Abstract: Centrifugal separator and a granular bed filter are arranged one over the other in a common cylindrical housing to constitute a unit for separating solid particles from a gas stream. For more effective separation of solid particles within a structure having a given overall volume, the gas inlet pipe is rectangular in cross-section and has a height amounting to 60 to 80% and a width amounting to 20 to 30% of the height H and a gas guide is provided in the gas outlet pipe and extends parallel to the axis of the pipe. This will result in an optimum matching of the separation of solid particles affected by centrifugal force and in the granular bed in close succession in the single structural unit.