CN115354105A - System and method for reducing exhaust gas circulating gas-based direct reduced iron - Google Patents
System and method for reducing exhaust gas circulating gas-based direct reduced iron Download PDFInfo
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- CN115354105A CN115354105A CN202210988593.1A CN202210988593A CN115354105A CN 115354105 A CN115354105 A CN 115354105A CN 202210988593 A CN202210988593 A CN 202210988593A CN 115354105 A CN115354105 A CN 115354105A
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 104
- 238000000034 method Methods 0.000 title claims abstract description 51
- 230000009467 reduction Effects 0.000 claims abstract description 104
- 230000008569 process Effects 0.000 claims abstract description 22
- 239000002994 raw material Substances 0.000 claims abstract description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 11
- 239000002028 Biomass Substances 0.000 claims abstract description 6
- 239000003245 coal Substances 0.000 claims abstract description 6
- 239000007789 gas Substances 0.000 claims description 224
- 238000006722 reduction reaction Methods 0.000 claims description 116
- 239000000843 powder Substances 0.000 claims description 77
- 238000002309 gasification Methods 0.000 claims description 46
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 32
- 239000011707 mineral Substances 0.000 claims description 32
- 229910052742 iron Inorganic materials 0.000 claims description 25
- 239000000428 dust Substances 0.000 claims description 24
- 239000002918 waste heat Substances 0.000 claims description 24
- 238000000746 purification Methods 0.000 claims description 22
- 238000002156 mixing Methods 0.000 claims description 21
- 238000002485 combustion reaction Methods 0.000 claims description 20
- 230000008929 regeneration Effects 0.000 claims description 20
- 238000011069 regeneration method Methods 0.000 claims description 20
- 238000001179 sorption measurement Methods 0.000 claims description 20
- 238000007731 hot pressing Methods 0.000 claims description 15
- 238000007885 magnetic separation Methods 0.000 claims description 12
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 229910052739 hydrogen Inorganic materials 0.000 claims description 9
- 238000011084 recovery Methods 0.000 claims description 9
- 229910001608 iron mineral Inorganic materials 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 239000004744 fabric Substances 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 239000003546 flue gas Substances 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 230000001172 regenerating effect Effects 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 230000005587 bubbling Effects 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003034 coal gas Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
- C21B2100/20—Increasing the gas reduction potential of recycled exhaust gases
- C21B2100/28—Increasing the gas reduction potential of recycled exhaust gases by separation
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
- C21B2100/20—Increasing the gas reduction potential of recycled exhaust gases
- C21B2100/28—Increasing the gas reduction potential of recycled exhaust gases by separation
- C21B2100/282—Increasing the gas reduction potential of recycled exhaust gases by separation of carbon dioxide
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
- C21B2100/40—Gas purification of exhaust gases to be recirculated or used in other metallurgical processes
- C21B2100/44—Removing particles, e.g. by scrubbing, dedusting
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
- C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
- C21B2100/66—Heat exchange
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
Abstract
The invention relates to a system and a method for reducing exhaust gas circulating gas-based direct reduced iron. The invention provides a method for preparing reducing gas by gasifying carbon-rich raw materials such as coal or biomass and the like, and reducing exhaust gas with certain reduction potential and sensible heat energy is recycled by heat and quality according to a gas-based direct reduced iron process, so that the energy consumption of the gas-based short-flow ironmaking process is reduced.
Description
Technical Field
The invention belongs to the technical field of metal smelting, and particularly relates to a system and a method for reducing exhaust gas circulating gas-based direct reduced iron.
Background
The information disclosed in this background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
At present, the steel production process mainly comprises a long-flow process of sintering and a blast furnace, and the problems of complex process flow, high energy consumption, large pollutant discharge amount and the like exist in the operation process. On the other hand, as the industrialization progresses deeply, the recovery rate of the scrap steel increases, and the demand of the utilization of the scrap steel on direct reduced iron (sponge iron) also increases remarkably. The direct reduced iron is an industrial raw material, is mainly used for electric furnace steelmaking, and partially replaces scrap steel or is matched with the scrap steel for use so as to improve furnace burden.
