Circulation gas treatment system and method for total-oxygen top gas circulation blast furnace

Abstract

The invention discloses a circulating gas treatment system and method for a total-oxygen top gas circulating blast furnace, and belongs to the technical field of low-carbon ironmaking. The circulating gas treatment system comprises a blast furnace, an oxygen flow adjusting module is arranged at an oxygen inlet of the blast furnace, and the blast furnace is sequentially connected with a purification module, a circulating fan and a pressure swing adsorption module; the pressure swing adsorption module is used for separating desorbed gas from the circulating gas and outputting decarbonized circulating gas; the decarburized circulating gas of the pressure swing adsorption module is heated and input into the blast furnace; the desorbed gas serves as fuel of the heating module to be combusted, and formed flue gas is exhausted after being desulfurized; a branch of the exhaust adjusting module is arranged between the purification module and the circulating fan, and the exhaust adjusting module is connected with the analysis gas branch and an external pipeline. According to the invention, the combustion utilization and cooperative regulation of the desorption gas are realized, and the problems of high energy consumption, difficult utilization of the desorption gas and inflexible gas flow control of a circulating gas treatment system are solved.

Description

Technical Field

[0001] This invention relates to the field of low-carbon ironmaking technology, specifically to a circulating gas treatment system and method for a full oxygen top gas circulating blast furnace. Background Technology

[0002] Currently, traditional blast furnace ironmaking accounts for over 95% of global iron production, but it has high carbon emissions. Direct reduction iron technology, represented by hydrogen-based shaft furnaces, has low carbon emissions, but its energy consumption and raw material costs are high. Therefore, based on existing blast furnace facilities, implementing full oxygen blast furnace top gas recirculation, supplemented by carbon dioxide removal processes, is undoubtedly the best choice to reduce carbon emissions while avoiding the massive waste caused by eliminating a large number of existing blast furnace facilities.

[0003] Removing carbon dioxide from the circulating gas is a crucial step, currently employing wet decarbonization and pressure swing adsorption (PSA) processes. For wet decarbonization processes (such as low-temperature methanol and amine absorption), absorbent regeneration requires significant steam or electrical energy, accounting for over 60% of operating costs. Furthermore, these systems are suitable for high-purity applications and are costly for all-oxygen blast furnace scenarios. As for PSA processes, the following issues exist in practical applications: First, the desorbed gas obtained by pressure swing adsorption of circulating gas is a mixture of carbon dioxide and carbon monoxide, which is complex and difficult to use directly. If it is further separated, purified and reused, the energy consumption and cost will increase significantly. In order to pursue a high decarbonization rate of carbon dioxide in circulating gas, a large amount of carbon monoxide is often lost with the desorbed gas, resulting in energy waste and environmental pollution.

[0004] Secondly, the desorbed gas often contains organic sulfur impurities such as carbonyl sulfur, which are difficult to remove during the adsorption process. If the desorbed gas is used for chemical synthesis, it will bring subsequent processing problems. In addition, the pressure and circulating gas flow rate of the all-oxygen blast furnace system need to be actively and flexibly controlled, but the existing technology lacks mature and reliable control schemes, making it difficult to adapt to the changing load requirements during blast furnace operation and affecting the stable operation of the system. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a circulating gas treatment system and method for a full oxygen top gas circulating blast furnace, which realizes the combustion utilization and coordinated control of desorbed gas, and solves the problems of high energy consumption, difficulty in utilizing desorbed gas, and inflexible gas flow control in the current circulating gas treatment system.

[0006] The technical solution of the present invention is as follows: In a first aspect of the invention, a circulating gas treatment system for a full oxygen top gas circulating blast furnace is provided, comprising a blast furnace, wherein an oxygen flow regulating module is provided at the oxygen inlet of the blast furnace, and a purification module, a circulating fan and a pressure swing adsorption module are sequentially connected to the circulating gas outlet of the blast furnace, wherein the pressure swing adsorption module is used to separate desorbed gas from the circulating gas and output decarbonized circulating gas. It also includes a circulating gas heating module, which receives the decarbonized circulating gas, heats it, and inputs it into the blast furnace; the desorbed gas is input into the circulating gas heating module for combustion, and the resulting flue gas is discharged after desulfurization. A branch of the exhaust gas regulating module is provided between the purification module and the circulating fan. The exhaust gas regulating module is connected to the desorption gas branch and the external pipeline network. In some embodiments of the present invention, the circulating fan is configured as a compressor with a flow regulating mechanism, the flow regulating mechanism including at least one of a moving and stationary blade adjusting structure, a frequency converter, or a return pipeline. In some embodiments of the present invention, the exhaust gas regulation module includes a pressure reducing valve group or a residual pressure energy recovery unit, and the exhaust gas regulation module is interlocked with the furnace top pressure detection module installed on the blast furnace. In some embodiments of the present invention, the circulating gas heating module is equipped with a combustion-supporting gas supply pipeline, which is used to supply air, oxygen-enriched gas or pure oxygen, in conjunction with the desorbed gas for combustion.

