Abstract:
A process for the integration of power generation and an SMR, including introducing a combustion air stream into a compressor, thereby producing a compressed air stream. The compressed air stream is then introduced, along with a combustor feed gas stream into a first combustor, thereby producing a first exhaust gas stream. The first exhaust gas stream is then introduced into the shell-side of an SMR, thereby providing the heat for the reforming reaction, and generating a syngas stream and a second exhaust gas stream. The second exhaust gas stream is introduced, along with a secondary fuel stream, into a second combustor, thereby producing a third exhaust gas stream. The third exhaust gas stream is then introduced into an expander, thereby producing power output and a fourth exhaust gas stream.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/039,470, filed Mar. 26, 2008, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]    Gas turbines are often located at synthesis gas production sites. It is typical for the fuel for both the gas turbine and the hydrocarbon containing reactant fed for the synthesis gas production to be natural gas. Where such installations exist, the gas turbines are not normally thermally linked to the synthesis gas production. In integrated gasification combined cycles, however, the gas turbine and the synthesis gas production are both thermally and operationally linked in that the fuel to the gas turbine is the synthesis gas and the synthesis gas is reheated through heat transfer with the synthesis gas stream being produced. 
         [0003]    In the present invention the gas turbine is combined with the SMR to generate power, hydrogen, and steam. This cogeneration scheme improves overall thermal efficiency of the process. It reduces the amount of by-product steam. The hydrogen generation is done in an exchanger type of reactor that is much more compact as compared to a conventional SMR furnace 
       SUMMARY  
       [0004]    A process for the integration of power generation and an SMR, including introducing a combustion air stream into a compressor, thereby producing a compressed air stream. The compressed air stream is then introduced, along with a combustor feed gas stream into a first combustor, thereby producing a first exhaust gas stream. The first exhaust gas stream is then introduced into the shell-side of an SMR, thereby providing the heat for the reforming reaction, and generating a syngas stream and a second exhaust gas stream. The second exhaust gas stream is introduced, along with a secondary fuel stream, into a second combustor, thereby producing a third exhaust gas stream. The third exhaust gas stream is then introduced into an expander, thereby producing power output and a fourth exhaust gas stream. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0005]    The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, and in which: 
           [0006]      FIG. 1  is a schematic representation of one embodiment of the present invention. 
           [0007]      FIG. 2  is a schematic representation of another embodiment of the present invention. 
           [0008]      FIG. 3  is a schematic representation of one embodiment of the present invention. 
           [0009]      FIG. 4  is a schematic representation of another embodiment of the present invention. 
           [0010]      FIGS. 1   a - 4   a  are schematic representations of another embodiment of the present inventions, as described in  FIGS. 1-4 . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0011]    Turning now to  FIG. 1 , combined SMR and cogeneration system  100  is provided. Combustion air stream  101  is introduced to air compressor  102 , where it is compressed and exits as compressed air stream  103 . Natural gas stream  104  introduced into natural gas pre-heater  105 , where it exits as heated natural gas stream  106 . Natural gas stream  104  may be purified if necessary. Heated natural gas stream  106  is divided into at least two portions, combustor feed gas stream  107  and SMR feed gas stream  108 . Combustor feed gas stream  107  is combined with compressed air stream  103  in first combustor  109 , where it is combusted, thereby generating first exhaust gas stream  110 . First exhaust gas stream  110  may have a temperature of between about 2000 F. and about 2200 F. Steam stream  111 , is combined with SMR feed gas stream  108 , to form combined feed stream  112 . Combined feed stream  112  is further preheated in a mixed feed preheater section of waste heat boiler  128  (shown in  FIG. 1   a ). Preheated combined feed stream  124  is introduced into SMR  113 , where it exits as syngas stream  119 . Syngas stream  119  may have a temperature of between about 1200 F. and about 1600 F. In one embodiment, SMR  113  may be of the type known as an exchanger type, which has no burners to supplement the heat content of first exhaust gas stream  110 . In another embodiment, SMR  113  may have burners (not shown) to supplement the heat content of first exhaust gas stream  110 , as needed. First exhaust gas stream  110  is introduced into the shell-side of SMR  113 , where it provides the heat required for the steam reforming process, then exiting as second exhaust gas stream  114 . Syngas stream  119  is introduced into filter  120 , where it is separated into hot hydrogen product stream  121  and secondary fuel stream  122 . Filter  120  may be a ceramic or metallic separator. Secondary fuel stream  122  may contain one or more of the following, unconverted methane, unrecovered H2, CO, CO2, and unused steam. The metallic separator may utilize palladium. Second exhaust gas stream  114  is combined with secondary fuel stream  122  in second combustor  115  where it is combusted, thereby generating third exhaust gas stream  116 . Third exhaust gas stream  116  is introduced into expander  117 , where it is expanded and exits as fourth exhaust gas stream  118 . Fourth exhaust gas stream  118  may have a temperature of between about 800 F. and about 1100 F. Fourth exhaust gas stream  118  is used for preheating mixed feed stream  112 , and for generating steam. Boiler feed water stream  125  is introduced into waste heat boiler  128 , wherein it is heated, vaporized, and superheated into steam stream  126 . Steam stream  126  may be used to feed the SMR (stream  111 ), with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown). 
