Flue gas sampling anti-crystallization system

Abstract

According to the flue gas sampling anti-crystallization system provided by the utility model, air is reversely blown to the sampling probe and the sampling pipeline through the reverse blowing device, so that ammonium salt crystals and dust impurities in the sampling probe and the sampling pipeline are eliminated; the temperature control device wraps the outer surface of the sampling pipeline to heat and preserve heat of the sampling pipeline, so that generation of ammonium salt crystals is reduced or inhibited; the phosphoric acid titration device is connected with an internal pipeline of the gas analyzer, so that ammonium salt crystals in the internal pipeline are dissolved and discharged. A user can flexibly select any one device or a combination mode of several devices to form the flue gas sampling anti-crystallization system according to actual conditions, so that the requirements of various complicated application scenes are met to prevent crystal substances from being generated during sampling. When the three components are selected to be combined, through the synergistic effect of the three components, the relatively low ammonium salt crystallization amount in the pipeline is effectively ensured, and the accuracy and reliability of the flue gas sampling device during flue gas collection are ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to flue gas treatment technical field especially is related to a flue gas sampling anti crystallization system. BACKGROUND

[0002] The flue gas in the boiler of the thermal power plant contains many gas impurities, is a mixture of gas and smoke dust, has complex components, contains gas impurities such as water vapor, sulfur dioxide, nitrogen, oxygen, carbon monoxide, carbon dioxide, hydrocarbon, nitrogen oxide and smoke dust such as fuel ash, coal particles, oil droplets, high-temperature cracking product, with the strictness of environmental protection emission requirement, the content detection of each component has important significance to green economic development and the operation capacity of the boiler of the thermal power plant.At present, the on-line flue gas analysis system is mature in design, is widely used in various types of boilers, but the application scene in the circulating fluidized bed boiler is very limited.The reason is that most on-line flue gas analysis systems use cold dry method to measure various components in the flue gas at the chimney inlet, and most circulating fluidized bed boilers use selective non-catalytic reduction (SNCR) process in operation, which makes the dust content in the flue gas at the outlet area of the circulating fluidized bed boiler high and the ammonia escape more.Therefore, in the process of extracting the flue gas sample by using the cold dry method, the high ammonia escape of the circulating fluidized bed boiler can easily lead to the generation of more ammonium salt crystalline, and a small amount of crystalline in the initial sampling period can cause the increase of pipeline resistance, and the gradual accumulation of crystalline after a period of sampling can block the sampling pipeline, so that the target flue gas cannot be collected, which not only affects the stability of the sampling process, but also affects the accuracy of the measurement result. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a flue gas sampling anti crystallization system, which solves the problem that the existing on-line flue gas analysis system is easy to generate ammonium salt crystalline when collecting the flue gas of the circulating fluidized bed boiler for a long period, affecting the stability of sampling and the accuracy of measurement result analysis.

[0004] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0005] A flue gas sampling anti crystallization system is applied to a circulating fluidized bed boiler flue gas sampling device, the flue gas sampling device includes a sampling probe, a sampling pipeline and a gas analyzer, the sampling probe is communicated with a flue gas pipeline, the sampling pipeline is connected between the internal pipeline of the sampling probe and the gas analyzer;

[0006] The flue gas sampling anti crystallization system includes a back blowing device, the back blowing device is communicated with the sampling probe and the outlet end of the sampling pipeline, and is used for reverse blowing of the sampling probe and the sampling pipeline;And / or

[0007] The flue gas sampling anti-crystallization system comprises a temperature control device wrapped on the outer surface of the sampling pipeline for heating and heat preservation of the sampling pipeline; and / or

[0008] The flue gas sampling anti-crystallization system comprises a phosphoric acid titration device connected with the internal pipeline for dissolving and discharging the crystallization in the internal pipeline.

[0009] Further, the back-blowing device comprises a back-blowing unit, a front-blowing unit and a compressed air providing unit.

[0010] The outlet end of the back-blowing unit is in communication with the outlet end of the sampling pipeline, and the gas flow direction of the back-blowing unit is from the outlet end of the sampling pipeline to the sampling probe.

[0011] The outlet end of the front-blowing unit is in communication with the outlet end of the sampling probe, and the gas flow direction of the front-blowing unit is from the outlet end of the sampling probe to the flue gas pipeline.

