Method for automatically controlling opening degree of secondary venturi throat of converter

Abstract

The present invention relates to a method for automatically controlling the opening degree of a secondary venturi throat of a converter. In a converter blowing process, when a converter is in a feeding state, when the converter blowing reaches a slag formation time point, after the converter blowing reaches a slag formation time point, before a sublance process test of the converter, and when the molten steel temperature approaches a smelting endpoint, a flue gas analyzer, a flame machine vision device, and an audio signal collection device collect data information such as the gas content of the top gas, a change in the light intensity of a converter mouth or the light intensity at the lower edge of a converter mouth, and a sonar slag measurement value during converter blowing, and transmit the collected data information to a PLC / DCS system. When the converter is in a feeding state, the opening degree of the secondary venturi throat of the converter is automatically controlled in the converter blowing process. The present invention has the advantages that: manual intervention is not needed, smoke and dust coming out are reduced, the gas recovery rate is increased, and production safety is maintained.

Description

A method for automatically controlling the opening of the second throat of a converter Technical Field

[0001] The invention relates to the technical field of converter gas recovery, in particular to a method for automatically controlling the opening of a converter throat. Background Art

[0002] In converter steelmaking, the control of the flue throat is very important. If it is not properly controlled, the following situations will occur: it will affect the gas recovery rate and affect the carbon emissions of negative energy steelmaking; it will easily cause smoke and dust to overflow, affecting environmental protection; it will easily cause flames to burn the factory frame and platform equipment, endangering production safety.

[0003] The existing methods for controlling the second-tier throat include the following:

[0004] 1. Manual fire control, when the fire is too big, manually adjust the opening of the nozzle.

[0005] 2. Automatic adjustment of the micro differential pressure at the furnace mouth. This method cannot be used normally because the pressure port is on the inside of the smoke hood, the environment is harsh, and it is often blocked by hot smoke, steel slag, and splashing objects.

[0006] 3. Static mode adjustment method, based on big data, sets a fixed opening at a fixed time; Publication No. CN107630120B discloses "A method for adjusting the second throat of a converter", the disclosure content of which is as follows:

[0007] 1) During the addition of iron and scrap steel, the opening of the second pipe throat is controlled at 40% to 50%;

[0008] 2) During the silicon-manganese oxidation period before the oxygen blowing volume reaches 20%, the RD valve opening is controlled at 50% to 60%;

[0009] 3) During the intense carbon-oxygen oxidation period with an oxygen blowing rate of 20% to 75%, the RD valve opening is controlled at more than 90%;

[0010] 4) After the oxygen blowing volume reaches 75%, the RD valve opening is controlled at 65% to 75%;

[0011] 5) At the beginning of the auxiliary gun process test, the RD valve opening is controlled at 50% to 60%;

[0012] 6) After the oxygen blowing is completed, the RD valve opening is controlled at 40% to 50%;

[0013] The shortcoming is that the adjustment method is to statically control the second throat.

[0014] 4. Automatic mode adjustment method, publication number: CN105154615B, discloses "an automatic adjustment device and adjustment method for the second throat of a converter", which breaks through the traditional micro-differential pressure control method of the furnace mouth pressure sensor, and adds a gas analyzer sensor, an oxygen analyzer sensor, an oxygen gun position sensor, and an oxygen regulating valve position sensor, which are respectively installed on the sides of the flue gas duct of the fan and the three-way valve. The carbon monoxide content, oxygen content, and oxygen gun position signals are used as identifiers, and the throat hydraulic station is controlled by PLC. When all the detection signals meet the conditions, the weight moves downward to the specified position. When any of the detection signals does not meet the conditions, the weight moves upward and returns to the initial position, thereby realizing automatic control and adjustment of the second throat of the converter; the second throat is dynamically controlled by gas content, but the disadvantage is that the variable is single.

[0015] Summary of the Invention

[0016] The object of the present invention is to provide a method for automatically controlling the opening of the second throat of a converter. When the converter starts blowing, the opening of the second throat of the converter is automatically controlled by using multiple variables such as the charging state, the change in the gas content of the converter top gas, the change in the light intensity of the converter mouth or the light intensity at the bottom edge of the furnace mouth, and the slag value measured by the blowing sonar. This reduces smoke and dust overflow during steelmaking, improves the gas recovery rate, and maintains production safety.

