Rapid detection device and method for leakage of hydrocarbon substances in circulating water

Abstract

The application provides a rapid detection device and method for leakage of hydrocarbon substances in circulating water, the rapid detection device comprising a sampling unit, a gas-liquid separation unit and a detection unit which are connected in sequence through pipelines; the sampling unit comprises sampling pipelines, the inlet ends of which are connected to circulating water inlet pipelines and / or circulating water outlet pipelines of a system to be detected; the system to be detected is a circulating water system; the gas-liquid separation unit comprises a gas-liquid separation bottle and a gas conveying pipeline; the gas-liquid separation bottle is connected to the outlet end of the sampling pipeline; the gas conveying pipeline is connected to the gas outlet of the gas-liquid separation bottle; the detection unit comprises a VOCs detection device, the feeding end of which is connected to the gas outlet of the gas conveying pipeline. The rapid detection device and method can be used for pre-separation of Fischer-Tropsch products, and can conveniently sample and detect the circulating water system and rapidly determine the leakage position in a short time, and are simple and easy to operate.

Description

Technical Field

[0001] This invention belongs to the field of chemical circulating water treatment, particularly in the petrochemical and coal chemical industries. Specifically, it relates to a rapid detection device and method for hydrocarbon leakage in circulating water. Background Technology

[0002] Due to factors such as equipment manufacturing, circulating water quality management, and operating conditions, leaks of media into circulating water or vice versa are unavoidable in chemical plants' circulating water heat exchangers. After a leak, the media enters the circulating water system, leading to deterioration of the circulating water quality, which in turn exacerbates heat exchanger corrosion and scaling, affecting the normal operation of the plant.

[0003] Furthermore, water quality treatment after a leak in a circulating water system is a highly complex task. Due to the large number and variety of heat exchangers, quickly and accurately locating the leak source is the most critical issue in mitigating the risks associated with leaks. Significant material leakage can lead to a deterioration and significant fluctuations in the overall water quality of the circulating water system. Currently, the most effective and common practice in the industry is to analyze the water quality indicators of the circulating water system to identify the leaking substance, and then take water samples from each heat exchanger for extensive analysis. However, this process is time-consuming due to the large number of heat exchangers and the extensive sample collection, which can delay system response and result in a significant waste of human and financial resources. Summary of the Invention

[0004] The first objective of this invention is to provide a rapid detection device for hydrocarbon leakage in circulating water. This rapid detection device can conveniently sample and detect circulating water systems and quickly determine the location of the leak in a short time. It is simple and easy to operate.

[0005] The second objective of this invention is to provide a method for detecting hydrocarbon leaks in circulating water using the aforementioned rapid detection device. This method can quickly determine the location of the hydrocarbon leak and is simple and easy to operate.

[0006] To achieve the first objective of this invention, a rapid detection device for hydrocarbon leakage in circulating water is provided. The rapid detection device includes a sampling unit, a gas-liquid separation unit, and a detection unit, which are sequentially and sealed together via pipelines.

[0007] The sampling unit includes a sampling pipeline, the inlet of which is connected to the circulating water inlet pipeline and / or circulating water outlet pipeline of the system to be tested, respectively, for sampling the circulating water inlet and circulating water outlet of the system to be tested; the system to be tested is a circulating water system.

[0008] The gas-liquid separation unit includes a gas-liquid separation bottle and a gas delivery pipeline; the gas-liquid separation bottle is connected to the outlet end of the sampling pipeline, and is used to receive the circulating influent water sample or the circulating effluent water sample from the sampling unit, and to perform gas-liquid separation on it so that the hydrocarbon substances therein are dispersed and separated to the upper layer of the gas-liquid separation bottle; the gas delivery pipeline is connected to the gas outlet of the gas-liquid separation bottle, and is used to output the gas from the upper layer of the gas-liquid separation bottle;

[0009] The detection unit includes a VOCs detection device, the feed end of which is connected to the gas outlet of the gas pipeline, for detecting VOCs in the gas from the gas-liquid separation unit.

[0010] In the rapid detection device of the present invention, preferably, if the volume of the gas-liquid separation bottle is V, then its water inlet volume does not exceed 2 / 3V, preferably (1 / 2-2 / 3)V; and / or

[0011] The gas-liquid separator bottle is a flexible bottle.

