Apparatus and method for treating a fibrous material web in a long nip press unit

Abstract

The invention relates to an apparatus and a method for treating a fibrous material web ( 9 ) in a paper or cardboard machine in a long nip press unit ( 29 ) comprising a press roll ( 24 ), which has a rotating press jacket ( 25 ) and a mating roll ( 23 ), wherein the fibrous material web ( 9 ) is dewatered in an extended press nip ( 26 ) between the mating roll ( 23 ) and the press jacket ( 25 ) of the press roll ( 24 ). According to the invention, the fibrous material web ( 9 ) is guided after the extended press nip ( 26 ) on a special rotating press jacket ( 25 ) of the press roll ( 24 ) to a transfer region ( 30 ), in which the fibrous material web ( 9 ) is transferred from the press jacket ( 25 ) to a transfer element ( 31, 27 ).

1 . A press arrangement of a paper or board machine for treating a pulp web ( 9 ), in which
 the pulp web ( 9 ) is guided through an extended press nip ( 26 ) of a long-nip pressing unit ( 29 ),   the long-nip pressing unit ( 29 ) has a press roll ( 24 ) in the form of a shoe press with a revolving press belt ( 25 ) and an opposing roll ( 23 ),   the pulp web ( 9 ) is carried on the press belt ( 25 ) of the press roll ( 24 ) after the extended press nip ( 26 ) to a transfer element ( 31 ,  27 ) to which the pulp web ( 9 ) is transferred, wherein the improvement comprises that   the pulp web ( 9 ) is carried on a felt ( 33 ) to and through the extended press nip ( 26 ),   the revolving press belt ( 25 ) includes a supporting material and an elastic, compressible polymer layer,   the polymer layer has a surface that faces the pulp web and has a hardness between 50 and 97 Shore A, and   said surface of the polymer layer contacts the pulp web and has reversible, pressure-dependent roughness of R z =2-80 microns, measured in accordance with ISO 4287, when pressure-relieved and R z =0-20 microns when pressure-loaded with a line load of 20-600 kN/m.   
     
     
         2 . The press arrangement according to  claim 1 , wherein the revolving press belt ( 25 ) is essentially impermeable. 
     
     
         3 . The press arrangement according to  claim 1 , wherein the polymer layer is a polymer compound, selected from the group consisting of acrylic polymer resin, polyurethane polymer resin, and a compound of polyurethane and polycarbonate polymer resin. 
     
     
         4 . The press arrangement according to  claim 1 , wherein the polymer layer includes a particulate filler. 
     
     
         5 . The press arrangement according to  claim 1 , wherein the polymer layer completely encloses the supporting material. 
     
     
         6 . (canceled) 
     
     
         7 . The press arrangement according to  claim 2 , wherein the polymer layer is a polymer compound, selected from the group consisting of acrylic polymer resin, polyurethane polymer resin, and a compound of polyurethane and polycarbonate polymer resin. 
     
     
         8 . The press arrangement according to  claim 2 , wherein the polymer layer includes a particulate filler. 
     
     
         9 . The press arrangement according to  claim 2 , wherein the polymer layer completely encloses the supporting material. 
     
     
         10 . The press arrangement according to  claim 3 , wherein the polymer layer includes a particulate filler. 
     
     
         11 . The press arrangement according to  claim 4 , wherein the filler is selected from the group consisting of china clay, a polymer material, and a metal. 
     
     
         12 . The press arrangement according to  claim 8 , wherein the polymer layer completely encloses the supporting material. 
     
     
         13 . The press arrangement according to  claim 12 , wherein
 the polymer layer is a polymer compound, selected from the group consisting of acrylic polymer resin, polyurethane polymer resin, and a compound of polyurethane and polycarbonate polymer resin; and   the filler is selected from the group consisting of china clay, a polymer material, and a metal.   
     
     
         14 . A process for treating a pulp web ( 9 ) in a paper or board machine in a long-nip pressing unit ( 29 ) with one press roll ( 24 ) that is formed as a shoe press roll and which has a rotating press belt ( 25 ) and one opposing roll ( 23 ), wherein
 the pulp web ( 9 ) is dewatered in an extended press nip ( 26 ) between the opposing roll ( 23 ) and the press belt ( 25 ) of the press roll ( 24 ),   the pulp web ( 9 ) is carried on the rotating press belt ( 25 ) of the press roll ( 24 ), after the extended press nip ( 26 ) to a transfer zone ( 30 ) in which the pulp web ( 9 ) is transferred from the press belt ( 25 ) to a transfer element ( 31 ,  27 ),   the pulp web ( 9 ) is carried on a felt ( 33 ) to and through the extended press nip ( 26 ), in contact with the rotating press belt ( 25 ) which press belt ( 25 ) includes a supporting material and an elastic, compressible polymer layer,   the polymer layer has a surface that faces the pulp web and has a hardness between 50 and 97 Shore A, and   said surface of the polymer layer contacts the pulp web and has reversible, pressure-dependent roughness of R z =2-80 microns, measured in accordance with ISO 4287, when pressure-relieved and R z =0-20 microns when pressure-loaded with a line load of 20-600 kN/m.   
     
     
         15 . The process of  claim 14 , wherein the revolving press belt ( 25 ) is essentially impermeable 
     
     
         16 . The process of  claim 14 , wherein the polymer layer is a polymer compound, selected from the group consisting of acrylic polymer resin, polyurethane polymer resin, and a compound of polyurethane and polycarbonate polymer resin. 
     
     
         17 . The process of  claim 14 , wherein the polymer layer completely encloses the supporting material. 
     
     
         18 . The process of  claim 14 , wherein the polymer layer completely encloses the supporting material. 
     
     
         19 . The process of  claim 15 , wherein the polymer layer includes a particulate filler. 
     
     
         20 . The process of  claim 19 , wherein the polymer layer completely encloses the supporting material.