A low-carbon injection method with coke dedusting ash

Abstract

A low-carbon injection method of adding coke dust removal ash, including dust removal machine pre-adjustment dust removal ash part, tank truck transfer direct part, premixing part and injection part; coke dust removal ash passes through the dust removal machine pre-adjustment dust removal ash part, tank truck transfer direct part, premixing part and injection part in turn and then enters the blast furnace. The coke dust removal ash is used to realize resource recycling utilization and achieve the purpose of reducing cost and increasing efficiency in ironmaking.

Description

Technical Field

[0001] This invention relates to a low-carbon injection method for adding coke dust, and more particularly to a method for reducing production costs and carbon emissions by adding coke dust to the injection system, belonging to the field of blast furnace ironmaking technology. Background Technology

[0002] Dust generated during steel production accounts for approximately 15%-20% of the total solid waste. Its composition is complex and diverse; for example, converter dust contains 40%-60% iron, and electric furnace dust contains 5%-30% zinc. If not effectively recycled, this dust can easily cause PM2.5 / PM10 pollution. Therefore, the resource recycling of steel industry dust is of significant strategic importance in multiple dimensions, including environmental governance, resource conservation, economic benefits, and low-carbon transformation, and is a key link in promoting the green development of the steel industry. Coke dust, as a fine particulate solid waste generated during coking production and transportation, is particularly important for the sustainable development of the coking-steel industry chain. This material has a fixed carbon content of 40%-65%, higher than that of general thermal coal, a volatile matter content of 5%-15%, and a calorific value of approximately 16-22 kcal. Coke dust, at MJ / kg, possesses significant energy and carbon value. Studies have shown that replacing coal with each ton of coke powder can reduce CO2 emissions by approximately 1.8 tons. However, in the utilization of coke dust in blast furnace injection, a systematic process has not yet been established. Related practices largely rely on localized adjustments based on experience in individual blast furnaces, lacking mature and complete technical records and standards, which restricts its large-scale, standardized, and efficient application. Therefore, a method for adding coke dust to the injection system is needed to fill the technological gap in the field of coke dust addition. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-carbon injection method for adding coke dust, which can add coke dust to the injection system, thereby reducing production costs and carbon emissions.

[0004] The problem described in this invention is solved by the following technical solution: A low-carbon injection method for adding coke dust includes a dust collector pre-conditioning section, a tanker car transfer straight-through section, a premixing section, and an injection section; the coke dust enters the blast furnace after passing through the dust collector pre-conditioning section, the tanker car transfer straight-through section, the premixing section, and the injection section in sequence.

[0005] The above-mentioned low-carbon injection method for adding coke dust includes the following steps in the pre-conditioning dust removal section of the dust collector: When coke dust needs to be collected, clean the accumulated dust in the ash hopper at the bottom of the bag filter beforehand; reduce the frequency of the feeding fan of the bag filter to 32HZ to reduce the negative pressure at the suction port; adjust the valve opening of the dust suction port to 50%; thereby increasing the proportion of coke dust in the ash hopper.

[0006] The above-mentioned low-carbon injection method for adding coke dust includes the following steps in the tanker truck transfer straight-through section: Connect the discharge valve at the bottom of the ash hopper of the bag filter to the inlet of the environmentally friendly suction and discharge tanker through a connecting pipe. Use the vacuum pump of the environmentally friendly suction and discharge tanker to create negative pressure inside the tank. Then open the ash discharge valve of the ash hopper to start unloading ash until the environmentally friendly suction and discharge tanker is filled with the required amount of dust. Then turn off the vacuum pump and disconnect the connecting pipe. The environmentally friendly suction and discharge tanker truck is driven to the side of the vertical mill. The feed valve is installed on the side wall of the coal pipe under the vertical mill. The discharge port of the environmentally friendly suction and discharge tanker truck is connected to the feed valve on the side wall of the coal pipe under the vertical mill through a connecting pipe.

[0007] The premixing step in the above-mentioned low-carbon injection method for adding coke dust includes the following steps: The environmentally friendly suction and discharge tanker is pressurized inside, and the dust is blown into the vertical mill through the coal outlet pipe; at the same time, the raw coal enters the coal outlet pipe from the coal bunker through the sealed weighing coal feeder and falls into the vertical mill; the dust and raw coal are ground and mixed in the vertical mill. The ratio of dust collected to raw coal should be controlled at 1:2. By mixing coke dust to reduce the overall volatile matter to 13%, the proportion of bituminous coal can be indirectly increased, reducing the cost of pulverized coal injection while ensuring the safe and stable operation of the mill system. During the pressurized blowing dust removal process of the environmentally friendly suction and discharge tank truck, the dust conveying pressure is controlled within 40 kPa; During the operation of the vertical mill, the mill vibration value is controlled within 5 mm / s, and the outlet temperature of the vertical mill is controlled below 80℃ to ensure the safety of the mill system.