[0012] In the rapid detection device of the present invention, preferably, the bottom of the gas-liquid separation bottle is provided with a vibration device for vibrating it to disperse and separate hydrocarbon substances in the circulating influent or circulating effluent water sample; and / or

[0013] The gas-liquid separation bottle is a handheld bottle, used to shake it by hand to separate hydrocarbon substances from the water sample that is circulating in or out of the water sample.

[0014] In the rapid detection device of the present invention, preferably, the mouth of the gas-liquid separation bottle and the stopper are connected in a sealed manner by a sealing ring, thread, or bolt; and / or

[0015] The inlet end of the sampling pipeline has a variable diameter structure.

[0016] In the rapid detection device of the present invention, preferably, the sampling unit further includes a sampling valve disposed on the sampling pipeline; and / or

[0017] The gas-liquid separation unit also includes a gas delivery valve, which is disposed on the gas delivery pipeline.

[0018] To achieve the second objective of this invention, a method for detecting hydrocarbon leakage in circulating water using the aforementioned rapid detection device is provided.

[0019] The detection method of the present invention, preferably, includes the following steps:

[0020] 1) Seal and connect the inlet end of the sampling pipeline in the sampling unit to the circulating water inlet pipeline and / or circulating water outlet pipeline of the system to be tested.

[0021] 2) The sampling unit samples the circulating influent and circulating effluent of the system to be tested through the sampling pipeline and then transports them to the gas-liquid separation bottle in the gas-liquid separation unit for gas-liquid separation. This allows hydrocarbons in the circulating influent or circulating effluent sample to escape and separate to the upper layer of the gas-liquid separation bottle, and then transport them through the gas pipeline to the VOCs detection device in the detection unit for VOCs content detection.

[0022] 3) Let the detection result of VOCs content in the circulating influent of the system to be tested be a mg / L, and the detection result of VOCs content in the circulating effluent of the system to be tested be b mg / L. Calculate the VOCs change rate γ according to the formula γ=(ba) / a×100%.

[0023] If γ≤5%, then it is determined that there is no hydrocarbon leakage in the system to be tested;

[0024] If γ = 5-10%, then the system under test is determined to have a micro-leakage of hydrocarbon substances.

[0025] If γ = 10-15%, then the system under test is determined to have a slight leakage of hydrocarbon substances.

[0026] If γ > 15%, then the system under test is determined to have a serious hydrocarbon leak.

[0027] In the detection method of the present invention, preferably, in step 2), the gas-liquid separation involves vibrating or hand-shaking the gas-liquid separation bottle to separate hydrocarbons from the circulating influent or effluent water sample; preferably, the vibration or hand-shaking rate is 2-10 times / s; preferably, the vibration or hand-shaking is performed in 5s time units, and then the gas supply valve is opened to detect the corresponding VOCs content. After the detection result is obtained, the gas supply valve is closed, and the aforementioned process is repeated until the change in the detected VOCs content within two adjacent time units is within ±1%, which is the detection endpoint.

[0028] The detection method of the present invention, preferably, involves first taking the circulating water system to be tested as the system to be tested and performing the tests according to steps 1) to 3).

[0029] Once a leak of hydrocarbons in the circulating water system is detected by γ, each primary circulating water subsystem within the circulating water system is then tested according to steps 1) to 3).

[0030] After identifying the first-level circulating water subsystem with hydrocarbon leakage by using the γ of each first-level circulating water subsystem, the second-level circulating water subsystems within the leaking first-level circulating water subsystem are then used as the systems to be tested according to steps 1) to 3). The second-level circulating water subsystem with hydrocarbon leakage is identified by using the γ of each second-level circulating water subsystem.

[0031] This process continues until each of the (n+1)th level circulating water subsystems within the nth level circulating water subsystem with hydrocarbon leakage is a single heat exchanger circulating water system. Then, each heat exchanger circulating water system within the nth level circulating water subsystem with hydrocarbon leakage is taken as the system to be tested and tested according to steps 1) to 3). The heat exchanger with hydrocarbon leakage is determined by the γ value of the circulating water system of each heat exchanger.

[0032] The detection method of the present invention preferably involves, after determining that a heat exchanger is leaking hydrocarbon substances, performing TOC content detection and / or COD content detection on its circulating influent and circulating effluent respectively, to verify that there is indeed a hydrocarbon substance leak.

