On-line leak detection device and on-line leak detection method for annealing furnace radiant tube

Abstract

The invention discloses an on-line leak detection device and an on-line leak detection method for radiant tubes of an annealing furnace, the annealing furnace is uniformly provided with a plurality of radiant tubes and an inlet hearth, the radiant tubes are connected with gas branch tubes, and the gas branch tubes are sequentially provided with gas branch tube control valves and gas branch tube flow detection pore plates; the online leak hunting device comprises a helium source, the helium source is connected with a pressure reducing device, the pressure reducing device is connected with a detection port hand valve, the detection port hand valve is connected with the fuel gas branch pipe flow detection pore plate through a helium connecting pipe, and a helium detector is arranged at the position of the inlet hearth. According to the invention, on-line detection can be carried out at the initial damage stage of the radiant tube in a normal production state, the leakage state of the radiant tube is found in advance and the radiant tube is shut down in time, the influence on the product quality is reduced, the damage degree of the abnormal radiant tube is evaluated, and the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of annealing furnace radiation tube detection, and in particular relates to an online leakage detection device and an online leakage detection method for annealing furnace radiation tubes. Background Art

[0002] At present, the annealing furnace of the cold rolling heat treatment line adopts a large number of radiant tube radiation heating. The radiant tube heating does not contact the strip steel, and the heating is uniform. The furnace is a nitrogen-hydrogen mixed oxygen-free atmosphere, which effectively guarantees the surface quality and plate shape of the strip steel. Usually, there are a large number of radiant tubes in the annealing furnace, ranging from 100 to 400, and most of them are W-shaped. Radiant tubes usually use coal gas, natural gas and other combustion to provide heat. In order to improve the combustion efficiency of radiant tubes, combustion air preheating technology is usually used. The exhaust gas discharged after the combustion of the radiant tube is used to heat the combustion air heat exchanger. The combustion air is heated by the heat exchanger to increase the temperature of the combustion air and improve the combustion efficiency. Usually this type of combustion air heat exchanger is installed in the exhaust gas outlet of the radiant tube. Since the furnace is in a high-temperature heating state for a long time, and the temperature rises and falls frequently according to the annealing temperature of different steel types, and the burner flame is uneven, the radiant tube often has thermal crack failures. On the one hand, it occurs on the radiant tube body. On the other hand, due to the different expansion coefficients between the radiant tube and the furnace shell after heating, cracks will appear in the welds at the welding points. During long-term use, the radiant tube is prone to burn-through and cracking, which affects the service life of the radiant tube. The most serious is that it directly affects the atmosphere in the furnace, causing defects such as strip steel spots, oxidation and plating leakage. At present, during the overhaul and furnace opening, the maintenance personnel enter the annealing furnace and inspect the radiant tube through the appearance to find the cracking problem, and replace the radiant tube simultaneously; under normal production conditions, if there is an abnormality on the plate surface or the atmosphere in the furnace, the abnormal radiant tube is found by shutting down the radiant tube one by one, and then directly deactivating it. There is no effective detection method for the radiant tube in the early stage of damage, and the processing efficiency is low, which affects the heating capacity. Summary of the invention

[0003] The present invention provides an online leak detection device and an online leak detection method for annealing furnace radiation tubes, which can perform online detection at the early stage of radiation tube damage. Under normal production conditions, the radiation tube leakage state can be discovered in advance and shut down in time, reducing the impact on product quality. At the same time, the degree of damage to abnormal radiation tubes can be evaluated to improve production efficiency.

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

[0005] According to one aspect of the present invention, there is provided an online leak detection device for radiant tubes of an annealing furnace, wherein a plurality of the radiant tubes are evenly arranged in the heating section and the soaking section of the annealing furnace, one side is set as an inlet furnace, the radiant tubes are connected to a gas branch pipe, a gas branch pipe control valve and a gas branch pipe flow detection orifice plate are sequentially arranged on the gas branch pipe, the online leak detection device comprises a helium source, a pressure reducing device is connected to the helium source, a detection port manual valve is connected to the pressure reducing device, the detection port manual valve is connected to the gas branch pipe flow detection orifice plate through a helium connecting pipe, and a helium detector is arranged at the inlet furnace.

