Blast furnace gas double-heat-storage type heating furnace oxygen-fuel combustion air-smoke zero-emission coupling system

Abstract

The invention relates to the technical field of regenerative heating furnaces, in particular to a blast furnace gas double-regenerative heating furnace oxygen-fuel combustion air and smoke zero emission coupling system which comprises a regenerative heating furnace, a reversing valve, a gas burner, an air burner, a pure oxygen nozzle, a gas pipeline, a soot pipeline, an air and smoke pipeline, a smoke return pipeline and a pure oxygen pipeline. A gas burner and an air burner are arranged on the furnace walls of the two sides of the heat accumulating type heating furnace, a pure oxygen nozzle is arranged between the gas burner and the air burner, the gas burner is connected with a gas pipeline and a soot pipeline through a reversing valve, and the pure oxygen nozzle is connected with a pure oxygen pipeline through an oxygen fast switching valve. The pure-oxygen combustion and air-smoke total-reflux oxygen-deficient combustion combined burner has the beneficial effects that pure-oxygen combustion and air-smoke total-reflux oxygen-deficient combustion are combined, so that the production effects of energy conservation, emission reduction, pollution reduction, carbon reduction and low cost are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of regenerative heating furnaces, and particularly to an all-oxygen combustion and zero-emission coupling system for a double regenerative heating furnace using blast furnace gas with empty flue gas. Background Art

[0002] Traditional double regenerative heating furnaces adopt an air and gas reversing regenerative system, which mainly has the following defects:

[0003] 1) Its fatal shortcoming is that the furnace pressure is high, fluctuates frequently, is unstable and non-adjustable; there is gas leakage during the reversing process, wasting fuel and adding pollution; the power consumption of the blower and induced draft fan is large, and the operation and maintenance cost is high.

[0004] 2) Whether it is the upper and lower nozzle mixing or the left and right nozzle mixing of air and gas in traditional double regenerative furnaces, there are defects such as different degrees of large oxidation and burnout, high nitrogen oxide concentration, and excessive particulate matter; even a complete desulfurization, denitrification and high-efficiency dust removal system needs to be equipped to meet the ultra-low emission requirements, greatly increasing the operation cost.

[0005] 3) The calorific value of blast furnace gas is low (usually <800 kcal / Nm 3 ), although the double regenerative technology is adopted, it is difficult to achieve stable combustion in the high-temperature zone with a temperature regime requirement above 1300°C using conventional air as the combustion-supporting agent.

[0006] 4) The exhaust gas temperature of the regenerator is still relatively high, generally greater than 150°C, and in some cases, it is 200°C or higher. The residual oxygen in the flue gas often exceeds 12%, and there is still energy waste and NOx pollution.

[0007] 5) According to the law of conservation of water equivalent in the heat exchange process, about 30% - 40% of the high-temperature flue gas does not participate in the heat exchange process of the regenerator during the production process of the regenerative heating furnace. This part of the high-temperature flue gas is a dead zone retained in the furnace, and even if it is discharged through the auxiliary flue, heat waste is inevitable.

[0008] Advanced all-oxygen and oxygen-enriched combustion technologies have been widely applied in conventional rolling heating furnaces, making great contributions to energy conservation, emission reduction, pollution reduction, carbon reduction and low burnout stable production of heating furnaces; however, there is no pioneering case for directly applying them to existing regenerative heating furnaces; industry calculations show that when directly applying them to existing regenerative heating furnaces, the oxygen consumption is large, the energy-saving benefit is not obvious, and there are compatibility problems with the current reversing system, which need to be solved by revolutionary technological innovation methods.

[0009] Difficulties in applying all-oxygen and oxygen-enriched combustion in regenerative heating furnaces:

[0010] 1) The mechanism of regenerative combustion makes full use of the regenerator as a heat carrier, transfers the waste heat of high-temperature exhaust gas to the incoming air and gas through storage and commutation heat exchange, maximizes the heat enthalpy of the incoming gas medium, and the exhaust gas temperature is more than 200 °C lower than that of the conventional heating furnace with double preheating of air and gas, so it is energy-saving; its superiority is that it meets the conditions for steelmaking with low-calorie gas. Low-calorie gas is a by-product of long-process iron and steel production and is inexpensive, while oxy-fuel and enriched-oxygen combustion consume about five times more oxygen than its cost. It is difficult to further tap potential and improve on the existing energy-saving effect.

[0011] 2) Regenerative combustion adopts the commutation mechanism, and it is difficult to couple the oxy-fuel burner and the existing air and gas regenerative burners; because there are furnace columns between the regenerative burners, the furnace structure and the layout of the furnace beam are all factors affecting the layout of the additional oxygen burner or oxygen lance. One of the problems faced when embedded in the regenerative burner body is that the high temperature in the furnace will affect the service life of the oxygen burner, and at the same time, the high temperature of oxygen combustion will burn out the regenerator; another is the risk of backflow of flue gas in the oxygen burner during the commutation operation.

