St. Kolaczkowski, CATALYTIC STATIONARY GAS-TURBINE COMBUSTORS - A REVIEW OF THE CHALLENGES FACED TO CLEAR THE NEXT SET OF HURDLES, Chemical engineering research & design, 73(A2), 1995, pp. 168-190
In response to the need to develop low NOx combustors, there has been
renewed interest in catalytic combustion and a new sense of urgency in
seeking to overcome the remaining hurdles and develop a commercial un
it. Starting with an explanation of how the shape of a 'light-off' cur
ve for a catalyst may vary, progress in the development of low, medium
and high temperature catalyst systems is described. Since gas turbine
s need to be capable of operating at varying power loads, where the ga
s inlet conditions vary, hybrid systems have been developed. These are
reviewed in this paper and the challenges faced by interdisciplinary
teams working on system designs are described. In general, schemes hav
e progressed on the lines of maximizing catalytic reactions until gas
temperatures exceed 800 degrees C, at which point homogeneous reaction
s become significant. Since natural gas is an abundant and relatively
clean fuel, it is used in many of the schemes described, and because o
f pressure drop constraints monoliths are favoured as catalyst support
systems. Practical advice is also provided on the use of mathematical
modelling techniques which should proceed in parallel with system des
ign, utilizing established knowledge in chemical reaction engineering
in order to make progress. An overview of the reactions and transport
processes taking place is described, and the difficulties of obtaining
kinetic and transport/physical property data are outlined. Despite th
e considerable progress that has been made, many challenges remain and
a number of these centre on system design and how to cope with varyin
g power loads. In addition, issues concerning catalyst durability fuel
-air mixing, minimization of stresses, and start-up need attention.