[0008] The above-mentioned low-carbon injection method for adding coke dust includes the following steps in the injection process: After the mixture of dust and raw coal is blown into the injection tank, the mixture accounts for less than five percent of the total weight of the material in the injection tank. Adjust the pressure of the injection tank to 50 kPa; clean the filter promptly when the pressure difference before and after the main filter of the injection system exceeds 100 kPa to ensure smooth injection.

[0009] This invention utilizes coke dust to achieve resource recycling and reduce costs and increase efficiency in ironmaking; by controlling the ash conveying pressure and mill vibration value, it ensures that the pipeline is not blocked while reducing the scouring and wear of the dust on the mill system; by controlling the ratio of raw coal to dust, it reduces the scouring and wear of coke dust on the mill system's pipelines and valves; by mixing coke dust, it reduces the overall volatile matter, indirectly increasing the bituminous coal ratio, reducing pulverized coal injection costs while ensuring the safe and stable operation of the mill system; by controlling the proportion of coke dust in the mixed coal, it ensures good fluidity after mixing; and by controlling the injection tank pressure and pipeline pressure difference, it ensures smooth injection, achieving cost reduction and efficiency improvement. Attached Figure Description

[0010] Figure 1 This invention provides a technical roadmap for a low-carbon injection method that adds coke dust to the cleaning process. Detailed Implementation

[0011] See Figure 1 This invention includes a dust collector pre-adjustment dust removal section, a tanker truck transfer straight-through section, a premixing section, and a pulse-jet section. The function of the dust collector pre-adjustment dust removal section is to increase the proportion of coke dust removal in the bag filter dust collector and decrease the proportion of ore dust removal, with the aim of increasing the carbon content of the dust removal. The tanker truck transfer straight-through section transfers the dust removal ash from the dust collector to the vertical mill. The premixing section ensures that the dust removal ash is fully mixed with the raw coal powder. The pulse-jet section blows the normal raw coal powder and the mixed raw coal powder with the dust removal ash into the blast furnace. The coke dust removal ash enters the blast furnace after passing through the dust collector pre-adjustment dust removal section, the tanker truck transfer straight-through section, the premixing section, and the pulse-jet section in sequence.

[0012] The pre-adjustment dust removal section of the dust collector includes the following steps: When coke dust needs to be collected, clean the accumulated dust in the ash hopper at the bottom of the bag filter beforehand; reduce the frequency of the feeding fan of the bag filter to 32HZ to reduce the negative pressure at the suction port; adjust the valve opening of the dust suction port to 50%; thereby increasing the proportion of coke dust in the ash hopper.

[0013] The main component of coke dust is carbon, which has low density and light weight; the main component of ore dust is minerals such as iron oxide, which has high density and heavy weight. When a lower airflow blows, the lighter coke dust is easily carried away by the airflow, while the heavier ore dust is more likely to fall or is difficult to blow away.

[0014] The frequency of the fan directly determines its speed and power. A lower frequency means a decrease in the total air volume and total air pressure provided by the fan. The purpose is to create an airflow environment that is conducive to separation. The air force cannot be too strong, otherwise it will suck up the heavy mineral lime along with it, and the separation effect will not be achieved.

[0015] Through the above adjustments, the resistance to air intake from the coke dust-generating point remains relatively unchanged; the resistance to air intake from the ore dust-generating point increases significantly, resulting in a sharp reduction in the amount of air and dust that can be drawn in; with the total air volume reduced, the intake channel for ore and lime is artificially restricted, which causes the system airflow to mainly concentrate on drawing materials from the coke dust-generating point, thereby reducing the mixing of ore and lime at the source; ultimately reducing the proportion of mineral powder in the dust collector ash, and significantly increasing the carbon content of the coke dust collector ash.

[0016] The tanker truck transfer through section includes the following steps: Connect the discharge valve at the bottom of the ash hopper of the bag filter to the inlet of the environmentally friendly suction and discharge tanker through a connecting pipe. Use the vacuum pump of the environmentally friendly suction and discharge tanker to create negative pressure inside the tank. Then open the ash discharge valve of the ash hopper to start unloading ash until the environmentally friendly suction and discharge tanker is filled with the required amount of dust. Then turn off the vacuum pump and disconnect the connecting pipe. The environmentally friendly suction and discharge tanker truck is driven to the side of the vertical mill. The feed valve is installed on the side wall of the coal pipe under the vertical mill. The discharge port of the environmentally friendly suction and discharge tanker truck is connected to the feed valve on the side wall of the coal pipe under the vertical mill through a connecting pipe. The connecting pipe here is a self-made seamless steel pipe buffer pipe with thickened pipe wall to reduce wear on the pipeline system.

