A device for measuring the oxygen content in boiler flue gas and its measuring method

Abstract

The present invention relates to the technical field of flue gas measurement, and particularly relates to a device for measuring the oxygen content in boiler flue gas and its measurement method. Its technical solution includes: a flue gas pipeline body, a flange, a first connection cover, a sampling pipe, a sampling tank and a second connection cover. One side of the inner wall of the flue gas pipeline body is inserted and installed with a sampling pipe. The inner wall of the sampling pipe is provided with filters distributed in a rectangular array. One end of the sampling pipe passing through the flue gas pipeline body is installed with a flange on its outer wall. The sampling pipe is connected to a sampling tank through the flange. A fixing plate is installed on the outer wall of one side of the sampling pipe. The second connection cover is installed on the inner wall of the first connection cover. The second connection cover is located inside the sampling pipe. By setting the sampling tank, the first connection cover and the second connection cover, the effect of facilitating the sampling of flue gas is achieved, the dust content in the sample is reduced, which is beneficial to subsequent measurement, the cleanliness of the filter is ensured, and the smoothness of the flue gas entering the sampling pipe is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas measurement, and specifically to a device and a measurement method for measuring the oxygen content in boiler flue gas. Background Art

[0002] A boiler is an energy conversion device. The energy input into the boiler includes the chemical energy in fuel and electric energy. The boiler outputs steam, high-temperature water or organic heat carriers with a certain amount of heat energy. The original meaning of "pot" refers to a water container heated over fire, and "furnace" refers to a place where fuel is burned. A boiler includes two main parts: the pot and the furnace. The hot water or steam generated in the boiler can directly provide the required heat energy for industrial production and people's livelihood, or can be converted into mechanical energy through a steam power device, or further converted into electrical energy through a generator. In the production process of power plant boilers, the oxygen content in flue gas reflects the quality of the combustion process and is a very important detection content. The prior art measures the oxygen content in flue gas by using zirconia or a gas analyzer for detection. A gas analyzer is a process analysis instrument for measuring gas components. Commonly used ones include thermal conductivity gas analyzers, electrochemistry gas analyzers, and infrared absorption analyzers, etc.

[0003] After retrieval, the patent publication number CN114627428A discloses a method for indirectly measuring the oxygen content in flue gas, specifically related to a method for measuring the oxygen content in the tail flue gas during the operation of a circulating fluidized bed boiler, belonging to the field of boiler detection and combustion control in thermal power plants. The factors affecting the oxygen content in flue gas include: boiler load, main steam flow rate, main steam pressure, main steam temperature, feed water flow rate, reheated steam temperature, reheated steam pressure, total air volume, total secondary air volume, total fuel volume, a total of 10 parameters. Wavelet transform is used to process the 10 parameters; a correlation coefficient matrix of the above 10 parameters and the oxygen content in flue gas is established. After eliminating the data with relatively small correlation with the oxygen content in flue gas, it is determined that the number of principal components to be extracted is 5, which are boiler load, main steam flow rate, feed water flow rate, total air volume, and total secondary air volume; the 5 extracted principal components are used as the input variables of a BP neural network to establish a model for the oxygen content in flue gas. The present invention realizes the indirect measurement of the oxygen content in flue gas.

[0004] When using a gas analyzer for measurement in the prior art, it is necessary to first sample the flue gas inside the flue gas pipeline. The existing sampling pipe structure is relatively simple, the dust content in the obtained sample is relatively high, which is not conducive to subsequent measurement, and the sampling pipe is easily adhered by foreign objects and blocked, affecting the sampling fluency. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and a measurement method for measuring the oxygen content in boiler flue gas to solve the problems raised in the above background art.

[0006] To achieve the above object, the present invention provides the following technical solution: A device for measuring the oxygen content in boiler flue gas, comprising a main body of a flue gas pipeline, a flange, a first connecting cover, a sampling pipe, a sampling tank and a second connecting cover. One side of the inner wall of the main body of the flue gas pipeline is inserted and installed with a sampling pipe. The inner wall of the sampling pipe is provided with a filter screen distributed in a rectangular array. One end of the sampling pipe passing through the main body of the flue gas pipeline is externally installed with a flange. The sampling pipe is connected to a sampling tank through the flange. One side outer wall of the sampling pipe is installed with a fixing plate. One side of the inner wall of the fixing plate is installed with a support frame. A screw hole is opened inside the support frame. The outer wall of the sampling pipe is provided with a first connecting cover. The second connecting cover is installed inside the inner wall of the first connecting cover. The second connecting cover is located inside the sampling pipe.

