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02503 Analysis and optimization of hybrid MCFC gasturbines plants
10 Engines (power generation and propulsion, electrical vehicles) from these sources, on-line mercury semicontinuous emission monitors (Hg SCEMs) have been developed and tested in recent years. Although Hg SCEMs have shown promise during these previous tests, rigorous field or long-term testing has not been done. In the past year, commercially available and prototype Hg SCEMs have been used by the Energy and Environmental Research Center (EERC) and others at several power plants. As part of the EERC work, Hg SCEMs were operated at a range of conditions and locations. In addition, the Hg SCEMs were operated for up to 1 month. The use of Hg SCEMs at these plants allowed for near-real-time data to be collected under changing plant conditions, as well as during normal ranges of operating conditions. Mercury emission data were obtained from different plants with different configurations. The plant configurations incorporated various pollution control technologies, including selective catalytic reduction (SCR), selective noncatalytic reduction, ammonium sulfate injection for flue gas conditioning, and flue gas desulfurization (FGD). The particulate control devices included electrostatic precipitators (ESPs), a fabric filter (FF), and a venturi scrubber. The testing at these sites included the operation of Hg SCEMs before and after particulate control devices, in wet and dry stack conditions, and at high temperatures (343°C). The results from these field measurements have provided data that have been evaluated to determine the reliability, variability, biases, and overall capability of Hg SCEMs for monitoring mercury at coal-fired utilities. Even under the best conditions, operation of Hg SCEMs is by no means simple. Their operation at high-dust-condition locations (i.e. prior to the particulate control device), wet stack conditions, and high temperatures has tested the ruggedness of the Hg SCEMs. As a result of this testing, some of the critical factors affecting accuracy, precision, and reliability have been made apparent. The overall capability of Hg SCEMs to produce near-real-time data (data every 5 rain) was also evaluated under these conditions. The duration of the tests ranged from short-term periods (1-2 h) up to 1 month. Evaluation of the data over the longer-term tests shows the range of mercury emissions due to the variability of mercury in the coal and the normal range of operating parameters for the unit. The range of data is important when control strategies and managing emission inventories are considered. EPA has not determined what type of monitoring or testing requirements will be included in the upcoming electric utility mercury regulations. There is, of course, interest in requiring the use of Hg SCEMs. However, the research to date has shown that commercially available Hg SCEMs are not capable of operating unattended to produce reliable and accurate emission data.
High temperature fuel cells are electricity producers that guarantee relevant energetic and environmental performances. They feature high electricity to input chemical energy ratios and availability of high temperature heat. Notwithstanding, the search for a further increase in electric efficiency, especially when applying a CHP solution is not feasible, has brought to plant integration with gas turbines (GTs) in several studies and some pilot installations. While for pressurized fuel cells the choice of internal combustion gas turbines seem to be the only one feasible, in ambient pressure fuel cells it seems useful to analyse the combination with indirect heated GT. This choice allows to optimize turbine pressure ratio and cell size. In this work, a parametric performance evaluation of a hybrid molten carbonate fuel cell (MCFC) indirect heated gas turbine has been performed by varying the fuel cell section size and the fuel utilization coefficient. The analysis of performance variation with the latter parameter shows how a cell that is optimized for stand alone operation is not necessarily optimized for the integration in a hybrid cycle. Working with reduced utilization factors, in fact can reduce irreversible losses and does not necessarily yield to less electricity production since the heat produced in the post combustor is recovered by the gas turbine section. This aspect has not been taken into sufficient consideration in literature. The analysis illustrates the methodology to define new operating conditions so to allow global output and global efficiency maximization.
04•02504 Development of a methanol fuelled reformer for fuel cell applications Lindstr6m, B. and Pettersson, L. J. Journal of Power Sources, 2003, 118, (1-2), 71-78. A compact methanol reformer for fuel cell vehicles (FCVs) has been developed and successfully, tested. The reformer which has been constructed to serve a 5 kWe fuel cell operates by combined reforming of methanol (CRM) (a combination of steam reforming and partial oxidation). The exploitable energy surplus in a fuel cell vehicle is low and therefore a combustion system for heating the reformer, which utilizes a catalyst for both evaporation and oxidation of liquid methanol was developed. Start-up times were obtained in the region of 4-6 rain depending on the oxygen-to-methanol ratio (OMR) used for the combined reforming reaction. The main drawback from decreasing the start-up time by increasing the oxygen-to-methanol ratio was that the CO concentrations in the product stream increased. The reforming reaction was performed over copper-based catalysts while the oxidation took place over a mixture of platinum and manganese-based catalysts. The catalysts were characterized using SEM-EDS, BET surface area measurement and X-ray diffraction (XRD).
