อิทธิพลของแผ่นกระจายอากาศและการเกาะกันของอนุภาคที่มีต่อฟลูอิไดเซชัน / สุรชัย ภัทรพงศ์เกษม = Influence of distributor and agglomeration on fluidization / Surachai Pattarapongkasem
Fluidization system has been widely used in many industries such as petrochemical, biochemical, and electrochemical processes. One of the major problems of 3-phase fluidization systems is that the liquid in the system causes the particle agglomeration, which results in an incomplete fluidization, or so-called defluidization. Since the factors that make a complete fluidization system include type and properties of particle, liquid, temperature, pressure, and distributor, we herein report our study in the effect of distributors and agglomerating particles on the fluidization. In a gas-solid fluidization experiment with plastic particles (0.6 cm in diameter), the minimum fluidization velocity (Umf) changed from 1.6 to 1.7, 1.85, 2.1, 2.2 m/s when the number of agglomerating particles increased from 1 to 2, 4, 5, 6, respectively, which was due to the movement resistance of the increased particle weight and buoyancy force. In order to achieve a complete fluidization at that stage, a higher air velocity is required. We found that the calculated and experimental values of minimum fluidization velocity of agglomerating particle are significantly different. For instance, in the case with 6 particles the calculate Umf was of 1.75 m/s whereas the experimental data was 2.2 m/s. We, therefore, decided to solve this problem by using fractal theory in the part of shape factor. This resulted in a much better agreement between the two values (new calculated Umf 2.39 m/s vs experimental Umf 2.2 m/s). We also found that the distributors type I and J which possess both straight and oblique air flows were the most efficient ones. In a system which contains mung bean (as a bed), moisture and water, the minimum fluidization velocity was higher than that in the dry system or 2-phase (Umf 1.5 m/s for the 3-phase and 1 m/s for the 2-phase system). Therefore, the liquid in the system is of great significance to the fluidization