Marine and land-based
diesel generators operate on exactly the same principles. However, due to their different operating environments, marine generators operate in more harsh environments. Therefore, when selecting a marine generator, it's important to consider the following environmental factors:
Typically, a diesel generator set and its main engine use fresh water to cool the engine block, cylinder liner, and cylinder head. This fresh water forms a closed circulation system, which is cooled by seawater. The heat exchanger used to cool the fresh water is typically made of corrosion-resistant copper.
Most large marine diesel engines are now equipped with a central cooling system. Seawater cools the fresh water inside, which is then used to cool the generator set and other equipment. This effectively reduces component corrosion.
The circulating water in the heat exchangers of land-based diesel generators and diesel engines is cooled by water from a sump, so the heat exchangers used by land-based generators and engines are the same. Marine diesel generator sets and marine diesel engines are typically equipped with seawater heat exchangers, using seawater to cool the internal water. Therefore, the heat exchangers used in marine diesel generator sets and diesel engines are identical.
There are differences between land-based and marine heat exchangers: the former uses freshwater tanks to cool the internal water, while the latter uses seawater. Consequently, the auxiliary systems of marine generator sets are relatively complex, with a comprehensive suite of auxiliary machinery systems. Generators on ships operate at speeds of 1000 rpm and 750 rpm (50Hz system), and starting typically uses 3MPa compressed air. Regarding fuel selection, high-quality marine generators can use 180° heavy fuel oil, which significantly reduces long-term power costs. However, this comes with the disadvantage of relatively complex maintenance and management.
In addition to the aforementioned environmental considerations, marine diesel generators also have stringent requirements. They must comply with the relevant standards of GB/T 3020, "General Technical Specifications for Marine Diesel Generator Sets," and must undergo inspections by China State Shipbuilding Corporation and CCS Classification Society to obtain the corresponding certifications.
The list of documents required for CCS certification includes an application for approval of marine product drawings/technical documents, a copy of the business license, a company profile, a statement of technical implementation capabilities, a list of testing equipment, a project description, a control panel approval test outline, a unit approval test outline, electrical design drawings, a general plan, a common baseplate drawing, a strength calculation for the marine engine baseplate, diagrams of each system, and functional descriptions of each system diagram.
