Synthesis gas method and apparatus
A method and apparatus for producing a synthesis gas product having one or more oxygen transport membrane elements thermally coupled to one or more catalytic reactors such that heat generated from the oxygen transport membrane element supplies endothermic heating requirements for steam methane reforming reactions occurring within the catalytic reactor through radiation and convention heat transfer. A hydrogen containing stream containing no more than 20 percent methane is combusted within the oxygen transport membrane element to produce the heat and a heated combustion product stream. The heated combustion product stream is combined with a reactant stream to form a combined stream that is subjected to the reforming within the catalytic reactor. The apparatus may include modules in which tubular membrane elements surround a central reactor tube.
1. A method for producing a synthesis gas product comprising:
contacting permeate and retentate sides of at least one oxygen transport membrane element configured to separate oxygen through oxygen ion transport with a hydrogen containing stream formed from a synthesis gas containing no more than 20 percent methane by volume and an oxygen containing stream, respectively;
reacting the hydrogen containing stream with the oxygen transported through the at least one oxygen transport membrane element, thereby generating heat, a heated reaction product stream and a heated retentate stream;
combining the heated reaction product stream with a reactant stream to form a combined stream comprising hydrocarbons contributed by the reactant stream and steam contributed at least by the heated reaction product stream;
reacting the hydrocarbons and steam contained in the combined stream in at least one catalytic reactor to produce a synthesis gas stream;
transferring the heat generated by the at least one oxygen transport membrane element to the at least one catalytic reactor by radiation from the at least one oxygen transport membrane element and by indirect heat transfer from the heated retentate stream to the at least one catalytic reactor to assist in supporting endothermic heating requirements of the steam methane reforming reaction; and
producing the synthesis gas product from at least part of the synthesis gas stream.
2. The method of claim 1 , wherein a supplementary steam stream is introduced into at least one of the hydrogen containing stream and the reactant stream.
3. The method of claim 1 , wherein a carbon dioxide stream is introduced into at least one of the heated reaction product stream, the reactant stream, the hydrogen containing stream and the combined stream.
4. The method of claim 1 , wherein the oxygen containing stream is preheated through indirect heat exchange with the heated retentate stream prior to being introduced to the retentate side of the at least one oxygen transport membrane.
5. The method of claim 1 , wherein the synthesis gas stream is divided such that the synthesis gas product is formed from the part of the synthesis gas stream and the hydrogen containing stream is formed from another part of the synthesis gas stream that is recycled to the permeate side of the at least one oxygen transport membrane element.
6. The method of claim 5 , wherein the synthesis gas stream is cooled at least in part by adding water or steam into the synthesis gas stream prior to dividing the synthesis gas stream.
7. The method of claim 6 , wherein a supplementary steam stream is introduced into at least one of the hydrogen containing stream and the reactant stream.
8. The method of claim 1 or claim 4 , wherein:
the at least one catalytic reactor has a polishing section heated by an auxiliary burner fired by a fuel thereby increasing equilibrium temperature at the outlet of the at least one catalytic reactor and reducing methane slip from the at least one catalytic reactor; and
the heated retentate supports combustion of the fuel within the auxiliary burner prior to preheating the oxygen containing stream.
9. The method of claim 1 , wherein:
the at least one catalytic reactor is at least one first catalytic reactor; and
the hydrogen containing stream is formed, at least in part, by reacting additional hydrocarbons and the further steam in the at least one second catalytic reactor.
10. The method of claim 9 , wherein the heat is also transferred to the at least one second catalytic reactor by radiation and indirect heat transfer from the heated retentate stream to supply the endothermic heating requirements for the reaction of the additional hydrocarbons and further steam.