Hydrogen Enriched Combustion Testing of Siemens Industrial SGT-400 at Atmospheric Conditions

Author(s):  
Kam-Kei Lam ◽  
Philipp Geipel ◽  
Jenny Larfeldt

In order to further extend the turbine fuel flex capability, a test under atmospheric conditions of a full-scale SGT-400 burner was performed to study the combustion behavior when operating on hydrogen enriched natural gas (NG). A high speed camera was installed in the rig to investigate the flame dynamics on different operation conditions. NOx emissions were measured for all presented conditions. The combustion system was instrumented with thermocouples on all the key locations to allow flame position monitoring and to avoid flame attachment on the hardware. Further measurements included static pressure probes to monitor combustor pressure drop. The test was conducted in a systematic matrix format to include the most important combustion parameters in order to identify their individual effects on the combustion behaviors. The quantity of hydrogen in natural gas, fuel split, air preheat temperature, air reference velocity and flame temperature were the combustion related variables studied in the presented test campaign. The volumetric hydrogen quantity could be increased to 30% maintaining stable operation for all measured conditions. Higher hydrogen contents up to 80 vol. % were reached without flash back tendency. A glowing spark igniter prevented testing at even higher hydrogen contents. Hydrogen enriched gas showed higher NOx emissions and improved blowout limit. Hydrogen blending in the fuel also reduced the combustor pressure drop, lowered the prechamber temperature and raised the pilot tip temperature.

Author(s):  
Kam-Kei Lam ◽  
Philipp Geipel ◽  
Jenny Larfeldt

In order to further extend the turbine fuel flex capability, a test under atmospheric conditions of a full-scale SGT-400 burner was performed to study the combustion behavior when operating on hydrogen enriched natural gas. A high speed camera was installed in the rig to investigate the flame dynamics on different operation conditions. NOx emissions were measured for all presented conditions. The combustion system was instrumented with thermocouples on all the key locations to allow flame position monitoring and to avoid flame attachment on the hardware. Further measurements included static pressure probes to monitor combustor pressure drop. The test was conducted in a systematic matrix format to include the most important combustion parameters in order to identify their individual effects on the combustion behaviors. The quantity of hydrogen in natural gas, fuel split, air preheat temperature, air reference velocity and flame temperature were the combustion related variables studied in the presented test campaign. The volumetric hydrogen quantity could be increased to 30% maintaining stable operation for all measured conditions. Higher hydrogen contents up to 80 vol-% were reached without flash back tendency. A glowing spark igniter prevented testing at even higher hydrogen contents. Hydrogen enriched gas showed higher NOx emissions and improved blowout limit. Hydrogen blending in the fuel also reduced the combustor pressure drop, lowered the prechamber temperature and raised the pilot tip temperature.


Author(s):  
T. Sidwell ◽  
K. Casleton ◽  
D. Straub ◽  
D. Maloney ◽  
G. Richards ◽  
...  

The U.S. Department of Energy Turbines Program has established very stringent NOx emissions goals of less than 3 ppmv for future turbine power generation. These future turbine power plants may operate on hydrogen-rich fuels, such as coal-derived synthesis gas (syngas), or pure hydrogen derived from shifting the syngas. Achieving these goals is expected to require improved combustor concepts which may be dramatically different than current combustor designs. Significant and costly experimental testing is usually required to assess new combustor concepts. Ideally, new concepts could be evaluated with numeric simulations to reduce development time and cost. However, current simulation capabilities are not sufficient to reliably capture the effects of fuel variations on flame extinction, emissions levels, and dynamic stability. Furthermore, very little data with controlled boundary conditions are available to check numeric predictions at actual turbine engine conditions, or simply to assess combustor performance without ambiguous boundary conditions. This paper presents a description of the development and operation of an optically-accessible research combustor, which is designed to provide fundamental combustion data at elevated pressure and inlet air temperature, and with precisely determined thermal, acoustic, and flow boundary conditions. The effects of fuel composition variations are investigated by blending of controlled quantities of hydrogen with natural gas. Recent test results — emissions data, dynamics data, and heat losses for hydrogen addition from 0 to 40% by fuel volume at two combustor pressures — and a description of future testing are also presented. The results show that the addition of hydrogen to natural gas in percentages as low as 5% of total fuel volume can significantly decrease the lean extinction limit, and promote stable operation at lower equivalence ratios while promoting lower NOx emissions. Dynamic pressures were measured, but combustion dynamics were not present due to the combustor configuration. The effect of heat losses on flame temperature and emissions were quantified.


