The SRY9-380V/6KW sheathed electric heater is used in the heating section of heat transfer oil systems, working with temperature control devices to raise the medium temperature. After the element is energized, heat is conducted to the heat transfer oil through the sheath wall, with an electric-to-heat conversion efficiency of no less than 95%, and the allowable working voltage error not exceeding 1.1 times the rated value. In on-site operation and maintenance, this model differs significantly from direct immersion bare wire heating solutions. The following comparison is made from several aspects.
Direct immersion heating wires are exposed in the heat transfer oil and are prone to adhesion by oil oxidation products during long-term operation, causing local overheating. The SRY9 type uses a metal sheath to completely isolate the heating element from the heat transfer oil, reducing coking tendency and facilitating extraction for inspection or replacement. Maintenance personnel can service a single element without draining the system, reducing downtime.
Heat transfer oil heating requires attention to the correspondence between surface load and medium temperature. The SRY9 type has its surface load limited according to the medium temperature at the design stage to avoid oil cracking due to local high temperatures. Compared with some heating tubes modified on site, this model has a smaller fluctuation range of sheath surface temperature when the temperature control loop is working normally, which helps extend the service life of the heat transfer oil.
This model has a rated voltage of 380V, a power of 6kW, and uses three-phase power supply. During operation, the three-phase current imbalance should be measured regularly. If the deviation exceeds 10%, the wiring terminals or the internal resistance of the element should be checked. Compared with single-phase heating solutions, three-phase power supply has lower line current at the same power, placing less burden on on-site distribution cables and switchgear.
The SRY9 type is usually fixed to the side wall of the oil tank by flange or threaded connection. During disassembly and assembly, it is necessary to confirm that the sealing gasket is intact. Compared with plug-in heating rods, its sheath outer diameter is larger, and there are clear requirements for the installation hole size. The maintenance cycle is recommended to be determined in combination with oil testing results. If the carbonized layer on the sheath surface is found to be thickened, it should be cleaned or replaced in time to avoid affecting heat transfer efficiency.
