Dew point corrosion test device and test method

Abstract

The invention discloses a dew point corrosion test device and a dew point corrosion test method. The test device comprises a gas evaporation unit, a dew point test cabin, a dew condensation collection unit and a condensation reflux unit, the gas evaporation unit is used for generating corrosive gas; a photoelectric sensor is arranged in the dew-point experiment module, a glass window and a high-speed camera are arranged at the top, and an air inlet, a first air outlet and a second air outlet are formed in the bottom; the gas inlet is connected with the gas evaporation unit, the first gas outlet is connected with the condensation collection unit, and the second gas outlet is connected with the condensation reflux unit; and the condensation collecting unit comprises a second electric heating belt, a condensing disc, a second temperature sensor, a pH meter and a liquid collecting cabin. According to the invention, the dew-point temperature and the dew-point pH value can be accurately detected, component analysis can be carried out on the dew condensation liquid in the liquid collection cabin, solutions with the same components are subsequently prepared to carry out an electrochemical corrosion experiment, and a dew-point electrochemical corrosion mechanism is researched.

Description

Technical Field

[0001] The present invention relates to the technical field of test devices, and particularly relates to a dew point corrosion test device and a test method. Background Art

[0002] Dew point corrosion widely exists in coal chemical production, such as the blind end parts of equipment and pipelines, closed bypasses, cold ends with insulated plugs, local condensation corrosion on one side of a pipeline due to a cooling medium on the other side, the top reflux part, etc. The mechanism of dew point corrosion is as follows: water vapor containing corrosive media such as HCl, CO2, SO2, SO3, NOX, etc., generates liquid condensation at the phase change point during the cooling process, that is, steam condensate, and the steam condensate corrodes the equipment and pipelines.

[0003] There are mainly three research methods for dew point corrosion: acid immersion experiment, laboratory simulation experiment, and on-site corrosion experiment. The essence of dew point corrosion is that acidic gas condenses in the low-temperature region to produce a high-concentration acidic liquid film, and the electrochemical corrosion of materials under the acidic liquid film. The acid immersion experiment can only study the corrosiveness of acid solutions with different pH values or compositions on metal materials, but cannot reveal the pH value or composition of the high-concentration acidic liquid film in the dew point region, and has limited guidance for actual engineering, resulting in doubts about the results of the acid immersion experiment. The on-site test is to directly place the test piece at a high-risk location suffering from dew point corrosion and regularly take it out for evaluation and analysis of the corrosion resistance performance. The results obtained by this method are highly reliable and are the most persuasive one among the research methods. However, the on-site test is complex to operate and is not conducive to the study of the material corrosion mechanism; therefore, people have carried out laboratory simulation experiments.

[0004] Chinese Patent CN101929945A discloses a test method and device for low-temperature dew point corrosion of phosphorus in yellow phosphorus tail gas on boiler materials, which includes a simulation test system for low-temperature dew point corrosion of phosphorus components in yellow phosphorus tail gas: it consists of a heating and temperature control system, a condensation and reflux system, and a tail gas treatment system. The condensation and reflux system (II) includes: a condenser, a five-neck flask, the condenser is connected to the five-neck flask through a rubber stopper, cooling water is introduced from the lower water inlet of the condenser and discharged from the upper water outlet, a temperature sensor probe is inserted into the reagent from another opening of the flask, the temperature sensor probe is connected to the flask through a rubber stopper, and the remaining three openings of the five-neck flask are respectively used to hold three parallel specimens. The specimens are suspended by polytetrafluoroethylene sample wires and completely immersed in the reagent, and the polytetrafluoroethylene wires are connected to the flask through rubber stoppers. This patent determines the dew point temperature through theoretical calculation and studies the corrosion situation at the dew point temperature. There is a deviation between the results of theoretical calculation and the actual situation, and this patent cannot directly measure the dew point temperature.

