Air supply method of hydrogen-rich carbon circulating oxygen blast furnace

Abstract

The invention discloses an air supply method of a hydrogen-carbon-rich circulating oxygen blast furnace. The air supply method comprises the following steps: starting the hydrogen-carbon-rich circulating oxygen blast furnace, performing decarburization, preliminarily establishing self-circulation, wherein the air supply ratio is greater than or equal to 0.40 and less than or equal to 0.70, keeping nitrogen flow unchanged, increasing the flow of oxygen and decarburized coal gas to improve the air supply ratio, and completing self-circulation establishment at a self-circulation medium-term stage. The invention discloses an air supply method for a hydrogen-carbon-rich circulating oxygen blast furnace. The air supply method comprises the following steps: starting the hydrogen-carbon-rich circulating oxygen blast furnace, decarburizing, preliminarily establishing self-circulation according to an air supply ratio of more than 0.70 and less than 1.20, keeping the oxygen flow unchanged, increasing the decarburized gas flow to reduce the nitrogen flow, performing a self-circulation medium-term stage and completing the establishment of the self-circulation. The invention discloses an air supply method of a hydrogen-rich carbon circulating oxygen blast furnace. The air supply method comprises the steps of first decarburization, starting of the hydrogen-rich carbon circulating oxygen blast furnace, second decarburization, preliminary establishment of self-circulation, middle-term stage of the self-circulation and completion of establishment of the self-circulation. According to the method, the blast furnace is rapidly transited to the normal production state from the damping-down state in a low-cost mode.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of blast furnace ironmaking, and particularly relates to a blast method of a hydrogen-rich carbon-cycling oxygen blast furnace. BACKGROUND

[0002] Steel is a carbon emission industry that is focused on by countries around the world, and is also an important field for implementing carbon emission reduction. China, as a world center for steel production and consumption, accounts for more than half of the global crude steel output, and accounts for about 15% of the total carbon emissions in China, which is one of the manufacturing industries with high carbon emissions.

[0003] Based on years of extensive research, China Baowu has developed a hydrogen-rich carbon-cycling oxygen blast furnace (HyCROF) ironmaking new process based on the long process of blast furnace-converter. The process recycles the coal gas produced by the traditional blast furnace after compression and removal of carbon dioxide and other complex processes back to the blast furnace. Since the process can achieve complete utilization of carbon chemical energy through carbon cycling, it can greatly reduce carbon emissions and fuel consumption in the ironmaking process. In July 2022, the world's first industrial-scale HyCROF test device was officially commissioned and put into operation at Xinjiang Bayi Steel (hereinafter referred to as "Bayi Steel"), and the test has achieved phased results. Then in late 2023, the 2500 cubic meter hydrogen-rich carbon-cycling oxygen blast furnace (HyCROF) commercial demonstration project of Bayi Steel has realized the full connection of full-oxygen smelting and coal gas self-circulation process. This project marks a major breakthrough in the green and low-carbon transformation of traditional long-process steelmaking.

[0004] However, how to blast the hydrogen-rich carbon-cycling oxygen blast furnace (HyCROF) to restart the hydrogen-rich carbon-cycling oxygen blast furnace from the idle stop state and restore the normal production process has not yet formed a complete system. Therefore, in the face of the newly proposed "hydrogen-rich carbon-cycling oxygen blast furnace ironmaking" new process, most production technicians simulate the blast method of the conventional traditional blast furnace, for example, using oxygen and nitrogen, mixing the two according to the air ratio, and then heating the mixed gas to obtain hot air, which is blown into the hydrogen-rich carbon-cycling oxygen blast furnace from the tuyere. After the blast volume at the tuyere reaches the target blast volume (the target blast volume is usually the blast volume in the normal production state of the blast furnace) and the furnace condition is established, the top coal gas produced by the blast furnace is continuously circulated and blown into the hydrogen-rich carbon-cycling oxygen blast furnace, while the flow of nitrogen is gradually reduced until the flow of nitrogen is reduced to 0, thereby starting the normal production mode of HyCROF.

[0005] However, the existing air supply method takes a long time to transition from a conventional blast furnace to the air supply of the HyCROF normal production mode, which results in a late time for continuously circulating and blowing the top coal gas generated by the hydrogen-rich carbon-circulation oxygen blast furnace into the blast furnace from the tuyere, thereby causing a high carbon (i.e., coke) consumption during the air supply process. In addition, as the furnace capacity becomes larger, the long air supply time also leads to a larger amount of nitrogen consumed during the air supply process, thereby causing a significant increase in production costs and affecting the competitiveness of the new process in the future. Therefore, how to air supply the hydrogen-rich carbon-circulation oxygen blast furnace in a low-cost manner to quickly transition from the idle state to the normal production state to start the HyCROF normal production mode becomes a technical problem to be solved. SUMMARY

[0006] The present application provides the following technical solutions to solve the above technical problems.

[0007] The present application provides a method for air supply of a hydrogen-rich carbon-circulation oxygen blast furnace, comprising:

[0008] Starting the hydrogen-rich carbon-circulation oxygen blast furnace: introducing oxygen and nitrogen into the hydrogen-rich carbon-circulation oxygen blast furnace after idling, starting the hydrogen-rich carbon-circulation oxygen blast furnace for ironmaking, obtaining top coal gas, and then increasing the flow rates of the oxygen and the nitrogen according to the capacity of the hydrogen-rich carbon-circulation oxygen blast furnace to receive air, thereby increasing the air supply ratio, which represents the ratio of the total flow rate of the gas introduced into the hydrogen-rich carbon-circulation oxygen blast furnace to the volume of the blast furnace, the unit of the total flow rate of the gas is Nm 3 / min, and the unit of the volume of the hydrogen-rich carbon-circulation oxygen blast furnace is m 3 ; wherein the increment of the oxygen flow rate each time is △b1;

[0009] Decarburization: collecting the top coal gas and decarburizing the top coal gas to obtain decarburized coal gas, so that the volume fraction of CO2 in the decarburized coal gas is <5%;

[0010] Preliminary establishment of self-circulation: when the air supply ratio satisfies 0.40≤air supply ratio≤0.70, the nitrogen flow rate is kept unchanged, the decarburized coal gas is introduced into the hydrogen-rich carbon-circulation oxygen blast furnace, and the flow rates of the oxygen and the decarburized coal gas are increased to increase the air supply ratio; wherein the increment of the decarburized coal gas flow rate each time is △a1, and the increment of the oxygen flow rate each time is △b2;

[0011] Mid stage of self-circulation: when the blast ratio meets 0.7 < blast ratio < 1.20, open the tap hole of the hydrogen-rich carbon-circulation oxygen blast furnace to obtain molten iron, while keeping the oxygen flow unchanged, increase the flow of the decarburized coal gas and reduce the flow of the nitrogen gas to maintain the blast ratio unchanged until the flow of the nitrogen gas is reduced to 0; then continue to increase the flow of the oxygen and the decarburized coal gas to increase the blast ratio; wherein the increment of the flow of the decarburized coal gas is △a2 each time, and the increment of the flow of the oxygen is △b3 each time;

[0012] After the self-circulation is established: when the blast ratio is greater than or equal to 1.2, continue to increase the flow of the oxygen and the decarburized coal gas to increase the blast ratio until the total flow of the gas introduced into the hydrogen-rich carbon-circulation oxygen blast furnace reaches the target blast volume, wherein the increment of the flow of the decarburized coal gas is △a3 each time, and the increment of the flow of the oxygen is △b4 each time, △a3 < △a1 and △a3 < △a2; △b4 < △b1, △b4 < △b2 and △b4 < △b3, and the target blast volume is the blast volume introduced into the hydrogen-rich carbon-circulation oxygen blast furnace in the normal production state.

[0013] By adopting the technical scheme, the hydrogen-rich carbon-circulation oxygen blast furnace is blown in at a low cost while achieving a large reduction in carbon emissions, and the hydrogen-rich carbon-circulation oxygen blast furnace is quickly transitioned from the idle state to the normal production state to start the HyCROF normal production mode, which provides a feasible solution for the popularization and landing of the subsequent HyCROF new process and the low-carbon transformation of the blast furnace long process.

[0014] The application further provides a blast method of a hydrogen-rich carbon-circulation oxygen blast furnace, which comprises:

[0015] Starting the hydrogen-rich carbon-circulation oxygen blast furnace: introducing oxygen and nitrogen into the hydrogen-rich carbon-circulation oxygen blast furnace after idling, starting the hydrogen-rich carbon-circulation oxygen blast furnace to smelt iron, obtaining top coal gas, and then increasing the flow of the oxygen and the nitrogen according to the capacity of the blast furnace to receive the blast volume, thereby increasing the blast ratio, wherein the blast ratio represents the ratio of the total flow of the gas introduced into the hydrogen-rich carbon-circulation oxygen blast furnace to the volume of the blast furnace, the unit of the total flow of the gas is Nm 3 / min, and the unit of the volume of the hydrogen-rich carbon-circulation oxygen blast furnace is m 3 ; wherein the increment of the flow of the oxygen is △b1 each time.

[0016] Decarburization: collecting the top coal gas and decarburizing the top coal gas to obtain decarburized coal gas, so that the volume fraction of CO2 in the decarburized coal gas is less than 5%;

[0017] Initial establishment of self-circulation: When the air supply ratio meets the condition of 0.70 < air supply ratio < 1.20, the blast furnace taphole is opened to tap molten iron. At the same time, the oxygen flow rate is kept constant, decarburized gas is introduced into the blast furnace and the flow rate of the decarburized gas is increased, while the nitrogen flow rate is decreased to maintain a constant air supply ratio until the flow rate of the introduced nitrogen is reduced to 0. The increment of the decarburized gas flow rate is Δa1 each time.

[0018] Mid-cycle stage: Continue to increase the oxygen flow rate and the decarbonized gas flow rate to improve the air supply ratio; wherein, the increment of the decarbonized gas flow rate is △a2 each time, and the increment of the oxygen flow rate is △b2 each time;

[0019] Self-circulation established: Once the air supply ratio is ≥1.2, continue to increase the flow rates of oxygen and decarbonized gas to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume. The increment of the decarbonized gas flow rate each time is Δa3, where Δa3 < Δa1 and Δa3 < Δa2; the increment of the oxygen flow rate each time is Δb3, where Δb3 < Δb1 and Δb3 < Δb2; the target air volume is the air volume introduced into the hydrogen-rich carbon-circulating oxygen blast furnace under normal production conditions.

[0020] By adopting the above technical solution, it is possible to supply air to the hydrogen-rich carbon-recirculating oxygen blast furnace in a low-cost and simple operation mode, so that it can quickly transition from the shutdown state to the normal production state and start the normal production mode of HyCROF. This provides a practical solution for the subsequent promotion and implementation of the new HyCROF process and the realization of the low-carbon transformation of the long process of blast furnace.

