Methods for periodic removal of contaminated working fluid from organic rankine cycle power systems

Abstract

An optimized Rankine thermodynamic cycle system and method include utilizing a working fluid including a base component and an effective amount of a lower boiling point component, where the effective amount is sufficient to raise a power utilization efficiency of the systems by up to 10%, without changing a weight of the fluid reducing turbine efficiency for the particular base component and for optimizing output control valves for adjusting the working fluid composition and temperature sensors measuring an initial temperature of a coolant medium and a final temperature of a heat source stream to computer control valves to continuously adjust a pressure and a flow rate of a working fluid stream to be vaporized so that a heat utilization of the system is about 99% increasing output by approximately 3% to 6% on a sustained and permanent yearly basis.

We claim: 
     
         1 . A method for removing oil contamination from an organic Rankine cycle system comprising:
 a condenser subsystem comprising at least one first heat exchange unit that condenses a spent working fluid stream to form a condensed working fluid stream,   a pressure and flow rate adjusting subsystem comprising a feed pump to form a pressurized condensed working fluid stream,   a vaporization or boiling subsystem comprising at least one heat exchange unit that vaporizes the pressurized condensed working fluid stream to form a vaporized working fluid stream,   an energy conversion subsystem comprising at least one turbine, an admission valve, and a turbine bypass valve that extracts a portion of thermal energy from the vaporized working fluid stream to form the spent working fluid stream, and   a working fluid reserve tank subsystem including a reserve tank, a first valve for stopping a flow of working fluid to the vaporization subsystem, a second valve for stopping a flow of working fluid to the reserve tank, and a third valve for directing working fluid from the reserve tank back into the system,   
       where the method comprising the steps of:
 concurrently, stopping the feed pump, closing the admission valve and the first valve to stop the flow of working fluid through the system, and opening the second valve and the turbine bypass valve to direct cleaned working fluid into the reserve tank, 
 continuing a flow of a heat source stream into the vaporization or boiling subsystem and a flow of a cooling stream into the condensation subsystem so that residual working fluid contaminated with a turbine lubricating oil boils in the vaporization or boiling subsystem to form a highly contaminated working fluid and a cleaned vaporized working fluid, which is condensed in the condensation subsystem to form a cleaned condensed working fluid, which is collected in the reserve tank, 
 removing the highly contaminated working fluid from the vaporization or boiling subsystem, 
 adding an amount of working fluid to the reserve tank to account for the removed highly contaminated working fluid, 
 concurrently, opening the third valve, closing the second valve, and charging the working fluid from the reserve tank into the system, 
 concurrently closing the third valve, starting the feed pump, opening the admission valve and the first valve, and closing the turbine bypass valve restarting the system of clean or substantially cleaned working fluid, and 
 periodically repeating the steps on a periodic basis. 
 
     
     
         2 . The method of  claim 1 , wherein the periodic basis occurs when a degree of oil contamination of the working fluid decreases a performance of the system. 
     
     
         3 . The method of  claim 1 , wherein the periodic basis is yearly. 
     
     
         4 . The method of  claim 1 , wherein the method occurs in a time period of less than 1 day. 
     
     
         5 . The method of  claim 4 , wherein the time period is between about 4 and about 24 hours. 
     
     
         6 . The method of  claim 5 , wherein the time period is between about 6 and about 24 hours. 
     
     
         7 . The method of  claim 1 , wherein as the amount of working fluid in the vaporization or boiling subsystem is reduced, a concentration of contaminating oil in a remaining working fluid in the vaporization subsystem goes up and a temperature in the vaporization or boiling subsystem goes up, when this temperature reaches a desired level only a small amount of heavily contaminated working fluid is left in the vaporization or boiling subsystem, which is safely removed from the system for disposal removing all or substantially all of the oil contamination from the system. 
     
     
         8 . The method of  claim 7 , wherein the small amount of the heavily contaminated working fluid is between 5% and 10% of the entire working fluid amount.