[0005] Chinese Patent CN117805186 discloses an experimental device for dew point corrosion characteristic detection, which includes a gas delivery unit, a first-stage condensation reflux unit connected to the gas delivery unit, a second-stage condensation reflux unit connected to the first-stage condensation reflux unit, and an exhaust gas treatment unit connected to the second-stage condensation reflux unit. A dew point corrosion simulation experiment chamber is provided inside the first-stage condensation reflux unit. A thermometer and a pH meter are embedded inside the dew point corrosion simulation experiment chamber. Corrosion test coupons made of different materials can be placed inside the dew point corrosion simulation experiment chamber. A high-speed camera and an infrared thermometer are provided around the dew point corrosion simulation experiment chamber. This patent slowly adjusts the refrigerant temperature and flow rate of the first condenser to make the gas reach the dew point, and droplets appear on the corrosion test coupons, and records the values of the pH meter and the thermometer. The temperature corresponding to the thermometer is the dew point temperature. This method has a slow temperature response speed, there is a deviation between the measured dew point temperature and the true value, and the dew point temperature is determined only by observing the droplets on the corrosion coupon once, so the measurement result has low accuracy.

[0006] In summary, there is still no method and device in the prior art that can accurately measure the dew point temperature and the condensation components. Summary of the Invention

[0007] To achieve the above object, the present invention provides a dew point corrosion test device and a test method.

[0008] The technical solution adopted by the present invention is:

[0009] A dew point corrosion test device includes a gas evaporation unit, a dew point experiment chamber, a condensation collection unit, and a condensation reflux unit;

[0010] The gas evaporation unit is used to generate corrosive gas; the outer wall of the dew point experiment chamber is provided with a first electric heating tape and a first temperature sensor, a photoelectric sensor is provided inside the experiment chamber, a glass window and a high-speed camera are provided at the top of the experiment chamber, and an air inlet, a first air outlet, and a second air outlet are provided at the bottom of the experiment chamber; the air inlet is connected to the gas evaporation unit, the first air outlet is connected to the condensation collection unit, and the second air outlet is connected to the condensation reflux unit;

[0011] The condensation collection unit includes a second electric heating tape, a condensation pan, a second temperature sensor, a pH meter, and a liquid collection chamber; the condensation pan is installed directly below the first air outlet, and its upper surface is completely exposed in the dew point experiment chamber; a condensate outlet is provided at the center of the condensation pan, and the liquid collection chamber is connected to the condensate outlet of the condensation pan through a condensate pipe; the second temperature sensor is used to measure the surface temperature of the condensation pan; the pH meter is used to measure the pH value of the dew point condensate; the second electric heating tape is embedded inside the condensation pan to control the surface temperature of the condensation pan;

[0012] The condensation reflux unit is connected to the gas evaporation unit and the dew point test chamber, and is used to maintain the component balance in the dew point test chamber and control the pressure in the chamber.

[0013] Further, the photoelectric sensor is interlocked with the second electric heating belt for control.

[0014] Further, a third temperature sensor is provided in the connecting pipe between the gas evaporation unit and the dew point test chamber, and a heat insulation layer is provided on the outer wall of the connecting pipe.

[0015] Further, the material of the dew point test chamber is polytetrafluoroethylene, and the glass window is made of electrically heated high borosilicate glass.

[0016] Further, the material of the condensation pan is copper, and its surface is titanium-plated.

[0017] Further, the gas evaporation unit includes an electric heating pot and a distillation flask disposed in the electric heating pot. The distillation flask is provided with a first outlet and a second outlet. The first outlet is connected to the dew point test chamber, and a first temperature sensor is installed in the first outlet; the second outlet is connected to the condensation reflux unit.

