1) pickling temperature: increasing the pickling temperature is conducive to improve the descaling effect, if the temperature is too high, it will aggravate the corrosion of the acid washing plate on the heat exchanger plate, through repeated tests, acid The washing temperature is preferably controlled at 60 °C.
2) pickling solution concentration: According to repeated trials, the acid washing solution should be prepared according to the concentration of formic acid 81.0%, water 17.0%, buffer 1.2%, surfactant 0.8%, cleaning effect it is good.
3) pickling method and time: pickling method should be combined with static soaking and dynamic cycling. The pickling time is first static soaking for 2 h, then dynamic cycling for 3-4 h. The pickling concentration should be sampled frequently during the pickling process. When the difference between the two adjacent assays is less than 0.2%, the pickling reaction is considered to be complete.
4) passivation treatment: after the end of pickling, the scale and metal oxide on the surface of the plate heat exchanger are mostly dissolved and detached, exposed to new metal, easy to corrode, so pickled After that, the heat exchanger sheets are passivated.