[0033] The detection method of the present invention preferably verifies the existence of a hydrocarbon leak when the TOC content in the circulating effluent of a heat exchanger where a hydrocarbon leak is identified is more than 10% higher than the TOC content in its circulating influent; and / or

[0034] When the COD content in the circulating water of a heat exchanger where a hydrocarbon leak is identified is more than 10% higher than the COD content in its circulating influent, it is confirmed that a hydrocarbon leak does exist.

[0035] The beneficial effects of this invention are as follows:

[0036] The present invention provides a rapid detection device for hydrocarbon leakage in circulating water and a method for detecting hydrocarbon leakage in circulating water using the same device. This device can quickly and accurately detect the leak source heat exchanger, significantly shortening the detection cycle while improving the accuracy of the investigation; it reduces the need for analysis of substances such as COD, TOC, hydrocarbons, and oils, saving manpower, material resources, financial resources, and time; it shortens system detection time, reducing the impact of leakage on the circulating water system and chemical plants; and it enables online rapid location of the leak source under heat exchanger operating conditions. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a rapid detection device for hydrocarbon leakage in circulating water according to one embodiment of the present invention; wherein,

[0038] 1-System to be tested; 11-Circulating water inlet pipeline; 12-Circulating water outlet pipeline; 13-Circulating water inlet spray; 14-Circulating water outlet spray; 2-Sampling unit; 21-Sampling pipeline; 22-Sampling valve; 3-Gas-liquid separation unit; 31-Gas-liquid separation bottle; 32-Gas delivery pipeline; 33-Gas delivery valve; 4-Detection unit; 41-VOCs detection device. Detailed Implementation

[0039] The technical solution and its effects of the present invention will be further described below with reference to specific embodiments / examples. The following embodiments / examples are only for illustrating the content of the present invention, and the invention is not limited to the following embodiments or examples. Simple modifications made to the present invention based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0040] This invention provides a rapid detection device for hydrocarbon leakage in circulating water, such as... Figure 1 As shown, the rapid detection device includes a sampling unit 2, a gas-liquid separation unit 3, and a detection unit 4, which are sequentially and sealed together by pipelines; wherein,

[0041] The sampling unit 2 includes a sampling pipeline 21, the inlet of which is connected to the circulating water inlet pipeline 11 and / or the circulating water outlet pipeline 12 of the system to be tested 1, respectively, for sampling the circulating water inlet and circulating water outlet of the system to be tested 1; the system to be tested 1 is a circulating water system.

[0042] The gas-liquid separation unit 3 includes a gas-liquid separation bottle 31 and a gas delivery line 32. The gas-liquid separation bottle 31 is connected to the outlet end of the sampling line 21 and is used to receive the circulating influent water sample or the circulating effluent water sample from the sampling unit 2, and to perform gas-liquid separation on it so that the hydrocarbon substances therein are dispersed and separated to the upper layer of the gas-liquid separation bottle 31. The gas delivery line 32 is connected to the gas outlet of the gas-liquid separation bottle 31 and is used to output the gas from the upper layer of the gas-liquid separation bottle 31.

[0043] The detection unit 4 includes a VOCs detection device 41, whose feed end is connected to the gas outlet of the gas pipeline 32, for detecting VOCs in the gas from the gas-liquid separation unit 3.

[0044] The present invention provides a rapid detection device for hydrocarbon leaks in circulating water, which can quickly and accurately detect the leak source heat exchanger, greatly shortening the detection cycle while improving the accuracy of investigation; reducing the analysis of a large amount of substances such as COD, TOC, hydrocarbons, and oils, saving manpower, material resources, financial resources, and time; shortening the system detection time, reducing the impact of leaks on circulating water systems and chemical plants; and enabling online rapid location of leak sources under heat exchanger operating conditions.

[0045] Those skilled in the art will understand that a circulating water inlet spray 13 is installed on the circulating water inlet pipeline 11; and a circulating water outlet spray 14 is installed on the circulating water outlet pipeline 12. VOCs are volatile organic compounds.

[0046] In one embodiment, the inlet end of the sampling pipeline 21 is connected to the circulating water inlet spray 13 and / or the circulating water outlet spray 14, respectively.

[0047] Those skilled in the art will understand that, in order to facilitate installation and disassembly, in one embodiment, the inlet end of the sampling pipeline 21 is configured as a variable diameter structure for quick and airtight connection with the circulating water inlet spray 13 and / or the circulating water outlet spray 14, thereby enabling its rapid installation and disassembly.

