A method for online leakage detection of radiation tubes in cold rolling annealing furnace

Abstract

The invention discloses an online leakage detection method for radiant tubes of a cold rolling annealing furnace, relates to the technical field of online leakage detection for radiant tubes, and aims to solve the problem that the existing leakage detection method for radiant tubes is cumbersome and it is not convenient to find out the specific leakage places of a large number of radiant tubes; the invention comprises the following steps: installing a CO online detector in the heating area of ​​the radiant tubes of the annealing furnace; when the CO content is abnormal, the radiant tubes are divided into a plurality of areas, a plurality of areas are reserved, and other areas are closed; if the CO content is still abnormal, the radiant tubes in the reserved areas are closed one by one and the CO content is monitored until the CO content of a certain radiant tube returns to normal after being closed, which is the target leaking radiant tube; if the CO content of the reserved area is normal, another area is opened and the CO content is monitored until the abnormal CO content is detected after a certain area is opened, the radiant tubes in the target leaking area are closed one by one and the CO content is monitored until the CO content of a certain radiant tube returns to normal after being closed, which is the target leaking radiant tube; the method of the invention is simple and efficient, and is convenient for accurately finding out the leakage point.

Description

Technical Field

[0001] The invention relates to the technical field of online leakage detection of radiant tubes, in particular to an online leakage detection method for radiant tubes of a cold rolling annealing furnace. Background Art

[0002] The annealing furnace of the cold rolling processing line adopts a large number of radiation tube heating structures. Nitrogen and hydrogen mixed gas is injected into the furnace to reduce the strip and prevent oxidation. The number of radiation tubes usually ranges from 100 to 400. Radiant tubes usually use coal gas or natural gas combustion to provide heat. Long-term use of radiation tubes will cause burn-through and cracking, which will affect the atmosphere in the furnace and cause defects such as strip stains, oxidation and plating leakage. At present, during the overhaul and furnace opening, maintenance personnel enter the annealing furnace and find defects such as cracking of radiation tubes through visual inspection; in addition, when strip defects and abnormal atmosphere in the furnace are caused under normal production conditions, the radiation tubes are shut down one by one for search until the defects are eliminated, and then the overhaul and furnace opening are checked and confirmed. The low efficiency has a great impact on production quality, and there is a lack of effective detection methods for daily radiation tubes.

[0003] In the invention patent application with publication number CN102853976A and titled "Online Leak Detection Method and Device for Radiant Tubes in Heat Treatment Furnaces", a method is disclosed in which a vacuum sampling pump is used to suck a radiant tube with only one opening, and the gas flow is observed to detect whether there is a leak. This method can indeed detect leaks online, but for the existing multi-layer and large-volume radiant tube structures, the detection is extremely cumbersome, and it is even more complicated and cumbersome to accurately detect leaking radiant tubes; therefore, an online leak detection method for radiant tubes in cold rolling annealing furnaces is urgently needed to solve this problem. Summary of the invention

[0004] The object of the present invention is to provide an online leakage detection method for radiant tubes of a cold rolling annealing furnace, so as to solve the problem that the existing radiant tube leakage detection method is complicated and inconvenient to detect the specific leakage locations of a large number of radiant tubes.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an online leakage detection method for a cold rolling annealing furnace radiant tube, comprising the following specific steps: installing a CO online detector in a heating area of ​​the radiant tube of the annealing furnace, detecting the CO content in the furnace by the CO online detector in normal production, and when the CO content is abnormal, indicating that there is a radiation tube leakage, the radiation tube is divided into multiple areas, several areas are reserved, and all the radiation tubes in other areas are closed, and the CO content change trend is monitored. If the CO content is still abnormal, it indicates that the radiation tube leakage is in the reserved area, and the radiation tubes in the reserved area are closed one by one and the CO content is monitored until the CO content of a certain radiation tube returns to normal after being closed, which is the target leakage radiation tube; if the CO content of the reserved area is normal, another area is opened and the CO content is monitored until the CO content is abnormal after a certain area is opened, indicating that the target leakage area is found, and the radiation tubes in the target leakage area are closed one by one and the CO content is monitored until the CO content of a certain radiation tube returns to normal after being closed, which is the target leakage radiation tube.

[0006] Preferably, the CO online detector is fixedly installed on the top of the middle section of the annealing furnace radiation tube heating area.

[0007] Preferably, when the CO content in the furnace is above 5 ppm, it is determined to be abnormal, and when it is less than 5 ppm, it is normal.

