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。     

合成脲醛树脂的反应模型研究

研究了脲醛树脂合成反应在不同时间的甲醛与尿素物质的量比、pH值和温度对反应速率的影响,在加成反应阶段测定了甲醛含量,并在缩聚反应阶段测定了树脂的粘度。实验发现,甲醛与尿素在初始碱性阶段10 min内反应速率最快,随后呈逐渐降低的规律。通过正交实验,回归得到了脲醛树脂在缩聚反应阶段的反应时间与粘度变化的万程式,通过比较理论值(由方程式计算而得)与实验值(相同试验条件下测得)可知,当温度为60-80℃、pH值为4.0～5.5以及在反应时间间隔内进行拟合时,两者粘度的绝对误差在2 s以内。     

低甲醛脲醛树脂的合成

脲醛树脂是由尿素与甲醛在催化作用下经过加成和缩聚反应生成的低分子量树脂，它主要用于大批量木材的胶接生产，如制造胶合板、刨花板、纤维板等，还有缓释肥料等。脲醛树脂用在人造板业上是一个比较好的胶粘剂，还有与其他合成木材胶粘剂相比除了耐水性、耐久性差外，有很多优点，如原料易得，成本低廉，不产生污染且工艺简单等。     

实验室用压力式喷雾干燥器的研究

实验室用压力式喷雾干燥器是目前建筑陶瓷行业所急需的.笔者主要介绍了研究本课题的意义及创新之处,并阐述了本课题的研究内容及关键技术.     

黄原胶雾化性能及喷雾干燥的实验研究

通过对黄原胶发酵液雾化实验数据的整理,得出黄原胶雾化性能曲线及适宜的操作参数。在喷雾干燥黄原胶过程中获得较满意的效果,从而得出用喷干法生产黄原胶的可行性结论。     

阻燃脲醛树脂的研究

以磷酸改性脲醛树脂，制得水溶性的膨胀型防火涂料，具有良好的阻燃防火性能和较好的透明性。     

脲醛树脂耐水性的研究

为了提高短切玻纤毡用脲醛树脂粘合剂的耐水性,尤其是耐热水性,研究了尿/醛比、三聚氰胺、醇类的醚化、聚乙烯醇以及聚丙烯酸乳液对脲醛树脂耐水性的影响。其主要影响因素是交联密度和亲水性物质的含量,良好的交联密度和尽可能少的亲水性物质是脲醛树脂耐水性的保障。     

脲醛树脂的固化研究

通过缩聚法制备出脲醛树脂,考察了制备单组分固化剂NH4C l、2%HC l、5%的H3PO4、H2O2及双组分固化剂NH4C l和2%HC l、NH4C l和5%H3PO4的使用条件,并确定了复合固化剂的配比和用量。发现双组分固化剂固化时间适宜,固化效果好。     

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.

     

喷雾干燥系统的经济优化研究

对三环节　经济优化能量综合方法在喷雾干燥系统的应用进行了全面深入的研究,提出了适用于喷雾干燥系统的　经济调优法;改进了喷雾干燥器的ＰＡＲＴＩ模型,使之能够方便快捷地进行模拟计算;以干燥尾气为决策变量,在一定　经济边界条件Ｇ＿（ｕｉ）和Ｃ＿（ｕｊ）下,给出了喷雾干燥塔的　经济优化计算方法。工业实际用例数据表明,该法实用、思路清楚且运算速度快。     

Narrow tube spray drying

Spray drying conventionally necessitates relatively large or elongated drying chambers. The present study examined the possibility in shrinking the spray drying chamber into narrow tube-like geometry. The key was in utilizing fine droplets which had low transport response time. A narrow copper/steel tube spray dryer (internal diameters between 12.7 and 48.0 mm) was constructed and was fitted with a two-fluid atomizer producing droplets in the size range smaller than 10 µm. Maltodextrin, lactose, and sucrose were spray-dried. The narrow tube approach allowed direct manipulation of the drying conditions via heating or cooling along the wall of the tube. This form of manipulation in the drying conditions, surprisingly, resulted in very distinctly crystalline spray-dried sucrose particles. The tube spray dryer was further modified with a long coiled-up tube, extending the particle residence time with minimal space requirements. Endoscopic analysis revealed that particle deposition within the tube resembled loosely attached particle and granules. The tube spray drying concept can potentially be used to provide precise control of the particle drying history along the length of the drying chamber, not limited to the control of the drying conditions at the inlet or outlet of a spray dryer.     

Microencapsulation of hazelnut oil through spray drying

This study was performed to investigate the influence of air inlet temperature (AIT) on the microencapsulation of hazelnut oil by spray drying. Encapsulated powders were analyzed for moisture content, powder yield, surface oil, encapsulation efficiency (EE), bulk density, and particle morphology. The obtained results demonstrated that moisture content, surface oil, and bulk density decreased by 37.8, 27.5, and 33%, respectively as AIT increased from 140 to 220°C. However, powder yield and encapsulation efficiency increased considerably with the rise in AIT. Higher EEs of about 75–80% were observed in this study.     

喷雾干燥条件对PVC专用树脂质量的影响

阐述了喷雾干燥条件对PVC专用树脂的黏度、挥发物、筛余物指标的影响。生产实践表明喷雾干燥塔出口温度约为55℃（当树脂含水量超过0．6％时干燥塔出口温度为55-56℃）,气液比为7-9,能使树脂优级品率达到98．5％以上。     

喷雾干燥塔黏壁原因的分析及探讨

介绍了喷雾干燥塔在PVC树脂生产中产生黏壁的原因,并从喷雾干燥塔喷嘴的安装,操作风量以及温度等方面提出了改进方法,取得了良好的效果。     

喷雾干燥粘壁的原因与解决途径

对喷雾干燥粘壁的类型和原因进行了分析。喷雾干燥粘壁主要有半湿物料粘壁、低熔点物料的热熔性粘壁和干粉表面粘附三种类型。半湿物料粘壁主要与喷雾干燥塔结构、雾化器结构、安装、操作以及热风在塔内的运动状态有关。物料熔点低于干燥温度时容易产生热熔性粘壁。干粉表面粘附与塔壁的几何形状、粗糙程度、空气流速、静电力等有关。提出了解决各种类型粘壁的技术措施。     

低温喷雾干燥制备胰岛素缓释微球的试验研究

采用低沸点溶剂喷雾干燥法制备了胰岛素缓释微球，并从外观形态、粒径分布、包封率、体外释放、热学特性等方面考察了微球的性能。结果表明，胰岛素微球粒径分布较窄，具有较高的包封率，且该方法制备方便、生产效率高，易于实现工业化生产。     

New narrow tube spray dryer for precise drying history control

Of all the operating conditions in a spray dryer, temperature of the drying medium holds the key parameter in affecting the degree of crystallinity in spray-dried particles. Previous experiments only focus on controlling the drying temperature at the inlet or outlet of drying chamber to delineate the drying history of particles, precluding any detailed studies on particle development throughout the drying duration. Hence, the objective of this work is to address the current limitation by introducing a modified narrow tube spray dryer which enables in situ control of drying history. Essentially, the drying chamber consists of 10 narrow copper tubes with an internal diameter of 1.7?cm. Each individual copper tube can be heated independently to create a unique controlled drying history. Scanning electron microscopy images demonstrate the significant impact of drying history on lactose morphology with possible crystallization by even slight variations in the drying history, which further accentuates the sensitivity of degree of crystallization to temperature. With this newly developed equipment, the detailed drying history conditions can be designed and manipulated to engineer the desired particle properties.