Patent Publication Number: US-2011073809-A1

Title: Reduction Of CO2 Emissions From A Steam Methane Reformer And/Or Autothermal Reformer Using H2 As A Fuel

Description:
BACKGROUND 
     Steam methane reformers (SMR) and autothermal reformers (ATR) emit CO 2  when used for producing hydrogen or syngas. Part of the CO 2  emitted is due to hydrocarbons used as fuel for the steam methane reformer. CO 2  emissions are being regulated and/or taxed in some areas of the world. The regulations/taxes will increase the cost of hydrogen and/or syngas, or the regulations may forbid building new SMRs for hydrogen or syngas production. It is possible to capture the CO 2  from the flue gas, but this is difficult and expensive. For existing plants, physical constraints may make adding the process for capture impossible. 
     SUMMARY 
     The present invention is a method for reducing carbon dioxide emissions from a reforming process. This method includes producing a hot crude syngas stream in a reformer; indirectly exchanging heat between said hot crude syngas stream and a process stream, thereby generating a cool crude syngas stream; and introducing said cool crude syngas stream into a first separation means, thereby producing a syngas stream and a fuel hydrogen stream. The present invention also includes introducing said syngas stream into a second separation means, thereby producing a product syngas stream, and a carbon dioxide rich stream; blending said fuel hydrogen stream with a hydrocarbon stream, thereby producing a blended fuel stream; and introducing said blended fuel stream into a reformer, thereby generating an exhaust stream that has a lower percentage of carbon dioxide than it would without the introduction of said fuel hydrogen stream. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic representation of one embodiment of the present invention. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention would use a portion of the product H2 as the fuel or part of the fuel to reduce CO 2  emissions from an SMR or ATR. When H2 is burned it produces no CO2. Capturing CO2 from the process side (the area where H2 or syngas is formed) of an SMR or ATR is cheaper and easier than capturing CO2 in the flue gas. Further, since capture on the process side is already required for CO2 emission reduction, using part of the produced H2 would not greatly increase the cost of equipment or complexity of the plant. 
     Turning now to  FIG. 1 , system  100  is presented. Reformer feed stream  101  is introduced into the catalyst tubes of reformer unit  102 . Hydrocarbon stream  104  is blended with fuel hydrogen stream  114 , thereby producing blended fuel stream  105 . Reformer unit  102  may be a Steam Methane Reformer (SMR) or an Autothermal Reformer (ATR). Blended fuel stream  105  is introduced, with combustion oxidant stream  103 , into the shell side of reformer  102 , where they are combusted thereby providing the temperature and heat required for the reforming process. The products of this combustion exits the shell side of reformer  102  as exhaust stream  106 . 
     Reformer feed stream  101  is converted into hot crude syngas stream  107 , which exits reformer  102  and is introduced into process cooling section  108 . Within the process cooling section  108 , hot crude syngas stream  107  indirectly exchanges heat with cold boiler feed water stream  109 , thereby producing heated stream  110 , and with the syngas stream exiting as cool crude syngas stream  111 . Cool crude syngas stream  111  is then introduced into first separation means  112 , where it is separated into syngas stream  113 , and fuel hydrogen stream  114 . First separation means  112  may be a pressure swing adsorber, a membrane-type separator, or a cryogenic-type separator. Syngas stream is then introduced into second separation means  115 , where it is separated into product syngas stream  116 , and carbon dioxide rich stream  117 . Second separation means  115  may be a pressure swing adsorber, a membrane-type separator, or a cryogenic-type separator. If reformer  102  is an ATR, carbon dioxide rich stream  117  may be blended with fuel gas, and optionally steam, to produce reformer feed stream  101 .