The cleaning agent currently used in plate heat exchangers is pickling, which includes organic and inorganic acids.The main organic acids are: oxalic acid, formic acid. The main inorganic acids are: hydrochloric acid, nitric acid.According to the heat exchanger fouling and process, sheet material and scale composition analysis:
(1) The heat exchanger has a small flow area and a complicated internal structure, and it is difficult to discharge the cleaning liquid if it is precipitated.
(2) The heat exchanger plate is made of nickel-titanium alloy. Using hydrochloric acid as the cleaning liquid, it is easy to cause strong corrosion to the plate and shorten the service life of the heat exchanger.
(3) The main components of scale are calcium magnesium carbonate and iron oxide.
Through repeated tests, it was found that the choice of formic acid as the cleaning solution is the best.
The addition of a buffering agent and a surfactant to the formic acid cleaning solution provides a better cleaning effect and reduces the corrosion of the cleaning solution on the sheet.
Chemical tests on scale samples have shown that formic acid is effective in removing scale. Through the acid immersion test, it was found that formic acid can effectively remove the scale attached to the sheet, and its corrosion effect on the heat exchanger sheet is also small.