WÄRTSILÄ WARTSILA 26, Руководство по эксплуатации продукта

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9.3.6 Fresh water central cooler (4E08)
The fresh water cooler can be of either plate, tube or box cooler type. Plate coolers are most
common. Several engines can share the same cooler.
It can be necessary to compensate a high flow resistance in the circuit with a smaller pressure
drop over the central cooler.
The flow to the fresh water cooler must be calculated case by case based on how the circuit
is designed.
As an alternative for the central coolers of the plate or of the tube type a box cooler can be
installed. The principle of box cooling is very simple. Cooling water is forced through a
U-tube-bundle, which is placed in a sea-chest having inlet- and outlet-grids. Cooling effect
is reached by natural circulation of the surrounding water. The outboard water is warmed up
and rises by its lower density, thus causing a natural upward circulation flow which removes
the heat.
Box cooling has the advantage that no raw water system is needed, and box coolers are less
sensitive for fouling and therefor well suited for shallow or muddy waters.
9.3.7 Waste heat recovery
The waste heat in the HT cooling water can be used for fresh water production, central heating,
tank heating etc. The system should in such case be provided with a temperature control
valve to avoid unnecessary cooling, as shown in the example diagrams. With this arrangement
the HT water flow through the heat recovery can be increased.
The heat available from HT cooling water is affected by ambient conditions. It should also be
taken into account that the recoverable heat is reduced by circulation to the expansion tank,
radiation from piping and leakages in temperature control valves.
9.3.8 Air venting
Air may be entrained in the system after an overhaul, or a leak may continuously add air or
gas into the system. The engine is equipped with vent pipes to evacuate air from the cooling
water circuits. The vent pipes should be drawn separately to the expansion tank from each
connection on the engine, except for the vent pipes from the charge air cooler on V-engines,
which may be connected to the corresponding line on the opposite cylinder bank.
Venting pipes to the expansion tank are to be installed at all high points in the piping system,
where air or gas can accumulate.
The vent pipes must be continuously rising.
Wärtsilä 26 Product Guide - a9 - 7 September 2016 9-11
9. Cooling Water System Wärtsilä 26 Product Guide