[0017] To achieve the above object, the present invention is implemented through the following technical solutions:

[0018] A method for automatically controlling the opening of the second blown converter throat is implemented based on a PLC / DCS system. The empirical value before the start of blowing is used as the initial value of the second blown converter throat opening. When the converter starts blowing, the following specific steps are included:

[0019] 1) When the converter is in the charging state, the opening of the converter throat is set to: increase the opening by one on the basis of the initial value, maintain the opening for the set time, and then return to the initial value;

[0020] 2) When the converter reaches the slag point during blowing, the sum of the CO and CO2 concentrations in the top gas is greater than the set value 1, or the CO2 concentration in the top gas is greater than the set value 2, the opening of the converter throat is set to: increase the opening by 2 from the initial value, maintain the opening for the set time 2, and then return to the initial value;

[0021] 3) When the converter reaches the slag point, the following steps are included:

[0022] Step S1: When the light intensity at the converter mouth is less than a set threshold value of one, the opening of the converter throat is set to increase by three on the basis of the initial value, and the opening is maintained until the light intensity at the converter mouth returns to the set threshold value of one, and then the opening is returned to the initial value;

[0023] Step S2: When the light intensity at the bottom edge of the converter mouth is greater than the set threshold value 2, the opening of the converter throat is set to increase by 4 on the basis of the initial value, and maintain the opening until the light intensity at the bottom edge of the converter mouth returns to the set threshold value 2, then returning to the initial value;

[0024] 4) When the converter reaches the slag point after blowing, and the sonar slag value falls into the return-drying area, the opening of the converter throat is set to: reduce the opening by 5% based on the initial value, and maintain it until the sonar slag value leaves the return-drying area, then return to the initial value;

[0025] 5) Before the converter auxiliary lance process test, if the sum of the carbon monoxide concentration and the carbon dioxide concentration in the top gas is detected to drop suddenly, and the sonar slag value falls into the splashing area, the opening of the converter second throat is set to increase by six on the basis of the initial value and maintain it until the sonar slag value leaves the splashing area, or until the slope of the sum of the carbon monoxide concentration and the carbon dioxide concentration in the top gas is greater than zero, then return to the initial value;

[0026] 6) When the temperature of the molten steel approaches the end point of smelting, the light intensity value at the furnace mouth becomes stronger, and the throat opening of the converter is restored to the initial value.

[0027] The slag value measured by converter sonar is the sound intensity value of fixed frequency sound.

[0028] The carbon monoxide concentration and carbon dioxide concentration of the top gas are detected by a flue gas analyzer, which is installed at the end of the rising section of the vaporization cooling flue of the converter waste heat boiler; the light intensity value of the converter furnace mouth or the intensity value of the lower edge of the converter furnace mouth is detected by a flame machine vision device, which is installed directly opposite the converter fire door; the sonar slag measurement value is detected by a flame machine vision device, which is installed at the side wall of the converter ear shaft facing the furnace mouth.

[0029] The flame machine vision device includes a camera, the flame machine vision device includes a sound sensor, the flue gas analyzer, the flame machine vision device, and the flame machine vision device are all connected to the PLC / DCS system.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The gas content of the furnace top gas, the light intensity of the converter mouth or the change of the light intensity at the bottom edge of the converter mouth, and the sonar slag value of the converter blowing are collected through the flue gas analyzer, flame machine vision device, and audio signal acquisition device. The collected data information is transmitted to the PLC / DCS system. When the converter is in the charging state, the opening of the converter throat and the gas recovery rate are automatically controlled during the converter blowing process to maintain production safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a structural diagram of a method for automatically controlling the throat opening of a converter.

[0033] Figure 2 is a test curve of the converter steelmaking blowing process.

[0034] Figure 3 is a schematic diagram of the control principle of the Erwen throat.

