The article presents results of the research on the dissolution of synthetic microporous zeolites KA-U in solutions of acetic and citric acids. The efficiency of zeolite dissolution in 3-10 wt.% acetic acid is 92-95%. For a system containing 20 wt.% citric acid, the percentage of dissolution of zeolites was 98%. The need for active mixing and an insignificant effect of temperature on the process of zeolite dissolution has been established. In winter, in particular, at temperatures below -10 °C, it is proposed to use water-methanol solutions to dissolve zeolites. The optimal composition was chosen based on 10 wt.% citric acid and 50 vol.% water-alcohol solution of methanol, the solubility of the zeolite was 45%. The selected composition has a low freezing point (below -400 °C). To avoid corrosion of aluminum equipment, corrosion studies were carried out, and the corrosive activity of organic acid solutions on aluminum samples was determined. In these systems, the aluminum corrosion rate is insignificant and amounts to 0.11 mm/year. Pilot tests were carried out at the UPPPNG-3.6 unit for the dissolution of zeolite deposits with solutions of organic acids in the cavity of the E-400 heat exchanger in winter and summer periods. Taking into account the cold season, a reagent based on 10 wt.% citric acid and 50 vol.% water-alcohol solution was chosen. The technological efficiency of the cleaning process was 51%. In summer, the heat exchanger chamber was treated with citric acid solutions and satisfactory results were obtained. The proposed compositions of citric acid were tested on AC-620 and AC-480 air coolers of the UPPPNG-3.6 unit for cleaning calcium carbonate deposits. It has been found that the use of 17-36.5 wt.% aqueous solutions of citric acid completely removes calcium carbonate from the outer surface of the heat exchanger.
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