Heat recovery technique for catalyst regenerator flue gas

A process for catalytic conversion using a molecular sieve catalyst which accumulates carbonaceous deposit during operation of a catalytic reactor, wherein the carbonaceous deposit is removed in a high temperature regenerator unit with a regeneration medium, the process comprising the steps of:

• (a) passing a high temperature effluent stream from the regenerator unit to a heat exchanger associated with a steam generator fed with preheated boiler feed water, to produce high pressure steam and a partially cooled effluent stream;
• (b) passing the partially cooled effluent stream to a heat exchanger associated with a high pressure boiler feed water preheater to provide preheated boiler feed water and further cooled effluent stream;
• (c) passing the preheated boiler feed water and the high pressure steam from the steam generator to a steam drum for direct contact and mixing;
• (d) recovering high pressure steam from the steam drum;
• and
• (e) passing liquid preheated boiler feed water from the steam drum to the steam generator, thereby providing efficient recovery of thermal values,
• wherein the high temperature effluent stream has a temperature of at least about 650° C., the partially cooled effluent stream has a temperature not greater than about 262° C., and the further cooled effluent stream has a temperature not greater than about 127° C.