CN117512245A - Self-heating low-carbon direct iron reduction process - Google Patents
Self-heating low-carbon direct iron reduction process Download PDFInfo
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- CN117512245A CN117512245A CN202311276668.4A CN202311276668A CN117512245A CN 117512245 A CN117512245 A CN 117512245A CN 202311276668 A CN202311276668 A CN 202311276668A CN 117512245 A CN117512245 A CN 117512245A
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 160
- 238000010438 heat treatment Methods 0.000 title claims abstract description 74
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 69
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 50
- 238000011946 reduction process Methods 0.000 title claims abstract description 18
- 239000007789 gas Substances 0.000 claims abstract description 167
- 238000000034 method Methods 0.000 claims abstract description 101
- 230000008569 process Effects 0.000 claims abstract description 95
- 239000001257 hydrogen Substances 0.000 claims abstract description 86
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 86
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 83
- 238000005485 electric heating Methods 0.000 claims abstract description 58
- 239000000463 material Substances 0.000 claims abstract description 46
- 239000002994 raw material Substances 0.000 claims abstract description 28
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 27
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims abstract description 5
- 238000006722 reduction reaction Methods 0.000 claims description 43
- 239000008188 pellet Substances 0.000 claims description 38
- 239000000571 coke Substances 0.000 claims description 24
- 239000000428 dust Substances 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 13
- 229910000831 Steel Inorganic materials 0.000 claims description 12
- 239000010959 steel Substances 0.000 claims description 12
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 8
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- 238000005245 sintering Methods 0.000 claims description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 5
- 239000003245 coal Substances 0.000 claims description 5
- 238000005262 decarbonization Methods 0.000 claims description 5
- 230000018044 dehydration Effects 0.000 claims description 5
- 238000006297 dehydration reaction Methods 0.000 claims description 5
- 238000004064 recycling Methods 0.000 claims description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 4
- 239000003345 natural gas Substances 0.000 claims description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 3
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 3
- 238000005261 decarburization Methods 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 239000003034 coal gas Substances 0.000 claims description 2
- 238000002309 gasification Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- 239000004576 sand Substances 0.000 claims description 2
- 239000010902 straw Substances 0.000 claims description 2
- 238000003786 synthesis reaction Methods 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 29
- 238000006243 chemical reaction Methods 0.000 abstract description 25
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 230000008901 benefit Effects 0.000 abstract description 6
- 239000011343 solid material Substances 0.000 abstract description 6
- 230000009467 reduction Effects 0.000 description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 19
- 239000001301 oxygen Substances 0.000 description 19
- 229910052760 oxygen Inorganic materials 0.000 description 19
- 238000002485 combustion reaction Methods 0.000 description 6
- 230000005611 electricity Effects 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000010248 power generation Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000004146 energy storage Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052595 hematite Inorganic materials 0.000 description 3
- 239000011019 hematite Substances 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 3
- 238000005272 metallurgy Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 238000004880 explosion Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 2
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- CUPCBVUMRUSXIU-UHFFFAOYSA-N [Fe].OOO Chemical compound [Fe].OOO CUPCBVUMRUSXIU-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012256 powdered iron Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000006057 reforming reaction Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/02—Making spongy iron or liquid steel, by direct processes in shaft furnaces
-
- 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
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0086—Conditioning, transformation of reduced iron ores
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/12—Making spongy iron or liquid steel, by direct processes in electric furnaces
-
- 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
- C21B2100/62—Energy conversion other than by heat exchange, e.g. by use of exhaust gas in energy production
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention provides a self-heating low-carbon direct iron reduction process, which is used for preparing reduced iron or sponge iron, and is characterized in that iron raw materials containing ferric oxide are prereduced in a preheating section of an electric heating shaft kiln, then the iron raw materials or solid materials (hereinafter referred to as solid materials) obtained by changing the iron raw materials in the heating process are directly electrified in the heating section of the electric heating shaft kiln through a power electrode, and the materials are heated through the resistance heating of a solid material pile in the heating section and the reaction heat is provided for the endothermic reaction of reducing the ferric oxide by hydrogen-rich gas. The invention has the advantages of simple process flow, low carbon emission, low investment and high production capacity.
