The inner/outer self-cleaning phenomenon in the granular bed filter-cyclone coupled separator

•A novel phenomenon named by self-cleaning in a granular bed filter-cyclone coupled gas–solid separator was proposed and investigated by experiments.•The tangential velocity induced by the cyclone shell played an essential role in both the dust collection and the outer self-cleaning.•The dust cake formation was restrained by the inner self-cleaning induced by the scratching of the collector particles movement.•The self-cleaning phenomenon was of practical relevance and the relevant underlying mechanisms were analyzed.