Damping-down material design and control method for hydrogen-rich carbon circulating oxygen blast furnace

Abstract

The invention belongs to the technical field of low-carbon metallurgy, and discloses a damping-down material design and control method for a hydrogen-rich carbon circulating oxygen blast furnace, which is suitable for being used during regular maintenance or long-period planned maintenance of a large hydrogen-rich carbon circulating oxygen blast furnace when a traditional mode is converted into a HyCROF process mode. According to the method, by determining an overall strategy of damping-down materials, the average ore-coke ratio of the whole furnace is controlled to be 2.4-2.8, and the total ore reduction ratio is controlled to be 20%-30%; a damping-down material structure is designed in a segmented mode, a blast furnace material column is divided into a plurality of segments, and different parameters are designed for all the segments; executing segmented adding operation in sequence; and after reblowing, a heat system is connected, and the Si content of molten iron is kept in a high-position interval. The in-furnace initial environment with abundant heat, good air permeability and appropriate slag iron fluidity can be constructed, stable transition of the blast furnace is achieved, safe and smooth process switching is guaranteed, and the problems that in the prior art, heat storage is insufficient, material column air permeability is poor, and transition is not smooth are solved.

Description

Technical Field

[0001] This invention relates to the field of low-carbon metallurgical technology, and in particular to a method for designing and controlling the restoring blast load of a hydrogen-rich carbon circulating oxygen blast furnace. Background Technology

[0002] Hydrogen-rich carbon-recirculating oxygen blast furnaces are a crucial technological pathway for achieving low-carbon and green transformation in the steel industry. Compared to traditional blast furnaces, HyCROF blast furnaces utilize oxygen-blown blast and recirculate heated top gas (rich in CO and H2) after CO2 removal, significantly altering the gas distribution, heat balance, and reduction process within the furnace. When such blast furnaces require planned maintenance or process switching, a shutdown operation is necessary. During the shutdown, physicochemical reactions within the blast furnace nearly cease, heat is lost, and the permeability of the charge column deteriorates. After blast is restored, the design and addition strategy of the shutdown charge are critical to the rapid recovery of furnace operation and adaptation to the intensified smelting requirements of the new HyCROF process.

[0003] Traditional blast furnace rest charge design primarily focuses on "insulating" the hearth and providing initial heat after resuming blast, typically employing a single load reduction strategy. However, for HyCROF blast furnaces, the goal after process switching or maintenance is not only to restore production but also to quickly establish a new balance of high intensity, high oxygen enrichment, and high injection volume. Traditional rest charge designs suffer from the following problems: First, the heat reserve may be insufficient to meet the high heat requirements of the hearth for rapid load increases after HyCROF mode blasting; second, the permeability structure of the charge column is not optimized for the penetration of high-temperature circulating gas into the softening zone, easily leading to uneven charging and excessive pressure differential after resuming blast; third, the lack of a smooth thermal gradient from the hearth to the furnace body makes it difficult to achieve a smooth transition from the rest state to the high-intensity smelting state of HyCROF. Therefore, a rest charge solution specifically designed for large HyCROF blast furnaces is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for designing and controlling the rest blast load in a hydrogen-rich carbon-circulating oxygen blast furnace, so as to solve the technical defects mentioned in the background art.

[0005] To achieve the above objectives, the basic solution provided by this invention is: a method for designing and controlling the down-wind charge in a hydrogen-rich carbon-circulating oxygen blast furnace, comprising the following steps: S1. Determine the overall strategy for blast furnace shutdown: Based on the blast furnace volume, planned shutdown time and target HyCROF operating parameters, determine the target value of the overall load of the entire furnace. The target value of the overall load ensures that the average ore-coke ratio of the entire furnace is controlled between 2.4 and 2.8, and the total reduction in ore ratio is controlled between 20% and 30%. S2. Segmented design of blast furnace charge structure: Divide the blast furnace charge column into at least five segments from bottom to top, including the lower section of the tuyere, the belly section, the waist section, the lower section of the furnace body, the middle section of the furnace body, and the upper section of the furnace body. Design different ore reduction ratios, coke batches, [Si] target values, and slag basicity R2 for each segment. S3. Perform segmented addition operation: Before the blast furnace is shut down, add the shutdown materials to the blast furnace in the order from bottom to top according to the material list designed in S2. S4. Connection of hot regime after air supply: After air supply, in the early stage of ramp-up in HyCROF mode, the actual molten iron content [Si] is maintained in the high range of 0.8%-1.2% by controlling the air temperature, oxygen enrichment rate and decarburization gas injection volume.