Description
Technical Field
The invention belongs to the field of ferrous metallurgy, and relates to a production process of reduced iron or sponge iron.
Background
The steel industry production value of China is about 5% of the GDP of China, and the steel yield is about half of the world steel yield. At present, the steelmaking process in China is mainly a long-flow process of a blast furnace-converter, and the carbon emission is huge. The carbon emission of the chinese steel industry is about 15% of the national carbon emission. In the blast furnace ironmaking process, coke and coal are used, and the carbon emission of the coke and the coal accounts for 60-70% of the carbon emission in the steel industry. I.e. the iron-making process accounts for approximately 10% of the total national carbon emissions. It can be seen that the emission reduction in the iron and steel industry plays a significant role. Wherein the emission reduction of the ironmaking process occupies a larger specific gravity.
The statistical data of 2022-year national electric power industry released by the national energy agency recently show that the national cumulative installed power generation capacity is about 25.6 hundred million kilowatts by the end of 12 months in 2022, which is increased by 7.8% in a homonymy. In 2022, the national renewable energy general-purpose installation machine exceeds 12 million kw, and the installation of hydroelectric, wind-powered, solar-powered, biomass-powered (the four terms are hereinafter referred to as green electricity) machines is the first world. Wherein, the installed capacity of wind power is about 3.7 hundred million kilowatts (370 Gw), and the same ratio is increased by 11.2%; the installed capacity of the solar power generation is about 3.9 hundred million kilowatts, and the same ratio is increased by 28.1 percent. Because wind power and solar power generation are unstable and are not synchronous with the peak-valley of power demand, energy storage for wind power and photovoltaic is also a huge problem. In recent years, hydrogen production by utilizing wind power and photovoltaic water electrolysis is vigorous. Biomass utilization may also skip the power generation step to directly produce synthesis gas and hydrogen. Hydrogen is used as an energy storage medium, has large capacity, does not attenuate long-time energy storage, can be also used in chemical and metallurgical industries, and has great advantages. The hydrogen gas obtained by these process routes has a new name, namely green hydrogen.
Therefore, an iron-making process using green electricity as a heat source and green hydrogen as a reducing agent has basic conditions of energy and raw materials.
The current hydrogen metallurgy iron making process has a hydrogen-rich reduction blast furnace process and a gas-based (hydrogen) direct reduction process.
The hydrogen-rich process blows coke oven gas or other gases into the blast furnace, the hydrogen in the coke oven gas has strong reducing capability, and the inlet amount of the coke oven gas determines the economic benefit and the carbon reduction effect of the process. The higher the percentage of coke oven gas is, the better the carbon reduction effect is. H in coke oven gas 2 The reaction for reducing ferric oxide is an endothermic reaction, more oxygen-enriched gas needs to be blown to carry out thermal compensation as the reduction process of hydrogen is more involved, and the increase of the oxygen-enriched concentration strengthens the combustion of carbon in a swirling zone, thereby being beneficial to the rapid reduction of furnace burden. In 2020, baowu carried out a hydrogen-rich carbon circulating oxygen blast furnace process experiment on eight-one steel, and the decarbonized coal gas was fed into the hydrogen-rich carbon circulating blast furnace, so that the carbon emission was reduced by 30% compared with the conventional blast furnace. According to the experiment of the plum steel No. 2 blast furnace, the hydrogen-rich blast furnace process for injecting coke oven gas can reduce carbon emission by about 10%. The hydrogen-rich reduction blast furnace process is an improvement on the existing long-flow process, and has limited carbon reduction effect.
