The JM Davy/BP fixed-bed FT technology comprises a series of reaction vessels charged with a proprietary BP catalyst.
Syngas derived from a variety of hydrocarbon feedstocks is suitable for our fixed-bed FT process. JM Davy’s technologies for reforming natural gas to syngas include auto-thermal reforming, steam-methane reforming and compact reforming.
The FT converters are multiple single-pass tubular exchangers containing fixed beds of proprietary catalyst loaded in CANS. The reactant gasses pass through the tubes, making extensive contact with the catalyst. Products, by-products and unreacted syngas move down through the tubes and exit at the converter’s base.
Following pre-heating, the syngas enters the FT converter where H2 and CO react to form paraffinic compounds of various chain lengths:
The exit stream from the FT converter comprises:
- Heavy paraffin products (liquid)
- Light paraffin products (gas)
- Reaction water vapour
- Unreacted syngas
- Minor impurities
Separation of the heavy wax paraffins from the exit stream takes place immediately downstream of the reactor.
The remainder of the stream is gaseous. Cooling separates the light paraffin product and water vapour, leaving significant quantities of unconverted syngas. This stream is recycled back to the FT converter giving an overall conversion of 95%.
Product separation: The heavy liquid hydrocarbons exiting the FT converters collects in wax traps and proceeds to further processing. This ‘wax’ product is a solid at room temperature, with chain lengths of nC20 – nC100+.
The total light hydrocarbon and water by-product are separated in a decanter. The resulting liquid paraffin constitutes a majority of the hydrocarbon product, with chain lengths of nC5 – nC25.
Both the wax and liquid products are free from particulate contamination.
The water by-product contains dissolved gases and traces of light hydrocarbons and is normally recycled back to syngas production. This reduces overall feedstock demand and minimises the hydrocarbon load on the plant effluent treatment facility.