CN112662830A - Method for pre-heat exchanging hydrogen by utilizing direct reduction iron furnace top gas - Google Patents
Method for pre-heat exchanging hydrogen by utilizing direct reduction iron furnace top gas Download PDFInfo
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- CN112662830A CN112662830A CN202011571959.2A CN202011571959A CN112662830A CN 112662830 A CN112662830 A CN 112662830A CN 202011571959 A CN202011571959 A CN 202011571959A CN 112662830 A CN112662830 A CN 112662830A
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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
- C21B13/02—Making spongy iron or liquid steel, by direct processes in shaft furnaces
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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
Abstract
The invention relates to a method for pre-heat exchanging hydrogen by directly reducing top gas of an iron furnace, which is to cool the top gas to less than 180 ℃ and pressurize the top gas to more than 9kg, and to exchange H by CO2Technical obtaining of H2Converting hydrogen with the content of more than or equal to 96% at normal temperature, exchanging heat with furnace top gas, heating to 330-480 ℃, heating to 400-600 ℃ by adopting a partial oxidation method, adding the heated gas into high-temperature crude gas of a molten iron bath to obtain the hydrogen-carbon ratio of more than 1.1, the temperature of 630-1050 ℃ and the oxidation degree (H)2O+CO2) Less than or equal to 3 percent of recycled reducing gas is used for introducing into the direct reduced iron shaft furnace to produce direct reduced iron. The invention utilizes the furnace top gas and the conversion hydrogen to exchange heat, further improves the temperature of the conversion hydrogen by a partial oxidation method, fully utilizes the heat of the furnace top gas of the direct reduced iron, the heat generated by the conversion reaction and the water vapor in the furnace top gas, and improves the utilization efficiency of energy sources.
Description
Technical Field
The invention belongs to the technical field of direct reduced iron, and relates to a method for smelting direct reduced iron by utilizing high-temperature raw gas of molten iron bath, in particular to a method for converting top gas of direct reduced iron into H through CO in coal chemical industry2Then, normal temperature is obtainedThe method of changing hydrogen and exchanging heat with top gas. The method can further fully utilize the heat of the top gas of the directly reduced iron, the heat generated by the conversion reaction and the heat generated by the compressed gas, and improve the utilization efficiency of energy.
Background
The existing technology for reducing iron by natural gas and coke oven gas in a shaft furnace, such as MIDREX, HYL-III, CSDRI, CTR, WTY-DRI and the like, can not leave CH4A reforming furnace and a reducing gas reheating process. For example, typical MIDREX technology preheats the reducing gas to 600 ℃ in a tube furnace and then CH in a second stage reducing gas reformer4Cracking into (H)2And + CO), heating the reducing gas to 840-900 ℃, and feeding the reducing gas into the direct reduced iron shaft furnace for producing direct reduced iron.
In contrast, all the iron bath furnaces and coal gas production from molten iron bath in coal-based molten reduced iron in the world are quite silent after the research and experiment for more than 40 years, except for His melt molten reduced iron. The main reasons for this are: 1. the gas production is large and reaches 2000m3(ii) a/t coal; 2. the temperature of the raw gas is as high as 1200-1700 ℃, and the raw gas contains a large amount of dust and is difficult to utilize; 3. the erosion speed of the refractory material of the furnace lining is too fast and reaches 19kg/t coal; 4. the energy consumption is higher than that of blast furnace ironmaking, and the blast furnace ironmaking cannot compete with the blast furnace.
In 1982-1983, Japan and Sweden collaborated, and the research was carried out on the CIG molten reduced iron method of Sweden Imperial academy of Industrial science. Wherein, the research of iron-smelting and steel-making process is emphasized by the research group of the Japanese, and the research of coal gasification method is emphasized in Sweden, and the obtained crude gas comprises the following components: 67-69% CO, H2 28%～29%，CO2≤1.4，N2< 4%, and a small amount of sulfur. The target product of CIG molten reduced iron is molten iron, and the test is not progressed after being frustrated.
