阅读说明：本技术 一种连续退火炉炉膛气氛波动加压置换方法 (Furnace chamber atmosphere fluctuation pressurization replacement method for continuous annealing furnace ) 是由 王智增 李耀强 周恒龙 王志磊 郑璐 江高 张�成 于 2019-08-30 设计创作，主要内容包括：本发明涉及一种连续退火炉炉膛气氛波动加压置换方法,属于冶金行业冷轧薄板连续退火生产技术领域。技术方案是：①使炉膛内部气氛压力和保温棉内气氛压力均在200~300Pa状态下进行炉膛内部气氛置换；②当炉膛内部气氛的氧气含量m1降至7000~8000ppm时,炉膛内部气氛压力提高至600~800Pa,③直到炉膛内部气氛和保温棉内部气氛压力差小于10Pa,④逐步减少氮气注入量,直至炉膛内部气氛的氧气含量小于200ppm时,即完成连续退火炉炉膛气氛波动加压置换。本发明的有益效果是：通过炉膛气氛压力与保温棉气氛内部压力的波动压力差,加速置换保温棉内部氧气,从而可以有效的缩短炉膛氮气置换时间,减少氮气消耗量。(The invention relates to a furnace hearth atmosphere fluctuation pressurization replacement method of a continuous annealing furnace, belonging to the technical field of cold-rolled sheet continuous annealing production in the metallurgical industry, which adopts the technical scheme that the furnace hearth atmosphere pressure and the heat-preservation cotton atmosphere pressure are both replaced in the state of 200 ~ 300Pa, when the oxygen content m1 of the furnace hearth atmosphere is reduced to 7000 ~ 8000ppm, the furnace hearth atmosphere pressure is increased to 600 ~ 800Pa, until the pressure difference between the furnace hearth atmosphere and the heat-preservation cotton atmosphere is less than 10Pa, the nitrogen injection amount is gradually reduced until the oxygen content of the furnace hearth atmosphere is less than 200ppm, the continuous furnace hearth atmosphere fluctuation pressurization replacement is completed.)

1. A furnace hearth atmosphere fluctuation pressurization replacement method of a continuous annealing furnace is characterized in that heat insulation cotton (2) and a stainless steel lining plate (3) are arranged on the inner wall of the continuous annealing furnace (1) and used for heat insulation and heat insulation of a furnace hearth; the continuous annealing furnace (1) is provided with a nitrogen replacement pipeline (4), and a nitrogen flow regulating valve (6) is arranged on the nitrogen replacement pipeline (4) and used for regulating the flow of the purging nitrogen; furnace roof diffuse governing valve (7) are installed on furnace roof diffuse pipeline (5), are used for adjusting nitrogen gas replacement and sweep the aperture, its characterized in that: the continuous annealing furnace hearth atmosphere fluctuation pressurization replacement method comprises the following steps:

firstly, after the annealing furnace is sealed, adjusting the nitrogen injection amount and the opening degree of a furnace top diffusion adjusting valve (7) through a nitrogen flow adjusting valve (6), so that the internal atmosphere pressure of the hearth and the internal atmosphere pressure of the heat-preservation cotton are replaced under the condition of 200 ~ 300 Pa;

when the oxygen content of the atmosphere in the hearth is reduced to 7000 ~ 8000ppm, the nitrogen injection amount is gradually increased, and the opening degree of a furnace top diffusion regulating valve (7) is gradually reduced until the atmosphere pressure in the hearth is increased to 600 ~ 800Pa and the atmosphere pressure in the heat-preservation cotton is increased to 450 ~ 550 Pa;

keeping the nitrogen injection amount and the opening degree of the furnace top diffusion regulating valve (7) in the step II, continuously performing atmosphere replacement inside the hearth until the pressure difference between the atmosphere inside the hearth and the atmosphere inside the heat preservation cotton is less than 10Pa, and continuously performing atmosphere replacement inside the hearth for 10 ~ 15min under the state;

gradually reducing the nitrogen injection amount, and simultaneously gradually increasing the opening degree of a furnace top diffusion regulating valve (7) until the internal atmosphere pressure of the hearth is reduced to 320 ~ Pa and the internal atmosphere pressure of the heat-preservation cotton is 450 ~ Pa;

keeping the nitrogen injection amount and the opening degree of the furnace top diffusion regulating valve (7) in the step IV, continuously replacing the atmosphere in the hearth until the pressure difference between the atmosphere in the hearth and the atmosphere in the heat preservation cotton is less than 10Pa, and continuously replacing the atmosphere in the hearth for 3 ~ 5min under the state;

sixthly, repeating the step III to the step V, and starting to ignite and heat the continuous annealing furnace when the oxygen content of the atmosphere in the hearth is reduced to 300 ~ 500 ppm;

and seventhly, in the ignition temperature rise process of the continuous annealing furnace, repeating the step III-the step V at the same time, and finishing the fluctuation pressurization replacement of the furnace chamber atmosphere of the continuous annealing furnace when the oxygen content of the furnace chamber atmosphere is less than 200 ppm.

