Heat transfer from a source to a fluid to be heated using a heat driven loop

Abstract

Oil in a storage tank is heated by providing one or more elongate conduits within the storage tank in the form of a loop extending from an inlet manifold across the tank and returning to an outlet manifold. The inlet manifold is connected to an evaporator section at a heat source and the outlet manifold acts as a return of the condensate. The conduit forms a loop and back flow in the loop is prevented by providing a head in the liquid in the conduit at a position adjacent to or at the evaporation section caused by a standing column of the liquid with optionally a pump. The flow around the loop at high speed sufficient to carry all condensate forwardly is caused solely by application of energy to the system by the heat source. Inert gases are collected immediately upstream of the trap and can be purged therefrom.

1 . A method for transferring heat from a combustion heat source to a fluid to be heated comprising:
 providing a combustion heat source;   providing a fluid to be heated at a position spaced from the heat source;   providing a closed system including at least one conduit;   providing an evaporation section of the closed system at the heat source;   providing a condensation section of the closed system in the fluid to be heated;   providing a heat transfer fluid medium within the closed system having a temperature of boiling from liquid to vapor such that heat from the heat source causes the liquid to boil to form a vapor in the evaporation section and such that release of heat from the condensation section to the fluid to be heated causes the vapor to condense to liquid in the condensation section;   the at least one conduit forming a loop extending from the evaporation section through the condensation section and back to the evaporation section so as to conduct the heat transfer fluid medium from the evaporation section to the condensation section and back to the evaporation section;   applying heat energy to the heat transfer medium by the heat source at the vaporizer section so that the thermal energy causes expansion of volume due to a change of state;   flow around the loop being biased in one direction by the creation of a head.   
     
     
         2 . The method according to  claim 1  wherein the conduit and condensation section have a resistance to flow of the vapor from the vaporizer section to and through the condensation section and wherein the head is arranged such that, subsequent to start-up and during steady state flow of the heat transfer fluid medium in the loop, the head defines a pressure in the liquid at least equal to a pressure drop in the vapor caused by the resistance to flow of the vapor in the conduit from the evaporation section to and through the condensation section. 
     
     
         3 . The method according to  claim 1  wherein the head is generated by a standing column of liquid without assistance from a pump. 
     
     
         4 . The method according to  claim 1  wherein the head is created by a combination of pressure developed by a pump and a standing column of the liquid. 
     
     
         5 . The method according to  claim 4  wherein the condenser is higher than the pump and there is arranged to be a column of liquid at the inlet to the pump. 
     
     
         6 . The method according to  claim 1  wherein there is provided a pump and the condenser is lower than the pump and the pump is arranged to generate a suction at the inlet acting to lift the liquid to the pump. 
     
     
         7 . The method according to  claim 1  wherein the head is partly generated by a pump and the operation of the process is controlled by varying the flow rate of pump. 
     
     
         8 . The method according to  claim 8  wherein there is provided a viewing port and the operation of the process is controlled by varying the pump while viewing passage of vapor from the evaporation section so as to ensure passage substantially wholly of vapor with a minimal amount of liquid. 
     
     
         9 . The method according to  claim 7  wherein the pump is a positive displacement pump so that the rate of flow is directly proportional to a rotation rate of the pump. 
     
     
         10 . The method according to  claim 9  wherein the condensation section is arranged at a height above the pump such that a column of liquid generated thereby generates a pressure greater than a required pressure for optimum operation and wherein the positive displacement pump generates an outlet pressure below that of the column. 
     
     
         11 . The method according to  claim 1  wherein the system contains a total volume of liquid less than 43.5 litres or 1.5 cu. ft. 
     
     
         12 . The method according to  claim 1  wherein the system is evacuated prior to start up. 
     
     
         13 . The method according to  claim 12  wherein the system is evacuated prior to start up so that the operating pressure in the vapor is less than 15 psi. 
     
     
         14 . The method according to  claim 12  wherein there is provided a compressor having a storage tank and the system is evacuated prior to start up by connecting the inlet of the compressor to the system and wherein the system is purged after shut down by compressed air from the storage tank. 
     
     
         15 . The method according to  claim 1  wherein the flow of vapor from the evaporation section to the condensation section is at sufficient velocity to carry all condensate forwardly to a position where it can flow around the loop under gravity back to the evaporation section. 
     
     
         16 . The method according to  claim 1  wherein substantially all the vapor generated in the evaporation section is caused to condense in the condensation section. 
     
     
         17 . The method according to  claim 1  wherein substantially no heat transferred is transferred to the fluid to be heated by cooling of the condensed liquid. 
     
     
         18 . A method for transferring heat from a combustion heat source to a fluid to be heated comprising:
 providing a combustion heat source;   providing a fluid to be heated at a position spaced from the heat source;   providing a closed system including at least one conduit;   providing an evaporation section of the closed system at the heat source;   providing a condensation section of the closed system in the fluid to be heated;   providing a heat transfer fluid medium within the closed system having a temperature of boiling from liquid to vapor such that heat from the heat source causes the liquid to boil to form a vapor in the evaporation section and such that release of heat from the condensation section to the fluid to be heated causes the vapor to condense to liquid in the condensation section;   the at least one conduit forming a loop extending from the evaporation section through the condensation section and back to the evaporation section so as to conduct the heat transfer fluid medium from the evaporation section to the condensation section and back to the evaporation section;   applying heat energy to the heat transfer medium by the heat source at the vaporizer section thermal energy causes expansion of volume due to a change of state;   and causing boiling of the liquid in the evaporation section and flow of the vapor from the evaporation section to carry non-vapor additives in the liquid in the evaporation section into the conduit with the vapor.   
     
