A high-temperature iron-making system and method for coal gasification and simultaneous smelting reduction

Abstract

This invention discloses a high-temperature ironmaking system and method for pulverized coal gasification and synergistic melting reduction. The system comprises a pulverized coal gasification-iron oxide preheating section, a pulverized coal gasification-iron oxide reduction section, a high-temperature ironmaking melting section, and a slag-iron separation section, connected from top to bottom. The pulverized coal gasification-iron oxide preheating section is equipped with a common pulverized coal gasification burner and an iron oxide powder nozzle, as well as multiple dispersed pulverized coal gasification burners and iron oxide powder nozzles. The high-temperature ironmaking melting section is connected to the pulverized coal gasification-iron oxide reduction section via a conical inlet. In this invention, pulverized coal undergoes combustion and gasification reactions in the pulverized coal gasification-iron oxide preheating section, releasing a large amount of heat. In the pulverized coal gasification-iron oxide reduction section, the iron oxide powder undergoes a reduction reaction. The separated gas enters a waste heat comprehensive utilization unit for further utilization of waste heat. The tail gas from the ironmaking furnace can be used to heat the steam and oxygen required for the gasification reduction reaction, achieving efficient utilization of pulverized coal.

Description

Technical Field

[0001] This invention relates to a high-temperature ironmaking method and system. Background Technology

[0002] Traditional ironmaking processes include the blast furnace method, the direct reduction method, and the smelting reduction method.

[0003] Blast furnace ironmaking: Iron ore, coke, and limestone are charged from the top of the blast furnace from top to bottom, and hot air is blown in from the bottom of the tuyeres from bottom to top, forming a countercurrent contact. It has the following disadvantages: (1) High energy consumption and environmental pollution: The blast furnace ironmaking process requires a large amount of raw materials such as coal, coke, and iron ore. Coal will produce a large amount of harmful gases during the coking process, and the coal combustion process will emit a large amount of CO2, which will cause huge pollution to the environment. (2) High production cost: Coke is the main raw material for blast furnace ironmaking. Its raw material cost is becoming increasingly expensive, and coke resources are non-renewable, which leads to an increase in the cost of blast furnace ironmaking. (3) Long and complex production process: The production process of blast furnace ironmaking is long. From the raw material yard to the sintering plant, coking plant, and then to the blast furnace ironmaking system, each link requires a lot of time and resources. This long process results in a very large total investment and land area. (4) Long smelting cycle: Traditional blast furnaces rely on gas-solid phase indirect reduction, which results in a long smelting cycle. (5) Significant environmental impact: Blast furnace ironmaking generates a large amount of slag and pollutants, which seriously affect the ecological environment. In addition, the cooling capacity of the blast furnace hearth is not matched with the smelting intensity, which can easily lead to accidents such as hearth burn-through.

[0004] The direct reduction method requires the use of high-quality reducing agents, resulting in high production costs; it also has drawbacks such as complex processes, relatively low production efficiency, and difficulty in large-scale production.

[0005] The melt reduction method has drawbacks such as complex process, large equipment investment, high technical requirements, and high overall energy consumption. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-temperature ironmaking method and system that utilizes pulverized coal gasification and synergistic melting reduction with high efficiency in iron oxide reduction reaction.

[0007] To solve the above-mentioned technical problems, the present invention provides a high-temperature ironmaking system for pulverized coal gasification and synergistic melting reduction, comprising an ironmaking furnace and a waste heat comprehensive utilization unit. The ironmaking furnace includes a pulverized coal gasification-iron oxide reduction unit and a high-temperature ironmaking melting unit. The pulverized coal gasification-iron oxide reduction unit includes a pulverized coal gasification-iron oxide preheating section and a pulverized coal gasification-iron oxide reduction section. The high-temperature ironmaking melting unit is divided into a high-temperature ironmaking melting section and a slag-iron separation section. The pulverized coal gasification-iron oxide preheating section, the pulverized coal gasification-iron oxide reduction section, the high-temperature ironmaking melting section, and the slag-iron separation section are connected from top to bottom. The pulverized coal gasification-iron oxide preheating section is equipped with a common pulverized coal gasification burner and an iron oxide powder nozzle. The pulverized coal gasification-iron oxide preheating section is also equipped with multiple dispersed pulverized coal gasification burners and iron oxide powder nozzles. The pulverized coal gasification burners are connected to an oxygen-steam mixture supply pipeline, and all the iron oxide powder nozzles are connected to a steam supply pipeline. A thermal reducing gas input pipe is installed at the top of the slag-iron separation section. The pulverized coal gasification-iron oxide reduction unit adopts a cold wall, and the high-temperature ironmaking melting unit adopts a hot wall. The high-temperature ironmaking melting section and the pulverized coal gasification-iron oxide reduction section are connected by a conical opening. The small end of the conical opening is located in the high-temperature ironmaking melting section, and the large end of the conical opening is connected to the furnace wall of the pulverized coal gasification-iron oxide reduction section. The furnace wall of the high-temperature ironmaking melting section located on one side of the conical opening is provided with a tail gas outlet. The waste heat comprehensive utilization unit is connected to the tail gas outlet. The oxygen-steam mixed gas supply pipeline and the steam supply pipeline extract heat from the waste heat comprehensive utilization unit.

