is lower than 1250°C and the pressure is lower than 0.25 MPa, and the switch valves 8 on the cold gas inlet pipe 6 and the hot gas exhaust pipe 7 are closed, the gas heating furnace 1 is switched from the air supply state to the furnace-stove state, and then the main control room shuts down the flue valve 11, opens the stop valve 13 and the recovery valve 17, and the gas in the gas heating furnace 1 enters the recovery pipe 15 through the flue 4 and the connecting pipe 12. Then the main control room calculates the opening of the first pressure regulating valve 20 and the second pressure regulating valve 22 according to the gas pressure state in the furnace gas pipe 5. After the calculation is completed, After completion, the main unit in the central control room adjusts the opening of the first pressure regulating valve 20 and the second pressure regulating valve 22 to the calculated value, so that the pressure of the recovered gas is equal to the pressure of the furnace gas, and the recovered gas in the recovery pipe 15 enters the furnace gas pipe 5 through the purification buffer tank 18 and the gas pipe 19 for recovery. When the pressure in the gas heating furnace 1 is reduced to 10kPa, the gas recovery is completed, and the main unit in the central control room opens the purge valve 27, and the nitrogen in the nitrogen tank 26 enters the purification buffer tank 18 through the nitrogen pipe 25, driving the residual gas into the furnace gas pipe 5, then closes the stop valve 13 and the recovery valve 17, and opens the flue valve 11.

[0019] Example 2 A method for recovering gas during the stewing period of a gas heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace comprises the following steps: S1. When the temperature of the heating gas supplied by the gas heating furnace 1 to the hydrogen-rich carbon circulating oxygen blast furnace is lower than 1250°C and the pressure is lower than 0.25 MPa, and the on-off valves 8 on the cold gas inlet pipe 6 and the hot gas exhaust pipe 7 are closed, the gas heating furnace 1 switches from the air supply state to the furnace stewing state; S2: After the gas heating furnace 1 is switched to the stewing state, the main control room shuts down the flue valve 11, opens the stop valve 13 and the recovery valve 17, and the gas in the gas heating furnace 1 enters the recovery pipe 15 through the flue 4 and the connecting pipe 12; S3. The host computer in the central control room calculates the openings of the first pressure regulating valve 20 and the second pressure regulating valve 22 according to the gas pressure state in the furnace gas pipe 5. The calculation formula for the opening of the first pressure regulating valve 20 is as follows: in: Where: is the opening of the first pressure regulating valve; is the maximum flow rate when the first pressure regulating valve is fully open; The flow rate required by the first pressure regulating valve in the current working condition; Indicates the volume flow rate upstream of the first pressure regulating valve; is the pressure drop of the first pressure regulating valve; is the mass at the outlet of the first pressure regulating valve; is the density before the first pressure regulating valve; is the absolute pressure at the outlet of the first pressure regulating valve; is the gas constant; is temperature; is the flow rate at the outlet of the first pressure regulating valve; The absolute pressure of the purification buffer tank; is the downstream pressure of the second pressure regulating valve; is the pressure drop of the second pressure regulating valve; is the flow rate at the outlet of the second pressure regulating valve; is the maximum flow rate when the second pressure regulating valve is fully open; The calculation formula of the opening degree of the second pressure regulating valve 22 is as follows: Where: is the opening of the second pressure regulating valve; is the maximum flow rate when the second pressure regulating valve is fully open; The flow rate required by the second pressure regulating valve in the current working condition; S4. After the calculation is completed, the host computer in the central control room adjusts the openings of the first pressure regulating valve 20 and the second pressure regulating valve 22 to the calculated values, so that the pressure of the recovered gas is equal to the pressure of the boiler gas. The recovered gas in the recovery pipe 15 enters the boiler gas pipe 5 through the purification buffer tank 18 and the gas pipe 19 for recovery. S5. When the pressure in the gas heating furnace 1 drops to 10 kPa, the gas recovery is completed. The main engine in the central control room opens the purge valve 27, and the nitrogen in the nitrogen tank 26 enters the purification buffer tank 18 through the nitrogen pipe 25, driving the residual gas into the furnace gas pipe 5. Then the stop valve 13 and the recovery valve 17 are closed, and the flue valve 11 is opened.

