Patent ID: 7673395

Claim:
A dryer bar apparatus of a dryer for drying a web in a papermaking machine, said apparatus comprising: a rotatable dryer shell of cylindrical configuration, said dryer shell having an outer surface for drying the web; said dryer shell having an inner surface which defines an enclosure, said inner surface having a radius Ri; said enclosure being connected to a source of pressurized steam such that in operation of the dryer, a transfer of thermal energy from the steam within said enclosure through said inner surface of said dryer shell to said outer surface of said dryer shell is achieved so that the web is dried; a syphon disposed within said enclosure for controlling a layer of condensed steam accumulating adjacent to said inner surface of said dryer shell during operation of said apparatus; a specific number of turbulence bars disposed within said enclosure for maximizing uniformity of said transfer of thermal energy in a cross machine direction and minimizing said transfer of thermal energy through said dryer shell from said inner to said outer surface, each of said turbulence bars extending in a cross machine direction in contact with said inner surface, said bars being circumferentially spaced equidistantly around said inner surface of said dryer shell for generating turbulence within said layer so that uniformity of said transfer of thermal energy in said cross machine direction is maximized while said transfer of thermal energy through said dryer shell from said inner to said outer surface is minimized; and said maximizing uniformity of said transfer of thermal energy in said cross machine direction and minimizing said transfer of thermal energy through said dryer shell from said inner to said outer surface being attained by the fitting of said specific number of turbulence bars within said dryer shell; said specific number of turbulence bars being determined by the equation: N =int{[2π Ri/[ 4π( Ri δ) 1/2 W]} in which: N=said specific number of turbulence bars in said dryer shell; int=an integer number of a value in { } brackets; π=3.1415; Ri=said inside radius of said inner surface of said dryer shell in inches; δ=an average depth of said layer in inches; W=a width of each of said turbulence bars in inches.