A pretreatment device and pretreatment method for an online analyzer in a chemical process

Abstract

The present invention is a pretreatment device for an online analyzer of a chemical process, comprising a controller, a container for a liquid to be tested, a circulation pump, a filter, a liquid inlet pressure sensor and a liquid outlet pressure sensor, wherein the liquid inlet pressure sensor is installed on the top of the filter, the liquid outlet pressure sensor is installed at the liquid outlet of the filter, the container for the liquid to be tested is connected with a main circulation pipeline, the circulation pump is installed on the main circulation pipeline, a liquid output pipeline is also connected to the main circulation pipeline, a liquid input pipeline is connected to the liquid output pipeline, the liquid input pipeline is connected to the liquid inlet of the filter, the filter is also connected to the container for the liquid to be tested through a return liquid pipeline, a sampling pipeline is connected to the return liquid pipeline, a first ball valve and a second ball valve are installed on the liquid output pipeline, a third ball valve is installed on the liquid input pipeline, and the liquid inlet pressure sensor and the liquid outlet pressure sensor are both connected to the controller in communication. Beneficial effects: improving detection accuracy, extending the life of the analyzer and the maintenance cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of online analysis of chemical processes. The chemical process may be a chemical surface treatment or a production process involving liquid chemicals, or may be raw water, industrial waste water, or recycled water involved in the production process. Specifically, the present invention relates to a pretreatment device and a pretreatment method for an online analyzer. Background Art

[0002] In the process of industrial production transforming from labor-intensive to technology-intensive, a large number of companies have begun to use various online analytical instruments in the past few decades to improve the degree of automation, enhance process control capabilities, reduce labor injuries, reduce labor intensity, and replace long-term manual duty.

[0003] Since online analyzers are relatively sophisticated instruments, some of their key components, such as solenoid valves, rotary valves, plunger pumps, syringe pumps, etc., are often unable to withstand large and small particle impurities or high pressure in liquid samples due to their technical and material limitations, which will cause inaccurate test results of online analyzers, thus bringing serious negative impacts on process control, and even production accidents and casualties. The reason is that large and small particles can cause blockage of pipelines or internal wear of key components, thus affecting the test results. Large particles can be inorganic or organic, or a mixture of the two. It is generally believed that particles with a particle size of more than 50 microns may cause irreversible damage or blockage of key components, and the degree of damage will vary depending on the physical properties of the particles themselves. On the other hand, when the pressure at the sampling point is greater than the maximum pressure that the inlet valve body can withstand, the valve body will be broken, and accurate sampling cannot be performed, thereby losing the accuracy of the measurement results.

[0004] At present, the pretreatment method of online analyzers in chemical processes still remains in a relatively simple method, that is, a filter is connected in series in front of the analyzer. There are some problems with this method. First, there are problems with use and maintenance. If the pore size of the filter element is too small, it is easy to block and the maintenance frequency is high, and the operator cannot find the filter blockage in time and perform maintenance. If the pore size of the filter element is large, the filtering purpose cannot be achieved, and the instrument components will be worn. Second, if the pressure at the sampling point is high, it will also affect the accuracy of the test results. Third, based on the above problems, it is impossible to achieve unattended application conditions, and personnel need to check whether the filter element is blocked regularly. Fourth, when there is no pressure in the sampling point pipeline, the pretreatment pipeline cannot identify whether the online analyzer can take samples. Fifth, because the current pretreatment method does not provide automatic update of the test liquid in the filter, the sampling of the online analyzer is not time-effective, that is, it cannot represent the current situation of the real test liquid. In order to make up for the timeliness problem, the work of liquid update can only be completed by the online analyzer. In fact, most online analyzers do not support this function. Even if they support this function, the volume that can be updated is quite different from the filter volume and pipeline volume. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a set of highly reliable automated online analyzer pretreatment solutions, which realize the functions of filtering particulate matter, reducing the pressure of pipeline pressure on the instrument valve body, providing sampling timeliness, unmanned alarm at any time, highly reliable self-diagnosis, backwashing and filter element replacement in a step-by-step easy maintenance manner.

