PURPOSE: To prolong the life of a filter by introducing an exhaust gas which leaves from a combustion chamber and has a specific temp. and pressure and in which an ash content is 0.1 to 60 g/Nm3 to at least one baffle surface and separating a liquid ash content.

CONSTITUTION: The exhaust gas 6, which is generated by combustion of carbon- contg. fuels and has the temp. of 200 to 1800°C, the pressure of 1 to 100 bars and the ash content of 0.1 to 60 g/Nm3, is introduced perpendicularly downward from above into an inversion type separator 1 through an inlet 10. When the ash-contg. exhaust gas 6 collides against the baffle surface 13, the ash liquid drops are separated and flow downward on the baffle surface 13 disposed to incline slightly. The exhaust gas 7 from which the ash liquid drops are sufficiently removed emerges from the inversion type separator through an outlet 11. The liquid ash 16 gathers to the conical portion of the inversion type separator 1 and is intermittently discharged through a valve 9 and a pipeline 8.