System for efficiently utilizing iron-making energy based on B-MIF smelting reduction

Abstract

The utility model discloses a system for efficiently utilizing iron-making energy based on B-MIF smelting reduction, belongs to the technical field of iron-making, and aims to solve the problems of low utilization rate of coal gas and heat energy and higher carbon emission in the conventional B-MIF process. The system for efficiently utilizing the smelting reduction ironmaking energy based on B-MIF comprises a smelting reduction furnace (12), a CO2 fixing furnace (19), a CO2 gasification furnace (20), a coal gas storage tank (21), a pulverized coal bunker (24) and a CO2 conversion furnace (25). The system based on efficient utilization of the B-MIF smelting reduction ironmaking energy can utilize waste heat of the system to achieve gas purification and decarbonization treatment, cyclic utilization of carbon is achieved, and then the technological smelting and energy utilization efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of ironmaking technology, specifically a system for efficient energy utilization in B-MIF molten reduction ironmaking. Background Technology

[0002] Steel production is mainly based on the blast furnace-converter model, with coke as the primary energy source. In recent years, coke-free non-blast furnace smelting reduction ironmaking technology has developed rapidly. It uses non-coking coal as the main energy source, greatly improving environmental protection levels and eliminating the need for hot briquetting processes such as sintering and pelletizing, thus breaking the "long process" limitation of traditional ironmaking technology.

[0003] With continuous innovation in smelting reduction processes, the B-MIF (Biomass-based smelting furnace) process has been proposed and gradually developed. However, many key technical challenges remain to be solved in terms of smelting efficiency, comprehensive utilization of gas and waste heat, preventing its industrial application. The B-MIF process uses a combination of hot and cold blast, with cold blast inlets at the top of the softening zone. The secondary combustion of CO in the rising gas stream provides additional energy to the furnace, improving thermal efficiency. Therefore, its gas temperature is relatively high (500℃~750℃) and its CO2 content is high. However, the current process of direct venting results in heat waste and increased carbon emissions. The high furnace temperature makes the slag rich in sensible heat resources (1400℃~1550℃), but the current water-flushing slag process results in low heat utilization. Furthermore, this process is a one-stage reduction, with direct reduction of the furnace charge and low indirect reduction, leading to reduced smelting efficiency. Utility Model Content

[0004] To address the issues of low utilization rate of gas and heat energy and high carbon emissions in the existing B-MIF process, this invention provides a system for efficient energy utilization in B-MIF molten reduction ironmaking. This system can utilize its own waste heat to purify and decarbonize the gas and achieve carbon recycling, thereby improving the efficiency of the smelting process and energy utilization.

[0005] The technical solution adopted by this utility model embodiment to solve its technical problem is:

[0006] A system for efficient energy utilization in B-MIF molten reduction ironmaking includes a molten reduction furnace, a fixed CO2 furnace, a CO2 gasifier, a gas storage tank, a pulverized coal silo, and a CO2 converter. Gas and air can be mixed and combusted exothermically in the molten reduction furnace, and the top gas produced in the molten reduction furnace can enter the fixed CO2 furnace. In the fixed CO2 furnace, CO2 and CaO in the top gas can react to produce CaCO3. The fixed CO2 furnace removes CO2 from the top gas. The fixed CO2 furnace and the CO2 gasifier are connected, and the CaCO3 produced in the fixed CO2 furnace can enter the CO2 gasifier. The CO2-removed top gas can be stored in the gas storage tank. The gas storage tank is connected to the melting reduction furnace and the CO2 gasification furnace. The gas in the gas storage tank can enter the melting reduction furnace and the CO2 gasification furnace. In the CO2 gasification furnace, O2 and CO can mix and burn to release heat and decompose CaCO3 into CO2 and CaO. The CO2 produced in the CO2 gasification furnace can enter the pulverized coal silo. The CO2 can transport the pulverized coal in the pulverized coal silo to the CO2 converter. The melting reduction furnace is connected to the CO2 converter through the slag trough. The slag discharged from the melting reduction furnace can enter the CO2 converter through the slag trough to release heat. In the CO2 converter, CO2 and pulverized coal can react with the heat released by the slag to generate CO. The gas produced in the CO2 converter can enter the gas storage tank.

[0007] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes a hot blast stove. The molten reduction stove has a tuyer and a cold air inlet. The tuyer is located in the middle of the molten reduction stove. The hot air provided by the hot blast stove can be injected into the molten reduction stove through the tuyer. The gas in the gas storage tank can also be injected into the molten reduction stove through the tuyer. The cold air inlet is located at the top of the molten reduction stove, and air can enter the molten reduction stove through the cold air inlet.

[0008] The molten reduction furnace is connected to the inlet of the CO2 fixed furnace through the flue gas outlet pipe at the top of the furnace. The inlet of the CO2 fixed furnace is located at the bottom of the CO2 fixed furnace. The gas discharged from the top of the molten reduction furnace can move upward in the CO2 fixed furnace. CaO powder can be sprayed downward from the top of the CO2 fixed furnace. The gas discharged from the top of the CO2 fixed furnace can enter the gas storage tank after being removed by the dust collector.

[0009] The system for efficient energy utilization in ironmaking based on B-MIF molten reduction includes multiple molten reduction furnaces connected in series. A first outlet pipe and a second outlet pipe are connected between the CO2 stationary furnace and the CO2 gasification furnace. CaCO3 produced in the CO2 stationary furnace can enter the CO2 gasification furnace through the first outlet pipe, and CaO produced in the CO2 gasification furnace can enter the CO2 stationary furnace through the second outlet pipe.