[0006] The technical solution is as follows:

[0007] A pretreatment device for an online analyzer of a chemical process, characterized in that it comprises a controller, a container for a liquid to be tested, a circulation pump, a filter, a liquid inlet pressure sensor and a liquid outlet pressure sensor, wherein the filter has a liquid inlet, a liquid outlet, an overflow port and a sewage outlet, a sewage outlet is installed with a sewage valve at the sewage outlet, an overflow valve is installed at the overflow port, the liquid inlet pressure sensor is installed at the top of the filter, the liquid outlet pressure sensor is installed at the liquid outlet of the filter, the container for the liquid to be tested is connected to a main circulation pipeline, the circulation pump is installed on the main circulation pipeline, and the main circulation pipeline is connected to the main circulation pipeline. A liquid output pipeline is also connected to the road, and a liquid input pipeline is connected to the liquid output pipeline, and the liquid input pipeline is connected to the liquid inlet of the filter, and the liquid to be tested in the liquid container is input into the filter. The filter is also connected to the liquid container to be tested through a return liquid pipeline, and a sampling pipeline connected to the online analyzer is connected to the return liquid pipeline. A first ball valve is installed on the front section of the liquid output pipeline, and a second ball valve is installed on the rear section thereof. A third ball valve is installed on the liquid input pipeline, and the liquid inlet pressure sensor and the liquid outlet pressure sensor are both communicatively connected to the controller.

[0008] As a further improvement, the starting end of the return liquid pipeline is connected to the liquid outlet, the sampling pipeline is installed at the starting end of the return liquid pipeline, located after the liquid outlet pressure sensor, a normally closed solenoid valve is installed on the front section of the return liquid pipeline, and a fourth ball valve is installed on the rear section thereof, and the end of the liquid output pipeline is connected to the return liquid pipeline through a three-way connector.

[0009] As a further improvement, the starting end of the liquid return pipeline is installed on the overflow port, the overflow valve is installed on the front end of the liquid return pipeline, the pretreatment device also includes a circulation pool, the liquid outlet of the filter is connected to a first liquid return branch, the end of the first liquid return branch is connected to the circulation pool, and a second liquid return branch is also connected to the front section of the liquid return pipeline through a three-way connector, the end of the second liquid return branch is connected to the circulation pool, the end of the liquid output pipeline is connected to the first liquid return branch through a three-way connector, an inlet solenoid valve is also installed on the first liquid return branch, an outlet solenoid valve is also installed on the second liquid return branch, and the sampling pipeline is installed on the second liquid return branch.

[0010] As a further improvement, a liquid level meter is installed in the circulation pool, and the top of the circulation pool is also provided with an overflow port for communicating with the atmosphere.

[0011] As a further improvement, the liquid level meter is a float liquid level meter.

[0012] As a further improvement, the liquid level meter is an ultrasonic liquid level meter.

[0013] A pretreatment method for an online analyzer in a chemical process, characterized in that it comprises the following steps:

[0014] S1. Before use, you first need to open the first ball valve, the third ball valve and the overflow valve, close the second ball valve, fill the filter with the liquid to be tested, and when you observe liquid overflow at the top overflow port, close the overflow valve. In daily use, the overflow valve is in a normally closed state except for manual intervention maintenance;

[0015] S2. Judging whether the main circulation pipeline is operating normally by the pressure value of the inlet pressure sensor, so as to determine whether the start-up conditions are met and whether it meets the requirements of the filter driving force. When the requirements of the filter driving force are met, the judgment is made by observing the pressure difference between the inlet pressure sensor and the outlet pressure sensor; if the pressure difference is less than the preset value, the test liquid filtered by the filter returns to the test liquid container through the return line to continue to circulate; if the pressure difference is greater than or equal to the preset value, the side cannot continue to circulate, the controller control device stops running and alarms, opens the normally closed solenoid valve to reduce the pressure, and confirms the pressure difference between the inlet pressure sensor and the outlet pressure sensor again to judge whether the filter element of the filter is blocked;

