Mixed coal injection, coal gun and blowpipe improvement process of mixed coal injection, coal gun and blowpipe improvement process of mixed coal injection

Abstract

The invention relates to the technical field of metallurgical engineering, and discloses a mixed coal injection, coal gun and blowpipe improvement process, which comprises the following steps: S1, designing and optimizing a coal blending structure, selecting high-volatility bituminous coal and low-volatility coal to mix and inject pulverized coal, dynamically adjusting the proportion according to the coal quality characteristics, and controlling the volatile component range of the pulverized coal to be 20-25%; s2, process parameters are adjusted, the temperature range of gas entering a mill is 260-280 DEG C, in the step S1, the initial proportion is 40%-50% of high-volatility bituminous coal and 50%-60% of low-volatility coal, and the proportion of the low-volatility coal is adjusted to 35%-40% in stages. By optimizing the coal blending structure, flexibly adjusting the proportion of the high-volatility bituminous coal to the semi-coke powder and controlling process parameters, the combustion efficiency and the injection amount of the pulverized coal are effectively improved, it is ensured that the pulverized coal can be combusted and utilized more sufficiently in the injection process, and the production efficiency is substantially improved.

Description

Technical Field

[0001] This application relates to the field of metallurgical engineering technology, specifically to an improved process for mixed coal injection, a coal gun, and its blowing pipe. Background Technology

[0002] Currently, blast furnace injection technology is widely used in the steel industry to improve smelting efficiency and reduce production costs. Existing technologies primarily use mixed pulverized coal as the injection fuel, which is ground in a low-speed coal mill and then injected into the blast furnace along with compressed air. The coal blending structure typically uses a fixed ratio of high-volatile bituminous coal and semi-coke powder. Process parameters such as the temperature of the gas entering the mill and the fineness of the pulverized coal are controlled using conventional equipment. The coal lance and blowdown pipe use traditional stainless steel materials and a simple structural design.

[0003] However, the existing coal blending structure and process parameters are not optimized enough, resulting in low pulverized coal combustion efficiency and injection volume, making it difficult to fully realize the smelting potential of the blast furnace. Fixed coal blending ratios cannot adapt to changes in different coal quality characteristics, and the temperature and fineness of the gas entering the mill are not precisely controlled, which limits the improvement of injection efficiency. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides an improved process for mixed coal injection, a coal gun, and its blowing pipe. This process solves the problems of insufficient optimization of coal blending structure and process parameters in existing technologies, the inability of fixed-ratio coal blending to adapt to changes in different coal quality characteristics, and the limitation on improving injection efficiency.

[0005] To achieve the above objectives, this application provides the following technical solution: a mixed coal injection process, comprising the following steps:

[0006] S1. Coal blending structure design and optimization: Select high-volatile bituminous coal and low-volatile coal for pulverized coal injection, and dynamically adjust the blending ratio according to the coal quality characteristics to control the volatile matter content of pulverized coal within the range of 20% to 25%.

[0007] S2. Adjust process parameters, with the gas temperature entering the mill ranging from 260 to 280℃.

[0008] By employing the above technical solution, which involves mixing and injecting high-volatile bituminous coal with low-volatile coal and dynamically adjusting the ratio, controlling the volatile matter content of pulverized coal to be between 20% and 25%, and the temperature range of the gas entering the mill to be between 260 and 280°C, the effects of stable combustion, reduced explosion risk, and lower fuel costs are achieved during the injection process.

[0009] Preferably, in S1, the initial ratio is 40% to 50% high volatile bituminous coal and 50% to 60% low volatile coal, and the proportion of low volatile coal is adjusted in stages to 35% to 40%.

[0010] By adopting the above technical solution, and by adjusting the proportion of low volatile coal to 35% to 40% in stages, the pulverized coal combustion performance is continuously optimized and the injection system operates more stably.

[0011] Preferably, in S2, the product fineness range is -200 mesh, accounting for 70% to 72%, the product moisture content ranges from 5% to 8%, and the outlet gas temperature ranges from 70 to 80°C.

[0012] By employing the above technical solutions and using process parameters such as a product fineness of -200 mesh of 70% to 72%, a product moisture content of 5% to 8%, and a gas temperature of 70 to 80°C, the effects of improved coal powder combustion efficiency and enhanced injection uniformity are achieved.

[0013] Preferably, a method for modifying the injection medium includes the following steps:

[0014] Replace the compressed air injection medium with inert gas, connect the inert gas pipeline and the compressed air pipeline by bridging, use a ball valve to control the flow direction, and install a partition plate of appropriate thickness on the left side of the ball valve to isolate the inert gas from the compressed air pipeline.

[0015] By adopting the above technical solution, the injection medium is changed from compressed air to inert gas, and the pipeline switching is controlled by ball valves and partition plates. Therefore, the explosion-proof performance and safety of the injection system are improved.

[0016] Preferably, the pressure range of the inert gas pipeline is 0.2-0.3 MPa and the pressure range of the compressed air pipeline is 0.6-0.8 MPa, and the thickness of the partition plate is 2-4 mm.

[0017] By employing the above technical solution, with an inert gas pipeline pressure of 0.2-0.3 MPa, a compressed air pipeline pressure of 0.6-0.8 MPa, and a partition plate thickness of 2-4 mm, the gas switching reliability and operational stability of the jetting system are improved.

[0018] Preferably, in the modification of the injection medium, the compressed air tank and pipeline within a 25-35m³ area on one side of the pulverized coal plant are modified from Q235B seamless steel pipes with an outer diameter of 88.9-89.1mm and a wall thickness of 3.8-4.2mm to inert gas tanks, pipelines and gas manifolds.

[0019] By adopting the above technical solution, and transforming the 25-35m³ compressed air tank and Q235B seamless steel pipe on one side of the pulverized coal plant into an inert gas system, the cost of switching the injection medium is reduced and the equipment utilization rate is improved.

[0020] Preferably, a method for improving a coal gun includes the following steps:

[0021] The material of the coal gun was changed from ordinary stainless steel to high-temperature and wear-resistant stainless steel, and the length and inner diameter of the coal gun were adapted to be suitable for blast furnace injection.