[0008] Preferably, the top of the pulverized coal gasification-iron oxide preheating section is provided with a feed inlet, which is connected to a common pulverized coal gasification burner and an iron oxide powder nozzle. Pulverized coal gasification burners and iron oxide powder nozzles are provided on the circumference of at least two horizontal planes on the side of the pulverized coal gasification-iron oxide preheating section, and the pulverized coal gasification burners and iron oxide powder nozzles on adjacent horizontal planes are arranged in a cross manner in the vertical direction.

[0009] Preferably, the side of the pulverized coal gasification-iron oxide preheating section is also provided with a common pulverized coal gasification burner and an iron oxide powder nozzle.

[0010] Preferably, the slag-iron separation section is connected to a steel casting mold for receiving molten iron and a slag cooling system for receiving slag.

[0011] Preferably, the waste heat comprehensive utilization unit includes a first heat extraction pipeline for extracting heat from the slag cooling system and a second heat extraction pipeline for extracting heat from the blast furnace tail gas. The second heat extraction pipeline is connected to the first heat extraction pipeline. The first heat extraction pipeline is used to input water into the second heat extraction pipeline. The second heat extraction pipeline includes a steam generation unit and an oxygen-vapor mixture generation unit. The oxygen-vapor mixture generation unit is connected to an oxygen supply unit. An oxygen-vapor mixture supply pipeline is connected to the oxygen-vapor mixture generation unit, and a steam supply pipeline is connected to the steam generation unit.

[0012] Preferably, a step is provided on one side of the furnace wall between the slag-iron separation section and the high-temperature ironmaking melting section. The slag-iron separation section is wider than the high-temperature ironmaking melting section. A slag cooler is connected to the upper slag outlet of the slag-iron separation section, and a steel casting mold is connected to the lower iron outlet of the slag-iron separation section. A slag cooler is connected to the slag cooler, and a ball mill is connected to the slag cooler. The hot reducing gas input pipe is located above the step, and the slag outlet and iron outlet are located below the step.

[0013] Preferably, the cold wall is a water-cooled wall, and a water-cooled coil is provided in the water-cooled wall. The water-cooled coil is connected to a steam drum, and the steam drum is connected to a steam generation unit.

