CN204330650U - A kind of flue gas engineering acid dewpoint measurement apparatus based on thermodynamics method - Google Patents

Abstract

The utility model relates to a flue gas engineering acid dew point measuring device based on a thermodynamic method. The return of water is realized by connecting the condenser with the temperature-controlled water tank; wherein, the heat exchanger includes: an outer tube, which includes a first outer tube and a second outer tube; the first outer tube is provided with a second A variable diameter section, and the second outer tube has an inlet end and a closed end, the first outer tube has an outlet end and an inlet end, and the outlet end of the first outer tube is connected to the inlet end of the second outer tube; the inner tube, the The inner pipe has an outlet end and an inlet end, and the outlet end of the inner pipe is close to the closed end of the second outer pipe; the inlet end of the first outer pipe is provided with a seal, and a water inlet pipe and an outlet pipe are arranged on the seal, and the inner pipe The pipe is connected with the water inlet pipe.

Description

A flue gas engineering acid dew point measurement device based on thermodynamic method

technical field

The utility model relates to the field of energy and power engineering, in particular to an acid dew point measuring device for flue gas engineering based on a thermodynamic method.

Background technique

Among the various losses of the boiler, the exhaust gas loss accounts for the largest proportion, and reducing the exhaust gas temperature as much as possible is of great practical significance for energy saving and emission reduction. With the use of flue gas at the tail of the boiler, the temperature of the flue gas decreases, causing condensation of sulfuric acid vapor and water vapor in the flue gas, corrosion and ash deposition on equipment, and deterioration of heat transfer performance and safety performance of the heat exchanger. Therefore, accurately measuring the acid dew point of boiler tail gas engineering can guide the design of waste heat utilization equipment and has important practical significance in engineering practice to maximize the use of boiler flue gas waste heat.

The Chinese patent document with application number 201310298139.4 discloses a device for determining the acid dew point of boiler flue gas engineering, including a heat exchanger and a temperature control water tank. The outer layer at the same end of the two layers communicates with the water inlet of the temperature control water tank through the pipeline, and the inner layer communicates with the water outlet of the temperature control water tank through the pipeline and the flow meter, water pump, and water outlet valve arranged on the pipeline; The water inlet is also connected with a water supply pipeline, and a heat exchanger wall temperature sensor is provided on the outer wall of the heat exchanger, and a water inlet temperature sensor and an outlet water temperature sensor are respectively provided on the pipelines connected with the inlet and outlet of the temperature control water tank; A heating unit is provided, and the heat exchanger wall temperature sensor, water inlet temperature sensor, water outlet temperature sensor and the heating unit are respectively connected with the control system of the temperature control water tank.

The patent is to determine the acid dew point of boiler tail gas engineering by measuring the sudden change of heat transfer coefficient. The test device disclosed in this patent mainly has the following defects: the return water is cooled by the way of supply water, which makes the water consumption in the test process too large and has a great dependence on the selection of water source. The way of cooling with supply water requires Too many connecting pipes make the test system complicated, not suitable for equipment installation and transportation, and the continuity and stability of the test are low. The temperature is measured by a temperature inspection instrument. The circuit connection of the temperature inspection instrument is complicated, and an external computer is required for data collection, and real-time data recording is required manually, which makes the overall measurement process very inconvenient.

Therefore, how to design a brand-new device to simplify the test process and make the test continuity and stability higher is something that those skilled in the art need to solve.

Utility model content

The purpose of this utility model is to provide a flue gas engineering acid dew point measuring device based on a thermodynamic method in order to overcome the above-mentioned deficiencies in the prior art. The flue gas engineering acid dew point measurement device provided by this solution uses a condenser instead of supply cooling water for cooling, which reduces the dependence on the water source during the test process, makes the dew point test equipment more widely used, and avoids the need for a large number of replacements. Thermal hose, while enhancing continuity and stability of cooling performance during testing.

