What impacts might poor coal quality during operation have on the safety and economic efficiency of the boiler? What impact will it have on the steam temperature?

An increase in moisture and ash content in coal, along with a decrease in volatile matter, all lead to delayed ignition of the fuel, a postponement of the combustion and burnout processes, and an upward shift in the position of the highest flame temperature； A decrease in calorific value leads to an increase in the amount of fuel used, which in turn increases the volume of flue gas, raises the flame center, and also enhances the convective heat transfer behind it ； The coal powder becomes coarser, making combustion difficult, and the flame moves toward the furnace outlet. When the quality of coal deteriorates, the temperature in the main combustion zone of the furnace decreases, while the temperature at the furnace outlet increases; as a result, the superheated steam temperature rises. When the quality of coal improves, the flame temperature in the main combustion zone increases, but the temperature of the flue gas at the furnace outlet and the superheated steam temperature decrease.