[0007] When using a device for measuring the oxygen content in boiler flue gas and its measuring method in this technical solution, the motor body drives the screw rod to rotate, which can drive the first connecting cover to move horizontally outside the sampling pipe, thereby exposing the filter screen, enabling the flue gas inside the main body of the flue gas pipeline to pass through the filter screen and enter the inside of the sampling pipe. Then, when the first connecting cover and the second connecting cover come into contact with the fixing plate, the filter screen can be blocked, ensuring the relative sealing inside the sampling pipe. The flushing liquid enters the inside of the first connecting cover through the water inlet pipe after being pressurized by the water pump, thereby flushing the filter screen and ensuring the cleanliness of the filter screen. After the flushing liquid flushes the filter screen, it enters the space between the sampling pipe and the second connecting cover, and then is discharged through the water outlet pipe, achieving the purpose of circulating flushing the filter screen with the flushing liquid. Moreover, after the flushing liquid exchanges heat through the second connecting cover, it can cool the flue gas inside the sampling pipe. The extraction device discharges the air inside the sampling tank through the air extraction pipe, making the inside of the sampling tank in a negative pressure state. The solenoid valve is opened, enabling the flue gas inside the sampling pipe to enter the inside of the sampling tank. Then, the solenoid valve resets, and the flue gas collected inside the sampling tank can be discharged through the exhaust pipe, so as to be measured by an external gas analyzer.

[0008] Preferably, a solenoid valve is provided on one side outer wall of the sampling tank, and the solenoid valve can control the sampling tank to be connected to the inside of the sampling pipe in a controlled manner;

[0009] One side outer wall of the sampling tank is inserted and installed with an air extraction pipe, and the air extraction pipe is connected to an external air extraction device. The extraction device discharges the air inside the sampling tank through the air extraction pipe, making the inside of the sampling tank in a negative pressure state, thereby reducing the air content inside the sampling tank and reducing the influence on the sample;

[0010] One side outer wall of the sampling tank away from the suction pipe is inserted and installed with an exhaust pipe. The flue gas collected inside the sampling tank can be discharged through the exhaust pipe, and then measured by an external gas analyzer. It should be noted that according to the extracted flue gas and the gas analyzer, it operates according to the set measurement rules. The set operation rules can be selected with reference to the prior art or set according to the actual operation conditions, which is not the improvement of this application and will not be repeated here;

[0011] Valves are provided on one side outer walls of both the suction pipe and the exhaust pipe. The valves can ensure the controlled connection of the suction pipe and the exhaust pipe.

[0012] Preferably, a motor body is installed on one side inner wall of the first connection cover. The motor body is located inside the second connection cover. The outer wall of the first connection cover is wrapped with a heat insulation layer, which can ensure the heat insulation ability of the first connection cover and ensure that the motor body is at the required working temperature;

[0013] A screw rod is provided on one side outer wall of the motor body. The screw rod meshes inside the threaded hole. The motor body drives the screw rod to rotate, which can drive the first connection cover to move horizontally outside the sampling pipe until the first connection cover and the second connection cover contact the fixing plate, which can block the filter screen and protect the filter screen.

[0014] Preferably, first sealing gaskets are fixedly attached to one side outer walls of both the first connection cover and the second connection cover. The first sealing gaskets contact the fixing plate, which can ensure the sealing performance between the first connection cover and the second connection cover and the fixing plate respectively;

[0015] Baffles are installed on one side outer wall of the second connection cover and one side inner wall of the sampling pipe respectively. Second sealing gaskets are fixedly attached to the opposite side outer walls of the two baffles. The second sealing gaskets can ensure the sealing performance between the baffles, prevent the flue gas from directly entering the inside of the sampling pipe, force the flue gas to enter the sampling pipe after being filtered by the filter screen, and can filter the dust in the flue gas to improve the cleanliness of the flue gas.

