US 5,053,371 AGranted

Catalyst regeneration method with three-zone combustion gas addition

AssigneeUop LLC

InventorRobert R. Williamson

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Abstract

A semi-continuous process for combusting coke from catalyst particles in a fixed bed is improved by injecting combustion air for the regeneration section to the three places, upper air to the burn zone, middle air to the chlorination zone and lower air to the burn zone. By this method combustion gas is added the halogenation gas loop which circulates chlorination gas around the chlorination zone in substantially closed system. Any gas that leaves the chlorination zone flows into the burn zone from the chlorination zone. Thus, passing additional air to the chlorination zone increases the oxygen concentration of the chloriation gas to that additional oxygen-containing chlorination gas and chlorination gas with a higher oxygen concentration passes into the burn zone from the chlorination zone. This method adds air for coke combustion and improves platinum dispersion in the halogenation zone.

Claims24

Dependent claims

In a method of operating a continuous regeneration system for a reforming process, said regeneration section including a burn zone, a halogenation zone, and a drying zone in serial progression, comprising:

(a) passing catalyst particles containing a platinum group metal and having coke deposited thereon to said burn zone and contacting said catalyst particles with an oxygen-containing recycle gas to combust coke from said particles;
(b) continuously circulating said recycle gas from a flue gas outlet to a recycle gas inlet in a recycle gas loop, venting a vent gas comprising combustion products from said recycle loop, and adding a combustion gas comprising an oxygen-containing gas to said recycle gas loop in substantially equal mass flow to the amount of vent gas leaving the recycle loop;
(c) passing catalyst particles from said burn zone to said halogenation zone and contacting said catalyst particles with a halogen-containing gas in said halogenation zone and redispersing said platinum group metal on said catalyst;
(d) continuously circulating said halogen-containing gas from a halogenation gas outlet to a halogenation gas inlet in a halogenation loop and adding a halogen to said halogenation gas loop in an amount determined to maintain a halogen concentration in said halogenation loop;
(e) passing catalyst particles from said halogenation zone to a drying zone and contacting said catalyst particles with an oxygen-containing drying gas in said drying zone;
(f) passing said oxygen-containing drying gas to a lower portion of said drying zone;
(g) passing at least a portion of said oxygen-containing drying gas upwardly from said drying zone through said halogenation zone in admixture with said halogenation gas to provide, in part, combustion gas for said burn zone;
and,
(h) passing at least a portion of said halogenation gas into said burn zone to provide, in part, combustion gas for said burn zone,
the improvement comprising:
measuring the oxygen concentration of the recycle gas to determine the required addition of combustion gas to said regeneration zone and adding at least a portion of the combustion gas to satisfy said required addition of combustion gas to the portion of said halogenation gas flowing from said halogenation gas outlet to said halogenation gas inlet and said combustion gas is in addition to any other oxygen-containing gas that enters said halogenation loop.

8 more elements

In a method of operating a continuous regeneration system for a reforming process, said regeneration section including a serial progression of a burn zone, a chlorination zone, and a drying zone in a stacked vertical arrangement, comprising:

(a) passing catalyst particles containing a platinum group metal and having coke deposited thereon to the top of said burn zone, retaining catalyst particles in an annular catalyst bed that extends vertically through said burn zone and halogenation zone and contacting said catalyst particles with an oxygen-containing recycle gas by passing said recycle gas radially through said bed to combust coke from said particles;
(b) continuously circulating said recycle gas from a flue gas outlet to a recycle gas inlet in a recycle gas loop, venting a vent gas comprising combustion products from said from said recycle gas as it flow from said flue gas outlet to said flue gas inlet, adding a combustion gas comprising an oxygen-containing gas to said recycle gas loop in substantially equal mass flow to the amount of vent gas leaving the recycle loop, and adding a first portion of an oxygen-containing gas stream as a first portion of said combustion gas to said recycle gas as it flows from said flue gas outlet to said recycle gas inlet;
(c) passing catalyst particles from said burn zone to said halogenation zone and contacting said catalyst particles with a halogen-containing gas in said halogenation zone by passing said halogen-containing gas radially through said annular bed and redispersing platinum particles on said catalyst;
(d) continuously circulating said halogen-containing gas from a halogenation gas outlet to a halogenation gas inlet in a halogenation loop and adding a halogen and a second portion of an oxygen-containing gas stream to said halogenation gas loop as said halogen-containing gas flows from said halogenation gas outlet to said halogenation gas inlet in an amount determined to maintain a halogen concentration in said halogenation loop;
(e) passing catalyst particles from said halogenation zone to a a bed of catalyst particles in said drying zone and contacting said catalyst particles with a drying gas comprising a third portion of an oxygen-containing gas stream in said drying zone;
(f) passing said drying gas upwardly from a lower portion of said drying zone to an upper portion of said drying zone;
(g) passing at least a portion of said drying gas upwardly into said halogenation zone in admixture with said halogenation gas;
and,
(h) passing at least a portion of said halogen-containing gas vertically into said annular bed in said burn zone to provide, in part, combustion gas for said burn zone,
the improvement comprising,
measuring the oxygen concentration of the recycle gas to determine the required addition of combustion gas to said halogenation zone and adding a fourth portion of an oxygen-containing gas stream to said halogen-containing gas flowing from said halogenation gas outlet to said halogenation gas inlet to supply combustion gas to said regeneration zone.

8 more elements

A method of controlling a continuous reforming catalyst regeneration system to increase the coke burning capacity of the system, said regeneration section including in serial progression a burn zone, a halogenation zone, and a drying zone, said method comprising:

(a) passing catalyst particles containing a platinum group metal and having coke deposited thereon to said burn zone, retaining catalyst particles in said burn zone as a first catalyst bed and contacting said catalyst particles with an oxygen-containing recycle gas to combust coke from said particles;
(b) continuously circulating said recycle gas from a flue gas outlet to a recycle gas inlet in a recycle gas loop, venting a vent gas comprising combustion products from said recycle loop, adding a combustion gas comprising an oxygen-containing gas to said recycle gas loop in substantially equal mass flow to the amount of vent gas leaving the recycle loop, adding a first oxygen-containing stream to said recycle gas flowing from said flue gas outlet to said recycle gas inlet as a first portion of said combustion gas and passing said recycle gas through said first catalyst bed at a first average superficial velocity;
(c) measuring the concentration of oxygen in said recycle gas and the addition of said first oxygen-containing gas stream and generating a first signal representing said oxygen concentration of said recycle gas and a second signal representing the addition rate of said first oxygen-containing gas;
(d) passing catalyst particles from said burn zone to said halogenation zone and contacting said catalyst particles with a halogen-containing gas in said halogenation zone and redispersing platinum group metals on said catalyst;
(e) continuously circulating said halogen-containing gas from a halogenation gas outlet to a halogenation gas inlet in a halogenation loop and adding a halogen to said halogenation gas loop in an amount determined to maintain a halogen concentration in said adding a halogenation loop;
(f) passing catalyst particles from said halogenation zone to a drying zone, retaining catalyst particles in said drying zone as a second catalyst bed and contacting said catalyst particles with a drying gas comprising a second oxygen-containing gas in said drying zone;
(g) passing said drying gas to a lower portion of said drying zone, measuring the rate of addition of said oxygen-containing gas, generating a third signal representing the rate of addition of said oxygen-containing gas, and passing said drying gas through said drying zone at a second average superficial velocity;
(h) passing said drying gas upwardly through said halogenation zone in admixture with said halogenation gas;
(i) passing at least a portion of said halogenation gas into said burn zone to provide, in part, combustion gas for said burn zone;
(j) comparing said first signal with a first set point for oxygen concentration in the range of from 0.25 to 2.0 mol. %, said second signal with a second set point for gas addition, and said third signal with a set point for gas addition;
(k) charging a third oxygen-containing gas stream to said halogenation gas stream flowing from said halogenation gas outlet to said halogenation gas inlet to supply additional combustion gas to said burn zone to prevent said first, second and third signals from exceeding said first, second and third set points.

8 more elements

Dependencies are inferred from the claim text.