[0016] S3. If the blockage requires manual backwashing: close the third ball valve, open the second ball valve and the first normally closed solenoid valve, and the liquid in the liquid container to be tested enters the liquid return pipeline through the liquid output pipeline, and enters the filter from the liquid return pipeline for backwashing, and finally open the drain valve to discharge the waste liquid from the drain outlet;

[0017] S4. After the waste liquid is drained, close the drain valve and the second ball valve, and open the third ball valve to allow the liquid to continue to circulate in the device. When sampling, close the normally closed solenoid valve, and the online analyzer takes samples from the sampling pipeline for analysis.

[0018] As a further improvement, a pretreatment method for an online analyzer of a chemical process comprises the following steps:

[0019] S1. Before use, you first need to open the first ball valve, the third ball valve and the overflow valve, close the second ball valve, fill the filter with the liquid to be tested, and when you observe liquid overflow at the top overflow port, close the overflow valve. In daily use, the overflow valve is in a normally closed state except for manual intervention maintenance;

[0020] S2. Judging whether the main circulation pipeline is operating normally by the pressure value of the inlet pressure sensor, so as to determine whether the start-up conditions are met and whether the requirements of the filter driving force are met. When the requirements of the filter driving force are met, the judgment is made by observing the pressure difference between the inlet pressure sensor and the outlet pressure sensor; if the pressure difference is less than the preset value, the liquid to be tested after being filtered by the filter returns to the liquid to be tested container through the return line to continue to circulate; if the pressure difference is greater than or equal to the preset value, the side cannot continue to circulate, and the controller stops the operation of the control device and alarms;

[0021] S3, keep the inlet solenoid valve in the closed state, open the outlet solenoid valve, drain the liquid in the circulation pool by gravity, check and confirm that the liquid in the circulation pool is empty, open the inlet solenoid valve and the outlet solenoid valve, and confirm the pressure difference between the inlet pressure sensor and the outlet pressure sensor to determine whether the pressure reduction is successful;

[0022] S4. If the pressure reduction is unsuccessful, it means that the filter element in the filter is clogged, and manual intervention is required to backwash the filter: close the third ball valve, open the second ball valve, and the liquid in the test liquid container enters the first liquid return branch through the liquid output pipeline, and enters the filter from the first liquid return branch for backwashing. Finally, open the drain valve to discharge the waste liquid from the drain outlet;

[0023] S5. After the waste liquid is drained, close the drain valve and the second ball valve, and open the third ball valve to allow the liquid to continue to circulate in the device. When sampling, close the outlet solenoid valve, and the online analyzer takes samples from the sampling pipeline for analysis.

[0024] Beneficial Effects

[0025] The beneficial effects are as follows: the present invention simultaneously achieves the dual purpose of filtering particulate matter and reducing the pressure of the liquid to be tested, meets the basic needs of the analyzer for the liquid to be tested, improves detection accuracy, and extends the life and maintenance cycle of the analyzer. It meets the unattended needs. If maintenance is required, such as backwashing or replacement of the filter element, real-time reminders are provided through sensors. It is usually required that the sampling point is in a circulating pipeline, that is, it has its own pressure. The pressure sensor can be used to predict the situation of the production line and achieve work synchronization with the production line, that is, when the production line is not in production, there is no pressure at the sampling point, and no pretreatment will be performed. Liquid sample sampling pays attention to timeliness, that is, each time sampling is taken, it is hoped that a sample that can represent the current state of the liquid to be tested can be obtained. The present invention provides pipeline liquid renewal and circulation in the pretreatment stage, and then the online analyzer performs sampling analysis. Through the control of the upper computer, closed-loop control is achieved to improve operational reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described below with reference to the accompanying drawings and implementation examples.

[0027] Figure 1 It is a structural schematic diagram of the present invention;

[0028] Figure 2 It is a schematic diagram of the structure of the circulation pool of the present invention.