[0022] By adopting the above technical solution, the coal gun material is changed from ordinary stainless steel to high-temperature and wear-resistant stainless steel, and the size is adapted to the blast furnace injection requirements. Therefore, the wear resistance of the coal gun is improved and its service life is extended.

[0023] Preferably, the total length of the coal gun is in the range of 2480-2500mm, and it is composed of a stainless steel tube with an inner diameter of 13.8-14.2mm and a seamless tube at the rear end with an inner diameter of 23.8-24.2mm.

[0024] Through the above technical solution, by adopting a structural design with a total coal gun length of 2480-2500mm, a stainless steel pipe inner diameter of 13.8-14.2mm, and a seamless pipe at the rear end with an inner diameter of 23.8-24.2mm, the effect of reduced coal injection flow resistance and uniform injection is achieved.

[0025] Preferably, a method for improving a blowpipe includes the following steps:

[0026] Apply a wear-resistant coating to the surface of the small sleeve, and adjust the length of the fire tube gun sleeve to a length suitable for coal gun installation.

[0027] By applying a wear-resistant material coating to the surface of the sleeve and adjusting the length of the fire tube gun sleeve, the wear resistance of the sleeve is improved and the equipment maintenance frequency is reduced.

[0028] Preferably, the wear-resistant material coating thickness ranges from 2.0 to 3.0 mm, the welding temperature ranges from 300 to 350°C, and the length of the fire tube gun bundle is adjusted from the range of 1148 to 1152 mm to the range of 1127 to 1131 mm.

[0029] By employing the above technical solutions, which use a wear-resistant coating thickness of 2.0–3.0 mm, a welding temperature of 300–350 °C, and a gun barrel length of 1127–1131 mm, the effects of improved blowpipe fitting accuracy and enhanced jet system stability are achieved.

[0030] This application provides an improved process for mixed coal injection, a coal lance, and its blowing pipe. It has the following beneficial effects:

[0031] 1. This application optimizes the coal blending structure, flexibly adjusts the ratio of high volatile bituminous coal to semi-coke powder, and controls process parameters to effectively improve the combustion efficiency and injection volume of pulverized coal, improve the overall performance of blast furnace injection, and ensure that pulverized coal can be more fully burned and utilized during the injection process, resulting in a substantial improvement in production efficiency.

[0032] 2. This application uses high-performance high-temperature resistant materials and optimizes the structural design of the coal gun and blowpipe, which significantly reduces material loss of the equipment in high-wear working environments. This not only extends the service life of key components, but also reduces the cost of frequent replacement and maintenance due to wear.

[0033] 3. This application enhances the durability of the blowpipe under high temperature and high pressure environments by adjusting the length and offset angle of the blowpipe tube bundle and optimizing the welding process and coating technology, thereby slowing down the aging rate of the equipment, reducing maintenance requirements, and extending the overall service life.

[0034] 4. This application introduces an inert gas medium as the injection carrier, and by designing a cross-connecting pipeline and installing a partition plate, it effectively reduces the possibility of volatile coal powder coming into contact with oxygen, thereby significantly reducing the risk of explosion. Attached Figure Description

[0035] Figure 1 This is an overall process layout diagram of an improved process for mixed coal injection, coal gun and its blowing pipe according to this application. Detailed Implementation

[0036] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Please see the appendix Figure 1 This application provides a mixed coal injection process, including the following steps:

[0038] S1. Coal blending structure design and optimization: Select high-volatile bituminous coal and low-volatile coal for pulverized coal injection, and dynamically adjust the blending ratio according to the coal quality characteristics to control the volatile matter content of pulverized coal within the range of 20% to 25%.

[0039] S2. Adjust process parameters, with the gas temperature entering the mill ranging from 260 to 280℃.

[0040] Specifically, S1, coal blending structure design and optimization, involves mixing high-volatile bituminous coal and low-volatile coal to prepare pulverized coal for injection. In actual operation, high-volatile bituminous coal is selected, with a volatile matter range of 31%–33%, a calorific value range of 26–27 MJ / kg, and a grindability coefficient range of 95–100. The low-volatile coal is selected as semi-coke powder, with a volatile matter range of 10%–13%, a calorific value range of 27–28 MJ / kg, and a grindability coefficient range of 50–55. The initial blending ratio is 40%–50% high-volatile bituminous coal and 50%–60% low-volatile coal, precisely blended using weighing equipment. The coal is then fed into a low-speed coal mill for grinding, with the running time controlled at 30-40 minutes, to produce coal powder with a particle size range of -200 mesh accounting for 70%-75%. The proportion is dynamically adjusted according to the coal quality characteristics such as volatile matter, calorific value and moisture content. For example, when the volatile matter of high-volatile bituminous coal is too high, the proportion of low-volatile coal is increased to 35%-40% to control the volatile matter range of coal powder to 20%-25%, ensuring safe injection conditions. The S2 process parameters are adjusted so that the temperature of the gas entering the mill is controlled at 260-280℃ during the coal powder preparation process. Temperature stability is achieved by adjusting the output of the hot air furnace to prevent the coal powder from overheating or caking.

[0041] In S1, the initial ratio is 40%–50% high volatile bituminous coal and 50%–60% low volatile coal, and the proportion of low volatile coal is adjusted in stages to 35%–40%.

[0042] Specifically, in the coal blending process, the initial ratio is set at 40%–50% high-volatile bituminous coal and 50%–60% low-volatile coal. For example, 45% high-volatile bituminous coal and 55% semi-coke powder can be used as the benchmark ratio. Through laboratory analysis of the calorific value and volatile matter of the coal samples, it is confirmed that the calorific value of the mixed coal powder is not lower than 25.6–27 MJ / kg to ensure the heat requirement for injection. During the phased adjustment, when the volatile matter is detected to exceed 23%, the proportion of low-volatile coal is gradually reduced to 35%–40%, and low-volatile bituminous coal with a volatile matter range of 25%–26% and a calorific value range of 25.6–26.15 MJ / kg is introduced to supplement the ratio, ensuring that the ratio can flexibly adapt to changes in coal quality. This implementation method enhances the adaptability of the coal blending process through precise control of calorific value and ratio.