The short-flow ironmaking process of gas-based direct reduction not only can meet the requirement of direct reduced iron production, but also has the advantages of short process flow and low pollutant discharge. However, compared with Gao Lugao, the energy consumption of the gas-based direct reduced iron is mainly caused by the fact that the reduction potential and the countercurrent heat exchange of the reducing gas are fully utilized in the traditional blast furnace smelting process, and the discharged blast furnace gas is low in heat value and temperature; and the reduction exhaust gas discharged in the short-process iron smelting process has high reduction potential and high temperature, so that the reduction of the energy consumption of the gas-based direct reduced iron is a problem which needs to be solved in the large-scale industrial application of the short-process direct reduced iron. In addition, china is a country rich in coal, lean in oil and less in gas, and the gas-based direct iron reduction process by using natural gas, coal gas or hydrogen as an iron ore powder reducing agent faces the neck problems of resource shortage, import requirement, high price and the like; directly threatens the sustainable development of the steel industry in China.
Disclosure of Invention
In view of the current energy situation of China and the double problems of high energy consumption in the process of directly reducing iron by gas base, the invention provides a system and a method for reducing exhaust gas circulation by gas base directly reduced iron. The invention provides a method for preparing reducing gas by gasifying carbon-rich raw materials such as coal or biomass and the like, and reducing exhaust gas with certain reduction potential and sensible heat energy is recycled by heat and quality according to a gas-based direct reduced iron process, so that the energy consumption of the gas-based short-flow ironmaking process is reduced.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect of the present invention, there is provided a system for reducing exhaust gas circulated gas-based direct reduced iron, comprising: the device comprises a gasification device, a mixing unit, a mineral powder reduction unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device, a pressure swing adsorption purification device, a reduced iron powder cooler, a magnetic separation device and a hot pressing device; the device comprises a gasification device, a mixing unit, a mineral powder reduction unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device and a pressure swing adsorption purification device which are sequentially connected, and the mineral powder preheating unit, the mineral powder reduction unit, a reduced iron powder cooler, a magnetic separation device and a hot pressing device are sequentially connected.
Further, the system also comprises a combustion device; the inlet of the combustion device is connected with the dust removal device, and the outlet pipeline of the combustion device is connected with the outlet pipeline of the heat regeneration device and converged into a pipeline which is connected with the mixing unit.
The invention provides a method for reducing exhaust gas circulating gas-based direct reduced iron. The method comprises the following steps:
(1) The carbon-rich raw material reacts with a gasifying agent in a gasifying device to generate H 2 The CO gas and the part of the reduction exhaust gas with lower temperature at the outlet of the dust removal device are returned to the gasification device for temperature regulation;
(2) The gasified gas generated by the gasification device is mixed with the purified and heated circulating reducing gas in the mixing unit to form reducing gas, and the reducing gas enters the mineral powder reducing unit to generate the reduction reaction of iron mineral powder; converting iron ore powder into a direct reduced iron powder product, cooling the direct reduced iron powder product by an iron powder cooler, entering a magnetic separation device to realize primary screening and purification, hot-pressing the product into blocks by a hot-pressing device, and conveying the blocks to the next procedure;
(3) After the direct reduction reaction occurs, the reducing gas is converted into reducing exhaust gas; the reduction exhaust gas enters a mineral powder preheating unit to preheat the iron mineral powder raw material, then enters a heat regeneration device, exchanges heat with the purified circulating reduction gas in the heat regeneration device, reduces the temperature of the reduction exhaust gas to 200-500 ℃, and then enters a waste heat boiler to recover the residual sensible heat energy;
(4) The reduction exhaust gas discharged from the outlet of the waste heat boiler is dedusted, and most of the reduction exhaust gas enters a pressure swing adsorption purification device to remove H in the reduction gas 2 O and CO 2 Obtaining purified circulating reducing gas, recovering part of sensible heat of the reducing exhaust gas by the circulating reducing gas through a heat recovery device, burning one part of the reducing exhaust gas in a burning device to raise the temperature of the circulating reducing gas discharged from the heat recovery device, and mixing the circulating reducing gas with the gasified gas produced by a gasification device in a mixing unit; the other part of the reduction exhaust gas enters a gasification device to participate in the temperature adjustment of the gasified gas.
Further, the carbon-rich raw material includes coal, biomass, and the like. The gasifying agent comprises pure O 2 、H 2 O、CO 2 。
Further, in the gasification device, the carbon-rich raw material and the gasifying agent react at a high temperature of 1200-2000 ℃; part of the reduced exhaust gas with lower temperature at the outlet of the waste heat boiler is returned to the gasification device for temperature adjustment, and the temperature of the gasified gas at the outlet of the final gasification device is 800-1300 ℃.