[0016] Preferably, a water inlet pipe is inserted and installed on one side outer wall of the fixing plate. The water inlet pipe is located between the sampling pipe and the first connection cover. The water inlet pipe is connected to an external water pump. The flushing liquid enters the inside of the first connection cover through the water inlet pipe after being pressurized by the water pump, so as to flush the filter screen and ensure the cleanliness of the filter screen;

[0017] On the outer wall of the fixed plate on the side away from the water inlet pipe, a water outlet pipe is inserted and installed. The water outlet pipe is located between the sampling pipe and the second connection cover. After the flushing liquid flushes the filter screen, it enters the space between the sampling pipe and the second connection cover, and then is discharged through the water outlet pipe, achieving the purpose of circulating flushing the filter screen with the flushing liquid. Moreover, after the flushing liquid exchanges heat through the second connection cover, it can cool the flue gas inside the sampling pipe, thereby facilitating the collection of flue gas, avoiding causing the sampling tank to heat up, and facilitating the staff to take the sampling tank.

[0018] Preferably, a measurement method for a boiler flue gas oxygen content measurement device includes the following steps:

[0019] Step 1: The motor body drives the screw rod to rotate, which can drive the first connection cover to move horizontally outside the sampling pipe, thereby exposing the filter screen, enabling the flue gas inside the flue gas pipeline body to pass through the filter screen and enter the sampling pipe.

[0020] Step 2: The motor body makes the first connection cover and the second connection cover contact the fixed plate, which can block the filter screen and ensure the relative sealing inside the sampling pipe.

[0021] Step 3: The flushing liquid is pressurized by a water pump and enters the first connection cover through the water inlet pipe, thereby flushing the filter screen and ensuring the cleanliness of the filter screen.

[0022] Step 4: After the flushing liquid flushes the filter screen, it enters the space between the sampling pipe and the second connection cover, and then is discharged through the water outlet pipe, achieving the purpose of circulating flushing the filter screen with the flushing liquid. Moreover, after the flushing liquid exchanges heat through the second connection cover, it can cool the flue gas inside the sampling pipe.

[0023] Step 5: The extraction device discharges the air inside the sampling tank through the extraction pipe, making the inside of the sampling tank in a negative pressure state. The solenoid valve is opened, enabling the flue gas inside the sampling pipe to enter the sampling tank. Then the solenoid valve resets, and the flue gas collected inside the sampling tank can be discharged through the exhaust pipe, and then measured by an external gas analyzer.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: By providing a sampling tank, a first connection cover and a second connection cover, the present invention achieves the effect of facilitating the sampling of flue gas. The motor body drives the screw rod to rotate, which can drive the first connection cover to move horizontally outside the sampling pipe until the first connection cover and the second connection cover come into contact with the fixing plate, which can block the filter screen and protect the filter screen. The second gasket can ensure the sealing between the baffles, prevent flue gas from directly entering the sampling pipe, force the flue gas to enter the sampling pipe after being filtered by the filter screen, filter the dust in the flue gas, improve the cleanliness of the flue gas, reduce the dust content in the sample, and facilitate subsequent measurement. The flushing liquid is pressurized by a water pump and enters the first connection cover through the water inlet pipe, thereby flushing the filter screen, ensuring the cleanliness of the filter screen and the smooth flow of flue gas into the sampling pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a partial sectional view of the structure of the flue gas pipe body of the present invention;

[0026] Figure 2 is an enlarged schematic view of the structure of the sampling tank of the present invention;

[0027] Figure 3 is an enlarged schematic view of the structure of the first connection cover of the present invention;

[0028] Figure 4 is a partial enlarged schematic view of the structure of the sampling pipe of the present invention;

[0029] Figure 5 is of the present invention Figure 3 partial enlarged schematic view of the structure of the second connection cover in.