CN 101787408A discloses a method for producing direct reduced iron by using sensible heat of raw gas, which uses a direct reduction shaft furnace as a high-temperature dust remover of a raw gas particle bed, uses iron ore (including iron ore coal pellets, iron oxide pellets and coal-coated iron ore powder pellets) in the shaft furnace as dust removing particles of a moving particle bed, co-produces the direct reduced iron in the process of removing dust from the high-temperature raw gas, and simultaneously completes 5 functions of using the sensible heat, reducing the iron, reducing the temperature, removing the dust and reducing the gas pressure in the reduction shaft furnace. The patent purifies the top gas produced by the reduction shaft furnace and uses the top gas as raw material gas or fuel gas for producing chemical products, thereby effectively improving the comprehensive utilization efficiency of coal energy. According to the method, the coal gas and the direct reduced iron shaft furnace are separately arranged, the coal gas adopts coal with high ash melting point and softening point, iron minerals and other minerals with low softening points are avoided from being contained in the coal gas, and the problems of bonding and blocking caused by the minerals with low softening points can be solved.
However, the raw gas in the patent is not recycled, only sensible heat of the raw gas is utilized for 1 time, and the top gas after producing the direct reduced iron is purified to be used as a fuel gas and a chemical raw material gas, so that residual heat and residual gas are not fully utilized.
CN 111218535A discloses a method for producing direct reduced iron by heating circulating reducing gas from molten iron bath coal gas, which is to smelt direct reduced iron by utilizing the sensible heat of the molten iron bath coal gas, and the waste heat recovery steam of furnace top gas of the direct reduced iron is used for converting CO into H from the furnace top gas2。
Disclosure of Invention
The invention aims to provide a method for pre-heating and exchanging hydrogen by using coal gas at the top of a direct reduced iron furnace so as to improve the heat energy utilization efficiency in the production process of the direct reduced iron to the maximum extent.
The method for pre-heat conversion of hydrogen by using the top gas of the direct reduced iron furnace is based on that the top gas of the direct reduced iron furnace is used as water gas and can convert H by using CO in the coal chemical industry2The process flow transforms the hydrogen to obtain transformed hydrogen which is returned to the direct reduced iron shaft furnace for producing direct reduced iron, and the method comprises the following steps:
1) producing 350-500 ℃ top gas with the pressure of 1-5 kg from the top of the direct reduced iron shaft furnace;
2) dedusting the top gas, then feeding the top gas into a heat exchanger, exchanging heat with normal-temperature conversion hydrogen, cooling to less than 180 ℃, pressurizing to more than 9kg, feeding the top gas into a flow of converting the top gas into the hydrogen, and obtaining H by adopting conventional CO conversion and gas separation technologies2The content is more than or equal to 96 percent, the pressure is 4-8 kg, and the degree of oxidation(CO2+H2O) is less than or equal to 3 percent, and hydrogen is transformed at the normal temperature of less than 25 ℃;
3) the normal-temperature transformed hydrogen enters a heat exchanger, exchanges heat with furnace top gas, and is heated to 330-480 ℃ to obtain medium-temperature transformed hydrogen;
4) adding less than 3% of O into the medium-temperature conversion hydrogen2Or from CH4Or H2High temperature gas after combustion to obtain oxidation degree (CO)2+H2O) is less than or equal to 6 percent, and hydrogen is transformed at the medium-high temperature of 400-600 ℃;
5) adding the obtained medium-high temperature conversion hydrogen into high-temperature raw gas of molten iron bath coal gas production gas with the temperature of 1400-1600 ℃ and the pressure of 4-5 kg, and heating the added medium-high temperature conversion hydrogen by using the high-temperature raw gas to obtain the medium-high temperature conversion hydrogen with the hydrogen-carbon ratio of more than 1.1, the temperature of 630-1050 ℃, and the oxidation degree (H)2O+CO2) Introducing less than or equal to 3% of furnace-entering circulating reducing gas into the direct reduced iron shaft furnace, providing heat and reducing agent to produce direct reduced iron, and producing furnace top gas with the temperature of 350-500 ℃ and the pressure of 1-5 kg from the furnace top;
the above processes are circularly carried out.
In the method of the invention, the percentage content is volume percentage content.
