Numerical and Experimental Investigation of the Combustion and Emission Characteristics of Low to Medium Calorific Value Landfill Gas Blended with Hydrogen

Landfill gas (LFG) is a natural by-product of the biodegradation of organic wastes in a landfill site, and it is legally considered to be a waste. It contains methane (CH4) which is a hydrocarbon fuel with a high calorific value of 55.5 MJ/kg, and other inert gases such as CO2 and N2. The composition of the LFG varies widely depending on the design, age and deposited content of the landfill sites. When the LFG contains a high fraction of CH4 (>40 vol%), it can directly be used for power generation and heating applications as an effective renewable fuel. It is also used to produce synthetic natural gas through purification processes. However, when the LFG contains a low concentration of methane (
There is a potential to utilise low to medium calorific value LFG with 20 – 40 vol% CH4 for the process heating needs of industries. However, the presence of a high percentage of inert gases in low to medium calorific value LFG presents a challenge for maintaining stable combustion as required for practical applications. In particular, the high percentage of CO2 could result in unstable flame, blow-off, and production of harmful emissions. In order to minimise those problems and to enhance combustion performance of LFG, flame stability must be improved, and flammability limits expanded. Fuel enrichment techniques with high quality fuel can be used to achieve those requirements. Currently, there are limited research studies on the combustion of low to medium calorific value LFG using fuel enrichment techniques. The proposed project aims to have a better understanding of combustion, thermal and emission characteristics of LFG with low to medium calorific value and explore the potential of hydrogen enrichment technique to produce stable combustion. The hydrogen is selected as the potential enrichment fuel because of its future potential as an environmentally friendly source of energy, clean combustion, and high heating value (120-142 MJ/kg). The combustion and emission characteristics will be investigated numerically using CHEMKIN by applying the GRI-Mech 3.0 reaction mechanism and experimentally using various standard methods such as constant volume combustion bomb with schlieren photography, heat flux method, and pollutant emission measurement techniques. The effect of different compositions of diluents in the LFG and hydrogen enrichment will be investigated fully. The outcome from the project may enhance the fundamental knowledge of combustion, thermal and emission characteristics of hydrogen-enriched low to medium calorific value LFG and pave the way to design combustion systems to better utilise low-quality LFG as a renewable source of energy while reducing harmful emissions to the atmosphere.