Cause analysis of increase of pressure drop in guard reactor of gasoline hydrotreating unit
Hou Lei;Deng Yunqing;Zhao Leping;Guan Minghua;SINOPEC Wuhan Company;SINOPEC Fushun Research Institute of Petroleum and Petrochemicals;
The causes of rapid increased pressure drop in the guard reactor in the OCT-MD hydrtreating unit were studied,and skimming was proposed. Due to the abnormal operation of the gas compressor in FCC Unit Ⅱ and the lubricant oil entering the stabilized gasoline,the existing gum in FCC gasoline was significantly increased from ≤5. 0 mg /(100 m L) to 10. 0 ~ 27. 0 mg /(100 m L),and the pressure drop in the guard reactor of OCT-MD Unit was rapidly raised from 0. 08 MPa to 0. 28 MPa. The SO_3,Na_2 O,Fe_2O_3and WO_3 in the powdered coke of skimming catalyst reached 50. 0%,22. 0%,8. 0% and 6. 0% respectively. All these show that dehydration separation is not complete in the sweetening section of FCC Unit and trace amounts of sodium and cobalt is entrained into the reactor. The cause of the increase of pressure drop in the reactor is that the coking precursor of lubricant oil and diolefin is polymerized coking based on sodium and iron as crystal nucleus. During the normal operation of FCC Unit Ⅱ,the basic properties of stabilized gasoline,sweetened gasoline and heavy distillates are normal,which will not lead to the rapid increase of pressure drop in prehydrogenation guard reactor.