Desulfurization system and method for desulfurizing a fuel stream

Abstract

A method for producing a substantially desulfurized hydrocarbon fuel stream at temperatures less than 100° C. including providing a nondesulfurized fuel cell hydrocarbon fuel stream and passing the fuel stream through a sequential sulfur adsorbent system containing calcium exchanged zeolite, hydrated alumina and a selective sulfur adsorbent placed in sequence to produce a substantially desulfurized hydrocarbon fuel stream.

Description

CROSS REFERENCED TO RELATED APPLICATIONS [0001] This application is a continuation-in-part application based on application Ser. No. 11 / 207,154, filed on Aug. 18, 2005, which is a continuation-in-part application based on application Ser. No. 10 / 923,177, which was filed on Sep. 1, 2004.BACKGROUND OF INVENTION [0002] The present invention relates to a novel method for producing a substantially desulfurized hydrocarbon fuel stream, particularly for hydrogen generation, and more particularly for use within a fuel cell processing train, by passing a nondesulfurized hydrocarbon fuel stream, particularly natural gas, propane or liquefied petroleum gas (LPG), through a sequential sulfur adsorbent system at temperatures less than 100° C., wherein the sequential sulfur adsorbent system contains in sequence a zeolite sulfur adsorbent, a hydrated alumina adsorbent, and a selective sulfur adsorbent. The present invention further relates to a process for producing hydrogen within a fuel cell pro...

AI Technical Summary

Benefits of technology

[0015] A further invention is a sequential sulfur adsorbent system, particularly for hydrogen generation and most particularly for use in a fuel cell processing train, comprising, in sequence, a calcium exchanged zeolite, a hydrated alumina adsorbent, and a selective sulfur adsorbent. The choice of the specific selective sulfur adsorbent that is used within the sequential sulfur adsorbent system depends upon the composition and quantity of the sulfur compounds that are present in the hydr...

Problems solved by technology

Unfortunately, virtually all raw fuels of this type contain relatively high levels, up to as high as 1,000 ppm or so, but typically in the range of 20 to 500 ppm, of various naturally occurring sulfur compounds, such as, but not limited to, carbonyl sulfide, hydrogen sulfide, thiophenes, such as tetra hydro thiophene, dimethyl sulfide, various mercaptans, disulfides, sulfoxides, other organic sulfides, higher molecular weight organic sulfur compounds, and combinations thereof.

The presence of sulfur-containing compounds, particularly carbonyl sulfide, in a hydrocarbon fuel stream can be very damaging to components of the fuel cell processing train, including the fuel cell stack itself, and such compounds must therefore be substantially removed.

If not substantially removed, the sulfur compounds may shorten the life expectancy of the components of the fuel cell processing train.

Further, desulfurization systems for such uses must have high capacity, as they may need to be in use for an extended period of time before replacement.

In addition, there are often limits on the quantity of sulfur compounds which can be adsorbed by such physical sulfur adsorbents.

In addition, other operational problems may occur when such chemical desulfurization processes are utilized.

Breakthrough by virtually any of the sulfur compounds present in the hydrocarbon fuel stream is disadvantageous as substantially all sulfur compounds can cause damage to components of a hydrogen generation system, particularly for a fuel cell processing train.

Further, some sulfur compounds, particularly carbonyl sulfide, are quite difficult to remove from such fuel streams, especially without the addition of hydrolyzing agents.

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