[0035] In the figure: 1- flame machine vision device 2- audio signal acquisition device 3- flue gas analyzer 4- converter waste heat boiler vaporization cooling flue. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0037] The following examples are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0038] [Example 1]

[0039] The main reasons for flue gas overflow during converter steelmaking and blowing are as follows:

[0040] 1. When the converter is in the charging state, dust will overflow;

[0041] 2. When molten steel splashes, smoke will overflow;

[0042] 3. When the carbon monoxide produced during blowing or the carbon dioxide in the top gas changes suddenly, the flue gas will overflow;

[0043] In response to the above three reasons, the flue gas analyzer, flame machine vision device, and audio signal acquisition device are used to collect data information on changes in the gas content of the furnace top gas, changes in the light intensity of the converter furnace mouth or the light intensity of the lower edge of the converter furnace mouth, and the converter sonar slag value (the converter sonar slag value is the sound intensity value of a fixed frequency sound), and the collected data information is transmitted to the PLC / DCS system. When the converter furnace is in the charging state, the opening of the converter second throat is automatically controlled during the converter blowing process. See Figure 1, a method for automatically controlling the opening of the converter second throat, the carbon monoxide concentration and the carbon dioxide concentration of the top gas are detected by the flue gas analyzer 3, and the flue gas analyzer 3 is arranged before the end of the ascending section of the vaporization cooling flue 4 of the converter waste heat boiler; when the molten steel splashes, the lower edge of the converter furnace mouth will produce strong light, and the light intensity value of the converter furnace mouth or the converter furnace The intensity value of the lower edge of the mouth is detected by a flame machine vision device, which is set 20 meters away from the converter fire door, based on the camera's ability to observe the flame at the converter mouth during steelmaking; the sonar slag value is detected by an audio signal acquisition device, which is set at the gap between the converter ear shaft side wall and the smoke hood; the flame machine vision device includes a camera, which is used to detect the furnace mouth area and the lower edge area of ​​the furnace mouth, detect changes in the light intensity of the furnace mouth and whether there is slag overflow at the lower edge of the furnace mouth, and the audio signal acquisition device includes a sound sensor and an audio transmitter. The sound sensor converts the collected signal into a 4-20mA signal through the audio transmitter. The sound sensor of the audio signal acquisition device is used to detect the sonar slag value. The flue gas analyzer, flame machine vision device, and audio signal acquisition device are all connected to the PLC / DCS system.

[0044] See Figure 2 and Figure 3. a represents the furnace mouth light intensity detection curve, b represents the sonar curve, c represents the sum of carbon monoxide and carbon dioxide, d represents the carbon dioxide curve, and e represents the carbon monoxide curve. Before starting blowing, the second wen throat opening is set to 65% based on manual experience. When starting blowing, the specific contents include:

[0045] 1) When the converter is in the charging state, the opening of the converter throat is set to: increase the opening by 5% on the basis of the initial value to 70%, maintain it for 20 seconds and then return to the initial value;

[0046] 2) When the converter reaches the slag point during blowing, the carbon monoxide concentration in the top gas is greater than the set value by 20% to 27%, or the carbon dioxide concentration in the top gas starts to decrease from an increasing value, the smoke starts to grow and has a tendency to splash. The opening of the converter throat is set to increase by 10% from the initial value of 65%, maintain the opening for 1 minute, and then return to the initial value.

[0047] 3) When the converter reaches the slag point, the following steps are included:

[0048] Step S1: When the light intensity value at the converter mouth is less than the set threshold value of 27, the smoke is too large and blocks the light. The opening of the converter throat is set to increase by 10% on the basis of the initial value of 65%, and maintain the opening until the light intensity value at the converter mouth returns to the set threshold value of 32, then return to the initial value.

[0049] Step S2: When the light intensity at the bottom edge of the converter mouth exceeds the set threshold of 50, slag overflows to the bottom edge of the furnace mouth, and the opening of the converter throat is set to increase by 10% on the basis of the initial value of 65%, and maintain the opening until the light intensity at the bottom edge of the converter mouth returns to the set threshold of 45, then return to the initial value;

[0050] 4) When the converter reaches the slag point after blowing, and the sonar slag value falls into the return-drying area, the flue gas generated at this time is reduced. The opening of the converter second throat is set to: reduce the opening by 10% based on the initial value of 65%, and maintain it until the sonar slag value leaves the return-drying area, then return to the initial value, in order to increase the gas recovery rate;

[0051] 5) Before the converter auxiliary lance process test, if the sum of the detected carbon monoxide concentration and carbon dioxide concentration suddenly drops and the sonar slag value falls into the splashing area, it means that molten steel splashing is about to occur. The opening of the converter secondary throat is set to increase by 10% on the basis of the initial value of 65% and maintain the opening until the slope of the sum of the carbon monoxide concentration and the carbon dioxide concentration is greater than zero or the sonar slag value leaves the splashing area, then return to the initial value;

[0052] 6) When the molten steel temperature is very high and close to the end of smelting, when the furnace mouth light intensity value becomes stronger to the set threshold value of 72, the converter throat opening is restored to the initial value of 65%.