[0018] Further, the condensation reflux unit includes a condenser, an acidic gas absorption tank and an alkaline gas absorption tank. The condenser is provided with a gas inlet, a gas outlet, a refrigerant inlet, a refrigerant outlet and a condensate reflux port; the gas inlet is connected to the second gas outlet of the dew point test chamber through an intake pipe, and a cut-off valve is provided on the intake pipe. The gas outlet is communicated with the alkaline gas absorption tank through an outlet pipe. The top gas outlet of the alkaline gas absorption tank is communicated with the acidic gas absorption tank through a pipe. The condensate reflux port is connected to the second outlet of the gas evaporation unit through a reflux pipe, and a cut-off valve is provided on the condensate reflux port.

[0019] A test method for dew point corrosion using the above-mentioned dew point corrosion test device includes the following steps:

[0020] (1) Turn on the first electric heating belt and the first temperature sensor to preheat the dew point test chamber. At the same time, turn on the second electric heating belt and the second temperature sensor to preheat the dew condensation collection unit.

[0021] (2) After the dew point test chamber and the dew condensation collection unit are preheated, add the prepared test solution into the distillation flask, start the electric heating pot to heat the test solution, and at the same time open the cut-off valves on the intake pipe and the reflux pipe of the condensation reflux unit to connect the condensation reflux unit with the dew point test chamber and the dew condensation collection unit; and pass cooling water through the condenser.

[0022] (3) As the solution in the distillation flask boils, the acidic gas rises and enters the dew point test chamber through the air inlet. Turn on the photoelectric sensor and the high-speed camera. When the temperature of the dew collection unit decreases and droplets appear on the surface of the condensation plate 33 as observed by the high-speed camera 25, record the temperature value displayed by the second temperature sensor. Control the power of the second electric heating tape to increase through the photoelectric sensor, so that the surface temperature of the condensation plate rises until the droplets disappear. Measure the temperature of the second temperature sensor again. Repeat this process 3 - 4 times, and take the arithmetic mean of all measured values as the dew point temperature.

[0023] (4) Turn off the photoelectric sensor, manually control the power of the second electric heating tape to decrease, so that the surface temperature of the condensation plate is lower than the dew point temperature. The dew point condensate accumulates on the condensation plate and enters the condensate collection chamber through the condensate pipe for collection. Turn on the pH meter to detect the pH value of the dew point condensate in the condensate collection chamber.

[0024] Further, during the above test process, part of the acidic gas entering the dew point test chamber enters the condenser through the second air outlet, is cooled by the refrigerant in the condenser, and most of it condenses into liquid and returns to the multi-port distillation flask through the reflux pipe. A small amount of uncondensed gas enters the alkaline gas absorption tank and the acidic gas absorption tank in sequence for waste gas absorption.

[0025] Further, take a sample of the dew point condensate in the condensate collection chamber for chemical composition analysis, and configure a solution with the same composition for electrochemical corrosion experiments.

[0026] Advantages of the present invention:

[0027] 1. The test device of the present invention can control the surface temperature of the condensation plate through electric heating, enabling the test gas to condense on the surface of the condensation plate. The electric heating control has a fast response speed, and the experimental results are more accurate. By measuring the surface temperature of the condensation plate, the dew point temperature can be accurately detected, and the detection accuracy of the dew point temperature is high.

[0028] 2. The present invention is provided with a liquid collection chamber to collect the dew condensation liquid on the surface of the condensation plate. It is very convenient to measure the pH value of the dew point condensate using a pH meter, and samples can be taken to analyze the composition of the dew condensation liquid in the liquid collection chamber. Subsequently, a solution with the same composition can be configured for electrochemical corrosion experiments to study the electrochemical corrosion mechanism.

[0029] 3. The test method of the present invention further improves the detection accuracy of the dew point temperature by increasing and decreasing the surface temperature of the condensation plate multiple times. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the dew point corrosion test device of the present invention. Detailed Embodiments

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and preferred embodiments.

[0032] Refer to Figure 1 , a dew point corrosion test device, comprising a gas evaporation unit 1, a dew point experiment chamber 2, a condensation collection unit 3, and a condensation reflux unit 4.

