Drier for paper webs

Claim 2

Apparatus for the high speed continuous thermal treatment of webs of paper sheet material and the like comprising a pair of air permeable endless metallic conveyor belts of high thermal conductivity, means for supporting said endless belts in mutually engaged superimposed facing relationship along a portion of the length of said belts, said portion defining a common path of belt travel and constituting a web treating section having an inlet end and an outlet end to convey a web of material through said section while in sandwiched relation between said belts; each belt having a separate return path between said outlet and inlet ends and means along each return path for thermally pretreating each belt immediately in advance of mutual engagement of the belts at the inlet end of the web treating section said supporting means including a pair of closely spaced thermally controllable rolls in said web treating section adjacent said inlet end, the rolls in turn engaging the superimposed belts over an arcuate contacting area of greater than 180*.

Claim 3

A drier apparatus as in claim 1, in which, blow-through heater rolls guide said belts on said return runs to the inlet end of said conveyor section, said inlet lies against one of said heater rolls, and the blow-through area of each of said rolls is confined to form a preheating zone facing the area of single belt engagement therewith and comprises said means for thermally pretreating the belts.

Claim 4

The apparatus of claim 2, in which, said thermally controllable rolls are blow-through heater rolls positioned in vertically offset relation.

Claim 5

The apparatus of claim 3, in which, guide rolls at the outlet end of said conveyor section are vertically offset and engage the belts for the return run thereof back to the inlet end, and one of said outlet rolls urges said superimposed belts against the periphery of the other Outlet roll.

Claim 6

The apparatus of claim 4, in which, said pair of outlet guide rolls are blow-through rolls, each being axially adjustable to apply tension on the belts and in the area of single belt engagement therewith providing means to apply heat to the belt at the start of return travel.

Claim 7

The apparatus of claim 5, in which, a suction chamber is positioned opposite the area of said confined heating zone of each inlet guide roll and recirculating means are provided to reheat air drawn from said chamber and returned to said heating zone.

Claim 8

Apparatus for continuously drying a high speed running paper web comprising a pair of woven wire mesh endless conveyor belts of high heat conductivity, a series of guide rolls supporting travel of the belts in endless paths and bringing said belts together in superimposed relation along a conveyor path section to convey the web therebetween, certain of the rolls being adjustably mounted for belt tension and to exert squeezing action on a paper web between the belts in the areas of superimposed belt contact with the rolls, said series of rolls including matched sets of opposed closely spaced upper and lower blow-through heater rolls, each upper roll being vertically and forwardly offset above the corresponding roll of the lower set, such pairs of corresponding upper and lower rolls, respectively, providing return preheating rolls at the inlet end of said conveyor path section, intermediate rolls, and belt return rolls at the outlet end, said belts being arranged for travel on the rolls with said conveyor path section commencing at the forward undersurface of the upper inlet return roll, continuing upwardly around the upper intermediate roll, and then downwardly and rearwardly around the lower intermediate roll for passage to the outlet against the upper surface of said lower return outlet roll.

Claim 9

Apparatus for continuously drying a high speed running paper web comprising a pair of woven wire mesh endless conveyor belts of high heat conductivity, a series of guide rolls supporting travel of the belts in endless paths and bringing said belts together in superimposed relation along a conveyor path section to convey the web therebetween, certain of the rolls being adjustably mounted for belt tension and to exert squeezing action on a paper web between the belts in the areas of superimposed belt contact with the rolls, said series of rolls including matched sets of opposed closely spaced upper and lower blow-through heater rolls, each upper roll being vertically and forwardly offset above the corresponding roll of the lower set, such pairs of corresponding upper and lower rolls, respectively, providing return preheating rolls at the inlet end of said conveyor path section, intermediate rolls, and belt return rolls at the outlet end, said belts being arranged for travel on the rolls with said conveyor path section commencing at the forward undersurface of the upper inlet return roll, continuing upwardly around the upper intermediate roll, and then downwardly and rearwardly around the lower intermediate roll for passage to the outlet against the upper surface of said lower return outlet roll.