| CPC B01D 46/2411 (2013.01) [G01N 1/2247 (2013.01)] | 10 Claims |
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1. A method, comprising:
conducting a process gas through a filter cartridge having a filter jacket which surrounds the filter cartridge, with the filter jacket functioning as a depth filter for purification of the process gas passing through the filter jacket to obtain a purified gas sample;
withdrawing the process gas via an inner tube located in the filter cartridge, with the filter cartridge projecting into a gas flow of the process gas;
conducting the purified gas sample via a gas sample line from the inner tube to a chilled mirror hygrometer, external from the filter cartridge, for determining an absolute humidity of the gas sample of the process gas;
connecting a backwash device to the inner tube;
introducing a purge gas into the inner tube for backwashing in order to remove particle deposits from an outer side of the filter cartridge; and
conducting the purge gas via a plurality of openings, arranged on a circumference of the inner tube, into an annular gap between an outer side of the inner tube and an inner side of the filter cartridge, with the openings being arranged at an opening spacing from an adjacent opening in a longitudinal direction, wherein the opening spacing is smaller at a first end of the inner tube than at a second end of the inner tube, so that more purge gas is conducted out of the inner tube in a region of the first end than in a region of the second end of the inner tube, with the first end projecting deeper into the gas flow of the process gas than the second end.
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