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In this contribution, an overview of the progress in the design of an enhanced FLOX[R] burner is given. A fuel flexible burner concept was developed to fulfill the requirements of modern gas turbines: high specific power density, high turbine inlet temperature, and low N[O.sub.x] emissions. The basis for the research work is numerical simulation. With the focus on pollutant emissions, a detailed chemical kinetic mechanism is used in the calculations. A novel mixing control concept, called HiPerMix[R], and its application in the FLOX[R] burner are presented. In view of the desired operational conditions in a gas turbine combustor, this enhanced FLOX[R] burner was manufactured and experimentally investigated at the DLR test facility. In the present work, experimental and computational results are presented for natural gas and natural gas +hydrogen combustion at gas turbine relevant conditions and high adiabatic flame temperatures (up to [T.sub.ad] = 2000 K). The respective power densities are [P.sub.A] =13.3 MW/[m.sup.2] bar (natural gas (NG)) and [P.sub.A] =14.8 MW/[m.sup.2] bar (NG + [H.sub.2]), satisfying the demands of a gas turbine combustor. It is demonstrated that the combustion is complete and stable and that the pollutant emissions are very low. [DOI: 10.1115/1.4001825] Keywords: FLOX[R], HiPerMix[R], flameless combustion, gas turbine combustion, high temperature gas turbine, fuel flexibility, hydrogen combustion, numerical simulation, high pressure test rig, laser diagnostics

As carbon capture and storage technology has grown as a promising option to significantly reduce C[O.sub.2] emissions, system integration and optimization claim an important and crucial role. This paper presents a comparative study of a gas turbine cycle with postcombustion C[O.sub.2] separation using an amine-based absorption process with monoethanolamine. The study has been made for a triple pressure reheated 400 MWe natural gas-fuelled combined cycle with exhaust gas recirculation (EGR) to improve capture efficiency. Two different options for the energy supply to the solvent regeneration have been evaluated and compared concerning plant performance. In the first alternative heat is provided by steam extracted internally from the bottoming steam cycle, while in the second option an external biomass-fuelled boiler was utilized to generate the required heat. With this novel configuration the amount of COa captured can be even more than 100% if the exhaust gas from the biofuelled boiler is mixed and cleaned together with the main exhaust gas flow from the combined cycle. In order to make an unprejudiced comparison between the two alternatives, the reduced steam turbine efficiency has been taken into consideration and estimated, for the alternative with internal steam extraction. The cycles have been modeled in the commercial heat and mass balance program IPSEPRO[TM] using detailed component models. Utilizing EGR can double the C[O.sub.2] content of the exhaust gases and reduce the energy need for the separation process by approximately 2% points. Using an external biomass-fuelled boiler as heat source for amine regeneration turns out to be an interesting option due to high C[O.sub.2] capture effectiveness. However the electrical efficiency of the power plant is reduced compared with the option with internal steam extraction. Another drawback with the external boiler is the higher investment costs but nevertheless, it is flexibility due to the independency from the rest of the power generation system represents a major operational advantage. [DOl: 10.1115/1.4000122]

