Effects of non-premixed H2 injection on the stability, shape, and combustion/emissions characteristics of premixed CH4/air flames: An experimental study

Ahmed Abdelhalim, Ahmed Abdelhafez*, Medhat A. Nemitallah

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This study investigates the stability and combustion characteristics of a hydrogen-enriched, lean, stratified CH4/air flame in a model gas-turbine burner that mimics Dual Annular Counter-Rotating Swirl (DACRS) burners in actual aeroderivative gas turbines. The primary CH4/air mixture was supplied with swirl at the center of combustor, while hydrogen was injected as non-premixed non-swirling jets at the periphery of primary mixture. Enrichment hydrogen was examined for the first time in DACRS-like burners, which highlights the novelty of the present work. The study analyzed the effects of hydrogen fraction (volumetric percentage of hydrogen in the total fuel entering combustor) ranging from 0 to 20% and equivalence ratio ranging from 0.5 to 0.73 on flame stability, structure, and emissions. For the studied combustor, the results showed that the addition of hydrogen in this manner has two opposing effects on the flame. Hydrogen-enrichment enhances the reaction kinetics and flame speed, which should lead to a more stable, brighter, and more compact flame, but the high momentum of the non-swirling hydrogen jets weakens the swirl intensity of the primary CH4/air flame, which has a negative influence on its stability. The combined net result is that the blowout limit of the flame remained constant at an equivalence ratio of about 0.5, despite increasing the hydrogen fraction up to 20%. NOx emissions were observed not to be affected by hydrogen enrichment up to 20%, but increasing the equivalence ratio favors NOx formation as expected.

Original languageEnglish
Article number131213
JournalFuel
Volume365
DOIs
StateAccepted/In press - 2024

Bibliographical note

Publisher Copyright:
© 2024 Elsevier Ltd

Keywords

  • Adiabatic flame temperature
  • Dry Low NOx (DLN) burner
  • Flame stability
  • Gas-turbine combustor
  • Hydrogen enrichment
  • Stratified combustion

ASJC Scopus subject areas

  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry

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