Device and method for producing direct reduction iron by full hydrogen

Abstract

The invention discloses a device and a method for producing direct reduced iron by full hydrogen, circulating hydrogen discharged from a reduction furnace enters a hydrogen circulating system and directly exchanges heat with high-temperature coke produced by a coke oven in a coking process after being cooled and dehydrated, and the high-temperature circulating hydrogen after heat exchange carries coke powder; the high-temperature circulating hydrogen enters a reduction area of the reduction furnace to participate in reduction of iron-containing materials after being subjected to gravity settling and cyclone dust removal for coke powder removal, and sponge iron is obtained; coke powder obtained after cyclone dust removal enters a gasification furnace of a carburizing system to be oxidized into CO, and then the CO serves as carburizing gas to enter a carburizing area of a reduction furnace to complete carburizing of sponge iron. According to the invention, a coking process and a full-hydrogen direct reduction iron production process are coupled, so that the heating of circulating reducing gas and the carburization of direct reduction iron are realized.

Description

Technical Field

[0001] This invention relates to the field of gas-based direct reduction ironmaking technology, and more specifically, to an apparatus and method for producing direct reduced iron using all-hydrogen. Background Technology

[0002] Gas-based vertical shaft furnace direct reduction process is one of the most representative direct reduction processes. There are direct reduction processes such as MIDREX, HYL-I, HYL-III and HYL / Energiron-ZR that use gas-based vertical shaft furnaces as reduction reactors. Natural gas is generally used as the reducing agent. In recent years, direct reduction furnaces using coke oven gas as the reducing agent have emerged and are used in conjunction with coke ovens to produce direct reduced iron.

[0003] The production of direct reduced iron using all-hydrogen technology has become a promising technological route for future low-carbon metallurgy. However, how to achieve carburization during all-hydrogen reduction remains a problem that needs to be solved.

[0004] In existing technologies, the literature "Development Direction and Strategy of Non-Blast Furnace Ironmaking Technology" by Zhou Yusheng, Qian Hui, et al., focuses on using high-purity oxygen (12-20 mg / L) to achieve high-purity oxygen production. 3 The gas is blown into a high-temperature reducing gas containing methane, raising the gas temperature to approximately 1000°C and the temperature inside the shaft furnace to 900°C. This increases the shaft furnace's productivity by about 20% and saves 5% on energy. Oxygen is then added to partially oxidize the natural gas, generating an even higher-temperature reducing gas. This heating process uses a specially designed burner to partially combust the oxygen and natural gas. This technology has been further developed into the ZR (Zero Reforming) technology for NG / COG shaft furnaces, which improves shaft furnace productivity and reduces investment without requiring an additional reformer. The ZR zero-reformation direct reduction process involves partially burning natural gas with a small amount of oxygen to raise its temperature to 1085°C before it enters the furnace (methane reforming is more thorough when the temperature exceeds 1000°C). The HYL zero-reformation direct reduction process is only suitable for coke oven gas, Lurgi gas, and natural gas containing methane in the reducing gas.

[0005] In their paper "Development and Review of Non-Blast Furnace Ironmaking Processes," Sun Taipeng et al. introduced the production status of direct reduced iron (DRI) at home and abroad in recent years and analyzed the status of different non-blast furnace ironmaking processes. Through the analysis of several representative processes, they concluded that Midrex and HYL-III are the most mature and important DRI processes. The FASTMET process has been continuously improved in recent years. my country should develop new technologies with independent intellectual property rights that are suitable for my country's resource conditions and national conditions, based on the introduction and assimilation of new processes. In the Midrex process, the reducing gas is produced by catalytic cracking of natural gas, and the cracking agent is the top gas. The top gas contains about 70% CO and H2. After being pressurized, it is sent to the mixing chamber and mixed evenly with an equivalent amount of natural gas. The mixed gas first enters a heat exchanger for preheating. The heat source for the heat exchanger is the tail gas of the reformer. The preheated mixed gas is sent to the nickel catalytic reaction tube group in the reformer for catalytic cracking reaction and conversion into reducing gas. The reducing gas contains about 95% CO and H2 and the temperature is 850-900℃.

[0006] In the paper "Current Status and Future Adaptability Analysis of Non-Blast Furnace Ironmaking Processes" by Ying Ziwei et al., it is noted that the Energiron process developed Zero Reforming (ZR) technology, which eliminates the natural gas reformer and catalyst, saving some investment. However, the gas-fired furnace of the ZR technology operates in a high-methane environment for a long time. Iron elements in the high-temperature alloy furnace tubes inside the furnace are prone to carburization reaction with methane, causing corrosion of the furnace tubes and leakage of reducing gas, ultimately leading to an explosion. The explosion of the furnace in the Nucor ZR process shows that Zero Reforming is not a foolproof and safe direct reduction process in a vertical furnace. Excessive methane content not only poses certain safety hazards to the furnace, but methane cracking also reduces the reduction temperature in the vertical furnace, thus requiring an increase in the temperature of the gas entering the furnace to compensate for the temperature.

[0007] In Zhang Fuming et al.'s paper, "Current Status and Prospect of Gas-Based Vertical Shaft Furnace Direct Reduction Technology," both the MIDREX and HYL processes have been developed for gas-based vertical shaft furnaces using coke oven gas. The MIDREX process first reforms the purified and preheated coke oven gas in a thermal reactor, while simultaneously adding a CO2 removal device to the reducing gas loop, allowing it to produce cold or hot DRI. The HYL-ZR process does not require modification to the reducing gas loop, but it necessitates first introducing the coke oven gas into a cooling loop, thus limiting its production to cold DRI. Research indicates that the difficulty in utilizing coke oven gas lies in its presence of small amounts of BTX (a mixture of benzene, toluene, and xylene), tar, and naphthalene, among other impurities. BTX can cause carbon deposition when the reducing gas passes through the heater, leading to pipe blockage. Furthermore, for the HYL-ZR process, the working pressure inside the vertical shaft furnace is approximately 0.6 MPa, while the pressure of the gas output from the coking plant is approximately 5 kPa. Therefore, it is necessary to pressurize the coke oven gas. During the pressurization process, a large amount of tar and naphthalene in the gas will be released, which will also clog equipment and pipelines. How to eliminate the harm of impurities such as BTX to the reduction process is a key technical challenge that needs to be overcome in the gas-based vertical shaft furnace direct reduction process using coke oven gas as fuel.

