Immersion Heaters for Lubrication Oil TanksThe product development team of a manufacturer of large rotating equipment contacted durex. They were looking for vendors with a more customer-oriented, engineering approach to upgrade their immersion heater designs used in lube oil heating systems. The electric heater not only had to provide heat to ensure proper lubrication in start-up conditions, but also needed to have an integrated, self-contained control system. The customer also wanted to integrate a liquid level control system that did not rely on the “traditional” heater element high limit temperature arrangement commonly used in industry. The other issue was space limitation for the installation and removal of the immersion heater for servicing.Considering the requirements, Durex developed an integrated electric immersion heater / control panel approach. A mini control panel was integrated into the industrial immersion heater design in place of the traditional terminal enclosure. The control system incorporated a thermostatic process control, a “floatless,” solid-state low liquid level sensor and control scheme, appropriate fusing, contactors, etc. as well. The panel was interconnected to the heater elements for easy installation and set-up. An on/off switch and limit reset were added to the front panel. Two power feeds are brought in: a 120V low voltage instrument feed and a 480V high voltage heater power feed across mechanical limit contactors. An integral low voltage transformer can be added to just go with a 480V high voltage power feed. To keep immersion length to a minimum, high density element counts are utilized along with appropriate watt densities depending on the type of lubrication oil used and the tank nozzle connection sizes.
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