What should I pay attention to when cleaning industrial process chiller?
Selection of cleaning agent:
The current choice of cleaning agent is acid cleaning, which includes organic acid and inorganic acid. Organic acids mainly include oxalic acid and formic acid. Inorganic acids mainly include hydrochloric acid, nitric acid, etc. According to the analysis of cooler scaling and process, material and scale composition, it is concluded that:
1) The FL +5°C ~ +35°C Water Chillers has a small flow area and a complex internal structure, and it is difficult to discharge the cleaning fluid if it precipitates.
2) The cooler is made of nickel-titanium alloy, and hydrochloric acid is used as the cleaning fluid. It is easy to cause strong corrosion to the plates and shorten the service life of the cooler. Through repeated tests, it is found that the best effect is to choose formic acid as cleaning solution.
Adding buffer and surfactant to the formic acid cleaning solution can achieve better cleaning effect and reduce the corrosion of the cleaning solution to the plate. The chemical test of scale samples shows that formic acid can effectively remove scale. Through acid immersion test, it is found that formic acid can effectively remove the scale attached to the plate, and it has little corrosion effect on the cooler plate.
Basic principle of scale removal:
1) Dissolution: The acid solution is easy to react with calcium, magnesium and carbonate salt water scale to form soluble compounds to dissolve the scale.
2) Stripping action: acid solution can dissolve the oxide on the metal surface and destroy the combination with scale. Thus, the scale attached to the metal oxide surface is stripped. And fall off.
3) Air lift: after the reaction of acid solution with calcium, magnesium and carbonate salt scale, a large amount of carbon dioxide is produced. Carbon dioxide gas is in the process of overflow. For the scale layer that is difficult to dissolve or slow to dissolve, it has certain lifting power to make the scale fall off from the heating surface of the cooler.
4) Loosening effect: For scale containing silicate and sulfate mixture, due to the dissolution of calcium, magnesium, carbonate and iron oxides in the acid solution, the remaining scale will become loose and easy to be washed down by the flowing acid solution.