확산증류공정을 이용하여 대기압에서 물과 공비점을 가지는 tert-butyl alcohol(TBA)과 isopropyl alcohol(IPA)를 공비 조성 이상의 농도로 탈수하였다. 확산증류는 두 개의 동심관으로 이루어진 젖은 벽탑과 비활성 기체층으로 구성된다. 탑으로 도입된 혼합물은 끓는점 이하에서 증발하고 증발한 기체들은 비활성 기체층을 서로 다른 속도로 확산해서 낮은 온도로 유지되는 면에 응축한다. 본 연구에서는 비활성 기체층으로 이산화탄소, 공기 그리고 헬륨을 사용하였고, 확산거리는 서로 다른 직경을 가진 내부관을 교체해 조절하였다. 이와 함께 증발부의 온도를 변화시키면서 물질전달과 분리에 미치는 영향을 관찰하였다. 분리의 효과는 증발부와 응축부의 조성 차이로 정의된 선택도와 응축부의 플럭스를 측정하여 나타냈다. TBA/water계와 IPA/water계에서 증발부의 온도는 비활성 기체의 종류와 확산거리에 관계없이 각각 35℃와 40℃에서 선택도가 최고였고, 증발부의 온도가 증가할수록 플럭스는 증가했다. 선택도는 이산화탄소를 비활성 기체로 사용한 경우가 가장 좋았고, 플럭스는 헬륨을 사용한 경우가 가장 많았다. 확산거리가 줄어들수록 선택도와 플럭스는 증가했다. 이론식들로부터 구한 값을 실험결과와 비교하였다.

Tert-butyl alcohol(TBA) and isopropyl alcohol(IPA) which showed an azeotrope with water at atmospheric pressure were dehydrated in a wetted-wall column by the diffusion distillation. The diffusion distillation process was made up of wetted-wall column which consists of two concentric tubes and an inert gas layer. The liquid mixture introduced at the top of column flowed down and evaporated below the boiling temperature and diffused through an inert gas layer with different diffusion rate and then condensed at the plate which kept at low temperature. Experiments were carried out at various evaporation side temperatures, and with various kinds of gases such as CO₂ air and helium. The diffusion length was varied by interchanging of inner tubes of different diameters. The degree of separation was presented by selectivity and flux of condensed side. The selectivity was defined as the difference in composition between the evaporation and the condensation side. TBA/water and IPA/water systems were found to show the maximum selectivity at 35℃ and 40℃, respectively. With increasing evaporation side temperature, the flux was increased. The highest selectivity was obtained with carbon dioxide as an inert gas and the highest flux with helium. The selectivity and the flux were increased with decreasing the diffusion length. The experimental data were compared with the theoretical results.

Wetted-Wall Column Azeotrope Dehydration TBA IPA

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