What is an electric process heater and what is its primary function in industrial applications?
Electrical process heaters are designed for efficiently heating liquid or gaseous flowing fluids. The design is based on the general conditions such as the type and properties of the respective fluid, pressure and temperature as well as the desired operating points in the process.
Depending on the application, electric process heaters may be used for both direct and indirect heating, which makes them a particularly versatile heating option.
What are the main components of an electric process heater and their functions?
Heater elements within electric heaters are mainly composed of three elements: an insulating core, a heat conductive coil wrapped around the insulation, and an encasing sheath made from stainless steel, aluminum, nickel or iron.
How does an electric process heater generate and transfer heat to the process fluid?
Electrical process heaters directly heat fluids, converting electrical energy in the heating rods to thermal energy. The thermal energy is then transferred from the heating rods to the fluid. Here, it is important that the design be matched to the general conditions, for each fluid has its specific properties.
What types of heating elements are commonly used in electric process heaters, and how do they differ?
The design of the individual heating elements is a function of the application. There are faster or slower heating elements, mechanically robust or more filigree designs. Also, a distinction is made between compacted heating elements and heating elements where the internal heating insert can be replaced without the necessity of draining the fluid.
Heating elements
Tubular heaters, diameter 8.5 or 16 mm
Cartridge-type heaters, diameter 16, 18 or 25 mm
Exchangeable heating elements, including a protective tube, diameter 25, 42 or 65 mm
What are the primary applications of electric process heaters in various industries?
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.
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
How do you determine the appropriate size and power rating of an electric process heater for a specific application?
Your heating problem must be clearly stated, paying careful attention to defining operating parameters. Take these into consideration:
Minimum start and finish temperatures expected
Maximum flow rate of materials being heated
Required time for start-up heating and process cycle times
Weights and dimensions of both heated materials and containing vessels
Effects of insulation and its thermal properties
Electrical requirements — voltage
Temperature sensing methods and locations
Temperature controller type
Power controller type
Electrical limitations
And since the thermal system you’re creating may not take into account all the possible or unforeseen heating requirements, don’t forget a safety factor. A safety factor increases heater capacity beyond calculated requirements.
What materials are typically used in the construction of electric process heaters to ensure durability and efficiency?
The fluid to be heated and the application temperature mainly define the materials which can be used for the unheated and/or heated surfaces. Otherwise, corrosion may quickly result in a failure of the flow-type heater, for example.
Materials of the wetted and unheated components
Carbon steel
Corrosion-resistant stainless steel
Heat-resistant stainless steel
Titanium, Hastelloy, special materials
Brass
Materials of the heating surface:
Carbon steel
Corrosion-resistant stainless steel
Heat-resistant stainless steel
Titanium, Hastelloy, special materials.
How do temperature and pressure conditions affect the performance of an electric process heater?
Electric process heaters can reach higher temperatures than fuel heaters. That makes them capable of performing tasks other heaters cannot. Being able to reach and maintain operation at high temperatures gives electric immersion heaters a big advantage over combustion heaters.
Electric process heaters boast higher efficiency rates and offer precise temperature control, leading to optimized energy consumption and enhanced process performance. Unlike fossil fuel heaters, which suffer from combustion losses and heat dissipation, electric heaters convert nearly all input energy into useful heat. This efficiency translates into reduced energy costs and improved productivity, making electric heaters a financially attractive option in the long run.
What are the common maintenance procedures for electric process heaters to ensure optimal performance and longevity?
Maintenance and Inspection
Regular Cleaning: Dust and debris can accumulate in your heater, causing it to overheat. Regularly clean the heater’s grills and vents with a soft cloth or vacuum cleaner.
Check for Damage: Inspect the heater’s cord and plug for any signs of wear or damage. Do not use the heater if the cord is frayed or the plug is damaged.
Professional Servicing: If your heater is malfunctioning, seek professional servicing rather than attempting repairs yourself. This ensures that any issues are correctly and safely resolved.
How can electric process heaters be controlled and monitored to maintain precise temperature settings?
The proper control monitoring of the electric process heater is also critical, and many legacy process heating systems include old-fashioned and outdated control systems that do not actively link the current real-time heater performance to the professionals that are paid to monitor them. Control room personnel with modern heater control and switching technology can actively monitor phase loss, current draw and heater sheath temperatures at their local control room human machine interface (HMI) screen. Upgrades should include using modern Silicon Controlled Rectifier (SCR) monitoring products available, such as the Watlow ASPYRE SCR, designed to provide real-time monitoring and data. The addition of process and overtemperature sensors can be monitored by way of connected devices to help monitor runaway conditions damaging to the process. Phase-loss detectors can show unbalanced electrical load and trigger maintenance corrections that will help the heater run longer and more effectively. All items can be easily added to the existing control loop.
What safety considerations should be taken into account when installing and operating electric process heaters?
Proper Placement:
Place your heater on a flat, stable surface.
Keep it away from flammable materials like curtains, furniture, and bedding.
Maintain a safe distance of at least three feet from any objects.
Avoid Water Exposure: Never use an electric heater in damp or wet areas, such as bathrooms or kitchens, unless it’s specifically designed for such environments. Water exposure can lead to electrical shocks or short circuits.
Supervise Usage:
Always turn off the heater when you leave the room or go to sleep.
Keep an eye on the heater when it’s in use, especially if children or pets are around.
Use Appropriate Power Sources:
Plug your heater directly into a wall outlet. Avoid using extension cords or power strips, as they can overheat and cause fires.
Ensure your home’s electrical system can handle the heater’s power requirements.
Specific Safety Features
When purchasing an electric heater, look for these safety features:
Overheat Protection: Automatically shuts off the heater if it becomes too hot, preventing potential fire hazards.
Tip-Over Switch: Turns off the heater if it’s accidentally knocked over, which is especially important for homes with children and pets.
Cool-Touch Housing: Ensures the heater’s exterior remains cool to the touch, reducing the risk of burns
What are the common failure modes of electric process heaters and how can they be mitigated?
Heating element may fail due to any one or more of the following reasons:
Formation of hotspots.
Oxidation of the element and intermittency of operation.
Embrittlement caused by grain growth.
Corrosion