Publication Date:
2017-07-21
Description:
The syngas production step is one of the most costly steps in a gas to liquid plant. It is common practice to use oxygen as oxidant in the reforming step. However, by the introduction of microchannel reactors with their remarkable heat transfer characteristics, high active catalyst site exposure to reactants and therefore high once-through conversions, the use of enriched-air maybe justified. The purpose of this paper is to analyze the merits of using enriched-air versus pure oxygen in the reforming step of a gas to liquid plant utilizing an autothermal reformer (ATR), while microchannel reactors are used in the once-through Fischer-Tropsch (FT) step. Pure oxygen is provided by a cryogenic Air Separation Unit (ASU) and enriched-air by use of air separation membranes. To make the two cases comparable, the total once-through CO conversion is kept the same. By using pure oxygen less FT reactor volume is required which means lower reactor cost at the expense of having a costly cryogenic ASU to produce pure oxygen. The operating cost of ASU is lower than air membrane, while its installed cost is higher. Due to safety and space issues of having a cryogenic ASU offshore, the only viable option is the use of enriched-air, while in an onshore setting, the use of oxygen is more attractive.
Print ISSN:
0930-7516
Electronic ISSN:
1521-4125
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
