Combustion System Update SGT5-4000F: Design, Testing and Validation

The effects and characteristics of hydrogen in SNG on gas turbine combustion using a diffusion type combustor

Hydrogen and ammonia are considered crucial carbon-free energy carriers optimally suited for seasonal chemical storage and balancing of the energy system. In this context, longitudinally-staged combustion systems represent an attractive technology in power generation for their capability of achieving low NOx emissions while conserving high load and, crucially, fuel flexibility at high thermal efficiency. Such two-stage combustion systems have been successfully implemented for natural gas firing of gas turbines and, more recently, have shown significant potential for clean and efficient hydrogen-firing operation. However, optimal operation with ammonia-based fuel mixtures is yet to be established. In a recent numerical modelling study (GT2023-103835), a novel Rich-Quench Lean (RQL) operational concept was proposed to burn a fuel-rich mixture of partially-decomposed ammonia and air (for equivalence ratios ϕ ∼ 1.1–1.2) in the first stage of a longitudinally-staged combustion system. Complete oxidation of the remaining (hydrogen) fuel is theoretically ensured by dilution-air addition downstream of the first stage combustor and it is confirmed by predictions from ongoing LES calculations (GT2024-128946). However, any operational concept based on these near-stoichiometric combustion conditions, while minimizing undesired prompt NOx and N2O formation by ammonia oxidation, can potentially result in significant, and certainly unpractical, thermal load on the first stage combustor liner that needs to be mitigated. In the present study, we exploit a newly developed reactors-network model to efficiently investigate the NOx-emissions performance of a longitudinally-staged combustion system fired with natural gas, hydrogen or ammonia. Firstly, the reactors network framework is validated with experimental, computational and other similar reactor network results in the literature. Secondly, the optimal air distribution within the longitudinally-staged combustion system is found for clean (low emissions) and efficient (complete fuel conversion) ammonia-firing operation. Thirdly, the consequences of such “ammonia-optimized” air distribution on flame stabilization and NOx emissions in more conventional natural gas- and hydrogen-firing operation are considered. Finally, an optimal air and fuel distribution is suggested for the longitudinally-staged combustion system on the basis that, while still ensuring robust flame stabilization and high turbine inlet temperature, it minimizes NOx emissions for all three fuels considered.

From the view point of future coal utilization technology for the thermal power generation systems, the coal gasification combined cycle system has drawn special interest recently. In the coal gasification combined cycle power generation system, it is necessary to develop a high temperature gas turbine combustor using a low-BTU gas (LBG) which has high thermal efficiency and low emissions. In Japan a development program of the coal gasification combined cycle power generation system has started in 1985 by the national government and Japanese electric companies. In this program, 1300°C class gas turbines will be developed. If the fuel gas cleaning system is a hot type, the coal gaseous fuel to be supplied to gas turbines will contain ammonia. Ammonia will be converted to nitric oxides in the combustion process in gas turbines. Therefore, low fuel-NOx combustion technology will be one of the most important research subjects. This paper describes low fuel-NOx combustion technology for 1300°C class gas turbine combustors using coal gaseous low-BTU fuel as well as combustion characteristics and carbon monoxide emission characteristics. Combustion tests were conducted using a full-scale combustor used for the 150 MW gas turbine at the atmospheric pressure. Furthermore, high pressure combustion tests were conducted using a half-scale combustor used for the 1 50 MW gas turbine.

Industrial gas turbines like the MGT6000 are often operated as power supply or as mechanical drives. In these applications, liquid fuels like “diesel fuel no. 2” can be used either as main fuel or as backup fuel if natural gas is not reliably available. The MAN gas turbines (MGT) operate with the advanced can combustion (ACC) system, which is capable of ultralow NOx emissions for gaseous fuels. This system has been further developed to provide dry dual fuel capability. In this paper, we describe the design and detailed experimental validation process of the liquid fuel injection, and its integration into the gas turbine package. A central lance with an integrated two-stage nozzle is employed as a liquid pilot stage, enabling ignition and startup of the engine on liquid fuel only. The pilot stage is continuously operated, whereas the bulk of the liquid fuel is injected through the premixed combustor stage. The premixed stage comprises a set of four decentralized nozzles based on fluidic oscillator atomizers, wherein atomization of the liquid fuel is achieved through self-induced oscillations. We present results illustrating the spray, hydrodynamic, and emission performance of the injectors. Extensive testing of the burner at atmospheric and full load high-pressure conditions has been performed, before verification within full engine tests. We show the design of the fuel supply and distribution system. Finally, we discuss the integration of the dual fuel system into the standard gas turbine package of the MGT6000.