[0008] In Zhang Ben et al.'s paper, "Development of Gas-Based Vertical Shaft Furnace Direct Reduction Ironmaking Technology," significant differences are observed between the two processes in terms of process characteristics. The MIDREX process uses dry reforming of natural gas, employing CO2 from the furnace top gas as the oxidant; therefore, there is no decarburization device in the furnace top gas treatment process. The φ(H2) / φ(CO) ratio in the reducing gas produced by the reformer is approximately 1.6. In contrast, the Energiron process uses wet reforming of natural gas, employing steam as the oxidant. Therefore, there is a decarburization device in the furnace top gas treatment process, and a gas humidifier before the gas enters the heating furnace. The φ(H2) / φ(CO) ratio in the reducing gas produced by this process is approximately 3.5. The HYL / Energiron-ZR process replaces the independent reformer with an in-shaft furnace self-reforming process, incorporating a CO2 removal device and a steam humidification device in the reducing furnace top gas. This allows for selective removal of oxidizing gas components from the reducing gas and flexible adjustment of the reducing gas composition.

[0009] Chinese patent application CN202080039047.2 discloses a method for the direct reduction of iron, using hydrogen to produce direct reduced iron (DRI) with or without carbon, wherein the hydrogen is produced using water generated internally by the method; the method includes one or two gas loops, one for influencing the reduction of oxides and the other for influencing carburizing of DRI; the main loop responsible for reduction recycles the spent gas from the shaft furnace in a loop including a dry dust removal step, an oxygen removal step for generating hydrogen, and a loop connected to the shaft furnace for reduction; in the absence of a second loop, this loop, combined with natural gas addition, can be used for carbon deposition. An auxiliary carburizing loop installed downstream of the shaft furnace allows for finer control of carbon addition; this loop includes a reactor vessel, a dust removal step, and a gas separation unit.

[0010] Chinese Patent Application No. CN 202180023189.4 discloses a method for producing direct reduced iron with an increased carbon content, comprising: providing a carbon monoxide-rich gas stream and splitting the carbon monoxide-rich gas stream into at least two separate carbon monoxide-rich gas streams; providing a hydrocarbon-rich gas stream and splitting the hydrocarbon-rich gas stream into at least two separate hydrocarbon-rich gas streams; blending one of the carbon monoxide-rich gas streams with one of the hydrocarbon-rich gas streams to form a mixed carburizing gas stream; blending another of the at least two separate carbon monoxide-rich gas streams with another of the at least two separate hydrocarbon-rich gas streams to form different mixed carburizing gas streams; feeding each of the mixed carburizing gas streams with different compositions to a transition zone of a direct reduction furnace, and exposing partially or fully reduced iron oxides to the mixed carburizing gas streams to increase the carbon content of the resulting direct reduced iron to greater than 4.5% by weight.

[0011] Chinese Patent Application No. CN97182473.8 discloses a method and apparatus for controlling direct reduction iron carburizing. This involves reforming hydrocarbons in a reduction reactor (10) using oxidants such as water and oxygen. A reducing gas is generated from natural gas in a reduction reaction system (5) to chemically reduce iron oxides. The reactor (10) contains metallic iron, which acts as a reforming catalyst, in a steady state. The amount of carbon in the DRI (62) is controlled by changing the relative amounts of water, carbon dioxide, and oxygen in the reducing gas supplied to the reduction reactor (10). The amount of carbon in the DRI (62) is controlled by the amount of water supplied to the reduction reactor (10), while oxygen is added to provide the energy required for DRI carburizing.

[0012] In summary, although the existing technologies mentioned above include direct reduction iron processes utilizing hydrogen, they are not technologies for producing direct reduced iron entirely with hydrogen. Both the process gas and the carburizing gas contain hydrocarbons such as CH4. Therefore, it is necessary to develop a method for producing direct reduced iron entirely with hydrogen that can solve the problems of heating the circulating reducing gas and carburizing the direct reduced iron during the production of direct reduced iron entirely with hydrogen. Summary of the Invention

[0013] To address the shortcomings of existing technologies, the present invention aims to provide an apparatus and method for producing direct reduced iron using all-hydrogen technology. By coupling the coking process with the direct reduced iron production process using all-hydrogen technology, the heating of the circulating reducing gas and the carburizing of the direct reduced iron are achieved.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] The first aspect of the present invention provides a method for producing direct reduced iron using all-hydrogen. Circulating hydrogen gas from the reduction furnace enters a hydrogen circulation system, is cooled and dehydrated, and then directly exchanges heat with high-temperature coke produced in the coking process. The high-temperature circulating hydrogen gas after heat exchange carries coke powder. After gravity settling and cyclone dust removal to remove the coke powder, the high-temperature circulating hydrogen gas enters the reduction zone of the reduction furnace to participate in the reduction of iron-containing materials to obtain sponge iron. The coke powder obtained after cyclone dust removal enters the gasifier of the carburizing system, is oxidized to CO, and then enters the carburizing zone of the reduction furnace as carburizing gas to complete the carburizing of the sponge iron.

[0016] Preferably, it includes the following steps:

[0017] S1, the circulating hydrogen from the reduction furnace enters the hydrogen circulation system and is cooled to 80℃±10℃ by the cooling, dehydration and dust removal system. At the same time, the water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen is pressurized and then enters the direct heat exchanger.