2. The method for replacing furnace hearth atmosphere of continuous annealing furnace by fluctuating pressurization according to claim 1, characterized in that the nitrogen injection amount in the step (r) is 4000 ~ 5000Nm and 5000Nm³/HThe opening degree of the furnace top diffusion regulating valve (7) is 50 percent;

the injection amount of the nitrogen in the step (II) is 4000 ~ 5000Nm and 5000Nm³Step-wise increase in/H to 5500 ~ 6500Nm³H, the opening degree of the furnace top diffusion regulating valve (7) is gradually reduced to 10 percent from 50 percent;

the injection amount of nitrogen in the step (c) is 5500 ~ 6500Nm³H, the opening degree of the furnace top diffusion regulating valve (7) is 10 percent;

the injection amount of the nitrogen in the step (iv) is from 5500 ~ 6500Nm³Stepwise reduction of/H to 2800 ~ 3500 Nm³H, the opening degree of the furnace top diffusion regulating valve (7) is gradually increased from 10% to 50%;

the injection amount of nitrogen in the step (v) is 2800 ~ 3500 Nm³And H, the opening degree of the furnace top diffusion regulating valve (7) is 50 percent.

Technical Field

The invention relates to a furnace atmosphere fluctuation pressurization replacement method for a continuous annealing furnace, belonging to the technical field of continuous annealing production of cold-rolled sheets in the metallurgical industry.

Background

The continuous annealing line is a production unit mainly used for producing cold-rolled sheets, wherein the continuous annealing line is key equipment for carrying out annealing process treatment on the cold-rolled sheets. The continuous annealing furnace adopts a full radiant tube for heating, the atmosphere in the furnace is protective gas mainly containing nitrogen, and the protective gas is used for isolating air, so that the furnace is always kept in an oxygen-free reducing atmosphere, and the condition that the plate strip is oxidized in the continuous annealing furnace is ensured.

The inner wall of the annealing furnace adopts heat insulation cotton and a stainless steel lining board as refractory materials to isolate heat. In the production process of the cold-rolled sheet, blow-in operation is required due to production accidents such as strip steel breakage in a furnace, furnace roller nodulation and the like or maintenance of equipment in the furnace. In the blow-in operation, the annealing furnace needs to be cooled, and then the supply of nitrogen and hydrogen is stopped. After air enters the hearth to replace residual nitrogen, the maintainers can enter the annealing furnace to treat accidents. When the furnace is opened and normal production is resumed again, atmosphere replacement operation needs to be carried out on the hearth of the continuous annealing furnace firstly, namely, air with oxidability in the hearth is replaced by inert gas nitrogen, so that equipment or product damage caused by oxidation reaction of equipment or strip steel in the temperature rising stage is avoided. The atmosphere replacement work of the annealing furnace is an important part in the recovery process.

At present, the method for replacing the atmosphere of the hearth of the annealing furnace is to inject a large amount of nitrogen into the hearth, open a diffusion valve at the same time, and perform atmosphere replacement work through long-time gas flowing and diffusion. Because the inside of the continuous annealing furnace is a closed space, nitrogen in the furnace is replaced by injecting the nitrogen into the furnace through a furnace bottom injection pipeline and then discharging the nitrogen from an automatic bleeding valve at the top of the furnace. And the oxygen in the hearth is reduced to the required oxygen content value through continuous blowing and dilution of nitrogen in the furnace. Because the annealing furnace is internally provided with a large amount of heat preservation cotton, after the continuous annealing furnace is opened for a long time, a large amount of air enters the heat preservation cotton through diffusion, and only oxygen in a hearth outside the heat preservation cotton can be blown away in the nitrogen replacement process of the hearth. And the oxygen in the heat preservation cotton needs to be diluted and replaced after gas molecules gradually diffuse to the hearth by the self diffusion motion. In the whole nitrogen purging process of the hearth, air adsorbed in the heat-insulating cotton cannot be rapidly purged and eliminated due to the refractory lining plate and the heat-insulating cotton and can only be reduced through gas diffusion, so that the purging time of the hearth is too long, the energy consumption medium is too much, the production time needs to be recovered, and the production rhythm and the production yield are seriously influenced.