         [0012]    Hot hydrogen product stream  121  is then introduced into natural gas pre-heater  105 , where indirectly exchanges heat with natural gas stream  104 , exiting as  15  cooled hydrogen product stream  123 . In another embodiment, the heat from hot hydrogen stream  121  may be used for preheating BFW. 
         [0013]    In one embodiment, air compressor  102  and expander  117  may be mechanically attached. In another embodiment, the power required for air compressor  102  is at least partially provided by the power generated by expander  117 . In another embodiment, the power required for air compressor  102  is completely provided by the power generated by expander  117 . 
         [0014]    The above described process can be optimized by one skilled in the art, depending upon the particular power, steam and hydrogen products requirements. At least the following variables are available for optimization, with the skilled artisan recognizing that other aspects of the proposed invention may also be manipulated to yield further optimized results. 
         [0015]    The amount of natural gas that is sent to SMR (stream  108 ) may be varied to optimize the system. This parameter affects the amount of heat that is used for reforming. The amount of hydrogen that is made in SMR increases when more natural gas is reformed. However increasing the natural gas into the SMR reduces the amount of power that is produced in expander  117 , as the exhaust gas temperature (streams  114  and  116 ) is reduced. 
         [0016]    The steam to natural gas ratio may be varied to optimize the system. If the steam to natural gas ratio is increased, the amount of hydrogen that is produced increases. The excess steam that is not used in the reforming of methane will ultimately be sent to expander  117 , which will result in increased power production. The desired minimum molar ratio of steam to methane is about 2.0. 
         [0017]    SMR  113  contains a catalyst to assist the steam reforming of methane. The catalyst may be in the shape of pellets, granular, tablets etc. The catalyst can also be in the form of a coated monolith or coated tube surface. The catalysts using nickel or noble metals are commercially available. 
         [0018]    Hot hydrogen product stream  121 , as permeate from the filter  120  is hot and may be at low pressure of less than 50 psig. Heat is recovered from this stream and the product hydrogen is compressed to desired pressure. 
         [0019]    The use of heat for hydrogen production improves the efficiency of power generation and hydrogen generation. 
         [0020]    This processing scheme differs from the prior art in a number of respects. First the instant process uses higher level heat, upstream of expander  117 , for reforming. Second the hot gases that are used in the reforming exchanger are at high pressure, thereby reducing the size of the reforming exchanger. Third the proposed process recovers hydrogen from the reformed gas mixture. Fourth the proposed process removes hydrogen from the gas mixture at elevated temperature, thereby allowing the use of hot residue gas fuel. 
