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HYDROGEN REMOVAL FOR RAPID POLYOLEFIN TRANSITIONS

IP.com Disclosure Number: IPCOM000209066D
Publication Date: 2011-Jul-25
Document File: 1 page(s) / 13K

Publishing Venue

The IP.com Prior Art Database

Abstract

Two methods are described to remove hydrogen from gas phase polyolefin reactors, thereby speeding product transitions and reducing the amount of reactor off-grade. The method involves the use of two systems to remove reactor hydrogen, a hydrogen separation system and a hydrogenation system. The two systems are used in a coordinated fashion to remove hydrogen from the cycle. The hydrogen separation system is used when relatively high levels of hydrogen are present in the cycle gas, and when there is no relative need for additional reactor inerts. The hydrogenation system is used when the hydrogen separation system is inefficient due to low hydrogen concentration, and/or there is a desire to add reactor inerts. Hydrogen removal is often the economic limiting step in transitioning from one resin grade to another. Rapid hydrogen removal (without substantial cycle gas venting) can reduce off-grade. The operation of the two systems is determined by use of a reaction system optimizer, which may be performed by either a computer or manually by operation’s personnel. By removing hydrogen from the cycle, or converting the hydrogen to a favorable inert, one can optimize the plant operating conditions.

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HYDROGEN REMOVAL FOR RAPID POLYOLEFIN TRANSITIONS

Two methods are described to remove hydrogen from gas phase polyolefin reactors, thereby speeding product transitions and reducing the amount of reactor off-grade. The method involves the use of two systems to remove reactor hydrogen, a hydrogen separation system and a hydrogenation system. The two systems are used in a coordinated fashion to remove hydrogen from the cycle. The hydrogen separation system is used when relatively high levels of hydrogen are present in the cycle gas, and when there is no relative need for additional reactor inerts. The hydrogenation system is used when the hydrogen separation system is inefficient due to low hydrogen concentration, and/or there is a desire to add reactor inerts. Hydrogen removal is often the economic limiting step in transitioning from one resin grade to another. Rapid hydrogen removal (without substantial cycle gas venting) can reduce off-grade. The operation of the two systems is determined by use of a reaction system optimizer, which may be performed by either a computer or manually by operation's personnel. By removing hydrogen from the cycle, or converting the hydrogen to a favorable inert, one can optimize the plant operating conditions.

The hydrogen separation system can utilize a permeable membrane or other means to separate hydrogen from the cycle. The hydrogenation system uses a catalyst bed to provide hydrogenation of the primary reactor olefin. The two s...