CONTROL CONFIGURATIONS FOR AN ENERGY INTEGRATED DISTILLATION COLUMN

Process integration provides a tool for exploiting significant energy savings in chemical plants. A large pare thereof is often realised in distillation columns. An ultimate degree of energy integration for dis tillation columns is integration of condenser and reboiler of the same column through a direct or indirect heat pump. In this paper the stud y of a single distillation column integrated with an indirect heat pum p reveals some general operational characteristics of energy integrate d distillation plants. It is illustrated how a base case design of ene rgy integration may render the integrated plant open loop unstable. Th e control loop necessary for stabilization influences the set of actua tors available for inventory and purity control. It is discussed how t he operating region can be covered using the actuators of an integrate d plant relative to using standard distillation column actuators. Opti mum energy efficiency of the energy integrated column is discussed thr ough comparison to the base case design. Emphasis is placed on design effects upon plant controllability and operability. Finally general de sign and operational aspects of energy integrated distillation are ext racted.