System for extracting hydrogen from a gas containing methane

Abstract

A system for extracting hydrogen from a gas containing methane, especially natural gas. Hydrocarbons contained in the gas are catalytically broken down in a reformer by steam in order to form hydrogen, carbon monoxide and carbon dioxide. Catalytic conversion of the obtained carbon monoxide with steam occurs in a downstream conversion step in order to form carbon monoxide and water. Carbon dioxide is removed from the converted gas flow by gas washing, and the washed hydrogen-rich gas flow is subsequently divided in a pressure-swing adsorption system into a product gas flow made of hydrogen and a waste gas flow. The waste gas flow is introduced with hydrogen, which is separated from the gas flow after gas washing, into a reformer which is essentially a carbon-free combustible gas, and is combusted there.

1 . A system for extracting hydrogen from a gas that contains methane comprising:
 at least one reformer having a combustion chamber for catalytic splitting of gaseous hydrocarbons with steam;   a conversion stage having at least one conversion reactor for catalytic conversion of carbon monoxide to carbon dioxide and hydrogen, with steam;   a gas scrubber for separating carbon dioxide from the gas stream that leaves the conversion stage; and   a subsequent pressure swing absorption system for isolating hydrogen, to which a gas line that is passed back to the combustion chamber is connected, for firing the reformer with a gas stream that exits from the adsorption system,   wherein an additional device is provided for passing back part of the hydrogen-rich gas stream that leaves the gas scrubber into the combustion chamber of the reformer.   
     
     
         2 . The system according to  claim 1 , wherein the conversion stage comprises a conversion reactor operating at temperatures between 360 and 500° C. and a subsequent conversion reactor operating at temperatures between 210 and 270° C. 
     
     
         3 . The system according to  claim 1 , further comprising a purification stage for concentrating the separated carbon dioxide after the carbon dioxide exits the gas scrubber.