[0018] S2, after dehydration, the circulating hydrogen is evenly distributed through the gas distribution plate at the bottom of the direct heat exchanger and then enters the direct heat exchanger. The low-temperature circulating hydrogen flows upward through the coke gaps and directly exchanges heat with the high-temperature coke produced by the coking oven in the coking process. The circulating hydrogen is heated to 960℃±25℃ and then discharged from the top of the direct heat exchanger. The high-temperature coke is cooled to 120±20℃ and then discharged from the bottom of the direct heat exchanger.

[0019] S3, the heated high-temperature circulating hydrogen gas, carrying coke powder, exits from the top of the direct heat exchanger. After settling in the gravity settling chamber, the coke powder content carried by the high-temperature circulating hydrogen gas is reduced to 10 g / m³. 3 ~20g / m 3 Then it enters the cyclone dust collector, and the high-temperature circulating hydrogen gas after removing coke powder enters the reduction zone of the reduction furnace to participate in the reduction of iron-containing materials to obtain sponge iron.

[0020] S4, the coke powder coming out of the cyclone dust collector enters the gasifier. In the initial stage of startup, the coke powder is oxidized to CO under the action of oxygen. The CO gas is used as carburizing gas and is pressurized by the pressurization unit and introduced into the carburizing zone of the reduction furnace to complete the carburizing of the sponge iron.

[0021] S5, the tail gas containing CO and CO2 after carburizing is recycled to the gasifier. The coke powder in the gasifier is gasified and used as carburizing gas. After being pressurized by the pressurization unit, it enters the carburizing area to participate in the carburizing of sponge iron.

[0022] Preferably, in step S1, low-temperature high-pressure hydrogen is added to the hydrogen circulation system, and the added hydrogen is mixed with the hydrogen pressurized by the booster and then enters the direct heat exchanger.

[0023] Preferably, in step S2, the high-temperature coke at 1025℃±25℃ first enters the coke loading buffer tank, and then enters the direct heat exchanger through the vertical channel between the coke loading buffer tank and the direct heat exchanger, where it directly contacts and exchanges heat with the circulating hydrogen. After the high-temperature coke is cooled to 120℃±20℃, it is discharged from the bottom of the direct heat exchanger. The bottom of the coke loading buffer tank is connected to an exhaust fan, and the exhaust fan maintains zero pressure or a slight negative pressure of 0Pa to -10Pa at the connection between the bottom of the coke loading buffer tank and the exhaust fan.

[0024] Preferably, in step S4, the gasification furnace is electrically heated, and the furnace temperature is 1285±15℃.

[0025] Preferably, in step S4, the metallization rate of the carburized sponge iron is ≥93%, and the carbon content is 3%±1%.

[0026] A second aspect of the present invention provides an apparatus for the direct reduced iron production process using all-hydrogen, comprising a reduction furnace having a feed inlet and a gas outlet at the top; a reduction zone at the upper part of the reduction furnace and a carburizing zone at the lower part; further comprising:

[0027] The hydrogen circulation system includes a cooling dehydration and dust removal system, a booster compressor, a direct heat exchanger, a gravity settling chamber, and a cyclone dust collector connected by pipelines; the cooling dehydration and dust removal system is connected to the outlet of the reduction furnace; the direct heat exchanger is used for direct heat exchange between circulating hydrogen and high-temperature coke; the top outlet of the cyclone dust collector is connected to the hydrogen inlet of the reduction zone of the reduction furnace.

[0028] The carburizing system includes a gasifier and a pressurization unit; the gas inlet at the bottom of the gasifier is connected to the carburizing gas outlet at the top of the carburizing zone of the reduction furnace, the gas outlet at the top of the gasifier is connected to the pressurization unit, and the top of the gasifier is connected to the cyclone dust collector. The gasifier is used to oxidize the coke powder coming out of the cyclone dust collector to obtain carburizing gas; the pressurization unit is connected to the carburizing gas inlet at the bottom of the carburizing zone of the reduction furnace.

[0029] The apparatus for producing direct reduced iron from all hydrogen is used to perform the method for producing direct reduced iron from all hydrogen as described in the first aspect of the invention.

[0030] Preferably, a coke loading buffer tank is provided above the direct heat exchanger, and the coke loading buffer tank is connected to the direct heat exchanger through a vertical channel; a fan is connected to the bottom of the coke loading buffer tank through a pipe.

[0031] Preferably, the bottom of the direct heat exchanger is provided with a gas distribution plate for uniformly distributing the gas.

[0032] Preferably, the gravity settling chamber has an air inlet in the middle that is connected to the direct heat exchanger, an air outlet at the top of the gravity settling chamber, and a baffle wall inside the gravity settling chamber to separate the air inlet and the air outlet.

[0033] Preferably, the hydrogen circulation system further includes a hydrogen replenishment mechanism, which is connected to the pipeline between the booster and the direct heat exchanger via a hydrogen replenishment pipeline, and is also connected to the hydrogen production device.

[0034] The apparatus and method for producing direct reduced iron using all-hydrogen provided by this invention have the following beneficial effects:

[0035] 1. The present invention utilizes the heat energy of high-temperature red coke produced in the coking process for heating reducing hydrogen, without the need for additional heat sources, thus achieving good economic efficiency.

[0036] 2. The carbon source for direct reduction iron carburizing in this invention comes from the dust-removed coke powder after heat exchange between the red coke and circulating hydrogen in the system. The carburizing circulating gas enters the high-temperature furnace containing the dust-removed coke powder to react and replenish the carbon consumed in the carburizing process. The system process is simple and efficient. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the apparatus for the all-hydrogen production of direct reduced iron according to the present invention;

[0038] In the diagram, 1. Reduction furnace; 2. Cooling, dehydration and dust removal system; 3. Coke loading buffer tank; 4. Direct heat exchanger; 5. Gravity settling chamber; 6. Cyclone dust collector; 7. Gasifier; 8. Booster; 9. Booster unit; 10. Exhaust fan. Detailed Implementation

[0039] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] Combination Figure 1 As shown, this invention provides an apparatus for the all-hydrogen production of direct reduced iron (DRI), comprising a reduction furnace 1, a hydrogen circulation system, and a carburizing system. The circulating hydrogen used in the reduction zone of the reduction furnace 1 is heated using the thermal energy of high-temperature red-hot coke produced in the coking process. The carbon source for DRI carburizing comes from the high-temperature red-hot coke and the dust-removed coke powder after heat exchange with the circulating hydrogen. The carburizing gas enters a gasifier 7 containing the dust-removed coke powder to react and replenish the carbon consumed during the carburizing process. This invention couples the coking process and the all-hydrogen production of DRI process, achieving both the heating of the circulating reducing gas and the carburizing of DRI.

