Systems and Methods for Polyethylene Recovery with Low Volatile Content
AssigneeChevron Phillips Chemical Company LP
InventorsKenneth A. Dooley, Jeffrey S. Lowell, Joseph A. Curren, Scott E. Kufeld
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Abstract
The present invention discloses methods for removing volatile components from an ethylene polymer effluent stream from a polymerization reactor, and related polyethylene recovery and volatile removal systems. In these methods and systems, the polymer solids temperature is increased significantly prior to introduction of the polymer solids into a purge column for the final stripping of volatile components from the polymer solids.
Claims21
1-20. (canceled)
A method for removing volatile components from an ethylene polymer effluent stream from an ethylene polymerization reactor, the method comprising:
- (i) reducing a pressure of the effluent stream to remove a first portion of the volatile components from polymer solids, wherein:
- the pressure is reduced to a range from about 2 to about 200 psig, and
- the polymer solids have a solids temperature from about 10° F. to about 50° F. less than a reaction temperature in the ethylene polymerization reactor;
- (ii) fluidizing the polymer solids while heating to increase the solids temperature from at least about 10° F. above the solids temperature in step (i) and up to about 20° F. greater than the reaction temperature, and wherein a second portion of the volatile components are removed;
- and
- (iii) contacting the polymer solids with a stripping gas to remove a third portion of the volatile components to form a polymer solids stream containing less than 40 ppm by weight (ppmw) of volatile components.
A method for removing volatile components from an ethylene polymer effluent stream from an ethylene polymerization reactor, the method comprising:
- (I) contacting the effluent stream with a fluidizing gas at a reduced pressure while heating to remove an initial portion of the volatile components from polymer solids, the polymer solids having a solids temperature from about 30° F. less to about 20° F. greater than a reaction temperature in the ethylene polymerization reactor;
- and
- (II) contacting the polymer solids with a stripping gas to remove a final portion of the volatile components to form a polymer solids stream containing less than 40 ppm by weight of volatile components.
A polyethylene recovery and volatile removal system comprising:
- (a) a flash chamber for reducing a pressure of an ethylene polymer effluent stream from an ethylene polymerization reactor and for removing a first portion of volatile components from polymer solids, wherein the flash chamber is configured to form the polymer solids at a solids temperature from about 10° F. to about 50° F. less than a reaction temperature in the ethylene polymerization reactor;
- (b) a fluidized bed heater for fluidizing the polymer solids and for heating the polymer solids to a solids temperature from at least about 10° F. above the solids temperature in (a) and up to about 20° F. greater than the reaction temperature, wherein the fluidized bed heater is configured to remove a second portion of the volatile components;
- (c) a purge column for contacting the polymer solids with a stripping gas, wherein the purge column is configured to remove a third portion of the volatile components to form a polymer solids stream containing less than 100 ppmw (ppm by weight) of volatile components;
- and
- (d) an extruder for converting the polymer solids stream into solid polymer pellets.
A polyethylene recovery and volatile removal system comprising:
- (A) a heated fluidized bed flash chamber for heating and for reducing a pressure of an ethylene polymer effluent stream from an ethylene polymerization reactor, and for removing an initial portion of volatile components from polymer solids, wherein the heated fluidized bed flash chamber is configured to form the polymer solids at a solids temperature from about 30° F. less to about 20° F. greater than a reaction temperature in the ethylene polymerization reactor;
- and
- (B) a purge column for contacting the polymer solids with a stripping gas, wherein the purge column is configured to remove a final portion of the volatile components to produce a polymer solids stream containing less than 100 ppmw of volatile components;
- wherein:
- the ethylene polymerization reactor is a loop slurry reactor or a gas phase reactor.
Dependencies are inferred from the claim text.