Abstract:

Heat of hot process streams is recovered to preheat cold streams, and some steam is generated simultaneously below pinch points to increase the efficiency of energy recovery.Hot feed/discharge between plants cannot only reduce the total utilities of up-plant and down-plant, but also increase steam generation by changing the pinch location and shape of grand composite curve (GCC).Composite curve of streams employed for hot feed/discharge and GCC are figured in a T-Q diagram, where the temperature of hot discharge is targeted by reversing and moving the composite curve of streams in horizontal direction, and the pressure and flowrate of steam generation are optimized by considering the energy requirement of steam in different pressure grade.An industrial example involving a vacuum residue hydrotreating plant (VRHP）and a fluid catalytic cracking plant (FCCP）is investigated to demonstrate the performance of presented model.The solution results indicate a decrease in the total utilities and an increase in the steam generation.