electric process heaters

In modern industrial processes, maintaining precise temperatures is crucial for the quality and efficiency of production. Electric process heaters play a vital role in achieving this by providing a reliable and controllable source of heat. These heaters use electrical energy to generate heat, which can be transferred to various substances or workpieces. Whether it’s heating liquids, gases, or solids, electric process heaters offer versatility, precision, and energy – efficient solutions for a wide range of industrial applications.​

Induction Heating​
Induction heating operates on the principle of electromagnetic induction. An alternating current (AC) is passed through a coil, creating a changing magnetic field. When a conductive material, such as a metal workpiece, is placed within this magnetic field, eddy currents are induced in the material. These eddy currents encounter the electrical resistance of the material, generating heat. The amount of heat generated can be controlled by adjusting the frequency and intensity of the alternating current in the coil. Induction heating offers several advantages, including rapid heating, precise temperature control, and the ability to heat specific areas of a workpiece without heating the entire object.​
Infrared Heating​
Infrared heating relies on the emission of infrared radiation. All objects with a temperature above absolute zero emit infrared radiation, and electric infrared heaters use this principle to generate heat. These heaters typically consist of heating elements, such as quartz lamps or ceramic emitters, that are heated electrically. When heated, these elements emit infrared radiation, which is then absorbed by the object or medium to be heated. The absorbed infrared energy is converted into heat within the object, causing it to warm up. Infrared heating is known for its fast response time, energy efficiency, and the ability to heat objects without direct contact, making it suitable for applications where rapid and precise heating is required.​
Types of Electric Process Heaters​
Immersion Heaters​
Design and Operation​
Immersion heaters are designed to be directly immersed in the substance to be heated, such as liquids or molten materials. They consist of a heating element, usually made of stainless steel, nickel – chrome alloy, or other corrosion – resistant materials, encased in a protective sheath. The heating element is connected to an electrical power source, and when energized, it heats the surrounding medium. Immersion heaters can be either flanged, where they are mounted through a flange on the side of a tank or vessel, or cartridge – type, which are inserted into drilled holes in a solid object, such as a mold or a metal block.​
Applications​
They are widely used in various industries. In the chemical industry, immersion heaters are used to heat chemical reactors, tanks, and vessels, ensuring that chemical reactions occur at the desired temperatures. In the food and beverage industry, they can be used to heat liquids during the production process, such as heating milk for pasteurization or heating cooking oils. They are also commonly found in laboratories for heating small volumes of liquids for experiments.​
Circulation Heaters​

Design and Operation​
Circulation heaters are used to heat fluids that are in a continuous flow. They typically consist of a housing with one or more heating elements inside. The fluid enters the heater, flows around the heating elements, absorbs the heat, and then exits the heater at an elevated temperature. These heaters often have a compact design and can be integrated into existing fluid – circulation systems. Some circulation heaters may also include features such as built – in pumps to ensure a consistent flow rate of the fluid.​
Applications​
Circulation heaters are essential in industrial processes where a continuous supply of heated fluid is required. For example, in plastic manufacturing, they are used to heat the plastic melt as it is being extruded or injection – molded, ensuring a smooth and consistent production process. In power plants, they can be used to heat the coolant in closed – loop systems, maintaining the optimal operating temperature of the equipment.​
Duct Heaters​
Design and Operation​
Duct heaters are installed within air ducts or ventilation systems to heat the air passing through them. They usually consist of heating elements, such as finned – tube elements or wire – wound elements, mounted in a metal housing. The air flows over the heating elements, absorbing the heat and increasing in temperature. Duct heaters can be controlled to regulate the temperature of the air, and they may be equipped with sensors and control systems to maintain a consistent output.​
Applications​
These heaters are commonly used in commercial and industrial buildings for space heating. In large warehouses, factories, and office buildings, duct heaters can be integrated into the central heating and ventilation systems to warm the incoming air, providing a comfortable indoor environment. They are also used in industrial processes where heated air is required, such as in drying processes for wood, paper, or textiles.​
Band Heaters​
Design and Operation​