[0006] Furthermore, the specific requirements for the segmented design in S2 are as follows: Lower tuyere section: ore reduction ratio is 8%-12%, coke batch size increases by 0.5-1.5 tons compared to normal production, and the target [Si] content in molten iron is set at 0.7%-0.9%; Furnace belly and waist section: ore reduction ratio is 25%-35%, coke batch size is 17.5-19.0 tons, and the target [Si] content in molten iron is 1.4%-1.6%. Clean coke is added in this area, with the amount of clean coke accounting for 5%-8% of the total coke amount; Lower furnace body to upper furnace body section: ore reduction ratio gradually decreases from 15%-22% to 0%-5%, coke batch size gradually decreases from 16.5-17.5 tons to 14.5-15.5 tons, and the target [Si] content in molten iron gradually decreases from 1.1%-1.3% to 0.7%-0.9%.

[0007] Furthermore, throughout the entire process of adding the restorative material, the slag basicity R2 was stably controlled within the range of 1.00 to 1.05.

[0008] Furthermore, the clean coke is added at the furnace belly section and the furnace waist section.

[0009] Furthermore, the total amount of coke added to the resting air feed (including clean coke) makes the total number of loading cycles of the feed column reach 40-50 batches.

[0010] Compared with the prior art, the advantages of this invention are: 1. Precise heat reserve: By setting high [Si] targets in stages and significantly reducing the load on the furnace belly and waist, and adding clean coke in key areas, the furnace hearth provides ample and reasonably distributed heat for rapid intensity improvement after HyCROF mode re-blowing, avoiding the risk of furnace cooling in the early stage of re-blowing.

[0011] 2. Optimized feed column structure: The addition of a large amount of coke and clean coke to the furnace belly and waist section significantly improves the air permeability and liquid permeability of the softening zone, ensuring that high-temperature circulating gas can pass through smoothly, creating good kinetic conditions for the HyCROF process to perform effectively.

[0012] 3. Smooth transition gradient: From the lower part of the furnace to the upper part, the load and [Si] target gradually decrease, forming a smooth transition zone, which enables the blast furnace to smoothly transition from the shutdown and heat preservation state to the HyCROF high-intensity smelting state, reducing furnace condition fluctuations.

[0013] 4. Ensuring smooth operation and safety: This method, through comprehensive control, ensures the stability of the material column during the shutdown period, effectively preventing abnormal furnace conditions such as material collapse, slippage, and suspension after the resumption of ventilation, thus ensuring the safety and smooth operation of the process switching process. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the segmented structure of the air-supported material of the present invention; Figure 2 This is a graph showing the change in the ore reduction ratio and [Si] target of each section of the resting air material according to the present invention. Detailed Implementation

[0015] The present invention will be further described in detail below through specific embodiments: like Figures 1 to 2 As shown: A method for designing and controlling the down-wind load in a hydrogen-rich carbon-circulating oxygen blast furnace, comprising the following steps: S1. Determine the overall strategy for blast furnace shutdown: Based on the blast furnace volume, planned shutdown time and target HyCROF operating parameters, determine the target value of the overall load of the entire furnace. The target value of the overall load ensures that the average ore-coke ratio of the entire furnace is controlled between 2.4 and 2.8, and the total reduction in ore ratio is controlled between 20% and 30%.

