scholarly journals Effects of Injector Recess and Combustion Chamber Length on Combustion Stability of Swirl Coaxial Injectors

2020 ◽  
Vol 24 (1) ◽  
pp. 24-33
Author(s):  
Sujin Bak ◽  
Donghyun Hwang ◽  
Kyubok Ahn ◽  
Youngbin Yoon
Keyword(s):  
Combustion Chamber ◽  
Combustion Stability ◽  
Chamber Length

Siemens SGT-800 Industrial Gas Turbine Enhanced to 50MW: Combustor Design Modifications, Validation and Operation Experience

2013 ◽  
Author(s):  
Daniel Lörstad ◽  
Annika Lindholm ◽  
Jan Pettersson ◽  
Mats Björkman ◽  
Ingvar Hultmark
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Cooling System ◽  
Good Condition ◽  
Combined Cycle ◽  
Combustion Stability ◽  
Combustion System ◽  
Design Work ◽  
Engine Operation ◽  
Cooling Air

Siemens Oil & Gas introduced an enhanced SGT-800 gas turbine during 2010. The new power rating is 50.5MW at a 38.3% electrical efficiency in simple cycle (ISO) and best in class combined-cycle performance of more than 55%, for improved fuel flexibility at low emissions. The updated components in the gas turbine are interchangeable from the existing 47MW rating. The increased power and improved efficiency are mainly obtained by improved compressor airfoil profiles and improved turbine aerodynamics and cooling air layout. The current paper is focused on the design modifications of the combustor parts and the combustion validation and operation experience. The serial cooling system of the annular combustion chamber is improved using aerodynamically shaped liner cooling air inlet and reduced liner rib height to minimize the pressure drop and optimize the cooling layout to improve the life due to engine operation hours. The cold parts of the combustion chamber were redesigned using cast cooling struts where the variable thickness was optimized to maximize the cycle life. Due to fewer thicker vanes of the turbine stage #1, the combustor-turbine interface is accordingly updated to maintain the life requirements due to the upstream effect of the stronger pressure gradient. Minor burner tuning is used which in combination with the previously introduced combustor passive damping results in low emissions for >50% load, which is insensitive to ambient conditions. The combustion system has shown excellent combustion stability properties, such as to rapid load changes and large flame temperature range at high loads, which leads to the possibility of single digit Dry Low Emission (DLE) NOx. The combustion system has also shown insensitivity to fuels of large content of hydrogen, different hydrocarbons, inerts and CO. Also DLE liquid operation shows low emissions for 50–100% load. The first SGT-800 with 50.5MW rating was successfully tested during the Spring 2010 and the expected performance figures were confirmed. The fleet leader has, up to January 2013, accumulated >16000 Equivalent Operation Hours (EOH) and a planned follow up inspection made after 10000 EOH by boroscope of the hot section showed that the combustor was in good condition. This paper presents some details of the design work carried out during the development of the combustor design enhancement and the combustion operation experience from the first units.

Lean-Burn Characteristics of a Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition

2018 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Fuel Injector ◽  
Heavy Duty ◽  
Lean Burn ◽  
Spark Timing ◽  
Heavy Duty Diesel

Increased utilization of natural-gas (NG) in the transportation sector can decrease the use of petroleum-based fuels and reduce greenhouse-gas emissions. Heavy-duty diesel engines retrofitted to NG spark ignition (SI) can achieve higher efficiencies and low NOx, CO, and HC emissions when operated under lean-burn conditions. To investigate the SI lean-burn combustion phenomena in a bowl-in-piston combustion chamber, a conventional heavy-duty direct-injection CI engine was converted to SI operation by replacing the fuel injector with a spark plug and by fumigating NG in the intake manifold. Steady-state engine experiments and numerical simulations were performed at several operating conditions that changed spark timing, engine speed, and mixture equivalence ratio. Results suggested a two-zone NG combustion inside the diesel-like combustion chamber. More frequent and significant late burn (including double-peak heat release rate) was observed for advanced spark timing. This was due to the chamber geometry affecting the local flame speed, which resulted in a faster and thicker flame in the bowl but a slower and thinner flame in the squish volume. Good combustion stability (COVIMEP < 3 %), moderate rate of pressure rise, and lack of knocking showed promise for heavy-duty CI engines converted to NG SI operation.

