Method and device for controlling oxygen content of tail gas of organic contaminated soil thermal desorption system

The invention discloses a method and a device for controlling the oxygen content of tail gas of an organic contaminated soil thermal desorption system. The method comprises the three steps of air purification pretreatment, nitrogen preparation and online nitrogen supplementation. The device comprises an air purification pretreatment unit, a nitrogen preparation unit and an online nitrogen supplementation control unit which are sequentially connected according to the directionofgasflow, wherein nitrogen protection is provided for an organic contaminated soil thermal desorption system through the online nitrogen supplementation control unit. According to the invention, through the air purification pretreatment unit, the contents of oil, water and dust in air meet the requirements of raw materials of a nitrogen making machine; nitrogen with the purity of 98-99.99% is obtained through a nitrogen preparation unit; and nitrogen is automatically supplemented into a thermal desorption system through the online nitrog