Methods and systems for improving performance of desalting units

Abstract

New methods and systems for crude oil desalting are provided that utilize hydrodynamic cavitation to crack molecules that have a tendency to form emulsions, thereby allowing increased desalter throughput, reduced desalter operating temperatures, and/or reduced or eliminated need for diluent oil or emulsifier.

What is claimed is: 
     
         1 . A method for improving the performance of a desalting unit comprising:
 subjecting a feed oil stream to hydrodynamic cavitation to produce a cavitated oil stream, and thereafter   desalting the cavitated oil stream to remove at least a portion of salt contained in the cavitated oil stream.   
     
     
         2 . The method of  claim 1 , wherein at least a portion of hydrocarbon molecules in the feed oil stream are cracked to lower molecular weight hydrocarbons when subjected to hydrodynamic cavitation. 
     
     
         3 . The method of  claim 1 , wherein the feed oil stream comprises an asphaltene content of greater than 5 wt %. 
     
     
         4 . The method of  claim 1 , wherein the feed oil stream comprises a resin content of greater than 5 wt %. 
     
     
         5 . The method of  claim 1 , where the cavitated oil stream is desalted at a temperature between 200° F. and 325° F. 
     
     
         6 . The method of  claim 1 , wherein the feed oil stream has an API gravity of 20° or less. 
     
     
         7 . The method of  claim 3 , wherein at least a portion of the asphaltene molecules are cracked to lower molecular weight hydrocarbons when the feed oil stream is subjected to hydrodynamic cavitation. 
     
     
         8 . The method of  claim 1 , further comprising mixing the cavitated oil stream with a wash water stream prior to desalting the cavitated oil stream. 
     
     
         9 . The method of  claim 1 , further comprising mixing the feed oil stream with a wash water stream prior to subjecting the feed oil stream to hydrodynamic cavitation. 
     
     
         10 . The method of  claim 1 , further comprising heating the feed oil stream prior to subjecting the feed oil stream to hydrodynamic cavitation. 
     
     
         11 . The method of  claim 1 , wherein the feed oil stream is subjected to hydrodynamic cavitation in the absence of a catalyst. 
     
     
         12 . The method of  claim 1 , wherein the feed oil stream is subjected to hydrodynamic cavitation in the absence of a diluent. 
     
     
         13 . The method of  claim 1 , wherein the feed oil stream is subjected to hydrodynamic cavitation in the absence of a hydrogen containing gas or with a hydrogen containing gas content of less than 50 standard cubic feet per barrel. 
     
     
         14 . The method of  claim 1 , wherein the feed oil stream is hydrodynamically cavitated at a temperature between 200 and 325° F. 
     
     
         15 . The method of  claim 1 , wherein the feed oil stream is hydrodynamically cavitated at a pressure drop greater than 400 psig. 
     
     
         16 . The method of  claim 15 , wherein the pressure drop is greater than 1000 psig. 
     
     
         17 . The method of  claim 16 , wherein the pressure drop is greater than 2000 psig. 
     
     
         18 . The method of  claim 1 , further comprising adding a solvent or an oil having an API gravity of greater than 30° to the feed oil stream prior to subjecting the feed oil stream to hydrodynamic cavitation. 
     
     
         19 . A system for desalting a feed oil comprising:
 a feed oil stream containing salt;   a hydrodynamic cavitation unit receiving the feed oil stream and adapted to subject the feed oil stream to hydrodynamic cavitation and thereby produce a cavitated feed oil stream; and   a desalting unit downstream of the hydrodynamic cavitation unit, the desalting unit adapted to remove at least a portion of the salt from the cavitated feed oil stream.