Use of Solvent to Decrease Caustic Scrubber Fouling

Abstract

A method of reducing the formation of fouling deposits occurring in a caustic scrubber used to remove acid gases can include providing a caustic scrubber fed with an alkaline aqueous solution including essentially one or more of NaOH, KOH or LiOH. The method can include providing an olefin-containing hydrocarbon stream that is contaminated with oxygenated compounds and acid gases. The oxygenated compounds can be capable of making polymeric fouling deposits in the presence of the alkaline solution of the scrubber. The method can include sending the hydrocarbon stream to the caustic scrubber to recover an olefin-containing hydrocarbon stream that is essentially free of acid gases. An efficient amount of a solvent capable of reducing the formation of fouling deposits can be introduced in the caustic scrubber and/or in the alkaline solution fed to the scrubber. The solvent can be separated from the alkaline solution.

What is claimed: 
     
         1 - 14 . (canceled) 
     
     
         15 . A method of reducing the formation of fouling deposits occurring in a caustic scrubber used to remove acid gases comprising:
 a) providing a caustic scrubber fed with an alkaline aqueous solution comprising NaOH, KOH, LiOH, or combinations thereof;   b) providing an olefin-containing hydrocarbon stream contaminated with oxygenated compounds and acid gases, wherein the oxygenated compounds are capable of making polymeric fouling deposits in the presence of the alkaline aqueous solution;   c) sending the olefin-containing hydrocarbon stream to the caustic scrubber to recover an olefin-containing hydrocarbon stream essentially free of acid gases;   d) wherein an efficient amount of a solvent capable reducing the formation of fouling deposits is introduced in the caustic scrubber, in the alkaline aqueous solution fed to the caustic scrubber, or combinations thereof;   e) wherein a liquid outlet of the caustic scrubber is sent to means to separate the solvent from the alkaline aqueous solution; and   f) optionally, wherein an additive is introduced in the caustic scrubber, the alkaline aqueous solution, or combinations thereof, wherein the additive is capable of reducing the conversion of the oxygenated compounds to polymeric fouling deposits in the presence of the alkaline aqueous solution.   
     
     
         16 . The method of  claim 15 , wherein the solvent is only introduced in the caustic scrubber. 
     
     
         17 . The method of  claim 15 , wherein the solvent is only introduced in the alkaline aqueous solution fed to the caustic scrubber. 
     
     
         18 . The method of  claim 15 , wherein the solvent is introduced in the caustic scrubber and in the alkaline aqueous solution fed to the caustic scrubber. 
     
     
         19 . The method of  claim 15 , wherein the solvent is essentially immiscible with the alkaline aqueous solution. 
     
     
         20 . The method of  claim 15 , wherein the solvent is a hydrocarbon. 
     
     
         21 . The method of  claim 15 , wherein the solvent is an aromatic. 
     
     
         22 . The method of  claim 15 , wherein the solvent is benzene, toluene, or xylene. 
     
     
         23 . The method of  claim 15 , wherein a weight ratio of the solvent to the flow of the alkaline aqueous solution is up to 0.1. 
     
     
         24 . The method of  claim 15 , wherein a weight ratio of the solvent to the flow of the alkaline aqueous solution ranges from 0.02 to 0.1. 
     
     
         25 . The method of  claim 15 , wherein the solvent separated from the alkaline aqueous solution at step e) is treated to eliminate heavies and recycled at step d). 
     
     
         26 . The method of  claim 15 , wherein the means of step e) to separate the solvent from the alkaline aqueous solution are located in a bottom of the caustic scrubber. 
     
     
         27 . The method of  claim 15 , wherein the oxygenated compounds are carbonyl enolizable components. 
     
     
         28 . The method of  claim 15 , wherein a proportion of the oxygenated compounds in the olefin-containing hydrocarbon stream is up to 15000 wppm. 
     
     
         29 . The method of  claim 15 , wherein a proportion of acid gases in the olefin-containing hydrocarbon stream is up to 1%. 
     
     
         30 . The method of  claim 15 , wherein the olefin-containing hydrocarbon stream leaving the caustic scrubber is fed to a scrubber fed with water to remove any alkaline content of said olefin-containing hydrocarbon stream. 
     
     
         31 . A method of reducing the formation of fouling deposits occurring in a caustic scrubber used to remove acid gases comprising:
 a) providing a caustic scrubber fed with an alkaline aqueous solution comprising NaOH, KOH, LiOH, or combinations thereof;   b) providing an olefin-containing hydrocarbon stream contaminated with oxygenated compounds and acid gases, wherein the oxygenated compounds are capable of making polymeric fouling deposits in the presence of the alkaline aqueous solution;   c) sending the olefin-containing hydrocarbon stream to the caustic scrubber to recover an olefin-containing hydrocarbon stream essentially free of acid gases;   d) wherein an efficient amount of a solvent capable reducing the formation of fouling deposits is introduced in the caustic scrubber, in the alkaline aqueous solution fed to the caustic scrubber, or combinations thereof, wherein a weight ratio of the solvent to the flow of the alkaline aqueous solution is up to 0.1, and wherein the solvent is essentially immiscible with the alkaline aqueous solution;   e) wherein a liquid outlet of the caustic scrubber is sent to means to separate the solvent from the alkaline aqueous solution; and   f) optionally, wherein an additive is introduced in the caustic scrubber, the alkaline aqueous solution, or combinations thereof, wherein the additive is capable of reducing the conversion of the oxygenated compounds to polymeric fouling deposits in the presence of the alkaline aqueous solution.   
     
     
         32 . The method of  claim 31 , wherein the solvent is a hydrocarbon. 
     
     
         33 . The method of  claim 31 , wherein the solvent is an aromatic. 
     
     
         34 . The method of  claim 31 , wherein the solvent is benzene, toluene, or xylene.