The Effect of Fuel Types and Admission Method Upon Combustion Efficiency

1959 ◽  
Vol 81 (4) ◽  
pp. 423-426
Author(s):  
H. N. McManus ◽  
W. E. Ibele ◽  
T. E. Murphy
Keyword(s):  
Combustion Chamber ◽  
Air Flow ◽  
Flow Patterns ◽  
Combustion Efficiency ◽  
Spray Nozzle ◽  
Optimum Size ◽  
Fuel Type ◽  
Chamber Length ◽  
Different Types ◽  
Improved Performance

A series of tests to determine the effect of combustion-chamber length for three different types of fuel admission (gaseous, spray, and vaporized) upon combustion efficiency was performed in identical combustor geometries and with similar air-flow patterns. The effects of fuel-air ratio and full-section velocity were examined for individual methods of admission. The effect of fuel volatility also was examined. It was found that the vaporized fuel type of admission was superior in efficiency to the spray-fuel admission in all comparable cases. Increased fuel volatility improved performance in the case of the vaporizer but did not affect the performance of the spray nozzle. The performance of vaporising tubes was found to vary inversely with size. An optimum size was exhibited.

Control of Lean Blowout in Partially Premixed Swirl-Stabilized Combustor Using a Fuel Rich Central Pilot Configuration

2019 ◽  
Author(s):  
Somnath De ◽  
Prasanna Mondal ◽  
Gourav Manohar Sardar ◽  
Rakin Bin Bokhtiar ◽  
Arijit Bhattacharya ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Premixed Flames ◽  
Premixed Combustion ◽  
Combustion Stability ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Lean Blowout ◽  
Partially Premixed Combustion ◽  
Partially Premixed

Abstract The main problem for using reliable and stable diffusion combustion in modern gas turbine engines is the production of NOx at a higher level which is not permissible for maintaining the healthy environment. Thus, combustion in lean premixed mode has become the most promising technology in many applications related to power generation gas turbine, industrial burner etc. Although the lean combustion minimizes NOx production, it suffers from an increased risk of lean blowout (LBO) when the requirement of thrust or load is low. It mainly occurs at the lean condition when the equilibrium between the flame speed and the unburnt air-fuel mixture velocity is broken. Current aircraft gas turbine engines operate fuel close to the combustion chamber which leads to the partially premixed combustion. Partially premixed combustion is also susceptible to lean blowout. Therefore, we have designed a swirl-stabilized dump combustor, where different lengths of fuel-air mixing are available. Our present work aims at improving the combustion stability by incorporating a secondary fuel injection through a pilot arrangement connected with the combustion chamber for premixed as well as partially premixed flames. Incorporation of the pilot system adds a small fraction of the total fuel into the combustion chamber directly. This investigation shows significant extension of the LBO limit towards leaner fuel-air mixture while the NOx emission in the combustion chamber is within the permissible limit. This result can be used for aircraft operators during the process of landing when fuel supply has to be decreased to reduce engine thrust or for power plants operating at low loads. The study of control is based on the colour variation of the flame which actually defines the changes in combustion characteristics. For early detection of LBO, the ratio between the intensity of red and blue colour obtained from flame images with a high speed camera is used. As LBO is approached, the ratio of red to blue intensity falls monotonically. When the ratio falls below a preset threshold, a small fraction of the total fuel is added to the central pilot line. This strategy allows the LBO limit to be shifted to a much lower equivalence ratio (maximum 20% and 11% for fully premixed and least premixed flames, respectively) without any significant increase in NOx production. The analysis includes a feedback control algorithm which is computed in MATLAB and the code is embedded in Labview for hardware implementation.

Lean-Burn Characteristics of a Heavy-Duty Diesel Engine Retrofitted to Natural-Gas Spark Ignition

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Fuel Injector ◽  
Heavy Duty ◽  
Lean Burn ◽  
Heavy Duty Diesel ◽  
Ci Engines

Increased utilization of natural gas (NG) in the transportation sector can decrease the use of petroleum-based fuels and reduced greenhouse gas emissions. Heavy-duty diesel engines retrofitted to NG spark ignition (SI) can achieve higher efficiencies and low NOX, CO, and hydrocarbon (HC) emissions when operated under lean-burn conditions. To investigate the SI lean-burn combustion phenomena in a bowl-in-piston combustion chamber, a conventional heavy-duty direct-injection CI engine was converted to SI operation by replacing the fuel injector with a spark plug and by fumigating NG in the intake manifold. Steady-state engine experiments and numerical simulations were performed at several operating conditions that changed spark timing (ST), engine speed, and mixture equivalence ratio. Results suggested a two-zone NG combustion inside the diesel-like combustion chamber. More frequent and significant late-burn (including double-peak heat release rate) was observed for advanced ST. This was due to the chamber geometry affecting the local flame speed, which resulted in a faster and thicker flame in the bowl but a slower and thinner flame in the squish volume. Good combustion stability (COVIMEP < 3%), moderate rate of pressure-rise, and lack of knocking showed promise for heavy-duty CI engines converted to NG SI operation.