In order to achieve the above object, the utility model adopts the following technical solutions:

A flue gas engineering acid dew point measurement device based on a thermodynamic method, including a temperature-controlled water tank, which is connected to a water flow regulating valve, a water pump, a flow meter and a heat exchanger in sequence, and the water outlet of the heat exchanger passes through a condenser and The temperature-controlled water tanks are connected to realize the backflow of water;

Wherein, the heat exchanger includes:

an outer tube, the outer tube includes a first outer tube and a second outer tube, the first outer tube and the second outer tube are detachably connected;

The first outer tube is provided with a first reducing section, and the second outer tube has an inlet end and a closed end, the first outer tube has an outlet end and an inlet end, and the outlet end of the first outer tube is connected to the second outer tube. The inlet port is connected;

an inner tube disposed inside the outer tube, the inner tube has an outlet end and an inlet end, the outlet end of the inner tube is close to the closed end of the second outer tube;

The inlet end of the first outer pipe is closed by a circular seal welded thereon, the circular seal is provided with a water inlet pipe and a water outlet pipe, the inner pipe is connected with the water inlet pipe, and after the water flow enters from the water inlet pipe, It flows through the inner pipe to the closed end, flows through the channel between the outer pipe and the inner pipe, and then flows out from the outlet pipe.

Preferably, the second outer tube is provided with a second diameter reducing section, and the outlet end of the first outer tube communicates with the inlet end of the reduced diameter second outer tube.

Preferably, the outer tube is a finned tube with fins.

Preferably, the flowmeter and the heat exchanger are connected through a first connecting pipe; the temperature control water tank includes a tank, a control system, a heating unit and a water level control sensor; the water level control sensor and the heating unit are connected to the control system respectively connect.

Preferably, the condenser includes a box body, a cooling fan, a multi-tube copper elbow, a condensed water inlet pipe and a condensed water outlet pipe, the outlet pipe is connected with the condensed water inlet pipe, and the water flows through the multi-tube copper pipe. After the pipe is bent, the condensed water flows back to the temperature-controlled water tank from the outlet pipe.

Preferably, the control system includes a power supply, a temperature controller, a relay, a water pump switch and a cooling fan switch;

Wherein, the temperature controller, the relay, the water pump switch and the fan switch are respectively connected to the power supply;

The water pump switch is connected in series between the power supply and the water pump;

The cooling fan switch is connected in series between the power supply and the cooling fan.

Preferably, the water inlet pipe and the water outlet pipe are respectively provided with an inlet water temperature sensor and an outlet water temperature sensor, and the inlet water temperature sensor and the outlet water temperature sensor are respectively connected to a temperature tester.

Preferably, the test device further includes a smoke temperature sensor and a wall temperature sensor, the wall temperature sensor is arranged on the outer wall of the outer tube, and the wall temperature sensor and the smoke temperature sensor are respectively connected to the temperature tester.

The beneficial effects of the utility model are:

(1) The test device uses a condenser to replace the supply cooling water for cooling, which reduces the dependence on the water source during the test, makes the dew point test equipment more widely used, and avoids the use of a large number of heat exchange hoses, making the equipment Portable while enhancing continuity and stability of cooling performance during testing.

(2) This test device uses a temperature tester to replace the original temperature inspection instrument for temperature measurement, which reduces the complexity of the circuit during the measurement process, cancels the use of the computer, makes the test equipment simpler, and avoids manual real-time recording of data , making the testing process more convenient.

Description of drawings:

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the utility model, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the overall structural representation of the utility model;

Fig. 2 is the structural representation of condenser in the utility model;

Fig. 3 is the structural representation of heat exchanger among the middle embodiment 1 in the utility model;

Fig. 4 is the structural representation of heat exchanger among the middle embodiment 2 in the utility model;

Fig. 5 is the structural representation of control system in the utility model;

Among them: 1. Heat exchanger, 2. Temperature control water tank, 21. Tank body, 22. Control system, 23. Heating unit, 25. Water outlet, 26. Overflow port, 27. Water level control sensor, 221. Power supply, 222, temperature controller, 223, relay, 224, water pump switch, 225, cooling fan switch, 2-1, first outer tube, 2-2, second outer tube, 2-3, first reducing section, 2 -4, the second variable diameter section, 2-5, closed end, 3, smoke velocity detector, 4, flow meter, 5, water pump, 61, inlet water temperature sensor, 62, outlet water temperature sensor, 63, smoke temperature sensor , 64. Wall temperature sensor, 7. Water flow regulating valve, 8. Condenser, 81. Cabinet, 82. Cooling fan, 83. Multi-pass copper elbow, 84. Condensate water inlet pipe, 85. Condensate water Water outlet pipe, 9, temperature tester, 11, inner pipe, 12, outer pipe, 13, water inlet pipe, 14, water outlet pipe, 15, circular seal, 16, first connecting pipe, 17, second connecting pipe, 18. The third connecting pipe.