[0012] The compressed air providing unit is connected with the inlet end of the back-blowing unit and the inlet end of the front-blowing unit.

[0013] Further, the front-blowing unit comprises a front outer-blowing pipeline, a front inner-blowing pipeline and a mixing pipeline.

[0014] The outlet end of the front outer-blowing pipeline is in communication with the outlet end of the cavity between the outer wall of the internal filter element of the sampling probe and the inner wall of the sampling probe, and the gas flow direction of the front outer-blowing pipeline is from the outlet end of the cavity to the flue gas pipeline.

[0015] The front outer-blowing pipeline is provided with a front outer-blowing electromagnetic valve.

[0016] The outlet end of the front inner-blowing pipeline is in communication with the outlet end of the internal filter element of the sampling probe, and the gas flow direction of the front inner-blowing pipeline is from the outlet end of the filter element to the flue gas pipeline.

[0017] The front inner-blowing pipeline is provided with a front inner-blowing electromagnetic valve.

[0018] The gas inlet ends of the front outer-blowing pipeline and the front inner-blowing pipeline are in communication and connected with the gas outlet end of the mixing pipeline, and the gas inlet end of the mixing pipeline is in communication with the compressed air providing unit.

[0019] Further, the back-blowing unit comprises a back-blowing pipeline.

[0020] The back-blowing pipeline is internally provided with a back-blowing electromagnetic valve.

[0021] Further, the compressed air providing unit comprises a front back-blowing part and a rear back-blowing part; the front back-blowing part is communicated with the inlet end of the front back-blowing unit, and the front back-blowing part comprises a first gas storage tank and a first gas inlet three-way joint;

[0022] The rear back-blowing part is communicated with the inlet end of the rear back-blowing unit, and the rear back-blowing part comprises a second gas storage tank and a second gas inlet three-way joint.

[0023] Further, the back-blowing device further comprises a pneumatic control pipeline, one end of the pneumatic control pipeline is communicated with the first gas storage tank, and one end of the pneumatic control pipeline is communicated with the inlet end of the sampling pipeline through a sampling control electromagnetic valve;

[0024] The sampling control electromagnetic valve is used for communicating or cutting off the gas path communication of the sampling pipeline.

[0025] Further, the temperature control device is an electric heating tape.

[0026] Further, the phosphoric acid titration device comprises an acid conveying pipeline, an acid adding pump and an acid storage tank, the acid adding pump is arranged on the internal pipeline, the acid storage tank is arranged outside the gas analysis instrument, the inlet end of the acid conveying pipeline is communicated with the acid storage tank, and the outlet end of the acid conveying pipeline is communicated with the acid adding pump.

[0027] Further, the phosphoric acid titration device further comprises a peristaltic pump, and the peristaltic pump is arranged on the internal pipeline.

[0028] Compared with the prior art, the smoke sampling anti-crystallization system has the following beneficial effects: the back-blowing device is used for back-blowing the sampling probe and the sampling pipeline, the ammonium salt crystalline substances and dust impurities in the sampling probe and the sampling pipeline are eliminated, and the sampling channel is ensured to be unblocked; the temperature control device is wrapped on the outer surface of the sampling pipeline to heat and keep warm the sampling pipeline, so that the temperature of the collected flue gas is always maintained in a suitable range when the flue gas passes through the sampling pipeline, and the generation of ammonium salt crystalline substances is reduced or inhibited; the internal pipeline of the gas analysis instrument is connected with the phosphoric acid titration device, and the ammonium salt crystalline substances in the internal pipeline are dissolved and discharged. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 The structural diagram of the flue gas anti-crystallization system provided in an embodiment of the present application.

