MAN B&W S50ME-B8-TII Project Guide ... - MAN Diesel & Turbo
MAN B&W S50ME-B8-TII Project Guide ... - MAN Diesel & Turbo
MAN B&W S50ME-B8-TII Project Guide ... - MAN Diesel & Turbo
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
<strong>MAN</strong> B&W 7.06<br />
Water In Fuel Emulsification<br />
The emulsification of water into the fuel oil reduces<br />
the NO x emission with about 1% per 1% water<br />
added to the fuel up to about 20% without modification<br />
of the engine fuel injection equipment.<br />
A Water In Fuel emulsion (WIF) mixed for this purpose<br />
and based on Heavy Fuel Oil (HFO) is stable<br />
for a long time, whereas a WIF based on Marine<br />
<strong>Diesel</strong> Oil is only stable for a short period of time<br />
unless an emulsifying agent is applied.<br />
As both the <strong>MAN</strong> B&W two�stroke main engine<br />
and the <strong>MAN</strong> <strong>Diesel</strong> GenSets are designed to run<br />
on emulsified HFO, it can be used for a common<br />
system.<br />
It is supposed below, that both the main engine<br />
and GenSets are running on the same fuel, either<br />
HFO or a homogenised HFO-based WIF.<br />
Special arrangements are available on request for<br />
a more sophisticated system in which the GenSets<br />
can run with or without a homogenised HFObased<br />
WIF, if the main engine is running on that.<br />
Please note that the fuel pump injection capacity<br />
shall be confirmed for the main engine as well as<br />
the GenSets for the selected percentage of water<br />
in the WIF.<br />
Temperature and pressure<br />
When water is added by emulsification, the fuel<br />
viscosity increases. In order to keep the injection<br />
viscosity at 10-15 cSt and still be able to operate<br />
on up to 700 cSt fuel oil, the heating temperature<br />
has to be increased to about 170 °C depending on<br />
the water content.<br />
The higher temperature calls for a higher pressure<br />
to prevent cavitation and steam formation in the<br />
system. The inlet pressure is thus set to 13 bar.<br />
In order to avoid temperature chock when mixing<br />
water into the fuel in the homogeniser, the water<br />
inlet temperature is to be set to 70�90 °C.<br />
Safety system<br />
Page 1 of 2<br />
In case the pressure in the fuel oil line drops, the<br />
water homogenised into the Water In Fuel emulsion<br />
will evaporate, damaging the emulsion and<br />
creating supply problems. This situation is avoided<br />
by installing a third, air driven supply pump,<br />
which keeps the pressure as long as air is left in<br />
the tank ‘S’, see Fig. 7.06.01.<br />
Before the tank ‘S’ is empty, an alarm is given and<br />
the drain valve is opened, which will drain off the<br />
WIF and replace it with HFO or diesel oil from the<br />
service tank.<br />
The drain system is kept at atmospheric pressure,<br />
so the water will evaporate when the hot emulsion<br />
enters the safety tank. The safety tank shall be<br />
designed accordingly.<br />
Impact on the auxiliary systems<br />
Please note that if the engine operates on Water<br />
In Fuel emulsion (WIF), in order to reduce the NO x<br />
emission, the exhaust gas temperature will decrease<br />
due to the reduced air / exhaust gas ratio<br />
and the increased specific heat of the exhaust gas.<br />
Depending on the water content, this will have an<br />
impact on the calculation and design of the following<br />
items:<br />
• Freshwater generators<br />
• Energy for production of freshwater<br />
• Jacket water system<br />
• Waste heat recovery system<br />
• Exhaust gas boiler<br />
• Storage tank for freshwater<br />
For further information about emulsification of water<br />
into the fuel and use of Water In Fuel emulsion<br />
(WIF), please refer to our publication titled:<br />
Exhaust Gas Emission Control Today and<br />
Tomorrow<br />
The publication is available at: www.mandiesel.com<br />
under ‘Quicklinks’ → ‘Technical Papers<br />
<strong>MAN</strong> B&W MC/MC-C, ME/ME-C/ME-GI/ME-B engines 198 38 82�8.3<br />
<strong>MAN</strong> <strong>Diesel</strong>