The method for exchanging hydrogen by utilizing the preheating of the top gas of the direct reduction iron furnace further utilizes the heat of the top gas of the direct reduction iron furnace, forms H after multiple times of CO exchange and heat exchange and conventional necessary desulfurization and decarburization treatment2The hydrogen is changed at normal temperature when the content is increased to more than 96 percent. Therefore, the method not only utilizes all sensible heat in the high-temperature raw gas of the molten iron bath, but also utilizes the sensible heat of the top gas, the sensible heat generated by CO conversion and the heat generated by pressurizing the gas by the compressor in a heat exchange mode, thereby greatly improving the utilization amount of the sensible heat in the gas and improving the yield of the direct reduced iron.
The invention utilizes furnace top gas at 350-500 ℃ to heat and convert hydrogen to 330-480 ℃ at normal temperature, because CO is removed according to standard gas calculation2The amount of the normal-temperature conversion hydrogen is reduced by 1/3 compared with the amount of the top gas, the high enthalpy is used for heating the low enthalpy, and the temperature of the normal-temperature conversion hydrogen after heating is lower than that of the furnaceTop gas temperature, is possible.
The water vapor required by CO conversion is a large amount of water vapor generated by reducing iron by hydrogen contained in the directly reduced iron furnace top gas, and (H) in the furnace top gas can be utilized2O + CO) for medium and/or low temperature CO shift of the top gas in the presence of a catalyst in the shift converter.
In addition, the CO medium-temperature conversion and the CO low-temperature conversion are heat release processes, and the top gas can be raised to a certain temperature. Therefore, by utilizing sensible heat generated by CO conversion, water vapor can be obtained through heat exchange to supplement CO conversion H2The required water vapor.
The insufficient part can be supplemented by the water vapor recovered by the production system, for example, including but not limited to, the water vapor generated when the high-temperature liquid slag of the molten iron bath coal gas is cooled, the water vapor recovered by the co-production of synthetic ammonia and urea, the water vapor recovered from the boiler waste gas by using a turbine to drive a compressor, and the like; water vapor outside the system may also be introduced for the shift process.
The method of the invention aims to improve the temperature of the shift hydrogen, and the reducing gas in the molten iron bath coal gas is completely used as the reducing agent for directly reducing iron. Sensible heat of crude gas of gas produced by smelting iron and bathing coal, sensible heat of top gas of direct reduced iron furnace utilized by heat exchange, sensible heat generated by CO conversion, sensible heat generated by compressing gas by a compressor, and sensible heat of less than 3 percent of O added into intermediate temperature conversion hydrogen by adopting a partial oxidation method2Heat generated or CH admixed4Or H2The heat of the high-temperature gas after combustion is totally used for heating and transforming the hydrogen. Therefore, the method can maximize the yield of the direct reduced iron and maximize the energy utilization efficiency.
The temperature of the transformed hydrogen is increased to be more than or equal to 550 ℃, and the transformed hydrogen is added into the high-temperature crude gas of the molten iron bath at 1600 ℃ to obtain the circulating reducing gas at 850 ℃ for producing the direct reduced iron, so that the reducing gas in the coal gas of the molten iron bath can be completely used as the reducing agent for directly reducing the iron, and the energy consumption of the reducing agent for directly reducing the iron is only 218kg. standard coal/t.DRI. If 550 ℃ is not reached, there will be some residual hydrogen.
The residual hydrogen can be heated to 550-600 ℃ by adopting a set of heating system and added into the high-temperature molten iron bath crude gas at 1400-1600 ℃ to obtain the circulating reducing gas for producing the direct reduced iron. Although it is economically efficient to add a hydrogen heating system, it is more advocated to use this part of hydrogen for ammonia synthesis and further for the production of chemical products such as urea. This is because the addition of a heating hydrogen conversion system will increase a waste gas discharge chimney, will take away heat, and will increase CO2And the discharge of water vapor. Although not toxic and harmful substances, water vapor is a carrier of particulate matter PM2.5, and the haze is aggravated in a quiet atmospheric environment. The process for smelting the direct reduced iron by utilizing the high-temperature raw gas of the molten iron bath can realize the purpose of no CO2And water vapor venting.
