Cooling tower air duct outlet sampling equipment and cooling tower drift rate testing method

Abstract

The invention provides a cooling tower air duct outlet sampling device and a cooling tower drift rate test method, the sampling device comprises a constant speed sampling device, the constant speed sampling device comprises a nozzle pipe, and the nozzle pipe is filled with tightly arranged glass beads; the heating element is coated outside the nozzle pipe; the speed measuring instrument is arranged at the sampling opening of the nozzle pipe; the protractor is arranged at the downstream of the tachymeter; the collecting device is connected in series at the downstream of the nozzle pipe, and a vacuumizing device is arranged at the downstream of the collecting device. The method for testing the drift rate of the cooling tower comprises the following steps: measuring the wind speed of a plurality of sampling points by adopting the sampling equipment at the outlet of the air duct of the cooling tower, and collecting a tracer element measurement sample; synchronously adopting second sampling equipment to collect a circulating water sample; and according to the content of each tracer element in the tracer element measurement sample and the circulating water sample and the total equivalent sampling time, calculating the average drift rate and evaluating the credibility. The problems that in the prior art, small water drops cannot be captured, the measurement accuracy is low, and operation is tedious can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of cooling tower testing, and in particular to a cooling tower air duct outlet sampling device and a cooling tower drift rate testing method. Background Art

[0002] When the hot water in the cooling tower contacts the air to dissipate heat, part of the hot water will evaporate to form water vapor, which will carry some water droplets into the air to form drift water. The design and operating conditions of the cooling tower will also affect the drift water situation. For example, the poor effect of the drift eliminator, the uneven water distribution system, and the excessive air velocity may cause more water droplets to be taken out of the cooling tower. Since the drift water of the cooling tower will cause the loss of circulating water, increase the consumption of water resources, increase the replenishment of circulating water and the operating cost; at the same time, the drift water will carry the minerals and chemicals in the circulating water. If discharged into the environment, it may cause pollution to the surrounding soil, water sources and ecosystems. Therefore, by testing the drift water rate of the cooling tower, it is possible to evaluate whether the performance of the cooling tower meets the requirements, as well as the design, manufacturing and operation management level of the cooling tower and its impact on the environment, to detect potential problems early, and to make improvements and optimizations to reduce the drift water rate, so as to save water resources, reduce environmental pollution, improve the operating efficiency of the cooling tower, reduce operating costs, and improve economic benefits.

[0003] At present, the test method for cooling tower drift rate mainly adopts the filter paper weighing method: by using filter paper to collect the weight of cooling tower drift water within a certain period of time, the drift rate is calculated. This test method has the following defects and shortcomings:

[0004] 1. Limited measurement accuracy: On the one hand, the filter paper weighing method has limited ability to capture floating water particles (especially smaller water droplets). For water droplets of different sizes, the collection effect of the filter paper may be different, and it cannot accurately reflect the size distribution of floating water droplets, which may lead to a low measurement result of the floating water rate; on the other hand, the water absorption of the filter paper may be affected by factors such as environmental humidity and temperature, thus affecting the accuracy of the measurement;

[0005] 2. The measurement lacks representativeness: The filter paper can only collect the drift water at a specific location, which may not represent the drift water situation of the entire cooling tower, resulting in a lack of representativeness in the measurement results;

[0006] 3. Complicated operation: The filter paper weighing method requires regular replacement of filter paper and weighing operations, which is relatively cumbersome and increases the workload and time cost of the test;

[0007] 4. Unable to monitor in real time: The filter paper weighing method usually measures after a period of time, and cannot monitor the changes in the bleaching rate in real time, which has certain limitations in timely discovering and solving problems. Summary of the invention

[0008] The purpose of the present invention is to overcome the defects of the prior art and provide a cooling tower duct outlet sampling device and a cooling tower drift water rate testing method, which can solve the problems in the prior art that the drift water rate test cannot capture smaller water droplets, resulting in limited measurement accuracy, cumbersome operation, and poor real-time performance.

