Process heating in an industrial setting is a function that involves many parts. An important aspect of nearly any industry, process heating is a procedure that largely defines the success of production: Many industrial-level products rely on a precise level of heat, whether it is in a food product or a gas pipeline. Electric immersion heaters provide that consistent, controllable heating for many efficient and sustainable industrial heating processes.

These industrial-level devices are designed to heat different substances such as water, food products and oil through direct contact with an electric heating element. Industrial immersion heaters achieve both high and precise temperatures through this direct contact. Because of this, immersion heaters are utilized in many process industries such as chemicals, oil and gas, and food processing.

One interesting development for electric immersion heaters has been the sharp increase in hydraulic fracturing. In all of these industries, the main purpose of an electric immersion heater is to bring the given substance to an elevated temperature or to prevent the substance from freezing in harsh environments. Usually applied in large pressure vessels or tanks, industrial-level immersion heaters are simply indispensable to process heating because of their efficiency, speed and cost-effectiveness.

Types of Immersion Heaters in Process Heating

Immersion heaters come in a variety of types and sizes, and as a group, they often are typically subdivided into two general types: direct and indirect immersion heaters. For the process heating applications already mentioned, three types in particular are used: over-the-side, circulation (or inline) and flanged electric heaters. All three are considered direct immersion heaters because the main heating element — called the sheath or terminal housing — comes into direct contact with the given liquid or substance. This direct contact also helps make these three types of heaters some of the most efficient devices for process heating.

To give a better picture of the specific applications and specifications, each type of electric immersion heater is discussed in detail.

Over-the-Side Heaters. Coated in a waterproof substance, over-the-side heaters are inserted in a tank or drum with the heating element positioned along the side of the vessel or at the bottom. This style of installation makes it easy for other operations to be conducted even while the substance is being treated by the heating element.

Over-the-side immersion heaters are usually designed to be compatible with nearly any standard tank. In addition, they typically can be customized to fit non-standardized tanks when needed. This is one of the features that make over-the-side immersion heaters popular as an economic choice for project managers. The interchangeability of the heating element means less customization and, therefore, less overhead cost.

Each over-the-side immersion heater usually is equipped with an external temperature probe and a digital controller. This makes it a much simpler task to bring large containers of liquid to the right temperature, and to maintain this temperature with minimal effort or concern about compromising the substance or the process.

Advantages of using over-the-side immersion heaters include the straightforward installation process of the heating elements. This offers a flexible option for project managers who need the heating element for different applications. Second, the heating elements offer an economical option for those with smaller projects and projected uses. Third, over-the-side immersion heaters can be used interchangeably with multiple substances and fluids.

Circulation (Inline) Heaters. Inline heaters can be used with many different substances, including everything from water and steam to waste oil. The major advantage of using inline heaters with substances like oil is their combined ability to control the temperature and regulate the viscosity of the substance. The heating element achieves this by pumping the fluid through a piping circuit that surrounds the encased inline heater. The desired temperature is achieved quickly because the substance is in constant contact with the heating element. At the same time, fluid viscosity is maintained because the substance is in constant motion.

Substances can be heated up to 1,000°F (538°C) using inline heaters because the actual heating element is insulated by anti-corrosion material. Once the substance reaches its determined temperature, the fluid is automatically released through the outlet nozzle at a predetermined rate.

Inline heaters are used in applications such as heating oils and other liquids, processing corrosive solutions, maintaining the correct temperature in water-cooled engines, superheating steam, controlling the heat in oil sumps and achieving preheating in various substances. Other advantages include that the installation and heating capability of inline heaters are relatively flexible.

Flanged Heaters. Flanged heaters are most commonly used in pressure vessels because the heat is divided evenly in order to avoid corrosion. In other words, flanged heaters are best used in tandem with pressure vessels for higher kilowatt applications. Flanged immersion heaters, like over-the-side heaters, usually are implemented along with accessible controls on the outside of the vessel or tank.

Flanged heaters have several benefits. First, just like many electric immersion heaters, they are easy to install and maintain. The fact that they are removable eases both installation and cleaning. Second, flanged heaters are available in a range of specifications and with different available elements. This means that they can be utilized in both large, high volume tanks and small, low watt density pressure vessels.

Benefits of Electric Immersion Heaters for Process Heating

Immersion heaters are beneficial for process heating applications for several reasons. The electric heaters leave a small footprint and have a low weight in most instances. This means workers do not have to deal with unnecessarily heavy equipment.

Electric immersion heaters have a precise control over temperature, which is beneficial for process heating that requires a more defined procedure. The heaters are also nearly completely independent because the energy input is driven by electric power without requiring any external process hookup.

Electric immersion heaters are nearly 100 percent efficient for process heating because nearly all of the input electricity is converted directly to heat.

For all of these reasons, electric immersion heaters have become increasingly popular in the global economic environment for industrial process heating.