Method and apparatus for operating a fuel cell in combination with an absorption chiller

Abstract

A standard phosphoric acid fuel cell power plant ( 11 ) has its heat exchanger ( 29 ) removed such that a higher temperature coolant flow can be directed from the system to the generator ( 37 ) of an absorption chiller ( 34 ). In one embodiment, the higher temperature coolant may flow directly from the fuel cell stack ( 14 ) to the generator and after passing therethrough, it is routed back to the high temperature coolant loop ( 27 ). In another embodiment, the higher temperature coolant is made to transfer some of its heat to a lower temperature coolant and the lower temperature coolant is then made to flow directly to the generator and back to the lower temperature coolant loop ( 22 ). In the first embodiment, either a double effect absorption chiller or a single effect absorption chiller is used, while in the second embodiment a single effect absorption chiller is used.

1 . A combined system of an absorption chiller and a fuel cell power plant of the type having a fuel cell stack and an associated stack coolant loop in which the coolant is heated to a level of high grade heat, comprising:
 an absorption chiller having a generator for heating an absorptive solution;   a first conduit for conducting the flow of heated coolant directly from the fuel cell stack to the generator for providing heat thereto and, in the process, being cooled; and   a second conduit for conducting the cooled coolant back to the stack coolant loop.   
   
   
       2 . A combined system as set forth in  claim 1  wherein the temperature level of said high grade heat is in the range of 310-335° F. 
   
   
       3 . A combined system as set forth in  claim 1  wherein said absorption chiller is a double effect chiller and the flow of heated coolant is conducted into a high stage generator. 
   
   
       4 . A combined system as set forth in  claim 1  wherein said absorption chiller is a single effect absorption chiller. 
   
   
       5 . A combined system as set forth in  claim 1  wherein said fuel cell power plant includes another coolant loop with the coolant therein being heated to a temperature level of low grade heat and further wherein heat is transferred from said stack coolant loop to said other coolant loop. 
   
   
       6 . A combined system as set forth in  claim 5  wherein said fuel cell power plant includes a fuel processing system which generates heat which is transferred to said other coolant loop. 
   
   
       7 . A combined system as set forth in  claim 6  wherein said fuel cell power plant includes another heat source which transfers heat to said other coolant loop, said other heat source originating at said fuel cell stack. 
   
   
       8 . A combined system as set forth in  claim 5  wherein said second conduit is fluidly connected to said stack coolant loop at a point downstream of said point wherein said heat is transferred from said stack coolant loop to said other coolant loop. 
   
   
       9 . A combined system as set forth in  claim 1  wherein said fuel cell power plant includes phosphoric acid fuel cells. 
   
   
       10 . A method of adapting for use with an absorption chiller, a fuel cell power plant having a fuel cell stack with a first coolant flowing therethrough in a high grade heat loop which passes through a first heat exchanger to transfer heat to a second coolant in a low grade heat loop which, in turn, passes through a second heat exchanger to transfer heat to said second heat exchanger, comprising the steps of:
 removing the second heat exchanger;   providing an absorption chiller having a generator;   directly connecting said high grade heat loop to said generator such that the first coolant flows from said high grade heat loop, through said generator and back to said high grade heat loop.   
   
   
       11 . The method as set forth in  claim 10  wherein said absorption chiller is a double effect absorption chiller and the generator is a high stage generator. 
   
   
       12 . The method as set forth in  claim 10  wherein said absorption chiller is a single effect absorption chiller. 
   
   
       13 . The method as set forth in  claim 10  wherein the point where said first coolant flows back to said high grade heat loop is a point downstream from said first heat exchanger. 
   
   
       14 . A method for adapting for use with an absorption chiller, a fuel cell power plant having a fuel cell stack with a first coolant flowing therethrough in a high grade heat loop which passes through a first heat exchanger to transfer heat to a second coolant in the low grade heat loop which, in turn, passes through a second heat exchanger to transfer heat to said second heat exchanger, comprising the steps of:
 removing the second heat exchanger;   providing an absorption chiller having a generator; and   fluidly connecting said low grade heat loop to said generator such that the second coolant flows from said low grade heat loop, through said generator and back to said low grade heat loop.   
   
   
       15 . A method as set forth in  claim 14  wherein said absorption chiller is a double effect absorption chiller and said generator is a high stage generator. 
   
   
       16 . A method as set forth in  claim 14  wherein said absorption chiller is a single effect absorption chiller. 
   
   
       17 . A method as set forth in  claim 14  wherein said fuel cell stack includes phosphoric acid fuel cells.