The hydrogen direct reduction process or gas-based direct reduction process generally employs a shaft furnace (also referred to as a shaft kiln, shaft kiln) device, which does not require coke and coking links. The short-flow steelmaking process is characterized in that iron concentrate is formed into green pellets with uniform granularity (about 10mm in diameter) and certain strength, the green pellets are roasted in a strong oxidizing atmosphere of 1150-1300 ℃ (optimal 1200 ℃), decomposition, oxidization, desulfurization and other solid-phase reactions are completed, magnetite is converted into hematite, and high-strength oxidized pellets are obtained. The roasting process of the oxidized pellets adopts natural gas as fuel, and the consumption of the natural gas per ton of oxidized pellets is about 32m 3 . And then reducing the oxidized pellets by hydrogen (green hydrogen) at high temperature in a vertical kiln or a rotary kiln to obtain direct reduced iron (sponge iron). The process can theoretically reduce carbon emission of more than 90% in the ironmaking process.
In the hydrogen-rich reduction blast furnace process, as the hydrogen is reduced to hematite at high temperature to perform an endothermic reaction, oxygen-rich gas is introduced when the hydrogen utilization rate is increased, and heat is supplied by the combustion reaction. When adopting the gas-based direct reduction ironmaking process, the heat supply for the reaction becomes a serious problem. 2021, month 5, zhang Xuan technology starts to build 120 ten thousand tons/year hydrogen metallurgy demonstration project at the open-door, which is a gas-based direct reduction iron-making process. The project utilizes the advantages of the national grade renewable energy demonstration area of Zhangkou to develop a new hydrogen reduction process, can replace the traditional blast furnace carbon metallurgy process, and can reduce the carbon emission by 60 percent. In principle, the project can adopt green electricity and green hydrogen to achieve 98% carbon emission reduction. It is estimated that coke oven gas is used as a reducing agent, and a large amount of carbon-containing gas (CO and methane account for about 20 mol%) is contained in the coke oven gas, and that part of methane, CO or hydrogen and oxygen in the raw material gas is combusted to supply heat for the reaction in the reaction process due to the heat supply for the reaction of reducing hematite with hydrogen. In the process flow of this item, hydrogen or coke oven gas and oxygen are heated to about 950 ℃ in order to supply heat to the reduction reaction. However, the sensible heat of the oxidized pellets and the gas entering the shaft kiln is far less than the latent heat of reaction required for the reaction, so that an excessive amount of hydrogen-rich raw material gas is required to enter the shaft kiln, and the power of the gas circulation process and the burden of the purification process are increased. And the hydrogen or the hydrogen-rich gas is heated to such a high temperature, so that the safety is very low. Further, the combustion reaction of oxygen does not necessarily occur at the site of the reduction reaction of iron oxyhydroxide. The addition of additional oxygen, which wastes reducing gas, produced water or CO2, is also detrimental to the reduction of iron oxide. The rate of occurrence of the reduction reaction and the specific area in the shaft kiln reactor are difficult to control. It should be noted that, after the hydrogen-rich gas enters the reaction system, the hydrogen therein reduces the iron oxide to generate water, and the water and CO and/or methane are reformed to generate hydrogen under the catalysis of the generated reduced iron, so that the hydrogen is mainly involved in the reduction reaction.
In order to solve the problem of supplying heat to the endothermic reduction reaction, one large apparatus in korea adopts a process in which a plurality of fluidized beds are connected in series. The process requires not only that the raw material gas is brought into heat for the endothermic reduction reaction, but also that the flow rate of the gas is large enough to fluidize the powdered iron ore raw material, thus requiring a large flow rate of the gas in far excess of the reduction equivalent required for the reduction reaction. The process scheme needs to perform procedures such as temperature rising, dust removing, conveying, temperature reducing, circulation and the like on a large amount of high-temperature gas, and has the advantages of high energy consumption, low reliability and poor safety.
In summary, since the production capacity of the iron and steel industry is huge, the hydrogen-rich gas reduction iron-making process is also planned to a scale with a annual production capacity of more than 50 ten thousand tons. Heating and heat transfer are significant challenges for large scale endothermic reactions, whether using shaft or rotary kilns or other forms of reactors. There is a great safety risk and energy waste in heating hydrogen or hydrogen-rich gas. Oxygen is introduced into a reducing gas such as hydrogen or a hydrogen-rich gas, and there is a risk of explosion.
