FCC combustion zone catalyst cooling process

Claim 1

A process for the combustion of a combustible material present on fluidized catalyst particles employed in a hydrocarbon conversion process which comprises the steps of: (a) introducing a first stream of oxygen-containing combustion gas and said fluidized catalyst particles into a combustion zone maintained at a temperature sufficient for oxidation of said combustible material and therein oxidizing said combustible material to produce hot fluidized catalyst particles; (b) passing catalyst particles upward by fluidization from the combustion zone into a second zone located above the combustion zone, and collecting a dense phase bed of hot catalyst particles in a particle collection section located at the bottom of said second zone; (c) transferring a stream of catalyst particles downward from said particle collection section through a particle flow control means and a vertically orientated first particle transfer conduit into an upper end of a backmixed particle cooling chamber; (d) admixing said stream of catalyst particles into a backmixed dense phase particle bed located in a lower portion of the particle cooling chamber; (e) fluidizing said dense phase fluidized particle bed located in the particle cooling chamber in a controlled manner by the upward passage of a controlled flow of a second stream of oxygen-containing combustion gas; (f) cooling particles present in the backmixed dense phase fluidized particle bed located in the particle cooling chamber through the use of a heat exchanger entirely present in the lower portion of the particle cooling chamber; (g) discharging the second stream of combustion gas and catalyst particles from the cooling chamber into the combustion zone through a second particle transfer conduit communicating with the cooling chamber at a point above the heat exchanger, and (h) reducing or terminating the flow of the second stream of combustion gas and the admixture of said stream of particles into the dense phase particle bed located in the lower portion of the cooling chamber to thereby: (i) reduce or terminate the fluidization of the particle bed located in the lower portion of the cooling chamber and catalyst cooling as desired for operation of the process and thereby substantially covering at least a portion of said heat exchanger with a stagnant bed of catalyst particles while: (ii) still maintaining the downward flow of said stream of catalyst particles into the upper end of the cooling chamber and through said second particle transfer conduit into the combustion zone.