Thermal Fluid Heaters (Hot Oil Heaters) utilize oil as the heat transfer media, which is circulated in a closed loop between the heater and a customer’s heat user. Generally speaking, mineral oils are limited to about 550°F and synthetic oils can reach up to 750°F. While the most common thermal fluid heating systems are in liquid phase, vapor phase oil systems are available as well.
Using oil as the heat transfer media allows us to supply a customer with high temperature while operating at low pressure. The materials of construction for most hot oil installations are limited to Schedule 40 carbon steel pipe which quite easily meets the pressure/temperature requirements. A steam system that operates at a similar temperature requires a much higher operating pressure. The higher operating pressure of a steam system could and often does require a much thicker, costlier material such as Schedule 80, Schedule 120, or even a much thicker Schedule 160.
Thermal fluid systems have no water treatment requirement, no feed water preheat requirement, no blow-down losses, and most do not need freeze protection. Comparing steam systems with the additional ancillary component requirements and associated operating costs, thermal fluid systems are increasingly more often the best solution.
Thermal fluid heaters are normally constructed to meet ASME Section VIII of the Boiler and Pressure Vessel Code. In most areas, ASME Section VIII equipment does not require a licensed boiler operator, thus potentially allowing for additional savings by the customer.
Overall, when operating at higher temperatures, the features of a thermal fluid heating system can yield significant savings versus a steam system.