Disclosure of Invention
The invention aims to provide an iron-making process for supplying heat required by the reaction for the endothermic reaction of reducing iron oxide by hydrogen-rich gas with a scale of hundreds of thousands of tons or more, which avoids preheating the hydrogen-rich gas entering a reduction reactor to high temperature, avoids introducing oxygen into flammable and explosive high-temperature gas such as hydrogen or coke oven gas, greatly improves the utilization rate of a hearth of the reactor, and finally ensures that the hydrogen-rich gas reduction low-carbon iron-making process can be realized on the premise of large-scale, low cost and high safety requirements.
The purpose of the invention is realized in the following way: the iron raw material or solid material (hereinafter referred to as material) generated in the reaction process is directly electrified by a power electrode in the electric heating shaft kiln, and the material is heated and heat is provided for endothermic reaction by means of heating of the material by the resistance of the material pile under the action of current. And (5) treating the gas withdrawn from the electric heating shaft kiln.
The purpose of the invention is realized in the following way:
the self-heating low-carbon direct iron reduction process is characterized in that iron raw materials containing iron oxide are fed into an electric heating shaft kiln to be heated, and the iron oxide and hydrogen-rich gas undergo a reduction reaction in the heating process to obtain reduced iron, and the process is characterized in that: the process consists of an electric heating reduction process and a tail gas treatment process; the iron raw materials are as follows: iron-containing dust, sea sand, lump iron ore, sintered iron ore, pellets formed by iron ore powder or oxidized pellets obtained by oxidizing roasting, and pellets formed by ferric oxide in the iron and steel industry. The technical scheme of the invention has no special requirements on the types of raw ores, the occurrence forms or crystalline phases of iron in the ores, the common impurity types in the ores and the occurrence forms thereof, but has certain requirements on the iron content in the ores, and the total average total iron content of various iron-containing raw materials fed into a kiln is required to be more than 40%, preferably more than 45%. The electric heating reduction process comprises the following steps: the method comprises the steps that the iron raw materials and/or materials (hereinafter referred to as materials) obtained by changing the iron raw materials in the heating section of the electric heating shaft kiln are directly electrified through a power electrode, a material pile heats by self resistance, and the materials sequentially pass through a preheating section, a heating section and a cooling section from top to bottom in the electric heating shaft kiln and are discharged; the highest temperature of the material passing through the electric heating shaft kiln is not lower than 600 ℃; the material is preheated in the preheating section by the gas withdrawn from the heating section and partially prereduced by the reducing gas in the gas phase so that its electrical conductivity is improved; iron oxide is reduced by hydrogen-rich gas in a heating section to generate direct reduced iron or sponge iron; the hydrogen-rich gas enters the electric heating shaft kiln, sequentially passes through a cooling section, a heating section and a preheating section of the electric heating shaft kiln from bottom to top, and then is withdrawn from the electric heating shaft kiln; the hydrogen-rich gas is preheated by heat exchange with the materials withdrawn from the heating section in the cooling section of the electric heating shaft kiln; the gas withdrawn from the electric heating shaft kiln enters a tail gas treatment process; the air pressure of the gas in the electric heating shaft kiln is less than 2MPa.
Further, the electric heating shaft kiln comprises: the hearth heating section is provided with a plurality of electrodes of a heating power supply, voltage is applied to the heated material through the electrodes so as to feed current into the heated material, and the heated material is heated by utilizing resistance heating of the heated material accumulated in the heating section; the electric heating shaft kiln is also provided with a preheating section and a cooling section; the material sequentially passes through a preheating section, a heating section and a cooling section in the electric heating shaft kiln; the electric heating shaft kiln is characterized in that a gas inlet is arranged at one end of the cooling section, and a gas outlet is arranged at one end of the preheating section. The heating power supply electrode of the electric heating shaft kiln can be embedded on the hearth wall, and the current path passes through the materials in the heating section.
