Iron ore smelting reduction system
By designing the system of pre-reduction furnace and melt reduction furnace, the vault oxygen gun is used for swirl combustion and air vent re-ignition oxygen gun to increase the temperature of the molten iron, which solves the problem of heat dissynchronization in the traditional melt reduction process, and achieves efficient and low-cost melt reduction of iron ore, which is environmentally friendly.
Patent Information
- Application Number
- CN202421541982.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-02
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2034-07-02
AI Technical Summary
In traditional blast furnaces and other melt reduction processes, the heating, melting and reduction processes of heat are in a synchronous state, resulting in low efficiency, high cost, and uneconomical.
A system including a pre-reduction furnace and a melt reduction furnace was designed, and the cyclone combustion was employed to perform cyclonic combustion, rapid heating and final reduction of iron ore, combined with a heat exchange and dust removal device to achieve thermal energy recovery, reduce costs, and increase the iron temperature through the air outlet re-ignition oxygen gun.
The pre-reduction speed and heating speed are improved, the pre-reduction and heating process is matched, the overall productivity is improved, energy consumption and cost are reduced, and the system is simple, the operation is simple, and the environment is environmentally friendly.
Smart Images
Figure CN222773768U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of iron and steel metallurgy, in particular to an iron ore melting reduction system. Background Art
[0002] At present, short-process steelmaking mainly uses scrap steel as raw material, which brings the problem of residual elements. Therefore, it is necessary to introduce a pure iron source. If direct reduced iron is used as the iron source, the gangue carried in the middle will cause serious smelting pressure on the smelting equipment. Appropriate molten iron is needed as the smelting raw material, and a new type of smelting reduction device needs to be developed to provide ironmaking raw materials for the blast furnace. The traditional blast furnace ironmaking process is to heat, reduce and melt the iron ore through the moving bed of iron ore through countercurrent CO and H2. Among them, the bottleneck of heating, reduction and melting is near the soft melting zone of the furnace waist, and most of the heat is consumed here. The combustion zone of the blast furnace is located in the lower part of the blast furnace, that is, the generation and consumption of heat in the blast furnace are in an asynchronous state, which leads to the overheating of the blast furnace combustion zone when the soft melting zone needs more heat, which is not conducive to the smooth smelting. Although the new oxygen blast furnace uses pure oxygen instead of air for smelting, the generation and consumption of heat in the blast furnace are also in an asynchronous state, and the high-efficiency smelting brought by pure oxygen is not fully utilized. The non-blast furnace ironmaking process - COREX process completes the pre-reduction of iron ore in the vertical furnace, and completes the final reduction, melting and generation of reducing gas in the smelting gasifier. The area that needs the most heat in the process is the arch of the smelting gasifier, where the final reduction, heating, melting of iron ore, heating and decomposition of coal blocks need to be completed. The heat of the COREX process comes from the combustion zone at the bottom of the smelting gasifier, where the coal blocks and pure oxygen complete the combustion reaction. Therefore, the COREX process is also a metallurgical system with asynchronous heating, smelting and reduction. The heating, melting and reduction in the system are mutually restrained, and the high efficiency of pure oxygen ironmaking cannot be exerted. Another smelting reduction process - HI smelt process heats, melts and reduces simultaneously, but there is no preheating and pre-reduction stage and only coal powder can be used as fuel, which limits the reduction of fuel ratio and cost, and does not use pure oxygen for enhanced smelting.
[0003] Traditional blast furnaces use coke as the main fuel, non-blast furnace ironmaking process - COREX process uses lump coal as the main fuel, and HI smelt process uses pulverized coal as the main fuel. These fuels consume a lot of costs and have carbon emission problems. In order to solve the waste plastic and tire crisis in cities, some advanced blast furnaces can now spray waste plastics. Waste plastics are recycled fuels, which do not have carbon emission problems and costs. On the contrary, consuming waste plastics can also receive incentive fees for urban waste treatment. Therefore, waste plastics and tires are low-cost fuels. However, the spraying of waste plastics and tires at the blast furnace tuyere requires rapid combustion due to the narrow combustion zone, and they need to be crushed and the composition must be kept stable. These requirements limit the application of low-cost fuels. Summary of the invention
[0004] The utility model aims to solve the above technical problems and provide an iron ore smelting reduction system which uses waste plastics and waste tires as main fuels and has a simple system, low cost, high efficiency and is environmentally friendly.
