Method and system for monitoring high-temperature corrosion of water cooling wall of boiler

Abstract

The embodiment of the invention provides a boiler water-cooled wall high-temperature corrosion monitoring method and system. The method comprises the steps that a smoke sample close to a water-cooled wall in a boiler is obtained; respectively measuring the concentration of CO, the concentration of O2 and the concentration of H2S in the flue gas sample; and judging the high-temperature corrosion degree of the water cooling wall according to the measured CO concentration, O2 concentration and H2S concentration. According to the method, the high-temperature corrosion degree of the water-cooled wall is judged according to the gas component concentration in a flue gas sample close to the water-cooled wall in a boiler, online monitoring of the high-temperature corrosion degree of the water-cooled wall is achieved, the tendency of high-temperature corrosion of the water-cooled wall can be monitored online in real time through monitoring of the wall-adhering atmosphere of the water-cooled wall, advanced pre-control is achieved, and real-time monitoring is achieved. And operation and maintenance personnel are reminded to carry out operation and maintenance work in time according to the monitored high-temperature corrosion degree of the water-cooled wall, high-temperature corrosion and pipe explosion of the water-cooled wall are prevented, and the safety and economical efficiency of unit operation are improved.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of high-temperature corrosion monitoring of boiler water walls, and particularly relate to a method and system for monitoring high-temperature corrosion of boiler water walls. Background Art

[0002] With the implementation of ultra-low emission transformation, in order to reduce nitrogen oxides, low-nitrogen burners are generally adopted in boilers. The low-nitrogen combustion technology uses air-staged combustion to reduce nitrogen oxides. The main combustion area operates under oxygen-deficient conditions, and pulverized coal combustion is incomplete, resulting in a strongly reducing atmosphere. Coupled with the tight coal market situation, in order to reduce fuel costs, some high-sulfur coal is co-fired, leading to high-temperature sulfur corrosion of the water wall in a reducing atmosphere.

[0003] High-temperature corrosion can cause the water wall to thin, reduce the metal strength, and under the action of alternating thermal stress, the corrosion products will also accelerate the expansion of transverse cracks, greatly increasing the risk of water wall tube rupture, causing unplanned shutdown of the unit, and seriously threatening the safe and stable operation of the unit.

[0004] Thermal power plants implement technical supervision of high-temperature corrosion of the water wall by measuring the thickness of the water wall during maintenance. The degree of high-temperature corrosion of the water wall is evaluated through the measurement results, and passive protection measures such as tube replacement and anti-corrosion spraying are taken, which has a certain lag. There is an inseparable connection between the wall-attached atmosphere of the water wall and high-temperature corrosion. By monitoring the wall-attached atmosphere of the water wall, the tendency of high-temperature corrosion of the water wall can be monitored in real time online, achieving early pre-control.

[0005] In view of the above problems, it is necessary to propose a method and system for monitoring high-temperature corrosion of boiler water walls that are reasonably designed and can effectively solve the above problems. Summary of the Invention

[0006] The embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a method and system for monitoring high-temperature corrosion of boiler water walls.

[0007] One aspect of the embodiments of the present disclosure provides a method for monitoring high-temperature corrosion of a boiler water wall, the method comprising:

[0008] Obtaining a flue gas sample inside the boiler near the water wall;

[0009] Measuring the CO concentration, O 2 concentration and H 2 S concentration in the flue gas sample respectively;

[0010] Determining the degree of high-temperature corrosion of the water wall according to the measured CO concentration, the O 2 concentration and the H 2 S concentration.

[0011] Optionally, determining the high-temperature corrosion degree of the water wall according to the measured CO concentration, the O 2 concentration, and the H 2 S concentration includes:

[0012] When the O 2 concentration ≥ 2%, it is determined that there is no high-temperature corrosion risk for the water wall;

[0013] When 1% ≤ the O 2 concentration < 2% and the CO concentration < 0.1%, it is determined that the water wall is at a slight high-temperature corrosion risk;

[0014] When 0.1% ≤ the CO concentration ≤ 3% and 0.01% ≤ the H 2 S concentration ≤ 0.02%, it is determined that the water wall is at a medium high-temperature corrosion risk;

[0015] When the CO concentration > 3% or the H 2 S concentration > 0.02%, it is determined that the water wall is at a severe high-temperature corrosion risk.

