Device and method and device for moisture-controlled blow-off after the application of a layer onto a flat steel product

Device (150) for applying a ZnAlMg layer or a ZnAl layer (10) to a flat steel product (100), comprising:

• a zinc alloy melt bath (11) with an input side (E) and an exit side (A),
• a dry gas supply (18) configured to provide a dry gas stream (TG),
• a water vapor device (50) configured to provide water vapor gas (WG),
• means (20) for determining gas humidity and/or moisture content,
• a stripping nozzle device (14) which is fluidically connected to the gas supply (18) and to the water vapor device (50) in order to supply the stripping nozzle device (14) with a stripping gas (AG) as a mixture of the dry gas stream (TG) and the gaseous water vapor (WG), wherein
• the stripping nozzle device (14) comprises at least one gas nozzle (15) for blowing off the front side (V) and at least one gas nozzle (15) for blowing off the back side (R) of the flat steel product (100) with the stripping gas (AG),
• the gas nozzles (15) are arranged in the region of the exit side (A) of the zinc alloy melt bath (11),
• the means (20) for determining gas humidity and/or moisture content are arranged in or at the stripping nozzle device (14) in order to determine the gas humidity before or when the stripping gas (AG) exits in direction of the front side (V) or back side (R) of the flat steel product (100), and wherein at least one of the following two conditions B1, B2 is met:
• B1:
• the stripping gas (AG) has a moisture content, or a proportion of the gaseous water vapor gas (WG), that is greater than 200 ppm and less than 43700 ppm, with the moisture content preferably being in the range 500 ppm to 9980 ppm,
• B2:
• the stripping gas (AG) has a dew point (TP) that is greater than −39° C. and less than +30° C., with the dew point (TP) preferably being in the range between −29° C. and +7° C.