[0006] Furthermore, the helium connecting pipe is a hose.

[0007] Furthermore, the minimum leak rate specification of the helium detector is 1.0*10-8mbar.l / s.

[0008] Furthermore, the helium source is a helium cylinder.

[0009] According to another aspect of the present invention, an online leakage detection method for annealing furnace radiant tubes is provided, which is performed by the online leakage detection device for annealing furnace radiant tubes described in the above technical solution. The method is as follows:

[0010] S1, decompressing the helium source to a set pressure through the decompression device;

[0011] S2, installing the helium detector at the entrance furnace of the annealing furnace;

[0012] S3, connecting the helium connecting pipe to the detection port of the gas branch pipe flow detection orifice plate connected to one of the ignited and heated radiation tubes on the annealing furnace, opening the detection port hand valve, and closing the detection port hand valve after helium is delivered to the radiation tube through the gas branch pipe for a set time;

[0013] S4. Perform helium detection by the helium detector. If helium is detected within a set time, it indicates that the radiation tube is leaking. If no helium is detected within the set time, it indicates that the radiation tube is not leaking.

[0014] Furthermore, the method also includes: after the radiation tube is leak-proof after being detected by the helium detector, the helium connecting tube connected to the helium source is connected to the detection port of the gas branch flow detection orifice plate connected to the next ignited and heated radiation tube, and the test is performed according to the S1-S4 method.

[0015] Furthermore, the method also includes: when the radiation tube is detected to have a leak by the helium detector, shutting down the radiation tube, waiting for a set time, and after no helium component can be detected by the helium detector, connecting the helium connecting tube connected to the helium source to the detection port of the gas branch flow detection orifice plate connected to the next ignited and heated radiation tube, and testing according to the S1-S4 method.

[0016] Furthermore, the waiting time is set to 10 minutes.

[0017] Furthermore, the pressure of the gas branch pipe is controlled below 10Kpa; the set pressure to which the helium source in S1 is reduced by the pressure reducing device is 30Kpa; the set time for delivering helium to the radiation tube through the gas branch pipe in S3 is 1 minute; and the set time for the helium detector to perform helium detection in S4 is 5 minutes.

[0018] Compared with the prior art, the online leakage detection device and the online leakage detection method for annealing furnace radiant tubes of the present invention involve common components or equipment, which are easy to assemble and detect. In combination with the leakage detection method, the leakage of the annealing furnace radiant tubes can be determined online and accurately located. It is convenient and reliable, and can timely analyze and judge the shutdown or power reduction measures based on the leakage rate of the leaking radiant tubes, thereby reducing the impact on product quality, reducing the impact of cracking of the radiant tubes on the furnace atmosphere and the radiant tubes, and improving the equipment life and production efficiency. In addition, the method adopts online dynamic detection, does not affect normal production, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of an online leak detection device for annealing furnace radiant tubes according to the present invention;

[0020] In the figure: 1. Helium source; 2. Pressure reducing device; 3. Detection port manual valve; 4. Gas branch flow detection orifice plate; 5. Helium connecting pipe; 6. Radiant tube; 7. Inlet furnace; 8. Helium detector; 9. Annealing furnace; 10. Gas branch; 11. Gas branch control valve. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in 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 in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the usual meanings understood by people with general skills in the field to which the present disclosure belongs. "Up", "down", "left", "right", "front", "back" and the like 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 can include electrical connections, whether direct or indirect. The parts not described in detail in the present invention are all known technologies of technicians in the field of this technology.

[0022] Embodiment 1:

[0023] like Figure 1 As shown, the heating section and the soaking section of the annealing furnace 9 are evenly provided with a plurality of radiation tubes 6, and an inlet furnace 7 of the furnace area is also provided. A gas branch pipe 10 is connected to the radiation tube 6, and the gas branch pipe 10 is used to transport coal gas or natural gas for combustion to the radiation tube 6. A gas branch pipe control valve 11 and a gas branch pipe flow detection orifice plate 4 are sequentially provided on the gas branch pipe 10. The gas branch pipe control valve 11 is used to control the gas flow and pressure, and the gas branch pipe flow detection orifice plate 4 is provided with a detection port for detecting the gas flow in the pipe.