[0014] Preferably, the waste heat comprehensive utilization unit includes a high-temperature gas preheater, a waste heat boiler, a deoxygenated water preheater, a low-temperature gas preheater, a primary oxygen steam mixer, a secondary oxygen steam mixer, an oxygen generator, a deaerator, and a boiler feed water pump. The waste heat boiler is connected to the lower part of the deoxygenated water preheater, and the deoxygenated water preheater is connected to the lower part of the low-temperature gas preheater. The high-temperature gas preheater, waste heat boiler, and deoxygenated water preheater are all tubular heat exchangers, and the low-temperature gas preheater is a heat pipe heat exchanger. The inner cavity of the low-temperature gas preheater is divided into left and right chambers, and heat transfer between the two chambers is achieved through heat pipes. The heating medium and the heated medium are located separately in the left and right chambers. The heating medium chambers of the high-temperature gas preheater, waste heat boiler, deoxygenated water preheater, and low-temperature gas preheater are connected sequentially through pipelines. The heating medium inlet of the high-temperature gas preheater is connected to the tail gas outlet of the blast furnace. The slag cooler and slag chiller are both water-cooled. The water-cooled pipes of the slag chiller, the water-cooled pipes of the slag cooler, the deaerator, and the deoxygenated water preheater are connected sequentially through pipelines. The heated medium coils of the water preheater and the waste heat boiler are connected in sequence. A boiler feed water pump is installed on the connecting pipeline of the deaerator and the deaerated water preheater. The outlet of the oxygen generator is connected to the heated medium inlet of the low-temperature gas preheater through a primary oxygen steam mixer. The heated medium outlets of the waste heat boiler and the deaerated water preheater are both connected to a steam storage unit. The high-temperature gas preheater has two independent heated medium coils, one above the other. The heated medium outlet of the low-temperature gas preheater, the steam storage unit, and the heated medium inlet of the high-temperature gas preheater are all connected to a secondary oxygen steam mixer. The heated medium outlet of the high-temperature gas preheater is connected to a pulverized coal gasification burner. The heated medium inlet of the high-temperature gas preheater is connected to a steam storage unit. The heated medium outlet of the high-temperature gas preheater is connected to an iron oxide powder nozzle. The steam storage unit consists of a steam drum and a steam main pipe connected to the steam drum. The steam main pipe is equipped with a steam outlet.

[0015] The present invention relates to a high-temperature ironmaking method using pulverized coal gasification and synergistic melting reduction, employing any of the aforementioned high-temperature ironmaking systems using pulverized coal gasification and synergistic melting reduction. Pulverized coal is transported by gas flow to the pulverized coal gasification burner in the blast furnace, and iron oxide powder is transported by gas flow to the iron oxide powder nozzle in the blast furnace. Water and oxygen are supplied to the waste heat comprehensive utilization unit, and thermal reducing gas is supplied to the thermal reducing gas input pipe. An oxygen-steam mixture supply pipeline supplies an oxygen-steam mixture to the pulverized coal gasification burner, and a steam supply pipeline supplies steam to the iron oxide powder nozzle. The pulverized coal undergoes combustion and gasification reactions in the blast furnace, releasing a large amount of heat and generating reducing gases. Iron oxide powder reacts with reducing gas to produce iron. The iron and slag are separated in the slag-iron separation section, and the molten iron and slag are collected separately. The tail gas of the blast furnace is heated by the waste heat utilization system and then purified.

[0016] Preferably, the pulverized coal and iron oxide powder are fed into the blast furnace by airflow, and the airflow input is one or more of CO2, H2, and CO, while the thermal reducing gas supplied to the thermal reducing gas input pipe is one or two of H2 and CO.

[0017] The beneficial effects of this invention are as follows: By setting up pulverized coal gasification burners and iron oxide powder nozzles in the pulverized coal gasification-iron oxide preheating section, and supplying high-temperature oxygen-steam mixture to the pulverized coal gasification burners and high-temperature steam to the iron oxide powder nozzles, the pulverized coal undergoes combustion and gasification reactions in the pulverized coal gasification-iron oxide preheating section, releasing a large amount of heat. The iron oxide powder carried by the steam is rapidly mixed with the high-temperature reducing gas, undergoing mass and heat transfer processes. The generated reducing gas carries the iron oxide powder downwards, reducing the iron oxide powder in the pulverized coal gasification-iron oxide reduction section. As the material enters through the conical inlet... In the high-temperature ironmaking melting section, the centrifugal force of the conical opening allows for better separation of gas and solid energy in the material. The separated gas enters the waste heat comprehensive utilization unit for further utilization of waste heat. It also allows the unreacted iron oxide powder to have better counter-current contact with the hot reducing gas introduced from the top of the slag-iron separation section, further realizing the reduction of high-temperature iron oxide powder. The conical opening helps to extend the residence time of the material in the pulverized coal gasification-iron oxide reduction unit, making the reaction more complete, thereby improving the reduction efficiency of iron oxide powder. The tail gas of the ironmaking furnace can heat the steam and oxygen required for the gasification reduction reaction, realizing the efficient utilization of pulverized coal.

