화학공학소재연구정보센터
HWAHAK KONGHAK, Vol.18, No.1, 39-49, February, 1980
새로운 정유탑 간이설계법
New Short-Cut Procedures for Distillation Column Design
초록
다성분계를 경질 Key 성분과 중질 Key 성분으로 형성된 의이성분계로 간과하고 계의 평균 비휘발도를 최상단과 최저단에서의 Key 성분의 가하 평균으로 가정하는 등의 단수화과정을 통하여 정밀도는 다소희생하고 보다 신속한 그리고 지루한 시행착오법의 반복 계산을 우회하는 새로운 정유탑설계법을 제시하였다. 유축액 및 탑저액의 조성, 최소 이론단수, 최소 환류비 설계법은 물론 하드웨어(Hardware)의 실제설계에 필요한 탑반경, 높이, 단간격, 열부하계산등에 최적한 계산식을 제시하였다. 특히 전이론 단수를 구할 수 있는 도해를 도출함으로서 복잡한 반복 계산을 피하여 손쉽게 전이론댐구를 계산 할 수 있게 하였다.
본 연구에서 적용한 가정 및 단순화의 타당성을 논증하기 위하여 Smith-Brinkly 간이설계법(SB), Fenske-Underwood-Erbar-Maddox 간이설계법(FUEM) 및 수차단계산법(SBSM)에 의한 실제설계예를 본 연구의 계산결과와 비교 검토하여 상기 방법중 정밀도가 가장 높은 SBSM과의 오차는 약 10 % 내외라는 것을 확인하였다.
Use of iterative stepwise methods has been a common practice in designing multicomponent distillation columns. Sometimes, it is difficult to justify iterative calculations from the point of view of cost-effectiveness, particularly when the input information does not have precision or accuracy, or when one simply does not have sufficient information for the system under study.
In this work a new method was proposed whereby quick and simple procedures give rise to values of 14 different parameters needed for the design of a column for a multicomponent distillation. Several simplifying assumptions are made in the course : the usual one of a quasi-binary in which the average relative volatility is represented by a geometric mean of relative volatilities of the light key referred to the heavy in the bottoms over the light key referred to the heavy in the distillate, Prater and Boyd's approximation for column efficiency, approximations for expedience that arise in the actual mechanical fabrications of columns according to the common industrial practice, and other simplifications in the heat exchanger calculations.
In order to validate the proposed method, comparisons are made with other popular methods such as Smith-Brinkly Short-Cut Method(SB), Fenske-Underwood-Erbar-Maddox Short-Cut Method(FUEM) and Step-by-Step Method(SBSM) by means of an actual design example. Departure from the results by the Step-by-Step method was about 10 %, the latter being the method yielding the highest accuracy as well as precision.
Also, in this work procedures are presented for calculations of several hardware parameters of a distillation column and of heat exchangers annexed to the column.