FCC三旋细颗粒凝结长大特性实验研究

Growing characteristics of heterogeneous condensation of fine particles after FCC cyclone

为进一步提高FCC三旋细颗粒脱除效率,基于蒸汽相变原理,在低过饱和度下进行了FCC三旋细颗粒相变长大特性的实验,并采用静电低压冲击器(EIPI+)测量相变长大前后颗粒粒径分布,研究了热水温度、颗粒初始浓度及烟气流量对颗粒相变长大的影响。结果表明:提高热水温度可显著促进颗粒长大;颗粒的初始浓度对其长大效果的影响因热水温度而异,具有一定不确定性;烟气流量增大会抑制颗粒长大。在最优的实验条件下,细颗粒的算术平均粒径由初始的1.35增大到6.76μm,已达FCC大三旋装置除尘的临界粒径,可进行工业分离。

Growing characteristics of FCC fine particles was studied based on vapor condensation principle under low supersaturation degrees through mixing of hot water vapor and cold gas.ELPI+was used to measure the diameter distribution before and after phase changing development.Effects of hot water temperature(30,40 and 50℃),initial particle concentration(998 and 2004 particles·cm^-3)and particle flow rate(2 and 4 L·min^-1)on particle growth were discussed experimentally.The results show that larger supersaturation degree could highly improve particle growth.The effects of initial particle concentration vary with hot water temperatures.Larger flow rate of particles would restrain particle growth.Under the optimal experimental condition,the particle size could be enlarged from the initial 1.35 to 6.67μm.The particle size after pre-agglomeration satisfies well with the critical particle size requirement of three-stage cyclone equipment in FCC.