Experimental Investigation of the Liquid Fuel Evaporation in a Premix Duct for Lean Premixed and Prevaporized Combustion

1997 ◽  
Vol 119 (4) ◽  
pp. 815-821 ◽  
Author(s):  
M. Brandt ◽  
K. O. Gugel ◽  
C. Hassa
Keyword(s):  
Experimental Investigation ◽  
Air Temperature ◽  
Flow Rate ◽  
Liquid Fuel ◽  
Operating Conditions ◽  
Dispersion Characteristics ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Lean Premixed ◽  
Fuel Evaporation

Liquid fuel evaporation was investigated in a premix duct, operating at conditions expected for lean premixed and prevaporized combustion. Results from a flat prefilming airblast atomizer are presented. Kerosine Jet A was used in all experiments. Air pressure, air temperature, and liquid fuel flow rate were varied separately; their relative influences on atomization, evaporation, and fuel dispersion are discussed. The results show that at pressures up to 15 bars and temperatures up to 850 K, nearly complete evaporation of the fuel was achieved, without autoignition of the fuel. For the configuration tested, the fuel distributions of the liquid and evaporated fuel show very little difference in their dispersion characteristics and were not much affected by a variation of the operating conditions.

scholarly journals Experimental Investigation of the Liquid Fuel Evaporation in a Premix Duct for Lean Premixed and Prevaporized Combustion

1996 ◽  
Author(s):  
Michael Brandt ◽  
Kay O. Gugel ◽  
Christoph Hassa
Keyword(s):  
Experimental Investigation ◽  
Air Temperature ◽  
Flow Rate ◽  
Liquid Fuel ◽  
Operating Conditions ◽  
Dispersion Characteristics ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Lean Premixed ◽  
Fuel Evaporation

Liquid fuel evaporation was investigated in a premix duct, operating at conditions expected for lean premixed and prevaporized combustion. Results from a flat prefilming airblast atomizer are presented. Kerosine Jet A was used in all experiments. Air pressure, air temperature and liquid fuel flow rate were varied separately, their relative influences on atomization, evaporation and fuel dispersion are discussed. The results show, that at pressures up to 15 bars and temperatures up to 850 K, nearly complete evaporation of the fuel was achieved, without autoignition of the fuel. For the configuration tested, the fuel distributions of the liquid and evaporated fuel sbow very little differences in their dispersion characteristics and were not much affected by a variation of the operating conditions.

Drive Train Over-Speed Prediction for Gas Fuel Based Gas Turbine Power Generation Units

2015 ◽  
Author(s):  
M. Moinul I. Forhad ◽  
Mark Bloomberg
Keyword(s):  
Power Generation ◽  
Flow Rate ◽  
Circuit Breaker ◽  
Angular Acceleration ◽  
Operating Conditions ◽  
Drive Train ◽  
Fuel Flow Rate ◽  
Fuel Gas ◽  
Fuel Flow ◽  
Gas System

Under all circumstances, an engine and its driven equipment(s) must be prevented from operating at a speed above the maximum allowed speed — to ensure the safety of the equipment, plant and its personnel. However, meeting this requirement is particularly challenging for power generation units where the drive train is composed of electric generators driven by free power turbines (i.e. aerodynamically-coupled power turbines), since during load-shed events or circuit breaker failure, full loss of load happens almost instantly. During these events, usually the Fuel Metering Valve is fully closed by the Engine Control System and the Fuel Isolation Valve is closed by the safety system. But, fuel gas continues to flow to the system during the closing of the valves, and furthermore, the fuel gas trapped in the piping between the valve and the fuel injectors still has enough pressure to flow to the combustion chamber and add energy to the system, which at that point has almost no external load, thus likely to cause an over-speeding of the drive-train. This paper is to report a dynamic model created for drive-train over-speed predictions. In this model, fuel flow rate to the engine is calculated based on the principle of conservation of mass together with the fuel gas equation of state. The calculated fuel flow rate is then used to find the amount of power supply to the drive train, which in the next step is converted to the torque applied on the shaft. Finally, Newton’s second law is used to determine the angular acceleration and the angular speed. This approach is applied to two different variations of the Industrial RB211 Engine — the DLE (Dry Low Emission) RB211 and Non-DLE RB211 — which have different designs of the fuel gas system and the burners. For both cases, the results using the modeling approach presented in this paper demonstrate around 99% agreement with the actual measured over-speed values recorded during trip events. The model allows studying the drive train speed for different operating conditions and failure cases, and also makes it easy to understand and quantify the effect of fuel gas system parameter variation on drive-train over-speed.