[0053] The present invention collects data information on the gas content of furnace top gas, the light intensity at the converter mouth or the change in the light intensity at the bottom edge of the converter mouth, and the converter blowing sonar slag value through a flue gas analyzer, a flame machine vision device, and an audio signal acquisition device, and transmits the collected data information to a PLC / DCS system. When the converter is in a charging state, the opening of the converter throat is automatically controlled during the converter blowing process without manual intervention, thereby reducing smoke and dust overflow, improving the gas recovery rate, and maintaining production safety.

Claims

1. A method for automatically controlling the opening of the second throat of a converter, based on a PLC / DCS system, characterized in that: The empirical value before the start of blowing is used as the initial value of the converter throat opening value. When the converter starts blowing, the specific contents include: 1) When the converter is in the charging state, the opening of the converter throat is set to: increase the opening by one on the basis of the initial value, maintain the setting time for one, and then return to the initial value; 2) When the converter reaches the slag point, the sum of the carbon monoxide concentration and the carbon dioxide concentration of the top gas is greater than the set value 1, or the carbon dioxide concentration of the top gas is greater than the set value 2, the opening of the converter throat is set to: increase the opening by 2 on the basis of the initial value, maintain the opening for the set time 2, and then return to the initial value; 3) When the converter reaches the slag point, the following steps are included: Step S1, when the light intensity value at the converter mouth is less than the set threshold value 1, the opening of the second converter throat is set to: increase the opening by 3 on the basis of the initial value, and maintain it until the light intensity value at the converter mouth returns to the set threshold value 1, then return to the initial value; Step S2, when the light intensity value at the bottom edge of the converter mouth is greater than the set threshold value 2, the opening of the second converter throat is set to: increase the opening by 4 on the basis of the initial value, and maintain it until the light intensity value at the bottom edge of the converter mouth returns to the set threshold value 2, then return to the initial value; 4) When the converter reaches the slag point after blowing, and the sonar slag value falls into the return-drying area, the opening of the converter throat is set to: reduce the opening by 5 on the basis of the initial value, and maintain it until the sonar slag value leaves the return-drying area and then return to the initial value; 5) Before the converter auxiliary gun process test, if it is detected that the sum of the carbon monoxide concentration and the carbon dioxide concentration of the furnace top gas suddenly drops, and the sonar slag value falls in the splashing area, the opening of the converter second throat is set to: increase the opening by six on the basis of the initial value, and maintain it until the sonar slag value leaves the splashing area, or maintain it until the slope of the sum of the carbon monoxide concentration and the carbon dioxide concentration of the furnace top gas is greater than zero, then return to the initial value; 6) When the temperature of molten steel approaches the end point of smelting, the light intensity value at the furnace mouth becomes stronger, and the throat opening of the converter is restored to the initial value.

2. The method for automatically controlling the opening of the converter throat according to claim 1, characterized in that: The converter sonar slag measurement value is the sound intensity value of a fixed frequency sound.

3. The method for automatically controlling the opening of the converter throat according to claim 1, characterized in that: The carbon monoxide concentration and the carbon dioxide concentration of the top gas are detected by a flue gas analyzer, which is arranged at the end of the rising section of the vaporization cooling flue of the converter waste heat boiler; the light intensity value of the converter furnace mouth or the strong light value of the lower edge of the converter furnace mouth is detected by a flame machine vision device, which is arranged opposite to the converter fire-blocking door; the sonar slag measurement value is detected by a flame machine vision device, which is arranged at the side wall of the converter ear shaft facing the furnace mouth.

4. The method for automatically controlling the opening of the converter throat according to claim 3, characterized in that: The flame machine vision device includes a camera, the flame machine vision device includes a sound sensor, the flue gas analyzer, the flame machine vision device, and the flame machine vision device are all connected to the PLC / DCS system.

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