Thermal fluid heaters, also referred to as hot oil heaters, are industrial heating systems in which a special heat-transfer liquid is recirculated by a pump through a fired heat exchanger. Thermal fluid heaters are used in industrial processes requiring high efficiency and accurate temperature control ranging between 300 °F and 750° F. These heaters operate in a closed-loop circulation system under minimal pressure.
The uses of thermal fluid heaters include food, plastic, and chemical processing, as well as pharmaceutical and biofuel production. Offering a range of unique benefits, these heaters can function at high temperatures for extended periods, resist scale formation and corrosion, and allow for automatic operation. Their sturdy design ensures long operating life which minimizes the risk of costly downtime.
Key Factors to Keep in Mind When Choosing a Thermal Fluid Heater
There are several important factors to keep in mind when deciding on a specific thermal fluid heating system. Users should carefully consider the specific application at hand and design parameters, installation requirements, space restrictions, maintenance requirements, costs versus budget, and fuel efficiency.
First, evaluate the surface area of the heater coil, also called the heat-transfer surface. A generous surface area is imperative for proper heater design. Too small of a heater coil or heating element will impede efficiency and result in a higher film temperature, which thermally degrades the heat-transfer fluid. Also, running poor-quality oil in a system will shorten the life of coils and coke-heating elements, and slowly reduce heater efficiency. On the other hand, operating a smaller coil and using less surface area can allow for significant cost savings. Therefore, when comparing heating systems, it’s critical to carefully assess the coil and element surface area, as well as relative heat-flux rates.
Fuel efficiency should also be kept in mind. A simple process with low supply temperatures and inexpensive thermal fluid may not require a customized, highly efficient system, so a less expensive option may be suitable. Conversely, a more complex process requiring higher temperatures and more expensive fluid will benefit from a more sophisticated system.
Finally, consider fluid velocity and pressure drop when weighing options for a heating system. A higher fluid velocity typically means better heat transfer and lower film temperatures. Keep in mind, however, that pressure drop increases with fluid velocity, which translates to a need for a higher pump horsepower and in turn, increases operating costs.
Coil Design Options for Thermal Fluid Heaters
There are several different types of tank heating coils available, typically:
- helically wound fin tubes
- longitudinal fins
- bare pipe
Helically wound fins offer several benefits over their longitudinal counterparts. Their heat transfer is twice as great, and they require half the number of coils, saving money and reducing installation costs. Also, helically wound fins don’t have “dead spots,” making them much less likely to coke.
Compared to a bare pipe setup, a helically wound coil has up to 12 times greater surface area per linear foot of pipe, so significantly less pipe is needed to heat the tank. Single helical coil thermal fluid heaters can provide simple, cost-effective solutions for a wide range of applications.
Selecting the Proper Thermal Fluid Heating System
Several factors must be taken into consideration when deciding on a thermal fluid heating system - specific application, installation requirements, space restrictions, design requirements, maintenance needs, cost, and fuel efficiency must all be carefully considered before deciding on a specific model. Partnering with a knowledgeable supplier who can guide you through the selection process will help ensure you get the best heating system for your unique application.
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