[0007] In some embodiments of the present invention, a flue gas desulfurization module is also included, which is connected to the flue gas outlet of the circulating gas heating module. In some embodiments of the present invention, a supplementary gas access pipeline is also included, which is connected to the pipeline between the decarbonization circulating gas outlet of the pressure swing adsorption module and the circulating gas channel inlet of the circulating gas heating module, for supplementing fuel gas or reducing gas. In a second aspect of the invention, a method for treating circulating gas in a fully oxygen-top gas circulating blast furnace is provided, employing the above-described treatment system, comprising: The circulating gas from the blast furnace is purified by removing dust and acidic impurities. The purified circulating gas is pressurized. Desorbed gas is separated from the pressurized recycle gas by pressure swing adsorption to obtain decarbonized recycle gas, wherein the desorbed gas contains a mixture of carbon monoxide and carbon dioxide. In the circulating gas heating module, the desorbed gas is burned to heat the decarbonized circulating gas, and the flue gas generated by the combustion of the desorbed gas is discharged after desulfurization. The heated decarburized recycle gas is returned to the blast furnace; By adjusting the oxygen flow rate blown into the blast furnace, the amount of gas generated in the blast furnace and the heat balance inside the furnace are controlled. A portion of the gas is extracted from the circulating gas to form an exhaust system, and the furnace top pressure is controlled by adjusting the flow rate of the exhaust gas.

[0008] In some embodiments of the present invention, the flow rate of the circulating air in the system is controlled by adjusting the operating parameters of the circulating fan. In some embodiments of the present invention, the desorbed gas is combusted using pure oxygen or oxygen-enriched gas. In some embodiments of the present invention, fuel gas or reducing gas is added to the circulating gas pipeline, the fuel gas or reducing gas being used to achieve pressure control of the gas in the pipeline; when the system is started, the circulating gas volume in the pipeline is brought to a balance by adding fuel gas or reducing gas, thereby quickly starting the system. One or more technical solutions of the present invention have the following beneficial effects: By directly introducing the desorbed gas generated by the pressure swing adsorption module into the heating module as fuel, the energy consumption of deep separation of carbon monoxide and carbon dioxide in the desorbed gas is avoided, realizing the closed-loop utilization of energy. The heat generated by the combustion of the desorbed gas is directly used to heat the recirculated gas after decarburization, thereby significantly reducing the overall energy consumption and operating cost of the system while ensuring the thermal balance required by the blast furnace.

[0009] By utilizing the combustion process to convert organic sulfur impurities such as carbonyl sulfur in the desorbed gas into sulfur dioxide, which is then efficiently removed by the flue gas desulfurization module, this treatment path converts complex organic sulfur into sulfur oxides that are easy to process using mature technologies. This solves the problems of impurity enrichment and subsequent utilization, and ensures that the system emissions meet environmental protection requirements.

[0010] By implementing coordinated control through an oxygen flow regulation module and an exhaust gas regulation module, the oxygen flow is adjusted to control the amount of blast furnace gas generated, while the exhaust gas regulation module regulates system pressure and discharges inert gas to prevent accumulation. This achieves proactive, flexible, and reliable control over key system operating parameters. The flow regulation mechanism equipped in the circulating fan further ensures the adjustability of the circulating airflow. This multi-pronged coordinated control strategy enables the system to flexibly adapt to changes in blast furnace load, ensuring the long-term stable operation of the all-oxygen blast furnace.