[0017] The premixing process includes the following steps: The environmentally friendly suction and discharge tanker is pressurized inside, and the dust is blown into the vertical mill through the coal outlet pipe; at the same time, the raw coal enters the coal outlet pipe from the coal bunker through the sealed weighing coal feeder and falls into the vertical mill; the dust and raw coal are ground and mixed in the vertical mill. The ratio of dust collector ash to raw coal should be controlled at 1:2. Coke dust collector ash is dry and has good fluidity, while raw coal usually contains a certain amount of moisture. Adding dry dust collector ash is equivalent to introducing a natural "desiccant" and "dispersant" into the mill. It can help to quickly remove the moisture in the raw coal, prevent coal powder from adhering to the inner wall of the mill, thereby improving grinding efficiency and ventilation efficiency, and increasing the output per unit time.

[0018] By mixing coke dust with raw coal to reduce the overall volatile matter to 13%, the proportion of bituminous coal can be indirectly increased, reducing the cost of pulverized coal injection while ensuring the safe and stable operation of the mill system. Coal used for pulverized coal injection is usually divided into anthracite and bituminous coal. Anthracite has low volatile matter and high price, while bituminous coal has high volatile matter and low price. For safety reasons, the proportion of bituminous coal is traditionally limited, but this results in higher production costs. After adding coke dust, because the volatile matter of coke dust is extremely low, mixing it with raw coal will lower the average volatile matter of the entire mixture. By mixing coke dust with other materials to reduce overall volatile matter, the proportion of bituminous coal can be increased. The improvement in bituminous coal quality can be calculated using the following formula: ; and These are the volatile components of raw coal powder and coke dust, respectively. It is the volatile matter of bituminous coal; and The quantities of raw coal powder and coke dust are respectively. To improve the quality of bituminous coal, calculations show that adding coke dust can reduce the volatile matter content of the blended coal from 18% to 13%. This provides room for increasing the bituminous coal ratio in subsequent blended coal production, reducing pulverized coal injection costs while ensuring the safe and stable operation of the mill system. Because the overall volatile matter of the mixture is "diluted" and reduced by the coke dust, production personnel are allowed to add more cheap, high-volatile bituminous coal to the formula without worrying about exceeding the total volatile matter limit; this reduces the total cost of pulverized coal injection.

[0019] During the pressurized blowing of dust removal ash by the environmentally friendly suction and discharge tanker truck, the ash conveying pressure is controlled within 40 kPa; if the pressure is too high, the airflow speed will be too fast, which may lead to increased wear at the bends of the pipeline. Therefore, the pressure is controlled at a lower level to ensure that the dust removal ash flows in a stable and dense pneumatic conveying state. During vertical mill operation, the mill vibration value is controlled within 5 mm / s, and the mill outlet temperature is controlled below 80℃ to ensure the safety of the mill system. The mill will vibrate when grinding materials. Excessive vibration may indicate uneven feeding, uneven wear of internal liners or steel balls, or mechanical failure. Strictly controlling the vibration value is to protect the core components of the mill and prevent unplanned shutdowns due to mechanical damage. Coke dust is a combustible powder. When it is suspended in the air and reaches a certain temperature, there is a risk of dust explosion. Therefore, the outlet temperature is controlled within 80℃, setting a safety temperature red line below the ignition point to ensure production safety.

[0020] The blowing section includes the following steps: After the mixture of coke dust and raw coal is blown into the injection tank, the mixture accounts for less than 5% of the total weight of the material in the injection tank. Although the coke dust itself is dry, its particle shape and surface characteristics are different from those of pulverized coal. An excessively high proportion, greater than 5%, may disrupt the overall fluidization characteristics of the mixed pulverized coal, leading to poor material flow, arching, or unstable flow in the injection tank, which seriously affects the continuity and precision of the injection. Therefore, the proportion of the raw coal mixture with coke dust is kept below 5% of the total material in the injection tank to maximize economic benefits under the absolute premise of ensuring the stable and smooth operation of the blast furnace. Adjust the pressure of the injection tank to 50 kPa; clean the filter promptly when the pressure difference before and after the main filter of the injection system exceeds 100 kPa to ensure smooth injection. Example