Further, the composition of the gasified gas is as follows: CO 30-60 vol%, H 2 20-40% by volume of CO 2 0 to 15 percent by volume, H 2 The volume percentage of O is 0-10%.
Further, the reduced iron ore powder passes through an iron powder cooler, and the temperature is reduced to 25-700 ℃.
Further, the reducing gas comprises the following components: CO accounting for 40 to 60 percent by volume and H 2 30-40% by volume of CO 2 0 to 5 percent by volume, H 2 The volume percentage of O is 0 to 5 percent. The temperature of the reducing gas is 800-1300 ℃.
The temperature of the reduction reaction is controlled between 800 and 1100 ℃.
Further, after the direct reduction reaction occurs, the reducing gas is converted into reducing exhaust gas, and the temperature of the reducing exhaust gas is 700-1000 ℃.
Further, reducing the exhaust gas to preheat the iron ore powder raw material to 500-800 ℃ at normal temperature.
Furthermore, the temperature of the reduction exhaust gas discharged from the ore powder preheating unit is 600-900 ℃, heat exchange is carried out between the reduction exhaust gas and the purified circulating reduction gas in a heat regeneration device, and the temperature of the reduction exhaust gas is reduced to 200-500 ℃.
Furthermore, the temperature of the reduction exhaust gas discharged from the outlet of the waste heat boiler is 100-300 ℃.
Furthermore, the temperature of the circulating reducing gas is raised to 800-1300 ℃ by burning part of the reducing exhaust gas.
Further, CO in the circulating reducing gas purified by pressure swing adsorption 2 And H 2 0-5% of O, 50-60% of CO and H 2 The volume percentage is 40-50%.
Furthermore, the exhaust gas is partially reduced by using the combustion device, the heat of the high-temperature flue gas generated by combustion is transferred to the circulating reduction gas, and the heat can be realized by using a heat accumulating type heat exchanger or a high-temperature-resistant shell-and-tube heat exchanger.
Further, the particle size of the iron ore powder is 50-1000 microns.
Further, the gas conveying process is provided with conveying power by an induced draft fan or a blower.
Further, the dust removing device can be a cloth bag dust removing device, a cyclone separator, an axial flow type cyclone separator, an electrostatic dust remover and the like.
The invention has the beneficial effects that: the invention provides a reduction exhaust gas circulation process and a reduction exhaust gas circulation method for gas-based direct reduced iron. According to the characteristics of high reduction potential and high temperature of the reduction exhaust gas in the short-process direct reduction iron process, the heat/mass recycling of the reduction gas is realized by reasonably arranging the purification and circulation modes of the reduction exhaust gas, the reduction treatment capacity of iron ore powder is increased, the energy consumption of system ton iron is reduced, the system economy is improved, and the method has wide application prospect.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic process diagram of the reduction off-gas cycle of gas-based direct reduced iron of the present invention.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
As shown in fig. 1, the present invention provides a system and method for reducing gas-based direct reduced iron of a spent gas cycle.
The invention provides a system for circulating reduction exhaust gas of gas-based direct reduced iron, which comprises: the device comprises a gasification device, a reducing gas mixing unit, a mineral powder reducing unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device, a pressure swing adsorption purification device, a combustion device, a reduced iron powder cooler, a magnetic separation device and a hot pressing device. The device comprises a gasification device, a mixing unit, a mineral powder reduction unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device and a pressure swing adsorption purification device which are sequentially connected, and the mineral powder preheating unit, the mineral powder reduction unit, a reduced iron powder cooler, a magnetic separation device and a hot pressing device are sequentially connected.
The invention also provides a method for recycling the reduction exhaust gas of the gas-based direct reduced iron.
Firstly, coal or biomass and other carbon-rich raw materials are mixed with pure O in the high temperature range of 1200-2000 DEG C 2 、H 2 O、CO 2 The gasification agent reacts to generate rich H 2 CO, the main reaction generated is C + O 2 ＝CO 2 ，C+O 2 ＝2CO，C+CO 2 ＝2CO，C+H 2 O＝CO+H 2 . Part of the reduced exhaust gas with lower temperature at the outlet of the waste heat boiler is returned to the gasification device for temperature adjustment, and the temperature of the gasified gas at the outlet of the final gasification device is 800-1300 ℃. According to the difference of the carbon-rich raw materials, the concentration of the gasified gas produced by the gasification device is changed within a certain range, wherein the volume percentage of CO is 30-60%, and H is 2 20-40% by volume of CO 2 0 to 15 percent by volume, H 2 Volume percent of O0 to 10 percent.
