Abstract
We present a basic idea for the prediction of burner minimum loads for different coal-fired furnaces. Our idea is using the equation expressed by heat loss ratio and radiation intensities. We measured radiation intensities near the burner exit and studied the radiation profiles with decreasing burner load at 25MJ/h single burner test furnace. Radiation intensity decreases with decreasing load and the intensity at the burner minimum load is approximately 150kW/m^2. To get the equation for the prediction, quantities of heat transferred to the flame stabilization region at full and minimum loads are studied theoretically. We compared the decreasing radiation profile with the predicted profile by the equation at 25MJ/h test furnace and got good agreement. Next, we predicted the minimum loads for different types of coal at 150MJ/h test furnace. The assessment using data shows that our equation can be used to predict burner minimum load for the low-stabilized condition from the high-stabilized condition with an error of about 12%.
