Study on the influence of different thermal coals on the mixed-burning characteristics of ventilation air methane and pulverized coal

To effectively utilize ventilation air methane (VAM), it is proposed to pass it into the boiler of the coal-fired power plant for mixed combustion. However, the different types of thermal coal utilized present distinct characteristics when mixed with VAM. In this paper, lignite, bituminous coal, and anthracite are selected to study the CH₄ conversion rate, system ignition temperature, and NO emission characteristics of the VAM-pulverized coal coupled system on a fluidized bed experimental platform. The experimental results show that the ignition temperatures of VAM are 748, 736, and 732 °C when the CH₄ concentration is 0.25, 0.5, and 0.75%. After the addition of thermal coal, the ignition temperature decreased significantly. When the CH₄ concentration is 0.25%, the ignition temperature of the lignite-VAM system is the lowest, which is 450 °C. Anthracite has the strongest catalytic effect on CH₄ combustion. When the heating rate is 5 °C /min, the reaction rate of CH₄ is the fastest in the anthracite-VAM coupled system. Under laboratory conditions, the peak NO concentration in the coal-VAM coupled system was lignite > bituminous coal > anthracite at different CH₄ concentrations, and the CH₄ in VAM had a reducing action on the NO generated during mixed combustion, with a stronger reducing effect observed as the CH₄ concentration increased. The results of this study can lay the foundation for the industrial application of the mixed combustion of VAM and thermal coal, and be of great significance for solving the practical problems caused by the change of boiler coal types. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.