A Control-Oriented Jet Ignition Combustion Model for an SI Engine

2015 ◽  
Author(s):  
Ruitao Song ◽  
Gerald Gentz ◽  
Guoming Zhu ◽  
Elisa Toulson ◽  
Harold Schock
Keyword(s):  
Combustion Chamber ◽  
Combustion Process ◽  
Turbulent Jets ◽  
Combustion Stability ◽  
Combustion Model ◽  
Combustion Chambers ◽  
Si Engine ◽  
Lean Operations ◽  
Combustion Processes ◽  
Hil Simulation

A turbulent jet ignition system of a spark ignited (SI) engine consists of pre-combustion and main-combustion chambers, where the combustion in the main-combustion chamber is initiated by turbulent jets of reacting products from the pre-combustion chamber. If the gas exchange and combustion processes are accurately controlled, the highly distributed ignition will enable very fast combustion and improve combustion stability under lean operations, which leads to high thermal efficiency, knock limit extension, and near zero NOx emissions. For model-based control, a precise combustion model is a necessity. This paper presents a control-oriented jet ignition combustion model, which is developed based on simplified fluid dynamics and thermodynamics, and implemented into a dSPACE based real-time hardware-in-the-loop (HIL) simulation environment. The two-zone combustion model is developed to simulate the combustion process in two combustion chambers. Correspondingly, the gas flowing through the orifices between two combustion chambers is divided into burned and unburned gases during the combustion process. The pressure traces measured from a rapid compression machine (RCM), equipped with a jet igniter, are used for initial model validation. The HIL simulation results show a good agreement with the experimental data.

scholarly journals THE INFLUENCE OF THE COMPOSITION AND PARAMETERS OF THE OIL GAS SUPPLY ON THE COMBUSTION LIMITS IN THE COMBUSTION CHAMBER

2020 ◽  
pp. 64-71
Author(s):  
Alyona Shilova ◽  
◽  
Roman Bulbovich ◽  
Nikolay Bachev ◽  
Oleg Matyunin ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Power Plants ◽  
Central Place ◽  
Combustion Stability ◽  
Fuel Gas ◽  
Micro Gas Turbine ◽  
Gas Utilization ◽  
Excess Air ◽  
Combustion Limits ◽  
Oil Gas

The question of oil gas utilization today is very important.In the development of domestic micro-gas-turbine utilization power plants, the central place is occupied by the creation of a universal combustion chamber, which would ensure stable combustion of ballasted gases at different fields under variable operating conditions.In this work, the phlegmatization method was used to determine the lower and upper concentration limits, which allows taking into account the effect of ballasting components on the combustion limits. When calculating the coefficients of excess air at the upper and lower limits, the influence of the composition, temperature, and supply pressure of the components was taken into account.An analysis of the results showed that taking into account the parameters of air and oil gas at the outlet of the compressors expands the limits of combustion by the coefficient of excess air. An additional regenerative heating of the air between the compressor and the combustion chamber shifts the combustion stability region in terms of the excess air coefficient towards rich mixtures. Recuperative heating of fuel gas shifts the area of sustainable combustion towards lean mixtures. Simultaneous regenerative heating of fuel gas and air expands the area of sustainable combustion.

NUMERICAL SIMULATION OF THE EFFECT OF INITIAL NONUNIFORMITY AND FLUCTUATIONS OF FUEL CONCENTRATION ON COMBUSTION STABILITY AND NOX AND CO EMISSION IN A LEAN PREMIXED METHANE/AIR COMBUSTOR

2020 ◽  
Author(s):  
K. Ya. Yakubovskiy ◽  
◽  
A. B. Lebedev ◽  
P. D. Toktaliev ◽  
◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Turbulent Flows ◽  
Three Dimensional ◽  
Combustion Stability ◽  
Fuel Concentration ◽  
Eddy Simulation ◽  
Flow Parameters ◽  
Low Emission ◽  
Large Eddy ◽  
Co Emission

The effect of initial nonuniformity and fluctuations of fuel concentration on the combustion stability and NOx and CO emission in the model combustion chamber was analyzed with the use of previously developed simple and computationally inexpensive Large Eddy Simulation (LES) methodology for simulation of three-dimensional unsteady turbulent flows with premixed combustion of methane-air mixture in low-emission combustion chamber which geometry is represented by channel with the backward facing step. Typical sizes of the combustion chamber, flow parameters, turbulence level, and method of flame front stabilization are close to those of full-sized industrial combustors.

