Gas dehydrator and method of using same
Systems and methods presented herein generally relate to recycling, or reducing flaring or venting, of vent gases from glycol based dehydration of natural gas. Some systems and methods use high pressure gas, high pressure glycol, or pump-assisted high pressure glycol to provide motive energy to draw reflux gas and/or skimmer gas through one or more venturis and back to the contact tower of the dehydration system. Some systems and methods provide for harvesting energy from the dehydration process.
1 . A system, comprising:
a contact tower having an inlet;
a reflux column configured to receive a rich glycol stream from the contact tower, wherein the reflux column is configured to generate a reflux gas stream;
a flash separator configured to receive at least a portion of the reflux gas stream, wherein the flash separator is configured to generate a flash gas stream, and at least a portion of the flash gas stream is diverted back to the inlet of the contact tower;
a first venturi pump configured to compress the reflux gas stream from near atmospheric pressure to a pressure at or near a pressure of the flash separator; and
a second venturi pump configured to compress the reflux gas stream and the flash gas stream to a pressure at or near a pressure of the contact tower, wherein the first venturi pump comprising a first venturi and the second venturi pump comprising a second venturi, wherein in use, at least one of the reflux gas stream or the flash gas stream is drawn through one or more venturis comprising the first venturi and/or the second venturi to the contact tower.
2 . The system of claim 1 , wherein the reflux gas stream comprises benzene, toluene, ethylbenzene, or xylene.
3 . The system of claim 1 , comprising a heat exchanger configured to receive the reflux gas stream from the reflux column, wherein the heat exchanger is configured to cool the reflux gas stream to generate a non-condensable gas stream.
4 . The system of claim 3 , comprising a separator configured to receive the non-condensable gas stream from the heat exchanger, wherein the separator is configured to separate liquid water from the non-condensable gas stream.
5 . A glycol based dehydration system, comprising
a contact tower, wherein in use, wet gas enters the contact tower and is dehydrated by glycol flowing through the contact tower, and a water-rich glycol stream exits the contact tower;
a reflux column configured to filter and heat the water-rich glycol stream, wherein the reflux column is configured to generate a reflux gas stream from the water-rich glycol stream;
a flash separator configured to receive at least a portion of the reflux gas stream from the reflux column, wherein the flash separator is configured to generate a flash gas stream;
a high pressure venturi pump comprising a first venturi of one or more venturis; and
a low pressure venturi pump comprising a second venturi of the one or more venturis wherein in use, at least one of the reflux gas stream or the flash gas stream is drawn through the one or more venturis to the contact tower, wherein the low pressure venturi pump is configured to compress the reflux gas stream from near atmospheric pressure to a pressure at or near a pressure of the flash separator, and the high pressure venturi pump is configured to compress the reflux gas stream and the flash gas stream to a pressure at or near a pressure of the contact tower.
6 . The system of claim 5 , wherein the one or more venturis comprises a cascaded arrangement of three venturis.
7 . The system of claim 5 , wherein in use, at least one of the reflux gas stream or the flash gas stream is routed to the one or more venturis as a pressure control to avoid excessively low pressure on the reflux column.
8 . The system of claim 5 , wherein the high pressure venturi pump and the low pressure venturi pump each comprise a booster pump.
9 . The system of claim 5 , wherein a recycled glycol stream pumped from a bottom of the contact tower is configured to be used as motive fluid for the high pressure venturi pump.
10 . The system of claim 5 , comprising a heat exchanger configured to receive the reflux gas stream from the reflux column, wherein the heat exchanger is configured to cool the reflux gas stream to generate a non-condensable gas stream.
11 . The system of claim 10 , comprising a separator configured to receive the non-condensable gas stream from the heat exchanger, wherein the separator is configured to separate liquid water from the non-condensable gas stream.
12 . A method for glycol based dehydration, comprising:
dehydrating a wet gas in a contact tower via a glycol flowing through the contact tower, and outputting a water-rich glycol stream from the contact tower;
filtering and heating the water-rich glycol stream via a reflux column, and generating a reflux gas stream from the water-rich glycol stream via the reflux column;
receiving at least a portion of the reflux gas stream from the reflux column via a flash separator, and generating a flash gas stream via the flash separator;
drawing in at least one of the reflux gas stream or the flash gas stream through one or more venturis to the contact tower, wherein the one or more venturis comprise a first venturi of a first venturi pump and a second venturi of a second venturi pump;
compressing, via the second venturi pump, the reflux gas stream from near atmospheric pressure to a pressure at or near a pressure of the flash separator; and
compressing, via the first venturi pump, the reflux gas stream and the flash gas stream to a pressure at or near a pressure of the contact tower.
13 . The method of claim 12 , comprising receiving the reflux gas stream from the reflux column into a heat exchanger, and cooling the reflux gas stream in the heat exchanger to generate a non-condensable gas stream.
14 . The method of claim 13 , comprising receiving the non-condensable gas stream from the heat exchanger into a separator, and separating liquid water from the non-condensable gas stream via the separator.
15 . A glycol based dehydration system, comprising:
a contact tower, wherein in use, wet gas enters the contact tower and is dehydrated by glycol flowing through the contact tower, and a water-rich glycol stream exits the contact tower;
a reflux column configured to filter and heat the water-rich glycol stream, wherein the reflux column is configured to generate a reflux gas stream from the water-rich glycol stream;
a flash separator configured to receive at least a portion of the reflux gas stream from the reflux column, wherein the flash separator is configured to generate a flash gas stream;
a first venturi pump comprising a first venturi of one or more venturis and a second venturi pump comprising a second venturi of the one or more venturis, wherein in use, at least one of the reflux gas stream or the flash gas stream is drawn through the one or more venturis to the contact tower, wherein the second venturi pump is configured to compress the reflux gas stream from near atmospheric pressure to a pressure at or near a pressure of the flash separator, and the first venturi pump is configured to compress the reflux gas stream and the flash gas stream to a pressure at or near a pressure of the contact tower; and
system controls configured to improve gas recovery, achieve steady state operation, and/or avoid undesirable operating modes.
16 . The system of claim 15 , wherein the system controls comprises a processor.
17 . The system of claim 15 , comprising:
a heat exchanger configured to receive the reflux gas stream from the reflux column, wherein the heat exchanger is configured to cool the reflux gas stream to generate a non-condensable gas stream; and
a separator configured to receive the non-condensable gas stream from the heat exchanger, wherein the separator is configured to separate liquid water from the non-condensable gas stream.