[0012] 3) The furnace temperature of oxy-fuel and enriched-oxygen combustion is 100 - 300 °C higher than that of conventional combustion, and the flue gas volume is significantly reduced. Applying it to the existing regenerative heating furnace requires technological innovation. One is to solve the influence of the reduced flue gas volume on weakening convective heat transfer, the second is to avoid local high temperature affecting the furnace temperature uniformity and the influence on the nitrogen oxide index caused by the high temperature area, and the third is to carry out simulation for oxy-fuel combustion in the regenerative furnace to reasonably arrange the installation position of the oxygen lance or oxygen burner, and the problem of installation space also needs to be solved. Summary of the Invention

[0013] In order to overcome the deficiencies of the prior art, the present invention provides a coupling system for oxy-fuel combustion and zero-emission of empty flue gas in a blast furnace gas double-regenerative heating furnace. Through the process method of zero-emission of all empty flue gas returning to the furnace, the technology of all empty flue gas returning to the furnace + staged pure oxygen injection is adopted, and the coupling technology of gradient oxy-fuel combustion and under-oxygen combustion with empty flue gas reflux is implemented. The coal flue gas is discharged as usual, and the gas backwashing system is retained. The upgrade of the oxy-fuel automatic control system is synchronized with the integration of the original system to achieve the production effects of energy saving, emission reduction, pollution reduction, carbon reduction, and low cost, and provide a complete set of new equipment and systems for oxy-fuel participation in regenerative combustion with extreme energy efficiency, ultra-low environmental emissions, and no pollution.

[0014] To achieve the above object, the present invention is realized by adopting the following technical solutions:

[0015] A coupling system for all-oxygen combustion and zero-emission of empty flue gas in a blast furnace gas double regenerative reheating furnace, comprising a regenerative reheating furnace, a reversing valve, a gas burner, an air burner, a pure oxygen nozzle, a gas pipeline, a coal smoke pipeline, an empty flue gas pipeline, a return flue gas pipeline and a pure oxygen pipeline. The regenerative reheating furnace is provided with regenerative gas burners and air burners on both side furnace walls. A pure oxygen nozzle is arranged between the gas burner and the air burner. The gas burner is connected to the gas pipeline and the coal smoke pipeline respectively through the reversing valve. The air burner is connected to the return flue gas pipeline and the empty flue gas pipeline respectively through the reversing valve. The pure oxygen nozzle is connected to the pure oxygen pipeline. The empty flue gas pipeline is respectively connected to the suction ports of an empty flue gas induced draft fan and a combustion-supporting fan, and pneumatic quick cut valves are installed on both inlet pipelines connected to the fans. The outlet pipelines of the empty flue gas induced draft fan and the combustion-supporting fan are both connected to the return flue gas pipeline through electric shut-off valves. A relief pipeline is provided at the high point of the outlet pipeline of the empty flue gas induced draft fan and an electric regulating cut-off valve is installed.

[0016] Further, a thermocouple, a flow orifice plate I, a CO analyzer, a pressure transmitter, a flow electric regulating valve, a residual oxygen analyzer and a NOx analyzer are sequentially arranged on the empty flue gas pipeline to which the air burner is connected through the reversing valve.

[0017] Further, a flow orifice plate II and an electric butterfly valve are sequentially arranged on the return flue gas pipeline.

[0018] Further, the regenerative reheating furnace is an up-and-down mixed double regenerative reheating furnace. The regenerative reheating furnace is divided into burner regenerative boxes for up-and-down heating. In the upper heating burner regenerative box, the gas burner is at the lower part and the air burner is at the upper part. In the lower heating burner regenerative box, the gas burner is at the upper part and the air burner is at the lower part. A swirl pure oxygen nozzle is added between the burner regenerative boxes along the center line of the interface between the gas burner and the air burner in the burner regenerative box in the furnace length direction.

[0019] Further, the regenerative reheating furnace is a left-and-right mixed double regenerative reheating furnace. The gas burners and the air burners in the regenerative boxes on the furnace wall of the regenerative reheating furnace are in a left-and-right intersection angle form. The oxygen nozzle is a swirl pure oxygen nozzle and is arranged at the position between two regenerative boxes on the intersection center line of the gas burner and the air burner in the furnace length direction.

[0020] Further, the pure oxygen nozzle has circumferentially distributed swirl holes. The two swirl holes on the horizontal line are larger than the swirl holes in other directions. The oxygen supply load of the pure oxygen nozzle is customized according to the output of the reheating furnace.

[0021] Further, the heating method of the coupling system for all-oxygen combustion and zero-emission of empty flue gas in the blast furnace gas double regenerative reheating furnace specifically comprises the following steps:

[0022] S1. The pure oxygen pipeline is connected to the pure oxygen nozzles on both side walls of the regenerative heating furnace through a dedicated oxygen valve group. The gas pipeline and the coal smoke pipeline are respectively connected to the gas burners on both side walls of the regenerative heating furnace through a reversing valve. The smoke return pipeline and the empty smoke pipeline are respectively connected to the air burners on both side walls of the regenerative heating furnace through a reversing valve.

