Numerical Simulation Research on Coal Combustion in Rotary Kiln with Multi-air Channel Coal Burner

This paper presents a 3-dimentional numerical study with CFX software on physical field in rotary kiln with multi-air channel coal burner. The effects of some parameters on flame feature and temperature profile were conducted, which provides reference for optimal operation and design of the multi-air coal burner. A thermal measurement was conducted on an industrial rotary kiln with a length of 90 meters and an inner diameter of 4.5 meters with four-air channel coal burner to obtain the operational conditions and to validate the simulation predictions. The computational result shows that velocity profile near the burner exit is saddle-like. Little central airflow can avoid coal backing up. It was also found that the four-channel coal burner has a good adaptability for the volatiles and size of the coal. Generally, for anthracite coal, average coal size should be limited within 60 micron, and for bituminous coal, an active flame still can be obtained even when the coal size is 86.4 micron.