Steam/carbon ratio detection and control

Abstract

Steam is provided to the primary inlet ( 16 ) of an ejector ( 13 ), which also receives natural gas at a secondary inlet ( 28 ). A computer responds to a signal ( 37 ) indicating current in the load of a fuel cell as well as a signal ( 43 ) indicating temperature of a steam reformer ( 10 ) to move a linear actuator ( 23 ) to control a needle ( 21 ) that adjusts the size of the steam orifice. Reformate is fed to a separator scrubber ( 48 ) which cools the reformate to its dew point indicated by a sensor ( 71 ). From that, a controller ( 25 ) generates the fuel/carbon ratio for display ( 84 ) and to bias a signal on a line ( 24 ) regulating the amount of steam passing through an ejector ( 13 ) to the inlet ( 11 ) of the reformer. Alternatively, the reformate may be cooled to its dew point by a controllable heat exchanger ( 58 a ) in response to pressure ( 94 ) and temperature ( 71 ) signals.

1 . A method comprising:
 providing a flow of steam to a primary inlet ( 16 ) of an ejector ( 13 );   providing a flow of hydrocarbon fuel to a secondary inlet ( 28 ) of said ejector;   providing effluent of said ejector to a steam reformer ( 11 );   cooling reformate from the steam reformer to its dew point in apparatus ( 46 ,  58 ;  58   a );   characterized by:   generating in a controller ( 25 ), a ratio signal indicative of the steam/carbon ratio of the cooled reformate as a function of the dew point of cooled reformate indicated by a sensor ( 71 ).   
     
     
         2 . A method according to  claim 1  further characterized by:
 presenting in a display ( 84 ) said steam/carbon ratio indicated by said ratio signal. 
 
     
     
         3 . A method according to  claim 1  further comprising:
 said controller ( 25 ) providing on a first line ( 24 ) a signal indicative of the amount of steam to be provided to said steam reformer ( 11 ) and providing on a second line ( 33 ), as a function of the signal on said first line, a signal indicative of the amount of fuel to be provided to said steam reformer; 
 further characterized in that: 
 said controller modifies the signals on said first and/or second lines as a function of said ratio signal. 
 
     
     
         4 . A method according to  claim 1  further characterized in that:
 said step of providing hydrocarbon fuel comprises providing natural gas. 
 
     
     
         5 . A method according to  claim 1  further characterized in that:
 said step of cooling comprises cooling the reformate in a separator scrubber ( 46 ) of an ammonia removal subsystem ( 49 ). 
 
     
     
         6 . A method according to  claim 1  further characterized in that:
 said step of cooling comprises cooling the reformate in a controllable heat exchanger ( 58   a ). 
 
     
     
         7 . A method comprising:
 providing a mixture of steam and hydrocarbon fuel to a steam reformer ( 10 );   cooling reformate flowing from said reformer to provide a reformate flow ( 69 ) cooled to its dew point;   characterized by:   providing a temperature signal ( 72 ) indicative of the dew point of the cooled reformate flow; and   adjusting the steam/carbon ratio of the mixture in response to the temperature signal.   
     
     
         8 . Apparatus comprising:
 a steam reformer ( 10 );   means ( 13 ,  23 ,  30 ) for providing a mixture of steam and hydrocarbon fuel to the steam reformer;   means ( 49 ,  58   a ) for cooling reformate flowing from said reformer to provide a reformate flow ( 69 ) cooled to its dew point;   characterized by:   means ( 71 ) for providing a temperature signal indicative of the dew point of the cooled reformate flow; and   means ( 25 ,  13 ,  23 ,  30 ) for adjusting the steam/carbon ratio of the mixture in response to the temperature signal.   
     
     
         9 . Apparatus comprising:
 means ( 15 ) for providing a flow of steam to a primary inlet ( 16 ) of an ejector ( 13 );   means ( 35 ) for providing a flow of hydrocarbon fuel to a secondary inlet ( 28 ) of said injector;   means ( 12 ) for providing effluent said ejector to a steam reformer ( 10 );   apparatus ( 49 ,  58   a ) for cooling reformate from the steam reformer to its dew point;   characterized by:   a controller ( 25 ) configured to generate a ratio signal indicative of the steam/carbon ratio of the cooled reformate as a function of the dew point of cooled reformate indicated by a sensor ( 71 ).   
     
     
         10 . Apparatus comprising:
 a controller ( 25 );   an ejector ( 13 ) configured to receive a flow of steam at a primary inlet ( 16 ) and a flow of hydrocarbon fuel at a secondary inlet ( 28 );   a steam reformer ( 10 ) configured to receive outflow of said ejector at an inlet ( 11 );   apparatus ( 48   a,    58   a ) configured to cool reformate from the reformer to its dew point;   a temperature sensor ( 71 ) providing to said controller a temperature signal ( 72 ) indicative of the dew point temperature of reformate;   characterized by:   said controller configured to generate in response to said temperature signal, a ratio signal indicative of the steam/carbon ratio of the reformate.   
     
     
         11 . Apparatus according to  claim 10  further characterized by:
 a display ( 84 ) configured to display the steam/carbon ratio indicated by said ratio signal. 
 
     
     
         12 . Apparatus according to  claim 10  wherein:
 said controller ( 25 ) is configured to provide on a first line ( 24 ) a signal indicative of the amount of steam to be provided to said steam reformer ( 10 ) and to provide on a second line ( 33 ), as a function of the signal on said first line, a signal indicative of the amount of fuel to be provided to said steam reformer; and 
 further characterized in that: 
 said controller is configured to modify the signal on said first and/or second lines as a function of said ratio signal. 
 
     
     
         13 . Apparatus according to  claim 10  further characterized in that:
 said ejector ( 13 ) is configured to receive natural gas at the secondary inlet ( 28 ). 
 
     
     
         14 . Apparatus according to  claim 10  further characterized in that:
 said apparatus is a separator scrubber ( 48 ) of an ammonia removal subsystem ( 49 ). 
 
     
     
         15 . Apparatus according to  claim 10  further characterized in that:
 said apparatus is a controllable heat exchanger ( 58   a ).