Detailed ways:

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Embodiment 1: A flue gas engineering acid dew point measurement device based on a thermodynamic method, its structure is shown in Figure 1, Figure 2, Figure 3 and Figure 5, including a heat exchanger 1, a temperature control water tank 2, and a smoke velocity detector 3 , flow meter 4, water pump 5, inlet water temperature sensor 61, outlet water temperature sensor 62, smoke temperature sensor 63 and wall temperature sensor 64, water flow regulating valve 7, condenser 8 and temperature tester 9;

Smoke velocity detector 3 is used to measure flow velocity.

The temperature control water tank 2 is connected with the heat exchanger 1 and supplies water to the heat exchanger 1 through the water pump 5, the water flow regulating valve 7 and the flow meter 4. The water quantity regulating valve 7 is arranged after the water pump 5 to ensure the constant water flow.

The temperature control water tank 2 is provided with a water outlet 25 and an overflow port 26 .

The heat exchanger 1 includes an outer tube 12, the outer tube 12 includes a first outer tube 2-1 and a second outer tube 2-2, and the first outer tube 2-1 and the second outer tube 2-2 are detachably connected;

The first outer tube 2-1 is provided with a first reducing section 2-3, and the second outer tube 2-2 has an inlet end and a closed end 2-5, and the first outer tube 2-1 has an outlet end and a closed end 2-5. The inlet end, the outlet end of the first outer tube 2-1 is connected with the inlet end of the second outer tube 2-2 through threads;

An inner tube 11 disposed in the outer tube 12, the inner tube 11 has an outlet end and an inlet end, and the outlet end of the inner tube 11 is close to the closed end 2-5 of the first outer tube 2-1;

The inlet end of the first outer pipe 2-1 is closed by a circular seal 15 welded thereon, and the circular seal 15 is provided with a water inlet pipe 13 and a water outlet pipe 14, and the inner pipe 11 communicates with the water inlet pipe 13 After the water flow enters from the water inlet pipe 13, it flows to the closed end 2-5 through the inner pipe 11, and flows out from the water outlet pipe 14 after flowing through the passage between the outer pipe 12 and the inner pipe 11.

Specifically, the flowmeter 4 communicates with the heat exchanger 1 through a first connecting pipe 16, and an inlet water temperature sensor 61 is provided at an end of the first connecting pipe 16 close to the heat exchanger 1; and the water outlet end of the heat exchanger 1 The channel 14 also communicates with the condenser 8 through a second connecting pipe 17 , and an outlet water temperature sensor 62 is provided at the end of the second connecting pipe 17 close to the heat exchanger 1 .

The condenser 8 includes a box body 81 , a cooling fan 82 , a multi-tube copper elbow 83 , a condensed water inlet pipe 84 and a condensed water outlet pipe 85 . The water outlet pipe 14 communicates with the condensed water inlet pipe 84 , and the water flows back to the temperature-controlled water tank 2 from the condensed water outlet pipe 85 after flowing through the multi-pass copper elbow 83 . The water flows through the multi-pass copper elbow 83 and is cooled by the cooling fan 82 .

The temperature-controlled water tank 2 includes a tank body 21 , a control system 22 , a heating unit 23 and a water level control sensor 27 ; the water level control sensor 27 and the heating unit 23 are respectively connected to the control system 22 .

The control system 22 includes a power supply 221 , a temperature controller 222 , a relay 223 , a water pump switch 224 and a cooling fan switch 225 . Wherein: temperature controller 222, relay 223, water pump switch 224 and fan switch 225 are connected with power supply 221 respectively, and water pump switch 224 is connected in series between power supply 221 and water pump 5; Cooling fan switch 225 is connected in series between power supply 221 and described condenser 8 between.

The above-mentioned inlet water temperature sensor 61 , outlet water temperature sensor 62 , smoke temperature sensor 63 and wall temperature sensor 64 are respectively connected with the temperature tester 9 .

Temperature controller 222 is connected with wall temperature sensor 64, by temperature controller 222, setting temperature T ₀ is compared with the detected temperature of wall surface temperature sensor 64, and the on-off of control relay 223; Relay 223 is connected with heating unit 23, The on-off of the relay 223 directly controls whether the heating unit 23 works; the temperature tester 9 is connected with the inlet water temperature sensor 61, the outlet water temperature sensor 62, the smoke temperature sensor 63 and the wall temperature sensor 64, and can measure the inlet and outlet water temperature of the heat exchanger 1 , Smoke temperature and heat exchanger wall temperature.

Water pump switch 224 and cooling fan switch 225 are connected in series between power supply 221 and water pump 5, control the work of water pump 5 and cooling fan 82; powered by.

