Thermal oil systems often consist of a primary system and one or more secondary systems.
The primary system consists of a boiler, pump (s), piping, storage tank, expansion tank, possibly a heat exchanger, etc. that is installed as a circuit, naturally provided with the necessary pressure and temperature protection units. The boiler heats the thermal oil, the pump circulates the oil in the primary circuit.
Thermal oil systems can be equipped with so-called economizers. These are units that are installed in the boiler exhaust system that can improve efficiency by a few percent.
In the secondary circuits, ie those parts of the thermal system that are connected to the users (this can be a reactor vessel, a drying tunnel, or whatever) will send the required heat via controlled valves. The cooled oil is pumped back into the primary circuit to be reheated by the boiler.
It will be clear that the capacity of the boiler depends on the size of the secondary circuits and the heat required per circuit. In thermal oil systems, all circuits are protected against overpressure, too high and or too low temperature, and the flow (flow) is constantly measured. When the pump (s) fail, the boiler is automatically switched off to prevent overheating and / or combustion of the thermal oil.
The vast majority of thermal oil systems up to 350 °C are virtually pressure-free and operate in the liquid phase of the thermal oil. At temperatures above 350 °C, the pressure can rise to 10 bar. Thermal oil systems operating around 400 °C can operate in the gas phase of the thermal liquid in addition to the liquid phase, depending on the customer's wishes.
