Experimental study on liquid hydrocarbon formation during pressurized underground coal gasification conditions
Date
2018Author
Van Dyk, J.C.
Waanders, F.B.
Brand, J.F.
Nguyen, M.
Scheithauer, D.
Metadata
Show full item recordAbstract
UCG is a gasification process used to produce synthesis gas from coal in situ
(underground in the coal seam) by injecting air or oxygen, with or without steam, into
coal seams and extracting the product gas via surface wells. The resulting synthetic gas
(“syngas”) can be used to produce electricity, as well as chemicals, liquid fuels,
hydrogen and synthetic natural gas. Together with the resulting syngas, some of the coal
components, especially condensable water, oils, tars, inorganic trace elements and a
small fraction fly ash as particulate matter make its way to the surface via the production
well and can cause negative impacts on downstream processes. Tar and oil formation
during pressurised Underground Coal Gasification condition will be discussed in this
paper.
The project aims at generating and characterizing tar/oil (condensable hydrocarbon
fraction) from a South African Highveld coal sample under conditions that imitate the
pyrolysis stage of Underground Coal Gasification (UCG). For the generation of the
tar/oil fraction, a pressurized pyrolysis plant of the Institute of Energy Process
Engineering and Chemical Engineering at TU Bergakademie Freiberg is used.
The experimental equipment is a counter-current fixed bed reactor, in which the
preheated purge gas Argon and if necessary the previously generated steam is introduced
at the bottom of the reactor. The fixed bed is gradually building up during the
experiment as the feedstock is introduced from a storage tank via a screw feeding system
into the reactor. The system is electrically heated and can be operated at pressures up to
30 bars. The tar/oil fraction is collected within a condensation system, whereby a solvent
is used to remove the tar/oil from the condensers. Permanent gases are analysed after
pressure reduction.
To generated tar/oil under UCG conditions, the following conditions will be used:
Pressure: 30 bars
Superficial flow velocity: 0.05 m/s
Particle size: 2.0 - 6.3 mm
Temperature(s): 650 °C; 800 °C
Steam addition: 0 - 0. 15 kg/kg coal
The results from this study, both on quality and quantity, on the liquid hydrocarbon
formation during a UCG process will be discussed
URI
http://hdl.handle.net/10394/32966http://www.engineering.pitt.edu/Sub-Sites/Conferences/PCC/_Library/2018-Conference-Docs/2018-PCC-Abstract-Booklet/