[0008] Preferably, when the radiation tubes are divided into a plurality of regions, they are divided according to the number of radiation tube layers, and the same layer is the same region.

[0009] Preferably, when the CO content is abnormal, the radiation tubes on the top layer are retained and the other layers are closed. When the CO content is normal, the radiation tubes are opened layer by layer from top to bottom and the CO content is monitored.

[0010] Preferably, monitoring the change trend of CO content specifically includes the following steps: keeping the radiation tubes in the area to be monitored turned on, keeping the radiation tubes in other areas unchanged for 20 minutes, opening the bleed valve at the top of the annealing furnace for 10 minutes, then closing the bleed valve at the top of the annealing furnace for 10 minutes, and monitoring the change of CO content within 10 minutes of closing the bleed valve.

[0011] Preferably, after the target leaking radiation tube is found, it is closed and disabled, and all other radiation tubes are opened. If the CO content is still abnormal, there are other leakage locations, and leak detection is continued until all the target leaking radiation tubes are closed, and then all other radiation tubes are opened and the CO content is monitored to return to normal.

[0012] Preferably, the CO online detector adopts an infrared sensor type.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The online leakage detection method for the cold rolling annealing furnace radiation tube is simple, convenient, and efficient. It can accurately detect the leakage points in a large number of radiation tubes, and it is easy to realize automatic control, which meets the modern production needs.

[0015] 2. The online leakage detection method for the cold rolling annealing furnace radiation tube can realize online judgment of the continuous annealing furnace radiation tube leakage. Usually, the radiation tube damage has a certain process. The present invention can detect the radiation tube in time to find the leakage state under normal production state, find the radiation tube failure in advance, and shut down the radiation tube in time. The timely shutdown of the leaking radiation tube can reduce the impact on product quality and reduce strip defects. At the same time, it is beneficial to improve the safety of the annealing furnace. The method has low labor intensity and high efficiency, does not affect normal production, and has positive significance for the atmosphere management in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the leak detection process of an embodiment of the present invention. DETAILED DESCRIPTION

[0017] A method for online leak detection of a radiant tube of a cold rolling annealing furnace is provided. A CO online detector is installed in a heating area of ​​the radiant tube of the annealing furnace. In normal production, the CO content in the furnace is detected by the CO online detector. Usually, the annealing furnace is composed of 95% nitrogen and 5% hydrogen, and the radiant tube of the heating section is burned with coal gas and air. The exhaust gas is drawn into a chimney through an exhaust gas pipeline and discharged into the atmosphere. The inventor accidentally discovered that the radiant tube burned through and cracked to cause leakage, and the exhaust gas entered the furnace, and the CO content in the furnace increased significantly. Therefore, a certain amount of CO was detected by the CO online detector to determine whether the radiant tube was leaking.

[0018] Specifically: when the abnormal CO content indicates that there is a radiation tube leakage, the radiation tube is divided into multiple areas, and several areas are reserved. All radiation tubes in other areas are closed, and the trend of CO content changes is monitored. If the CO content is still abnormal, it means that the radiation tube leakage is in the reserved area. The radiation tubes in the reserved area are closed one by one and the CO content is monitored until the CO content returns to normal after a certain radiation tube is closed, which is the target leaking radiation tube; if the CO content in the reserved area is normal, another area is opened and the CO content is monitored until an abnormal CO content is detected after a certain area is opened, indicating that the target leakage area is found. The radiation tubes in the target leakage area are closed one by one and the CO content is monitored until the CO content returns to normal after a certain radiation tube is closed, which is the target leaking radiation tube.

[0019] Example:

[0020] like Figure 1As shown in the figure, a vertical annealing furnace uses high-coke mixed gas as fuel and adopts radiant tube heating. The radiant tube control mode is on / off working mode. The CO online detector adopts infrared sensor type and is fixedly installed on the top of the middle section of the annealing furnace heating section to detect the CO content in the annealing furnace heating section when the radiant tube is in working state, and determine the leakage of the radiant tube.

[0021] During normal production, the online CO gas detector monitors the CO content in the furnace, and the normal CO content is less than 5ppm. When the CO content in the furnace is ≥5ppm, only the top layer of radiation tubes is kept burning according to the number of existing radiation tube layers, and all other radiation tubes are closed on the HMI screen. This state is maintained for 20 minutes, the top relief valve is opened for 10 minutes, and then the top relief valve is closed for 10 minutes, and the CO content in the furnace is monitored within 10 minutes. If the CO content in the furnace is still detected to be ≥5ppm, the radiation tubes of the layer are closed one by one, and the change of CO content in the furnace is monitored at the same time. If the CO content of a radiation tube is less than 5ppm after it is closed, the closed radiation tube is a leaking radiation tube, and the leaking radiation tube is kept closed and out of service.

