Air vent apparatus for water tube

1. An air vent apparatus for a water tube, comprising:

an air separator pipe installed to have an axial direction along a vertical direction, and connected to a portion, where an air reservoir tends to occur, of the water tube for passage of water;

an air vent pump capable of venting air accumulating in the air separator pipe;

air amount detection means for detecting an air amount of the air accumulating in the air separator pipe; and

control means for actuating the air vent pump when the air amount detected by the air amount detection means exceeds a set air amount which has been set beforehand, and for stopping the air vent pump when the air amount detected by the air amount detection means decreases to not more than the set air amount which has been set beforehand.

2. The air vent apparatus for a water tube according to claim 1 , wherein

the water tube is a circulating water tube on a water release side for releasing seawater, which has been discharged from a condenser, into a sea.

3. An air vent apparatus for a water tube, comprising:

an air separator pipe installed to have and axial direction along a vertical direction, and connected to a portion, where an air reservoir tends to occur, of the water tube for passage of water; and

an air vent means for venting air accumulating in the air separator pipe,

wherein when a height of the water tube disposed is once raised, and then lowered, along a flowing direction of water, the air separator pipe is connected to a portion of the water tube where the height of the water tube begins to be lowered,

wherein the water tube includes a raised portion where the height of the water tube is raised and a lowered portion where the height of the water tube begins to be lowered, and

wherein the water tube includes a substantially straight and horizontal tube portion between the raised portion and the lowered portion.