Separating Oil and Water Streams

Abstract

Embodiments described herein provide a system and methods for separating oil and water streams. The method includes separating a fluid stream into an oil continuous stream and a water continuous stream using a cyclonic separator, flowing the oil continuous stream to a first gravity separation vessel, and flowing the water continuous stream to a second gravity separation vessel. The method also includes separating the oil continuous stream in the first gravity separation vessel into an oil stream and a water stream and separating the water continuous stream in the second gravity separation vessel into an oil stream and a water stream.

1 . A method for separating oil and water streams, comprising:
 separating a fluid stream into an oil continuous stream and a water continuous stream using a cyclonic separator;   flowing the oil continuous stream to a first gravity separation vessel;   flowing the water continuous stream to a second gravity separation vessel;   separating the oil continuous stream in the first gravity separation vessel into a first oil stream and a first water stream; and   separating the water continuous stream in the second gravity separation vessel into a second oil stream and a second water stream.   
     
     
         2 . The method of  claim 1 , further comprising:
 combining the first oil stream and the second oil stream into a single oil stream; and   combining the first water stream and the second water stream into a single water stream.   
     
     
         3 . The method of  claim 1 , comprising using a swirl element within the cyclonic separator to impart radial acceleration to the fluid stream. 
     
     
         4 . The method of  claim 2 , comprising controlling a radial acceleration to avoid forming an emulsion. 
     
     
         5 . The method of  claim 4 , comprising controlling the radial acceleration using a plurality of swirl vanes arranged in parallel or in series on the swirl element. 
     
     
         6 . The method of  claim 3 , comprising generating the radial acceleration within the fluid stream with a total pressure drop of less than about 1 bar. 
     
     
         7 . The method of  claim 1 , comprising using a vortex finder within the cyclonic separator to remove the oil continuous stream. 
     
     
         8 . The method of  claim 1 , comprising using an electrostatic coalescer upstream of the cyclonic separator to create larger water droplets. 
     
     
         9 . The method of  claim 1 , comprising using an electrostatic coalescer downstream of the cyclonic separator and upstream of the first gravity separation vessel. 
     
     
         10 . The method of  claim 8 , comprising automatically shutting off the electrostatic coalescer if the fluid stream approaches a water continuous phase. 
     
     
         11 . The method of  claim 1 , comprising using an additional cyclonic separator downstream of the first gravity separation vessel or the second gravity separation vessel, or both, for further separation of oil from water. 
     
     
         12 . A system for separating oil and water streams, comprising:
 a cyclonic separator configured to separate a fluid stream into an oil continuous stream and a water continuous stream;   a first gravity separation vessel configured to separate the water continuous stream into a first oil stream and a first water stream; and   a second gravity separation vessel configured to separate the oil continuous stream into a second oil stream and a second water stream.   
     
     
         13 . The system of  claim 12 , comprising an electrostatic coalescer upstream of the cyclonic separator. 
     
     
         14 . The system of  claim 12 , comprising an electrostatic coalescer on the oil continuous stream. 
     
     
         15 . The system of  claim 12 , wherein a swirl element within the cyclonic separator comprises a plurality of swirl vanes arranged parallel or in series. 
     
     
         16 . The system of  claim 12 , comprising an antiswirl device for straightening a flow path of the water continuous stream or the oil continuous stream, or both, downstream of the cyclonic separator. 
     
     
         17 . A method for separating two immiscible phases from a fluid stream, comprising:
 sending the fluid stream into a cyclonic separator;   generating radial acceleration within the cyclonic separator using a swirl element;   controlling the radial acceleration at a value at which the two immiscible phases separate into two continuous phases;   removing the two continuous phases from the cyclonic separator into two lines using a vortex finder; and   sending the two continuous phases to two separate downstream vessels for further separation of the two immiscible phases.   
     
     
         18 . The method of  claim 17 , comprising controlling the radial acceleration of the fluid stream by selecting an angular orientation of at least one swirl vane on the swirl element. 
     
     
         19 . The method of  claim 17 , comprising decreasing the tangential velocity component of the fluid stream perpendicular to a flow path using an antiswirl device downstream of a point at which the radial acceleration was generated. 
     
     
         20 . The method of  claim 17 , comprising controlling the swirling of the fluid stream to maintain the radial acceleration at a value at which shearing of the two immiscible phases does not cause an emulsion to form.