[0041] Combination Figure 1 As shown, the reduction furnace 1 has a feed inlet and a gas outlet at the top; the upper part of the reduction furnace 1 has a reduction zone and the lower part has a carburizing zone; iron-containing materials such as pellets and carbon-containing pellet lumps fall into the reduction zone of the reduction furnace 1 from the feed inlet, and produce sponge iron under the reduction action of circulating hydrogen. Then the sponge iron falls into the carburizing zone and completes carburizing under the action of carburizing gas; the circulating hydrogen comes out from the gas outlet at the top of the reduction furnace 1 and enters the hydrogen circulation system. After being heated, it returns to the lower part of the reduction zone to participate in the reduction of iron; the carburizing gas that has completed carburizing comes out from the upper part of the carburizing zone and enters the carburizing system to replenish the carburizing gas before returning to the carburizing zone to continue to participate in the carburizing reaction of sponge iron.

[0042] Combination Figure 1As shown, the hydrogen circulation system includes a cooling dehydration and dust removal system 2, a booster compressor 8, a direct heat exchanger 4, a gravity settling chamber 5, and a cyclone dust collector 6, all connected by pipelines. The cooling dehydration and dust removal system 2 is connected to the outlet of the reduction furnace 1. The direct heat exchanger 4 is used for direct heat exchange between circulating hydrogen and high-temperature coke. The top outlet of the cyclone dust collector 6 is connected to the hydrogen inlet of the reduction zone of the reduction furnace 1. In a specific embodiment, a coke loading buffer tank 3 is provided above the direct heat exchanger 4, and the coke loading buffer tank 3 is connected to the direct heat exchanger 4 via a vertical channel. A blower 10 is connected to the bottom of the coke loading buffer tank 3 via a pipeline to maintain zero pressure or a slight negative pressure (0 Pa to -10 Pa) at the connection between the bottom of the coke loading buffer tank 3 and the blower 10. The gas discharged by the blower 10 can be used for supplementary heating of the coke oven head. A gas distribution plate is provided at the bottom of the direct heat exchanger 4 to distribute the gas evenly. The gravity settling chamber 5 has an air inlet in the middle that connects to the direct heat exchanger 4, and an air outlet at the top. A baffle wall separates the air inlet and outlet within the gravity settling chamber 5. The hydrogen circulation system also includes a hydrogen replenishment mechanism, which is connected to the pipeline between the booster 8 and the direct heat exchanger 4 via a hydrogen replenishment pipe. The hydrogen replenishment mechanism is also connected to a hydrogen production device, which can utilize principles such as water electrolysis, natural gas production, coal production, raw coal gas production, heavy oil production, or biomass production. The circulating hydrogen gas exiting from the top of the reduction furnace 1 enters the cooling, dehydration, and dust removal system 2 to be cooled to 80℃±10℃. Simultaneously, water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen gas is then pressurized by the booster 8 and enters the direct heat exchanger 4 along with supplementary hydrogen gas. After being evenly distributed by the gas distribution plate at the bottom of the direct reduced iron, it undergoes direct heat exchange with the high-temperature coke in the direct heat exchanger 4. The circulating hydrogen gas is then heated to 960±25℃ and carries coke powder out from the top of the direct heat exchanger 4, entering the gravity settling chamber 5 equipped with baffles. After gravity settling, the coke powder carrying capacity of the circulating hydrogen gas is reduced to 10g / m³. 3 ~20g / m 3 Then it enters the cyclone dust collector 6 for further dust removal. After being removed by the cyclone dust collector, the circulating hydrogen enters the reduction furnace 1 from the reduction zone to continue participating in the reduction of iron and obtain sponge iron.

[0043] Combination Figure 1As shown, the carburizing system includes a gasifier 7 and a pressurization unit 9; the gas inlet at the bottom of the gasifier 7 is connected to the carburizing gas outlet at the top of the carburizing area of ​​the reduction furnace 1, the gas outlet at the top of the gasifier 7 is connected to the pressurization unit 9, and the top of the gasifier 7 is connected to the cyclone dust collector 6. The gasifier 7 is used to oxidize the coke powder coming out of the cyclone dust collector 6 to obtain carburizing gas; the pressurization unit 9 is connected to the carburizing gas inlet at the bottom of the carburizing area of ​​the reduction furnace 1. Coke powder exiting the cyclone dust collector 6 enters the gasifier 7. At the initial stage of the device startup, a certain amount of oxygen is introduced into the gasifier 7, causing part of the coke powder entering the gasifier 7 to oxidize and generate CO. The CO gas is used as carburizing gas and is pressurized by the pressurization unit 9 before entering the carburizing area to carburize the sponge iron. After carburizing is completed, the carburizing gas (containing CO and CO2 tail gas) is circulated back to the gasifier 7 of the carburizing system. The CO2 in the tail gas reacts with the coke powder continuously entering the gasifier 7 to generate CO to replenish the carburizing gas. After being pressurized by the pressurization unit 9, it re-enters the carburizing area to carburize the sponge iron.

