Fluidized bed reaction systems
AssigneeUnion Carbide Corporation
InventorsJohn M. Jenkins, III, Russell L. Jones, Thomas M. Jones
Life of this patent
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Abstract
A process is described for increasing the space time yield of polymer production in a fluidized bed reactor employing an exothermic polymerization reaction by cooling the recycle stream to below its dew point and returning the resultant two-phase fluid stream to the reactor to maintain the fluidized bed at a desired temperature above the dew point of the recycle stream.
Claims39
In a continuous gas fluidized bed polymerization process for the production of polymer from monomer by continuously passing a gaseous stream comprising said monomer through a fluidized bed reactor in the presence of catalyst under reactive conditions, withdrawing polymeric product and a stream comprising unreacted monomer gases, cooling said stream comprising unreacted monomer gases and returning said cooled stream to said reactor together with sufficient additional monomer to replace that monomer polymerized and withdrawn as product, the improvement which comprises:
- cooling part or all of said stream comprising unreacted monomer gases to form a mixture comprising a gas phase and a liquid phase and reintroducing said mixture into said reactor wherein said liquid phase is vaporized.
A method for controlling the temperature of a gas fluidized bed during the production of polymer in a fluidized bed reactor by an exothermic polymerization reaction, which comprises continuously introducing into the bed a stream comprising unreacted monomer gas cooled to below the maximum desired temperature within said bed and simultaneously or separately introducing a stream of liquid into said reactor under conditions such that an essentially uniform mixture of said gas and liquid is introduced into said bed at a level below the region of maximum desired temperature within said reactor wherein said liquid is vaporized.
A process for producing polymer from monomer by an exothermic polymerization reaction in a gas fluidized bed reactor having an upper polymerization zone containing a bed of growing polymer particles and a lower gas diffusion zone, which comprises:
- (1) continuously passing a gaseous stream comprising monomer through said polymerization zone with an upward velocity sufficient to maintain said particles in a suspended and gas fluidized condition;
- (2) introducing a polymerization catalyst into said polymerization zone;
- (3) withdrawing polymer product from said polymerization zone;
- (4) continuously withdrawing a stream of unreacted gases comprising monomer from said polymerization zone, compressing and cooling said stream to a temperature below the dew point of said stream to form a mixture comprising a gas phase and a liquid phase;
- and
- (5) continuously introducing said mixture into said polymerization zone wherein said liquid phase is vaporized.
A method for controlling the temperature of a fluidized bed during the production of polymers in a gas fluidized bed reactor by an exothermic polymerization reaction which comprises continuously introducing a stream comprising an essentially uniform gas-liquid mixture containing monomer into said bed wherein said liquid is vaporized.
In a continuous gas fluidized bed polymerization process for the production of polymer from monomer by continuously passing a gaseous stream comprising said monomer through a fluidized bed reactor in the presence of catalyst under reactive conditions, withdrawing polymeric product and a stream comprising unreacted monomer gases, cooling said stream comprising unreacted gases and returning said cooled stream to said reactor together with sufficient additional monomer to replace that monomer polymerized and withdrawn as product, the improvement which comprises:
- cooling part or all of said stream comprising unreacted gases to form a mixture comprising a gas phase and a liquid phase and reintroducing said mixture into said reactor wherein said liquid phase is volatilized;
- said gaseous stream passing through said fluidized bed reactor at a superficial velocity sufficient to maintain a viable fluidized bed.
A process for producing polymer from monomer by an exothermic polymerization reaction in a gas fluidized bed reactor having an upper polymerization zone containing a bed of growing polymer particles and a lower gas diffusion zone, which comprises:
- (1) continuously passing a gaseous stream comprising monomer through said polymerization zone with an upward velocity sufficient to maintain said particles in a suspended and gas fluidized condition;
- (2) introducing a polymerization catalyst into said polymerization zone in an inert gas stream at a point 20-40% of the diameter away from the reactor wall and about 5-30% of the height of the bed;
- (3) withdrawing polymer product from said polymerization zone;
- (4) continuously withdrawing a stream of unreacted gases comprising monomer from said polymerization zone, compressing and cooling said stream to a temperature below the dew point of said stream to form a mixture comprising a gas phase and a liquid phase;
- and
- (5) continuously introducing said mixture into said polymerization zone wherein said liquid phase is vaporized.
A process for producing polymer from monomer by an exothermic polymerization reaction in a gas fluidized bed reactor having an upper polymerization zone containing a bed of growing polymer particles and a lower gas diffusion zone, which comprises:
- (1) continuously passing a gaseous stream comprising monomer through said polymerization zone with an upward velocity sufficient to maintain said particles in a suspended and gas fluidized condition;
- (2) introducing a polymerization catalyst into said polymerization zone;
- (3) withdrawing polymer product from said polymerization zone;
- (4) continuously withdrawing a stream of unreacted gases comprising monomer from said polymerization zone, compressing and cooling said stream to a temperature below the dew point of said stream to form a mixture comprising a gas phase and a liquid phase;
- (5) continuously introducing said mixture into said polymerization zone wherein said liquid phase is vaporized;
- and
- (6) controlling the temperature of said mixture so as to maintain constant temperature in said polymerization zone, as the change in polymerization catalyst feed is varied to control the rate of said polymerization.
In a continuous gas fluidized bed polymerization process for the production of polymer from monomer comprising ethylene and/or propylene by continuously passing a gaseous stream comprising said monomer through a fluidized bed reactor in the presence of catalyst under reactive conditions, withdrawing polymeric product and a stream comprising unreacted gases, comprising monomer, cooling said stream comprising unreacted gases and returning said cooled stream to said reactor together with sufficient additional monomer to replace that monomer polymerized and withdrawn as product, the improvement which comprises:
- cooling part or all of said stream comprising unreacted gases to form a mixture comprising a gas phase and a liquid phase and reintroducing said mixture into said reactor wherein said liquid phase is vaporized.
Dependencies are inferred from the claim text.