[0024] The online leak detection device for the annealing furnace radiation tube provided by the present invention includes a helium source 1, which is usually a helium bottle, which is convenient and practical. The helium source 1 is connected to a pressure reducing device 2, and the pressure reducing device 2 is connected to a detection port hand valve 3, which is connected to a gas branch pipe flow detection orifice plate 4 through a helium connecting pipe 5, and is used to send helium to the gas branch pipe 10 and send it into the radiation tube 6 together with the gas when the radiation tube 6 is operating normally. A helium detector 8 for detecting the helium composition in the furnace is provided at the entrance furnace 7 of the annealing furnace 9; the helium connecting pipe 5 is usually a hose, which is easy to connect. The minimum leak rate specification of the helium detector 8 is 1.0*10-8mbar.l / s, such as the INFICON UL1000 mobile helium vacuum leak detector, which uses the internal helium mass spectrometer of the instrument to analyze and output the leak rate result, and the change trend of the leak rate value detected by helium reflects whether the radiation tube body is damaged and the degree of damage. The mobile helium detector can detect a minimum leakage rate of 1.0*10-8mbar.l / s, i.e. -8 level. The leakage of the radiation tube body can be judged by the change in the leakage rate trend. After the device is turned on and left to stand for more than 20 minutes, the helium content in the initial state of the air that can be measured is (5~6)*10-9mbar.l / s.

[0025] Embodiment 2:

[0026] The present invention provides an online leakage detection method for annealing furnace radiant tubes, which is performed by the online leakage detection device for annealing furnace radiant tubes in Example 1. The radiant tubes 6 in the annealing furnace 9 are produced normally. The leakage detection method is as follows:

[0027] S1. Reduce the pressure of the helium source 1 to a set pressure of 30 Kpa via the pressure reducing device 2.

[0028] S2. A helium detector 8 is provided at the entrance furnace 7 of the furnace zone of the annealing furnace 9.

[0029] S3. Connect the detection port of the gas branch pipe flow detection orifice plate 4 connected to one of the ignited and heated radiation tubes 6 on the annealing furnace 9 through the helium connecting pipe 5, open the detection port manual valve 3, and after helium is delivered to the radiation tube 6 through the gas branch pipe 10 for the set time of 1 minute, close the detection port manual valve 3; the pressure of the gas branch pipe 10 is controlled at 9Kpa.

[0030] S4. Perform helium detection by the helium detector 8. If helium is detected within the set time of 5 minutes, it indicates that the radiation tube 6 has a leak. If no helium is detected within the set time of 5 minutes, it indicates that the radiation tube 6 has no leak, and the helium is discharged from the radiation tube 6 through the exhaust gas pipeline.

[0031] When the radiation tube 6 is leak-proof after being detected by the helium detector 8, the helium connecting tube 5 connected to the helium source 1 is connected to the detection port of the gas branch flow detection orifice plate 4 connected to the next ignited and heated radiation tube 6, and the test is continued according to the above S1-S4 method.

[0032] When the radiation tube 6 is tested for leakage by the helium detector 8, if the helium component is detected to be ≥1.0*10-8mbar.l / s, the radiation tube 6 is shut down, and after waiting for a set time of 10 minutes, when no helium component can be detected by the helium detector 8, the helium connecting pipe 5 connected to the helium source 1 is connected to the detection port of the gas branch flow detection orifice plate 4 connected to the next ignited and heated radiation tube 6, and the test is continued in the S1-S4 mode.

