Control method of converter wet dust removal system

Abstract

The invention relates to a control method of a wet dust removal system of a converter. The control method comprises the step of differently setting micro differential pressure, the rotating speed of a fan and the water flow of a spray tower according to different oxygen steps of the converter. According to the control method of the converter wet dust removal system, the whole process of the converter smelting process is deeply combined, the air volume needed by the converter in each stage is controlled, the method that the fan frequency conversion speed regulation is matched with the circular seam opening degree control is used, the accurate air volume is provided in the converter smelting process, and the air volume control response is rapid. And the accurate air volume can reduce the consumption of turbid circulating water while improving the dust removal effect of the spray tower.

Description

Technical Field

[0001] The invention relates to a control method for a converter wet dust removal system and belongs to the technical field of environmental protection. Background Art

[0002] With the increase in environmental protection efforts in recent years, dust emissions and carbon emissions must be implemented in accordance with the emission standards of metallurgical enterprises. As a major smoke and dust emitter, iron and steel metallurgical enterprises must not only consider the concentration of smoke and dust particles not exceeding the standard, but also consider the carbon emissions not exceeding the standard. At the same time, the cost of producing a ton of steel by enterprises also needs to be further reduced. Compressing production costs and striving for the maximum benefit space are important problems currently faced by enterprises. The flue gas generated in the converter steelmaking process of steel enterprises is treated through a primary dust removal pipeline. The flue gas particulate matter concentration is high, the carbon emission is large, and the water vapor and electricity energy consumption is large. How to consume less water vapor and electricity energy in the converter steelmaking process and increase the converter gas recovery is an important means to reduce production costs. However, reducing the concentration of flue gas particles and reducing carbon emissions in the converter steelmaking process are also problems that enterprises have to face. The converter steelmaking process must solve the relationship between production cost and environmental protection. The most important thing is to control the air volume of the primary dust removal system. The quality of air volume control directly affects the dust removal effect of the primary dust removal system, the consumption of water vapor and electricity, and the gas recovery.

[0003] In the prior art, the air volume control of the primary dust removal system adopts the method of fan variable frequency speed regulation and the method of adjusting the system air volume by adjusting the ring gap opening of the constant speed fan. In the actual converter smelting process, the flue gas in the furnace changes greatly. When the fan works at a high speed, the speed regulation response is slow, and there is a great hysteresis in the adjustment and control of the air volume. The ring gap uses a hydraulic servo mechanism to adjust the air volume, which also has hysteresis. Single frequency conversion control or ring gap opening adjustment control not only has a slow response to the dust removal duct air volume control, but also consumes a lot of water vapor and electricity energy. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to overcome the shortcomings of the above-mentioned technology and provide a control method for a converter wet dust removal system which can improve the quality and amount of coal gas recovery and reduce the dust particle emission concentration and carbon emission.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: a control method for a converter wet dust removal system, comprising the following steps: (1) The rated speed of the fan of the converter wet dust removal system is r, and the fan speed is preset as follows: r1=26.7%r, r2=60%r, r3=66.7%r, r4=73.3%r, r5=80%r, r6=90%r; The maximum water flow rate of the spray tower of the converter wet dust removal system is f, and the water flow rate of the spray tower is preset as follows: f1=40%f, f2=50%f, f3=62.5%f, f4=75%f, f5=87.5%f, f6=100%f; (2) At the beginning of the converter batch, the converter differential pressure P is set to P = +0.0pa, the fan speed R = r1, and the spray tower water flow F = f1; (3) During the scrap steel adding stage in the converter, the differential pressure P is set to P=+0.0pa, the fan speed R=r2, and the water flow rate of the spray tower F=f2; (4) During the converter iron addition stage, the differential pressure P is set to P = +0.0pa, the fan speed R = r3, and the spray tower water flow F = f3; (5) During the converter blowing-first charging stage, the differential pressure P is set to P=+10.0pa, the fan speed R=r5, and the spray tower water flow F=f6; (6) During the converter blowing-second charging stage, the differential pressure P is set to P=+20.0pa, the fan speed R=r5, and the spray tower water flow F=f6; (7) At the initial stage of converter blowing-gas recovery, the differential pressure P is set to P=-10.0pa, the fan speed R=r6, and the spray tower water flow F=f5; (8) In the middle stage of converter blowing-gas recovery, the differential pressure P is set to P=-20.0pa, the fan speed R=r6, and the spray tower water flow F=f5; (9) In the late stage of converter blowing-gas recovery, the differential pressure P is set to P=-10.0pa, the fan speed R=r6, and the spray tower water flow F=f5; (10) During the secondary gun measurement stage, the differential pressure P is set to P = +10.0pa, the fan speed R = r5, and the spray tower water flow F = f4; (11) During the steel-making process of the converter, the differential pressure P is set to P = +0.0 pa, the fan speed R = r3, and the water flow rate of the spray tower F = f4; (12) During the converter slag splashing stage, the differential pressure P is set to P = +0.0 pa, the fan speed R = r4, and the spray tower water flow F = f4; (13) At the end of the furnace, the differential pressure P is set to P = +0.0pa, the fan speed R = r1, and the water flow rate of the spray tower F = f1.

