Ethane recovery methods and configurations

摘要

Contemplated methods and configurations use a cooled ethane and CO2-containing feed gas that is expanded in a first turbo-expander and subsequently heat-exchanged to allow for relatively high expander inlet temperatures to a second turbo expander. Consequently, the relatively warm demethanizer feed from the second expander effectively removes CO2 from the ethane product and prevents carbon dioxide freezing in the demethanizer, while another portion of the heat-exchanged and expanded feed gas is further chilled and reduced in pressure to form a lean reflux for high ethane recovery.

主权项

1. A gas processing plant for processing a feed gas, comprising:
a feed gas source configured to provide a feed gas comprising at least 0.5 mol % CO2 and less than 3 mol % C3+ components; a first heat exchanger, a first turboexpander, and a second heat exchanger, coupled to each other in series upstream of a demethanizer and configured to cool and expand the feed gas to a pressure above a demethanizer operating pressure; a separator fluidly coupled to the second heat exchanger and configured to separate the cooled and expanded feed gas into a liquid phase and a vapor phase; a second turboexpander coupled to the separator and configured to expand a first portion of the vapor phase to the demethanizer pressure, and to deliver the expanded first portion to a top section of the demethanizer; wherein the first heat exchanger, the first turboexpander, and the second heat exchanger are configured such that the first portion of the vapor phase has a temperature suitable for stripping of CO2 from an ethane product in the demethanizer; a third heat exchanger and a pressure reduction device that are coupled to each other and configured to receive and condense a second portion of the vapor phase to thereby form a reflux to the demethanizer; a deethanizer configured to receive a bottom product of the demethanizer and a portion of a totally condensed deethanizer product as a reflux, and produce a deethanizer overhead product; a fourth heat exchanger configured to use the deethanizer overhead product or a demethanizer overhead product as a heat source to heat a side draw of the demethanizer to a temperature suitable to strip CO2 from the ethane product in the demethanizer; and a fifth heat exchanger configured to receive the deethanizer overhead product to provide cooling to the deethanizer overhead product, wherein the fourth heat exchanger or the fifth heat exchanger are configured to (i) receive the overhead deethanizer product and (ii) totally condense the deethanizer overhead product to thereby form the totally condensed deethanizer overhead product.