The partial oxidation process is used to raise the temperature of the shifted hydrogen, which is admixed with O2The amount of hydrogen is controlled to be less than 3% at the explosion point of hydrogen oxidation combustion. In addition, combustion H may be carried out2Or CH4The high-temperature gas is added into the medium-temperature conversion hydrogen to obtain the medium-high temperature conversion hydrogen with the oxidation degree less than 6 percent. The added high-temperature gas raises the medium-temperature conversion hydrogen to 400-600 ℃, and is added into the high-temperature crude gas of the molten iron bath at 1400-1600 ℃ to obtain the hydrogen-carbon ratio of more than 1.1, the temperature of 630-1050 ℃, and the oxidation degree (H)2O+CO2) Less than or equal to 3 percent of recycled reducing gas is fed into the furnace. The reason why the recycled reducing gas with the oxidation degree less than or equal to 3 percent can be obtained is (CO) in the gas produced by smelting iron bath coal2+H2The content of O) is as low as less than 2 percent, and the (CO) in the hydrogen can be converted at medium and high temperature2+H2O) for dilution.
In the method, the water vapor in the top gas of the directly reduced iron furnace generates H after the shift reaction2And CO2，H2Can be recycled, which is the key reason for the invention to realize hydrogen reduction without discharging water vapor.
The method of the present invention has no special limitation on the dust remover adopted in the process flow, and can include, but is not limited to, high temperature dust removers such as heat-resistant stainless steel sintering dust removers, ceramic dust removers, cyclone dust removers, etc., and the selected dust remover must meet the technical requirements of the process flow of the present invention, for example, the heat-resistant temperature of the material must be higher than the gas temperature in the process flow, and the dust removal effect must not affect CO transformation and the downstream process flow.
The heat exchange process in the method of the present invention preferably employs a counter-current heat exchanger, including but not limited to a tubular heat exchanger, a plate heat exchanger, etc., and the heat exchanger selected must meet the technical requirements of the process of the present invention. For example, the temperature difference between the recycle reducing gas outlet and the top gas inlet is < 50 ℃.
Furthermore, the heat exchange process in the method can also adopt a heat pipe exchanger.
The method of the invention has no special limitation on the purification of the converted hydrogen after the CO conversion of the top gas of the direct reduced iron furnace, can adopt various conventional coal chemical industry gas purification processes, and preferably selects the process with small pressure drop, good purification effect, sulfur and CO2Can be recycled or used as a water washing coal gas purification technology of various natural gas direct reduction iron processes.
For example, it may include, but is not limited to, using a gas-based direct reduced iron shaft furnace top gas cleaning method; low-temperature methanol washing desulfurization and CO removal2A technique; wet oxidation desulfurization techniques, such as wet desulfurization and decarburization techniques of the Changchun east lion science and technology group. The adopted chemical technology needs to meet the technical requirements of the process flow of the invention. The low-temperature coal gas produced by the low-temperature methanol washing can be heated to normal temperature by adopting an external heating method, such as air heat exchange preheating, air heat pump preheating and the like.
The method of the present invention also has no particular limitation on the adopted CO medium-temperature shift and/or low-temperature shift technology, including the shift catalyst, and can include, but is not limited to, conventional processes such as "one-middle-two low", "two-middle-three low", "full low shift", "middle series low shift", "two-middle-two low", etc., but the shift effect must meet the technical requirements of the process flow of the present invention, for example, shifted H2Content > 96%, H2The S content is less than 0.5 percent.
The prior technical package for hydrogen production, separation and extraction of hydrogen from water gas adopted in the method of the inventionComprises the following steps: technology for separating and extracting hydrogen from shift gas by pressure swing adsorption after shift gas desulfurization and separating and recovering CO2Separation of N2(ii) a Technology for extracting hydrogen by changing gas and low-temperature methanol washing separation2S recovery, CO separation recovery2Separation of N2(ii) a Water washing separation and extraction of H2Technology, separation and recovery of CO2、H2S, obtaining H2The technique of (1); a low-temperature methanol washing process designed by Sading engineering Co., Ltd; the technology for extracting hydrogen by pressure swing adsorption separation after the desulfurization of the shift gas is designed by the Mr. Baiman technology company, the southwest chemical engineering company and the Changchun east lion technology company; the technology of washing, separating and extracting reducing gas by MIDREX company, and the like. Wherein, the low-temperature methanol washing technology needs pressure more than or equal to 25kg, the methanol needs to be cooled, various gases after the low-temperature methanol washing are heated and analyzed, more energy is consumed, hydrogen is needed to do work and reduce pressure, but S and CO are recovered2Recovering H2The efficiency is higher, and the method is suitable for the process flow of separating and extracting hydrogen with large flow.