The gasified gas produced by the gasification device is mixed with the purified and heated circulating reducing gas in the mixing unit to form reducing gas, the reducing gas enters the mineral powder reducing unit to carry out reduction reaction of iron mineral powder, and the main reaction is 3Fe 2 O 3 +CO＝2Fe 3 O 4 +CO 2 ，Fe 3 O 4 +CO＝3FeO+CO 2 ，FeO+CO＝Fe+CO 2 ，Fe 2 O 3 +CO＝2FeO+CO 2 ，3Fe 2 O 3 +H 2 ＝2Fe 3 O 4 +H 2 O，Fe 3 O 4 +H 2 ＝3FeO+H 2 O，FeO+H 2 ＝Fe+H 2 O，Fe 2 O 3 +H 2 ＝2FeO+H 2 And O. In the reaction, the effective components of CO and H2 in the reducing gas are finally deprived of oxygen atoms in the iron ore powder to generate CO 2 And H 2 O (CO and H in reducing gas) 2 Partial conversion to CO 2 And H 2 O, but CO and H 2 Still a major part). Meanwhile, the iron ore powder is converted into a direct reduction iron powder product, the temperature of the reduced iron ore powder can be reduced to 25-700 ℃ through an iron powder cooler, and the function of temperature reduction is to prevent secondary oxidation of the direct reduction iron. And the cooled direct reduced iron powder enters a magnetic separation device to realize primary screening and purification, is hot-pressed into blocks by a hot-pressing device, and is conveyed to the next procedure.
After the direct reduction reaction occurs, the reducing gas is converted into reducing exhaust gas (H) 2 And CO reduction potential is reduced), but has certain reduction potential and sensible heat energy, the temperature is 700-1000 ℃, the emission can cause direct waste of energy, but the reduction of exhaust gas also has the characteristics of low heat value, small gas quantity and the like, and the energy-saving mode of directly burning, generating and recovering energy is often not energy-saving. The invention therefore proposes to achieve heat/mass recovery of the reduced offgas after reduction. Recovering sensible heat of the reduction exhaust gas, preheating the iron ore powder raw material, and preheating the iron ore powder raw material to 500-800 ℃ at normal temperature. The temperature of the reduction exhaust gas discharged from the ore powder preheating unit is about 600-900 ℃, the reduction exhaust gas is subjected to heat exchange with the purified circulating reduction gas in a heat regeneration device, the temperature of the reduction exhaust gas is reduced to 200-500 ℃, and the reduction exhaust gas enters a waste heat boiler to returnThe residual sensible heat energy is collected.
The temperature of the reduction exhaust gas discharged from the outlet of the waste heat boiler is about 100-300 ℃, after dust removal, most of the reduction exhaust gas enters a pressure swing adsorption purification device to remove CO in the reduction gas 2 And H 2 And O, improving the reduction potential of the circulating reduction gas, recovering the sensible heat of the reduction exhaust gas part through a heat recovery device, raising the temperature of the circulating reduction gas to 800-1300 ℃ through the reduction exhaust gas of the combustion part, and mixing the circulating reduction gas with the gasification gas produced by a gasification device in a mixing unit. CO in the circulating reducing gas purified by pressure swing adsorption 2 And H 2 0-5% by volume of O, 50-60% by volume of CO and H 2 The volume percentage is 40-50%.
In some embodiments, the exhaust gas is partially reduced by combustion of the combustion device, and the heat of the high-temperature flue gas generated by combustion is transferred to the circulating reduction gas by using a regenerative heat exchanger or a high-temperature-resistant shell-and-tube heat exchanger.
In some embodiments, the iron ore fines have a particle size of 50 to 1000 microns.
In some embodiments, the gasification apparatus may take a variety of forms, and may be a rotary kiln, a moving bed, an entrained bed, a fluidized bed, an ebullating bed, a bubbling bed, a spouted bed, a settling bed, or the like; the reactor structure form of the mineral powder preheating and reducing unit can be a rotary kiln, a moving bed, an entrained flow bed, a fluidized bed, a bubbling bed, a spouted bed, a settling bed and the like. The whole flow direction of the reducing gas and the iron ore powder is counter potential, the heat exchange temperature difference is increased, and the heat and mass exchange efficiency is improved.
