Search / Korean Journal of Chemical Engineering
HWAHAK KONGHAK,
Vol.36, No.3, 438-446, 1998
삼성분 혼합물 증류에서의 이성분계 단효율 값을 이용한 각 단 평균농도 예측
Prediction of Average Concentration of Each Plate using Binary Plate Efficiency Data in Ternary Mixture Distillation
n-Hexane/n-heptane/n-octane계와 methano1/2-propanol/water계에 대한 다성분계 증류의 농도분포를 각 단에서 총괄 기상 물질전달 단위수(number of overact vapor phase transfer units), [Nov]가 일정하다는 가정을 이용한 경우와 선형화 이론을 적용한 Maxwell-Stefantlr의 해를 이용하는 경우, Maxwell-Stefan식의 일반해를 이용하는 경우로 나누어 예측하였다. 실험은 직경 1 in., 10단 및 15단으로 이루어진 Oldershaw column을 이용하여 수행하였으며, 각 단의 농도를 측정하여 예측한 농도분포와 비교하였다. 총괄 기상 물질전달 단위수, [Nov]가 일정하다는 가정을 이용한 경우 각 계에 대한 실험값은 예측값과 많은 차이를 나타내었으나, Maxwell-Stefan식을 이용한 예측값은 실험값과 거의 일치하였다. 또, 세 가지 방법을 이용하여 원하는 조성을 얻고자 할 때 필요한 단수를 계산하였다. n-Hexane/n-heptane/n-octane계와 같은 이상적 혼합물의 경우 각 방법간의 별 차이가 나타나지 않았으나, methanol/2-propanol/water계와 같은 비이상적인 혼합물의 경우 각 방법간에 많은 차이를 나타내었다.
In the multicomponent distillation, the concentration profiles for the n-hexane/n-heptane/n-octane system and the methanol/2-propanol/water system are predicted by following three methods:
(1) assumption of constant number of overall vapor phase transfer units, [Nov]
(2) solution of Maxwell-Stefan equation based on linearized theory
(3) the general solution of Maxwell-Stefan equation
The experiments are performed in a 1 in. diameter Oldershaw column with 10 plates and 15 plates respectively, in order to compare the predicted concentration profiles with the measured concentration profiles. The predicted concentration profiles using the assumption of constant [Nov] are deviated from the measured concentration profiles for both systems. But the predicted concentration profiles using other two methods are in good agreement with the measured concentration profiles. And three methods are used to predict the required number of stages for a specified separation. In non-ideal system the predicted numbers of stages are different from each other. But in ideal system three methods predict almost same numbers of stages with each other.
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