[0022] If the CO content in the furnace is less than 5ppm when the first layer of radiation tubes is opened, it indicates that the leaking radiation tube is not in the first layer; open the second layer of radiation tubes on the HMI screen, and keep the other layers of radiation tubes closed. Keep this state for 20 minutes, open the top relief valve for 10 minutes, and then close the top relief valve for 10 minutes, and monitor the CO content in the furnace within 10 minutes; if the CO content in the furnace is still detected to be ≧5ppm, close the radiation tubes of this layer one by one, and monitor the change of CO content in the furnace. If the CO content of a radiation tube is less than 5ppm after it is closed, the closed radiation tube is the leaking radiation tube, and the leaking radiation tube remains closed and out of service;

[0023] If the second layer of radiation tubes is opened and the CO content in the furnace is detected to be less than 5ppm, it indicates that the leaking radiation tubes are not in the second layer. Repeat the above operation and perform leak detection layer by layer.

[0024] All radiation tubes on each layer must be opened for inspection to find leaking radiation tubes until the CO content in the furnace is less than 5ppm when all radiation tubes except the deactivated ones are working.

[0025] In the above embodiment, each time a radiation tube is turned off individually, it is best to wait for 1-10 minutes, preferably 3 minutes, to observe the change in CO content to prevent a slight lag in the atmosphere change.

[0026] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0027] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A method for online leakage detection of radiant tubes of a cold rolling annealing furnace, characterized in that: The method comprises the following specific steps: installing a CO online detector in the radiant tube heating area of ​​the annealing furnace, detecting the CO content in the furnace by the CO online detector in normal production, and when the CO content is abnormal, indicating that there is a radiation tube leakage, dividing the radiation tube into multiple areas, retaining several areas, closing all the radiation tubes in other areas, and monitoring the change trend of the CO content. If the CO content is still abnormal, it indicates that the radiation tube leakage is in the reserved area, closing the radiation tubes in the reserved area one by one and monitoring the CO content until the CO content returns to normal after a certain radiation tube is closed, which is the target leaking radiation tube; if the CO content in the reserved area is normal, opening another area and monitoring the CO content until the CO content is abnormal after a certain area is opened, indicating that the target leaking area is found, closing the radiation tubes in the target leaking area one by one and monitoring the CO content until the CO content returns to normal after a certain radiation tube is closed, which is the target leaking radiation tube; The monitoring of the CO content change trend specifically includes the following steps: keeping the radiation tubes in the monitored area turned on and keeping the radiation tubes in other areas unchanged for 20 minutes, opening the bleed valve at the top of the annealing furnace for 10 minutes, then closing the bleed valve at the top of the annealing furnace for 10 minutes, and monitoring the CO content change within 10 minutes of closing the bleed valve; After the target leaking radiation tube is found, it is closed and deactivated, and all other radiation tubes are opened. If the CO content is still abnormal, there are other leak locations. Leak detection is continued until all the target leaking radiation tubes are closed, and then all other radiation tubes are opened and the CO content is monitored to return to normal.

2. The method for online leak detection of a cold rolling annealing furnace radiant tube according to claim 1, characterized in that: The CO online detector is fixedly installed on the top of the middle section of the annealing furnace radiation tube heating area.

3. The method for online leakage detection of a cold rolling annealing furnace radiant tube according to claim 1, characterized in that: When the CO content in the furnace is above 5ppm, it is considered abnormal, and when it is less than 5ppm, it is normal.

4. The method for online leakage detection of a cold rolling annealing furnace radiant tube according to claim 1, characterized in that: When the radiation tubes are divided into a plurality of regions, the regions are divided according to the number of radiation tube layers, and the same layer is the same region.

5. The method for online leak detection of radiant tubes of a cold rolling annealing furnace according to claim 4, characterized in that: When the CO content is abnormal, keep the top layer of radiation tubes first and close the other layers. When the CO content is normal, open the radiation tubes layer by layer from top to bottom and monitor the CO content.

6. The method for online leak detection of a cold rolling annealing furnace radiant tube according to claim 1, characterized in that: The CO online detector adopts an infrared sensor type.

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