[0033] The gas evaporation unit 1 is used to generate corrosive gas, including an electric heating pan 11 and a multi-neck distillation flask 12 disposed in the electric heating pan. For example, in this embodiment, the distillation flask 12 is provided with a first outlet and a second outlet. The first outlet is connected to the dew point experiment chamber 2, and a temperature sensor 13 is installed in the first outlet; the second outlet is a condensate reflux port 121 and is connected to the condensation reflux unit 4.

[0034] The outer wall of the dew point experiment chamber 2 is provided with an electric heating tape 22 and a temperature sensor 23. A photoelectric sensor 26 is disposed inside the chamber. A glass window 24 is provided at the top of the chamber, and an air inlet, a first air outlet, and a second air outlet are provided at the bottom of the chamber; the air inlet is connected to the first outlet of the multi-neck distillation flask 12. Outside the dew point experiment chamber 2, above the glass window 24, a high-speed camera 25 is provided for observing the condensation condition inside the dew point experiment chamber 2.

[0035] The condensation collection unit 3 includes an electric heating tape 32, a condensation pan 33, a temperature sensor 31, a pH meter 34, and a liquid collection chamber 35; the condensation pan 33 is disposed directly below the first air outlet of the dew point experiment chamber 2, and its upper surface is completely exposed in the dew point experiment chamber 2. The photoelectric sensor 26 is disposed directly above the condensation pan 33; the electric heating tape 32 is disposed at the bottom of the condensation pan 33 for controlling the surface temperature of the condensation pan 33. The photoelectric sensor 26 is in interlocking control with the electric heating tape 32. When the photoelectric sensor 26 detects that the reflection light intensity becomes weak due to condensation on the surface of the condensation pan 33, it controls the electric heating tape 32 to adjust the power to increase the temperature of the condensation pan 33. The temperature sensor 31 is connected to the surface of the condensation pan 33 for measuring the condensation temperature of the condensation pan.

[0036] A condensation tube is connected to the central part of the condensation pan 33. The liquid collection chamber 35 is connected to the condensation pan 33 through the condensation tube for collecting the dew point condensate on the condensation pan 33. An isolation valve is provided in the condensation tube; the pH meter 34 is disposed in the liquid collection chamber 35 for measuring the pH value of the dew point condensate.

[0037] In this embodiment, the dew point test chamber 2 is made of polytetrafluoroethylene, and the glass window 24 is a 25-mm-thick electrically heated high borosilicate glass window. The connecting pipe between the distillation flask 12 and the dew point test chamber 2 is provided with a heat insulation layer, so that the surface temperatures of the gas delivery unit 1 and the dew point test chamber 2 are both higher than the dew point temperature, enabling the acidic gas to only condense on the surface of the condensation tray 33, ensuring the accuracy of dew point detection.

[0038] The condensation tray 33 is made of copper with a titanium coating, ensuring a high heat transfer coefficient, sensitive temperature control, and corrosion resistance to most acid solutions. The contact of the temperature sensor 31 is 2 mm away from the upper surface of the condensation tray 33, ensuring accurate detection of the dew point temperature.

[0039] The condensation reflux unit 4 includes a condenser 41, an alkaline gas absorption tank 42, and an acidic gas absorption tank 43. The condenser 41 has a gas inlet, a gas outlet, a refrigerant inlet 411, a refrigerant outlet 413, and a condensate reflux port 412. The condensate reflux port 412 is connected to the condensate reflux port 121 of the multi-port distillation flask 12 through a reflux pipe, and a cut-off valve is provided on the reflux pipe. The gas inlet is connected to the second gas outlet of the dew point test chamber 2 through an intake pipe, and a cut-off valve is provided on the intake pipe. The gas outlet is connected to the alkaline gas absorption tank 42 through a pipe. The top of the alkaline gas absorption tank 42 has an air outlet, and the air outlet of the alkaline gas absorption tank 42 is connected to the acidic gas absorption tank 43 through a pipe.