[0009] In order to achieve the above purpose and other purposes, the present invention is implemented by including the following technical solutions: as a first aspect, the present invention proposes a cooling tower duct outlet sampling device, including a constant speed sampling device, including a nozzle tube, which is filled with closely arranged glass beads; a heating element, coated on the outside of the nozzle tube; a speed meter, arranged at the sampling port of the nozzle tube; a protractor, arranged downstream of the speed meter; a collecting device, connected in series downstream of the nozzle tube, and a vacuum pumping device is arranged downstream thereof.

[0010] This scheme ensures that all the drift water can be evaporated in the nozzle tube by arranging a nozzle tube with built-in glass beads and coated with a heating element in the isokinetic sampling device, preventing the tracer in the water droplets from being deposited on the glass beads, thereby improving the test accuracy of the drift water rate; at the same time, by arranging a vacuum device downstream of the collection device, all local drift water samples, including smaller water droplets, can be collected by vacuuming, thereby improving the capture ability of drift water particles.

[0011] In one embodiment, the length of the nozzle tube is at least 80 mm.

[0012] This solution can save nozzle tube material while ensuring that its length can meet the arrangement of other components on or around it, and ultimately meet the requirement that the collected airflow can be completely evaporated after being heated in the tube.

[0013] In one embodiment, the isokinetic sampling device further includes a temperature sensor, and the temperature sensor is disposed at the sampling port of the nozzle tube.

[0014] The temperature sensor of this solution can be a platinum resistance temperature sensor, which is used to measure the temperature of the sampling point to understand the working effectiveness of the heating element. The platinum resistance temperature sensor has the characteristics of high precision and high stability, which can improve the accuracy of temperature monitoring.

[0015] In one embodiment, the temperature sensor and the speed meter are suspended on a connecting pipe section between a delivery pipeline and the nozzle pipe through a bracket, and the delivery pipeline connects the nozzle pipe and a collecting device.

[0016] The design of this scheme can ensure that the temperature sensor and the velocimeter remain relatively still with the sampling port of the nozzle tube, so that after the device is arranged for the first time, the measurement of all sampling points can be completed at one time by moving the position of the nozzle, which simplifies the operation and saves test time;

[0017] In one embodiment, the isokinetic sampling device further comprises an integrated box, the integrated box is arranged downstream of the protractor, and the temperature sensor is electrically connected to the integrated box.

[0018] The integrated box design of this solution can cooperate with the anemometer to measure air flow rate and display test data such as wind speed, temperature, angle, etc., making it convenient for the tester to read the test data.

[0019] As a second aspect, the present invention provides a cooling tower drift rate testing method, comprising the steps of:

[0020] S1, determine whether the operating conditions of the cooling tower meet the test conditions, if so, proceed to step S2;

[0021] S2. Using the cooling tower wind duct outlet sampling device as described in the first aspect to measure the wind speed at multiple sampling points at the cooling tower wind duct outlet and collect tracer element measurement samples; simultaneously using a second sampling device to collect circulating water samples at the hot water inlet of the cooling tower;

[0022] S3, calculating the average water bleaching rate according to the content of each tracer element in the tracer element determination sample and the circulating water sample and the total equivalent sampling time;

[0023] S4. Evaluate the credibility of the average water drift rate by calculating the isokinetic percentage.

[0024] This solution can complete real-time sampling and drift water rate determination. It is easy to operate, has strong drift water collection ability, strong environmental adaptability, is basically not affected by the humidity and temperature of the environment, and the measurement results are highly accurate and reliable.

[0025] In one embodiment, the total equivalent sampling time is the sum of the equivalent sampling time of each sampling point, and the equivalent sampling time of a certain sampling point is adjusted by adjusting the nominal sampling time of each sampling point according to the angle measured by the protractor.

