Enhancing combustion stability and emission performance of low-calorific landfill gas through hydrogen enrichment in a double-layer porous media burner

This study investigates the enhancement of combustion stability and emission performance of low-calorific landfill gas (LFG) through hydrogen enrichment in a double-layer porous media burner. Landfill gas, a renewable energy source, often faces utilization challenges due to low methane content and high CO₂ dilution, leading to combustion instability and significant environmental impacts from venting or flaring. The research leverages porous media combustion technology paired with hydrogen blending to address these issues. Experiments were conducted to analyze the influence of hydrogen blending ratios (α_H2 = 0 %–30 %), equivalence ratios (φ = 0.8–1.2), and inlet flow velocities (u_in = 1.0–2.0 m/s) on three types of LFG compositions (LFG20, LFG30, LFG40). Results demonstrate that hydrogen enrichment broadens combustion stability, with optimal conditions achieving high thermal performance (peak temperatures up to 1074.28 °C) and reduced pollutant emissions. LFG20 achieved flame within porous media (FWP) atα_H2 = 15 %–25 %, while LFG40 requiredα_H2 ≤15 % to prevent flashback. Stoichiometric (φ = 1.0) and lean conditions (φ = 0.8) exhibited wider FWP ranges compared to rich conditions (φ = 1.2), where CO₂ dilution impaired stability. CO emissions decreased with the addition of hydrogen but rebounded atα_H2 >10 % due to preferential H₂ oxidation. NO emissions increased with hydrogen, driven by thermal NO mechanisms. This work contributes valuable insights into designing efficient combustion systems for low-calorific landfill gas recovery and emphasizes the promising role of hydrogen in advancing sustainable energy solutions.