流化床喷雾造粒技术在废水处理中的应用

论述了流化床喷雾造粒技术在废水中提取有用物质工艺上的应用及意义。     

流化床喷雾造粒的研究进展

对流化床喷雾造粒技术进行了简述,对其颗粒成长机理、造粒影响因素和造成聚变失稳因素进行了归纳,并就其发展前景作了展望。     

流化床喷雾造粒技术进展

本文介绍了流化床喷雾造粒技术,包括造粒机理、操作方式、影响因素等。流化床喷雾造粒是将溶液、悬浮液或熔融液喷雾到已经干燥或不完全干燥颗粒的流化床床层内,在同一设备内一步完成蒸发、结晶、干燥或化学反应的造粒过程。流化床造粒操作对颗粒的尺寸、形状要求不高,所得到的产品无结块、具有良好的流动性能。与其他传统的造粒方法相比,流化床造粒具有工艺流程简单、设备装置紧凑、投资省、生产强度大等优点,越来越引起人们的关注。     

流化床喷雾造粒过程的传热传质

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     

喷雾流化造粒技术在硫酸锰生产中的应用

硫酸锰不仅是一种重要的化工原料,也是一种重要的饲料添加剂和肥料添加剂,它广泛用于医药、食品、农药、造纸、催化剂等行业。所介绍的硫酸锰生产新工艺,能解决传统硫酸锰生产过程繁琐、流程长、造粒周期长、操作复杂、能耗高、环境污染严重等问题。     

流化床造粒的研究进展

简述了流化床造粒的主要方法，阐述了造粒的机理主要是团聚和涂布两种过程，总结了影响造粒的因素和研究造粒过程中提高团聚效率的方法，并对流化床今后的研究方向进行了展望。     

流化床喷雾造粒颗粒包覆过程的因素研究

以玻璃珠为原始晶种分别在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;结果表明,料液浓度越高。流化气速越低,其生长速率越大,而床层温度则呈现一定的非单调性。     

底部进料流化床喷雾造粒器内尿素造粒过程

在下端直径２００ｍｍ、上端直径３９０ｍｍ、高１０００ｍｍ的圆锥形流化床喷雾造粒器内,研究了尿素颗粒的生长规律和机理．料液从底部喷入床层,颗粒生长完全由分层生长控制,增大料液流量和降低床层温度,颗粒的粒径生长速率增大．床层内的温度分布类似于开口向上的抛物线,径向上温度差别大,轴向上温度差别小,中心轴线上温度最低,温度随径向距离的增大而升高．产品颗粒与塔式造粒产品颗粒相比,抗压强度明显提高．     

喷雾流化床造粒的层式生长模型试验

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。     

气力输送技术在染料喷雾造粒中的应用

<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     

A study of spray granulation in vibrated fluidized bed with internal heating tubes

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.     

Identification of thermal zones and population balance modelling of fluidized bed spray granulation

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.     

Influence of conical nozzle attachments on horizontal spray dispersion in a fluidized bed

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.     

Multi-component granulation in a fast fluidized bed

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.     

Analysis of the start-up process in continuous fluidized bed spray granulation by population balance modelling

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.     

Investigating the dynamic behaviour of fluidized bed spray granulation processes applying numerical simulation tools

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.     

喷动流化床造粒实验研究

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。     

双级流化床干燥装置及其应用

介绍了双级流化床干燥的原理、特点和工艺流程 ,并对两级不同结构和工况的流化床组合方式之合理性进行了说明。此外 ,还列举了若干工业装置运行实例 ,并将其使用情况同传统的干燥装置进行了对比。     

流化床制粒过程颗粒水分预测研究

对流化床进行工程化改造,安装近红外光谱仪,对制粒过程中的颗粒水分含量进行光谱采集。采用偏最小二乘法(PLS)、粒子群-核岭回归(PSO-KRR)和随机森林-偏最小二乘法(RF-PLS)建立回归模型,对不同的算法的预测精度进行了研究。结果表明,PLS模型预测集均方根误差(RMSE)为0.218 0,相关系数R为0.971 7;PSO-KRR模型预测集RMSE为0.215 4,R为0.973 8;RF-PLS模型预测集RMSE为0.205 9,R为0.973 3。其中RF-PLS模型的预测效果最好。     

Discrete element modelling of fluidised bed spray granulation

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.