[0010] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes an oxygen tank. A combustion nozzle is installed on the upper part of the CO2 gasifier. A gas storage tank is connected to the combustion nozzle of the CO2 gasifier through a first gas delivery pipeline. The gas in the gas storage tank can supply the combustion nozzle of the CO2 gasifier. The oxygen tank can provide O2 to the combustion nozzle of the CO2 gasifier. A gas analyzer is installed on the first gas delivery pipeline. The gas analyzer can detect the CO content. The amount of O2 provided by the oxygen tank can be adjusted. The CO2 gasifier contains a thermocouple.

[0011] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes a CO2 storage tank. The CO2 gas discharged from the CO2 gasifier can enter the CO2 storage tank after being dusted by a dust collector. The CO2 gas discharged from the CO2 storage tank can enter the pulverized coal silo after being pressurized by a gas compressor. The CO2 converter is connected to a mixing lance. The pulverized coal in the pulverized coal silo and the pressurized CO2 gas can enter the CO2 converter from the mixing lance. The connection between the slag trough and the CO2 converter is located above the mixing lance. The liquid slag discharged from the slag trough can come into contact with the pulverized coal and CO2 mixture sprayed from the mixing lance.

[0012] The system for efficient utilization of energy in B-MIF molten reduction ironmaking also includes a slag pool and a waste heat power generation device. A slag crusher is installed at the bottom of the CO2 converter. The slag in the CO2 converter can be crushed by the slag crusher and then enter the slag pool. The CO2 converter, dust collector, waste heat power generation device, gas compressor and gas storage tank are connected in sequence. The gas generated in the CO2 converter can be dusted by the dust collector, have its heat recovered by the waste heat power generation device and be pressurized by the gas compressor before entering the gas storage tank.

[0013] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes a pre-reduction system. The pre-reduction system comprises a mixer, a briquetting machine, a pre-reduction furnace, and a furnace top charging system arranged sequentially. The mixer can mix the ironmaking raw materials evenly, and the briquetting machine can press the mixed ironmaking raw materials into lumps. The lumps of ironmaking raw materials can enter the pre-reduction furnace, which is connected to a combustion nozzle and a reducing gas inlet. The gas in the gas storage tank can be supplied to the combustion nozzle of the pre-reduction furnace and burned in the pre-reduction furnace. The gas in the gas storage tank can also be supplied to the reducing gas inlet of the pre-reduction furnace and used to reduce the lumps of ironmaking raw materials. The furnace top charging system can transport the ironmaking raw materials after the reduction reaction to the molten reduction furnace.

[0014] The pre-reduction furnace has a double-layer structure, containing an inner pre-reduction zone and an outer heating zone. The combustion nozzles are connected to the upper and lower sides of the outer heating zone. The furnace body inlet is located at the left end of the pre-reduction furnace, and the furnace body outlet is located at the right end of the pre-reduction furnace. The lumpy ironmaking raw material can enter the inner pre-reduction zone from the furnace body inlet and move to the right before leaving from the furnace body outlet. Both the furnace body inlet and the furnace body outlet are equipped with gas sealers, and the gas sealers are connected to N2 gas storage tanks.

[0015] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes a flue gas waste heat recovery furnace and a chimney. The pre-reduction furnace has a flue gas outlet. The flue gas in the pre-reduction furnace can be discharged from the flue gas outlet into the flue gas waste heat recovery furnace to release heat and then be discharged through the chimney. The gas in the gas storage tank can absorb heat in the flue gas waste heat recovery furnace and then be supplied to the combustion nozzle and reducing gas inlet. The right side of the pre-reduction furnace is connected to the inlet of the CO2 fixed furnace through a gas pipeline. The CO2 fixed furnace can fix and remove CO2 from the gas produced by the pre-reduction furnace.

[0016] The beneficial effects of this utility model embodiment are:

[0017] 1. A CO2 removal system was developed, which utilizes the waste heat of the coal gas from the molten reduction process to achieve the fixed removal of CO2 from the coal gas with a removal efficiency of ≥90%, thereby improving the quality of the coal gas and the efficient utilization of thermal energy resources.

[0018] 2. A CO2 conversion system was developed, which utilizes the sensible heat of the slag in the molten reduction furnace to convert the collected CO2 into CO, thereby obtaining high-quality CO-rich coal gas with a heat recovery rate of ≥50% and a CO2 conversion rate of ≥80%.

[0019] 3. A pre-reduction system with a double-layer structure was developed, which utilizes the obtained high-quality coal gas to increase the metallization rate of cold-pressed blocks by ≥55% and improve the efficiency of molten reduction smelting.

[0020] 4. Based on the various systems developed above and their interconnections, carbon recycling is achieved throughout the entire process system, reducing carbon emissions and enabling a reduction of carbon emissions by ≥50%. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0022] Figure 1 This is a schematic diagram of the system for efficient energy utilization in ironmaking based on B-MIF molten reduction, as described in this utility model.