         [0021]    Turning now to  FIG. 2 , combined SMR and cogeneration system  200  is provided. Combustion air stream  201  is introduced to air compressor  202 , where it is compressed and exits as compressed air stream  203 . Natural gas stream  204  introduced into natural gas pre-heater  205 , where it exits as heated natural gas stream  206 . Natural gas stream  204  may be purified if necessary. Heated natural gas stream  206  is divided into at least two portions, combustor feed gas stream  207  and SMR feed gas stream  208 . Combustor feed gas stream  207  is combined with compressed air stream  203  in combustor  209 , where it is combusted, thereby generating first exhaust gas stream  210 . First exhaust gas stream  210  is introduced into expander  217 , where it is expanded and exits as second exhaust gas stream  221 . Steam stream  211 , is combined with SMR feed gas stream  208 , to form combined feed stream  212 . Combined feed stream  212  is further preheated in a mixed feed preheater section of waste heat boiler  225  (shown in  FIG. 2   a ). Preheated combined feed stream  226  is then introduced into SMR  213 , where it exits as syngas stream  215 . Second exhaust gas stream  221  is introduced into the shell-side of SMR  213 , where it provides the heat required for the steam reforming process, then exiting as third exhaust gas stream  214 . Third exhaust gas stream  214  is used for preheating mixed feed stream  212 , and for generating steam. Boiler feed water stream  222  is introduced into waste heat boiler  225 , wherein it is heated, vaporized, and superheated into steam stream  223 . Steam stream  223  may be used to feed the SMR (stream  211 ), with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown). 
         [0022]    In one embodiment, SMR  213  may be of the type known as an exchanger type, which has no burners to supplement the heat content of first exhaust gas stream  203 . In another embodiment, SMR  213  may have burners (not shown) to supplement the heat content of first exhaust gas stream  221 , as needed. Syngas stream  215  is introduced into filter  216 , where it is separated into hot hydrogen product stream  217  and secondary fuel stream  218 . Filter  216  may be a ceramic or metallic separator. Secondary fuel stream  218  may contain one or more of the following, unconverted methane, unrecovered H2, CO, CO2, and unused steam. The metallic separator may utilize palladium. Hot hydrogen product stream  217  is then introduced into natural gas pre-heater  205 , where indirectly exchanges heat with natural gas stream  204 , exiting as cooled hydrogen product stream  220 . 
         [0023]    In one embodiment, air compressor  202  and expander  217  may be mechanically attached in another embodiment, the power required for air compressor  202  is at least partially provided by the power generated by expander  217 . In another embodiment, the power required for air compressor  202  is completely provided by the power generated by expander  217 . In one embodiment, third exhaust gas stream  214  may be used for preheating natural gas, preheating a mixed feed to the SMR, for generating steam, or any combination thereof. In one embodiment, the steam that is generated is used to feed the SMR, with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown). 
         [0024]    Turning now to  FIG. 3 , combined SMR and cogeneration system  300  is provided. Combustion air stream  301  is introduced to air compressor  302 , where it is compressed and exits as compressed air stream  303 . Natural gas stream  304  introduced into natural gas pre-heater  305 , where it exits as heated natural gas stream  306 . Natural gas stream  304  may be purified if necessary. Heated natural gas stream  306  is divided into at least two portions, combustor feed gas stream  307  and SMR feed gas stream  308 . Combustor feed gas stream  307  is combined with compressed air stream  303  in first combustor  309 , where it is combusted, thereby generating first exhaust gas stream  310 . First exhaust gas stream  310  is introduced into first expander  331 , where it is expanded and exits as second exhaust gas stream  332 . Steam stream  311 , is combined with SMR feed gas stream  308 , to form combined feed stream  312 . Combined feed stream  312  is further preheated in a mixed feed preheater section of waste heat boiler  336  (shown in  FIG. 3   a ). Preheated combined feed stream  337  is introduced into SMR  313 , where it exits as syngas stream  315 . In one embodiment, SMR  313  may be of the type known as an exchanger type, which has no burners to supplement the heat content of fourth exhaust gas stream  323 . In another embodiment, SMR  313  may have burners (not shown) to supplement the heat content of fourth exhaust gas stream  323 , as needed. Fourth exhaust gas stream  323  is introduced into the shell-side of SMR  313 , where it provides the heat required for the steam reforming process, then exiting as fifth exhaust gas stream  314 . Fifth exhaust gas stream  314  is used for preheating mixed feed stream  312 , and for generating steam. Boiler feed water stream  333  is introduced into waste heat boiler  336 , wherein it is heated, vaporized, and superheated into steam stream  334 . Steam stream  334  may be used to feed the SMR (stream  311 ), with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown). 
