A device, similar to a boiler, in which fuel is burnt to create exhaust gases which contain less than 5% oxygen. Inert gas generator consists of a combined burner and scrubber, both seawater-cooled. Marine diesel or heavy fuel oil is burnt to produce flue gas with oxygen content of 2-4%. The gas then enters the scrubber part, where it is cooled and cleaned by sprayed seawater before being led to the deck area.