A method for detecting and operating particulate matter in a cold rolling annealing furnace

Abstract

The invention discloses a method for detecting and operating particulate matter in a cold rolling annealing furnace. The annealing furnace is preceded by a cleaning section. When the annealing furnace is in production, an online particulate matter detector is arranged at the top of the slow cooling section area to detect the particulate matter content in the annealing furnace in real time. When the particulate matter content in the furnace is within a normal range, the furnace top relief valve is automatically controlled and adjusted according to the furnace pressure. When the particulate matter content in the furnace exceeds the normal range, the relief valve opening at the top of the slow cooling section is increased, the brush roller pressure of the cleaning section is increased, the electrolytic cleaning current of the cleaning section is increased, the conductivity of the cleaning section is controlled to increase the reflectivity of the strip steel, and the production plan is timely changed from high-strength steel to ordinary carbon steel production. The invention can be applied to timely detect the particulate matter content in the furnace under normal production conditions, analyze the relationship between various strip steel production particulates in the furnace, adjust the production plan in time, reasonably control the annealing furnace gas release, improve the cleaning effect of the cleaning section and the operation quality of the annealing furnace, extend the maintenance cycle, and further improve product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of cold rolling, and in particular relates to a method for detecting and operating particulate matter in a cold rolling annealing furnace. Background Art

[0002] Annealing furnace is an important equipment used in cold rolling production line of strip steel. Annealing furnace of cold rolling processing line usually adopts a large number of radiation tubes for heating. Nitrogen and hydrogen mixed gas is injected into the furnace to reduce the strip steel and prevent oxidation. A cleaning section is usually set in front of the annealing furnace. The cleaning section usually adopts hot alkali washing, electrolytic cleaning and hot rinsing to clean the strip steel. Under normal circumstances, in the process of producing alloy steel, some alloy elements will precipitate and impurities such as iron powder will remain after the strip steel is cleaned in the cleaning section. Particulate matter will be produced in the furnace. When the particulate matter reaches a certain amount, it will affect the surface quality of the strip steel. The surface of the produced strip steel is prone to defects such as indentation and pitting. Over time, it will cause furnace roller nodules. Usually, the furnace roller nodules are most serious in the area from the soaking section to the slow cooling section, which further affects the surface quality of the strip steel. At present, the grinding roller method is usually used to solve the above problems to maintain short-term production. After a long time, when the furnace roller nodules are aggravated, the furnace can only be opened for maintenance and replacement of furnace rollers to achieve normal production, which is time-consuming, labor-intensive and greatly increases the operation and maintenance costs. How to timely and effectively monitor the degree of particulate matter in the furnace atmosphere during production is of positive significance for effectively guiding production planning and scheduling and reasonably controlling the emission of furnace atmosphere. Summary of the invention

[0003] In view of the defects existing in the background technology, the present invention provides a method for detecting and operating particulate matter in a cold rolling annealing furnace. The present invention can be used to timely detect the content of particulate matter in the annealing furnace under normal production conditions of the annealing furnace, analyze the relationship between various strip steel production particulate matter in the furnace, adjust the production plan in time, reasonably control the gas emission of the annealing furnace, improve the cleaning effect of the cleaning section and the operation quality of the annealing furnace, extend the maintenance cycle, and further improve product quality.

[0004] The technical solution of the present invention is as follows:

[0005] The invention discloses a method for detecting and operating particulate matter in a cold rolling annealing furnace, which is suitable for strip steel production. A cleaning section is provided in front of the annealing furnace. When the annealing furnace is in production, an online particulate matter detector is arranged at the top of the slow cooling section area to detect the particulate matter content of the atmosphere in the annealing furnace in real time. When the particulate matter content in the furnace is within a normal range, the relief valve on the top of the furnace is automatically controlled and adjusted according to the furnace pressure, which is suitable for the production of high-strength steel. When the particulate matter content in the furnace exceeds the normal range, the opening of the relief valve on the top of the slow cooling section is increased, the pressing amount of the brush roller in the cleaning section in front of the annealing furnace is increased, the electrolytic cleaning current of the cleaning section is increased, the conductivity of the cleaning section is controlled to improve the reflectivity of the strip steel, and the production plan is promptly changed from high-strength steel to ordinary carbon steel production, and the particulate matter content in the furnace is monitored in real time. When the particulate matter content in the furnace drops to the normal range and remains stable, it is changed to high-strength steel production.

