Optimized heat exchanger network design for a phthalic anhydride plant using pinch technology: A Maximum Energy Recovery approach with economic analysis

Abstract

Effective energy management and optimization are pivotal in addressing energy-related challenges and mitigating environmental pollution. In industrial contexts, pinch technology provides practical and advantageous methods for establishing targets and efficiently harnessing excess energy within a facility. This case study focuses on a phthalic anhydride unit, a critical intermediate in the plastics industry, where the chemical reaction within the reactor is notably exothermic. To enhance energy recovery while minimizing the number of units, we designed an optimized heat exchanger network employing pinch technology. Instead of dissipating excess heat through cooling water, we redirected it to generate steam in a heat recovery steam generator. Our analysis defined four distinct scenarios, allowing for a comparative assessment among them. This strategic approach enables the plant to avoid annual cooling costs estimated at approximately €54,621 when operating for 7,000 h per year. Additionally, upon evaluating the scenarios, we determined that Scenario B exhibits the shortest payback period of 9 months for new heat exchangers, with a capital investment of €355,700. Overall, the plant stands to achieve a significant annual profit of approximately €477,295.

Keywords

• Pinch Technology
• Phthalic anhydride unit
• Energy recovery
• Payback period
• Capital cost