     
         19 . The method according to  claim 18  wherein the conduit is arranged relative to the evaporation section such that boiling of the liquid in the evaporation section does not cause liquid to bridge the conduit so as to act as a bubble pump. 
     
     
         20 . The method according to  claim 18  wherein the conduit is arranged relative to the evaporation section such that the velocity of the vapor is greater than 500 ft/sec. 
     
     
         21 . A method for transferring heat from a combustion heat source to a fluid to be heated comprising:
 providing a combustion heat source;   providing a fluid to be heated at a position spaced from the heat source;   providing a closed system including at least one conduit;   providing an evaporation section of the closed system at the heat source;   providing a condensation section of the closed system in the fluid to be heated;   providing a heat transfer fluid medium within the closed system having a temperature of boiling from liquid to vapor such that heat from the heat source causes the liquid to boil to form a vapor in the evaporation section and such that release of heat from the condensation section to the fluid to be heated causes the vapor to condense to liquid in the condensation section;   the at least one conduit forming a loop extending from the evaporation section through the condensation section and back to the evaporation section so as to conduct the heat transfer fluid medium from the evaporation section to the condensation section and back to the evaporation section;   applying heat energy to the heat transfer medium by the heat source at the vaporizer section thermal energy causes expansion of volume due to a change of state;   wherein the system is at least partly evacuated prior to start up such that during steady state operation the pressure in the system is less than 15 psi above atmospheric pressure.   
     
     
         22 . A method for transferring heat from a combustion heat source to a fluid to be heated comprising:
 providing a combustion heat source;   providing a fluid to be heated at a position spaced from the heat source;   providing a closed system including at least one conduit;   providing an evaporation section of the closed system at the heat source;   providing a condensation section of the closed system in the fluid to be heated;   providing a heat transfer fluid medium within the closed system having a temperature of boiling from liquid to vapor such that heat from the heat source causes the liquid to boil to form a vapor in the evaporation section and such that release of heat from the condensation section to the fluid to be heated causes the vapor to condense to liquid in the condensation section;   the at least one conduit forming a loop extending from the evaporation section through the condensation section and back to the evaporation section so as to conduct the heat transfer fluid medium from the evaporation section to the condensation section and back to the evaporation section;   applying heat energy to the heat transfer medium by the heat source at the vaporizer section thermal energy causes expansion of volume due to a change of state;   wherein the total volume of liquid in the system is less than 43.5 litres or 1.5 cu ft.   
     
     
         23 . A method for transferring heat from a combustion heat source to a fluid to be heated comprising:
 providing a combustion heat source;   providing a fluid to be heated at a position spaced from the heat source;   providing a closed system including at least one conduit;   providing an evaporation section of the closed system at the heat source;   providing a condensation section of the closed system in the fluid to be heated;   providing a heat transfer fluid medium within the closed system having a temperature of boiling from liquid to vapor such that heat from the heat source causes the liquid to boil to form a vapor in the evaporation section and such that release of heat from the condensation section to the fluid to be heated causes the vapor to condense to liquid in the condensation section;   the at least one conduit forming a loop extending from the evaporation section through the condensation section and back to the evaporation section so as to conduct the heat transfer fluid medium from the evaporation section to the condensation section and back to the evaporation section;   applying heat energy to the heat transfer medium by the heat source at the vaporizer section thermal energy causes expansion of volume due to a change of state;   wherein flow around the loop is biased in one direction by a head created in part by a pump;   and wherein there is provided a viewing port for viewing passage of vapor from the evaporation section;   and wherein the operation of the process is controlled by varying the flow rate of the pump while viewing passage of vapor from the evaporation section so as to ensure passage substantially wholly of vapor with a minimal amount of liquid.   
     
     
         24 . A method for transferring heat from a combustion heat source to a fluid to be heated comprising:
 providing a combustion heat source;   providing a fluid to be heated at a position spaced from the heat source;   providing a closed system including at least one conduit;   providing an evaporation section of the closed system at the heat source;   providing a condensation section of the closed system in the fluid to be heated;   providing a heat transfer fluid medium within the closed system having a temperature of boiling from liquid to vapor such that heat from the heat source causes the liquid to boil to form a vapor in the evaporation section and such that release of heat from the condensation section to the fluid to be heated causes the vapor to condense to liquid in the condensation section;   the at least one conduit forming a loop extending from the evaporation section through the condensation section and back to the evaporation section so as to conduct the heat transfer fluid medium from the evaporation section to the condensation section and back to the evaporation section;   applying heat energy to the heat transfer medium by the heat source at the vaporizer section thermal energy causes expansion of volume due to a change of state;   wherein flow around the loop is biased in one direction by a head created in part by a pump;   and wherein the pump is a positive displacement pump so that the rate of flow is directionally proportional to a rotation rate of the pump.   
     
     
         25 . The method according to  claim 24  wherein the condensation section is arranged at a height above the pump such that a column of liquid generated thereby generates a pressure greater than a required pressure for optimum operation and wherein the positive displacement pump generates an outlet pressure below that of the column.