Band heaters are cylindrical in shape and are designed to be wrapped around cylindrical objects, such as pipes, barrels, or machine components. They are made up of a heating element, usually a resistance wire, embedded in a flexible insulation material and enclosed in a metal sheath. The band heater is secured around the object to be heated using clamps or fasteners. When powered, the heating element generates heat, which is transferred to the object through conduction.​
Applications​
Band heaters are widely used in the plastics industry to heat the barrels of injection – molding machines and extruders. They help to maintain the temperature of the plastic material as it is being melted and processed, ensuring consistent product quality. In the packaging industry, they can be used to heat sealing jaws for heat – sealing plastic films or bags.​
Applications of Electric Process Heaters​
Manufacturing Industry​
Metalworking​
In metalworking processes, electric process heaters are used for various purposes. Induction heaters are commonly used for forging, where they heat metal billets or bars to a high temperature, making them more malleable and easier to shape. Resistance heaters can be used for heat – treating metals, such as annealing, quenching, and tempering, to improve their mechanical properties. Band heaters are often used to heat the dies and molds in metal – casting processes, ensuring that the molten metal fills the mold cavities properly.​
Plastics Processing​
The plastics industry relies heavily on electric process heaters. Immersion heaters are used to heat the plastic pellets in hoppers before they are fed into the extrusion or injection – molding machines. Circulation heaters maintain the temperature of the plastic melt during the extrusion process, ensuring a smooth flow and consistent product dimensions. Infrared heaters can be used for post – processing operations, such as drying and curing plastic parts, reducing the cycle time and improving the quality of the final product.​

Chemical Industry​
Reactor Heating​
In chemical plants, electric process heaters are used to heat reactors where chemical reactions take place. These heaters ensure that the reactions occur at the optimal temperature, which is crucial for the yield and quality of the chemical products. Immersion heaters can be directly installed in the reactors to provide uniform heating, while circulation heaters can be used to heat the reaction medium as it circulates through the system.​
Distillation and Evaporation​
During distillation and evaporation processes, electric heaters are used to provide the necessary heat to separate components in a mixture or to remove solvents. Duct heaters can be used to heat the air or gas streams in distillation columns, while resistance heaters can be used to heat the stills or evaporators, ensuring efficient separation and concentration of the chemical substances.​
Food and Beverage Industry​
Cooking and Processing​
Electric process heaters are used in food processing plants for cooking, baking, and pasteurization. Immersion heaters can be used to heat liquids, such as soups, sauces, and milk, during the cooking and pasteurization processes. Infrared heaters are commonly used in ovens for baking bread, cakes, and other baked goods, providing even and efficient heating. Duct heaters can be used to heat the air in drying rooms, where food products are dried to remove moisture and extend their shelf life.​
Beverage Production​
In the beverage industry, electric heaters are used for heating and cooling processes. For example, in beer brewing, electric heaters are used to heat the mash during the mashing process and to heat the wort during the boiling process. They are also used to heat the water for cleaning and sanitizing equipment. In the production of bottled and canned beverages, electric heaters can be used to heat the filling machines and to maintain the temperature of the beverages during the filling and capping processes.​
Future Expansion​
When selecting an electric process heater, it’s advisable to consider future expansion plans. If there is a possibility of increasing the production volume or adding more processes that require heating in the future, choosing a heater with a slightly higher power capacity than the current needs can save the cost and inconvenience of having to replace the heater later.​
Temperature Range​
Application – Specific Requirements​
Different industrial applications have specific temperature requirements. Some processes may only need to operate at relatively low temperatures, while others, such as certain heat – treatment processes in the metal industry or high – temperature chemical reactions, require high temperatures. It’s essential to choose an electric process heater that can provide the required temperature range for the specific application. For example, in a plastics extrusion process, the heater may need to maintain a temperature range of 150 – 300°C, while in a metal forging process, the temperature may need to reach 1000°C or higher.​
Temperature Control Accuracy​
In addition to the temperature range, the accuracy of temperature control is also important. In precision manufacturing processes or in chemical reactions where a specific temperature needs to be maintained within a narrow tolerance, heaters with advanced temperature control systems are required. Some electric process heaters are equipped with digital controllers that can maintain the temperature within ±1°C or even better, ensuring consistent product quality and process efficiency.​
