Retrofit by inspection using thermodynamic process visualisation

• Published in: Computers & chemical engineering 1998-01, Vol.22, p.S809-S812
• Main Authors: Lakshmanan, R., Bañares-Alcántara, R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Devices using thermal energy; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat Exchanger Networks; Heat exchangers (included heat transformers, condensers, cooling towers); Rational use of energy: conservation and recovery of energy; Redesign; Retrofit; Thermodynamic Visualisation
• ISSN: 0098-1354; 1873-4375
• DOI: 10.1016/S0098-1354(98)00154-9

Although grassroots Heat Exchanger Network (HEN) Synthesis has received much attention in the literature, relatively little research has focused on the retrofit problem, which comprises the vast majority of real industrial cases. Attempts at rigorous automation (Ciric and Floudas, 1989; Yee and Grossmann, 1991) have met with limited success primarily because of the excessive computational costs associated with this problem when formulated as a Mixed-integer Nonlinear Program (MINLP). Other approaches (Briones and Kokossis, 1995; Tjoe, 1986; and Asante, 1996) make simplifying assumptions which are only appropriate for restricted classes of problems. The research described here has focused on the development of a visualisation tool, the Retrofit Thermodynamic Diagram (RTD), and a set of guidelines for developing retrofit solutions by inspection. The method relies heavily on the ingenuity of the designer, but has proved to be very flexible — handling a wide variety of problem formulations. It has produced designs that are significantly superior to published solutions, ranging from 85% additional energy saving — for the same payback period — (Lakshmanan and Bañares-Alcántara, 1996) to a 70% reduction in capital cost (for the same level of energy saving).