Automatic Control and Monitoring System and Method for Primary Brine Sludge Filter Press

Abstract

The present invention discloses an automatic control and monitoring system and method for a primary brine sludge filter press, which relates to the technical field of primary brine treatment processes. By adding an inlet liquid cut-off valve, a process air cut-off valve, and a water washing cut-off valve to the salt mud inlet pipeline of the sludge filter press, and installing a PLC controller in the oil pressure system for PLC control, the present invention realizes the connection between the salt mud inlet pressure and the oil pressure of the filter press, accurately controls the operating parameters of the filter press, realizes one-key operation of the filter press for inlet liquid, blowing, and water washing, improves the filtration efficiency of the filter press, reduces the salt content rate of the salt mud to 5-10%, reduces the water content rate to 40-45%, improves the automation control level of the brine at the same time, and reduces the labor intensity of the post.

Description

Technical Field

[0001] The present invention relates to the technical field of primary brine treatment processes, and particularly to an automatic control and monitoring system and method for a primary brine sludge filter press. Background Art

[0002] During the refining process of primary brine, sodium hydroxide solution and sodium carbonate solution are used as refining agents. In the crude brine tank, the purpose of removing calcium and magnesium ions is achieved by reacting with calcium and magnesium ions in the brine to form magnesium hydroxide precipitate and calcium carbonate precipitate. The calcium carbonate and magnesium hydroxide precipitates are discharged to the sludge tank through filtration equipment such as pre - processors, Kail membranes, and ceramic membranes. The slurry in the sludge tank is transported to a plate - and - frame filter press by a sludge pump for pressure filtration to form a mud cake and then transported out for disposal.

[0003] At present, in the chlor - alkali industry, the liquid inlet, air blowing, and water washing operations of the sludge filter press are all manually controlled on - site, and the sludge discharge operation is PLC - manually controlled; the feeding time of the filter press, water washing, and air blowing are all operated by experience without quantitative standards. At present, the automation level of PLC control is relatively low, and the workload of personnel is relatively large. At the same time, there is no online operation monitoring for the sludge filter press. In daily production, only manual intermittent inspections are used to monitor the operation status of the equipment. Often, due to the long high - pressure filtration time of the sludge filter press, problems cannot be found in time, resulting in problems such as high - pressure deformation of filter plates. Affected by manual operation and operation by experience, the salt content index of the filtered sludge is as high as 15 - 20%, and the water content is 50 - 60%, causing waste of salt resources and environmental pollution. Summary of the Invention

[0004] In order to solve the above - mentioned technical problems, the present invention provides an automatic control and monitoring system and method for a primary brine sludge filter press. The operations of the filter press are programmed into the PLC controller, and the PLC controller is data - connected to the DCS control module. The DCS control module is used to realize one - key operations of liquid inlet, air blowing, and water washing of the filter press, improve the automation control level of brine, and reduce the labor intensity of the post.

[0005] To achieve this technical purpose, the present invention adopts the following solutions:

[0006] An automatic control and monitoring system for a primary brine sludge filter press includes a PLC controller, a DCS control module, a filter press, a sludge tank, a sludge pump, a water washing pump, and an air inlet pipe. The filter press is connected to an oil pressure system; the sludge tank is connected to the filter press through a sludge pump and a pipeline. The filter press is also connected to the water washing pump and the air inlet pipe through pipelines. Among them, a process air cut - off valve is installed on the air inlet pipe, a water washing cut - off valve is installed on the pipeline connecting the water washing pump and the filter press, and a liquid inlet cut - off valve is installed on the pipeline connecting the sludge pump and the filter press; the process air cut - off valve, the water washing cut - off valve, the liquid inlet cut - off valve, and the water washing pump are respectively in communication connection with the DCS control module. The DCS control module is in communication connection with the PLC controller, and the PLC controller is connected to the oil pressure system.

[0007] Furthermore, the inlet of the filter press is connected with a liquid inlet pipeline, and a remote pressure gauge is installed on the liquid inlet pipeline. The remote pressure gauge is communicatively connected to the DCS control module.

