Bubble properties such as bubble size distribution, bubble mean chord length, bubble rising velocity, bubble frequency and bubble void fraction for air-coal fluidization system have been measured using electro-resistivity probe in a 0.3 by 0.3 m in bed cross-section and 4.0 m in height cold test apparatus.
Based on the measurements, the effect of parameters on the bubble properties have been discussed, such as excess air velocity(4.7 - 23.3 cm/sec), particle size (0.034 - 0.062 cm), prove height above distributor (10-40cm).
The cumulative size distribution data are fitted well by a logarithmic normal probability distribution. A correlation equation which can predict the cumulative distribution line is presented. With this equation, one can predict the mean chord length, the standard deviation, the cumulative and number fraction in arbitrary operating condition.
Mean chord length, bubble rising velocity increases with excess air velocity and probe height. However, the mean chord length is independent of particle size with excess air velocity as a parameter. Bubble rising velocity decreases a little with an increase of particle size. Bubble diameter was predicted by correlating the bubble rising velocity with the mean chord length. Bubble frequency and void fraction increases with excess air velocity.
