Numerical Simulation of Lean Blowout of Alternative Fuels in 7-element Lean Direct Injector

Currently, high efficiency and low emissions are most important requisites for the design of modern gas turbines due to the strong environmental restrictions around the world. In the past years, alternative fuels have been considered for application in industrial gas turbines. Therefore, combustor performance, pollutant emissions and the ability to burn several fuels became of much concern and high priority has been given to the combustor design. This paper describes a methodology focused on the design of stationary gas turbines combustion chambers with the ability to efficiently burn conventional and alternative fuels. A simplified methodology is used for the calculations of the equilibrium temperature and chemical species in the primary zone of a gas turbine combustor. Direct fuel injection and diffusion flames, together with numerical methods like Newton-Raphson, LU Factorization and Lagrange Polynomials, are used for the calculations. Diesel, ethanol and methanol fuels were chosen for the numerical study. A computer code sequentially calculates the main geometry of the combustor. From the numerical simulation it is concluded that the basic gas turbine combustor geometry, for some operating conditions and burning diesel, ethanol or methanol, are of similar sizes, because the development of aerodynamic characteristics predominate over the thermochemical properties. It is worth to note that the type of fuel has a marked effect on the stability and combustion advancement in the combustor. This can be seen when the primary zone is analyzed under a steady-state operating condition. At full power, the pressure is 1.8 MPa and the temperature 1,000 K at the combustor inlet. Then, the equivalence ratios in the primary zone are 1.3933 (diesel), 1.4352 (ethanol) and 1.3977 (methanol) and the equilibrium temperatures for the same operating conditions are 2,809 K (diesel), 2,754 K (ethanol) and 2,702 K (methanol). This means that the combustor can reach similar flame stability conditions, whereas the combustion efficiency will require richer fuel/air mixtures of ethanol or methanol are burnt instead of diesel. Another important result from the numerical study is that the concentration of the main pollutants (CO, CO2, NO, NO2) is reduced when ethanol or methanol are burnt, in place of diesel.

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Numerical Simulation on Hydrogen Lean-blowout Limit in Bluff-body Burner

International Journal of Advancements in Computing Technology ◽

10.4156/ijact.vol3.issue10.29 ◽

2011 ◽

Vol 3 (10) ◽

pp. 232-239 ◽

Cited By ~ 1

Author(s):

Yajun Li ◽

Hongtao Zheng ◽

Lin Cai

Keyword(s):

Numerical Simulation ◽

Bluff Body ◽

Lean Blowout

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Experimental Investigation of Fuel Composition Effects on Syngas Combustion

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration ◽

10.1115/gt2015-42401 ◽

2015 ◽

Cited By ~ 2

Author(s):

Thijs Bouten ◽

Martin Beran ◽

Lars-Uno Axelsson

Keyword(s):

Experimental Investigation ◽

Heat Release ◽

Gas Turbine ◽

Alternative Fuels ◽

Oil And Gas ◽

Flame Temperature ◽

Fuel Composition ◽

Lean Blowout ◽

Track Record ◽

Syngas Combustion

The OPRA OP16 gas turbine is an all radial single-shaft gas turbine rated at 1.9 MW with a successful track record from oil and gas applications as well as industrial and commercial CHP applications. To meet the growing demand for alternative fuels, OPRA Turbines has developed a new tubular combustor for the OP16 gas turbine fleet. The combustor has been successfully tested on a wide variety of (ultra-) low-calorific gaseous fuels in an atmospheric combustion test rig. This paper presents an experimental investigation of syngas combustion in the low-calorific fuel combustor. The effect of the variation in fuel composition on the combustion characteristics has been investigated extensively. This includes the effect of variable heating values and variations in the ratio between hydrogen and carbon monoxide and between syngas and hydrocarbons. The effects of these variations on the combustor performance, emissions and lean blowout limits will be discussed and compared to the results obtained from the combustion of propane. Major differences in emissions have been found, mainly influenced by the flame temperature and presence of hydrogen in the fuel. Lean blowout of the combustor is largely determined by the presence of hydrogen, whereas other components are found to have less influence. Theoretical calculation, based on le Chatelier’s rule and a method based on heat release, of the lean blowout limit has been compared to the experiments. It was found that the heat release method predicts the flammability limit more accurately than le Chatelier’s rule. This is caused by the inaccuracy of the latter to handle fuels with a large amount of hydrogen.