Further, the hydrogen-rich gas is gas, shale gas, coal bed gas, coke oven gas, water gas, blast furnace gas, synthetic gas (the synthetic gas is generally obtained by reforming coal, natural gas, oil or hydrocarbon with oxygen and/or water, and contains hydrogen and CO), methanol, ammonia, straw gasification gas, and heaven gasOne or more of the gases, or hydrogen is added to the gases. Methane or other carbon-containing components of these gases undergo a reforming reaction with water produced during the reaction to produce hydrogen and CO and/or CO 2 The reducing component of the reduction reaction with iron ore is therefore mainly hydrogen.
Further, the tail gas treatment process is that the tail gas is mixed with fresh hydrogen-rich gas after dust removal, dehydration and decarburization, and then enters an electric heating shaft kiln for recycling. The decarbonization process is to remove carbon dioxide and/or partial carbon monoxide in the tail gas. Conventional triethanolamine decarbonization processes may be used. The dust removal can be realized by adopting a cyclone separator and/or a cloth bag dust remover, or can be realized by adopting water spraying, and meanwhile, dust and a large amount of water vapor in the tail gas are removed. When ammonia or nitrogen is present in the feed gas, a denitrification process is required during the tail gas treatment. Of course, the denitrification can adopt the technological methods of carbon molecular sieve pressure swing adsorption and the like.
Or the hydrogen-rich gas is hydrogen. Photovoltaic and wind power can produce significant amounts of green hydrogen. At present, about 45-55 kwh of electricity is consumed for electrolysis production of each kilogram of hydrogen. When the hydrogen-rich gas is pure hydrogen, the tail gas treatment process is to remove dust and dehydrate the tail gas withdrawn from the electric heating shaft kiln, and then the tail gas is mixed with fresh hydrogen and enters the electric heating shaft kiln for recycling.
The electric heating vertical kiln equipment is adopted as a reactor for the reduction reaction, so that gas phase and solid phase materials are in full contact, and the self-heating mode of directly electrifying the solid phase materials is adopted, and the materials in the heating section are heated and the reduction reaction can be timely supplemented with heat, so that the heat required by the reaction and sensible heat carried by the gas entering the electric heating vertical kiln are decoupled, the quantity and the temperature of the gas entering the electric heating vertical kiln are not particularly required, the air inflow can be further greatly reduced, and the air inflow is only determined according to the requirement of the reduction reaction. After the air inflow of the hydrogen-rich gas is greatly reduced, the load of the tail gas treatment process is greatly reduced, the tail gas can be not recycled, and the tail gas treatment process is simplified into the tail gas combustion. The combustion process can be used for providing heat for sintering of iron ore pellets and particle ores, producing oxidized pellets or sintered ores, and further reducing carbon emission in the iron-making process. The combustion process can also be used for preheating the hydrogen-rich gas before entering the electric heating shaft kiln so as to reduce the electric quantity consumed by the electric heating of the electric heating shaft kiln.
Compared with the prior art, the invention has the following advantages:
compared with the traditional blast furnace ironmaking process, the carbon emission of the ironmaking process can be reduced by more than 50 percent.
When green hydrogen is used as the reducing agent, carbon emissions can be reduced by more than 90%. When a small amount of hydrogen tail gas is combusted into sintered oxidized pellets and/or sintered ores, zero carbon emission can be achieved by the iron-making process. And simplifying the tail gas treatment process.
Compared with the existing direct reduction process of the gas-based shaft furnace, the raw material oxidized pellets are not bonded by using cement spraying, so that the equipment investment is reduced, the running cost is reduced, and the subsequent deslagging load is reduced.
Compared with the existing gas-based shaft furnace direct reduction process, the technical scheme of the invention can control a definite reaction area, control a heating section to be a main reaction area, and in the reaction area, the material temperature is not rapidly reduced along with the reaction, so that the utilization rate of a hearth of the shaft furnace is greatly improved.