[0016] Optionally, the method further includes:

[0017] When the water wall is at the medium high-temperature corrosion risk or the severe high-temperature corrosion risk, an alarm is issued.

[0018] Optionally, the method further includes:

[0019] Obtaining the cumulative operating duration of the water wall at various levels of high-temperature corrosion risk within one maintenance cycle;

[0020] Determining whether to issue an alarm according to the cumulative operating duration.

[0021] Optionally, determining whether to issue an alarm according to the cumulative operating duration includes:

[0022] When the cumulative operating duration of the water wall at the medium high-temperature corrosion risk and / or the severe high-temperature corrosion risk within one maintenance cycle is greater than 1500 h, an alarm is issued.

[0023] Optionally, after obtaining the flue gas sample near the water wall in the boiler, the method further includes:

[0024] Filtering and drying the flue gas sample to remove dust and moisture in the flue gas sample.

[0025] Another aspect of the embodiments of the present disclosure provides a high-temperature corrosion monitoring system for a boiler water wall, including a sampling device, a first gas measuring device, a second gas measuring device, and a processor;

[0026] The first end of the sampling device penetrates through the water-cooled wall and extends into the boiler, and the second end of the sampling device is connected to the first gas measuring device and the second gas measuring device respectively through a gas transmission pipeline; wherein,

[0027] The sampling device is used to obtain a flue gas sample near the water-cooled wall in the boiler;

[0028] The first gas measuring device is used to measure the CO concentration and O 2 concentration in the flue gas sample;

[0029] The second gas measuring device is used to measure the H 2 S concentration in the flue gas sample;

[0030] The processor is electrically connected to the first gas measuring device and the second gas measuring device respectively, and is used to determine the high-temperature corrosion degree of the water-cooled wall according to the measured CO concentration, the O 2 concentration and the H 2 S concentration.

[0031] Optionally, the processor is further used for:

[0032] When the O 2 concentration ≥ 2%, it is determined that there is no high-temperature corrosion risk for the water-cooled wall;

[0033] When 1% ≤ the O 2 concentration < 2% and the CO concentration < 0.1%, it is determined that the water-cooled wall is at a slight high-temperature corrosion risk;

[0034] When 0.1% ≤ the CO concentration ≤ 3% and 0.01% ≤ the H 2 S concentration ≤ 0.02%, it is determined that the water-cooled wall is at a medium high-temperature corrosion risk;

[0035] When the CO concentration > 3% or the H 2 S concentration > 0.02%, it is determined that the water-cooled wall is at a serious high-temperature corrosion risk.

[0036] Optionally, the system further includes an alarm device electrically connected to the processor;

[0037] The alarm device is used to give an early warning when the water-cooled wall is at the medium high-temperature corrosion risk or the serious high-temperature corrosion risk;

[0038] The alarm device is further used to give an early warning when the cumulative operation duration of the water-cooled wall at the medium high-temperature corrosion risk and / or the serious high-temperature corrosion risk within one maintenance cycle is greater than 1500h.

[0039] Optionally, the system further includes a filtering and drying device and an anti-blowing and anti-blocking device;

[0040] The filtering and drying device is connected in series to the gas transmission pipeline;

[0041] The anti-blowing and anti-blocking device includes a compressed air tank and an anti-blowing pipeline. The first end of the anti-blowing pipeline is connected to the second end of the sampling device, and the second end of the anti-blowing device is connected to the compressed air tank.

[0042] In the boiler water wall high-temperature corrosion monitoring method and device according to an embodiment of the present disclosure, the method includes: obtaining a flue gas sample near the water wall in the boiler; respectively measuring the CO concentration, O 2 concentration, and H 2 S concentration in the flue gas sample; and determining the high-temperature corrosion degree of the water wall according to the measured CO concentration, O 2 concentration, and H 2 S concentration. This method determines the high-temperature corrosion degree of the water wall through the gas component concentrations in the flue gas sample near the water wall in the boiler, realizes the online monitoring of the high-temperature corrosion degree of the water wall, can monitor the tendency of high-temperature corrosion of the water wall in real time through the monitoring of the atmosphere near the water wall, achieve early pre-control, and remind the operation and maintenance personnel to carry out operation and maintenance work in time according to the monitored high-temperature corrosion degree of the water wall, prevent the water wall from suffering from high-temperature corrosion and bursting, and improve the safety and economy of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic flow chart of a boiler water wall high-temperature corrosion monitoring method according to an embodiment of the present disclosure;

[0044] Figure 2 is a schematic structural diagram of a boiler water wall high-temperature corrosion monitoring system according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0045] To enable those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, the following further describes the embodiments of the present disclosure in detail with reference to the drawings and specific embodiments.

