THERMOCHEMICAL CONVERSION: (CO)GASIFICATION AND HYDROTHERMAL GASIFICATION - Biomass as a Sustainable Energy Source for the Future - page 322

again needs to be ground or converted to slurry. Manufacturers of gasifier

types are Shell, Texaco, Krupp-Uhde, Future Energy (formerly Noell/Babcock
Borsig Power), ConocoPhillips (E-gas technology, formerly Destec/Dow), Mitsubishi
Heavy Industries (MHI), Hitachi, and Choren (formerly UET, now Linde-patented,
Germany).
Coal gasification was the initial application of the EF type of gasifier, in the 1950s
by Koppers. Koppers-Totzek slagging gasifiers operating at atmospheric pressure for
syngas production aimed at the production of ammonia (NH 3 ). The gasifier is char-
acterized by coal and oxygen being fed via pairs of opposed burners inside niches on
the side parts of a typically egg-shaped reactor. At the top part of the reactor, the pro-
duced raw syngas leaves the reactor at a maximum temperature of about 1500 C and is
rapidly cooled down (quenching) using water to a temperature of about 900 C; it is
then cooled down further in a syngas cooler in which steam is produced. Quenching is
crucial to prevent sticky slag droplets entering and depositing on the heat exchanger.
A steam jacket as reactor wall protects the steel from the high temperatures. The
produced slag mainly leaves the reactor via a bottom hole.
The PRENFLO and Shell Coal Gasification Process (SCGP) are processes
that have been developed later and are pressurized versions (3.0

“ slagging ”

4.0 MPa) of the
Koppers-Totzek process with a higher efficiency. They maintain the feature of
diametrically opposed burners inside side niches of the vertically mounted cylindrical
reactor. A gas quench has replaced the water quench.
Also, in these processes, membrane walls are applied instead of a steam jacket to
protect the pressure shell from too high temperatures. These walls are used for the
generation of high-pressure saturated steam for additional power production. Aimed
at power production, the developments led to the erection of a 2000 t

−

day −1 SCGP unit

day −1 PRENFLO unit in Puertollano
(Spain). Both gasifiers form the heart of an IGCC unit for electricity production.
The power-producing company NUON has demonstrated cofiring of coal with
chicken manure in the Buggenum plant up to about 30 wt% biomass share using
the (modified) Shell process-based 253 MW e plant for electricity production (see,
e.g., Van Dongen and Kanaar (2006)). The concept and reactor technology can be
extended to polygeneration of heat, power, and syngas-based chemicals.
The General Electric (GE)-owned Texaco gasification process is also of the EF type,
with the main difference being that the fuel is fed as a water slurry, whereas Koppers-
Totzek- and Shell-based coal gasifiers use steam. Future Energy GmbH developed a
down-firedEF reactor. Instead of burners inside of the reactor, this gasifier only consists
of a single burner in the top part, which results in a simpler and lower-cost reactor. Also,
the control of this single burner is easier than the other types mentioned with a resulting
lower capital and operational cost. The German company Choren developed a three-
stage gasification process involving the following subprocesses:

in Buggenum (the Netherlands) and a 3000 t

1. Low-temperature pyrolysis/gasification
2. High-temperature gasification
3. Endothermic EF gasification