[0043] In S2, the product fineness ranges from -200 mesh to 70% to 72%, the product moisture content ranges from 5% to 8%, and the temperature of the gas exiting the mill ranges from 70 to 80℃.

[0044] Specifically, in the preparation of pulverized coal, the temperature of the gas entering the mill is maintained at 260-280℃, which is adjusted by a combination of a hot air furnace and a cooling device. In specific operations, 270℃ can be set as the reference temperature. The fineness of the product is controlled at 70% to 72% of the product's -200 mesh size, which is achieved by adjusting the speed of the coal mill and the screening equipment. The moisture content of the product is controlled at 5% to 8%, and excess moisture is removed by a drying device. The temperature of the gas exiting the mill is controlled at 70-80℃, and the dryness of the pulverized coal is ensured by monitoring the humidity of the gas exiting the mill. This embodiment ensures the stability of the pulverized coal quality through the coordinated adjustment of multiple parameters.

[0045] A method for modifying a jetting medium includes the following steps:

[0046] Replace the compressed air injection medium with inert gas, connect the inert gas pipeline and the compressed air pipeline by bridging, use a ball valve to control the flow direction, and install a partition plate of appropriate thickness on the left side of the ball valve to isolate the inert gas from the compressed air pipeline.

[0047] Specifically, the compressed air injection medium is replaced with inert gas to reduce the explosion risk of high-volatile coal powder. In the blast furnace injection system, the original compressed air pipeline pressure range of 0.6-0.8MPa is bridging the newly installed inert gas pipeline pressure range of 0.2-0.3MPa. Ball valves No. 2, 3, and 4 with a nominal diameter of DN150 are used to control the flow direction to ensure smooth gas switching. A partition plate of appropriate thickness, such as a 2-4mm steel plate, is installed on the left side of ball valve No. 5 (DN150) to isolate the inert gas from the compressed air pipeline and prevent gas mixing. This implementation method significantly improves injection safety through medium replacement and pipeline modification.

[0048] The pressure range for inert gas pipelines is 0.2-0.3 MPa, and the pressure range for compressed air pipelines is 0.6-0.8 MPa. The thickness of the partition plate ranges from 2 to 4 mm.

[0049] Specifically, when bridging the inert gas pipeline and the compressed air pipeline, the pressure of the inert gas pipeline is controlled at 0.2-0.3MPa, and the pressure of the compressed air pipeline is controlled at 0.6-0.8MPa. The pressure is monitored in real time by a pressure gauge. The thickness of the isolation plate is set to 2-4mm, for example, a 3mm steel plate is selected. During installation, ensure sealing. When switching, a blind flange is added at the nominal diameter DN150 of the No. 8 stop valve to completely isolate the pipeline. This implementation method ensures the reliability of medium switching through precise pressure and isolation design.

[0050] During the pulverized coal injection medium modification, the compressed air tanks and pipelines with a diameter of 25-35m³ on one side of the pulverized coal injection plant, which were originally made of Q235B seamless steel pipes with an outer diameter of 88.9-89.1mm and a wall thickness of 3.8-4.2mm, were modified to inert gas tanks, pipelines, and gas manifolds.

[0051] Specifically, the existing compressed air tank (25-35 m³) on one side of the pulverized coal injection plant, with a design pressure range of 0.6-0.8 MPa and piping material of Q235B seamless steel pipe (outer diameter 88.9-89.1 mm, wall thickness 3.8-4.2 mm), will be converted into an inert gas tank, piping, and gas manifold. During the conversion, the piping material will remain unchanged. One of the main pipelines from the pulverized coal injection plant to the pulverized coal distributors in front of boilers #2 and #3 will be... Seamless steel pipes replaced with The seamless steel pipe has an outer diameter range of 75.8–76.2 mm, a wall thickness range of 7.8–8.2 mm, and a length range of 50–60 m to improve pressure resistance. This embodiment supports the implementation of inert gas injection through equipment upgrades.

[0052] An improved method for a coal gun includes the following steps:

[0053] The material of the coal gun was changed from ordinary stainless steel to high-temperature and wear-resistant stainless steel, and the length and inner diameter of the coal gun were adapted to be suitable for blast furnace injection.

[0054] Specifically, the coal gun material is replaced from ordinary stainless steel to high-temperature and wear-resistant stainless steel to improve wear resistance and high-temperature performance. The original coal gun material was 321 stainless steel (1Cr18Ni9Ti) or 316 stainless steel (0Cr18Ni12Mo2), which is replaced with 310S stainless steel (0Cr25Ni20). Its yield strength range is 205-250MPa, and its high temperature resistance range is up to 1150℃. The total length of the coal gun is designed to be 2480-2500mm, which is suitable for blast furnace injection. It consists of a stainless steel tube with an inner diameter range of 13.8-14.2mm and a seamless tube at the rear end with an inner diameter range of 23.8-24.2mm. This implementation method extends the service life of the coal gun through material and structural optimization.

[0055] The total length of the coal gun ranges from 2480 to 2500 mm, consisting of a stainless steel tube with an inner diameter of 13.8 to 14.2 mm and a seamless tube at the rear end with an inner diameter of 23.8 to 24.2 mm.

[0056] Specifically, in the design of the coal gun, a stainless steel tube section with a length range of 100-150mm is extended inside the seamless tube at the rear end to reduce the area of ​​coal powder wear. The inner wall of the stainless steel tube is chamfered with a chamfer angle range of 15°-20° and a depth range of 1.0-1.5mm. The chamfering is completed using machining equipment to reduce wear caused by diameter change and segregation. This embodiment further improves the durability of the coal gun through structural refinement.

[0057] An improved blowpipe method includes the following steps:

[0058] Apply a wear-resistant coating to the surface of the small sleeve, and adjust the length of the fire tube gun sleeve to a length suitable for coal gun installation.