[0006] As a further improvement of the technical solution, the particle online detector adopts the laser backscattering principle to measure the particle in the furnace.

[0007] As a further improvement of the technical solution, the normal range of the particulate matter content in the furnace is less than 5 mg / m 3 .

[0008] As a further improvement of the technical solution, the particulate matter content in the furnace exceeds the normal range when the particulate matter content in the furnace is greater than 5 mg / m 3 When the temperature is high, increase the opening of the top vent valve in the slow cooling section to 50%-90%, increase the brush roller pressure current in the cleaning section by 5%, increase the brush roller pressure, increase the electrolytic cleaning current in the cleaning section by 10%, control the conductivity of the cleaning section to increase by 20ms, and increase the reflectivity of the strip to more than 90%.

[0009] Furthermore, the heating of the annealing furnace is controlled by radiant tube heating.

[0010] Compared with the prior art, the particle detection and operation method in the cold rolling annealing furnace described in the present invention is to set an online particle detector on the top of the slow cooling section of the annealing furnace, use the laser backscattering principle to monitor the particle content of the furnace atmosphere in real time, and determine the nodule condition of the furnace roller; when the particle content in the furnace atmosphere exceeds the normal range, timely adjust the release amount by the furnace top release valve opening, increase the brush roller pressure by increasing the brush roller pressure working current of the cleaning section, improve the cleaning ability by increasing the electrolytic cleaning current, the conductivity of the cleaning section, and the reflectivity of the strip, and when the particle content exceeds the normal range, timely adjust the production plan, switch from high-strength steel to ordinary carbon steel production, and switch to high-strength steel production after the particle content returns to the normal range and stabilizes. This method can effectively monitor the particle content in the furnace and take effective measures to control the formation of particles, improve product quality, and has positive significance for extending the maintenance cycle of the annealing furnace. DETAILED DESCRIPTION

[0011] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "upper", "lower", "left", "right", "front", "back", "inside", "outside", etc. used in the patent application specification and claims of the present disclosure are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly; "connected" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0013] The present invention discloses a method for detecting and operating particulate matter in a cold rolling annealing furnace, which is suitable for strip steel production. The annealing furnace is a vertical continuous annealing furnace, which is composed of a preheating section, a soaking section, a heating section, a slow cooling section, a fast cooling section, an aging section, and a final cooling section. The heating is controlled by radiant tube heating. There is a cleaning section in front of the furnace, and the cleaning section is composed of hot alkali washing, three-stage electrolytic cleaning, and hot rinsing. When the annealing furnace is used to produce products with high alloy content, during the process of heating and soaking, due to the reducing atmosphere in the furnace, the reducing property is strong in this area, and some alloys will precipitate. In addition, impurities such as iron powder may remain after the strip steel is cleaned in the cleaning section, resulting in an increase in particulate matter. Usually, the furnace roller nodules are most serious in the area from the soaking section to the slow cooling section.

[0014] The method of the present invention is to set a particle online detector at the top of the slow cooling section of the annealing furnace to detect the particle content of the atmosphere in the annealing furnace in real time under the normal production state of the production line; the particle online detector adopts the laser backscattering principle to measure the particle content in the furnace, which has the advantage of realizing real-time online detection of the particle content in the atmosphere of the annealing furnace under the working state of the annealing furnace, and determining the production status of the annealing furnace and the nodulation status of the furnace roller. Under normal circumstances, the particle content in the furnace is less than 5mg / m 3 It is in the normal range. At this time, the furnace top relief valve is automatically controlled and adjusted according to the furnace pressure. It is suitable for the production of high-strength steel and phosphating steel. When the particulate matter content in the furnace is greater than 5mg / m 3When the temperature is too high, it is abnormal. At this time, increase the opening of the top vent valve of the slow cooling section, increase the brush roller pressure in the cleaning section before the annealing furnace, increase the electrolytic cleaning current in the cleaning section, control the conductivity of the cleaning section to improve the reflectivity of the strip steel, and promptly switch the production plan from high-strength steel to ordinary carbon steel production, and monitor the particulate matter content in the furnace in real time. When the particulate matter content in the furnace drops to the normal range and remains stable, switch to high-strength steel production. Under normal circumstances, when the particulate matter content in the furnace is greater than 5mg / m 3 When the temperature is high, increase the opening of the top vent valve in the slow cooling section to 50%-90%, increase the brush roller pressure current in the cleaning section by 5%, increase the brush roller pressure, increase the electrolytic cleaning current in the cleaning section by 10%, control the conductivity of the cleaning section to increase by 20ms, and increase the reflectivity of the strip to more than 90%.