[0030] In the figure: 1. Flue gas pipe body; 11. Sampling pipe; 12. Fixing plate; 13. Water inlet pipe; 14. Water outlet pipe; 15. Support frame; 16. Screw hole; 17. Filter screen; 2. Flange; 21. Sampling tank; 22. Solenoid valve; 23. Suction pipe; 24. Exhaust pipe; 25. Valve; 3. First connection cover; 31. Second connection cover; 32. Motor body; 33. Screw rod; 34. First gasket; 35. Baffle; 36. Second gasket. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "equipped with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Please refer to Figures 1 to 5 , the three embodiments provided by the present invention:

[0035] Embodiment 1: A device for measuring the oxygen content in boiler flue gas and its measuring method, including a flue gas pipe body 1, a flange 2, a first connecting cover 3, a sampling pipe 11, a sampling tank 21 and a second connecting cover 31. One side of the inner wall of the flue gas pipe body 1 is inserted and installed with the sampling pipe 11. The inner wall of the sampling pipe 11 is provided with a filter screen 17 distributed in a rectangular array. According to the appendix Figure 4 It can be seen that the filter screen 17 is located between the fixing plate 12 and the baffle 35, and the filter screen 17 is located inside the sampling pipe 11. One end of the sampling pipe 11 passing through the flue gas pipe body 1 is externally installed with a flange 2. The sampling pipe 11 is connected to the sampling tank 21 through the flange 2. One side outer wall of the sampling pipe 11 is installed with a fixing plate 12. One side of the inner wall of the fixing plate 12 is installed with a support frame 15. A screw hole 16 is opened inside the support frame 15. The outer wall of the sampling pipe 11 is provided with a first connecting cover 3. The inner wall of the first connecting cover 3 is installed with a second connecting cover 31. The second connecting cover 31 is located inside the sampling pipe 11.

[0036] On one side of the inner wall of the first connecting cover 3, a motor body 32 is installed. As is well known to those skilled in the art, the measuring device of the present invention also needs to provide the motor body 32 to enable it to work properly. And as is well known to those skilled in the art, the provision of the motor body 32 is common, and they all belong to conventional means or common knowledge, so it will not be elaborated here. Those skilled in the art can make any selection according to their needs or convenience. The motor body 32 is located inside the second connecting cover 31. The outer wall of the first connecting cover 3 is wrapped with a heat insulation layer, which can ensure the heat insulation ability of the first connecting cover 3 and ensure that the motor body 32 is at the required working temperature;

[0037] On one side of the outer wall of the motor body 32, a screw rod 33 is provided. The screw rod 33 meshes inside the screw hole 16. The motor body 32 drives the screw rod 33 to rotate, which can drive the first connecting cover 3 to move horizontally outside the sampling pipe 11 until the first connecting cover 3 and the second connecting cover 31 come into contact with the fixing plate 12, which can block the filter screen 17 and protect the filter screen 17. The motor body 32 drives the screw rod 33 to rotate, which can drive the first connecting cover 3 to move horizontally outside the sampling pipe 11, thereby exposing the filter screen 17, enabling the flue gas in the flue gas pipeline body 1 to pass through the filter screen 17 and then enter the sampling pipe. After that, the first connecting cover 3 and the second connecting cover 31 come into contact with the fixing plate 12, which can block the filter screen 17 and ensure the relative sealing inside the sampling pipe 11.

[0038] On one side of the outer walls of the first connecting cover 3 and the second connecting cover 31, a first sealing gasket 34 is fixedly attached. The first sealing gasket 34 is in contact with the fixing plate 12, which can ensure the sealing between the first connecting cover 3 and the second connecting cover 31 and the fixing plate 12 respectively;

[0039] On one side of the outer wall of the second connecting cover 31 and one side of the inner wall of the sampling pipe 11, baffles 35 are installed. On the opposite side outer walls of the two baffles 35, second sealing gaskets 36 are fixedly attached. The second sealing gaskets 36 can ensure the sealing between the baffles 35, prevent the flue gas from directly entering the sampling pipe 11, force the flue gas to pass through the filter screen 17 and then enter the sampling pipe 11, which can filter the dust in the flue gas and improve the cleanliness of the flue gas.