[0040] When the above test device is performing a condensation test,

[0041] 1. First, turn on the temperature sensor 23 and the electric heating tape 22 outside the dew point test chamber 2 to preheat the dew point test chamber 2. At the same time, turn on the temperature sensor 31 and the electric heating tape 32 inside the condensation collection unit 3 to preheat the condensation collection unit 3. The preheating temperatures of the dew point test chamber 2 and the condensation collection unit 3 are both set to 120 °C.

[0042] 2. After the preheating of the dew point test chamber 2 and the condensation collection unit 3 is completed, add the prepared test solution to the distillation flask 12, start the electric heating pan 11 to heat the distillation flask 12, and at the same time open the cut-off valve on the intake pipe of the condensation reflux unit 4 and close the cut-off valve on the reflux pipe. Pass cooling water in from the refrigerant inlet 411 and out from the refrigerant outlet 413.

[0043] 3. As the solution in the distillation flask boils, the acidic gas rises and enters the dew point test chamber 2 through the air inlet. Turn on the photoelectric sensor 26 and the high-speed camera 25. When the temperature of the dew condensation collection unit decreases slowly and tiny droplets appear on the surface of the condensation disk 33 as observed through the high-speed camera 25, record the temperature displayed by the temperature sensor 31. At this time, the light intensity of the photoelectric sensor 26 weakens, and the photoelectric sensor 26 controls the power of the electric heating tape 32 to increase slowly, causing the surface temperature of the condensation disk 33 to rise slowly until the droplets disappear. Record the temperature of the temperature sensor 31 again. Repeat this process 3 - 4 times, and take the arithmetic mean as the dew point temperature.

[0044] 4. Turn off the photoelectric sensor 26, manually control the power of the electric heating tape 32 to decrease, so that the surface temperature of the condensation disk 33 is slightly lower than the dew point temperature, and the dew point condensate slowly accumulates on the condensation disk 33. When the dew point condensate accumulates to a certain extent, open the isolation valve in the condenser tube, and collect the dew point condensate through the condensate collection chamber 35. Turn on the pH meter 34 to detect the pH value of the dew point condensate, and chemical composition analysis of the dew point condensate can be carried out, and a solution with the same composition can be prepared for electrochemical corrosion experiments.

[0045] 5. During the above test process, part of the acidic gas entering the dew point test chamber 2 enters the condenser 41 through the second air outlet. After being cooled by the refrigerant in the condenser, most of it condenses into liquid and returns to the multi-port distillation flask 12 through the reflux pipeline to ensure the overall component balance of the experimental system. A small amount of uncondensed gas enters the alkaline gas absorption tank 42 and the acidic gas absorption tank 43 in sequence for waste gas absorption.

[0046] This application also provides a method for conducting a dew point test using the above test device.

[0047] Example 1

[0048] (1) Clean the device, connect all components, and wrap the pipeline and other parts with a heat insulation layer. Turn on the temperature sensors 23 and 31 and the electric heating tapes 22 and 32 to preheat the dew point test chamber 2 and the dew condensation collection unit 3. Set the preheating temperature to 120°.

[0049] (2) Add the pre-prepared mixed liquid (composition of the mixed liquid: dimethyl silicone oil: 0.001 mol / L HCl solution = 9:1) to the distillation flask 12. Turn on the power switch of the electric heating pan 11 to heat the mixed liquid to generate corrosive gas for the experiment. At the same time, pass cooling water (ordinary tap water is used in this example) through the condenser 21. During the heating process, observe the bubbling situation of the waste gas treatment unit to ensure that basically no gas enters the waste gas treatment unit, and control the pressure in the test chamber to ensure safe operation.

