聚合釜黏壁原因分析及减缓措施

通过对聚合物、黏壁物的剖析以及生产工艺参数的分析发现,聚合釜黏壁的主要原因是频繁的人工清釜、产品结构调整、聚合温度波动和聚合釜内液固物质的相比过低.通过改变催化剂粒径和活性、严格管理清釜作业操作、减少频繁开停车次数、控制聚合釜内合适的液固物质相比等方式,保证生产运行稳定等手段,有效缓解了聚合釜黏壁,延长了聚合釜运行周期...     

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。     

喷雾干燥塔热风门失效原因分析及处理

针对喷雾干燥塔热风门失效影响干燥过程这一严重困扰生产的问题 ,从热风门的结构、衬里结构及材料、操作条件等方面分析了热风门失效的原因 ,并据此提出了处理和预防热风门失效的几项措施。措施实施后效果明显 ,热风门的使用寿命延长了 2～ 3倍。     

喷雾干燥塔操作工艺分析

对喷雾干燥塔的粘塔,跑粉等现象,通过理论分析,使问题得以解决。     

喷雾干燥塔模糊控制模型及仿真

本文在研究喷雾干燥塔的传统控制的基础上,提出利用模糊控制方法并建立了模糊控制模型,仿真结果表明利用模糊控制方法进行喷雾干燥塔的控制是可行的。     

喷雾干燥塔节能新措施

本文从燃料，机械，减水剂等方面，对陶瓷喷雾干燥的节能问题进行了阐述，通过采取不同的技术措施，可大幅度降低喷雾干燥塔的能源消耗。     

喷雾干燥器粘壁产生的原因

引言众所周知,喷雾干燥工艺及设备是陶瓷、保护渣、化工、高岭土等行业常用的泥浆干燥设备。不管是哪个行业都或多或少存在喷雾塔体粘壁问题。此问题看似小问题,其实对使用厂会造成诸多不便,同时也造成了能源的浪费,尤其是粘性较大的泥浆原料,此问题尤为突出。     

HDPE装置黏壁原因分析及处理措施

高密度聚乙烯环管淤浆工艺生产过程中会出现黏壁现象,反应器的黏壁是普遍存在的问题,这也是多种因素相互作用造成的。低聚物的生成、聚合温度高、静电、共聚单体等都有可能使反应器产生黏壁现象。通过合理控制共聚单体浓度,控制反应温度,保持反应器内壁光洁度,控制反应器内固含量等方法,可有效减少反应器黏壁概率,延长装置的运行周期。     

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.     

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。     

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。     

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.     

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.

     

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.     

新型无填料喷雾冷却塔

介绍了循环水冷却原理,提出适于我国西北地区的新型无填料喷雾冷却塔提高循环水利用率的优势及改造方案。     

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。     

脲醛树脂喷雾干燥实验研究

研究了脲醛树脂乳液喷雾干燥过程工艺条件,探讨了热风温度,压缩空气压力,蠕动泵转速等因素对喷雾干燥过程的影响。从而得到粉末脲醛树脂产品,质量达国内引进装置生产的粉状脲醛树脂的质量指标,应用结果优于GB/T 14732-1993的各项指标。