Our system involves very simple filtration technique; to meet the IMO D-2 standards by filtering sea water to less than 10 microns using the already existing ballast water system on board and using water dynamics to its best advantage.
PRACTICAL AND COST EFFECTIVE SOLUTION
IN MANAGING BALLAST WATER
(A SEA FARING TECHNIQUE)
A typical example of a double hull V.L.C.C. tanker DWT= 300,000.0 metric tons, where pair of Dedicated Side Wing Tanks and Double Bottom Tanks forward of pumproom are chosen. These tanks are interconnected providing a good water head of 30.0 metres. Inside the wing tank at a top level a fibre glass floating tank of sufficient capacity is built inside to act as a filter bed of low density filtering medium (1st stage filtration). During ballasting, sea water passes through the sea chest, via the ballast pump and enters the filter bed from top via a suitably modified pipeline. Filtered water less than 100 microns rating is collected as captive storage, right within the double bottom and wing tanks. The ballasting operation is commenced immediately as the vessel berths alongside, taking advantage of minimum 2 to 3 hours before the cargo discharge operation begins. This filtered water with a pressure head of 30 mtrs; drives the filter turbine by gravity in the pumproom (2nd stage filtration). In this filter turbine are mounted series of revolving sandwich disc which contains toughened filters of very fine wire meshes of non corrosive material.
On the face of these each revolving disc is a suction scanner, driven by eductor system which is already an integral part of the ballast system for stripping ballast tanks. The suction scanner continuously removes all the clogged particles from the face of filter disc and sends it back again to the filter bed. From the outlet of turbine filter, water of less than 10 microns is disinfected through the U.V. Reactor by the same gravity force and distributed to the other ballast tanks as filtered and treated water. During D'ballasting operation, water is again disinfected by passing only through the U.V. Reactor.
V.L.C.C. TANKER DWT = 300,000.0 METRIC TONS
Flushing of the filter bed is periodically done by keeping check on the supply and demand of filtered water in the storage tanks, without any stoppage / interruptions in the ballasting operations; as the whole process of ballast distribution to other tanks is done under gravity.
Experiments conducted on small scale; gave good results, as the filter turbine outlet water flow remained unrestricted due to continuous cleaning of clogged filters by the educting system.
The presentation will give a total overview and insight of actual Ballast operations conducted on board ships; and also provide practical, economical and feasible options from the ship owners point of view.
(A TRULY SEA FARING EXPERINCE)