JACKET COOLING WATER SYSTEM

Aim:

Cooling of engine is achieved by circulating cooling liquid around internal passage within the
engine (Jacket Space)

The cooling liquid heated up is cooled by sea water without adequate coding certain past are
exposed to high temperature as a result of burning of fuel which would water is not used
used directly nature cause failure of parts Sea a coding media because of its corrasive as a

System

Jcw system for a slow speed engine is shown in fig. Pumps takes suction from dearator and
discharge it to coded and then passes through 3 way vlv. Further it enter into a bottom
manifold and gent equally distributed to all six units as the bottom and top of cylinder liner.
Therefore quills are present further through cylinder head ie. bore passage, to exhaust ulv
and back to deareator. Two pipes are connected to the top and bottom of the deareator
through expansion tank,

•Components.

) JWC Plp: Cooling coater needs to flow through Jacket spaces, bore passages, for this
water pressure is required which is supplied by JOW plp. There are two pumps of which one
is running and one is standby, the suction and discharge lines of both the pumps are
connected with common manifold through. SD & SDNR vis. For automatic operation The
pressure developed by pumps are between 1.5 to 2 bars

2) Suction and discharge pressure gauges: Pressure gaugers are used to monitor suction
and discharge pressure of the pump. Suction pressure gauge is compound (vacuum) gauge,
Both the pressure gauges are provided with isolation values, for maintenance and
replacement of pressure gauges.

with resped to discharge pressure the pressure switch cuts out the respective Jow plp in
case of low discharge pressure, and stundby plp cuts in.

3) SD & 3DNR values:

The suction values of both the plp are SD where as disharge vlu are SONR Both suction and
discharge uw of both pipare always hept open for automatic operation of plp. The discharge
vlu are SONR to avoid badeflow of water to standby plp

JCW Cooler:
It is shell and tabe heat exchangers, cooling F.w Houss through shell and seacoater flows
through tubes. These are 4 thermometer. ie, Sexscater in , sere water out, fresh water in
fresh water out, During ↓ maintenance and overhaul the heat exchanger is drained through.
drain viv of the bottom of shell.

In order to check leakages in tubes hydraulic pressure test is carried out for which pressure
testing Hange is connected on the shell In case of any air entrapped in cooler it has to be
purged out through purge cock.

5) Sacrificial anode:

Since sw is used as heat exchanging medium, it has corrosion causing potential. Dissimilar
metals in presence of electrolyte solution causes formation of galvanic cell and leads to
Galvanic Corrosion In order to protect the shell and tube from corrosion the Sacrificial
anodes are fitted on shell.

6)Preheater:

Before starting the engine the engine has to be warmed up to avoid thermal shocks Suction
side of the Jew ptp. Steam preheater is fitted after the

The steam supply to preheater is controlled by PID controlled. through a signal hom
thermostatic switch within the preheater line

7) Pneumatic control diaphragm operated three way valve:

The throttling of water is controlled by a PID controller. which recieve signal from engine
outlet temperature switch. The

3 lines connected to 3 way valve are

→From cooled (Inlet line)

→ Bypass line inlet line)

→Two system (outlet)

The temperature of water is more then, more water will go amoutht. of flow through cooler, if
temp. of water less then water will bypass through cooler [Temp range. 75°c & max 85°C].
Minimum

8) Inlet manifold:

The water flows from outlet of 3 way valve to the inlet. mamifold. The inlet manifold equally
distibute pressurized coater to all the units as well as to the turbocharger cooling. The inlet
manifold is provided to the temperature sensor. It displays the ondet temperature of water
entering into units to ensure optimum temp. is maintained.
Pressure switch It displays the inlet pressure of water entering into all units to ensure equal
distribution.

Local thermometer: During watchkeeping the temp of indet manifold can be measured using
local thermometer.

The Jacket water from the system can be drain during maintenance through a dran cock
provided at the end of the indet manifold.

a)

Cylinder liner jacket passage:

The Jacket passage is divided into two section because of presense of quills at the centre
centre water from inlet manifold is connected to both lowered and apper Jacket through
branch pipe. Also both lower and upper Jacket passage connected internally through a pipe

The temperature sensor is fitted on upper Jacket of each unit to monitor Jow temp of each
unit, which helps to ensure each unit is performing within optimum range.

10)

Cylinder head coding water space:

Water from upper Jacket flows into cylinear head coding space These cooling spaces are
drilled bore passage, which cods fuel injectors, starting air value and body of the cylinder
head.

4)

Exhausts valve housing:

Water flows from cylinder head to exhaust uw housing which cools valve seat, valve guide
and valve spindle The outlet bempt of water from exhaust valve housing is monitored
through thermometer fitted. on outlet of each unit.

12

) Expansion Bellous:

Expansion bellow is fitted between exhaust valve water outlet pipe and outlet (common
manifold). Since working temp of water flowing through system is in between 75°C to 85°c
which thermal may lead to thermal expansion of pipe. If the connection is rigid It may crack
due to thermal. expansion and vibration

13)

Outlet manifold:
Cooling water from all unit enter into common manifold through expansion bellow vent /
Recirculation, line is connected to outlet manifold cwhich opens into expansion tank. These
line is fitted with an islation value. Temp Switch and temp. sensor is fitted on outlet manifold.