[0011] In addition, the design of the supplementary gas inlet pipeline enhances the system's adaptability to various gas sources, and the option for the heating module to support oxygen-enriched or pure oxygen combustion creates conditions for obtaining high-concentration carbon dioxide flue gas, which is convenient for subsequent use. Attached Figure Description

[0012] Figure 1This is a schematic diagram of the operating principle of a circulating gas treatment system for a fully oxygen-top gas circulating blast furnace, provided in Embodiment 1 of the present invention. Detailed Implementation The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Example 1 In a typical embodiment of the present invention, such as Figure 1 As shown, a circulating gas treatment system for a blast furnace with full oxygen top gas circulation is proposed, including a blast furnace. An oxygen flow regulation module is provided at the oxygen inlet of the blast furnace. The circulating gas outlet of the blast furnace is connected in sequence to a purification module, a circulating fan and a pressure swing adsorption module. The pressure swing adsorption module is used to separate the desorbed gas from the circulating gas and output decarbonized circulating gas. It also includes a circulating gas heating module, which receives decarbonized circulating gas, heats it, and inputs it into the blast furnace; the desorbed gas is input into the circulating gas heating module for combustion, and the resulting flue gas is discharged after desulfurization; A branch of the exhaust gas regulating module is provided between the purification module and the circulating fan. The exhaust gas regulating module is connected to the desorption gas branch and the external pipeline. In this embodiment, the blast furnace serves as a reducing reaction vessel for ironmaking; The purification module is used for dust removal and acid removal of circulating coal gas. In this embodiment, the purification module uses dry bag filter or wet filter to remove dust particles from the coal gas, mainly mineral powder, coke powder, etc., and removes strong acid impurities through alkaline neutralization reaction. The circulating fan is used to pressurize the circulating air and control its flow rate; The pressure swing adsorption (PSA) module is used to separate desorbed gas from the circulating gas. The desorbed gas is mainly a mixture of carbon dioxide and carbon monoxide. The ratio of carbon monoxide to carbon monoxide in the mixture can be controlled through the design of the PSA module to achieve a usable calorific value for fuel. In this embodiment, the carbon monoxide content in the desorbed gas is between 10% and 30%. The calorific value varies depending on the carbon monoxide content, whether PSA or VPSA is used. With PSA, the carbon monoxide content is higher, generally adjustable between 25% and 30%, and it is directly used for heating the circulating gas. With VPSA, the carbon monoxide content is generally below 20%, resulting in a lower calorific value, requiring co-firing with exhaust gas or external supplemental fuel. In this embodiment, the PSA process is selected. The preferred flow rate of the desorbed gas is approximately 30-40% of the total circulating gas volume. The preferred carbon dioxide content in the desorbed gas is approximately 70%, and the preferred carbon monoxide content is approximately 30%, with a calorific value of approximately 4 MJ / cubic meter, which meets the fuel calorific value requirements of the circulating gas heating system. If full oxygen combustion is used at this time, it can be ensured that the flue gas formed after the desorbed gas is mainly carbon dioxide, which is convenient for subsequent use and no longer requires additional energy consumption such as wet decarbonization. The remainder can be discharged and utilized.

[0014] The decarbonized circulating gas after adsorption and decarbonization by the pressure swing adsorption system is heated and then enters the blast furnace. The oxygen flow regulation module is used to control the amount of oxygen entering the blast furnace, thereby controlling the blast furnace production intensity and gas generation, and thus controllably increasing the system pressure. The exhaust and ventilation control module is used to remove inert gases and impurities from the circulating gas and control the furnace top pressure.

[0015] By sequentially processing the blast furnace's circulating gas through a purification module, a circulating fan, a pressure swing adsorption (PSA) module, and a heating module before returning it to the blast furnace, a complete gas circulation loop is constructed. The desorbed gas produced by the PSA module is directly used as fuel for the heating module to heat the decarbonized circulating gas after decarburization. Simultaneously, an oxygen flow regulation module is installed to control the blast furnace's gas production, and a branch of the exhaust gas regulation module controls the system pressure and discharges inert gases. This achieves effective removal of carbon dioxide from the circulating gas and utilizes the carbon monoxide-rich desorbed gas as fuel on-site, avoiding the high energy consumption and cost associated with complex separation and purification processes or the direct emission causing air pollution. Furthermore, the synergistic effect of oxygen flow regulation and exhaust gas regulation provides a reliable and flexible control method for the pressure and flow of the all-oxygen blast furnace circulating gas system, solving the problem of inflexible gas flow control in circulating gas treatment systems and difficulty in adapting to changes in gas pressure and load, thus ensuring the stable and smooth operation of the blast furnace.

[0016] The circulating fan is configured as a compressor with a flow regulation mechanism, which includes at least one of the following: a moving and stationary blade adjustment structure, a frequency converter, or a return pipeline. This configuration provides multiple feasible and efficient methods for regulating the circulating gas flow rate. Adjusting the moving and stationary blades, frequency conversion regulation, or setting up a return pipeline can all achieve precise, continuous, and rapid adjustment of the output gas volume of the circulating fan. This allows for flexible response to changes in blast furnace operating conditions, ensuring that the circulating gas flow rate matches the blast furnace production requirements, and further enhancing the stability and controllability of the entire system.