Compared with the existing gas-based shaft furnace direct reduction process, the technical scheme of the invention does not need to bring sensible heat into the raw gas of the high-temperature hydrogen-rich gas to supply heat for reaction, so that the excessive hydrogen-rich gas can be reduced as much as possible on the premise of meeting the reduction degree of iron ores, and the load of tail gas treatment is greatly reduced.
Compared with the prior gas-based shaft furnace process, the iron ore adopted by the process has the iron grade of 66-69%. And domestic high-grade iron ores are imported. And the reserves of the high-grade iron ores in the world only account for about 3 percent of the reserves of the whole iron ores. Experiments show that the direct reduced iron process of the invention can use iron ore raw materials with iron content as low as 45%. Has great significance for the utilization of low-grade iron ores.
Compared with the existing gas-based direct reduction process, the method does not need to add oxygen enrichment or oxygen into the inlet gas to enable the inlet gas to burn for reaction heat supply, and does not need to preheat the raw material gas at high temperature. The process and the equipment are simplified, the safety is improved, the equipment investment is reduced, and the running cost is reduced.
In a word, the invention opens up a technical route with low carbon emission, high safety, low investment, low running cost, high reliability and feasible technology for the low-carbon iron-making process taking hydrogen-rich gas as the reducing agent.
Detailed Description
Drawings
The following describes a specific technical solution of the present invention with reference to the drawings and examples.
FIG. 1 is a block diagram of the process of self-heating low-carbon direct reduced iron of example 1.
Fig. 2 is a block diagram of the process of self-heating low-carbon direct reduced iron of example 2.
Example 1
The embodiment adopts a coke oven gas reduction low-carbon ironmaking process, and a process flow diagram is shown in figure 1.
The oxidized pellets with the iron content of about 54% are used as iron raw materials, the iron raw materials are not preheated, the iron raw materials directly enter a feeding hopper of the electric heating shaft kiln, the oxidized pellets enter a preheating section of the electric heating shaft kiln along with downward running of solid materials, heat exchange is carried out between the oxidized pellets and high-temperature gas (containing water vapor generated by reduction reaction) from the heating section of the shaft kiln in the preheating section, and when the oxidized pellets are preheated to about 650 ℃, the oxidized pellets are partially reduced, so that conductivity is obtained. After the oxidized pellets move to the heating section, an electrode of a heating power supply is arranged on the wall of the kiln chamber of the heating section, current is fed into materials in the heating section, the materials are heated by the current, and the temperature is further increased to 950-1100 ℃. The iron oxide in the oxidized pellet in the heating section is reduced to direct reduced iron. With the increase of the reduction degree, the material resistance is reduced, the reduction reaction is also reduced, and the heat demand is also reduced correspondingly. The voltage of the heating power supply is reduced, and the heating value is reduced. The materials discharged from the heating section are subjected to heat exchange with the normal-temperature or low-temperature coke oven gas entering the kiln, so that the temperature of the materials is reduced, the coke oven gas is preheated, and the coke oven gas has a higher temperature when entering the heating section.
The gas withdrawn from the feed end of the electrothermal shaft kiln, with dust and a large amount of water and CO 2 Which is cleaned in a dust removal and dehydration process and removes CO therein through a decarbonization process 2 . The dust removal and dehydration process adopts circulating water to spray at first, and dust and most of water in the circulating gas are removed. And then passing through molecular sieve or condensing and drying. The obtained circulating gas and fresh coke oven gas enter the electric heating shaft kiln basically at normal temperature.
Compared with the existing most advanced gas-based reduction iron-making process (Zhang Xuan technology 120 ten thousand tons/year iron-making process), the process of the embodiment has fewer working procedures of oxygen production (or oxygen enrichment), pellet oxide spray mud, preheating of the inlet gas before entering a kiln, oxygen enrichment or oxygen addition to the inlet gas, and the like. The embodiment has simple process and high safety, avoids high-temperature preheating of the coke oven gas, and avoids the safety risk of explosion and the like caused by adding oxygen or oxygen enrichment into the combustible gas such as the coke oven gas. And the reduction reaction is fully carried out in the whole heating section, so that the kiln chamber utilization rate is greatly improved. The process route of the invention greatly reduces the investment cost and the running cost. The embodiment and the invention open up a safe and reliable, economical and feasible technical route for a large-scale green hydrogen-rich gas low-carbon iron-making process.
