Operation
9270−1/A1
Winterthur Gas & Diesel Ltd.
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Table 1: SCR System Valves Data
Valve No. Name Function
V1
(CV7821C)
SCR reactor inlet valve
Usually open
Lets the exhaust gas go into the the SCR reactor.
The positioner (XI7831C) transmits the position feedback
signal of the valve V1.
V2
(CV7822C)
SCR reactor outlet valve
Usually open
Lets the exhaust gas go out of the the SCR reactor.
The positioner (XI7832C) transmits the position feedback
signal of the valve V2.
V3
(CV7823C)
SCR bypass valve
Usually open
Lets the exhaust gas bypass the SCR reactor.
Lets the temperature of the SCR reactor increase
smoothly.
The positioner (XI78333C) transmits the position
feedback signal of the valve V3.
V4
(CV7077C)
Turbocharger bypass valve
Usually closed
Lets the exhaust gas temperature increase at low engine
loads.
The positioner (XI7077C) transmits the position feedback
signal of the valve V4.
Also used for:
Waste heat recovery (WHR)
Low load tuning (LLT)
Delta bypass tuning (DBT)
V7
(CV7827C)
SCR reactor pressure relief
valve
Usually open
Controls the air flow from the sealing/venting in SCR
bypass mode (if applicable).
Additionally, it can be used to prevent internal
overpressure of the SCR.
The positioner (XI7837C) transmits the position feedback
signal of the valve V7.
This configuration lets you satisfactorily operate the SCR system at the selected
mode.
Table 2: Operational Limits
SCR Operation Mode T
Minimum
Exhaust
Gas
T
Maximum
Exhaust
Gas
Marine Diesel Oil and urea injection
300° 470°
Note: The values given in Table 2 can change.
CAUTION
Damage Hazard. The SCR is designed to operate with Marine Gas
Oil (maximum sulphur content of 0.1%). Do not operate the engine
with fuels that have a high sulphur content. Damage the the SCR
will occur.
The exhaust gas mass flow can go through the SCR reactor until the exhaust gas is
at the maximum temperature. Temperatures of exhaust gas mass flow above the
maximum limit can cause the catalyst elements to become worn.
For urea injection, keep a minimum temperature to prevent clogging of the SCR
reactor. Ammonium bisulphates can occur. For more data, refer to the documentation
of the SCR supplier.
2016−11
Selective Catalytic Reduction System
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