盘式连续干燥器中物料与加热盘间的传热

<正> 盘式连续干燥器是一种连续操作的搅拌物料传导干燥设备,它操作弹性大,性能良好,运转可靠,干燥效率高,目前已被许多国家广泛应用于工农业生产中。本文拟将E.U.Schlunder和N.Mollekopf针对间歇式搅拌物料传导干燥提出的“扩散理论”应用于盘式连续干燥器中物料的干燥过程,计算物料的干燥速率及料层温度,并以聚氯乙烯树脂为物料在盘式连续干燥器样机上进行干燥实验。     

盘式连续干燥器的耙叶设计探讨

在所有传导式干燥机中,盘式连续干燥器的有效加热面积最高,理论上可达100%,但如果耙叶设计与选择不当,将导致实际有效加热而积降低,有的共至低至50%以下,盘面上出现大最的裸露面积,严莆影响了盘式连续干燥器效能的正常发挥.通过理论分析和图形解析方法,给出了盘式十燥机耙叶设计的一些准则,可消除盘面的裸露面积,提高干燥机的综...     

盘式连续干燥器干燥速率及耙叶搅拌数

盘式连续干燥器干燥速率及耙叶搅拌数司孟华张继军河北经贸管理干部学院石家庄市０５００１１）（核工业部第四设计研究院石家庄市０５００２１）搅拌物料床层的传热与传质是非常复杂的，ＥＵＳｃｈｌｕｎｄｅｒ和ＮＭｏｌｅｋｏｐｆ对其进行了研究，并采用集总参数的方法...     

盘式连续干燥器在氢氧化钡生产中的应用

介绍了应用于氢氧化钡干燥的盘式连续干燥器。阐述了该干燥器的工作原理及工艺流程,分析了这种干燥形式的特点及应用领域,并与传统的气流管干燥机进行了比较。结果表明,用于氢氧化钡的干燥,盘式连续干燥器优于气流管干燥机。     

盘式连续干燥器在卤水法硫酸钡干燥中的应用

介绍了盘式连续干燥器的主要结构、工作原理及其在卤水法硫酸钡干燥中的应用。     

盘式干燥器设计和应用

盘式连续干燥器发展至今已有几十年的历史,最初它只用于硫铁矿的焙烧及煤粉的干燥,由于其设备投资较大及当时的一些技术问题,一直没有引起人们的重视。近几十年,由于节能、改善工作环境及一些难处理物料干燥的需要,许多国家又开始了盘式连续干燥器的开发和研究工作,进一步改进了其制造加工工艺,降低了成本,提高了干燥性能,将广泛应用于化工、染料、农药、塑料、医药、食品等领域,并取得很高的效益。     

滚筒干燥器内丝状物料的传热传质特性研究

干燥涉及众多生产领域,卷烟加工过程中存在干燥环节,滚筒烘丝机是用于干燥烟丝的主要设备。在滚筒烘丝机内,烟丝与周围环境进行热质交换,不同的运行控制条件,将直接影响烟丝的品质。由于干燥过程受众多因素的影响,至今烟草加工企业对烘丝机内部烟丝的传热传质特性缺乏深层次的认识,不利于烟丝品质的提高。针对上述背景,本文基于传热传质学、流体力学、多相流动等相关理论,通过计算机数值模拟方法,建立并求解滚筒内的传热传质数学模型,获得不同操作条件下烟丝温度、含水率变化的详细信息,并将所得结果与实际生产数据相验证。研究结果表明,烟丝与气流逆流流动条件下,干燥过程存在三个阶段：预热段、恒速段、降速段,烟丝含水率先升后降,烟丝温度经历先升高、后降低、再升高的过程;顺流流动条件下,干燥过程存在两个阶段：预热段与恒速段,烟丝含水率沿程单调下降,烟丝温度在预热段急剧上升,在恒速段平缓上升。     

反丁烯二酸生产中盘式连续干燥器的应用

本文介绍了应用于反丁烯二酸干燥的盘式连续干燥器．阐述了工作原理及工艺流程．分析了这种干燥形式的特点及应舟领域．并重点与气流式干燥器进行了比较。     

盘式连续干燥器与回转窑干燥机干燥镍精矿的比较

介绍了盘式连续干燥器与回转窑干燥机的工作原理和干燥效果,通过对盘式连续干燥器的实验数据和回转窑的实际生产数据的分析比较,证明盘式连续干燥器干燥镍精矿的优越性及节能环保效果。     

盘式连续干燥器中耙叶的设计

简单介绍了盘式连续干燥器中常见的几种耙叶形式,并根据物料在干燥器中的运动规律,对平面刮板形式耙叶的主要尺寸提出了设计方案。为了使耙叶在干燥器运行的过程中更好地输送及翻炒物料,又对耙叶的结构形式提出了几点改进意见。     

EFFECT OF BLOW BOXES ON EVAPORATION DURING CYLINDER CONTACT IN A PAPER MACHINE DRYER SECTION

ABSTRACT

In this paper an inexpensive configuration for a cylinder blow box (CBB) and its effect on the evaporation rate are described. The objective of this work was to determine the effect of the blow boxes on drying intensity on a paper machine. The pilot machine trials were simulated with a computer program. Based on these results two cases were simulated for a commercial paper machine with and without blow boxes on single cylinders. The results revealed that when using the blow boxes on single cylinders, the drying rate can be increased by up to 15%. The potential for using this kind of configuration is biggest at the beginning of a dryer section. A simple construction of blow boxes makes this technique useful especially in boosting the drying performance of older paper and board machines. The exhaust air from the boxes can be utilized in ventilation of dryer pockets.     

