US Patent 7673395 Dryer bar apparatus of a dryer

A dryer bar apparatus of a dryer for drying a web in a papermaking machine includes a number of turbulence bars circumferentially spaced equidistantly around the inner surface of the dryer shell for generating turbulence within a layer of condensate. The arrangement is such that uniformity of the transfer of thermal energy in the cross machine direction is maximized while the transfer of thermal energy through the dryer shell from the inner to the outer surface is minimized. Also, the number of turbulence bars is determined by the equation:N=int{2πRi/[4π(Ri/d)½+W]}in which:N=the number of turbulence bars in the dryer shell;int=an integer number of a value in { } brackets;π=3.1415;Ri=the inside radius of the inner surface of the dryer shell in inches;d=an average depth of the layer in inches;W=a width of each of the turbulence bars in inches.