Disclosure of Invention

The invention aims to provide a furnace atmosphere fluctuation pressurization replacement method for a continuous annealing furnace, which can quickly eliminate air adsorbed into heat-preservation cotton, thereby reducing the furnace purging time and the furnace purging nitrogen consumption and solving the problems in the background technology.

The technical scheme of the invention is as follows:

a continuous annealing furnace hearth atmosphere fluctuation pressurization replacement method is characterized in that heat preservation cotton and a stainless steel lining plate are arranged on the inner wall of a continuous annealing furnace and used for heat preservation and heat insulation of a hearth; the continuous annealing furnace is provided with a nitrogen displacement pipeline, and a nitrogen flow regulating valve is arranged on the nitrogen displacement pipeline and used for regulating the flow of the blowing nitrogen; the furnace top diffusion regulating valve is arranged on a furnace top diffusion pipeline and used for regulating the nitrogen replacement purging opening, and the furnace hearth atmosphere fluctuation pressurization replacement method of the continuous annealing furnace comprises the following steps:

firstly, after the annealing furnace is sealed, regulating the nitrogen injection amount and the opening degree of a furnace top diffusion regulating valve through a nitrogen flow regulating valve, so that the internal atmosphere pressure of the hearth and the internal atmosphere pressure of the heat preservation cotton are subjected to internal atmosphere replacement in the hearth under the condition of 200 ~ 300 Pa;

when the oxygen content of the atmosphere in the hearth is reduced to 7000 ~ 8000ppm, gradually increasing the nitrogen injection amount, and gradually reducing the opening of a furnace top diffusion regulating valve until the atmosphere pressure in the hearth is increased to 600 ~ 800Pa, and the atmosphere pressure in the heat-preservation cotton is increased to 450 ~ 550 Pa;

keeping the nitrogen injection amount and the opening degree of a furnace top diffusion regulating valve in the step, continuously performing atmosphere replacement inside the hearth until the pressure difference between the atmosphere inside the hearth and the atmosphere inside the heat preservation cotton is less than 10Pa, and continuously performing atmosphere replacement inside the hearth for 10 ~ 15min in the state;

gradually reducing the nitrogen injection amount, and simultaneously gradually increasing the opening of the furnace top diffusion regulating valve until the internal atmosphere pressure of the hearth is reduced to 320 ~ Pa and the internal atmosphere pressure of the heat-preservation cotton is 450 ~ Pa;

keeping the nitrogen injection amount and the opening degree of the furnace top diffusion regulating valve in the step IV, continuously replacing the atmosphere in the hearth until the pressure difference between the atmosphere in the hearth and the atmosphere in the heat preservation cotton is less than 10Pa, and continuously replacing the atmosphere in the hearth for 3 ~ 5min in the state;

sixthly, repeating the step III to the step V, and starting to ignite and heat the continuous annealing furnace when the oxygen content of the atmosphere in the hearth is reduced to 300 ~ 500 ppm;

and seventhly, in the ignition temperature rise process of the continuous annealing furnace, repeating the step III-the step V at the same time, and finishing the fluctuation pressurization replacement of the furnace chamber atmosphere of the continuous annealing furnace when the oxygen content of the furnace chamber atmosphere is less than 200 ppm.

The nitrogen injection amount in the step (i) is 4000 ~ 5000Nm and 5000Nm³H, the opening degree of the furnace top diffusion regulating valve is 50 percent;

the injection amount of the nitrogen in the step (II) is 4000 ~ 5000Nm and 5000Nm³Step-wise increase in/H to 5500 ~ 6500Nm³H, gradually reducing the opening degree of the furnace top diffusion regulating valve from 50% to 10%;

the injection amount of nitrogen in the step (c) is 5500 ~ 6500Nm³H, the opening degree of the furnace top diffusion regulating valve is 10 percent;

in the step (iv)The nitrogen injection amount is from 5500 ~ 6500Nm³Stepwise reduction of/H to 2800 ~ 3500 Nm³H, gradually increasing the opening of the furnace top diffusion regulating valve from 10% to 50%;

the injection amount of nitrogen in the step (v) is 2800 ~ 3500 Nm³And H, the opening degree of the furnace top diffusion regulating valve is 50 percent.