[0029] Numbers in the figure:

[0030] 1. Test liquid container 2. Circulation pump 3. Filter

[0031] 301, night inlet 302, liquid outlet 303, overflow outlet

[0032] 304, sewage outlet 4, liquid inlet pressure sensor 5, liquid outlet pressure sensor

[0033] 6. Drain valve 7. Overflow valve 8. Main circulation pipeline

[0034] 9. Liquid output pipeline 10. Liquid input pipeline 11. Liquid return pipeline

[0035] 12. Sampling pipeline 13. First ball valve 14. Second ball valve

[0036] 15. Third ball valve 16. Normally closed solenoid valve 17. Fourth ball valve

[0037] 18. Circulation pool 1801, overflow port 19, first liquid return branch

[0038] 20. Second liquid return branch 21. Inlet solenoid valve 22. Outlet solenoid valve

[0039] 23. Liquid level meter DETAILED DESCRIPTION

[0040] In order to have a further understanding and recognition of the structural features and the effects achieved by the present invention, a preferred embodiment and accompanying drawings are used for detailed description as follows:

[0041] like Figure 1As shown, a pretreatment device for an online analyzer of a chemical process comprises a controller, a test liquid container 1, a circulation pump 2, a filter 3, a liquid inlet pressure sensor 4 and a liquid outlet pressure sensor 5. The filter 3 has a liquid inlet 301, a liquid outlet 302, an overflow port 303 and a sewage outlet 304. A sewage outlet 304 is provided with a sewage valve 6, and an overflow valve 7 is provided at the overflow port 303. The liquid inlet pressure sensor 4 is provided at the top of the filter 3, and the liquid outlet pressure sensor 5 is provided at the liquid outlet 302 of the filter 3. The test liquid container 1 is connected with a main circulation pipeline 8, and the circulation pump 2 is installed on the main circulation pipeline 8. The main circulation pipeline 8 is also connected with a liquid output pipeline 9, and the liquid output pipeline 9 is connected with a liquid input pipeline 10. The liquid input pipeline 10 is connected with the liquid inlet 301 of the filter 3, and the test liquid in the test liquid container 1 is input into the filter 3. The filter 3 is also connected with the test liquid container 1 through a liquid return pipeline 11, and the filtered liquid in the filter 3 is returned to the test liquid container, so that the test liquid circulates in this way to maintain the cleanliness of the test liquid. The liquid return pipeline 11 is connected with a sampling pipeline 12 connected with an online analyzer, and the circulating liquid is pre-detected by the online analyzer set here to ensure the sampling and analysis results of the test liquid at the detection point. A first ball valve 13 is installed on the front section of the liquid output pipeline 9 to control the liquid output. It can also control the liquid output pipeline 9 to update the liquid in the filter 3 and return it to the filter 3, so as to achieve the purpose of timeliness and representativeness of the liquid sample obtained by the sampling pipeline 12 connected to the subsequent online analyzer without additional loss of chemicals. A second ball valve 14 is installed on the rear section of the liquid output pipeline. When the filter 3 is backwashed, the second ball valve 14 needs to be opened. A third ball valve 15 is installed on the liquid input pipeline 10 to control whether the liquid in the liquid input pipeline is output to the filter 3. The liquid inlet pressure sensor 4 and the liquid outlet pressure sensor 5 are both connected to the controller for communication. The starting end of the liquid return pipeline 11 is connected to the liquid outlet 302, the sampling pipeline 12 is installed at the starting end of the liquid return pipeline 11, and is located after the liquid outlet pressure sensor 5. A normally closed solenoid valve 16 is installed on the front section of the liquid return pipeline 11, and a fourth ball valve 17 is installed on the rear section thereof. The end of the liquid output pipeline 9 is connected to the liquid return pipeline 11 through a three-way connector.