The method of the invention is used for the gas H adopted after CO conversion in the process flow2With CO2Separation techniques, e.g. CO capture2The separation of CO is not particularly limited, and may be selected by MIDREX technology, low-temperature methanol washing technology, Pressure Swing Adsorption (PSA) technology, etc2Capture and recovery technique without CO in the production process2Emission, at the same time as CO has to be achieved2The technical requirement of utilization and the technical requirement that the oxidation degree of the direct reduced iron recycle reducing gas is less than 3 percent.
Because the method of the invention adopts CO to transform H2Process for recovering CO at low cost2Production of chemical products from residual reducing gas and production of green H from nuclear or renewable electric power2H, by-product of this process2、CO2、N2Can be CO-produced with chemical products, and finally urea, methanol and the like can be synthesized by a chemical method, so that CO can be realized2And (4) zero emission.
The method can fully utilize the sensible heat of oxidative decomposition of coal, the sensible heat of the coal gas at the top of the direct reduction iron furnace and the sensible heat of CO conversion reaction, so the method of the invention is used for a day longer than MIDREXThe method for producing the direct reduced iron by using the natural gas has low energy consumption. The method is characterized in that a part of top gas is required to be separated for combustion in the MIDREX method and used for indirectly heating the reducing gas and the converter, the waste gas discharged by the combustion of the part of top gas, the natural gas pyrolysis energy consumption and the indirect heating of the reducing gas are the energy loss and the CO loss of the MIDREX2The main process of emission. The invention therefore relates to CO with regard to energy consumption, to pollutant gas emissions2The method has the advantages of energy conservation and emission reduction compared with the method for directly reducing iron by natural gas in the aspects of recycling, hydrogen resource recycling and the like.
Detailed Description
The following examples further describe embodiments of the present invention. The following examples are only for more clearly illustrating the technical solutions of the present invention so as to enable those skilled in the art to better understand and utilize the present invention, and do not limit the scope of the present invention.
In the present invention, the terms such as "upper", "lower", "left", "right" and "middle" are used for clarity of description only, and are not used to limit the scope of the present invention, and the relative relationship changes or adjustments may be made without substantial technical changes and modifications.
The names and the short names of the process and the equipment adopted by the invention belong to the conventional names in the field, each name is quite clear and definite in the field of related application, and a person skilled in the art can understand the conventional process steps and apply the corresponding equipment according to the names.
Example 1.
A water gas hydrogen production process is adopted. The temperature of the directly reduced iron furnace top gas is 350-500 ℃, the pressure is 1-4 kg, the directly reduced iron furnace top gas exchanges heat with the normal temperature conversion hydrogen after being dedusted, the furnace top gas is pressurized to 10kg in a compressor after being cooled to less than 150 ℃, and the hydrogen production process is carried out.
The hydrogen production process adopts the water gas hydrogen production technology in the coal chemical industry, and particularly adopts pressure swing adsorption separation to extract H2S and CO are separated and recovered2To obtain H2The content is not less than 96 percent, and the pressure is 4-8 kg. The temperature is less than 25 ℃, and the oxidation degree is less than or equal to 3 percent.
After the normal temperature conversion hydrogen exchanges heat with the furnace top gas, the medium temperature conversion hydrogen with the temperature of 330-480 ℃ is obtained, and O with the concentration less than or equal to 3 percent is added by adopting a partial oxidation method2And obtaining medium-high temperature transformation hydrogen with the oxidation degree of less than or equal to 6% and the temperature of 500-600 ℃.
Sending the medium-high temperature transformed hydrogen into high-temperature raw gas of molten iron bath coal gas at 1400-1600 ℃ to obtain 630-1050 ℃, the oxidation degree of which is less than or equal to 3 percent, the pressure of which is 4-8 kg, (H)2And + CO) is more than or equal to 90 percent, and the hydrogen-carbon ratio is more than or equal to 1.1, and the circulating reducing gas is sent into the direct reduced iron shaft furnace to smelt the direct reduced iron.
Example 2.