[0008] The automatic control and monitoring method for the primary brine sludge filter press is carried out according to the following steps:

[0009] Step 1: The sludge is transported to the sludge filter press by a sludge transfer pump. As the sludge filter press operates, the inlet pressure of the sludge filter press continuously rises. When the inlet pressure of the sludge filter press is higher than the set upper limit value of the inlet pressure or lower than the set lower limit value of the inlet pressure, the DCS control module sends a command to close the inlet cut-off valve, and the filter press exits the system to perform the operation in Step 2;

[0010] Or when the adjusted value of the oil pressure system of the sludge filter press is higher than the set upper limit value of the oil pressure by the PLC controller or lower than the set lower limit value of the oil pressure, the PLC controller feeds back the oil pressure system pressure to the DCS control module, and the DCS control module closes the inlet cut-off valve of the sludge filter press to perform the operation in Step 2;

[0011] Step 2: The water washing pump is started, the water washing cut-off valve is opened, and the sludge filter press is washed. After the water washing operation is completed, the water washing cut-off valve is closed;

[0012] Step 3: The signal that the water washing cut-off valve is closed is fed back to the DCS control module. The DCS control module issues an instruction for the filter press to blow air. The process air cut-off valve of the filter press is opened, and the filter press starts the air blowing operation. After the air blowing is completed, the process air cut-off valve is closed;

[0013] Step 4: The filter press starts to feed liquid again, operates according to Steps 1 to 3, and repeats the operation repeatedly. The filter press performs the sludge discharging operation.

[0014] Furthermore, the inlet pressure of the filter press is monitored in real time through the remote pressure gauge. The upper and lower limit values of the inlet pressure are set in the DCS control module, and the upper and lower limit values of the oil pressure are set in the PLC controller.

[0015] Furthermore, when the oil pressure of the oil pressure system of the sludge filter press is between the set upper and lower limit values of the oil pressure, the oil pressure system pressure remains unchanged to ensure the normal and stable operation of the sludge filter press; when the inlet pressure of the sludge filter press is between the set upper and lower limit values of the inlet pressure, the sludge filter press operates normally.

[0016] Furthermore, the starting time of the water washing pump in Step 2 is 5 - 10 s, and the water washing operation time lasts for 20 min.

[0017] Furthermore, the process air flow rate in Step 3 is controlled at 1000 - 2000 m³ / h, and the air blowing time is controlled at 15 min.

[0018] Further, the number of repetitions of Step 4 is 3 to 4 times.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: by adding a liquid inlet cut-off valve, a process air cut-off valve, and a water washing cut-off valve to the salt mud inlet pipeline of the salt mud filter press, and installing a PLC controller in the hydraulic oil system for PLC control, the connection between the salt mud inlet pressure and the hydraulic oil pressure of the filter press is realized, the operating parameters of the filter press are accurately controlled, and one-key operations of liquid inlet, air blowing, and water washing of the filter press are achieved, improving the filtration efficiency of the filter press. The salt content rate of the salt mud is reduced to 5 - 10%, the water content rate is reduced to 40 - 45%, and at the same time, the automatic control level of the brine is improved, and the labor intensity of the post is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the electrical instrument diagram of the automatic control and monitoring system for the primary brine salt mud filter press provided by the embodiment of the present invention;

[0021] Figure 2 It is the logic block diagram of the automatic control and monitoring system for the primary brine salt mud filter press provided by the embodiment of the present invention;

[0022] The labels in the figure are: 1, hydraulic oil system; 2, salt mud filter press; 3, process air cut-off valve; 4, water washing cut-off valve; 5, process air inlet duct; 6, process air flowmeter; 7, water washing pump; 8, PLC controller; 9, salt mud pipe; 10, liquid inlet cut-off valve; 11, salt mud pump; 12, salt mud pond; 13, water washing pipe; 14, DCS control module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To fully understand the purpose, features, and effects of the present invention, the present invention will be described in detail through the following specific embodiments, but the present invention is not limited thereto.

[0024] As Figure 1 shown, an automatic control and monitoring system for a primary brine salt mud filter press provided by the present invention is composed of a salt mud filter press 2, a hydraulic oil system 1, a process air inlet duct 5, a process air cut-off valve 3, a process air flowmeter 6, a water washing pump 7, a water washing pipe 13, a water washing cut-off valve 4, a salt mud pond 12, a salt mud pump 11, a liquid inlet cut-off valve 10, a PLC controller 8, a DCS control module 14, etc. The salt mud pond 12 is connected to the salt mud pump 11 through a pipeline, the salt mud pump 11 is connected to the salt mud filter press 2 through a salt mud pipe 9, the salt mud filter press 2 is connected to the hydraulic oil system 1, the hydraulic oil system 1 is connected to the PLC controller 8, and the PLC controller 8 is communicatively connected to the DCS control module 14. A liquid inlet cut-off valve 10 and a feed remote pressure gauge are installed on the salt mud pipe 9, and the liquid inlet cut-off valve 10 and the feed pressure gauge are respectively communicatively connected to the DCS control module 14.

