Polymerization Product Pressures in Olefin Polymerization

Abstract

A process for making a low density polymer in a polymerization reactor system, the process comprising polymerizing an olefin monomer, and optionally an olefin comonomer, in the presence of a diluent in a polymerization reactor to make a polymerization product slurry consisting of a liquid phase and a solid phase, wherein the solid phase comprises an olefin polymer having a density of between about 0.905 g/cm 3 to about 0.945 g/cm 3 ; and discharging the polymerization product slurry from the polymerization reactor through a continuous take-off valve to make a mixture further comprising a vapor phase. The mixture comprises a pressure less than a bubble point pressure of a component in the polymerization product slurry.

1 - 20 . (canceled) 
     
     
         21 . A process for pressure management of a polymerization product comprising a liquid phase and a solid phase, the process comprising:
 reducing, at a location downstream of a polymerization reactor and upstream of a heater, a pressure of the polymerization product to less than a bubble point pressure of at least one component of the liquid phase.   
     
     
         22 . The process of  claim 21 , wherein at least a portion of the liquid phase vaporizes to yield a vaporized portion of the liquid phase. 
     
     
         23 . The process of  claim 21 , wherein the heater is upstream of a separation vessel. 
     
     
         24 . The process of  claim 21 , wherein the at least one component of the liquid phase comprises isobutane; ethylene; a comonomer comprising one or more of propylene, 1-butene, 1-hexene, and 1-octene; or combinations thereof. 
     
     
         25 . The process of  claim 21 , wherein the location is within or downstream of a continuous take-off valve and is upstream of the heater. 
     
     
         26 . The process of  claim 25 , wherein the continuous take-off valve has a nominal diameter of about 1 inch to about 8 inches. 
     
     
         27 . The process of  claim 25 , wherein the continuous take-off valve comprises more than one valve. 
     
     
         28 . A process for pressure management of a polymerization product comprising a liquid phase and a solid phase, the process comprising:
 reducing, using a continuous take-off valve of a polymerization system, a pressure of the polymerization product to less than a bubble point pressure of at least one component of the liquid phase.   
     
     
         29 . The process of  claim 28 , wherein at least a portion of the liquid phase vaporizes to yield a vaporized portion of the liquid phase. 
     
     
         30 . The process of  claim 28 , wherein the at least one component of the liquid phase comprises isobutane; ethylene; a comonomer comprising one or more of propylene, 1-butene, 1-hexene, and 1-octene; or combinations thereof. 
     
     
         31 . The process of  claim 28 , wherein the continuous take-off valve has a nominal diameter of about 1 inch to about 8 inches. 
     
     
         32 . The process of  claim 28 , wherein the continuous takeoff valve comprises more than one valve. 
     
     
         33 . The process of  claim 28 , wherein the continuous take-off valve is downstream of a polymerization reactor and upstream of a heater. 
     
     
         34 . A process for pressure management of a polymerization product comprising about 0.001% to about 4% ethane by total weight of a liquid phase of the polymerization product, the process comprising:
 reducing a pressure of the polymerization product to less than a bubble point pressure of at least one component of the liquid phase of the polymerization product such that at least a portion of the liquid phase vaporizes to yield vapor phase comprising a vaporized portion of the liquid phase and the ethane.   
     
     
         35 . The process of  claim 34 , wherein the step of reducing is performed at a location downstream of a polymerization reactor and upstream of a heater. 
     
     
         36 . The process of  claim 35 , wherein the heater is upstream of a separation vessel. 
     
     
         37 . The process of  claim 35 , wherein title location is within or downstream of a continuous take-off valve and is upstream of the heater. 
     
     
         38 . The process of  claim 37 , wherein the continuous tike-off valve has a nominal diameter of about 1 inch to about 8 inches. 
     
     
         39 . The process of  claim 37 , wherein the continuous take-off valve comprises more than one valve. 
     
     
         40 . The process of  claim 34 , wherein the at least one component of the liquid phase comprises isobutane; ethylene; a comonomer comprising one or more of propylene, 1-butene, 1-hexene and 1-octene; or combinations thereof.