High temperature oil in a heating jacket on a jacketed kettle (for example) does not necessarily mean a quicker product heat up time compared to a lower temperature steam jacket.
In the food industry there exists also the risk of oil contamination into the food product via a leaky connection or worse, a fractured or leaking jacket wall.
The most commonly used type of steam jacket consists simply of an outer cylinder surrounding the vessel. Steam circulates in the outer jacket, and condenses on the wall of the vessel. Jacketed vessels may also be lagged, or may contain an internal air space surrounding the jacket. This is to ensure that as little steam as possible condenses on the outer jacket wall, and that the heat is transferred inwards to the vessel.
· Assuming both vessels are hemispherical with volume of 1440 litres of water
· The surface area of a hemi with OD of 1400mm is 3m2.
· Both vessels heating water from 20 Deg C to 100 Deg C.
· Steam at 3 bar 145 Deg C and oil at 4 bar 200 deg C
· Heat up times – Steam 45 minutes and Oil 48 Minutes
· Service flow rates – Steam 300 kg/hr and Oil 6000 kg/hr
It would seem safer and more efficient in adopting steam heated jackets for processing kettles.