The method mainly comprises the steps of adjusting the injection amount of nitrogen of the annealing furnace and the opening degree of a furnace top bleeding valve to enable the pressure difference between the internal atmosphere pressure of the hearth and the internal atmosphere pressure of the heat-preservation cotton to exist, increasing the diffusion efficiency of oxygen and nitrogen in the annealing hearth through high pressure difference, enabling the oxygen in the heat-preservation cotton to be rapidly diffused into the hearth, and rapidly discharging the atmosphere containing oxygen out of the hearth through the furnace top bleeding valve through high pressure difference airflow, thereby shortening the atmosphere replacement time of the hearth of the annealing furnace.

The invention has the beneficial effects that: through the fluctuation pressure difference of furnace atmosphere pressure and the cotton atmosphere internal pressure that keeps warm, the cotton internal oxygen that keeps warm is replaced with higher speed to can effectually shorten furnace nitrogen gas replacement time, reduce the nitrogen gas consumption, shorten and resume production time consuming, very big satisfying production rhythm and energy-conserving demand.

Drawings

FIG. 1 is a schematic structural view of the present invention;

in the figure: 1. the device comprises a continuous annealing furnace, 2 parts of heat preservation cotton, 3 parts of a stainless steel lining plate, 4 parts of a nitrogen replacement pipeline, 5 parts of a furnace top diffusion pipeline, 6 parts of a nitrogen flow regulating valve, 7 parts of a furnace top diffusion regulating valve, 8 parts of a hearth pressure transmitter, 9 parts of a heat preservation cotton internal pressure transmitter, 10 parts of an atmosphere analyzer.

Detailed Description

The invention is further illustrated by way of example in the following with reference to the accompanying drawings.

Referring to the attached figure 1, a furnace hearth atmosphere fluctuation pressurization replacement method of a continuous annealing furnace, wherein heat preservation cotton 2 and a stainless steel lining plate 3 are arranged on the inner wall of the continuous annealing furnace 1 and used for preserving and insulating heat of a furnace hearth; the continuous annealing furnace 1 is provided with a nitrogen replacement pipeline 4, and a nitrogen flow regulating valve 6 is arranged on the nitrogen replacement pipeline 4 and used for regulating the flow of the purging nitrogen; the furnace top diffusion regulating valve 7 is arranged on the furnace top diffusion pipeline 5 and is used for regulating the nitrogen replacement purging opening, and the furnace hearth atmosphere fluctuation pressurization replacement method of the continuous annealing furnace comprises the following steps:

firstly, after the annealing furnace is sealed, regulating the nitrogen injection amount through a nitrogen flow regulating valve 6 and regulating the opening degree of a furnace top diffusion regulating valve 7 to ensure that the internal atmosphere pressure of the hearth and the internal atmosphere pressure of the heat preservation cotton are subjected to internal atmosphere replacement of the hearth under the state of 200 ~ 300 Pa;

when the oxygen content of the atmosphere in the hearth is reduced to 7000 ~ 8000ppm, gradually increasing the nitrogen injection amount, and gradually reducing the opening degree of the furnace top diffusion regulating valve 7 until the atmosphere pressure in the hearth is increased to 600 ~ 800Pa, and the atmosphere pressure in the heat-preservation cotton is increased to 450 ~ 550 Pa;

keeping the nitrogen injection amount and the opening degree of the furnace top diffusion regulating valve 7 in the step II, continuously performing the atmosphere replacement inside the hearth until the pressure difference between the atmosphere inside the hearth and the atmosphere inside the heat preservation cotton is less than 10Pa, and continuously performing the atmosphere replacement inside the hearth for 10 ~ 15min in the state;

gradually reducing the nitrogen injection amount, and simultaneously gradually increasing the opening degree of the furnace top diffusion regulating valve 7 until the internal atmosphere pressure of the hearth is reduced to 320 ~ Pa and the internal atmosphere pressure of the heat-preservation cotton is 450 ~ Pa;

keeping the nitrogen injection amount and the opening degree of the furnace top diffusion regulating valve 7 in the step IV, continuously replacing the atmosphere inside the hearth until the pressure difference between the atmosphere inside the hearth and the atmosphere inside the heat preservation cotton is less than 10Pa, and continuously replacing the atmosphere inside the hearth for 3 ~ 5min under the state;

sixthly, repeating the step III to the step V, and starting to ignite and heat the continuous annealing furnace when the oxygen content of the atmosphere in the hearth is reduced to 300 ~ 500 ppm;

and seventhly, in the ignition temperature rise process of the continuous annealing furnace, repeating the step III-the step V at the same time, and finishing the fluctuation pressurization replacement of the furnace chamber atmosphere of the continuous annealing furnace when the oxygen content of the furnace chamber atmosphere is less than 200 ppm.