Mechanical drain valve-1

Release time:

2024-03-29

Use and classification of drain valve When the steam used as the heat medium in the steam heating system is cooled in the process of pipeline transportation, condensate will be produced. Generally, these condensed water should be discharged from the heating equipment as soon as possible to ensure the heat transfer efficiency of the equipment. If condensed water accumulates in the pipe network, it will hinder the steam flow and increase the steam humidity, which will inevitably affect the heat exchange efficiency; moreover, it may cause water hammer and damage the pipeline valves. The steam trap is a kind of equipment which can automatically and rapidly discharge the condensed water in the steam heating equipment and system pipe network, and prevent the steam from discharging with the water. Therefore, the steam trap is also called the steam trap drain valve. The traps are mainly divided into three categories: mechanical type, thermal dynamic type and thermal static type.

(1) the mechanical type uses the change of condensate liquid level to cause the movement of floating elements and open and close the valve. According to the structure of the float, it can be divided into three types: bucket type, floating ball type and free semi floating ball type.

(2) according to the movement speed of steam condensate, the thermal power type uses the density difference and viscosity coefficient difference of steam and condensate to directly open and close the valve disc. It is divided into disc type and pulse type.

(3) thermal static type, which uses the temperature difference between steam and condensate to drive components to open and close the valve disc. According to the expansion elements, it can be divided into bellows type, bimetal type, film box type and temperature control type.

The classification of traps is as follows.

Mechanical type: bucket type, floating ball type, free semi floating ball type.

Thermal power type: disc type, pulse type.

Thermal static type: bellows type, bimetal type, film box type, temperature control type.

Mechanical drain valve

Mechanical drain valve uses float to open and close valve disc.

Bucket drain valve

Bucket type drain valve. The bucket is lifted on the top cover of the drain valve with the help of a lever and a pin (lever fulcrum). The cover is equipped with a valve seat for discharging condensate, and the lever is equipped with a valve disc. When the system starts to operate and the air and condensate enter the drain valve, the bucket is obliquely covered at the bottom of the shell due to its own weight, and the valve disc is in the open state, so the condensate is just discharged. A small amount of non condensable air is discharged from the vent hole, and the remaining condensate is accumulated in the lower part of the bucket and the cavity at the lower part of the shell outside the bucket. When the steam enters the drain valve, it will gather at the upper part of the bucket, and the water at the lower part will float the bucket full of steam, and then drive the lever to close the valve to prevent the steam discharge. As long as steam enters into the drain valve and the bucket is full of steam, the drain valve can remain closed.

When the steam stops entering, the steam accumulated in the bucket gradually condenses into water due to the heat dissipation of the shell of the drain valve; a small amount of residual steam is released from the normally open vent hole, the bucket loses its buoyancy and sinks, and the valve is opened. The condensate filled the inner chamber of the shell began to drain out again.