[0005] The utility model iron ore smelting reduction system comprises a pre-reduction furnace and a smelting reduction furnace, the bottom of the pre-reduction furnace is connected to the top of the smelting reduction furnace via a reducing iron ore feeding pipeline, the top of the pre-reduction furnace is provided with an iron ore feeding port and a pre-reduction gas outlet, and the lower part is provided with a reducing gas inlet; the top of the smelting reduction furnace is an arch, a plurality of arch oxygen guns are evenly arranged along the radial direction, and a waste material feeding port, a flux feeding port and a reducing gas outlet are also provided on the top; the furnace body of the smelting reduction furnace is provided with a waste carbon brick bed, the bottom of the bed is provided with a pre-reduction gas inlet, and the bottom of the furnace is provided with a furnace iron mouth.
[0006] It also includes two sets of heat exchange and dust removal devices in parallel, the inlets of the two sets of heat exchange and dust removal devices in parallel are connected to the pre-reduction gas outlet of the pre-reduction furnace and the reduction gas outlet of the smelting reduction furnace through valves, and the outlets of the two sets of heat exchange and dust removal devices in parallel are connected to the reduction gas inlet of the pre-reduction furnace and the pre-reduction gas inlet of the smelting reduction furnace through valves.
[0007] The pre-reduction coal gas outlet is connected to a three-way pipe through a furnace top coal gas cyclone dust collector, and the first outlet of the three-way pipe is connected to the inlets of two sets of parallel heat exchange and dust removal devices through a recovery coal gas flow regulating valve and a furnace top coal gas fan; the second outlet is connected to a dry dust removal device through an output coal gas flow regulating valve.
[0008] The heat exchange and dust removal device is a coal gas heat exchange furnace and a hot coal gas cyclone dust collector connected in series.
[0009] A heat storage body is arranged in the coal gas heat exchange furnace.
[0010] The axes of the multiple dome oxygen lances are tangent to a circle whose radius is 1 / 2 of the circle under the dome.
[0011] A tuyere supplementary combustion oxygen gun is provided below the pre-reduction coal gas inlet.
[0012] A conveyor, a roller feeder and an intermediate silo are sequentially arranged at the lower part of the pre-reduction furnace.
[0013] In view of the problems existing in the background technology, the inventor has made the following improvements:
[0014] (1) The top of the smelting reduction furnace is an arch, and a plurality of arch oxygen lances are evenly arranged along the radial direction. At the same time, a waste material inlet is set on the top. The added waste plastics and waste tires are used to carry out swirl combustion with pure oxygen in the arch of the smelting reduction furnace, so as to directly and quickly heat and finally reduce the pre-reduced iron ore. The pre-reduction speed and the heating speed are matched, so that the pre-reduction speed is increased by 30%. In the smelting reduction furnace, the combustion zone is located in the arch part of the smelting reduction furnace, so that the pre-reduced iron ore passes through the combustion zone during the falling process of the arch, and the final reduction, heating and melting are completed within 9 seconds. During the rapid movement of the waste carbon brick material bed, the melting of the molten iron and the slag reaction are completed within 10 minutes to generate high-temperature molten iron. The overall productivity of the system of the present invention is increased by more than 30% compared with that of a traditional blast furnace or a modern smelting reduction furnace.
[0015] (2) The tuyere of the oxygen lance on the dome is distributed in a ring shape, and the axes of all oxygen lances are tangent to a circle whose radius is 1 / 2 of the circle under the dome. The supersonic pure oxygen flow blown in along the inscribed circle forms a rotating flow of gas around the dome after burning with the rich fuel of the furnace top gas. Under the action of the horizontal rotating flow of gas, a high-temperature vertical circulating gas flow is generated to quickly heat the material, thereby further improving the production efficiency.
[0016] (3) The pre-reduction gas outlet of the pre-reduction furnace and the reduction gas outlet of the smelting reduction furnace are connected to the reduction gas inlet of the pre-reduction furnace and the pre-reduction gas inlet of the smelting reduction furnace through a heat exchange and dust removal device. The high-temperature reduction gas is stored here for heating the pre-reduction gas, realizing heat energy recovery, reducing production costs, and being environmentally friendly. The heat exchange and dust removal device is a series-connected coal gas heat exchange furnace and a hot coal gas cyclone dust collector. The hot coal gas and furnace dust in the coal gas cyclone dust collector undergo a carbon dissolution reaction, and the temperature is reduced to 1400°C, and the CO% is increased to more than 90%.
