Combustion for Gas Turbine Applications

THEVENIN, ANDERS G. ERSSON, ROLF GABRIELSSON, R GOVIND MENON, PEHR H. BJORNBOM AND SVEN G. JARAS 

Catalytic combustion has received an increasing interest as an ultra-low emission technology for gas turbines. The main advantage with catalytic combustion is the possibility to decrease, and for some fuels to increase, the fuel-to-air ratio beyond the limits of flammability. Hence the combustion process and the temperature evolution in a gas turbine combustion chamber can be better controlled and stabilized. This flexibility gives the possibility to reduce emissions of unwanted pollutants compared with conventional flame combustion. Depending on fuel characteristics, emissions such as thermal and fuel-NOx, CO and hydrocarbons as well as soot can be reduced to ultra-low levels. Other advantages are lower noise levels and less vibrations. 

During this time period, an increasing number of reviews and general articles on catalytic combustion have been published. Recently, basic principles as 

More recently, new applications of catalytic combustion have been explored. Particularly the use in small-scale gas turbines to be used in mobile applications, such as rail locomotives, road vehicles and ships is anticipated. In addition, an increased use of small gas turbines for industrial applications such as offshore installations, pipeline compressors and power generation is expected. 

The aim with the present paper is to survey the literature on catalytic fuel combustion for high temperature gas turbine applications with emphasis on the progress during the last five years. Reference to work before 1993 can be found in an earlier review from our laboratory. Following a brief introduction to catalytic combustion and a discussion on formation and abatement of emission, state-of-the-art in materials development will be reviewed in Section 3. Recent results from mathematical modelling are covered in Section 4. An update of new concepts of catalytic combustors and advanced pilot-scale tests will be presented in Section 5, where also a case study on a recently finished European project is reported. Finally, deactivation of combustion catalysts is discussed in Section 6 and a spin-off effect of catalytic combustion is recapitulated in Section 7. 

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However, most of the following discussion will deal with catalytic combustion for gas turbine applications. Figure 4 shows a schematic view of an open-cycle gas turbine unit with a catalytic combustor (cf. a conventional unit in Fig. 2.). 

E. M. Johansson, D. Papadias, P.O. Thevenin, A.G. Ersson, R. Gabrielsson, P.G. Menon, P.H. Bjornbom and S.G. Jaras, in Catalytic Combustion for Gas Turbine Applications, Catalysis-Specialist Periodical Reports, Volume 14, Royal Society of Chemistry, Cambridge 2001... 

In this section, recent development of high temperature stable support materials as well as washcoat and active materials is reviewed. Some of the most promising materials to be used as supports in catalytic combustion for gas turbine applications are summarized in Table 1. These monolithic support materials, such as alumina or zirconia, could also be used as washcoat materials with another preparation method. Typical light-off temperatures and specific surface areas for some of the interesting catalyst compositions are summarized in Table 2. 

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