Abstract: An incineration system and method are disclosed wherein a waste gas is transferred from tank means to an incinerator for disposal therein. Products of combustion discharged from the incinerator may be used (1) to heat a liquid medium for use in washing down the tank means; and (2) as an inert purge gas for application to said tank means. A control system is disclosed for the admission of fuel, combustion air, incineration air, and waste gas to said incinerator whereby a substantially constant operating temperature may be maintained therein despite variations in the quantity and heating value of waste gas admitted thereto, thus resulting in products of combustion of substantially constant quality suitable for use as a purge gas.