[0044] Combination Figure 1 As shown, this invention provides a method for producing direct reduced iron using all-hydrogen. Circulating hydrogen from the reduction furnace enters a hydrogen circulation system, where it is cooled and dehydrated before directly exchanging heat with high-temperature coke produced in the coking process. The high-temperature circulating hydrogen, carrying coke powder, undergoes gravity settling and cyclone dust removal to remove the coke powder before entering the reduction zone of the reduction furnace to participate in the reduction of iron-containing materials and obtain sponge iron. The coke powder obtained after cyclone dust removal enters the gasifier of the carburizing system, is oxidized to CO, and then enters the carburizing zone of the reduction furnace as carburizing gas to complete the carburizing of the sponge iron.

[0045] This invention also provides a method for producing direct reduced iron using all-hydrogen, comprising the following steps:

[0046] S1, the circulating hydrogen from the reduction furnace 1 enters the hydrogen circulation system and is cooled to 80℃±10℃ by the cooling, dehydration and dust removal system 2. At the same time, the water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen is pressurized by the booster and then enters the direct heat exchanger 4.

[0047] During the above process, low-temperature, high-pressure hydrogen is supplied to the hydrogen circulation system. The supplied hydrogen mixes with the hydrogen pressurized by the booster 8 and then enters the direct heat exchanger 4. The sources of supplied hydrogen include hydrogen production from water electrolysis, hydrogen production from natural gas, hydrogen production from coal, hydrogen production from raw coal gas, hydrogen production from heavy oil, and hydrogen production from biomass.

[0048] S2, the dehydrated circulating hydrogen enters the direct heat exchanger 4 after being evenly distributed by the gas distribution plate at the bottom of the direct heat exchanger 4. The low-temperature circulating hydrogen flows upward through the coke gaps and directly exchanges heat with the high-temperature coke produced by the coke oven in the coking process. The circulating hydrogen is heated to 960℃±25℃ and then discharged from the top of the direct heat exchanger 4. The high-temperature coke is cooled to 120±20℃ and then discharged from the bottom of the direct heat exchanger 4.

[0049] In the above process, high-temperature coke at 1025℃±25℃ first enters the coke loading buffer tank 3, and then enters the direct heat exchanger 4 through the vertical channel between the coke loading buffer tank 3 and the direct heat exchanger 4, where it directly contacts and exchanges heat with circulating hydrogen. After being cooled to 120℃±20℃, the high-temperature coke is discharged from the bottom of the direct heat exchanger 4. The bottom of the coke loading buffer tank 3 is connected to the exhaust fan 10 through a pipe. The exhaust fan 10 maintains zero pressure or a slight negative pressure (0Pa to -10Pa) at the connection between the bottom of the coke loading buffer tank 3 and the exhaust fan 10. The gas discharged by the exhaust fan 10 can be used for supplementary heating of the coke oven head. The high-temperature coke mentioned above comes from coke produced in the same area of ​​the coking process.

[0050] S3, when the heated high-temperature circulating hydrogen gas exits from the top of the direct heat exchanger 4, it carries coke powder. After settling in the gravity settling chamber 5, the coke powder content carried by the high-temperature circulating hydrogen gas is reduced to 10 g / m³. 3 ~20g / m 3 Then it enters the cyclone dust collector 6, and the high-temperature circulating hydrogen gas after removing coke powder enters the reduction zone of the reduction furnace 1 to participate in the reduction of iron-containing materials to obtain sponge iron.

[0051] When circulating hydrogen gas at 960℃±25℃ exits from the top of the direct heat exchanger 4, it carries coke powder and enters the gravity settling chamber 5 equipped with a baffle wall. The dimensions of the gas flow cross-sectional area of ​​the gravity settling chamber 5 can be designed to reduce the coke powder content carried by the circulating hydrogen gas to 10g / m². 3 ~20g / m 3 Then, the coke powder enters the cyclone dust collector 6 to further reduce the amount of coke powder carried. The coke powder coming out of the cyclone dust collector 6 enters a gasifier 7. The high-temperature circulating hydrogen from the cyclone dust collector 6 enters the reduction furnace 1 to reduce the iron ore and obtain sponge iron.

[0052] S4, the coke powder coming out of the cyclone dust collector 6 enters the gasifier 7. In the initial stage of startup, the coke powder is oxidized to CO under the action of oxygen. The CO gas is used as carburizing gas and is pressurized by the pressurization unit 9 and introduced into the carburizing area of ​​the reduction furnace 1 to complete the carburizing of the sponge iron.

[0053] The coke powder exiting the cyclone dust collector 6 enters the gasifier 7. During the initial startup phase, a certain amount of oxygen is introduced into the gasifier 7, causing partial oxidation of the coke powder entering the combustion furnace to generate CO. This CO gas is then introduced as carburizing gas into the carburizing zone at the bottom of the reduction furnace 1 to carburize the sponge iron. The coke powder mentioned above comes from coke powder carried by circulating hydrogen during direct heat exchange with high-temperature coke. The gasifier 7 is electrically heated, with an internal temperature of 1285±15℃. After carburizing, the metallization rate of the sponge iron product is ≥93%, and the carbon content is 3%±1%.

[0054] S5, the tail gas containing CO and CO2 after carburizing is recycled to the gasifier 7. The coke powder in the gasifier 7 is gasified and used as carburizing gas. After being pressurized by the pressurization unit 9, it enters the carburizing area to participate in the carburizing of sponge iron.

[0055] After carburizing, the tail gas containing CO and CO2 is recycled to the gasifier 7, which gasifies the coke powder that continuously enters the gasifier 7 to supplement the carburizing gas. The carburizing gas is pressurized by the pressurization unit 9 and then enters the carburizing area to carburize the sponge iron.

[0056] Example 1

[0057] like Figure 1 As shown, this example provides a method for producing direct reduced iron using all-hydrogen, including the following process equipment: an iron ore reduction furnace 1, a direct heat exchanger for high-temperature coke and hydrogen 4, a coke loading buffer tank 3, a gravity settling chamber 5, a cyclone dust collector 6, a coke powder gasification furnace 7, a circulating hydrogen cooling, dehydration and dust removal system 2 for water vapor from the reduction furnace 1, a booster compressor 8, a booster unit 9, etc. The iron ore includes pellets, carbon-containing pellets, lump ore, etc., and the hydrogen sources include hydrogen production from water electrolysis, hydrogen production from natural gas, hydrogen production from coal, hydrogen production from raw coal gas, hydrogen production from heavy oil, hydrogen production from biomass, etc.

