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Very Large Gas Carriers - Using LPG as Fuel (Part 2 of 4)


Arrangements for using LPG as fuel onboard VLGC

Typical system arrangement for using LPG as fuel onboard, essentially would have provision for storing, processing, supplying and consuming the fuel. In addition, essential safety and control systems are to be available. Following is a brief description of a basic arrangement with essential components.



Engine

MAN LGIP Engines (Courtesy - MAN website)


MAN B&W has developed the ME-LGIP series two-stroke diesel cycle engines which is being proposed for VLGCs. These are based on the ME-GI engines used extensively in service with LNG carriers and LNG as fuel ships.

LPG is supplied to the engine, in liquid form, at 50 bar and a temperature range of 30-50 ℃ by the Fuel Processing and Supply system. The cylinder head mounted LPG injector further pressurizes the fuel to 600 bar, the injection pressure. Pilot fuel is also injected to the cylinder via the pilot fuel injector located on the cylinder head (MAN Energy Solutions, n.d.).

Certain amount of LPG is re-circulated back to the fuel oil service tank. The engine can operate on LPG at loads above 10%. The first engine of this type was tested in Busan, Korea in December 2019.

LPG Storage & Service tank

VLGC Arrg't with Fuel Service Tank & Fuel Preparation Room within the compressor room


On VLGC, the cargo loading manifold and cargo tanks itself can be considered as provision for bunkering and fuel storage. Additionally, a fuel service tank is provided as a deck tank, located close to the fuel gas processing room. It is provided to prevent any cargo contamination from the LPG re-circulated from the engine due to its higher temperature, possible oil traces etc. (MAN Energy Solutions, n.d.)

The service tank would also allow separation of any Nitrogen, mixed with LPG during the return line purging operation. LPG from the cargo tanks could be transferred by submerged fuel transfer pumps from where it would pass on to the fuel processing system. 
Type- C pressure vessel design is suitable for the service tank.


Comments

  1. Priyashree16 August 2022 at 06:45

    Excellent information regarding LPG Gas Storage Tank & Service tank. Really informative. Thanks for sharing.

    ReplyDelete

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