Energy Conversion Using Rankine Cycle System

Abstract

A process for recovering waste heat in an organic Rankine cycle system which comprises passing a liquid phase working fluid through heat exchange in successive communication with two or more process streams which thus heat the working fluid, removing a vapor phase working fluid from the heat exchanger, passing the vapor phase working fluid to an expander wherein the waste heat is converted into mechanical energy, and passing the vapor phase working fluid from the expander to a condenser wherein the vapor phase working fluid is condensed into the liquid phase working fluid.

1 . An apparatus for generating power from two or more process streams having different temperatures in an organic Rankine cycle system, comprising:
 (a) one or more lower-temperature exchangers for exchanging heat between at least one lower-temperature process stream and a liquid Rankine-cycle working fluid to obtain a heated working fluid;   (b) one or more higher-temperature exchangers for exchanging heat between at least one higher-temperature process stream and the heated working fluid to obtain a vaporized working fluid;   (c) an expander driven by the vaporized working fluid to produce power to an output shaft and a reduced-pressure working fluid;   (d) a working-fluid condenser for reducing the temperature of the reduced-pressure working fluid to obtain a liquid working fluid;   (e) a pump to circulate the liquid working fluid in the cycle system;   (f) conduits connecting the one or more lower-temperature exchangers, higher-temperature exchangers, expander, condenser, pump, and working-stream bypasses around one or both of the exchangers; and,   (g) a controller for monitoring flow rates, temperatures and pressures of the two or more process streams and working fluid and for providing control signals to the pump and expander.   
     
     
         2 . The apparatus of  claim 1  further comprising a generator to produce electric power connected to the output shaft of the expander. 
     
     
         3 . The apparatus of  claim 1  wherein one or more of the lower-temperature and higher-temperature exchangers are condensers for condensing at least part of the respective process streams from vapor phase into liquid phase. 
     
     
         4 . The apparatus of  claim 3  wherein one or more of the condensers are overhead condensers of distillation columns. 
     
     
         5 . The apparatus of  claim 1  wherein one or more of the lower-temperature and higher-temperature exchangers is a reactor effluent cooler. 
     
     
         6 . The apparatus of  claim 1  wherein at least one of the lower-temperature exchangers is a product cooler. 
     
     
         7 . The apparatus of  claim 1  wherein one or more of the exchangers has an enhanced nucleate boiling surface. 
     
     
         8 . The apparatus of  claim 1  wherein one or more of the condensers has an enhanced condensing surface. 
     
     
         9 . The apparatus of  claim 1  wherein the working fluid comprises R-245a. 
     
     
         10 . The apparatus of  claim 1  comprising two or more low-temperature exchangers, each for exchanging heat between at least one lower-temperature process stream and a liquid Rankine-cycle working fluid to obtain a heated working fluid; 
     
     
         11 . An apparatus for generating power from two or more process streams having different temperatures in an organic Rankine cycle system, comprising:
 (a) a lower-temperature condenser for condensing at least one lower-temperature process stream by heating a liquid Rankine-cycle working fluid to obtain a heated working fluid;   (b) a higher-temperature condenser for condensing at least one higher-temperature process stream by heating the heated working fluid to obtain a vaporized working fluid;   (c) an expander driven by the vaporized working fluid to produce power to an output shaft and a reduced-pressure working fluid;   (d) a working-fluid condenser for reducing the temperature of the reduced-pressure working fluid to obtain a liquid working fluid;   (e) a pump to circulate the liquid working fluid in the cycle system;   (f) conduits connecting the lower-temperature condenser, higher-temperature condenser, expander, condenser, pump, and working-stream bypasses around one or both of the condenser; and,   (g) a controller for monitoring flow rates, temperatures and pressures of the two or more process streams and working fluid and for providing control signals to the pump and expander.   
     
     
         12 . The apparatus of  claim 11  wherein one or more of the lower-temperature and higher-temperature exchangers are condensers for condensing at least part of the respective process streams from vapor phase into liquid phase. 
     
     
         13 . The apparatus of  claim 12  wherein one or more of the condensers are overhead condensers of distillation columns. 
     
     
         14 . The apparatus of  claim 11  further comprising a generator to produce electric power connected to the output shaft of the expander. 
     
     
         15 . The apparatus of  claim 11  wherein one or more of the exchangers has an enhanced nucleate boiling surface. 
     
     
         16 . The apparatus of  claim 11  wherein the working fluid comprises R-245a. 
     
     
         17 . A process for generating power from two process streams having different temperatures in an organic Rankine cycle system, comprising:
 (a) cooling a lower-temperature process stream by heating a liquid Rankine-cycle working fluid to obtain a heated working fluid;   (b) cooling a higher-temperature process stream by heating the heated working fluid to obtain a vaporized working fluid;   (c) expanding the vaporized working fluid to produce power to an output shaft and a reduced-pressure working fluid; and,   (d) condensing the reduced-pressure working fluid to obtain the liquid Rankine-cycle working fluid.   
     
     
         18 . The process of  claim 17  further comprising generating power via a generator connected to the output shaft of the expander. 
     
     
         19 . The process of  claim 17  wherein one or more of the process streams comprise overhead vapors of distillation columns and are condensed at least partially to liquid streams. 
     
     
         20 . The process of  claim 17  wherein the working fluid comprises R-245a.