Experimental Analysis of Confinement and Swirl Effects on Premixed CH4-H2 Flame Behavior in a Pressurized Generic Swirl Burner

2017 ◽  
Author(s):  
Jon Runyon ◽  
Richard Marsh ◽  
Daniel Pugh ◽  
Philip Bowen ◽  
Anthony Giles ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Kinetic Modelling ◽  
Dynamic Pressure ◽  
Flame Stabilization ◽  
Combustion Noise ◽  
Combustion Stability ◽  
Acoustic Response ◽  
Swirl Burner ◽  
Swirl Number

The introduction of hydrogen into natural gas systems for environmental benefit presents potential operational issues for gas turbine combustion and power generation applications; in particular acceptable blending concentrations are still widely debated. The use of a generic swirl burner under conditions pertinent to a gas turbine combustor is therefore advantageous to (i) provide evidence of potential design modifications to inform future gas turbine operation on hydrogen blends and (ii) validate numerical model predictions. Building on a previous experimental combustion database consisting of methane-hydrogen fuel blends under atmospheric and elevated ambient conditions, a new scaled generic swirl burner has been designed for experimental investigation of flame stability and exhaust gas emissions at combustor inlet temperatures to 573 K, pressures to 0.33 MPa, and thermal powers to 126 kW. The geometry downstream of the modular burner is developed further to enable separate investigation under isothermal and combustion conditions of the influence of combustor outlet geometry and the effect of changing geometric swirl number. The burner confinement is modified to include both a cylindrical exit quartz combustion chamber and a conical convergent exit quartz combustion chamber, designed to provide a more representative geometric and acoustic boundary at the combustor outlet. Two inlet geometric swirl numbers of industrial relevance are chosen; namely 0.5 and 0.8. Combustion stability and heat release locations of lean premixed CH4-air and CH4-H2-air combustion are evaluated by a combination of OH planar laser induced fluorescence, OH* chemiluminescence, and dynamic pressure measurements. Changes in flame stabilization location are characterized by the use of an OH* chemiluminescence intensity centroid. Notable upstream flame movement coupled with changes in acoustic response are evident, particularly near the lean operating limit as hydrogen blending shifts lean blowoff of methane flames to lower equivalence ratios with corresponding reduction in NOx emissions. The influence of increased pressure on the lean operating point stability and emissions appear to be small over the range considered, however a power law correlation has been developed for scaling combustion noise amplitudes with inlet pressure and swirl number. Indicators of flame flashback as well as combustor acoustic response are affected considerably when the convergent combustor outlet geometry is deployed. This has been shown to alter the influence of the central recirculation zone as a flame stabilizing coherent flow structure. Chemical kinetic modelling supports the experimental observations that stable burner operation can be achieved with blended methane-hydrogen up to 15% by volume.

Improvement of Gas Turbine Injection Systems by Combined Experimental/Numerical Approach

2002 ◽  
Author(s):  
G. Riccio ◽  
P. Adami ◽  
F. Martelli ◽  
D. Cecchini ◽  
L. Carrai
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Numerical Approach ◽  
Combustion Stability ◽  
Pollutant Emissions ◽  
Injection System ◽  
Flame Stability ◽  
Fuel Injection System ◽  
Joint Application

An aerodynamic study for the premixing device of an industrial turbine gas combustor is discussed. The present work is based on a joint application of numerical CFD and experimental investigation tools in order to verify and optimize the combustor gaseous fuel injection system. The objective is the retrofit of an old generation gas turbine combustion chamber that is carried out considering new targets of NOx emission keeping the same CO and combustion stability performances. CFD has been used to compare different premixing duct configurations for improved mixing features. Experimental test has been carried out in order to assess the pollutant emissions, flame stability and pattern factor characteristics of the full combustion chamber retrofitted with the modified injection system.

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