[0017] (4) A tuyere supplementary oxygen gun is provided below the reducing gas inlet, which can blow a small amount of oxygen into the molten reduction furnace to raise the temperature near the tuyere to 1500°C, ultimately ensuring that the output molten iron temperature is higher than 1400°C, providing a pure iron source with high physical heat for steelmaking, reducing the energy consumption of steelmaking and improving productivity.
[0018] (5) The utility model has a simple system and is easy to operate. It uses waste plastics and waste tires as fuel, has low fuel cost, has independent strengthening of the smelting reduction furnace and the pre-reduction furnace, has good process flexibility, has low preparation investment and operation costs, is environmentally friendly, and has good economy. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is the first state diagram of the system of the present utility model.
[0020] Figure 2 This is the second state diagram of the system of the present utility model.
[0021] Figure 3 This is a schematic diagram of the installation of the dome oxygen gun.
[0022] Among them, 1. Pre-reduction furnace; 2. Smelting reduction furnace; 3. Gas heat exchange furnace A; 4. Gas heat exchange furnace B; 5. Hot gas cyclone dust collector A; 6. Furnace top gas cyclone dust collector; 7. Furnace top gas fan; 8. Iron ore inlet; 9. Waste carbon brick inlet; 10. Waste material inlet; 11. Flux material inlet; 12. Dome oxygen gun; 13. Tuyere supplementary combustion oxygen gun; 14. Roller feeder; 15. Dry dust removal device; 16. Raw gas inlet; 17. Hot gas cyclone dust collector B; 18. Conveyor; 19. Intermediate silo; 20. Pre-reduction iron ore feeding pipe; 21. Reduction gas outlet; 22. Vault; 23. Waste carbon brick bed; 24. Furnace body; 26. Pre-reduction gas inlet; 27. Furnace hearth; 28. Furnace hearth iron mouth; 29. Pre-reduction gas outlet; 30. Tee pipe; 31. Recovery gas flow regulating valve; 32. Output gas flow regulating valve. DETAILED DESCRIPTION
[0023] The utility model system is further explained below in conjunction with the accompanying drawings:
[0024] See also Figure 1-Figure 3 The iron ore smelting reduction system of the utility model comprises a pre-reduction furnace 1 and a smelting reduction furnace 2; the bottom of the pre-reduction furnace 1 is connected to the top of the smelting reduction furnace 2 via a reduced iron ore feeding pipeline 20.
[0025] The top of the pre-reduction furnace 1 is provided with an iron ore inlet 8 and a pre-reduction gas outlet 21, and the lower part is provided with a reduction gas inlet 16; below the reduction gas inlet 16 are provided a conveyor 18, a roller feeder 14 and an intermediate silo 19 in sequence.
[0026] The top of the smelting reduction furnace 2 is a dome 22, and a plurality of dome oxygen lances 12 are evenly arranged along the radial direction of the dome 22. Figure 3 The tuyere of the dome oxygen lance 12 is distributed in a ring shape. It is further preferred that the axes of all oxygen lances are tangent to a circle with a radius of 1 / 2 of the circle under the dome 22. The dome 22 is also provided with a waste carbon brick inlet 9, a waste material inlet 10, a flux inlet 11 and a reduction gas outlet 29. Preferably, the waste material inlet 10 and the flux inlet 11 are evenly distributed on a circle with a radius of 1 / 3 of the circle under the dome 22. The furnace body 24 of the molten reduction furnace 2 is provided with a waste carbon brick bed 23, a pre-reduction gas inlet 26 is provided at the bottom of the bed, a tuyere supplementary combustion oxygen lance 13 is provided below the pre-reduction gas inlet 26, and a furnace iron mouth 28 is provided at the bottom of the furnace 27.
[0027] It also includes two sets of heat exchange and dust removal devices connected in parallel, the first set of heat exchange and dust removal devices is a series-connected coal gas heat exchange furnace A3 (with a heat storage body) and a hot coal gas cyclone dust collector A5, and the second set of heat exchange and dust removal devices is a series-connected coal gas heat exchange furnace B4 (with a heat storage body) and a hot coal gas cyclone dust collector B17. The coal gas inlets of the coal gas heat exchange furnace A3 and the coal gas heat exchange furnace B4 are connected respectively through valves.
