Synthesis gas method and apparatus

Abstract

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.

Description

FIELD OF THE INVENTION[0001]The present invention provides a method and apparatus for producing a synthesis gas product in which a hydrogen containing stream composed of a synthesis gas containing no more than 20 percent by volume methane is reacted with oxygen permeating through an oxygen transport membrane to generate heat to heat the membrane and support endothermic heating requirements of steam methane reforming reactions conducted in a separate catalytic reactor designed to produce the synthesis gas product.BACKGROUND OF THE INVENTION[0002]Synthesis gas containing hydrogen and carbon monoxide is produced for a variety of industrial applications, for example, the production of hydrogen, chemicals and synthetic fuel production. Conventionally, the synthesis gas is produced in a fired reformer in which natural gas and steam is reformed to the synthesis gas in catalyst filled reformer tubes. The endothermic heating requirements for steam methane reforming reactions occurring within...

AI Technical Summary

Benefits of technology

This approach results in a less complex and expensive system with reduced susceptibility to failure, as it uses less membrane area and allows for easier catalyst maintenance, while achieving the desired hydrogen-to-carbon monoxide ratio for synthetic fuel production.

Problems solved by technology

This is not optimal for the production of synthesis gas for synthetic fuel production such as in Fisher-Tropsch or methanol synthesis where a hydrogen to carbon monoxide ratio of 1.8 to 2.0 within the synthesis gas is more desirable.

As can be appreciated, conventional methods of producing a synthesis gas such as have been discussed above are expensive and complex installations.

Such carbon deposition will degrade reforming catalyst used in connection with the oxygen transport membrane reactor.

The problem with all of these systems is that an oxygen transport membrane will operate at high temperatures of about 900° C. to 1100° C. Where hydrocarbons such as methane and also higher order hydrocarbons are subjected to such temperatures carbon formation will occur.

As such, the oxygen is not generally available at the entrance to the reactor.

This also results in an aggravated carbon formation problem at the entrance that is especially the case at low steam-to-carbon ratios.

In any case, a reactant containing methane and steam will produce a relatively low oxygen flux across the membrane resulting in the membrane area required for such a reactor to be larger and it will add to the expense and complexity in such a reactor.

In prior art reactor designs where the catalyst is employed adjacent to the oxygen transport membrane, catalyst replacement becomes an expensive if not impractical exercise.

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