Abstract: Coking and blockage of feed heat exchanger in the S Zorb unit of a refining and chemical company affected the long-term operation of the unit and safe and stable production of the whole plant. Through analysis and judgment, the main reasons of coking and blockage in the heat exchanger were the high content of gum in the feed gasoline, unclean on-line cleaning of the heat exchanger and impurities in the feed.The coking and blockage situation of the feed heat exchanger in the unit has been obviously improved by taking some measures, such as strengthening the management of feedstocks, improving the cleaning method of heat exchanger, and adding scale inhibitor. The operation period of the heat exchanger was increased from 2 months to more than 14 months.

Key words: gasoline, S Zorb, adsorptive desulfurization, heat exchanger, coking, scale inhibitor