[0050] (3) After the acid gas fills the regulated dew point test chamber 2, turn on the photoelectric sensor 26 and the high-speed camera 25. When the surface temperature of the condensation plate 33 drops to 103 °C, obvious condensation is observed on the surface of the condensation plate 33 through the high-speed camera 25; at this time, the reflected light intensity of the photoelectric sensor weakens, and the feedback signal of the photoelectric sensor controls the power of the electric heating tape 32 to increase. After the surface temperature of the condensation plate 33 rises to 108 °C, the droplets are observed to disappear significantly. After the droplets completely disappear, the photoelectric sensor controls the power of the electric heating tape 32 to gradually decrease again, and the surface temperature of the condensation plate 33 slowly decreases. When obvious condensation appears on the surface of the condensation plate 33 again, record the temperature of the temperature sensor 31. Repeat the experiment four times. The four dew point temperatures are 103 °C, 104.5 °C, 103.5 °C, and 104 °C respectively. Take the arithmetic mean of the four times, 103.75 °C, as the dew point temperature of this experiment.

[0051] (4) Maintain the surface temperature of the condensation plate 33 at 103.5 °C, allow the dew point condensate to slowly accumulate on the condensation plate 33, and then flow into the condensate collection chamber 35. Observe that the pH value displayed by the pH meter 34 is 2.5.

[0052] Example 2

[0053] (1) Take the condensate in the condensate collection chamber 35 in Example 1 for component detection. The Cl concentration in the dew point condensate is 0.00316 mol / L, and there is also a small amount of dimethyl silicone oil. -

[0054] (2) Configure a solution with the same components for the electrochemical experiment. The test method is as follows:

[0055] Cut the 316 stainless steel working electrode into 10×10×3 mm, weld a copper wire on the back, encapsulate it with epoxy resin, and the exposed area is 1 cm². Prepare an auxiliary electrode platinum electrode and a reference electrode saturated calomel electrode. Place the working electrode and the auxiliary electrode into the prepared solution, place the reference electrode into the saturated KCL solution, connect it to the HCL solution through a salt bridge, and connect the three electrodes to the electrochemical workstation. Heat the solution to 104 °C, turn on the electrochemical workstation, obtain the Tafel polarization curve, and use the Tafel extrapolation method to calculate the corrosion rate to be 0.02629 mm / y. 2

[0056] Example 3

[0057] (1) Clean the device, connect all components, wrap the pipeline and other parts with a heat insulation layer, turn on the temperature sensors 23 and 31 and the electric heating tapes 22 and 32, and preheat the dew point test chamber 2 and the dew condensation collection unit 3. The preheating temperature is set to 120 °C.

[0058] (2) Add the pre-prepared mixed liquid (composition of the mixed liquid: dimethyl silicone oil: 0.001 mol / L HCl solution = 7:1) to the distillation flask 12. Turn on the power switch of the electric heating pan 11 to heat the mixed liquid to generate corrosive gas for experimental use. At the same time, pass cooling water (normal temperature water is used in this embodiment) into the condenser 21. During the heating process, it is necessary to observe the bubbling situation of the waste gas treatment unit so that basically no gas enters the waste gas treatment unit, control the pressure in the test chamber, and ensure the operation safety;

[0059] (3) After the acidic gas fills the regulated dew point test chamber 2, turn on the photoelectric sensor 26 and the high-speed camera 25. When the surface temperature of the condensation disk 33 drops to 105 °C, obvious condensation is observed on the surface of the condensation disk 33 through the high-speed camera 25; at this time, the reflected light intensity of the photoelectric sensor weakens, and the feedback signal of the photoelectric sensor controls the power of the electric heating tape 32 to increase. After the surface temperature of the condensation disk 33 rises to 110 °C, it is observed that the liquid droplets significantly disappear. After the liquid droplets completely disappear, the photoelectric sensor controls the power of the electric heating tape 32 to gradually decrease again, and the surface temperature of the condensation disk 33 slowly decreases. When obvious condensation appears on the surface of the condensation disk 33 again, record the temperature of the temperature sensor 31. Repeat the experiment four times. The four dew point temperatures are 105 °C, 106 °C, 105.5 °C, and 105.3 °C respectively. Take the arithmetic average of the four times, 105.45 °C, as the dew point temperature of this experiment.