Application of Dielectric Barrier Discharge to Improve the Flashback Limit of a Lean Premixed Dump Combustor

2011 ◽  
Author(s):  
Philippe Versailles ◽  
Wajid Ali Chishty ◽  
Huu Duc Vo
Keyword(s):  
Natural Gas ◽  
Dielectric Barrier Discharge ◽  
Flow Rate ◽  
Gas Turbines ◽  
Barrier Discharge ◽  
Operating Conditions ◽  
Diffusion Type ◽  
Dielectric Barrier ◽  
Fuel Flow ◽  
Lean Premixed

In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NOx emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of Dielectric Barrier Discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5% of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions.

An Experimental Investigation of HCCI Combustion Stability Using N-Heptane

2007 ◽  
Author(s):  
Hailin Li ◽  
W. Stuart Neill ◽  
Wally Chippior ◽  
Joshua D. Taylor
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Combustion Process ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Air Temperatures ◽  
Wide Range ◽  
Cyclic Variations

In this paper, cyclic variations in the combustion process of a single-cylinder HCCI engine operated with n-heptane were measured over a range of intake air temperatures and pressures, compression ratios, air/fuel ratios, and exhaust gas recirculation (EGR) rates. The operating conditions produced a wide range of combustion timings from overly advanced combustion where knocking occurred to retarded combustion where incomplete combustion was detected. Cycle-to-cycle variations were shown to depend strongly on the crank angle phasing of 50% heat release and fuel flow rate. Combustion instability increased significantly with retarded combustion phasing especially when the fuel flow rate was low. Retarded combustion phasing can be tolerated when the fuel flow rate is high. It was also concluded that the cyclic variations in imep are primarily due to the variations in the total heat released from cycle-to-cycle. The completeness of the combustion process in one cycle affects the in-cylinder conditions and resultant heat release in the next engine cycle.

Large Eddy Simulation of a Bluff-Body–Stabilized Flame With Close-Coupled Liquid Fuel Injection

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Andrew G. Smith ◽  
Suresh Menon ◽  
Jeffery A. Lovett ◽  
Baris A. Sen
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Liquid Fuel ◽  
Bluff Body ◽  
Fuel Flow Rate ◽  
Flow Rates ◽  
Fuel Mass ◽  
Fuel Flow ◽  
Large Eddy ◽  
Mass Flow Rates

Large eddy simulations (LES) are performed of a bluff-body–stabilized flame with discrete liquid fuel injectors located just upstream of the bluff-body trailing edge in a so-called “close-coupled” configuration. Nonreacting and reacting simulations of the Georgia Tech single flameholder test rig [Cross et al., 2010, “Dynamics of Non-premixed Bluff Body-Stabilized Flames in Heated Air Flow,” Proceedings of ASME Turbo Expo, Paper No. GT2010-23059] are conducted using an Eulerian–Lagrangian approach with a finite volume solver. Experimental data is first used to characterize the boundary conditions under nonreacting conditions before simulating reacting test cases at two different fuel mass flow rates. The two fuel mass flow rates not only result in different global equivalence ratios but different spatial distributions of fuel, especially in the near-field wake of the bluff body. The differing spatial distribution of fuel results in two distinct flame dynamics; at the high-fuel flow rate, large-scale sinusoidal Bérnard/von-Kármán (BVK) oscillations are observed, whereas a symmetric flame is seen under the low-fuel flow rate condition.

