| abstract |
A process and apparatus are provided for recovering diluent, unreacted monomer, and unreacted comonomer from a polymerization reactor effluent. The comonomer has a boiling point higher than the boiling point of the monomer and the diluent has a boiling point between the boiling points of the monomer and comonomer. The process and apparatus employ at least one flash tank, a first fractionation stage including a first column and operating at a first fractionation pressure, and a second fraction stage including a second column and operating at a higher second fractionation pressure. Comonomer is withdrawn from the first column as a fractionation product, and overhead vapor containing diluent and monomer is substantially condensed to yield a substantially condensed overhead stream. Liquid and vapor from the stream are separated in an accumulator. Vapor and liquid from the accumulator are compressed and pumped, respectively, for delivery to the second fractionation stage at approximately the second fractionation pressure. The pumped liquid is a major portion by weight of the total flow of pumped liquid and compressed vapor to the second fractionation stage. Diluent and monomer are withdrawn from the second column as fractionation products. |