Research On Restrictive Factors And Solutions For The Long-term Operation Of Catalytic Cracking

Fluid Catalytic Cracking(FCC)technology,which has experienced eight decades of development since its emergence in 1936,has firmly occupied the core position of the secondary operation of the refining industry.At present,FCC gasoline and diesel account for approximately 2/3 of gasoline product and1/4~1/5 diesel product in China,respectively.Despite the rapid development of new energy technology,its large-scale application still needs the testing of time and FCC technology will maintain its core status in fuel production for a period of time.Along with the further development of FCC technology,the role of producing chemical raw material becomes more crucial,building the bridge between refining and chemical industry.Because of the crucial role of FCC,any abnormal production-event and unscheduled plant shutdown could result in significant impact.Therefore,the long-term operation of FCC plant turns into the major concern for every refinery.This paper takes the long-term operation of the third FCC plant in our refinery as the research object,finding out the two key aspects that restrict the long-term operation by comparing the operation conditions during seven periods: One is coking problem and the other one is equipment failure.Coking problem mainly occurs in the reaction system and the main column slurry system.Reaction system: Analysis is based on the properties of raw material,processing load,and structure of the equipment.Heavier feedstock makes atomization more difficult and overloading operation with impropriate conditions get it even worse,massive un-atomized oil provides material for coking.Old equipment in service cannot meet the demand of production,resulting in the term of coking.Bring out the breakthrough point of the reaction system coking problem,which is: eliminate or reduce un-atomized oil and upgrade equipment to disrupt the coking condition.Slurry system: Analysis proceeds by internal and external aspects.The denser slurry is the internal factor of the coking problem and the external factoris the impropriate operating condition.Bring out the breakthrough point of the slurry system coking problem,which is: optimize slurry properties and operating condition.Equipment failure problem mainly occurs in the reactor-regenerator internals and large-scale generating unit.Internals: For common problems like the low design standard and short service life,it can be solved by developing the design and manufacture standards.For ineffective management and impropriate operating problem,optimizing of management and operating regulations should be concerned.For maintenance and checking problem,a precise maintenance plan and stricter checking and accepting standards should be established to make sure the safety responsibility system work effectively level by level.Large-scale generating unit: According to the present operating situation of the crucial generating unit(Three machine sets(blower,flue gas turbine,generator),compressor,booster)of the third FCC plant,the analysis is focused on the compressor operation situation,based on the problems,and factors that affecting long-term operation,combined with typical accident cases.Some suggestions and measures are put forwards also.In the end,the relations between FCC plant scale-up and long-term operation are discussed.It is considered that the FCC plant scale-up is ripe enough in China and the scale-up will have a positive impact on the plant long-term operation.