[0006] A further improvement of the above scheme is that the micro differential pressure P of the converter is adjusted by the size of the annular gap opening of the converter.

[0007] The control method of the converter wet dust removal system provided by the present invention deeply combines the whole process of the converter smelting process, controls the air volume required by the converter at each stage, and uses the method of coordinating the frequency conversion speed regulation of the fan and the ring seam opening control to provide accurate air volume in the converter smelting process, and the air volume control responds quickly. The precise air volume can reduce the consumption of turbid circulating water while improving the dust removal effect of the spray tower. The unique micro-differential pressure control of the air volume in the converter gas recovery process can improve the converter gas quality and increase the gas recovery volume. The 6-speed speed regulation of the fan can save electricity consumption compared to the method of adjusting the air volume by the ring seam at a constant speed, which plays an important role in reducing the production cost of the enterprise. It has a very obvious effect on reducing the emission of smoke particles and carbon emissions in the converter steelmaking process. Combined with the equipment function and production process, it has a wide range of applications and has very good development prospects. Implementation

[0008] The control method of the converter wet dust removal system of this embodiment is applied to the converter oxygen blowing stage, and therefore, "oxygen step" is usually used to represent a certain time period of the converter oxygen blowing.

[0009] If the on-site converter equipment cannot meet the control method of the converter wet dust removal system of this embodiment, the equipment needs to be modified first. Specifically: the constant speed fan is modified for frequency conversion. The fan has a multi-speed debugging function. The fan inverter is set to achieve 6-speed control, and logical programming is performed with the converter oxygen step in the PLC to achieve control of different fan speeds in different oxygen step stages of the converter.

[0010] Adding a flow regulating valve to the spray tower gun pipeline can realize the regulation and control of the spray gun flow at different stages of the oxygen step.

[0011] Increase data collection and data analysis. Data collection mainly includes flue air volume, fan speed, annular gap opening, spray tower spray gun flow, furnace mouth micro differential pressure, and dust meter smoke detection. Connect the data acquisition instrument to the converter server port, and count the data to be collected according to the converter oxygen step. Data collection mainly includes flue air volume, fan speed, annular gap opening, spray tower spray gun flow, furnace mouth micro differential pressure, and dust meter smoke detection value. These signals are collected through the first, second, and third level systems and then summarized and stored to form a large amount of historical data. According to the artificially set conditions during the operation of the equipment, the corresponding functional relationship between the speed and the air volume in the dust removal pipeline when the annular gap opening remains unchanged is obtained; the corresponding functional relationship between the annular gap opening and the air volume in the dust removal pipeline when the speed remains unchanged is obtained by analysis; the corresponding relationship between the speed remains unchanged, the furnace mouth micro differential pressure setting value and feedback value and the annular gap opening is obtained by analysis.

[0012] In this way, through long-term data analysis, the optimal air volume control mode in each stage of the smelting oxygen step is obtained, and the logical control program for the fan speed, annular gap opening, spray tower water flow, and micro differential pressure settings of the converter in different oxygen steps is compiled, so that different air volume control modes are automatically configured and executed in different oxygen steps during converter smelting, thereby achieving better results.

[0013] The control method of the converter wet dust removal system of this embodiment specifically includes: (1) The rated speed of the fan is r, and the fan speed presets are: r1=26.7%r, r2=60%r, r3=66.7%r, r4=73.3%r, r5=80%r, r6=90%r.