[0021] Optionally, in the step of starting the hydrogen-rich carbon-circulating oxygen blast furnace, the volume flow ratio of oxygen and nitrogen introduced is maintained at 1:5 to 1:3. In the step of initial self-circulation establishment, decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the volume flow ratio of oxygen and decarbonized gas is maintained at 1:5 to 1:3 to increase the flow rate of oxygen and decarbonized gas.

[0022] Optionally, the self-circulating intermediate stage further includes: when the flow rate of the nitrogen to be introduced is reduced to 0, the flow rate of the decarbonized gas and the flow rate of oxygen are kept constant until the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%, and then the flow rate of oxygen and the flow rate of decarbonized gas are increased to improve the air supply ratio.

[0023] Optionally, when the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30% during the intermediate stage of the self-circulation, the oxygen flow rate and the decarbonized gas flow rate are increased by maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3; and in the self-circulation establishment completion step, the oxygen flow rate and the decarbonized gas flow rate are increased by maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3.

[0024] Optionally, the decarbonization step further includes: detecting the total pressure of the introduced oxygen and nitrogen and the total pressure of the generated top coal gas, wherein the total pressure of the oxygen and nitrogen is P1 and the total pressure of the top coal gas is P2; when P1≥60kpa and P2≥10kpa, the top coal gas is collected and decarbonized to obtain decarbonized coal gas.

[0025] Optionally, a dust removal step is further included between the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace and the decarbonization step. The dust removal step includes: collecting the top gas and removing dust from the top gas to filter out dust.

[0026] Optionally, a pressurization step is further included between the start-up of the hydrogen-rich carbon-cycle oxygen blast furnace and the decarbonization step. The pressurization step includes: collecting the top gas, pressurizing the top gas, and then decarbonizing the pressurized top gas.

[0027] Optionally, the self-circulation establishment completion step further includes: the volume fraction of N2 in the top gas is <20%.

[0028] The present invention also provides a method for supplying air to a hydrogen-rich carbon-circulating oxygen blast furnace, comprising:

[0029] First decarbonization: The pipeline gas is introduced into the decarbonization device to perform the first decarbonization to obtain the first decarbonized gas, so that the volume fraction of CO2 in the first decarbonized gas is <5%. The pipeline gas is one or more of blast furnace gas, coke oven gas or converter gas.

[0030] Starting the hydrogen-rich carbon-circulating oxygen blast furnace: After shutdown, the oxygen and the first decarbonized gas are introduced into the hydrogen-rich carbon-circulating oxygen blast furnace to start ironmaking and obtain top gas. Then, based on the blast furnace's blast capacity, the flow rates of the oxygen and the first decarbonized gas are increased, thereby increasing the blast ratio. The blast ratio represents the ratio of the total gas flow rate into the hydrogen-rich carbon-circulating oxygen blast furnace to the furnace's volume. The unit of the total gas flow rate is Nm³. 3 / min, the volume of the hydrogen-rich carbon-circulating oxygen blast furnace is in m³. 3Wherein, the increment of the first decarbonized coal gas flow rate each time is Δc1, and the increment of the oxygen flow rate each time is Δd1;

[0031] Second decarbonization: Collect the top coal gas and decarbonize the top coal gas to obtain second decarbonized coal gas, such that the volume fraction of CO2 in the second decarbonized coal gas is <5%;

[0032] Preliminary establishment of self-circulation: A second decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the flow rate of the oxygen and the flow rate of the first decarbonized gas are increased to improve the air supply ratio; wherein, the increment of the flow rate of the first decarbonized gas each time is Δc2, and the increment of the flow rate of the oxygen each time is Δd2.

[0033] Mid-cycle stage: When the air supply ratio meets the condition of 0.70 < air supply ratio < 1.20, the tap hole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron. At the same time, the oxygen flow rate is kept constant, the flow rate of the second decarburized gas is increased, and the flow rate of the first decarburized gas is decreased to maintain the air supply ratio constant until the flow rate of the first decarburized gas decreases to 0. After that, the oxygen flow rate and the flow rate of the second decarburized gas are increased to improve the air supply ratio. The increment of the second decarburized gas flow rate each time is Δc3, and the increment of the oxygen flow rate each time is Δd3.

[0034] Self-circulation established: When the air supply ratio is ≥1.2, continue to increase the flow rates of oxygen and the second decarbonized gas to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume. The increment of the second decarbonized gas flow rate each time is Δc4, and the increment of the oxygen flow rate each time is Δd4, where Δc4 < Δc1, Δc4 < Δc2, and Δc4 < Δc3; Δd4 < Δd1, Δd4 < Δd2, and Δd4 < Δd3. The target air volume is the air volume introduced into the hydrogen-rich carbon-circulating oxygen blast furnace under normal production conditions. The shutdown time of the hydrogen-rich carbon-circulating oxygen blast furnace is ≤20 hours.

[0035] By adopting the above technical solution, not only can the production cost be further reduced, but the hydrogen-rich carbon circulating oxygen blast furnace can also quickly transition from a short shutdown state (shutdown time ≤ 20h) to a normal production state to start the normal production mode of HyCROF.

[0036] Optionally, in the step of starting the hydrogen-rich carbon-circulating oxygen blast furnace, the volume flow ratio of the introduced oxygen and the first decarbonized gas is maintained at 1:5 to 1:3. In the step of initially establishing self-circulation, the second decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the volume flow ratio of the oxygen and the first decarbonized gas is maintained at 1:5 to 1:3 to increase the flow rate of the oxygen and the first decarbonized gas.

[0037] Optionally, the self-circulating intermediate stage further includes: when the flow rate of the first decarbonized gas decreases to 0, keeping the flow rate of the second decarbonized gas and the oxygen flow rate unchanged until the volume fraction of CO2 in the second decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%, and then continuing to increase the oxygen flow rate and the flow rate of the second decarbonized gas to increase the air supply ratio.

[0038] Optionally, when the volume fraction of CO2 in the second decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30% during the mid-stage of the self-circulation, the oxygen flow rate and the second decarbonized gas flow rate are increased while maintaining the volume flow rate ratio of oxygen to second decarbonized gas at 1:5 to 1:3.

[0039] Optionally, a dust removal step is included before the first decarbonization step, the first dust removal step including: introducing pipeline gas into a dust removal device for dust removal to filter dust.

[0040] Optionally, the second decarbonization step further includes: detecting the total pressure of the introduced oxygen and the first decarbonized gas and the total pressure of the generated top gas, wherein the total pressure of the oxygen and the first decarbonized gas is P3, and the total pressure of the top gas is P4; when P3 ≥ 60 kPa and P4 ≥ 10 kPa, the top gas is collected, and the top gas is subjected to a second decarbonization to obtain a second decarbonized gas.

[0041] Optionally, a dust removal step is further included between the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace and the second decarbonization step. The dust removal step includes: collecting the top gas and removing dust from the top gas to filter out dust.

[0042] Optionally, before starting the hydrogen-rich carbon-cycle oxygen blast furnace and the second decarbonization step, a pressurization step is further included. The pressurization step includes: collecting the top gas, pressurizing the top gas, and then performing a second decarbonization on the pressurized top gas.

[0043] Optionally, the self-circulation complete establishment step further includes: the volume fraction of N2 in the top gas is <20%. Attached Figure Description

[0044] Figure 1 A schematic diagram of the process flow and process equipment of the air supply method for a hydrogen-rich carbon circulating oxygen blast furnace according to an embodiment of the present invention is shown.

[0045] Figure 2 A schematic diagram of the process flow and process equipment of the air supply method for a hydrogen-rich carbon circulating oxygen blast furnace according to another embodiment of the present invention is shown.

[0046] (Symbol Explanation)

[0047] 1-Top gas dust removal device; 2-Gas compressor; 3-Decarbonization device; 4-Gas injection valve station; 5-Gas heating device; 6-Gas pipeline network; 7-Smelting furnace Detailed Implementation

[0048] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0049] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0051] Shutdown of a hydrogen-rich carbon-circulating oxygen blast furnace refers to the temporary cessation of production operations due to planned maintenance, equipment failure, or other reasons. Simultaneously, the injection of decarbonized gas, oxygen, nitrogen, or any other gases into the furnace is stopped, and the blast furnace enters a shutdown state. After addressing production or equipment issues during the shutdown, air needs to be reintroduced to restore normal production. However, during the initial air induction phase, the tuyeres of the blast furnace have a strong capacity to receive air. As the air volume increases, the capacity decreases. Therefore, the initial air induction pace and magnitude can be appropriately faster and larger, but the pace and magnitude should be appropriately slowed down and reduced in the later stages of air induction to ensure a smooth and stable furnace operation, i.e., a return to normal production. Because the "hydrogen-rich carbon-circulating oxygen blast furnace" process is newly proposed, the related air induction technology is still under development and in the exploratory stage. To be on the safe side, the production technicians used the traditional blast furnace ironmaking air supply method.

[0052] As mentioned in the background section, existing technologies often continuously introduce nitrogen and oxygen into a hydrogen-rich carbon-circulating oxygen blast furnace until the air volume reaches the target air volume and the furnace operation is established. Only then does the nitrogen usage begin to decrease, and top gas is gradually injected into the furnace from the tuyeres to establish self-circulation. In short, the existing air supply method can be simply summarized as: "Introducing nitrogen and oxygen into a hydrogen-rich carbon-circulating oxygen blast furnace until the air volume at the tuyeres reaches the target air volume - reducing the nitrogen flow rate until it reaches zero, while simultaneously introducing top gas into the blast furnace - establishing furnace operation (self-circulation established)." Because the top gas is injected into the hydrogen-rich carbon-circulating oxygen blast furnace too late, carbon (i.e., coke) consumption is high during the air supply process. Furthermore, because nitrogen usage is only reduced after the target air volume is reached, the initial nitrogen consumption is high. This high nitrogen consumption not only results in excessively high production costs but also significantly lengthens the time required to reduce it to zero.

[0053] Therefore, the inventors hope to propose a practical technical solution that can supply air to the hydrogen-rich carbon-cycle oxygen blast furnace, enabling it to transition to normal production mode. However, the circulation system is quite complex. What conditions should be adjusted, and how should they be adjusted, to ensure the establishment of circulation and accelerate the establishment of self-circulation, to ensure the smooth progress of the reaction, and to reduce the use of nitrogen, ultimately achieving complete self-circulation through the generated top gas? The design of the above-mentioned air supply method is a huge system engineering project with complex internal reaction processes. Any change in parameters may cause changes to the entire circulation and reaction processes, making the design very difficult.

[0054] Based on this, and through the design of multiple cyclic conditions and numerous experiments, the present invention provides the following technical solution to solve the above-mentioned technical problems.

