VERFAHREN ZUR HERSTELLUNG VON NEUEN INDOL-5-CARBOXAMIDDERIVATEN, DEREN SALZEN UND HYDRATEN

In a filter unit for hot dust-laden crude gases, a plurality of filter chambers (4) are attached on the crude gas side to a collective crude gas line (1) and to an unpressurised dust collection vessel (5). On the clean gas side, they open out into a clean gas manifold (14) and can individually be impinged from a backflow line (23) each for cleaning their filter bodies (7). In order to be able to filter hot crude gases directly at a superatmospheric pressure of, for example, 2 to 3 bar, an effective cleaning of the filter bodies (7) is necessary. For this purpose it is proposed to connect the filter chambers (4) in an unpressurised state on the crude gas side for cleaning and to use the pressurised clean gas itself, or ambient air pressurised by the crude gas, for backflushing.