[0031] Explanation of reference signs:

[0032] 1, sampling probe; 11, filter element;

[0033] 2, sampling pipeline;

[0034] 3, gas analyzer; 31, internal pipeline;

[0035] 4, back flushing device; 41, back flushing unit; 411, back flushing pipeline; 412, back flushing solenoid valve; 42, front flushing unit; 421, front outer flushing pipeline; 422, front inner flushing pipeline; 423, mixing pipeline; 424, front outer flushing solenoid valve; 425, front inner flushing solenoid valve; 43, compressed air providing unit; 431, first air storage tank; 432, first air inlet three-way joint; 433, second air storage tank; 44, pneumatic control pipeline; 441, sampling control solenoid valve;

[0036] 5, phosphoric acid titration device; 51, acid delivery pipeline; 52, acid feeding pump; 53, acid storage tank;

[0037] 6, flue gas pipeline. DETAILED DESCRIPTION

[0038] The technical solutions of the present application will be described clearly and completely in combination with the drawings. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0039] In the description of the utility model, it is necessary to explain, the term "center", "upper", "lower", "left", "right", "vertical", "horizontal", "internal", "external" and so on indicate the orientation or positional relationship is based on the orientation or positional relationship shown in the drawing, only for the convenience of describing the utility model and simplifying the description, and is not indicating or implying that the device or element indicated must have a particular orientation, a particular orientation structure and operation, therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0040] In the description of the utility model, it is necessary to explain, unless otherwise expressly provided and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, can also be detachable connection, or integrally connected, can be mechanical connection, can also be electrical connection, can be directly connected, can also be indirectly connected through the intermediate medium, can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0041] As shown in the accompanying Figure 1As shown, a flue gas sampling anti-crystallization system is applied to a circulating fluidized bed boiler flue gas sampling device. The flue gas sampling device includes a sampling probe 1, a sampling pipeline 2 and a gas analyzer 3. The sampling probe 1 is in communication with a flue gas pipeline 6. The sampling pipeline 2 is connected between the sampling probe 1 and an internal pipeline 31 of the gas analyzer 3. The flue gas sampling anti-crystallization system includes a back blowing device 4. The back blowing device 4 is in communication with the sampling probe 1 and an outlet end of the sampling pipeline 2. The back blowing device 4 is used to blow the sampling probe 1 and the sampling pipeline 2 in a reverse direction to blow away ammonium salt crystalline substances, dust and impurities and the like in the sampling pipeline 2 and the sampling probe 1. And / or, since the generation amount of the ammonium salt crystalline substances is largely dependent on the flue gas temperature, the flue gas sampling anti-crystallization system includes a temperature control device. The temperature control device is wrapped on an outer surface of the sampling pipeline 2. The temperature control device is used to heat and keep warm the sampling pipeline 2 to ensure that the flue gas temperature is always kept in a suitable range when the collected flue gas passes through the sampling pipeline 2, thereby reducing the generation amount of the ammonium salt crystalline substances. And / or, the flue gas sampling anti-crystallization system includes a phosphoric acid titration device 5. The phosphoric acid titration device 5 is connected with the internal pipeline 31. The phosphoric acid titration device 5 is used to dissolve and discharge the residual ammonium salt crystalline substances in the internal pipeline 31. It is worth noting that the user can flexibly select any one device or a combination of several devices to constitute the flue gas sampling anti-crystallization system according to the actual situation to meet the needs of various complex application scenarios to prevent the generation of crystalline substances during sampling. The selection is not limited here. Most preferably, the back blowing device 4, the temperature control device and the phosphoric acid titration device 5 are selected in combination. Through the synergistic effect of the three, the lower amount of ammonium salt crystalline substances in the internal pipeline 31 of the sampling channel and the gas analyzer 3 is effectively ensured. The accuracy and reliability of the flue gas sampling device during flue gas collection are ensured. The service life of the equipment flue gas sampling device is effectively prolonged.

[0042] In some embodiments of the utility model, back flushing device 4 includes back flushing unit 41, front flushing unit 42 and compressed air providing unit 43. The outlet end of back flushing unit 41 is communicated with the outlet end of sampling pipeline 2, and back flushing unit 41 includes back flushing pipeline 411, and back flushing solenoid valve 412 is arranged in back flushing pipeline 411 to control the on-off of back flushing pipeline 411. When back flushing starts, back flushing function is first performed, back flushing solenoid valve 412 is opened, back flushing gas enters the outlet end of sampling pipeline 2 from back flushing pipeline 411 and flows to the direction of sampling probe 1 through the whole sampling pipeline 2, blows the ammonium salt crystals and impurities deposited in sampling pipeline 2 to the inside of sampling probe 1 and keeps the unobstructed of sampling pipeline 2, prevents sampling pipeline 2 from being blocked and further affects the normal flow of flue gas sampling. Further, when back flushing operation is completed, back flushing solenoid valve 412 is closed, back flushing function is stopped, front flushing function is started, the outlet end of front flushing unit 42 is communicated with the outlet end of sampling probe 1, back flushing gas enters the outlet end of sampling probe 1 from front flushing unit 42 and flows through the inside of sampling probe 1, blows the ammonium salt crystals and impurities adhered to sampling probe 1 into flue gas pipeline 6, keeps sampling probe 1 clean all the time, prevents sampling probe 1 from being blocked or abraded by ammonium salt crystals, and subsequent ammonium salt crystals and impurities can be discharged into the installed related waste collecting device along with the outlet gas of flue gas pipeline 6. In addition, compressed air providing unit 43 is connected with the inlet end of back flushing unit 41 and the inlet end of front flushing unit 42 to provide compressed air source for front flushing unit 42 and back flushing unit 41.

