The Working Principle of Thermal Hot Oil Heaters

Heat exchangers are used in the transfer of thermal energy from one system to another when direct heat transfer is not possible. In most scenarios like this, the heat exchanger employs a working fluid to transfer heat from a source to a different location.

But today, the use of oil as a thermal fluid is becoming more and more common. Oil heaters do not experience problems with high pressure or corrosion created by steam. They can also be employed in a large range of applications across diverse industries, including oil and gas, water and wastewater, and process heating.

Extremely versatile, hot oil heat transfer systems allow for very high efficiency. In fact, for waste heat recovery applications, these devices may see efficiency values above 90% — significantly higher than those of steam-based heating systems.

Using Thermal Fluid Heating Systems Instead of Direct Fired Systems

Industry professionals employ thermal fluid heating systems for a variety of different reasons, but chief among them is safety. In most industrial processes, heat is generated by the direct combustion of a hydrocarbon; in general, it’s unsafe to directly transfer heat from this source to a load. Plus, this approach offers little control over heat transfer.

The combustion process can seriously endanger the safety of the exposed mechanical components. This fact can, in turn, significantly increase system maintenance costs. In thermal fluid systems, however, the heat from the primary source is transferred to a circulating fluid, which is pumped to a heat exchanger that can then be used to heat a secondary fluid, thus providing an indirect heat transfer path.

In some industrial processes, it is possible to directly heat the fluid at the load end, or the secondary fluid. But in many applications, the secondary fluid may be corrosive, making this approach very difficult, if not impossible. And in other situations, the secondary fluid may have a desired temperature limit that is low compared with that of the oil (at 350 °C), making this method highly inefficient.

How Hot Oil Heaters Work

Thermal oil heaters operate on the same principle as their steam-based counterparts. The thermal oil heater design process begins with the identification of the most appropriate setup for a given process system. Components of sufficient strength are then chosen, and the heater is constructed.

When constructing these devices, it’s essential that the working fluid (thermal oil) maintains a temperature between the oil’s flash point and fire point. Other conditions conducive to mechanical breakdown, such as leaks, must be avoided. It’s also important to ensure that the working fluid is completely contained and is not exposed to moisture or direct sunlight.

A thermal hot oil heater can serve as an effective solution if all of these precautions are taken. As discussed earlier, these devices gain heat from a source, carry the thermal energy in an oil pumped through pipelines, and then transfer that energy to the secondary fluid.

Vertical Vs. Horizontal Hot Oil Heaters

There is no functional difference between vertical and horizontal heater installation. In either case, the heat is transferred from the working fluid (thermal oil) to the secondary fluid. The choice of a vertical or horizontal configuration is based primarily on the specific plant layout and space constraints.

In general, horizontal hot oil heater transfer systems allow for better access to the device for maintenance operations, but they also take up more floor space. Vertical heaters take up less space but can pose accessibility challenges.

The Versatility of Industrial Hot Oil Heaters

Versatile, reliable, and high-performing, hot oil heaters are used in a range of different process industries. While there are some upfront costs required to shift from traditional steam-based devices to hot oil heaters, the long-term safety benefits and low maintenance costs provide for a positive return on investment.

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