Shell/tube heat exchangers upstream of three-phase separator in gas-oil separation plant

Abstract

A gas-oil separation plant (GOSP) system includes a crude inlet line for flowing an inlet fluid stream to an upstream heat exchanger. The upstream heat exchanger includes an outer shell and a bundle of heating tubes therein defined between a lower tube height and an upper tube height. A first exchanger discharge is operable to discharge an oil component of the inlet fluid stream as a heated oil stream. At least one level controller is operable to control a flow a fluid into or out of the outer shell to maintain a lower level of the oil component in the outer shell at or below the first tube height and an upper level of the oil component at or above the second tube height. A separation vessel is fluidly coupled to the first exchanger discharge, and is operable to separate the heated oil stream into gas, oil and water components.

The invention claimed is: 
     
         1 . A gas-oil separation plant (GOSP) system, comprising:
 a crude inlet line extending from a source of an inlet fluid stream;   an upstream heat exchanger including an outer shell fluidly coupled to the crude inlet line and a bundle of tubes extending through the outer shell and fluidly coupled to a source of a heated fluid, the bundle of tubes defined between a lower tube height and an upper tube height defined above a lower end of the outer shell;   a first exchanger discharge extending above the lower end of the outer shell and operable to discharge an oil component of the inlet fluid stream from the upstream heat exchanger as a heated oil stream;   at least one level controller operable to control a flow of at least one of the inlet fluid stream into the outer shell or the heated oil stream from the outer shell to maintain a lower level of the oil component in the outer shell at or below the lower tube height and an upper level of the oil component at or above the upper tube height; and   a separation vessel fluidly coupled to the first exchanger discharge downstream of the upstream heat exchanger, the separation vessel operable to separate the heated oil stream into gas, oil and water components.   
     
     
         2 . The GOSP system of  claim 1 , further comprising a second exchanger discharge extending through the outer shell and operable discharge a water component of the of the inlet fluid stream from the upstream heat exchanger as a water stream. 
     
     
         3 . The GOSP system of  claim 2 , wherein each of the first and second exchanger discharges include a draw-off valve coupled therein, and wherein the draw-off valves in the first and second exchanger discharges are operatively coupled to the at least one level controller. 
     
     
         4 . The GOSP system of  claim 3 , further comprising one or more level control sensors communicably coupled to the at least one level controller and operable to detect the upper level and the lower level of the oil component, and wherein the at least one level controller is operable to adjust the draw-off valves in response to detection of the upper level below a predetermined upper threshold or detection of the lower level above a predetermined lower threshold. 
     
     
         5 . The GOSP system if  claim 1 , further comprising an oil line downstream of the separation vessel, the oil line extending to a de-salter and at least one of the group consisting of a degassing tank, a downstream heat exchanger, a dehydrator, and a stabilization column. 
     
     
         6 . The GOSP system of  claim 5 , further comprising an inlet conduit fluidly coupled to the bundle of tubes and wherein the inlet conduit is fluidly coupled to the oil line. 
     
     
         7 . The GOSP system of  claim 5 , further comprising a chemical injection line fluidly coupled to the oil line upstream of the de-salter and further comprising a wash water injection line extending into the de-salter. 
     
     
         8 . The GOSP system of  claim 1 , wherein the outer shell is elongated and defines a longitudinal direction, and wherein the tubes extend longitudinally within the outer shell. 
     
     
         9 . A method for operating a GOSP system, the method comprising:
 flowing an inlet fluid stream into an outer shell of an upstream heat exchanger;   passing a heated fluid through a bundle of tubes extending through the outer shell of the upstream heat exchanger to heat the inlet fluid stream and permit a water component of the inlet fluid stream to accumulate at a lower end of the outer shell and an oil component of the inlet fluid stream to accumulate on the water component;   discharging a heated oil stream of the oil component from the outer shell of the upstream heat exchanger through a first exchanger discharge;   adjusting a flow of at least one of the inlet fluid stream or the heated oil stream to maintain a lower level of the oil component in the outer shell at or below a lower tube height and an upper level of the oil component at or above an upper tube height; a pressure of the inlet fluid stream with an inlet pressure control valve coupled within the crude inlet line; and   flowing the heated oil stream to a separation vessel downstream of the upstream heat exchanger and separating the heated oil stream into gas, oil and water components within the separation vessel.   
     
     
         10 . The method of  claim 9 , further comprising discharging the water component of the of the inlet fluid stream from the upstream heat exchanger as a water stream through a second exchanger discharge. 
     
     
         11 . The method of  claim 10 , wherein adjusting the flow comprises adjusting a position of a draw-off valve coupled within the each of the first and second exchanger discharges. 
     
     
         12 . The method of  claim 11 , further comprising detecting the upper level and the lower level of the oil component with one or more level control sensors communicably coupled to a level controller. 
     
     
         13 . The method of  claim 12 , further comprising operating the level controller to adjust the position of the draw-off valves in response to detecting the upper level below a predetermined upper threshold or detecting the lower level above a predetermined lower threshold. 
     
     
         14 . The method of  claim 9 , further comprising flowing the heated oil stream from the separation vessel through a de-gassing tank, a dehydrator, a de-salter and a stabilization column. 
     
     
         15 . The method of  claim 14 , further comprising injecting a chemical stream into the heated oil stream upstream of the de-salter and injecting a wash water stream into the heated oil stream within the de-salter.