Microencapsulation in foam spray drying

Abstract

The article presents the results of the experiments of gas-admixing foam spray drying microencapsulation of oil in co-current spray drying tower. The introduction of a foaming gas resulted in a decrease of encapsulation efficiency: for high foaming gas/liquid ratio (GLR) 6.43·10^?3 kg/kg and T_air,0=215?°C by over 50% relative to the non-foaming process due to damage of the microcapsule structure and leakage of the oil phase to the particle surface. For moderate drying temperatures and GLR, 80% of microencapsulation efficiency might be achieved with simultaneous control of selected product properties like apparent and bulk density or angle of repose. Abbreviations GLR gas-to-liquid ratio

HR Hausner ratio

MDX maltodextrin

PSD particle size distribution

SEM scanning electron microscope.

     

压力喷雾干燥在聚氯化铝生产中的应用

近几年中国开始采用喷雾干燥生产高品位固体聚氯化铝，以适应国际产品的市场要求。笔者对采用压力喷雾干燥和离心喷雾干燥生产固体聚氯化铝进行了比较，通过实例介绍了压力喷雾干燥生产应用情况，并对生产影响因素和改进措施进行了论述。     

Recent advances in biofuel drying

Sweden must be regarded as one of the leading countries to utilize biofuels for heating purposes. A national survey of technique and economy for biofuel drying systems has therefore been deemed to be of wider interest. As well flue gas dryers as steam dryers are used but in different applications. Operating experiences from both types are reported. A thermodynamic analysis of various system solutions is also performed. Rotary flue gas dryers dominate the market in fuel factories, which are not colocated with other industrial activities. Steam dryers are best suited for integrated systems, where their capability for heat recovery can be exploited. A new approach is to recover electricity instead of heat. This is accomplished in a system integrated in a district heating plant with power cogeneration. The environmental issues are of ever increasing concern and the release of volatile organic compounds (VOC) during drying and influence of the fuel moisture content on emissions from the combustion are discussed.     

Sampling method for studying the activity of lactic acid bacteria during spray drying

In this study, a novel sampling method was established to study changes in the activity of lactic acid bacteria during spray drying. Before spray drying, a sampling device with a refrigerant and a magnet was pre-cooled and positioned in a spray-drying tower. Carbonyl iron powder (CIP) was added to the drying media to increase the sampling mass by the magnetic effect. During drying, a temperature sensor measured the particle contact temperature. After drying, the sample in the sampling device was taken out to analyze the characteristics, including the mass, water content, and bacteria livability in the sample. The sampling device and method were optimized with a sampling cup with a depth of 3.5?cm (for contact temperatures below 79.1°C) or 5?cm (for contact temperatures below 89.1°C). The ratio of CIP to reconstituted skim milk (RSM) was 1:10, and RSM concentration was not lower than 20% (w/w). This method was then applied to spray drying of Lactobacillus bulgaricus sp1.1. Furthermore, it was demonstrated that 2?mL of sterile water placed in the sampling cup prior to drying resulted in a more accurate measurement of cell viability. This sampling method can be used in practical spray drying applications for biological materials without using a special instrument or drying tower.     

A one-dimensional plug-flow model of a counter-current spray drying tower

A one-dimensional numerical model for a detergent slurry drying process in a counter-current spray drying tower is developed for the prediction of the gas and droplet/particle temperature profiles within the tower. The model accommodates droplets/particles over a range of sizes. A semi-empirical slurry droplet drying model is integrated with a counter-current tower simulation based on mass, energy and particulate phase momentum balances in order to calculate the drying rate and the particle residence time within the tower. The coupled first order ordinary differential equations for the two phases are solved numerically using the iterative shooting method in an algorithm developed within MATLAB. The predictions of the numerical model are compared with industrial pilot plant data. The results are found to vary significantly with the specified size distribution of the droplets. Despite the simplicity of the model in ignoring the coalescence, agglomeration, wall deposition and re-entrainment, the model gives reasonable agreement with the experimental data.     

Reduction of a model for single droplet drying and application to CFD of skim milk spray drying

In this work, a novel methodology for the development of a high-accuracy computational fluid dynamics (CFD) model for the spray-drying process is described. Starting point is an own spatially resolving model of droplet/particle drying, which was developed and validated on the basis of a series of single droplet drying (SDD) experiments. This sophisticated model is transformed to a much simpler version: the characteristic drying curve approach, after running the full SDD model in a wide range of operating conditions. Then, the obtained reduced model is implemented into the CFD solver. The CFD spray-drying model takes into account the hydrodynamics of the continuous phase, particle drying kinetics, changes in the particle diameter, and the heat loss from the drying chamber to the environment. Validation of the entire procedure is provided by data obtained from drying experiments performed in a co-current laboratory spray tower. High accuracy of the developed CFD model of skim milk spray drying has been found for both phases, for the mean outlet temperature of the continuous phase (air) and for the change in average particle moisture content along the spray tower (discrete phase).     