[0026] The design of this solution can eliminate the angle deviation during sampling, avoid the influence of the change of air direction at the cooling tower outlet on the test results, ensure that the sample flow collected is of constant speed, and improve the accuracy of measurement.

[0027] In one embodiment, the method for calculating the constant velocity percentage comprises the steps of:

[0028] S41, calculating the air velocity at each sampling point according to the reading of the anemometer;

[0029] S42, calculating the equivalent sampling time of each sampling point according to the reading of the protractor;

[0030] S43, calculating the sample velocity of each sampling point according to the sample volume flow rate of each sampling point and the sampling port area of ​​the nozzle tube;

[0031] S44. Calculate the isokinetic percentage of the sample at each sampling point and the isokinetic percentage of the overall sample based on the air velocity, equivalent sampling time and sample velocity; if the isokinetic percentage of the sample at each sampling point and the isokinetic percentage of the overall sample are both within the range of 90% to 110%, the average water drift rate is credible; otherwise, the average water drift rate is unreliable and should be retested.

[0032] This design can ensure that the measurement results of the average bleaching rate are accurate and reliable, which helps to find problems in time and take corresponding measures.

[0033] In one embodiment, the concentration of tracer elements in the ambient air background sample is measured simultaneously with step S2 to evaluate the credibility of the average water bleaching rate.

[0034] This solution can monitor ambient air samples to avoid potential impacts, help detect problems in a timely manner and take appropriate measures.

[0035] In one embodiment, the thermal performance test is performed simultaneously with the step S2.

[0036] This solution can realize the simultaneous implementation of different performance tests of the cooling tower and save overall testing time.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The sampling device provided by the present invention can be directly installed at the sampling point of the cooling tower air duct outlet to complete real-time sampling and drift water rate determination. It has a simple and ingenious structure, is easy to operate, and has a strong drift water collection capacity;

[0039] 2. The sampling device provided by the present invention can perform sampling at multiple sampling points, which can more comprehensively represent the drifting water condition of the entire cooling tower, making the measurement results more representative; after the device is arranged for the first time, the measurement of all sampling points can be completed at one time by moving the position of the nozzle. Only samples need to be collected on site without any weighing and calculation work, which saves test time;

[0040] 3. The water bleaching rate test method provided by the present invention has strong environmental adaptability and is basically not affected by the humidity and temperature of the environment. It monitors the ambient air samples at the same time to avoid potential impacts; real-time monitoring of ambient air samples, circulating water samples, and the speed and direction of the sampling points helps to discover problems in a timely manner and take corresponding measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Shown is a schematic structural diagram of a cooling tower air duct outlet sampling device according to the present invention.

[0042] Figure 2 Shown is a schematic diagram of the steps of a cooling tower drift rate testing method of the present invention. DETAILED DESCRIPTION

[0043] Please refer to the attached Figure 1-2 The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0044] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for the technical personnel in this field to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportion relationship or adjustment of the size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0045] In the present invention, the serial numbers assigned to the components, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" mentioned in the present invention includes direct and indirect connections unless otherwise specified. The terms "include", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, and may include other elements not explicitly listed in addition to those listed.

[0046] The overall idea of ​​the technical solution provided by the present invention is as follows: The present invention provides a cooling tower drift rate test method, comprising the steps of:

[0047] S1, determine whether the operating conditions of the cooling tower meet the test conditions, if so, proceed to step S2;

[0048] S2. Using the cooling tower wind duct outlet sampling device as described in the first aspect to measure the wind speed at multiple sampling points at the cooling tower wind duct outlet and collect tracer element measurement samples; simultaneously using a second sampling device to collect circulating water samples at the hot water inlet of the cooling tower;

[0049] S3, calculating the average water bleaching rate according to the content of each tracer element in the tracer element determination sample and the circulating water sample and the total equivalent sampling time;

[0050] S4. Evaluate the credibility of the average water drift rate by calculating the isokinetic percentage.