[0046] As Figure 1 shown, one aspect of the embodiment of the present disclosure provides a boiler water wall high-temperature corrosion monitoring method S100, and the method S100 includes:

[0047] S110. Obtain a flue gas sample near the water wall in the boiler.

[0048] Specifically, as Figure 2 shown, a flue gas sample near the water wall A in the boiler is obtained through the sampling device 1.

[0049] S120. Measure the CO concentration, O 2 concentration, and H 2 S concentration in the flue gas sample respectively.

[0050] Specifically, as Figure 2 shown, measure the CO concentration and O 2 concentration of the flue gas sample through the first gas measurement device 2, and measure the H 2 S concentration in the flue gas sample through the second gas measurement device 3. Among them, the first gas measurement device 2 and the second gas measurement device 3 can adopt a flue gas measuring instrument.

[0051] S130. Determine the high-temperature corrosion degree of the water wall according to the measured CO concentration, the O 2 concentration, and the H 2 S concentration.

[0052] Specifically, the processor 4 determines the high-temperature corrosion degree of the water wall A according to the measured CO concentration, O 2 concentration, and H 2 S concentration. Among them, the specific process for the processor 4 to determine the high-temperature corrosion degree of the water wall A can be as follows:

[0053] When the O 2 concentration ≥ 2%, it is determined that the water wall has no risk of high-temperature corrosion.

[0054] When 1% ≤ the O 2 concentration < 2% and the CO concentration < 0.1%, it is determined that the water wall is at a slight high-temperature corrosion risk.

[0055] When 0.1% ≤ the CO concentration ≤ 3% and 0.01% ≤ the H 2 S concentration ≤ 0.02%, it is determined that the water wall is at a medium high-temperature corrosion risk.

[0056] When the CO concentration > 3% or the H 2 S concentration > 0.02%, it is determined that the water wall is at a severe high-temperature corrosion risk.

[0057] Since there is an inseparable connection between the concentration of the atmosphere adjacent to the water wall and high-temperature corrosion, the tendency of high-temperature corrosion of the water wall can be monitored in real time and online through the monitoring of the atmosphere adjacent to the water wall, achieving early pre-control.

[0058] Exemplarily, the method further includes:

[0059] When the water wall A is at medium high-temperature corrosion risk or severe high-temperature corrosion risk, the alarm device issues a warning to remind the operation and maintenance personnel to carry out operation and maintenance work in a timely manner. Among them, the warning can be issued through sound or light, and this embodiment does not make specific limitations and can be selected according to actual needs.

[0060] Exemplarily, the method further includes:

[0061] Obtaining the cumulative operation duration of the water wall A at various levels of high-temperature corrosion risk within one maintenance cycle.

[0062] Determining whether to issue a warning according to the cumulative operation duration.

[0063] Specifically, automatically counting the cumulative operation durations of the water wall A at no high-temperature corrosion risk, slight high-temperature corrosion risk, medium high-temperature corrosion risk, and severe high-temperature corrosion risk respectively within one maintenance cycle.

[0064] Among them, when the cumulative operation duration of the water wall A at medium high-temperature corrosion risk and / or severe high-temperature corrosion risk within one maintenance cycle is greater than 1500h, the alarm device issues a warning.

[0065] That is to say, when the cumulative operation duration of the water wall A at medium high-temperature corrosion risk within one maintenance cycle is greater than 1500h, or when the cumulative operation duration of the water wall A at severe high-temperature corrosion risk within one maintenance cycle is greater than 1500h, or when the cumulative operation duration of the water wall A at medium high-temperature corrosion risk and severe high-temperature corrosion risk within one maintenance cycle is greater than 1500h, the alarm device issues a warning.