[0040] Embodiment 2: A device for measuring the oxygen content in boiler flue gas and its measuring method, including a main flue gas pipe body 1, a flange 2, a first connecting cover 3, a sampling pipe 11, a sampling tank 21 and a second connecting cover 31. One side of the inner wall of the main flue gas pipe body 1 is inserted and installed with a sampling pipe 11. The inner wall of the sampling pipe 11 is provided with filters 17 distributed in a rectangular array. One end of the sampling pipe 11 passing through the main flue gas pipe body 1 is externally installed with a flange 2. The sampling pipe 11 is connected to a sampling tank 21 through the flange 2. One side outer wall of the sampling pipe 11 is installed with a fixing plate 12. One side of the inner wall of the fixing plate 12 is installed with a support frame 15. A screw hole 16 is opened inside the support frame 15. The outer wall of the sampling pipe 11 is provided with a first connecting cover 3. The inner wall of the first connecting cover 3 is installed with a second connecting cover 31. The second connecting cover 31 is located inside the sampling pipe 11.

[0041] One side of the inner wall of the first connecting cover 3 is installed with a motor body 32. The motor body 32 is located inside the second connecting cover 31. The outer wall of the first connecting cover 3 is wrapped with a heat insulation layer, which can ensure the heat insulation ability of the first connecting cover 3 and ensure that the motor body 32 is at the required working temperature.

[0042] One side of the outer wall of the motor body 32 is provided with a screw rod 33. The screw rod 33 meshes inside the screw hole 16. The motor body 32 drives the screw rod 33 to rotate, which can drive the first connecting cover 3 to move horizontally outside the sampling pipe 11 until the first connecting cover 3 and the second connecting cover 31 are in contact with the fixing plate 12, which can block the filter 17 and protect the filter 17.

[0043] Both the first connecting cover 3 and the second connecting cover 31 are fixedly attached with a first sealing gasket 34 on one side of their outer walls. The first sealing gasket 34 is in contact with the fixing plate 12, which can ensure the sealing performance between the first connecting cover 3 and the second connecting cover 31 and the fixing plate 12 respectively.

[0044] One side of the outer wall of the second connecting cover 31 and one side of the inner wall of the sampling pipe 11 are both installed with baffles 35. Both sides of the outer walls of the two baffles 35 facing each other are fixedly attached with a second sealing gasket 36. The second sealing gasket 36 can ensure the sealing performance between the baffles 35, prevent flue gas from directly entering the inside of the sampling pipe 11, force the flue gas to enter the sampling pipe 11 after being filtered by the filter 17, and can filter the dust in the flue gas to improve the cleanliness of the flue gas.

[0045] One side of the outer wall of the fixing plate 12 is inserted and installed with a water inlet pipe 13. The water inlet pipe 13 is located between the sampling pipe 11 and the first connecting cover 3. The water inlet pipe 13 is connected to an external water pump. The flushing liquid enters the inside of the first connecting cover 3 through the water inlet pipe 13 after being pressurized by the water pump, thereby flushing the filter 17 and ensuring the cleanliness of the filter 17.

[0046] An outlet pipe 14 is installed on the outer wall of the fixing plate 12 on the side away from the water inlet pipe 13. The outlet pipe 14 is located between the sampling tube 11 and the second connecting cover 31. After the flushing liquid flushes the filter 17, it enters between the sampling tube 11 and the second connecting cover 31, and is then discharged through the outlet pipe 14, thereby achieving the purpose of circulating flushing of the filter 17 by the flushing liquid. After the flushing liquid is heat-exchanged through the second connecting cover 31, it can cool down the flue gas inside the sampling tube 11, thereby facilitating the collection of the flue gas, avoiding the sampling tank 21 from heating up, and facilitating the staff to take the sampling tank 21.

[0047] Embodiment 3: A device for measuring oxygen content in boiler flue gas and a measuring method thereof, comprising a flue gas duct body 1, a flange 2, a first connecting cover 3, a sampling tube 11, a sampling tank 21 and a second connecting cover 31. The sampling tube 11 is plugged and installed on one side of the inner wall of the flue gas duct body 1, and a filter screen 17 distributed in a rectangular array is arranged on the inner wall of the sampling tube 11. The sampling tube 11 passes through the outer wall of one end of the flue gas duct body 1 and a flange 2 is installed. The sampling tube 11 is connected to the sampling tank 21 through the flange 2. A fixing plate 12 is installed on the outer wall of one side of the sampling tube 11, and a support frame 15 is installed on one side of the inner wall of the fixing plate 12. A screw hole 16 is opened inside the support frame 15. A first connecting cover 3 is arranged on the outer wall of the sampling tube 11, and a second connecting cover 31 is installed on the inner wall of the first connecting cover 3. The second connecting cover 31 is located inside the sampling tube 11.