[0042] like Figure 2As shown, a pretreatment device for an online analyzer of a chemical process comprises a controller, a test liquid container 1, a circulation pump 2, a filter 3, a liquid inlet pressure sensor 4 and a liquid outlet pressure sensor 5. The filter 3 has a liquid inlet 301, a liquid outlet 302, an overflow port 303 and a sewage outlet 304. A sewage outlet 304 is provided with a sewage valve 6, and an overflow valve 7 is provided at the overflow port 303. The liquid inlet pressure sensor 4 is provided at the top of the filter 3, and the liquid outlet pressure sensor 5 is provided at the liquid outlet 302 of the filter 3. The test liquid container 1 is connected with a main circulation pipeline 8, and the circulation pump 2 is installed on the main circulation pipeline 8. The main circulation pipeline 8 is also connected with a liquid output pipeline 9, and the liquid output pipeline 9 is connected with a liquid input pipeline 10. The liquid input pipeline 10 is connected with the liquid inlet 301 of the filter 3, and the test liquid in the test liquid container 1 is input into the filter 3. The filter 3 is also connected with the test liquid container 1 through a liquid return pipeline 11, and the filtered liquid in the filter 3 is returned to the test liquid container, so that the test liquid circulates in this way to maintain the cleanliness of the test liquid. The liquid return pipeline 11 is connected with a sampling pipeline 12 connected with an online analyzer, and the circulating liquid is pre-detected by the online analyzer set here to ensure the sampling and analysis results of the test liquid at the detection point. A first ball valve 13 is installed on the front section of the liquid output pipeline 9 to control the liquid output. It can also control the liquid output pipeline 9 to update the liquid in the filter 3 and return it to the filter 3, so as to achieve the purpose of timeliness and representativeness of the liquid sample obtained by the sampling pipeline 12 connected to the subsequent online analyzer without additional loss of chemicals. A second ball valve 13 is installed on the rear section of the liquid output pipeline. When the filter 3 is backwashed, the second ball valve 13 needs to be opened. A third ball valve 14 is installed on the liquid input pipeline 10 to control whether the liquid in the liquid input pipeline is output to the filter 3. The liquid inlet pressure sensor 4 and the liquid outlet pressure sensor 5 are both connected to the controller for communication. The starting end of the liquid return pipeline 11 is installed on the overflow port 303, and the overflow valve 7 is installed on the front end of the liquid return pipeline 11. The pretreatment device also includes a circulation pool 18. The liquid outlet 302 of the filter 3 is connected to a first liquid return branch 19. The end of the first liquid return branch 19 is connected to the circulation pool 18. The liquid enters the circulation pool 18 through the first liquid return branch 19. The front section of the liquid return pipeline 11 is also connected to a second liquid return branch 20 through a three-way connector. The end of the second liquid return branch 20 is connected to the liquid return pipe 11. The end is connected to the circulation pool 18, and the liquid returns to the reflux pipeline 11 through the second liquid return branch 20. The end of the liquid output pipeline 9 is connected to the first liquid return branch 19 through a three-way connector. During backwashing, the liquid returns to the filter 3 from the liquid output pipeline 9 through the first liquid return branch 19. An inlet solenoid valve 21 is also installed on the first liquid return branch 19, and an outlet solenoid valve 22 is also installed on the second liquid return branch 20. The sampling pipeline 12 is installed on the second liquid return branch 20.The device of the present invention has a pressure reduction function through the setting of the circulation pool. When reducing the pressure, keep the inlet solenoid valve 21 in a closed state, open the outlet solenoid valve 22, and drain the liquid by gravity. At the same time, install a liquid level meter 23 on the circulation pool 18 to determine whether the liquid in the circulation pool 18 is emptied. After confirming that it is empty, open the inlet solenoid valve 21 and the outlet solenoid valve 22 at the same time to confirm the pressure difference between the inlet pressure sensor 4 and the outlet pressure sensor 5 to determine whether the purpose of pressure reduction is achieved. Whether the pressure reduction is successful can be used to determine whether the filter element in the filter 3 is blocked. The top of the circulation pool 18 also has an overflow port 1801 for communicating with the atmosphere to ensure pressure reduction. The liquid level meter 23 is a float liquid level meter, and can also be an ultrasonic liquid level meter, which can be changed according to actual usage.

