What is purpose of Crude Oil Washing?
Crude oil washing (COW) is a system whereby oil tanks on a tanker are cleaned out between voyages not with water, but with crude oil – the cargo itself. The solvent action of the crude oil makes the cleaning process far more effective than when water is used.
How is Crude Oil Washing?
Crude oil washing (COW) is washing out the residue from the oil tanker using the crude oil cargo itself, after the cargo tanks have been emptied. Crude oil is pumped back and preheated in the slop tanks, then sprayed back via high pressure nozzles in the cargo tanks onto the walls of the tank.
What are the disadvantages of Crude Oil Washing?
Disadvantages of crude oil washing
- It does not eliminate completely the need to clean tanks with salt water whether it be for clean ballast or for entering a repair yard.
- The ship’s pipelines cannot be gas freed.
What are the precautions for Crude Oil Washing?
Precautions to be taken while Crude Oil Washing:
- Commencing washing with large accumulations of oil remaining in the tank.
- Adding chemical agents to the tank washing water.
- Recirculating tank washing water.
- Washing large cargo tanks (greater that 10,000 cubic meters).
What is dirty ballast?
Dirty ballast is water which may contain residual fuel and other constituents as a result of sea water being stored in fuel tanks. Dirty ballast is discharged to the environment after being processed through OCMs and/or OWS systems that ensure the ballast water fuel/oil concentrations are below Federal standards.
Which gas is generated during crude oil washing?
Confirming Atmosphere in Tanks to be Crude Oil Washed produces inert gas with an oxygen content of less than 5%. For Prevention of Electrostatic Generation Do not use crude oil containing water, as washing oil.
What are the advantages of crude oil?
Advantages of Oil Energy
- Oil has High Energy Density.
- Oil is Easily Available.
- Oil is Used in a Variety of Industries.
- Oil is a Constant Power Source.
- Emission of Greenhouse Gases.
- Water Pollution.
- Oil Refining Produces Highly Toxic Substances.
What should an oil tanker with crude oil washing be provided with?
1 Every oil tanker operating with crude oil washing systems shall be provided with an Operations and Equipment Manual* detailing the system and equipment and specifying operational procedures.
Why is nitrogen used for purging?
Why Is Nitrogen Used for Purging? Nitrogen is dry and non-combustible, and the nitrogen displacement of combustible gases will prevent an unstable and potentially ignitable atmosphere.
What do ships use for ballast?
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide stability for a vessel. Using water in a tank provides easier weight adjustment than the stone or iron ballast used in older vessels.
What did sailing ships use for ballast?
Wooden sailing vessels were inherently buoyant, and tall masts made them extremely top-heavy. Ballast stones were added or removed as the weight of cargo, supplies, or ordnance changed. Anchors and extra cannon were also sometimes used as ballast.
What are the requirements for crude oil washing?
Requirements for crude oil washing. The ship should be fitted with an inert gas system and the ability to control and limit the amount of oxygen in the cargo tanks (An upper limit of maximum 8% is permissible). All the cargo tanks should be fitted with fixed tank washing machines which may be mounted on deck or inside the tank (submerged machines).
What happens when you wash a crude oil tank?
Crude oil washing will produce electrostatic charging in the cargo tank. Water washing of a tank which has not been adequately drained may also cause charge accumulation. Use of conductive ullage tapes to measure tank bottoms during tank washing.
What are the advantages of crude oil washing?
Advantages of crude oil washing. Chances of pollution are reduced because: Dirty ballast carried in a tank after COW will have much less oil and oily sediments. Less wash water is required to clean tanks for ‘clean ballast’ or for man entry purpose. Routine water washing of tanks for sludge control is largely eliminated.
Can a crude oil wash be carried out without inert gas?
Under no circumstances are Crude Oil Washing operations to be commenced without operational inert gas equipment. Any Butterworth tank washing water heaters fitted must be blanked off and drained at all times. Before each Crude Oil Washing operation a full pressure test of the system must be carried out.