[0021] Pre-treat the accumulated ash in the bag filter to ensure that the dust collected by the subsequent environmentally friendly suction and discharge tanker is treated dust with high carbon content; adjust the frequency of the feeding fan to 32HZ; reduce the valve opening on the ash pipeline to 50%; then transfer the dust in the ash hopper to the vertical mill position through the environmentally friendly suction and discharge tanker; then blow the dust into the vertical mill and mix it with the raw coal through the connecting pipe, with an ash conveying pressure of 38kPa; during this process, control the ratio of dust to raw coal to be 1:2; control the mill vibration value to be within 5mm / s, and the outlet temperature to 73°; Control the proportion of coke dust in the mixed coal to less than 5% to ensure good fluidity after mixing while reducing costs and increasing efficiency; appropriately increase the pressure of the injection tank to 50 kPa, and clean the filter in time when the pipeline differential pressure exceeds 100 kPa to ensure smooth injection.

[0022] After adopting the technology described in this process, the amount of dust generated by the blast furnace injection coke is 30t / day, accounting for 3% of the pulverized coal used in the blast furnace; based on the current price of bituminous coal of 900 yuan / t and anthracite of 1000 yuan / t, the cost of mixed coal is 970 yuan / t, and the mixed coal is 70% anthracite + 30% bituminous coal; 970 yuan / t = 70% * 1000 yuan / t + 30% * 900 yuan / t; Coke dust replaces 24 tons / day of mixed pulverized coal, calculated at a replacement ratio of 0.8; the resulting benefit is 23,300 yuan / day, and the annual benefit is 8,497,200 yuan; 8,497,200 yuan = 24 tons * 970 yuan / ton * 365 days; Calculations show that this process generates significant economic benefits. Utilizing coke dust achieves resource recycling and reduces costs while increasing efficiency in ironmaking.

Claims

1. A low-carbon injection method for adding coke dust, characterized in that: It includes a dust collector pre-adjustment dust removal section, a tanker car transfer straight passage section, a premixing section, and a pulse-jet section; the coke dust enters the blast furnace after passing through the dust collector pre-adjustment dust removal section, the tanker car transfer straight passage section, the premixing section, and the pulse-jet section in sequence. The pre-adjustment dust removal section of the dust collector includes the following steps: When coke dust needs to be collected, clean the accumulated dust in the ash hopper at the bottom of the bag filter in advance; reduce the frequency of the feeding fan of the bag filter to 32Hz to reduce the negative pressure at the suction port; adjust the valve opening of the dust suction port to 50%; thereby increasing the proportion of coke dust in the ash hopper. The tanker truck transfer through section includes the following steps: Connect the discharge valve at the bottom of the ash hopper of the bag filter to the inlet of the environmentally friendly suction and discharge tanker through a connecting pipe. Use the vacuum pump of the environmentally friendly suction and discharge tanker to create negative pressure inside the tank. Then open the ash discharge valve of the ash hopper to start unloading ash until the environmentally friendly suction and discharge tanker is filled with the required amount of dust. Then turn off the vacuum pump and disconnect the connecting pipe. Drive the environmentally friendly suction and discharge tanker truck to the side of the vertical mill. The feed valve is installed on the side wall of the coal pipe under the vertical mill. The discharge port of the environmentally friendly suction and discharge tanker truck is connected to the feed valve on the side wall of the coal pipe under the vertical mill through a connecting pipe. The premixing process includes the following steps: The environmentally friendly suction and discharge tanker is pressurized inside, and the dust is blown into the vertical mill through the coal outlet pipe; at the same time, the raw coal enters the coal outlet pipe from the coal bunker through the sealed weighing coal feeder and falls into the vertical mill; the dust and raw coal are ground and mixed in the vertical mill. The ratio of dust collector ash to raw coal should be controlled at 1:

2. By mixing coke dust to reduce the overall volatile matter to 13%, the proportion of bituminous coal can be indirectly increased, reducing the cost of pulverized coal injection while ensuring the safe and stable operation of the mill system. During the pressurized blowing dust removal process of the environmentally friendly suction and discharge tank truck, the dust conveying pressure is controlled within 40 kPa; During the operation of the vertical mill, the mill vibration value is controlled within 5 mm / s, and the vertical mill outlet temperature is controlled below 80℃ to ensure the safety of the mill system. The blowing section includes the following steps: After the mixture of dust and raw coal is blown into the injection tank, the mixture accounts for less than five percent of the total weight of the material in the injection tank. Adjust the pressure of the injection tank to 50 kPa; clean the filter promptly when the pressure difference before and after the main filter of the injection system exceeds 100 kPa to ensure smooth injection.

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