04/02505 Evaluation of soot particulate mitigation additives in a T63 engine
10
ENGINES Power generation and propulsion, electrical vehicles
04/02502 Achieving ultra low emissions in a commercial 1.4 MW gas turbine utilizing catalytic combustion Kajita, S. and Betta, R. D. Catalysis Today, 2003, 83, (1 4), 279-288. The drive to achieve low emissions from gas turbines has been an ongoing challenge for over 30 years with the reduction of NOx levels representing the most difficult issue. Catalytic combustion represents the technological approach that can achieve the lowest level of NOx, in the range of 3 ppm and lower depending on the combustion system design. The program to develop a catalytic combustion technology that can achieve ultra low levels of NO,., CO and unburned hydrocarbons (UHCs), applicable to a wide range of gas turbine systems and with long term durability is described. The technoIogieal approach is to combust only a portion of the fuel within the catalyst with the remaining fuel combusted downstream of the catalyst allowing the catalyst to operate at a low temperature and thus obtaining good long term catalyst durability. This catalytic combustion approach is then applied to a 1.4 MW gas turbine to demonstrate feasibility and to obtain real field experience and to identify issues and areas needing further work. The success of this demonstration lead to a commercial combustor design. This combustor and the final commercial package is described and the performance specifications discussed.
04/02503 Analysis and optimization of hybrid MCFC gas turbines plants Lunghi, P. et al. Journal of Power Sources, 2003, I18, (1-2), 108-117.
350
Fuel and Energy Abstracts September 2004
Corporan, E. et al. Fuel Processing Technology, 2004, 85, (6-7), 727742. The performance of fuel additive candidates to mitigate soot particulate emissions in turbine engines was assessed in a T63 helicopter engine. Seventeen additives, including commercial compounds to reduce emissions in internal combustion engines, diesel cetane improvers, and experimental/proprietary additives, were evaluated. The additives were individually injected into the JP-8 fuel feed to the engine, and evaluated at a minimum of three concentration levels. The engine was operated at two conditions, idle and cruise, to investigate additive effects at different power settings or equivalence ratios. Particulate samples were collected from the engine exhaust using an oil-cooled probe, and analysed using a suite of particulates instrumentation, which included a condensation nuclei counter, scanning mobility particle sizer, laser particle counter and a tapered element oscillating microbalance. Results indicate that the diesel cetane improvers and commercial smoke abatement additives tested had minimal impact on particulate emissions in the T63 turboshaft engine. One proprietary additive was shown to reduce particle number density by up to 67% at the relatively high concentration of 3000 mg/1. These benefits were observed only at cruise condition, which may provide some insight into the mechanisms by which the additive suppresses the formation or enhances the oxidation of soot particles. Test results with blends of JP-8 and Norpar-13 (normal paraffins) show significant reductions in particulate emissions for both idle and cruise conditions demonstrating the potential environmental benefits of using blends of clean (low aromatic and low sulfur) fuels with JP-8. Comparisons of mass determination with different instruments and preliminary results of chemical characterization of particulate emissions with and without additives are also presented.
04/02506
Knock in spark ignition hydrogen engines
Li, H. and Karim, G. A. International Journal of Hydrogen Energy, 2004, 29, (8), 859-865. In engine applications, the onset of knock remains one of the prime limitations that needs to be addressed so as to avoid its incidence and achieve superior performance. In the present contribution relating to the spark ignition hydrogen-fuelled engine, the effects of changes in
High temperature fuel cells are electricity producers that guarantee relevant energetic and environmental performances. They feature high electricity to input chemical energy ratios and availability of high temperature heat. Notwithstanding, the search for a further increase in electric efficiency, especially when applying a CHP solution is not feasible, has brought to plant integration with gas turbines (GTs) in several studies and some pilot installations. While for pressurized fuel cells the choice of internal combustion gas turbines seem to be the only one feasible, in ambient pressure fuel cells it seems useful to analyse the combination with indirect heated GT. This choice allows to optimize turbine pressure ratio and cell size. In this work, a parametric performance evaluation of a hybrid molten carbonate fuel cell (MCFC) indirect heated gas turbine has been performed by varying the fuel cell section size and the fuel utilization coefficient. The analysis of performance variation with the latter parameter shows how a cell that is optimized for stand alone operation is not necessarily optimized for the integration in a hybrid cycle. Working with reduced utilization factors, in fact can reduce irreversible losses and does not necessarily yield to less electricity production since the heat produced in the post combustor is recovered by the gas turbine section. This aspect has not been taken into sufficient consideration in literature. The analysis illustrates the methodology to define new operating conditions so to allow global output and global efficiency maximization.
