共查询到20条相似文献,搜索用时 62 毫秒
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This article presents a mathematical model of heat and mass transfer for the process of fluidized-bed spray granulation, which can be applied in the analysis of bed temperature profile, temperature and humidity of outlet gas and moisture content of particles. Effects of operation parameters on the batch granulation are investigated. The theoretical calculation agrees reasonably well with the experimental data.Keywords fluidized-bed spray granulation, mathematical model, heat and mass transfer 相似文献
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喷雾流化床造粒的层式生长模型试验 总被引:2,自引:0,他引:2
本文对喷雾流化床造粒过程中颗粒的层式生长进行了理论分析研究,得出了造粒层式生长模式下颗粒质量随操作时间变化的线性增长模型,并通过喷雾流化床对玻璃球的包衣试验对此进行了验证。试验表明,颗粒相对质量的增长速率大小可用来初步判断造粒过程颗粒的成长方式。 相似文献
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<正> 一、前言 染料喷雾造粒技术在我国应用已有二十多年的历史,因为采用该技术生产的产品为颗粒状,所以除保持染料原有特性外,与粉状染料相比,具有化料快,降低粉尘飞扬,改善生产和使用环境等优点,深受生产及应用部门的欢迎。近年来,在国际市场上颗粒状染料十分走俏,我国出口染料也以颗粒状居多。 然而,粒状染料的生产一般采用压力式雾化器进行喷雾造粒,由于受雾化器结构的 相似文献
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Xiaoheng PAN Shichao YE Zeguang ZHANG Li ZHANG Xuejun ZHU 《Frontiers of Chemical Engineering in China》2009,3(1):78-82
The granulation process in a vibrated fluidized bed with immersed horizontal heating tubes was studied in this paper, with
small monoammonium phosphate particles as the initial particles and monoammonium phosphate solution sprayed on them. The concrete
influences on the granulating performance of the immersed horizontal heating power, fluidizing gas velocity, vibration frequency
and amplitude had been analyzed theoretically. The results show that appropriate vibration intensity is a preferred condition
for the growth of partials, but the fine dust will become much more along with prolonged vibration. Increasing the heating
power is beneficial to raise the growth rate. Particles will grow faster if the fluidizing gas velocity is higher, but this
will cause more fine dust. The optimized condition of A = 0.002 m, f = 6.67 Hz, u = 1.4 m/s was given after the analysis of the experimental results. In the end, a semiempirical formula was derived from
the experiment data, and the calculation results show good agreement with the experimental data. 相似文献
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Air temperature measurements in a fluidized bed of glass beads top sprayed with water showed that conditions for particles growth were fulfilled only in the cold wetting zone under the nozzle which size and shape depended on operating conditions (liquid spray rate, nozzle air pressure, air temperature, and particles load). Evolution of the particle size distribution during agglomeration was modelled using population balance and representing the fluidized bed as two perfectly mixed reactors exchanging particles with particle growth only in the one corresponding to the wetting zone. The model was applied to the agglomeration of non-soluble glass beads and soluble maltodextrin particles spraying respectively an acacia gum solution (binder) and water. Among the three adjustable parameters, identified from experimental particle size distributions evolution during glass beads agglomeration, only one describing the kinetics of the size distribution evolution depended on process variables. The model allowed satisfying simulation of the evolution of the particle size distribution during maltodextrin agglomeration. 相似文献
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In this paper, we investigate numerically the influence of conical nozzle attachments on spray dispersion in a fluidized bed. We utilize an Eulerian approach to simulate flow through the nozzle and subsequent interactions between droplets and solid particles. We use process parameters and material properties relevant to the fluid coking process – bitumen upgrading by thermal cracking – by approximating available experimental data. After considering several attachments with varying expansion angles, we discovered that the best liquid distribution is obtained with the 40° angle attachment because of the jet instabilities facilitated by such a shape of an attachment. 相似文献
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Atsushi Tsutsumi Hidehiko Suzuki Yasushi Saito Kunio Yoshida Ryohei Yamazaki 《Powder Technology》1998,100(2-3):237-241
The granulation of multi-component particles was conducted in a fast fluidized bed with an atomizing binder solution. The effects of gas velocity and binder droplet diameter on granulation rate, granule size distribution and granule composition were studied. The granulation rate and granule yield were determined by the balance between the agglomeration rate of feed particles and the disintegration rate of granules because there was no secondary granulation. With the increase in gas velocity and the reduction in binder droplet size, the agglomeration rate of feed particles decreased but the disintegration rate of granules increased, resulting in a reduced granule yield. Despite the larger fraction of small particles in the granules, the homogenous granulation of multi-component particles was achieved. 相似文献
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Stefan Heinrich Mirko PeglowMatthias Ihlow Markus HennebergLothar Mörl 《Chemical engineering science》2002,57(20):4369-4390
A physics-based population balance model is constructed for continuous fluidized bed spray granulation with internal and external separations. A balance area around the granulator and around the separator is described, including all input and output particle and mass flows. A simplified growth and attrition model is developed for the diameter change of the particles in the granulator. The population balances facilitate the calculation of the particle size distributions changing over time in the fluidized bed and in the product flow. It is demonstrated that an unsteady start-up phase occurred in every case, which possibly leads to instability (oscillating behaviour). This may be regulated by controlling the overall nuclei balance. 相似文献
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Particulate processes involve different kinetic processes such as formation of nuclei, their subsequent growth and breakage. In addition, external product classification can play a significant role. A reliable prediction and thorough understanding of potential sources for instability is not only of scientific interest but also an important issue for better process design and process control.The application of these nonlinear dynamics is concerned with fluidized bed spray granulation. Self-sustained oscillations may rise in processes with external product classification.Therefore, focus of this work is on process stability which can be influenced by classifying, milling and recycling of particles and by the production of internal and external seeds.First a brief introduction to the model is given, that couples the particle population state with thermodynamic-, fluiddynamic- and granulation process for a unit with non-classifying product discharge and a screening and milling unit in the seed recycle and builds the core of the software package AVA®FBSim®, used for the experiments. 相似文献
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喷动流化床造粒实验研究 总被引:1,自引:0,他引:1
喷动流化床用于粉体造粒,是一种新型的造粒方法。与其它几种造粒方法相比.具有设备投资省、能耗低、设备结构简单等优点。作者经过实验发现,气流雾化器安装于底部或侧部,或是二者结合。可实现对多种粉体的造粒和包衣。气流雾化喷嘴是喷动流化造粒装置的主要部件。为此对气流雾化喷嘴作了一些实验研究。 相似文献
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A novel discrete element spray granulation model capturing the key features of fluidised bed hydrodynamics, liquid-solid contacting and agglomeration is presented. The model computes the motion of every individual particle and droplet in the system, considering the gas phase as a continuum. Microscale processes such as particle-particle collisions, droplet-particle coalescence and agglomeration are directly taken into account by simple closure models. Simulations of the hydrodynamic behaviour of a batch granulation process are presented to demonstrate the potential of the model for creating insight into the influence of several key process conditions such as fluidisation velocity, spray rate and spray pattern on powder product characteristics. 相似文献