How to clean a plate heat exchanger?

1. Preparation before cleaning
Shutdown and isolation: Make sure the plate heat exchanger has been shut down and disconnected from the main pipeline to ensure the safety of the operator.
Drain the medium: Drain the medium in the heat exchanger to prevent leakage of the medium during the cleaning process from causing harm to personnel.
2. Cleaning method
Chemical cleaning
Flushing: Before pickling, open-type flush the heat exchanger to remove impurities such as mud and scale, improve the pickling effect, and reduce the acid consumption of pickling.
Pickling:
Pour the cleaning liquid into the cleaning equipment and then inject it into the heat exchanger.
Soak statically for 2 hours, then dynamically circulate for 3-4 hours, and perform positive and reverse alternating cleaning every 0.5 hours.
After pickling, if the pH value of the acid solution is greater than 2, the acid solution can be reused, otherwise, the pickling solution should be diluted and neutralized and then discharged.
Alkaline cleaning: After the acid cleaning, use NaOH, Na3PO4, and softened water in a certain proportion, and use dynamic circulation to perform alkaline cleaning on the heat exchanger to achieve acid-base neutralization and prevent corrosion of the heat exchanger plates.
Water washing: After the alkaline cleaning, rinse the heat exchanger repeatedly with clean softened water for 0.5 hours to thoroughly rinse the residue.
Passivation treatment: After the acid cleaning, passivate the heat exchanger plates to prevent corrosion.
Mechanical cleaning
Plate removal: Disassemble the plate heat exchanger and take out the plates.
Brushing: Use a soft brush to brush each plate to avoid scratching the plate with a steel brush.
Rinse: Rinse the plates with a high-pressure water gun or clean water to ensure that they are clean.
Ultrasonic cleaning
Prepare cleaning solution: Add tap water to the cleaning tank, and then mix and dilute it with the cleaning solution "Type I".
Place the heat exchanger: Place the plate heat exchanger vertically in the cleaning tank.
Set the cleaning cycle: Set the ultrasonic cleaning cycle to 1 hour.
Check the cleaning effect: After the cleaning cycle is completed, rinse and check the heat exchanger to ensure that it is clean.
3. Post-cleaning treatment
Dry: After cleaning, wipe the plate heat exchanger dry with a clean cloth to ensure that there are no foreign particles and fibers between the plates and the rubber pads.
Check the sealing gasket: Check the status of the sealing gasket to ensure that it is intact and replace it if necessary.
Assemble: Reassemble the cleaned plates to ensure that the sealing gasket is firmly adhered.
Pressure test: After assembly, perform a pressure test on the heat exchanger to ensure that its sealing and performance meet the standards.
4. Precautions
Avoid using strong acids: It is strictly forbidden to use strong acids such as hydrochloric acid for cleaning to avoid corrosion of the heat exchanger plates.
Choose a suitable cleaning agent: Choose a mild cleaning agent, such as formic acid, and conduct sufficient tests before cleaning to ensure that the reaction between the cleaning agent and dirt will not damage the plates.
Regular cleaning: Clean regularly, especially when the thermal efficiency is significantly reduced or the pressure drop changes significantly, it should be cleaned in time.
Control water quality: In daily use, strictly control water quality to prevent impurities from entering the heat exchanger and reduce the frequency and difficulty of cleaning.