[0043] A pretreatment method for an online analyzer in a chemical process, such as Figure 1 As shown, the following steps are included:

[0044] S1. Before use, you first need to open the first ball valve 13, the third ball valve 15 and the relief valve 7, close the second ball valve 14, fill the filter with the liquid to be tested, and when liquid overflow is observed at the top overflow port, close the relief valve. In daily use, except for manual intervention maintenance, the relief valve 7 is in a normally closed state;

[0045] S2. Determine whether the main circulation pipeline is operating normally through the pressure value of the inlet pressure sensor 4, so as to determine whether the startup conditions are met and whether it meets the requirements of the filter driving force. When the filter driving force requirements are met, determine by observing the pressure difference between the inlet pressure sensor 4 and the outlet pressure sensor 5; if the pressure difference is less than the preset value, the test liquid filtered by the filter 3 returns to the test liquid container 1 through the return liquid pipeline 11 to continue to circulate; if the pressure difference is greater than or equal to the preset value, the side cannot continue to circulate, the controller control device stops running and alarms, opens the normally closed solenoid valve 16, and reduces the pressure. After reducing the pressure, confirm the pressure difference between the inlet pressure sensor 4 and the outlet pressure sensor 5 again to determine whether the filter element of the filter 3 is blocked;

[0046] S3. If the filter element of the filter 3 is clogged and needs to be backwashed manually: close the third ball valve 15, open the second ball valve 14 and the normally closed solenoid valve 16, and the liquid in the test liquid container enters the liquid return pipeline 11 through the liquid output pipeline, and enters the filter 3 from the liquid return pipeline 11 for backwashing, and finally open the drain valve 6 to discharge the waste liquid from the drain outlet;

[0047] S4. After the waste liquid is drained, close the drain valve 6 and the second ball valve 14, and open the third ball valve 15 to allow the liquid to continue to circulate in the device. When sampling, close the normally closed solenoid valve 16, and the online analyzer takes samples from the sampling pipeline for analysis.

[0048] A pretreatment method for an online analyzer in a chemical process, such as Figure 2 As shown, the following steps are included:

[0049] S1. Before use, first open the first ball valve 13, the third ball valve 15 and the relief valve 7, close the second ball valve 14, fill the filter 3 with the liquid to be tested, and when liquid overflow is observed at the top overflow port 303, close the relief valve 7. In daily use, the relief valve 7 is in a normally closed state except for manual intervention maintenance;

[0050] S2, judging whether the main circulation pipeline is operating normally by the pressure value of the inlet pressure sensor 4, so as to determine whether the start-up conditions are met and whether it meets the requirements of the filter driving force. When the requirements of the filter driving force are met, the judgment is made by observing the pressure difference between the inlet pressure sensor and the outlet pressure sensor; if the pressure difference is less than the preset value, the liquid to be tested after being filtered by the filter 3 returns to the liquid container 3 to be tested through the return line 11 and continues to circulate; if the pressure difference is greater than or equal to the preset value, the side cannot continue to circulate, and the controller stops the operation of the control device and alarms;

[0051] S3, keep the inlet solenoid valve 21 in the closed state, open the outlet solenoid valve 22, drain the liquid in the circulation pool 18 by gravity drainage, check and confirm that the liquid in the circulation pool 18 is empty, open the inlet solenoid valve 21 and the outlet solenoid valve 22, and confirm the pressure difference between the inlet pressure sensor 4 and the outlet pressure sensor 5 to determine whether the pressure reduction is successful;

[0052] S4. If the pressure reduction is unsuccessful, it means that the filter element in the filter 3 is clogged, and manual intervention is required to backwash the filter: close the third ball valve 15, open the second ball valve 14, and the liquid in the test liquid container 3 enters the first liquid return branch 19 through the liquid output pipeline, and enters the filter 3 from the first liquid return branch 19 for backwashing, and finally open the drain valve 6 to discharge the waste liquid from the drain outlet;

[0053] S5. After the waste liquid is drained, close the drain valve 6 and the second ball valve 14, and open the third ball valve 15 to allow the liquid to continue to circulate in the device. When sampling, close the outlet solenoid valve 22, and the online analyzer takes samples from the sampling pipeline for analysis.

