• Gas Train

Just before the gas enters the engine room a gas train, consisting of two block valves and a bleed valve, ensure that gas flow from the gas supply system to the engine can be prevented when not desired. For safety reasons one block valve, also called “Main Gas Valve”, is physically controlled from a safety unit and the other from a control unit.

Engine room installations

• Sealing Oil System

The sealing oil system supplies oil to the gas injection valve and the window valve in order to provide sealing between the gas and the control oil, and to lubricate the moving parts. The sealing oil system has two pumps. The master pump is started just before gas is lead to the engine and the other is standby in case the sealing oil pressure drops too much. The operating pressure is 25-50 bar higher than the gas pressure.

• Double wall pipes

According to the principle of Gas Safe Engine Room all piping are with double wall pipes, with the outer shielding pipe designed to prevent gas outflow to the machinery spaces in the event of rupture of the gas pipe. The intervening space, including also the space around valves, flanges, etc., is equipped with separate mechanical ventilation with a capacity of at least 30 air changes per hour. 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.

• Gas Block

For each cylinder a gas block is mounted directly on the cylinder cover. A principle diagram of the gas block is shown in annex 2. The gas block holds an accumulator to ensure that the rate of gas flow does not drop too much during the injection period.

The gas block is equipped with three gas valves:

Info no. Sub category Ident. no.

3092815 - 7Title

Dual Fuel Operation Page no.

10 (28)

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

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

 A Window/Shut Down with the functionality described in the section “Design criteria and concept of the gas system”.

 A Gas Blow Off valve used to depressurise gas connection line between the Window valve and the gas injection valves

 A Purge valve used to blow off and purge the gas in the gas accumulator.

4. Dual Fuel Control System Design

This section describes the structure and functionality of the Dual Fuel Control System GI-ECS delivered by MAN Diesel & Turbo SE and interface to other systems is only described where required for the understanding of the Dual Fuel Control System.

4.1 Main tasks and architecture of the Dual Fuel Control System

The Dual Fuel Control System has three main tasks:

1. Gas Plant Control

2. Dual Fuel Injection Control

3. Gas Safety Monitoring

The conceptual decisions of separating the control from safety and the main tasks listed above resulted in the architecture shown in annex 3