SCANIA INDUSTRIAL ENGINES (specification) - part 33
SCANIA INDUSTRIAL ENGINES
SCR system
EU Stage IV, US Tier 4f
SCR (Selective Catalytic Reduction) technology is used on Scania’s engines for
EU Stage IV and US Tier 4f to reduce the NO
X
content in the exhaust gases.
A chemical process is started by injecting reductant, an urea and water
mixture, into the exhaust gas stream. During injection the water evaporates
and the urea breaks down to form ammonia. The ammonia then reacts with
the nitrogen gases in the catalytic converter and forms harmless products
such as nitrogen gas and water. Through the use of SCR the exhaust gases
are purged of poisonous levels of NO
X
in the best possible way. Scania is
making use of a system that is carefully developed and tested in our own
laboratory.
The reductant tank is available in different sizes and is heated by the engine’s
cooling system in order to avoid freezing of the urea solution; urea freezes at
-11°C. The tank and a pump module are delivered as a unit which is fitted to
brackets for an easy installation. The Scania system contains all mechanical
and electrical parts needed except from the exhaust piping which is to be
adapted according to the customers installation.
Standard
Optional
1 Evaporator module
-
2 Reductant pressure line
2.5 m
4 m, 5 m, 6.5 m
3
Coolant hose for tank and pump
heating
-
-
4 Coolant valve
-
5 Reductant fluid return line
2.5 m
4 m, 5 m, 6.5 m
6 Reductant tank
38 l
45 l, 60 l, 63 l, 70 l
7
Coolant hose, return from tank and
pump heating
-
-
8 NOx sensor with control unit
-
9 Oxidation catalytic converter
1)
Engine-mounted
Separately
10 Temperature sensor
-
11 SCR catalyst
-
12 NO
x
sensor with control unit
-
Standard
Optional
1 Customer interface, SCR system
–
2 between engine and SCR control unit
3 m
4.5 m, 6 m
3 NO
x
sensor electrical cable
3 m
4.5 m, 6 m
4 Electrical interface, SCR system
-
5 Reductant doser electrical cable
3 m
4.5 m, 6 m
6 Temperature sensor electrical cable
3 m
4.5 m, 6 m, 9 m
7 NO
x
sensor electrical cable
3 m
4.5 m, 6 m, 9 m
The principle for Scania SCR system
This specification may be revised without notice.
1) Not DC13 085A or DC16.
Mechanical system
Electric system
6
10
5
8
4
12
3
7
9
2
11
1
4
6
5
2
3
7
1