An investigation on process of seeded granulation in a continuous drum granulator using DEM

Numerical simulation of wet granulation in a continuous granulator is carried out using Discrete Element Method (DEM) to discover the possibility of formation of seeded granules in a continuous process with the aim of reducing number of experimental trials and means of process control. Simple and scooped drum granulators are utilized to attain homogenous seeded granules in which the effects of drum rotational speed, particles surface energy, and particles size ratio are investigated. To reduce the simulation time a scale-up scheme is designed in which a dimensionless number (Cohesion number) is defined based on the work of cohesion and gravitational potential energy of the particles. Also a mathematical/numerical method along with a MATLAB code is developed by which the percentage of surface coverage of each granule is predicted precisely. The results show that use of continuous granulator for seeded granulation is promising provided that a high level of shear is considered in the granulator design, i.e. using baffles inside drum granulators is essential for producing seeded granules. It is observed that the optimum surface energy for seeded granulation in scooped granulator (used in this study) with rotational speed of 50 rpm is 3 J/m², which is close to the value predicted by the concept of Cohesion number. It is also shown that increasing the seed/fine size ratio enhances the seeded granulation both quantitatively (60% increase in seeds surface coverage) and qualitatively (more homogeneous granules).     

A novel approach to determine wet restitution coefficients through a unified correlation and energy analysis

Wet particle interactions are observed in many applications, for example, pharmaceutical, food, agricultural, polymerization, agglomeration, and coating, in which an accurate evaluation of the wet restitution coefficient (e_wet) is crucial to understand the particle flowability, operating conditions and product size distribution. Experiments were performed to measure the wet restitution coefficient by impacting a spherical particle on a stationary plate covered with a thin liquid layer of water or glycerol solution in this work. Furthermore, novel approaches for estimation of e_wet were developed using dimensional analysis (using the Buckingham π theorem and regression analysis) in combination with energy budget analysis. In the correlation development, the dominant physical properties of solid and liquid, particle impact velocity and liquid layer thickness are grouped into well‐known dimensionless numbers viz. Reynolds, Weber and Stokes. Whereas in the energy analysis, the energy dissipation rates were determined for five distinct collision phases, that is, dipping, dry collision, undipping, formation and breakage of the liquid bridge, and added mass. The efficacy of the developed approaches was analyzed by comparing obtained results with experiments and an elastohydrodynamic model, and a modified elastohydrodynamic model. © 2014 American Institute of Chemical Engineers AIChE J, 61: 769–779, 2015     

大颗粒尿素造粒机流化风道的改造

通过对大颗粒尿素在流化床中的运动分析,将日本东洋工程公司（TEC）大颗粒尿素造粒机的流化风道设计高度由1000mm变更为900mm。改造后,流化床层的流化状态未受影响,操作中各种参数无需改变,并且可以减轻清洗造粒机时稀尿液对风道及风门的腐蚀。     

硝铵磷生产在线更换造粒机喷头的技术

针对硝铵磷装置在运行过程中,因原料磷酸一铵中含有不熔颗粒物等造成造粒机喷头堵塞、塔壁物料黏结严重,云峰分公司采取相应的解决措施,包括控制喷头转速、在线更换造粒机喷头。详细介绍在线更换造粒机喷头的步骤及注意事项。经过改进,产品质量提升,装置运行周期由7 d延长至180 d。     

Effects of process parameters on granules properties produced in a high shear granulator

Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder. The dried granules have been analysed for their strength, density and size distribution. The results show that increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. The underlying cause is an increase in granule density. Granules are consolidated more at higher impeller speeds. Moreover, the granule size distribution seems not to be affected significantly by an increase in impeller speed. Granules produced with high binder viscosity have a considerably lower strength, wide strength distribution due to poor dispersion of binder on the powder bed. Binder addition methods have showed no considerable effect on granule strength or on granule size distribution.     

新型喷雾造粒喷嘴内闪蒸过程数值模拟

根据戊烷闪蒸相变中的传质传热规律,改进了戊烷闪蒸过程的经验模型,并将其植入到CFD软件Fluent中,较为准确地预测闪蒸雾化的非平衡热力学过程。对新型喷雾造粒喷嘴内气液戊烷和沥青的三相闪蒸流动过程进行了数值模拟,结果显示:介质在新型旋流喷嘴内呈现分层流动,能够控制戊烷闪蒸速率,可以制备质量较好的沥青颗粒。     

挤压力对干法制粒机挤压辊运行特性分析

干法制粒机液压系统多采用普通电磁阀控制,即使采用了电液比例阀,也未形成闭环控制。针对此问题,基于电液比例技术对200型干法制粒机液压系统进行改进设计。依据挤压辊颤振力学模型,推导其竖直方向运动微分方程。利用AMESim和ADAMS软件构建机液联合仿真模型,研究不同的挤压成型压力对挤压辊运行特性的影响规律。结果表明：挤压辊运行特性较为平稳,挤压成型压力对位移特性的影响可以忽略不计;在系统启动瞬间,挤压辊速度和加速度波动峰值达到最大值;适当增大挤压成型压力,可有效改善挤压辊的速度和加速度波动特性;挤压成型压力对角加速度的影响要大于对角速度的影响。     

磷酸铵类肥料技术讲座

这一讲着重介绍用浓缩磷酸经槽式预中和获得磷铵料浆,然后在转鼓氨化造粒机中造粒的机理和操作条件.同时阐述了转鼓氨化造粒机的构造以及用于生产MAP、DAP和NPK复合肥的条件.     

水下切粒设备国产化之路

对国产水下切粒设备研制开发过程进行回顾。并介绍了国产水下切粒设备技术上的独特优势 ,各种型号设备的技术参数和未来的开发方向。经用户使用证明 ,已达到国外同类设备的先进水平 ,完全可以替代进口。     

有机型复合颗粒肥生产线设计

介绍了有机型复合颗粒肥生产线的设计，对生产线的主设备制粒机的改制进行了研究，且取得成功。