In some embodiments, the gas conveying process is powered by an induced draft fan or a forced draft fan.
In some embodiments, the dust removing device may be a cloth bag dust remover, a cyclone separator, an axial flow cyclone separator, an electrostatic dust remover, or the like.
The whole process realizes zero discharge of reduction exhaust gas, most of the reduction exhaust gas enters a pressure swing adsorption purification device to be converted into circulating reduction gas, and a small part of the reduction exhaust gas is sent to a gasification device for temperature adjustment or sent to a combustor for combustion; wherein, the reduction exhaust gas entering the pressure swing adsorption purification device accounts for 85-95% of the total reduction gas volume/reduction exhaust gas volume; the reducing exhaust gas entering the combustor and sent to the gasification device for temperature adjustment accounts for 5-15% of the total reducing gas volume/reducing exhaust gas volume.
Removing most of H in the circulating reducing gas by using a pressure swing adsorption purification device 2 O and CO 2 Removing H according to the design capacity of the gasification device and the requirement on the reducing gas component 2 O and CO 2 Is sent into a gasification device as a gasification agent to participate in gasification reaction to realize H 2 O/CO 2 The quality returns to the circulation, and the external discharge capacity is reduced.
The invention has the innovation point that the characteristics of high reduction potential and high temperature of the reduction exhaust gas in the direct reduced iron system are fully utilized, and the heat/quality of the reduction exhaust gas is recycled, so that the energy consumption is reduced.
Example 1
A system for a spent gas cycle for reduction of gas-based direct reduced iron, comprising: the device comprises a gasification device, a reducing gas mixing unit, a mineral powder reducing unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device, a pressure swing adsorption purification device, a combustion device, a reduced iron powder cooler, a magnetic separation device and a hot pressing device. The device comprises a gasification device, a mixing unit, a mineral powder reduction unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device and a pressure swing adsorption purification device which are sequentially connected, and the mineral powder preheating unit, the mineral powder reduction unit, a reduced iron powder cooler, a magnetic separation device and a hot pressing device are sequentially connected.
A method for recycling reduction exhaust gas of gas-based direct reduced iron based on the system comprises the following steps:
(1) The biomass reacts with oxygen in the gasification unit to produce H-rich 2 The CO gas and the part of the reduction exhaust gas with lower temperature at the outlet of the dust removal device are returned to the gasification device for temperature regulation; in the gasification device, the carbon-rich raw material and the gasifying agent react at a high temperature of 1200-2000 ℃; part of the reduced exhaust gas with lower temperature at the outlet of the waste heat boiler is returned to the gasification device for temperature adjustment, and the temperature range of the gasified gas at the outlet of the final gasification device is 800-1300 ℃.
(2) The gasified gas generated by the gasification device is mixed with the purified and heated circulating reducing gas in the mixing unit to form reducing gas, and the reducing gas enters the mineral powder reducing unit to generate the reduction reaction of iron mineral powder; converting iron ore powder into a direct reduced iron powder product, cooling the direct reduced iron powder product by an iron powder cooler, entering a magnetic separation device to realize primary screening and purification, hot-pressing the product into blocks by a hot-pressing device, and conveying the blocks to the next process; the reduced iron ore powder passes through an iron powder cooler, and the temperature is reduced to about 100 ℃. After the direct reduction reaction occurs, the reducing gas is converted into reducing exhaust gas, and the temperature of the reducing exhaust gas is 700 ℃.
(3) After the direct reduction reaction occurs, the reducing gas is converted into reducing exhaust gas; the reduction exhaust gas enters a mineral powder preheating unit to preheat the iron mineral powder raw material, then enters a heat regeneration device, exchanges heat with the purified circulating reduction gas in the heat regeneration device, reduces the temperature of the reduction exhaust gas to 200 ℃, and then enters a waste heat boiler to recover residual sensible heat energy; reducing the exhaust gas to preheat the iron ore powder raw material to about 500 ℃ at normal temperature.
