Attrition of Different Materials in Fluidized Beds

• Main Authors: Tung-Yu Yang, 楊東昱
• Other Authors: Shu-Yii Wu
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/44921694405894183235

碩士 === 逢甲大學 === 化學工程學系 === 88 === Within the application of fluidized bed, carryover of fine particles caused by bed materials attrition is frequently observed. The catalyst lost in the regeneration process caused by attrition and the de-dusting equipment overloading in the system both are increasing the cost in the processes. The later process absorbent attrition changes the particle size distribution and affects the efficiency of the desulfurization. For gas-solid fluidized bed, high gas velocity from nozzle or recircular pipe is the dominant source of particle attrition. In this investigation, we focus on the attrition of FCC, limestone, quartz sand and silica sand particles in a fluidized bed with multiple jets. Experimental work was carried out in a batch gas fluidized bed with 6.62 cm inner diameter and 2.5 m bed height. There are various geometry arrangements of multi-jet system, gas velocity, diameter of jet, and jet pitch to simulate jetting phenomenon in grid zone in a fluidized bed. The experimental results show that the attrition rate is function of particle size distribution, materials nature, multiple-jet velocity and jet diameters. The empirical attrition rate equation developed from the motion of gas bubble is shown as follows: Rt=K''ao*(nj^0.5)*g*Uj(Uo-Umf)*(dor/D)*W [kg/s] For FCC : K''ao = 7.91*(10^-6) [s/m2] For limestone : K''ao = 1.08*(10^-6) [s/m2] For quartz sand : K''ao = 2.10*(10^-6) [s/m2] For silica sand : K''ao = 2.70*(10^-6) [s/m2] Also we quote abrasive index, AI, established by CEMA (Conveyor Equipment Manufacturer''s Association), and the sphericity of bed-materials to estimate the intrinsic attrition rate constant, K''ao. The result is shown as follow: K''ao = 3.41*(10^-8)*(AI/φs) [s/m2]