[0051] The main idea is: by sucking a part of the cooling tower outlet airflow into the cooling tower duct outlet sampling device at the same speed and direction as the local speed of the cooling tower (constant speed), the circulating water is collected while measuring the duct outlet, and after the test is completed, the tracer element is quantitatively analyzed for the samples of the duct outlet, circulating water, etc., so as to calculate the actual drift rate of the cooling tower. The present invention is basically not affected by the humidity and temperature of the environment; sampling can be performed at multiple sampling points, which can more comprehensively represent the drift status of the entire cooling tower, making the measurement results more representative; after the device is arranged for the first time, the measurement of all sampling points can be completed at one time by moving the position of the nozzle tube, and only samples need to be collected on site, and no weighing and calculation work is performed, saving test time; in addition, real-time monitoring of the circulating water sample, the speed and direction of the sampling point are helpful to timely discover problems and take corresponding measures.

[0052] After introducing the basic principles of the present invention, various non-limiting implementation methods of the present invention will be specifically described below in conjunction with the accompanying drawings.

[0053] Embodiment 1

[0054] like Figure 1 As shown, the present invention provides a cooling tower duct outlet sampling device, comprising a constant speed sampling device 100, a collecting device 200 and a vacuum device 300 connected in series from upstream to downstream, and a control device 400 electrically connected to the constant speed sampling device 100, the collecting device 200 and the vacuum device 300 respectively.

[0055] The isokinetic sampling device 100 includes a nozzle tube 110, a heating element 120, a temperature sensor 130 and a flow velocity and direction measuring mechanism. The nozzle tube 110 is used to collect the airflow at the outlet of the cooling tower duct. Its length is at least 80 mm to ensure that the length can meet the arrangement of other components on or around it, and finally meet the requirement that the collected airflow can be completely evaporated after being heated in the tube. The nozzle tube 110 is filled with glass beads, and the glass beads are closely arranged; the heating element 120 is coated on the outside of the nozzle tube 110, such as an electric heating alloy mesh, for heating the nozzle tube 110, ensuring that the glass beads in the nozzle tube 110 can maintain a sufficient temperature, so as to evaporate the water that hits its external surface, and prevent the tracer in the water droplets from being deposited on the glass beads and thus affecting the test results of the floating water rate. The temperature sensor 130 can be a platinum resistance temperature sensor, which is arranged at the sampling port of the nozzle tube 110 and is used to measure the temperature of the sampling point. The flow velocity and direction measuring mechanism includes an anemometer 141, a protractor 142 and an integrated box 143. The anemometer 141 is arranged at the sampling port of the nozzle tube 110 and is used to measure the flow velocity at the sampling point. In this embodiment, the anemometer 141 adopts a pitot tube. In some other embodiments, the anemometer 141 can also adopt a propeller anemometer. The integrated box 143 is connected to the anemometer 141 and is used to cooperate with the anemometer 141 to measure the air flow velocity and display the test results. The protractor 142 is arranged between the anemometer 141 and the integrated box 143 and is used to measure the angle between the sample flow direction and the normal of the sampling plane. The measurement result page can be displayed on the panel of the integrated box 143.

[0056] Furthermore, the temperature sensor 130 can also be electrically connected to the integrated box 143, and its measurement result can be displayed on the panel of the integrated box 143. The temperature sensor 130 and the speed meter 141 can be suspended on the connecting pipe section of the delivery pipeline 152 and the nozzle pipe 110 through the bracket 151, so that the temperature sensor 130 and the speed meter 141 and the sampling port of the nozzle pipe 110 remain relatively still.

[0057] The collecting device 200 is connected in series with the nozzle pipe 110 through the delivery pipeline 152 and is located downstream of the nozzle pipe 110. The collecting device 200 includes a filter assembly for collecting tracer elements (such as calcium, magnesium, sodium, potassium and other mineral elements) in the sample. A vacuum pipeline 310 is provided downstream of the collecting device 200. The vacuum device 300 can collect all local drifting and discharged samples, including smaller water droplets, by vacuuming, thereby improving the ability to capture drifting water particles.

