Reforming and Hydrogen Purification System

Abstract

A reforming and hydrogen purification system operating with minimal pressure drop for producing free hydrogen from different hydrogen rich fuels includes a hydrogen reforming catalyst bed in a vessel in communication with a core unit containing a hydrogen permeable selective membrane. The vessel is located within an insulated enclosure which forms an air inlet passageway and an exhaust passageway on opposite sides of the vessel. Air and raffinate pass through a burner within the air inlet passageway, providing a heated flue gas to heat the catalyst to the reaction temperature needed to generate free hydrogen from the feedstock. The burner flue gas flows laterally over and along the length of the bed between the input and output ends of the bed. Hydrogen is recovered from the core for use by a hydrogen-consuming device such as a fuel cell. The remaining unrecovered hydrogen in the reformed gases is contained in raffinate and is used to supply process heat via the burner. The exhaust flue gas and the inlet air supply pass through a recuperator in which the inlet air is heated from the hot exhaust gas. The feedstock input line is also coupled to the raffinate line and the hydrogen recovery line to preheat the feedstock prior to entry into the catalyst bed.

Description

BACKGROUND OF THE INVENTION[0001]The present invention is directed to a steam reformer for producing purified hydrogen including purified hydrogen for fuel cells.[0002]Purified hydrogen is an important commodity in semiconductor, metallurgical, and chemical processing. It is also highly useful as a source of fuel for fuel cells, which can produce electrical power from hydrogen. There are a variety of means for producing purified hydrogen. Hydrogen can be liberated from hydrogen-containing compounds such as alcohol by reforming with steam at elevated temperatures over a catalyst bed. Since this reaction is endothermic, the heat can be supplied from an external burner, or the heat can be supplied in-situ by mixing some oxygen and partially burning some of the fuel. The former process is generally called steam reforming; when air or oxygen is mixed with the fuel to supply heat the process is referred to as autothermal or partial oxidation reforming. Once the reforming process has been ...

AI Technical Summary

Benefits of technology

[0006]The present invention is particularly directed to a hydrogen purification reformer which may be constructed as a compact unit with efficient heating of the reformer from a burner. The burner gas has a minimal pressure drop in the system which results in a low power and low cost air supply for processing of the hydrogen rich fuel.

[0008]In accordance with a particular feature of this invention, a burner unit has a flue gas output stream communicating essentially directly from the burner unit to the catalyst unit and having a length substantially on the order of the length of the catalyst unit, i.e. typically the spacing between the catalyst unit's outlet and inlet. The flue gas stream thus passes laterally over substantially the entire length of the catalyst resulting in minimal air pressure drop in the system.

[0010]The preferred construction particularly provides for the efficient functioning of the catalyst and the heating of the catalyst, the feedstock and the air supply, as well as permitting use of a relatively low pressure air supply, yielding higher energy efficiency.

[0023]In addition, in one preferred construction, the flue gas from a catalytic burner unit downstream of the catalyst bed is coupled to an extended length of the input feedstock line, as by locating a coiled length thereof within the outlet passageway carrying the hot exhaust flue gas. This construction can be used to preheat the feedstock with the flue gas exhaust, which is particularly advantageous when using a catalytic burner.

[0027]Thus, the location and structure of the burner, and several heat recuperating systems have a linear orientation related to the pressure vessel. The capacity of the reforming system is then directly related to the linear length of the components in the final assembly resulting in efficient and ready scaling of hydrogen generation.

Problems solved by technology

The burner gas has a minimal pressure drop in the system which results in a low power and low cost air supply for processing of the hydrogen rich fuel.

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