Study On Flow Behavior Of The Two Phases In The Modified Scheibel Extraction Column

Scheibel extraction column is a mechanically agitated extraction column which consists of an alternate series of mixing sections and packed sections. It is widely used in industry due to its high extraction efficiency. However, the extraction efficiency is influenced by strong backmixing which leads to poor performance of the Scheibel extraction column. In the modified Scheibel extraction column, backmixing is reduced by setting sleve plates at each end of the packed section, and the modified extraction column has advantages in extraction efficiency.The hydrodynamics behaviors of two phases such as the hold up of dispersed phase, the mean drop size of dispersed phase and the residence time distribution of the two phase are of key importance to dealing with the flooding, specific area and flow pattern of the two phases, which are also the foundation for mass transfer research. So studying on hydrodynamics behaviors is significant.The influence of rotor speed, flow rate of dispersed phase and continuous phase and physical properties of two phases on the mean drop size of dispersed phase was studied in this dissertation. The result showed that rotor speed, flow rate of dispersed phase and physical properties of two phase affect the mean drop size in different degrees. The flow rate of continuous phase shows little influence on the mean drop size. In different range of Renold number, the factors show different influence. A series of correlations was proposed to predict the mean drop size of dispersed phase in different Renold number ranges. The maximal relative error between calculated and observed values16.9%, and the mean relative error is±4.9%.The residence time distribution (RTD) of continuous phase was determined with no mass transfer. The influence of rotor speed, flow rate of dispersed phase and flow rate of continuous phase was discussed in this dissertation. According to the RTD curve, there existed non-ideal flow like short flow and stagnant zone where the flow rate is slow in the continuous phase. It is necessary to adjust some structures of the modified Scheibei extraction column to improve the situation. From the RTD curve, a simple method to predict the holdup of dispersed phase was proposed. Holdup under different rotor speed, dispersed phase flow rates and continuous phase flow rate was obtained by this method.