The deck water seal offers a positive break in the system by means of a water trap. This permits inert gas to be delivered to the main deck while preventing gas back flow, even when the IGS is shut down. The regulations require two independent water supplies for the deck water seal. When the IGS is operating, the scrubber pump supply is used; the second supply, normally the salt-water service pump, is used when the IGS is not operating. Each pump must be capable of operation at all times. The deck water seal is provided with a heater to prevent the water from freezing and an automatic control system that prevents overheating of the seal
(1) The wet seal is described in Figure.
It is deemed the most reliable and is the only type generally approved for use on most vessels.
(1) The wet seal is described in Figure.
It is deemed the most reliable and is the only type generally approved for use on most vessels.
(2) The Semi-dry seal operates dry after the IG flow displaces the water. Venturi action returns the water when a gas block is needed as described in Figure.
(3) The Dry seal operates normally dry and is filled with water when the IG plant is shut down or when tank pressure exceeds the IG pressure.
In the dry type seal, the water is drained from the seal when the IG plant is in operation (gas flowing to the tanks), and filled with water when the IG plant is either shut down, or the tank pressure exceeds the IG blower discharge pressure. Filling and drainage are performed by automatically operated valves controlled by the levels in the water seal and the drop tank, and by the operating state of the blowers
0 comments:
Post a Comment