[0055] This invention provides a method for supplying air to a hydrogen-rich carbon-circulating oxygen blast furnace, comprising:

[0056] Starting a hydrogen-rich carbon-circulating oxygen blast furnace: After shutdown, oxygen and nitrogen are introduced into the hydrogen-rich carbon-circulating oxygen blast furnace to start ironmaking and obtain top gas. Then, the flow rates of oxygen and nitrogen are increased according to the blast furnace's blast capacity, thereby increasing the blast ratio. The blast ratio represents the ratio of the total gas flow rate into the hydrogen-rich carbon-circulating oxygen blast furnace to the blast furnace volume. The unit of the total gas flow rate is Nm³. 3 / min, the unit of volume of a hydrogen-rich carbon-circulating oxygen blast furnace is m³. 3 The increment of the oxygen flow rate for each increase is Δb1.

[0057] Decarbonization: Collect the top coal gas and decarbonize it to obtain decarbonized coal gas, so that the volume fraction of CO2 in the decarbonized coal gas is <5%;

[0058] Initial establishment of self-circulation: When the air supply ratio meets the condition of 0.40≤air supply ratio≤0.70, keep the nitrogen flow rate constant, introduce decarbonized coal gas into the hydrogen-rich carbon-circulating oxygen blast furnace, and increase the flow rates of oxygen and decarbonized coal gas to improve the air supply ratio; wherein, the increment of the decarbonized coal gas flow rate each time is △a1, and the increment of the oxygen flow rate each time is △b2.

[0059] Mid-stage of self-circulation: When the air supply ratio meets the condition of 0.7 < air supply ratio < 1.20, the blast furnace taphole is opened to obtain molten iron. At the same time, the oxygen flow rate is kept constant, the decarburized gas flow rate is increased, and the nitrogen flow rate is decreased to maintain the air supply ratio constant until the nitrogen flow rate is reduced to 0. After that, the oxygen flow rate and the decarburized gas flow rate are increased to improve the air supply ratio. The increment of the decarburized gas flow rate is Δa2 each time, and the increment of the oxygen flow rate is Δb3 each time.

[0060] Self-circulation established: Once the air supply ratio is ≥1.2, continue to increase the flow rates of oxygen and decarbonized gas to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume, which is the air supply ratio acceptable under normal production conditions, for example, an air supply ratio of 2. The increment of the decarbonized gas flow rate each time is △a3, and the increment of the oxygen flow rate each time is △b4, where △a3 < △a1 and △a3 < △a2; △b4 < △b1, △b4 < △b2 and △b4 < △b3. The target air volume is the air volume introduced into the hydrogen-rich carbon-circulating oxygen blast furnace under normal production conditions. Specifically, the increment of decarburized gas flow rate each time is lower than the increments of decarburized gas flow rate in the initial self-circulation establishment step and the intermediate self-circulation stage step; the increment of oxygen flow rate each time is lower than the increments of oxygen flow rate in the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace, the initial self-circulation establishment step, and the intermediate self-circulation stage step. The target air volume is the air volume supplied to the hydrogen-rich carbon-circulating oxygen blast furnace under normal production conditions. It should be noted that the above method is suitable for hydrogen-rich carbon-circulating oxygen blast furnaces with any shutdown time, especially those with a shutdown time of 48 hours or more.

[0061] The air supply method provided by this invention can be simply summarized as follows: "Introduce nitrogen and oxygen into the hydrogen-rich carbon-circulating oxygen blast furnace until the air supply ratio is 0.40 ≤ air supply ratio ≤ 0.70, introduce top coal gas into the blast furnace, and at the same time keep the nitrogen flow rate constant, increase the flow rate of decarbonized coal gas (decarbonized top coal gas) and oxygen - when 0.7 < air supply ratio < 1.20, reduce the nitrogen flow rate until it is reduced to 0 - increase the oxygen and decarbonized coal gas until the target air volume is reached - establish smooth furnace operation (self-circulation established)." The air supply method provided by this invention establishes self-circulation once the air volume at the tuyeres reaches the target air volume. In contrast, existing air supply methods only begin reducing nitrogen and introducing top gas into the hydrogen-rich carbon-circulating oxygen blast furnace after the target air volume is reached, which undoubtedly prolongs the air supply time. Furthermore, due to the continuous introduction of oxygen and nitrogen, the nitrogen flow rate introduced into the hydrogen-rich carbon-circulating oxygen blast furnace is significantly higher when the target air volume is reached. This inevitably leads to an excessively long time required to reduce the high nitrogen content to zero. In this invention, the nitrogen flow rate remains constant when the air supply ratio is between 0.40 and 0.70, and is reduced until it reaches zero when the air supply ratio is between 0.7 and 1.20. Therefore, compared to existing air supply methods, this invention requires less nitrogen initially, reducing production costs. Additionally, the reduced nitrogen content significantly shortens the time required to reduce it to zero. Furthermore, since the present invention introduces the top gas into the hydrogen-rich carbon-cycle oxygen blast furnace when the air supply ratio is 0.40≤0.70, and the top gas contains a large amount of reducing gas CO, which can be used to reduce iron ore, the earlier introduction of CO can also reduce the coke ratio (i.e., reduce coke consumption).

[0062] Therefore, the air supply method for hydrogen-rich carbon-circulating oxygen blast furnaces provided by this invention enables the furnace to quickly transition from a shutdown state to a normal production state at low cost. This provides a practical solution for the subsequent promotion and implementation of the HyCROF process, and for achieving the low-carbon transformation of long-process hydrogen-rich carbon-circulating oxygen blast furnaces. The process provided by this invention represents a new technological development trend.

[0063] The following is combined with Figure 1 This will further elaborate on the above technical solutions and their effects.

[0064] like Figure 1 As shown, nitrogen gas is introduced at gas injection valve station 4. The introduced nitrogen gas is heated to over 1200℃ by gas heating device 5 and then enters the smelting furnace 7 through the tuyeres. At the same time, room temperature oxygen is also introduced into the hydrogen-rich carbon-circulating oxygen blast furnace through the tuyeres, and the hydrogen-rich carbon-circulating oxygen blast furnace is started to produce ironmaking gas. The time when oxygen is introduced through the tuyeres is the start time of air supply.

[0065] The introduced oxygen reacts with the coke to produce carbon dioxide, releasing a large amount of heat. The carbon dioxide is then rapidly reduced to CO, which can be used to reduce iron ore to produce iron and CO2. Because the contact time between the gas and the furnace charge is extremely short (about 8 seconds), a large amount of CO is discharged directly from the top of the furnace before it can reduce the iron ore. Therefore, the top gas contains a large amount of CO, N2, and a small amount of CO2. In addition, because iron ore contains water of crystallization, the top gas also contains some hydrogen and other gases.

[0066] Furthermore, as nitrogen and oxygen are continuously introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, the furnace's ability to receive blast air decreases. Therefore, this invention increases the flow rates of oxygen and nitrogen based on the blast air receiving capacity of the hydrogen-rich carbon-circulating oxygen blast furnace, thereby improving the blast ratio. The blast ratio represents the ratio of the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace to the volume of the furnace; the unit of the total gas flow rate is Nm³. 3 / min ("N" stands for "Normal", meaning the flow rate is the volumetric flow rate under standard atmospheric pressure), the unit of volume for a hydrogen-rich carbon-cycle oxygen blast furnace is m³ / min. 3 Specifically, as the air volume supplied to the tuyere increases, the tuyere's ability to receive air volume becomes weaker and weaker. Therefore, the frequency of increasing the amount of oxygen and nitrogen in the early stage of air supply can be appropriately faster. That is, as long as the actual value reaches the set value, it can continue to be increased. Since the N2 content in the top gas generated in the early stage is too high and it does not have the conditions for self-circulation, the top gas is released from the gas venting tower at the top of the furnace in the early stage of air supply.

[0067] Since the top gas also contains CO2, and CO2 consumes coke, the CO2 concentration in the top gas needs to be reduced before it is introduced into the hydrogen-rich carbon-cycle oxygen blast furnace. Therefore, this invention collects the top gas and introduces it into a decarbonization device 3 to remove CO2, thus obtaining decarbonized gas. The decarbonization device 3 can employ the activated MDEA (activated methyl diethanolamine) decarbonization process to absorb carbon dioxide from the top gas, but is not limited to this method. Other methods include pressure swing adsorption (PSA), temperature swing adsorption (TSA), membrane separation, polyethylene glycol dimethyl ether (Selexol), low-temperature methanol washing (Rectisol), and hot potassium carbonate processes. After decarbonization using the above processes, the volume fraction of CO2 in the decarbonized gas can be reduced to below 5%.

[0068] Furthermore, in the process of starting the hydrogen-rich carbon-circulating oxygen blast furnace, the flow rates of oxygen and nitrogen are increased according to the furnace's blast capacity, with the volumetric flow rate ratio of the introduced oxygen and nitrogen maintained at 1:5 to 1:3. This invention simulates the oxygen and nitrogen concentrations in the blast during conventional blast furnace production in the early stages of blasting, maintaining the volumetric flow rate ratio of the introduced oxygen and nitrogen at 1:5 to 1:3, thereby avoiding excessively high oxygen enrichment and facilitating furnace condition recovery and smooth operation. Specifically, the volumetric flow rate ratio of oxygen and nitrogen is 1:5 to 1:4.

[0069] Further research revealed that before the air-to-gas ratio reaches 0.40, the N2 content in the decarbonized gas remains high, while the effective CO and H2 contents are low. Therefore, the quality of the decarbonized gas obtained after decarbonization by the aforementioned decarbonization device 3 is poor and needs to be vented through the vent pipe, temporarily not for recycling. When 0.40 ≤ air-to-gas ratio ≤ 0.70, the quality of the decarbonized gas gradually improves, and it can be introduced into the hydrogen-rich carbon-circulating oxygen blast furnace to initiate self-circulation. Specifically, the decarbonized gas can be introduced from the gas injection valve station 4, heated to over 1200℃ by the gas heating device 5, and then introduced into the smelting furnace 7 along with nitrogen through the tuyeres. At this time, the decarbonized gas is introduced into the furnace, and the CO in the decarbonized gas has strong reducing properties, so it can be used to reduce iron ore, thereby reducing the coke ratio. Then, the flow rates of oxygen and decarbonized gas are increased simultaneously to improve the air-to-gas ratio. In particular, 0.48 ≤ air-to-gas ratio ≤ 0.52.

[0070] Further research revealed that when the air-to-feed ratio is between 0.7 and 1.20, the nitrogen flow rate can be reduced. Specifically, when the air-to-feed ratio is between 0.7 and 1.20, the taphole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to tap molten iron, while maintaining a constant oxygen flow rate. The decarburized gas flow rate is increased, and the nitrogen flow rate is decreased to maintain a constant air-to-feed ratio until the nitrogen flow rate is reduced to 0. Specifically, the air-to-feed ratio should be between 0.98 and 1.02. Once the nitrogen flow rate is reduced to 0, the decarburized gas and oxygen flow rates are kept constant. The concentrations of N2 in the top gas and CO2 in the decarburized gas are monitored. When the volume fraction of CO2 in the decarburized gas is less than 3% and the volume fraction of N2 in the top gas is less than 30%, it indicates that the quality of the top gas produced in the hydrogen-rich carbon-circulating oxygen blast furnace is gradually improving. After this point, the oxygen and decarburized gas flow rates can be further increased to improve the air-to-feed ratio.

