The daily maintenance of the electrophoresis ultrafiltration system mainly involves the attenuation and recovery of the permeate volume of the ultrafiltration solution. Under normal operation of electrophoretic paint, several factors that affect ultrafiltration excess are: type of paint, percentage of solid content, temperature, conductivity, pH value, flow rate of electrophoretic paint entering the ultrafiltration system, inlet pressure of the ultrafiltration system, pressure difference, and pollutants introduced during pretreatment. The electrophoresis ultrafiltration system must be managed and maintained by a dedicated person, and the above data must be recorded daily in detail and accurately; When a problem occurs, it is of great help in analyzing the cause of the problem.
After a few days of operation of the electrophoresis ultrafiltration system, the flow rate of the ultrafiltration system will stabilize at a flow rate value, which is the normal value of the system. When the flow rate of the ultrafiltration system drops to 70% of the normal value, the system must be cleaned. If cleaning is delayed, it will cause blockage of the ultrafiltration tube, making it impossible to restore the flow rate of the ultrafiltration solution.
Attention: The ultrafiltration system should minimize abnormal shutdowns during daily operation or cleaning, as this can cause blockages in the ultrafiltration tubes and prevent the recovery of ultrafiltration fluid flow.
1. Normal shutdown:
Before shutting down the feed pump or cleaning pump, the ultrafiltration system should first slowly close the outlet valve of the pump until it is completely closed, and finally turn off the motor and immediately clean the ultrafiltration device.
Warning: The following situations can cause fatal harm to ultrafiltration membrane components.
1. Sudden power outage in the workshop.
2. After shutdown, the ultrafiltration membrane components were not cleaned immediately.
Formula for Cleaning Solution 2: (Paint for Cathodic Electrophoretic Coating)
Formula 1: Used before short-term shutdown. Formula: Deionized water -100% cycle cleaning: 1-2 hours
Formula 2: Used for cleaning common blockages. Formula: 1. Electrophoretic paint solvent -5%
2. Acetic acid -3%
3. Deionized water - other
Cycle cleaning soaking: 12-24 hours or more
3 three Cleaning program
Fill the cleaning tank with deionized water for later use. 2. Close or open the relevant ball valves, start the cleaning pump, and clean the residual paint in the ultrafiltration tank. During the operation, pay attention to adding deionized water to the cleaning tank, observe the liquid level of the cleaning water tank and the color of the cleaning discharge liquid, and continue cleaning until the discharge liquid is clear. Stop the cleaning pump. Prepare cleaning solution in the cleaning tank, start the cleaning pump, perform circulating cleaning, and return the cleaning solution to the cleaning tank. During the cyclic cleaning process, the cleaned substances will quickly contaminate the cleaning solution. When the cleaning solution is severely contaminated, it should be discharged and the cleaning agent should be re formulated to continue cleaning. Repeat the above operation until the cleaning solution returned to the cleaning tank is clear. If the membrane module is severely blocked, stop the cleaning pump after circulating for 2 hours or until the temperature reaches 49 ℃ (be careful not to exceed 49 ℃), seal the cleaning solution in the ultrafiltration device, soak for one day and night or longer, and then perform circulating cleaning for 2 hours. After cleaning, the cleaning solution should be drained. Add deionized water to the cleaning tank, start the cleaning pump, perform cyclic cleaning, clean the chemical cleaning agent thoroughly, and discharge it. Inject clean deionized water into the ultrafiltration device again, and the cleaning process is complete.
Special precautions for maintenance of electrophoresis ultrafiltration equipment
When the inlet pressure of ultrafiltration decreases by 20%, the precision filter bag (with a filtration accuracy of 25um) in the ultrafiltration filter must be replaced. Before replacing the ultrafiltration precision filter bag, it must be washed and soaked with pure water. When releasing the filter bag, it should be placed upright and not loose. At the same time, the compression frame should also be aligned and not biased. The fastening nut should be tightened; Otherwise, it is easy to leak slag, which cannot achieve good filtering effect and cause blockage of the subsequent ultrafiltration tube. After installing the 3 filter bags, the exhaust valve at the top of the ultrafiltration filter must be opened to release air first, filling the filter with paint, and then turning on the ultrafiltration pressure pump. During normal operation, the bypass valves cannot be opened. When the main circulation pump needs to be shut down due to malfunction or maintenance, the ultrafiltration booster pump must also be shut down. The inlet and outlet valves of the pump, as well as the paint inlet and outlet valves and permeate valves of the ultrafiltration membrane tube, must be closed. If the shutdown exceeds half an hour, the paint in the membrane tube must be drained, cleaned with pure water, and soaked in pure water to protect the ultrafiltration membrane.
If the following abnormal situations and operations occur in the electrophoresis ultrafiltration equipment, it will immediately damage the ultrafiltration membrane, causing a significant decrease in the permeate flow rate of the ultrafiltration water, which cannot be restored:
Cathodic electrophoretic paint has poor stability and is prone to slagging, which can easily clog fine filter bags and ultrafiltration membranes. During the operation of the electrophoresis ultrafiltration membrane, the fine filter bag is clogged, resulting in a low flow rate of electrophoresis paint in the ultrafiltration membrane. The sedimentation of electrophoresis paint clogs the ultrafiltration membrane, and the permeability of ultrafiltration water gradually decreases to zero. After running for a few days, the water output of the ultrafiltration membrane will reach a stable value. When this value drops to around 70%, immediate backwashing must be carried out. If the cleaning is delayed, it will cause the ultrafiltration membrane to clog, making the flow irreversible. When the ultrafiltration membrane is shut down due to special factors such as power outages, holidays, or tank cleaning during operation, the electrophoretic paint in the ultrafiltration membrane must be completely replaced with cleaning water (solvent water for the tank) before shutting down; Otherwise, the electrophoretic paint in the ultrafiltration tube will precipitate, adhere to the surface of the ultrafiltration membrane, block the ultrafiltration membrane, and significantly reduce the permeability of ultrafiltration water during operation. When the pH value, temperature, solid content, conductivity, and other management values of the cathodic electrophoretic paint in tank 5 are not within the normal range, the dispersion of the cathodic electrophoretic paint will be unstable, and it is easy to condense into blocks on the ultrafiltration membrane, leading to blockage. The 6 workpieces entering the electrophoresis tank must be cleaned first. The phosphate ions brought into the electrophoresis tank by pre-treatment will have a significant impact on the cathodic electrophoretic paint, and the ultrafiltration membrane will be blocked by condensed matter (such as lead phosphate) pollutants. If the cathodic electrophoretic paint is lead-free, there should be measures to prevent bacteria in the electrophoretic paint; If bacteria grow in cathodic electrophoretic paint, it is easy to form slag, block fine filter bags, and damage ultrafiltration membranes.