[0048] Those skilled in the art will understand that the mouth and stopper of the gas-liquid separator 31 can be sealed using common methods. In one embodiment, the mouth and stopper of the gas-liquid separator 31 are sealed using a sealing ring, threads, or bolts.

[0049] To allow hydrocarbons in the circulating inlet or outlet water sample of the gas-liquid separation bottle 31 to dissipate, sufficient space is required; therefore, the sample size cannot be too large. In one embodiment, if the volume of the gas-liquid separation bottle 31 is V, then its inlet water volume shall not exceed 2 / 3V, preferably (1 / 2-2 / 3)V, such as 0.55V, 0.6V, and 0.65V.

[0050] In one embodiment, the gas-liquid separation bottle 31 is a flexible bottle, such as a flexible water bottle or a flexible gas bottle, which is lightweight, easy to grip, made of readily available and low-cost materials, not easily damaged, and easy to move.

[0051] Those skilled in the art will understand that the gas-liquid separation bottle 31 is primarily used for gas-liquid separation of the circulating influent or effluent water sample, thereby separating hydrocarbons from the water body. To ensure the hydrocarbons are separated from the water body more completely and quickly, in one embodiment, a vibration device is provided at the bottom of the gas-liquid separation bottle 31 to vibrate it and separate the hydrocarbons from the circulating influent or effluent water sample; and / or

[0052] The gas-liquid separation bottle 31 is a handheld bottle, which is used to shake it by hand to separate hydrocarbon substances from the water sample that is circulating in or out of the water sample.

[0053] In one embodiment, the sampling unit 2 further includes a sampling valve 22, which is disposed on the sampling pipeline 21; and / or

[0054] The gas-liquid separation unit 3 also includes a gas delivery valve 33, which is disposed on the gas delivery pipeline 32.

[0055] Those skilled in the art will understand that only one sampling line can be installed, first connected to the circulating water inlet line to collect circulating water, then subjected to gas-liquid separation and detection, before the sampling line is disassembled and reinstalled to collect circulating water outlet water. Alternatively, for rapid sampling and detection, two sampling lines can be installed simultaneously, or even two gas-liquid separation bottles and two VOCs detection devices can be installed to independently sample, separate, and detect circulating water inlet and circulating water samples. However, the rapid detection device of this application is relatively convenient and quick to disassemble and install, and there is no need to repeatedly set up related structures and increase costs.

[0056] Given the convenience of on-site testing, the rapid testing device is preferably a handheld device, and more preferably a rechargeable device.

[0057] This invention also provides a method for detecting hydrocarbon leakage in circulating water using the aforementioned rapid detection device, comprising the following steps:

[0058] 1) Seal and connect the inlet end of the sampling pipeline 21 in the sampling unit 2 to the circulating water inlet pipeline and / or circulating water outlet pipeline of the system to be tested.

[0059] 2) The sampling unit 2 samples the circulating inlet and circulating outlet water of the system to be tested through the sampling pipeline 21 and then transports them to the gas-liquid separation bottle 31 in the gas-liquid separation unit 3 for gas-liquid separation. This allows hydrocarbon substances in the circulating inlet or circulating outlet water sample to escape and separate to the upper layer of the gas-liquid separation bottle 31, and then transport them through the gas transmission pipeline 32 to the VOCs detection device 41 in the detection unit 4 for VOCs content detection.

[0060] 3) Let the detection result of VOCs content in the circulating influent of the system to be tested be a mg / L, and the detection result of VOCs content in the circulating effluent of the system to be tested be b mg / L. Calculate the VOCs change rate γ according to the formula γ=(ba) / a×100%.

[0061] If γ≤5%, then it is determined that there is no hydrocarbon leakage in the system to be tested;

[0062] If γ = 5-10%, then the system under test is determined to have a micro-leakage of hydrocarbon substances.

[0063] If γ = 10-15%, then the system under test is determined to have a slight leakage of hydrocarbon substances.

[0064] If γ > 15%, then the system under test is determined to have a serious hydrocarbon leak.

[0065] Those skilled in the art will understand that in step 2), the circulating influent sample and the circulating effluent sample are sequentially fed into the gas-liquid separation bottle 31 for gas-liquid separation, and the upper gas layer after separation is sent to the detection unit for detection. For example, the circulating influent sample is first taken, fed into the gas-liquid separation bottle 31 for gas-liquid separation, and the upper gas layer after separation is sent to the detection unit for detection. After the detection result is obtained, the circulating effluent sample is then taken, fed into the gas-liquid separation bottle 31 for gas-liquid separation, and the upper gas layer after separation is sent to the detection unit for detection.

