FINE CONTROL OF HZSM-5’S PORE-OPENING SIZE BY A NEW CVD METHOD

A new CVD method without vacuum condition(CVDWV)was designed in this study,ithad been found that by modifying the flow rate of the carrier gas(N_2)and the temperature of sur-face reaction,silicon saturator and sample tube,the amount of silica deposited on the external sur-face of the zeolite could be precisely controlled,The changes in the physicochemical properties ofzeolite,such as pore-opening size,acidity and reaction property were investigated.The results ob-tained showed that:modification of the improved CVD method did not change the internal structureand acidity of the zeolite,but could bring about significant change of pore-opening size and reactionproperty as desired.     

多孔金属通孔度的控制

依据多孔金属的渗流制备原理,建立了控制通孔度的理论计算模型,研究了压差△Ｐ,球状填料半径Ｒ、金属液的表面张力σ以及金属液／颗粒间澜有θ对通孔度Ｉ的影响规律,实验证实该模型与实验结果良好吻合,可用于渗流法制备多孔金属时通孔度的定量控制。     

开孔形式对盘环形挡板汽提器特性影响的模拟分析

采用CFD方法对安置盘环挡板的汽提器进行了模拟计算,对比了盘环挡板上有无开孔情况下的颗粒流动分布。结果表明,在盘环挡板上进行开孔可有效减少“气垫”区域,使气体与颗粒更顺利地穿透挡板进行高效接触。此外,通过对比不同开孔形式下的催化剂颗粒流动与气泡分布特性,可以发现均匀开孔时,随着开孔尺寸的增加,气相流动阻力下降,可以携带颗粒更加均匀地穿过盘环挡板,使得挡板以下的“气垫”区域减小,颗粒在汽提器内分布更加均匀,有利于汽提蒸汽与催化剂颗粒之间的接触。但是,随着开孔尺寸增加,汽提器内气泡的平均尺寸有所增加,气泡数量减小,气泡所占的总体积及气泡所能提供的相界面积有所减少。对比均匀开孔与非均匀开孔的颗粒流动与气泡特性,结果表明,在盘形挡板顶部附近开孔12mm,其他区域均匀开孔9mm的非均匀开孔形式在确保催化剂颗粒流动的均匀性分布、汽提蒸汽与催化剂颗粒之间的接触效果的同时,容易产生更小的气泡,可以提供更高的气固相界面积,更加有利于汽提器性能的改善,因此是比较优选的开孔方式。本文关于挡板开孔形式影响的模拟分析对设计高性能的汽提器内构件具有重要意义。