Richard L. Hack

Impact of Ethane, Propane, and Diluent Content in Natural Gas on the Performance of a Commercial Microturbine Generator

The impact of fuel composition on performance of power generation devices is gaining interest as a desire to diversify fuel supplies increases. In the present study measurements of combustion performance were conducted on a commercial natural gas fired 60-kW gas turbine as a function of fuel composition. A statistically designed experiment was carried out and exhaust emissions were obtained for significant amounts of ethane and propane. In addition, a limited study of the effect of inerts was examined. The results show that emissions of NOx, CO, and NOx/NO are not well correlated with common descriptions of the fuel such as higher heating value or methane number. The results and trends indicate that the presence of higher hydrocarbons in the fuel leads to appreciably higher NOx emissions for both test devices operating under similar lean conditions, while having less impact on CO emissions.Copyright

Assessment of a Rich-Burn, Quick-Mix, Lean-Burn–Based Supplemental Burner System in a Vitiated Air Stream

ABSTRACT In an effort to increase overall efficiency of distributed power generation systems, strategies to optimize the combination of cooling or heating with power (CCHP) are desired. One significant issue in implementing a CCHP system is that electrical loads and heating/cooling loads are rarely synchronized. Duct burners are frequently used in large systems to provide additional heat when the waste heat available from the prime mover does not meet the needs of the heat recovery device. Duct burners must operate on vitiated oxidizer streams, which can result in poor stability, elevated emissions, or both. Rich-burn, quick-mix, lean-burn (RQL) style combustors have been shown to provide low emission and high stability in lean burn gas turbine applications, but have not been considered for duct burner applications. To this point, the current work carries out an experimental investigation to assess the merits of using an RQL style combustor in a duct burner application. A systematic evaluation of several RQL burner configurations revealed that a lean-zone-to-rich-zone air mass ratio of 2.5 produced the lowest emissions of NOx and CO at a fixed fuel-to-air ratio. However, this reduction in emissions was accompanied with a decrease in the stability range of the burner. Furthermore, decreasing the amount of swirl in the rich zone was found to decrease NOx emissions. It was observed that oxygen concentration of the oxidizer had a more significant effect on the emission of CO than any configuration of the burner.

Performance Assessment of a Gas Fired RQL Combustion System Operated in a Vitiated Air Stream

Increased interest in distributed power generation has led to increased interest in combined heating cooling and power (CCHP). One significant issue in implementing a CCHP is that electrical loads and heating or cooling loads are rarely synchronized. Duct burners are frequently used to provide additional heat when the waste heat available from the prime mover does not meet the needs of the heat recovery device. Duct burners are required to operate on vitiated oxidizer streams which can result in poor stability, poor emissions, or both. Rich-burn, quick-mix, lean-burn (RQL) style combustors have been shown to provide low emission and high stability in lean gas turbine applications. An experiment was performed to assess the merits of using a RQL style combustor in a duct burner application. Several burner configurations were tested and it was found that an RQL combustor showed greatly improved stability over a single stage combustor when operating under vitiated conditions without adversely effecting emissions.

Monitoring Microturbine Generators Installed in the South Coast Air Basin

Microturbine generators offer an interesting early commercial strategy for implementation of distributed generation. Through a program sponsored by the South Coast Air Quality Management District (SCAQMD), 207 microturbines of 30 and 60kW output are deployed or in the process of being deployed at 47 sites throughout the SCAQMD. These units are being monitored for general operational characteristics such as hours operated, number of starts, total output. In addition, several of the sites have been outfitted with additional sensors that facilitate the collection of efficiency information. Performance results from two of these sites are presented along with corresponding economic evaluation. The results indicate that actual performance does not reach the manufacturer’s specifications and that the recent increases in natural gas prices have increased the projected payback period for the equipment.Copyright