[0017] The exhaust gas regulation module includes a pressure reducing valve group or a residual pressure energy recovery unit, and the exhaust gas regulation module is interlocked with the furnace top pressure detection module installed on the blast furnace. First, the pressure-reducing valve assembly enables direct and reliable control of exhaust flow and system pressure, offering a simple structure and rapid response. Second, the use of a residual pressure energy recovery unit, such as a furnace top residual pressure power generation unit, allows for the conversion of the pressure energy of the high-pressure circulating gas into electrical energy for reuse while controlling the pressure, significantly improving the overall system's energy efficiency and reducing operating energy consumption. Interlocking with the furnace top pressure achieves automatic closed-loop pressure control, ensuring the furnace top pressure remains stable within the set range and enhancing the system's automation level and safety reliability. In this embodiment, the exhaust adjustment module controls the system pressure to be adjustable from 0.15 to 0.3 MPa.

[0018] Understandably, nitrogen is the main inert gas in the system. During pressure swing adsorption (PSA), it primarily enters the circulating gas, with only a small amount entering the desorbed gas, leading to enrichment in the circulating gas. Therefore, a portion of the circulating gas must be extracted from the system to address this issue. The extraction rate is optimized based on oxygen purity and the impurity content in the raw materials to avoid pressure fluctuations caused by changes in gas production due to adjustments in oxygen supply. Simultaneously, ensuring a certain extraction rate, and using this to control the furnace top pressure, simplifies furnace top pressure control. Combined with the oxygen flow regulation module, controlling the amount of oxygen entering the blast furnace allows for control of blast furnace production intensity and gas production, thereby ensuring sufficient circulating gas volume and controllable influence on gas composition. Pressure adjustment via extraction and gas production adjustment via oxygen supply can be independent, avoiding mutual interference.

[0019] The circulating gas heating module is equipped with a combustion-supporting gas supply pipeline, which is used to supply air, oxygen-enriched gas or pure oxygen, in conjunction with the desorbed gas for combustion.

[0020] This configuration provides options for different combustion methods to suit various operating conditions and product requirements. When air-assisted combustion is used, the system configuration is simple. When oxygen-enriched or pure oxygen-assisted combustion is used, the combustion temperature can be increased, heat transfer can be enhanced, and the flue gas produced by combustion mainly consists of carbon dioxide and water. The concentration of carbon dioxide in the flue gas is significantly increased. In particular, when pure oxygen combustion is used, high-purity carbon dioxide flue gas can be obtained, which greatly facilitates the subsequent direct capture, utilization, or storage of flue gas, providing convenient conditions for achieving carbon emission reduction targets.

[0021] It also includes a flue gas desulfurization module, which is connected to the flue gas outlet of the circulating gas heating module. This design solves the environmental pollution problem caused by sulfur impurities (such as carbonyl sulfide) that may be present in the desorbed gas fuel. Through combustion, these complex organic sulfur impurities are converted into easily treatable sulfur oxides such as sulfur dioxide. The flue gas desulfurization module can efficiently remove sulfur dioxide from the flue gas, ensuring that the final emission or prepared flue gas meets environmental protection requirements. It also avoids the corrosion and pollution of subsequent carbon dioxide utilization equipment by sulfides, ensuring the clean and environmentally friendly operation of the entire system.

[0022] It also includes a supplementary gas inlet pipeline, which connects to the pipeline between the decarbonization circulating gas outlet of the pressure swing adsorption module and the circulating gas heating module, and is used to supplement fuel gas or reducing gas. The supplementary gas can also be connected before the purification module, the compression module, or the decarbonization module. The specific connection location is adaptively optimized according to whether the supplementary gas needs purification, decarbonization, and pressurization under actual operating conditions.

[0023] When the inert gas content in the circulating gas is high and the exhaust volume needs to be increased, the amount of desorbed gas needs to be controlled. In this case, decarbonization is carried out using processes such as VPSA. The carbon monoxide content in the desorbed gas is low and the calorific value does not meet the requirements of the heating module. The fuel for the heating module needs to be supplemented. The preferred fuel components are hydrogen, carbon monoxide, or hydrocarbons to ensure that the flue gas composition is sufficiently pure carbon dioxide or only adds some moisture under pure oxygen combustion conditions.