[0028] The two parallel sets of heat exchange and dust removal devices store heat and exchange heat alternately, and their inlets are connected to the pre-reduction gas outlet 29 of the pre-reduction furnace 1 and the reduction gas outlet 21 of the smelting reduction furnace through valves, and the outlets of the two parallel sets of heat exchange and dust removal devices are connected to the reduction gas inlet 16 of the pre-reduction furnace 1 and the pre-reduction gas inlet 26 of the smelting reduction furnace 2 through valves.
[0029] The pre-reduction gas outlet 26 is connected to the three-way pipe 30 via the furnace top gas cyclone dust collector 6. The first outlet of the three-way pipe 30 is connected to the inlets of two sets of parallel heat exchange and dust removal devices via the recovery gas flow regulating valve 32 and the furnace top gas fan 7; the second outlet is connected to the dry dust removal device 15 via the output gas flow regulating valve 31.
[0030] Process flow:
[0031] See also Figure 1 and Figure 2 , iron ore is fed into the pre-reduction furnace 1 from the iron ore feeding port 8 on the top of the pre-reduction furnace 1, and a moving bed of iron ore is formed in the pre-reduction furnace 1, and the moving bed of iron ore is heated to 850° C. in countercurrent flow with the reducing gas from the lower reducing gas inlet 16, so as to complete the pre-reduction of the iron ore (at this time, the metallization rate is 50%); after the reduction is completed, the pre-reduced iron ore is transported downward by a conveyor 18, and enters the intermediate material bin 19 after being crushed by the roller feeder 14, and finally enters the smelting reduction furnace 2 through the pre-reduction iron ore feeding pipe 20; the pre-reduction gas on the top of the pre-reduction furnace 1 is sent to the top gas cyclone dust collector 6 through the pre-reduction gas outlet 29 for dust removal, and then is divided into two streams through the three-way pipe 30, one stream is sent to the heat exchange dust removal device through the recovery gas flow regulating valve 32 and the top gas fan 7, and the other stream is sent to the dry dust removal device 15 through the output gas flow regulating valve 31 for further dust removal, and then is sent to the external gas pipeline network.
[0032] The pre-reduced iron ore is fed into the dome 22 of the smelting reduction furnace 2 through the pre-reduction iron ore feeding pipe 20, and at the same time, waste carbon bricks, waste materials (at least one of waste plastics and / or waste tire materials) and flux are respectively fed into the corresponding waste carbon brick feeding port 9, waste material feeding port 10, and flux feeding port 11. The waste is rapidly heated to above 1300°C during the falling process, and the volatile hydrocarbons are decomposed and merged into the heating gas flowing out of the waste carbon brick bed, and are burned with the pure oxygen blown into the dome oxygen lance 12 at the dome 22 to release heat, so that the temperature of the dome 22 is maintained at about 1450°C; the combustion zone in the smelting reduction furnace 2 is located at the dome In the part 22, the pre-reduced iron ore passes through the combustion zone during its fall from the arch 22, and completes final reduction, heating and melting within 9 seconds. The heat of the pre-reduction gas provides heat and kinetic energy for the smelting reduction furnace 2, and provides a driving force for the rapid movement of the waste carbon brick bed 37 to melt it. During the rapid movement of the waste carbon brick bed 23, the melting and slag reaction of the molten iron are completed to generate high-temperature molten iron, and the gangue and flux in the iron ore undergo slag reaction to generate slag and desulfurize. The molten iron and slag are merged into the furnace 27, and iron and slag are periodically discharged from the furnace iron mouth 28; the generated reducing gas is discharged through the reducing gas outlet 21 at the top.
[0033] During operation, the gas heat exchange furnace A3 or the gas heat exchange furnace B4 in the two heat exchange and dust removal devices store and release heat in turn. Figure 1 When the coal gas heat exchange furnace A3 is storing heat, the high-temperature reducing coal gas is drawn out from the reducing coal outlet 21 of the smelting reduction furnace 2 and first sent to the hot coal gas cyclone dust collector A5 for dust removal, and then enters the heated heat storage body in the heating coal gas heat exchange furnace A3. After the temperature of the reducing coal gas drops to 850°C, it is sent to the pre-reduction furnace 1 through the reducing coal gas inlet 16 of the pre-reduction furnace 1; at the same time, the coal gas heat exchange furnace B4 releases heat, and the pre-reduction gas flowing out from the pre-reduction coal gas outlet 26 of the pre-reduction furnace 1 is firstly dusted in the coal gas cyclone dust collector 6 on the furnace top, One of the streams is pressurized by the furnace top gas blower 7 and then enters the gas heat exchange furnace B4, exchanges heat with the internal storage body in the furnace to 1450°C, and then the dust removal temperature is reduced to 1400°C in the hot gas cyclone dust collector 17B, and the volume proportion of CO in the gas is increased to more than 90%, and finally is blown into the smelting reduction furnace 2 through the pre-reduction gas inlet 26 at the lower part of the smelting reduction furnace 2. There is a tuyere supplementary combustion oxygen gun 13 below the raw gas inlet 26, which blows a small amount of oxygen into the smelting reduction furnace 2 to raise the temperature near the inlet to 1500°C.