[0025] The sludge filter press 2 is also connected with a process air inlet pipe 5 and a water washing pipe 13. A process air cut-off valve 3 and a process air flowmeter 6 are installed on the process air inlet pipe 5, and the process air cut-off valve 3 and the process air flowmeter 6 are respectively in communication connection with the DCS control module 14; a water washing pump 7 and a water washing cut-off valve 4 are installed on the water washing pipe 13, and the water washing pump 7 and the water washing cut-off valve 4 are respectively in communication connection with the DCS control module 14. The sludge filter press 2 adopts a plate-and-frame filter press or a box filter press.

[0026] The sediment such as sand, calcium carbonate, and magnesium hydroxide generated during the fine filtration of the crude brine is discharged into the sludge pond and transported to the sludge filter press 2 by the sludge pump 11. After the sludge filter press 2 operates for a period of time, the inlet pressure of the filter press continuously rises. The upper and lower limit values of the inlet pressure are set in the DCS control module 14, and the upper and lower limit values of the oil pressure of the oil pressure system are set in the PLC controller 8.

[0027] Please refer to Figure 2 , an automatic control and monitoring method for the primary brine sludge filter press. The inlet pressure of the sludge filter press 2 is monitored in real time through a feed remote pressure gauge, and the monitoring result is sent to the DCS control module 14. After receiving the oil pressure system information, the PLC controller 8 transmits the oil pressure information to the DCS control module 14. The DCS control module 14 respectively processes and analyzes the inlet pressure and the oil pressure system pressure. The DCS control module 14 judges and controls the operating state of the sludge filter press according to the data processing result. The specific steps are as follows:

[0028] Step 1: The sludge is transported to the sludge filter press by the sludge transport pump. As the sludge filter press operates, the inlet pressure of the sludge filter press continuously rises. When the inlet pressure of the sludge filter press is higher than the set upper limit value of the inlet pressure or lower than the set lower limit value of the inlet pressure, the DCS control module sends a command to close the inlet cut-off valve, and the filter press discharges the system to perform the operation of Step 2;

[0029] Or when the adjusted value of the oil pressure system pressure of the sludge filter press is higher than the set upper limit value of the oil pressure of the PLC controller or lower than the set lower limit value of the oil pressure (in case of liquid leakage), the PLC controller feeds back the oil pressure system pressure to the DCS control module, and the DCS control module closes the inlet cut-off valve of the sludge filter press to perform the operation of Step 2;

[0030] When the oil pressure system pressure is between the set upper and lower limit values of the oil pressure, the oil pressure system maintains the pressure unchanged. At the same time, when the inlet pressure is between the set upper and lower limit values of the inlet pressure, the sludge filter press operates normally.

[0031] Step 2: The DCS control system closes the salt sludge inlet shut-off valve of the salt sludge filter press, and the water washing pump starts automatically. The water washing valve opens 5 - 10 seconds (the time can be adjusted according to the actual situation) after the water washing pump starts, and the salt sludge filter press starts the water washing operation. The water washing operation of the salt sludge filter press lasts for 20 minutes (the time can be adjusted according to the actual situation). After the water washing operation is completed, the water washing valve closes.

[0032] Step 3: The signal that the water washing valve is closed is fed back to the DCS control module. The DCS control module issues an instruction for the salt sludge filter press to perform a blowing operation. The process air shut-off valve of the salt sludge filter press opens, and the salt sludge filter press starts the blowing operation. The process air flow rate is controlled at 1000 - 2000 m³ / h, and the blowing time is controlled at 15 minutes (the time can be adjusted according to the actual situation).

[0033] Step 4: After the blowing is completed, the salt sludge filter press starts to operate with liquid inlet again. Repeat the above steps for liquid inlet + blowing + water washing, and repeat 3 - 4 times (the number of repetitions can be adjusted according to the actual situation). Repeated operations can improve the filtration efficiency.

[0034] When the liquid inlet pressure of the salt sludge filter press abnormally increases, a command is sent to the salt sludge inlet shut-off valve and the PLC controller through the DCS control module. The salt sludge inlet shut-off valve closes according to the instruction of the DCS control module, and the PLC controller automatically adjusts the pressure of the oil pressure system, and promptly cuts out the salt sludge filter press to prevent liquid leakage or equipment damage, which can improve the operation efficiency of the salt sludge filter press. The salt content of the salt sludge is reduced to 5 - 10%, and the water content is reduced to 40 - 45%.