[0058] Embodiment 2

[0059] like Figure 2 As shown, the present invention also provides a cooling tower drift rate testing method, comprising the steps of:

[0060] S1, determine whether the operating conditions of the cooling tower meet the test conditions, if so, proceed to step S2;

[0061] Specifically, before testing, it is necessary to ensure that the cooling tower and related equipment are in good operating condition, such as the inlet air temperature, sampling area, circulating water flow, operating fan horsepower of mechanical ventilation cooling towers, wind speed, wet bulb temperature, dry bulb temperature, multi-unit tower operation, etc. should all meet the test restrictions. The changes in operating conditions during sampling should be kept within the specified range, especially the circulating water flow, inlet and outlet water flow, and tracer element concentration.

[0062] S2, using a first sampling device to measure the wind speed and temperature of multiple sampling points at the outlet of the wind duct of the cooling tower and collect samples for tracer element determination; simultaneously using a second sampling device to collect circulating water samples at the hot water inlet of the cooling tower;

[0063] Specifically, the first sampling device can be the cooling tower drift rate test device described in Example 1; the temperature at the sampling point is generally measured using a platinum resistance temperature sensor, and the wind speed at the sampling point can be measured using a Pitot tube or a propeller anemometer. The second sampling device can be a water sampler or a water quality analyzer. For example, a water hardness analyzer can directly measure the calcium and magnesium ion content in a water sample. Placing the second sampling device at the hot water inlet of the cooling tower can ensure that a representative circulating water sample is collected.

[0064] Furthermore, a conventional thermal performance test can be performed simultaneously with step S2, and the simultaneous performance tests of the cooling tower can save the overall test time. Specifically, the circulating water flow rate, water temperature, inlet air temperature, atmospheric pressure, fan shaft power, wind speed and other items are measured according to the conventional thermal performance test method. The thermal performance test method adopts the existing technology and will not be described here.

[0065] S3, calculating the average water bleaching rate according to the content of each tracer element in the tracer element determination sample and the circulating water sample and the total equivalent sampling time;

[0066] S31, calculating the water bleaching rate under a single tracer element according to the content of each tracer element in the tracer element determination sample and the circulating water sample and the total equivalent sampling time;

[0067] Specifically, since different tracer elements may have different methods for determining their contents, they need to be determined separately. The formula for calculating the bleaching rate based on a certain tracer element is:

[0068] Among them: AN is the sampling port area of ​​the nozzle tube of the first sampling device, in m 2 ; A SP is the cooling tower wind duct outlet area (i.e. sampling plane area), m 2 ; W T The net mass of a specified tracer element in the sample for tracer element determination is expressed in μg; Q WT is the water flow rate during the test, directly read by the flow meter of the cooling tower circulating water unit, in L / s; t e is the total equivalent sampling time (i.e. the sum of the equivalent sampling times of all sampling points), in seconds; CTC is the concentration of the specified tracer element in the circulating water sample, in ppm.

[0069] In addition, since the air direction at the outlet of the cooling tower is always changing, when the anemometer is not facing the airflow direction and there is a flow angle deviation, it will affect the results of the field test. For example, the sampling port of the anemometer is perpendicular to the sampling plane (the outlet of the wind tube of the cooling tower) but is not aligned with the airflow, then the effective speed through the sampling port will be reduced to the cosine value of the speed at the angle deviating from the normal direction, and the sample flow collected is not isovelocity, and the calculated drift rate result is unreliable. Therefore, it is necessary to make adjustments during sampling to eliminate the angle deviation. Specifically, during sampling, when there is an angle flow at the air outlet, the sampling port of the nozzle tube 110 must be aligned with the gas flow direction to ensure isovelocity sampling. When the nozzle of the nozzle tube 110 is aligned with the gas flow direction but not aligned with the sampling plane, the nominal basic sampling time is adjusted by the cosine value of the angle deviating from the normal direction to meet the needs of isovelocity and proportional sampling.