[0020] Example 3 A method for recovering gas during the stewing period of a gas heating furnace based on a hydrogen-rich carbon circulating oxygen blast furnace comprises the following steps: S1. When the temperature of the heating gas supplied by the gas heating furnace 1 to the hydrogen-rich carbon circulating oxygen blast furnace is lower than 1250°C and the pressure is lower than 0.25 MPa, and the on-off valves 8 on the cold gas inlet pipe 6 and the hot gas exhaust pipe 7 are closed, the gas heating furnace 1 switches from the air supply state to the furnace stewing state; S2: After the gas heating furnace 1 is switched to the stewing state, the main control room shuts down the flue valve 11, opens the stop valve 13 and the recovery valve 17, and the gas in the gas heating furnace 1 enters the recovery pipe 15 through the flue 4 and the connecting pipe 12; S3. The host computer in the central control room calculates the openings of the first pressure regulating valve 20 and the second pressure regulating valve 22 according to the gas pressure state in the furnace gas pipe 5. The calculation formula for the opening of the first pressure regulating valve 20 is as follows: Among them are known: , , , , , , , , the specific calculation steps are as follows: Where: is the opening of the first pressure regulating valve; is the maximum flow rate when the first pressure regulating valve is fully open; The flow rate required by the first pressure regulating valve in the current working condition; Indicates the volume flow rate upstream of the first pressure regulating valve; is the pressure drop of the first pressure regulating valve; is the mass at the outlet of the first pressure regulating valve; is the density before the first pressure regulating valve; is the absolute pressure at the outlet of the first pressure regulating valve; is the gas constant; is temperature; is the flow rate at the outlet of the first pressure regulating valve; The absolute pressure of the purification buffer tank; is the downstream pressure of the second pressure regulating valve; is the pressure drop of the second pressure regulating valve; is the flow rate at the outlet of the second pressure regulating valve; is the maximum flow rate when the second pressure regulating valve is fully open; The calculation formula of the opening degree of the second pressure regulating valve 22 is as follows: Among them are known: , , the specific calculation steps are as follows: Where: is the opening of the second pressure regulating valve; is the maximum flow rate when the second pressure regulating valve is fully open; The flow rate required by the second pressure regulating valve in the current working condition; S4. After the calculation is complete, the opening of the first pressure regulating valve is 21%, and the opening of the second pressure regulating valve is 100%. Therefore, the host computer in the central control room adjusts the openings of the first pressure regulating valve 20 and the second pressure regulating valve 22 to 21% and 100%, respectively, so that the pressure of the recovered gas is equal to that of the boiler gas. The recovered gas in the recovery pipe 15 enters the boiler gas pipe 5 through the purification buffer tank 18 and the gas pipe 19 for recovery. S5. When the pressure in the gas heating furnace 1 drops to 10 kPa, the gas recovery is completed. The main engine in the central control room opens the purge valve 27, and the nitrogen in the nitrogen tank 26 enters the purification buffer tank 18 through the nitrogen pipe 25, driving the residual gas into the furnace gas pipe 5. Then the stop valve 13 and the recovery valve 17 are closed, and the flue valve 11 is opened.

[0021] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A coal gas recovery system for a coal gas heating furnace during the stewing period based on a hydrogen-rich carbon cycle oxygen blast furnace, characterized in that: The invention comprises a gas heating furnace (1), a chimney (2) and a flare tower (3), wherein the gas heating furnace (1) is connected to a flue (4), a furnace gas pipe (5), a cold gas inlet pipe (6) and a hot gas exhaust pipe (7), respectively, and the furnace gas pipe (5), the cold gas inlet pipe (6) and the hot gas exhaust pipe (7) are all provided with a switch valve (8), and the gas heating furnace (1) is provided with a thermocouple (9) and a pressure sensor (10), respectively. (4) is connected to the chimney (2), the flue (4) is provided with a flue valve (11), the flue (4) is connected to a connecting pipe (12), the connecting pipe (12) is provided with a stop valve (13), the connecting pipe (12) is respectively connected to a vent pipe (14) and a recovery pipe (15), the vent pipe (14) and the recovery pipe (15) are respectively provided with a vent valve (16) and a recovery valve (17), the vent pipe (14) is connected to the flare The tower (3) is connected, one end of the recovery pipe (15) is connected to the purification buffer tank (18), the outlet end of the purification buffer tank (18) is connected to the gas pipe (19), the gas pipe (19) is connected to the furnace gas pipe (5), the end of the recovery pipe (15) close to the inlet of the purification buffer tank (18) is provided with a first pressure regulating valve (20) and a second pressure sensor (21), the gas pipe (19) is provided with a second pressure regulating valve (22), a third pressure sensor (23) and a flow meter (24), the thermocouple (9), the first pressure sensor (10), the flue valve (11), the stop valve (13), the relief valve (16), the recovery valve (17), the first pressure regulating valve (20), the second pressure sensor (21), the second pressure regulating valve (22), the third pressure sensor (23) and the flow meter (24) are all electrically connected to a PLC controller, and the PLC controller is electrically connected to the host computer in the central control room.