[0018] Because it is equipped with both integrated pulverized coal gasification burners and iron oxide powder nozzles, as well as dispersed pulverized coal gasification burners and iron oxide powder nozzles, along with cold walls and hot walls, some of the iron oxide entering through the integrated nozzles can undergo a reduction reaction immediately in the pulverized coal gasification-iron oxide preheating section. Most of the iron oxide entering through the dispersed iron oxide powder nozzles will remain in the pulverized coal gasification-iron oxide reduction section and beyond before undergoing a reduction reaction. This makes the reduction reaction more dispersed in the pulverized coal gasification-iron oxide reduction unit and the high-temperature ironmaking melting section, prevents local overheating, and improves reaction efficiency. Attached Figure Description

[0019] Figure 1 This is a flowchart of the ironmaking system of the present invention; Figure 2 Figure 1 shows a first horizontal plane nozzle arrangement according to an embodiment of the present invention; Figure 3 Figure 1 shows a second horizontal plane nozzle arrangement according to an embodiment of the present invention; Figure 4 Figure 1 shows a first horizontal plane nozzle arrangement diagram according to another embodiment of the present invention; Figure 5Figure 1 shows a second horizontal plane nozzle arrangement according to another embodiment of the present invention; In the diagram, 1. Pulverized coal gasification burner, 2. Iron oxide powder nozzle, 3. Steam drum, 4. Pulverized coal gasification-iron oxide preheating section, 5. Pulverized coal gasification-iron oxide reduction section, 6. Water-cooled coil, 7. Water-cooled wall, 8. High-temperature ironmaking melting section, 9. Hot wall, 10. Slag-iron separation section, 11. Steel injection mold, 12. Slag cooler, 13. Slag cooler, 14. Ball mill, 15. Deaerator, 16. Boiler feed water pump, 17. Oxygen generator, 18. High-temperature gas preheater, 19. Waste heat boiler, 20. Deaerated water preheater, 21. Secondary oxygen steam mixer, 22. Low-temperature gas preheater, 23. Primary oxygen steam mixer, 24. Steam main, 25. Thermal reducing gas input pipe. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0021] like Figure 1 As shown, the high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction in this embodiment includes a pulverized coal gasification-iron oxide reduction unit, a high-temperature ironmaking melting unit, and a waste heat comprehensive utilization unit.

[0022] The pulverized coal gasification-iron oxide reduction unit includes a pulverized coal gasification-iron oxide preheating section 4 and a pulverized coal gasification-iron oxide reduction section 5. The high-temperature ironmaking melting unit is divided into a high-temperature ironmaking melting section 8 and a slag-iron separation section 10.

[0023] The pulverized coal gasification-iron oxide preheating section 4, the pulverized coal gasification-iron oxide reduction section 5, the high-temperature ironmaking melting section 8, and the slag-iron separation section 10 are connected from top to bottom to form an ironmaking furnace. A hot reducing gas input pipe is installed at the upper part of the slag-iron separation section 10.

[0024] The top of the pulverized coal gasification-iron oxide preheating section 4 is equipped with a feed inlet and a steam drum 3. The feed inlet is connected to a pulverized coal gasification burner 1, an iron oxide powder nozzle 2, and an oxygen-steam mixture supply pipeline, forming a unified pulverized coal gasification burner 1 and iron oxide powder nozzle 2. Figure 2 and Figure 3 As shown, the first and second horizontal planes on the side of the pulverized coal gasification-iron oxide preheating section 4 are equipped with pulverized coal gasification burners 1 and iron oxide powder nozzles 2 that are staggered circumferentially. The first horizontal plane is located above the second horizontal plane, and the pulverized coal gasification burners 1 and iron oxide powder nozzles 2 on the first and second horizontal planes are arranged in a cross pattern. Figure 4 and Figure 5 As shown, a combined pulverized coal gasification burner 1 and iron oxide powder nozzle 2 can also be installed in the side nozzles to make the reaction more dispersed.

[0025] The furnace walls of both the pulverized coal gasification-iron oxide preheating section 4 and the pulverized coal gasification-iron oxide reduction section 5 are water-cooled walls 7, and water-cooled coils 6 are installed in the water-cooled walls 7. The steam outlet of the water-cooled coils 6 is connected to the steam drum 3, and the steam drum 3 is connected to the steam main pipe 24.

