Mcdermott International, Inc.

George J Montgomery, Iv

Hafez K Aghili

A method of recycling a portion of the overhead vapor stream to enhance ethane recovery from a demethanizer. After the overhead vapor stream is discharged from the demethanizer, a portion of it, reflux, is compressed in a cyrogenic compressor to a pressure greater than that of the demethanizer. Afterwards the pressurized reflux is chilled in a heat exchanger causing at least a portion of it, and preferably all of it, to condense to a liquid. The pressure of this condensed reflux is then equalized to that of the demethanizer across a recycle valve so that a liquid reflux can be fed back to the top of the demethanizer. This recycling of a liquid reflux enhances ethane recovery as a column bottoms product from the demethanizer.

Ethane recovery system

A method for extracting natural gas liquids from a gas stream that has a high content of hydrogen and carbon dioxide is shown. This gas stream is scrubbed, dehydrated, filtered compressed and chilled prior to entering a demethanizer where the overhead residue gas consisting of hydrogen, nitrogen and methane are separated from the demethanizer bottoms product. Ths bottoms product is then warmed prior to entering a de-ethanizer where ethane, ethylene, and carbon dioxide are separated from the de-ethanizer bottoms product which consists of the heavier compounds of propylene, propane, butane, pentane and the like. The cold demethanizer residue gas is used to cool the incoming inlet gas stream via an inlet gas cooler, and expanded vapor from a high pressure separator is cross exchanged with the de-ethanizer overhead product stream.

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Houston, TX, United States of America

George J Montgomery, Iv