[0015] Taking the batch production of high-strength steel DP800 as an example, the particle content in the furnace is monitored by an online particle detector, and the normal value is <5mg / m 3 ; The furnace top relief valve is in automatic control and adjustment according to the furnace pressure;

[0016] When the particle content in the furnace is greater than 5 mg / m 3 When the cooling time is about 2 hours, manually open the top relief valve of the slow cooling section by 75%;

[0017] Increase the brush roller pressure working current in the cleaning section from 70% to 75% to increase the brush roller pressure;

[0018] Increase electrolytic cleaning current from 4900A to 5390A;

[0019] Improve the conductivity of the cleaning section by 20ms, the reflectivity of the strip steel is > 90%, and the cleaning effect of the cleaning section is improved.

[0020] At the same time, track the content of particulate matter in the furnace and arrange the production of high-strength steel when it shows a downward trend;

[0021] When the particle content continues to rise, the production plan is adjusted in time from high-strength steel to ordinary carbon steel production, and the relief valve is kept in the state until the particle content decreases and stabilizes, and then the high-strength steel production is arranged;

[0022] Through the above adjustments, the content of particulate matter in the furnace can be effectively controlled, the particulate matter in the furnace can be reduced, the furnace condition can be stabilized, the long-term management of the annealing furnace can be achieved, the nodules of the furnace rollers can be effectively controlled, and the product quality can be guaranteed.

Claims

1. A method for detecting and operating particulate matter in a cold rolling annealing furnace, suitable for strip steel production, wherein the annealing furnace is preceded by a cleaning section, characterized in that: When the annealing furnace is in production, an online particle detector is arranged at the top of the slow cooling section area to detect the particle content of the atmosphere in the annealing furnace in real time; when the particle content in the furnace is within the normal range, the furnace top relief valve is automatically controlled and adjusted according to the furnace pressure, which is suitable for the production of high-strength steel; when the particle content in the furnace exceeds the normal range, the opening of the relief valve at the top of the slow cooling section is increased, the brush roller pressure in the front cleaning section of the annealing furnace is increased, the electrolytic cleaning current in the cleaning section is increased, the conductivity of the cleaning section is controlled to improve the reflectivity of the strip steel, and the production plan is promptly changed from high-strength steel to ordinary carbon steel production, and the particle content in the furnace is monitored in real time. When the particle content in the furnace drops to the normal range and remains stable, it is switched to high-strength steel production; The particle online detector uses the laser backscattering principle to measure the particles in the furnace; The normal range of particulate matter content in the furnace is less than 5 mg / m³.

2. A method for detecting and operating particulate matter in a cold rolling annealing furnace according to claim 1, characterized in that: When the particulate matter content in the furnace exceeds the normal range, that is, when the particulate matter content in the furnace is greater than 5 mg / m³, the opening of the top vent valve of the slow cooling section is increased to 50%-90%, the brush roller pressure current of the cleaning section is increased by 5%, the brush roller pressure is increased, the electrolytic cleaning current of the cleaning section is increased by 10%, the conductivity of the cleaning section is controlled to increase by 20ms, and the reflectivity of the strip is increased to greater than 90%.

3. A method for detecting and operating particulate matter in a cold rolling annealing furnace according to claim 1, characterized in that: The annealing furnace heating is controlled by radiant tube heating.