[0023] The annotations in the attached figures are explained as follows:

[0024] 1. Mixer; 2. Briquetting machine; 3. Pre-reduction furnace; 4. Combustion nozzle; 5. Inner pre-reduction zone; 6. Outer heating zone; 7. Flue gas outlet; 8. Flue gas waste heat recovery furnace; 9. Hot flue gas inlet; 10. Cold flue gas outlet; 11. Heat exchange pipe; 12. Melting reduction furnace; 13. Slag trough; 14. Tubular outlet; 15. Hot blast stove; 16. Cold air inlet; 17. Furnace top charging system; 18. Furnace top flue gas outlet pipe; 19. CO2 solid... 20. Fixed furnace; 21. CO2 gasifier; 22. Gas storage tank; 23. Dust collector; 24. CO2 storage tank; 25. Pulverized coal silo; 26. CO2 converter; 27. Mixing spray gun; 28. Slag crusher; 29. ​​Slag pool; 30. Waste heat power generation unit; 31. Gas compressor; 32. N2 storage tank; 33. Gas sealer; 34. Cold briquette; 35. Chimney; 36. Gas analyzer; 37. Oxygen tank; 38. Reducing gas inlet. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] For ease of understanding and description, the following description of this utility model uses absolute positional relationships. Unless otherwise specified, the directional word "above" indicates... Figure 1 The direction above, the directional word "down" indicates Figure 1 The lower side of the middle, the directional word "left" indicates Figure 1 The left side of the direction, the directional word "right" indicates Figure 1 The right-hand direction in the text, the directional word "front" indicates perpendicular to. Figure 1 The direction of the paper and pointing inwards from the paper; the directional word "back" indicates perpendicular to the paper. Figure 1 The orientation of the paper is pointed outwards from the paper surface. This invention is described from the perspective of a reader or user, but the aforementioned directional terms should not be construed as limiting the scope of protection of this invention. Regarding the dimensions and angles of the components, those skilled in the art can determine them specifically based on actual needs or a limited number of experiments.

[0027] like Figure 1 As shown in the embodiment of this utility model, a system for efficient energy utilization in ironmaking based on B-MIF molten reduction includes a molten reduction furnace 12, a CO2 fixed furnace 19, a CO2 gasification furnace 20, a gas storage tank 21, a pulverized coal silo 24, and a CO2 converter 25.

[0028] The gas and air can be mixed and burned in the molten reduction furnace 12 to release heat, and the top gas generated by the combustion in the molten reduction furnace 12 can enter the CO2 stationary furnace 19;

[0029] In the CO2 fixed furnace 19, the CO2 and CaO in the top gas can react to generate CaCO3. The CO2 fixed furnace 19 can remove CO2 from the top gas. The CO2 fixed furnace 19 is connected to the CO2 gasifier 20. The CaCO3 generated in the CO2 fixed furnace 19 can enter the CO2 gasifier 20.

[0030] The gas from the top of the furnace after CO2 removal can be stored in a gas storage tank 21. The gas storage tank 21 is connected to the melting reduction furnace 12 and the CO2 gasification furnace 20. The gas in the gas storage tank 21 can be burned in the melting reduction furnace 12 and the CO2 gasification furnace 20.

[0031] In the CO2 gasifier 20, O2 and CO can be mixed and burned to release heat and decompose CaCO3 to generate CO2 and CaO. The CO2 generated in the CO2 gasifier 20 can enter the pulverized coal silo 24.

[0032] CO2 can transport the pulverized coal in the pulverized coal bin 24 to the CO2 converter 25. The molten reduction furnace 12 is connected to the CO2 converter 25 through the slag trough 13. The slag discharged from the molten reduction furnace 12 can enter the CO2 converter 25 through the slag trough 13 to release heat.

[0033] In the CO2 converter 25, CO2 and pulverized coal can react with the heat released from the slag to generate CO, and the coal gas generated in the CO2 converter 25 can enter the coal gas storage tank 21.

[0034] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes a hot blast stove 15. The molten reduction furnace 12 contains a tuyer 14 and a cold air inlet 16. The tuyer 14 is located in the middle of the molten reduction furnace 12. The hot air provided by the hot blast stove 15 can be injected into the molten reduction furnace 12 through the tuyer 14. The gas in the gas storage tank 21 can also be injected into the molten reduction furnace 12 through the tuyer 14. The cold air inlet 16 is located at the upper part of the molten reduction furnace 12, and cold air can enter the molten reduction furnace 12 through the cold air inlet 16.

[0035] like Figure 1As shown, a CO2 stationary furnace 19 and a molten reduction furnace 12 are arranged vertically. The molten reduction furnace 12 is connected to the inlet of the CO2 stationary furnace 19 through a flue gas outlet pipe 18 at the top of the furnace. The inlet of the CO2 stationary furnace 19 is located at the bottom of the CO2 stationary furnace 19. The end of the flue gas outlet pipe 18 at the top of the furnace is flush with the center line of the CO2 stationary furnace 19. The top gas discharged from the molten reduction furnace 12 can move upward in the CO2 stationary furnace 19. CaO powder can be sprayed downward from the top of the CO2 stationary furnace 19. CO2 and CaO can react with the heat of the top gas to generate CaCO3. The top gas discharged from the CO2 stationary furnace 19 can enter the gas storage tank 21 after being dusted by the dust collector 22.