[0071] Furthermore, when the air supply ratio is ≥1.2, the flow rates of oxygen and decarbonized gas are continuously increased to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume (i.e., the target air supply ratio). Each increase in the decarbonized gas flow rate is lower than the increases in the decarbonized gas flow rate during the initial self-circulation establishment step and the mid-stage self-circulation phase. Each increase in the oxygen flow rate is also lower than the increases in the oxygen flow rate during the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace, the initial self-circulation establishment step, and the mid-stage self-circulation phase, i.e., Δa3 < Δa1 and Δa3 < Δa2; Δb4 < Δb1, Δb4 < Δb2, and Δb4 < Δb3. The target air volume is the air volume introduced into the hydrogen-rich carbon-circulating oxygen blast furnace during normal production. Furthermore, 60%△a1≤△a3≤90%△a1, 60%△b1≤△b4≤90%△b1.

[0072] The following uses a volume of 1000m³ 3 The above technical solution will be further illustrated by taking a hydrogen-rich carbon-circulating oxygen blast furnace as an example.

[0073] Initially, nitrogen and oxygen are introduced into the hydrogen-rich carbon-cycle oxygen blast furnace at flow rates of 5000 Nm³ and 5000 Nm³, respectively. 3 / h and 1000Nm 3 / h, then based on the blast capacity of the hydrogen-rich carbon-cycle oxygen blast furnace, increase nitrogen by 5000 Nm³ each time. 3 / h and oxygen 1000Nm 3 Simultaneously increase the flow rates of nitrogen and oxygen by a rate of / h until the air-to-air ratio reaches 0.40-0.70. At this point, keep the nitrogen flow rate constant and introduce decarbonized gas into the hydrogen-rich carbon-circulating oxygen blast furnace, increasing the decarbonized gas flow rate by 4000-4500 Nm³ each time. 3 / h and oxygen 800-900Nm 3 The air supply ratio is increased by simultaneously increasing the flow rate of decarbonized gas and oxygen by adjusting the range of / h.

[0074] When the air-to-air ratio is 0.70-1.20, the taphole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron, while keeping the oxygen flow rate constant. The decarburization gas flow rate is increased by 3500-4000 Nm³ / h each time, while the nitrogen flow rate is decreased by 3500-4000 Nm³ / h. 3 The air supply ratio is maintained constant at a rate of / h until the nitrogen flow rate is reduced to 0. Once the nitrogen flow rate is reduced to 0, the decarbonized gas flow rate and oxygen flow rate are kept constant until the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%. After that, the decarbonized gas flow rate is increased by 3500-4000 Nm³ each time. 3 / h and oxygen 700-800Nm 3 The air supply ratio is increased by simultaneously increasing the flow rate of decarbonized gas and oxygen by adjusting the flow rate by / h.

[0075] When the air supply ratio is ≥1.2, increase the decarbonized gas supply by 3000-3500 Nm³ each time. 3 / h and oxygen 600-700Nm 3 The flow rate of decarbonized gas and oxygen is increased synchronously in a range of / h to improve the air-to-feed ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume (i.e., the target air-to-feed ratio). Specifically, when the air-to-feed ratio is ≥1.2, the increment of decarbonized gas flow rate each time is smaller than the increment of decarbonized gas flow rate in any previous stage (e.g., the initial establishment of self-circulation, the middle stage of self-circulation), and the increment of oxygen flow rate each time is also smaller than the increment of oxygen flow rate in any previous stage (starting up the hydrogen-rich carbon-circulating oxygen blast furnace, the initial establishment of self-circulation, the middle stage of self-circulation). This operation facilitates the rapid heating of the hydrogen-rich carbon-circulating oxygen blast furnace, thereby accelerating the reaction rate inside the furnace, restoring furnace conditions, and ultimately improving production efficiency. The study found that, for different furnace volumes, when the air supply ratio is ≥1.2, the optimal increase in decarbonized gas flow and oxygen flow is 60%-90% of the increase in decarbonized gas flow and oxygen flow in each step of starting the hydrogen-rich carbon-cycle oxygen blast furnace. Specifically, 60%△a1≤△a3≤90%△a1 and 60%△b1≤△b4≤90%△b1.

[0076] Furthermore, in the above embodiments, the volumetric flow rate ratio of oxygen to nitrogen introduced in the step of starting the hydrogen-rich carbon-circulating oxygen blast furnace is maintained at 1:5 to 1:3. In the initial self-circulation establishment step, decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace while maintaining the volumetric flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3 to increase the flow rate of oxygen and decarbonized gas. Specifically, the volumetric flow rate ratio of introduced oxygen to nitrogen is maintained at 1:5 to 1:4, and the volumetric flow rate ratio of oxygen to decarbonized gas is maintained at 1:5 to 1:4.

[0077] Furthermore, in the above embodiments, the self-circulation mid-stage further includes: when the flow rate of the nitrogen gas to be introduced is reduced to 0, the flow rate of the decarbonized gas and the flow rate of oxygen are kept constant until the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%, and then the flow rate of oxygen and the flow rate of decarbonized gas are increased to improve the air supply ratio.

[0078] Furthermore, in the above embodiments, when the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30% during the mid-stage of self-circulation, the oxygen flow rate and decarbonized gas flow rate are increased while maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3; and when the self-circulation establishment completion step is completed, the oxygen flow rate and decarbonized gas flow rate are increased while maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3. Specifically, the volume flow rate ratio of oxygen to decarbonized gas is 1:5. Studies have found that maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 in each stage (i.e., the initial self-circulation establishment step, the mid-stage of self-circulation, and the self-circulation establishment completion step) helps to establish self-circulation more quickly and smoothly in the furnace.

[0079] Furthermore, the present invention also provides the following technical solutions to address the technical problems existing in the current air supply methods.

[0080] A method for supplying air to a hydrogen-rich carbon-circulating oxygen blast furnace includes:

[0081] Starting the hydrogen-rich carbon-circulating oxygen blast furnace: After shutdown, oxygen and nitrogen are introduced into the hydrogen-rich carbon-circulating oxygen blast furnace to start ironmaking and obtain top gas. Then, the flow rates of oxygen and nitrogen are increased according to the furnace's blast capacity, thereby increasing the air-to-feed ratio. The volumetric flow rate ratio of the introduced oxygen and nitrogen is maintained at 1:5 to 1:3. The air-to-feed ratio represents the ratio of the total gas flow rate to the volume of the hydrogen-rich carbon-circulating oxygen blast furnace, with the unit of total gas flow rate being Nm³. 3 / min, the unit of volume for a hydrogen-rich carbon-circulating oxygen blast furnace is m³. 3 The increment of the oxygen flow rate for each increase is Δb1.

[0082] Decarbonization: Collect the top coal gas and decarbonize it to obtain decarbonized coal gas, so that the volume fraction of CO2 in the decarbonized coal gas is <5%;

[0083] Initial establishment of self-circulation: When the air supply ratio meets the condition of 0.7 < air supply ratio < 1.20, the tap hole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron. At the same time, the oxygen flow rate is kept constant, decarburized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace and the flow rate of decarburized gas is increased, while the nitrogen flow rate is reduced to maintain a constant air supply ratio until the flow rate of nitrogen introduced is reduced to 0; wherein, the increment of the decarburized gas flow rate is Δa1 each time.

[0084] Mid-cycle stage: Continue to increase the oxygen flow rate and the decarbonized gas flow rate to improve the air supply ratio; wherein, the increment of the decarbonized gas flow rate is △a2 each time, and the increment of the oxygen flow rate is △b2 each time;

[0085] Self-circulation established: Once the air supply ratio is ≥1.2, continue increasing the flow rates of oxygen and decarbonized gas to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume. The increment of the decarbonized gas flow rate each time is Δa3, where Δa3 < Δa1 and Δa3 < Δa2; the increment of the oxygen flow rate each time is Δb3, where Δb3 < Δb1 and Δb3 < Δb2; the target air volume is the air volume introduced into the hydrogen-rich carbon-circulating oxygen blast furnace under normal production conditions. Further, 60%Δa1 ≤ Δa3 ≤ 90%Δa1, and 60%Δb1 ≤ Δb3 ≤ 90%Δb1.

[0086] The above method involves reducing nitrogen gas and simultaneously introducing top coal gas into the hydrogen-rich carbon-circulating oxygen blast furnace when the air-to-gas ratio meets the following condition: 0.7 < air-to-gas ratio < 1.20. Compared to existing air supply methods, this method establishes self-circulation more quickly, reduces nitrogen consumption, lowers the coke ratio, and is simple and easy to operate. Specifically, the air-to-gas ratio is 0.98 < air-to-gas ratio < 1.02.

[0087] Furthermore, in the above embodiment, the mid-cycle stage further includes: when the flow rate of nitrogen to be introduced is reduced to 0, the flow rates of decarbonized gas and oxygen are kept constant until the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%, after which the flow rates of oxygen and decarbonized gas are increased to improve the air supply ratio. Even further, when the volume fraction of CO2 in the decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30% in the mid-cycle stage, the flow rates of oxygen and decarbonized gas are increased while maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3. Specifically, the volume flow rate ratio of oxygen to decarbonized gas is maintained at 1:5 to 1:4.

[0088] Furthermore, in the above embodiments, the oxygen flow rate and decarbonized gas flow rate are increased by maintaining the volume flow rate ratio of oxygen to decarbonized gas at 1:5 to 1:3 during the self-circulation establishment completion step.

[0089] Furthermore, the decarbonization steps in the above embodiments also include: detecting the total pressure of the introduced oxygen and nitrogen and the total pressure of the generated top coal gas, wherein the total pressure of the oxygen and nitrogen is P1 (i.e., the air supply pressure), and the total pressure of the top coal gas is P2. When P1 ≥ 60 kPa and P2 ≥ 10 kPa, the top coal gas is collected and decarbonized (i.e., CO2 is removed from the top coal gas) to obtain decarbonized coal gas. Since the energy consumption for starting the decarbonization device is too high and a certain pressure is required for startup, the higher the gas pressure before entering the decarbonization device, the lower the energy consumption of the decarbonization device, and the better the decarbonization effect (i.e., the effect of the decarbonization device in absorbing CO2). Studies have found that when P1 and P2 meet the above conditions, the energy consumption of the decarbonization device can be significantly reduced, and the volume fraction of CO2 in the decarbonized coal gas can be reduced to below 3%.

[0090] Furthermore, in the above embodiments, after collecting the top coal gas, it can be pressurized and then introduced into a decarbonization device for decarbonization. Specifically, as shown in... Figure 1 As shown, when P1≥60kPa and P2≥10kPa, the top gas generated in the step of starting the hydrogen-rich carbon cycle oxygen blast furnace is collected, the top gas is first introduced into the gas compressor 2 and pressurized to above 1.0MPaG, and then the top gas is introduced into the decarbonization device 3 for decarbonization to obtain decarbonized gas.