[0014] The maximum water flow rate of the spray tower is f, and the water flow rate of the spray tower is preset as follows: f1=40%f, f2=50%f, f3=62.5%f, f4=75%f, f5=87.5%f, f6=100%f.

[0015] The converter's micro differential pressure is adjusted by the annular gap opening. Generally speaking, the annular gap opening is adjusted between 29% and 37%, and can also be adjusted to other values ​​when process requirements change.

[0016] (2) In the "start of the furnace" stage of the oxygen step, the micro differential pressure P of the converter is set to P=+0.0pa, the fan speed R=r1, and the water flow rate of the spray tower F=f1; in this stage, there is no scrap steel or molten iron in the converter, the micro differential pressure is 0, the minimum annular gap opening can meet the process, the minimum fan speed can achieve energy saving, and the water flow rate of the spray tower is in a small flow state to avoid nozzle blockage and reduce the consumption of turbid circulating water.

[0017] (3) In the oxygen step "converter plus scrap steel" stage, the micro differential pressure P is set to P = +0.0pa, the fan speed R = r2, and the spray tower water flow F = f2; in this stage, the scrap steel in the converter produces very small amounts of dust, and there is basically no chemical reaction between the low-temperature scrap steel and the furnace at about 700°C, and no smoke is generated. The minimum annular gap opening can meet the process, and the speed R = r2 can ensure the rapid increase of the fan speed in the next oxygen step, increase the spray tower water flow F = f2, and remove the small amount of dust generated by the scrap steel.

[0018] (4) In the oxygen step "converter adding molten iron" stage, the micro differential pressure P is set to P=+0.0pa, the fan speed R=r3, and the spray tower water flow F=f3; in this stage, the molten iron produces a large amount of smoke and dust, but because the angle of the converter during the iron adding period is 20-45 degrees, most of the smoke and dust is absorbed by the secondary dust removal, and only a small part of the smoke and dust enters the primary dust removal pipeline through the smoke hood. The minimum annular gap opening can meet the process, combined with the speed R=r3, it can meet the process dust removal requirements, increase the spray tower water flow F=f3, and remove the dust generated by the iron adding.

[0019] (5) In the oxygen step "converter blowing-first charging" stage, the micro differential pressure P is set to P=+10.0pa, the fan speed R=r5, and the spray tower water flow F=f6; in this stage, after the oxygen lance is lowered, the converter is charged with raw and auxiliary materials for the first time. At this time, a large amount of dust (from raw and auxiliary materials) and a small amount of carbon dioxide and carbon monoxide (the initial carbon-oxygen reaction is not violent) are generated in the furnace. The flue gas generated is mainly dust. The furnace mouth micro differential pressure is set to P=+10.0pa, so that the furnace mouth is in a micro positive pressure state to prevent the atmosphere from entering the furnace mouth and burning carbon monoxide. The oxygen concentration drops slowly, affecting the start time of gas recovery, and avoiding serious smoke at the furnace mouth, causing environmental pollution; increasing the fan speed R=r5 is conducive to quickly extracting the flue gas in the furnace, and at the same time cooperating with the annular seam to quickly realize the control of the micro differential; increasing the spray tower water flow F=f6 to increase the dust removal effect of the spray tower on the smoke in the flue gas and the cooling effect on the smoke.

[0020] (6) In the oxygen step "converter blowing-second charging" stage, the micro differential pressure P is set to P=+20.0pa, the fan speed R=r5, and the spray tower water flow F=f6; at this stage, the carbon-oxygen reaction in the furnace has begun to intensify, and carbon dioxide and carbon monoxide are in a process of rapid increase. At the same time, the flue gas is also accompanied by dust generated during the charging process. The furnace mouth micro differential pressure P=+20.0pa keeps the furnace mouth in a micro positive pressure state to prevent the atmosphere from entering the furnace mouth to burn carbon monoxide, while reducing the oxygen concentration in the flue gas, which is conducive to the rapid satisfaction of gas recovery conditions and avoids serious smoke at the furnace mouth, causing environmental pollution. Maintaining the fan speed R=r5 is conducive to quickly extracting the flue gas in the furnace, and at the same time, the annular seam is used to quickly control the micro differential. Increasing the spray tower water flow F=f6 increases the dust removal effect of the spray tower on the smoke in the flue gas and the cooling effect on the smoke.