[0016] S2. Segmented Design of Blast Furnace Burst Structure: Divide the blast furnace burden column into at least five segments from bottom to top, including the lower tuyere section, the belly section, the waist section, the lower section of the furnace body, the middle section of the furnace body, and the upper section of the furnace body. Design different ore reduction ratios, coke batches, [Si] target values, and slag basicity R2 for each segment. The specific requirements for segmented design are as follows: Lower section of the tuyeres: ore reduction ratio is 8%-12%, coke batch size increases by 0.5-1.5 tons compared to normal production, and the target [Si] content in molten iron is set at 0.7%-0.9%; Furnace belly and waist section: ore reduction ratio is 25%-35%, coke batch size is 17.5-19.0 tons, and the target [Si] content in molten iron is 1.4%-1.6%. Clean coke is added in this area, accounting for 5%-8% of the total coke content; Lower section of the furnace body to upper section of the furnace body: ore reduction ratio gradually decreases from 15%-22% to 0%-5%, coke batch size gradually decreases from 16.5-17.5 tons to 14.5-15.5 tons, and the target [Si] content in molten iron gradually decreases from 1.1%-1.3% to 0.7%-0.9%. Clean coke is added in the furnace belly and waist sections.

[0017] S3. Perform segmented addition operation: Before the blast furnace is shut down, according to the material list designed in S2, add each segment of shutdown material to the blast furnace in order from bottom to top.

[0018] S4. Heat regime connection after blast: After blast is supplied, in the initial stage of ramp-up in HyCROF mode, the actual molten iron [Si] content is maintained at a high level of 0.8%-1.2% by controlling the blast temperature, oxygen enrichment rate and decarburization gas injection volume; throughout the entire blast rest material addition process, the slag basicity R2 is stably controlled within the range of 1.00 to 1.05; the total coke addition amount (including clean coke) of the blast rest material makes the total number of charge cycles of the material column reach 40-50 batches.

[0019] A certain enterprise has a 2500m 3 Taking the example of a blast furnace switching from traditional to HyCROF process with a planned 32-hour shutdown, the specific implementation of this invention is described below: S1. Determine the overall strategy for blast furnace shutdown load: Based on the blast furnace volume and the requirement of a target daily output of 6,000 tons of HyCROF, the overall load target for this shutdown load is determined to be 2.708, and the total reduction in ore is 24.2% (including net coke).

[0020] S2. Segmented design of the air-supported structure: As shown in the attached document. Figure 1 and 2 As shown, the ventilation material is divided into 6 sections for design, and the specific material list is shown in Table 1: Table 1, 2500m 3 HyCROF Blast Furnace Shutdown Material Change List material section Reduction of ore ratio Coke (t) Sintering (t) Team (t) Mineral lot (t) [Si] Target (%) <![CDATA[R2]]> O / C Number of loads status quo - 16.80 42.0 17.0 60.0 0.4 1.04 3.571 - Under the spotlight 11.06% 17.00 36.0 18.0 54.0 0.8 1.03 3.176 5 Furnace belly 26.89% 18.00 30.0 17.0 47.0 1.5 1.02 2.611 8 Net coke 1 - 40.0 - - - - - - - Furnace waist 31.89% 18.50 29.0 16.0 45.0 1.5 1.00 2.432 7 Net coke 2 - 20.0 - - - - - - - Furnace body bottom 19.04% 16.60 32.0 16.0 48.0 1.2 1.01 2.892 8 Furnace body 12.50% 16.00 33.0 17.0 50.0 1.0 1.02 3.125 8 stove body 2.37% 15.20 36.0 16.0 53.0 0.8 1.05 3.487 8 total 24.2% 800.9 2169 - - - - 2.708 44 S3. Perform segmented feeding operation: Before the planned shutdown, strictly follow the above material list and start feeding from the lower section of the tuyeres until all the upper section of the furnace body is loaded into the furnace. A total of 800.9 tons of coke (including 60 tons of net coke) and 2169 tons of ore were added, forming a material column structure with 44 feeding cycles.

