CN-116445709-B - Method for controlling continuous annealing and oxidation color defect of strip steel

Abstract

The invention discloses a control method for a strip steel continuous annealing oxidation color defect, which relates to the technical field of strip steel heat treatment, the strip steel continuous annealing oxidation color defect control method comprises a set of online oxygen content detection device, a set of online dew point detection device, a set of online oxidation color detector and a set of fan power control system. The strip steel continuous annealing oxidation color defect control method is characterized in that an online dew point detection device is used for detecting dew points of air channels of a slow cooling section, a fast cooling section, an aging section and a final cooling section, and an online oxidation color detector is used for detecting the oxidation color condition of the strip steel surface in real time. Finally, the fan power feedback control system carries out feedback control on the fan power through the detection result, so that the on-line control of the strip steel oxidation color is realized, the oxidation color defect can be automatically controlled, the abnormality is automatically alarmed, the leakage point investigation time can be shortened, the occurrence amount of the oxidation color can be effectively controlled, and the automation level of the unit is greatly improved.

Inventors

• Wan Zhaotang
• ZHANG LIYANG

Assignees

• 宝钢湛江钢铁有限公司

Dates

Publication Date

20260505

Application Date

20230329

Claims (9)

1. 1. The control method for the continuous annealing and oxidation color defect of the strip steel is characterized by comprising a set of online oxygen content detection device, a set of online dew point detection device, a set of online oxidation color detector and a set of fan power control system, and comprises the following operation steps: s1, oxygen content and dew point detection: The online oxygen content detection device and the online dew point detection device are used for online real-time circulating detection of ppm-level oxygen content and dew point of each air duct of the slow cooling section, the fast cooling section, the aging section and the final cooling section, and oxygen content detection points and dew point detection points are arranged on the air duct at the air outlet side of the fan and are fed back to the fan power control system; s2, detecting an oxidation color defect: The online oxidation color detector is arranged near the unit outlet quality inspection table and is provided with a stable strong light illumination system, the gray scale of the upper surface and the lower surface of the strip steel is detected by utilizing a high-speed camera, the gray scale value is used for representing the oxidation color defect degree of the surface of the strip steel, the fan power control system also selects a fan with the smallest difference value according to the gray scale value of the upper surface and the lower surface of the strip steel detected by the online oxidation color detector and the difference value of each fan oxygen content, the preset limit value of the dew point and the preset limit value of the dew point, carries out fixed-point detection on the air flue with the fan with the smallest difference value and carries out limit feedback control on the fan power of the area with the fan with the smallest difference value, and when the difference value of the oxygen content or the dew point and the preset limit value of the oxygen content is not the smallest, the fan with the smallest difference value is automatically replaced to carry out fixed-point detection on the air flue with the new fan with the smallest difference value and carries out limit feedback control on the fan power of the area with the fan with the smallest difference value until the oxidation color value meets the release standard; S3, fan power automatic limitation: setting an oxygen content measuring instrument and a dew point measuring instrument in air channels of the slow cooling section, the fast cooling section, the aging section and the final cooling section, and automatically limiting the maximum power of fans of the slow cooling section, the fast cooling section, the aging section and the final cooling section by a table lookup method according to the oxygen content and the dew point measuring result and comparing the oxygen content with a dew point limiting value; s4, setting an oxygen content and dew point correspondence table: setting a table corresponding to the limiting color difference gray value and the oxygen content and the dew point, and maintaining the table corresponding to the limiting color difference gray value, the oxygen content and the dew point limit value of each steel grade into an online oxidation color meter computer database system.
2. 2. The method for controlling the continuous annealing and oxidation defect of the strip steel is characterized in that in the step S1, an oxygen content limiting value and a dew point limiting value are preset for each fan by a fan power control system, the oxygen content detected in real time and the dew point are compared with the oxygen content preset limiting value and the dew point preset limiting value, fan power limiting feedback control is carried out, namely, when the oxygen content detected in real time and the dew point exceed the respective limiting values, the circulation detection is automatically changed into fixed-point detection of an air duct where a detection point with the overrun limiting value is located, the fan rotating speed corresponding to the air duct where the detection point is located is automatically reduced until the detection result is qualified, and then the circulation detection and judgment are continued.
3. 3. The method for controlling the continuous annealing and oxidation defect of the strip steel according to claim 2, wherein when the rotating speed of the fans corresponding to the air duct where the detection point is located is automatically reduced, if the fans are symmetrically arranged, the two fans need to be synchronously reduced in speed, and the pressure balance is maintained.
4. 4. The method for controlling the continuous annealing and oxidation defect of strip steel according to claim 1, wherein in the step S3, oxygen content and dew point limiting values are distinguished according to steel types, and maximum powers of fans of a slow cooling section, a fast cooling section, an aging section and a final cooling section are limited according to respective comparison tables of the steel types.
5. 5. The method for controlling the continuous annealing and oxidation defect of the strip steel according to claim 1, wherein in the step S3, a gray level value table of the limit color difference of each steel grade is preset, and the maximum power of fans of the slow cooling section, the fast cooling section, the aging section and the final cooling section of the steel grade is distinguished by using the gray level detection result of the online oxidation color meter through a table look-up method.
6. 6. The method for controlling the oxidation defect of continuous annealing of strip steel according to claim 1, wherein in the step S4, the limit color difference gray scale value of automatic comparison of new steel grades appears later and the oxygen content and the dew point limit value of the steel grades are updated.
7. 7. The method for controlling the continuous annealing and oxidation defect of strip steel according to claim 1, wherein the shafts of the fans of the slow cooling section and the fast cooling section are sealed by high-pressure nitrogen with the pressure of more than or equal to 3kg besides carbon sealing.
8. 8. The method for controlling the continuous annealing and oxidation defect of the strip steel according to claim 1, wherein the conical flow guide ports behind all the fan heat exchangers are of a double-layer sealing structure and are sealed by high-pressure nitrogen with the pressure of more than or equal to 3 kg.
9. 9. The method for controlling the continuous annealing and oxidation defect of strip steel according to claim 1, wherein dew points in hearths of the slow cooling section, the fast cooling section, the ageing section and the final cooling section are controlled below-40 ℃.

