This section is available on request - MAN Diesel & Turbo

MAN B&W
B.O.G.
�40 to �140°C
1.08 to 1.20 bar (a)
M.C.W. 36°C
Hx
M
EEx
VSD Recycle
Hx
M
EEX
VSD Recycle
Hx
M
EEX
VSD Recycle
Gas supply system � capacity management
The minimum requirement for the regulation of
supply to the ME�GI engine <strong>is</strong> a turndown ratio of
3.33 which equals a regulation down to 30% of
the maximum flow (For a twin engine system, the
TR <strong>is</strong> 6.66). Alternatively in accordance with the
requirements of the ship owners
Both the LP and HP compressor packages have 0
=> 100% capacity variation systems, which allows
enormous flexibility and control.
Stable control of cargo tank pressure <strong>is</strong> the
primary function of the LP compressor control
system. Dynamic capacity variation <strong>is</strong> achieved
by a combination of compressor speed variation
and gas d<strong>is</strong>charge to recycle. The system <strong>is</strong> responsible
for maintaining the BOG pressure set
tank pressure point within the range of 1,06 � 1,20
bar(a) through 0 => 100% compressor capacity.
At full load of the ME�GI engine on gas, the HP
compressor delivers approximately 265 bar
Hx
Hx
Hx
Optional
3rd unit
40 to 50°C
3.0 to 5.0 bar (a)
MAN Diesel
7.09
Page 3 of 7
whereas at 50% load, the pressure <strong>is</strong> reduced to
130�180 bar. The d<strong>is</strong>charge pressure set points
are controlled within ±5%. Compressor speed
variation controls the capacity range of approximately
100 => 50% of volumetric flow. Speed
control <strong>is</strong> the primary variation; speed control
logic <strong>is</strong> integrated with recycle to reduce speed/
capacity when the system <strong>is</strong> recycling under
standby (0% capacity) or part load conditions.
LP & HP compressor systems are coordinated
such that BOG pressure <strong>is</strong> safely controlled,
whilst however delivering all <strong>available</strong> gas at the
correct pressure to the ME�GI engine. Load and
availability signals are exchanged between compressor
and engine control systems for th<strong>is</strong> purpose.
MAN B&W ME�GI engines ME�GI engines 198 48 85�8.4
M
EEx
VSD
Recycle
Fig. 7.09.03: Gas compressor system � indicating capacity control and cooling systems
Hx
Water out
To GSU
Supply to
ME�GI
150�265 bar (a)
45°C
178 53 69�4.0