[0021] S4. Thermal Regime Connection After Blast Furnace Resumption: After blast furnace blasting, the HyCROF ramp-up plan was initiated. In the initial 8 hours, by controlling the hot blast temperature at 1150℃ and gradually introducing decarburized gas and oxygen enrichment, the actual [Si] content in the molten iron was successfully maintained at a relatively high level of 0.8%-1.0%. This effectively connected with the 1.5% high [Si] target set for the hearth and waist sections during the rest blast period, ensuring ample heat in the hearth and maintaining a physical heat level consistently above 1500℃. Thanks to the excellent heat reserve and permeable structure, the blast furnace blasting proceeded smoothly after resumption, with stable pressure differentials, and daily output recovered to 5472 tons within 24 hours, laying a solid foundation for a rapid increase to the subsequent target of 6000 tons per day.

[0022] This invention, through the above-mentioned refined and structured design and control of the restorative blast furnace material, successfully solves the technical problem of difficult furnace condition recovery and uneven transition during process switching or long-term maintenance of large HyCROF blast furnaces.

[0023] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for designing and controlling the down-wind load in a hydrogen-rich carbon-circulating oxygen blast furnace, characterized in that, Includes the following steps: S1. Determine the overall strategy for blast furnace shutdown: Based on the blast furnace volume, planned shutdown time and target HyCROF operating parameters, determine the target value of the overall load of the entire furnace. The target value of the overall load ensures that the average ore-coke ratio of the entire furnace is controlled between 2.4 and 2.8, and the total reduction in ore ratio is controlled between 20% and 30%. S2. Segmented design of blast furnace charge structure: Divide the blast furnace charge column into at least five segments from bottom to top, including the lower section of the tuyere, the belly section, the waist section, the lower section of the furnace body, the middle section of the furnace body, and the upper section of the furnace body. Design different ore reduction ratios, coke batches, [Si] target values, and slag basicity R2 for each segment. S3. Perform segmented addition operation: Before the blast furnace is shut down, add the shutdown materials to the blast furnace in the order from bottom to top according to the material list designed in S2. S4. Connection of hot regime after air supply: After air supply, in the early stage of ramp-up in HyCROF mode, the actual molten iron content [Si] is maintained in the high range of 0.8%-1.2% by controlling the air temperature, oxygen enrichment rate and decarburization gas injection volume.

2. The method for designing and controlling the rest blast load of a hydrogen-rich carbon-circulating oxygen blast furnace according to claim 1, characterized in that, The specific requirements for the segmented design in S2 are as follows: Lower tuyere section: ore reduction ratio is 8%-12%, coke batch size increases by 0.5-1.5 tons compared to normal production, and the target [Si] content in molten iron is set at 0.7%-0.9%; Furnace belly and waist section: ore reduction ratio is 25%-35%, coke batch size is 17.5-19.0 tons, and the target [Si] content in molten iron is 1.4%-1.6%. Clean coke is added in this area, accounting for 5%-8% of the total coke content; Lower furnace body to upper furnace body section: ore reduction ratio gradually decreases from 15%-22% to 0%-5%, coke batch size gradually decreases from 16.5-17.5 tons to 14.5-15.5 tons, and the target [Si] content in molten iron gradually decreases from 1.1%-1.3% to 0.7%-0.9%.

3. The method for designing and controlling the rest blast load in a hydrogen-rich carbon-circulating oxygen blast furnace according to claim 1, characterized in that, Throughout the entire process of adding the restorative material, the slag basicity R2 was stably controlled within the range of 1.00 to 1.

05.

4. The method for designing and controlling the rest blast load of a hydrogen-rich carbon-circulating oxygen blast furnace according to claim 2, characterized in that, The clean coke is added at the furnace belly section and the furnace waist section.

5. The method for designing and controlling the rest blast load of a hydrogen-rich carbon-circulating oxygen blast furnace according to claim 1, characterized in that, The total amount of coke added to the resting air feed (including clean coke) makes the total number of loading cycles of the feed column reach 40-50 batches.

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