Dynamic leak detection system in propane heat exchangers

Abstract

Systems and processes for detecting leaks into a refrigeration system having a heat exchanger where the process side is configured to operate at a higher pressure than the refrigerant side. The system includes a refrigerant circulation system including a refrigerant feed pipe fluidly connected to and configured to provide a refrigerant to an inlet of the refrigerant side of the heat exchanger, as well as a refrigerant effluent pipe fluidly connected to and configured to receive a refrigerant from an outlet of the refrigerant side of the heat exchanger. One or more sensors are provided, the sensors being configured to measure a property of the refrigerant, such as temperature, pressure, or flow rate, for example. Additionally, the system for detecting leaks includes a digital control system configured to provide an alert when a signal from at least one of the one or more sensors is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger.

What is claimed: 
     
         1 . A natural gas processing facility, comprising:
 a feed line providing a mixture of acid gases, methane, ethane, propane, and optionally butane and other heavier hydrocarbons;   a compression section comprising one or more compressors configured to receive the mixture from the feed line, increase a pressure of the mixture and output a compressed mixture of methane, ethane, propane, and acid gases;   a flow line for providing the compressed mixture to a stripper, the stripper configured to separate the compressed mixture into an overhead product comprising the acid gases, methane, ethane, and at least a portion of the propane and a bottoms product comprising propane and any butane and other heavier hydrocarbons;   a propane chiller configured to receive the overhead product, chill the overhead product, and output a chilled overhead product;   a flow line for providing the chilled overhead product to a deethanizer, the deethanizer configured to separate the chilled overhead product into an overhead fraction comprising the acid gases, methane and ethane, and a bottoms product comprising propane and any butane and other heavier hydrocarbons;   an overhead condenser configured to condense at least a portion of the overhead fraction, provide reflux to the deethanizer, and to output an overhead vapor product comprising methane, ethane, and acid gases;   a closed loop refrigeration system configured to provide a refrigerant to each of the propane chiller and the overhead condenser;   one or more sensors configured to measure a property of the refrigerant, wherein the one or more sensors are disposed along a refrigerant feed line providing a refrigerant flow to the propane chiller or to the overhead condenser, along a refrigerant effluent flow line from the propane chiller or the overhead condenser, or both;   a digital control system configured to:
 receive a signal from each of the one or more sensors; 
 provide an alert when a signal from one of the one or more sensors is indicative of a leak of acid gases into the closed loop refrigeration loop. 
   
     
     
         2 . The system of  claim 1 , wherein the one or more sensors comprise a pressure sensor configured to measure a pressure of the refrigerant in the refrigerant system; a temperature sensor configured to measure a temperature of the refrigerant in the refrigerant system; and a flow rate sensor configured to measure a flow rate of the refrigerant flow in the refrigerant system. 
     
     
         3 . The system of  claim 1 , wherein the one or more sensors comprise:
 a feed temperature sensor disposed along a refrigerant feed line providing a refrigerant flow to the propane chiller, and an effluent temperature sensor along a refrigerant effluent flow line from the propane chiller, and wherein the digital control system is configured to provide an alert based upon a temperature of the effluent temperature sensor, a difference in temperature between the feed temperature sensor and the effluent temperature sensor, or both; and   a condenser feed temperature sensor disposed along a refrigerant feed line providing a refrigerant flow to the overhead condenser, and an effluent temperature sensor along a refrigerant effluent flow line from the overhead condenser, and wherein the digital control system is configured to provide an alert based upon a temperature of the condenser effluent temperature sensor, a difference in temperature between the condenser feed temperature sensor and the condenser effluent temperature sensor, or both.   
     
     
         4 . The system of  claim 1 , wherein the one or more sensors comprise:
 a feed pressure sensor disposed along a refrigerant feed line providing a refrigerant flow to the propane chiller, and an effluent pressure sensor along a refrigerant effluent flow line from the propane chiller, and wherein the digital control system is configured to provide an alert based upon a pressure of the effluent pressure sensor, a difference in pressure between the feed pressure sensor and the effluent pressure sensor, or both; and   a condenser pressure temperature sensor disposed along a refrigerant feed line providing a refrigerant flow to the overhead condenser, and a condenser effluent pressure sensor disposed along a refrigerant effluent flow line from the overhead condenser, and wherein the digital control system is configured to provide an alert based upon a pressure of the condenser effluent pressure sensor, a difference in pressure between the condenser feed pressure sensor and the condenser effluent pressure sensor, or both.   
     