[0066] The detection method of the present invention can shorten the detection time of a single heat exchanger to less than 1 minute, that is, it can determine whether the heat exchanger is leaking within 1 minute.

[0067] In one embodiment, in step 2), the gas-liquid separation involves vibrating or hand-shaking the gas-liquid separation bottle 31 to separate hydrocarbons from the circulating influent or effluent water sample. Preferably, the vibration or hand-shaking rate is 2-10 times / s, such as 3 times / s, 4 times / s, 5 times / s, 6 times / s, 7 times / s, 8 times / s, and 9 times / s. Preferably, after vibrating or hand-shaking in 5-second time units, the gas supply valve 33 is opened to detect the corresponding VOCs content. After the detection result is obtained, the gas supply valve 33 is closed, and the aforementioned process is repeated until the change in the detected VOCs content within two adjacent time units is within ±1%, which is the detection endpoint.

[0068] Those skilled in the art will understand that the gas-liquid separation bottle 31 can be vibrated or shaken by hand at any angle or in any direction, such as vertical, horizontal, or tilted, as long as the hydrocarbon substances inside can be separated from the circulating influent or effluent water sample.

[0069] In one embodiment, the detection method first takes the circulating water system to be tested as the system to be tested and performs the test according to steps 1) to 3).

[0070] Once a leak of hydrocarbons in the circulating water system is detected by γ, each primary circulating water subsystem within the circulating water system is then tested according to steps 1) to 3).

[0071] After identifying the first-level circulating water subsystem with hydrocarbon leakage by using the γ of each first-level circulating water subsystem, the second-level circulating water subsystems within the leaking first-level circulating water subsystem are then used as the systems to be tested according to steps 1) to 3). The second-level circulating water subsystem with hydrocarbon leakage is identified by using the γ of each second-level circulating water subsystem.

[0072] This process continues until each of the (n+1)th level circulating water subsystems within the nth level circulating water subsystem with hydrocarbon leakage is a single heat exchanger circulating water system. Then, each heat exchanger circulating water system within the nth level circulating water subsystem with hydrocarbon leakage is taken as the system to be tested and tested according to steps 1) to 3). The heat exchanger with hydrocarbon leakage is determined by the γ value of the circulating water system of each heat exchanger.

[0073] Those skilled in the art will understand that the size of n is related to the number of stages in the multi-stage subsystems within the circulating water system.

[0074] Those skilled in the art will understand that when testing various subsystems at the same level, multiple sets of the aforementioned rapid testing devices can be used to perform parallel testing on each subsystem; alternatively, one set of the aforementioned rapid testing device can be used to test one subsystem at the same level, then the rapid testing device can be removed and installed on another subsystem at the same level for testing, and so on, which is equivalent to testing each subsystem at the same level sequentially using the same set of rapid testing devices. Since the rapid testing device of this application has a short single testing time and is easy to disassemble and install, testing with only one set does not take long, eliminating the need to use multiple sets and increase testing costs.

[0075] The rapid detection device and corresponding detection method of this invention can shorten the detection time of a single heat exchanger to less than 1 minute, meaning that the presence or absence of a leak in the heat exchanger can be determined within 1 minute. The detection time required for the entire system depends mainly on the number of rapid detection devices used and the number of tests required (the number of tests is related to the number of stages in the multi-level subsystems of the circulating water system and the number of individual heat exchangers in the last stage), but the specific leak location of the entire system can be determined within a maximum of one hour. Compared to the prior art, which requires several days or even tens of days to obtain test results by sampling and analyzing the inlet and outlet water of each heat exchanger in each level of the circulating water subsystem, and the results are not necessarily accurate, this application greatly improves the detection speed and accuracy, significantly increases detection efficiency, avoids continuous leakage due to the inability to detect hydrocarbon leaks in a timely manner, thus preventing the impact of continuous leakage on the quality of the circulating water and reducing the number of times the circulating water needs to be treated.

[0076] In one implementation, after determining that a heat exchanger is leaking hydrocarbons, the TOC content and / or COD content of its circulating influent and circulating effluent are tested respectively to verify that there is indeed a hydrocarbon leak.