Author(s):  
Brian Hollon ◽  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Vincent McDonell ◽  
Howard Lee

This paper discusses the development and testing of a full-scale micro-mixing lean-premix injector for hydrogen and syngas fuels that demonstrated ultra-low emissions and stable operation without flashback for high-hydrogen fuels at representative full-scale operating conditions. The injector was fabricated using Macrolamination technology, which is a process by which injectors are manufactured from bonded layers. The injector utilizes sixteen micro-mixing cups for effective and rapid mixing of fuel and air in a compact package. The full scale injector is rated at 1.3 MWth when operating on natural gas at 12.4 bar (180 psi) combustor pressure. The injector operated without flash back on fuel mixtures ranging from 100% natural gas to 100% hydrogen and emissions were shown to be insensitive to operating pressure. Ultra-low NOx emissions of 3 ppm were achieved at a flame temperature of 1750 K (2690 °F) using a fuel mixture containing 50% hydrogen and 50% natural gas by volume with 40% nitrogen dilution added to the fuel stream. NOx emissions of 1.5 ppm were demonstrated at a flame temperature over 1680 K (2564 °F) using the same fuel mixture with only 10% nitrogen dilution, and NOx emissions of 3.5 ppm were demonstrated at a flame temperature of 1730 K (2650 °F) with only 10% carbon dioxide dilution. Finally, using 100% hydrogen with 30% carbon dioxide dilution, 3.6 ppm NOx emissions were demonstrated at a flame temperature over 1600 K (2420 °F). Superior operability was achieved with the injector operating at temperatures below 1470 K (2186 °F) on a fuel mixture containing 87% hydrogen and 13% natural gas. The tests validated the micro-mixing fuel injector technology and the injectors show great promise for use in future gas turbine engines operating on hydrogen, syngas or other fuel mixtures of various compositions.


Author(s):  
Jochen R. Kalb ◽  
Thomas Sattelmayer

The technological objective of this work is the development of a lean-premixed burner for natural gas. Sub-ppm NOx emissions can be accomplished by shifting the lean blowout limit (LBO) to slightly lower adiabatic flame temperatures than the LBO of current standard burners. This can be achieved with a novel burner concept utilizing periodic flue gas recirculation: Hot flue gas is admixed to the injected premixed fresh mixture with a mass flow rate of comparable magnitude, in order to achieve self-ignition. The subsequent combustion of the diluted mixture again delivers flue gas. A fraction of the combustion products is then admixed to the next stream of fresh mixture. This process pattern is to be continued in a cyclically closed topology, in order to achieve stable combustion of e.g. natural gas in a temperature regime of very low NOx production. The principal ignition behavior and NOx production characteristics of one sequence of the periodic process was modeled by an idealized adiabatic system with instantaneous admixture of partially or completely burnt flue gas to one stream of fresh reactants. With the CHEMKIN-II package a reactor network consisting of one perfectly stirred reactor (PSR, providing ignition in the first place) and two plug flow reactors (PFR) has been used. The effect of varying burnout and the influence of the fraction of admixed flue gas have been evaluated. The simulations have been conducted with the reaction mechanism of Miller and Bowman and the GRI-Mech 3.0 mechanism. The results show that the high radical content of partially combusted products leads to a massive decrease of the time required for the formation of the radical pool. As a consequence, self-ignition times of 1 ms are achieved even at adiabatic flame temperatures of 1600 K and less, if the flue gas content is about 50%–60% of the reacting flow after mixing is complete. Interestingly, the effect of radicals on ignition is strong, outweighs the temperature deficiency and thus allows stable operation at very low NOx emissions.