Methane-fueled low NOx combustor research had been conducted under the Japanese supersonic/hypersonic propulsion research program. A unique form of premixture jet swirl combustor (PJSC) was proposed for the ultra low NOx combustor of a Mach 3 turbojet engine. Fuel-air mixing tests and fundamental combustion tests were conducted to obtain the design data and combustion characteristics in the first phase of the research. A single can-type combustor was fabricated and high-temperature and high-pressure combustion tests were carried out for the evaluation on NOx emission reduction capability of the PJSC concept in the second phase. In the final phase of research, a multisector combustor was fabricated and the performance demonstration test was conducted for the final evaluation of the pollutant exhaust emission goals and the combustor performance goals set in the HYPR project. The sequential three-phased program was completed successfully, and the project goals of NOx emission, combustion efficiency, pressure loss and exit gas temperature pattern factor at the Mach 3 cruise condition, together with the ICAO regulatory levels for supersonic aircraft at LTO conditions, were all achieved in the performance demonstration test.

Concerns about climate change have encouraged significant interest in concepts for ultralow or “zero”-emissions power generation systems. In a concept proposed by Clean Energy Systems, Inc., nitrogen is removed from the combustion air and replaced with steam diluent. In this way, formation of nitrogen oxides is prevented, and the exhaust stream can be separated into concentrated CO2 and water streams. The concentrated CO2 stream could then serve as input to a CO2 sequestration process. In this study, experimental data are reported from a full-scale combustion test using steam as the diluent in oxy-fuel combustion. This combustor represents the “reheat” combustion system in a steam cycle that uses a high and low-pressure steam expansion. The reheat combustor serves to raise the temperature of the low-pressure steam turbine inlet, similar to the reheat stage of a conventional steam power cycle. Unlike a conventional steam cycle, the reheat enthalpy is actually generated by oxy-fuel combustion in the steam flow. This paper reports on the unique design aspects of this combustor, as well as initial emissions and operating performance.

Concerns about climate change have encouraged significant interest in concepts for ultra-low or “zero”-emissions power generation systems. In a concept proposed by Clean Energy Systems, Inc., nitrogen is removed from the combustion air and replaced with steam diluent. In this way, formation of nitrogen oxides is prevented, and the exhaust stream can be separated into concentrated CO2 and water streams. The concentrated CO2 stream could then serve as input to a CO2 sequestration process. In this study, experimental data are reported from a fullscale combustion test using steam as the diluent in oxy-fuel combustion. This combustor represents the “reheat” combustion system in a steam cycle that uses a high and low-pressure steam expansion. The reheat combustor serves to raise the temperature of the low-pressure steam turbine inlet, similar to the reheat stage of a conventional steam power cycle. Unlike a conventional steam cycle, the reheat enthalpy is actually generated by oxy-fuel combustion in the steam flow. This paper reports on the unique design aspects of this combustor, as well as initial emissions and operating performance.

Following successful testing of the SGT-400 combustion system at atmospheric conditions with hydrogen enriched natural gas, a high pressure combustion test campaign was carried out at the Siemens test facility in Lincoln UK. Combustion performance at full engine operating conditions was studied, with the aim of demonstrating the capability of the standard SGT-400 combustion hardware to fire fuels with increased hydrogen content. Measurements consisted of: a pilot tip thermocouple to monitor the risk of flashback; pressure sensors to capture the combustion dynamics signature; and emissions instrumentation measuring NOx and CO. The combustor was also instrumented with thermocouples to monitor both the distribution of wall temperatures and potential locations of flashback when utilizing the highly reactive hydrogen enriched gas. The current paper reports the findings of the high pressure tests and compares with the atmospheric results that had been documented previously. Combustion behavior at full engine pressure and temperature was found to be consistent with atmospheric conditions. Pilot tip temperature increased with the hydrogen gas content due to the higher flame speed. Combustion dynamics shifted to a higher frequency for the hydrogen enriched gas, and heat release fluctuations increased. NOx emission also increased with the hydrogen blending due to the enhanced fuel reactivity. The high pressure tests demonstrated that the SGT-400 standard DLE combustion system can operate without risk of flashback for up to 20% vol hydrogen content. The next phase of the hydrogen program is to test a production engine using enriched gas and confirm its full operational characteristics. Extending the operational envelope of the standard DLE combustion system to hydrogen contents above 20% vol is also of interest.

