In the application of stainless steel explosion-proof heating rods in air separation equipment electric heating tubes, issues of surface temperature and medium compatibility are often encountered. Taking the SUTE air separation equipment electric heating tube as an example, its technical parameters specify a maximum surface temperature of 270°C (within 1000h), which is a reference for O&M personnel to judge whether the thermal load is reasonable. Compared with ordinary single-ended heating rods, the explosion-proof structure has additional requirements for sheath thickness and terminal chamber sealing, and the surface heat dissipation conditions change accordingly. On site, the voltage and power matching must be checked according to actual working conditions.
When melting solid oils such as asphalt and paraffin, directly applying the rated voltage can easily cause local overheating. Compared with similar solutions, some heating tubes adopt a reduced-voltage startup method: after the solid is completely melted, the voltage is raised to the rated value for operation. This avoids a sudden rise in sheath surface temperature and reduces the risk of coking and insulation aging. O&M personnel should confirm whether the voltage regulating device or stepped wiring has the conditions for reduced-voltage startup, and record the current changes during the melting stage.
In daily maintenance, referring to the limit that the surface temperature shall not exceed 270°C within 1000h, regularly check whether the heating tube surface has blackening, carbon deposition, or decreased insulation resistance. Compared with ordinary heating rods, the terminal chamber and seals of explosion-proof products require special attention to prevent medium infiltration from affecting insulation. If slow heating is found, first check the supply voltage and medium fluidity rather than directly increasing the set temperature.
When comparing selections, attention should be paid to whether the explosion-proof grade and sheath material match the low-temperature medium environment of the air separation equipment, and at the same time confirm the power margin under reduced-voltage operating conditions. O&M records should include the voltage tap position and measured surface temperature for each melting operation, to facilitate subsequent judgment of the heating tube condition.