[0021] (7) In the oxygen step "converter blowing-the initial stage of gas recovery", the micro differential pressure P is set to P=-10.0pa, the fan speed R=r6, and the spray tower water flow F=f5; in this stage, carbon dioxide and carbon monoxide are in a process of rapid increase, the carbon monoxide content has met the gas recovery concentration, and the dust in the flue gas is reduced compared with the previous stage. The furnace mouth micro differential pressure is set to P=-10.0pa, the annular seam opening is automatically increased, the fan speed R=r6 is increased, and the flue gas duct air volume is increased, which is conducive to improving the gas recovery quality and increasing the gas recovery output. At the same time, since the dust in the flue gas is reduced compared with the previous stage, the spray tower water flow F=f5 is appropriately reduced, which is conducive to reducing the flue wind resistance and avoiding system surge.

[0022] (8) In the oxygen step "converter blowing-mid-stage of gas recovery", the micro differential pressure P is set to P=-20.0pa, the fan speed R=r6, and the spray tower water flow F=f5; in this stage, the carbon dioxide concentration in the furnace begins to decrease, and the carbon monoxide concentration reaches the highest concentration in smelting, with a concentration range of 40%-70%. The dust concentration in the flue gas has not changed much compared with the previous stage. The furnace mouth micro differential pressure P=-20.0pa, the annular seam opening is automatically increased, and the fan speed R=r6 is maintained to maximize the pipeline air volume, maximize the gas recovery output, and maintain the spray tower water flow F=f5, which is beneficial to reduce the flue wind resistance and avoid system surge.

[0023] (9) In the oxygen step "converter blowing-late gas recovery" stage, the micro differential pressure P is set to P=-10.0pa, the fan speed R=r6, and the spray tower water flow F=f5; in this stage, the carbon content in the molten iron is in a declining state. Affected by the bottom blowing of the converter process in the late blowing stage and the position of the oxygen lance, the carbon dioxide concentration in the furnace begins to rise again, and the carbon monoxide concentration begins to decrease. Finally, in the late gas recovery stage, the carbon dioxide concentration is greater than the carbon monoxide concentration, and the furnace mouth micro differential pressure P=-10.0pa, which appropriately reduces the negative pressure at the furnace mouth and reduces the amount of air entering the furnace mouth, allowing carbon monoxide to continue to maintain above the recovery concentration value for a long time, extending the gas recovery time, maintaining the fan speed R=r6, and ensuring the gas recovery output to the greatest extent. Maintaining the spray tower water flow F=f5 is beneficial to reducing the flue wind resistance and avoiding system surge.

[0024] (10) In the oxygen step "auxiliary gun measurement" stage, the micro differential pressure P is set to P = +10.0pa, the fan speed is R = r5, and the spray tower water flow rate is F = f4; in this stage, the converter blowing has been completed, the gas recovery is finished, and the steel can be tapped only after the auxiliary gun determines the carbon and oxygen components. The furnace mouth micro differential pressure P = +10.0pa puts the furnace mouth in a micro positive pressure state, the annular seam automatically reduces its opening, the fan speed is reduced by R = r5, the pipeline air volume is reduced, and excessive loss of molten steel temperature is avoided. The spray tower water flow rate F = f4 is maintained, and the consumption of turbid circulating water is reduced under the premise of meeting the requirements of dust removal and flue gas cooling.

[0025] (11) In the oxygen step "converter steel tapping" stage, the micro differential pressure P is set to P = +0.0pa, the fan speed is R = r3, and the spray tower water flow rate is F = f4; in this stage, the flue gas is accompanied by dust during the converter steel tapping process. Maintaining the fan speed R = r3 and the minimum opening of the annular seam can meet the process dust removal requirements, and maintaining the spray tower water flow rate F = f4 to remove the dust generated by steel tapping.

[0026] (12) In the oxygen step "converter slag splashing" stage, the micro differential pressure P is set to P = +0.0pa, the fan speed R = r4, and the spray tower water flow F = f4; in this stage, the converter uses nitrogen to blow the steel slag at the bottom of the furnace to splash slag. At this time, flue gas containing dust is generated in the furnace. The fan speed R = r4 is appropriately increased, and the minimum opening of the annular seam can meet the process dust removal requirements, and the spray tower water flow F = f4 is maintained to remove the dust generated by the splashing slag.

