Wartsila 31 Product Manual page 101

Wärtsilä 31 Product Guide
9.3.2 Stand-by circulation pumps (4P03, 4P05)
Stand-by pumps should be of centrifugal type and electrically driven. Required capacities and
delivery pressures are stated in Technical data.
9.3.3 Temperature control valve for central cooler (4V08)
When it is desired to utilize the engine driven LT-pump for cooling of external equipment, e.g.
a reduction or a generator, there must be a common LT temperature control valve in the
external system, instead of an individual valve for each engine. The common LT temperature
control valve is installed after the central cooler and controls the temperature of the water
before the engine and the external equipment, by partly bypassing the central cooler. The
valve can be either direct acting or electrically actuated.
The set-point of the temperature control valve 4V08 is 38 ºC in the type of system described
above.
Engines operating on HFO must have individual LT temperature control valves. A separate
pump is required for the external equipment in such case, and the set-point of 4V08 can be
lower than 38 ºC if necessary.
9.3.4 Charge air temperature control valve (4V09)
The temperature of the charge air is maintained on desired level with an electrically actuated
temperature control valve in the external LT circuit. The control valve regulates the water flow
through the LT-stage of the charge air cooler according to the measured temperature in the
charge air receiver.
9.3.5 Coolers for other equipment and MDF coolers
The engine driven LT circulating pump can supply cooling water to one or two small coolers
installed in parallel to the engine, for example a MDF cooler or a reduction gear cooler. This
is only possible for engines operating on MDF, because the LT temperature control valve
cannot be built on the engine to control the temperature after the engine. Separate circulating
pumps are required for larger flows.
Design guidelines for the MDF cooler are given in chapter Fuel system.
9.3.6 Fresh water central cooler (4E08)
The flow to the fresh water cooler must be calculated case by case based on how the circuit
is designed.
In case the fresh water central cooler is used for combined LT and HT water flows in a parallel
system the total flow can be calculated with the following formula:
where:
Wärtsilä 31 Product Guide - a1 - 18 October 2016
Some classification societies require that spare pumps are carried onboard even
though the ship has multiple engines. Stand-by pumps can in such case be worth
considering also for this type of application.
q = total fresh water flow [m³/h]
q nominal LT pump capacity[m³/h]
LT =
Φ = heat dissipated to HT water [kW]
NOTE
9. Cooling Water System
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