내부순환시스템에서의 목록데이터 처리

일반적으로 석유화학산업에서는 단위공정간에 상호 upstream이 되는 내부순환공정이 흔히 발견되며, 이로 인해 단위공 정당 투입물 및 산출물량을 정량화하는 것에 어려움이 발생되게 된다. 현재 이러한 문제의 해결방안으로는 cut-off criteria 또는 외부 D/B와의 upstream의 연결, 시스템 경계의 확장을 통한 순환시스템의 선형화 방법이 있을 것이다. 하지만, 이상의 방법들도 선형구조의 공정에 적용하기 쉬운 방법으로 현재까지 내부순환공정에 적용하기 위한 기준은 제안되지 않았다. 그러 므로, 본 연구에서는 (1) 연립방정식을 통해 단위공정의 투입물 및 산출물량을 정량화하는 방법, (2) 이중 cut-off를 통한 정량화법, (3) 반복점에서의 cut-off를 통한 정량화법을 통한 제안을 제시하고자 한다. 이상의 3가지 제안을 통해 연구결과의 일관성을 제공하였으며, 특히, 연립방정식을 통한 단위공정의 정량화는 에러를 감소시킬 수 있도록 하였다.

In petrochemical industry, generally inner recurring processes are found. There is a problem to identify and quantify of inputs/outputs for each unit process. Current available methods to solve this problem are to linearize process flows by using cut-off criteria, to uplink offside D/B and to expand system boundary. But, the above methods of cut-off criteria and system boundary proposed ISO or SETAC is appropriate to the linear structure. And, until now, there is no criteria proposed on establishing system boundary per unit process in the inner-circulation system. Then, for this study, we present objective and consistent criteria that are applicable to the inner-circulation system of real process. These are (1) to determinate quantity of input/output by simultaneous equations, (2) to determinate quantity of input/output by double cut-off, and, (3) to operate cut-off criteria at repeating point.

First suggested method is to determinate quantity of input/output by simultaneous equations. It regards an unit process as a factor. Raw materials or materials from offsite D/B is regarded as an constant number. Input flow is regarded as positive(+) and output flow is regarded as negative(-). Second method is to determinate quantity of input/output by double cut-off. It is that cut-off at upstream point which is repeated uplink properly base on the cut-off criteria. Third method is to operate cut-off criteria at repeating point. Considering repeat processes uniformly, cut-off is accomplished at proper repeating point. Then, data collection process is achieved in this boundary. The result is that the three methods proposed is contributed to making reliability on a project results based on the consistency and site-specific data. Especially, inventory quantification on the unit process using simultaneous equations will be able to decrease the error.