[0036] Due to the influence of reaction rate, the CO2 removal rate of a single CO2 stationary furnace is limited. To improve the removal rate, a multi-stage CO2 stationary furnace series connection can be adopted, i.e., a fluidized bed configuration. With four or more stages, the CO2 solidification rate can exceed 90%. The generated CaCO3 drifts and accumulates at the bottom of the CO2 stationary furnace. Therefore, the system for efficient energy utilization in B-MIF molten reduction ironmaking includes multiple CO2 stationary furnaces 19 connected in series. A first outlet pipe and a second outlet pipe connect the CO2 stationary furnace 19 and the CO2 gasifier 20. The CaCO3 generated in the CO2 stationary furnace 19 can be recycled into the CO2 gasifier 20 through the first outlet pipe, and the CaO generated in the CO2 gasifier 20 can be recycled into the CO2 stationary furnace 19 through the second outlet pipe.

[0037] like Figure 1 As shown, the system for efficient energy utilization in B-MIF molten reduction ironmaking also includes an oxygen tank 36. A combustion nozzle 4 is installed on the upper part of the CO2 gasifier 20. A gas storage tank 21 is connected to the combustion nozzle 4 of the CO2 gasifier 20 through a first gas delivery pipeline. The gas in the gas storage tank 21 can supply the combustion nozzle 4 of the CO2 gasifier 20. The oxygen tank 36 can provide O2 to the combustion nozzle 4 of the CO2 gasifier 20. The gas and O2 burn and release heat in the CO2 gasifier 20, decomposing CaCO3 into CO2 and CaO. A gas analyzer 35 is installed on the first gas delivery pipeline. The gas analyzer 35 can detect the CO content in the first gas delivery pipeline. The amount of O2 provided by the oxygen tank 36 can be adjusted. The CO2 gasifier 20 contains a thermocouple.

[0038] The system for efficient utilization of energy in B-MIF molten reduction ironmaking also includes a CO2 storage tank 23. The CO2 gas discharged from the CO2 gasifier 20 can enter the CO2 storage tank 23 after being dusted by the dust collector 22. The CO2 gas discharged from the CO2 storage tank 23 can enter the pulverized coal silo 24 after being pressurized by the gas compressor 30. After being pressurized, the CO2 gas can be used as a carrier gas to blow the pulverized coal in the pulverized coal silo 24 into the CO2 converter 25. The CO2 converter 25 is connected to a mixing lance 26. The pulverized coal in the pulverized coal silo 24 and the pressurized CO2 gas can be sprayed into the CO2 converter 25 from the mixing lance 26. The connection between the slag trough 13 and the CO2 converter 25 is located above the mixing lance 26. The liquid slag discharged from the slag trough 13 can come into contact with the pulverized coal and CO2 mixture sprayed from the mixing lance 26. The CO2 and pulverized coal can react with the heat released by the slag to generate CO (i.e., coal gas).

[0039] like Figure 1 As shown, the system for efficient utilization of energy in ironmaking based on B-MIF molten reduction also includes a slag pool 28 and a waste heat power generation device 29. A slag crusher 27 is installed at the bottom of the CO2 converter 25. The slag in the CO2 converter 25 can be crushed by the slag crusher 27 and then enter the slag pool 28 for recycling. The CO2 converter 25, dust collector 22, waste heat power generation device 29, gas compressor 30 and gas storage tank 21 are connected in sequence. The gas (mainly CO) generated in the CO2 converter 25 can be dusted by the dust collector 22, have its heat recovered by the waste heat power generation device 29 and be pressurized by the gas compressor 30 before entering the gas storage tank 21.

[0040] The system for efficient utilization of energy in B-MIF molten reduction ironmaking also includes a pre-reduction system, which can use high-quality CO-rich coal gas to pre-reduce the furnace charge to improve the metallization rate. The pre-reduction system includes a mixer 1, a briquetting machine 2, a pre-reduction furnace 3, and a furnace top charging system 17 arranged in sequence. The mixer 1 can mix the ironmaking raw materials evenly. The briquetting machine 2 can be a double-roll briquetting machine, which can press the mixed ironmaking raw materials into blocks (or spheres). The block ironmaking raw materials can enter the pre-reduction furnace 3. The pre-reduction furnace 3 is connected to a combustion nozzle 4 and a reducing gas inlet 37. The gas in the gas storage tank 21 can be supplied to the combustion nozzle 4 of the pre-reduction furnace 3 and combusted and released heat in the pre-reduction furnace 3. The gas in the gas storage tank 21 can also be supplied to the reducing gas inlet 37 of the pre-reduction furnace 3. The gas entering the pre-reduction furnace 3 from the reducing gas inlet 37 is used to reduce the block ironmaking raw materials, that is, the gas and the ironmaking raw materials undergo a reduction reaction, which increases the metallization rate of the ironmaking raw materials. The furnace top charging system 17 can transport the ironmaking raw materials after the reduction reaction to the furnace top of the molten reduction furnace 12 and pour them into the molten reduction furnace 12.

[0041] like Figure 1 As shown, the pre-reduction furnace 3 has a double-layer structure, containing an inner pre-reduction zone 5 and an outer heating zone 6. Combustion nozzles 4 are connected to the upper and lower sides of the outer heating zone 6, and the combustion heat released by the nozzles 4 can sequentially heat the outer heating zone 6 and the inner pre-reduction zone 5. The left end of the pre-reduction furnace 3 has a furnace inlet, and the right end has a furnace outlet. A conveying device is installed inside the pre-reduction furnace 3, allowing lumpy ironmaking raw materials to enter the inner pre-reduction zone 5 from the furnace inlet, move to the right, and exit from the furnace outlet. A reducing gas inlet 37 is located at the furnace inlet. Both the furnace inlet and outlet are equipped with gas sealers 32, which are connected to an N2 storage tank 31. The gas sealer 32's gas source is N2.

