Fire extinguishing system for an organic rankine cycle hydrocarbon evaporator

Abstract

The present invention provides an organic Rankine cycle energy recovery system comprising features which provide for fire suppression and/or ignition suppression in the event of an unintentional release of a flammable component of the system, for example a flammable working fluid such as cyclopentane, into a part of the of the system in which the prevailing temperature is higher than the autoignition temperature of the flammable component. In one embodiment, and the organic Rankine cycle energy recovery system comprises an inert gas source disposed upstream of a hydrocarbon evaporator and configured to purge the hydrocarbon evaporator with an inert gas on detection of a leak thereby.

1 . An organic Rankine cycle energy recovery system comprising:
 (a) an evaporator apparatus comprising a housing, a heat source gas inlet, a heat source gas outlet, a working fluid inlet, a working fluid outlet, and a heat exchange tube disposed within the housing and in fluid communication with the working fluid inlet and the working fluid outlet;   (b) a detector capable of sensing the working fluid or a combustion by-product thereof;   (c) a work extraction device;   (d) a condenser;   (e) a pump;   (f) an inert gas source disposed upstream of the evaporator;   (g) a controller configured to receive an output from the detector; and   (h) a heat source gas by-pass;   wherein the controller is configured to actuate the inert gas source,   and wherein the controller is configured to divert a heat source gas to the heat source gas by-pass,   and wherein the controller is configured to prevent introduction of a working fluid into the evaporator.   
     
     
         2 . The energy recovery system of  claim 1 , wherein the detector is selected from the group consisting of gas sensors, photo-detectors, solid-state sensors, infrared spectrometric detectors, ultraviolet detectors, temperature sensors, and flame sensors. 
     
     
         3 . The energy recovery system of  claim 1 , wherein the detector is disposed within the evaporator housing. 
     
     
         4 . The energy recovery system of  claim 1 , wherein the detector is disposed outside of the evaporator housing. 
     
     
         5 . The energy recovery system of  claim 1 , wherein the detector is disposed downstream of the evaporator. 
     
     
         6 . The energy recovery system of  claim 1 , wherein the inert gas source comprises an inert gas selected from the group consisting of nitrogen, argon, carbon dioxide, and combinations of tow or more of the foregoing gases. 
     
     
         7 . The energy recovery system of  claim 1 , wherein the work extraction device comprises a turbine. 
     
     
         8 . The energy recovery system according to  claim 9 , wherein said turbine is configured to produce electrical energy. 
     
     
         9 . A method of energy recovery from an organic Rankine cycle system comprising:
 (i) introducing a heat source gas into an evaporator apparatus comprising a heat exchange tube containing a working fluid;   (ii) transferring heat from the heat source gas to the working fluid to provide a heated working fluid;   (iii) transferring energy from the heated working fluid to a work extraction device located outside of the evaporator apparatus; and   (iv) returning the working fluid to the evaporator apparatus;   wherein the method is carried out in an organic Rankine cycle energy recovery system configured to detect the working fluid or a combustion by-product thereof and to generate a signal in response to the detection,   and wherein the organic Rankine cycle energy recovery system is configured to receive the signal from the detector at a controller,   and wherein the controller is configured to actuate an inert gas source upstream of the evaporator in response the signal,   and wherein the controller is configured to divert the heat source gas into a heat source gas by-pass in response the signal,   and wherein the controller is configured to prevent introduction of a working fluid into the evaporator apparatus in response the signal.   
     
     
         10 . The method according to  claim 9 , wherein the organic Rankine cycle energy recovery system comprises:
 (a) an evaporator apparatus comprising a housing, a heat source gas inlet, a heat source gas outlet, a working fluid inlet, a working fluid outlet, and a heat exchange tube disposed within the housing and in fluid communication with the working fluid inlet and the working fluid outlet;   (b) a detector capable of sensing the working fluid or a combustion by-product thereof;   (c) a work extraction device;   (d) a condenser;   (e) a pump;   (f) an inert gas source disposed upstream of the evaporator apparatus;   (g) a controller configured to receive an output from the detector; and   (h) a heat source gas by-pass   wherein the controller is configured to actuate the inert gas source,   and wherein the controller is configured to divert a heat source gas to the heat source gas by-pass,   and wherein the controller is configured to prevent introduction of a working fluid into the evaporator.   
     
     
         11 . The method according to  claim 10 , wherein the detector is selected from the group consisting of gas sensors, photo-detectors, solid-state sensors, infrared spectrometric detectors, ultraviolet detectors, temperature sensors, and flame sensors. 
     
     
         12 . The method according to  claim 10 , wherein the inert gas source comprises an inert gas selected from the group consisting of nitrogen, argon, carbon dioxide and combinations thereof. 
     
     
         13 . The method according to  claim 9 , wherein the working fluid is a hydrocarbon. 
     
     
         14 . The method according to  claim 9 , wherein the working fluid is selected from the group consisting of cyclopentane and cyclohexane. 
     
     
         15 . The method according to  claim 9 , wherein the heat source gas contains oxygen. 
     
     
         16 . The method according to  claim 9 , wherein the heat source gas is flue gas. 
     
     
         17 . The method according to  claim 9 , wherein the inert gas source comprises at least one inert gas selected from the group consisting of nitrogen, argon, and carbon dioxide. 
     
     
         18 . The method according to  claim 10 , wherein the detector is disposed within the evaporator housing. 
     
     
         19 . The method according to  claim 10 , wherein the detector is disposed downstream of the evaporator. 
     
     
         20 . An evaporator apparatus for use in an organic Rankine cycle energy recovery system, comprising:
 a housing, a heat source gas inlet, a heat source gas outlet, a working fluid inlet, a working fluid outlet, a heat exchange tube disposed within the housing and in fluid communication with the working fluid inlet and the working fluid outlet, and a detector capable of sensing the working fluid, or a combustion by-product thereof, wherein the working fluid inlet is coupled to a valve configured to be switchable between a working fluid source and a inert gas source.