When viscous media such as heavy oil are transported in storage tanks or pipelines, a drop in temperature causes viscosity to rise rapidly, increasing pumping load and even leading to pipeline solidification. Field operation and maintenance personnel often encounter phenomena such as coking on the surface of heating elements, power attenuation, excessively high junction box temperature, and leakage at flange seals. These problems are mostly related to the selection of power density, matching of medium characteristics, and the setting of heat dissipation zones.
The ZYC series among explosion-proof electric heating plates provides differentiated power density solutions for different media. Models with a power density of 0.8W/cm² are suitable for viscous media such as heavy oil, with the number of heating tubes ranging from 1 to 3, insertion depths covering 2.7m, 5.2m, and 7.8m, power corresponding to 5kW to 45kW, and flange specifications from DN100 to DN300. Models with a power density of 1.5W/cm² are used for media such as light oil and medium oil, with insertion depths of 5.8m or 7.2m and a power range of 20kW to 75kW. During selection, if the medium operating temperature is relatively high, it is necessary to confirm whether a heat dissipation zone is configured to reduce the internal temperature of the junction box and avoid premature aging of electrical components.
During the operation and maintenance stage, the surface of the heating tubes should be regularly inspected for carbon deposits or scaling. Especially under heavy oil conditions, local overheating will accelerate coking. Flange connections need to be retightened periodically to prevent seal failure caused by thermal cycling. Measuring the insulation resistance of the heating tubes to ground and the loop resistance can determine whether the elements are damp or broken. If it is found that the power density does not match the actual medium, it should be recalculated based on the medium viscosity-temperature curve rather than simply increasing the voltage.
The installation direction, insertion depth, and medium flow state of explosion-proof electric heating plates also affect the heat exchange effect. For static storage tanks, the arrangement of heating tubes should avoid local dead zones; for flowing pipelines, sufficient residence time for the medium being heated must be allowed. Recording operating current, outlet temperature, and surface temperature on site helps establish a health record for the equipment and provides a basis for subsequent maintenance.