Heater Material and Construction​
Compatibility with the Medium​
The material of the heater should be compatible with the substance being heated. For example, if the heater is used to heat corrosive liquids, such as acids or alkalis, the heating element and the sheath material should be resistant to corrosion. Stainless steel, nickel – based alloys, and certain types of ceramics are commonly used materials for heaters in corrosive environments. In applications where the heater comes into contact with food products, the materials used should be food – grade and comply with relevant safety standards.​
Durability and Reliability​
The construction of the heater should ensure durability and reliability. Heaters with a robust design, proper insulation, and high – quality components are more likely to withstand the rigors of industrial use and have a longer lifespan. Look for heaters with features such as reinforced heating elements, double – walled insulation, and sturdy mounting brackets to ensure stable operation.​
Safety Features​
Over – Temperature Protection​
An essential safety feature of electric process heaters is over – temperature protection. This feature monitors the temperature of the heater or the medium being heated and shuts off the power supply if the temperature exceeds a pre – set limit. Over – temperature protection can prevent damage to the heater, the processed material, and potential safety hazards such as fires or explosions.​
Ground Fault Protection​
Ground fault protection is designed to detect and interrupt the electrical current in case of a fault, such as a short circuit to ground. This helps to prevent electrical shocks and damage to the equipment. Electric process heaters should be equipped with reliable ground fault protection devices, especially in environments where there is a risk of water or moisture exposure.​
Thermal Insulation​
Proper thermal insulation around the heater helps to reduce heat losses, improve energy efficiency, and prevent accidental burns. The insulation material should be of high quality and have good thermal – insulating properties. Additionally, the insulation should be designed to withstand the operating temperature of the heater without degrading or releasing harmful substances.​
Maintenance of Electric Process Heaters​
Regular Inspections​
Heating Elements​
Regularly inspect the heating elements for signs of wear, damage, or deterioration. Look for cracks, breaks, or discoloration in the heating elements. If any damage is detected, the heating elements should be replaced promptly to ensure the proper operation of the heater. In the case of resistance heating elements, check the electrical connections for tightness and signs of corrosion.​
Electrical Connections​
Inspect all electrical connections, including wires, terminals, and plugs, for loose connections, frayed wires, or signs of overheating. Loose connections can cause arcing, which can damage the connections and pose a safety hazard. Tighten any loose connections and replace any damaged wires or terminals.​
Control Systems​
Check the control systems, such as thermostats, controllers, and sensors, to ensure they are functioning correctly. Calibrate the temperature sensors regularly to ensure accurate temperature readings. Test the control functions, such as on/off switching, temperature adjustment, and safety shut – off mechanisms, to ensure they are working properly.​
Cleaning​
Exterior Cleaning​
Clean the exterior of the heater regularly to remove dust, dirt, and debris. Use a soft cloth or brush to wipe the surface of the heater. Avoid using abrasive cleaners or solvents that may damage the finish or the insulation of the heater.​
Interior Cleaning (if applicable)​
For heaters where the interior can be accessed, such as immersion heaters or duct heaters, clean the interior periodically to remove any scale, deposits, or contaminants. This can improve the heat transfer efficiency of the heater. Use appropriate cleaning agents and methods based on the type of heater and the nature of the contaminants.​
Lubrication (if applicable)​
Some electric process heaters, such as those with moving parts like fans or pumps, may require lubrication. Follow the manufacturer’s recommendations for lubrication intervals and the type of lubricant to use. Proper lubrication can reduce friction, wear, and noise, and extend the lifespan of the moving parts.​
Replacement of Worn – Out Parts​
Over time, certain parts of the electric process heater may wear out or become damaged. Replace any worn – out or damaged parts promptly to maintain the performance and safety of the heater. Keep a stock of essential spare parts, such as heating elements, fuses, and control components, to minimize downtime in case of a breakdown.​
Conclusion​
Electric process heaters are versatile and essential components in modern industrial processes. Understanding their working principles, different types, applications, selection criteria, and maintenance requirements is crucial for ensuring their efficient and reliable operation. By carefully considering these factors, industries can select the right electric process heaters for their specific needs, optimize their production processes, and improve product quality while maintaining a safe working environment.