1. The poor welding quality of the pipe system of the mechanical seal device seriously affects the safety of the feed pump

The mechanical seal liquid temperature of the feed pump is designed to alarm at 80 ℃ and trip at 90 ℃. When the slight leakage of the pipeline system causes the temperature of the mechanical seal fluid to rise slowly (because the mechanical seal fluid through the heat exchanger decreases, or the mechanical seal fluid cannot be cooled well), when the serious leakage of the pipeline system causes the temperature of the mechanical seal fluid to rise sharply. All these make the dynamic ring, static ring and bonding surface of the mechanical seal not cool well, and the dynamic ring and static ring are damaged due to overheating. During operation, the feed pump tripped due to leakage of mechanical seal pipe system for many times, which also aggravated the wear of mechanical seal. Therefore, higher requirements are put forward for the welding quality of the pipe system of the mechanical seal device.

2. The influence of feedwater quality on mechanical sealing device.

As the mechanical seal device has high requirements for water quality, when the water quality deteriorates, the mechanical seal device is easily blocked due to the thin circulating pipe system of the mechanical seal device, causing the temperature of the mechanical seal fluid to rise; When the feed pump operates at low speed and the water quality deteriorates, the impurities cannot be taken away by the water in time due to the low lifting pressure of the reverse spiral groove, which causes the impurities to deposit on the mechanical seal and scratch the binding surface of the dynamic and static rings of the mechanical seal, causing the mechanical seal to leak. Therefore, it is necessary to strengthen the water quality supervision of unit startup and shutdown and normal operation.

3. Influence of operation mode on mechanical seal device.

(1) When the unit is under regular load adjustment, the feedwater pump is in a variable working condition or the feedwater pump is often in a startup and shutdown state, resulting in the instantaneous displacement of the pump shaft of the feedwater pump, making the bonding surface clearance between the dynamic and static rings of the feedwater pump too small to form a flow film, causing dry friction between the dynamic and static rings and damaging the mechanical seal device. The thrust bearing of the feed pump was worn due to the balance destruction of the pump unit itself, which led to the leakage of the mechanical seal device. Therefore, the pump set shall be adjusted as far as possible during operation. Protect the mechanical seal from damage.