The plate heat exchanger is made up of many stamped corrugated thin plates at a certain interval, sealed by gaskets and laminated and compacted by a frame and a compression screw. The four corner holes of the plates and gaskets form fluid distribution pipes and collection pipes, and reasonably separate cold and hot fluids. How to clean the scale of the plate heat exchanger?
(1) Plate punching. Flush the plate heat exchanger before pickling, so that impurities such as mud and scale inside the heat exchanger are cleaned out. This can improve an effect of pickling and reduce the acid consumption of pickling.
(2) Pour the cleaning liquid into the cleaning equipment, and then pour it into the heat exchanger.
(3) Pickling. Statically soak the heat exchanger filled with acid solution for 2h. Then continue dynamic circulation for 3 to 4 h. During this period, the positive and negative cleaning was performed alternately every 0.5 h. After pickling, if the pH of the acid solution is greater than 2, the acid solution can be reused, otherwise, the acid solution should be diluted, neutralized and drained.
(4) Alkaline washing. After the pickling is completed, it is prepared with NaOH, Na, PO, and demineralized water in a certain proportion, and the heat exchanger is alkali washed by dynamic circulation to achieve acid-base neutralization, so that the heat exchanger plates are no longer corroded.
(5) Water washing: After the alkali washing, use clean demineralized water to repeatedly rinse the heat exchanger for 0.5 h to thoroughly rinse the residue in the heat exchanger. During the cleaning process of the plate heat exchanger, time records of each step should be made. After cleaning, the plate heat exchanger should be subjected to a pressure test.