[0024] This configuration significantly enhances the operational flexibility and raw material adaptability of the entire system. When the calorific value of the desorbed gas is insufficient to meet heating requirements, or when the reducing composition of the circulating gas needs to be adjusted, external gas sources such as coke oven gas, hydrogen, natural gas, or syngas can be supplied through this supplementary gas connection to the pipeline. This allows the system to comprehensively utilize various by-product fuels or green hydrogen energy, ensuring not only the stable operation of the heating system and the optimization of the circulating gas composition, but also providing the possibility for further reducing fossil energy consumption and carbon emissions, improving the system's environmental friendliness, and reducing operating costs.

[0025] In this embodiment, combustion is used to convert carbon monoxide into carbon dioxide and avoid the energy consumption of separation, thus avoiding the energy consumption of wet regeneration (currently, the energy consumption level is about 2.5 GJ / tCO2); the pressure swing adsorption module is set after the circulating fan, with an operating pressure of 0.5-0.6 MPa, and the pressure after decarbonization is about 0.45-0.55 MPa, which meets the requirements of blast furnace air intake.

[0026] In other embodiments of the present invention, the supplementary gas, such as converter gas containing carbon dioxide, should be supplied before the pressure swing adsorption module and selected to be supplied before or after the compressor depending on the gas source pressure.

[0027] In a second aspect of the invention, a method for treating circulating gas in a fully oxygen-top gas circulating blast furnace is provided, employing the above-described treatment system, comprising: The circulating gas from the blast furnace is purified by removing dust and acidic impurities. The purified circulating gas is pressurized. Desorbed gas is separated from the pressurized recycle gas by pressure swing adsorption to obtain decarbonized recycle gas containing a mixture of carbon monoxide and carbon dioxide. In the circulating gas heating module, the combusted desorbed gas is used to heat the decarbonized circulating gas, and the flue gas generated by the combustion of the desorbed gas is discharged or recycled after desulfurization. The heated decarburized recycle gas is returned to the blast furnace; By adjusting the oxygen flow rate blown into the blast furnace, the amount of gas generated in the blast furnace and the heat balance inside the furnace can be controlled. A portion of the gas is extracted from the circulating gas to form an exhaust system, and the furnace top pressure is controlled by adjusting the exhaust flow rate.

[0028] This setup organically combines the fuel utilization of the desorbed gas with the active control of the system into a whole process flow, achieving low-energy removal and resource utilization of carbon dioxide in the circulating gas.

[0029] Instead of completely separating, purifying, and reusing carbon monoxide and carbon dioxide separately, only coarse separation of carbon dioxide is performed to ensure that the circulating gas meets the usage requirements. The mixture of carbon monoxide and carbon dioxide in the desorbed gas is directly burned to produce carbon dioxide. In particular, if pure oxygen is used in the combustion process, carbon dioxide products with the required purity can be obtained directly, thereby saving the extra energy consumption of wet decarbonization absorbent. At the same time, because the desorbed gas is utilized by combustion, the sulfur in the desorbed gas will exist in the final form of sulfur dioxide. The removal process is mature and inexpensive.

[0030] By controlling the oxygen content in the blast furnace to control the reaction rate and the amount of blast furnace gas produced, the system pressure can be indirectly controlled. The system pressure can also be directly controlled by controlling the exhaust gas volume, which is simple and easy to implement. The system pressure can be indirectly affected by controlling the amount of supplementary fuel gas or reducing gas, and the composition of the circulating gas can be flexibly adjusted. Through the above measures, the circulation volume of the circulating gas and the system pressure are controllable, and the control methods are flexible and effective.

[0031] The flow rate of circulating gas in the system is controlled by adjusting the operating parameters of the circulating fan. By adjusting parameters such as the moving and stationary blade angles, motor frequency, or return flow rate of the circulating fan, the circulation rate of the circulating gas in the system can be directly and effectively changed, thereby actively matching the smelting intensity of the blast furnace and maintaining a reasonable gas-solid ratio and reducing atmosphere. This is a key operation to ensure the smooth progress of the reaction in the blast furnace and the thermal balance of the system.