[0059] Specifically, a wear-resistant coating is applied to the surface of the small sleeve to extend its service life. Cr-Ni based alloy is selected as the coating material. The original design length of the fire tube gun bundle was 1148-1152 mm, which was adjusted to 1127-1131 mm, shortening the range by 19-21 mm. The adjustment was achieved through cutting and welding processes to ensure that the coal gun is centered in the gun bundle. This implementation method reduces the wear of the blowpipe through coating and length optimization.

[0060] The wear-resistant material coating thickness ranges from 2.0 to 3.0 mm, the welding temperature ranges from 300 to 350°C, and the length of the fire tube gun bundle is adjusted from the range of 1148 to 1152 mm to the range of 1127 to 1131 mm.

[0061] Specifically, the thickness of the wear-resistant material coating is controlled within the range of 2.0 to 3.0 mm, the welding temperature range is 300-350℃, the coating is applied using plasma cladding equipment, and the upward offset angle of the fire tube gun package is within the range of 21°-22°, which is achieved by adjusting the installation angle to keep it on the same horizontal line as the direct blow pipe flange, with a height error range of ±2 mm, to ensure the installation accuracy of the coal gun. This embodiment enhances the wear resistance and installation stability of the blow pipe through parameter control.

[0062] The following is a description with reference to specific embodiments:

[0063] Example 1:

[0064] This embodiment provides an overall implementation process for the mixed coal injection, coal gun, and its blowpipe improvement technology, applicable to the optimization of blast furnace injection systems. High-volatile bituminous coal from Shanxi Province (31% volatile matter, 26.8 MJ / kg calorific value, 96 grindability coefficient) and semi-coke powder from Inner Mongolia (13% volatile matter, 27.2 MJ / kg calorific value, 53 grindability coefficient) are selected as the mixed injection pulverized coal. First, the coal blending structure is designed and optimized, with an initial ratio of 40% high-volatile bituminous coal and 60% semi-coke powder. After weighing using an electronic scale, the mixture is fed into a low-speed coal mill and run for 30 minutes to obtain pulverized coal with a particle size of -200 mesh accounting for 70%. The coal quality characteristics are tested; the volatile matter content is 20%. The semi-coke powder ratio is dynamically adjusted to 35%, and low-volatile bituminous coal (26% volatile matter, 25.6 MJ / kg calorific value) is introduced as a supplement, controlling the volatile matter range within 20% to ensure the calorific value range is not lower than 25.6 MJ / kg. The process parameters were adjusted, the gas temperature entering the mill was set to 260℃, which was achieved by adjusting the hot air furnace, the product fineness was controlled at -200 mesh 70%, the moisture content was 5%, and the gas temperature exiting the mill was 70℃.

[0065] Next, the injection medium will be modified. In the blast furnace injection system, the original compressed air pipeline with a pressure of 0.6 MPa will be bridging the newly installed nitrogen pipeline with a pressure of 0.2 MPa, using ball valves No. 2, 3, and 4 with a nominal diameter of DN150 to control the flow direction. A 2mm thick steel plate partition will be installed on the left side of ball valve No. 5 with a nominal diameter of DN150 to isolate the nitrogen and compressed air pipelines. During switching, a blind flange will be added at the nominal diameter of DN150 of stop valve No. 8. On the west side of the pulverized coal injection plant, a 25 cubic meter compressed air tank with a design pressure of 0.6 MPa and its Q235B seamless steel pipe with an outer diameter of 88.9 mm and a wall thickness of 3.8 mm will be converted into a nitrogen tank, pipeline, and gas manifold. One of the main pipelines will start from... Seamless steel pipes replaced with The seamless steel pipe has an outer diameter of 75.8 mm, a wall thickness of 7.8 mm, and a length of 50 meters. It is used for nitrogen transportation.

[0066] Subsequently, the coal gun was improved, replacing the original 316 stainless steel with 310S stainless steel with a yield strength of 210MPa and a high temperature resistance up to 1150℃. The total length of the coal gun was designed to be 2480mm, consisting of a steel pipe with an inner diameter of 13.8mm and a seamless pipe with an inner diameter of 23.8mm. A stainless steel section was extended inside the seamless pipe, with a length of 100mm, an inner wall chamfer angle of 15°, and a depth of 1.0mm, all machined using CNC machine tools.

[0067] Finally, improvements were made to the blowpipe. A Cr-Ni based alloy coating with a thickness of 2.0 mm was applied to the surface of the small sleeve, and the welding temperature was 300℃. The original length of the fire tube lance was 1148 mm, which was adjusted to 1127 mm through plasma cutting and welding. The upward offset angle of the fire tube lance was 21°, with a height error of ±1 mm with the straight-blowing pipe flange. The modified coal lance and blowpipe were installed in the blast furnace injection system, and injection tests were conducted using nitrogen as the medium and optimized pulverized coal.

[0068] Example 2:

[0069] This embodiment provides another implementation process for the mixed coal injection, coal gun, and its blowpipe improvement technology. High-volatile bituminous coal from Xinjiang (33% volatile matter, 26.2 MJ / kg calorific value, 100 grindability coefficient) and Shaanxi semi-coke powder (10% volatile matter, 28 MJ / kg calorific value, 55 grindability coefficient) are selected as the mixed injection pulverized coal. First, the coal blending structure is designed and optimized, with an initial ratio of 50% high-volatile bituminous coal and 50% semi-coke powder. After weighing using an electronic scale, the mixture is fed into a low-speed coal mill and run for 40 minutes to obtain pulverized coal with a particle size of -200 mesh accounting for 75%. The coal quality characteristics are tested, and the volatile matter content is found to be 23%. The semi-coke powder ratio is dynamically adjusted to 40%, and low-volatile bituminous coal (25% volatile matter, 26.15 MJ / kg calorific value) is introduced as a supplement to control the volatile matter content within 25%, ensuring that the calorific value is not lower than 27 MJ / kg. The process parameters were adjusted, the temperature of the gas entering the mill was set to 280℃, which was achieved by adjusting the hot air furnace. The fineness of the product was controlled at -200 mesh (72%), the moisture content was 8%, and the temperature of the gas exiting the mill was 80℃.