[0066] Exemplarily, after obtaining the flue gas sample near the water wall in the boiler, the method further includes:

[0067] Filtering and drying the flue gas sample to remove dust and moisture in the flue gas sample for more accurate measurement of the concentrations of various atmospheres in the flue gas sample.

[0068] The boiler water wall high-temperature corrosion monitoring method of the present disclosure embodiment, the method includes: obtaining a flue gas sample near the water wall in the boiler; respectively measuring the CO concentration, O 2 concentration, and H 2 S concentration in the flue gas sample; according to the measured CO concentration, O 2 concentration, and H 2The S concentration is used to determine the high-temperature corrosion degree of the water-cooled wall. This method determines the high-temperature corrosion degree of the water-cooled wall through the gas component concentrations in the flue gas sample near the water-cooled wall in the boiler, realizes the online monitoring of the high-temperature corrosion degree of the water-cooled wall. Through the monitoring of the atmosphere adhering to the water-cooled wall, the tendency of high-temperature corrosion of the water-cooled wall can be monitored in real time online, achieving early pre-control. According to the monitored high-temperature corrosion degree of the water-cooled wall, it reminds the operation and maintenance personnel to carry out operation and maintenance work in a timely manner, preventing the water-cooled wall from suffering from high-temperature corrosion and tube explosion, and improving the safety and economy of the unit operation.

[0069] Exemplarily, as Figure 2 shown, on the other hand, an embodiment of the present disclosure provides a high-temperature corrosion monitoring system for a boiler water-cooled wall, including a sampling device 1, a first gas measurement device 2, a second gas measurement device 3, and a processor 4.

[0070] The first end of the sampling device 1 penetrates through the water-cooled wall A and extends into the boiler, and the second end of the sampling device 1 is connected to the first gas measurement device 2 and the second gas measurement device 3 respectively through a gas transmission pipeline 5.

[0071] Among them, the sampling device 1 is used to obtain a flue gas sample near the water-cooled wall in the boiler.

[0072] The first gas measurement device 2 is used to measure the CO concentration and O 2 concentration in the flue gas sample.

[0073] The second gas measurement device 3 is used to measure the H 2 S concentration in the flue gas sample;

[0074] The processor 4 is electrically connected to the first gas measurement device 2 and the second gas measurement device 3 respectively, and is used to determine the high-temperature corrosion degree of the water-cooled wall according to the measured CO concentration, O 2 concentration, and H 2 S concentration.

[0075] Specifically, the flue gas sample taken by the sampling device 1 is respectively transported to the first gas measurement device 2 and the second gas measurement device 3 through the gas transmission pipeline 5. Among them, the first gas measurement device 2 measures the CO concentration and O 2 concentration in the flue gas sample, and the second gas measurement device 3 measures the H 2 S concentration in the flue gas sample, preventing measurement interference caused by CO and H 2 S and ensuring accurate measurement. The measured CO, O 2 , H 2 S concentration signals are sent to the processor 4 for processing. After receiving the CO, O 2 , H 2 S concentration signals, the processor 4 automatically draws CO, O 2 , H 2S concentration distribution map and based on CO, O 2 , H 2 S concentration to draw a regional distribution map of the high-temperature corrosion degree to determine the high-temperature corrosion degree of the water wall.

[0076] As Figure 2 shown, an air extraction pump 6 and a stop valve 7 are also connected in series in the gas transmission pipeline 5. The flue gas sample taken by the sampling device 1 is extracted to the first gas measuring device 2 and the second gas measuring device 3 through the air extraction pump 6. The stop valve 7 is used to control the opening and closing of the gas transmission pipeline 5.

[0077] It should be noted that in this embodiment, the sampling device 1 can use high-temperature resistant stainless steel pipes such as 310S, 316H, RA330, etc. The pipe specification is φ8mm×2mm, and a sampling head is provided at the front end of the pipe. The sampling head is of bell shape.

[0078] It should be further noted that in this embodiment, the first gas measuring device 2 and the second gas measuring device 3 can use flue gas measuring instruments.

