Heat Integration by Multiple Hot Discharges/Feeds between Plants

• Published in: Industrial & engineering chemistry research Vol. 50; no. 18; pp. 10744 - 10754
• Main Authors: Zhang, B. J, Luo, X. L, Chen, Q. L, Hui, Chi-Wai
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 21.09.2011
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology; Financing; Industrial engineering; Investment; Joining; Mixed integer; Process Design and Control; Storage tanks; Streams; Utilities; Heat recovery
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie201367z

Some independent plants making up a chemical or petrochemical site are linked by process streams. Linking process streams are, in general, cooled in up-plants and reheated in down-plants to satisfy process requirements. These streams, even more, travel from up-plants to storage tanks and, then, to down-plants, which results in low energy-use efficiency. Up-plants with multiple hot discharges and down-plants with multiple hot feeds are proposed in this paper, and a T–Q graphic method is presented to target the temperature of multiple hot discharges/feeds between plants. The T–Q diagram is composed of a grand composite curve (GCC) and a composite curve that only involves process streams employed for hot discharge/feed. A mixed integer linear programming (MILP) model is formulated to minimize the total hot and cold utilities of up- and down-plants and to solve the temperature of hot discharge/feed and the heat transfer between plants. Some examples are utilized to demonstrate the performance of the presented method for multiple hot discharges/feeds between plants. Results show an obvious decrease in the total hot and cold utilities of up- and down-plants, along with less investment for equipment.