Waste heat recovery system

Abstract

A waste heat recovery system in which hot waste fluids, such as flue gasses, pass through a fluid heat exchanger configured to transfer energy in the form of heat to a heat transfer liquid, preferably molten salt. The energy in the molten salt is used to generate useable power such as electrical energy. The waste gas heat recovery system is especially adapted for use with batch processes, such as steelmaking and copper converting, and allows continuous or substantially continuous power production.

1 . A waste gas heat recovery system, comprising:
 a source of waste heat fluid;   a first heat exchanger configured to transfer energy from the waste heat fluid to a heat transfer fluid;   a second heat exchanger configured to transfer energy from the heat transfer fluid to a working fluid; and   a power production system configured to convert the transferred energy in the working fluid into electrical energy.   
     
     
         2 . The system of  claim 1 , wherein the working fluid is steam and the power production system further comprises:
 a steam generator;   a steam turbine; and   an electrical generator.   
     
     
         3 . The system of  claim 1 , wherein the source of the waste heat is flue gasses from a steelmaking process. 
     
     
         4 . The system of  claim 3 , wherein the steelmaking process comprises an electric arc furnace 
     
     
         5 . The system of  claim 1 , wherein the heat transfer fluid is molten salt. 
     
     
         6 . The system of  claim 5  further comprising:
 a cold salt tank; and 
 a hot salt tank, all arranged in fluid communication with the first heat exchanger. 
 
     
     
         7 . A waste gas heat recovery system, comprising:
 a source of waste heat gas;   a first heat exchanger configured to transfer energy from the waste heat gas to a heat transfer fluid;   a second heat exchanger configured to transfer energy from the heat transfer fluid to water to produce steam, or other vaporized fluid; and   an electrical power generating system configured to convert the energy in the steam or vapor into electrical energy.   
     
     
         8 . The system of  claim 1 , wherein the source of waste heat gas is a steelmaking process. 
     
     
         9 . The system of  claim 2 , wherein the heat transfer fluid is molten salt. 
     
     
         10 . The system of  claim 3 , wherein the power generating system is a steam turbine. 
     
     
         11 . A method of recovering waste heat comprising:
 providing waste heat;   passing the waste heat through a first heat exchanger configured to transfer energy from the waste heat to a heat transfer fluid;   passing the heat transfer fluid through a second heat exchanger within a power production system.   
     
     
         12 . The method of  claim 11  wherein the waste heat is provided by flue gasses generate by a steelmaking process. 
     
     
         13 . The method of  claim 12  wherein the steelmaking process comprises an electric arc furnace. 
     
     
         14 . The method of  claim 11  wherein the heat transfer fluid is molten salt. 
     
     
         15 . The method of  claim 14  further comprising:
 providing the molten salt to the first heat exchanger from a cold salt storage tank; 
 storing the molten salt in a thermal storage prior to passing the heat transfer fluid through a second heat exchanger within a power production system. 
 
     
     
         16 . The method of  claim 11  further comprising generating steam in the second heat exchanger. 
     
     
         17 . The method of  claim 16  further comprising the providing the steam generated by the second heat exchanger to a steam turbine. 
     
     
         18 . The method of  claim 17  of generating electrical power from the steam turbine. 
     
     
         19 . The method of  claim 14  further comprising generating steam in the second heat exchanger. 
     
     
         20 . The method of  claim 19  further comprising the providing the steam generated by the second heat exchanger to a steam turbine.