Numerical Simulation of Combustion in 660 MW Tangentially Fired Pulverized Coal Boiler on Ultra-Low Load Operation

Abstract

In this paper, the combustion conditions in the boiler furnace of a 660 MW tangential fired pulverized coal boiler are numerically simulated at 15% and 20% rated loads, to study the flexibility of coal-fired power units on ultra-low load operation. The numerical results show that the boiler can operate safely at 15% and 20% ultra-low loads, and the combustion condition in the furnace is better at 20% load, and the tangent circles formed by each characteristic section in the furnace are better, and when the boiler load is decreased to 15%, the tangent circles in the furnace begin to deteriorate. The average flue gas temperature of different areas of the furnace shows that when the boiler furnace operates under ultra-low load conditions, the average smoke temperature of the cold ash hopper at 20% load is basically the same as the average smoke temperature at 15% load; in the burner area, the average smoke temperature of the cold ash hopper at 20% load is about 50 K higher than that at 15% load; in the burned out area, the average smoke temperature of the cold ash hopper at 20% load is slightly higher than that at 15% load. The average temperature of flue gas in the furnace showed a tendency to increase rapidly with the height of the furnace, then slow down and fluctuate the temperature in the burner area, and finally increase slightly in the burnout area due to the further combustion of combustible components to release heat, and then began to decrease.