2. The coal gas recovery system for the coal gas heating furnace during the stewing period based on the hydrogen-rich carbon cycle oxygen blast furnace according to claim 1 is characterized in that: The recovery pipe (15) is connected to a nitrogen pipe (25), one end of the nitrogen pipe (25) is connected to a nitrogen tank (26), and a purge valve (27) is provided on the nitrogen pipe (25).

3. The coal gas recovery system for the coal gas heating furnace during the stewing period based on the hydrogen-rich carbon cycle oxygen blast furnace according to claim 1 is characterized in that: The recovery pipe (15) is provided with a bag dust collector (28).

4. A method for recovering gas from a gas heating furnace during the burnout period of a hydrogen-rich carbon cycle oxygen blast furnace according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. When the temperature of the heating gas delivered by the gas heating furnace (1) to the hydrogen-rich carbon circulating oxygen blast furnace is lower than 1250°C and the pressure is lower than 0.25 MPa, and the switch valves (8) on the cold gas inlet pipe (6) and the hot gas exhaust pipe (7) are closed, the gas heating furnace (1) changes from the air supply state to the furnace stewing state; S2. After the gas heating furnace (1) is switched to the stewing state, the main control room shuts down the flue valve (11), opens the stop valve (13) and the recovery valve (17), and the gas in the gas heating furnace (1) enters the recovery pipe (15) through the flue (4) and the connecting pipe (12); S3, the main engine in the central control room calculates the opening of the first pressure regulating valve (20) and the second pressure regulating valve (22) according to the gas pressure state in the furnace gas pipe (5); S4. After the calculation is completed, the host computer in the central control room adjusts the opening of the first pressure regulating valve (20) and the second pressure regulating valve (22) to the calculated value, so that the pressure of the recovered gas is equal to the pressure of the boiler gas, and the recovered gas in the recovery pipe (15) enters the boiler gas pipe (5) through the purification buffer tank (18) and the gas pipe (19) for recovery; S5. When the pressure in the gas heating furnace (1) drops to 10 kPa, the gas recovery is completed, the stop valve (13) and the recovery valve (17) are closed, and the flue valve (11) is opened.

5. The method for recovering coal gas during the burnout period of a gas heating furnace based on a hydrogen-rich carbon cycle oxygen blast furnace according to claim 4, characterized in that: In S3, the calculation formula of the opening of the first pressure regulating valve (20) is as follows: in: Where: is the opening of the first pressure regulating valve; is the maximum flow rate when the first pressure regulating valve is fully open; The flow rate required by the first pressure regulating valve in the current working condition; Indicates the volume flow rate upstream of the first pressure regulating valve; is the pressure drop of the first pressure regulating valve; is the mass at the outlet of the first pressure regulating valve; is the density before the first pressure regulating valve; is the absolute pressure at the outlet of the first pressure regulating valve; is the gas constant; is temperature; is the flow rate at the outlet of the first pressure regulating valve; The absolute pressure of the purification buffer tank; is the downstream pressure of the second pressure regulating valve; is the pressure drop of the second pressure regulating valve; is the flow rate at the outlet of the second pressure regulating valve; It is the maximum flow rate when the second pressure regulating valve is fully open.

6. The method for recovering coal gas during the burnout period of a gas heating furnace based on a hydrogen-rich carbon cycle oxygen blast furnace according to claim 5, characterized in that: In S3, the calculation formula of the opening of the second pressure regulating valve (22) is as follows: Where: is the opening of the second pressure regulating valve; is the maximum flow rate when the second pressure regulating valve is fully open; The flow rate required by the second pressure regulating valve in the current working condition.

7. The method for recovering coal gas during the burnout period of a gas heating furnace based on a hydrogen-rich carbon cycle oxygen blast furnace according to claim 4, characterized in that: In S5, when the pressure in the gas heating furnace (1) drops to 10 kPa, the main engine in the central control room opens the purge valve (27), and the nitrogen in the nitrogen tank (26) enters the purification buffer tank (18) through the nitrogen pipe (25), driving the residual gas into the furnace gas pipe (5).

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