Temperature switch provide signal to PJD controller) which in turn controls the Sway valve
whereas the temperature sensor indicates the manifold temp in ECR The outlet manifold. is
provided. with isolation value

An orifice, is provided in line cohich connect outlet manifold to the deareater. It creates the
back pressure in the each one every jacket passage to get better heat transfer from each
unit.

14) Deareator.

Air or gas entering the system can lead to loss of cooling water pressure as gas expands, in
the suction eye of Jew plp In the event of gas gas leathage loss of Jacket coater pressure
via the head or crack. lines, rapid can occur. The deareator is an equipment which will slow
down the process sufficiently to allow the vessal. to be placed in the safe. position for the
maintenance.

which Dearrator removes vapour, dissolved oxygen and other gouses. are present in the
system the dearrator. has 4 connection.

→ Vapour line at the Top Coutgoing).

→Jcw plp. Suction. Coutgoing)

→ Outlet manifold of six units. Cincoming)

→Makeup line from expansion tank. Cincoming)

15) Expansion Tank:

Expansion or header tank. maintain a constant head. on the circulation pumps reducing
cavitation at higher temperatures. Acts as a reserve in the event of leakage. Atso it is we for
dosing of chemicals.

Construction features.

The expansion tank has a goage glass for measuring the water level of the tank.

- A low level, alarm is also present so there can be an alarm is ECR before the tank gets
empty and air enter the system

- For filling of the tank an make up, line is provided. on top whose. vw is manually, operated
for filling up the tank as per consumption.
-A hatch is also provided. for adding chemicals in the tank, and its also use by the
watchkeeper to see any pressure of exhaust gas fumes or lube oil which will be carried by
the Jacket cooling water in case of liner cylinder head cracks. or

- A manhole is also provided for maintenance purpose.

- A vent is provided on top for removal of hot gases and steam which is not condensed. A
space is provided. at the top for steam to condense

- An overflow pipe is provided on top of tank for overf excess water from tank overflowing of
So there is always sufficient amount of space for vapour to expand and Condense

-Drain is provided for draining during maintenance purposes. Two inlet pipes Cone for the
purging, draining and also use as recirculation line for Jacket water and other as vapour. to
get Condense.

One outlet pipe which is used for make up line. for Jacket cooling water system.

Purging / Recirculation line:

The pipeline is provided at the left mast corner of outlet manifold this used for 3 major
function:

D Recirculation

2) Drain

3) Purging.

Recirculation: When the chemical. is added in the expansion tank it is required to be

From expansion tank to the system. For this we open the isdation. valve of this pipelines and
chemically treated water now corculated from expansion tank to the system.

Drain: During overhauling the system has to be drained and de-pressurized For this we open
the isolation valve and the atmospheric pressure help. the system to drain through drain
cock, provided at inlet. of JCW. manifold

Purging: After the overhauling of the system the air from the system is required to be purged
out. For this we open the isolation vlw. of this pipeline and air from the system travel through
this pipelines to the expansion tank and then, vent out to the atmosphere.

System parameter:

Pressure = 1.5 to 2 bar

Water temp = 75 to 85°C.

Chemical. Treatment:

The engine cooling coater should be determineralized. coater with proper treatment
essential for effective cooling, and. preventing corrosion untreated distilled water alasorbs
coa from air & becomes corrosive therefore, it is necessary to add corrosion inhibiters should
be checked and treated to satisfy following requirements

→PH. total hardness as Cacos T chloride, Suliphate silicate

The property of coding water may be changed during service due to contamination or
evaporation. The evoling water Should be checked preferably once in a week with help of
test Kits laboratory test of sample water is also recommended every 3 montly.

Some recommended chemical are listed below:

Carboxylates →50L- 1000L

T Nitrile 3kg/1000L

Nitrite Borate 2.25L/1000L

NitritePolymer 8L/1000L

Maintenance :

Cleaning:

If any deposit or rust is abnormally detected in the coding water system, the system should
be deaned throroughly and then the cooling water also should be refilled up completely by
needy treated water.

The cleaning of the cooling soling system includes degreasing and de-scaling procedures
which needs special, chemicals. It should be done strictly in accordance with instructions
from the supplied of cleaning chemicals.

Filling up of coding water:

Directly after cleaning process of the coding system. Flush the system throroughly with water
until Pit value to be about 7 and drain the water. Fill up the system with distilled water until
the water level of the expansion tank to have margin for the treatment.

Prepare the solution of inhibitor acording to the instruction. from the maker and add the
solution into the expansion tank. Add distilled water more to the normal level of the
expansion tank. Run the engine for settlement according to the inhibitor makers. ors
recommendation or at least for 24 hours and then check the quality of water for confirmation.
If the amount of cooling water is reduced due to evaporation or leakage or drainage for
maintenance, the water level of the tank should be maintained by adding water. water for
compensating evaporation should be distilled water. while the water for less due to leakage
or drainage should be some treated water. After adding the water checking of the quality of
water should be carried out to confirm the correct concentration of the ingredients.