Process and apparatus for catalytically cracking hydrocarbons with recycled slurry filter backflush

Abstract

A process for catalytically cracking hydrocarbons is disclosed. The process comprises contacting a hydrocarbon feed stream with a catalyst to catalytically crack the hydrocarbon feed stream to provide a cracked stream and spent catalyst. The spent catalyst is disengaged from the cracked stream in a reactor vessel. Hydrocarbons are stripped from the spent catalyst. The cracked stream is fractionated in a main fractionation column into products comprising a slurry oil stream from a bottom of the main fractionation column. The slurry oil stream is filtered in a filter vessel through a filter to provide a filtered slurry oil stream. Thereafter, the filter is backflushed with a hydrocarbon stream to produce a backflushed hydrocarbon stream comprising catalyst fines. The backflushed hydrocarbon stream is recycled to the reactor vessel. An apparatus for catalytically cracking hydrocarbons is also disclosed.

1 . A process for catalytically cracking hydrocarbons, comprising:
 contacting a hydrocarbon feed stream with a catalyst to catalytically crack said hydrocarbon feed stream to provide a cracked stream and spent catalyst;   disengaging said spent catalyst from said cracked stream in a reactor vessel;   stripping hydrocarbons from said spent catalyst;   fractionating said cracked stream in a main fractionation column into products comprising a slurry oil stream;   filtering said slurry oil stream through a filter to provide a filtered oil stream;   backflushing the filter with a hydrocarbon stream to produce a backflushed hydrocarbon stream comprising catalyst fines; and   recycling said backflushed hydrocarbon stream to the reactor vessel.   
     
     
         2 . The process of  claim 1 , wherein said hydrocarbon stream is a naphtha stream. 
     
     
         3 . The process of  claim 1 , wherein the step of backflushing the filter comprises:
 passing a washing fluid to the filter vessel to wash the filter; and   passing said hydrocarbon stream through the filter vessel to backflush the filter.   
     
     
         4 . The process of  claim 3 , wherein the washing fluid comprises light cycle oil, heavy cycle oil or a mixture thereof. 
     
     
         5 . The process of  claim 1 , wherein the step of recycling said backflushed hydrocarbon stream comprises passing said backflushed hydrocarbon stream to the reactor vessel at a location above or in a catalyst bed in the reactor vessel. 
     
     
         6 . The process of  claim 1 , wherein the reactor vessel communicates with a riser reactor and further comprises a disengaging chamber in fluid communication with the riser reactor, and a stripping section in fluid communication with the disengaging chamber. 
     
     
         7 . The process of  claim 6  further comprising passing said backflushed hydrocarbon stream to the stripping section through a distributor. 
     
     
         8 . The process of  claim 7 , wherein the distributor has an outlet located inside the disengaging chamber. 
     
     
         9 . The process of  claim 2 , wherein said naphtha stream is taken from the main fractionation column. 
     
     
         10 . The process of  claim 6  further comprising recycling said filtered slurry oil stream to the riser reactor. 
     
     
         11 . A process for catalytically cracking hydrocarbons, comprising:
 contacting a hydrocarbon feed stream with a catalyst to catalytically crack said hydrocarbon feed stream to provide a cracked stream and spent catalyst;   disengaging said spent catalyst from said cracked stream into a catalyst bed in a reactor vessel;   stripping hydrocarbons from said spent catalyst;   fractionating said cracked stream in a main fractionation column into products comprising a slurry oil stream;   filtering said slurry oil stream in a filter vessel through a filter to provide a filtered slurry oil stream;   backflushing the filter with a naphtha stream to produce a backflushed naphtha stream comprising catalyst fines; and   recycling said backflushed naphtha stream to a location above or in the catalyst bed in the reactor vessel.   
     
     
         12 . The process of  claim 11 , wherein the naphtha stream is a heavy naphtha stream. 
     
     
         13 . The process of  claim 11 , wherein the naphtha stream is taken from the main fractionation column. 
     
     
         14 . The process of  claim 1 , wherein the step of backflushing the filter comprises:
 passing a washing fluid to the filter vessel to wash the filter; and   passing said naphtha stream through the filter vessel to backflush the filter.   
     
     
         15 . An apparatus for catalytically cracking hydrocarbons, comprising:
 a riser reactor, a disengaging chamber in fluid communication with the riser reactor, a stripping section in fluid communication with the disengaging chamber;   a filter; and   a distributor in fluid communication with the filter and the stripping section in fluid communication with the filter.   
     
     
         16 . The apparatus of  claim 15 , wherein the filter is in a filter vessel and the distributor is in fluid communication with the filter vessel and the stripping section is in fluid communication with the filter vessel. 
     
     
         17 . The apparatus of  claim 15  further comprising a main fractionation column in fluid communication with said riser reactor and said filter vessel in fluid communication with said main column. 
     
     
         18 . The apparatus of  claim 15 , wherein the distributor is located inside the disengaging chamber. 
     
     
         19 . The apparatus of  claim 15 , wherein the distributor is located above or in a catalyst bed in the disengaging chamber. 
     
     
         20 . The apparatus of  claim 15  further comprising a second distributor in fluid communication with the filter and the riser reactor in fluid communication with the second distributor.