[0023] S2. Under the combustion condition on this side, the gas pipeline controlled by reversing supplies gas to the gas burner on this side of the regenerative heating furnace wall. The smoke return pipeline returns the empty smoke discharged from the air burner on the opposite side of the furnace to the air burner on this side of the regenerative heating furnace wall. At the same time, the pure oxygen pipeline supplies oxygen to the pure oxygen nozzle on this side. The gas, empty smoke and oxygen are mixed and burned to heat the billet.

[0024] S3. At the same time, the condition of the burners on the opposite side is that the oxygen quick cut valve for transporting oxygen in the pure oxygen pipeline on the opposite side is in the closed state, and the pure oxygen nozzle on the opposite side is not supplied with oxygen. A part of the high-temperature flue gas is discharged as coal smoke through the reversing valve and the coal smoke pipeline after being heat-exchanged by the regenerator in the gas burner on the opposite side of the furnace wall. The coal smoke is discharged into the atmosphere from the coal smoke chimney. Another part of the high-temperature flue gas is heat-exchanged by the regenerator in the air burner on the opposite side of the furnace wall and then connected to the empty smoke pipeline through the reversing valve to discharge the empty smoke. The empty smoke is sent into the smoke return pipeline through the empty smoke pipeline, returns to the furnace through the air burner on this side connected to the smoke return pipeline, and maintains the conveying state of the empty smoke to the air burner on this side all the time.

[0025] S4. In the next cycle, the burners on this side and the opposite side and the connected pipelines are reversed through the reversing valve. Under the combustion condition on the opposite side, the oxygen quick cut valve for transporting oxygen in the pure oxygen pipeline on this side is in the closed state, and the pure oxygen nozzle on this side is not supplied with oxygen. The gas pipeline controlled by reversing supplies gas to the gas burner on the opposite side of the regenerative heating furnace wall. The gas burner on this side is connected to the coal smoke pipeline to discharge coal smoke. The air burner on this side is connected to the empty smoke pipeline to discharge the empty smoke, which is sent back to the air burner on the opposite side for reheating and returning to the furnace through the empty smoke induced draft fan. At the same time, the pure oxygen pipeline supplies oxygen to the pure oxygen nozzle on the opposite side. The gas, empty smoke and oxygen are mixed and burned to heat the billet.

[0026] Further, the empty smoke returns to the furnace through the smoke return pipeline and is driven by the empty smoke induced draft fan, and the coal smoke is discharged by the coal smoke induced draft fan.

[0027] Further, regenerators are provided in the regenerative chambers on both side walls where the gas burners and air burners of the regenerative heating furnace are located. They absorb heat when the gas burners and air burners discharge the flue gas in the furnace, and heat the gas and empty smoke when reversing to supply gas and empty smoke.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1) Less input, more output. It is feasible to add pure oxygen nozzles to regenerative furnaces. The air pipeline and the empty flue pipeline are reorganized to form an empty flue pipeline and a return flue pipeline for flue gas recycling back to the furnace. The whole-oxygen return flue transformation system of the regenerative heating furnace has a small project volume, less investment, fast implementation, and good results.

[0030] 2) Since the flame of the whole-oxygen return flue high-temperature combustion technology in the regenerative heating furnace is not generated in the burner, but is formed after the gas and the empty flue are heated at high temperature in the regenerative chamber of the furnace wall and pure oxygen enters the furnace space and then begins to diffusely burn. The participation of pure oxygen in diffusion, disturbance, and entrainment is more conducive to combustion. Using whole-oxygen combustion reduces the participation of nitrogen, significantly reduces the flue gas volume, reduces the generation amount of NOx, and reduces pollutant emissions; the triatomic gas in the combustion products and the triatomic gas of the high-temperature empty flue returning to the furnace are superimposed to increase the flame radiation intensity and strengthen the radiation heat transfer; the participation of pure oxygen can significantly increase the combustion speed and promote complete combustion; it reduces the ignition temperature of the fuel and the burnout time, and greatly increases the heat release.

[0031] 3) The empty flue is reheated by the regenerator and returns to the furnace through the air burner, which not only maintains the flue gas fullness of the regenerative heating furnace but also can control the oxygen supply by the system to meet the combustion conditions of the oxygen-deficient empty flue and gas. At the same time, it also makes up for the shortcoming of the small flue gas volume of whole-oxygen combustion; the pure oxygen nozzle is inserted into the furnace wall between the regenerator boxes of the air burner and the gas burner. The high-pressure oxygen draws in the surrounding furnace gas and meets the simultaneously injected fuel together with the high-temperature return flue oxygen-deficient air flow to achieve combustion. The entrainment and disturbance gradient combustion of the swirling oxygen injection form a new type of flameless combustion that is completely different from the traditional flame, creating an excellent temperature field in the furnace, and greatly improving the furnace temperature uniformity.

[0032] 4) Whole-oxygen combustion replaces the combustion-supporting air, changes the air reversal to empty flue reversal, and all the empty flue is reheated and reversed back to the furnace after being discharged. The heat enthalpy of the empty flue is fully utilized, improving the heating efficiency, reducing flue gas emissions, and reducing pollution.

