Glossary

  • 1-stage FT. An approach to the Fischer-Tropsch (FT) process where the reactants are passed through a single FT reactor before proceeding to the upgrading step of the GTL process. In the case of Velocys' single-stage FT, a portion of the gases exiting the reactor is returned as input to the same reactor to further increase the CO conversion without significantly increasing the capital expenditure
  • 2-stage FT. An approach to the Fischer-Tropsch (FT) process where the reactants are passed through two FT reactors in series to increase the CO conversion. This approach results in a significantly higher capital expenditure than the alternative single stage with recycle approach.
  • Alpha (α). The chain growth probability as defined by the Anderson–Schulz–Flory (ASF) model. This is the probability that a longer hydrocarbon chain is formed as a result of the Fischer-Tropsch (FT) reaction. This also describes the composition distribution of the FT products.
  • Associated gas. Natural gas produced along with crude oil; currently this is often flared, vented or reinjected into the oil reservoir.
  • ATR. Autothermal reforming. In this process methane gas is mixed with oxygen and passed over a catalyst to produce syngas, consisting of hydrogen and carbon monoxide, which is used as an input to the Fischer-Tropsch process.
  • Biomass. Materials produced from the processing of wood, corn, sugar and other agricultural waste or municipal waste. It can be converted to syngas via a gasification process.
  • BTL. Biomass-to-liquids. BTL is a process used to convert a wide variety of waste biomass, such as from the processing of wood, corn, sugar and other agricultural waste or municipal waste into hydrocarbons such as diesel and jet fuel. The biomass is converted first into syngas through a gasification process, followed by the Fischer-Tropsch process and subsequent hydrocracking step.
  • C5+ selectivity. The percentage of products with five or more carbon atoms. This is the valuable portion of the products produced by the Fischer-Tropsch process.
  • C5+ yield. The percentage of the carbon monoxide molecules in the feed gas that is converted into hydrocarbon molecules with five or more carbon atoms.
  • Catalyst. A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
  • CNG. Compressed natural gas is made by compressing natural gas, to less than 1% of the volume it occupies at standard atmospheric pressure. CNG is a competitor technology to GTL, but is only suitable where there is a local market for the gas.
  • CO conversion. The percentage of the carbon monoxide molecules in the gas feed that is converted into products as part of the Fischer-Tropsch process.
  • FT. The Fischer-Tropsch process. The process whereby syngas, consisting of a mixture of carbon monoxide and hydrogen, is converted into hydrocarbons over a catalyst. The range of products produced is broad; the raw product "syncrude" is mostly a paraffinic wax, which can be blended into crude oil or upgraded to a range of products which include diesel, jet fuel, naphtha and bases for synthetic lubricants and waxes.
  • Gasification. The process that converts carbon-containing materials into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam.
  • GTL. Gas-to-liquids. GTL is a process used to convert natural gas into longer-chain hydrocarbons such as diesel and jet fuel. Methane-rich gases are converted into liquid syngas (a mix of carbon monoxide and hydrogen) is produced using steam methane reforming or autothermal reforming, followed by the Fischer-Tropsch process. Hydrocracking is then used to produce finished fuels.
  • Hydrocracking. The process where long-chain hydrocarbon molecules are broken down (cracked) into molecules with shorter chains, which can then be used as e.g. fuels. The products of the FT process require a light hydrocracking step to produce diesel, jet fuel and naphtha.
  • Hydroprocessing. Any of several processes including hydrogenation, hydrocracking and hydrotreating, used to turn heavy hydrocarbons into lighter fractions through the catalytic addition of hydrogen at elevated pressures and temperature, and to remove pollutants like sulphur, nitrogen and heavy metals from refinery-derived fuel oils. Specifically in relation to GTL, the products of the FT process require a light hydrocracking step that partly isomerises the heavy waxes to produce products such as diesel, jet fuel and naphtha.
  • LNG. Liquefied natural gas is natural gas that has been converted to liquid form by cooling it to approximately −162 °C for ease of storage or transport. LNG is a competitor technology to GTL, but does not produce a drop-in fuel suitable for use in existing infrastructure or engines, as GTL does.
  • Microchannel reactors/process technology. Microchannel reactors are compact reactors that have channels with diameters in the millimeter range. The use of microchannel processing makes it possible to greatly intensify chemical reactions enabling them to occur at rates many times faster than in conventional systems.
  • Module. One of many repeating units in a process plant. This can refer either to the way the plant is structured, assembled and shipped (for example, a complete GTL plant can be constructed on steel-framed modules of 14m x 4m x 4m) or to an "operating module" – a bank of reactors and associated equipment. Typically a modular FT section will have anything from two to a dozen operating modules.
  • OMX. Organic Matrix Combustion method of catalyst manufacture. This is Velocys' patented method for producing highly active catalysts with high metal loadings, while still maintaining crystallite sizes for optimal activity and stability. The OMX method combines the metal salt and organic components to make a complex that effectively stabilises the metal.
  • SMR. Steam methane reforming. In this process methane is mixed with steam and passed over a catalyst to produce syngas consisting of hydrogen and carbon monoxide that is used as an input to the Fischer-Tropsch process.
  • Stranded gas. Natural gas reserves located at a distance from existing infrastructure such that they cannot be commercially exploited using existing technologies.
  • Super-active catalyst. A catalyst, such as one made by the Organic Matrix Combustion method, with significantly higher activity than conventional catalysts. It contains higher metal loadings, while still maintaining optimal crystallite sizes ensuring high activity and stability.
  • Syngas / synthesis gas. A mixture of carbon monoxide and hydrogen. Used as the feedstock for the Fischer-Tropsch process.
  • Upgrading. Any process that increases the value of hydrocarbon products. This includes hydroprocessing, hydrocracking, fractionation and any other catalytic or non-catalytic process which improves the value of the products. During upgrading, the products of the FT process are converted to diesel, jet fuel, naphtha or bases for synthetic lubricants and waxes.

 

 

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