[0058] This example provides a method for producing direct reduced iron using all-hydrogen, including the following steps:

[0059] S1, the circulating hydrogen from the reduction furnace 1 enters the hydrogen circulation system, and is cooled to 85°C by the cooling, dehydration and dust removal system 2. At the same time, the water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen is pressurized by the booster 8 and then mixed with the low-temperature and high-pressure hydrogen in the hydrogen circulation system before entering the direct heat exchanger 4. In the above process, low-temperature and high-pressure hydrogen is added to the hydrogen circulation system for reduction.

[0060] S2, mixed hydrogen gas is evenly distributed through a gas distribution plate at the bottom of the direct heat exchanger 4 and then enters the direct heat exchanger 4. Low-temperature hydrogen gas flows upward through the coke gaps, directly exchanging heat with the high-temperature coke. The circulating hydrogen gas is heated to 960℃ and discharged from the top of the direct heat exchanger 4. A coke loading buffer tank 3 is installed above the direct heat exchanger 4, and is connected to the secondary heat exchanger via a vertical channel with a square cross-section. High-temperature coke at 1035℃ first enters the coke loading buffer tank 3, and then enters the direct heat exchanger 4 through the vertical channel between the coke loading buffer tank 3 and the direct heat exchanger 4, directly contacting and exchanging heat with the circulating hydrogen gas. After the coke is cooled to 130℃, it is discharged from the bottom of the secondary heat exchanger. A blower 10 is connected to the bottom of the coke loading buffer tank 3 via a pipe, maintaining zero pressure or a slight negative pressure (0Pa to -10Pa) at the connection point between the bottom of the coke loading buffer tank 3 and the blower 10. The gas discharged by the blower 10 can be used for supplementary heating of the coke oven head.

[0061] S3, 960℃ circulating hydrogen, carrying coke powder, exits from the top of the direct heat exchanger 4 and enters the gravity settling chamber 5, which is equipped with a baffle. The dimensions of the gas flow cross-sectional area of ​​the gravity settling chamber 5 are designed to ensure that the coke powder content of the circulating hydrogen is 15g / m³. 3 Then it enters the cyclone dust collector 6, and the high-temperature circulating hydrogen from the cyclone dust collector 6 enters the reduction furnace 1 to reduce the iron ore.

[0062] S4. Coke powder from cyclone dust collector 6 enters a gasifier 7. During the initial startup phase, a certain amount of oxygen is introduced into the gasifier 7, causing partial oxidation of the coke powder entering the combustion furnace to produce CO. This CO gas is then used as carburizing gas, pressurized by booster unit 9, and introduced into the carburizing zone below the reduction furnace 1 to carburize the sponge iron. The tail gas containing CO and CO2 after carburizing is recycled back to the gasifier 7, continuously gasifying the coke powder entering the gasifier 7 to replenish the carburizing gas. The carburizing gas is pressurized by booster unit 9 before entering the carburizing zone to carburize the sponge iron. The gasifier 7 is electrically heated, with an internal temperature of 1270℃. After carburizing, the sponge iron product has a metallization rate of 94.0% and a carbon content of 3.2%.

[0063] Example 2

[0064] like Figure 1 As shown, this example provides a method for producing direct reduced iron using all-hydrogen, including the following process equipment: an iron ore reduction furnace 1, a direct heat exchanger for high-temperature coke and hydrogen 4, a coke loading buffer tank 3, a gravity settling chamber 5, a cyclone dust collector 6, a coke powder gasification furnace 7, a circulating hydrogen cooling, dehydration and dust removal system 2 for water vapor from the reduction furnace 1, a booster compressor 8, a booster unit 9, etc. The iron ore includes pellets, carbon-containing pellets, lump ore, etc., and the hydrogen sources include hydrogen production from water electrolysis, hydrogen production from natural gas, hydrogen production from coal, hydrogen production from raw coal gas, hydrogen production from heavy oil, hydrogen production from biomass, etc.

[0065] This example provides a method for producing direct reduced iron using all-hydrogen, including the following steps:

[0066] S1, the circulating hydrogen from the reduction furnace 1 enters the hydrogen circulation system, and is cooled to 90°C by the cooling, dehydration and dust removal system 2. At the same time, the water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen is pressurized by the booster 8 and then mixed with the low-temperature and high-pressure hydrogen in the hydrogen circulation system before entering the direct heat exchanger 4. In the above process, low-temperature and high-pressure hydrogen is added to the hydrogen circulation system for reduction.

[0067] S2, mixed hydrogen gas is evenly distributed through a gas distribution plate at the bottom of the direct heat exchanger 4 and then enters the direct heat exchanger 4. Low-temperature hydrogen gas flows upward through the coke gaps, directly exchanging heat with the high-temperature coke. The circulating hydrogen gas is heated to 985℃ and discharged from the top of the direct heat exchanger 4. A coke loading buffer tank 3 is installed above the direct heat exchanger 4, and is connected to the secondary heat exchanger via a vertical channel with a square cross-section. High-temperature coke at 1050℃ first enters the coke loading buffer tank 3, and then enters the direct heat exchanger 4 through the vertical channel between the coke loading buffer tank 3 and the direct heat exchanger 4, directly contacting and exchanging heat with the circulating hydrogen gas. After the coke is cooled to 135℃, it is discharged from the bottom of the secondary heat exchanger. A blower 10 is connected to the bottom of the coke loading buffer tank 3 via a pipe, maintaining zero pressure or a slight negative pressure (0Pa to -10Pa) at the connection point between the bottom of the coke loading buffer tank 3 and the blower 10. The gas discharged by the blower 10 can be used for supplementary heating of the coke oven head.

