Patent ID: 6085549
Filing Date: 2000-07-11
Classification: B01D,C01B,C10L,Y02C,Y10S

Abstract:
A process for separating carbon dioxide from a raw gas stream containing carbon dioxide, comprising:STEP 1 removing sulfur dioxide, oxides of nitrogen, particulate matter, and water from the gas stream by direct contact cooling, and passing the gas through heat exchanges and water knockouts;STEP 2 passing the resultant gas of step 1 through first and second membranes and recycling a nonpermeate gas stream from the second membrane into an inlet of the first membrane;STEP 3 treating the permeate gas stream from the second membrane by progressively deep cooling, pressurizing, cooling, deep cooling and passing said permeate gas stream through a water knockout;STEP 4 passing the treated permeate gas from the knockout progressively through first and second gas-gas heat exchanger, a condenser, and a distillation column;STEP 5 passing a first portion of the gas of step 4 through the distillation column in contact with and countercurrently to a stripping vapor gas passing upwardly through said column;STEP 6 progressively passing a second portion of the gas of step 5 through the second and then the first gas-gas heat exchanger, splitting the stream, passing one portion to the desiccant dryer for regeneration of the dryer;STEP 7 discharging and recovering a carbon dioxide stream from the distillation column; andSTEP 8 recovering vapors from the carbon dioxide stream of step 7 and recycling said vapors into at least one of the first and second membranes.