Fluid catalytic cracking with supplemental heat

Abstract

A potentially heat-deficient fluid catalytic cracking process for effecting a bulk boiling point conversion of a high boiling point petroleum feed to lower boiling products in which the overall enthalpy balance between the endothermic cracking and exothermic regeneration is maintained by combustion of a supplemental fuel in the middle or upper region of the dense bed in the regenerator (including the region immediately above the dense phase bed). There is a direct economic benefit from operation of the cracking process in this way since the preferred supplemental fuel is methane (natural gas) which is currently a low cost fuel while liquid products are higher value. Use of natural gas as a supplemental fuel will allow re-optimization of the catalyst and operations separately from the heat balance demand.

What is claimed is: 
     
         1 . In a fluid catalytic cracking process for effecting a bulk boiling point conversion of a high boiling point petroleum feed to lower boiling products in which the feed is contacted with a hot cracking catalyst to effect endothermic cracking of the feed after which the spent catalyst is exothermically regenerated by oxidative combustion of coke deposited on the catalyst during the cracking in a fluidized regeneration bed of catalyst in a regeneration step, the improvement comprising combusting a supplemental fuel in the middle or upper region of the regeneration bed or the region immediately above the bed. 
     
     
         2 . A fluid catalytic cracking process according to  claim 1  in which the combustion of the supplemental fuel maintains an overall enthalpy balance between the endothermic cracking and exothermic regeneration. 
     
     
         3 . A fluid catalytic cracking process according to  claim 1  in which the supplemental fuel is injected into the middle region of the regeneration bed at a level at which the amount of oxygen in the bed is adequate to ensure combustion of the supplemental fuel. 
     
     
         4 . A fluid catalytic cracking process according to  claim 1  in which the supplemental fuel is injected into the dense bed in the upper region of the regeneration bed at a level at which the amount of oxygen in the bed is adequate to ensure combustion of the supplemental fuel. 
     
     
         5 . A fluid catalytic cracking process according to  claim 1  in which the supplemental fuel is injected into the dense bed at a level where catalyst particles enter a dilute phase above the dense bed and at which the amount of oxygen in the bed is adequate to ensure combustion of the supplemental fuel. 
     
     
         6 . A fluid catalytic cracking process according to  claim 1  in which the supplemental fuel comprises a gaseous fuel. 
     
     
         7 . A fluid catalytic cracking process according to  claim 1  in which the supplemental fuel comprises natural gas. 
     
     
         8 . A fluid catalytic cracking process according to  claim 1  in which the supplemental fuel comprises syngas. 
     
     
         9 . A fluid catalytic cracking process according to  claim 1  in which the high boiling point petroleum feed comprises a distillate feed. 
     
     
         10 . A fluid catalytic cracking process according to  claim 1  in which the high boiling point petroleum feed comprises a distillate feed having an end point not higher than 550° C.