[0070] Specifically, the sampling time of each sampling point i must be adjusted from the nominal sampling time according to the angle measured by the protractor 142. The adjustment formula is as follows:

[0071] t 2，i =t 1，i ×cosθ i

[0072] Among them, t 2，i is the equivalent sampling time of a sampling point after adjusting the gas flow angle, in minutes; t 1，i is the nominal sampling time of a sampling point, in min; θ i It is the angle between the gas flow direction at a certain sampling point and the normal to the sampling plane, in degrees.

[0073] S32, averaging the bleaching rates under different tracer elements to obtain an average bleaching rate;

[0074] Specifically, for the acceptance test, each sampling point needs to be tested in parallel twice. When calculating the average water bleaching rate, the average of the two water bleaching rates under each tracer element can be calculated respectively, and then the average of the two water bleaching rate averages of all tracer elements measured can be calculated; or the average of the water bleaching rates of all tracer elements measured in a single test can be calculated first, and then the average of the water bleaching rate averages of the two tests can be calculated.

[0075] S4, evaluating the credibility of the average drift rate by calculating the isokinetic percentage;

[0076] Furthermore, in order to ensure that the result of the average water drift rate is credible, it is necessary to calculate the constant velocity percentage. The calculation process of the constant velocity percentage is as follows:

[0077] S41, calculate the air speed U at each sampling point according to the reading of the speed meter 141 s，i ;

[0078] Specifically, if an anemometer (e.g. a propeller anemometer) is used, the velocity in the direction of the flow is determined by the anemometer velocity (including calibration corrections). If a Pitot tube is used, the velocity in the direction of the flow is calculated according to the following formula:

[0079]

[0080] Among them, U s，i is the air velocity at sampling point i, in m / s; C is the calibration coefficient of the Pitot tube, dimensionless; ρ is the density of the air at the sampling point, in kg / m 3 ; ΔP s，i It is the velocity pressure when the Pitot tube is aligned in the airflow, in Pa.

[0081] S42, calculating the equivalent sampling time t2 of each sampling point according to the reading of the protractor 142, i ;

[0082] Specifically, the sampling time of each sampling point i must be adjusted from the nominal sampling time according to the angle measured by the protractor 142. The adjustment formula is as follows:

[0083] t 2，i =t 1，i ×cosθ i

[0084] Among them, t 2，i is the equivalent sampling time of a sampling point after adjusting the gas flow angle, in minutes; t 1，i is the nominal sampling time of a sampling point, in min; θ i It is the angle between the gas flow direction at a certain sampling point and the normal to the sampling plane, in degrees.

[0085] S43, calculating the sample velocity U at each sampling point according to the sample volume flow rate at each sampling point and the sampling port area of ​​the nozzle tube 110 N，i ;

[0086] Specifically, the wind speed U at the sampling point N，i The calculation formula is:

[0087] Among them: U N，i is the sample velocity at sampling point i, in m / s; Q N，i A is the sample volume flow rate at sampling point i measured by the flowmeter, in L / min; N is the sampling port area of ​​the nozzle tube 110, in m 2 ;

[0088] S44, according to the air speed U s，i , equivalent sampling time t 2，i and the sample speed U N，i Calculate the isokinetic percentage of samples at each sampling point and the percentage of isokinetics of the entire sample If IK i % or IK% and 100% constant speed deviation is less than or equal to 10%, then the average drift rate is credible; if IK i If the deviation of % or IK% from 100% isokinetic rate exceeds 10%, the average drift rate is unreliable and the test should be repeated.

