Waste heat recovery generator

Abstract

A low grade waste heat recovery generator system is presented. The system comprises an expander generator set having a compressor rotatably coupled to a generator. The compressor rotates in a reverse direction to operate as an expander. The system also comprises a condenser fluidly coupled to the expander generator set, a refrigerant pump fluidly coupled to the condenser, an evaporator fluidly coupled to the refrigerant pump and the expander generator set, and a working fluid configured to flow from the evaporator to the expander generator set, to the condenser, and to the refrigerant pump in a closed loop Organic Rankin Cycle. The working fluid is heated to a temperature of about 140 ° F. to about 300 ° F.

1 . A low grade waste heat recovery generator system comprising: 
 an expander generator set having a compressor rotatably coupled to a generator, said compressor rotates in a reverse direction to operate as an expander;    a condenser fluidly coupled to said expander generator set;    a refrigerant pump fluidly coupled to said condenser;    an evaporator fluidly coupled to said refrigerant pump and said expander generator set; and    a working fluid configured to flow from said evaporator to said expander generator set to said condenser and to said refrigerant pump in a closed loop Organic Rankin Cycle, wherein said working fluid is heated to a temperature of about 140° F. to about 300° F.    
   
   
       2 . The low grade waste heat recovery generator system of  claim 1 , wherein said compressor is selected from the group consisting of a single screw compressor, a scroll compressor, and a double screw compressor.  
   
   
       3 . The low grade waste heat recovery generator system of  claim 1 , wherein said working fluid changes state in said evaporator to at least one of liquid to gas and liquid to vapor; and wherein said working fluid changes state in said condenser to at least one of gas to liquid and vapor to liquid.  
   
   
       4 . The low grade waste heat recovery generator system of  claim 1 , wherein said working fluid expands through said expander.  
   
   
       5 . The low grade waste heat recovery generator system of  claim 1 , further comprising: 
 at least one sensor coupled to said refrigerant pump, said at least one sensor configured to detect vapor wetness; and    at least one microprocessor coupled to said refrigerant pump, said at least one microprocessor configured to control operation of said refrigerant pump.    
   
   
       6 . The low grade waste heat recovery generator system of  claim 1 , further comprising: 
 a working fluid collector coupled between said condenser and said refrigerant pump.    
   
   
       7 . The low grade waste heat recovery generator system of  claim 1 , wherein said expander rotates said generator to generate electricity.  
   
   
       8 . The low grade waste heat recovery generator system of  claim 1 , further comprising: 
 a forced convection unit fluidly coupled to said condenser configured to provide forced convective cooling of said condenser.    
   
   
       9 . The low grade waste heat recovery generator system of  claim 1 , further comprising: 
 a preheater fluidly coupled to said evaporator and said refrigerant pump.    
   
   
       10 . The low grade waste heat recovery generator system of  claim 1 , wherein said evaporator is thermally coupled to a waste heat source and configured to transfer thermal energy from said waste heat source to said working fluid.  
   
   
       11 . The low grade waste heat recovery generator system of  claim 10 , wherein said waste heat source is selected from the group consisting of internal combustion engine, gas turbines, gas flares in landfills, industrial manufacturing processes, incinerators, boilers, geothermal wells and bio-gas.  
   
   
       12 . The low grade waste heat recovery generator system of  claim 1 , wherein said expander operates at about 800 rpms to about 10,000 rpms.  
   
   
       13 . The low grade waste heat recovery generator system of  claim 1 , wherein said expander generator set is disposed in a generator cabinet and is fluidly coupled to a recovery cabinet housing at least said condenser and said evaporator.  
   
   
       14 . The low grade waste heat recovery generator system of  claim 13 , wherein said generator cabinet is mounted on top of said recovery cabinet forming an integrated enclosure.  
   
   
       15 . A method of operating a waste heat recovery generator system to generate electrical power from low grade waste heat comprising: 
 transferring thermal energy from a waste heat source to a working fluid in an evaporator, said working fluid is heated to a temperature of about 140° F. to about 300° F.;    expanding said working fluid through an expander generator set fluidly coupled to said evaporator, said expander generator set having a compressor rotatably coupled to a generator, said compressor rotates in a reverse direction to operate as an expander;    rotating said expander to generate the electrical power in said generator;    condensing said working fluid in a condenser fluidly coupled to said expander generator set; and    flowing said working fluid to a refrigerant pump fluidly coupled to said condenser; and    pumping said working fluid to said evaporator fluidly coupled to said refrigerant pump in a closed loop Organic Rankin Cycle.    
   
   
       16 . The method of  claim 15 , wherein said compressor is selected from the group consisting of a single screw compressor, a scroll compressor, and a double screw compressor.  
   
   
       17 . The method of  claim 15 , further comprising: 
 coupling at least one microprocessor to said refrigerant pump, said at least one microprocessor configured to control operation of said refrigerant pump.    
   
   
       18 . The method of  claim 17 , wherein said refrigerant pump comprises at least one sensor configured to detect vapor wetness.  
   
   
       19 . The method of  claim 15 , further comprising: 
 cooling said condenser with a forced convection unit.