     
         5 . The system of  claim 1 , wherein the one or more sensors comprise:
 a feed temperature sensor disposed along a refrigerant feed line providing a refrigerant flow to the propane chiller, and an effluent temperature sensor along a refrigerant effluent flow line from the propane chiller, and wherein the digital control system is configured to provide an alert based upon a temperature of the effluent temperature sensor, a difference in temperature between the feed temperature sensor and the effluent temperature sensor, or both;   a condenser feed temperature sensor disposed along a refrigerant feed line providing a refrigerant flow to the overhead condenser, and an effluent temperature sensor along a refrigerant effluent flow line from the overhead condenser, and wherein the digital control system is configured to provide an alert based upon a temperature of the condenser effluent temperature sensor, a difference in temperature between the condenser feed temperature sensor and the condenser effluent temperature sensor, or both;   a feed pressure sensor disposed along a refrigerant feed line providing a refrigerant flow to the propane chiller, and an effluent pressure sensor along a refrigerant effluent flow line from the propane chiller, and wherein the digital control system is configured to provide an alert based upon a pressure of the effluent pressure sensor, a difference in pressure between the feed pressure sensor and the effluent pressure sensor, or both; and   a condenser pressure temperature sensor disposed along a refrigerant feed line providing a refrigerant flow to the overhead condenser, and a condenser effluent pressure sensor disposed along a refrigerant effluent flow line from the overhead condenser, and wherein the digital control system is configured to provide an alert based upon a pressure of the condenser effluent pressure sensor, a difference in pressure between the condenser feed pressure sensor and the condenser effluent pressure sensor, or both.   
     
     
         6 . The system of  claim 1 , wherein the closed loop refrigeration system comprises a compressor for compressing the refrigerant, wherein the one or more sensors comprise a sensor configured to measure a load on the turbine, and wherein the control system is configured to provide an alert when a turbine work load is indicative of leak. 
     
     
         7 . The system of  claim 1 , wherein the control system is configured to isolate the propane chiller when the one or more sensors are indicative of a leak in the propane chiller, and wherein the control system is configured to isolate the overhead condenser when the one or more sensors are indicative of a leak in the overhead condenser. 
     
     
         8 . A system for detecting leaks into a refrigeration system, the system comprising:
 a heat exchanger comprising a process side and a refrigerant side, the process side configured to operate at a higher pressure than the refrigerant side;   a refrigerant circulation system including:
 a refrigerant feed pipe fluidly connected to and configured to provide a refrigerant to an inlet of the refrigerant side of the heat exchanger; 
 a refrigerant effluent pipe fluidly connected to and configured to receive a refrigerant from an outlet of the refrigerant side of the heat exchanger; 
   one or more sensors configured to measure a property of the refrigerant;   a digital control system configured to provide an alert when a signal from at least one of the one or more sensors is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger.   
     
     
         9 . The system of  claim 8 , wherein the digital control system is further configured to isolate the heat exchanger when the signal is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger. 
     
     
         10 . The system of  claim 8 , wherein:
 the one or more sensors comprises a temperature sensor configured to measure a temperature of the refrigerant in the refrigerant circulation system; and   the digital control system is configured to provide an alert when a temperature indicated by the signal from the temperature sensor is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger.   
     
     
         11 . The system of  claim 8 , wherein:
 the one or more sensors comprises a pressure sensor configured to measure a pressure of the refrigerant in the refrigerant circulation system; and   the digital control system is configured to provide an alert when a pressure indicated by a signal from the pressure sensor is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger.   
     
     
         12 . The system of  claim 8 , wherein:
 the one or more sensors comprises a flow rate sensor configured to measure a flow rate of the refrigerant in the refrigerant circulation system; and   the digital control system is configured to provide an alert when a flow rate indicated by a signal from the flow rate sensor is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger.   
     
     
         13 . The system of  claim 8 , wherein the digital control system is configured to isolate the heat exchanger when a signal from at least one of the one or more sensors is indicative of a leak from the process side of the heat exchanger to the refrigerant side of the heat exchanger. 
     
     
         14 . A process for processing natural gas liquids, the process comprising:
 chilling a feed comprising acid gases, methane, ethane, and propane via indirect heat exchange with a refrigerant in a heat exchanger, wherein the feed is at a higher pressure than the refrigerant;   measuring a temperature, pressure and/or flow of refrigerant feed and effluent to and from the heat exchanger, respectively;   detecting a leak, automatically via a digital control system, based on a change or relative change in a measured temperature, pressure, or flow of refrigerant in the refrigerant loop upstream and/or downstream of the heat exchanger.   
     
     
         15 . The process of  claim 14 , further comprising isolating, automatically via the digital control system, the heat exchanger having the leak.