Development of a Catalytic Combustor for Small Gas Turbines

Mori, Kenji; Kitajima, J.; Kajita, S.; Ichihara, Shoichi

doi:10.1115/87-gt-62

Cited by 4 publications

(5 citation statements)

References 4 publications

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“…The residence times in the catalyst bed are typically 5 to 30 ms for tubes with hydraulic diameters on the order of I to 4 mm. For combustor inlet temperatures ranging from 650 K to 900 K, combustion efficiencies of greater than 99.5 percent have been reported over a range of fuel-air equivalence ratios that result in adiabatic flame temperatures between 1100 K and 1800 K (e.g., Wampler et al, 1976;Mori et al, 1987).…”

Section: Lean Burning Hydrogen-air Systemmentioning

confidence: 98%

Combustors for Micro-Gas Turbine Engines

Waitz

Gauba

Tzeng

1998

Journal of Fluids Engineering

204

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The development of a hydrogen-air microcombustor is described. The combustor is intended for use in a 1 rrmf inlet area, micro-gas turbine engine. While the size of the device poses several difficulties, it also provides new and unique opportunities. The combustion concept investigated is based upon introducing hydrogen and premixing it with air upstream of the combustor. The wide flammability limits of hydrogen-air mixtures and the use of refractory ceramics enable combustion at lean conditions, obviating the need for both a combustor dilution zone and combustor wall cooling. The entire combustion process is carried out at temperatures below the limitations set by material properties, resulting in a significant reduction of complexity when compared to larger-scale gas turbine combustors. A feasibility study with initial design analyses is presented, followed by experimental results from 0.13 cm' silicon carbide and steel microcombustors. The combustors were operated for tens of hours, and produced the requisite heat release for a microengine application over a range of fuel-air ratios, inlet temperatures, and pressures up to four atmo.^pheres. Issues of flame stability, heat transfer, ignition and mixing are addressed. A discussion of requirements for catalytic processes for hydrocarbon fuels is also presented.

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Section: Lean Burning Hydrogen-air Systemmentioning

confidence: 98%

Combustors for Micro-Gas Turbine Engines

Waitz

Gauba

Tzeng

1998

Journal of Fluids Engineering

204

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“…The law-ofthe-wall and standard k-E turbulence models are used. The governing equations are expressed as follows: the transport equations (1), the equation of state (2), and the conservation equation of species (3). $ represents one of the variables, Yi, u, v, w, e, k and C.…”

Section: Gas Phasementioning

confidence: 99%

“…It would be necessary for a combustor to achieve a mean NOx emission index of less than about 10 g/kg-fuel, assuming that the thermal efficiency of a gas turbine engine is 20%. In regard to the abatement of exhaust emission, various prevapor-premixed-lean-combustors [1] and catalytic combustors [2] have been reported. These combustors need to install a variable geometry in order to stabilize the combustion.…”

mentioning

confidence: 99%

Ignition and Exhaust Emission Characteristics of Spray Combustion in a Pre-Chamber Type Vortex Combustor

Ohkubo

Nomura

Idota

et al. 1992

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The lean ignition limit, the lean blowout limit and the exhaust emission characteristics of spray combustion have been investigated experimentally using a pre-chamber type vortex combustor developed for a 300KW large-bus gas turbine engine. It has been verified that these depend on the spray characteristics of the fuel injector and the air flow pattern or the distribution of air in the chamber. Ignition succeeds through three processes. The first step is the formation of a flame kernel near the sparking ignitor, the second step is the propagation of the flame kernel into a flame holding region, and the last step is the formation of a rotating flame in that region. The lean blowout limit of the rotating flame depends on the air flow pattern in the pre-chamber when the air temperature in the combustor inlet is under 470K, while a constant fuel-air ratio of less than 0.001 is maintained at 470K and above. With no or a little secondary air, the NOx emission index does not increase in proportion to the fuel-air ratio, because both the gas temperature and residence time decrease due to the radiative heat loss caused by soot formation and reduction of a recirculation region in the main-chamber. These phenomena were evaluated with 3 dimensional numerical simulations taking account of spray combustion, soot formation, the extended-Zeldovich thermal NO formation and radiative heat loss.

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“…The program was divided into three phases. Phase I aimed at the development of a catalyst most appropriate for the program, the design and fabrication of catalytic combustors containing the best catalyst found in this phase, and the development of a control system (1). In Phase II of the program, the catalytic combustors and the control system developed in the Phase I were installed in an actual turbine and tested to obtain information required for further improvement (2), (3).…”

Section: Introductionmentioning

confidence: 99%

“…However, the following problems which should be solved were found. (1) All catalyst elements exposed to the engine test cracked at their edges because of the large temperature gradient in the radial direction. (2) Although the catalyst ULNXC-302 developed in Phase I enabled a highly efficient combustion, with a combustion efficiency of more than 99%, over the entire range of operation, the catalyst activity deteriorated rapidly.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a Catalytic Combustor in a Gas Turbine-Generator Unit

Kajita

Tanaka

Kitajima

1990

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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As a final step of the Catalytic Combustor Development Program, a catalytic combustor developed was tested in a 150-kW gas turbine-generator unit. A digital control system was developed to improve its controllability for a transient operation, and a 200-hr continuous operation test was performed to asses the durability of the catalyst. During the test, an excellent performance of the control system was verified, and a very high combustion efficiency of more than 99% and a ultra-low NOx level of less than 5.6 ppm (at 15% O2) were achieved at a 150-kW generator output. In addition, the combustion efficiency has been maintained at over 98% for 200 hours of operation. However, the catalyst exposed to 200 hours of operation showed signs of deactivation.

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Development of a Catalytic Combustor for Small Gas Turbines

Cited by 4 publications

References 4 publications

Combustors for Micro-Gas Turbine Engines

Combustors for Micro-Gas Turbine Engines

Ignition and Exhaust Emission Characteristics of Spray Combustion in a Pre-Chamber Type Vortex Combustor

Evaluation of a Catalytic Combustor in a Gas Turbine-Generator Unit

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