[0034] When the temperature at the top of the gas heat exchange furnace A3 reaches above 1450°C, the gas heat exchange furnace A3 and the gas heat exchange furnace B4 are switched (by using a valve), that is, the gas heat exchange furnace A3 performs heating while the gas heat exchange furnace B4 performs heat storage. The process after switching is shown in FIG. Figure 2 .
[0035] In this embodiment, the mass percentage of total iron in the lump ore used is 55%, SiO25%, Al2O30.8%, the particle size range is 30-40mm, the average residence time of the lump ore in the pre-reduction furnace is 35min, and the operating gas velocity is 2.1m / s; the flux is one or a combination of lime, limestone, and dolomite, and the amount added is determined according to the binary basicity CaO / SiO21.1 of the slag formed during the smelting reduction process. 50% (mass percentage) waste plastics + 50% (mass percentage) waste tires are added to the dome, the fuel consumption is 265kg / t, the dome oxygen blowing amount is 241kg / t, and the dome waste carbon brick consumption is 44kg / t. The gas volume of the pre-reduction furnace tuyere is 1030m 3 / t, oxygen volume for supplementary combustion at tuyere: 100m 3 / t. The gas volume of the tuyere of the smelting reduction furnace is 850m 3 .
Claims
1. An iron ore smelting reduction system, comprising a pre-reduction furnace and a smelting reduction furnace, wherein the bottom of the pre-reduction furnace is connected to the top of the smelting reduction furnace via a reduced iron ore feeding pipeline, characterized in that: The top of the pre-reduction furnace is provided with an iron ore feeding inlet and a pre-reduction gas outlet, and the lower part is provided with a reducing gas inlet; the top of the smelting reduction furnace is a dome, and a plurality of dome oxygen guns are evenly arranged along the radial direction, and the top is also provided with a waste feeding inlet, a flux feeding inlet and a reducing gas outlet; the furnace body of the smelting reduction furnace is provided with a waste carbon brick bed, the bottom of the bed is provided with a pre-reduction gas inlet, and the bottom of the furnace is provided with a furnace iron mouth.
2. The iron ore smelting reduction system according to claim 1, characterized in that: It also includes two sets of heat exchange and dust removal devices in parallel, the inlets of the two sets of heat exchange and dust removal devices in parallel are connected to the pre-reduction gas outlet of the pre-reduction furnace and the reduction gas outlet of the smelting reduction furnace through valves, and the outlets of the two sets of heat exchange and dust removal devices in parallel are connected to the reduction gas inlet of the pre-reduction furnace and the pre-reduction gas inlet of the smelting reduction furnace through valves.
3. The iron ore smelting reduction system according to claim 2, characterized in that: The outlet of the pre-reduction coal gas is connected to a three-way pipe through a furnace top coal gas cyclone dust collector, and the first outlet of the three-way pipe is connected to the inlets of two sets of parallel heat exchange and dust removal devices through a recovery coal gas flow regulating valve and a furnace top coal gas fan; The second outlet is connected to a dry dust removal device via an output gas flow regulating valve.
4. The iron ore smelting reduction system according to claim 2, characterized in that: The heat exchange and dust removal device is a coal gas heat exchange furnace and a hot coal gas cyclone dust collector connected in series.
5. The iron ore smelting reduction system according to claim 4, characterized in that: A heat storage body is arranged in the coal gas heat exchange furnace.
6. The iron ore smelting reduction system according to claim 1, characterized in that: The axes of the multiple dome oxygen lances are tangent to a circle whose radius is 1 / 2 of the circle under the dome.
7. The iron ore smelting reduction system according to any one of claims 1 to 4, characterized in that: A tuyere supplementary combustion oxygen gun is provided below the pre-reduction coal gas inlet.
8. The iron ore smelting reduction system according to any one of claims 1 to 4, characterized in that: A conveyor, a roller feeder and an intermediate silo are sequentially arranged at the lower part of the pre-reduction furnace.