The nominal diameter of the first outer tube 2-1 and the second outer tube 2-2 can be 38mm, the nominal diameter of the first inner tube 1-1 and the second inner tube 1-2 can be 20mm, the first outer tube 2 -1 has a length of 0.4m, the second outer pipe 2-2 has a length of 1m, and the inner pipe 11 has a length of 1.3m, and the inner pipe 11 is a straight pipe.

A preferred choice is that the circular seal 15 is an iron plate with a thickness of 3mm.

According to needs, the first outer tube 2-1 and/or the second outer tube 2-2 can be selected to use finned tubes with fins of various shapes.

In the heat exchanger provided in this embodiment, a first reducing section 2-3 is provided on the first outer pipe 2-1. The nominal diameter of the port with the smaller nominal diameter of the first variable diameter section 2-3 is the same as the nominal diameter of the first outer tube 2-1, both of which are 38mm, and the nominal diameter of the end with the larger nominal diameter of the first variable diameter section 2-3 is 57mm, then correspondingly, the nominal diameter of the circular seal 15 is also 57mm.

The nominal diameter of the water inlet pipe 13 and the water outlet pipe 14 is 20mm, and the nominal diameter of the circular seal 15 is 57mm, so the water inlet pipe 13 and the water outlet pipe 14 can be connected with the circular seal 15 very conveniently.

In this embodiment, the outer tube 12 is threadedly connected by the first outer tube 2-1 and the second outer tube 2-2, and the second outer tube 2-2 will also be corroded during the heat exchange process. When the second outer tube 2-2 can no longer be used, it only needs to be disassembled for replacement, and neither the first outer tube 2-1 nor the inner tube 11 needs to be replaced.

Under the ambient temperature of 27-35°C during the day, when the set temperature of the constant temperature water tank is 45°C, the temperature of the cooling water entering the condenser 8 after being heated by the heat exchanger 1 during the test is 52°C, and the condenser fan 82 is turned on , The system runs continuously for 13 hours, and the temperature of the constant temperature water tank is always maintained at 45±0.5°C, achieving the purpose of temperature control.

Embodiment 2: A flue gas engineering acid dew point measurement device based on a thermodynamic method, its structure is shown in Figure 1, Figure 2, Figure 4 and Figure 5, including a heat exchanger 1, a temperature control water tank 2, and a smoke velocity detector 3 , flow meter 4, water pump 5, inlet water temperature sensor 61, outlet water temperature sensor 62, smoke temperature sensor 63 and wall temperature sensor 64, water flow regulating valve 7, condenser 8 and temperature tester 9;

The temperature control water tank 2 is connected with the heat exchanger 1 and supplies water to the heat exchanger 1 through the water pump 5, the water flow regulating valve 7 and the flow meter 4. The water quantity regulating valve 7 is arranged after the water pump 5 to ensure the constant water flow.

The temperature control water tank 2 is provided with a water outlet 25 and an overflow port 26 .

The heat exchanger 1 includes an outer tube 12, the outer tube 12 includes a first outer tube 2-1 and a second outer tube 2-2, and the first outer tube 2-1 and the second outer tube 2-2 are detachably connected;

Specifically, the first outer tube 2-1 is provided with a first reducing section 2-3, and the second outer tube 2-2 has an inlet end and a closed end 2-5, and the second outer tube 2-2 There is a second variable diameter section 2-4 on the top, the first outer tube 2-1 has an outlet end and an inlet end, and the outlet end of the first outer tube 2-1 is connected to the inlet end of the second outer tube 2-2 through threads. connect;

An inner tube 11 disposed in the outer tube 12, the inner tube 11 has an outlet end and an inlet end, and the outlet end of the inner tube 11 is close to the closed end 2-5 of the first outer tube 2-1;

The inlet end of the first outer pipe 2-1 is closed by a circular seal 15 welded thereon, and the circular seal 15 is provided with a water inlet pipe 13 and a water outlet pipe 14, and the inner pipe 11 communicates with the water inlet pipe 13 After the water flow enters from the water inlet pipe 13, it flows to the closed end 2-5 through the inner pipe 11, and flows out from the water outlet pipe 14 after flowing through the passage between the outer pipe 12 and the inner pipe 11.

A preferred choice is that the circular seal 15 is an iron plate with a thickness of 3mm.

According to needs, the second outer tube 2-2 can choose to use finned tubes with fins of various shapes.

