Inert gas source is taken from exhaust uptakes of boiler or main engine as it contains flue gases.
It serves as the supply valve from uptake to the rest of the system, isolating both the systems when not in use.
Flue gas enters the scrub tower from bottom and passes through a series of water sprayers and baffle plates to cool, clean and moisten the gases. The SO2 (sulphur dioxite) level decreases up to 90% and gas becomes clear of soot.
Flue
gas enters the scrub tower from bottom and passes through a series of water sprayers and baffle plates to cool, clean and moisten the gases. The SO2 (sulphur dioxite) level decreases up to 90% and gas becomes clear of soot.
Normally made of polypropylene, it is used to absorb moisture and water from the treated flue gas.
Normally two types of fan blowers are used, a steam driven turbine blower for I.G operation and an electrically driven blower for topping up (refilling) purpose.
The pressure within the tanks varies with the property of oil and atmospheric condition. To control this variation and to avoid overheating of blower fan, a pressure regulator valve is attached after blower discharge which re-circulates the excess gas back to the scrubbing tower.
Its purpose is to stop the gases returning back.
it is an additional non return mechanical device inline with deck seal.
The engine room system can be isolated fully with the deck system with the help of this valve.
It helps in controlling the over or under pressurization of cargo tanks.
A vessel has numbers of cargo holds and each hold is provided with an isolating valve. The valve controls the flow of inert gas to the hold and is operated only by a responsible officer in the vessel.
It is used to maintain a positive pressure of inert gas at the time of loading of cargo and during the loading time it is kept open to avoid pressurization of cargo tank.
Motor driven inert gas blowers supplies the treated gas from the scrubber tower to the tanks through pipes which are mounted on rubber vibration absorbers and isolated from the piping system by rubber expansion bellows.
Regulation of gas quantity delivered to the deck is controlled by gas control valves and the deck pressure is managed by pressure controller. If the deck pressure is lower than the set point, the output signal will be raised to open the valve more, and vice versa if the deck pressure is lower than the set-point. These valves will then work in cooperation to keep both the deck pressure / blower pressure at their respective set point without starving or overfeeding the circuit.
Regulation of gas quantity delivered to the deck is controlled by gas control valves and the deck pressure is managed by pressure controller. If the deck pressure is lower than the set point, the output signal will be raised to open the valve more, and vice versa if the deck pressure is lower than the set-point. These valves will then work in cooperation to keep both the deck pressure / blower pressure at their respective set point without starving or overfeeding the circuit6. before entering the deck line, the gas passes through the deck water seal which also acts as non-return valve automatically preventing the back-flow of explosive gases from the cargo tanks to the engine room.
Regulation of gas quantity delivered to the deck is controlled by gas control valves and the deck pressure is managed by pressure controller. If the deck pressure is lower than the set point, the output signal will be raised to open the valve more, and vice versa if the deck pressure is lower than the set-point. These valves will then work in cooperation to keep both the deck pressure / blower pressure at their respective set point without starving or overfeeding the circuit
6. before entering the deck line, the gas passes through the deck water seal which also acts as non-return valve automatically preventing the back-flow of explosive gases from the cargo tanks to the engine room.
After the deck seal, the inert gas relief is mounted to balance built-up deck water seal pressure when the system is shut down. In case of a failure of both the deck seal and the non-return valve, the relief valve will vent the gases flowing from the cargo tank into the atmosphere.
The oxygen analyser which is fitted after the blower separates the “production” and “distribution” components of the plant and analyzes the oxygen content of the gas and if it is more than 8%, it alarms and shuts down the plant.
High Level in scrubber leads to alarm and shutdown of blower and scrubber tower
Low pressure sea water supply (approx. 0.7 bar) to scrubber tower leads to alarm and shutdown of blower
Low pressure sea water supply (approx. 1.5 bar) to deck seal leads to alarm and shutdown of blower
High inert gas temperature (approx. 70 deg C) leads to alarm and shutdown of blower
Low pressure in line after blower (approx. 250mm wg) leads to alarm and shutdown of blower
Oxygen content high (8%) leads to alarm and shutdown of gas delivery to deck
Low level in deck seal leads to alarm and shutdown of gas delivery to deck
Power failure leads to alarm and shutdown of blower and scrubber tower
Emergency stop leads to alarm and shutdown of blower and scrubber tower