Description

Method for controlling continuous annealing and oxidation color defect of strip steel Technical Field The invention relates to the technical field of strip steel heat treatment, in particular to a strip steel continuous annealing oxidation color defect control method. Background In the cold rolling continuous annealing process, the annealing oxidation color is always quite outstanding, especially for ultra-high strength steel, because the high strength steel contains a large amount of reinforced alloy elements such as Si, mn and the like, the alloy elements are diffused and enriched on the surface of the steel plate and oxidized during annealing, so that the oxidation color is faster than that of ordinary carbon steel, the method for controlling the oxidation color mainly comprises the steps of reducing the oxygen content of a hearth, the dew point and improving the hydrogen content, and the method for improving the hydrogen content can reduce the oxidized strip steel to a certain extent, but the method is mainly suitable for a high-temperature section, has poor improvement effect on a low-temperature section and can increase the energy consumption of hydrogen, so that the reduction of the dew point and the oxygen content in a furnace, particularly the reduction of the oxygen content in air channels of each section of a slow cooling section, a fast cooling section, an aging section and a final cooling section, and the dew point are the main means for controlling the oxidation color at present. The patent with publication number CN105648178B discloses a control method for the oxidation color of the dual-phase steel in the cold rolling continuous annealing process, which mainly controls the oxidation color of the dual-phase steel by reducing the temperature of a heating section and a final cooling section, limiting the power of a cooling fan of a rapid cooling section to be within 80 percent, controlling the pH value and the conductivity of a water quenching tank and improving the hydrogen content of a furnace section. The method for controlling the oxidation color of the dual-phase steel based on the cold rolling continuous annealing process has the following defects: In the aspect of fan power, the method only enables the power of a cooling fan of a fast cooling section to be mechanically within 80%, on one hand, the oxygen content and the dew point under the power of the fan of 80% cannot be quantified to ensure the normal surface of strip steel, on the other hand, the oxidation color defect cannot be automatically controlled according to the continuous deterioration of the state of the fan, and if air leakage and water leakage of other sections of fans also cannot be timely found, the oxidation color cannot be timely controlled, and an operator cannot be timely reminded of paying attention to the abnormality of the fan at the position. Accordingly, in view of the above, a method for controlling the oxidation defect of continuous annealing of a strip steel has been proposed by researching and improving the conventional structure and defects. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a method for controlling the continuous annealing and oxidation defects of strip steel, which solves the problems in the prior art. The continuous annealing and oxidation color defect control method for the strip steel comprises a set of online oxygen content detection device, a set of online dew point detection device, a set of online oxidation color detector and a set of fan power control system, and the control method comprises the following operation steps: s1, oxygen content and dew point detection: The online oxygen content detection device and the online dew point detection device are used for online real-time circulating detection of ppm-level oxygen content and dew point of each air duct of the slow cooling section, the fast cooling section, the aging section and the final cooling section, and oxygen content detection points and dew point detection points are arranged on the air duct at the air outlet side of the fan and are fed back to the fan power control system; s2, detecting an oxidation color defect: The online oxidation color detector is arranged near the unit outlet quality inspection table and is used for quantitatively detecting the oxidation color defect condition of the upper surface and the lower surface of the strip steel, the online oxidation color detector is provided with a stable strong light illumination system, the gray scale value is used for representing the oxidation color defect degree of the upper surface and the lower surface of the strip steel, the fan power control system also selects a fan with the smallest difference value according to the gray scale value of the upper surface and the lower surface of the strip steel detected by the online oxidation color detector and the difference value of each fan oxygen content, the preset limit value of the