Catalytic Biogas Combined Heat and Power Generator

Abstract

An apparatus and method to desulfurize a biogas containing sulfur. Since biogas is produced by an anaerobic digester from human, animal, kitchen and agriculture's wastes, it is a short term recycled product from the photosynthesis of CO 2 , and has a net zero carbon emission. The sulfur compounds in the biogas can be removed by the following steps: (1) converting ail sulfur compounds into H 2 S by the hydrogen produced from the biogas over Pt group metal catalysts; (2) adsorbing the H 2 S at high temperature by the regenerable Pt group metal catalyst and adsorbents. The desulfurized biogas is further converted by an ATR/CPO reformer or a steam generating reformer to produce various reformates.

1 - 20 . (canceled) 
     
     
         21 . A method for operating a catalytic partial oxidation (CPO) desulfurization system, comprising:
 providing a biogas;   providing a catalytic partial oxidation (CPO) reformer;   creating an inlet fuel mixture by mixing the biogas with O 2  to adjust the inlet fuel mixture's O 2 /CH 4  ratio and H 2 O/CH 4  ratio;   delivering the biogas to the CPO reformer; and   reacting the biogas in the CPO reformer to create a reformate having a H 2 /CH 4  ratio, wherein the O 2 /CH 4  ratio of the inlet fuel mixture is adjusted to control the H 2 /CH 4  ratio in the reformate.   
     
     
         22 . The method of  claim 21 , comprising treating the biogas with a desulfurizer prior to creating the inlet fuel mixture. 
     
     
         23 . The method of  claim 22 , wherein the desulfurizer comprises one or more of a liquid wash, a filter, oxide adsorbents and regenerable supported Pt group metal catalysts. 
     
     
         24 . The method of  claim 21 , comprising producing the biogas using a fermentation process in the absence of oxygen. 
     
     
         25 . The method of  claim 21 , wherein the CPO reformer comprises Pt group catalysts. 
     
     
         26 . The method of  claim 21 , wherein reacting the biogas in the CPO reformer comprises converting sulfur in the biogas to H 2 S in the reformate. 
     
     
         27 . The method of  claim 26 , comprising removing the H 2 S from the reformate. 
     
     
         28 . The method of  claim 27 , wherein the H 2 S is removed using supported regenerable Pt group metal catalysts. 
     
     
         29 . The method of  claim 28 , wherein the H 2 S is removed at a temperature between 300° to 900° C. 
     
     
         30 . The method of  claim 28 , wherein the Pt group metal catalysts comprise one or more metals in the group of Pt, Pd, Rh, Ir, Ru, Os, and mixtures thereof, and are supported on stabilized Al 2 O 3 . 
     
     
         31 . The method of  claim 21 , wherein the reacting the biogas in the CPO reformer is done at an O 2 /C ratio of 0.05 to 0.25. 
     
     
         32 . The method of  claim 31 , wherein the reacting the biogas in the CPO reformer is done at a temperature between 200° to 800° C. 
     
     
         33 . The method of  claim 21 , comprising providing to an inlet of the CPO reformer a reactant mixture containing air or pure oxygen, water, and one or more fuels selected from the group consisting of a natural gas, a hydrocarbon and a biofuel for the purpose of controlling the H 2 /CH 4  ratio in the reformate by the O 2 /CH 4  ratio in the inlet feed mixture. 
     
     
         34 . The method of  claim 21 , comprising using the produced reformate from the reformer with a given H 2 /CH 4  ratio as a fuel to perform hydrogen assisted combustion by a downstream internal combustion engine/gas turbine. 
     
     
         35 . The method of  claim 34 , wherein the engine/gas turbine is connected to an electric generator to produce power as a distributed power station.