Bulk Carrier Cargo Bay Drainage Systems

In order to protect the safety of bulk carriers and prevent marine environmental pollution, it is necessary to pay attention to the inspection of the cargo tank water system, so as to ensure the smooth navigation of bulk carriers. This paper introduces the hazards and working principle of blockage of cargo tank drainage system of bulk carriers.

What are the hazards of clogged cargo tank drainage systems on bulk carriers?

1. It will cause water to accumulate in the cargo hold of the bulk carrier, and the residual cargo, chemical composition and other sundries in the water will cause corrosion to the bilge of the bulk carrier, which will bring potential danger to the safety of the hull.

2. Water in the cargo hold can combine with the cargo to adversely affect the quality of the cargo being transported, causing damage to the cargo, and may even react chemically with the cargo to cause significant damage.

3. When the bilge water accumulates too much, it may form easy-flowing state with the cargo, and the liquefaction of the cargo surface leads to the phenomenon of cargo flow, which seriously affects the stability of the ship when the bulk carrier is swaying, and leads to the ship's left and right tilting, and too large a difference between the fore and aft draught, which jeopardizes the navigational safety.

Bulk Carrier cargo bay Drainage Systems cognition and how it works

Bulk carrier cargo tank drainage system mainly consists of cargo tank sewage wells, filters, pipelines, valves, jet pumps and part of the piping system from the nacelle.

1. Bulk carrier cargo hold sewage well is a small container for temporary placement of cargo hold sewage, equipped with a sewage well cover to block cargo, sewage wells are generally set up in the two corners of the cargo hold near the stern of the ship, the water retained in the cargo will gradually accumulate, through the sewage well cover, flowing into the sewage well. When the level of the sewage well is at a high level, the sewage well jet pump can be primed by starting the engine room bilge pump to remove the accumulated sewage. Some ships are equipped with a sewage well high level alarm device, which will trigger an alarm when the sewage well level reaches a certain height.

2. The role of the filter is to filter the impurities in the sewage, the entire cargo hold drainage system pipe system to prevent clogging, but also to prevent impurities from entering the jet pump, affecting the rate of drainage, generally set in the bottom of the sewage well.

3. Valve is an essential part of the entire system, respectively, set up in front of and behind the jet pump, the valve before the pump is near the location of the sewage well, the jet pump and the pump after the valve is generally set up in the nacelle, check valves are generally set up in the pipeline near the sewage well drain, is a kind of relying on the pressure of the medium to open and close the automatic valve, whose main role is to prevent the medium from backing up, to avoid the occurrence of cargo damage. The working principle of the check valve is relatively simple, when the medium flows in the right direction, the valve opens normally, when the phenomenon of backflow or the pump stops the state, the valve will fall back quickly, such valves are prone to rust or stuck, and need to be regularly tested and maintained.

4. Jet pump is the most important part of the cargo hold drainage system, is a high-pressure working fluid through the nozzle to produce high-speed jet, in the suction chamber to form a low-pressure to eject the fluid, and with the momentum exchange, so that the ejection of fluid energy to increase, to achieve the purpose of pumping. High-pressure working fluid generally from the cabin bilge pump pumped seawater, ejected fluid from the cargo hold sewage well. Jet pump structure is relatively simple, no moving parts, reliable, less noise, because of its self-absorption ability is strong, commonly used in pumping dirty liquids containing a small amount of solid impurities.

5. When the sewage passes through the jet pump, it will face two choices, if it is environmentally hazardous solid bulk cargo, after the ship discharges the cargo, the residue of the cargo and its wash water should be received by the port reception facility or the ship's pollutant acceptance unit, prohibited from entering the sea, and according to the provisions of the garbage record book truthfully recorded. In the case of general cargo, the wash water can be discharged directly into the sea, but it needs to meet the distance of 12 nautical miles from the nearest land.

Conclude

In short, before loading, the bulk carrier cargo hold drainage system needs to be tested to check whether it is clogged, check whether the cargo hold drainage pump is in normal working condition, check whether the pipeline valves are smooth, and make a good record; before loading, the proposed cargo should be loaded with moisture content testing to ensure that the moisture content of the cargo is lower than the moisture limit of the shipment; in the case of inclement weather, even if it is to stop the operation, the emergency closure of hatch cover, to prevent rainwater from entering the hold. Prevent rainwater from entering the cargo hold.

The importance of bulk carrier cargo hold drainage system, pay attention to and strengthen the regular maintenance of bulk carrier cargo hold, and actively take preventive measures to protect the ship and crew navigation safety.