[0048] An electromagnetic valve 22 is disposed on the outer wall of one side of the sampling tank 21, and the electromagnetic valve 22 can control the sampling tank 21 to be connected to the inside of the sampling tube 11;

[0049] An exhaust pipe 23 is installed on the outer wall of one side of the sampling tank 21. The exhaust pipe 23 is connected to an external exhaust device. The exhaust device exhausts the air inside the sampling tank 21 through the exhaust pipe 23, so that the inside of the sampling tank 21 is in a negative pressure state, thereby reducing the air content inside the sampling tank 21 and reducing the impact on the sample;

[0050] An exhaust pipe 24 is installed on the outer wall of the sampling tank 21 away from the exhaust pipe 23. The flue gas collected inside the sampling tank 21 can be discharged through the exhaust pipe 24, so as to be measured by an external gas analyzer. It should be noted that according to the extracted flue gas and the gas analyzer, the set measurement rules are used for operation, wherein the set operation rules can be selected with reference to the prior art, or can be selected and set according to the actual operation situation, which is not the improvement of the present application and will not be repeated here;

[0051] A valve 25 is disposed on the outer wall of one side of the air extraction pipe 23 and the exhaust pipe 24 , and the valve 25 can ensure that the air extraction pipe 23 and the exhaust pipe 24 are connected in a controlled manner.

[0052] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A boiler flue gas oxygen content measuring device, comprising a flue gas duct body (1), a flange (2), a first connecting cover (3), a sampling tube (11), a sampling tank (21) and a second connecting cover (31), Features: A sampling tube (11) is inserted and installed on one side of the inner wall of the flue gas duct body (1), and a filter screen (17) distributed in a rectangular array is arranged on the inner wall of the sampling tube (11). The sampling tube (11) passes through the outer wall of one end of the flue gas duct body (1), and a flange (2) is installed. The sampling tube (11) is connected to a sampling tank (21) through the flange (2). A fixing plate (12) is installed on the outer wall of one side of the sampling tube (11), and a support frame (15) is installed on one side of the inner wall of the fixing plate (12). A screw hole (16) is opened inside the support frame (15). A first connecting cover (3) is arranged on the outer wall of the sampling tube (11), and a second connecting cover (31) is installed on the inner wall of the first connecting cover (3). The second connecting cover (31) is located at the sampling tube (11). Inside the sample tube (11), a motor body (32) is installed on one side of the inner wall of the first connecting cover (3), and the motor body (32) is located inside the second connecting cover (31). The outer wall of the first connecting cover (3) is wrapped with a heat insulation layer, which can ensure the heat insulation capacity of the first connecting cover (3) and can ensure that the motor body (32) is at a required working temperature. A screw (33) is arranged on the outer wall of one side of the motor body (32), and the screw (33) is engaged with the inside of the screw hole (16). The motor body (32) drives the screw (33) to rotate, which can drive the first connecting cover (3) to move horizontally outside the sampling tube (11) until the first connecting cover (3) and the second connecting cover (31) are in contact with the fixing plate (12), so as to The filter screen (17) is shielded to protect the filter screen (17); the first connection cover (3) and the second connection cover (31) are both fitted and fixed with a first sealing gasket (34) on one side of the outer wall; the first sealing gasket (34) is in contact with the fixing plate (12) to ensure the sealing between the first connection cover (3) and the second connection cover (31) and the fixing plate (12) respectively; a baffle (35) is installed on one side of the outer wall of the second connection cover (31) and one side of the inner wall of the sampling tube (11); the outer walls of the two baffles (35) on the opposite side are both fitted and fixed with a second sealing gasket (36); the second sealing gasket (36) can ensure the sealing between the baffles (35) to prevent smoke from directly entering the interior of the sampling tube (11), forcing the smoke to enter the sampling tube (11). The smoke enters the sampling tube (11) after being filtered through the filter screen (17), so that dust in the smoke can be filtered to improve the cleanliness of the smoke. A water inlet pipe (13) is installed on the outer wall of one side of the fixed plate (12), and the water inlet pipe (13) is located between the sampling tube (11) and the first connecting cover (3). The water inlet pipe (13) is connected to an external water pump. The flushing liquid is pressurized by the water pump and enters the first connecting cover (3) through the water inlet pipe (13), so as to flush the filter screen (17) and ensure the cleanliness of the filter screen (17). A water outlet pipe (14) is installed on the outer wall of the fixed plate (12) on the side away from the water inlet pipe (13), and the water outlet pipe (14) is located between the sampling tube (11) and the second connecting cover (31).After the flushing liquid flushes the filter screen (17), it enters between the sampling pipe (11) and the second connecting cover (31), and then is discharged through the water outlet pipe (14), achieving the purpose of circulating flushing the filter screen (17) with the flushing liquid. Moreover, after the flushing liquid exchanges heat through the second connecting cover (31), it can cool the flue gas inside the sampling pipe (11), thus facilitating the collection of the flue gas, avoiding causing the sampling tank (21) to heat up, and facilitating the staff to take the sampling tank (21).