[0033] 5) Applying whole-oxygen combustion coupled with empty flue return flue circulation on the regenerative heating furnace, adopting a pure oxygen supply method, combining hierarchical pure oxygen injection technology with reversal and return flue closed-loop control, avoiding the risk of excessive combustion temperature caused by flue gas recirculation, ensuring the coordination and adjustability of the reversal cycle and whole-oxygen combustion, avoiding mutual interference, with precise combustion control, complete combustion, uniform distribution of combustion heat, high combustion efficiency, and good heating quality.

[0034] 6) According to the timely heat load demand of the furnace, the oxygen-fuel ratio, the residual oxygen content of air smoke and coal smoke, and the CO concentration monitoring parameters, the air-smoke switching cycle is shortened to 120-150 seconds, and the coal gas switching maintains the original cycle; according to the CO and NOx concentration analysis and sensor feedback, the oxygen-fuel ratio is dynamically adjusted, the pure oxygen content is adjusted in real time, and the automatic control and process control upgrade management achieves ultimate energy efficiency and ensures that ultra-low emission environmentally friendly products meet the standards. At the same time, the oxidation and burning rate will be greatly reduced, the yield rate will be improved, and significant economic and social benefits will be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the blast furnace gas double regenerative heating furnace full oxygen combustion air smoke zero emission coupling system described in the present invention.

[0036] Figure 2 It is a schematic diagram of the upper and lower mixed regenerative heating furnace burner structure combined with the pure oxygen nozzle arrangement according to the present invention.

[0037] Figure 3 It is a schematic diagram of the left-right mixed regenerative heating furnace burner structure combined with the pure oxygen nozzle arrangement described in the present invention.

[0038] Figure 4 It is a top view of the installation arrangement of the pure oxygen nozzle of the regenerative heating furnace described in the present invention.

[0039] In the figure: 1. pure oxygen nozzle; 2. air burner; 3. gas burner; 4. gas pipeline; 5. pure oxygen pipeline; 6. air smoke pipeline; 7. smoke return pipeline; 8. reversing valve; 9. pneumatic quick-cut valve; 10. NOx analyzer; 11. residual oxygen analyzer; 12. flow electric regulating valve; 13. pressure transmitter; 14. CO analyzer; 15. flow orifice plate 1; 16. thermocouple; 17. electric butterfly valve; 18. flow orifice plate 2; 19. electric regulating cut-off valve; 20. air smoke induced draft fan; 21. coal smoke fan; 22. regenerative heating furnace; 23. venting pipeline; 24. coal smoke pipeline; 25. combustion-supporting air pipeline; 26. oxygen special valve group; 27. steel billet; 28. air smoke chimney; 29. ​​coal smoke chimney; 30. combustion-supporting fan; 31. oxygen quick-cut valve. DETAILED DESCRIPTION

[0040] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0041] like Figures 1-4As shown in the figure, the working principle of a fully oxygen - combustion and zero - emission coupling system for the air - exhausted flue gas of a blast - furnace gas double regenerative reheating furnace: By installing a pure - oxygen nozzle 1 between the gas burner 3 and the air burner 2 set on both side walls of the regenerative reheating furnace 22, the pure oxygen in the pure - oxygen nozzle 1, the high - temperature air - exhausted flue gas returned to the furnace by the air burner 2, and the gas in the gas burner 3 are fully mixed by entrainment and diffusion on one side inside the regenerative reheating furnace 22, realizing the complete combustion of gas and pure oxygen; On the opposite side of combustion, the high - temperature flue gas inside the regenerative reheating furnace 22 is exhausted by the air burner 2. After heat exchange, the low - temperature air - exhausted flue gas passes through the reversing valve 8 and is transported to the return - flue gas pipeline 7 through the connected air - exhausted flue gas pipeline 6, then returns to the air burner 2 on the combustion side, continues to be heated, and then returns to the inside of the regenerative reheating furnace 22; The high - temperature and lean - oxygen air - exhausted flue gas returning to the furnace helps with low heat loss and low nitrogen; The entrainment and disturbance effects of the pure - oxygen nozzle 1 make the residual C in the furnace completely burned out and obtain excellent furnace - temperature uniformity.

[0042] On the opposite side of combustion, the high - temperature flue gas inside the regenerative reheating furnace 22 is exhausted by the gas burner 3. After heat exchange, the low - temperature coal - exhausted flue gas passes through the reversing valve 8 and is transported to the outside of the coal - exhausted flue gas chimney 29 through the connected coal - exhausted flue gas pipeline 24 by the coal - exhausted flue gas induced draft fan 21. To avoid gas leakage during the moment of reversing when the gas burner 3 supplies gas, the gas back - blowing system still operates according to the original execution program.

