Pan European Networks - Government - page 208

Pan European Networks: Government
07
208
ENERGY
PROFILE
H
igh ash coals have been widely used for the generation
of power and industrial steam in India. Coal currently
accounts for more than 50% of total primary commercial
energy supply in India and for about 58.3% of total electricity
generation. Coal is likely to remain a key energy source for India,
for at least the next 30-40 years, as the country has significant
domestic coal reserves (relative to other fossil fuels) and a large
installed-capacity for coal-based electricity production.
The present method of using high ash coals is mostly direct
combustion, which is poorly efficient and generates high levels of
pollution. The situation is similar in Turkey where millions of tonnes
of lignite reserves distributed through the country are waiting to be
exploited for electricity generation. Gasification of coal is an
alternative to its direct combustion. The objective of the OPTIMASH
project is to optimise this technology for high ash content coals of
India and Turkey using innovative gasification processes.
Coal gasification, and the subsequent
electricity generation through a gas
turbine and a steam turbine using
the combustion flue gases heat (this
is called Integrated Gasification
Combined Cycle–IGCC), has the
potential for a more efficient and
cleaner use of coal.
Very briefly, gasification is an energy conversion process where
chemical reactions (for example between air and coal) occur
under oxidant deficient conditions so that at the end of this
‘incomplete combustion’ process, instead of CO
2
and H
2
O, a
produced gas mainly composed of CO and H
2
is obtained. Steam
or oxygen can also be used as gasification agent. The heat
necessary to trigger the endothermic gasification reactions may
come from the combustion of part of the coal feed. If the
combustion and gasification processes occur in the same reactor
(direct gasification) the calorific value of the produced gas is not
very high (as the N
2
contained in the combustion air is also
heated and is mixed with CO and H
2
). If the two processes occur
in different reactors (indirect gasification), the calorific value of the
produced gas is much higher. Depending on the coal properties,
mainly its ash content and ash fusion temperature, various coal
gasification technologies are available.
Coal gasification, and the subsequent electricity generation
through a gas turbine and a steam turbine using the combustion
flue gases heat (this is called Integrated Gasification Combined
Cycle–IGCC), has the potential for a more efficient and cleaner
use of coal.
Several IGCC plants are installed worldwide
main problem
for IGCC is its high capital cost, but the inclusion of carbon capture
and sequestration capabilities of IGCC make it a more attractive
choice for using low cost coal in a carbon constrained world.
In addition to electricity generation, the synthetic gas obtained by
coal gasification may have several other uses such as in liquid
fuel production through subsequent catalytic processes, in
industrial processes such as glass furnaces, in hydrogen
generation and other applications. Besides, the gasification
technology once optimised may also be used to gasify other fuels
such as petcoke, organic municipal waste and biomass residues,
either mixed with coal or alone. Finally, coal gasification enables
pre-combustion carbon capture (by transforming the CO into CO
2
and combusting the remaining H
2
). This high concentration CO
2
stream can be easily separated from H
2
by physical processes
such as membrane technologies, which are less energy
consuming and less expensive than post-combustion carbon
capture technologies, which are the only carbon capture methods
available for coal combustion power plants.
Objectives of the OPTIMASH project
The OPTIMASH project is supported by the EU ENERGY-2011
programme and aims to optimise the operating conditions of
IGCC technology based on high ash coals. This can be reached by
improving both the efficiency and the reliability of the gasification
system. Efficiency improvement can be gained by increasing cold
gas efficiency of the gasifier by optimising different gasification
technologies, such as indirect gasification, air/steam blown
gasification, and Pressurised Circulating Fluidised Bed technology,
among others.
Additional efficiency improvements could include syngas cooler
optimisation, coal pretreatment, system/heat integration, feeding
optimisation, and particle size optimisation. Reliability
improvement R&D topics mainly include continuous (pressurised)
coal feeding, agglomeration avoidance strategies, proper ash
From the ashes
CNRS ICARE Director Dr Iskender Gökalp discusses the OPTIMASH project and its
ambitions to design, manufacture and test a 1MW gasification plant optimised
for high ash coal
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