[0032] The desorbed gas is combusted using pure oxygen or oxygen-enriched gas. Using pure oxygen or oxygen-enriched combustion produces a high-temperature flame and combustion flue gas primarily composed of carbon dioxide, improving the combustion efficiency of the desorbed gas and the thermal efficiency of the heating module. It also creates conditions for producing high-concentration carbon dioxide that is easily processed, thus enhancing the overall low-carbon emission reduction effect of the process. It also includes supplementing the circulating gas pipeline with fuel gas or reducing gas to achieve pressure control of the gas in the pipeline; during system startup, the external supplementation of fuel gas or reducing gas brings the circulating gas volume in the pipeline to a balance, thereby quickly starting the system. When the system starts up, the load changes, or process parameters need to be adjusted, supplementing with external gas can quickly stabilize the system pressure, compensate for the calorific value, or enhance the reducing capacity of the circulating gas.

[0033] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A circulating gas treatment system for a blast furnace with full oxygen top gas circulation, characterized in that, The system includes a blast furnace, wherein an oxygen flow regulation module is provided at the oxygen inlet of the blast furnace, and a purification module, a circulating fan and a pressure swing adsorption module are connected in sequence at the circulating gas outlet of the blast furnace. The pressure swing adsorption module is used to separate the desorbed gas from the circulating gas and output decarbonized circulating gas. It also includes a circulating gas heating module, which receives the decarbonized circulating gas, heats it, and inputs it into the blast furnace; the desorbed gas is input into the circulating gas heating module for combustion, and the resulting flue gas is discharged after desulfurization. A branch of the exhaust gas regulating module is provided between the purification module and the circulating fan. The exhaust gas regulating module is connected to the desorption gas branch and the external pipeline network.

2. The circulating gas treatment system for a full oxygen top gas circulating blast furnace as described in claim 1, characterized in that, The circulating fan is configured as a compressor with a flow regulation mechanism, which includes at least one of a moving and stationary blade adjustment structure, a frequency converter, or a return pipeline.

3. The circulating gas treatment system for a full oxygen top gas circulating blast furnace as described in claim 1, characterized in that, The exhaust gas regulation module includes a pressure reducing valve group or a residual pressure energy recovery unit, and the exhaust gas regulation module is interlocked with the furnace top pressure detection module installed on the blast furnace.

4. A circulating gas treatment system for a full oxygen top gas circulating blast furnace as described in claim 1, characterized in that, The circulating gas heating module is equipped with a combustion-supporting gas supply pipeline, which is used to supply air, oxygen-enriched gas or pure oxygen to cooperate with the desorbed gas for combustion.

5. A circulating gas treatment system for a blast furnace with full oxygen top gas circulation as described in claim 1, characterized in that, It also includes a flue gas desulfurization module, which is connected to the flue gas outlet of the circulating gas heating module.

6. A circulating gas treatment system for a blast furnace with full oxygen top gas circulation as described in claim 1, characterized in that, It also includes a supplementary gas inlet pipeline, which is connected to the pipeline between the decarbonization circulating gas outlet of the pressure swing adsorption module and the circulating gas channel inlet of the circulating gas heating module, for supplementing fuel gas or reducing gas.

7. A method for treating circulating gas in a blast furnace with full oxygen top gas circulation, employing the circulating gas treatment system as described in any one of claims 1-6, characterized in that, include: The circulating gas from the blast furnace is purified by removing dust and acidic impurities. The purified circulating gas is pressurized. Desorbed gas is separated from the pressurized recycle gas by pressure swing adsorption to obtain decarbonized recycle gas, wherein the desorbed gas contains a mixture of carbon monoxide and carbon dioxide. In the circulating gas heating module, the desorbed gas is burned to heat the decarbonized circulating gas, and the flue gas generated by the combustion of the desorbed gas is discharged after desulfurization. The heated decarburized recycle gas is returned to the blast furnace; By adjusting the oxygen flow rate blown into the blast furnace, the amount of gas generated in the blast furnace and the heat balance inside the furnace are controlled. A portion of the gas is extracted from the circulating gas to form an exhaust system, and the furnace top pressure is controlled by adjusting the flow rate of the exhaust gas.

8. The circulating gas treatment method as described in claim 6, characterized in that, The flow rate of circulating air in the system is controlled by adjusting the operating parameters of the circulating fan.

9. The circulating gas treatment method as described in claim 6, characterized in that, The desorbed gas is burned using pure oxygen or oxygen-enriched gas.

10. The circulating gas treatment method as described in claim 6, characterized in that, It also includes replenishing the circulating gas pipeline with fuel gas or reducing gas, which is used to achieve pressure control of the gas in the pipeline; when the system is started, the amount of circulating gas in the pipeline is brought to a balance by replenishing the fuel gas or reducing gas, thereby quickly starting the system.

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