[0079] Exemplarily, the processing process of the processor for the CO concentration, O 2 concentration and H 2 S concentration signals is as follows:

[0080] When the O 2 concentration ≥ 2%, it is determined that there is no high-temperature corrosion risk for the water wall.

[0081] When 1% ≤ O 2 concentration < 2% and the CO concentration < 0.1%, it is determined that the water wall is in a slight high-temperature corrosion risk.

[0082] When 0.1% ≤ CO concentration ≤ 3% and 0.01% ≤ H 2 S concentration ≤ 0.02%, it is determined that the water wall is in a medium high-temperature corrosion risk.

[0083] When the CO concentration > 3% or H 2 S concentration > 0.02%, it is determined that the water wall is in a severe high-temperature corrosion risk.

[0084] Exemplarily, the system further includes an alarm device electrically connected to the processor 4.

[0085] The alarm device is used to give an early warning when the water wall A is in a medium high-temperature corrosion risk or a severe high-temperature corrosion risk.

[0086] The alarm device is also used to give an early warning when the cumulative operation duration of the water wall A in a medium high-temperature corrosion risk and / or a severe high-temperature corrosion risk within one maintenance cycle is greater than 1500h.

[0087] It should be noted that the alarm device can adopt an alarm, and the way for the alarm to issue a warning can be through sound alarm or light alarm. This embodiment does not make specific limitations and can be selected according to actual needs.

[0088] Exemplarily, as Figure 2 shown, the system further includes a filtering and drying device 6 and an anti-purge and anti-blocking device.

[0089] The filtering and drying device 8 is connected in series to the gas transmission pipeline 5. Specifically, the filtering and drying device 6 is used to filter and dry the flue gas sample to remove dust and moisture in the flue gas sample, so as to more accurately measure the concentrations of various atmospheres in the flue gas sample.

[0090] Among them, the filtering and drying device 8 can include a washing tank and a drying tank. The washing tank contains solutions such as FeSO 4 , CuSO 4 etc. The drying tank is filled with a desiccant. The flue gas first enters the washing tank to remove dust in the flue gas, and then enters the drying tank to fully dry the flue gas.

[0091] The anti-purge and anti-blocking device includes a compressed air tank 9 and an anti-purge pipeline 10. The first end of the anti-purge pipeline 10 is connected to the second end of the sampling device 1, and the second end of the anti-purge device 10 is connected to the compressed air tank 9. A shut-off valve 11 is provided on the anti-purge pipeline 10.

[0092] The purging process is as follows: close the stop valve 7, open the shut-off valve 11, and the compressed air in the compressed air tank 9 purges the sampling device 1. The compressed air pressure is 3 MPa to 5 MPa, and the purging period is 1 to 2 h / time to prevent the sampling device 1 from being blocked.

[0093] It should be noted that the system can be vertically installed and grid-distributed on the four-sided water-cooled wall fins in the main burner to burnout air area, with one arranged every 2 m to 3 m. According to the CO, O 2 , H 2 S concentration signals measured at each point, the processor determines the high-temperature corrosion degree of the water-cooled wall according to the CO, O 2 , H 2 S concentration signals measured at each point.

[0094] The high-temperature corrosion monitoring system for the boiler water wall in the embodiments of the present disclosure. This system obtains the flue gas sample near the water wall in the boiler through a sampling device, measures the gas component concentrations in the flue gas sample through a first gas measuring device and a second gas measuring device, and the processor determines the high-temperature corrosion degree of the water wall according to the measured gas component concentrations, realizing the online monitoring of the high-temperature corrosion degree of the water wall. Through the monitoring of the atmosphere adhering to the water wall, this system can monitor the tendency of high-temperature corrosion of the water wall in real time and online, achieve early pre-control, remind the operation and maintenance personnel to carry out operation and maintenance work in time according to the monitored high-temperature corrosion degree of the water wall, prevent the water wall from bursting due to high-temperature corrosion, and improve the safety and economy of the unit operation.

[0095] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the embodiments of the present disclosure. However, the embodiments of the present disclosure are not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the embodiments of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the embodiments of the present disclosure.

Claims

1. A method for monitoring high temperature corrosion of boiler water wall, characterized in that: The method comprises: Obtaining a flue gas sample close to the water-cooled wall in the boiler; Measuring the CO concentration, O2 concentration and H2S concentration in the flue gas sample respectively; The high-temperature corrosion degree of the water-cooled wall is determined according to the measured CO concentration, the O 2 concentration and the H 2 S concentration.