[0060] (4) Maintain the surface temperature of the condensation disk 33 at 105 °C, and let the dew point condensate slowly accumulate on the condensation disk 33 and then flow into the condensate collection chamber 35. Observe that the pH value displayed by the pH meter 34 is 2.1.

[0061] Example 4

[0062] (1) Take the condensate in the condensate collection chamber 35 in Example 3 for component detection. The Cl - concentration in the dew point condensate is 0.00794 mol / L, and there is also a small amount of dimethyl silicone oil.

[0063] (2) Prepare a solution with the same composition for electrochemical experiments. The test method is as follows:

[0064] Cut the 316 stainless steel working electrode into 10×10×3 mm, weld a copper wire on the back, encapsulate it with epoxy resin, and the exposed area is 1 cm 2 . Prepare an auxiliary electrode of platinum electrode and a reference electrode of saturated calomel electrode. Place the working electrode and the auxiliary electrode into the prepared solution, place the reference electrode into the saturated KCL solution, connect it to the HCL solution through a salt bridge, and connect the three electrodes to an electrochemical workstation. Heat the solution to 104 °, turn on the electrochemical workstation, obtain the Tafel polarization curve, and use the Tafel extrapolation method to calculate the corrosion rate as 0.03408 mm / y.

[0065] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also within the scope of protection of the present invention.

Claims

1. A dew point corrosion test device, characterized in that: It comprises a gas evaporation unit (1), a dew point test chamber (2), a condensation collection unit (3) and a condensation reflux unit (4); The gas evaporation unit (1) is used to generate corrosive gas; the outer wall of the dew point test chamber (2) is provided with a first electric heating belt (22) and a first temperature sensor (13); a photoelectric sensor (26) is provided in the test chamber; a glass window and a high-speed camera (25) are provided on the top of the test chamber; an air inlet, a first air outlet and a second air outlet are provided on the bottom of the test chamber; the air inlet is connected to the gas evaporation unit (1), the first air outlet is connected to the condensation collection unit (3), and the second air outlet is connected to the condensation reflux unit (4); The condensation collection unit (3) comprises a second electric heating belt (32), a condensation plate (33), a second temperature sensor (31), a pH meter (34), and a liquid collection chamber (35); the condensation plate (33) is installed directly below the first air outlet, and its upper surface is completely exposed in the dew point test chamber (2); a condensate outlet is provided at the center of the condensation plate (33), and the liquid collection chamber (35) is connected to the condensate outlet of the condensation plate (33) through a condensation pipe; the second temperature sensor (31) is used to measure the surface temperature of the condensation plate; the pH meter (34) is used to measure the pH value of the dew point condensate; the second electric heating belt (32) is embedded in the interior of the condensation plate (33) and is used to control the surface temperature of the condensation plate (33); The condensation reflux unit (4) is connected to the gas evaporation unit (1) and the dew point test chamber (2) and is used to maintain the component balance in the dew point test chamber (2) and control the pressure in the chamber.

2. A dew point corrosion test device according to claim 1, characterized in that: The photoelectric sensor (26) is interlockedly controlled with the second electric heating belt (32).

3. A dew point corrosion test device according to claim 1, characterized in that: A third temperature sensor (13) is provided in a connecting pipe between the gas evaporation unit (1) and the dew point test chamber (2), and a heat-insulating layer is provided on an outer wall of the connecting pipe.

4. A dew point corrosion test device according to claim 1, characterized in that: The material of the dew point test chamber (2) is polytetrafluoroethylene, and the glass window (24) is electrically heated high borosilicate glass.