         [0025]    Syngas stream  315  is introduced into filter  316 , where it is separated into hot hydrogen product stream  317  and secondary fuel stream  318 . Filter  316  may be a ceramic or metallic separator. Secondary fuel stream  318  may contain one or more of the following, unconverted methane, unrecovered H2, CO, CO2, and unused steam. The metallic separator may utilize palladium. Secondary fuel stream  318  is introduced into second expander  319 , where it is expanded and exits as expanded secondary fuel gas stream  320 . Second exhaust gas stream  332  is combined with expanded secondary fuel stream  320  in second combustor  322  where it is combusted, thereby generating fourth exhaust gas stream  323 . Hot hydrogen product stream  317  is then introduced into natural gas pre-heater  305 , where indirectly exchanges heat with natural gas stream  304 , exiting as cooled hydrogen product stream  324 . 
         [0026]    In one embodiment, air compressor  302  and first expander  331  may be mechanically attached. In another embodiment, the power required for air compressor  302  is at least partially provided by the power generated by at least one of first expander  331  and second expander  319 . In another embodiment, the power required for air compressor  302  is completely provided by the power generated by expander  331 . In one embodiment, fifth exhaust gas stream  314  may be used for preheating natural gas, preheating a mixed feed to the SMR, for generating steam, or any combination thereof. In one embodiment, the steam that is generated is used to feed the SMR, with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown). 
         [0027]    Turning now to  FIG. 4 , combined SMR and cogeneration system  400  is provided. Combustion air stream  401  is introduced to air compressor  402 , where it is compressed and exits as compressed air stream  403 . Natural gas stream  404  introduced into natural gas pre-heater  405 , where it exits as heated natural gas stream  406 . Natural gas stream  404  may be purified if necessary. Heated natural gas stream  406  is divided into at least two portions, combustor feed gas stream  407  and SMR feed gas stream  408 . Combustor feed gas stream  407  is combined with compressed air stream  403  in first combustor  409 , where it is combusted, thereby generating first exhaust gas stream  410 . First exhaust gas stream  410  is introduced into expander  420 , where it is expanded and exits as second exhaust gas stream  421 . Steam stream  411 , is combined with SMR feed gas stream  408 , to form combined feed stream  412 . Combined feed stream  412  is further preheated in a mixed feed preheater section of waste heat boiler  428  (shown in  FIG. 4   a ). Preheated combined feed stream  429  is introduced into SMR  413 , where it exits as syngas stream  415 . In one embodiment, SMR  413  may be of the type known as an exchanger type, which has no burners to supplement the heat content of fourth exhaust gas stream  424 . In another embodiment, SMR  413  may have burners (not shown) to supplement the heat content of fourth exhaust gas stream  424 , as needed. Fourth exhaust gas stream  424  is introduced into the shell-side of SMR  413 , where it provides the heat required for the steam reforming process, then exiting as fifth exhaust gas stream  414 . Fifth exhaust gas stream  414  is used for preheating mixed feed stream  412 , and for generating steam. Boiler feed water stream  425  is introduced into waste heat boiler  428 , wherein it is heated, vaporized, and superheated into steam stream  426 . Steam stream  426  may be used to feed the SMR (stream  411 ), with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown). 
         [0028]    Syngas stream  415  is introduced into natural gas pre-heater  405 , where indirectly exchanges heat with natural gas stream  404 , exiting as cooled syngas stream  416 . In one embodiment, cooled syngas stream  416  is at approximately ambient temperature. In another embodiment, cooled syngas stream  416  is at approximately 10 degrees warmer than ambient temperature. Cooled syngas stream  416  is introduced into PSA  417 , where it is separated into hydrogen product stream  418  and secondary fuel stream  419 . Secondary fuel stream  419  may contain one or more of the following, unconverted methane, unrecovered H2, CO, CO2, and unused steam. Secondary fuel stream  419  may be at a pressure of between about 2 psig and about 20 psig. Second exhaust gas stream  421  is combined with secondary fuel stream  419  in second combustor  423  where it is combusted, thereby generating fourth exhaust gas stream  424 . 
         [0029]    In one embodiment, air compressor  402  and expander  420  may be mechanically attached. In another embodiment, the power required for air compressor  402  is at least partially provided by the power generated by expander  420 . In another embodiment, the power required for air compressor  402  is completely provided by the power generated by expander  420 . In one embodiment, fifth exhaust gas stream  414  may be used for preheating natural gas, preheating a mixed feed to the SMR, for generating steam, or any combination thereof. In one embodiment, the steam that is generated is used to feed the SMR, with any remaining steam being available for exportation, or for power generation in a steam turbine (not shown).