Experimental Studies Of High Gravity Vacuum Distillation For Separating Ethanol-water

Ethanol is an important organic chemical raw material, widely used in food,pharmaceutical, chemical and aviation industries. In the actual production process,atmospheric distillation of ethanol cannot achieve the goal, so it is necessary to apply aspecial rectification means to be separated. The vacuum distillation method directly isolatedproduct without adding a third component like azeotropic distillation and extractivedistillation. In this paper, it is based on gravity technology to strengthen the ability to bind, soas to explore the process of vacuum distillation operation ethanol-water separation.This paper takes advantage of the single-stage RPB packed with corrugated meshpacking. It also establishes gravity batch distillation process in the condition of total refluxoperation. First, on the basis of the test to determine the steady state operation of the program,it makes inventigations of the effects of heating temperature(100~150℃)、the ethanolconcentration of feed（50~95wt%）、the operating pressure（101.325~11.325kPa） and gravityfactors（20.9024~130.6397） aimed at the effect of water separation efficiency of the systemfor ethanol-water. Using factor-horizontal experiment, the best condition in this process isxd=95wt%，Tw=100~110℃，β=64.0135~83.6094. When the operating pressure varies from11.325kPa to101.325kPa, the effect can be achieved very close to the azeotropic composition.By further reducing pressure and increasing feed concentration of ethanol in11.325kPa (nextto95wt%feed ethanol concentration), ethanol product was isolated. Combined with theexperimental results and the theoretical analysis, it can be proved that it is able to continue toimprove separation effect to get anhydrous alcohol products eventually by increased packingheight in RPB.Experimental data processing needs to use data at each pressure equilibrium, and thus takes advantage of NRTL Aspen Plus software selection method to calculate the ethanol-watersystem phase equilibrium data at different pressures. Selection Herington semi-empiricalformula for the calculation results are verified thermodynamic consistency. The results areauthentic. Use Binary Phase Diagram Analysis function of the system, the relationship of thesystem under different pressures and its relation to the relative volatility is obtained. Andexperiment corresponds to each set of devices and mass transfer parameters are figured out.Gravity vacuum distillation equipment can remain stable mass transfer advantage, thus HETPvaries from8.5mm to40.0mm.Finally, select the pressure P=11.325kPa when gravity vacuum distillation to93wt%~99wt%of raw material separation experiments, set the same operating parameters,and simulation is set up with the corresponding conventional packed column flow throughAspen processes. On separation gravity separation can be more outstanding than conventionalpacked column distillation.with maintaining a high mass transfer. Moreover, mass transferunit height of traditional packed column are reduced to1/4to1/7.The results can be found, the super gravity distillation separation of ethanol water hascertain applicability. This technology improves the operation safety, and has the obviousadvantages of process intensification effect and energy saving.