Water gas shift process and apparatus for purifying hydrogen for use with fuel cells

摘要

A process and apparatus are disclosed for the operation of a compact water gas shift reactor for use in conjunction with fuel cell to generate electric power from a feed stream comprising a hydrocarbon or an alcohol. The fuel cell comprises a proton exchange membrane which produces electric power from a hydrogen product stream which comprises essentially no carbon monoxide. The hydrogen product stream may produced from the feed stream in a steam reforming of autothermal reforming zone. The compact water gas shift reactor comprises a vertically aligned vessel having a top end, a bottom end opposite, which defines an interior space. The interior space contains a first water spray zone for contacting a reforming effluent stream comprising hydrogen with a first water stream. A first dispersion zone is disposed below the first water spray zone and above a high temperature shift zone. The high temperature shift zone contains a high temperature shift catalyst to produce a high temperature shift effluent stream. A second water spray zone is disposed below the high temperature shift zone and above a second dispersion zone. A low temperature shift zone is disposed below the second dispersion zone. The low temperature shift zone contains a low temperature shift catalyst to produce a water saturated hydrogen product stream which comprises less than 50 ppm-mol carbon monoxide. The water dispersion zones simplify the overall shift reaction zone and provide protection for the shift catalysts from temperature shock.