2. A boiler flue gas oxygen content measuring device according to claim 1, Features: An electromagnetic valve (22) is provided on an outer wall of one side of the sampling tank (21), and the electromagnetic valve (22) can control the sampling tank (21) to be connected to the inside of the sampling tube (11); An exhaust pipe (23) is plugged and installed on the outer wall of one side of the sampling tank (21), and the exhaust pipe (23) is connected to an external exhaust device. The exhaust device exhausts the air inside the sampling tank (21) through the exhaust pipe (23), so that the inside of the sampling tank (21) is in a negative pressure state, thereby reducing the air content inside the sampling tank (21) and reducing the impact on the sample; An exhaust pipe (24) is plugged and installed on the outer wall of the sampling tank (21) on the side facing away from the exhaust pipe (23), and the smoke collected inside the sampling tank (21) can be discharged through the exhaust pipe (24), so as to be measured by an external gas analyzer; The outer walls of one side of the air extraction pipe (23) and the exhaust pipe (24) are both provided with valves (25), and the valves (25) can ensure that the air extraction pipe (23) and the exhaust pipe (24) are in controlled communication.

3. A method for measuring oxygen content in boiler flue gas according to claim 2, Features: The steps include: Step 1: The motor body (32) drives the screw rod (33) to rotate, which can drive the first connection cover (3) to move horizontally outside the sampling tube (11), thereby exposing the filter screen (17), so that the smoke inside the smoke duct body (1) passes through the filter screen (17) and enters the sampling tube (11); Step 2: The motor body (32) makes the first connection cover (3) and the second connection cover (31) contact the fixed plate (12), so as to shield the filter screen (17) and ensure the sealing of the interior of the sampling tube (11); Step 3: The flushing liquid is pressurized by a water pump and enters the first connection cover (3) through the water inlet pipe (13), thereby flushing the filter screen (17) to ensure the cleanliness of the filter screen (17); Step 4: After the flushing liquid flushes the filter screen (17), it enters between the sampling tube (11) and the second connecting cover (31), and then is discharged through the outlet pipe (14), thereby achieving the purpose of circulating the flushing liquid on the filter screen (17), and after the flushing liquid exchanges heat through the second connecting cover (31), it can cool the flue gas inside the sampling tube (11); Step 5: The extraction device exhausts the air inside the sampling tank (21) through the exhaust pipe (23), so that the inside of the sampling tank (21) is in a negative pressure state, and the solenoid valve (22) is opened to allow the smoke inside the sampling tube (11) to enter the inside of the sampling tank (21). After that, the solenoid valve (22) is reset, and the smoke collected inside the sampling tank (21) can be discharged through the exhaust pipe (24), so as to be measured by an external gas analyzer.

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