2004 ◽  
Vol 128 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Jochen R. Kalb ◽  
Thomas Sattelmayer

The technological objective of this work is the development of a lean-premixed burner for natural gas. Sub-ppm NOx emissions can be accomplished by shifting the lean blowout limit (LBO) to slightly lower adiabatic flame temperatures than the LBO of current standard burners. This can be achieved with a novel burner concept utilizing spatially periodic recirculation of combustion products: Hot combustion products are admixed to the injected premixed fresh mixture with a mass flow rate of comparable magnitude, in order to achieve self-ignition. The subsequent combustion of the diluted mixture again delivers products. A fraction of these combustion products is then admixed to the next stream of fresh mixture. This process pattern is to be continued in a cyclically closed topology, in order to achieve stable combustion of, for example, natural gas in a temperature regime of very low NOx production. The principal ignition behavior and NOx production characteristics of one sequence of the periodic process was modeled by an idealized adiabatic system with instantaneous admixture of partially or completely burnt combustion products to one stream of fresh reactants. With the CHEMKIN-II package, a reactor network consisting of one perfectly stirred reactor (PSR, providing ignition in the first place) and two plug flow reactors (PFR) has been used. The effect of varying burnout and the influence of the fraction of admixed flue gas has been evaluated. The simulations have been conducted with the reaction mechanism of Miller and Bowman and the GRI-Mech 3.0 mechanism. The results show that the high radical content of partially combusted products leads to a massive decrease of the time required for the formation of the radical pool. As a consequence, self-ignition times of 1 ms are achieved even at adiabatic flame temperatures of 1600 K and less, if the flue gas content is about 50–60% of the reacting flow after mixing is complete. Interestingly, the effect of radicals on ignition is strong, outweighs the temperature deficiency and thus allows stable operation at very low NOx emissions.


Author(s):  
Prabhu Balasubramanian ◽  
Satish G. Kandlikar

The use of phase change heat transfer in parallel minichannels and microchannels is one of the solutions proposed for cooling high heat flux systems. The increase in pressure drop in a two phase system is one of the problems, that need to be studied in detail before proceeding to any design phase. The pressure drop fluctuations in a network of parallel channels connected by a common head need to be addressed for stable operation of flow boiling systems. The current work focuses on studying the pressure-drop fluctuations and flow instabilities in a set of six parallel rectangular minichannels, each with 333 μm hydraulic diameter. Demonized and degassed water was used for all the experiments. Pressure fluctuations are recorded and signal analysis is performed to find the dominant frequencies and their amplitudes. These pressure fluctuations are then mapped to their corresponding flow patterns observed using a high speed camera. The results help us to relate pressure fluctuations to different flow characteristics, and their effect on flow instability.


Author(s):  
Matteo Cerutti ◽  
Roberto Modi ◽  
Danielle Kalitan ◽  
Kapil K. Singh

As government regulations become increasingly strict with regards to combustion pollutant emissions, new gas turbine combustor designs must produce lower NOx while also maintaining acceptable combustor operability. The design and implementation of an efficient fuel/air premixer is paramount to achieving low emissions. Options for improving the design of a natural gas fired heavy-duty gas turbine partially premixed fuel nozzle have been considered in the current study. In particular, the study focused on fuel injection and pilot/main interaction at high pressure and high inlet temperature. NOx emissions results have been reported and analyzed for a baseline nozzle first. Available experience is shared in this paper in the form of a NOx correlative model, giving evidence of the consistency of current results with past campaigns. Subsequently, new fuel nozzle premixer designs have been investigated and compared, mainly in terms of NOx emissions performance. The operating range of investigation has been preliminarily checked by means of a flame stability assessment. Adequate margin to lean blow out and thermo-acoustic instabilities onset has been found while also maintaining acceptable CO emissions. NOx emission data were collected over a variety of fuel/air ratios and pilot/main splits for all the fuel nozzle configurations. Results clearly indicated the most effective design option in reducing NOx. In addition, the impact of each design modification has been quantified and the baseline correlative NOx emissions model calibrated to describe the new fuel nozzles behavior. Effect of inlet air pressure has been evaluated and included in the models, allowing the extensive use of less costly reduced pressure test campaigns hereafter. Although the observed effect of combustor pressure drop on NOx is not dominant for this particular fuel nozzle, sensitivity has been performed to consolidate gathered experience and to make the model able to evaluate even small design changes affecting pressure drop.


