Gas to Liquids
Using economically produced UCG syngas in the Gas to Liquids (GTL) process represents an exciting business opportunity for Linc Energy.
Linc Energy’s unique combination of UCG and GTL technologies can be commercialised in locations where there is suitably deep coal for UCG technology.
How GTL works
GTL is the process of converting a gas to a liquid. In Linc Energy’s case, syngas is produced via UCG very economically and can be converted into highly valuable intermediary and final products.
GTL is the term used to describe the chemical conversion of a gas into synthetic crude (syncrude) by the Fischer-Tropsch synthesis process. The syncrude is then refined by traditional methods to produce ultra-clean liquid transport fuels.
As a feedstock, the process uses syngas generated from the gasification of solid, liquid or gaseous carbon rich materials, such as coal or natural gas. Linc Energy is planning to use syngas from UCG to commercially produce liquids using GTL.
The following three main steps comprise Linc Energy’s GTL process:
- Gas treatment: removes impurities from the UCG syngas
- Fischer-Tropsch synthesis: produces syncrude through catalytic reactions
- Product work-up and refining: separates liquids and waxes and refines into final products
Gas treatment
Coal derived syngas (such as UCG syngas) contains various impurities that must be removed to meet specifications to run an efficient GTL plant.
Some impurities act as poisons to catalytic reactions in the GTL process, reducing the efficiency of the process. Such impurities include condensed oils, solid particles, arsenic, mercury, oxygen, sulphur compounds and carbon dioxide. These originate from the coal itself or its gasification. Impurities are removed from the gas and their absence enables high conversion to liquid fuels over a prolonged period.
On the completion of gas treatment, the syngas is free of impurities and is rich in hydrogen and carbon monoxide, which are the basic elements needed to manufacture syncrude.
Fischer-Tropsch synthesis
All saturated liquid fossil fuels are a chain of carbon molecules with single bond hydrogen molecules attached. The longer the carbon chain, the heavier the product. The hydrocarbons with the shortest carbon chains are gases like propane, ethane and methane, and the heaviest hydrocarbons are solids like tars and pitch.
Fischer-Tropsch synthesis combines carbon and hydrogen molecules into chains by reacting carbon monoxide with hydrogen in the presence of a metal catalyst, heat and pressure.
Product work-up and refining
The syncrude product from the Fischer-Tropsch synthesis is refined or upgraded into higher value end products through traditional and syncrude specific refining processes. The product range depends on the Fischer-Tropsch technology, process conditions and the refinery scheme or setup. New generation GTL plants are aimed primarily at producing middle distillates for transportation fuels, e.g. diesel, kerosene and naphtha.For more information, click here.