新型节能圆盘干燥器的开发与应用

干燥作业是耗能大户。热传导式多层圆盘干燥(冷却)器在节能方面具有显著优势。介绍了该干燥(冷却)器的设计、功能及其应用,并进行了经济性评价。     

淀粉在旋转气流干燥器中的热量传递

在旋转气流干燥器中,取一物料环作微元体,根据热平衡原理,建立了计算热介质与颗粒固体间的给热系数数学表达式。由气、固两相在旋转运动中的相对滑移关联式,进行了努塞尔准数Nu、空塔气速表征的雷诺数Re、气固质量比B的关联。在作者开发的φ150mm实验设备中,用淀粉进行传热的正交实验研究,得到了颗粒尺寸、颗粒湿含量、给热系数随干燥管高度的分布曲线。用非线性回归方法得到的关联式为: Nu=-0.937+0.133Re~(0.622)-0.042Re~(-1.285)B~(-0.790) 122≤Re≤189 0.0170≤B≤0.0863     

连续锦纶干燥塔的数学模型研究及数值仿真

针对某干燥塔的结构特点及运行过程中传热传质特性,建立了该干燥塔中干燥过程的传热传质微分模型,并用试验数据验证其合理性。运用经典龙格库塔法获得该模型的数值结果,分析了传热传质过程中干燥氮气温湿度和锦纶切片温湿度沿塔高的分布情况。通过仿真优化操作条件,提高了干燥塔的干燥能力。     

新型组合干燥器在镍精矿干燥中的应用

传统的回转窑等干燥设备在镍精矿的干燥上存在污染环境、能耗高及效率低等弊端,急切需要一种节能、环保、高效的干燥设备应用于镍精矿的干燥上。采用双桨叶干燥器和盘式连续干燥器组合干燥器对硫精矿进行干燥,通过25 d的半工业化试验,取得了成功,证明了此新型组合干燥设备在镍精矿干燥上的优越性,特别适合现在节能环保的要求,具有较大的社会推广意义。     

INVESTIGATION OF IMPINGEMENT HEAT TRANSFER COEFFICIENT AT HIGH TEMPERATURES

Very little information exists for the impingement heat transfer coefficient at high temperatures. All available empirical correlations are mainly based on experiments conducted at relatively low impingement temperatures, and thus cannot describe the heat transfer characteristics of the impingement air at high temperatures with sufficient accuracy. A comprehensive study of the impingement heat transfer coefficient at high temperatures is carried out and presented in this paper. The aim of the study is to give a summary of the experimental results of the impingement heat transfer covering a large impingement air temperature range from 100 to 700°C. Heat transfer measurements were carried out on a laboratory-scale test rig. The main parts of the rig were a fan, a gas burner for air heating, a heavily insulated nozzle array with 300 × 500 mm impingement surface, a 40 mm thick and 300 × 500 mm sized aluminium plate for determination of heat transfer, and a data acquisition system. The heat transfer rate was determined from the heat-up rate of the aluminium plate due to the high temperature jet impingement.     

盘式连续干燥器在苯胺黑生产中的应用

分析了苯胺黑生产中盘式连续干燥器的技术特性和应用情况,通过试验证实该干燥器具有热效率高,基本不污染环境等优点。     

INVESTIGATION OF IMPINGEMENT HEAT TRANSFER COEFFICIENT AT HIGH TEMPERATURES

ABSTRACT

Very little information exists for the impingement heat transfer coefficient at high temperatures. All available empirical correlations are mainly based on experiments conducted at relatively low impingement temperatures, and thus cannot describe the heat transfer characteristics of the impingement air at high temperatures with sufficient accuracy. A comprehensive study of the impingement heat transfer coefficient at high temperatures is carried out and presented in this paper. The aim of the study is to give a summary of the experimental results of the impingement heat transfer covering a large impingement air temperature range from 100 to 700°C. Heat transfer measurements were carried out on a laboratory-scale test rig. The main parts of the rig were a fan, a gas burner for air heating, a heavily insulated nozzle array with 300 × 500 mm impingement surface, a 40 mm thick and 300 × 500 mm sized aluminium plate for determination of heat transfer, and a data acquisition system. The heat transfer rate was determined from the heat-up rate of the aluminium plate due to the high temperature jet impingement.     

CONVECTTVE HEAT AND MASS TRANSFER AND EVOLUTION OF THE MOISTURE DISTRIBUTION IN COMBINED CONVECTION AND RADIO FREQUENCY DRYING

ABSTRACT

In a previous study (Dostie and Navarri, 1994), experiments indicated that a non-uniform moisture distribution could develop in radio frequency drying depending on the applied power and initial conditions, making the design and scale-up of such a dryer a more difficult task. Consequently, a thorough study of the combined convection and RF drying process was undertaken. Experimental results have shown that the values of the neat and mass transfer coefficients decrease with an increase in evaporation rate caused by RF energy. This effect is adequately taken into account by the boundary layer theory. Furthermore, the usual analogy between heat and mass transfer has been verified to apply in RF drying. Experiments have also shown that a different mass transfer resistance on both sides of the product should not result in non-uniform drying. However, it appears that non-uniform drying is dependent upon the initial moisture distribution and the relative intensity of heal transfer by convection and RF- It was shown that the maximum drying rate occurs at a higher average water content and that the total drying time increases with non-uniformity of the initial moisture distribution.