Heat tracing apparatus with heat-driven pumping system

Abstract

In a heat tracing system using heat from a radiant heater to heat a circulating fluid, thermoelectric generation modules are used to generate electricity for powering a circulating pump. Thermoelectric power generation modules are sandwiched between a heat-absorbing plate and a heat sink, and this assembly is positioned with the heat-absorbing plate adjacent to a radiant heater. A conduit loop passes through the heat sink, such that a fluid circulating through the conduit is heated from heat drawn from the heater into the heat sink. Due to the temperature differential between the hot and cold sides of the thermoelectric modules, the modules produce electricity to power the pump circulating the fluid through the conduit loop. Supplementary heat exchanger components may be provided for additional fluid-heating capacity, and thereby increasing the amount of heat available for the heat tracing loop.

What is claimed is: 
     
         1 . A heat tracing apparatus comprising:
 (a) a first flameless catalytic heater having a generally flat heat-radiating face;   (b) a first heat-absorbing plate having an inner face and a dark-coloured outer face, said outer face being positioned adjacent and substantially parallel to the heat-radiating face of the first catalytic heater with an intervening air space therebetween, such that the outer face of the first heat-absorbing plate will be exposed to radiant heat from the first catalytic heater upon actuation thereof;   (c) a first plurality of electrically interconnected thermoelectric modules each having a hot side and a cold side;   (d) a heat sink comprising one or more blocks of a heat-conducting material and having a first side and a second side;   (e) a closed conduit loop passing through the heat sink; and   (f) a pump for circulating a fluid through the conduit loop;   
       wherein the first plurality of thermoelectric modules are sandwiched between the inner face of the first heat-absorbing plate and the first side of the heat sink, with their hot sides in thermally-conductive proximity to the inner face of the heat-absorbing plate, and with their cold sides in thermally-conductive proximity to the first side of the heat sink, such that when a fluid is introduced into the conduit loop and the first catalytic heater is actuated:
 (g) the first plurality of thermoelectric modules will produce an electric current; 
 (h) the pump will circulate the fluid through the conduit loop, powered solely by said electric current; and 
 (i) the fluid circulating through the conduit loop will be heated by heat drawn from the heat sink. 
 
     
     
         2 . A heat tracing apparatus as in  claim 1 , wherein each block of heat-conducting material has one or more channels therethrough, adapted to allow passage of the heat tracing conduit loop. 
     
     
         3 . A heat tracing apparatus as in  claim 1 , wherein each block of heat-conducting material has one or more channels therethrough, adapted for connection to the heat tracing conduit loop. 
     
     
         4 . A heat tracing apparatus as in  claim 1 , wherein the heat-conducting material of at least one of the one or more blocks of heat-conducting material comprises a metal selected from the group consisting of copper and aluminum. 
     
     
         5 . A heat tracing apparatus as in  claim 1 , further comprising a second heat-absorbing plate and a second plurality of thermoelectric modules, said second plurality of thermoelectric modules being sandwiched between the second heat-absorbing plate and the second face of the heat sink. 
     
     
         6 . A heat tracing apparatus as in  claim 1 , wherein the conduit loop comprises an outlet section and a return section. 
     
     
         7 . A heat tracing apparatus as in  claim 6 , further comprising a collector tank having an inlet and an outlet, said collector tank being in fluid communication with the conduit loop, with the conduit loop's outlet section connected to the tank outlet of the tank, and with the conduit loop's return section connected to the tank inlet. 
     
     
         8 . A heat tracing apparatus as in  claim 1  wherein the first catalytic heater is fuelled by a fuel gas selected from the group consisting of propane and natural gas. 
     
     
         9 . A heat tracing apparatus as in  claim 7 , further comprising a by-pass conduit and an associated by-pass valve, said by-pass valve being operable between:
 (a) a first position in which fluid will flow from the collector tank, through the heat sink, and thence through the conduit loop back to the collector tank, but will not flow through the by-pass conduit; and   (b) a second position in which fluid will flow from the collector tank, through the heat sink, and thence through the by-pass conduit back to the collector tank, but will not flow through the conduit loop from the heat sink back to the collector tank.   
     
     
         10 . A heat tracing apparatus as in  claim 1 , further comprising a thermal safety switch associated with the heat sink, said safety switch being operable to shut off the flow of fuel gas to the first catalytic heater if the temperature of the heat sink exceeds a predetermined value. 
     
     
         11 . A heat tracing apparatus as in  claim 10  wherein the thermal safety switch comprises a temperature probe for sensing the temperature of the heat sink. 
     
     
         12 . A heat tracing apparatus as in  claim 1 , further comprising:
 (a) a second flameless catalytic heater having a generally flat heat-radiating face;   (b) a second heat-absorbing plate having an inner face and a dark-coloured outer face, said outer face being positioned adjacent and substantially parallel to the heat-radiating face of the second catalytic heater with an intervening air space therebetween, such that the outer face of the second heat-absorbing plate will be exposed to radiant heat from the second catalytic heater upon actuation thereof; and   (c) a second plurality of electrically interconnected thermoelectric modules each having a hot side and a cold side;   
       wherein:
 (d) the second plurality of thermoelectric modules are sandwiched between the inner face of the second heat-absorbing plate and the second side of the heat sink, with their hot sides in thermally-conductive proximity to the inner face of the second heat-absorbing plate, and with their cold sides in thermally-conductive proximity to the second side of the heat sink, such that the second plurality of thermoelectric modules produce an electric current; and 
 (e) a fluid circulating through the conduit loop will be further heated by heat drawn into the heat sink from the second catalytic heater. 
 
     
     
         13 . A heat tracing apparatus as in  claim 1 , further comprising a finned-tube heat exchanger and a second flameless catalytic heater having a heat-radiating face, wherein:
 (a) the conduit loop passes through the heat exchanger; and   (b) the second catalytic heater is positioned with its heat-radiating face adjacent to the heat exchanger such that a fluid flowing through the heat exchanger will be heated by radiant heat from the second catalytic heater.   
     
     
         14 . A heat tracing apparatus as in  claim 1  wherein the conduit loop flows through a finned-tube heat exchanger positioned above the first catalytic heater such that a fluid flowing through the heat exchanger will be heated by waste heat from the first catalytic heater. 
     
     
         15 . A heat tracing apparatus as in  claim 12 , further comprising a by-pass conduit and an associated by-pass valve, said by-pass valve being operable between a first position in which fluid is free to flow through the heat sink and thence through the heat exchanger, and a second position in which fluid will flow through the heat sink but not through the heat exchanger.