Author(s):  
Ralf v. d. Bank ◽  
Thomas Schilling

Within the EC framework 5 programme LOPOCOTEP Rolls-Royce Deutschland (RRD) continues to develop Lean Premix (Partially Pre-vaporized) (LP(P)) combustion systems to implement the ACARE goals to achieve further NOx reductions compared with the best combustor technology currently available. The results from the previous EC framework 4 programme LowNOx III had been used to calculate DpNOx/Foo values for an ICAO LTO cycle. The result showed that 40% from the CAEP II limit can be achieved for a medium size fan engine. Cycle and mission calculations have risen the hope that total NOx emissions can be reduced by more than 70% for a 800 NM medium range flight. The objective of the current programme is to further reduce the NOx emissions (30% CAEP II) for a more severe engine cycle and therefore a larger burner size compared to the LowNOx III programme. Flash-back and auto-ignition under all operation conditions have to be prevented. A scaling law was derived from the existing database and applied on an LP(P) module which was then tested at pressures of up to 35 bar and temperatures of up to 900 K in a single sector test rig. The applicability of the scaling laws was confirmed. Testing at take-off conditions showed single digit EINOx between 2 and 4 g/kg depending on the actual swirl-generator configuration. However, poor weak extinction was observed and gave concern regarding operability. The decision was taken to redirect the development efforts to improve operability and to increase the lean blow out (LBO) air-fuel-ratio (AFR). This led to the integration of an internal, centrally arranged pressure-swirl atomizer as pilot diffusion burner into the LP(P) burners. Due to an optimization of the aerodynamics of the LP(P) module which was performed at the same time the dimensions of the burner could be reduced while the effective area was kept constant. This burner was then initially tested at atmospheric conditions to address ignition and LBO limit. This burner showed excellent ground ignition capability at air temperatures as low as 350 K. In the best configuration one spark was sufficient. The testing of the lean extinction limit was repeatedly verified. At 350 K the LBO was always in the range between 110–130 OAFR. More detailed investigations on emissions, flash-back and auto-ignition characteristics will be performed at ONERA and Lund University.


2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771138 ◽  
Author(s):  
Eunhye Song ◽  
Juhun Song

The turbo-pump and turbine are driven by liquid fuel fed into a gas generator, where the fuel is oxidized with a liquid oxidizing agent. For stable operation of the turbine, the combustion temperature of the gas generator must be maintained below 1000 K. The thermodynamic characteristics of kerosene oxidation in the gas generator must be understood to optimize the design and operation conditions of the liquid-fueled rocket engine system. Herein, the 3-species surrogate mixture model for kerosene was selected, and the detailed Dagaut’s kerosene oxidation mechanism consisting of 225 chemical species and 1800 reversible chemical reactions was utilized. The exit gas temperature and product gas composition in the gas generator under fuel-rich conditions were simulated by applying the perfectly stirred reactor model. The perfectly stirred reactor model was used in combination with the liquid spray model for evaporation of the droplets and the two-temperature model for evaluation of the flame temperature separately from the locally averaged reactor temperature. The theoretical prediction of the gas species fraction and soot yield could be improved by applying the tar cracking mechanism, where the reaction characteristics under high temperature were taken into account.


Author(s):  
M. Bianco ◽  
S. M. Camporeale ◽  
B. Fortunato

Evaporative cycles, such as Recuperated Water lnjected (RWI) cycle, Humid Air Turbine (HAT) cycle, Cascaded Humidified Advanced Turbine (CHAT) offer the attractive possibility to increase plant efficiency without the use of a steam turbine, necessary for gas-steam combined cycles, appearing, therefore, as an interesting solution for industrial power applications such as electric utilities and independent power producers. It is expected that water addition may contribute to reduce NOx emissions in premixed flame combustors. In order to analyse this solution, a lean-bum combustor, fed with an homogeneous mixture formed by methane and humid air, has been analysed through CFD simulations, in order to predict velocity field, temperatures and emissions. The study has been carried out under the hypothesis of a two-dimensional, axisymmetric combustion chamber assuming, as set of operation conditions, atmospheric pressure, inlet temperature of 650 K, fuel-air equivalence ratio of the methane-air mixture ranging from 0.5 to 0.7 and water-air mass ratio varying from 0% to 5%. In the simulation, the presence of turbulence in the flow has been taken into account using a RNG k-ε model, whilst the chemical behaviour of the system has been described by means of a five-step global reduced mechanism including the oxidation mechanism and the NOx formation mechanism. The analysis of the results shows that the moisture in the premixed flow reduces both NOx and CO emissions at constant equivalence ratio; moreover the lean blow-out limit is shifted toward higher equivalence ratio. The main effect of the water seems to be the increase of the specific heat the mixture which causes a reduction in flame temperature, slowing the chemical reactions responsible of NOx formation. The reasonable agreement has been found between the simulation results concerning NOx emissions and recent experimental results carried out on premixed flamed with humid air. A discussion is also provided about the adopted turbulence models and their influence on the emission results.


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