Understanding Electric Process Heaters

Electric process heaters use electricity to increase the temperature of liquids and gases within process systems. Depending on the application, electric process heaters may be used for both direct and indirect heating, which makes them a particularly versatile heating option. To help you find the best electric heater for your needs, we have compiled a concise summary of electric process heater systems and their common uses.

Types of Electric Process Heaters

Electric process heaters are available in two separate styles: immersion heaters and circulation heaters. Each type offers distinct advantages for particular applications.

Immersion Heaters

Immersion heaters heat gases and liquids through direct contact. As the name suggests, the tubular electric elements are immersed in the process fluid. The major benefit of this type of process heater is that nearly all of the electricity generated is converted directly into heat with almost 100% efficiency. Heating elements are typically composed of highly corrosion-resistant and heat-resistant materials, such as Alloy 800, to ensure the optimal operation and service life of the heater.

Circulation Heaters

A circulation heater heats fluid as it passes through an enclosed system directly over the heating elements. The heater is often in the tube or pipe through which the gas or liquid material flows. Circulation heaters are highly specialized, and must often be tailored to the needs of each individual application.

Electric Thermal Fluid Systems

Thermal fluid heating is a type of indirect heating in which a liquid phase heat transfer medium is heated and circulated to one or more heat energy users within a closed loop system. Thermal oil, glycol, and water are common heat transfer mediums for these systems. An electric circulation heater can be used as a heat source for these closed-loop thermal fluid systems.

Common Applications

Heat control is critical to a wide variety of processes, from melting materials into formable resins to superheating gases and initiating chemical reactions. Below is a short summary of common applications in which electric process heaters are used.

Jacketed Reactor Heating & Cooling

Jacketed reactors are often kept at processing temperatures up to 800° F, and must be maintained at a stable temperature to ensure proper functionality. As the name implies, the reactor is covered with a secondary protective jacket around the surface of reactor vessel. Steam or thermal fluid is circulated through the jacket to control the reactor’s temperature.

Molding & Extrusion

Molding and extrusion processes require very specific temperature control. In addition to maintaining the temperature of the resin to ensure ideal part formation, the temperature of the part-forming extruder or mold must also be regulated. Closed-loop thermal fluid systems are used to monitor and adjust the system temperature as needed. Although steam heating systems are also used for molding and extrusion applications, they are not as safe as thermal fluid systems due to the high pressure required for effective steam heating. 

Molten Salts

Molten salts, or salt melts, refer to a range of materials composed of fluoride, chloride, or nitrate which are used for thermal energy storage and high-temperature industrial processes. Molten salts are valued for their ability to retain liquid form in temperatures upwards of 1000° F without increasing vapor pressure. They are often used in high-energy batteries for solar arrays and high-temperature metal treatments.

Other Applications

In addition to the above, other common applications of electric process heaters include:

• Asphalt production
• Glycol and amine re-boiling
• Freeze protection
• Tank temperature regulation
• Liquid vaporization
• Condensate stabilization
• Viscosity reduction
• High temperature air control
• Nitrogen and thermal fluid heating
• Heating of process gas, fuel gas, and natural gas

Electric Process Heater Considerations

When selecting the best electric process heater for your application, it is important to consider the needs and limitations of your equipment. Be sure to consider the following key factors:

• Fluid flow rate. Consider the volume or the flow rate of fluid to be heated to determine the heater’s required capacity.
• Process temperature. The greater the temperature increase, the greater the power output required.
• Thermal properties. The fluid’s thermal and physical properties help to determine the appropriate watt density.
• Footprint. Space and other physical limitations must be considered when determining the heater’s size and placement.

Sigma Thermal Solutions

Sigma Thermal Solutions offers the highest quality thermal immersion and circulation electric heaters on the market. We offer a watt-density range from 2–60 watts per square inch, and each system is specifically engineered for versatility to meet a wide range of system requirements. To ensure superior quality, our electric process heaters can be manufactured to meet and exceed a variety of industry standards, including ASME Section VIII Div I, CRN, and PED.

For more information on our superior thermal solutions, contact the experts at Sigma Thermal today or request a quote.