Targeting industrial heat pump integration in multi- period problems

Process integration aims at optimizing industrial processes by identifying the heat recovery potential and the optimal integration of energy conversion systems. Most industrial processes especially in the food industry are non-continuous problems (batch problems) that are more difficult to tackle with process integration techniques. Process integration of multi-period problems can become complex and often the heat integration is realized by using time averaging approaches. The main disadvantages are that the sizing of equipments becomes more difficult and that the investment cost calculation is almost impossible at the targeting stage, since storage tanks are not included. This work presents a MILP method that targets simultaneously the heat recovery and the integration of energy conversion systems like heat pumps and other utilities in multi-period multi-time problems. In each time slice, the heat cascade constraints are considered together with the flows of the utility streams and the mass balances for storage, which create a link between the different operating times.