The present disclosure deals with a gas cleaning system (1) for cleaning process flue gas. The gas cleaning system (1) comprises a reactor inlet duct (13) having a longitudinal axis and a reactor duct (14) fluidly connected perpendicularly to the reactor inlet duct and positioned downstream from the reactor inlet duct. The reactor duct likewise has a longitudinal axis. Within the reactor duct is a gas cleaning device (20), such as a catalytic reactor, and a gas flow rectifier (30) for rectifying flue gas flow from the reactor inlet duct (13) into the reactor duct (14). The gas flow rectifier is arranged in the reactor duct upstream of the gas cleaning device (20), wherein the gas flow rectifier (30) comprises at least one expanded screen (30a).

Aspects of the present disclosure include a protective mask to be worn over a nose and mouth of a wearer to protect the wearer from hazards in surrounding ambient air. The mask includes a mask portion, an airway, and an ionization filter. The mask portion includes an interior that extends over the nose and mouth of the wearer. The airway extends between the interior of the mask portion and the surrounding ambient air. The ionization filter includes an emitter within a portion of the airway, and a collector plate radially encompassing the emitter and defining at least a portion of the airway. The collector plate is electrically connected to at least first and second conductive porous filters. The first and second conductive porous filters and the collector plate collectively form at least a portion of a Faraday cage that encapsulates the emitter.

Aspects of the present disclosure include a protective mask to be worn over a nose and mouth of a wearer to protect the wearer from hazards in surrounding ambient air. The mask includes a mask portion, an airway, and an ionization filter. The mask portion includes an interior that extends over the nose and mouth of the wearer. The airway extends between the interior of the mask portion and the surrounding ambient air. The ionization filter includes an emitter within a portion of the airway, and a collector plate radially encompassing the emitter and defining at least a portion of the airway. The collector plate is electrically connected to at least first and second conductive porous filters. The first and second conductive porous filters and the collector plate collectively form at least a portion of a Faraday cage that encapsulates the emitter.