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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

[+] Author and Article Information
Eric L. Petersen

Texas A&M University,
College Station, TX 77843

Henry J. Curran

National University of Ireland,
Galway, Ireland

Gilles Bourque

Rolls-Royce Canada,
Montreal, H9P 1A5, Canada

Felix Güthe

Alstom, 5401 Baden, Switzerland

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received September 17, 2012; final manuscript received September 27, 2012; published online January 8, 2013. Editor: Dilip R. Ballal.

J. Eng. Gas Turbines Power 135(2), 021504 (Jan 08, 2013) (10 pages) Paper No: GTP-12-1363; doi: 10.1115/1.4007763 History: Received September 17, 2012; Revised September 27, 2012

Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio. The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied as well as experimental and theoretical disciplines.

Copyright © 2013 by ASME
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References

Figures

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Fig. 1

Alstom GT24/GT26 sequential combustion system

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Fig. 2

Rolls-Royce Industrial RB211 DLE combustion system

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Fig. 3

Laminar flame speed of CH4/Air [20] and NG2/Air [7] at atmospheric conditions. Symbols are experimental data, lines are simulations.

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Fig. 4

Sample of results of parametric flame speed study of CH4 with varying H2 additions. Approximate order from bottom dictates % H2 (lowest: 0%, upper: 100%). Line type dictates pressure and inlet temperature (solid: 15 atm, 300 K; dashed: 15 atm, 600 K; dotted: 35 atm, 600 K; dot dash: 15 atm, 900 K).

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Fig. 5

Sample of results of parametric flame speed study of NG2 with varying H2 additions. Approximate order from bottom dictates % H2 (lowest: 0%, upper: 100%). Line type dictates pressure and inlet temperature (solid: 15 atm, 300 K; dashed: 15 atm, 600 K; dotted: 35 atm, 600 K; dot dash: 15 atm, 900 K).

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Fig. 6

Effect of H2 addition on the normalized laminar flame speed of CH4 and NG2. Tin_1st, Pi = constant. Line order indicates CH4 (upper) or NG2 (lower). Line dictates equivalence ratio (solid: ϕ = 0.5; dashed: ϕ = 0.7; dotted: ϕ = 1.1; dot dash: ϕ = 1.5).

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Fig. 7

Hydrogen reactivity in air (ϕ = 1.0) as a function of temperature for the pressures examined in the present study

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Fig. 8

Effect of H2 addition to CH4 and NG2 as a function of initial pressure. Tin_2nd = 1100 K, ϕ = 0.7. Order dictates base fuel (upper: CH4, middle: NG2, lowest: H2). Solid lines: pure fuel; dashed lines: 5% H2; dotted lines: 50% H2; dot dash lines: 70% H2; dot dot dash lines: 90% H2.

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Fig. 9

Effect of H2 addition to as a function of initial pressure. Tin_2nd = 1300 K, ϕ = 0.7. Order dictates base fuel (upper: CH4, middle: NG2, lowest: H2). Solid lines: pure fuel; dashed lines: 5% H2; dotted lines: 50% H2; dot dash lines: 70% H2; dot dot dash lines: 90% H2.

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Fig. 10

Effect of H2 addition to CH4 and NG2 as a function of initial pressure. Tin_2nd = 1100 K, ϕ = 1.1. Order dictates base fuel (upper: CH4, middle: NG2, lowest: H2). Solid lines: pure fuel; dashed lines: 5% H2; dotted lines: 50% H2; dot dash lines: 70% H2; dot dot dash lines: 90% H2.

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Fig. 11

Schematic of the primary burner model using Chemkin modules. Inputs include: flame temperature, inlet temperature, fuel composition, and pressure. The laminar flame speed was returned.

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Fig. 12

Schematic of secondary burner model using Chemkin modules. In addition to the EV inputs, the secondary burner inlet temperature was required. The ignition delay time was returned.

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Fig. 13

Effect of H2 addition to CH4 and NG2. Tin_1st = 480 °C, 25 atm. Order in each pair indicates the base fuel (slower: CH4; faster: NG2) and symbols indicate rich (diamond), stoichiometric (triangle), or lean (square). Lines indicate Tflame (solid: 1600 K; dash: 1750 K; dot: 2150 K; dot dash: Tflame > 2500 K).

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Fig. 14

Effect of H2 addition to CH4 (larger values) and NG2 (smaller values); Tin_1st = 480 °C, ϕ < 1. Solid lines: 25 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 15

Effect of H2 power percent in mixtures of H2 and CH4 or NG2, Tin_1st = 480 °C, ϕ < 1. Solid lines: 25 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 16

Effect of flame temperature on the laminar flame speed for CH4 (larger values) and NG2 (smaller values). 50% H2, ϕ < 1, Tin_1st = constant. Solid lines: 25 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 17

Effect of inlet temperature on the laminar flame speed for CH4 (larger values) and NG2 (smaller values). 50% H2, ϕ < 1, Tflame = constant. Solid lines: 25 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 18

Effect of H2 addition to the ignition delay time of CH4 (smaller values) and NG2 (larger values), Tin_2nd = 1300 K, ϕ < 1. Solid lines: 30 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 19

Effect of H2 power percent on ignition delay time for mixtures of H2 and CH4 (smaller values) or NG2 (larger values), Tin_2nd = 1300 K, ϕ < 1. Solid lines: 30 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 20

Effect of inlet temperature on ignition delay time of CH4 (darker) and NG2-based (lighter) mixtures. 50% H2, ϕ < 1. Solid lines: 30 atm; dashed lines: 15 atm; dotted lines: 1 atm.

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Fig. 21

Effect of H2 addition to CH4 and NG2 on turbulent and laminar flame speeds. Tin_1st = 480 °C, p = 25 atm, ϕ < 1.

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