This study has been conducted to compare two cargo handling systems on MR tanker and Panamax tanker. Submerged hydraulic cargo pumps with hydraulic powerpacks (Hydraulic Systems) and frequency converter controlled electric deepwell pumps (Electric Systems) will be investigated and compared on all aspects of initial cost, installation, operation and maintenance.
The result of investigation shows Electric Systems have less manufacturing costs, higher environmental friendliness and reliable operation compare to Hydraulic Systems. Furthermore, the present experimental data will provide important database for Electric Systems onboard new ships and practical and empirical guidelines are constructed for further determine the design of the Electric Systems.
As a practical installation of Electric Systems, one of TOTAL FPSO and Teekay FPSO, some design criteria like air cooled converter room design, high viscosity operation, operation procedures and deepwell pump installation were introduced.
The environmental aspects are of great importance today, and this report concludes that energy consumption clearly favors Electric Systems compare to Hydraulic System. On the two reference vessels, annual fuel saving in generating the needed cargo discharge power can be estimated up to 17 % savings compare to Hydraulic System.
It is also possible that hydraulic oil pipes on deck could corrode and leak oil and subsequently be responsible for an oil spill.
Following main features for Electric Systems can be listed:
● Environmental friendly
● Proven record from FPSO, LPG ships & Chemical Tanker
● Less maintenance cost compare to Hydraulic Systems
● Stepless control by frequency converter
● Less total weight and less noise than Hydraulic Systems
● Improved efficiency compare to Hydraulic Systems
● Electric Systems can be fully utilized to handle liquids in a big specific gravity and high viscosity variation range.
Finally, this report carried out an extensive economically analysis, based on Capex* and Opex*, and concluded that savings could be made by specifying Electric Systems on the two reference vessels and FPSO project. Economical analysis has been based on new built in Korea.
* Capex Operating Expense Capital Expenditures, Opex