Method and reactor system for rapid kill gas injection to gas phase polymerization reactors
AssigneeMobil Oil Corporation
InventorsJohn E. Cook, Robert O. Hagerty, Frederick W. Jacob
Life of this patent
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Abstract
There is provided an improvement in a method for terminating a gas phase olefin polymerization reaction with a kill gas such as carbon monoxide or carbon dioxide. The improvement involves the use of a carrier gas to increase the rate of penetration of kill gas into the reaction medium. The improved method is particularly adaptable to a fluid bed reactor system.
Claims14
In a method of terminating, under emergency conditions, an olefin polymerization reaction conducted in the presence of a transition metal-based catalyst system in a substantially vertical gas phase reactor comprising a reactant inlet at the first end thereof and a venting means at the second end thereof to maintain the temperature of the reaction below the sintering temperature of the polymer, said method comprising opening the venting means and injecting an amount of a kill gas into the reaction medium in the reactor sufficient to terminate the reaction, the improvement comprising increasing the rate of penetration of the kill gas through the reaction medium in the reactor by injecting a sufficient penetration rate-increasing amount of a non-catalyst- poisoning carrier gas into the reaction medium along with said kill gas, said kill gas and said carrier gas being injected into the reactor at the first end thereof, thereby enabling the operation of the polymerization reaction at an increased operating temperature while maintaining a sufficient margin below the sintering temperature of the polymer particles to prevent sintering of the polymer particles in the event of the emergency conditions.
A method for rapidly terminating a gas phase olefin polymerization reaction in a fluid bed reactor system, said reactor system comprising a vertical fluid bed reactor wherein said polymerization takes said reactor powered by a compressor, said method being actuated in the event of failure of said compressor, said method comprising the steps of:
- (i) closing off said recycle line means;
- (ii) injecting an amount of carbon oxide gas sufficient to terminate said polymerization reaction, said injection taking place at the bottom of said reactor at a point below the polymer bed in said reactor;
- (iii) venting a gas from the top of the reactor at a point above said polymer bed;
- and
- (iv) injecting a nitrogen carrier gas at the bottom of said reactor at a point below the polymer bed in said reactor, the amount of said nitrogen carrier gas being sufficient to increase the rate at which said carbon oxide gas is transported to the top of said polymer bed thereby enabling the operation of the fluid bed reactor at an increased temperature as compared to the operating temperature thereof without the injection of the carrier gas,
- wherein said steps (i)-(iv) are carried out simultaneously, substantially simultaneously or in any particular sequence, provided that said steps are carried out in a manner such that the sintering temperature of the polymer in said polymer bed is not exceeded.
Dependencies are inferred from the claim text.