[0027] (13) In the "end of the furnace" stage of the oxygen step, the differential pressure P is set to P = +0.0pa, the fan speed R = r1, and the spray tower water flow F = f1. In this stage, there is no scrap steel or molten iron in the converter, the minimum ring gap opening can meet the process, the minimum fan speed can achieve energy saving, the minimum spray tower water flow, and the nozzle is in the minimum flow state to avoid nozzle blockage and reduce the consumption of turbid ring water.

[0028] By implementing the control method of the converter wet dust removal system of this embodiment, the following effects have been achieved: First, the gas recovery volume increased. In the "double slag" mode of the 150-ton converter, the average gas recovery volume per furnace increased from 14,562 m³ to 17,699 m³, and the gas efficiency of a single furnace increased by RMB 1,944.9. In the "single slag" mode of the 150-ton converter, the average gas recovery volume per furnace increased from 20,998 m³ to 22,884 m³, and the gas efficiency of a single furnace increased by RMB 1,131.6.

[0029] Second, the fan energy consumption is reduced. Under the current one-time dust removal conditions of our factory, the fan consumes 2553.7 kwh of electricity for smelting a furnace of molten steel before the improvement, and consumes 1976.9 kwh of electricity after using this method, which is 576.8 kwh less than the same period last year, and the economic benefit of a single furnace is 605.6 yuan.

[0030] Third, the consumption of turbid circulating water is reduced. Under the current one-time dust removal conditions of the three 150-ton converters in our factory, the four spray guns of the spray tower spray at a constant flow rate before the improvement, and the annual consumption is 11.775 million tons. After using this method, the flow rate of the four spray guns of the spray tower is adjusted in steps, and the annual consumption is 8.466 million tons, saving 3.309 million tons of turbid circulating water annually.

[0031] The present invention is not limited to the above embodiments. Any technical solution formed by equivalent replacement falls within the protection scope required by the present invention.

Claims

1. A control method for a converter wet dust removal system, characterized in that: The steps include: (1) The rated speed of the fan of the converter wet dust removal system is r, and the fan speed is preset as follows: r1=26.7%r, r2=60%r, r3=66.7%r, r4=73.3%r, r5=80%r, r6=90%r; The maximum water flow rate of the spray tower of the converter wet dust removal system is f, and the water flow rate of the spray tower is preset as follows: f1=40%f, f2=50%f, f3=62.5%f, f4=75%f, f5=87.5%f, f6=100%f; (2) At the beginning of the converter batch, the converter differential pressure P is set to P = +0.0pa, the fan speed R = r1, and the spray tower water flow F = f1; (3) During the scrap steel adding stage in the converter, the differential pressure P is set to P=+0.0pa, the fan speed R=r2, and the water flow rate of the spray tower F=f2; (4) During the converter iron addition stage, the differential pressure P is set to P = +0.0pa, the fan speed R = r3, and the spray tower water flow F = f3; (5) During the converter blowing-first charging stage, the differential pressure P is set to P=+10.0pa, the fan speed R=r5, and the spray tower water flow F=f6; (6) During the converter blowing-second charging stage, the differential pressure P is set to P=+20.0pa, the fan speed R=r5, and the spray tower water flow F=f6; (7) At the initial stage of converter blowing-gas recovery, the differential pressure P is set to P=-10.0pa, the fan speed R=r6, and the spray tower water flow F=f5; (8) In the middle stage of converter blowing-gas recovery, the differential pressure P is set to P=-20.0pa, the fan speed R=r6, and the spray tower water flow F=f5; (9) In the late stage of converter blowing-gas recovery, the differential pressure P is set to P=-10.0pa, the fan speed R=r6, and the spray tower water flow F=f5; (10) During the secondary gun measurement stage, the differential pressure P is set to P = +10.0pa, the fan speed R = r5, and the spray tower water flow F = f4; (11) During the steel-making process of the converter, the differential pressure P is set to P = +0.0 pa, the fan speed R = r3, and the water flow rate of the spray tower F = f4; (12) During the converter slag splashing stage, the differential pressure P is set to P = +0.0 pa, the fan speed R = r4, and the spray tower water flow F = f4; (13) At the end of the furnace, the differential pressure P is set to P = +0.0pa, the fan speed R = r1, and the water flow rate of the spray tower F = f1.

2. The control method of the converter wet dust removal system according to claim 1, characterized in that: The micro differential pressure P of the converter is adjusted by the size of the annular gap opening of the converter.