This article throws light on LNG ships in general. The two most famous designs of Q-flex and TFDE LNG ships are being compared. Readers can also easily compare the difference in operation on an electrically propelled ship and a conventional diesel propelled ship.
Tri-Fuel diesel Electric Propulsion Ships (TFDE) Operations
TFDE stands for Tri-Fuel diesel electric propulsion ships specifically for LNG carriers. Let us now see the general operational advantages from an Engineering point of view.
1. These ships have no Main propulsion diesel engine. They just have two small electrical motors. Thus less space and weight which can be used for cargo carrying.
2. Almost “zero” maintenance on electrical motors when compared to main diesel engines.
3. The bottom platform is almost empty without main diesel engines. Thus greater flexibility for locating machineries.
4. No scavenge space waste oil production. No cylinder oil and main lube oil Usage.
5. The ship can be constructed without any main engine sump space for lube oil and thus associated cofferdams.
6. No starting air pipelines and starting air compressors for main engine.
7. No HFO/MDO purifiers will be running as in diesel ship and thus less maintenance and cost.
8. Sludge production is very minimal and condensate from main engine, its associated tank can be neglected.
9. Easier watch keeping as parameters are less to monitor in the absence of main propulsion engine.
10. No vibrations and noise as compared to diesel engines.
11. The electrical motors can run even at 1 or 2 RPMs. Thus adding greater navigational advantages.
12. No limitations in number of starts on diesel engine.
13. Departure or arrival port, notice time required is very less when compared to a diesel engine propelled ship.
14. Complex electrical, electronic circuits and transformers for propulsion motor and speed control devices are required.
15. Sea water piping and cooling circuits are comparatively smaller.
16. Regular transfer of fuel is not required as the ships generator runs on gas.
17. The ship is generally classed as high voltage as the operating voltage may be of the order of 6600 Volts to 11kV.
18. Electric motor starting problems are very less when compared to diesel engine reversing and starting problems.
19. Electrical braking of the propulsion shaft is very much effective when compared to mechanical breaking in case of diesel engines.
20. The total operational cost of the ship is very less when compared to a diesel engine propelled ship.