[0077] In one implementation, when the TOC content in the circulating effluent of a heat exchanger where a hydrocarbon leak is identified is more than 10% higher than the TOC content in its circulating influent, a hydrocarbon leak is confirmed; and / or

[0078] When the COD content in the circulating water of a heat exchanger where a hydrocarbon leak is identified is more than 10% higher than the COD content in its circulating influent, it is confirmed that a hydrocarbon leak does exist.

[0079] Those skilled in the art will understand that TOC refers to Total Organic Carbon and COD refers to Chemical Oxygen Demand. The verification steps are only to further confirm the accuracy of the rapid detection device of this invention, so as to obtain certification documents for repairs, such as leak sealing or switching to a backup heat exchanger.

[0080] The present invention will be further illustrated below with specific embodiments and comparative examples.

[0081] Example 1 (S1)

[0082] In July 2020, the circulating water in the tower's water tank of a coal chemical project turned whitish. Subsequently, the circulating water system of the coal chemical project was selected as the system to be tested. Figure 1 The rapid detection device shown is used to detect hydrocarbon leaks. The detection method is as follows:

[0083] 1) The inlet end of the sampling pipeline 21 in the sampling unit 2 is respectively sealed and connected to the circulating water inlet pipeline and / or circulating water outlet pipeline of the system to be tested 1;

[0084] 2) The sampling unit 2 samples the circulating water (water from the main water supply pipe) and circulating water (water from the return water pipe) of the system to be tested 1 through the sampling pipeline 21, and then transports them to the gas-liquid separation bottle 31 in the gas-liquid separation unit 3 for gas-liquid separation. This allows hydrocarbon substances in the circulating water sample or circulating water sample to escape and separate to the upper layer of the gas-liquid separation bottle 31, and then transport them through the gas transmission pipeline 32 to the VOCs detection device 41 in the detection unit 4 for VOCs content detection.

[0085] 3) Let the detection result of VOCs content in the circulating influent of the system to be tested be a mg / L, and the detection result of VOCs content in the circulating effluent of the system to be tested be b mg / L. Calculate the VOCs change rate γ according to the formula γ=(ba) / a×100%.

[0086] If γ≤5%, then it is determined that there is no hydrocarbon leakage in the system to be tested 1;

[0087] If γ = 5-10%, then the hydrocarbon micro-leakage of the system to be detected is determined;

[0088] If γ = 10-15%, then the hydrocarbon substance in the system to be detected is determined to be slightly leaked;

[0089] If γ > 15%, then the hydrocarbon substance in the system to be detected is determined to be seriously leaked.

[0090] The test results are shown in Table 1.

[0091] Table 1. Detection results of Example 1

[0092]

[0093] According to the data in Table 1, the VOCs change rate γ of the circulating water system of this project is 500.2%, which is much greater than 15% and far exceeds the serious leakage control index, indicating that a serious leak has occurred in the heat exchanger of the circulating water system of this project.

[0094] Example 2 (S2)

[0095] Based on Example 1 (S1), the leakage location of the aforementioned project's circulating water system is further detected. The circulating water systems of the four sets of devices within the aforementioned project's circulating water system are considered its first-level circulating water subsystems, and these four sets of devices are used sequentially as the system to be tested (system 1) using methods such as... Figure 1 The rapid detection device shown was used to detect hydrocarbon leaks, and the detection method was the same as in Example 1 (S1). The detection results are shown in Table 2.

[0096] Table 2 Detection results of Example 2

[0097]

[0098] According to the data in Table 2, the VOCs change rate γ in the circulating water of the MTO unit, olefin separation unit, and polyethylene unit is less than 5%, indicating that there is no leakage in the circulating water systems of these three units. However, the VOCs change rate γ in the circulating water of the polypropylene unit reaches 3970.9%, which is much greater than 15% and far exceeds the serious leakage control index, indicating that there is a serious heat exchanger leakage in the circulating water system of the polypropylene unit.

[0099] Example 3 (S3)

[0100] Based on Example 2 (S2), the leakage location of the circulating water system of the polypropylene unit in the aforementioned project is further detected; wherein, the circulating water system of the polypropylene unit in the aforementioned project has 5 heat exchangers, namely E912, E911A, E911, E256 and E206; the circulating water system of the aforementioned 5 heat exchangers is used as the system to be tested 1 in sequence, using as follows Figure 1 The rapid detection device shown was used to detect hydrocarbon leaks, and the detection method was the same as in Example 1 (S1). The detection results are shown in Table 3.