[0068] S3, 985℃ circulating hydrogen, carrying coke powder, exits from the top of the direct heat exchanger 4 and enters the gravity settling chamber 5, which is equipped with a baffle. The dimensions of the gas flow cross-sectional area of ​​the gravity settling chamber 5 are designed to ensure that the coke powder content of the circulating hydrogen is 20g / m³. 3 Then it enters the cyclone dust collector 6, and the high-temperature circulating hydrogen from the cyclone dust collector 6 enters the reduction furnace 1 to reduce the iron ore.

[0069] S4. Coke powder exiting the cyclone dust collector 6 enters a gasifier 7. During the initial startup phase, a certain amount of oxygen is introduced into the gasifier 7, causing partial oxidation of the coke powder entering the combustion furnace to produce CO. This CO gas is then used as carburizing gas, pressurized by the booster unit 9, and introduced into the carburizing zone below the reduction furnace 1 to carburize the sponge iron. The tail gas containing CO and CO2 after carburizing is recycled back to the gasifier 7, continuously gasifying the coke powder entering the gasifier 7 to replenish the carburizing gas. The carburizing gas is pressurized by the booster unit 9 before entering the carburizing zone to carburize the sponge iron. The gasifier 7 is electrically heated, with an internal temperature of 1300℃. After carburizing, the sponge iron product has a metallization rate of 94.5% and a carbon content of 4%.

[0070] Example 3

[0071] like Figure 1As shown, this example provides a method for producing direct reduced iron using all-hydrogen, including the following process equipment: an iron ore reduction furnace 1, a direct heat exchanger for high-temperature coke and hydrogen 4, a coke loading buffer tank 3, a gravity settling chamber 5, a cyclone dust collector 6, a coke powder gasification furnace 7, a circulating hydrogen cooling, dehydration and dust removal system 2 for water vapor from the reduction furnace 1, a booster compressor 8, a booster unit 9, etc. The iron ore includes pellets, carbon-containing pellets, lump ore, etc., and the hydrogen sources include hydrogen production from water electrolysis, hydrogen production from natural gas, hydrogen production from coal, hydrogen production from raw coal gas, hydrogen production from heavy oil, hydrogen production from biomass, etc.

[0072] This example provides a method for producing direct reduced iron using all-hydrogen, including the following steps:

[0073] S1, the circulating hydrogen from the reduction furnace 1 enters the hydrogen circulation system, and is cooled to 80°C by the cooling, dehydration and dust removal system 2. At the same time, the water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen is pressurized by the booster 8 and then mixed with the low-temperature and high-pressure hydrogen in the hydrogen circulation system before entering the direct heat exchanger 4. In the above process, low-temperature and high-pressure hydrogen is added to the hydrogen circulation system for reduction.

[0074] S2, mixed hydrogen gas is evenly distributed through a gas distribution plate at the bottom of the direct heat exchanger 4 and then enters the direct heat exchanger 4. Low-temperature hydrogen gas flows upward through the coke gaps, directly exchanging heat with the high-temperature coke. The circulating hydrogen gas is heated to 935℃ and discharged from the top of the direct heat exchanger 4. A coke loading buffer tank 3 is installed above the direct heat exchanger 4, and is connected to the secondary heat exchanger via a vertical channel with a square cross-section. 1000℃ high-temperature coke first enters the coke loading buffer tank 3, and then enters the direct heat exchanger 4 through the vertical channel between the coke loading buffer tank 3 and the direct heat exchanger 4, directly contacting and exchanging heat with the circulating hydrogen gas. After the coke is cooled to 115℃, it is discharged from the bottom of the secondary heat exchanger. A blower 10 is connected to the bottom of the coke loading buffer tank 3 via a pipe, maintaining zero pressure or a slight negative pressure (0Pa to -10Pa) at the connection point between the bottom of the coke loading buffer tank 3 and the blower 10. The gas discharged by the blower 10 can be used for supplementary heating of the coke oven head.

[0075] S3, 935℃ circulating hydrogen, carrying coke powder, exits from the top of the direct heat exchanger 4 and enters the gravity settling chamber 5, which is equipped with a baffle. The dimensions of the gas flow cross-sectional area of ​​the gravity settling chamber 5 are designed to ensure that the coke powder content of the circulating hydrogen is 10g / m³. 3 Then it enters the cyclone dust collector 6, and the high-temperature circulating hydrogen from the cyclone dust collector 6 enters the reduction furnace 1 to reduce the iron ore.

[0076] S4. Coke powder exiting the cyclone dust collector 6 enters a gasifier 7. During the initial startup phase, a certain amount of oxygen is introduced into the gasifier 7, causing partial oxidation of the coke powder entering the combustion furnace to produce CO. This CO gas is then used as carburizing gas, pressurized by the booster unit 9, and introduced into the carburizing zone below the reduction furnace 1 to carburize the sponge iron. The tail gas containing CO and CO2 after carburizing is recycled back to the gasifier 7, continuously gasifying the coke powder entering the gasifier 7 to replenish the carburizing gas. The carburizing gas is pressurized by the booster unit 9 before entering the carburizing zone to carburize the sponge iron. The gasifier 7 is electrically heated, with an internal temperature of 1290℃. After carburizing, the sponge iron product has a metallization rate of 93.6% and a carbon content of 2.5%.

[0077] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for producing direct reduced iron using all-hydrogen, characterized in that, The circulating hydrogen from the reduction furnace enters the hydrogen circulation system. After being cooled and dehydrated, it directly exchanges heat with the high-temperature coke produced in the coking process. The high-temperature circulating hydrogen after heat exchange carries coke powder. After gravity settling and cyclone dust removal to remove the coke powder, the high-temperature circulating hydrogen enters the reduction zone of the reduction furnace to participate in the reduction of iron-containing materials to obtain sponge iron. The coke powder obtained after cyclone dust removal enters the gasifier of the carburizing system and is oxidized into CO. Then, it enters the carburizing zone of the reduction furnace as carburizing gas to complete the carburizing of sponge iron.