[0054] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. All equivalent changes and modifications to the shapes, structures, features and spirits described in the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A pretreatment method for an online analyzer in a chemical process, characterized in that: The invention comprises a controller, a container for the liquid to be tested, a circulation pump, a filter, a liquid inlet pressure sensor and a liquid outlet pressure sensor. The filter has a liquid inlet, a liquid outlet, an overflow port and a sewage outlet. A sewage outlet is provided with a sewage valve, and an overflow valve is provided with an overflow port. The liquid inlet pressure sensor is provided on the top of the filter, and the liquid outlet pressure sensor is provided at the liquid outlet of the filter. The container for the liquid to be tested is connected with a main circulation pipeline, the circulation pump is provided on the main circulation pipeline, and a liquid output pipeline is provided on the main circulation pipeline. The liquid output pipeline is connected with a liquid input pipeline, and the liquid input pipeline is connected with the liquid inlet of the filter, and the liquid to be tested in the liquid container to be tested is input into the filter. The filter is also connected with the liquid container to be tested through a liquid return pipeline, and a sampling pipeline connected with an online analyzer is connected on the liquid return pipeline. A first ball valve is installed on the front section of the liquid output pipeline, and a second ball valve is installed on the rear section thereof. A third ball valve is installed on the liquid input pipeline, and the liquid inlet pressure sensor and the liquid outlet pressure sensor are both communicatively connected with the controller. The starting end of the liquid return pipeline is connected to the liquid outlet, and the sampling pipeline is installed on the starting end of the liquid return pipeline, located after the liquid outlet pressure sensor. A normally closed solenoid valve is installed on the front section of the liquid return pipeline, and a fourth ball valve is installed on the rear section thereof. The end of the liquid output pipeline is connected to the liquid return pipeline through a three-way connector. The pretreatment method comprises the following steps: S1. Before use, you first need to open the first ball valve, the third ball valve and the overflow valve, close the second ball valve, fill the filter with the liquid to be tested, and when you observe liquid overflow at the top overflow port, close the overflow valve. In daily use, the overflow valve is in a normally closed state except for manual intervention maintenance; S2. Judging whether the main circulation pipeline is operating normally by the pressure value of the liquid inlet pressure sensor, so as to determine whether the start-up conditions are met and whether it meets the requirements of the filter driving force. When the requirements of the filter driving force are met, the judgment is made by observing the pressure difference between the liquid inlet pressure sensor and the liquid outlet pressure sensor; if the pressure difference is less than the preset value, the liquid to be tested after being filtered by the filter returns to the liquid to be tested container through the liquid return pipeline to continue to circulate; if the pressure difference is greater than or equal to the preset value, the side cannot continue to circulate, the controller control device stops running and alarms, opens the normally closed solenoid valve, and confirms the pressure difference between the liquid inlet pressure sensor and the liquid outlet pressure sensor again to judge whether the filter element of the filter is blocked; S3. If the blockage requires manual backwashing: close the third ball valve, open the second ball valve and the first normally closed solenoid valve, and the liquid in the liquid container to be tested enters the liquid return pipeline through the liquid output pipeline, and enters the filter from the liquid return pipeline for backwashing, and finally open the drain valve to discharge the waste liquid from the drain outlet; S4. After the waste liquid is drained, close the drain valve and the second ball valve, and open the third ball valve to allow the liquid to continue to circulate in the device. When sampling, close the normally closed solenoid valve, and the online analyzer takes samples from the sampling pipeline for analysis.

