Oxford Catalysts advances shale gas technology
16 Jun 2011
Oxford, UK – Small scale gas to liquids (GTL) facilities based on the use of microchannel Fischer-Tropsch (FT) reactors and designed for use on offshore platforms are exciting interest as a means to turn associated gas into an energy asset and to make wasteful flaring and expensive re-injection of gas a thing of the past.
According to Oxford Catalysts, a major exploration and production company is seriously considering the possibility of incorporating microchannel FT reactors into a planned 5,000 -15,000 barrel per day (bpd) GTL facility. The onshore unit, in North America, is designed to convert shale gas into finished synthetic fuels.
Microchannel FT reactors developed by US-based Velocys Inc., part of the Oxford Catalysts group, claims to have one of a few technology options earmarked for closer examination for use in the GTL facility.
The shortlisted technologies will be subjected to further evaluation as part of a major high-budget engineering study that will last for several months. The results of the study will be used to select the project’s technology providers.
Microchannel FT reactors developed by Velocys and using a new highly active FT catalysts developed by Oxford Catalysts exhibit conversion efficiencies in the range of 70% per pass, according to Jeff McDaniel, Oxford Catalysts director of commercialisation.
“The high efficiency and modular nature of our microchannel FT reactors makes them particularly useful for this type of application because capacity can be easily increased by simply ’numbering up’ or linking together additional FT reactor modules,” said McDaniel.
Shale Gas
Shale gas – natural gas production from hydrocarbon-rich shale formations – is one of the most rapidly expanding trends in onshore oil and gas exploration and production today. Shale gas has become an increasingly important source of natural gas in the United States in recent years and interest has spread to potential gas shales in Canada, Europe, Asia, and Australia. The US Department of Energy estimates that in 2011 the major souce of gas reserves growth will come from unconventional shale gas reservoirs.
The growth in shale gas production has been encouraged by a combination of rapid increases in natural gas prices and advances in technologies such as hydraulic fracturing to create extensive artificial fractures around well bores, and horizontal drilling to increase the borehole surface area in contact with the shale.
The GTL Process
The GTL process involves two operations: steam methane reforming (SMR), followed by Fischer-Tropsch (FT) synthesis and product upgrading, or hydrocracking. In SMR the methane gas is mixed with steam and passed over a catalyst to produce a syngas consisting of hydrogen (H2) and carbon monoxide (CO). The reaction is highly endothermic, so requires the input of heat. This can be generated by the combustion of the excess H2 and methane. In microchannel SMR reactors the heat-generating combustion and steam methane reforming processes take place in adjacent channels. The high heat transfer properties of the microchannels make the process very efficient.
These same heat transfer properties offer different advantages for the highly exothermic FT reaction. Microchannel FT reactors consist of reactor blocks containing thousands of thin process channels filled with FT catalyst, which are interleaved with water-filled coolant channels. As a result they are able to dissipate the heat produced by the FT reaction much more quickly than conventional systems, so more active FT catalysts can be used.
Microchannel reactors
Microchannel reactors are compact reactors that have channels with diameters in the millimetre range. The small diameter channels dissipate heat more quickly than conventional reactors with larger channel diameters in the 2.5 – 10 cm (1 – 4 inch) range so more active catalysts can be used. Mass and heat transfer limitations reduce the efficiency of the large conventional high pressure reactors used for hydroprocessing. The use of microchannel processing will make it possible to greatly intensify chemical reactions to enable them to occur at rates 10 to 1000 times faster than in conventional systems.