[0091] Furthermore, in the above embodiments, a dust removal step is included between the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace and the decarbonization step. The dust removal step includes: collecting the top gas and removing dust from the top gas to filter out dust. Specifically, as... Figure 1 As shown, when P1≥60kPa and P2≥10kPa, the top gas generated during the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace is collected. The top gas is first introduced into the top gas fine dust removal device 1 for dust removal. After cleaning, the top gas is purified to a dust content of 2mg / Nm³. 3 Next, the dust-removed top coal gas is introduced into the coal gas compressor 2 and pressurized to above 1.0 MPaG before entering the decarbonization device 3 for decarbonization to obtain decarbonized coal gas.

[0092] Furthermore, the study found that the steps to fully establish self-circulation also include: when the volume fraction of N2 in the top gas is <20%, the coke ratio can be further reduced.

[0093] The embodiments provided by the present invention can be applied not only to short-term wind closures but also to long-term wind closures. The closure time for short-term wind closures is usually no more than 20 hours (inclusive), while the closure time for long-term wind closures is usually more than 20 hours (exclusive), and can even be 48 hours.

[0094] The present invention also provides an air supply method applicable only to short-term ventilation shutdowns (shutdown time ≤ 20h).

[0095] A method for supplying air to a hydrogen-rich carbon-circulating oxygen blast furnace includes:

[0096] First decarbonization: The pipeline gas is introduced into the decarbonization device to perform the first decarbonization to obtain the first decarbonized gas, so that the volume fraction of CO2 in the first decarbonized gas is <5%. The pipeline gas is one or more of blast furnace gas, coke oven gas or converter gas.

[0097] Starting the hydrogen-rich carbon-circulating oxygen blast furnace: Oxygen and the first decarburized gas are introduced into the hydrogen-rich carbon-circulating oxygen blast furnace to start ironmaking and obtain top gas. Then, the flow rates of oxygen and the first decarburized gas are increased according to the blast furnace's capacity, thereby increasing the blast ratio. The blast ratio represents the ratio of the total gas flow rate into the hydrogen-rich carbon-circulating oxygen blast furnace to its volume. The unit of the total gas flow rate is Nm³. 3 / min, the unit of volume for a hydrogen-rich carbon-circulating oxygen blast furnace is m³. 3 Wherein, the increment of the first decarbonized coal gas flow rate each time is Δc1, and the increment of the oxygen flow rate each time is Δd1;

[0098] Second decarbonization: Collect the top coal gas and decarbonize it to obtain second decarbonized coal gas, so that the volume fraction of CO2 in the second decarbonized coal gas is <5%;

[0099] The self-circulation process is initially established as follows: a second decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the flow rates of oxygen and the first decarbonized gas are increased to improve the air supply ratio. The increment of the first decarbonized gas flow rate is Δc2 each time, and the increment of the oxygen flow rate is Δd2 each time. Specifically, during the process of introducing oxygen and the first decarbonized gas into the hydrogen-rich carbon-circulating oxygen blast furnace to improve the air supply ratio, the generated top gas is decarbonized to remove CO2 and obtains the second decarbonized gas. The second decarbonized gas is then continuously introduced into the furnace, meaning that the second decarbonized gas obtained during the air supply process is always introduced into the furnace.

[0100] Mid-cycle stage: When the air supply ratio meets the condition of 0.70 < air supply ratio < 1.20, the taphole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron. At the same time, the oxygen flow rate is kept constant, the flow rate of the second decarburized gas is increased, and the flow rate of the first decarburized gas is decreased to maintain the air supply ratio constant until the flow rate of the first decarburized gas decreases to 0. After that, the oxygen flow rate and the flow rate of the second decarburized gas are increased to improve the air supply ratio. The increment of the second decarburized gas flow rate each time is Δc3, and the increment of the oxygen flow rate each time is Δd3. Specifically, when the air supply ratio is lower than 0.98, the air supply ratio is improved by increasing the flow rates of oxygen and the first decarburized gas. The top gas obtained in this process is decarburized to obtain the second decarburized gas, and the obtained second decarburized gas is continuously fed into the furnace. That is, the amount of second decarburized gas obtained is the amount of second decarburized gas fed into the furnace. As the reaction proceeds, the amount of the second decarbonized gas will continuously increase. Therefore, when the air supply ratio satisfies the condition 0.70 < air supply ratio < 1.20, the air supply ratio can be maintained constant by keeping the oxygen flow rate constant, increasing the flow rate of the second decarbonized gas, and decreasing the flow rate of the first decarbonized gas. Specifically, 0.98 < air supply ratio < 1.02.

[0101] Self-circulation established: When the air supply ratio is ≥1.2, continue to increase the flow rate of oxygen and the second decarbonized gas to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon cycle oxygen blast furnace reaches the target air volume. The increment of the second decarbonized gas flow rate each time is △c4, and the increment of the oxygen flow rate each time is △d4, where △c4 < △c1, △c4 < △c2 and △c4 < △c3; △d4 < △d1, △d4 < △d2 and △d4 < △d3. Specifically, the increment of the second decarburized gas flow rate each time is lower than the increment of the first decarburized gas flow rate each time during the startup of the hydrogen-rich carbon-circulating oxygen blast furnace, the increment of the first decarburized gas flow rate each time during the initial establishment of self-circulation, and the increment of the second decarburized gas flow rate each time during the mid-stage of self-circulation; and the increment of the oxygen flow rate each time is lower than the increment of the oxygen flow rate each time during the startup of the hydrogen-rich carbon-circulating oxygen blast furnace, the increment of the oxygen flow rate each time during the initial establishment of self-circulation, and the increment of the oxygen flow rate each time during the mid-stage of self-circulation. The target air volume is the air volume supplied to the hydrogen-rich carbon-circulating oxygen blast furnace under normal production conditions; wherein, the shutdown time of the hydrogen-rich carbon-circulating oxygen blast furnace is ≤20h, and in particular, a shutdown time of 10h or less (including 10h) yields better recovery results. Further, 60%△c1≤△c4≤90%△c1, 60%△d1≤△d4≤90%△d1.

[0102] Piped gas is an existing resource within blast furnace ironmaking plants, primarily sourced from blast furnace gas, coke oven gas, and converter gas. Blast furnace gas is produced during ironmaking, converter gas during steelmaking, and coke oven gas during coking. All these gases contain a certain amount of nitrogen, especially blast furnace gas, whose main components and contents are: CO2: 6-22%, CO: 21-26%, H2: 1-4%, N2: 53-57%. Among these gases, blast furnace gas has the highest nitrogen content. Therefore, this invention eliminates the use of nitrogen, utilizing the plant's piped gas, thus not only reusing the piped gas but also reducing production costs. Research has found that blast furnaces with hydrogen-rich carbon-circulating oxygen systems are unsuitable for ventilation when shut down for more than 20 hours (i.e., eliminating nitrogen and using piped gas). This is mainly because after a prolonged shutdown (more than 20 hours), the furnace charge inside the smelting furnace becomes compacted, reducing the tuyeres' ability to receive air. Simultaneously, the internal temperature field gradually shifts downwards, requiring more heat and a longer time to restore the furnace temperature during the air supply process. If the furnace is directly connected to the plant's gas pipeline for air supply, a large amount of poorly flowing cold slag and iron will be generated and enter the hearth before the furnace temperature returns to normal, affecting the hearth's permeability and further prolonging the air supply and furnace condition recovery time.

[0103] The following is combined with Figure 2 The above technical solution will be further explained below.

[0104] like Figure 2 As shown, pipeline gas, such as blast furnace gas, can be introduced from the gas pipeline network 6 and then decarbonized by the decarbonization device 3 to obtain the first decarbonized gas. By adjusting the parameters of the decarbonization device 3, the CO2 volume fraction in the first decarbonized gas is kept below 5%, thus avoiding excessive CO2 concentration and excessive coke consumption when the first decarbonized gas is subsequently introduced into the hydrogen-rich carbon-circulating oxygen blast furnace. The first decarbonized gas is then introduced into the gas heating device 5 and heated to above 1200°C, before being introduced into the furnace through the tuyeres. Simultaneously, ambient temperature oxygen is also introduced into the furnace through the tuyeres to obtain top gas. The time when oxygen is introduced through the tuyeres is the start time of the blast. Because the downtime of the hydrogen-rich carbon-circulating oxygen blast furnace is relatively short, its tuyeres have a good capacity to receive air volume; therefore, the initial flow rates of the introduced oxygen and the first decarbonized gas can be set relatively high. As nitrogen and first decarbonized gas are continuously introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, its capacity to receive blast air gradually weakens. Therefore, this invention increases the flow rates of oxygen and first decarbonized gas based on the blast furnace's capacity to receive blast air, thereby increasing the blast ratio. Specifically, the flow rate of the first decarbonized gas can be increased by increasing the flow rate of the pipeline gas. In other words, this invention increases the flow rates of oxygen and pipeline gas based on changes in the blast furnace's capacity to receive blast air, thereby increasing the blast ratio.

[0105] The top gas is collected and decarbonized to obtain second decarbonized gas, the purpose of which is to remove CO2 from the top gas. The volume fraction of CO2 in the second decarbonized gas is reduced to below 5% by adjusting the parameters of the decarbonization unit 3. Then, the second decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, while simultaneously increasing the oxygen flow rate and the flow rate of the first decarbonized gas to increase the air-to-feed ratio until 0.70 < air-to-feed ratio < 1.20. Specifically, the air-to-feed ratio is maintained at 0.70 < air-to-feed ratio < 1.20 by increasing the oxygen flow rate and the flow rate of the pipeline gas.

[0106] When 0.70 < air supply ratio < 1.20, keep the oxygen flow rate constant, increase the flow rate of the second decarbonized gas, and decrease the flow rate of the first decarbonized gas to maintain the air supply ratio constant until the flow rate of the first decarbonized gas decreases to 0. Specifically, the flow rate of the first decarbonized gas is reduced by decreasing the flow rate of the pipeline gas until the flow rate of the pipeline gas decreases to 0, at which point the flow rate of the first decarbonized gas also decreases to 0.

[0107] When the flow rate of the first decarbonized gas decreases to 0, keep the flow rates of the second decarbonized gas and oxygen constant, and monitor the changes in the concentrations of CO2 in the second decarbonized gas and N2 in the top gas. When the volume fraction of CO2 in the second decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%, it indicates that the quality of the second decarbonized gas is gradually improving. After that, the oxygen flow rate and the second decarbonized gas flow rate can be increased to improve the air supply ratio.

