Abstract: Due to the excessive pressure drop of reaction system, unstable running of recycle hydrogen compressor and short processing period of the 500 kt/a coker gasoline hydrofining unit in Sinopec Maoming Company, an analysis of the pressure drop in heat exchanger and reactor was carried out. Results showed that fouling happened in the shell side of the high pressure heat exchanger and the top section of reactor was the main cause of the excessive pressure drop. By analyzing the fouling materials, it was found that coke formed by the condensation reactions of dienes and resin existed in the feed was the main component of the fouling materials. Measures, such as properly controlling the feed quality, using guard catalyst, increase the porosity of the reactor top section and optimizing operation conditions, could significantly decrease the coking rate of feed, and the operation period of the unit was prolonged.

Key words: coker gasoline, hydrofining, scale, diene