Method and apparatus for producing synthesis gas

A method of producing a synthesis gas product stream containing hydrogen and carbon monoxide comprising:

• reacting at least one hydrocarbon with the steam in steam methane reforming reactions conducted within separate reaction stages to produce the synthesis gas product stream;
• the reaction stages containing catalytic reaction zones within which the steam methane reforming reactions are conducted, combustion zones located adjacent to the reaction zones, separation zones located adjacent to the combustion zones and oxygen transport membrane elements located between the separation zones and the combustion zones;
• combusting a fuel within the combustion zones so that heat is provided to support endothermic heating requirements of the steam methane reforming reactions and operational temperature requirements of the oxygen transport membrane elements;
• introducing an oxygen containing gas into the separation zones and separating oxygen from the oxygen containing gas by oxygen ion transport occurring within the oxygen transport membrane elements, thereby to provide oxygen to support combustion of the fuel within the combustion zones;
• passing intermediate product streams produced through the steam methane reforming reactions sequentially through the reaction stages and discharging the synthesis gas product stream from a final of the reaction stages;
• and
• controlling temperature within each of the reaction stages by providing a sufficient number of the reaction stages such that at least the final of the reaction stages operates at a temperature range of between about 900° C. and about 1100° C. and at least one of the reaction stages, located upstream of the at least final reaction stage, has an operational temperature less than said temperature range due to the consumption of the heat in the endothermic reactions occurring within the at least one of the reaction stages.