The characterization of volatile and nonvolatile particle materials present in gas turbine exhaust is critical for accurate estimation of the potential impacts of airport activities on local air quality, atmospheric processes, and climate change. Two field campaigns were performed to collect an extensive set of particle and gaseous emission data for on-wing gas turbine engines. The tests included CFM56, RB211-535E4-B, AE3007, PW4158, and CJ610 engines, providing the opportunity to compare emissions from a wide range of engine technologies. Here we report mass, number, composition, and size data .for the nonvolatile (soot) and volatile particles present in engine exhaust. For all engines, soot emissions ([EI.sub.m]-soot) are greater at climbout (85% power) and takeoff (100% ) power than idle (4% or 7%) and approach (30%). At the engine exit plane, soot is the only type of particle detected. For exhaust sampled downwind (15-50 m) and diluted by ambient air, total particle number emissions ([EI.sub.n]-total) increases by about one or two orders of magnitude relative to the engine exit plane, and the increase is driven by volatile particles that have freshly nucleated in the cooling exhaust gas both in the free atmosphere and in the extractive sample lines. Fuel sulfur content is the determining factor for nucleation of new particles in the cooling exhaust gases. Compositional analysis indicates that the volatile particles consist of sulfate and organic materials ([EI.sub.m-]sulfate and [EI.sub.m]-organic). We estimate a lower bound S[IV] to S[VI] conversion efficiency of (0. 08 [+ or -] 0.01)%, independent of engine technology. Measurements of Elm-organic ranged from about 0.1 mg [kg.sup.-1] to 40 mg [kg.sup.-1]. Lubrication oil was present in particles emitted by all engines and accounted for over 90% of the particulate organic mass under some conditions. The products of incomplete combustion are a likely source of the remaining volatile organic particle material. [DOI: 10.1115/1.4000132]

The potential human health and environmental impacts of aircraft gas turbine engine emissions during normal airport operation are issues of growing concern. During the JETS/Aircraft Particle Emissions eXperiment(APEX)-2 and APEX-3 field campaigns, we performed an extensive series of gas phase and particulate emissions measurements of on-wing gas turbine engines. In all, nine different CFM56 style engines (including both CFM56-3BI and -7B22 models) and seven additional engines (two RB211-535E4-B engines, three AE3007 engines, one PW4158, and one CJ6108A) were studied to evaluate engine-to-engine variability. Specific gas-phase measurements include N[O.sub.2], NO, and total N[O.sub.x], HCHO, [C.sub.2][H.sub.4], CO, and a range of volatile organic compounds (e.g., benzene, styrene, toluene, naphthalene). A number of broad conclusions can be made based on the gas-phase data set: (1)field measurements of gas-phase emission indices (EIs) are generally consistent with 1CAO certification values; (2) speciation of gas phase N[O.sub.x] between NO and N[O.sub.2] is reproducible for different engine types and favors N[O.sub.2] at low power (and low fuel flow rate) and NO at high power (high fuel flow rate); (3) emission indices of gas-phase organic compounds and CO decrease rapidly with increasing fuel flow rate; (4) plotting EI-CO or volatile organic compound Els against fuel flow rate collapses much of the variability between the different engines, with one exception (AE3007); (5) HCHO, ethylene, acetaldehyde, and propene are the most abundant volatile organic compounds present in the exhaust gases that we can detect, independent of engine technology differences. Empirical correlations accurate to within 30% and based on the publicly available engine parameters are presented for estimating El-N[O.sub.x] and EI-N[O.sub.2]. Engine-to-engine variability, unavailability of combustor input conditions, changing ambient temperatures, and complex reaction dynamics limit the accuracy of global correlations for CO or volatile organic compound EIs. [DOI: 10.1115/1.4000131 ]

Atmospheric and high pressure rig tests were conducted to investigate the feasibility of using biodiesel as an alternative fuel to power industrial gas turbines in one of the world's leading dry low emissions (DLE) combustion systems, the SGT-100. At the same conditions, tests were also carried out for mineral diesel to provide reference information to evaluate biodiesel as an alternative fuel. In atmospheric pressure rig tests, the likelihood of the machine lighting was identified based on the measured probability of the ignition of a single combustor. Lean ignition and extinction limits at various air temperatures were also investigated with different air assist pressures. The ignition test results reveal that reliable ignition can be achieved with biodiesel across a range of air mass flow rates and air fuel ratios (AFRs). In high pressure rig tests, emissions and combustion dynamics were measured for various combustor air inlet pressures, temperatures, combustor wall pressure drops, and flame temperatures. These high pressure rig results show that biodiesel produced less N[O.sub.x] than mineral diesel. The test results indicate that the Siemens DLE combustion system can be adapted to use biodiesel as an alternative fuel without major modification. [DOI: 10.1115/1.3204617]

