Characteristics of combustion and ash deposition for pulverized coal combustion under various thermal loads: An experimental study in an 80 kWth combustion system

Load-following operations of coal power plants are required to cope with the variability in power generation from renewable energy sources. This study aimed to optimize combustion in coal-fired power plants at low loads by analyzing combustion efficiency, NO_x emissions, and ash deposition in a boiler. An experiment was conducted by varying the heat input in a bench-scale combustion system. The combustion performance, in terms of the CO concentration in combustion gas and unburned carbon content in ash, degraded during low-load operation. Consequently, the fuel ratio was found to be a key factor for determining the combustion efficiency during low-load operation. The nitrogen content of the fuel was dominant in terms of the NO conversion ratio. The inconsistency in the ash deposition tendency suggested that it was affected more by the composition of minerals than by the amount of ash or total feed rate of ash in coal.