Cooling device for blowing gas onto a surface of a traveling strip

A gas blower device for blowing gas onto a surface of a traveling strip, comprising:

• a plenum in the form of a hollow box for containing gas and comprising two side surfaces, a back surface and a front surface opposite the back surface, the front surface having a convex type profile, symmetric with respect to a mid-plane perpendicular to a plane of the strip, so that a middle ridge of the front surface is located at a smallest distance from the plane of the strip, the front surface further presenting a plurality of tubular nozzles protruding at the front surface and having a gas outlet orifice facing the traveling strip, all the outlet orifices being essentially in a plane parallel to the strip plane;
• a gas intake tube for feeding the plenum with gas;
• wherein all the tubular nozzles have the same length, the length being defined as a distance between the gas intake tube and the gas outlet orifice of each one of the plurality of tubular nozzles, so that a root or an inlet of each one of the plurality of tubular nozzles is located inside the plenum, each of the plurality of tubular nozzles passing without connection through an orifice inside the front surface, and having the root directly connected at a right angle to an internal connection plate within the plenum.