In this study, potentials of the liquid-fueled low-swirl burner technique for industrial gas-turbine combustor application are reported for the first time. A low-swirl fuel nozzle, which is a new implementation of the basic lowswirl burner design, is configured by the velocity measurement of methane-air open flames under atmospheric pressure and a low velocity (~3 m/s) condition. Flow properties, such as the axial stretch rate and virtual origins, are compared with the previously reported values with the axial vane type low-swirl injector, and it is confirmed that the flow field generated from the current implementation is of the typical low-swirl flow. Then, it is shown that the configuration successfully stabilize the lifted flame under much higher velocity (~50m/s) condition with kerosene fuel injected by a typical pressure atomizer. Finally, the fuel nozzle is installed in a 290 kW simple-cycle liquid-fueled gas turbine engine and is found to be operable over the entire operating range. The combustor inlet wall temperatures are shown to be within an acceptable range, even without the cooling air that was required for conventional combustors. This is an advantage of the lifted flame stabilized by the low-swirl technique. Although our focus is not on low emissions characteristics, NOx emissions is also found to be below maximum levels of current Japanese regulations (<84 ppm@15% O2). In sum, the proposed fuel nozzle design shows promise for the application of liquid-fueled industrial gas turbine engines.

In this study, potentials of the liquid-fueled low-swirl burner technique for industrial gas-turbine combustor application are reported for the first time. A low-swirl fuel nozzle, which is a new implementation of the basic lowswirl burner design, is configured by the velocity measurement of methane-air open flames under atmospheric pressure and a low velocity (~3 m/s) condition. Flow properties, such as the axial stretch rate and virtual origins, are compared with the previously reported values with the axial vane type low-swirl injector, and it is confirmed that the flow field generated from the current implementation is of the typical low-swirl flow. Then, it is shown that the configuration successfully stabilize the lifted flame under much higher velocity (~50m/s) condition with kerosene fuel injected by a typical pressure atomizer. Finally, the fuel nozzle is installed in a 290 kW simple-cycle liquid-fueled gas turbine engine and is found to be operable over the entire operating range. The combustor inlet wall temperatures are shown to be within an acceptable range, even without the cooling air that was required for conventional combustors. This is an advantage of the lifted flame stabilized by the low-swirl technique. Although our focus is not on low emissions characteristics, NOx emissions is also found to be below maximum levels of current Japanese regulations (<84 ppm@15% O2). In sum, the proposed fuel nozzle design shows promise for the application of liquid-fueled industrial gas turbine engines.

We developed a dual-fuel single can combustor for the Niigata Gas Turbine (NGT2BC), which was developed as a continuous-duty gas turbine capable of burning both kerosene and digester gas. The output of the NGT2BC is 920 kW for continuous use with digester gas and 1 375 kW for emergency use with liquid fuel. Digester gas, obtained from sludge processing at sewage treatment plants, is a biomass energy resource whose use reduces CO 2 emissions and take advantage of an otherwise wasted energy source. Design features for good combustion with digester gas include optimized the good matching of gas injection and swirl air and reduced reference velocity. The optimal combination of these parameters was determined through CFD analysis and atmospheric rig testing.

In this paper, flow fields inside a premixed combustor have been investigated by CFD analysis and PIV measurement in a preheating, non-reacting condition. Four types of premixer are examined. The design of the premixer is determined by the combination of swirlers and mixing tubes. There are two variations of triple-concentric swirlers and three variations of mixing tubes. Comparisons are made among mean velocity distributions derived from CFD and PIV. PDF analysis is performed on the data from PIV to discuss the possibility of the occurrence of flashback. Combustion rig tests have been carried out also on similar condition to see combustion instabilities depending on the choice of premixers and operating conditions. Flame is directly observed from crystal windows placed on the side and downstream of the combustion chamber. A glass rod is installed on the wall of the mixing tube so as to see light emissions inside the tube, i.e. evidence of flashback. Pressure fluctuations at the combustor liner are measured in one position. The spectra of pressure fluctuations are computed to look at the possibility of combustion oscillations. Discussions are made on the relation between the global flame structure and pressure modes. Finally, proper premixer configurations to prevent combustion instabilities are proposed.

The authors have developed a liquid-fueled, low-emissions, and single can combustor for the RGT3R, Niigata’s 300 kW class industrial gas turbine engine, with the goal of satisfying the most stringent environmental requirements for distributed power generation systems in Japan. This paper describes these development efforts, which included non-reacting Computational Fluid Dynamics (CFD) analysis and component and engine tests. The emissions target is less than 24 ppm nitrogen oxides (NOx), 60 ppm carbon monoxide (CO) and 60 ppm unburned hydrocarbons (UHCs) at dry 15% O2 correction for kerosene, while operating above 50% load. A lean premixed, pre-vaporized, axially staged combustion concept is used to minimize emissions levels to the strictest emissions regulations in urban areas such as Tokyo, Chiba, Saitama, Yokohama, and Osaka. This combustion system involves two pilot burners and two main mixture injection tubes that are extending into the combustion chamber to inject lean to ultra-lean premixed mixtures into the hot burned gas from pilot burners. Counter rotational swirl vanes are provided to pilot burners and main mixture injection tubes to prevent flashback into the premixing tubes. The RGT3R gas turbine engine operates smoothly with the developed DLE combustion system from idle to full load without combustion-driven pressure oscillations. A two-stage fuel control system employs liquid fuel supply for the pilot and main atomizers. As this paper describes, the emissions data from this engine meet the emissions goals.