[0026] Both the high-temperature ironmaking melting section 8 and the slag-iron separation section 10 have hot walls 9. A step is provided on one side of the furnace wall of the slag-iron separation section 10 and the high-temperature ironmaking melting section 8. The slag-iron separation section 10 is wider than the high-temperature ironmaking melting section 8, increasing its lateral dimension and facilitating slag-iron separation. A slag cooler 12 is connected to the upper slag outlet of the slag-iron separation section 10, and a steel casting mold 11 is connected to the lower iron outlet. A slag cooler 13 is connected below the slag cooler 12, and a ball mill 14 is connected below the slag cooler 13. The hot reducing gas input pipe 25 is located above the step, and the slag outlet and iron outlet are below the step.

[0027] The waste heat utilization unit includes a high-temperature gas preheater 18, a waste heat boiler 19, a deoxygenated water preheater 20, a low-temperature gas preheater 22, a primary oxygen steam mixer 23, a secondary oxygen steam mixer 21, an oxygen generator 17, a deaerator 15, and a boiler feed pump 16. The waste heat boiler 19 is connected to the deoxygenated water preheater 20 at its lower part, and the deoxygenated water preheater 20 is connected to the low-temperature gas preheater 22 at its lower part. The oxygen generator 17 can be a PSA oxygen generator or an air separation oxygen generator.

[0028] The high-temperature gas preheater 18, waste heat boiler 19, and deoxygenated water preheater 20 are all tubular heat exchangers that utilize coils for heat conduction. The low-temperature gas preheater 22 is a heat pipe heat exchanger with a heat pipe in the middle filled with a heat transfer medium. The inner cavity of the low-temperature gas preheater 22 is divided into left and right chambers, with heat transfer between the two chambers via heat pipes. The heating medium and the heated medium are separated in the left and right chambers. This arrangement prevents the low-temperature exhaust gas containing combustible gas and the preheated oxygen from leaking due to wear of the heat exchange tubes, which could cause the two gases to come into contact and mix, leading to an explosion. In the high-temperature gas preheater 18, due to the high temperature, if gas leakage occurs, the reducing gas and oxygen in the exhaust gas will directly burn, resulting in a very low risk of explosion. Therefore, heat can be conducted through coils. The heating medium chambers of the high-temperature gas preheater 18, waste heat boiler 19, deaerator water preheater 20, and low-temperature gas preheater 22 are connected sequentially by pipelines. The heating medium inlet of the high-temperature gas preheater 18 is connected to the high-temperature ironmaking melting section 8. The slag cooler 12 and the slag cooler 13 are both water-cooled. The water-cooled pipes of the slag cooler 13, the water-cooled pipes of the slag cooler 12, the deaerator 15, the heated medium coil of the deaerator water preheater 20, and the heated medium coil of the waste heat boiler 19 are connected sequentially. A boiler feed water pump 16 is installed on the connecting pipeline between the deaerator 15 and the deaerator water preheater 20. The gas outlet of the oxygen generator 17 passes through a primary... The oxygen-steam mixer 23 is connected to the inlet of the heated medium of the low-temperature gas preheater 22. The outlet of the heated medium of the waste heat boiler 19 and the outlet of the heated medium of the deaerated water preheater 20 are both connected to the steam drum 3 or the steam main 24. The high-temperature gas preheater 18 has two independent heated medium coils, one above the other. The outlet of the heated medium of the low-temperature gas preheater 22, the steam main 24, and the inlet of the heated medium on the high-temperature gas preheater 18 are all connected to the secondary oxygen-steam mixer 21. The outlet of the heated medium on the high-temperature gas preheater 18 is connected to the pulverized coal gasification burner 1, supplying oxygen and steam to the pulverized coal gasification burner 1. The inlet of the heated medium at the bottom of the high-temperature gas preheater 18 is connected to the steam drum 3 or the steam main 24, and the outlet of the heated medium at the bottom of the high-temperature gas preheater 18 is connected to the iron oxide powder nozzle 2.

[0029] Steam generated in the water-cooled coil 6, waste heat boiler 19, and deaerator water preheater 20 is collected in the steam drum 3 or steam main 24, and then supplied to the high-temperature gas preheater 18 for further heating to generate superheated steam, which is supplied to the iron oxide powder nozzle 2 and the first-stage oxygen steam mixer 23. The oxygen mixed with steam enters the low-temperature gas preheater 22 for further preheating, and then passes through the second-stage oxygen steam mixer 21 for further mixing with steam. It is then sent to the high-temperature gas preheater 18 for further heating to generate high-temperature oxygen-steam mixture, which is then sent to the pulverized coal gasification burner 1.