2. The method according to claim 1, characterized in that The step of determining the degree of high temperature corrosion of the water-cooled wall according to the measured CO concentration, O2 concentration, and H2S concentration includes: When the O2 concentration is ≥ 2%, it is determined that the water-cooled wall has no high-temperature corrosion risk; When 1%≤the O2 concentration<2% and the CO concentration<0.1%, it is determined that the water-cooled wall is at a slight high-temperature corrosion risk; When 0.1%≤the CO concentration≤3% and 0.01%≤the H2S concentration≤0.02%, it is determined that the water-cooled wall is at a medium high-temperature corrosion risk; When the CO concentration is greater than 3% or the H 2 S concentration is greater than 0.02%, it is determined that the water-cooled wall is at a risk of severe high-temperature corrosion.

3. The method according to claim 2, characterized in that The method further comprises: When the water-cooled wall is at the medium high-temperature corrosion risk or the severe high-temperature corrosion risk, an early warning is issued.

4. The method according to claim 2, characterized in that: The method further comprises: Obtaining the cumulative operation time of the water-cooled wall at various levels of high-temperature corrosion risk during an overhaul cycle; Whether to issue an early warning is determined based on the accumulated running time.

5. The method according to claim 4, characterized in that The determining whether to issue an early warning according to the accumulated operation time includes: When the cumulative operation time of the water-cooled wall being at the medium high-temperature corrosion risk and / or the severe high-temperature corrosion risk during one maintenance cycle is greater than 1500 hours, an early warning is issued.

6. The method according to any one of claims 1 to 4, characterized in that: After obtaining the flue gas sample close to the water-cooled wall in the boiler, the method further includes: The flue gas sample is filtered and dried to remove dust and moisture in the flue gas sample.

7. A boiler water wall high temperature corrosion monitoring system, characterized in that: It includes a sampling device, a first gas measuring device, a second gas measuring device and a processor; The first end of the sampling device extends through the water-cooled wall into the boiler, and the second end of the sampling device is connected to the first gas measuring device and the second gas measuring device through a gas pipeline; wherein, The sampling device is used to obtain flue gas samples close to the water-cooled wall in the boiler; The first gas measuring device is used to measure the CO concentration and O2 concentration in the flue gas sample; The second gas measuring device is used to measure the H2S concentration in the flue gas sample; The processor is electrically connected to the first gas measuring device and the second gas measuring device respectively, and is used to determine the high-temperature corrosion degree of the water-cooled wall according to the measured CO concentration, the O2 concentration and the H2S concentration.

8. The system according to claim 7, characterized in that The processor is further configured to: When the O2 concentration is ≥ 2%, it is determined that the water-cooled wall has no high-temperature corrosion risk; When 1%≤the O2 concentration<2% and the CO concentration<0.1%, it is determined that the water-cooled wall is at a slight high-temperature corrosion risk; When 0.1%≤the CO concentration≤3% and 0.01%≤the H2S concentration≤0.02%, it is determined that the water-cooled wall is at a medium high-temperature corrosion risk; When the CO concentration is greater than 3% or the H 2 S concentration is greater than 0.02%, it is determined that the water-cooled wall is at a risk of severe high-temperature corrosion.

9. The system according to claim 8, characterized in that The system also includes an alarm device electrically connected to the processor; The alarm device is used to issue an early warning when the water-cooled wall is at the medium high-temperature corrosion risk or the severe high-temperature corrosion risk; The alarm device is also used to issue an early warning when the cumulative operation time of the water-cooled wall being at the medium high-temperature corrosion risk and / or the severe high-temperature corrosion risk during one maintenance cycle is greater than 1500 hours.

10. The system according to claim 7, characterized in that The system also includes a filtering and drying device and a back-flushing and anti-blocking device; The filtering and drying device is arranged in series with the gas pipeline; The back-purge anti-blocking device comprises a compressed air tank and a back-purge pipeline, wherein a first end of the back-purge pipeline is connected to a second end of the sampling device, and a second end of the back-purge device is connected to the compressed air tank.

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