Carbon dioxide removal process

摘要

A process for efficiently removing carbon dioxide from a hydrocarbon containing feed stream utilizing a membrane separation unit in conjunction with a heat exchanger and a carbon dioxide separation unit wherein the streams obtained in the carbon dioxide separation unit are utilized to provide the cooling effect in the heat exchanger.

主权项

1. A process for recovering carbon dioxide from a pressurized hydrocarbon containing feed stream, the process comprising the steps of:
a) introducing a high pressure hydrocarbon containing feed stream that comprises at least methane and carbon dioxide into a first membrane separation unit at a temperature that is above the liquefaction temperature of carbon dioxide, the first membrane separation unit containing one or more membranes that are selective for carbon dioxide over the other components in the hydrocarbon containing feed stream, each membrane having a permeate side and a residue side and allowing for the passing of carbon dioxide to the permeate side to form a first membrane stream on the permeate side of the membrane and the substantial retention of the remaining components in the hydrocarbon containing feed stream to form a second membrane stream on the residue side of the membrane, the hydrocarbon containing feed containing at least 20% methane; b) withdrawing the second membrane stream for further use; c) compressing the first membrane stream; d) cooling the compressed first membrane stream using a multi-stream heat exchanger in order to form a compressed, cooled two phase first membrane stream; e) separating and purifying the compressed, cooled, two phase first membrane stream in a carbon dioxide separation unit to produce a carbon dioxide rich liquid stream and a carbon dioxide lean vapor stream; f) cooling the first membrane stream through heat exchange with the carbon dioxide rich liquid stream at the multi-stream heat exchanger, thereby producing a warmer carbon dioxide rich liquid stream; g) recovering the warmer carbon dioxide rich stream from the multi-stream heat exchanger as a high purity carbon dioxide product; and h) also cooling the first membrane stream through heat exchange with the Carbon dioxide lean vapor stream at the multi-stream heat exchanger.