04•02504 Development of a methanol fuelled reformer for fuel cell applications Lindstr6m, B. and Pettersson, L. J. Journal of Power Sources, 2003, 118, (1-2), 71-78. A compact methanol reformer for fuel cell vehicles (FCVs) has been developed and successfully, tested. The reformer which has been constructed to serve a 5 kWe fuel cell operates by combined reforming of methanol (CRM) (a combination of steam reforming and partial oxidation). The exploitable energy surplus in a fuel cell vehicle is low and therefore a combustion system for heating the reformer, which utilizes a catalyst for both evaporation and oxidation of liquid methanol was developed. Start-up times were obtained in the region of 4-6 rain depending on the oxygen-to-methanol ratio (OMR) used for the combined reforming reaction. The main drawback from decreasing the start-up time by increasing the oxygen-to-methanol ratio was that the CO concentrations in the product stream increased. The reforming reaction was performed over copper-based catalysts while the oxidation took place over a mixture of platinum and manganese-based catalysts. The catalysts were characterized using SEM-EDS, BET surface area measurement and X-ray diffraction (XRD).
04/02505 Evaluation of soot particulate mitigation additives in a T63 engine
10
ENGINES Power generation and propulsion, electrical vehicles
04/02502 Achieving ultra low emissions in a commercial 1.4 MW gas turbine utilizing catalytic combustion Kajita, S. and Betta, R. D. Catalysis Today, 2003, 83, (1 4), 279-288. The drive to achieve low emissions from gas turbines has been an ongoing challenge for over 30 years with the reduction of NOx levels representing the most difficult issue. Catalytic combustion represents the technological approach that can achieve the lowest level of NOx, in the range of 3 ppm and lower depending on the combustion system design. The program to develop a catalytic combustion technology that can achieve ultra low levels of NO,., CO and unburned hydrocarbons (UHCs), applicable to a wide range of gas turbine systems and with long term durability is described. The technoIogieal approach is to combust only a portion of the fuel within the catalyst with the remaining fuel combusted downstream of the catalyst allowing the catalyst to operate at a low temperature and thus obtaining good long term catalyst durability. This catalytic combustion approach is then applied to a 1.4 MW gas turbine to demonstrate feasibility and to obtain real field experience and to identify issues and areas needing further work. The success of this demonstration lead to a commercial combustor design. This combustor and the final commercial package is described and the performance specifications discussed.
04/02503 Analysis and optimization of hybrid MCFC gas turbines plants Lunghi, P. et al. Journal of Power Sources, 2003, I18, (1-2), 108-117.
350
Fuel and Energy Abstracts September 2004
Corporan, E. et al. Fuel Processing Technology, 2004, 85, (6-7), 727742. The performance of fuel additive candidates to mitigate soot particulate emissions in turbine engines was assessed in a T63 helicopter engine. Seventeen additives, including commercial compounds to reduce emissions in internal combustion engines, diesel cetane improvers, and experimental/proprietary additives, were evaluated. The additives were individually injected into the JP-8 fuel feed to the engine, and evaluated at a minimum of three concentration levels. The engine was operated at two conditions, idle and cruise, to investigate additive effects at different power settings or equivalence ratios. Particulate samples were collected from the engine exhaust using an oil-cooled probe, and analysed using a suite of particulates instrumentation, which included a condensation nuclei counter, scanning mobility particle sizer, laser particle counter and a tapered element oscillating microbalance. Results indicate that the diesel cetane improvers and commercial smoke abatement additives tested had minimal impact on particulate emissions in the T63 turboshaft engine. One proprietary additive was shown to reduce particle number density by up to 67% at the relatively high concentration of 3000 mg/1. These benefits were observed only at cruise condition, which may provide some insight into the mechanisms by which the additive suppresses the formation or enhances the oxidation of soot particles. Test results with blends of JP-8 and Norpar-13 (normal paraffins) show significant reductions in particulate emissions for both idle and cruise conditions demonstrating the potential environmental benefits of using blends of clean (low aromatic and low sulfur) fuels with JP-8. Comparisons of mass determination with different instruments and preliminary results of chemical characterization of particulate emissions with and without additives are also presented.
04/02506
Knock in spark ignition hydrogen engines
Li, H. and Karim, G. A. International Journal of Hydrogen Energy, 2004, 29, (8), 859-865. In engine applications, the onset of knock remains one of the prime limitations that needs to be addressed so as to avoid its incidence and achieve superior performance. In the present contribution relating to the spark ignition hydrogen-fuelled engine, the effects of changes in