[0043] As Figures 1-4 As shown in the figure, a fully oxygen - combustion and zero - emission coupling system for the air - exhausted flue gas of a blast - furnace gas double regenerative reheating furnace includes a regenerative reheating furnace 22, a reversing valve 8, a gas burner 3, an air burner 2, a pure - oxygen nozzle 1, a gas pipeline 4, a coal - exhausted flue gas pipeline 24, an air - exhausted flue gas pipeline 6, a return - flue gas pipeline 7, and a pure - oxygen pipeline 5. The regenerative gas burners 3 and air burners 2 are set on both side walls of the regenerative reheating furnace 22. A pure - oxygen nozzle 1 is set between the gas burner 3 and the air burner 2. The gas burner 3 is reversely connected to the gas pipeline 4 and the coal - exhausted flue gas pipeline 24 through the reversing valve 8. The air burner 2 is reversely connected to the return - flue gas pipeline 7 and the air - exhausted flue gas pipeline 6 through the reversing valve 8; The pure - oxygen nozzle 1 is connected to the pure - oxygen pipeline 5; The air - exhausted flue gas pipeline 6 is respectively connected to the suction ports of the air - exhausted flue gas induced draft fan 20 and the combustion - supporting fan 30, and pneumatic quick - cut valves 9 are installed on both inlet pipelines connected to the air - exhausted flue gas induced draft fan 20 and the combustion - supporting fan 30; The outlet pipelines of the air - exhausted flue gas induced draft fan 20 and the combustion - supporting fan are both connected to the return - flue gas pipeline 7; A relief pipeline 23 is provided at the high point of the outlet pipeline of the air - exhausted flue gas induced draft fan 20 and an electric regulating cut - off valve 19 is installed.

[0044] Further, a thermocouple 16, a first flow orifice plate 15, a CO analyzer 14, a pressure transmitter 13, a flow electric regulating valve 12, a residual oxygen analyzer 11, and a NOx analyzer 10 are sequentially arranged on the empty flue gas pipeline 6 to which the air burner 2 is connected through a reversing valve 8. The return smoke volume of the empty flue gas pipeline 6 is determined according to the instantaneous heat load demand of the furnace, the oxygen-fuel ratio, the residual oxygen content and CO concentration of the empty flue gas and coal smoke, the nitrogen oxide monitoring parameters, etc. An electric regulating cut-off valve 19 can also be arranged through the blow-off pipeline 23 to discharge and regulate the empty flue gas volume.

[0045] Further, a second flow orifice plate 18 and an electric butterfly valve 17 are sequentially arranged on the return flue gas pipeline 7. The return flue gas pipeline 7 is connected to the air burner 2 on one side furnace wall through a reversing valve 8.

[0046] Further, the regenerative heating furnace 22 is an upper and lower hybrid double regenerative heating furnace. The regenerative heating furnace 22 is divided into burner regenerative boxes for upper and lower heating. The gas burner 3 in the upper heating burner regenerative box is at the lower part, and the air burner 2 is at the upper part. The gas burner 3 in the lower heating burner regenerative box is at the upper part, and the air burner 2 is at the lower part. A swirl pure oxygen nozzle 1 is added between the burner regenerative boxes whose center line of the interface between the gas burner 3 and the air burner 2 in the burner regenerative box is along the furnace length direction; the two swirl holes on the horizontal line of the pure oxygen nozzle 1 are larger than the swirl holes in other directions, and the oxygen supply load of the pure oxygen nozzle 1 is customized and matched according to different heating furnace outputs.

[0047] Further, the regenerative heating furnace 22 is a left and right hybrid double regenerative heating furnace. The gas burner 3 and the air burner 2 in the regenerative box on the furnace wall of the regenerative heating furnace 22 are in a left and right intersection angle form; the pure oxygen nozzle 1 is a swirl pure oxygen nozzle and is arranged at the position between two regenerative boxes on the intersection angle center line of the gas burner 3 and the air burner 2 in the furnace length direction.

[0048] Further, the two swirl holes on the horizontal line of the pure oxygen nozzle 1 are larger than the swirl holes in other directions, and the oxygen supply load of the pure oxygen nozzle 1 is customized and matched according to different heating furnace outputs.

[0049] Further, the heating method of the fully oxygen-fired and empty flue gas zero-emission coupling system of the blast furnace gas double regenerative heating furnace specifically includes the following steps:

[0050] S1. The pure oxygen pipeline 5 is connected to the pure oxygen nozzles 1 on both sides of the furnace wall of the regenerative heating furnace 22 through an oxygen special valve group 26. The gas pipeline 4 and the coal smoke pipeline 24 are respectively connected to the gas burners 3 on both sides of the furnace wall of the regenerative heating furnace 22 through a reversing valve 8. The return flue gas pipeline 7 and the empty flue gas pipeline 6 are respectively connected to the air burners 2 on both sides of the furnace wall of the regenerative heating furnace 22 through a reversing valve 8;

[0051] S2. When burning on this side, the operating condition of the burners on this side is that the gas pipeline 4 under commutation control supplies gas to the gas burner 3 on the furnace wall of the regenerative heating furnace 22. The return flue gas pipeline 7 supplies the return furnace empty flue gas from the exhausted outside air of the air burner 2 on the opposite side to the air burner 2 on the furnace wall of the regenerative heating furnace 22. At the same time, the pure oxygen pipeline 5 supplies oxygen to the pure oxygen nozzle 1 on this side. The gas, empty flue gas and oxygen are mixed and burned to heat the billet.