[0042] The right side of the pre-reduction furnace 3 is connected to the inlet of the CO2 fixed furnace 19 via a gas pipeline. The high-temperature gas (≥800℃) rich in CO2 generated by the reduction in the inner pre-reduction zone 5 of the pre-reduction furnace 3 can be introduced into the CO2 fixed furnace 19 via the gas pipeline. The CO2 fixed furnace 19 can fix and remove the CO2 in the high-temperature gas generated by the pre-reduction furnace 3.

[0043] The system for efficient energy utilization in B-MIF molten reduction ironmaking also includes a flue gas waste heat recovery furnace 8 and a chimney 34. The upper part of the pre-reduction furnace 3 contains a flue gas outlet 7. The flue gas in the pre-reduction furnace 3 can be discharged from the flue gas outlet 7 and enter the flue gas waste heat recovery furnace 8 to release heat before being discharged through the chimney 34. For example, the flue gas discharged from the pre-reduction furnace 3 can enter the flue gas waste heat recovery furnace 8 from the hot flue gas inlet 9 and be discharged from the cold flue gas outlet 10. The gas in the gas storage tank 21 can absorb heat in the flue gas waste heat recovery furnace 8 before being supplied to the combustion nozzle 4 and the reducing gas inlet 37. For example, the flue gas waste heat recovery furnace 8 contains a heat exchange pipe 11. The gas in the gas storage tank 21 can enter the heat exchange pipe 11 to absorb heat before entering the combustion nozzle 4 and the reducing gas inlet 37 of the pre-reduction furnace 3. The heat exchange pipe 11 can be a spiral structure or a serpentine structure.

[0044] The following describes a method for efficient energy utilization in B-MIF molten reduction ironmaking. This method utilizes the aforementioned system for efficient energy utilization in B-MIF molten reduction ironmaking and includes the following steps:

[0045] The gas and air are mixed and burned in the molten reduction furnace 12, releasing heat. The top gas generated by the combustion in the molten reduction furnace 12 enters the CO2 stationary furnace 19.

[0046] In the CO2 stationary furnace 19, CO2 and CaO in the top gas react to generate CaCO3. The CO2 stationary furnace 19 removes CO2 from the top gas to form high-quality gas rich in CO after CO2 removal. The CaCO3 generated in the CO2 stationary furnace 19 can enter the CO2 gasifier 20.

[0047] The top gas after CO2 removal (i.e., high-quality gas rich in CO after CO2 removal) enters the gas storage tank 21 for storage, and the gas in the gas storage tank 21 enters the melting reduction furnace 12 and the CO2 gasification furnace 20 for combustion and heat release.

[0048] In the CO2 gasifier 20, O2 and CO are mixed and burned to release heat and decompose CaCO3 to generate CO2 and CaO. The CO2 generated in the CO2 gasifier 20 enters the pulverized coal silo 24.

[0049] CO2 transports the pulverized coal in the pulverized coal bin 24 to the CO2 converter 25, and the slag discharged from the molten reduction furnace 12 enters the CO2 converter 25 through the slag ditch 13 to release heat.

[0050] In the CO2 converter 25, CO2 and pulverized coal react with the heat released from the slag to generate CO, and the gas generated in the CO2 converter 25 enters the gas storage tank 21.

[0051] Hot air supplied by the hot blast stove 15 is injected into the molten reduction furnace 12 through the tuyeres 14, providing heat for the reduction reaction of iron oxides inside the furnace. Gas from the gas storage tank 21 is also injected into the molten reduction furnace 12 through the tuyeres 14 for combustion, providing heat to the furnace. During combustion, a large amount of CO2 is generated, and the high-temperature CO2-rich gas (500-750℃) is discharged through the flue gas outlet pipe 18 at the top of the furnace. A cold air inlet 16 is provided at the top of the molten reduction furnace 12, through which cold air enters the furnace.

[0052] The top gas discharged from the molten reduction furnace 12 moves upward in the CO2 stationary furnace 19. CaO powder is sprayed downward from the top of the CO2 stationary furnace 19. The top gas and CaO powder move in opposite directions in the CO2 stationary furnace 19. CO2 and CaO react with the heat of the top gas to generate CaCO3 (CO2+CaO=CaCO3; T≥500℃). The top gas discharged from the CO2 stationary furnace 19 (high-quality gas rich in CO after CO2 removal) enters the gas storage tank 21 after being dusted by the dust collector 22.

[0053] The CaCO3 produced in the CO2 stationary furnace 19 is recycled into the CO2 gasifier 20 through the first outlet pipe, and the CaO produced in the CO2 gasifier 20 is recycled into the CO2 stationary furnace 19 through the second outlet pipe.

[0054] The coal gas in the gas storage tank 21 is supplied to the combustion nozzle 4 of the CO2 gasifier 20, and the oxygen tank 36 provides O2 to the combustion nozzle 4 of the CO2 gasifier 20. The coal gas and O2 burn and release heat in the CO2 gasifier 20, decomposing CaCO3 into CO2 and CaO. Heating and calcining CaCO3 decomposes it into CO2 and CaO (CaCO3=CO2+CaO; T≥900℃). The gas analyzer 35 detects the CO content in the first coal gas delivery pipeline, and the flow rate of O2 supplied by the oxygen tank 36 can be adjusted in real time.