2. The method for producing direct reduced iron using all-hydrogen according to claim 1, characterized in that, Includes the following steps: S1, the circulating hydrogen from the reduction furnace enters the hydrogen circulation system and is cooled to 80℃±10℃ by the cooling, dehydration and dust removal system. At the same time, the water vapor in the circulating hydrogen condenses into water and is separated from the circulating hydrogen. The dehydrated circulating hydrogen is pressurized and then enters the direct heat exchanger. S2, after dehydration, the circulating hydrogen is evenly distributed through the gas distribution plate at the bottom of the direct heat exchanger and then enters the direct heat exchanger. The low-temperature circulating hydrogen flows upward through the coke gaps and directly exchanges heat with the high-temperature coke produced by the coking oven in the coking process. The circulating hydrogen is heated to 960℃±25℃ and then discharged from the top of the direct heat exchanger. The high-temperature coke is cooled to 120±20℃ and then discharged from the bottom of the direct heat exchanger. S3, the heated high-temperature circulating hydrogen gas, carrying coke powder, exits from the top of the direct heat exchanger. After settling in the gravity settling chamber, the coke powder content carried by the high-temperature circulating hydrogen gas is reduced to 10 g / m³. 3 ~20g / m 3 Then it enters the cyclone dust collector, and the high-temperature circulating hydrogen gas after removing coke powder enters the reduction zone of the reduction furnace to participate in the reduction of iron-containing materials to obtain sponge iron. S4, the coke powder coming out of the cyclone dust collector enters the gasifier. In the initial stage of startup, the coke powder is oxidized to CO under the action of oxygen. The CO gas is used as carburizing gas and is pressurized by the pressurization unit and introduced into the carburizing zone of the reduction furnace to complete the carburizing of the sponge iron. S5, the tail gas containing CO and CO2 after carburizing is recycled to the gasifier. The coke powder in the gasifier is gasified and used as carburizing gas. After being pressurized by the pressurization unit, it enters the carburizing area to participate in the carburizing of sponge iron.

3. The method for producing direct reduced iron using all-hydrogen according to claim 2, characterized in that, In step S1, low-temperature high-pressure hydrogen is added to the hydrogen circulation system. The added hydrogen is mixed with the hydrogen pressurized by the booster and then enters the direct heat exchanger.

4. The method for producing direct reduced iron using all-hydrogen according to claim 2, characterized in that, In step S2, high-temperature coke at 1025℃±25℃ first enters the coke loading buffer tank, and then enters the direct heat exchanger through the vertical channel between the coke loading buffer tank and the direct heat exchanger, where it directly contacts and exchanges heat with circulating hydrogen. After being cooled to 120℃±20℃, the high-temperature coke is discharged from the bottom of the direct heat exchanger. The bottom of the coke loading buffer tank is connected to an exhaust fan, which maintains zero pressure or a slight negative pressure of 0Pa to -10Pa at the connection between the bottom of the coke loading buffer tank and the exhaust fan.

5. The method for producing direct reduced iron using all-hydrogen according to claim 2, characterized in that, In step S4, the gasification furnace is electrically heated, and the furnace temperature is 1285±15℃.

6. The method for producing direct reduced iron using all-hydrogen according to claim 2, characterized in that, In step S4, the metallization rate of the carburized sponge iron is ≥93%, and the carbon content is 3%±1%.

7. An apparatus for producing direct reduced iron using all-hydrogen, comprising a reduction furnace, the top of which is provided with a feed inlet and a gas outlet; the upper part of the reduction furnace is provided with a reduction zone, and the lower part is provided with a carburizing zone; characterized in that, Also includes: The hydrogen circulation system includes a cooling dehydration and dust removal system, a booster compressor, a direct heat exchanger, a gravity settling chamber, and a cyclone dust collector connected by pipelines; the cooling dehydration and dust removal system is connected to the outlet of the reduction furnace; the direct heat exchanger is used for direct heat exchange between circulating hydrogen and high-temperature coke; the top outlet of the cyclone dust collector is connected to the hydrogen inlet of the reduction zone of the reduction furnace. The carburizing system includes a gasifier and a pressurization unit; the gas inlet at the bottom of the gasifier is connected to the carburizing gas outlet at the top of the carburizing zone of the reduction furnace, the gas outlet at the top of the gasifier is connected to the pressurization unit, and the top of the gasifier is connected to the cyclone dust collector. The gasifier is used to oxidize the coke powder coming out of the cyclone dust collector to obtain carburizing gas; the pressurization unit is connected to the carburizing gas inlet at the bottom of the carburizing zone of the reduction furnace. The apparatus for producing direct reduced iron with all hydrogen is used to perform the method for producing direct reduced iron with all hydrogen as described in any one of claims 1-6.

8. The apparatus for producing direct reduced iron using all-hydrogen according to claim 7, characterized in that, A coke loading buffer tank is provided above the direct heat exchanger, and the coke loading buffer tank is connected to the direct heat exchanger through a vertical channel; a fan is connected to the bottom of the coke loading buffer tank through a pipe.

9. The apparatus for producing direct reduced iron from all hydrogen according to claim 7, characterized in that, The bottom of the direct heat exchanger is provided with a gas distribution plate for uniformly distributing the gas.

10. The apparatus for producing direct reduced iron using all-hydrogen according to claim 7, characterized in that, The gravity settling chamber has an air inlet in the middle that is connected to the direct heat exchanger, an air outlet at the top of the gravity settling chamber, and a baffle wall inside the gravity settling chamber to separate the air inlet and the air outlet.

11. The apparatus for producing direct reduced iron from all hydrogen according to claim 10, characterized in that, The hydrogen circulation system also includes a hydrogen replenishment mechanism, which is connected to the pipeline between the booster and the direct heat exchanger via a hydrogen replenishment pipeline, and is also connected to the hydrogen production device.

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