[0101] Table 3. Detection results of Example 3

[0102]

[0103]

[0104] According to the data in Table 3, in the circulating water system of the polypropylene unit of this project, the VOCs content in the influent and effluent of the four heat exchangers (E912, E911A, E911, and E256) did not change significantly, with a VOCs change rate γ < 5%, indicating that the circulating water systems of these four heat exchangers did not experience leaks. However, the VOCs change rate γ in the influent and effluent of the circulating water system of heat exchanger E206 reached 10038.6%, far exceeding 15%, and far exceeding the severe leak control index, indicating that the circulating water system of heat exchanger E206 experienced a severe leak. Ultimately, the final leaking heat exchanger affecting the circulating water system of this project was quickly located.

[0105] Example 4 (S4)

[0106] First, the circulating water system of the project was tested according to Example 1 (S1), and it was determined that there was a leak of hydrocarbon substances based on the corresponding γ.

[0107] Then, the circulating water systems (first-stage circulating water subsystems) of the four units in the project were tested in sequence according to Example 2 (S2). Based on the corresponding γ, it was determined that the circulating water system of the polypropylene unit was the one with leaking hydrocarbon substances.

[0108] Then, in accordance with Example 3 (S3), the circulating water systems of the four heat exchangers in the polypropylene unit of the project (the circulating water system of a single heat exchanger, i.e. the last stage circulating water subsystem) were tested in sequence. Based on the corresponding γ, it was determined that the E206 heat exchanger was the one with hydrocarbon leakage.

[0109] Example 5 (S5)

[0110] Based on Example 4 (S4), the TOC content and COD content of the circulating water inlet and circulating water of the E206 heat exchanger were detected, respectively, and the results are shown in Table 4.

[0111] Table 4. Detection results of Example 5

[0112]

[0113]

[0114] According to the data in Table 4, the TOC content in the circulating effluent is 82.1 mg / L and the COD content is 216.3 mg / L, while the TOC content in the circulating influent is 2.2 mg / L and the COD content is 9.3 mg / L. The TOC content in the circulating effluent is about 3632% higher than that in the circulating influent, which is far higher than 10%, proving that there is indeed a serious leak in the circulating water system of the E206 heat exchanger. The COD content in the circulating effluent is about 2226% higher than that in the circulating influent, which is far higher than 10%, also proving that there is indeed a serious leak in the circulating water system of the E206 heat exchanger.

Claims

1. A method for detecting hydrocarbon leakage in circulating water, characterized in that, The detection method utilizes a rapid detection device; the rapid detection device comprises a sampling unit (2), a gas-liquid separation unit (3), and a detection unit (4) connected in a sealed manner via pipelines; wherein, The sampling unit (2) includes a sampling pipeline (21), the inlet of which is connected to the circulating water inlet pipeline and the circulating water outlet pipeline of the system to be tested, respectively, for sampling the circulating water inlet and circulating water outlet of the system to be tested; the system to be tested is a circulating water system; The gas-liquid separation unit (3) includes a gas-liquid separation bottle (31) and a gas delivery line (32); the gas-liquid separation bottle (31) is connected to the outlet end of the sampling line (21) and is used to receive the circulating influent sample and the circulating effluent sample from the sampling unit (2) respectively, and to perform gas-liquid separation on them so that the hydrocarbon substances therein are dispersed and separated to the upper layer of the gas-liquid separation bottle (31); the gas delivery line (32) is connected to the gas outlet of the gas-liquid separation bottle (31) and is used to output the gas from the upper layer of the gas-liquid separation bottle (31); The detection unit (4) includes a VOCs detection device (41), whose feed end is connected to the gas outlet of the gas pipeline (32) for detecting VOCs in the gas from the gas-liquid separation unit (3). The detection method includes the following steps: 1) The inlet end of the sampling pipeline (21) in the sampling unit (2) is sealed and connected to the circulating water inlet pipeline and the circulating water outlet pipeline of the system to be tested; 2) The sampling unit (2) takes samples of the circulating inlet and circulating outlet of the system to be tested through the sampling pipeline (21) and then transports them to the gas-liquid separation bottle (31) in the gas-liquid separation unit (3) for gas-liquid separation, so that the hydrocarbon substances in the circulating inlet and circulating outlet samples are dispersed and separated to the upper layer of the gas-liquid separation bottle (31), and then transported through the gas pipeline (32) to the VOCs detection device (41) in the detection unit (4) for VOCs content detection; 3) Let the detection result of VOCs content in the circulating influent of the system to be tested be a mg / L, and the detection result of VOCs content in the circulating effluent of the system to be tested be b mg / L. Calculate the VOCs change rate γ according to the formula γ=(ba) / a×100%. If γ≤5%, then it is determined that there is no hydrocarbon leakage in the system to be tested; If γ = 5-10%, then the system under test is determined to have a micro-leakage of hydrocarbon substances. If γ = 10-15%, then the system under test is determined to have a slight leakage of hydrocarbon substances. If γ > 15%, then the system under test is determined to have a serious hydrocarbon leak.