Ceramic gas turbine development that started in the 1950s has slowed considerably since most of the large-scale ceramic gas turbine development programs of the 1970s-1990s ended. While component durability still does not meet expectations, the prospect of significant energy savings and emission reductions, potentially achievable with ceramic gas turbines, continues to justify development efforts. Four gas turbine applications have been identified that could be commercially attractive: a small recuperated gas turbine (microturbine) with ~35% electrical efficiency, a recuperated gas turbine for transportation applications with ~40% electrical efficiency with potential applications for efficient small engine cogeneration, a ~40% efficient midsize industrial gas turbine, and a ~63% (combined cycle) efficient utility turbine. Key technologies have been identified to ensure performance and component durability targets can be met over the expected life cycle for these applications. These technologies include a [Si.sub.3][N.sub.4] or SiC with high fracture toughness, durable EBCs for [Si.sub.3][N.sub.4] and SiC, an effective EBC/TBC for SiC/SiC, a durable oxide/oxide ceramic matrix composite (CMC) with thermally insulating coating, and the next generation CMCs with high strength that can be used as structural materials for turbine components for small engines and for rotating components in engines of various sizes. The programs will require integrated partnerships between government, national laboratories, universities, and industry. The overall cost of the proposed development programs is estimated at U.S. $100M over 10 years, i.e., an annual average of U.S. $10M. [DOI: 10.1115/1.3124669]

Two power plant schemes that reduce C[O.sub.2] emission and employ natural gas reforming were analyzed and discussed. The first one integrates natural gas reforming technology for efficiency improvement with an oxy-fuel combined power system (OXYF-REF), with water as the main work fluid. The reforming heat is obtained from the available turbine exhaust heat, and the produced syngas is used as fuel with oxygen as the oxidizer. The turbine working fluid can expand down to a vacuum, producing a high-pressure ratio and thus more net work. The second system integrates natural gas reforming in a precombustion decarbonization scheme using chemical absorption technology for the C[O.sub.2] removal (PCD-REF). The gas turbine is the conventional air-based one with compressor intercooling. Supplementary combustion is employed to elevate the turbine exhaust temperature and thus achieve a much higher methane conversion rate (96.9%). Both systems involve internal heat recuperation from gas turbine exhausts, and particular attention has been paid to the integration of the heat recovery chain to reduce the related exergy destruction. The systems are simulated and their thermal efficiency, overall and component exergy losses, and C[O.sub.2] removal capacity are compared. The OXYF-REF system has a higher energy efficiency, of 51.4%, and higher C[O.sub.2] removal, but the product C[O.sub.2] has lower purity, of 84%. The PCD-REF system has a thermal efficiency of 46%, the captured C[O.sub.2] is 99% pure, and the C[O.sub.2] specific emission is 58.5 g/kWh. [DOI: 10.1115/1.2904895]

The emissions of liquid-fuel fired gas turbine engines are strongly affected by the fuel preparation process that includes atomization, evaporation, and mixing. In the present paper, the effects of fuel atomization and evaporation on emissions from an industrial gas turbine engine were investigated. In the engine studied, the fuel injector consists of a coaxial plain jet airblast atomizer and a premixer which consists of a cylindrical tube with four mixing holes and swirler slits. The goal of this device is to establish a fully vaporized, homogeneous fuel/air mixture for introduction into the combustion chamber and the reaction zone. In the present study, experiments were conducted at atmospheric pressure and room temperature as well as at actual engine conditions (0.34 MPa, 740 K) both with and without the premixer. Measurements included visualization, droplet size, and velocity. By conducting tests with and without the premixing section, the effect of the mixing holes and swirler slit design on atomization and evaporation was isolated. The results were also compared with engine data and the relationship between premixer performance and emissions was evaluated. By comparing the results of tests over a range of pressures, the viability of two scaling methods was evaluated with the conclusion that spray angle correlates with fuel to atomizing air momentum ratio. For the injector studied, however, the conditions resulting in superior atomization and vaporization did not translate into superior emissions performance. This suggests that, while atomization and the evaporation of the fuel are important in the fuel preparation process, they are of secondary importance to the fuel/air mixing prior to, and in the early stages of the reaction in, governing emissions. IDOl: 10.1115/1.2771564]

