Visual Measurement of Particle Movement in Rectangular Circulating Fluidized Bed

Particle movement in transition region and dilute region of a cold rectangular circulating fluidized bed (CFB) were studied by using a high-speed video camera and particle image velocimetry (PIV) technology. Measurements were carried out with transparent glass bead between 0.1-0.65mm as bed materials and cold air as flow medium. The results with different superficial gas velocity show that projection section causes the deflexion of particle movement in transition region and increasing particle lateral velocity. Besides, furnace outlet and corner effect has important influence on particle velocity distribution. The closer to the outlet of furnace, the stronger the lateral movement of particles. Outlet effect has more influence on lateral velocity component than axis velocity component. Lateral velocity component is the main factor which affects particle macroscopic motion. With higher superficial gas velocity, the non-homogeneous distribution of particle velocity becomes more acute in research regions. To reduce erosion in CFB boiler, it is recommended to adopt rounding structure in projection section, reduce the existence of irregular region, and select proper outlet structure and reasonable superficial gas velocity, furthermore, corner protection for rectangular CFB is also needed.