[0055] To efficiently utilize coal gas, a gas analyzer 35 is installed on the coal gas pipeline to the combustion nozzle. By real-time monitoring of CO content, the O2 flow rate (2CO + O2 = 2CO2) is adjusted to ensure complete combustion of CO and O2. Simultaneously, a thermocouple is installed inside the furnace to monitor the furnace temperature in real time. By adjusting the CO and O2 flow rates, the temperature in the CO2 gasification furnace 20 is ensured to be ≥900℃, thereby improving both combustion efficiency and CO2 purity.

[0056] The CaO generated from the decomposition of CaCO3 is recycled back to the CO2 stationary furnace 19. Specifically, to achieve the recycling of CaO, the CaCO3 at the bottom of the CO2 stationary furnace 19 is fed into the CO2 gasifier 20 approximately every 15 minutes. Then, the feed pipe is closed, and the combustion nozzle 4 of the CO2 gasifier 20 is opened for combustion heating. The gasifier calcines for 15 minutes. This intermittent processing method achieves an efficient circulation link of CaO between the CO2 stationary furnace 19 and the CO2 gasifier 20.

[0057] To efficiently utilize the collected CO2, a CO2 conversion system is proposed to convert the collected CO2 into CO. The CO2 gas discharged from the CO2 gasifier 20 is filtered by the dust collector 22 and then enters the CO2 storage tank 23. The CO2 gas discharged from the CO2 storage tank 23 is pressurized by the gas compressor 30 and then enters the pulverized coal silo 24. The pressurized CO2 gas acts as a carrier gas to blow the pulverized coal in the pulverized coal silo 24 into the CO2 converter 25. The pulverized coal in the pulverized coal silo 24 and the pressurized CO2 gas are injected into the CO2 converter 25 through the mixing nozzle 26. The liquid slag discharged from the slag trough 13 comes into contact with the mixture of pulverized coal and CO2 sprayed from the mixing nozzle 26. The CO2 and pulverized coal react with the heat released by the slag to generate CO (i.e., coal gas).

[0058] The molten pool in the molten reduction furnace 12 has a high temperature, so the discharged slag has a high temperature (≥1450℃). It is introduced into the CO2 converter 25 through the slag trough 13. The mixing lance is located below the end of the slag trough. When the liquid slag flows into the converter, it comes into contact with the coal powder and CO2 mixture sprayed from the lance, and an endothermic reaction occurs to generate CO (CO2+C=2CO). This achieves efficient utilization of the sensible heat of the slag while completing the CO2 conversion.

[0059] The slag in the CO2 converter 25 is crushed by the slag crusher 27 and then enters the slag pool 28 for recovery. The gas (mainly CO) generated in the CO2 converter 25 is dusted by the dust collector 22, the heat is recovered by the waste heat power generation device 29, and the gas is pressurized by the gas compressor 30 before entering the gas storage tank 21 for storage and utilization.

[0060] The CO2 converter 25 uses the sensible heat of blast furnace slag as its heat source. The slag discharge from the molten reduction furnace 12 is intermittent, with each smelting cycle lasting 30 minutes and a slag discharge time of 5 minutes. The CO2 conversion system is activated at the same time as the slag discharge, i.e., intermittent CO2 conversion. While the slag completes heat exchange, it is rapidly granulated under the high pressure of the mixing lance 26, and further crushed by the slag crusher 27 before being recovered through the slag pool 28.

[0061] The high-quality CO-rich coal gas produced in the CO2 converter 25 is stored in the coal gas storage tank 21 and can be freely allocated according to on-site needs. For example, it can be directly circulated back into the molten reduction furnace 12 through the tuyeres 14 to replace part of the solid fuel, thereby achieving further carbon reduction. Alternatively, it can be supplied externally for injection into the blast furnace and direct reduction furnace.

[0062] The method for efficient energy utilization in B-MIF-based molten reduction ironmaking further includes the following step: pre-reduction of ironmaking raw materials. The pre-reduction of ironmaking raw materials utilizes high-quality CO-rich coal gas to pre-reduce the furnace charge, thereby increasing the metallization rate. The iron-containing raw material fed into the furnace for molten reduction is cold-pressed briquette 33. Increasing the metallization rate of the cold-pressed briquette 33 fed into the furnace is beneficial for improving smelting efficiency and reducing energy consumption.

[0063] In the pre-reduction ironmaking raw material step, the mixer 1 mixes the ironmaking raw material evenly, and the briquetting machine 2 presses the mixed ironmaking raw material into block (or spherical) cold briquettes 33. Then, the block ironmaking raw material enters the pre-reduction furnace 3 under the action of the belt conveyor. The gas in the gas storage tank 21 is supplied to the combustion nozzle 4 of the pre-reduction furnace 3 and burns and releases heat in the pre-reduction furnace 3. The gas in the gas storage tank 21 is also supplied to the reducing gas inlet 37 of the pre-reduction furnace 3. The gas entering the pre-reduction furnace 3 from the reducing gas inlet 37 reduces the block ironmaking raw material and improves the metallization rate of the ironmaking raw material. The furnace top charging system 17 transports the ironmaking raw material after the reduction reaction to the furnace top of the molten reduction furnace 12 and pours it into the molten reduction furnace 12.

