双喷嘴矩形导流管喷动床喷动压降

引言 传统的柱锥形喷动床(CSBs)的应用受到一些因素的限制,例如处理物料能力、起始压力大及难以放大等,为此,Romankov等[1]最早提出了长方形截面的矩形喷动床结构,来克服CSBs的缺点.此后,Rocha等[2]用矩形喷动床进行了片剂包衣的研究.     

带导流管液固喷动床的最小喷动速度研究

在截面为矩形有机玻璃喷动床内,使用四种粒径的窄筛分球形玻璃珠,以常温水作为喷动和辅助液体。综合考虑床体的几何尺寸、操作参数以及液体和颗粒的物性特征,系统研究带导流管喷动床的最小喷动速度,得出最小喷动速度的经验公式,为设计和操作提供参考。     

双喷嘴矩形导流管喷动床脱硫性能的研究

针对半干法烟气脱硫方法,提出了一种新型的双喷嘴矩形导流管喷动床半干法烟气脱硫装置。在不同的钙硫摩尔比、静床层高度、表观气速、绝热饱和温差下,以消石灰为脱硫剂,研究了该装置的脱硫性能,并与未加导流管的双喷嘴矩形喷动床的脱硫性能进行了比较;研究了不同脱硫剂流量下导流管喷动床的喷动压降。实验结果表明:脱硫率与钙硫摩尔比、静床层高度成正比,与绝热饱和温差、表观气速成反比;喷动压降与脱硫剂流量成反比。并最终得出了实验条件下双喷嘴矩形导流管喷动床的最佳操作范围和脱硫率关联式。     

带导流管的喷动流化床的研究进展

综述了带导流管的喷动流化床的研究和发展现状,在湍流气固两相流理论的基础上讨论其流体力学特性;同时指出了研究中存在的问题和进一步研究的方向。     

矩形导流管喷动床下行区的床层压降

带导流管的矩形喷动床是传统喷动床的改进型式,矩形床内设置的与床同厚的垂直导流管,可以控制固体颗粒的内循环速率,同时使下行区中的气固移动床维持平推流.本文实验测定了不同表观气速、床层重量、不同固体颗粒与气体入口形式与尺寸时,矩形导流管喷动床下行区的床层压降,以考察其流动特征.实验结果表明,下行区存在床层压降的轴向分布,气固流动处于负压差下移上流区,且气固滑移速度自下而上是逐渐下降的.下行区颗粒床层的压降以及颗粒的移动下输,受到喷动床表观气速、床高、喷嘴尺寸、物料种类和颗粒直径的不同影响.     

二维导流管喷动床离散颗粒动力学模拟

采用离散单元法(DEM)-计算流体力学(CFD)双向耦合数值方法对二维导流管喷动床进行了模拟,颗粒的运动通过DEM模型描述,而气体的运动用Navier-Stokes方程进行求解,气体和固体颗粒之间的相互作用通过曳力形式传递。文中将DEM和边界元方法(BEM)结合起来解决颗粒在具有复杂边界设备内的运动。通过采用BEM+DEM-CFD相结合的方法进行模拟计算,得到了喷动床的最小喷动速度,研究了不同表观气速下床内的流型,得到了二维导流管喷动床的床层压降与表观气速的关系,统计分析了喷射区、环隙区内颗粒的运动速度和相应的空隙率,全面地描述了二维导流管喷动床内的气固流动特征。     

双喷嘴矩形喷动床流动性能实验研究

在120 mm×240 mm的双喷嘴矩形不锈钢床内,对新型双喷嘴矩形导流管喷动床的最小喷动速度和喷动高度进行了研究,考察了喷动气速、粒径、静床层高度、导流管直径、导流管安装位置对最小喷动速度和喷动高度的影响。结果表明:最小喷动速度随颗粒直径、导流管直径、导喷距的增大而增大,随静床层高度的增大而减小;喷动高度随喷动气速的增大而增大,随导流管直径的增大而减小,受静床层高度和导喷距的影响不大,并得出了最小喷动速度的关联式。     

液固导流管喷动流化床流型及流型转变的实验研究

以粒径为0.9mm的铜颗粒为流化颗粒,常温水为流化介质,在截面为59.2×15.6mm的矩形床中,对液固导流管喷动流化床的流型及流型转变进行实验了研究。通过对床层压降流量曲线的分析并结合实验观察,确定了液固导向管喷动流化床的流型及流型的划分,提出了流型图。研究结果对进一步开展导流管喷动流化床电极研究有重要的参考意义。     