[0052] S3. At the same time, when burning on this side, the operating condition of the burners on the opposite side is that the oxygen quick cut valve 31 of the pure oxygen pipeline 5 is in the closed state, and the pure oxygen nozzle 1 on the opposite side is not supplied with oxygen. A part of the high-temperature flue gas is discharged through the coal smoke pipeline 24 by using the reversing valve 8 after heat exchange through the regenerator in the gas burner 3 on the furnace wall of the opposite side. The coal smoke is discharged into the atmosphere from the coal smoke chimney 29. Another part of the high-temperature flue gas is connected to the empty flue gas pipeline 6 through the reversing valve 8 after heat exchange through the regenerator in the air burner 2 on the furnace wall of the opposite side to discharge the empty flue gas. The empty flue gas is sent into the return flue gas pipeline 7 through the empty flue gas pipeline 6, and returns to the furnace through the air burner 2 on this side connected to the return flue gas pipeline 7, and keeps the delivery state of this empty flue gas to the air burner 2 on this side all the time.

[0053] S4. In the next cycle, the burners on this side and the opposite side and the connected pipelines are commutated by the reversing valve. Under the combustion condition on the opposite side, the oxygen quick cut valve 31 of the pure oxygen pipeline 5 on this side is in the closed state, and the pure oxygen nozzle 1 on this side is not supplied with oxygen. The gas pipeline 4 under commutation control supplies gas to the gas burner 3 on the opposite side of the furnace wall of the regenerative heating furnace 22. The gas burner 3 on this side is connected to the coal smoke pipeline 24 to discharge the coal smoke; the air burner 2 on this side is connected to the empty flue gas pipeline 6 to discharge the empty flue gas. The empty flue gas is sent back to the air burner 2 on the opposite side for reheating and returning to the furnace through the empty flue gas induced draft fan 20. At the same time, the pure oxygen pipeline 5 supplies oxygen to the pure oxygen nozzle 1 on the opposite side. The gas, empty flue gas and oxygen are mixed and burned to heat the billet.

[0054] Further, the empty flue gas returns to the furnace through the return flue gas pipeline 7 and is driven by the empty flue gas induced draft fan 20, and the coal smoke is discharged by the coal smoke fan 21.

[0055] Further, regenerators are provided in the regenerative chambers on both sides of the furnace wall where the gas burner 3 and the air burner 2 of the regenerative heating furnace 22 are located. When the furnace flue gas is exhausted outside the gas burner 3 and the air burner 2, the regenerators absorb heat, and when the gas and the empty flue gas are sent in after commutation, they reheat the gas and the empty flue gas.

[0056] As Figures 1-4 shown, the working principle of a coupling system for zero-emission of empty flue gas in the all-oxygen combustion of a blast furnace gas double regenerative heating furnace:

[0057] 1) The method of realizing the function conversion of the combustion-supporting fan 30 and the air-smoke induced draft fan 20 to serve as a backup for each other is to change the combustion-supporting air reversal to the air-smoke reversal. The original air-smoke induced draft fan 20 inlet air-smoke duct 6 is kept unchanged, and the air-smoke induced draft fan 20 outlet smoke pipe is changed from the original docking air-smoke chimney 28 to the original combustion-supporting air duct 25 and an electric butterfly valve 17 is installed. The original combustion-supporting air duct 25 is the smoke return duct 7; the air-smoke induced draft fan 20 inlet air-smoke duct 6 is installed with a pneumatic quick-cut valve 9, and the front part of the pneumatic quick-cut valve 9 is connected to a bypass air-smoke duct 6 and a pneumatic quick-cut valve 9 connected to the air intake of the combustion-supporting fan 30, and an electric butterfly valve 17 is installed on the outlet duct of the combustion-supporting fan 30; thus, a production condition of one working and one standby of the air-smoke induced draft fan 20 and the original combustion-supporting fan 30 is formed in the air-smoke return process; only when the air-smoke induced draft fan 20 is in an accident state, it is switched to the combustion-supporting fan 30 to start, while the air-smoke reversal is continued. This method achieves zero-emission process of air smoke during the entire life cycle of the regenerative furnace's pure oxygen combustion coupled with flue gas circulation by changing the pipeline optimization design and adding control logic. It makes minimal changes to the original regenerative heating furnace and reduces the cost of transformation. Only the air smoke is returned to the furnace, while the coal smoke is still discharged, maintaining the original gas reversing heat storage and coal smoke backblowing technology.

[0058] 2) The superiority of pure oxygen combustion combined with the high temperature and rarefied oxygen characteristics of regenerative combustion can achieve complementary advantages and obtain superimposed energy saving, carbon reduction and emission reduction effects. Pure oxygen combustion reduces the power consumption of the combustion-supporting fan 30, and pure oxygen replaces air to reduce 78% of N2 participation, thereby reducing the amount of flue gas. The air regenerative reversing channel is used to recycle the air and smoke for heat storage. It not only maintains the flue gas fullness of the regenerative furnace, but also controls the oxygen supply by timing to meet the combustion conditions of oxygen-poor air and gas. The entrainment and disturbance gradient combustion of the swirl oxygen jet form a new type of flameless combustion that is completely different from the traditional flame, creating a uniform distribution of the excellent temperature field in the furnace.

