To prevent the internal erosion generated in a quenching column for quenching exhaust gas formed by incinerating industral waste.

Exhaust gas is introduced into the quenching column 1 as a descending flow and successively passed through the first region 2 on the inlet side of the tower, where the cooling of the exhaust gas is generated by the heat conduction with the inner wall of the quenching column 1, the second region 5, where the cooling of exhaust gas is generated by the heat conduction with the inner wall and cooling water, of the tower and the third region 4, where the exhaust gas is quenched to at least a temperature range of 800-80°C by cooling water ejected from a spray nozzle 3, of the tower. The inner wall of the second region 3 is constituted of SK30 refractory.