The plate heat exchanger is a high-efficiency heat exchange device composed of a plurality of corrugated heat transfer plates at a certain interval by welding or pressing by a rubber gasket. According to its processing technology, it is divided into detachable heat exchanger and all-welded non-removable heat exchanger.Most companies use plate heat exchangers. The maintenance of plate heat exchangers is critical. It can extend the service life of plate heat exchangers. Secondly, it can improve the efficiency of heat exchangers and save the company cost.
1. Selection of cleaning agent
The cleaning agents currently used are pickling, which includes organic and inorganic acids.The main organic acids are: oxalic acid and formic acid.The main inorganic acids are: hydrochloric acid and nitric acid.According to the analysis of heat exchanger fouling and process, material and scale composition, the plate heat exchanger has a small flow area and a complicated internal structure, and it is difficult to discharge if the cleaning liquid is precipitated.
2. The basic principle of removing scale from plate heat exchanger
(1) Dissolution: The acid solution easily reacts with calcium, magnesium, and carbonate scale to form a soluble compound, which dissolves the scale.
(2) Peeling action: The acid solution can dissolve the oxide on the metal surface. Thereby, the scale adhering to the surface of the metal oxide is peeled off.
(3) Air enthalpy action: After the acid solution reacts with calcium, magnesium and carbonate scale, a large amount of carbon dioxide is generated.During the overflow process, the carbon dioxide gas has a certain enthalpy power for the scale layer which is difficult to dissolve or dissolve slowly, so that the scale falls off from the heated surface of the heat exchanger.