WinGD X72 - SCR; VCS Operation − Scavenge Air Pressure too High (Tier II)

Operation9270−1/A1
Winterthur Gas & Diesel Ltd.
10/ 28
2.5 SCR / VCS Operation − Scavenge Air Pressure Too High (Tier II)
The heat capacity of the SCR reactor can cause high scavenge air pressure during a
fast load decrease of the engine. If the scavenge air pressure is too high, valve V3 is
opened to let the the exhaust mass flow bypass the hot SCR reactor, see Fig. 7.
The valve V4 can be opened to let the inlet air mass flow to the engine decrease. As
an option, the exhaust mass flow through the turbine is decreased and subsequently
the compressor speed.
The valves V1 and V2 stay open. The valves V4 ans V7 stay closed.
Engine
V1
V2
V3
V7
V4
Turbocharger
SCR Reactor
Air pipes − flow
Exhaust pipes − no flow
Exhaust pipes − flow
WCH03725
Fig. 7: SCR/VCS Operation − Scavenge Air Pressure Too High
2016−11
Selective Catalytic Reduction System