【作者】 王可；

【导师】 程榕； 杨阿三；

【作者基本信息】 浙江工业大学 ， 化学工程， 2003， 硕士

【摘要】 本文通过对流化床喷雾造粒涂布过程的理论分析，将涂布造粒过程分成三个阶段：碰撞、铺展和干燥(或冷凝)固化。本文综合了理论力学、弹性力学和传递原理的知识得出了判断液滴停留和铺展的力学判断式。并以玻璃珠为原始晶种分别在倒锥型和直筒型间歇式流化床喷雾造粒器中进行碳酸钾涂布造粒，考察了床层温度、料液流率、料液浓度和流化气速对颗粒粒径和体积增长的影响，并对两个流化床的实验结果进行了比较分析。结果表明，在倒锥型流化床中有较低的临界操作温度。在两个流化床中，料液浓度越高，流化气速越低则生长速率越快，而床层温度则呈现一定的非单调性。 本文通过实验值和理想涂布模型计算值的比较，提出了造粒过程中涂布效率问题。首次应用排队论的思想对涂布造粒过程进行了模拟，通过分析，建立了涂布过程通用的涂布效率表达式。在直筒型流化床中进行了喷雾造粒实验，研究了床层温度、流化气速和料液浓度等因素对涂布效率的影响，结果表明，它们对涂布效率的影响均是非单调的。一般都存在最优的床层温度、流化气速和料液浓度。本文还初步考察了两种结构的流化床对涂布效率的影响，结果表明倒锥型流化床更适合涂布造粒。应用排队论观点建立的涂布效率表达式能很好地解释以上各种实验现象。更多还原

【Abstract】 The mechanism of coating process in fluidized-bed spray granulation was analyzed theoretically firstly. The coating process can be divided into three stages-collision, extension and drying. There are two consequences after collision of droplets and fluidized particles, i.e. rebound or staying on the particles. As for those droplets capable of staying on the particles, they will not coat on the particles unless they extend. Through force analysis, an equation of whether the droplets will extend or not is studied. Subsequently, the coating process of potassium carbonate were studied in a taper fluidized-bed spray granulator and a cylinder fluidized-bed spray granulator respectively. The study indicates that there is a lower critical operating temperature in taper fluidized-bed than in cylinder fluidized-bed, besides, the higher fluid concentration and the lower fluidization velocity are, the faster the particles grow, but the operating temperature shows non-monotonous relationship with particles growth.Based on the preceding study on mechanism of coating process, the ideal coating model was established. Due to neglecting the coating efficiency, there were differences between experimental and modeling values. Therefore, it is of vital importance to study coating efficiency. The coating process in fluidized-bed spray granulation is similar to queuing system, therefore, the coating process is simulated with queuing theory in Operations Research originally. Then, the equation of coating efficiency is set up. In order to validate the expression of coating efficiency, the operating factors including fluidized-bed temperature, concentration of fluid and fluidization velocity were studied. It shows that there are optimal operating temperature, concentration of fluid and fluidization velocity during coating process.更多还原