Overview of the water seal

1. Working principle and overview of water seal



Water seal refers to the water column with a certain height in the device to prevent the gas in the system from entering the device.

The water seal is a measure to use a certain height of hydrostatic pressure to resist the change of air pressure in the drain pipe and prevent the gas in the pipe from entering the room. Water seals are usually implemented in traps, located under the drains of sanitary ware. Commonly used tubular traps are P-shaped and S-shaped. The water seal height h is related to the change of air pressure in the pipe, water evaporation rate, water loss, content of impurities in water and specific gravity. It should not be too large or too small. If the height of the water seal is too high, solid impurities in the water will easily deposit at the bottom of the trap and block the pipeline; but if the height of the water seal is too small, the gas in the pipe will easily overcome the hydrostatic pressure of the water seal and enter the room, polluting the environment.



2. Multi-stage water seals commonly used in power plants and their working principles



Water seals generally appear in the form of multi-stage water seals in power plants, and are mainly used for vapor-liquid two-phase flow water level adjustment devices for high and low heaters, sealing devices for water drainage and steam leakage of shaft seal heaters, water seal cylinders, and deaerators. The water seal device and so on.



Brief introduction of water seal:



1. Shaft plus multi-stage water seal

The function of the multi-stage water seal: maintain the water level of the shaft plus hydrophobic, and protect the vacuum. In theory, the shaft seal heater drains after passing through the multi-stage water seal and then returns to the steam side of the condenser at a certain height. Once in the multi-stage water seal After the water is filled, its water level basically remains unchanged. The multi-stage water seal is to increase the resistance of the hydrophobic return water. The flow resistance plus the height difference is just equal to the vacuum of the condenser. At this time, it is the most normal working condition, but in fact the working conditions are often changing, and the vacuum of the condenser is also It is also not static, so multi-stage water seals are generally easy to cause two results, one is poor water return (when the flow resistance is large), and the other is vacuum leakage (small return water resistance). Multi-stage water seals are not only Water cannot pass through steam, the vacuum of the condenser is too high, and the return water will be emptied, and air will naturally enter and the vacuum will naturally fall.