DAVINIA ALBALADEJO-MORALES Universidad de Murcia
3. Regalismo y concesiones en materia educativa para la carrera eclesiástica
In addition to the PV valves there is an independent liquid PV breaker fitted to the deck distribution main. This is located in the vicinity of No.3 centre cargo tank and it acts as a two-way liquid seal safety device. In the event of over-pressure, the liquid is blown onto the deck thereby opening the deck main and cargo spaces to atmosphere. When an excessive vacuum exists, the liquid is drawn into the deck main and opens the system to atmosphere. This is accompanied by a very distinguishable sucking noise. The liquid PV breaker is designed to operate after the PV valve. This means that it is the last line of defence in protecting the tanks from over-pressure or vacuum should the PV valves be defective or not of sufficient capacity. It operates at a pressure of approximately 1800mm H2O or a vacuum of approximately -700mm H2O.
The unit consists of two vertically mounted tubular ducts fitted concentrically.
The inner duct is connected to the inert gas main. The unit is charged with a mixture of 50% water and 50% antifreeze. It is fitted with sight glass, an upper and lower test cock and a wire mesh protective flame screen.
Section 2.3.5 - Page 2 of 3
Issue: Final Draft - November 2007 IMO No: 9323948
Deck Operating Manual
Maersk Nautica
Plug
Vacuum Disc
Vacuum Seat
Filter Elements
Shaft
Disc Unit
Lift Test Spindle Upper Valve House
Check Lift Lever Check Lift
Lever Cover
Plug
Illustration 2.3.5b High Velocity Pressure/Vacuum Valve
Main
Twin Main
Twin
Section 2.3.5 - Page 3 of 3
Issue: Final Draft - November 2007 IMO No: 9323948
2.4 Inert Gas System - Main and Top-up Generator
2.4.1 System description
2.4.2 Operation of the Main System
2.4.3 procedure for the Operation of the Inert Gas Top-up Generator (TuG)
Illustrations
2.4.1a Inert Gas System on deck
2.4.1b Inert Gas System in Engine room
2.4.2a Inert Gas Control panels - Ship’s Control Centre 2.4.2b ECr and bridge Inert Gas Indication panels 2.4.2c Inert Gas Capacity regulator
2.4.3a Inert Gas Generator Control panel No.2 2.4.3b Oxygen analyser
PT Funnel Top
NGV 009
Illustration 2.4.1a Inert Gas System on Deck
No.1 Water Ballast Tank (Port) No.2 Water Ballast Tank
(Port) No.5 Water Ballast Tank
(Port) No.3 Water Ballast Tank
(Port) No.4 Water Ballast Tank
(Port)
Cargo Oil TankNo.1 (Centre) No.2 Cargo
Oil Tank (Centre) Cargo Oil TankNo.5
(Centre)
Cargo Oil TankNo.3 (Centre) Cargo Oil TankNo.4
(Centre)
No.1 Water Ballast Tank (Starboard) No.2 Water Ballast Tank
(Starboard) No.5 Water Ballast Tank
(Starboard)
No.1 Cargo Oil Tank (Port) No.2 Cargo Oil Tank
(Port) No.5 Cargo Oil Tank
(Port) No.3 Cargo Oil Tank
(Port) No.4 Cargo Oil Tank
(Port) Slop Tank
(Port)
Dump Tank
No.3 Water Ballast Tank (Starboard) No.4 Water Ballast Tank
(Starboard)
No.1 Cargo Oil Tank (Starboard) No.2 Cargo Oil Tank
(Starboard) No.5 Cargo Oil Tank
(Starboard) Slop Tank
(Starboard) No.3 Cargo Oil Tank
(Starboard) No.4 Cargo Oil Tank
(Starboard)
Key
Inert Gas Sea Water Steam Condensate Connection Point for Water Driven Fan
To Ballast Main Line
600
300 300
300
300 500
300
Vent Riser With Screen
NDV
Flame Screen
Upper Deck
A Deck
Deck Water Seal Engine
To Cargo Main Line Shore Connection
Sampling Point
NDV003
Supply from Inert Gas Fans
Recirculation to Inert Gas Scrubber
Supply from Inert Gas Generator
From Steam System
To Condensate System From Deck
Water Seal Pump
To Scrubber Water Seal
NGV0007
NGV0011
NGV025
MTV027 MTV025 MTV023 MTV021 MTV019
MTV028 MTV026 MTV024 MTV022 MTV020
NGV
Issue: Final Draft - November 2007 IMO No: 9323948
2.4 INErT GaS SySTEM - MaIN aNd TOp-up GENEraTOr
2.4.1 SySTEM dESCrIpTION
Main System
Manufacturer: Smit Gas Systems BV, Nijmegen, Holland
Type: Fin 20.630- 0.1.2
Scrubber
Manufacturer: Smit Gas Systems BV, Nijmegen, Holland
Type: Venturi
Model: 190.12.121
Fans
Manufacturer: Flebu International AS, Voyenenga, Norway
Type: Centrifugal single-stage
Model: No.1 fan: BK40-1E
No.2 fan: BY31.5-1E
Capacity: No.1 fan 20,630m3/h at 2.16 bar (100% nominal)
No.2 fan 11,000m³/h at 2.0 bar (50% nominal)
Rating: No.1 fan 210kW, No.2 fan 103kW Top-up Generator System (TuG)
Manufacturer: Smit Gas Systems BV, Nijmegen, Holland
Type: Gin 500 - 0.15 BU
Capacity: 500m3/h (nominal) Inert Gas Sea Water pump
Manufacturer: Shinko Industries, Hiroshima, Japan
No. of sets: 1
Type: Vertical, motor-driven, centrifugal
Model: RVP250M
Capacity: 360m3/h at 6.0 bar Scrubber consumption: 357m3/h
TUG consumption: 42m3/h deck Seal Sea Water pump
Manufacturer: Shinko Industries, Hiroshima, Japan
No. of sets: 2
Type: Horizontal, motor-driven, centrifugal
Model: HJ40-2M
Capacity: 5.0m3/h at 5.5 bar
Introduction
The inert gas system (IGS) consists of a main inert gas plant, using boiler flue gas and an independent inert gas generator plant, to provide a gas explosion protection system, ie, a low O2 content in the cargo oil tanks and slop tanks.
This is achieved by maintaining a slight over-pressure in the tanks at all times.
Whilst discharging the cargo, liquid pumped out of the tanks is replaced by inert gas. Pressure of the inert gas in the tanks is to be maintained above atmospheric pressure at all times.
The IG used on this vessel is produced either by a conventional flue gas plant, which cools and cleans exhaust gas from the boiler uptake(s), or by an independent inert gas topping-up generator system, which burns marine diesel oil at a very low excess air setting. The resulting exhaust gas from either system is cooled and cleaned before being fed into the cargo tanks.
The main system is designed to maintain a positive tank pressure of 600
~900mmWG, with a tank O2 content of less than 5% maximum.
The system is used during:
• Cargo oil unloading.
• Hydrocarbon gas purging.
• Tank cleaning.
• Crude oil washing.
• Reducing the O2 content in the tank volume.
• Emergency inerting from deck of the ballast tanks via dedicated flexible hoses. The system offers additional flexibility for inerting and purging the ballast tanks, by the IG main connecting into the ballast main piping via a spool piece on deck before the IG main block valves.