869569271

Paweł Chorab

-    degree of openness of throttling valves,

-    level of liąuid in a tank.

Among others, system failures may be as fol-lows:

-    strainer blockage at bottom valves,

-    overheating of ballast pumps,

-    freezing of ballast water,

-    failures of valves and their opening-closing hydraulic system.

Fig. 3. E\amplcs of dialog Windows of the ballast water system elements [7]

Rys. 3. Przykładowe okna dialogowe elementów systemu instalacji balastowej. [7]

Research problems - applicability of the Simulator in establishing the sequence of ballast water exchange

The main function of the abovc ballast module is simulating the operation of the ballast installation on a given ship. Besides, the module can be used to determine the seąuence of emptying and reftlling ballast tanks. By simulating emptying / reftlling of one or morę ballast tanks the users can observe and analyze changes in these operational parameters:

-    displacement D [t],

-    mean draft T& [m],

-    draft aft T_R [m],

-    draft forward To [m],

-    trim I [m],

-    initial metacentric height GM [m],

-    righting lever GZ [m]

-    free surface correction AGM [m],

-    value of max. shear force occurring in ship’s hull SFmax,

-    value of max. bending moment occurring in ship’s hull BMmax,

-    value of blind sector ahead of ships bow S [m],

-    value of heeling angle tp [°],

-    others.

Every ship should carry a Ballast Water Management Plan, containing the complete procedurę of ballast water exchange described through subseąuent steps of the exchange operation. It is mandatory to indicate a/m operational parameters values for each step and compare them with crite-rial values. There are factors, however, that may complicate the establishment of a correct seąuence

-    the order of emptying and reftlling of ballast tanks:

-    a large numberof ballast tanks in a ship.

-    substantial volume of ballast water,

-    ballast pums unfit for continuous operation that may takc morę than a day,

-    long time of emptying and reftlling particular ballast tanks,

-    difficulties in determining such seąuence of operations that will not worsen one parameter at the expense of another parameter (e.g. relation between draft forward To and draft aft T_R).

For the preset seąuence of tank empty ing and re-ftlling the ballast module offers the capability of monitoring of:

-    changes in operational parameters (draft, list etc.) in real time,

-    changes in stability parameters (e.g. initial metacentric height) in real time,

-    stresses in the ship s hull (shear force, bending moment),

-    values of the blind sector ahead of the ship's bow,

-    technical parameters of ballast pumps (pres-sure),

-    others.

Besides, it is also possible to modify the estab-lished procedurę of ballast water exchange; each change, e.g., of the seąuence, may be simulated to obtain the results of such parametric changes.

The balast module can be further exploitcd to prepare guidelines for the master of the ship where ballast water exchange operations will be per-formed:

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Scientific Journals 25(97)