[0064] Combustion nozzle 4 releases heat to sequentially heat the outer heating zone 6 and the inner pre-reduction zone 5. The lumpy ironmaking raw material enters the inner pre-reduction zone 5 from the furnace inlet and moves to the right before exiting the pre-reduction furnace 3 from the furnace outlet. During this movement, it undergoes a reduction reaction with preheated CO introduced from the left side of the pre-reduction zone, increasing the metallization rate of the ironmaking raw material to ≥55%. Both the furnace inlet and outlet are equipped with gas sealers 32, which are connected to an N2 storage tank 31. The gas sealer 32's gas source is N2.

[0065] Specifically, the left and right inlets and outlets of the inner pre-reduction zone 5 are sealed with gas sealers 32 to prevent the entry of oxygen and the escape of coal gas. The sealing gas is nitrogen, which is drawn from the N2 storage tank 31. The right side of the pre-reduction furnace 3 is connected to the inlet of the CO2 fixed furnace 19 through a gas pipeline. The high-temperature coal gas (≥800℃) rich in CO2 generated by the reduction in the inner pre-reduction zone 5 of the pre-reduction furnace 3 is introduced into the CO2 fixed furnace 19 through the gas pipeline. The CO2 fixed furnace 19 fixes and removes the CO2 from the high-temperature coal gas generated by the pre-reduction furnace 3, thereby forming a carbon cycle for the entire system.

[0066] The high-temperature flue gas (≥900℃) generated by combustion in the outer heating zone 6 is discharged through the flue gas outlet 7 and enters the furnace through the hot flue gas inlet 9 of the flue gas waste heat recovery furnace 8, which is connected by a pipeline. The flue gas in the pre-reduction furnace 3 is discharged from the flue gas outlet 7 and enters the flue gas waste heat recovery furnace 8 to release heat before being discharged through the chimney 34. The gas in the gas storage tank 21 absorbs heat in the flue gas waste heat recovery furnace 8 and is then supplied to the combustion nozzle 4 and the reducing gas inlet 37. The temperature of the gas in the supply pipeline of the gas storage tank 21 is increased through heat exchange. The heated CO gas is introduced into the combustion nozzle 4 and the inner pre-reduction zone 5 to increase the combustion and reduction temperatures.

[0067] The above description is merely a specific embodiment of this utility model and should not be construed as limiting the scope of its implementation. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this utility model should still fall within its coverage. Furthermore, the technical features, technical solutions, and embodiments of this utility model can be freely combined and used.

Claims

1. A system for efficient energy utilization in ironmaking based on B-MIF molten reduction, characterized in that, The system for efficient energy utilization in ironmaking based on B-MIF molten reduction includes a molten reduction furnace (12), a CO2 stationary furnace (19), a CO2 gasification furnace (20), a gas storage tank (21), a pulverized coal silo (24), and a CO2 converter (25). The gas and air can be mixed and combusted in the molten reduction furnace (12) to release heat, and the top gas generated in the molten reduction furnace (12) can enter the CO2 stationary furnace (19); In the CO2 stationary furnace (19), CO2 and CaO in the top gas can react to generate CaCO3. The CO2 stationary furnace (19) can remove CO2 from the top gas. The CO2 stationary furnace (19) is connected to the CO2 gasifier (20). The CaCO3 generated in the CO2 stationary furnace (19) can enter the CO2 gasifier (20). The gas from the top of the furnace after CO2 removal can be stored in a gas storage tank (21). The gas storage tank (21) is connected to the melting reduction furnace (12) and the CO2 gasification furnace (20). The gas in the gas storage tank (21) can enter the melting reduction furnace (12) and the CO2 gasification furnace (20). In the CO2 gasifier (20), O2 and CO can be mixed and burned to release heat and decompose CaCO3 into CO2 and CaO. The CO2 produced in the CO2 gasifier (20) can enter the pulverized coal silo (24). CO2 can transport the pulverized coal in the pulverized coal bin (24) to the CO2 converter (25). The molten reduction furnace (12) is connected to the CO2 converter (25) through the slag ditch (13). The slag discharged from the molten reduction furnace (12) can enter the CO2 converter (25) through the slag ditch (13) to release heat. In the CO2 converter (25), CO2 and pulverized coal can react with the heat released by the slag to generate CO, and the gas generated in the CO2 converter (25) can enter the gas storage tank (21).

2. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The system for efficient utilization of energy in B-MIF molten reduction ironmaking also includes a hot blast stove (15). The molten reduction furnace (12) contains a tuyer (14) and a cold air inlet (16). The tuyer (14) is located in the middle of the molten reduction furnace (12). The hot air provided by the hot blast stove (15) can be injected into the molten reduction furnace (12) through the tuyer (14). The gas in the gas storage tank (21) can also be injected into the molten reduction furnace (12) through the tuyer (14). The cold air inlet (16) is located at the top of the molten reduction furnace (12). Air can enter the molten reduction furnace (12) through the cold air inlet (16).

3. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The molten reduction furnace (12) is connected to the inlet of the CO2 fixed furnace (19) through the flue gas outlet pipe (18) at the top of the furnace. The inlet of the CO2 fixed furnace (19) is located at the bottom of the CO2 fixed furnace (19). The top gas discharged from the molten reduction furnace (12) can move upward in the CO2 fixed furnace (19). CaO powder can be sprayed downward from the top of the CO2 fixed furnace (19). The top gas discharged from the CO2 fixed furnace (19) can enter the gas storage tank (21) after being dusted by the dust collector (22).

4. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The system for efficient utilization of energy in ironmaking based on B-MIF molten reduction includes multiple molten reduction furnaces (12) connected in series. A first outlet pipe and a second outlet pipe are connected between the CO2 stationary furnace (19) and the CO2 gasification furnace (20). The CaCO3 produced in the CO2 stationary furnace (19) can enter the CO2 gasification furnace (20) through the first outlet pipe, and the CaO produced in the CO2 gasification furnace (20) can enter the CO2 stationary furnace (19) through the second outlet pipe.

5. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The system based on B-MIF molten reduction ironmaking energy efficiency utilization also includes an oxygen tank (36), a combustion nozzle (4) is provided on the upper part of the CO2 gasifier (20), a gas storage tank (21) is connected to the combustion nozzle (4) of the CO2 gasifier (20) through a first gas delivery pipeline, the gas in the gas storage tank (21) can be supplied to the combustion nozzle (4) of the CO2 gasifier (20), the oxygen tank (36) can provide O2 to the combustion nozzle (4) of the CO2 gasifier (20), the first gas delivery pipeline is equipped with a gas analyzer (35), the gas analyzer (35) can detect CO content, the amount of O2 provided by the oxygen tank (36) can be adjusted, and the CO2 gasifier (20) contains a thermocouple.

6. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The system based on B-MIF molten reduction ironmaking energy efficiency utilization also includes a CO2 storage tank (23). The CO2 gas discharged from the CO2 gasifier (20) can enter the CO2 storage tank (23) after being dusted by the dust collector (22). The CO2 gas discharged from the CO2 storage tank (23) can enter the pulverized coal silo (24) after being pressurized by the gas compressor (30). The CO2 converter (25) is connected to a mixing nozzle (26). The pulverized coal in the pulverized coal silo (24) and the pressurized CO2 gas can enter the CO2 converter (25) from the mixing nozzle (26). The connection between the slag ditch (13) and the CO2 converter (25) is located above the mixing nozzle (26). The liquid slag discharged from the slag ditch (13) can come into contact with the pulverized coal and CO2 mixture sprayed by the mixing nozzle (26).

7. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The system based on B-MIF molten reduction ironmaking energy efficiency utilization also includes a slag pool (28) and a waste heat power generation device (29). A slag crusher (27) is provided at the bottom of the CO2 converter (25). The slag in the CO2 converter (25) can be crushed by the slag crusher (27) and enter the slag pool (28). The CO2 converter (25), dust collector (22), waste heat power generation device (29), gas compressor (30) and gas storage tank (21) are connected in sequence. The gas generated in the CO2 converter (25) can be dusted by the dust collector (22), have its heat recovered by the waste heat power generation device (29) and be pressurized by the gas compressor (30) before entering the gas storage tank (21).

8. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 1, characterized in that, The system based on B-MIF molten reduction ironmaking energy efficiency utilization also includes a pre-reduction system. The pre-reduction system contains a mixer (1), a briquetting machine (2), a pre-reduction furnace (3), and a furnace top charging system (17) arranged in sequence. The mixer (1) can mix the ironmaking raw materials evenly. The briquetting machine (2) can press the mixed ironmaking raw materials into blocks. The blocks of ironmaking raw materials can enter the pre-reduction furnace (3). The pre-reduction furnace (3) is connected to a combustion nozzle (4) and a reducing gas inlet (37). The gas in the gas storage tank (21) can be supplied to the combustion nozzle (4) of the pre-reduction furnace (3) and burned in the pre-reduction furnace (3). The gas in the gas storage tank (21) can also be supplied to the reducing gas inlet (37) of the pre-reduction furnace (3) and used to reduce the blocks of ironmaking raw materials. The furnace top charging system (17) can transport the ironmaking raw materials after the reduction reaction to the molten reduction furnace (12).

9. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 8, characterized in that, The pre-reduction furnace (3) has a double-layer structure. The pre-reduction furnace (3) contains an inner pre-reduction zone (5) and an outer heating zone (6). The combustion nozzle (4) is connected to the upper and lower sides of the outer heating zone (6). The left end of the pre-reduction furnace (3) is provided with a furnace body inlet, and the right end of the pre-reduction furnace (3) is provided with a furnace body outlet. The blocky ironmaking raw material can enter the inner pre-reduction zone (5) from the furnace body inlet and move to the right before leaving from the furnace body outlet. Both the furnace body inlet and the furnace body outlet are provided with gas sealers (32), and the gas sealers (32) are connected to N2 gas storage tanks (31).

10. The system for efficient energy utilization in B-MIF molten reduction ironmaking according to claim 9, characterized in that, The system based on B-MIF molten reduction ironmaking energy efficiency utilization also includes a flue gas waste heat recovery furnace (8) and a chimney (34). The pre-reduction furnace (3) has a flue gas outlet (7). The flue gas in the pre-reduction furnace (3) can be discharged from the flue gas outlet (7) into the flue gas waste heat recovery furnace (8) to release heat and then be discharged through the chimney (34). The gas in the gas storage tank (21) can absorb heat in the flue gas waste heat recovery furnace (8) and then be supplied to the combustion nozzle (4) and the reducing gas inlet (37). The right side of the pre-reduction furnace (3) is connected to the inlet of the CO2 fixed furnace (19) through a gas pipeline. The CO2 fixed furnace (19) can fix and remove CO2 from the gas produced by the pre-reduction furnace (3).

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