Example 2
The embodiment adopts a green-hydrogen green-electricity reduction zero-carbon iron-making process, and a process flow block diagram is shown in figure 2.
The oxidized pellets with the iron content of about 54% are used as iron raw materials, the iron raw materials are not preheated, the iron raw materials directly enter a feeding hopper of the electric heating shaft kiln, the oxidized pellets enter a preheating section of the electric heating shaft kiln along with downward running of solid materials, heat exchange is carried out between the oxidized pellets and high-temperature gas (containing water vapor generated by reduction reaction) from the heating section of the shaft kiln in the preheating section, and when the oxidized pellets are preheated to about 650 ℃, the oxidized pellets are partially reduced, so that conductivity is obtained. After the oxidized pellets move to the heating section, an electrode of a heating power supply is arranged on the wall of the kiln chamber of the heating section, current is fed into materials in the heating section, the materials are heated by the current, and the temperature is further increased to 950-1150 ℃. The iron oxide in the oxidized pellet in the heating section is reduced to direct reduced iron. With the increase of the reduction degree, the material resistance is reduced, the reduction reaction is also reduced, and the heat demand is also reduced correspondingly. The voltage of the heating power supply is reduced, and the heating value is reduced. The material discharged from the heating section exchanges heat with normal-temperature or low-temperature hydrogen entering the kiln, the temperature of the material is reduced, coke oven gas is preheated, and the coke oven gas has a higher temperature when entering the heating section. In the cooling section, preheated hydrogen can also react with high-temperature materials, the reduction degree of iron is further improved, and the metallization rate of iron in the materials discharged from the kiln reaches more than 95%.
The hydrogen feeding amount of the shaft kiln is controlled so that the hydrogen is 10-30% excessive compared with the reduction equivalent required by the oxidized pellets entering the electric heating shaft kiln at the same time.
The gas withdrawn from the feed end of the electrothermal shaft kiln, with dust and a large amount of water. The tail gas treatment process adopts circulating water to spray, so that dust and most of water in the tail gas are removed. And then the mixture is conveyed to an oxidized pellet sintering process through a Roots blower for burning sintered pellets or granular iron ore, so that the carbon-free sintering of the oxidized pellets or the sintered ore is realized. The process not only simplifies the tail gas treatment process, but also eliminates carbon emission in the sintering process of the oxidized pellets.
Green electricity is adopted in the auxiliary process by combining the heating of the electric heating shaft kiln, and zero carbon emission in the iron-making process is realized in the embodiment.
According to the technical scheme, not only can iron ore raw materials with higher iron content be adopted, but also part of kinds of ores with iron content as low as 40% can be adopted as shown by laboratory-scale principle verification experiments; the technical scheme of the invention can be adopted for determining the dust of iron ore with iron content higher than 45% or other iron and steel industries.