大尺寸喷动床最低喷动速度的估算

最低喷动速度是喷动床设计的重要参数之一。过去人们习惯采用Mathur-Gisher公式来计算,但由于该公式是建立在小直径床层(D_c=0.076～0.3m)实验的基础上的,故在大直径床层上应用时,产生明显的偏差。本文通过实际数据分析,提出了大直径喷动床层最低喷动速度计算的经验公式。     

导向管液固喷动床的数值模拟研究

本文以液-固两相流理论为基础,用颗粒动力学理论描述颗粒与颗粒间的碰撞,用标准湍流方程模拟液相和颗粒相的湍动,并且考虑液-固两相的相互作用,旨在探索一种工程设计和放大的新方法。对比颗粒循环速率和密相区真实液相流速的模拟结果与实验值,结果吻合较好。     

超细粉在导向管喷动床中的流化行为

以料径5μm的CaCO3超细粉为物料,对其在半圆形导向管喷动床中的流化行为进行研究,考察床层压降特性及喷嘴直径、导喷距及导向管直径对起始流化行为的影响。     

喷动床研究与进展

叙述了近年来出现的几种改型喷动床,包括多喷头喷动床、喷动流化床、带导向管的喷动床、性粒子旋转射流式喷动床、射流喷动床的研究与进展。它们在传统柱锥形喷动床的基础上,通过增加喷口、导向管、流化气、惰性粒子或增加喷动气速等方法,来克服原有喷动床应用的局限性,拓展其应用领域。     

Drying of Pharmaceuticals: The Applicability of Spouted Beds

This study evaluates the performance of conventional spouted beds (CSB) with inert bodies in the drying of pharmaceutical pastes, based on the dry product quality. The powder obtained by drying annatto extracts shows properties comparable to one of the commercial products, indicating that the spouting is competitive with other industrial and lab-scale processes. The contents of bixin and caffeine in annatto and guarana dry powders demonstrated a strong dependence on the inlet air temperature. Also, the properties of indomethacin-containing microcapsules dried in CSB and spray dryers revealed that spouting is a promising technique to obtain pharmaceutical forms with unique drug release qualities.     

Drying of Pharmaceuticals: The Applicability of Spouted Beds

ABSTRACT

This study evaluates the performance of conventional spouted beds (CSB) with inert bodies in the drying of pharmaceutical pastes, based on the dry product quality. The powder obtained by drying annatto extracts shows properties comparable to one of the commercial products, indicating that the spouting is competitive with other industrial and lab-scale processes. The contents of bixin and caffeine in annatto and guarana dry powders demonstrated a strong dependence on the inlet air temperature. Also, the properties of indomethacin-containing microcapsules dried in CSB and spray dryers revealed that spouting is a promising technique to obtain pharmaceutical forms with unique drug release qualities.     

导向喷动流化床颗粒物料抛高的估算

本文以气固两相流运动理论为基础，进行导向喷动流化床颗粒物料抛高估算，从而确定导向喷动流化床床高。计算结果与实验测定值吻合颇好。     

Flow in the annulus of a bed of fine particles spouted with water

The flow in the annulus of a water spouted bed of glass particles (275 to 774 μm) was studied experimentally in a cylindrical half-column 50.8 mm in diameter. An axisymmetric model, which assumes Darcy flow in the annulus and uses the experimental spout pressure distribution, predicts the flow and pressure fields in the annulus. The substantial differences between this flowfield and that for coarse particle beds that are observed are caused by differences in the normalized interfacial pressure profile. The model predicts that both the fluid velocity and the normalized fluid velocity at the top of the annulus decrease as the particle size and bed height are reduced. Particles are observed to enter the spout primarily near the spout inlet in agreement with predictions of the axial spout voidage distribution. The residence time distribution of the fluid in the annulus is relatively broad and the measured residence times are about 25% higher than those calculated.     

导向充气喷动床的临界充气速度

１前言在普通喷动床的环形区底部额外引入一股辅助气体,由于喷动气体和辅助气体各自独立地改变,气固系统将出现下列几种体系或操作状态：①固定床;②充气喷动床;③喷流床;④带射流的流化床。长期以来对充气喷动床与喷流床的区别不是很清楚的［１～５］。张怀清等［６...     

Spouted Beds of Inert Particles for Drying Suspension

ABSTRACT

A brief review of Brazilian research on drying process in spouted beds shows its relevance and evolution trends. Needs for applying this technique to dry pasty materials are discussed, focusing on a new model approach in order to overcome operational problems with particle agglomeration and with thermal efficiency. Based on this approach, two cases, drying of black liquor in a conical spouted bed of inert polypropylene particles under intermittent operation and drying of egg emulsion in a conical spouted bed of inert glass beads under continuous operation, are presented and analyzed.