搅拌槽中液——液分散的放大研究 Ⅱ、苯乙烯悬浮聚合反应器的放大准则

STUDIES ON LIQUID-LIQUID DISPERSION IN AGITNTED VESSEL(Ⅱ)RULE OF SCALE-UP FOR STYRENE SUSPENSION POLYMERIZATION REACTOR

本文提出了液—液分散体系的放大准则,并推出了各个波数域内的几何相似和非几何相似放大准则。在5L 和130L 聚合釜中得到了苯乙烯悬浮聚合反应器的放大准则。苯乙烯悬聚合中影响粒径及其分布的因素甚多,如搅拌转速,分散剂浓度,相比,界面张力及两相粘度等,对反应器放大规律研究带来很大的困难。Hoff、Reichert 等在不同尺寸的聚合釜里对上述因素进行了比较系统的研究,得到一些经验的粒径关联式和放大方程,见表1。经验放大方程因实验条件不同而相差很大。本文在液—液分散理论分析的基础上,提出了液—液分散体系的放大准则,结合5L 和130L 聚合试验,确定苯乙烯悬浮聚合反应器的放大准则。

From the analysis of forces exerted on droplets in agitated vessels,it is found that the turbulent dispersing forces must be equal during reactor scale-up,if the dispersed mean size of droplets should be maintained the same,namely τ_=const·P_V^((m-1)/2)(ND)^(3-m)d^(m-1)=Constant For geometrically similar baffied vessels in turbulent conditions,the scale-up rule in different sub- ranges are given as follows: In inertial subrange N_2/N_1=(T_1/T_2)^(0.857) In Taylor's subrange N_2/N_1=(T_1/T_2)^(0.8) In viscous dissipation subrange N_2/N_1=(T_1/T_2)^(2/3) Suspension polymerization of styrene was carried out in 51 and 1301 reactors respectively,the scale-up rule obtained is τ_=Const·P_V^(1/2)(ND)_(32)=Constant The average diameter of the droplets or particles is 1～2 mm,and the flow belongs to the Traylor's subrange.