HWAHAK KONGHAK, Vol.31, No.2, 144-153, April, 1993
난류촉진물을 이용한 한외여과의 투과효율 향상
Permeate Flux Improvement Using Turbulence Promoter in Ultrafiltration
초록
한외여과에서 난류발생에 의해 농도분극을 감소시켜 막투과 flux를 증가시키고 분리효율을 높이기 위하여 난류촉진물로서 현재 나권형 모듈에서 쓰이는 유로 형성체(feed spacer)를 평판형 한외여과 cell에 적용하였다. 난류촉진물을 사용하여 dextran 500,000용액의 한외여과 실험결과 막투과 flux는 막의 종류와 압력차, 순환유속, 도입용액 농도 등의 조작조건에 따라 13.8-114.4%의 증가율을 보였다. 한편 농도분극층 내에서의 용질의 물성변화를 고려하여 기존의 Sherwood수 상관관계식을 보정하고, 그 타당성을 검토하였는데, 보정된 Sherwood수 상관관계식은 기존의 관계식에 비하여 향상된 결과를 보였으며, 그 관계식은 아래와 같다.
NSh=0.306(NRe)0.285(NSc)0.330(NScm)0.113
A channel spacer of spiral-wound membrane module was applied to a flat plate ultrafiltration cell as a turbulence promoter in order to reduce concentration polarization in ultrafiltration of dextran(M.W. 500,000) solution. As a result of using turbulence promoter the permeate flux was improved by 13.8-114.4% depending on membranes and operational conditions. Mass transfer correlation was modified by considering variation of physical properties(viscosity, density and diffusivity) in concentration polarization layer. The modi-fied mass transfer correlation showed better agreement with experimental results than the conventional one. The modified mass transfer correlation is as follow:
NSh=0.306(NRe)0.285(NSC)0.330(NSCm)0.113
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