A seawater pump supplies cooling water by drawing water from the sea, pushing it through heat exchangers, and then discharging it back overboard.
Specifically, as described in the reference, a sea water cooling pump takes suction from the sea chest, pumps the seawater through the central FW cooler(s) and then overboard. This flow of cold seawater through a heat exchanger (like a central freshwater cooler) allows it to absorb heat from another system (usually freshwater circulating through the vessel's machinery), effectively cooling that system down.
The Seawater Cooling Process Explained
The use of a seawater pump for cooling is a fundamental process on vessels to manage heat generated by engines, generators, and other critical equipment. Here's a breakdown based on the provided information:
- Taking Suction: The seawater pump begins by taking suction from the sea chest. The sea chest is essentially an opening in the hull of the vessel below the waterline, covered by a grate to prevent large debris from entering. This is the intake point for the raw seawater.
- Pumping Through Coolers: Once the water is drawn in, the pump pumps the seawater through the central FW cooler(s) (Fresh Water coolers). These coolers are heat exchangers where the heat from a closed loop of freshwater (which circulates around the vessel's machinery) is transferred to the cooler seawater. The seawater temperature increases slightly as it absorbs heat.
- Discharge Overboard: After passing through the heat exchanger(s) and absorbing heat, the warmer seawater is then discharged overboard, back into the sea.
This continuous cycle ensures that the freshwater loop, and subsequently the vessel's machinery, remains within safe operating temperatures.
System Configuration
- Pump Redundancy: The system can be designed with two or three pumps. This redundancy is crucial for reliability.
- Constant Operation: The pumps are crucial for the operation of the vessel and they are always running when cooling is required, often continuously at sea.
In essence, the seawater pump acts as the engine of the cooling system, circulating the readily available cold medium (seawater) to transfer heat away from vital equipment.