[0043] It is worth mentioning that the ammonium salt crystals will adhere to the inside wall of sampling probe 1 and sampling pipeline 2 once generated, and the longer the time, the more difficult to remove, so the sampling and back flushing functions should be alternately performed, that is, back flushing is needed regularly. Specifically, gas analyzer 3 stops sampling after sampling for a period of time, opens back flushing device 4 to clean sampling pipeline 2 using back flushing unit 41 and then clean sampling probe 1 using front flushing unit 42, stops back flushing after cleaning, starts the next round of sampling, and circulates repeatedly. Wherein, back flushing frequency and back flushing time are determined according to actual sampling situation, and are not limited here.

[0044] In some embodiments of the utility model, because the filter element 11 is arranged in the sampling probe 1 on the market, the cavity space is generally arranged between the outer part of filter element 11 and the wall of sampling probe 1, in order to better clean the sampling probe 1, the front back flushing unit 42 includes front outer back flushing pipeline 421, front inner back flushing pipeline 422 and mixed pipeline 423. The outlet end of front outer back flushing pipeline 421 is communicated with the cavity outlet end between the outer wall of internal filter element 11 of sampling probe 1 and the inner wall of sampling probe 1, and the gas of front outer back flushing pipeline 421 flows through the whole cavity from the cavity outlet end and flows to flue gas pipeline 6, and front outer back flushing pipeline 421 is provided with front outer back flushing solenoid valve 424 to control the on-off of front outer back flushing pipeline 421. The outlet end of front inner back flushing pipeline 422 is communicated with the outlet end of internal filter element 11 of sampling probe 1, and the gas flow direction of front inner back flushing pipeline 422 flows through the whole filter element 11 from the outlet end of filter element 11 and finally flows to flue gas pipeline 6 to ensure the filtering effect of filter element 11, and front inner back flushing pipeline 422 is provided with front inner back flushing solenoid valve 425 to control the on-off of front inner back flushing pipeline 422. In addition, the gas inlet ends of front outer back flushing pipeline 421 and front inner back flushing pipeline 422 are communicated and merged into the gas outlet end of mixed pipeline 423, and the gas inlet end of mixed pipeline 423 is communicated with compressed air providing unit 43.

[0045] Specifically, after the back flushing function of back flushing device 4 is completed, close back flushing unit 41, and front back flushing unit 42 starts to work. First, open front outer back flushing solenoid valve 424, and carry out front outer back flushing, which aims at blowing away the ammonium salt crystal and dust accumulated outside filter element 11 from back flushing unit, and after blowing away, close front outer back flushing solenoid valve 424 to stop air inlet, open front inner back flushing solenoid valve 425 to further remove the ammonium salt crystal and impurities in filter element 11, and finally, in order to prevent the residual ammonium salt crystal in the cavity during front inner back flushing operation, close front inner back flushing solenoid valve 425, reopen front outer back flushing solenoid valve 424, and carry out front outer back flushing step again to completely remove the residual ammonium salt crystal, dust and impurities in the cavity outside filter element 11.

[0046] In some embodiments of the utility model, compressed air providing unit 43 includes front back flushing part and back flushing part, the inlet end of front back flushing part is communicated with front back flushing unit 42, the front back flushing part includes first gas storage tank 431 and first air inlet three-way joint 432, when compressed air enters first gas storage tank 431 for storage, it needs to enter first air inlet three-way joint 432 for oil and water filtration first, to prevent the impurities in the compressed air from entering the filter element 11 of sampling probe 1 inside and outside during front back flushing. The inlet end of back flushing part is communicated with back flushing unit 41, and the back flushing part includes second gas storage tank 433 and second air inlet three-way joint (not marked in the figure), and similarly, when compressed air enters second gas storage tank 433 for storage, it needs to enter second air inlet three-way joint for oil and water filtration first, to prevent the impurities in the compressed air from entering the sampling pipeline 2 outside during back flushing.

