Electric Circulation Heaters—Safety and Efficiency

Electric circulation heaters play an important role in a wide range of industries. Their ability to heat gases and liquids such as water, hydrocarbons, oils, and acids makes them particularly effective in the petrochemical and chemical processing industries.

Refinery processes such as gas, oil, and hydrocarbon heating, steam super heaters and mole sieve regeneration heating make heavy use of circulation heaters. Likewise, the electric circulation heater is used for the highly accurate, complex yet reliable heating processes demanded in the chemical processing industry.

Electric circulation heaters can even function as heat exchangers albeit using a different process. Unlike a tube heat exchanger wherein the medium is kept in tubes separate from the heating element, a circulation heater uses elements to heat the liquid or gas medium directly.

The latter method enables the circulation heater to attain efficiency rates of nearly 100%.

However, regardless of its role an electric circulation heater must be set up, optimized and maintained correctly for efficient and safe use. These factors together with the design determine how well the circulation heater will perform.

Good maintenance = efficiency, long life, and safety

Sound, regular maintenance practices are essential for the efficiency, safety, and longevity of electric circulation heaters. To optimize the function of a circulation heater you need to:

• Prevent overheating of the elements by using high-limit sheath sensors. Overheating can occur if a blockage halts the medium flow. A flow switch will shut down the heater immediately in these situations.
• Ensure that the heater is correctly installed, ideally in the horizontal position. Internal high-limit sensors are required if heaters are to be installed vertically. It is imperative to maintain the enclosure temperatures at or below 200 F. If temperatures exceed this, use cables and wiring with a higher temperature certification.
• Remove corrosion inside the terminal housing. Check for oxidation on all connections, clean and retighten them. A well sealed terminal housing may be required to protect against corrosion due to moisture or fumes. Blow clean with dry, oil-free air to complete this maintenance step.
• Remove scale build-up from the sheath and tubular elements regularly. Uncontrolled scale build-up will affect heat transfer to the liquid and may lead to overheating and failure. You can clean scale build up by brushing with a wire brush, using one of the mild, caustic chemical cleaners designed for this purpose or use a gentle sandblaster. Take care in all instances to avoid damage to the heater sheath.
• Look out for coking, which can occur when oil is heated and can contribute to premature heater failure. The degree of coking is closely linked to the temperature of the oil being heated so using a flat tubular element will reduce the incidence of coking, as the sheath runs cooler than that of a round tubular element.
• Ensure the heated section of the heater is free of silicone lubricant as its insulating properties may cause the heater to fail.
• Check all wiring connections—a common source of operation issues. Regularly check to ensure that electrical connections are tight (20 pound-inch torque on each heater stud). Alternating heating and cooling in the terminal enclosure may cause loose connections and these may lead to possible heater failure. Furthermore, the connections should be free of rust, oil, and dirt build-up. Clean and dry the interior of the terminal enclosure.
• Check and tighten any loose flange bolts and other mounting bolts as the heating/cooling process may have caused sealed bolts to loosen, resulting in leaks.
• Test sensing probes (thermostat or thermocouple) for correct operation and solid connections. Check safe grounding.

After purchasing your electric circulation heater, we urge you keep the previous advice in mind. For further insight into electric circulation heaters and other products in the Wattco catalog don’t hesitate to contact an expert today.