Exploitation

The operating procedure of the high-temperature fresh water cooling circuit is discussed as an example of the operation of one of the most complex and critical equipment for the safety of the ship - the main engine, the HT circuit cooling water system.
a)         Make sure that the level in the expansion tank is correct, top up with fresh water from the engine room if necessary.
b)    Make sure all valves on the pressure gauges and devices are open.
c)    Make sure the fresh water generator is bypassed.
d)    Make sure that all individual main engine cylinder cooling inlet and outlet valves are open, that the shut-off valves on the turbocharger body are open, and that all bleed valves are closed.
e)    Make sure all ventilation and drainage valves on the individual main engine cylinders are closed.
f)     Switch the valves as shown in figure below.
g)    Make sure the low temperature central fresh water cooling system is working properly.
h)    Bleed the system by opening a dedicated valve and closing when all air is released.
NOTE: When venting, fill the deaerator, which has a filling / refill connection from the fresh water expansion tank via a dedicated valve.
i)     Switch on one high-temperature cooling water circulation pump and select automatic standby for the other pump (only if the pumps are electrically driven).
j)     Deaerate the primary heater.
k)    Make sure that the condensate drain valve from the preheater is open and steam is supplied to the heater (only if steam is used for heating. If thermal oil is used for heating, open the thermal oil supply and drain valves from the heater).
NOTE: When the engine is being started, stopped, or run at low load, the HT cooling water temperature is maintained by directing a portion of it to circulate through the HT cooling water preheater. The heater uses thermostatically controlled steam or thermal oil to heat the water.
l)     Slowly raise the cooling water temperature to operating temperature using the steam or thermal oil control valve temperature setting. Check the system for leaks and rectify any leaks.
m)   Check the concentration of inhibitor in the cooling water system and add chemicals if necessary.
NOTE: To reduce the risk of corrosion, the cooling water in both cooling systems is treated with inhibitory chemicals. Cooling water must be tested in accordance with the requirements of the chemical supplier's and the company's operating procedures. After any necessary chemical treatment, it is necessary to record this by indicating the amount of chemicals added to the fresh cooling water expansion tank.
n)    When the main engine is sufficiently loaded, the high temperature cooling water can be directed to circulate through the fresh water generator if required.
o)    Open the cooling water heater bypass valve.
p)    Close the heater cooling water inlet and outlet valves.
NOTE: At sea, when the main engine is running at normal load, the heater will be bypassed and the hot cooling water will be routed through a fresh water generator that acts as a water cooler and produces fresh water for the ship by low pressure evaporation. If necessary, fresh water production can be maximized by using an HT cooling water preheater to increase the heat output to the fresh water generator.

Example of preparing a high temperature circuit cooling system for the start of an ME