Impinging stream dryer

Assimilating positive and negative the experiences obtained in the past, the author of this book has developed the Circulative Impinging Stream Dryer , an IS device suitable for powdery and/or granular materials [11, 82]. A test with quasi-industrial equipment on a scale of 1000 tones per year has exhibited good performance, and practical application may be expected in the near future. 

Left Figure 6.3 Vertical impinging stream dryer 191]. 

Right Figure 6.4 Vertical impinging stream dryer with an impingement cave. 

Figure 6.5 Tangential-horizontal two impinging streams dryer [58].

Figure 6.6 A brief view of tangential four-impinging stream dryer [94],...

Bar and Tamir [63] studied the two-impinging stream dryer with two pairs of airfeeding tubes, as briefly shown in Fig. 6.7. The purpose of adding the lower two air streams is to increase the hold-up and the mean residence time of the particles in the dryer, and also aims to enhance the turbulence between phases in order to increase the drying intensity. However, the experiments did not show that the secondary air streams increased either the hold-up or the transfer coefficient. On the other hand, the induction of the two secondary air streams results in the greatly increased hydraulic resistance of the system. The pressure drop across the dryer, with two pairs of air-feeding tubes and with a volume treble that of the dryer shown in Fig. 6.6, is as high as 3800 Pa. 

Figure 6.7 A brief view of the tangential impinging stream dryer with two pair gas-feeding [63].

Figure 6.8 Flash-impinging-stream dryer for pharmaceuticals [961.

Figure 6.12 Semi-batch impinging stream dryer [102.].

On the basis of a thorough understanding of the properties of gas-continuous impinging streams, including its advantages and disadvantages, the circulative impinging stream dryer (CISD) was developed and patented by the author of the present book [11, 103]. Primary tests on a quasi industrial scale have yielded satisfactory results, and it can be expected to be applied industrially in the near future. 

In view of the fact that most materials needing to be dried are powdery or granular solids, the development of the circulative impinging stream dryer is aimed at this kind of material. 

The structure of the circulative impinging stream dryer developed is sketched in Fig. 6.13, in which the flow configuration of vertical two impinging streams is employed. The equipment consists of three basic parts mounted co-axially the body, the upper and the lower accelerating tubes. The body is of a conical/cylindrical shape with different diameters. The lower-middle part of the body is a cylinder with a relatively... 

Figure 6.13 A brief view of the circulative impinging stream dryer (CISD).

Huang, Kai, Liu, Huayan and Wu, Yuan (2001). An investigation on drying in the circulative impinging stream dryer. J. Chem. Eng. of Chinese Universities. 15(3) 78-80 (in Chinese). 

Wu, Yuan, Wuhan Institute of Chemical Technology (2000). The circulative impinging stream dryer. Chinese paten, ZL00230326.4. 

Kudra, T. and Mujumdar. A. S. (1989). Impinging stream dryers. Dying Technology, 7 219-266. 

Although no details are available, an impinging stream dryer for sludges using super-heated steam as the drying medium has been operated at pilot scale successfully in Russia. Mujumdar has presented additional information on these special types of dryers [1] (see chapter on impinging stream drying in this handbook). 

Hosseinalipour, S.M. and Mujumdar, A.S. 1996. A model for superheated steam drying of particles in an impinging stream dryer. In Mathematical Modeling and Numerical Techniques in Drying Technology (I.W. Turner and A.S. Mujumdar, Eds.), Marcel Dekker, New York. 

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