The nominal diameter of the outlet end of the first outer tube 2-1 is 38 mm, the nominal diameter of the inlet end of the second outer tube 2-2 after passing through the second reducing section 2-4 is 38 mm, and the nominal diameter of the inner tube 11 is 20 mm.

Wherein, the length of the first outer pipe 2-1 is 0.4m, the length of the second outer pipe 2-2 is 1m, the length of the inner pipe 11 is 1.3m, and the inner pipe 11 is a straight pipe.

Specifically, the flowmeter 4 communicates with the heat exchanger 1 through a first connecting pipe 16, and an inlet water temperature sensor 61 is provided at an end of the first connecting pipe 16 close to the heat exchanger 1; and the water outlet end of the heat exchanger 1 The channel 14 also communicates with the condenser 8 through a second connecting pipe 17 , and an outlet water temperature sensor 62 is provided at the end of the second connecting pipe 17 close to the heat exchanger 1 .

The condenser 8 includes a box body 81 , a cooling fan 82 , a multi-tube copper elbow 83 , a condensed water inlet pipe 84 and a condensed water outlet pipe 85 . The outlet pipe 14 communicates with the condensed water inlet pipe 84 , and the water flows through the multi-pass copper elbow 83 and then flows back to the temperature-controlled water tank 2 from the condensed water outlet pipe 85 through the third connecting pipe 18 .

The temperature-controlled water tank 2 includes a tank body 21 , a control system 22 , a heating unit 23 and a water level control sensor 27 ; the water level control sensor 27 and the heating unit 23 are respectively connected to the control system 22 .

The control system 22 includes a power supply 221 , a temperature controller 222 , a relay 223 , a water pump switch 224 and a cooling fan switch 225 . Wherein: temperature controller 222, relay 223, water pump switch 224 and fan switch 225 are respectively connected with power supply 221, and water pump switch 224 is connected in series between power supply 221 and water pump 5; Cooling fan switch 225 is connected in series between power supply 221 and cooling fan 82 .

The above-mentioned inlet water temperature sensor 61 , outlet water temperature sensor 62 , smoke temperature sensor 63 and wall temperature sensor 64 are respectively connected with the temperature controller 222 .

Temperature controller 222 is connected with wall temperature sensor 64, by temperature controller 222, setting temperature T ₀ is compared with the detected temperature of wall surface temperature sensor 64, and the on-off of control relay 223; Relay 223 is connected with heating unit 23, The on-off of the relay 223 directly controls whether the heating unit 23 works; the temperature tester 9 is connected with the inlet water temperature sensor 61, the outlet water temperature sensor 62, the smoke temperature sensor 63 and the wall temperature sensor 64 respectively, and measures the inlet and outlet water temperature of the heat exchanger 1 , smoke temperature and heat exchanger wall temperature; water pump switch 224 and cooling fan switch 225 are connected in series between power supply 221, cooling fan 82 and water pump 5, and control the work of water pump 5 and cooling fan 82; Relay 223, temperature tester 9, water pump 5 and cooling fan 82 supply power.

The heat exchanger in this embodiment adopts a detachable structure, which has the following advantages compared with the prior art: In the prior art, the outer tube is a non-detachable structure. During the heat exchange test, the outer tube needs to be in corrosion It is often corroded in an aggressive gas environment, making it unusable. The outer tube cannot be disassembled, so the heat exchanger can only be replaced as a whole. In this embodiment, the outer tube 2 is threadedly connected by the first outer tube 2-1 and the second outer tube 2-2. During the heat exchange test, the second outer tube 2-2 will also be corroded. When the second outer tube 2-2 can no longer be used, it only needs to be disassembled for replacement, and neither the first outer tube 2-1 nor the inner tube 1 needs to be replaced, which greatly reduces the test cost. In addition, in this embodiment, when it is necessary to use heat exchange sections with different nominal diameters, materials, and tube shapes, it can be realized only by replacing the second outer tube 2-2 without replacing the entire heat exchange tube.

In this scheme, the characteristic that the heat transfer coefficient of the heat exchanger will change significantly when a wet ash layer appears on the surface of the heat exchanger is mainly used, and the acid dew point temperature of the boiler tail gas engineering is determined by observing the sudden change of the heat transfer coefficient of the heat exchanger , so as to guide the actual engineering design and avoid corrosion and dust accumulation in the heat exchanger.