Solvent evaporation and spray drying technique for micro- and nanospheres/particles preparation: A review

This article presents a comprehensive review of research relating to the preparation of biodegradable and biocompatible controlled/sustained release of micro and nanoparticles. It covers recent developments in the area of technology through solvent evaporation followed by lyophilization and spray drying. The last decade seen a shift from empirical formulation efforts to a technological approach based on better understanding of micro and nanoparticle formation in the solvent evaporation and spray drying technique. This review provides concepts and a theoretical framework for the preparation of micro and nanoparticle formation. Encapsulation of pharmaceutical materials has received much attention due to enhanced effectiveness, bioavailability, and the dissolution rates that can be achieved. Polymeric micro and nanoparticles can be used to transport drug in a rate-controlled and sometimes targeted manner. Initially, laboratory-scale experiments are performed, but for industrial scale-up, experiments are required using sophisticated technologies. The objective of this review article is to summarize the solvent evaporation and spray drying techniques for the preparation of biodegradable and biocompatible controlled/sustained release of micro and nanospheres/particles with focus on the steps involved in its preparation, materials used, and the technique of microencapsulation. The review also summarizes recent research on solvent evaporation and spray drying.     

液雾燃烧大涡模拟的应用研究进展

液雾燃烧数值模拟在能源、交通、化工冶金和航天航空等工程中有广泛的应用,近年来,大涡模拟研究尤其受到重视,不仅在基础研究领域中,而且在朝着工程应用方向发展,特别是在内燃机燃烧室和燃气轮机燃烧室液雾燃烧数值模拟中的应用。目前液雾燃烧大涡模拟被认为是工程上最有应用前途的CFD数值模拟方法,可以显示流动和燃烧发展的动态过程,而且其统计结果比雷诺平均模拟(RANS)的更精确。但是还存在一些有待解决的问题,主要是亚网格模型和模拟结果的详细实验检验。本文就此领域的研究进展,包括作者最近的研究,进行了简要的评述,讨论了进一步研究的问题。     

Physical and chemical properties of powder produced from spray drying of inulin component extracted from Jerusalem artichoke tuber powder

In this study, inulin was extracted from Jerusalem artichoke tuber (JAT) powder and then concentrated before spray drying. The aims of this study were to (1) determine the drying condition that provided high powder yield together with superior qualities of JAT inulin powder and (2) investigate the chemical and physical properties of inulin powder. The inulin extracts at different concentrations of 10, 20, and 30 °Brix were spray-dried and then compared. The spray drying experiments were conducted at the inlet/outlet air temperatures of 150/90, 170/90, and 190/90?°C for the chosen concentration of inulin extract. It appeared that spray drying of the 30 °Brix extract at the inlet/outlet drying air temperatures of 190/90?°C resulted in the highest value of powder recovery, bulk density, water solubility and the lowest moisture content and hygroscopicity in comparison with its counterparts. SEM micrographs showed that the powder produced by this condition was more stable and less sticky than others. The sugars, total fructo-oligosaccharides (1-kestose, nystose, and 1^F-β-fructofuranosyl nystose) and inulin-type fructans contents of powder were 12.88, 11.12, and 64.36?g/100?g of powder, respectively. The moisture sorption data and models developed in this work could be used for determining the suitable condition of surrounding air for inulin powder storage.     

CFD modeling of a pilot-scale countercurrent spray drying tower for the manufacture of detergent powder

A steady-state, three-dimensional, multiphase computational fluid dynamics (CFD) modeling of a pilot-plant countercurrent spray drying tower is carried out to study the drying behavior of detergent slurry droplets. The software package ANSYS Fluent is employed to solve the heat, mass, and momentum transfer between the hot gas and the polydispersed droplets/particles using the Eulerian–Lagrangian approach. The continuous-phase turbulence is modeled using the differential Reynolds stress model. The drying kinetics is modeled using a single-droplet drying model, which is incorporated into the CFD code using user-defined functions (UDFs). Heat loss from the insulated tower wall to the surrounding is modeled by considering thermal resistances due to deposits on the inside surface, wall, insulation, and outside convective film. For the particle–wall interaction, the restitution coefficient is specified as a constant value as well as a function of particle moisture content. It is found that the variation in the value of restitution coefficient with moisture causes significant changes in the velocity, temperature, and moisture profiles of the gas as well as the particles. Overall, a reasonably good agreement is obtained between the measured and predicted powder temperature, moisture content, and gas temperature at the bottom and top outlets of the tower; considering the complexity of the spray drying process, simplifying assumptions made in both the CFD and droplet drying models and the errors associated with the measurements.     

喷雾干燥技术在PVC糊树脂生产中的应用

简单介绍了目前PVC的生产情况,指出PVC糊树脂的市场需求量较大,一些企业准备扩产或对原装置进行改造。详细介绍了喷雾干燥技术在PVC糊树脂生产中的应用情况。     

Flame spray drying: Droplet and particle flow dynamics

ABSTRACT

The work presents the fundamental research of dispersed phase flow during flame spray drying. Particle dynamics analysis and laser Doppler anemometry technique were applied to determine particle size distribution and particle velocity distribution. Results of the study showed that stable combustion and longer length of the flame were observed for coarse spray (large droplets, low atomization pressure, small spraying angle, and low concentration of droplets in spray). Particle residence time in the combustion zone is the main factor affecting the increase in particle diameters due to puffing. Complex flow dynamics of dispersed phase observed at the outward regions of the flame in recirculation zones results in the formation of particle agglomerates.     