5. A dew point corrosion test device according to claim 1, characterized in that: The condensation plate (33) is made of copper with a titanium-plated surface.

6. A dew point corrosion test device according to claim 1, characterized in that: The gas evaporation unit (1) comprises an electric heating pot (11) and a distillation flask (12) arranged in the electric heating pot, the distillation flask (12) being provided with a first outlet and a second outlet, the first outlet being connected to a dew point test chamber (2), a first temperature sensor (13) being installed in the first outlet, and the second outlet being connected to a condensation reflux unit (4).

7. A dew point corrosion test device according to claim 6, characterized in that: The condensation reflux unit (4) comprises a condenser (41), an acidic gas absorption tank (43) and an alkaline gas absorption tank (42); the condenser (41) is provided with a gas inlet, a gas outlet, a refrigerant inlet (411), a refrigerant outlet (413) and a condensate reflux port (412); the gas inlet is connected to the second gas outlet of the dew point test chamber (2) through an inlet pipe, a shutoff valve is provided on the inlet pipe, the gas outlet is connected to the alkaline gas absorption tank (42) through an outlet pipe, the top gas outlet of the alkaline gas absorption tank (42) is connected to the acidic gas absorption tank (43) through a pipe, the condensate reflux port (412) is connected to the second outlet of the gas evaporation unit (1) through a reflux pipe, and a shutoff valve is provided on the condensate reflux port (412).

8. A method for conducting a dew point corrosion test using the dew point corrosion test device according to claim 7, characterized in that: The following steps are involved: (1) turning on the first electric heating belt (22) and the first temperature sensor (13) to preheat the dew point test chamber (2), and at the same time turning on the second electric heating belt (32) and the second temperature sensor (31) to preheat the condensation collection unit (3); (2) After the preheating of the dew point test chamber (2) and the condensation collection unit (3) is completed, the prepared test solution is added to the distillation flask (12), the electric heating pot (11) is started to heat the test solution, and at the same time, the isolation valves on the air inlet pipe and the reflux pipe of the condensation reflux unit (4) are opened to connect the condensation reflux unit (4) with the dew point test chamber (2) and the condensation collection unit (3); and cooling water is introduced into the condenser (41); (3) As the solution in the distillation flask boils, the acidic gas rises and enters the dew point test chamber (2) through the air inlet, and the photoelectric sensor (26) and the high-speed camera (25) are turned on; when the temperature of the condensation collection unit decreases, when droplets appear on the surface of the condensation plate 33 through the high-speed camera 25, the temperature value displayed by the second temperature sensor (31) is recorded; the power of the second electric heating belt (32) is increased by controlling the photoelectric sensor (26), and the surface temperature of the condensation plate (33) rises until the droplets disappear, and the temperature of the second temperature sensor (31) is measured again, and this is repeated 3-4 times, and the arithmetic average of all measured values ​​is taken as the dew point temperature; (4) Turn off the photoelectric sensor (26), manually control the power of the second electric heating belt (32) to reduce the surface temperature of the condensation plate below the dew point temperature, and the dew point condensate accumulates in the condensation plate (33) and enters the condensate collection chamber (35) through the condenser pipe for collection; turn on the pH meter (34) to detect the pH value of the dew point condensate in the condensate collection chamber (35).

9. The test method according to claim 8, characterized in that During the above test, part of the acidic gas entering the dew point test chamber (2) enters the condenser (41) through the second gas outlet, and after being cooled by the refrigerant in the condenser, most of it is condensed into liquid and refluxed to the multi-mouth distillation flask (12) through the reflux pipe, and a small amount of uncondensed gas enters the alkaline gas absorption tank (42) and the acidic gas absorption tank (43) in turn for waste gas absorption.

10. The test method according to claim 8, characterized in that: The dew point condensate in the condensate collection chamber (35) is sampled for chemical composition analysis, and a solution with the same composition is prepared for electrochemical corrosion experiment.

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