Safety Analysis Embedded in Total Site Synthesis

• Main Authors: A. Nemet, K. Lee, J.J. Klemeš, P.S. Varbanov, I. Moon, Z. Kravanja
• Format: Article
• Language: English
• Published: AIDIC Servizi S.r.l. 2015-09-01
• Series: Chemical Engineering Transactions
• Online Access: https://www.cetjournal.it/index.php/cet/article/view/4428

Decreasing utility consumptions by Total Site (TS) process-to-process Heat Integration can be performed via several possible configurations, namely: i) Indirect, via intermediate utility and ii) Direct, by transporting either hot or cold process streams from one process to a heat exchanger placed within another process, undertaking heat exchange and afterwards returning them to the original process. The indirect heat transfer requires more complex network compared to direct, whilst the direct configuration can have safety issues. This contribution presents a five-step approach for TS heat exchanger network (HEN) synthesis. During the first steps the risk assessment is determined for each possible heat transfer match between processes. The matches can be classified by applying a risk-ranking matrix to matches with high, medium and low-level risks. In the fifth step synthesis of the Total Site Heat Integration Network is performed by a mixed-integer nonlinear programming (MINLP) model by considering the classifications of the matches obtained during the first step. The matches can be assigned as forbidden (high risk), allowed with penalty (medium risk) and allowed (low-level risk). The objective of the MINLP model is to maximise the Expected Net Present Value of the Total Site. This methodology was tested on an illustrative case study for analysing the impact of risk assessment. The obtained TS heat exchanger networks (HENs) by applying the described methodology were inherently safer and yet economically viable.