Claims (10)
1. The self-heating low-carbon direct iron reduction process is characterized in that iron raw materials containing iron oxide are fed into an electric heating shaft kiln to be heated, and the iron oxide and hydrogen-rich gas undergo a reduction reaction in the heating process to obtain reduced iron, and the process is characterized in that: the process consists of an electric heating reduction process and a tail gas treatment process;
the iron raw materials are as follows: one or more of iron-containing dust, sea sand, lump iron ore, sintered iron ore, pellets formed by iron ore powder or oxidized pellets obtained by oxidizing roasting and pellets formed by ferric oxide in the iron and steel industry;
the electric heating reduction process comprises the following steps: the method comprises the steps that the iron raw materials and/or materials (hereinafter referred to as materials) obtained by changing the iron raw materials in the heating section of the electric heating shaft kiln are directly electrified through a power electrode, a material pile heats by self resistance, and the materials sequentially pass through a preheating section, a heating section and a cooling section from top to bottom in the electric heating shaft kiln and are discharged; the highest temperature of the material passing through the electric heating shaft kiln is not lower than 600 ℃; the material is preheated in the preheating section by the gas withdrawn from the heating section and partially prereduced by the reducing gas in the gas phase so that its electrical conductivity is improved; iron oxide is reduced by hydrogen-rich gas in a heating section to generate direct reduced iron or sponge iron;
the hydrogen-rich gas enters the electric heating shaft kiln, sequentially passes through a cooling section, a heating section and a preheating section of the electric heating shaft kiln from bottom to top, and then is withdrawn from the electric heating shaft kiln; the hydrogen-rich gas is preheated by heat exchange with the materials withdrawn from the heating section in the cooling section of the electric heating shaft kiln; the gas withdrawn from the electric heating shaft kiln enters a tail gas treatment process;
the air pressure of the gas in the electric heating shaft kiln is less than 2MPa.
2. The self-heating low-carbon direct reduced iron process according to claim 1, wherein: the electric heating shaft kiln comprises: the hearth heating section is provided with a plurality of electrodes of a heating power supply, voltage is applied to the heated material through the electrodes so as to feed current into the heated material, and the heated material is heated by utilizing resistance heating of the heated material accumulated in the heating section; the electric heating shaft kiln is also provided with a preheating section and a cooling section; the material sequentially passes through a preheating section, a heating section and a cooling section in the electric heating shaft kiln; the electric heating shaft kiln is characterized in that a gas inlet is arranged at one end of the cooling section, and a gas outlet is arranged at one end of the preheating section.
3. The self-heating low-carbon direct reduced iron process according to any one of claims 1 to 2, characterized in that: the hydrogen-rich gas is one or more of coal gas, shale gas, coal bed gas, coke oven gas, blast furnace gas, water gas, synthesis gas, methanol, ammonia gas, straw gasification gas and natural gas, or hydrogen is added into the above gases.
4. A self-heating low-carbon direct reduced iron process according to claim 3, characterized in that: the tail gas treatment process is that the tail gas is mixed with fresh hydrogen-rich gas after dust removal, dehydration and decarburization, and then enters an electric heating shaft kiln for recycling; the decarbonization process is to remove carbon dioxide and/or partial carbon monoxide in the tail gas.
5. A self-heating low-carbon direct reduced iron process according to claim 3, characterized in that: the tail gas treatment process is that the tail gas is mixed with fresh hydrogen-rich gas after dust removal, dehydration, decarburization and denitrification, and then enters an electric heating shaft kiln for recycling; the decarbonization process is to remove carbon dioxide and/or partial carbon monoxide in the tail gas; the denitrification process is to remove nitrogen in the tail gas.
6. The self-heating low-carbon direct reduced iron process according to any one of claims 1 to 2, characterized in that: the hydrogen-rich gas is hydrogen.
7. The self-heating low-carbon direct reduced iron process according to claim 6, wherein: the tail gas treatment process is to remove dust and dewater the tail gas withdrawn from the electric heating shaft kiln, and then mix the tail gas with fresh hydrogen to enter the electric heating shaft kiln for recycling.
8. The self-heating low-carbon direct reduced iron process according to any one of claims 1 to 2, characterized in that: the tail gas treatment process is to burn the tail gas.
9. The self-heating low-carbon direct reduced iron process according to claim 8, wherein: the tail gas treatment process is to burn the tail gas and is used for sintering the oxidized pellets and/or sintering iron ore.
10. The self-heating low-carbon direct reduced iron process according to claim 8, wherein: the tail gas treatment process is to burn the tail gas and is used for preheating the hydrogen-rich gas before entering the electric heating shaft kiln.
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| CN202311024318 | 2023-08-14 | ||
| CN202311024066 | 2023-08-14 | ||
| CN2023110243189 | 2023-08-14 | ||
| CN202311024066X | 2023-08-14 |
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