Process for filtering crude gases and filter apparatus

In a process for filtering crude gases, migrating granular filter material (15) passes through a migrating bed (11, 27); in this case, the crude gas first flows through the migrating filter material (15), which is located in this migrating bed (11, 27), and, in addition, through a further filter medium stationary relative to the migrating filter material, cleaning being carried out at this medium as a result of the movement of the migrating filter material past the stationary filter medium. The stationary filter medium is formed for example by a filter bag (13) or by a filter pocket. A filter apparatus, which is also suitable in particular for carrying out the abovementioned process, has a filter which is equipped with a migrating bed (11) charged with migrating filter material (15). In this case, this filter apparatus (1) has at least one further filter medium, which the migrating filter material (15) of the migrating bed passes by. In this case, this filter medium is formed for example by a filter bag (13) conically tapering downwards. A plurality of filter apparatuses (1) can be incorporated in a filter unit. A particularly compact filter unit is obtained if the individual filter apparatuses are designed as parallelepipeds and arranged in parallel next to each other.