Subsea heat exchanger

Abstract

Subsea convection heat exchanger ( 1 ) for cooling or heating a hydrocarbon-containing fluid in subsea environment. The heat exchanger ( 1 ) comprises a convection section with a fluid carrying pipe ( 7 ) adapted for heat transfer between the carried fluid on one side of the pipe wall and the surrounding water on the opposite side of the pipe wall. The convection section is enclosed by an enclosure ( 9 ) with sea water inlet ( 11 ) and a sea water outlet ( 13 ). The heat exchanger ( 1 ) is furthermore provided with means ( 15 ) for controlled through-flow of surrounding sea water from the sea water inlet ( 11 ) to the sea water outlet ( 13 ).

1 . A subsea convection heat exchanger for cooling or heating a hydrocarbon-containing fluid in a subsea environment, said heat exchanger comprising:
 a convection section comprising a fluid carrying pipe for heat transfer between carried fluid on one side of a pipe wall and surrounding water on an opposite side of the pipe wall;   wherein said convection section is enclosed by an enclosure comprising a sea water inlet and a sea water outlet; and   wherein the subsea convection heat exchanger comprises a pump for controlled through-flow of surrounding sea water from the sea water inlet to the sea water outlet.   
     
     
         2 . A subsea convection heat exchanger according to  claim 1 , wherein the subsea convection heat exchanger is hydrostatically balanced as there is fluid connection between an exterior and interior of the enclosure through at least one of said sea water inlet and said sea water outlet. 
     
     
         3 . (canceled) 
     
     
         4 . A subsea convection heat exchanger according to  claim 1 , wherein said pump is arranged in connection with the sea water outlet of the enclosure creating a pressure drop from the exterior of the enclosure to the interior of the enclosure. 
     
     
         5 . A subsea convection heat exchanger according to  claim 4 , wherein:
 said pump is arranged in a pump unit with a pump motor arranged in a motor chamber which is isolated from the surroundings and adapted to be hydrostatically balanced with surrounding sea water;   wherein the pump motor is adapted to operate the pump via a shaft running through a mechanical seat; and   wherein the arrangement of the pump unit creates a pressure drop over said mechanical seal from the motor chamber to the pump when the pump is running, as the pump is adapted to create a pressure drop from its outlet to its inlet.   
     
     
         6 . A subsea convection heat exchanger according to  claim 1 , wherein:
 the subsea convection heat exchanger exhibits a fluid inlet and a fluid outlet for the fluid to be cooled or heated; and   wherein said pump for through-flow of water is controlled by a controller, wherein the controller is at least partially controlled on a basis of a temperature of the fluid flowing in at least one of the fluid outlet and the fluid inlet, as measured by temperature sensor(s).