All oil and gas processing facilities have operating parameters specific to the application, to guide the selection of the most suitable heat transfer fluid. However, there are a few general parameters to keep in mind to select a fluid that delivers maximum efficiency for as long as possible.
The first thing to consider is thermal stability. All heat transfer oils can degrade over time, and the rate of degradation increases when the operational temperature exceeds that of the oil’s recommended use.
At high temperatures, the bonds between hydrocarbon chains start to break and produce carbon in a process called fouling. As the carbon concentration in the fluid increases, it deposits sludge into the pipes. This reduces the efficiency of the system and, if action is not taken, this sludge can obstruct the pipes and lead to serious safety hazards.
It’s important to choose a thermal fluid with a high thermal stability, which can resist high temperatures and occasional temperature peaks. This can slow down degradation and prevent the formation of sludge. It’s also important to choose a heat transfer fluid with a high flash point, the temperature at which a fluid produces enough vapour to be ignited. Over time, the molecules in a thermal fluid will break down in a process called thermal cracking, creating volatile light ends. These cause the flash point to drop, increasing the risk of fire.
In remote applications, such as offshore platforms, a fluid change can be very costly. At the same time, it’s essential that fire hazards must be avoided at all cost. For this reason, in these applications it’s essential to maintain the fluid’s normal operating conditions for as long as possible.