[0108] When the required air supply ratio is ≥1.2, continue to increase the flow rates of oxygen and the second decarbonized gas to improve the air supply ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume. Furthermore, each increase in the flow rate of the second decarbonized gas should be lower than the increase in the flow rate of the first decarbonized gas during the startup of the hydrogen-rich carbon-circulating oxygen blast furnace, the increase in the flow rate of the first decarbonized gas during the initial establishment of self-circulation, and the increase in the flow rate of the second decarbonized gas during the mid-stage of self-circulation. Similarly, each increase in the oxygen flow rate should be lower than the increase in the oxygen flow rate during the startup of the hydrogen-rich carbon-circulating oxygen blast furnace, the increase in the flow rate of the first decarbonized gas during the initial establishment of self-circulation, and the increase in the flow rate of the second decarbonized gas during the mid-stage of self-circulation. That is, Δc4 < Δc1, Δc4 < Δc2, and Δc4 < Δc3; Δd4 < Δd1, Δd4 < Δd2, and Δd4 < Δd3. Here, the target air volume is the air volume introduced into the blast furnace during normal production.

[0109] The following uses a volume of 1000m³ 3 The above technical solution will be further illustrated by taking a hydrogen-rich carbon-circulating oxygen blast furnace as an example.

[0110] Because the shutdown time is relatively short, the initial flow rates of oxygen and the first decarbonized gas can be set higher. Specifically, the initial flow rates of the first decarbonized gas and oxygen introduced into the hydrogen-rich carbon-circulating oxygen blast furnace are 20,000 Nm³ / h and 4,000 Nm³ / h, respectively. Then, based on the blast furnace's capacity, the flow rate of the first decarbonized gas is increased by 5,000 Nm³ / h each time. 3 / h and oxygen 1000Nm 3 The flow rates of the first decarburizing gas and oxygen are increased synchronously in increments of / h. When the air-to-air ratio is less than 1.20, the taphole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron, while the oxygen flow rate remains constant. The flow rate of the second decarburizing gas is increased by 4000-4500 Nm³ each time. 3 / h, reducing the first decarbonized gas flow rate by 4000-4500 Nm³. 3 The air supply ratio is maintained constant at a rate of / h until the flow rate of the first decarbonized gas decreases to 0 (i.e., the pipeline gas flow rate decreases to 0); once the flow rate of the first decarbonized gas decreases to 0, the flow rates of the second decarbonized gas and oxygen are kept constant until the volume fraction of CO2 in the second decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30%; thereafter, the second decarbonized gas is increased by 4000-4500 Nm³ each time. 3 / h and oxygen 800-900Nm 3 To increase the air supply ratio, the flow rate of the second decarbonized gas and oxygen will be increased synchronously by varying the rate of change per hour. Once the air supply ratio is ≥1.2, the flow rate of the second decarbonized gas will be increased by 3000–4000 Nm³ each time. 3 / h and oxygen 600-800Nm 3The flow rate of the second decarbonized gas and oxygen is increased synchronously by a certain increment per hour to improve the air-to-feed ratio until the total flow rate of gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches the target air volume (i.e., the target air-to-feed ratio). Specifically, when the air-to-feed ratio is ≥1.2, the increment of the second decarbonized gas flow rate is smaller than the increment of the first decarbonized gas flow rate in any previous stage (i.e., the initial self-circulation establishment stage, and the mid-stage of self-circulation), and the increment of the second decarbonized gas flow rate is also smaller than the increment of the oxygen flow rate in any previous stage (i.e., the initial self-circulation establishment stage, and the mid-stage of self-circulation). This operation facilitates rapid heating of the hydrogen-rich carbon-circulating oxygen blast furnace, thereby accelerating the reaction rate within the furnace and improving production efficiency. Studies have found that, for different furnace volumes, when the air supply ratio is ≥1.2, the best effect is achieved when the increment of the second decarbonization gas flow and oxygen flow is 60%-90% of the increment of the decarbonization gas flow and oxygen flow in each step of starting the hydrogen-rich carbon cycle oxygen blast furnace.

[0111] Furthermore, in the above embodiments, during the startup of the hydrogen-rich carbon-circulating oxygen blast furnace, the volumetric flow rate ratio of the introduced oxygen to the first decarbonized gas is maintained at 1:5 to 1:3. During the initial self-circulation establishment step, the second decarbonized gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the flow rates of both oxygen and the first decarbonized gas are increased while maintaining the volumetric flow rate ratio of oxygen to the first decarbonized gas at 1:5 to 1:3. When the volume fraction of CO2 in the second decarbonized gas is <3% and the volume fraction of N2 in the top gas is <30% during the mid-stage of self-circulation, the oxygen and second decarbonized gas flow rates are further increased while maintaining the volumetric flow rate ratio of oxygen to the second decarbonized gas at 1:5 to 1:3. Studies have found that setting both the volumetric flow rate ratio of oxygen to the first decarbonized gas to 1:5 helps to quickly and efficiently establish self-circulation and facilitates smooth furnace operation.

[0112] Furthermore, in the above embodiments, a dust removal step is included before the first decarbonization step. The first dust removal step includes: introducing pipeline gas into a dust removal device for dust removal to filter dust. Specifically, as... Figure 2 As shown, the pipeline gas 6 can be introduced into the top gas dust removal device 1 for dust removal. After cleaning, the pipeline gas is purified to a dust content of 2 mg / Nm³. 3 Next, it is introduced into the gas compressor 2 for pressurization, and the pipeline gas is pressurized to above 1.0 MPaG. Then, the pipeline gas is introduced into the decarbonization device 3 for decarbonization to obtain the first decarbonized gas.

[0113] Furthermore, in the above embodiments, the second decarbonization step further includes: detecting the total pressure of the introduced oxygen and the first decarbonized gas, as well as the total pressure of the generated top gas, wherein the total pressure of the oxygen and the first decarbonized gas is P3, and the total pressure of the top gas is P4. When P3 ≥ 60 kPa and P4 ≥ 10 kPa, the top gas is collected, and a second decarbonization is performed on the top gas to obtain the second decarbonized gas. Since the start-up energy consumption of the decarbonization device is too high, and a certain pressure is required for startup, the higher the pressure, the lower the energy consumption of the decarbonization device and the better the decarbonization effect. Studies have found that when P3 and P4 meet the above conditions, the energy consumption of the decarbonization device can be significantly reduced, and the decarbonization effect is best. Under this condition, the volume fraction of CO2 in the second decarbonized gas can be reduced to below 3%.

[0114] Furthermore, in the above embodiments, a dust removal step is also included between the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace and the second decarbonization step. The dust removal step includes: collecting the top gas and removing dust from the top gas to filter out dust.

[0115] Furthermore, in the above embodiments, a pressurization step is included before starting the hydrogen-rich carbon-cycle oxygen blast furnace and the second decarbonization step. The pressurization step includes: collecting the top gas, pressurizing the top gas, and then performing a second decarbonization on the pressurized top gas. Specifically, as shown... Figure 2 As shown, when P3 ≥ 60 kPa and P4 ≥ 10 kPa, the top gas generated during the start-up of the hydrogen-rich carbon-circulating oxygen blast furnace is collected. The top gas is first introduced into the fine dust removal device 1 for dust removal. After cleaning, the top gas is purified to a dust content of 2 mg / Nm³. 3 Next, the dust-removed top coal gas is introduced into the coal gas compressor 2 and pressurized to above 1.0 MPaG. Then, the top coal gas is introduced into the decarbonization device 3 for decarbonization to obtain the second decarbonized coal gas.

[0116] Furthermore, in the above embodiments, the self-circulation complete establishment step further includes: the volume fraction of N2 in the top gas is <20%. This can further reduce the coke ratio.

[0117] The present invention will now be described in further detail through specific embodiments and in conjunction with the accompanying drawings.

[0118] Example 1

[0119] Adopting such Figure 1 The apparatus shown supplies air to a hydrogen-rich carbon-circulating oxygen blast furnace with a shutdown time of 48 hours. The volume of the hydrogen-rich carbon-circulating oxygen blast furnace is 1000 m³. 3 .

[0120] (1) Nitrogen gas is introduced into the gas injection valve station 4, and its initial flow rate is set to 5000 Nm³. 3 / h, the nitrogen gas is heated to 1250℃ by the gas heating device 5 and then introduced through the air vent. The initial flow rate of room temperature oxygen is set to 1000Nm³. 3 / h, and high-temperature nitrogen gas are synchronously introduced into the vent through a separate channel at a ratio of 1:5. The resulting top coal gas is then released from the gas venting tower. Afterwards, nitrogen is added at a rate of 5000 Nm³ per cycle. 3 / h, add 1000 Nm of oxygen 3 The cycle is synchronized, increasing as soon as the actual value reaches the set value. When the air supply pressure P1 reaches 60 kPa and the top gas pressure P2 ≥ 10 kPa, the top gas is introduced into the decarbonization device 3 for decarbonization to obtain decarbonized gas. The obtained decarbonized gas is released from the vent pipe and is not recycled temporarily.

[0121] (2) Continue to increase the oxygen content at the air vent to 5000 Nm³. 3 / h, nitrogen flow rate up to 25000 Nm 3 / h (air supply ratio 0.5), once the CO2 content of the decarbonized gas is <5%, venting is stopped. The decarbonized gas is then directed to the gas injection valve station 4, heated to 1250℃ by the gas heating device 5, and circulated in through the vent 8. Simultaneously, the nitrogen flow rate is maintained at 25000 Nm³. 3 The rate remains constant, with an additional 4500 Nm³ of decarbonized gas added each time. 3 / h, simultaneously increase oxygen by 900 Nm 3 / h, until the decarbonized gas volume reaches 25000 Nm³. 3 / h, oxygen content reaches 10000 Nm 3 / h (combined air volume supply ratio 1.0), open the taphole to discharge iron. Simultaneously maintain an oxygen content of 10000 Nm³. 3 With the flow rate of decarbonized gas remaining constant at 4000 Nm³ / h, gradually increase the flow rate. 3 / h, reduce nitrogen flow rate by 4000 Nm 3 / h, until the decarbonized gas reaches 50000 Nm³. 3 / h, nitrogen flow rate reduced to 0.

[0122] (3) Keep the flow rates of decarbonized gas and oxygen constant. Once the N2 content in the top gas is less than 30% and the CO2 content in the decarbonized gas is less than 3%, continue to increase the decarbonized gas flow rate to 60,000 Nm³. 3 / For more than h, the oxygen content reaches 12000 Nm. 3 The air volume should be above 1.2 / h (overall air volume supply ratio should be above 1.2), and the temperature should be controlled at Tf ≥ 1800℃ (the theoretical combustion temperature at the duct should be greater than 1800℃). Each time, 3500 Nm³ of decarbonized gas should be added. 3 / h, oxygen 700Nm 3 / h. During the increase, appropriately slow down the pace of increasing the amount of decarbonized gas and oxygen. If the permeability is good, the air pressure is stable, the material flow is uniform, and the furnace temperature is sufficient (PT>1480℃), then continue to increase the amount of decarbonized gas and oxygen according to the above pace.