2. The detection method according to claim 1, characterized in that, Let the volume of the gas-liquid separator (31) be V, then its water inlet volume shall not exceed 2 / 3V; and / or The gas-liquid separator bottle (31) is a flexible bottle.

3. The detection method according to claim 1 or 2, characterized in that, The bottom of the gas-liquid separation bottle (31) is equipped with a vibration device for vibrating it to disperse and separate hydrocarbon substances in the circulating influent or circulating effluent water sample; and / or The gas-liquid separation bottle (31) is a handheld bottle, which is used to shake it by hand to separate and disperse hydrocarbon substances in the circulating influent or circulating effluent samples.

4. The detection method according to claim 1, characterized in that, The mouth and stopper of the gas-liquid separator (31) are sealed together by a sealing ring, thread, or bolt; and / or The inlet end of the sampling pipeline (21) has a variable diameter structure.

5. The detection method according to any one of claims 1, 2, and 4, characterized in that, The sampling unit (2) further includes a sampling valve (22), which is disposed on the sampling pipeline (21); and / or The gas-liquid separation unit (3) also includes a gas delivery valve (33), which is disposed on the gas delivery pipeline (32).

6. The detection method according to claim 5, characterized in that, In step 2), the gas-liquid separation is to vibrate or shake the gas-liquid separation bottle (31) by hand to separate the hydrocarbon substances in the influent and effluent water samples.

7. The detection method according to claim 6, characterized in that, In step 2), the vibration or hand-held shaking rate is 2-10 times / s.

8. The detection method according to claim 6, characterized in that, In step 2), after vibrating or shaking the hand for 5 seconds, the gas supply valve (33) is opened to detect the corresponding VOCs content. After the result is obtained, the gas supply valve (33) is turned off, and the above process is repeated until the change in the detected VOCs content within two adjacent time units is within ±1%, which is the detection endpoint.

9. The detection method according to any one of claims 1, 2, 4 and 6-8, characterized in that, In the aforementioned detection method, the circulating water system to be tested is first used as the system to be tested, and the test is carried out according to steps 1) to 3). Once a leak of hydrocarbons in the circulating water system is detected by gamma, each primary circulating water subsystem within the circulating water system is then tested according to steps 1) to 3). After identifying the first-level circulating water subsystem with hydrocarbon leakage by using the γ of each first-level circulating water subsystem, the second-level circulating water subsystems within the leaking first-level circulating water subsystem are then used as the systems to be tested according to steps 1) to 3). The second-level circulating water subsystem with hydrocarbon leakage is identified by using the γ of each second-level circulating water subsystem. This process continues until each of the (n+1)th level circulating water subsystems within the nth level circulating water subsystem with hydrocarbon leakage is a single heat exchanger circulating water system. Then, each heat exchanger circulating water system within the nth level circulating water subsystem with hydrocarbon leakage is taken as the system to be tested and tested according to steps 1) to 3). The heat exchanger with hydrocarbon leakage is determined by the γ value of the circulating water system of each heat exchanger.

10. The detection method according to claim 9, characterized in that, After identifying a heat exchanger with a hydrocarbon leak, TOC and / or COD content tests are performed on its circulating influent and circulating effluent to verify that a hydrocarbon leak does indeed exist.

11. The detection method according to claim 10, characterized in that, When the TOC content in the circulating effluent of a heat exchanger where a hydrocarbon leak is identified is more than 10% higher than the TOC content in its circulating influent, a hydrocarbon leak is confirmed; and / or When the COD content in the circulating effluent of a heat exchanger where a hydrocarbon leak is identified is more than 10% higher than the COD content in its circulating influent, it is confirmed that a hydrocarbon leak does exist.

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