(4) The reduction exhaust gas discharged from the outlet of the waste heat boiler is dedusted, and most of the reduction exhaust gas enters a pressure swing adsorption purification device to remove H in the reduction gas 2 O and CO 2 The purified circulating reducing gas is obtained, then the circulating reducing gas recovers part of sensible heat of the reducing exhaust gas through a heat recovery device, one part of the reducing exhaust gas is combusted in a combustion device to raise the temperature of the circulating reducing gas from the heat recovery device, and the circulating reducing gas is mixed with the gasified gas produced by a gasification device in a mixing unit; the other part of the reduction exhaust gas enters a gasification device to participate in the temperature adjustment of the gasified gas. And (3) reducing exhaust gas discharged from the ore powder preheating unit is at the temperature of 600 ℃, and is subjected to heat exchange with the purified circulating reducing gas in a heat regeneration device, and the temperature of the reducing exhaust gas is reduced to 200 ℃. The temperature of the reduction exhaust gas discharged from the outlet of the waste heat boiler is 100 ℃. The recycled reducing gas temperature is raised to 800 c by burning a portion of the reducing off-gas.
The gas conveying process is provided with conveying power by a draught fan. The dust removal device removes dust for the cloth bag.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A system for reducing off-gas recycle gas-based direct reduced iron, comprising: the device comprises a gasification device, a mixing unit, a mineral powder reduction unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device, a pressure swing adsorption purification device, a reduced iron powder cooler, a magnetic separation device and a hot pressing device; the device comprises a gasification device, a mixing unit, a mineral powder reducing unit, a mineral powder preheating unit, a heat regeneration device, a waste heat boiler, a dust removal device and a pressure swing adsorption purification device which are sequentially connected, wherein the mineral powder preheating unit, the mineral powder reducing unit, a reduced iron powder cooler, a magnetic separation device and a hot-pressing device are sequentially connected.
2. The system of claim 1, further comprising a combustion device; the inlet of the combustion device is connected with the dust removal device, and the outlet pipeline of the combustion device is connected with the outlet pipeline of the heat regeneration device and converged into a pipeline which is connected with the mixing unit.
3. A method of reducing off-gas recycle gas-based direct reduced iron, performed by the system of claim 1 or 2, the method comprising the steps of:
(1) The carbon-rich raw material reacts with a gasifying agent in a gasifying device to generate H 2 The CO gas and the part of the reduced exhaust gas with lower temperature at the outlet of the waste heat boiler are returned to the gasification device for temperature regulation;
(2) The gasified gas generated by the gasification device is mixed with the purified and heated circulating reducing gas into reducing gas in the mixing unit, and the reducing gas enters the mineral powder reducing unit to generate the reduction reaction of iron mineral powder; converting iron ore powder into a direct reduced iron powder product, cooling the direct reduced iron powder product by an iron powder cooler, entering a magnetic separation device to realize primary screening and purification, hot-pressing the product into blocks by a hot-pressing device, and conveying the blocks to the next procedure;
(3) After the direct reduction reaction occurs, the reducing gas is converted into reducing exhaust gas; the reduction exhaust gas enters a mineral powder preheating unit to preheat the iron mineral powder raw material, then enters a heat regeneration device, exchanges heat with the purified circulating reduction gas in the heat regeneration device, reduces the temperature of the reduction exhaust gas to 200-500 ℃, and then enters a waste heat boiler to recover the residual sensible heat energy;
(4) The reduction exhaust gas discharged from the outlet of the waste heat boiler is dedusted, and most of the reduction exhaust gas enters a pressure swing adsorption purification device to remove H in the reduction gas 2 O and CO 2 Obtaining purified circulating reducing gas, recovering part of sensible heat of the reducing exhaust gas by the circulating reducing gas through a heat recovery device, burning one part of the reducing exhaust gas in a burning device to raise the temperature of the circulating reducing gas discharged from the heat recovery device, and mixing the circulating reducing gas with the gasified gas produced by a gasification device in a mixing unit; the other part of the reduction exhaust gas enters a gasification device to participate in the temperature adjustment of the gasified gas.
4. The method according to claim 3, characterized in that zero discharge of the reduction exhaust gas is realized in the whole process, most of the reduction exhaust gas enters a pressure swing adsorption purification device to be converted into the circulating reduction gas, and a small part of the reduction exhaust gas is sent to a gasification device for temperature adjustment or sent to a combustor for combustion; wherein, the reduction exhaust gas entering the pressure swing adsorption purification device accounts for 85-95% of the total reduction gas volume/reduction exhaust gas volume; the reducing exhaust gas entering the combustor and sent to the gasification device for temperature adjustment accounts for 5-15% of the total reducing gas volume/reducing exhaust gas volume.