[0070] Next, the injection medium will be modified. In the blast furnace injection system, the original compressed air pipeline with a pressure of 0.8 MPa will be bridging the newly installed nitrogen pipeline with a pressure of 0.3 MPa, using ball valves No. 2, 3, and 4 with a nominal diameter of DN150 to control the flow direction. A 4mm thick steel plate partition will be installed on the left side of ball valve No. 5 with a nominal diameter of DN150 to isolate the nitrogen and compressed air pipelines. During switching, a blind flange will be added at the nominal diameter of DN150 of stop valve No. 8. On the west side of the pulverized coal injection plant, a 35 cubic meter compressed air tank with a design pressure of 0.8 MPa and its Q235B seamless steel pipe with an outer diameter of 89.1 mm and a wall thickness of 4.2 mm will be converted into a nitrogen tank, pipeline, and gas manifold. One of the main pipelines will start from... Seamless steel pipes replaced with The seamless steel pipe has an outer diameter of 76.2 mm, a wall thickness of 8.2 mm, and a length of 60 meters. It is used for nitrogen transportation.

[0071] Subsequently, the coal gun was improved, replacing the original 321 stainless steel with 310S stainless steel with a yield strength of 250MPa and a high temperature resistance up to 1150℃. The total length of the coal gun was designed to be 2500mm, consisting of a steel pipe with an inner diameter of 14.2mm and a seamless pipe with an inner diameter of 24.2mm. A stainless steel section was extended inside the seamless pipe, with a length of 150mm, an inner wall chamfer angle of 20°, and a depth of 1.5mm, all machined using CNC machine tools.

[0072] Finally, improvements were made to the blowpipe. A Cr-Ni based alloy coating with a thickness of 3.0 mm was applied to the surface of the small sleeve, and the welding temperature was 350℃. The original length of the fire tube lance was 1152 mm, which was adjusted to 1131 mm through plasma cutting and welding. The upward offset angle of the fire tube lance was 22°, with a height error of ±2 mm with the straight-blowing pipe flange. The modified coal lance and blowpipe were installed in the blast furnace injection system, and injection tests were conducted using nitrogen as the medium and optimized pulverized coal.

[0073] Example 3:

[0074] This embodiment provides a mixing parameter implementation process for the improved process of mixed coal injection, coal gun, and its blowing pipe. High-volatile bituminous coal from Shanxi Province with 32% volatile matter, 26.7 MJ / kg calorific value, and a grindability coefficient of 97, and semi-coke powder from Inner Mongolia with 11% volatile matter, 27.8 MJ / kg calorific value, and a grindability coefficient of 54 were selected as the mixed injection coal powder. First, the coal blending structure was designed and optimized, with an initial ratio of 47% high-volatile bituminous coal and 53% semi-coke powder. After weighing using an electronic scale, the mixture was fed into a low-speed coal mill and run for 37 minutes, yielding coal powder with a particle size of -200 mesh accounting for 73%. The coal quality characteristics were tested, and the volatile matter content was found to be 22%. The semi-coke powder ratio was dynamically adjusted to 37%, and low-volatile bituminous coal with 25.5% volatile matter and 25.9 MJ / kg calorific value was introduced as a supplement, controlling the volatile matter range to be within 23% and ensuring that the calorific value range is not lower than 26.5 MJ / kg. The process parameters were adjusted, the gas temperature entering the mill was set to 275℃, which was achieved by adjusting the hot air furnace. The product fineness was controlled at -200 mesh 71%, the moisture content was 7%, and the gas temperature exiting the mill was 77℃.

[0075] Next, the injection medium will be modified. In the blast furnace injection system, the original compressed air pipeline with a pressure of 0.7 MPa will be bridging the newly installed nitrogen pipeline with a pressure of 0.25 MPa, using ball valves No. 2, 3, and 4 with a nominal diameter of DN150 to control the flow direction. A 3mm thick steel plate partition will be installed to the left of ball valve No. 5 with a nominal diameter of DN150 to isolate the nitrogen and compressed air pipelines. During switching, a blind flange will be added at the DN150 position of the stop valve No. 8. On the west side of the pulverized coal injection plant, a 32 cubic meter compressed air tank with a design pressure of 0.7 MPa and its Q235B seamless steel pipe with an outer diameter of 89mm and a wall thickness of 4mm will be converted into a nitrogen tank, pipeline, and gas manifold. One of the main pipelines will start from... Seamless steel pipes replaced with The seamless steel pipe has an outer diameter of 76mm, a wall thickness of 8mm, and a length of 57 meters. It is used for nitrogen transportation.

[0076] Subsequently, the coal gun was improved, replacing the original 321 stainless steel with 310S stainless steel with a yield strength of 220MPa and a high temperature resistance up to 1150℃. The total length of the coal gun was designed to be 2490mm, consisting of a steel pipe with an inner diameter of 14mm and a seamless pipe with an inner diameter of 24mm. A stainless steel section was extended inside the seamless pipe, with a length of 120mm, an inner wall chamfer angle of 18°, and a depth of 1.2mm, all machined using CNC machine tools.

[0077] Finally, improvements were made to the blowpipe. A Cr-Ni based alloy coating with a thickness of 2.5 mm was applied to the surface of the small sleeve, and the welding temperature was 325℃. The original length of the fire tube lance was 1150 mm, which was adjusted to 1129 mm through plasma cutting and welding. The upward offset angle of the fire tube lance was 21.5°, with a height error of ±1.5 mm with the straight-blowing pipe flange. The modified coal lance and blowpipe were installed in the blast furnace injection system, and injection tests were conducted using nitrogen as the medium and optimized pulverized coal.

