Divalent Ion Removal From Monoethylene Glycol-Water Streams

Abstract

A system and process for the removal of divalent ions from a MEG-water stream are presented. The system includes a chemical treatment tank that receives the MEG-water stream, means for precipitating the calcium, magnesium, and hydroxide ions that are contained in the MEG-water stream, means for discharging the MEG-water stream from the chemical treatment tank, and means for recycling the discharged MEG-water stream back to the chemical treatment tank or routing it to a solids removal system. The means for precipitating the calcium, magnesium, and sulfate ions may be employed simultaneously or sequentially.

1 - 20 . (canceled) 
     
     
         21 . A process comprising:
 routing a monoethylene glycol (MEG) water stream containing sulfate ions to a vessel;   adding barium chloride to the MEG-water stream; and   forming and precipitating barium sulfate in the MEG-water stream to form a treated MEG-water stream.   
     
     
         22 . The process of  claim 21 , further comprising adding a solution of sodium carbonate, a solution of sodium hydroxide, or both to the MEG-water stream to precipitate calcium, magnesium or both. 
     
     
         23 . The process of  claim 21 , further comprising discharging the treated MEG-water stream from the vessel, recycling a first portion of the treated MEG-water stream to the vessel, and routing a second portion of the treated MEG-water stream to a solids removal system. 
     
     
         24 . The process of  claim 21 , further comprising routing the treated MEG-water stream to a solids removal system, separating barium sulfate solids in the solids removal system, and recycling the treated MEG-water stream to the vessel after it passes through the solids removal system. 
     
     
         25 . The process of  claim 21 , further comprising routing the treated MEG-water stream to a solids removal system and then to a filtrate tank. 
     
     
         26 . The process of  claim 22 , wherein the solution of sodium carbonate, the solution of sodium hydroxide, or both, and the barium chloride are added simultaneously. 
     
     
         27 . The process of  claim 22 , wherein the barium chloride and one or both of the solution of sodium carbonate and the solution of sodium hydroxide are all added sequentially. 
     
     
         28 . The process of  claim 26 , further comprising recycling the treated MEG-water stream to the vessel until the precipitation reactions are complete. 
     
     
         29 . The process of  claim 24 , further comprising adding a solution of sodium carbonate, a solution of sodium hydroxide, or both to the recycled MEG-water stream to precipitate calcium, magnesium or both. 
     
     
         30 . The process of  claim 29 , wherein a solution of sodium carbonate and a solution of sodium hydroxide are added sequentially to the recycled MEG-stream and resulting solids are separated by solids removal. 
     
     
         31 . A process comprising:
 performing a barium chloride treatment by adding barium chloride to a MEG-water stream containing sulfate ions; and   forming and precipitating barium sulfate in the MEG-water stream to form a treated MEG-water stream.   
     
     
         32 . The process of  claim 31 , further comprising adding a solution of sodium carbonate, a solution of sodium hydroxide, or both to the MEG-water stream to precipitate calcium, magnesium or both. 
     
     
         33 . The process of  claim 31 , further comprising removing solids from the treated MEG-water stream to form a solids-depleted stream and repeating the barium chloride treatment on the solids-depleted stream until all sulfate ions are removed. 
     
     
         34 . The process of  claim 31 , further comprising removing solids from the treated MEG-water stream to form a solids-depleted stream and adding a solution of sodium carbonate, a solution of sodium hydroxide, or both to the solids-depleted stream to precipitate calcium, magnesium or both. 
     
     
         35 . The process of  claim 32 , wherein the solution of sodium carbonate, the solution of sodium hydroxide, or both, and the barium chloride are added simultaneously. 
     
     
         36 . The process of  claim 32 , wherein the barium chloride and one or both of the solution of sodium carbonate and the solution of sodium hydroxide are all added sequentially. 
     
     
         37 . The process of  claim 31 , further comprising removing solids from the MEG-water stream to form a solids-depleted stream, and adding a solution of sodium carbonate, a solution of sodium hydroxide, or both to the solids-depleted stream to precipitate calcium, magnesium or both. 
     
     
         38 . The process of  claim 37 , wherein the solution of sodium carbonate and the solution of sodium hydroxide are both added, with solids removal between addition of the solution of sodium carbonate and addition of the solution of sodium hydroxide. 
     
     
         39 . A process comprising:
 routing a MEG-water stream to a vessel;   performing a barium chloride treatment by adding barium chloride to a MEG-water stream containing sulfate ions;   forming and precipitating barium sulfate in the MEG-water stream to form a treated MEG-water stream;   removing solids from the MEG-water stream to form a solids-depleted stream;   recycling the solids-depleted stream to the vessel; and   adding a solution of sodium carbonate, a solution of sodium hydroxide, or both to the solids-depleted stream to precipitate calcium, magnesium or both.   
     
     
         40 . The process of  claim 39 , wherein the solution of sodium carbonate and the solution of sodium hydroxide are both added, with solids removal between addition of the solution of sodium carbonate and addition of the solution of sodium hydroxide.