The Design of Flights in Cascading Rotary Dryers

ABSTRACT

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure     

The Design of Flights in Cascading Rotary Dryers

ABSTRACT

In designing cascading rotary dryers, it is important to sire the flights correctly in order to ensure....     

The Design of Flights in Cascading Rotary Dryers

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure.     

THE DESIGN OF FLIGHTS IN CASCADING ROTARY DRYERS

ABSTRACT

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure.…     

THE DESIGN OF FLIGHTS IN CASCADING ROTARY DRYERS

ABSTRACT

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure.…     

THE DESIGN OF FLIGHTS IN CASCADING ROTARY DRYERS

ABSTRACT

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure....     

A Funtadamental Study on Particle Transport Through Rotary Dryers for Flight Design and System Optimisation

A model for particle transport in a flighted horizontal rotary dryer is developed in this paper. Mathematical principles applied to the current study are in the areas of differential calculus and analytical geomentry. In contrast to the conventional approaches which are either based on mpirical/semi-empirical correlations or obtained from the investieation of single particle trajectories, this paper develops rigorous mathematical analysis of the transport of bulk solids. A variety of important issues in rotary drying, such as axial flowrate of solids, retention time distribution and solid holdup are addressed and treated by using non-traditional methods. Since the model takes dimension, number and geometry of flights into account, it possesses the following two haracteristics : (1) it is not only useful in the study of rotary drying dynamics, but lso applicable to other processes employing flighted rotating cylinders (such as granulation drumsand crushers) and (2) based on the model, an optimal drum configuration can be designed by using optimisation techniques. The model can be incorporated within a distributed arameter dryer model developed previously to form a more rigorous integrated dynamic model. A heoretical foundation for optimal flight design by using the current model is explained.

A pilot scale perspex rotary dryer equipped with a video camera has been constructed and used for model validation. Raw sugar was handled in the experiments. Particle transport was observed and measured by using a flow visualisation technique supplemented with traditional sampling methods. A significant model quality improvement has been observed through a comparative study between the newly developed model and conventional ones.     

A Funtadamental Study on Particle Transport Through Rotary Dryers for Flight Design and System Optimisation

ABSTRACT

A model for particle transport in a flighted horizontal rotary dryer is developed in this paper. Mathematical principles applied to the current study are in the areas of differential calculus and analytical geomentry. In contrast to the conventional approaches which are either based on mpirical/semi-empirical correlations or obtained from the investieation of single particle trajectories, this paper develops rigorous mathematical analysis of the transport of bulk solids. A variety of important issues in rotary drying, such as axial flowrate of solids, retention time distribution and solid holdup are addressed and treated by using non-traditional methods. Since the model takes dimension, number and geometry of flights into account, it possesses the following two haracteristics : (1) it is not only useful in the study of rotary drying dynamics, but lso applicable to other processes employing flighted rotating cylinders (such as granulation drumsand crushers) and (2) based on the model, an optimal drum configuration can be designed by using optimisation techniques. The model can be incorporated within a distributed arameter dryer model developed previously to form a more rigorous integrated dynamic model. A heoretical foundation for optimal flight design by using the current model is explained.

A pilot scale perspex rotary dryer equipped with a video camera has been constructed and used for model validation. Raw sugar was handled in the experiments. Particle transport was observed and measured by using a flow visualisation technique supplemented with traditional sampling methods. A significant model quality improvement has been observed through a comparative study between the newly developed model and conventional ones.     

Effect of Lifter Design on Drying Performance in Rotary Dryers

Lifter use in dryers improves mass transfer by increasing the amount of surface area available for transfer and also by increasing the velocity of gas over the particle surface. An even cross-sectional distribution of particles in a dryer improves the efficiency of operation by ensuring that evaporation from falling particles is taking place for the maximum fraction of the rotation period of the drier. Studies on lifter design to improve the cross-sectional particle distribution were performed on angled lifters. A single lifter was used and the mass-transfer rate examined as a function of angular lifter displacement. Analysis of the mass transfer characteristics of single lifters allowed performance comparisons and recommendations for lifter design.     

