FlowMac was used to make detailed mass balances for fiber, water, filler and energy. The model were tuned to have the same production rate, temperature profile and consistency profile as the real process. This paper machine have a pump, piping and control strategy for heating PM white water in the TMP heat recovery system. Several studies have shown that this heat stay in the white water tower. Actual temperature measurements show that the temperature in the white water tower can be 5°C hotter than the white water fed to the main pumps out of the tower.
With the model, we simulated alternative ways to create more circulation of the white water in the white water storage tower. The simulations showed that all heat that could be fed to the main white water pumps would reduce the amount of fresh steam to the white water silo. The FlowMac simulations showed that a 350 mm pipe had to be diverted and extended 20m in order to get an annual cost savings of 300 000 EUR.