Concerning the efforts in reducing the impact of fossil fuel combustion on climate change for power production utilizing gas turbine engines Flue Gas Recirculation (FGR) in combination with post combustion carbon capture and storage (CCS) is one promising approach. In this technique part of the flue gas is recirculated and introduced back into the compressor inlet reducing the flue gas flow (to the CCS) and increasing CO2 concentrations. Therefore FGR has a direct impact on the efficiency and size of the CO2 capture plant, with significant impact on the total cost. However, operating a GT under depleted O2 and increased CO2 conditions extends the range of normal combustor experience into a new regime. High pressure combustion tests were performed on a full scale single burner reheat combustor high-pressure test rig. The impact of FGR on NOx and CO emissions is analyzed and discussed in this paper. While NOx emissions are reduced by FGR, CO emissions increase due to decreasing O2 content although the SEV reheat combustor could be operated without problem over a wide range of operating conditions and FGR. A mechanism uncommon for GTs is identified whereby CO emissions increase at very high FGR ratios as stoichiometric conditions are approached. The feasibility to operate Alstom’s reheat engine (GT24/GT26) under FGR conditions up to high FGR ratios is demonstrated. FGR can be seen as continuation of the sequential combustion system which already uses a combustor operating in vitiated air conditions. Particularly promising is the increased flexibility of the sequential combustion system allowing to address the limiting factors for FGR operation (stability and CO emissions) through separated combustion chambers.

This paper focuses on the use of gas turbines (GTs) equipped with Dry Low Emissions (DLE) combustion technology in offshore oil and gas (O&G) applications. The paper presents information from offshore GT units and discusses improvements in operational reliability and fuel flexibility that have been achieved as a result of extensive testing on combustion systems. These improvements, coupled with significant NOx emissions reductions have made DLE gas turbines a viable alternative to non-DLE gas turbines, the latter of which have traditionally dominated the offshore market. Field operating data will be presented on three lightweight industrial gas turbine models that have been offered with DLE as a standard configuration for over 20 years. Currently, 394 units operate in offshore applications. The DLE configuration has accumulated more than 22 million hours of service. The paper outlines the performance, reliability, and fuel profiles of the current offshore fleet, confirming that DLE combustion systems have now achieved reliability on par with non-DLE combustion systems. A brief review of the testing experience proving the reliability and the range of fuels that can be burned within the DLE system will also be discussed in the paper.

Due to increasing environmental concerns, clean technology has become a key feature in industrial gas turbines. Swirler design is directly associated with the combustion performance for its roles in fuel distribution and flame stability. In this study, the development process of three new conceptual swirlers from Samsung Techwin is presented. Each swirler has unique features to enhance fuel-to-air mixing; Swirler 1 uses tangential air-bypass, Swirler 2 minimizes pressure loss using impeller-like design, and Swirler 3 has combined flow characteristics of axial and radial swirlers. Using extensive computational fluid dynamics (CFD) analysis, lead time and cost in manufacturing the prototypes were significantly reduced. The numerical methods were verified with a lab-scale combustion test; particle image velocimetry (PIV) measurement of cold flow, direct flame images, and OH planar laser induced fluorescence (PLIF) images were compared with result of large-eddy simulation (LES), and they showed good agreement. After design optimization using CFD, full-scale combustion tests were performed for all three swirlers. Flame from each swirler was visualized using a cylindrical quartz liner; direct images and OH chemiluminescence images of flames were obtained. Flame stability and blow-off limit at various air load were examined by gradually lowering the equivalence ratio. NOx and CO concentration were measured at the exhaust. All three swirlers satisfied low NOx and CO levels at the design conditions. The performance maps bounded by the NOx and CO limits and blow-off limit were obtained for all swirlers. Further efforts to maximize the combustors performance will be made.

The momentum flux ratio (MFR) significantly affects the mixing characteristics and combustion efficiency of propellants in rocket engine injectors. The spray characteristics of three gas-centered swirl-coaxial injectors used in a full-scale combustion test were investigated according to the change in the momentum flux ratio. The difference in combustion efficiency was analyzed through the comparison with combustion test results using spray visualization and quantification. The spray cross-sectional shape and droplet distribution were measured using a structured laser illumination planar imaging technique. As the swirl effect was more apparent at a low MFR, the flow rate of the liquid that was sprayed outside was high. The flow rate of the liquid sprayed around the gas injection increased with the MFR. The Sauter mean diameter (SMD) of each injector liquid spray was obtained using the laser shadow imaging method. The SMD decreased as the MFR of all injector types increased, and the injector with a high liquid flow rate and small SMD injected towards the gas center exhibited higher combustion efficiency than the injector with a dominant liquid spray and the large SMD at a large injection angle. The outcomes of the study could help contribute to the increase in the combustion efficiency of the full-scale staged combustion cycle engine combustor.

The objectives of this project include: (1) the development of an engineering data base which will provide detailed information on the properties of BCFs influencing combustion, ash deposition, ash erosion, particulate collection, and missions; and (2) the application of this technical data base to predict the performance and economic impacts of firing the BCFs in various commercial boiler designs. The technical approach used to develop the technical data includes: bench-scale fuel property, combustion, and ash deposition tests; pilot-scale combustion and ash effects test; and full-scale combustion tests.

97/05132 Toxic substances from coal combustion: laboratory studies: Senior, C. L. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13, (2), 1344–1349

Use of chemical fractionation to understand partitioning of biomass ash constituents during co-firing in fluidized bed combustion