A water gas hydrogen production process is adopted. The temperature of the directly reduced iron furnace top gas is 350-500 ℃, the pressure is 1-4 kg, the directly reduced iron furnace top gas exchanges heat with the normal temperature conversion hydrogen after being dedusted, the furnace top gas is pressurized to 10kg in a compressor after being cooled to less than 150 ℃, and the hydrogen production process is carried out.
The hydrogen production process adopts the water gas hydrogen production technology in the coal chemical industry, and particularly adopts pressure swing adsorption separation to extract H2S and CO are separated and recovered2To obtain H2The hydrogen is transformed at normal temperature, the content of which is more than or equal to 96 percent, the pressure of which is 4-8 kg, the temperature of which is less than 25 ℃ and the oxidation degree of which is less than or equal to 3 percent.
After the normal temperature conversion hydrogen exchanges heat with the furnace top gas, the medium temperature conversion hydrogen with the temperature of 330-480 ℃ is obtained, and then oxygen is adopted to burn CH4The generated high-temperature gas is added into the medium-temperature conversion hydrogen to obtain the medium-high temperature conversion hydrogen with the oxidation degree of less than or equal to 6% and the temperature of 500-600 ℃.
Sending the medium-high temperature transformed hydrogen into high-temperature raw gas of molten iron bath coal gas at 1400-1600 ℃ to obtain 630-1050 ℃, the oxidation degree of which is less than or equal to 3 percent, the pressure of which is 4-8 kg, (H)2And + CO) is more than or equal to 90 percent, and the hydrogen-carbon ratio is more than or equal to 1.1, and the circulating reducing gas is sent into the direct reduced iron shaft furnace to smelt the direct reduced iron.
Example 3.
A water gas hydrogen production process is adopted. The temperature of the directly reduced iron furnace top gas is 350-500 ℃, the pressure is 1-4 kg, the directly reduced iron furnace top gas exchanges heat with the normal temperature conversion hydrogen after being dedusted, the furnace top gas is cooled to be less than 180 ℃, and then the furnace top gas enters a compressor to be pressurized to be more than or equal to 25kg, and then the furnace top gas enters a hydrogen production process.
The hydrogen production process adopts a coal hydrogen production process in the coal chemical industry, particularly adopts a low-temperature methanol washing technology to separate and extract H2S and CO are separated and recovered2To obtain H2The hydrogen is transformed at normal temperature, the content of which is more than or equal to 96 percent, the pressure of which is 4-8 kg, the temperature of which is less than 25 ℃ and the oxidation degree of which is less than or equal to 3 percent.
After the normal temperature conversion hydrogen exchanges heat with the furnace top gas, the medium temperature conversion hydrogen with the temperature of 330-480 ℃ is obtained, and then oxygen is adopted to burn CH4The generated high-temperature gas is added into the medium-temperature conversion hydrogen to obtain the medium-high temperature conversion hydrogen with the oxidation degree of less than or equal to 6% and the temperature of 500-600 ℃.
Sending the medium-high temperature transformed hydrogen into high-temperature raw gas of molten iron bath coal gas at 1400-1600 ℃ to obtain 630-1050 ℃, the oxidation degree of which is less than or equal to 3 percent, the pressure of which is 4-8 kg, (H)2And + CO) is more than or equal to 90 percent, and the hydrogen-carbon ratio is more than or equal to 1.1, and the circulating reducing gas is sent into the direct reduced iron shaft furnace to smelt the direct reduced iron.
Example 4.
A water gas hydrogen production process is adopted. The temperature of the directly reduced iron furnace top gas is 350-500 ℃, the pressure is 1-4 kg, the directly reduced iron furnace top gas exchanges heat with the normal temperature conversion hydrogen after being dedusted, the furnace top gas is cooled to be less than 180 ℃, and then the furnace top gas enters a compressor to be pressurized to be more than or equal to 25kg, and then the furnace top gas enters a hydrogen production process.
The hydrogen production process adopts a coal hydrogen production process in the coal chemical industry, particularly adopts a low-temperature methanol washing technology to separate and extract H2S and CO are separated and recovered2To obtain H2The hydrogen is transformed at normal temperature, the content of which is more than or equal to 96 percent, the pressure of which is 4-8 kg, the temperature of which is less than 25 ℃ and the oxidation degree of which is less than or equal to 3 percent.
