Components in line: fuel/air inlets -> combustion blower (forced draught) -> burner and combustion chamber/boiler fired by diesel or gas -> exhaust gas -> inert gas cooler/quench -> water separator / scrubber unit (sea water washing) -> demister (mist eliminator) -> refrigeration chiller (inert gas cooler/dryer) -> activated charcoal / desulphurisation or final filters -> inert gas discharge blower -> distribution header and valves -> to cargo tank (vent/ purge / pressure control). A gas analyser (O2/CO2 content) and dew-point monitor are on the discharge line, with a discharge overboard/by-pass line and deck water seal.

An inert gas generator produces inert gas specifically for gas carriers, where the inerting medium must be of very low oxygen (typ. less than 1-2% O2 for gas tank inerting) and low hydrocarbon residue, often hot, dry and clean so it does not contaminate or condense in the tanks. Air is drawn by a blower and mixed with fuel (marine diesel or the cargo/gaseous fuel) and burnt in a pressurised combustion chamber so that essentially all oxygen is consumed. The hot combustion products (mainly nitrogen, carbon dioxide and water vapour) then pass to a cooling/scrubbing tower where they are cooled and washed by sea water, which removes particulate soot, sulphur and soluble gases and drops the temperature. A demister removes entrained water droplets. The gas then passes through a refrigeration chiller/cooler which dries it by condensing out water vapour, giving a low dew point so that no liquid water or ice can form in the tanks. Final polishing (activated carbon for odour/removal) may be added. The inert gas is delivered by the discharge blower to a distribution header; from there it passes through the deck water seal and dry lines into the cargo tanks, where it is used to inert, purge, pressurise and (with the pump) vapour-free the tanks. Continuous O2 and dew-point analysis confirms the gas is within specification; if the oxygen is too high the gas is automatically diverted overboard.

The chiller (refrigeration cooler) cools the inert gas below its dew point so that the moisture condenses out, producing dry gas of low dew point (commonly below -40 C or a set low value). This prevents: (1) formation of liquid water, ice or hydrates in the cold cargo tanks, which could block valves, cause corrosion or contaminate and give erroneous readings; (2) water vapour that would otherwise be carried into the tanks. The chiller therefore ensures the inert gas delivered to the tanks is dry, protecting the cargo and equipment and maintaining tank atmosphere integrity.