[0030] The high-temperature ironmaking melting section 8 and the pulverized coal gasification-iron oxide reduction section 5 are connected by a conical opening. The small end of the conical opening is located in the high-temperature ironmaking melting section 8, and the large end of the conical opening is connected to the furnace wall of the pulverized coal gasification-iron oxide reduction section 5. A tail gas outlet is provided on the furnace wall of the high-temperature ironmaking melting section 8 on one side of the conical opening, and the lower end of the high-temperature gas preheater 18 is connected to the tail gas outlet.

[0031] In this system, the pipelines for material flow can be equipped with corresponding power devices and valves as needed for material flow.

[0032] This embodiment employs a high-temperature ironmaking method combining pulverized coal gasification and synergistic smelting reduction. Figure 1 The high-temperature ironmaking system for pulverized coal gasification and synergistic molten reduction, as shown, involves the following steps: pulverized coal is conveyed by pneumatic gasification to the pulverized coal gasification nozzle 1 of the ironmaking furnace; iron oxide powder is conveyed by pneumatic gasification to the iron oxide powder nozzle 2 of the ironmaking furnace; demineralized water is supplied to the slag cooler; and thermal reducing gases H2 and CO (at a temperature of 1400-1600℃) are supplied to the thermal reducing gas input pipe. The conveying gas for the pulverized coal or iron oxide powder can be one or more of CO2, H2, and CO.

[0033] Pulverized coal is transported by gas flow to the pulverized coal gasification burners 1 at the top and side of the furnace body, where it undergoes combustion and water gasification reactions with high-temperature gasifying agents (oxygen and steam, 580-620℃), releasing a large amount of heat and generating a large amount of reducing gases (CO and H2, etc.). C+O2=CO2; 2C+O2=2CO; C+H2O=H2+CO; C+CO2=2CO; Some of the iron oxide powder undergoes a reduction reaction at the pulverized coal gasification burner 1 and iron oxide powder nozzle 2 in the co-existing system. The iron oxide powder is then transported by gas flow to the side iron oxide powder nozzle 2. The iron oxide powder carried by steam (at a temperature of 600-680℃) rapidly mixes with high-temperature reducing gases from the top and sides of the furnace in the pulverized coal gasification-iron oxide preheating section 4, undergoing mass and heat transfer. The reducing gases carry the iron oxide powder downwards, where it undergoes a reduction reaction in the pulverized coal gasification-iron oxide reduction section 5.

[0034] The reduction reaction is as follows: 3CO+Fe2O3=2Fe+3CO2; 3H2+Fe2O3=2Fe+3H2O; 4CO+Fe3O4=3Fe+4CO2; 4H2+Fe3O4=3Fe+4H2O; The furnace body of the pulverized coal gasification-iron oxide preheating section 4 and the pulverized coal gasification-iron oxide reduction section 5 adopts a water-cooled wall design 7, and the furnace wall is equipped with a cooling coil 6, which can remove the large amount of heat generated during the combustion and gasification process at any time; the steam generated in this process enters the steam drum 3 for system use, and the excess steam is supplied externally.

[0035] As the material enters the high-temperature ironmaking melting section 8 through the conical opening, the gas in the material enters the high-temperature gas preheater 18, and other materials continue to move downwards. The unreacted iron oxide powder comes into counter-current contact with the hot reducing gas introduced from the top of the slag-iron separation section 10, further reducing the high-temperature iron oxide powder. The reduced molten iron and slag enter the slag-iron separation section 10 under gravity for the separation of molten iron and slag. The molten iron at the bottom of the slag-iron separation section 10 enters the steel casting mold 11 for steelmaking, and the upper slag is cooled by the slag cooler 12 and then enters the slag cooler 13 for further cooling. It is then cooled by heat exchange in the demineralized water. The cooled steel slag is mixed with additives and sent to the ball mill 14 for ultrafine grinding. The ground product is used as a PVC additive.

[0036] The oxygen produced by the oxygen generator 17 is mixed with steam in the first-stage oxygen-steam mixer 23 and then enters the low-temperature gas preheater 22. After exchanging heat with the tail gas and raising the temperature, it is further mixed with steam in the second-stage oxygen-steam mixer 21 and then enters the high-temperature gas preheater 18, which raises the temperature of the oxygen steam to 580-620℃. It is then fed into the pulverized coal gasification burner 1 as a gasifying agent.

