You start with milk at 4C, heat it to ~70C via heat exchanger (+66C), then 75c via heating (+5C), wait 15 seconds for pasteurization, cool down to ~9C via heat exchanger (-66C), then just chill to 4C via refrigeration (-5C).
This requires ~1/14th the energy to heat the milk and also rapidly cools it down below ambient temperature afterwards saving even more energy.
You see similar approaches for a lot of large scale chemical processes.
I had never heard of this, the use of already existing heat is amazing! Do they run 24/7? If not, they must use a lot of energy to cold start the process.
One classic example I always hear about efficient use of heat exchanger is the building of.swimming pool in the same building as ice rink. The heat produce cooling one is used to warm the other.
You start with milk at 4C, heat it to ~70C via heat exchanger (+66C), then 75c via heating (+5C), wait 15 seconds for pasteurization, cool down to ~9C via heat exchanger (-66C), then just chill to 4C via refrigeration (-5C).
This requires ~1/14th the energy to heat the milk and also rapidly cools it down below ambient temperature afterwards saving even more energy.
You see similar approaches for a lot of large scale chemical processes.