[0123] (4) Monitor the furnace condition. When the temperature of molten iron in three consecutive furnaces is >1480℃, and the CO2 content of the decarburized gas is stably controlled below 3%, and the N2 content of the top gas drops to below 20%, it indicates that the furnace condition is good. Continue to increase the amount of decarburized gas to 105000 Nm³. 3 / h (decarbonized gas ratio 700Nm) 3 / tHM), with the oxygen supply increased to 21000 Nm³. 3 / tHM. Considering the relative difficulty in restoring furnace conditions after a long shutdown, the decarbonized gas ratio reached 700Nm. 3 / tHM means that the self-circulating gas volume has reached the target value, that is, the target air volume has been reached under the condition of no coal injection.

[0124] (5) Start the pulverized coal injection at the tuyeres, setting the initial injection rate to 30 kg / tHM. Confirm that the combustion at the tuyeres is good, and increase the coal ratio at intervals of 20-30 kg / tHM until it reaches 100 kg / tHM. To ensure Tf ≥ 1800℃, increase the oxygen content while increasing the coal ratio until the oxygen content reaches 28000 Nm³. 3 / h, at which point HyCROF reaches normal production status.

[0125] Example 2

[0126] Adopting such Figure 2 The apparatus shown supplies air to a hydrogen-rich carbon-circulating oxygen blast furnace with a shutdown time of 10 hours. The volume of the hydrogen-rich carbon-circulating oxygen blast furnace is 1000 m³. 3 .

[0127] (1) Open the shut-off valve before the top gas dust removal device 1 to connect the blast furnace gas to the gas pipeline network 6. After passing through the top gas dust removal device 1 and the gas compressor 2, the blast furnace gas enters the decarbonization device 3. After decarbonization, the first decarbonized gas is obtained. Initially, the first decarbonized gas is released from the vent pipe. This continues until the CO2 content of the first decarbonized gas is less than 5%. At this point, the initial pipeline gas flow rate is set to 20,000 Nm³. 3 / h, open the shut-off valve of the gas injection station 4, introduce the first decarbonized gas into the gas heating device 5, heat it to 1250℃, and then inject it into the furnace through the tuyeres. The initial oxygen content is set to 4000 Nm³. 3 / h, according to the ratio of oxygen to blast furnace gas in the pipeline network of 1:5, it is introduced simultaneously from the tuyeres through a separate channel.

[0128] (2) Each time blast furnace gas is added to the pipeline network, it should be 5000 Nm³. 3 / h, add 1000 Nm of oxygen 3 The pressure is increased synchronously at a rate of / h, rising as soon as the actual value reaches the set value. Simultaneously, the obtained top gas is released from the gas venting tower. Once the air supply pressure P3 reaches 60 kPa and the top gas pressure P4 reaches 10 kPa, the valve to the gas venting tower is closed, and the top gas enters the decarbonization device 3 for secondary decarbonization to obtain second decarbonized gas. This second decarbonized gas is then heated by the gas heating device 5 and introduced into the hydrogen-rich carbon-circulating oxygen blast furnace through the tuyeres. This process continues until the amount of second decarbonized gas reaches 50,000 Nm³. 3 / h, oxygen flow rate increased to 10000 Nm 3 / h (comprehensive air volume to air supply ratio 1.0), open the taphole to tap iron. At this time, keep the oxygen content constant and gradually reduce the blast furnace gas volume in the pipeline until the pipeline gas volume is reduced to 0.

[0129] (3) Keep the flow rates of the second decarbonized gas and oxygen constant. When N2 in the top gas is less than 30% and CO2 in the second decarbonized gas is less than 3%, continue to increase the flow rate of the second decarbonized gas by 4500 Nm³ each time. 3 / h, oxygen flow rate 900 Nm 3 The decarbonized gas volume is increased to 60,000 Nm³ / h. 3 / h or more, oxygen content up to 12000 Nm 3 When the flow rate is above 1.2 (air supply ratio above 1.2), pay attention to controlling Tf ≥ 1800℃, and appropriately slow down the pace of increasing the amount of decarbonized gas and oxygen. Each increase should be 4000 Nm³ of decarbonized gas. 3 / h, oxygen 800Nm 3 / h. If the air permeability is good, the air pressure is stable, the material flow is uniform, and the furnace temperature is sufficient (furnace temperature > 1480℃), then increase the decarbonization gas by 4000 Nm³ each time, as described above. 3 / h, oxygen 800Nm 3 (h) Continue to increase the amount of decarbonized gas and oxygen.

[0130] (4) When the temperature of three consecutive furnaces of molten iron exceeds 1480℃, and the CO2 content of the decarburized gas is stably controlled below 3%, and the N2 content of the top gas decreases to below 20%, it indicates that the furnace temperature is sufficient and the quality of the top gas and decarburized gas is good. At this time, the amount of decarburized gas should be increased to 135000 Nm³. 3 / h (decarbonized gas ratio 900Nm) 3 With increasing decarbonized gas ratio, the indirect reduction degree of the furnace charge increases, while the direct reduction degree (coke reduction of iron ore) decreases, resulting in a significant reduction in oxygen consumption. The furnace condition recovers quickly during short-term shutdown and re-blowing processes, with the decarbonized gas ratio reaching 900 Nm³. 3 / tHM means that the self-circulating gas volume has reached the target value, that is, the target air volume has been reached under the condition of no coal injection.

[0131] (5) Start the pulverized coal injection at the tuyere, setting the initial injection rate to 30 kg / tHM. If the combustion at the tuyere is good, increase the coal ratio at intervals of 20-30 kg / tHM until it reaches 100 kg / tHM. To ensure Tf ≥ 1800℃, adjust the oxygen content while increasing the coal ratio until the oxygen content reaches 24000 Nm³. 3 / h, at this point HyCROF enters normal production status.

[0132] Table 1 records the data on coke ratio, coal ratio, decarbonized gas ratio, solid fuel ratio, oxygen consumption, direct reduction degree, and CO utilization rate for Examples 1-2 above. The coke ratio refers to the amount of coke consumed per unit of pig iron produced during the hydrogen-rich carbon-cycle oxygen blast furnace ironmaking process. The coal ratio is the amount of pulverized coal consumed per unit of pig iron produced. Since coal is much cheaper than coke, a higher coal ratio results in a lower coke ratio and lower iron production costs. The solid fuel ratio is the sum of the amount of coke, pulverized coal, and other solid fuels consumed per unit of pig iron produced. A lower solid fuel ratio indicates lower fossil fuel consumption and lower carbon emissions during the smelting process. The decarbonization gas ratio refers to the amount of decarbonization gas consumed per unit of pig iron smelting. A higher decarbonization gas ratio indicates that more solid fuel is replaced by decarbonization gas, resulting in lower carbon emissions. Oxygen consumption refers to the amount of oxygen consumed per unit of pig iron smelting. A lower oxygen consumption indicates a lower solid fuel ratio, resulting in lower carbon emissions. Direct reduction degree refers to the proportion of iron directly reduced by carbon during the smelting process to all reduced iron. A lower direct reduction degree indicates a lower coke ratio. CO utilization rate refers to the percentage of CO used to reduce iron ore. A higher CO utilization rate indicates higher CO utilization efficiency. Table 1 also lists the data on coke ratio, coal ratio, solid fuel ratio, oxygen consumption, direct reduction degree, and CO utilization rate involved in existing conventional blast furnace ironmaking processes.

[0133] Table 1

[0134]

[0135] As shown in Table 1, compared to conventional blast furnace blasting methods, the blasting method provided by this invention has a lower coke ratio, a lower solid fuel ratio, less oxygen consumption, a lower direct reduction degree, and a higher CO utilization rate. Furthermore, this invention proposes a practical technical solution that allows for low-cost and simple operation of blast furnaces to supply air to hydrogen-rich carbon-recirculating oxygen blast furnaces, enabling them to quickly transition from a shutdown state to normal production and initiate HyCROF normal production. This facilitates the subsequent promotion and implementation of the new HyCROF process, achieving a low-carbon transformation of the blast furnace long-process.

[0136] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. A method of blast air supply for a hydrogen-rich carbon cycle oxygen blast furnace, characterized by, The method comprises the following steps: Turning on the hydrogen-rich carbon cycle oxygen blast furnace: oxygen and nitrogen are introduced into the hydrogen-rich carbon cycle oxygen blast furnace after the hydrogen-rich carbon cycle oxygen blast furnace is shut down, the hydrogen-rich carbon cycle oxygen blast furnace is started to smelt iron, and top coal gas is obtained, then the flow rates of the oxygen and the nitrogen are increased according to the capacity of the hydrogen-rich carbon cycle oxygen blast furnace to accept the amount of wind, and then the air supply ratio is increased, the air supply ratio represents the ratio of the total flow rate of the gas introduced into the hydrogen-rich carbon cycle oxygen blast furnace to the volume of the hydrogen-rich carbon cycle oxygen blast furnace, the unit of the total flow rate of the gas is Nm3 / min, and the unit of the volume of the hydrogen-rich carbon cycle oxygen blast furnace is m 3 ; wherein the increment of the oxygen flow rate each time is △b1; Decarburization: collecting top coal gas and decarburizing the top coal gas to obtain decarburized coal gas, so that the volume fraction of CO2 in the decarburized coal gas is less than 5%; Preliminary establishment of self-circulation: when the blast ratio meets 0.40≤blast ratio≤0.70, the nitrogen flow is kept unchanged, the decarburized coal gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the oxygen flow and the decarburized coal gas flow are increased to increase the blast ratio; wherein the increment of the decarburized coal gas flow each time is △a1, and the increment of the oxygen flow each time is △b2; Mid-term stage of self-circulation: when the blast ratio meets 0.7<blast ratio<1.20, the tap hole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron, the oxygen flow is kept unchanged, the decarburized coal gas flow is increased, and the nitrogen flow is reduced to maintain the blast ratio unchanged until the nitrogen flow introduced is reduced to 0; then the oxygen flow and the decarburized coal gas flow are continuously increased to increase the blast ratio, wherein the increment of the decarburized coal gas flow each time is △a2, and the increment of the oxygen flow each time is △b3; Completion of establishment of self-circulation: when the blast ratio is greater than or equal to 1.2, the oxygen and the decarburized coal gas flows are continuously increased to increase the blast ratio until the total flow of the gas introduced into the hydrogen-rich carbon-circulating oxygen blast furnace reaches a target blast volume, wherein the increment of the decarburized coal gas flow each time is △a3, the increment of the oxygen flow each time is △b4, △a3<△a1 and △a3<△a2; △b4<△b1, △b4<△b2 and △b4<△b3, and the target blast volume is the blast volume introduced in the normal production state of the hydrogen-rich carbon-circulating oxygen blast furnace.