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Spark Advance Modeling of Hydrogen-Fueled Spark Ignition Engines Using Combustion Descriptors

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4038798 ◽

2018 ◽

Vol 140 (8) ◽

Author(s):

Saket Verma ◽

L. M. Das

Keyword(s):

Numerical Simulation ◽

Alternative Fuels ◽

System Development ◽

Spark Ignition ◽

Spark Ignition Engines ◽

Ansys Fluent ◽

Engine Design ◽

Pressure Peak ◽

Si Engines ◽

Computational Fluid Dynamics Cfd

In-cylinder pressure-based combustion descriptors have been widely used for engine combustion control and spark advance scheduling. Although these combustion descriptors have been extensively studied for gasoline-fueled spark ignition (SI) engines, adequate literature is not available on use of alternative fuels in SI engines. In an attempt to partially address this gap, present work focuses on spark advance modeling of hydrogen-fueled SI engines based on combustion descriptors. In this study, two such combustion descriptors, namely, position of the pressure peak (PPP) and 50% mass fraction burned (MFB) have been used to evaluate the efficiency of the combustion. With a view to achieve this objective, numerical simulation of engine processes was carried out in computational fluid dynamics (CFD) software ANSYS fluent and simulation data were subsequently validated with the experimental results. In view of typical combustion characteristics of hydrogen fuel, spark advance plays a very crucial role in the system development. Based on these numerical simulation results, it was observed that the empirical rules used for combustion descriptors (PPP and 50% MFB) for the best spark advance in conventional gasoline fueled engines do not hold good for hydrogen engines. This work suggests revised empirical rules as: PPP is 8–9 deg after piston top dead center (ATDC) and position of 50% MFB is 0–1 deg ATDC for the maximum brake torque (MBT) conditions. This range may vary slightly with engine design but remains almost constant for a particular engine configuration. Furthermore, using these empirical rules, spark advance timings for the engine are presented for its working range.

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Numerical investigation of fuel flexibility in a small-scale flameless combustor

Journal of Physics Conference Series ◽

10.1088/1742-6596/2116/1/012017 ◽

2021 ◽

Vol 2116 (1) ◽

pp. 012017

Author(s):

P Rijo ◽

P J Coelho

Keyword(s):

Numerical Simulation ◽

Natural Gas ◽

Numerical Investigation ◽

Equivalence Ratio ◽

Alternative Fuels ◽

Premixed Combustion ◽

Small Scale ◽

Combustion Mode ◽

Geometrical Characteristics ◽

Fuel Flexibility

Abstract Numerical simulation of a laboratory flameless combustor was performed to investigate the flexibility to burn alternative fuels to natural gas. The studied fuels are biogas, syngas and a mixture of ammonia and methane. The inlet temperatures of air and fuel, the equivalence ratio and the geometrical characteristics of the combustor were maintained constant. The results show that flameless combustion is observed in the biogas and in the NH3/CH4 mixture, while the syngas burns according to the conventional non-premixed combustion mode. According to the predictions, the biogas emits 1.1 ppm of NOx and 229 ppm of CO, syngas produces 7.8 ppm of NOx and 35 ppm of CO and the NH3/CH4 mixture emits about 3900 ppm of NOx and 608 ppm of CO. The high NOx and CO emissions in the NH3/CH4 mixture show that the combustor needs to be optimized to burn a nitrogen-containing fuel.

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Numerical simulation of alternative fuels combustion in gas turbines

10.1063/1.5130823 ◽

2019 ◽

Author(s):

J. A. Vilag ◽

V. A. Vilag ◽

C. Pușcașu ◽

R. E. Nicoară ◽

M. Călugăru

Keyword(s):

Numerical Simulation ◽

Gas Turbines ◽

Alternative Fuels

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Evaluation of Impact on Lean Blowout Limit and Ignition Delay While Using Alternative Fuels on Gas Turbine Combustor

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2018-75245 ◽

2018 ◽

Author(s):

Ihab Ahmed ◽

Lukai Zheng ◽

Emamode A. Ubogu ◽

Bhupendra Khandelwal

Keyword(s):

Gas Turbine ◽

Ignition Delay ◽

High Speed ◽

Feedback Loop ◽

Alternative Fuels ◽

Cetane Number ◽

Jet Fuels ◽

Low Carbon ◽

Gas Turbine Combustor ◽

Lean Blowout

Burning leaner is an effective way to reduce emissions and improve efficiency. However, this increases the instability of the combustion and hence, increases the tendency of the flame to blowout. On the other hand, the ignition delay of a jet fuel is a crucial factor of the instability feedback loop. Shorter ignition delay results in faster feedback loop, and longer ignition delay results in slower feedback loop. This study investigates the potential effect of ignition delay on the lean blowout limit of a gas turbine combustion chamber. At the Low Carbon Combustion Centre of The University of Sheffield, a range of tests were carried out for a range of jet fuels on a Rolls-Royce Tay combustor rig. The ignition delay for each fuel was tested using Advanced Fuel Ignition Delay Analyser (AFIDA 2805). Lean blowout tests (LBO) was conducted on various air flows rates. High speed imaging was recorded using a high speed camera to give further details of the flame behavior near blowout limit for various fuels. The instability level was observed using the pressure, vibration and acoustic fluctuation. This paper presents results from an experimental study performed on a small gas turbine combustor, comparing Lean Blowout limit of different conventional, alternative and novel jet fuels with various ignition delay characteristics. It was observed that at higher cetane number, the blowout is improved remarkably. The Ignition plays an important role in determining the average instability level, and as result determines the Lean Blowout limit of a fuel.

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