[0033] After the present invention was applied in a certain steel enterprise, very good results were achieved. The surface color of the steel strip produced by a certain horizontal annealing furnace of the steel enterprise was dark. After detection by the atmosphere detection analyzer in the furnace, the oxygen content ppm and the dew point detector were both within the normal range. There was no abnormality in the inspection of the cleaning section of the production line, the steel strip inspection was no abnormality, and there was no abnormality in the leakage point detection of the furnace body and the negative pressure area. The annealing furnace adopts coke oven gas to heat the radiant tube, and the radiant tube control mode is ON / OFF mode. The air-fuel ratio of the radiant tube is detected by the gas branch flow detection orifice plate and the combustion air flow detection orifice plate. The air-fuel ratio is adjusted to achieve a one-time adjustment and fix the combustion flow. Then, helium detection was performed on the 120 radiant tubes in the heating section of the annealing furnace. Through the detection, it was found that 3 radiant tubes were leaking, and then they were shut down and deactivated. The color of the produced steel strip returned to normal. The method is simple and practical, and the effect is obvious.

Claims

1. An online leak detection device for annealing furnace radiant tubes, wherein the annealing furnace (9) is evenly provided with a plurality of radiant tubes (6), one side of which is provided with an inlet furnace (7), the radiant tubes (6) are connected with a gas branch pipe (10), the gas branch pipe (10) is sequentially provided with a gas branch pipe control valve (11) and a gas branch pipe flow detection orifice plate (4), characterized in that: The online leak detection device comprises a helium source (1), the helium source (1) is connected to a pressure reducing device (2), the pressure reducing device (2) is connected to a detection port hand valve (3), the detection port hand valve (3) is connected to the gas branch pipe flow detection orifice plate (4) through a helium connecting pipe (5), and a helium detector (8) is arranged at the inlet furnace (7).

2. The on-line leakage detection device for annealing furnace radiant tube according to claim 1, characterized in that: The helium connecting pipe (5) is a hose.

3. The on-line leakage detection device for annealing furnace radiant tube according to claim 1, characterized in that: The minimum leak rate specification of the helium detector (8) is 1.0*10-8mbar.l / s.

4. The on-line leak detection device for annealing furnace radiant tube according to claim 1, characterized in that: The helium source (1) is a helium cylinder.

5. The online leak detection method of the online leak detection device for annealing furnace radiant tube according to any one of claims 1 to 4, characterized in that: The method is as follows: S1, reducing the pressure of the helium source (1) to a set pressure via the pressure reducing device (2); S2, installing the helium detector (8) at the entrance furnace (7) of the furnace zone of the annealing furnace (9); S3, connecting the detection port of the gas branch pipe flow detection orifice plate (4) connected to one of the ignited and heated radiation tubes (6) on the annealing furnace (9) through the helium connection pipe (5), opening the detection port hand valve (3), and after helium is delivered to the radiation tube (6) through the gas branch pipe (10) for a set time, closing the detection port hand valve (3); S4. Performing helium detection by means of the helium detector (8). If helium is detected within a set time, it indicates that the radiation tube (6) is leaking. If no helium is detected within a set time, it indicates that the radiation tube (6) is not leaking.

6. The online leak detection method according to claim 5, characterized in that: Also includes: When the radiation tube (6) is detected to have no leakage by the helium detector (8), the helium connecting tube (5) connected to the helium source (1) is connected to the detection port of the gas branch flow detection orifice plate (4) connected to the next ignited and heated radiation tube (6), and the test is carried out according to the S1-S4 method.

7. The online leak detection method according to claim 5, characterized in that: Also includes: When the radiation tube (6) is detected to have leakage by the helium detector (8), the radiation tube (6) is shut down, and after waiting for a set time, when no helium component can be detected by the helium detector (8), the helium connecting tube (5) connected to the helium source (1) is connected to the detection port of the gas branch flow detection orifice plate (4) connected to the next ignited and heated radiation tube (6), and the test is performed according to the S1-S4 method.

8. The online leak detection method according to claim 5, characterized in that: The waiting time is set to 10 minutes.

9. The online leak detection method according to any one of claims 5 to 8, characterized in that: The pressure of the gas branch pipe (10) is controlled to be below 10 KPa; the set pressure to which the helium source (1) in S1 is reduced by the pressure reducing device (2) is 30 KPa; the set time for delivering helium to the radiation tube (6) through the gas branch pipe (10) in S3 is 1 minute; and the set time for the helium detector (8) in S4 to perform helium detection is 5 minutes.

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