Leak in the mechanical seal of the reformed xylene bottom pump

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Current operating conditions of the mechanical seal for pump P605 in the reprocessing workshop: Pump identifier: P-605AB (reboiler pump at the bottom of the xylene tower). Medium temperature: 330°C. Inlet pressure: 0.395 MPa; outlet pressure: 1.35 MPa. Flushing scheme: Plan21+52. Buffer fluid: white oil. Rotational speed: 1490 RPM. Mechanical seal type: Dandong Klon series, double-corded mechanical seal; model: JBB131.125//JBB131.125. The medium transported by this pump consists of C9 + fractions. Density: Kg/m3 (value varies as needed). SN605 heavy aromatics: density ranges from 900 to 1008. Boiling range: initial boiling point = 227.0°C; 10% distillate – 231.0°C; 50% distillate – 244.0°C; 90% distillate – 338.0°C; 95% distillate – 350.0°C. Final boiling point ≤ 220°C. Recycled volume: // Original design parameters: file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml28776/wps1.jpg. Operating problems: The temperature of the primary flushing medium for the mechanical seal is too high, and its composition is too heavy, resulting in coking and blockages at the orifice plate. After passing through the heat exchanger, the temperature drops to 85°C, but once it enters the mechanical seal chamber, the temperature rises above 85°C, even higher. This causes the thermal expansion coefficients of the moving ring seat (made of alloy) and the moving ring sealing surface (made of silicon carbide) to differ, leading to separation between them and relative movement, which ultimately results in failure of the primary seal. The mechanical seal manufacturer needs to select or design a suitable type of mechanical seal based on the current operating conditions of the pump, in order to ensure its normal and stable operation.