Pressure Management for Slurry Polymerization (Chevron)

CATEGORY: POLYMERIZATION 
Pressure Management for Slurry Polymerization (Chevron)

Type	Patent
Inventor	Scott E. Kufeld
Inventor	Bruce E. Kreischer
URL	Free Full Text Source:  http://www.google.com/patents/US20140121335
Assignee	Chevron Phillips Chemical Company Lp
Patent Number	US20140121335 A1
Issue Date	May 1, 2014
Abstract	Processes and systems for the production for pressure management of a polymerization product flowing from a loop polymerization reactor to a separation vessel in a slurry polymerization system are disclosed herein. For example, a process comprises withdrawing the polymerization product from a loop polymerization reactor, and conveying the withdrawn polymerization product to a separation vessel via a first pressure differential and a second pressure differential. The withdrawn polymerization product may flow through the first pressure differential before flowing through the second pressure differential, and the first pressure differential may be less than the second pressure differential. BACKGROUND Polyolefins such as polyethylene and polypropylene may be prepared by slurry polymerization. In this technique, feed materials such as diluent, monomer and catalyst are introduced to a loop reaction zone, forming a slurry in the reaction zone. In continuous loop reactors, the slurry circulates through the loop reaction zone, and the monomer reacts at the catalyst in a polymerization reaction. The polymerization reaction yields solid polyolefins in the slurry. A polymerization product having solid polyolefins is then transferred from the reactor and separated to recover the solid polyolefins. Operating pressures during transfer of the product can affect recovery of solid polyolefins; thus, pressure management can be important.