Crude oil washing (COW) is rinsing the residue from the
storage tanks of an oil tanker using the crude oil cargo itself, after the
cargo storage tanks have been cleared. Crude oil is pumped back and preheated
in the slop tanks, then sprayed back through high tension nozzles in the
freight storage tanks onto the walls of the tank. Due to the sticky nature of
the crude oil, the oil hold on to the storage tank wall surfaces, and such oil
adds to the cargo 'Remaining on board' (the ROB). By COW the containers, the
amount of ROB is substantially reduced. With the existing high expense of oil,
the financial savings are substantial, both for the Charterer as well as the
Ship owner. If the cargo ROB is regarded as 'liquid and pumpable' then the
charterers could assert from the owner for any cargo loss. It replaced the lots
on the top and seawater washing systems, both of which involved led releasing
oil-contaminated water right into the sea.
History
Even with load on top there is still some
oil in the released water from the slop tank. Beginning in the 1970s, efficient
tools using crude oil itself for washing started to change the water-based
cleaning, resulting in the existing technique of crude oil cleaning. This
minimizes the remaining deliberate discharge of oil-contaminated water as well
as raises the amount of cargo discharged, supplying an additional benefit to
the cargo proprietor.
Modern vessels likewise use segregated
ballast storage tanks and these eliminate the issue of discharge of oily
ballast water.
Crude oil cleaning (COW) is a system where
oil tanks on a tanker are cleared out between voyages not with water but with
crude oil - the cargo itself. The solvent action of the crude oil makes the
cleansing process far more effective than when water is made use of. (There is
normally a final water rinse but the amount of water involved is reduced.) The
system helps avoid contamination of the seas from operational measures.
Disadvantages with Water Washing
As vessel sizes increased and also much more strict
policies versus oil pollution were applied, it was understood that water
washing alone is an inferior container cleaning approach. WHOLE LOT (Load On Top),
no matter how full and advanced it may be, can never eliminate the great
disadvantages with water cleaning compared to COW:
Longer time for washing each storage tank, leading to
maximized bunker expenses.
Handling bigger quantities of water is expensive and also
induces maximized pollution of the sea given
that the water is
contaminated with oil, even when WHOLE LOT procedures are utilized.
Increased rust as a
result of substantial water washing.
Development of Crude Oil Washing
The introduction of load on top was a good
contribution to the fight versus aquatic pollution but it did not entirely get
rid of contamination arising from storage tank cleaning operations. Although
the quantity as well as rate of discharge is carefully managed, the process
still resulted in some pollution occurring. In the late 1970s an improvement
was presented. Instead of using water, the container cleaning machines relied
on crude oil - in other words, the cargo itself. When shot into the debris
holding on to the storage tank walls, the oil merely liquefied them, turning
them back right into usable oil that can be pumped off with the rest of the
cargo. There was no requirement for slop tanks to be utilized since the process
left virtually no slops. The process ended up being referred to as Crude Oil
Washing (COW). Crude Oil Washing indicated that the mixture of oil and water,
which previously resulted in a lot functional pollution, was practically ended.
At the same time, the proprietor is able to release far more of this cargo than
previously, considering that much less of it is left holding on to the storage
tank wall surfaces and bottoms.
Advantages COW
Since that equipment and
treatments are well adapted for COW, the following advantages are obtained in
contrast with water washing:
Substantial reduction in air
pollution capacity since less oil continues to be aboard after discharge and
also much less oil-contaminated water is handed throughout the ballast passage.
* Reductions in time and price of container cleansing.
* Desludging manually prevented.
* Minimized container cleansing time at sea.
* Boosted out-turn of payload.
* Decreased dead freight as less oil-water slops are kept on board.
* Less seawater discharged to refineries.
* Decreased storage tank rust caused by
water washing.
No comments:
Post a Comment