Combustible gas detection system

Abstract

A system is provided for monitoring the levels of combustible gas in a gas stream. The system includes means for controlling the relative humidity of the gas stream and maintain a humidity level in the performance range of combustible gas sensors. A number of methods are illustrated for achieving the humidity control including secondary phase separations and the adjusting of the gas stream temperature.

1 . A system for generating hydrogen gas comprising: 
 an electrochemical cell stack;    a phase separator fluidly coupled to said electrochemical stack for receiving a water gas mixture;    a vent conduit fluidly connected and extending vertically from the top of said phase separator; and,    a combustible gas sensor coupled to said vent conduit.    
     
     
         2 . The system for generating hydrogen gas of  claim 1  wherein said vent conduit is metallic.  
     
     
         3 . The system for generating hydrogen gas of  claim 2  wherein said combustible gas sensor is electrically grounded to said vent conduit.  
     
     
         4 . The system for generating hydrogen gas of  claim 3  wherein said vent conduit further comprises an exhaust outlet.  
     
     
         5 . The system for generating hydrogen gas of  claim 4  wherein said combustible gas sensor is positioned adjacent to said exhaust outlet.  
     
     
         6 . A system for generating hydrogen gas comprising: 
 an electrochemical cell stack having and anode and electrode, said electrochemical cell stack further having at least one gas outlet and a means for electrolytically decomposing water to produce hydrogen gas;    a phase separator having a bottom and a top portion thereon, said phase separator being fluidly coupled to said electrochemical stack gas outlet for receiving a water gas mixture;    a vent conduit fluidly connected and extending from said phase separator top portion; and,    a catalytic bead type combustible gas sensor coupled to said vent conduit, said combustible gas sensor having sensing means for determining the lower explosive limit of gas within said vent conduit.    
     
     
         7 . The system for generating hydrogen gas of  claim 6  wherein said vent conduit comprises a body having a inlet fluidly coupled to said phase separator top portion, an outlet positioned at a body first end and perpendicular to said inlet, and a vent slot being positioned at a body second end opposite said outlet.  
     
     
         8 . The system for generating hydrogen gas of  claim 7  wherein said body is comprised of a housing portion mounted to a bracket portion, said bracket portion having a first and second flange wherein said body outlet is positioned in said first flange.  
     
     
         9 . The system for generating hydrogen gas of  claim 8  wherein said body is made from stainless steel.  
     
     
         10 . The system for generating hydrogen gas of  claim 7  wherein said combustible gas sensor is electrically connected to said vent conduit.  
     
     
         11 . The system for generating hydrogen gas of  claim 10  wherein said electrical connection is an electrical ground.  
     
     
         12 . The system for generating hydrogen gas of  claim 6  wherein said vent conduit further comprises an exhaust outlet.  
     
     
         13 . The system for generating hydrogen gas of  claim 12  wherein said sensing means is positioned adjacent to said exhaust outlet.  
     
     
         14 . A system for generating hydrogen gas comprising: 
 a water conduit;    an electrochemical cell stack having an inlet connected to said water conduit and a gas outlet, said cell stack further having a membrane electrode assembly comprising an anode and cathode with a solid membrane arranged in between, said membrane electrode assembly being arranged to allow electrolytic decomposion of water received from said water conduit to produce hydrogen gas wherein said hydrogen exits said gas outlet;    a phase separator having an inlet coupled to said cell stack outlet and a water outlet fluidly coupled to said water conduit, said phase separator further having a vent outlet arranged opposite said water outlet;    a vent conduit fluidly connected and extending from said phase separator vent outlet, said vent conduit having an inlet and an outlet being arranged perpendicular to said inlet; and,    a combustible gas sensor having a monitoring unit and a sensor unit, said sensor unit being operably coupled to said vent conduit.    
     
     
         15 . The system for generating hydrogen gas of  claim 14  wherein said sensor unit is mounted to said vent conduit opposite said vent conduit outlet.  
     
     
         16 . The system for generating hydrogen gas of  claim 15  wherein said sensor unit is a catalytic bead type sensor.  
     
     
         17 . The system for generating hydrogen gas of  claim 15  wherein said vent conduit is comprises: 
 a housing having an opening coupled to said phase separator vent outlet; and,    a bracket coupled to said housing and having a wall portion positioned opposite to and generally perpendicular to said housing opening.    
     
     
         18 . The system for generating hydrogen gas of  claim 17  wherein said housing has a pair of tabs extending therefrom, and said bracket has at least one pair of slots sized and positioned to receive said housing tabs.  
     
     
         19 . The system for generating hydrogen gas of  claim 18  wherein said bracket further includes a first and second flange extending perpendicular to said bracket wall portion, said first and second flanges being arranged on opposite ends of said bracket.  
     
     
         20 . The system for generating hydrogen gas of  claim 19  wherein said first flange has an opening sized to receive said sensor unit.