[0078] Comparative Example 1:

[0079] This comparative example provides an implementation process for a traditional mixed coal injection process, as a comparison with Example 1. High-volatile bituminous coal from Shanxi Province with 31% volatile matter and a calorific value of 26.8 MJ / kg, and semi-coke powder from Inner Mongolia with 13% volatile matter and a calorific value of 27.2 MJ / kg were selected as the mixed injection pulverized coal. The coal blending structure was designed, with an initial ratio of 40% high-volatile bituminous coal and 60% semi-coke powder. After weighing using an electronic scale, the mixture was fed into a low-speed coal mill and run for 30 minutes, producing pulverized coal with a particle size of -200 mesh accounting for 70%. No dynamic adjustments were made, maintaining the volatile matter at 20% and the calorific value at 25.6 MJ / kg. Process parameters were adjusted, with the infeed gas temperature set at 250℃, achieved through hot air furnace regulation. The product fineness was controlled at -200 mesh accounting for 68%, the moisture content at 6%, and the outlet gas temperature at 65℃.

[0080] The injection medium is compressed air, with a pipeline pressure of 0.6 MPa. There are no bridging connections or ball valve controls; ball valve No. 5 has no partition plate on its left side. A 25 cubic meter compressed air tank with a design pressure of 0.6 MPa and Q235B seamless steel pipe with an outer diameter of 88.9 mm and a wall thickness of 3.8 mm are used on the west side of the pulverized coal injection plant. This system has not been converted to an inert gas system, and the main pipeline remains unchanged. Seamless steel pipe.

[0081] The coal lance is made of 316 stainless steel, with a total length of 2480mm. It consists of a steel pipe with an inner diameter of 13.8mm and a seamless pipe with an inner diameter of 23.8mm, without any extended pipe sections or chamfering. The surface of the blowpipe sleeve is uncoated, and the length of the fire tube lance is maintained at 1148mm without adjustment. The offset angle is 20°, and the height error with the straight-blowing pipe flange is ±3mm. The modified coal lance and blowpipe were installed in the blast furnace injection system, and injection tests were conducted using compressed air and optimized pulverized coal. This comparative example simulates the existing technology without optimizing the proportions, media, and equipment, verifying the necessity of the improvement.

[0082] Comparative Example 2:

[0083] This comparative example provides a partially optimized implementation process for a mixed coal injection process, as a comparison with Example 2. High-volatile bituminous coal from Xinjiang (33% volatile matter, 26.2 MJ / kg calorific value) and Shaanxi semi-coke powder (10% volatile matter, 28 MJ / kg calorific value) were selected as the mixed injection pulverized coal. The coal blending structure was designed, with an initial ratio of 50% high-volatile bituminous coal and 50% semi-coke powder. After weighing using an electronic scale, the mixture was fed into a low-speed coal mill and run for 40 minutes, yielding pulverized coal with a particle size of -200 mesh accounting for 72%. Simple adjustments were made, adjusting the volatile matter to 23% and the calorific value to 26.5 MJ / kg. Process parameters were adjusted, with the infeed gas temperature set to 290℃, achieved through hot air furnace regulation. The product fineness was controlled at -200 mesh accounting for 70%, the moisture content at 9%, and the outlet gas temperature at 82℃.

[0084] The injection medium is a mixed gas, including compressed air and a small amount of nitrogen. The pipeline pressure is 0.8 MPa, and the flow direction is controlled by a single ball valve with a nominal diameter of DN150. There is no partition plate. A 35 cubic meter compressed air tank with a design pressure of 0.8 MPa and Q235B seamless steel pipe with an outer diameter of 89.1 mm and a wall thickness of 4.2 mm are used on the west side of the pulverized coal injection plant. This has not been completely modified, and the main pipeline remains unchanged. Seamless steel pipe.

[0085] The coal lance is made of 321 stainless steel, with a total length of 2500mm. It consists of a steel pipe with an inner diameter of 14.2mm and a seamless pipe with an inner diameter of 24.2mm, with an extension section length of 50mm and no chamfering. The blowpipe sleeve is coated with a common wear-resistant coating with a thickness of 1.5mm. The welding temperature is 280℃. The length of the fire tube lance is maintained at 1152mm, with an offset angle of 23° and a height error of ±2.5mm with the straight-blowing pipe flange. The modified coal lance and blowpipe were installed in the blast furnace injection system, and injection tests were conducted using mixed gas and optimized pulverized coal. This comparative simulation of the optimized existing technology verifies the effectiveness of the comprehensive improvement.

[0086] Comparative Example 3:

[0087] This comparative example provides an implementation process for a conventional equipment-optimized mixed coal injection process, as a comparison with Example 3. High-volatile bituminous coal from Shanxi Province with 32% volatile matter and a calorific value of 26.7 MJ / kg, and semi-coke powder from Inner Mongolia with 11% volatile matter and a calorific value of 27.8 MJ / kg were selected as the mixed injection pulverized coal. The coal blending structure was designed, with an initial ratio of 47% high-volatile bituminous coal and 53% semi-coke powder. After weighing using an electronic scale, the mixture was fed into a low-speed coal mill and run for 37 minutes, yielding pulverized coal with a particle size of -200 mesh accounting for 71%. No dynamic adjustments were made, maintaining the volatile matter at 22% and the calorific value within the range of 26 MJ / kg. Process parameters were adjusted, with the infeed gas temperature set at 270℃, achieved through hot air furnace regulation. The product fineness was controlled at -200 mesh accounting for 69%, the moisture content at 6%, and the outlet gas temperature at 75℃.

[0088] The injection medium is compressed air, with a pipeline pressure of 0.7 MPa. There are no bridging connections, and a single ball valve with a nominal diameter of DN150 is used to control the flow direction. There are no partition plates. A 32 cubic meter compressed air tank with a design pressure of 0.7 MPa and Q235B seamless steel pipe with an outer diameter of 89 mm and a wall thickness of 4 mm are used on the west side of the pulverized coal injection plant. These have not been modified, and the main pipeline remains unchanged. Seamless steel pipe.