This paper summarizes achievements in the Siemens Westinghouse Advanced Turbine Systems (ATS) Program. The ATS Program, co-funded by the U.S. Department of Energy, Office of Fossil Energy, was a very successful multiyear (from 1992 to 2001) collaborative effort between government, industry, and participating universities. The program goals were to develop technologies necessary for achieving significant gains in natural gas-fired power generation plant efficiency, a reduction in emissions, and a decrease in cost of electricity, while maintaining current state-of-the-art electricity generation systems' reliability, availability, and maintainability levels. Siemens Westinghouse technology development concentrated on the following areas: aerodynamic design, combustion, heat transfer/cooling design, engine mechanical design, advanced alloys, advanced coating systems, and single crystal (SC) alloy casting development. Success was achieved in designing and full scale verification testing of a high-pressure high-efficiency, compressor, airfoil clocking concept verification on a two-stage turbine rig test, high-temperature bond coat/TBC system development, and demonstrating feasibility of large SC turbine airfoil castings. The ATS program included successful completion of W501G engine development testing. This engine is the first step in the W501ATS engine introduction and incorporates many ATS technologies, such as closed-loop steam cooling, advanced compressor design, advanced sealing, and high-temperature materials and coatings. [DOI: 10.1115/1.1719030]

Continuous emissions monitoring of gas turbine engines in pipeline service have typically been monitored using either laboratory derived instruments (CEMS), or predicted using data from low cost sensors on the engines and algorithms generated by mapping engine performance (PEMS). A new cost-effective system developed under a program sponsored by the Gas Research Institute (Chicago) combines the advantages of both systems to monitor engine emissions in gas transmission service. This hybrid system is a sensor-based analyzer that uses a sensor array, including a newly developed N[O.sub.x] sensor, to directly monitor N[O.sub.x], CO, and [O.sub.2] emissions at the stack. The gases are measured hot and wet. The new systems were installed and tested on a gas-fired Rolls Royce Spey turbine engine and on Ingersoll-Rand KVG-410 and Cooper GMVH-10 reciprocating engines in gas transmission service. These systems passed the Relative Accuracy Test (Part B) required under U.S. EPA regulations (40 CFR 60).

Increased focus on air pollution from gas turbines in the Norwegian sector of the North Sea has resulted in taxes on C[O.sub.2]. Statements made by the Norwegian authorities imply regulations and/or taxes on N[O.sub.x] emissions in the near future. The existing C[O.sub.2] tax of NOK 0.82/S[m.sup.3] (US Dollars O. 12/S[m.sup.3]) and possible future tax on N[O.sub.x] are analyzed mainly with respect to operating and maintenance costs for the gas turbine. Depending on actual tax levels, the machine should be operated on full load/optimum thermal efficiency or part load to reduce specific exhaust emissions. Based on field measurements, exhaust emissions (C[O.sub.2], CO, N[O.sub.x], [N.sub.2]O, UHC, etc.) are established with respect to load and gas turbine performance, including performance degradation. Different N[O.sub.x] emission correlations are analyzed based on test results, and a proposed prediction model presented. The impact of machinery performance degradation on emission levels is particularly analyzed. Good agreement is achieved between measured and predicted N[O.sub.x] emissions from the proposed correlation. To achieve continuous exhaust emission control the proposed N[O.sub.x] model is implemented to the on-line condition monitoring system on the Sleipner A platform, rather than introducing sensitive emission sensors in the exhaust gas stack. The on-line condition monitoring system forms an important tool in detecting machinery condition/degradation and air pollution, and achieving optimum energy conservation.