Integration of Heat and Water Networks in Scheduling of Chemical Plants
Sudha Chauhan (Prof. Munawar A. Shaik) 13th September 2017, Wednesday, 04:30‐05:00 pm (25+5 mins), ChE Seminar hall
In the present scenario, batch plants are being used widely in chemical industry due to their flexibility which allows the production of different products by sharing the same equipment or vessel. Since equipments are shared by different tasks, water is used for equipment cleaning and energy is used for heating/cooling. The cost of effluent treatment and energy is increasing day by day. Hence, it is highly required to handle both the utilities efficiently, so that we can make optimal utilization of them without violating the environmental regulations.
This work addresses the integration of water networks and scheduling as well as heat networks and scheduling. The industrial water management has been accomplished by considering water reuse based on sequential and simultaneous approaches while heat integration has been done by aligning the heat producing and heat consuming tasks and simultaneously generating a production schedule.The presented scheduling model is based on state-task-network process representation, and unit-specific event based continuous time formulation. In sequential technique, discrete time model has been used to minimize the freshwater. On the other hand, in simultaneous technique no post-processing-unit-wait policy has been considered for washing units. The concept of Water Management Hierarchy (WMH) has been applied in a given fixed schedule for designing an optimum water network by exploring the possibilities for water minimization.
It has been demonstrated from the presented work that for freshwater minimization simultaneous approach is better than sequential approach, since it optimizes production schedule and water consumption simultaneously. In addition, WMH offers a comprehensive approach to reduce the wastewater by implementing the several wastewater minimization options. Flexible heat integration also offers considerable savings in the utilities.