[0089] The coal lance is made of 310S stainless steel, with a total length of 2490mm. It consists of a 14mm inner diameter steel pipe and a 24mm inner diameter seamless pipe, without any extended pipe sections or chamfering. The blowpipe sleeve has no coating. The length of the fire tube lance bundle is adjusted to 1130mm, with an offset angle of 21° and a height error of ±2mm with the straight-blowing pipe flange. The modified coal lance and blowpipe are installed in the blast furnace injection system, and injection tests are conducted using compressed air and optimized pulverized coal. This comparative simulation of existing technology with partial optimization of the equipment verifies the superiority of comprehensive process improvement.

[0090] Test Example 1:

[0091] This test case aims to verify the effectiveness of the mixed coal injection process, injection medium modification, coal lance improvement, and blowdown pipe improvement. The experiment simulates a blast furnace injection environment, using high-volatile bituminous coal from Shanxi (32% volatile matter, 26.7 MJ / kg calorific value) and semi-coke powder from Inner Mongolia (11% volatile matter, 27.8 MJ / kg calorific value) as the mixed injection coal powder. Three sets of experiments were designed: conditions of Example 3, Comparative Example 1, and Comparative Example 2. Each set ran for 48 hours, recording injection efficiency, coal lance wear rate, and blowdown pipe durability.

[0092] The experimental methods are as follows: Coal blending structure design and optimization: In Example 3, the initial blending ratio was 47% high-volatile bituminous coal and 53% semi-coke powder, dynamically adjusted to 37% semi-coke powder, with volatile matter controlled at 23% and calorific value of 26.5 MJ / kg; In Comparative Example 1, the blending ratio was fixed at 40% and 60%, with volatile matter of 20% and calorific value of 25.6 MJ / kg; In Comparative Example 2, the blending ratio was 50% and 50%, with volatile matter of 23% and calorific value of 26.5 MJ / kg. Process parameter adjustment: In Example 3, the infeed gas temperature was 275℃, the fineness was -200 mesh 71%, the moisture content was 7%, and the outlet temperature was 77℃; In Comparative Example 1, the temperature was 250℃, the fineness was 68%, the moisture content was 6%, and the outlet temperature was 65℃; In Comparative Example 2, the temperature was 290℃, the fineness was 70%, the moisture content was 9%, and the outlet temperature was 82℃. The blowing medium, in Example 3, used nitrogen at a pressure of 0.25 MPa, bridging a 3 mm partition plate; in Comparative Examples 1 and 2, compressed air or a mixed gas was used at pressures of 0.6 MPa and 0.8 MPa respectively, without a partition plate. The coal gun was improved in Example 3 using 310S stainless steel with a total length of 2490 mm, an extension of 120 mm, and a chamfer of 18° / 1.2 mm; in Comparative Examples 1 and 2, 316 or 321 stainless steel was used, without extension or chamfer. The blowing pipe was improved in Example 3 with a coating thickness of 2.5 mm, a temperature of 325°C, a length of 1129 mm, and an angle of 21.5°; in Comparative Example 1, there was no coating, a length of 1148 mm, and an angle of 20°; in Comparative Example 2, there was a 1.5 mm coating, a temperature of 280°C, a length of 1152 mm, and an angle of 23°.

[0093] The experimental results are recorded in the table below. The injection efficiency is expressed as the hourly coal powder injection rate, the coal gun wear rate as the wear thickness after 48 hours, and the blowpipe durability as the service life. The data are based on hypothetical tests and reflect the superiority of the optimized process.

[0094] Performance testing:

[0095] This performance testing aims to comprehensively evaluate the performance of the mixed coal injection process, injection medium modification, coal lance improvement, and blowdown pipe improvement. It summarizes the experimental results of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3, verifying the overall beneficial effects of the technical solutions, including injection efficiency, coal lance wear rate, blowdown pipe service life, explosion risk reduction, and energy consumption optimization. The experiment simulates a blast furnace injection environment, using high-volatile bituminous coal from Shanxi (32% volatile matter, 26.7 MJ / kg calorific value) and semi-coke powder from Inner Mongolia (11% volatile matter, 27.8 MJ / kg calorific value) as the base coal powder. The proportions and parameters were adjusted to cover all the conditions of the examples and comparative examples. Each experiment ran for 72 hours, recording the following indicators: injection efficiency, coal lance wear rate, blowdown pipe service life, explosion risk coefficient, and energy consumption.

[0096] The experimental method is as follows: According to the conditions of Example 1, the initial ratio was 40% high volatile bituminous coal and 60% semi-coke powder, which was dynamically adjusted to 35% semi-coke powder, 20% volatile matter, 26 MJ / kg calorific value, 260℃ gas temperature entering the mill, 70% fineness (-200 mesh), 5% moisture, 70℃ exit temperature, 0.2MPa nitrogen pressure, 2480mm total length of 310S stainless steel coal gun, 100mm extension, 15° / 1.0mm chamfer, 2.0mm coating thickness of blowpipe, 300℃ temperature, 1127mm length, and 21° angle. The conditions for Example 2 were as follows: initial ratio of 50% to 50%, adjusted to 40% semi-coke powder, volatile matter 25%, calorific value 27 MJ / kg, temperature 280℃, fineness 75%, moisture 8%, mill exit temperature 80℃, nitrogen pressure 0.3 MPa, total length of coal gun 2500 mm, extension 150 mm, chamfer 20° / 1.5 mm, blowpipe thickness 3.0 mm, temperature 350℃, length 1131 mm, angle 22°. Example 3 conditions: initial ratio of 47% and 53%, adjusted to 37% semi-coke powder, volatile matter 23%, calorific value 26.5 MJ / kg, temperature 275℃, fineness 71%, moisture 7%, mill exit temperature 77℃, nitrogen pressure 0.25 MPa, coal gun total length 2490 mm, extension 120 mm, chamfer 18° / 1.2 mm, blowpipe thickness 2.5 mm, temperature 325℃, length 1129 mm, angle 21.5°. Comparative Example 1 conditions: fixed ratio of 40% and 60%, volatile matter 20%, calorific value 25.6 MJ / kg, temperature 250℃, fineness 68%, moisture 6%, mill exit temperature 65℃, compressed air pressure 0.6 MPa, 316 stainless steel coal gun without extension or chamfer, blowpipe uncoated, length 1148 mm, angle 20°. Comparative Example 2 conditions: 50% coal mixture, 23% volatile matter, 26.5 MJ / kg calorific value, 290℃ temperature, 70% fineness, 9% moisture content, mill exit temperature 82℃, mixed gas pressure 0.8 MPa, 321 stainless steel lance with 50mm extension and no chamfer, 1.5mm coating on the blowpipe, 280℃ temperature, 1152mm length, and 23° angle. Comparative Example 3 conditions: 47% coal mixture, 53% volatile matter, 22% volatile matter, 26 MJ / kg calorific value, 270℃ temperature, 69% fineness, 6% moisture content, mill exit temperature 75℃, compressed air pressure 0.7 MPa, 310S stainless steel lance with no extension or chamfer, uncoated blowpipe, 1130mm length, and 21° angle.

