Influences of structural and operating parameters

In the investigation, the volumetric evaporation intensity, Ev, is used as the major comparative criterion, which is defined as 

A set of data on the variation of moisture content of the product with the feed rate under typical operating conditions is given in Fig. 6.21. In critical cases the moisture content may be above the value specified and in more serious cases the material in the annular chamber may completely loss its ability to flow, the system is blocked out, and finally the operation is destroyed. 

In the equipment shown in Fig. 6.14 two possible options for the product discharge were considered. It is reasonable that researchers would want to employ the scheme of overflow through the upper outlet. If such a scheme was feasible, the control of the material level in the annular chamber, which has an important effect on the stable operation of the device, would become very easy and convenient. 

Unfortunately, the experiments yield negative results with the upper discharging port, the out-particles are obviously finer in size, the out rate is unstable, and the moisture content of the out material is higher and higher as the process proceeds. Even without analysis, it can be judged that the moisture content of the product does not meet that required. 

According to Elperin et al. [6], after impingement between the opposing streams, the radial velocity of the gas flow decays following the relationship below  

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For a fundamental understanding of the hybrid process it is necessary to describe the interactions between two different unit operations with appropriate models. Making basic parameter studies the equilibrium stage model for distillation and a short-cut model for membrane separation is sufficient. The models are well established and the model parameters are quite accessible. This combination gives an first survey on the influence of structural and operational parameters on the concentration profiles in the column and on the maximum amount of water, which can be removed. 

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