2011-03-16 JAB JAB ER Document transferred to template. 0

3.3 The Design of the Dual Fuel Engine

The principle P&I diagram in ref.1 showing the gas installations is the best approach to understand how the MAN Diesel & Turbo high pressure gas system is working. Notice the separation of installations inside engine room, which has to follow the design principle of gas safe engine room, and external installations outside engine room.

In the following the functionality of the main components of the gas system are shortly explained.

External systems outside engine room

The detailed design of the external systems will normally be carried out by the inpidual shipyard/contractor and is, therefore, not subject to the type approval of the engine. The interface to the external systems is specified by MAN Diesel & Turbo see annex 3. Furthermore, the GI-ECS electrical interface to the external systems has to pass a barrier to ATEX area.

• Double Pipe Ventilation System

The purpose of the ventilation system is to ensure that the space between the inner and the outer pipes of the double wall gas pipe system and the gas components in the gas block is ventilated with air, and it acts as a separation between the engine room and the high pressure gas system. The pressure in the duct has to be below the pressure in the engine room in order to safeguard against any gas leakage to the engine room. To make sure that the pipes are vented sufficiently, two flow sensors are located at the air inlet i.e. opposite to the suction fan. Thereby, it is possible to detect if the gas outer pipe is fractured.

• HC Sensors

Two double set of HC sensors are used.

One set for safety monitoring in the vented double pipe detecting a leakage in the gas system on engine.

The other HC sensor set detects gas in the gas return pipe. It is used during the inert gas purging sequence to determine when the gas system on engine can be considered purged.

• Gas Supply System

The purpose of the Gas Supply System is at any time to deliver the required gas flow at the specified pressure, which is load dependent. The gas pressure varies between approximately 200 to 300 bar.

Info no. Sub category Ident. no.

3092815 - 7

Title

Dual Fuel Operation Page no.

9 (28)

Date Des. Chk. Appd. A. C. Change/replacement C. no.

2011-03-16 JAB JAB ER Document transferred to template. 0

• Gas Return System (Optional)

When gas running is stopped the remaining gas in the pipes and accumulators on engine side is returned  to the Gas Return System if it is ready to receive gas.

Otherwise, the gas is blown off to the atmosphere. In case of a Gas Shutdown the gas is always send to atmosphere.

• Inert Gas System

The inert gas system provides inert gas used during the purging procedure to flush the gas system on engine after a gas stop and a blow off of high pressure gas.