Inert Gas Generator, from the name we already known that it is gas to inert on tank. I used this package to prevent explosion on fuel tank. I suppose that Watsilla and Alfa Laval are leading tech on this kind package. As statutory rule and standard, we have to prevent Oxygen contain over 8 % on fuel/oil tank. It is relate with flammable mixture limit. As we know about triangle combustion, vary component such as fuel, oxygen and ignition. A mixture of hydrocarbon gas and air cannot ignite, unless its composition lies within a range of gas-in-air concentrations known as the flammable range. Line A-B that have slope is limit without inert gas, and left line like a curve is line after added inert gas.
Commonly, on offshore project, IGG perform sea water to reduce heat of inert gas after combustion process, and to collect dangerous gas such as NOx and SOx, IGG put Scrubber on top of tank. Fresh water purge wall to prevent corrosion. Before through inside IGG, those fluid will pass on Duplex basket filter, kind of filter that use micro mesh. Fresh air and fuel gas to conduct combustion and nitrogen gas to flash from any accident that may happen. PSV are applied on fresh air and fuel gas to make safety process with set point as by pass from IGG. PV Breaker or pressure vacuum breaker applied on line of gas output. PV Breaker use hydrostatic pressure method. Kind of safety component to maintain pressure and if it failure inert gas will through out from line by PB Breaker.
Beside preventive on fuel/oil tank explosion, Inert gas can perform to decline condensate oxygen on fuel tank, so that we can ignore condensate that collect on top of tank, then fall and mixture with fuel. Because it can disturb engine combustion if fuel already contained water. Air on tank has humidity, humidity is water contain in air. During some condition water will adhere on top of tank. and may collect and drop into fuel.
Please kindly read bellow statutory standard from Canada regarding IGG