Temperature At Start Of Engine; Preheating Of Diesel Engine; Normal Start Of Engine; Start Of Cold Engine - Man B&W L35MC6-TII Project Manual

MAN B&W

Temperature at Start of Engine

In order to protect the engine, some minimum
temperature restrictions have to be considered
before starting the engine and, in order to avoid
corrosive attacks on the cylinder liners during
starting.

Normal start of engine

Normally, a minimum engine jacket water temper-
ature of 50 °C is recommended before the engine
is started and run up gradually to 90% of speci-
fied MCR speed.
For running between 90% and 100% of specified
MCR speed, it is recommended that the load be
increased slowly – i.e. over a period of 30 minutes.

Start of cold engine

In exceptional circumstances where it is not pos-
sible to comply with the above-mentioned recom-
mendation, a minimum of 20 °C can be accepted
before the engine is started and run up slowly to
90% of specified MCR speed.
However, before exceeding 90% specified MCR
speed, a minimum engine temperature of 50 °C
should be obtained and, increased slowly – i.e.
over a period of at least 30 minutes.
The time period required for increasing the jacket
water temperature from 20 °C to 50 °C will de-
pend on the amount of water in the jacket cooling
water system, and the engine load.
Note:
The above considerations are based on the as-
sumption that the engine has already been well
runin.
MAN B&W MC/MCC, ME/MEC/MEGI/ME-B engines
Temperature
increase of
jacket water
C
1.50%
60
50
40
30
20
10
0
0 10
Fig. 12.08.01: Jacket water preheater

Preheating of diesel engine

Preheating during standstill periods
During short stays in port (i.e. less than 45 days),
it is recommended that the engine is kept pre-
heated, the purpose being to prevent temperature
variation in the engine structure and correspond-
ing variation in thermal expansions and possible
leakages.
The jacket cooling water outlet temperature should
be kept as high as possible and should – before
startingup – be increased to at least 50 °C, either
by means of cooling water from the auxiliary en-
gines, or by means of a builtin preheater in the
jacket cooling water system, or a combination.
MAN Diesel
1.25%
1.00% 0.75%
20 30 40 50
Preheating time
12.08
Page 1 of 1
Preheater
capacity in
% of nominal
MCR power
0.50%
60 70
hours
178 16 631.0
198 39 860.2