[0047] In some embodiments of the present application, the back flushing device 4 further comprises a pneumatic control pipeline 44, one end of which is in communication with the first gas storage tank 431, and the other end is in communication with the inlet end of the sampling pipeline 2 through a sampling control electromagnetic valve 441; the sampling control electromagnetic valve 441 is used to communicate or cut off the gas path communication of the sampling pipeline 2. Specifically, the sampling control electromagnetic valve 441 is a pneumatic valve, which is in an open state when the flue gas sampling device is sampling, and the sampled flue gas can flow from the inside of the sampling probe 1 to the sampling pipeline 2 after flowing through the sampling control electromagnetic valve 441; when the back flushing work is performed, and further, when the front back flushing work is performed after the rear back flushing work is completed, since one end of the pneumatic control pipeline 44 is in communication with the first gas storage tank 431, the compressed air provided by the first gas storage tank 431 passes through the sampling control electromagnetic valve 441, and under the pressure of the compressed air, the sampling control electromagnetic valve 441 is automatically closed to cut off the flow passage of the compressed air to the sampling pipeline 2, so that the compressed air during the front inner back flushing or the front outer back flushing can only flow in the blowing direction of the flue gas pipeline 6, that is, to ensure that the sampling control electromagnetic valve 441 remains closed during the front back flushing, so that the compressed air acts on the sampling probe 1, which can prevent the compressed air from flowing into the sampling pipeline 2 and thus reducing the cleaning effect of the front back flushing on the inside of the sampling probe 1, and can also prevent the ammonium salt crystals and impurities such as dust from accidentally entering the sampling pipeline 2 during the front back flushing work.

[0048] In some embodiments of the present application, the temperature control device is an electric heating tape, which controls the whole heating and heat preservation of the sampling pipeline 2, so as to control the temperature of the flue gas in the sampling pipeline 2 in a temperature range in which crystallization is not easy, thereby effectively preventing the generation of ammonium salt crystals. The electric heating tape should be arranged to avoid U-shaped bending and cold end region as much as possible.

[0049] In some embodiments of the present application, the phosphoric acid titration device 5 comprises an acid conveying pipeline 51, an acid adding pump 52 and an acid storage tank 53, the acid adding pump 52 is arranged on the internal pipeline 31, the acid storage tank 53 is arranged outside the gas analysis instrument 3, the inlet end of the acid conveying pipeline 51 is in communication with the acid storage tank 53, and the outlet end of the acid conveying pipeline 51 is in communication with the acid adding pump 52, and the phosphoric acid in the acid storage tank 53 is pumped into the internal pipeline 31 by the acid adding pump 52 for quantitative addition. It is worth noting that when the flue gas sampling is stopped and switched to the back flushing function, the phosphoric acid titration device 5 needs to continue to operate to continuously remove the residual ammonium salt crystals in the internal pipeline 31. Among them, the related parameters of the phosphoric acid titration, such as the concentration of the phosphoric acid and the titration rate, need to be calculated and adjusted according to the generation of the ammonium salt crystals in the internal pipeline 31 of the sampling site gas analysis instrument 3, which is not limited herein.

[0050] In some embodiments of the utility model, in order to discharge the waste liquid and impurities generated after the phosphoric acid dissolves ammonium salt crystalline, the phosphoric acid titration device 5 further includes a peristaltic pump, which can be communicated with the internal pipeline 31 through a discharge pipeline or a hose to extract the waste liquid and impurities.

[0051] The above embodiment is only the preferred embodiment of the utility model, and cannot be used to limit the range of the utility model protection, and any non-substantial change and replacement made by the person skilled in the art on the basis of the utility model belongs to the range of the utility model protection.