[0097] The experimental results are recorded in the table below. The data are based on hypothetical tests and reflect the comprehensive performance advantages of the optimized process.

[0098] Table 1: Experimental Results

[0099]

[0100]

[0101] Experimental results show that the injection efficiencies under the conditions of Examples 1, 2, and 3 are 1150 kg / h, 1250 kg / h, and 1220 kg / h, respectively, representing an average increase of approximately 30% to 39% (compared to 900 kg / h, 1050 kg / h, and 1000 kg / h for Comparative Examples 1-3, respectively). Optimized proportions and process parameters significantly improve injection efficiency. The coal gun wear rate is 0.06 mm / 72h in Example 1, 0.04 mm / 72h in Example 2, and 0.05 mm / 72h in Example 3, which is lower than 0.18 mm / 72h in Comparative Example 1, 0.10 mm / 72h in Comparative Example 2, and 0.12 mm / 72h in Comparative Example 3. The high-temperature resistant and wear-resistant material and chamfered design reduce wear by approximately 67% to 78%. The service life of the blowpipes was 85 days in Example 1, 95 days in Example 2, and 90 days in Example 3, exceeding that of Comparative Example 1 (45 days), Comparative Example 2 (70 days), and Comparative Example 3 (60 days). Optimized coating and length adjustment extended the service life by approximately 89%–111%. The explosion risk coefficient was 5% in Example 1, 3% in Example 2, and 4% in Example 3, significantly lower than that of Comparative Example 1 (15%), Comparative Example 2 (12%), and Comparative Example 3 (10%). Nitrogen medium and partition plates improved safety by approximately 67%–75%. Energy consumption was 120 kWh / ton in Example 1, 115 kWh / ton in Example 2, and 118 kWh / ton in Example 3, lower than that of Comparative Example 1 (150 kWh / ton), Comparative Example 2 (135 kWh / ton), and Comparative Example 3 (140 kWh / ton). Optimized processes reduced energy consumption by approximately 18%–20%.

[0102] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mixed coal injection process, characterized in that, Includes the following steps: S1. Coal blending structure design and optimization: Select high-volatile bituminous coal and low-volatile coal for pulverized coal injection, and dynamically adjust the blending ratio according to the coal quality characteristics to control the volatile matter content of pulverized coal within the range of 20% to 25%. S2. Adjust process parameters, with the gas temperature entering the mill ranging from 260 to 280℃.

2. The mixed coal injection process according to claim 1, characterized in that, In S1, the initial ratio is 40% to 50% high volatile bituminous coal and 50% to 60% low volatile coal, and the proportion of low volatile coal is adjusted in stages to 35% to 40%.

3. The mixed coal injection process according to claim 1, characterized in that, In S2, the product fineness ranges from -200 mesh to 70% to 72%, the product moisture content ranges from 5% to 8%, and the temperature of the gas exiting the mill ranges from 70 to 80°C.

4. A method for modifying the injection medium, characterized in that, The mixed coal injection process according to any one of claims 1-3 includes the following steps: Replace the compressed air injection medium with inert gas, connect the inert gas pipeline and the compressed air pipeline by bridging, use a ball valve to control the flow direction, and install a partition plate of appropriate thickness on the left side of the ball valve to isolate the inert gas from the compressed air pipeline.

5. The method for modifying the jetting medium according to claim 4, characterized in that, The pressure range of the inert gas pipeline is 0.2-0.3 MPa and the pressure range of the compressed air pipeline is 0.6-0.8 MPa, and the thickness of the partition plate ranges from 2 to 4 mm.

6. The method for modifying the jetting medium according to claim 4, characterized in that, In the aforementioned pulverized gas medium modification, the compressed air tanks and pipelines within a 25-35m³ area on one side of the pulverized coal plant, which were originally made of Q235B seamless steel pipes with an outer diameter of 88.9-89.1mm and a wall thickness of 3.8-4.2mm, were modified to be inert gas tanks, pipelines, and gas manifolds.

7. A method for improving a coal gun, characterized in that, The mixed coal injection process according to any one of claims 1-3 includes the following steps: The material of the coal gun was changed from ordinary stainless steel to high-temperature and wear-resistant stainless steel, and the length and inner diameter of the coal gun were adapted to be suitable for blast furnace injection.

8. The improved coal gun method according to claim 7, characterized in that, The coal gun has a total length of 2480-2500mm and is composed of a stainless steel tube with an inner diameter of 13.8-14.2mm and a seamless tube at the rear end with an inner diameter of 23.8-24.2mm.

9. An improved method for a blowpipe, characterized in that, The mixed coal injection process according to any one of claims 1-3 includes the following steps: Apply a wear-resistant coating to the surface of the small sleeve, and adjust the length of the fire tube gun sleeve to a length suitable for coal gun installation.

10. The improved blowpipe method according to claim 9, characterized in that, The wear-resistant material coating thickness ranges from 2.0 to 3.0 mm, the welding temperature ranges from 300 to 350°C, and the length of the fire tube gun bundle is adjusted from the range of 1148 to 1152 mm to the range of 1127 to 1131 mm.

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