[0089] S5. Use a third sampling device to collect ambient air background samples and measure the concentration of tracer elements therein to evaluate the credibility of the average water bleaching rate.

[0090] Specifically, collecting ambient air background samples should be performed simultaneously with step S2 to determine the concentration of potential tracer elements in the ambient air. The third sampling device can be a suitable ambient air filter sampler or a constant speed device that samples from the upwind direction of the cooling tower. When the potential impact of the measured tracer element concentration in the ambient air on the average water drift rate is within an allowable range, the average water drift rate is credible; otherwise, the average water drift rate is unreliable and should be retested.

[0091] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value. The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology can modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A cooling tower duct outlet sampling device, characterized in that: include Isokinetic sampling device, including a nozzle tube filled with closely arranged glass beads; A heating element, wrapped outside the nozzle tube; A velocimeter, arranged at the sampling port of the nozzle tube; a protractor, disposed downstream of the velocimeter; The collecting device is connected in series downstream of the nozzle pipe, and a vacuum pumping device is arranged downstream of the collecting device.

2. The cooling tower duct outlet sampling device according to claim 1 is characterized in that: The length of the nozzle tube is at least 80 mm.

3. The cooling tower air duct outlet sampling device according to claim 1, characterized in that: The isokinetic sampling device further comprises a temperature sensor, and the temperature sensor is arranged at the sampling port of the nozzle tube.

4. The cooling tower air duct outlet sampling device according to claim 3, characterized in that: The temperature sensor and the speed meter are hoisted on the connecting pipe section of the delivery pipeline and the nozzle pipe through a bracket, and the delivery pipeline connects the nozzle pipe and the collecting device.

5. The cooling tower air duct outlet sampling device according to claim 3, characterized in that: The isokinetic sampling device further comprises an integrated box, which is arranged downstream of the protractor, and the temperature sensor is electrically connected to the integrated box.

6. A cooling tower drift rate test method, characterized in that: Included steps S1, determine whether the operating conditions of the cooling tower meet the test conditions, if so, proceed to step S2; S2. Using the cooling tower duct outlet sampling device as described in any one of claims 1 to 5 to measure the wind speed at multiple sampling points at the cooling tower duct outlet and collect tracer element measurement samples; simultaneously using a second sampling device to collect circulating water samples at the hot water inlet of the cooling tower; S3, calculating the average water bleaching rate according to the content of each tracer element in the tracer element determination sample and the circulating water sample and the total equivalent sampling time; S4. Evaluate the credibility of the average water drift rate by calculating the isokinetic percentage.

7. The cooling tower drift rate testing method according to claim 6, characterized in that: The total equivalent sampling time is the sum of the equivalent sampling time of each sampling point, and the equivalent sampling time of a certain sampling point is adjusted to the nominal sampling time of each sampling point according to the angle measured by the protractor.

8. The cooling tower drift rate testing method according to claim 6, characterized in that: The method for calculating the constant velocity percentage comprises the steps of: S41, calculating the air velocity at each sampling point according to the reading of the anemometer; S42, calculating the equivalent sampling time of each sampling point according to the reading of the protractor; S43, calculating the sample velocity of each sampling point according to the sample volume flow rate of each sampling point and the sampling port area of ​​the nozzle tube; S44. Calculate the isokinetic percentage of the sample at each sampling point and the isokinetic percentage of the overall sample based on the air velocity, equivalent sampling time and sample velocity; if the isokinetic percentage of the sample at each sampling point and the isokinetic percentage of the overall sample are both within the range of 90% to 110%, the average water drift rate is credible; otherwise, the average water drift rate is unreliable and should be retested.

9. The cooling tower drift rate testing method according to claim 6, characterized in that: The concentration of the tracer element in the ambient air background sample is measured synchronously with step S2 to evaluate the credibility of the average water bleaching rate.

10. The cooling tower drift rate testing method according to claim 6, characterized in that: The thermal performance test is performed synchronously with step S2.

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