复合肥干燥机组合式抄板的设计及应用

针对复合肥传统干燥机抄板存在的问题,设计了由40°螺旋角抄板、180°抄板、100°抄板和135°抄板组成的组合式抄板,并将其应用于复合肥工业生产中,取得了较好的效果。     

Dynamic Characteristics of Solids Transportation in Rotary Dryers

Abstract

An original method was proposed for the determination of the mean residence time in a continuous dryer, based on the step-change in the solids feed rate. The method has been validated through experiments performed in a pilot-scale rotary dryer. The effect of the solids flow rate, gas flow rate, dryer rotation speed, and dryer slope was quantified. Several design correlations to predict the residence time in rotary dryers were critically evaluated, and a new, more accurate correlation was derived.     

Dynamic Characteristics of Solids Transportation in Rotary Dryers

An original method was proposed for the determination of the mean residence time in a continuous dryer, based on the step-change in the solids feed rate. The method has been validated through experiments performed in a pilot-scale rotary dryer. The effect of the solids flow rate, gas flow rate, dryer rotation speed, and dryer slope was quantified. Several design correlations to predict the residence time in rotary dryers were critically evaluated, and a new, more accurate correlation was derived.     

Evaluation of Simple Control Strategies for Rotary Dryers

Abstract

Rotary dryers are very versatile process equipment as it can accommodate a large variety of products over a wide range of flow rates. To obtain a uniform product quality and to operate the dryer economically with minimal environmental impact, it is necessary to use efficient control strategies. In this article, two simple control strategies are proposed to improve the feedback-only controller that is normally used. One strategy is a partial feedforward control loop addition to the feedback loop and the second is a moisture predictor that allows taking control actions on the estimates of the discharge moisture content rather than waiting to measure its value at the discharge. The performance of these two strategies was compared with the performance of a feedback-only controller and an ideal feedback-feedforward controller. It is shown that the two proposed control strategies significantly improve the performance of a feedback-only control strategy without having to install new sensors.     

干燥机十字抄板组的改造

分析干燥机十字抄板组的损坏原因,并通过计算确定技术改造方案,使十字抄板组的损坏问题得到解决。     

Evaluation of Simple Control Strategies for Rotary Dryers

Rotary dryers are very versatile process equipment as it can accommodate a large variety of products over a wide range of flow rates. To obtain a uniform product quality and to operate the dryer economically with minimal environmental impact, it is necessary to use efficient control strategies. In this article, two simple control strategies are proposed to improve the feedback-only controller that is normally used. One strategy is a partial feedforward control loop addition to the feedback loop and the second is a moisture predictor that allows taking control actions on the estimates of the discharge moisture content rather than waiting to measure its value at the discharge. The performance of these two strategies was compared with the performance of a feedback-only controller and an ideal feedback-feedforward controller. It is shown that the two proposed control strategies significantly improve the performance of a feedback-only control strategy without having to install new sensors.     

硝酸磷肥回转滚筒干燥机抄板改造

介绍硝酸磷肥干燥机抄板的改造情况。拆除若干组损坏频繁的十字抄板,代之以升举抄板,改造后设备故障率降低,连续运行时间延长,企业效益提高。     

Modeling of Fertilizer Drying in Roto-Aerated and Conventional Rotary Dryers

Conventional rotary dryers are equipped with flights placed parallel along the length of the shell to promote a rain of solids across the dryer section. In the roto-aerated dryer the hot air flows through the particles that run on the bottom of the drum through a series of mini-pipes and there is no cascading. This study analyzed heat and mass transfer modeling between the air and the fertilizer particles in conventional rotary and roto-aerated dryers, as well as the simulation results with the experimental data. A good agreement between the simulated and experimental results was obtained for the two rotary dryer configurations analyzed.     

转筒干燥器中物料运动模型的研究现状

综述了近年来国内外关于转筒干燥器物料运动模型的研究现状,分析了各种模型的特点及适用性,并对其今后的发展方向进行了展望。     

THE DESIGN OF FLIGHTS IN CASCADING ROTARY DRYERS

ABSTRACT

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure....     

小型移动式粮食干燥机的设计

阐述了以秸秆为燃料的小型移动式粮食干燥机的主要结构组成和工作原理,并对干燥塔和热风炉等主要部件进行了设计计算,确定了合理的结构参数与工作参数。样机性能试验表明,该干燥机能满足粮食干燥要求,而且操作方便、移动性好,适合农户使用。