Application of Dielectric Barrier Discharge to Improve the Flashback Limit of a Lean Premixed Dump Combustor

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
Philippe Versailles ◽  
Wajid Ali Chishty ◽  
Huu Duc Vo
Keyword(s):  
Natural Gas ◽  
Dielectric Barrier Discharge ◽  
Flow Rate ◽  
Gas Turbines ◽  
Barrier Discharge ◽  
Operating Conditions ◽  
Diffusion Type ◽  
Dielectric Barrier ◽  
Fuel Flow ◽  
Lean Premixed

In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NOx emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of dielectric barrier discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5% of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions.

Dynamic Simulation of a HRSG System for a Given Start-Up/Shut Down Curve

2011 ◽  
Author(s):  
Hun Cha ◽  
Yoo Seok Song ◽  
Kyu Jong Kim ◽  
Jung Rae Kim ◽  
Sung Min KIM
Keyword(s):  
Dynamic Analysis ◽  
Gas Turbine ◽  
Flow Rate ◽  
Exhaust Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Start Up ◽  
Gas Turbine Exhaust ◽  
Main Steam ◽  
Duct Burner

An inappropriate design of HRSG (Heat Recovery Steam Generator) may lead to mechanical problems including the fatigue failure caused by rapid load change such as operating trip, start-up or shut down. The performance of HRSG with dynamic analysis should be investigated in case of start-up or shutdown. In this study, dynamic analysis for the HRSG system was carried out by commercial software. The HRSG system was modeled with HP, IP, LP evaporator, duct burner, superheater, reheater and economizer. The main variables for the analysis were the temperature and mass flow rate from gas turbine and fuel flow rate of duct burner for given start-up (cold/warm/hot) and shutdown curve. The results showed that the exhaust gas condition of gas turbine and fuel flow rate of duct burner were main factors controlling the performance of HRSG such as flow rate and temperature of main steam from final superheater and pressure of HP drum. The time delay at the change of steam temperature between gas turbine exhaust gas and HP steam was within 2 minutes at any analysis cases.

Model Analysis of Syngas Combustion and Emissions for a Micro Gas Turbine

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Chi-Rong Liu ◽  
Hsin-Yi Shih
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Heat Input ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Fuel Flow Rate ◽  
Micro Gas Turbine ◽  
Fuel Flow ◽  
Temperature Distributions ◽  
Flame Structures

The purpose of this study is to investigate the combustion and emission characteristics of syngas fuels applied in a micro gas turbine, which is originally designed for a natural gas fired engine. The computation results were conducted by a numerical model, which consists of the three-dimension compressible k–ε model for turbulent flow and PPDF (presumed probability density function) model for combustion process. As the syngas is substituted for methane, the fuel flow rate and the total heat input to the combustor from the methane/syngas blended fuels are varied with syngas compositions and syngas substitution percentages. The computed results presented the syngas substitution effects on the combustion and emission characteristics at different syngas percentages (up to 90%) for three typical syngas compositions and the conditions where syngas applied at fixed fuel flow rate and at fixed heat input were examined. Results showed the flame structures varied with different syngas substitution percentages. The high temperature regions were dense and concentrated on the core of the primary zone for H2-rich syngas, and then shifted to the sides of the combustor when syngas percentages were high. The NOx emissions decreased with increasing syngas percentages, but NOx emissions are higher at higher hydrogen content at the same syngas percentage. The CO2 emissions decreased for 10% syngas substitution, but then increased as syngas percentage increased. Only using H2-rich syngas could produce less carbon dioxide. The detailed flame structures, temperature distributions, and gas emissions of the combustor were presented and compared. The exit temperature distributions and pattern factor (PF) were also discussed. Before syngas fuels are utilized as an alternative fuel for the micro gas turbine, further experimental testing is needed as the modeling results provide a guidance for the improved designs of the combustor.

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