[0037] The demineralized water first exchanges heat with the slag in the new type of slag cooler 13 to raise its temperature, and then enters the slag cooler 12 to exchange heat with the high-temperature slag. After that, it enters the deaerator 15. The deoxygenated water is sent to the deoxygenated water preheater 20 by the boiler feed water pump 16 for further heating, and then enters the waste heat boiler 19 and the steam drum 3. Part of the steam produced by the waste heat boiler 19 is used as the gasification agent of the system, and the excess is supplied externally.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-temperature ironmaking system for pulverized coal gasification and synergistic melting reduction, comprising an ironmaking furnace and a waste heat comprehensive utilization unit, characterized in that: The blast furnace includes a pulverized coal gasification-iron oxide reduction unit and a high-temperature blast furnace melting unit. The pulverized coal gasification-iron oxide reduction unit includes a pulverized coal gasification-iron oxide preheating section and a pulverized coal gasification-iron oxide reduction section. The high-temperature blast furnace melting unit is divided into a high-temperature blast furnace melting section and a slag-iron separation section. The pulverized coal gasification-iron oxide preheating section, the pulverized coal gasification-iron oxide reduction section, the high-temperature blast furnace melting section, and the slag-iron separation section are connected from top to bottom. The pulverized coal gasification-iron oxide preheating section is equipped with a common pulverized coal gasification burner and an iron oxide powder nozzle. The pulverized coal gasification-iron oxide preheating section is also equipped with multiple dispersed pulverized coal gasification burners and iron oxide powder nozzles. The pulverized coal gasification burners are connected to an oxygen-steam mixture supply pipeline, and all the iron oxide powder nozzles are connected to a steam supply pipeline. A thermal reducing gas input pipe is installed at the top of the slag-iron separation section. The pulverized coal gasification-iron oxide reduction unit adopts a cold wall, and the high-temperature ironmaking melting unit adopts a hot wall. The high-temperature ironmaking melting section and the pulverized coal gasification-iron oxide reduction section are connected by a conical opening. The small end of the conical opening is located in the high-temperature ironmaking melting section, and the large end of the conical opening is connected to the furnace wall of the pulverized coal gasification-iron oxide reduction section. The furnace wall of the high-temperature ironmaking melting section located on one side of the conical opening is provided with a tail gas outlet. The waste heat comprehensive utilization unit is connected to the tail gas outlet. The oxygen-steam mixed gas supply pipeline and the steam supply pipeline extract heat from the waste heat comprehensive utilization unit.

2. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 1, characterized in that: The top of the pulverized coal gasification-iron oxide preheating section is provided with a feed inlet, which is connected to a common pulverized coal gasification burner and an iron oxide powder nozzle. Pulverized coal gasification burners and iron oxide powder nozzles are provided on the circumference of at least two horizontal planes on the side of the pulverized coal gasification-iron oxide preheating section, and the pulverized coal gasification burners and iron oxide powder nozzles on adjacent horizontal planes are arranged in a cross manner in the vertical direction.

3. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 2, characterized in that: The side of the pulverized coal gasification-iron oxide preheating section is also equipped with a common pulverized coal gasification burner and an iron oxide powder nozzle.

4. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 1, characterized in that: The slag-iron separation section is connected to a steel casting mold for receiving molten iron and a slag cooling system for receiving slag.

5. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 4, characterized in that: The waste heat comprehensive utilization unit includes a first heat extraction pipeline for extracting heat from the slag cooling system and a second heat extraction pipeline for extracting heat from the blast furnace tail gas. The second heat extraction pipeline is connected to the first heat extraction pipeline. The first heat extraction pipeline is used to input water into the second heat extraction pipeline. The second heat extraction pipeline includes a steam generation unit and an oxygen-vapor mixture generation unit. The oxygen-vapor mixture generation unit is connected to an oxygen supply unit. An oxygen-vapor mixture supply pipeline is connected to the oxygen-vapor mixture generation unit, and a steam supply pipeline is connected to the steam generation unit.

6. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 5, characterized in that: The furnace wall on one side of the slag-iron separation section and the high-temperature ironmaking melting section is provided with a step. The slag-iron separation section is wider than the high-temperature ironmaking melting section. The slag outlet at the upper part of the slag-iron separation section is connected to a slag cooler, and the iron outlet at the lower part of the slag-iron separation section is connected to a steel casting mold. The slag cooler is connected to a slag cooler, and the slag cooler is connected to a ball mill. The hot reducing gas input pipe is located above the step, and the slag outlet and iron outlet are located below the step.

7. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 6, characterized in that: The cold wall is a water-cooled wall, and a water-cooled coil is installed in the water-cooled wall. The water-cooled coil is connected to a steam drum, and the steam drum is connected to a steam generation unit.

8. The high-temperature ironmaking system of pulverized coal gasification and synergistic melting reduction according to claim 7, characterized in that: The waste heat comprehensive utilization unit includes a high-temperature gas preheater, a waste heat boiler, a deoxygenated water preheater, a low-temperature gas preheater, a primary oxygen steam mixer, a secondary oxygen steam mixer, an oxygen generator, a deaerator, and a boiler feed water pump. The waste heat boiler is connected to the lower part of the deoxygenated water preheater, which is connected to the lower part of the low-temperature gas preheater. The high-temperature gas preheater, waste heat boiler, and deoxygenated water preheater are all tubular heat exchangers, while the low-temperature gas preheater is a heat pipe heat exchanger. The inner cavity of the low-temperature gas preheater is divided into left and right chambers, with heat transfer between the two chambers via heat pipes. The heating medium and the heated medium are located separately in the left and right chambers. The heating medium chambers of the high-temperature gas preheater, waste heat boiler, deoxygenated water preheater, and low-temperature gas preheater are connected sequentially by pipes. The heating medium inlet of the high-temperature gas preheater is connected to the tail gas outlet of the blast furnace. The slag cooler and slag chiller are both water-cooled. The water-cooled pipes of the slag chiller, the water-cooled pipes of the slag cooler, the deaerator, and the deoxygenated water preheater are connected sequentially. The heated medium coils of the heat exchanger and the waste heat boiler are connected in sequence. A boiler feed water pump is installed on the connecting pipeline of the deaerator and the deoxygenated water preheater. The outlet of the oxygen generator is connected to the heated medium inlet of the low-temperature gas preheater through a primary oxygen steam mixer. The heated medium outlets of the waste heat boiler and the deoxygenated water preheater are both connected to a steam storage unit. The high-temperature gas preheater has two independent heated medium coils, one above the other. The heated medium outlet of the low-temperature gas preheater, the steam storage unit, and the heated medium inlet of the high-temperature gas preheater are all connected to a secondary oxygen steam mixer. The heated medium outlet of the high-temperature gas preheater is connected to a pulverized coal gasification burner. The heated medium inlet of the high-temperature gas preheater is connected to a steam storage unit. The heated medium outlet of the high-temperature gas preheater is connected to an iron oxide powder nozzle. The steam storage unit consists of a steam drum and a steam main pipe connected to the steam drum. The steam main pipe is equipped with a steam outlet.

9. A high-temperature ironmaking method using pulverized coal gasification and synergistic smelting reduction, characterized in that: The high-temperature ironmaking system using pulverized coal gasification and synergistic melting reduction as described in any one of claims 1-8 involves pulverized coal being transported by pneumatic gas to the pulverized coal gasification burner in the ironmaking furnace, iron oxide powder being transported by pneumatic gas to the iron oxide powder nozzle in the ironmaking furnace, water and oxygen being supplied to the waste heat comprehensive utilization unit, and thermal reducing gas being supplied to the thermal reducing gas input pipe. An oxygen-steam mixture supply pipeline supplies an oxygen-steam mixture to the pulverized coal gasification burner, and a steam supply pipeline supplies steam to the iron oxide powder nozzle. The pulverized coal undergoes combustion and gasification reactions in the ironmaking furnace, releasing a large amount of heat and generating reducing gases. Iron oxide powder reacts with reducing gas to produce iron. The iron and slag are separated in the slag-iron separation section, and the molten iron and slag are collected separately. The tail gas of the blast furnace is heated by the waste heat utilization system and then purified.

10. The high-temperature ironmaking method of pulverized coal gasification and synergistic melting reduction according to claim 9, characterized in that: The pulverized coal and iron oxide powder are fed into the ironmaking furnace by airflow. The airflow input uses one or more of CO2, H2, and CO. The thermal reducing gas supplied to the thermal reducing gas input pipe is one or two of H2 and CO.

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