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재순환이 포함된 화학공정의 정상상태 이득의 계산
Calculation of Steady state Gains for Chemical Process with Recycle
HWAHAK KONGHAK, August 1991, 29(4), 481-486(6), NONE
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Abstract
재순환이 포함된 공정(대부분의 화학공정)에서의 변수들 간의 정상상태 이득은 재순환의 영향으로 unit 자체만을 고려하여 구한 이득과 차이를 보이고 있다. 이로 인해 unit 자체에서 구한 이득을 바탕으로 편별기준을 적용하게 되면 loop pairing 및 변수들의 상호작용 해석을 잘못하게 되는 오류를 범하게 되어 합리적 제어구조 선정에 문제를 발생시킨다. 따라서 본 연구에서는 이를 해결하기 위해 unit 자체에서 구한 정상상태 이득과 재순환을 고려한 공정의 정상상태 이득 사이의 차이점을 규명하고 두 이득 사이의 관계를 연결시켜 주는 방법을 구하였다. 다루고자 하는 재순환 공정은 크게 관심있는 unit에만 독립변수(입력변수)가 있는 경우와 독립변수들이 다른 공정에서도 같이 존재하는 경우로 나눌 수 있으며 각각에 대해 정상상태 이득을 올바르게 구하는 방법을 제시하였다. 그리고 예제를 통하여 제시한 방법의 검증과 응용성을 알아 보았다.
The steady state gains of variables of the process which has recycle streams(most of all chemical processes)are different from those of each individual process. If the gains of individual process are applied to the criterion for the steady state gains, it is wrong to pair the control loops and analyze the interaction of variables of process with recycle. In the end the resonable selection of control structure is mistaken. The proper calculation method of steady state gains of process which has recycle streams was proposed through the efficient sensitivity analysis of process flowsheet variables. The treated recycle processes were divided into two cases. In the first case, independent variables(input variables)only exist in the interesting unit and in the second case, independent variables exit several units at the same time. The method was suggested to calculate correctly the steady state gains for the each case. The suggested method was applied to example to illustrate its usefulness.
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