Divalent cation removal from rich monoethylene glycol (meg) feed streams by ion exchange

Abstract

A system and process for removing divalent cations from a rich MEG feed stream is presented. An ion exchange bed containing a cation exchange resin adsorbs the divalent cations in the rich MEG feed stream as it flows through the ion exchange bed. After the divalent ions have been removed, the feed stream flows through a flash separator and a distillation column to reclaim MEG. Alternatively, the feed stream flows through a distillation column to regenerate MEG. The spent cation exchange resin may be regenerated in place using a regeneration brine comprised of sodium chloride and water. After use, the regeneration brine may be disposed as waste or recycled to the brine storage tank and re-used to regenerate the cation exchange resin.

We claim: 
     
         1 . A process for removing divalent cations from a feed stream containing water and monoethylene glycol (MEG), the process comprising:
 passing the feed stream through an ion exchange bed containing a cation exchange resin, wherein the divalent cations are adsorbed by the cation exchange resin to form an effluent stream; and   passing the effluent stream from the ion exchange bed through a distillation column to yield MEG and distilled water.   
     
     
         2 . The process of  claim 1 , further comprising regenerating the cation exchange resin by passing a regeneration brine through the cation exchange resin. 
     
     
         3 . The process of  claim 2 , wherein the regeneration brine comprises water from the distillation column. 
     
     
         4 . The process of  claim 3 , wherein the regeneration brine is stored in a brine storage tank. 
     
     
         5 . The process of  claim 4 , wherein the feed stream is passed through the ion exchange bed in a first direction, and the regeneration brine is routed from the brine storage tank to the ion exchange bed in a second direction opposite from the first direction. 
     
     
         6 . The process of  claim 5 , wherein the regeneration brine is formed by mixing sodium chloride from an external source with the water from the distillation column. 
     
     
         7 . The process of  claim 6 , wherein the regeneration brine is re-used to regenerate the ion exchange bed. 
     
     
         8 . A process for removing divalent cations from a feed stream containing water and monoethylene glycol (MEG), the process comprising:
 passing the feed stream in a first direction through an ion exchange bed containing a cation exchange resin, wherein the divalent cations are adsorbed by the cation exchange resin to form an effluent stream;   passing the effluent stream from the ion exchange bed through a distillation column to yield MEG and distilled water; and   regenerating the cation exchange resin by passing a regeneration brine through the ion exchange bed in a second direction opposite from the first direction.   
     
     
         9 . The process of  claim 8 , wherein the regeneration brine is formed in a regeneration brine tank by mixing sodium chloride from an external source with water from the distillation column. 
     
     
         10 . The process of  claim 8 , wherein the regeneration brine is sourced from a regeneration brine tank and is re-used. 
     
     
         11 . The process of  claim 8 , wherein the regeneration brine comprises sodium chloride sourced from MEG reclamation and water from the distillation column. 
     
     
         12 . The process of  claim 8 , wherein the regenerating forms a waste stream containing only salts originally present in the feed stream. 
     
     
         13 . The process of  claim 12 , wherein the regeneration brine is formed using water obtained from the distillation column. 
     
     
         14 . The process of  claim 12 , wherein the waste stream is used as a regeneration brine. 
     
     
         15 . The process of  claim 8 , wherein vaporized water from the distillation column is cooled and routed to a regeneration brine tank, and sodium chloride is added to the regeneration brine tank to form the regeneration brine. 
     
     
         16 . The process of  claim 15 , wherein the sodium chloride is obtained from an external source. 
     
     
         17 . The process of  claim 15 , wherein the sodium chloride is obtained from a waste stream of the regeneration operation. 
     
     
         18 . A process for removing divalent cations from a feed stream containing water and monoethylene glycol (MEG), the process comprising:
 passing the feed stream in a first direction through an ion exchange bed containing a cation exchange resin, wherein the divalent cations are adsorbed by the cation exchange resin to form an effluent stream;   passing the effluent stream from the ion exchange bed through a distillation column to yield MEG and distilled water; and   regenerating the cation exchange resin by passing a regeneration brine, formed using water from the distillation column, from a regeneration brine tank through the ion exchange bed in a second direction opposite from the first direction.   
     
     
         19 . The process of  claim 18 , wherein sodium chloride obtained as a waste stream from the regeneration process is added to the regeneration brine tank to make the regeneration brine. 
     
     
         20 . The process of  claim 19 , wherein sodium chloride from an external source is also added to the regeneration brine tank to make the regeneration brine.