Bilge system
Purpose of bilge water system
Bilge water is the liquid (mainly water or water
containing a small amount of oil) that often accumulates in the hull of a ship
during its operation.
The main sources of bilge water are:
(1) the main engine, auxiliary machinery, equipment and
pipeline joints due to sealing failure leakage of oil or water;
Leakage of oil and water for stern tube seal;
(3) the discharge of bilge water from the rudder engine
room to the engine room or shaft tunnel;
In addition, the discharge of condensate from air
compressor, air bottle, steam distribution valve group and pipeline drainage;
5. The condensate of air conditioning pipelines, air pipes
and steel bulkheads and pipe walls;
6 cleaning filter, equipment parts and other washing
water;
7.Drainage of bilges and decks near the waterline;
8. Being put out a fire in the fire water, deck flushing
water;
9. 'levies for some special cabin of pouring water in case
of an emergency;
10. through non-watertight parts
infiltration of rainwater, etc.
The system used to remove bilge water is called bilge
system. It is important to protect the ship system, it is not only required in
the normal ship During navigation, the bilge water generated in the watertight
cabin is effectively removed, and in case of emergency of hull damage, the
entry
Water tanks can also drain effectively with limited
intake. Therefore, bilge system is the system to ensure the safety of shipping.
Principle of bilge water system
FIG. 3.1.1 shows the bottom water system of a bulk cargo
(schematic diagram).There are three sewage Wells and one position in the engine
room
At the rear of the engine room, two at the starboard and
starboard of the front of the engine room;Generally, there is a pit under the
main engine
To install sewage Wells, or not
Generally, there is a pit under the main engine
To install sewage Wells, or not Bilge tank is also
provided in the double bottom of the engine room aft.The rear of each
compartment in the hold
The port side also has two sewage Wells
Bilge tank is also provided in the double bottom of the
engine room aft. the rear of each compartment in the hold
There are also two sewage Wells on the port side the bow
chain locker also has a sewage well. Bilge suction pipe ends are provided with
suction.
The entrance automatic
high alarm device is installed in the suction place of bilge water, sewage well
or bilge water tank for easy access open
valve and pump to drain bilge water. Ships that meet the requirements of
unattended engine rooms are often equipped with remote control system of valves
and bilge water
Dynamic discharge facilities.
Valve remote control system and bilge water from
dynamic discharge facilities.
FIG. 3.1.1 schematic diagram of bilge water system
1- oil residue pump;2- fire main pump;3- general bilge
pump;4- bilge oil and water separator;5- bilge suction
-Water absorption to stripping Jet pump
Cargo compartment Bottom
water main system is also equipped with special
bilge pump and combined bilge general pump and fire general pump to prevent
oily sewage discharge to sea water, the engine room is
equipped with bilge oil and water separator.
1. Working principle of the system
Bilge pumps or general pumps can be used to draw sewage
from all sewage Wells.Generally, there are intercepts at both ends of each
bilge pipe
Check valve or check suction inlet to prevent backflow of
bilge water.
During navigation, oily water inhaled through the bilge
pump of the engine room must be discharged to the bilge tank. When the ship
docked, The bilge water is then discharged to a special bilge receiving device
on shore. For outboard discharge, use bilge separator
after leaving, its oil content is less than 15ppm can be
discharged. Bilge water in a cargo tank or a clean oil-free cabin in the engine
room
Bottom water can be pumped through the main pump and
discharged directly overboard.
In addition to the normal sailing condition, the ship
should remove the cargo hold, the engine room, especially the bilge water in
the engine room.
In order to rapidly drain watertight compartments with
limited water intake in the event of damage to the vessel, the code requires
the installation of a bilge emergency suction pipe at the sea pump suction pipe
with maximum engine room capacity
2. Layout principle of bilge pump
Because of the variety of ships, each ship has different
bilge systems. But the pipeline and the water pump layout all have certain
Principles can be followed. There are three principles for
the layout of bilge pump:
This system of arrangement applies to ships with several
engine rooms, boiler rooms, and other cabins.
And each cabin must maintain its working independence. As
shown in figure 3.1.2, each tank has its own bilge pump and system.
It has the advantage of ensuring the independence of each
section of the system. It can prevent pipes from passing through the watertight
bulkhead; Installation of pipeline equipment is simplified.
It is mainly applicable to military ships. First, military
ships are equipped with engine room, front auxiliary engine room and rear
auxiliary engine room. Second, it requires each cabin alone
Strong standing. Third, the pipeline is simple, convenient
maintenance, light weight.
Transverse section figure
FIG. 3.1.2 bilge system arranged according to the
principle of independence
Suction strainer;2- injector;3- stop to return valve;4-
stop valve;5- collecting well;6- water line of jet pump work
The floor plan
To the outboard
2) piping for bilge system of the fore and aft tanks,
To the respective bilge pumps in the engine room, or bilge
piping in the engine room, port and starboard piping in the cargo hold
Connect to the respective bilge pumps in the engine room
and operate in the engine room.Figure 3.1.3 shows the separation before and
after.
In order to reduce the equipment in the engine room and
facilitate the operation, bilge pumps on the actual ship can be used in reserve
with each other, as shown in figure 3.1.3
The layout shown does not exist. The suction manifold of
the two pumps is connected but the valves are isolated from each other.
Main equipment and accessories
1. Bilge pump
equipment that can be used as bilge pumps in ships
includes jet pumps, centrifugal pumps, piston pumps and axial flows
pump. The centrifugal pump is often used for bilge pump or fire
fighting because of its large displacement, low requirement for water quality
and low price. It also usually be used as main
pump, bilge main pump or fire main pump. Since the piston pump can produce a
high vacuum degree, it has a strong suction capacity, and it is not easy to
crush the oil droplets floating on the surface of the water and mix with the
water, increasing the difficulty of separation, so it is widely used for high
vacuum degree.
Increase the difficulty of separation, so it is widely
used for special bilge pumps. Axial flow pumps are rarely used as bilge pumps,
General bilge water contains impurities, easy to cause
screw wear. Axial flow pump is used as bilge pump on ship
For single screw (snake) pump. The structure of the jet
pump has no moving parts, its power is high pressure liquid, no prime mover. So
It is simple in structure and small in size. It is widely used
in bilge water system. The spray bilge pump consists of three parts: nozzle,
mixing chamber and diffuser pipe. Jet pumps work by using high pressure water
as the power to draw and discharge liquid. The working water from the fire
fighting system is ejected at a high speed after passing through nozzle 1, and
it takes away the air around the nozzle to produce a certain vacuum, which
makes the bilge water press into mixing from the suction inlet
In room 2.Working water and bilge water are constantly
colliding and mixing in the mixing chamber to exchange momentum. Mix it up enter
the diffuser tube with gradually expanding cross-sectional area 3, the mixed
water in the diffuser tube gradually reduces the speed, and the static pressure
gradually increases, so as to pump out
The liquid builds up the pressure head to achieve the purpose
of discharging the liquid.
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