Patent ID: 6658893
Filing Date: 2003-12-09
Classification: F25J

Abstract:
A process for recovery of liquefied petroleum gas from a feed stream, the process comprising:passing said feed stream through an indirect heat exchanger; separating said feed stream into a first vapor fraction and a first liquid fraction; transferring said first liquid fraction to said indirect heat exchanger; transferring said first vapor fraction to a direct heat exchanger absorber column; transferring said first liquid fraction to a distilling unit; distilling said first liquid fraction in said distilling unit to yield a second vapor fraction and a second liquid fraction; cooling said second vapor fraction in said indirect heat exchanger; separating said second vapor fraction into a third vapor fraction and a third liquid fraction; returning substantially all of said third liquid fraction to said distilling unit; passing said third vapor fraction through the indirect heat exchanger, at least a portion of said third vapor fraction condensing to a liquid phase; decreasing pressure of said third vapor fraction such that at least a portion of said liquid phase flashes; transferring said third vapor fraction to said direct heat exchanger absorber column such that said third vapor fraction mixes with said first vapor fraction, yielding a fourth vapor fraction and a fourth liquid fraction; transferring said fourth liquid fraction to said indirect heat exchanger; transferring said fourth liquid fraction to said distilling unit to distill said fourth liquid fraction; and transferring said fourth vapor fraction to said indirect heat exchanger, such that, the feed stream exchanges heat with the first liquid fraction, the fourth vapor fraction and the fourth liquid fraction, all four streams being in parallel, and the third vapor fraction exchanges heat with the fourth vapor fraction and the fourth liquid fraction, all three streams being in parallel, and the second vapor fraction exchanges heat with the fourth vapor fraction and the fourth liquid fraction, all three streams being in parallel, wherein heat is exchanged between the feed stream and the fourth liquid fraction, after the fourth liquid fraction has exchanged with the third vapor fraction, and then with the second vapor fraction.