[0035] Finally, it should be noted that: The above-listed are only the preferred embodiments of the present invention. Of course, those skilled in the art can make changes and modifications to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and its equivalent technologies, they should all be considered as the protection scope of the present invention.

Claims

1. An automatic control and monitoring method for a primary brine sludge filter press, characterized in that, Proceed as follows: Step 1: The salt sludge is transported to the salt sludge filter press by the salt sludge transfer pump. As the salt sludge filter press operates, the inlet pressure of the salt sludge filter press continuously rises. When the inlet pressure of the salt sludge filter press is higher than the set upper limit value of the inlet pressure or lower than the set lower limit value of the inlet pressure, the DCS control module sends a command to close the inlet cut-off valve, and the filter press exits the system to perform the operation in Step 2; Or when the pressure adjustment value of the oil pressure system of the salt sludge filter press is higher than the set upper limit value of the oil pressure set by the PLC controller or lower than the set lower limit value of the oil pressure, the PLC controller feeds back the oil pressure system pressure to the DCS control module, and the DCS control module closes the inlet cut-off valve of the salt sludge filter press to perform the operation in Step 2; Step 2: Start the water wash pump, open the water wash cut-off valve, and perform a water wash operation on the salt sludge filter press. After the water wash operation is completed, close the water wash cut-off valve; Step 3: The signal that the water wash cut-off valve is closed is fed back to the DCS control module. The DCS control module issues an instruction for the filter press to blow air. The process air cut-off valve of the filter press is opened, and the filter press starts to blow air. After the blowing is completed, the process air cut-off valve is closed; Step 4: The filter press starts to feed liquid again, operates according to Steps 1 to 3, repeats the operation repeatedly, and the filter press performs sludge discharge operation; The automatic control and monitoring system for the primary brine salt sludge filter press includes a PLC controller, a DCS control module, a filter press, a salt sludge tank, a salt sludge pump, a water wash pump, and an air inlet pipe. The filter press is connected with an oil pressure system; it is characterized in that, The salt sludge tank is communicated with the filter press through the salt sludge pump and a pipeline. The filter press is also connected with the water wash pump and the air inlet pipe through pipelines. Among them, a process air cut-off valve is installed on the air inlet pipe, a water wash cut-off valve is installed on the pipeline connecting the water wash pump and the filter press, and an inlet cut-off valve is installed on the pipeline connecting the salt sludge pump and the filter press; The process air cut-off valve, the water wash cut-off valve, the inlet cut-off valve, and the water wash pump are respectively communicatively connected with the DCS control module. The DCS control module is communicatively connected with the PLC controller, and the PLC controller is electrically connected with the oil pressure system; The inlet of the filter press is connected with an inlet liquid pipeline, and a remote pressure gauge is installed on the inlet liquid pipeline. The remote pressure gauge is communicatively connected with the DCS control module.

2. The automatic control and monitoring method of the primary brine sludge filter press according to claim 1, characterized in that, The inlet pressure of the filter press is monitored in real time through the remote pressure gauge. The upper and lower limit values of the inlet pressure are set in the DCS control module, and the upper and lower limit values of the oil pressure are set in the PLC controller.

3. The automatic control and monitoring method of the primary brine sludge filter press according to claim 2, characterized in that, When the oil pressure of the oil pressure system of the salt sludge filter press is between the set upper and lower limit values of the oil pressure, the oil pressure system pressure remains unchanged to ensure the normal and stable operation of the salt sludge filter press; when the inlet pressure of the salt sludge filter press is between the set upper and lower limit values of the inlet pressure, the salt sludge filter press operates normally.

4. The automatic control and monitoring method of the primary brine sludge filter press according to claim 1, characterized in that, In Step 2, the start time of the water wash pump is 5 - 10 s, and the water wash operation time lasts for 20 min.

5. The automatic control and monitoring method of the primary brine sludge filter press according to claim 1, characterized in that, In Step 3, the process air flow rate is controlled at 1000 - 2000 m³ / h, and the blowing time is controlled at 15 min.

6. The automatic control and monitoring method of the primary brine sludge filter press according to claim 1, characterized in that In Step 4, the number of repeated operations is 3 - 4 times.

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