2. A pretreatment method for an online analyzer in a chemical process, characterized in that: The invention comprises a controller, a container for liquid to be tested, a circulation pump, a filter, a liquid inlet pressure sensor and a liquid outlet pressure sensor, wherein the filter has a liquid inlet, a liquid outlet, an overflow port and a sewage outlet, a sewage outlet is installed with a sewage valve, an overflow valve is installed with the overflow port, the liquid inlet pressure sensor is installed on the top of the filter, the liquid outlet pressure sensor is installed at the liquid outlet of the filter, the container for liquid to be tested is connected with a main circulation pipeline, the circulation pump is installed on the main circulation pipeline, a liquid output pipeline is also connected on the main circulation pipeline, a liquid input pipeline is connected on the liquid output pipeline, the liquid input pipeline is connected with the liquid inlet of the filter, the liquid to be tested in the container for liquid to be tested is input into the filter, the filter is also connected with the container for liquid to be tested through a liquid return pipeline, a sampling pipeline connected with an online analyzer is connected on the liquid return pipeline, and a sampling pipeline connected with an online analyzer is connected on the liquid output pipeline. A first ball valve is installed on the front section, a second ball valve is installed on the rear section, a third ball valve is installed on the liquid input pipeline, the liquid inlet pressure sensor and the liquid outlet pressure sensor are both connected to the controller, the starting end of the liquid return pipeline is installed on the overflow port, the overflow valve is installed on the front end of the liquid return pipeline, the pretreatment device also includes a circulation pool, the liquid outlet of the filter is connected to a first liquid return branch, the end of the first liquid return branch is communicated with the circulation pool, the front section of the liquid return pipeline is also connected to a second liquid return branch through a three-way connector, the end of the second liquid return branch is communicated with the circulation pool, the end of the liquid output pipeline is connected to the first liquid return branch through a three-way connector, an inlet solenoid valve is also installed on the first liquid return branch, an outlet solenoid valve is also installed on the second liquid return branch, the sampling pipeline is installed on the second liquid return branch, and the pretreatment method includes the following steps: S1. Before use, you first need to open the first ball valve, the third ball valve and the overflow valve, close the second ball valve, fill the filter with the liquid to be tested, and when you observe liquid overflow at the top overflow port, close the overflow valve. In daily use, the overflow valve is in a normally closed state except for manual intervention maintenance; S2. Judging whether the main circulation pipeline is operating normally by the pressure value of the inlet pressure sensor, so as to determine whether the start-up conditions are met and whether the requirements of the filter driving force are met. When the requirements of the filter driving force are met, the judgment is made by observing the pressure difference between the inlet pressure sensor and the outlet pressure sensor; if the pressure difference is less than the preset value, the liquid to be tested after being filtered by the filter returns to the liquid to be tested container through the return line to continue to circulate; if the pressure difference is greater than or equal to the preset value, the side cannot continue to circulate, and the controller stops the operation of the control device and alarms; S3, keep the inlet solenoid valve in the closed state, open the outlet solenoid valve, drain the liquid in the circulation pool by gravity, check and confirm that the liquid in the circulation pool is empty, open the inlet solenoid valve and the outlet solenoid valve, and confirm the pressure difference between the inlet pressure sensor and the outlet pressure sensor to determine whether the pressure reduction is successful; S4. If the pressure reduction is unsuccessful, it means that the filter element in the filter is clogged, and manual intervention is required to backwash the filter: close the third ball valve, open the second ball valve, and the liquid in the test liquid container enters the first liquid return branch through the liquid output pipeline, and enters the filter from the first liquid return branch for backwashing. Finally, open the drain valve to discharge the waste liquid from the drain outlet; S5. After the waste liquid is drained, close the drain valve and the second ball valve, and open the third ball valve to allow the liquid to continue to circulate in the device. When sampling, close the outlet solenoid valve, and the online analyzer takes samples from the sampling pipeline for analysis.

3. The pretreatment method for an online analyzer of a chemical process according to claim 2, characterized in that: A liquid level meter is also installed in the circulation pool, and an overflow port is also provided on the top of the circulation pool for communicating with the atmosphere.

4. The pretreatment method for an online analyzer of a chemical process according to claim 3, characterized in that: The liquid level meter is a float liquid level meter.

5. The pretreatment method for an online analyzer of a chemical process according to claim 4, characterized in that: The liquid level meter is an ultrasonic liquid level meter.

Images