US 4,859,643 A · Regeneration method with reduced catalyst heat exposure

Abstract

A method for regenerating coke-contaminated catalyst particles achieves better utilization of oxygen and minimizes surface area loss of the catalyst by confining particles in the combustion section of a regeneration zone to a tapered bed configuration. In this method, catalyst particles move through the regeneration zone in continuous or semi-continuous flow and are formed into a vertically elongated bed of particles in the regeneration zone. An oxygen-containing gas is passed through the particle bed in a transverse direction and initiates combustion of the coke deposits along a burn front that extends diagonally through the catalyst bed from the inlet surface of the bed to the outlet surface of the bed. The catalyst bed is tapered to reduce the volume of catalyst particles behind the burn wave, with respect to gas flow through the bed, thereby increasing the gas flow through the upper portion of the bed and removing catalyst that would be exposed to high temperature flue gas flowing across the bed from the burn front. The method of this invention can confine catalyst particles to a bed having a continuous taper or the thickness of the bed may be varied by confining the catalyst in discrete bed portions that increase progressively down the length of the bed. This method of regeneration can also include steps for halogenation and drying of the catalyst particles. A particularly useful application of this invention is in reforming processes.

Claims20

Dependent claims

A method of removing coke from the surface of solid catalyst particles in a regeneration zone through which the particles move in at least semi-continuous flow, aid method comprising:

(a) passing catalyst particles containing coke deposits into said regeneration zone;
(b) forming a vertically elongated bed of said particles in a combustion section of said regeneration zone;
(c) at least periodically moving said particles down said bed;
(d) introducing an oxygen-containing gas into said combustion section in an amount sufficient to provide breakthrough of said oxygen-containing gas, passing said gas into an inlet face of said bed in a direction generally transverse to the direction of catalyst flow so that the oxygen-containing gas passes through the upper portion of said combustion section at a superficial velocity that is greater than the superficial velocity of the gas passing through a lower portion of the combustion section, and initiating combustion of said coke deposits along a burn front that extends vertically through said combustion section, said front having a width less than the width of said bed, said burn front starting at the uppermost point of said inlet face and extending down said catalyst bed at an angle such that the distance from said inlet face to said burn increases with its distance from said uppermost point;
(e) collecting a flue gas, produced by combustion of said coke, from an outlet face of said bed, and removing said flue gas from said regeneration zone;
(f) decreasing the duration of travel of said flue gas in at least an upper portion of said combustion section after said flue gas exits said burn front;
and
(g) withdrawing particles from the bottom of said bed below a point in said combustion section at which breakthrough of said oxygen-containing gas occurs, and adding catalyst particles to the top of said bed thereby causing said moving of said particles.

5 more elements

A method of removing coke from catalyst particles in a regeneration zone containing a vertically extended and continuous combustion section through which the particles move in at least semi-continuous flow, said method comprising:

(a) passing catalyst particles containing coke deposits into said regeneration zone;
(b) forming a vertically elongated bed of said particles in said combustion section of said regeneration zone;
(c) at least periodically moving said particles down said bed by withdrawing particles from the bottom of said bed and adding catalyst particles to the top of said bed;
(d) introducing an oxygen-containing gas into said combustion section, by passing all of said gas into a distribution space that communicates with an inlet face of said bed, said distribution space providing open communication for said gas with said inlet face over the length of said combustion section, passing said gas through said bed in a direction generally transverse to the direction of catalyst flow, at a differential flow rate that is greatest at an upper portion of said combustion section and lowest in a lower portion of said combustion section, and initiating combustion of said coke deposits along a burn front that extends vertically through said combustion section, said front having a width less than the width of said bed, said burn front starting at the uppermost point of said inlet face and extending down said catalyst bed at an angle such that the distance from said inlet face to said burn front increases with its distance from said uppermost point and said continuous combustion section having sufficient length for breakthrough of said oxygen-containing gas to occur within said combustion section;
(e) collecting a flue gas, produced by combustion of said coke, from an outlet face of said bed, and removing said flue gas from said regeneration zone;
and
(f) reducing the volume of said particles between said burn front and said outlet face by confining said bed to have a smaller thickness at the top of said combustion section than the thickness of said bed at the bottom of said combustion section.

4 more elements

Dependencies are inferred from the claim text.

Regeneration method with reduced catalyst heat exposure

Life of this patent

Regeneration method with reduced catalyst heat exposure

Life of this patent

Abstract

Claims20