And (3) exchanging heat between the normal-temperature transformed hydrogen and the furnace top gas to obtain the medium-temperature transformed hydrogen at 330-480 ℃.
The medium-temperature transformed hydrogen is sent into high-temperature crude gas of molten iron bath coal gas production at 1400-1600 ℃ to obtain 630-1050 ℃, the oxidation degree is less than or equal to 3%, the pressure is 4-8 kg, (H)2And + CO) is more than or equal to 90 percent, and the hydrogen-carbon ratio is more than or equal to 1.1, and the circulating reducing gas is sent into the direct reduced iron shaft furnace to smelt the direct reduced iron.
The above embodiments of the present invention are not intended to be exhaustive or to limit the invention to the precise form disclosed. Various changes, modifications, substitutions and alterations to these embodiments will be apparent to those skilled in the art without departing from the principles and spirit of this invention.
Claims (4)
1. A method for pre-heat exchanging hydrogen gas using direct reduction iron furnace top gas, the method comprising:
1) producing 350-500 ℃ top gas with the pressure of 1-5 kg from the top of the direct reduced iron shaft furnace;
2) dedusting the top gas, then feeding the top gas into a heat exchanger, exchanging heat with normal-temperature conversion hydrogen, cooling to less than 180 ℃, pressurizing to more than 9kg, feeding the top gas into a flow of converting the top gas into the hydrogen, and obtaining H by adopting conventional CO conversion and gas separation technologies2The content is more than or equal to 96 percent, the pressure is 4-8 kg, and the oxidation degree (CO) is2+H2O) is less than or equal to 3 percent, and hydrogen is transformed at the normal temperature of less than 25 ℃;
3) the normal-temperature transformed hydrogen enters a heat exchanger, exchanges heat with furnace top gas, and is heated to 330-480 ℃ to obtain medium-temperature transformed hydrogen;
4) adding less than 3% of O into the medium-temperature conversion hydrogen2Or from CH4Or H2High temperature gas after combustion to obtain oxidation degree (CO)2+H2O) is less than or equal to 6 percent, and hydrogen is transformed at the medium-high temperature of 400-600 ℃;
5) adding the obtained medium-high temperature conversion hydrogen into high-temperature raw gas of molten iron bath coal gas production gas with the temperature of 1400-1600 ℃ and the pressure of 4-5 kg, and heating the added medium-high temperature conversion hydrogen by using the high-temperature raw gas to obtain the medium-high temperature conversion hydrogen with the hydrogen-carbon ratio of more than 1.1, the temperature of 630-1050 ℃, and the oxidation degree (H)2O+CO2) Introducing less than or equal to 3% of furnace-entering circulating reducing gas into the direct reduced iron shaft furnace, providing heat and reducing agent to produce direct reduced iron, and producing furnace top gas with the temperature of 350-500 ℃ and the pressure of 1-5 kg from the furnace top;
the above processes are circularly carried out.
2. The method of claim 1, wherein the heat exchange process uses a counter-current heat exchanger.
3. The method for pre-heating hydrogen conversion using direct reduced iron furnace top gas according to claim 2, wherein the counter-flow heat exchanger is a tubular heat exchanger or a baffle heat exchanger.
4. The method of claim 1, wherein the heat exchange process uses a heat pipe exchanger.
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| CN113373273A (en) * | 2021-06-17 | 2021-09-10 | 北京金博威科技有限公司 | Gas-based reduction method, gas-based reduction system and application of granular iron ore |
| CN113403441A (en) * | 2021-06-17 | 2021-09-17 | 北京金博威科技有限公司 | Production method, production system and application of granular direct reduced iron |
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| SE2250976A1 (en) * | 2022-08-18 | 2024-02-19 | Luossavaara Kiirunavaara Ab | A direct reduction facility and a method of direct reduction of metal oxide |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113373273A (en) * | 2021-06-17 | 2021-09-10 | 北京金博威科技有限公司 | Gas-based reduction method, gas-based reduction system and application of granular iron ore |
| CN113403441A (en) * | 2021-06-17 | 2021-09-17 | 北京金博威科技有限公司 | Production method, production system and application of granular direct reduced iron |
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Application publication date: 20210416 |