Following the drying of spray paints using space and time contrast of dynamic speckle

The short drying times of spray paints are of great benefit in some applications, and this property allows for painting over almost-immediately. However, this fast-drying process precludes following it using conventional techniques. In a previous article, we used the dynamic speckle to follow the drying process of solvent-based and water-based paints with relatively long drying times, and recently we developed alternative speckle contrast methods to characterize faster processes. This article presents the application of these methods using dynamic speckle techniques to study the drying of a spray paint. Activity image display is also included.     

Lactose hydrolyzed milk powder: Thermodynamic characterization of the drying process

Industrial production of lactose hydrolyzed milk powder (LHMP) remains challenging. Due to the presence of the monosaccharides glucose and galactose, lactose-free powders tend to suffer stickiness, caking, and browning during drying and storage. We sought to find ideal conditions spray dryer inlet air temperature (θ_air,in) and concentrated milk flow rate (m_CM) for LHMP production. We tested θ_air,in settings of 115–160°C and m_CM of 0.3–1.5?kg?·?h^?1, and also applied mass and energetic balances. LHMP generally exhibited higher mass and energetic losses than the control (milk powder containing lactose), as a consequence of the relatively low dryability of LHMP. For a lab scale spray dryer, the ideal conditions settings for LHMP production were θ_air,in?=?145?±?2°C and m_CM?=?1.0?kg?·?h^?1, taking into account the mass yield and energetic cost (kJ?·?kg^?1 of powder) of the process. These ideal conditions are a potential tool for the industrial development of lactose-free dairy powders.     

水泥厂用导料槽的改进

<正>0前言带式输送机在运行过程中,在溜槽与导料槽之间经常会出现撒料溢尘现象,存在较严重的环境污染。为解决上述问题通常采用的方法是加装除尘器、洒水装置等。这些方法虽然在一定程度上暂时解决了问题,但需要长期和经常性的维护,这无疑增加了维护工作量,也增加了成本。针对撒料溢尘     

喷雾干燥法脱硫在水泥企业中的应用实践

水泥企业存在因煤质的变化和原材料成分的变化造成SO2超标现象,很难有效控制。针对此种情况,介绍一种喷雾干燥的脱硫方法,并以实际生产为例,分析了水泥生产过程中硫的来源及在系统中各个部分的存在形态,喷雾干燥法工艺流程及生产情况。该方法应用在新型干法熟料生产线上,取得了一定的效果。     

确定喷雾干燥中雾滴粒度分布的轨迹分析法

由于喷雾干燥中雾滴的运动较复杂,所以目前多是通过实验测量来确定雾滴粒度分布,有限多不便因素。通过模拟粒子受力情况以及与空气的传质传热,采用时间增量法和拖动坐标系逐步跟踪粒子的运动轨迹,建立数学模型,再结合实验中样板取样所得到的数据,即可确定喷雾干燥中雾滴粒度分布。     

Redox (pro-oxidant/antioxidant) balance in the spray drying of orange peel extracts

ABSTRACT

Phenolic compounds have been reported to show both antioxidant and pro-oxidant properties. The effects of spray drying conditions on the balance between antioxidant and pro-oxidant properties of orange peel extract have been evaluated in this work. The inlet drying temperatures (ranging between 100 and 175°C) gave no significant effect on the redox recoveries. On the other hand, the main air flow rate (between 28 and 38?m³/h) and feed pump rate (between 4 and 7?mL/min) significantly affected the pro-/antioxidant recovery ratio. The ratios of pro-/antioxidant recovery were found to be between 1.00 and 1.13, and the pro-oxidant and antioxidant recoveries in this study were found to be between 87–96 and 83–93%, respectively.     

Energy requirements and production cost of the spray drying process of cheese whey

The influence of spray drying conditions on the energy required, production cost, and physicochemical characteristics of cheese whey was researched. The factors investigated were the inlet air temperature (180–220°C), outlet air temperature (80–100°C), and silica and maltodextrin (DE-10) as additives at 2 and 5% (w/w), respectively. Analysis of variance revealed that the inlet and outlet air temperatures, and the addition of additives had significant effects (p?T_inlet of 180°C, T_outlet of 80°C, and the addition of 5% additive material. Under these conditions, 0.2165?kg/h of dried product was obtained, with a moisture content of 2.08% and water activity of 0.125, and the product cost was $17.06?kg with an energy consumption of 2.0490?kW?·?h/kg of dry product.     

喷雾干燥法制备羧基丁苯-纳米氧化硅杂化复合粉末

羧基丁苯-纳米氧化硅杂化胶乳经喷雾干燥法,制备了粒径为2～8μm,含水质量分数小于1％,比表面积为2．9m^2／g的羧基丁苯-纳米氧化硅杂化复合粉末。喷雾干燥的最佳工艺条件为进口温度220℃。出口温度140℃,进料速度500mL／h,进料质量分数5％,雾化器转速26000r／min。