a stripping vessel is located immediately below the disengaging vessel outlet to receive catalyst as it leaves the dissipator plates application_number US 25073094 A description looking first at a more complete description of the fcc process the typical feed to an fcc unit is a gas oil such as a light or vacuum gas oil other petroleum derived feed streams to an fcc unit may comprise a diesel boiling range mixture of hydrocarbons or heavier hydrocarbons such as reduced crude oils it is preferred that the feed stream consist of a mixture of hydrocarbons having boiling points as determined by the appropriate astm test method above about 230 u00b0 c and more preferably above about 290 u00b0 c it is becoming customary to refer to fcc type units which are processing heavier feedstocks such as atmospheric reduced crudes as residual crude cracking units or residual cracking units the process and apparatus of this invention can be used for either fcc or residual cracking operations for convenience the remainder of this specification will only make reference to the fcc process the chemical composition and structure of the feed to an fcc unit will affect the amount of coke deposited upon the catalyst in the reaction zone normally the higher the molecular weight conradson carbon heptane insolubles and carbon hydrogen ratio of the feedstock the higher will be the coke level on the spent catalyst also high levels of combined nitrogen such as found in shale derived oils will increase the coke level on spent catalyst processing of heavier feedstocks such as deasphalted oils or atmospheric bottoms from a crude oil fractionation unit commonly referred to as reduced crude results in an increase in some or all of these factors and therefore causes an increase.