5. The method of claim 3, wherein the carbon-rich feedstock comprises coal, biomass; the gasifying agent comprises pure O 2 、H 2 O、CO 2 One or more of;
or, in the gasification device, the carbon-rich raw material and the gasifying agent react at a high temperature of 1200-2000 ℃; part of the reduced exhaust gas with lower temperature at the outlet of the waste heat boiler is returned to the gasification device for temperature adjustment, and the temperature of the gasified gas at the outlet of the final gasification device is 800-1300 ℃;
or, gasifying gasComprises the following components: CO 30-60 vol%, H 2 20-40% by volume of CO 2 0-15% by volume, H 2 The volume percentage of O is 0-10%.
6. The method as claimed in claim 3, wherein the reduced iron ore powder is cooled to 25-700 ℃ by an iron powder cooler;
or, the reducing gas component is: CO accounting for 40 to 60 percent by volume and H 2 30-40% of volume percent, 0-5% of CO2 volume percent and 0-5% of H2O volume percent. The temperature of the reducing gas is 800-1300 ℃;
the reduction reaction temperature is 800-1100 ℃.
7. The method as claimed in claim 3, characterized in that after the direct reduction reaction has taken place, the reducing gas is converted into reducing exhaust gas, the temperature of which is 700-1000 ℃;
or, reducing the exhaust gas to preheat the iron ore powder raw material to 500-800 ℃ at normal temperature;
or the temperature of the reduction exhaust gas discharged from the ore powder preheating unit is 600-900 ℃, heat exchange is carried out between the reduction exhaust gas and the purified circulating reduction gas in a heat regeneration device, and the temperature of the reduction exhaust gas is reduced to 200-500 ℃;
or the temperature of the reduction exhaust gas discharged from the outlet of the waste heat boiler is 100-300 ℃;
or, the temperature of the circulating reducing gas is raised to 800-1300 ℃ by burning part of the reducing exhaust gas.
8. The method of claim 3, wherein the CO in the pressure swing adsorption purified recycle reducing gas 2 And H 2 0-5% of O, 50-60% of CO and H 2 The volume percentage is 40-50%.
9. The method of claim 3, wherein the exhaust gas is partially reduced by combustion using a combustion device, and heat of high-temperature flue gas generated by the combustion is transferred to the circulating reduction gas by using a regenerative heat exchanger or a high-temperature-resistant shell-and-tube heat exchanger.
10. The method according to claim 3, wherein the iron ore powder has a particle size of 50 to 1000 μm; or the gas conveying process is provided with conveying power by an induced draft fan or a blower; or the dust removal device is a cloth bag dust removal device, a cyclone separator, an axial flow type cyclone separator or an electrostatic dust remover.
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| CN102586527A (en) * | 2012-02-29 | 2012-07-18 | 上海大学 | Novel hydrogen-carbon smelting reduction ironmaking process |
| CN102586528A (en) * | 2012-02-29 | 2012-07-18 | 上海大学 | Novel natural gas smelting reduction ironmaking process |
| US20140331821A1 (en) * | 2012-08-22 | 2014-11-13 | Hoffman & Sons Technologies, Llc | Producing of pig iron from iron-containing materials |
| CN108588406A (en) * | 2018-06-15 | 2018-09-28 | 甘肃酒钢集团宏兴钢铁股份有限公司 | A kind of refractory iron ore suspension heating-coal base magnetic roasting process |
| CN111961784A (en) * | 2020-08-31 | 2020-11-20 | 山东大学 | Method and system for reduction reaction of iron ore powder in bubbling bed |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102586527A (en) * | 2012-02-29 | 2012-07-18 | 上海大学 | Novel hydrogen-carbon smelting reduction ironmaking process |
| CN102586528A (en) * | 2012-02-29 | 2012-07-18 | 上海大学 | Novel natural gas smelting reduction ironmaking process |
| US20140331821A1 (en) * | 2012-08-22 | 2014-11-13 | Hoffman & Sons Technologies, Llc | Producing of pig iron from iron-containing materials |
| CN108588406A (en) * | 2018-06-15 | 2018-09-28 | 甘肃酒钢集团宏兴钢铁股份有限公司 | A kind of refractory iron ore suspension heating-coal base magnetic roasting process |
| CN111961784A (en) * | 2020-08-31 | 2020-11-20 | 山东大学 | Method and system for reduction reaction of iron ore powder in bubbling bed |
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