Use the temperature control water tank to control the temperature of the cooling water in the water tank according to the measured value of the heat exchanger wall temperature, so as to achieve the effect of stabilizing the inlet water temperature, so that the inlet water temperature can be set according to the needs, so as to measure the heat transfer of the heat exchanger at different inlet water temperatures coefficient. When measuring, first set the cooling water at a higher initial temperature so that the outer tube works at a higher water temperature. As the amount of dry ash deposited on the wall of the outer tube increases, the heat transfer coefficient of the heat exchanger decreases slowly. When the dry ash on the surface of the outer tube is deposited to a saturated state, the amount of dry ash will not increase, and the heat transfer coefficient of the heat exchanger will no longer change; when the heat transfer coefficient of the heat exchanger is stable, it will gradually decrease through control means Inlet water temperature, when the wall temperature of the outer tube is higher than the engineering acid dew point, the dry ash state on the surface of the outer tube will not change, and the heat transfer coefficient of the heat exchanger will not change significantly; continue to reduce the wall temperature of the heat exchanger by controlling the inlet water temperature , when the wall temperature drops to the engineering acid dew point, the dry ash on the surface of the outer tube will become wet ash bonded to the wall surface of the outer tube due to condensation in the flue gas, and the heat transfer coefficient will drop sharply. By observing the change of the heat transfer coefficient of the heat exchanger, the dew point of the flue gas engineering acid is obtained.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments enables those skilled in the art to realize or use the utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A flue gas engineering acid dew point measuring device based on thermodynamic method, it is characterized in that, comprises temperature control water tank, and temperature control water tank is connected with water flow control valve, water pump, flowmeter and heat exchanger successively, the heat exchanger The water outlet is connected to the temperature-controlled water tank through the condenser to realize the return of water; Wherein, the heat exchanger includes: an outer tube, the outer tube includes a first outer tube and a second outer tube, the first outer tube and the second outer tube are detachably connected; The first outer tube is provided with a first reducing section, and the second outer tube has an inlet end and a closed end, the first outer tube has an outlet end and an inlet end, and the outlet end of the first outer tube is connected to the second outer tube. The inlet port is connected; an inner tube disposed inside the outer tube, the inner tube has an outlet end and an inlet end, the outlet end of the inner tube is close to the closed end of the second outer tube; The inlet end of the first outer pipe is closed by a circular seal welded thereon, the circular seal is provided with a water inlet pipe and a water outlet pipe, the inner pipe is connected with the water inlet pipe, and after the water flow enters from the water inlet pipe, It flows through the inner pipe to the closed end, flows through the passage between the outer pipe and the inner pipe, and then flows out from the outlet pipe. 2. The flue gas engineering acid dew point measuring device according to claim 1, characterized in that, the second outer pipe is provided with a second diameter-reducing section, and the outlet end of the first outer pipe is connected to the second diameter-reducing section. The inlet ends of the outer tubes are connected. 3. The flue gas engineering acid dew point measurement device according to claim 2, characterized in that, the second outer tube is a finned tube with fins. 4. flue gas engineering acid dew point measuring device according to claim 1, is characterized in that, described flowmeter and heat exchanger are connected through the first connecting pipe; Temperature control water tank comprises casing, control system, heating unit and The water level control sensor; the water level control sensor and the heating unit are respectively connected with the control system. 5. The flue gas engineering acid dew point measuring device according to claim 1, wherein the condenser comprises a casing, a cooling fan, a multi-tube copper elbow, a condensed water inlet pipe and a condensed water outlet pipe; The water outlet pipe is connected with the condensed water inlet pipe, and the water flows back to the temperature-controlled water tank from the condensed water outlet pipe after flowing through the multi-pass copper elbow. 6. The flue gas engineering acid dew point measuring device according to claim 4, wherein the control system includes a power supply, a temperature controller, a relay, a water pump switch and a cooling fan switch; Wherein, the temperature controller, the relay, the water pump switch and the cooling fan switch are respectively connected to the power supply; the water pump switch is connected in series between the power supply and the water pump; the cooling fan switch is connected in series between the power supply and the cooling fan. 7. The flue gas engineering acid dew point measuring device according to claim 1, characterized in that, the inlet water pipe and the outlet pipe are respectively provided with an inlet water temperature sensor and an outlet water temperature sensor, an inlet water temperature sensor and an outlet water temperature sensor respectively connected to the temperature tester. 8. flue gas engineering acid dew point measuring device according to claim 7, is characterized in that, described flue gas engineering acid dew point measuring device also comprises smoke temperature sensor and wall temperature sensor, and wall temperature sensor is arranged on the outer pipe outer wall , the wall temperature sensor and the smoke temperature sensor are respectively connected with the temperature tester.