Simulation Study of Natural Gas Blending with Hydrogen and Dissociated Methanol Gas for Boiler Combustion

In light of the worldwide consensus on net-zero emissions, using clean fuels to wholly or substantially replace traditional fuels has emerged as the dominant route of industrial development. This paper presents a methanol-hydrogen co-combustion method for boilers, based on methanol, a zero-carbon fuel produced from CO₂. The technique uses boiler waste heat to catalytically fracture methanol into dissociated methanol gas (DMG), largely composed of H₂ and CO. The DMG is blended with the original fuel to improve thermal efficiency and minimize emissions. A three-dimensional geometric model was developed with a tiny direct-current natural gas (NG) boiler as the research subject. The combustion characteristics of natural gas mixed with various concentrations of DMG and hydrogen were simulated using the finite volume approach. Blending hydrogen and DMG at a flow rate of 10 m³/h and a surplus air ratio of 1.2 improves the NG heat release rate and furnace temperature. At a 5% hydrogen mixing ratio, the heat release rate rises by up to 2.2%, while the average furnace temperature reaches a high of 1886 K. Meanwhile, at a DMG mixing ratio of 10%, the heat release rate increases by a maximum of 2.1%, while at a mixing ratio of 5%, the average furnace temperature reaches 1895 K. Overall, hydrogen has a greater effect on increasing the heat release rate of NG combustion, whereas DMG has a larger potential to raise furnace temperature.