Abstract To explore the effects of the hydrogen-coal co-combustion characteristics and NO x emissions of a large-scale 660 MW single-reheat tower-type power boiler, numerical simulation was performed to investigate the effects of over-fire air (OFA) ratios in the range of 15–25 %, hydrogen blending ratios from 0 % to 20 % and boiler loads spanning 30–100 % of the boiler maximum continuous rating (BMCR). Results show that an OFA ratio of 25 % reduces the outlet NO concentration to 260 mg m −3 but compromises the burnout rate. Hydrogen blending expands the high-temperature zones and enhances the combustion stability under low-load conditions. The NO x emissions present a trend of first decreasing and then increasing with the rise in hydrogen blending ratio. The optimal hydrogen blending ratio is determined as 10 %, corresponding to NO x emissions of 280 mg m −3 at 100 % BMCR and 492 mg m −3 at 30 % BMCR. When the hydrogen blending ratio exceeds 10 %, a surge in thermal NO x emissions is observed, with the value reaching 483 mg m −3 at a blending ratio of 20 % and a boiler load of 100 % BMCR. This study provides theoretical support for the optimization of hydrogen-coal co-combustion technology and the realization of carbon neutrality goals.
Da et al. (2026) studied this question.