Fuel System and Fuel Measurement - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 70

MDO
emergency

MDO
transfer fump

sample
point

counter

MDO
store

join
user

IFO transfer pump1

IFO
store 1

settling
tank 1

IFO transfer pu mp2

IFO
store 2

settling
tank 2

overrun

Fig. 4.9 Multistage fuel system on a ship

flow into tanks in the engine space. A part of the water and mud is already separated
from the fuel in settling tanks which are heated to a temperature of approximately
70C (158F). Water and mud are regularly pumped into mud tanks [ 43 ].
Fuel is processed by separating and filtering. Oil synchronous separators are
centrifuges, in which a geared wing pump thrusts the oil through a high-grade steel
plate stack, turning at 12,000 rpm. The conically formed plates are equipped with
separation channels. The purer and lighter oil substances flow into these channels
and the heavy components, like water and dirt, are forced outside and are collected
in a special waste container [ 44 ].
To optimally separate fuel, heat exchangers are in front of the synchronous
separators. Their temperature is 70-99C (158-210F) depending on the fuel
density. For heavy marine fuel oils with many pollutants, the separators are
connected in series. The fuel filters in the marine technology are reversible flow
filters. In separate modules, the HFO and IFO fuels are heated to the right injection
viscosity of approximately 12 cSt at 130C (266F) at a pressure of about
(7-10) 9 10 5 Pa, i.e., 102-145 psi or 14,620-20,885 lbf ft -2 [ 45 ].
Heavy marine fuels with high viscosity are pumped into a collection tank at a
pressure of around (6-8) 9 10 5 Pa, i.e., 87-116 psi or 12,531-16,708 lbf ft -2 . The
modern type of injection is the Common Rail technology with a pressure of (200-
300) 9 10 5 Pa, i.e., 2,901-4,352 psi or 417,711-626,566 lbf ft -2 . Common Rail
technology is now mass produced by all marine diesel engine manufacturers [ 46 ].
Figure 4.9 shows the plan of a ship's fuel preparation and supply system
containing tanks for MDO and IFO fuels, transfer pumps, setting tanks, a sample
point, a counter, and a joint user [ 47 ].