Improving energy recovery in milk powder production through soft data optimisation

Milk powder production is highly energy intensive and can benefit from the application of Pinch analysis techniques to develop better methods for integrating the process. In this study, process stream data is extracted from an industrial plant and Pinch analysis applied to calculate utility and heat recovery targets. Some of process data is also varied, within small ranges that do not harm product quality or violate environmental regulation, to minimise utility use targets. Using the Pinch design method and the targets as a guide, Maximum Energy Recovery (MER) networks are developed for two cases, where the condenser in the evaporator section of the plant may be directly or indirectly integrating into the reminder of the process. The two MER networks are compared to two heat exchanger network structures commonly found in industry. Results show that there is potential to increase specific heat recovery by over 30%, while reducing total cost by almost 10%, in the best case. To achieve maximum energy recovery, spray dryer exhaust air heat recovery is necessary and should be matched to preheat the dryer inlet air stream.