[0059] 3) The air smoke duct 6 connected to the air burner 2 via the reversing valve 8 is provided with a thermocouple 16, a flow orifice plate 15, a CO analyzer 14, a pressure transmitter 13, a flow electric regulating valve 12, a residual oxygen analyzer 11 and a NOx analyzer 10, etc. The automatic adjustment of the control system is mainly aimed at the state parameters of the air smoke monitored online. When the residual oxygen content, CO concentration, nitrogen oxides and other related parameters in the flue gas of the air smoke duct 6 measured deviate from the standard value, the return smoke volume of the air smoke duct 6 is adjusted and determined according to the instantaneous heat load demand of the furnace. Under the working condition that meets the oxygen-fuel ratio requirements, the smoke volume is adjusted by the electric regulating cut-off valve 19 of the venting duct 23 at the high point of the return smoke duct 7, and the flow orifice plate 2 18 of the return smoke duct 7 is used for accurate calibration.

[0060] 4) For the compact installation structure of the burner regenerator box of the existing regenerative furnace, a special oxygen lance outer protection structure is required to assist in the installation and strengthen the connection with the steel structure columns of the existing furnace body, including the outer protection structure with through holes in the pipeline of special structure, etc., which can ensure that the installation position and space of the oxygen lance are not affected.

[0061] 5) Heating method of the full-oxygen combustion and zero-emission coupling system of the blast furnace gas double regenerative heating furnace. Pure oxygen replaces the combustion-supporting air. In fact, oxygen and gas burn with a precise air-oxygen ratio, and all the empty flue gas is recycled back to the furnace through the combustion-supporting air pipeline using the commutation mechanism. The flue gas returning to the furnace is a triatomic gas with high temperature and low oxygen content, increasing the radiant heat in the furnace and further reducing oxidation and burning loss. The initial temperature of the empty flue gas before returning to the regenerator is more than 150 °C higher than the original combustion-supporting air, and it is also heated to 800 - 1000 °C when leaving the regenerator and then returns to the furnace. Compared with the existing blast furnace gas double regenerative heating furnace, it is basically not necessary to make major changes to the regenerative burner and commutation device. Only by recombining and connecting the existing empty flue gas pipeline and combustion-supporting air pipeline and implementing adjustments and controls such as valves and instruments can full-oxygen combustion and zero-emission of empty flue gas be achieved, which is more energy-saving, more efficient, and more environmentally friendly than the original double regenerative heating form. Through the full return of the empty flue gas of the regenerative heating furnace to the furnace and coupling with full-oxygen combustion, the production goals of energy conservation, emission reduction, pollution reduction, carbon reduction, and low burning loss of the furnace can be achieved.

[0062] As mentioned above, only the specific preferred embodiments of the present invention are described, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A fully oxygen - combustion and zero - emission coupling system for air - free flue gas in a double regenerative heating furnace using blast furnace gas, comprising a regenerative heating furnace, a reversing valve, a gas burner, an air burner, a pure oxygen nozzle, a gas pipeline, a coal - smoke pipeline, an air - free flue gas pipeline, a return flue gas pipeline, and a pure oxygen pipeline, characterized in that, On both side walls of the regenerative reheating furnace, regenerative gas burners and air burners are arranged. A pure oxygen nozzle is arranged between the gas burner and the air burner. The gas burner is connected to the gas pipeline and the soot pipeline respectively through a reversing valve. The air burner is connected to the return smoke pipeline and the empty smoke pipeline respectively through a reversing valve. The pure oxygen nozzle is connected to the pure oxygen pipeline. The empty smoke pipeline is respectively connected to the empty smoke induced draft fan and the air inlet of the combustion-supporting fan, and pneumatic quick cut valves are installed on both inlet pipelines connected to the fan. The outlet pipelines of the empty smoke induced draft fan and the combustion-supporting fan are both connected to the return smoke pipeline through electric shut-off valves. A relief pipeline is provided at the high point of the outlet pipeline of the empty smoke induced draft fan and an electric regulating cut-off valve is installed.

2. The full-oxygen combustion and zero-emission coupling system for the double regenerative heating furnace of blast furnace gas according to claim 1, wherein A thermocouple, a flow orifice plate I, a CO analyzer, a pressure transmitter, a flow electric regulating valve, a residual oxygen analyzer and a NOx analyzer are successively arranged on the empty smoke pipeline to which the air burner is connected through a reversing valve.

3. The full-oxygen combustion and zero-emission coupling system of the double regenerative heating furnace for blast furnace gas according to claim 1, characterized in that, A flow orifice plate II and an electric butterfly valve are successively arranged on the return smoke pipeline.