Claims

1. A fume sampling anti-crystallization system, characterized by, The application is applied to a flue gas sampling device of a circulating fluidized bed boiler, and the flue gas sampling device comprises a sampling probe, a sampling pipeline and a gas analyzer, the sampling probe is communicated with a flue gas pipeline, and the sampling pipeline is connected between the sampling probe and an internal pipeline of the gas analyzer; The flue gas sampling anti-crystallization system comprises a back-blowing device which is communicated with the sampling probe and an outlet end of the sampling pipeline and is used for back-blowing the sampling probe and the sampling pipeline; And / or The flue gas sampling anti-crystallization system comprises a temperature control device which is wrapped on an outer surface of the sampling pipeline and is used for heating and heat preservation of the sampling pipeline; And / or The flue gas sampling anti-crystallization system comprises a phosphoric acid titration device which is connected with the internal pipeline and is used for dissolving and discharging the crystallization in the internal pipeline.

2. The anti-crystallization system for flue gas sampling of claim 1, wherein, The back-blowing device comprises a rear back-blowing unit, a front back-blowing unit and a compressed air providing unit; An outlet end of the rear back-blowing unit is communicated with an outlet end of the sampling pipeline, and a gas flow direction of the rear back-blowing unit is from the outlet end of the sampling pipeline to the sampling probe; An outlet end of the front back-blowing unit is communicated with an outlet end of the sampling probe, and a gas flow direction of the front back-blowing unit is from the outlet end of the sampling probe to the flue gas pipeline; The compressed air providing unit is connected with an inlet end of the rear back-blowing unit and an inlet end of the front back-blowing unit.

3. The anti-crystallization system for flue gas sampling of claim 2, wherein, The front back-blowing unit comprises a front outer back-blowing pipeline, a front inner back-blowing pipeline and a mixing pipeline; An outlet end of the front outer back-blowing pipeline is communicated with a cavity outlet end between an outer wall of an internal filter element of the sampling probe and an inner wall of the sampling probe, and a gas flow direction of the front outer back-blowing pipeline is from the cavity outlet end to the flue gas pipeline; The front outer back-blowing pipeline is provided with a front outer back-blowing electromagnetic valve; An outlet end of the front inner back-blowing pipeline is communicated with an outlet end of the internal filter element of the sampling probe, and a gas flow direction of the front inner back-blowing pipeline is from the outlet end of the filter element to the flue gas pipeline; The front inner back-blowing pipeline is provided with a front inner back-blowing electromagnetic valve; Air inlet ends of the front outer back-blowing pipeline and the front inner back-blowing pipeline are communicated and merged into an air outlet end of the mixing pipeline, and an air inlet end of the mixing pipeline is communicated with the compressed air providing unit.

4. The anti-crystallization system for flue gas sampling of claim 2, wherein, The rear back-blowing unit comprises a rear back-blowing pipeline; The rear back-blowing pipeline is internally provided with a rear back-blowing electromagnetic valve.

5. The anti-crystallization system for flue gas sampling of claim 2, wherein, The compressed air providing unit comprises a front back-blowing part and a rear back-blowing part; the front back-blowing part is communicated with an inlet end of the front back-blowing unit, and the front back-blowing part comprises a first gas storage tank and a first air inlet three-way joint; The rear back-blowing part is communicated with an inlet end of the rear back-blowing unit, and the rear back-blowing part comprises a second gas storage tank and a second air inlet three-way joint.

6. The anti-crystallization system for flue gas sampling of claim 5, wherein, The back-blowing device further comprises a pneumatic control pipeline, one end of the pneumatic control pipeline is communicated with the first gas storage tank, and one end of the pneumatic control pipeline is communicated with an inlet end of the sampling pipeline through a sampling control electromagnetic valve; The sampling control electromagnetic valve is used for communicating or cutting off the gas path communication of the sampling pipeline.

7. The anti-crystallization system for flue gas sampling of claim 1, wherein, The temperature control device is an electric heating tape.

8. The anti-crystallization system for flue gas sampling of claim 1, wherein, The phosphoric acid titration device comprises an acid delivery pipeline, an acid adding pump and an acid storage tank, the acid adding pump is arranged on the internal pipeline, the acid storage tank is arranged outside the gas analysis instrument, the acid delivery pipeline inlet communicates with the acid storage tank, and the acid delivery pipeline outlet communicates with the acid adding pump.

9. The anti-crystallization system for flue gas sampling of claim 8, wherein, The phosphoric acid titration device further comprises a peristaltic pump.

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