2. A method of blast air supply for a hydrogen-rich carbon cycle oxygen blast furnace, characterized by, The method comprises the following steps: Opening hydrogen-rich carbon cycle oxygen blast furnace: introducing oxygen and nitrogen into the hydrogen-rich carbon cycle oxygen blast furnace after the hydrogen-rich carbon cycle oxygen blast furnace is shut down, opening the hydrogen-rich carbon cycle oxygen blast furnace for ironmaking, obtaining top coal gas, and then increasing the flow rates of the oxygen and the nitrogen according to the capacity of the hydrogen-rich carbon cycle oxygen blast furnace to receive the air volume, and further increasing the air supply ratio, the air supply ratio representing the ratio of the total flow rate of the gas introduced into the hydrogen-rich carbon cycle oxygen blast furnace to the volume of the hydrogen-rich carbon cycle oxygen blast furnace, the unit of the total flow rate of the gas being Nm 3 / min, the unit of the volume of the hydrogen-rich carbon cycle oxygen blast furnace being m 3 ; wherein the increment of the oxygen flow rate each time is △b1; Decarburization: collecting top coal gas and decarburizing the top coal gas to obtain decarburized coal gas, so that the volume fraction of CO2 in the decarburized coal gas is less than 5%; Preliminary establishment of self-circulation: when the blast ratio meets 0.70<blast ratio<1.20, the tap hole of the hydrogen-rich carbon-circulating oxygen blast furnace is opened to obtain molten iron, the oxygen flow is kept unchanged, the decarburized coal gas is introduced into the hydrogen-rich carbon-circulating oxygen blast furnace, and the decarburized coal gas flow is increased, and the nitrogen flow is reduced to maintain the blast ratio unchanged until the nitrogen flow introduced is reduced to 0; wherein the increment of the decarburized coal gas flow each time is △a1; Mid-term stage of self-circulation: the oxygen flow and the decarburized coal gas flow are continuously increased to increase the blast ratio; wherein the increment of the decarburized coal gas flow each time is △a2, and the increment of the oxygen flow each time is △b2; When the volume fraction of CO2 in the decarburized coal gas < 3% and the volume fraction of N2 in the top coal gas < 30% in the middle stage of the self-circulation, the flow rate of the oxygen and the flow rate of the decarburized coal gas are increased under the condition that the volume flow rate ratio of the oxygen and the decarburized coal gas is kept at 1:5-1:3; and the flow rate of the oxygen and the flow rate of the decarburized coal gas are increased under the condition that the volume flow rate ratio of the oxygen and the decarburized coal gas is kept at 1:5-1:3 in the self-circulation completion step.

3. The air supply method according to claim 1, wherein The volume flow rate ratio of the oxygen and the nitrogen introduced in the step of starting the hydrogen-rich carbon-circulation oxygen blast furnace is kept at 1:5-1:3, and the flow rate of the oxygen and the flow rate of the decarburized coal gas are increased under the condition that the volume flow rate ratio of the oxygen and the decarburized coal gas is kept at 1:5-1:3 in the step of preliminarily establishing the self-circulation.

4. The air supply method according to claim 1 or 2, wherein The step of preliminarily establishing the self-circulation further comprises: when the flow rate of the nitrogen to be introduced is reduced to 0, the flow rate of the decarburized coal gas and the flow rate of the oxygen are kept unchanged until the volume fraction of CO2 in the decarburized coal gas < 3% and the volume fraction of N2 in the top coal gas < 30%, and then the flow rate of the oxygen and the flow rate of the decarburized coal gas are continuously increased to increase the blast ratio.

5. The air supply method according to claim 4, wherein When the volume fraction of CO2 in the decarburized coal gas < 3% and the volume fraction of N2 in the top coal gas < 30% in the middle stage of the self-circulation, the flow rate of the oxygen and the flow rate of the decarburized coal gas are increased under the condition that the volume flow rate ratio of the oxygen and the decarburized coal gas is kept at 1:5-1:3; and the flow rate of the oxygen and the flow rate of the decarburized coal gas are increased under the condition that the volume flow rate ratio of the oxygen and the decarburized coal gas is kept at 1:5-1:3 in the self-circulation completion step.

6. The air supply method according to claim 1 or 2, wherein The step of decarburizing further comprises: detecting the total pressure of the introduced oxygen and nitrogen and the total pressure of the generated top coal gas, wherein the total pressure of the oxygen and the nitrogen is P1, and the total pressure of the top coal gas is P2; when P1≥60kpa and P2≥10kpa, the top coal gas is collected, and the top coal gas is subjected to decarburization to obtain decarburized coal gas.

7. The air supply method according to claim 1 or 2, wherein The step of starting the hydrogen-rich carbon-circulation oxygen blast furnace and the step of decarburizing further comprise a dust removal step, and the dust removal step comprises: collecting the top coal gas, and subjecting the top coal gas to dust removal to filter dust.

8. The air supply method according to claim 1 or 2, wherein The step of starting the hydrogen-rich carbon-circulation oxygen blast furnace and the step of decarburizing further comprise a pressurization step, and the pressurization step comprises: collecting the top coal gas, and subjecting the top coal gas to pressurization, and then subjecting the pressurized top coal gas to decarburization.

9. The air supply method according to claim 1 or 2, wherein The step of preliminarily establishing the self-circulation further comprises: the volume fraction of N2 in the top coal gas < 20%.

10. A method of blast air supply for a hydrogen-rich carbon cycle oxygen blast furnace, characterized by, The step of decarburizing further comprises: first decarburization: introducing pipe network coal gas into a decarburization device to subject the pipe network coal gas to first decarburization to obtain first decarburized coal gas, so that the volume fraction of CO2 in the first decarburized coal gas < 5%, and the pipe network coal gas is one or more of blast furnace gas, coke oven gas or converter gas; Turning on a hydrogen-rich carbon cycle oxygen blast furnace: introducing the oxygen and the first decarburized coal gas into a hydrogen-rich carbon cycle oxygen blast furnace which has been idled, turning on the hydrogen-rich carbon cycle oxygen blast furnace for ironmaking, obtaining top coal gas, and then increasing the flow rates of the oxygen and the first decarburized coal gas according to the capacity of the hydrogen-rich carbon cycle oxygen blast furnace to receive the air volume, and further increasing the air supply ratio, the air supply ratio representing the ratio of the total flow rate of the gas introduced into the hydrogen-rich carbon cycle oxygen blast furnace to the volume of the hydrogen-rich carbon cycle oxygen blast furnace, the unit of the total flow rate of the gas being Nm 3 / min, the unit of the volume of the hydrogen-rich carbon cycle oxygen blast furnace being m 3 ; wherein the increment of the flow rate of the first decarburized coal gas each time is △c1, and the increment of the flow rate of the oxygen each time is △d1. second decarburization: collecting top coal gas and decarburizing the top coal gas to obtain second decarburized coal gas, so that the volume fraction of CO2 in the second decarburized coal gas is <5%; initial establishment of self-circulation: introducing the second decarburized coal gas into the hydrogen-rich carbon-circulation oxygen blast furnace, and increasing the flow rates of the oxygen and the first decarburized coal gas to increase the air ratio; wherein the increment of the flow rate of the first decarburized coal gas each time is △c2, and the increment of the flow rate of the oxygen each time is △d2; mid-term stage of self-circulation: when the air ratio satisfies 0.70 < air ratio < 1.20, tapping molten iron through the tapping hole of the hydrogen-rich carbon-circulation oxygen blast furnace while keeping the flow rate of the oxygen unchanged, increasing the flow rate of the second decarburized coal gas, and decreasing the flow rate of the first decarburized coal gas to maintain the air ratio unchanged until the flow rate of the first decarburized coal gas is reduced to 0; then, the flow rates of the oxygen and the second decarburized coal gas are continuously increased to increase the air ratio; wherein the increment of the flow rate of the second decarburized coal gas each time is △c3, and the increment of the flow rate of the oxygen each time is △d3; completion of establishment of self-circulation: when the air ratio is ≥1.2, the flow rates of the oxygen and the second decarburized coal gas are continuously increased to increase the air ratio until the total flow rate of the gases introduced into the hydrogen-rich carbon-circulation oxygen blast furnace reaches a target air volume, wherein the increment of the flow rate of the second decarburized coal gas each time is △c4, the increment of the flow rate of the oxygen each time is △d4, △c4 < △c1, △c4 < △c2, and △c4 < △c3; △d4 < △d1, △d4 < △d2, and △d4 < △d3; the target air volume is the air volume introduced in the normal production state of the hydrogen-rich carbon-circulation oxygen blast furnace; wherein the downtime of the hydrogen-rich carbon-circulation oxygen blast furnace is ≤20 h.

11. The air supply method according to claim 10, wherein In the step of starting the hydrogen-rich carbon-circulation oxygen blast furnace, the volume flow rate ratio of the introduced oxygen and first decarburized coal gas is kept at 1:5-1:3, and the flow rates of the oxygen and the first decarburized coal gas are increased under the condition that the second decarburized coal gas is introduced into the hydrogen-rich carbon-circulation oxygen blast furnace and the volume flow rate ratio of the oxygen and the first decarburized coal gas is kept at 1:5-1:3 in the step of initial establishment of self-circulation.

12. The air supply method according to claim 10, wherein In the mid-term stage of self-circulation, when the flow rate of the first decarburized coal gas is reduced to 0, the flow rates of the second decarburized coal gas and the oxygen are kept unchanged until the volume fraction of CO2 in the second decarburized coal gas is <3% and the volume fraction of N2 in the top coal gas is <30%, and then the flow rates of the oxygen and the second decarburized coal gas are continuously increased to increase the air ratio.

13. The air supply method according to claim 12, wherein When the volume fraction of CO2 in the second decarburized coal gas is <3% and the volume fraction of N2 in the top coal gas is <30% in the mid-term stage of self-circulation, the flow rates of the oxygen and the second decarburized coal gas are continuously increased under the condition that the volume flow rate ratio of the oxygen and the second decarburized coal gas is kept at 1:5-1:

3.

14. The air supply method according to claim 10, wherein The first decarburization step further comprises a dust removal step, and the first dust removal step comprises introducing the pipe network coal gas into a dust removal device for dust removal to filter dust.

15. The method of claim 10, wherein, The second decarburization step further comprises: detecting the total pressure of the oxygen and the first decarburized coal gas and the total pressure of the top coal gas generated, wherein the total pressure of the oxygen and the first decarburized coal gas is P3, and the total pressure of the top coal gas is P4, when P3≥60kpa and P4≥10kpa, the top coal gas is collected and the top coal gas is subjected to a second decarburization to obtain a second decarburized coal gas.

16. The method of claim 10, wherein, The open hydrogen-rich carbon cycle oxygen blast furnace and the second decarburization step further comprise a dust removal step, which comprises: collecting the top coal gas and removing dust from the top coal gas to filter the dust.

17. The air supply method according to claim 10, wherein The open hydrogen-rich carbon cycle oxygen blast furnace and the second decarburization step further comprise a pressurization step, which comprises: collecting the top coal gas and pressurizing the top coal gas, and then subjecting the pressurized top coal gas to a second decarburization.

18. The air supply method according to claim 10, wherein The self-circulation establishment completion step further comprises: the volume fraction of N2 in the top coal gas is <20%.

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