4. A fully oxygenated combustion and zero-emission coupling system for a double regenerative heating furnace using blast furnace gas according to claim 1, characterized in that, The regenerative reheating furnace is an upper and lower hybrid double regenerative reheating furnace. The regenerative reheating furnace is divided into burner regenerator boxes for upper and lower heating. In the upper heating burner regenerator box, the gas burner is at the lower part and the air burner is at the upper part. In the lower heating burner regenerator box, the gas burner is at the upper part and the air burner is at the lower part. A swirl pure oxygen nozzle is added between the burner regenerator boxes along the center line of the interface between the gas burner and the air burner in the burner regenerator box in the furnace length direction.

5. A fully oxygen-fired and zero-emission coupling system for the double regenerative heating furnace of blast furnace gas according to claim 1, characterized in that, The regenerative reheating furnace is a left and right hybrid double regenerative reheating furnace. The gas burner and the air burner in the regenerator box on the furnace wall of the regenerative reheating furnace are in a left and right intersection angle form. The oxygen nozzle is a swirl pure oxygen nozzle and is arranged at the position between two regenerator boxes on the intersection center line of the gas burner and the air burner in the furnace length direction.

6. A fully oxygen combustion and empty flue zero-emission coupling system for a blast furnace gas double regenerative heating furnace according to claim 1 or 4 or 5, characterized in that, The pure oxygen nozzle has a circumferentially distributed swirl hole. The two swirl holes on the horizontal line are larger than the swirl holes in other directions. The oxygen supply load of the pure oxygen nozzle is customized and matched according to the output of the reheating furnace.

7. The heating method of the fully oxygen-fired and empty flue zero-emission coupling system of a blast furnace gas double regenerative reheating furnace according to claim 1, characterized in that, The heating method of the all-oxygen combustion and empty smoke zero-emission coupling system of the blast furnace gas double regenerative reheating furnace specifically includes the following steps: S1. The pure oxygen pipeline is connected to the pure oxygen nozzles on both side walls of the regenerative reheating furnace through an oxygen special valve group. The gas pipeline and the soot pipeline are respectively connected to the gas burners on both side walls of the regenerative reheating furnace through a reversing valve. The return smoke pipeline and the empty smoke pipeline are respectively connected to the air burners on both side walls of the regenerative reheating furnace through a reversing valve. S2. Under the combustion condition on this side, the gas pipeline controlled by reversing supplies gas to the gas burner on this side of the furnace wall of the regenerative reheating furnace. The return smoke pipeline returns the empty smoke discharged from the air burner on the opposite side of the furnace to the air burner on this side of the furnace wall of the regenerative reheating furnace. At the same time, the pure oxygen pipeline supplies oxygen to the pure oxygen nozzle on this side. The gas, the empty smoke and the oxygen are mixed and burned to heat the steel billet. S3. Meanwhile, for the burner on the opposite side, the oxygen quick cut valve for oxygen transportation in the pure oxygen pipeline on the opposite side is in the closed state, and the pure oxygen nozzle on the opposite side is not supplied with oxygen. A part of the high-temperature flue gas exchanges heat through the regenerator in the gas burner on the opposite side of the furnace wall, and then the coal soot is discharged through the coal soot pipeline by using the reversing valve. The coal soot is discharged into the atmosphere from the coal soot chimney. Another part of the high-temperature flue gas exchanges heat through the regenerator in the air burner on the opposite side of the furnace wall, and then is connected to the empty flue gas pipeline through the reversing valve to discharge the empty flue gas. The empty flue gas is sent into the return flue gas pipeline through the empty flue gas pipeline, and returns to the furnace through the air burner on this side connected to the return flue gas pipeline, and the transportation state of the empty flue gas to the air burner on this side is maintained all the time; S4. In the next cycle, the burners on this side and the opposite side and the connected pipelines are reversed through the reversing valve. Under the combustion condition on the opposite side, the oxygen quick cut valve for oxygen transportation in the pure oxygen pipeline on this side is in the closed state, and the pure oxygen nozzle on this side is not supplied with oxygen. The gas pipeline controlled by the reversing valve supplies gas to the gas burner on the opposite side of the regenerative heating furnace wall. The gas burner on this side is connected to the coal soot pipeline to discharge the coal soot; the air burner on this side is connected to the empty flue gas pipeline to discharge the empty flue gas, and is sent back to the air burner on the opposite side for reheating and then back to the furnace through the empty flue gas induced draft fan. At the same time, the pure oxygen pipeline supplies oxygen to the pure oxygen nozzle on the opposite side, and the gas, empty flue gas and oxygen are mixed and burned to heat the billet.

8. The heating method of an all-oxygen combustion and empty flue zero-emission coupling system for a blast furnace gas double regenerative reheating furnace according to claim 7, characterized in that, The empty flue gas returns to the furnace through the return flue gas pipeline and is driven by the empty flue gas induced draft fan, and the coal soot is discharged by the coal soot induced draft fan.

9. The heating method of an all-oxygen combustion and zero-emission coupling system with air smoke in a double regenerative heating furnace for blast furnace gas according to claim 7, characterized in that, Regenerators are provided with regenerators in the two furnace walls where the gas burners and air burners of the regenerative heating furnace are located. When the furnace gas is discharged from the gas burners and air burners, the regenerators absorb heat, and when the gas and empty flue gas are sent in the reverse direction, they heat the gas and empty flue gas.

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