Methods for removing water from liquid recovrery systems

Abstract

Methods for removing water from liquid recovery systems may comprise introducing a dry sweet gas into a first chilldown train to produce a first intermediate stream; introducing the first intermediate stream and a dry regeneration gas into a dehydrator to produce a second intermediate stream; introducing the second intermediate stream into a second chilldown train to produce a third intermediate stream; introducing the third intermediate stream into a third chilldown train to produce a first recycle stream; introducing the first recycle stream into the second chilldown train and withdrawing from the second chilldown train to produce a second recycle stream; and introducing the second recycle stream into the first chilldown train withdrawing a wet sweet gas from the first chilldown train, wherein the wet sweet gas has a water concentration higher than in the dry sweet gas introduced to the first chilldown train.

The invention claimed is: 
     
         1 . A method comprising:
 introducing a dry sweet gas into a first chilldown train to produce a first intermediate stream;   introducing the first intermediate stream and a dry regeneration gas into a dehydrator to produce a second intermediate stream;   introducing the second intermediate stream into a second chilldown train to produce a third intermediate stream;   introducing the third intermediate stream into a third chilldown train to produce a first recycle stream;   introducing the first recycle stream into the second chilldown train and withdrawing from the second chilldown train to produce a second recycle stream; and   introducing the second recycle stream into the first chilldown train withdrawing a wet sweet gas from the first chilldown train, wherein the wet sweet gas has a water concentration higher than in the dry sweet gas introduced to the first chilldown train.   
     
     
         2 . The method of  claim 1 , wherein the dry sweet gas has a water concentration of about 0.1 ppm or less. 
     
     
         3 . The method of  claim 1 , wherein the dry sweet gas has a hydrogen sulfide concentration of about 16 ppm or less. 
     
     
         4 . The method of  claim 1 , wherein the dry sweet gas has a carbon dioxide concentration of about 300 ppm or less. 
     
     
         5 . The method of  claim 1 , wherein the dry sweet gas comprises methane, ethane, propane, butanes, nitrogen, or any combination thereof. 
     
     
         6 . The method of  claim 1 , wherein the wet sweet gas has a water concentration of about 150 ppm or more. 
     
     
         7 . The method of  claim 1 , wherein the dry regeneration gas has a water concentration of about 0.1 ppm or less. 
     
     
         8 . The method of  claim 1 , wherein the dry regeneration gas comprises methane, nitrogen, air, or any combination thereof. 
     
     
         9 . The method of  claim 1 , wherein the method occurs over a time period of about 5 days to about 7 days. 
     
     
         10 . The method of  claim 9 , wherein the wet sweet gas has a dew point temperature of about −30° F. to about −50° F. after the time period. 
     
     
         11 . The method of  claim 1 , wherein the first chilldown train comprises a distillation tower, a heat exchanger, a refrigeration unit, an expander, a letdown valve, or any combination thereof. 
     
     
         12 . The method of  claim 1 , wherein the dehydrator comprises a molecular sieve, a glycol dehydration unit, a passive dehydration system, or any combination thereof. 
     
     
         13 . The method of  claim 1 , wherein the second chilldown train comprises a distillation tower, a heat exchanger, a refrigeration unit, an expander, a letdown valve, or any combination thereof. 
     
     
         14 . The method of  claim 1 , wherein the third chilldown train comprises a distillation tower, a heat exchanger, a refrigeration unit, an expander, a letdown valve, or any combination thereof. 
     
     
         15 . A method comprising:
 introducing a dry sweet gas into a first chilldown train to produce a first intermediate stream;
 wherein the dry sweet gas has a water concentration of about 0.1 ppm or less, a hydrogen sulfide concentration of about 16 ppm or less, and a carbon dioxide concentration of about 300 ppm or less; 
   introducing the first intermediate stream into a molecular sieve;   introducing a dry regeneration gas into the molecular sieve;
 wherein the dry regeneration gas comprises methane, nitrogen, air, or any combination thereof; 
   producing a second intermediate stream from the molecular sieve;   introducing the second intermediate stream into a second chilldown train to produce a third intermediate stream;   introducing the third intermediate stream into a third chilldown train to produce a first recycle stream;   introducing the first recycle stream into the second chilldown train;   producing a second recycle stream from the second chilldown train;   introducing the second recycle stream into the first chilldown train; and   producing a wet sweet gas having a water concentration of about 150 ppm or more and a dew point temperature of about −30° F. to about −50° F. after about 5 days to about 7 days from the first chilldown train.