Machine and method for manufacturing tissue paper

Abstract

The machine ( 10 ) comprises a Yankee cylinder ( 35 ), having a cylindrical side surface ( 35 S), rotating around an axis ( 35 A) thereof, and a continuous flexible member ( 17 ) comprising a first surface ( 17 A) suitable to receive a layer of cellulose pulp (S), comprising cellulose fibers and water, and a second surface ( 17 B), opposite to the first surface ( 17 A). A guide roller ( 31 ) is also provided, around which the continuous flexible member ( 17 ) is driven. The second surface ( 17 B) of the continuous flexible member ( 17 ) is in contact with the first guide roller ( 31 ). The machine further comprises a first pressure roller ( 33 ) around which the continuous flexible member ( 17 ) is driven, arranged downstream of the guide roller ( 31 ) with respect to a feeding direction of the layer of cellulose pulp (S). The first pressure roller ( 33 ) and the Yankee cylinder ( 35 ) define a first pressure nip ( 34 ), inside which the continuous flexible member ( 17 ) is pressed by means of the first pressure roller ( 33 ) against the cylindrical surface ( 35 S) of the Yankee cylinder ( 35 ) in order to remove water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 ).

1 . A machine ( 10 ) for wet manufacturing of tissue paper, comprising in combination:
 a Yankee cylinder ( 35 ) comprising a cylindrical side surface ( 35 S), rotating around an axis ( 35 A) thereof;   a continuous flexible member ( 17 ) comprising a first surface ( 17 A) suitable to receive a layer of cellulose pulp (S), comprising cellulose fibers and water, and a second surface ( 17 B), opposite to the first surface ( 17 A);   a guide roller ( 31 ), around which the continuous flexible member ( 17 ) is driven; wherein the second surface ( 17 B) of the continuous flexible member ( 17 ) is in contact with the first guide roller ( 31 ); wherein, in the area guided around the guide roller ( 31 ), the first surface ( 17 A) of the continuous flexible member ( 17 ) is spaced from the Yankee cylinder ( 35 ); and wherein the guide roller ( 31 ) is suitable to remove water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 );   a first pressure roller ( 33 ) around which the continuous flexible member ( 17 ) is driven, arranged downstream of the guide roller ( 31 ) with respect to a feeding direction of the layer of cellulose pulp (S); wherein the first pressure roller ( 33 ) and the Yankee cylinder ( 35 ) define a first pressure nip ( 34 ), inside which the continuous flexible member ( 17 ) is pressed by means of the first pressure roller ( 33 ) against the cylindrical surface ( 35 S) of the Yankee cylinder ( 35 ); and wherein the first pressure roller ( 33 ) is suitable to remove water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 ).   
     
     
         2 . The machine ( 10 ) of  claim 1 , wherein the guide roller ( 31 ) is a suction roller. 
     
     
         3 . The machine ( 10 ) of  claim 2 , wherein the guide roller ( 31 ) comprises an outer cylindrical skirt ( 39 ) provided with a plurality of through holes ( 51 ) connecting an outer surface of the guide roller and an inner suction chamber ( 43 . 2 ) of the guide roller ( 31 ). 
     
     
         4 . The machine ( 10 ) of  claim 3 , wherein the suction chamber ( 43 . 2 ) extends for a portion of the circumferential extension of the suction roller ( 31 ) and is arranged in a stationary position with respect to the rotation axis ( 31 A) of the guide roller ( 31 ), so as to generate a suction area through the through holes ( 51 ) of the cylindrical skirt ( 39 ), the suction area being fixed with respect to the path of the continuous flexible member. 
     
     
         5 . The machine ( 10 ) of  claim 4 , wherein the suction chamber ( 43 . 2 ) is arranged in an area of the guide roller ( 31 ) that is in contact with the continuous flexible member ( 17 ), so as to generate suction of water contained in the layer of cellulose pulp (S), through the flexible member ( 17 ) in the through holes. 
     
     
         6 . The machine ( 10 ) of  claim 5 , wherein inside the cylindrical skirt ( 39 ) an annular volume ( 43 ) is arranged, fluidly connected to the through holes ( 51 ), the annular volume ( 43 ) being subdivided into said suction chamber ( 43 . 2 ) and a non-suction area ( 43 . 1 ), so that water is temporarily sucked in the through holes ( 51 ) when they pass in front of the suction chamber ( 43 . 2 ) and is removed from the through holes ( 51 ) due to the centrifugal effect when the through holes pass along the non-suction area ( 43 . 1 ) of the annular volume ( 43 ). 
     
     
         7 . The machine ( 10 ) of one or more of the previous claims, wherein the first pressure roller ( 33 ) is a pressure roller with dead holes ( 57 ). 
     
     
         8 . The machine ( 10 ) of one or more of the  claims 1  to  6 , wherein the first pressure roller comprises an outer cylindrical skirt provided with a plurality of through holes connecting an outer surface of the first pressure roller and an inner suction chamber of the first pressure roller; wherein preferably the suction chamber extends for a portion of the circumferential extension of the first pressure roller and is arranged in stationary position with respect to the axis of the first pressure roller, so as to generate a suction area through the through holes of the cylindrical skirt, the suction area being fixed with respect to the path of the continuous flexible member ( 17 ); and wherein preferably the suction chamber is arranged in an area of the first pressure roller that is in contact with the continuous flexible member ( 17 ), so as to generate suction of water contained in the layer of cellulose pulp (S), through the flexible member ( 17 ) in the through holes; and wherein preferably inside the cylindrical skirt an annular volume is arranged, fluidly connected to the through holes, the annular volume being subdivided into said suction chamber and a non-suction area, so that water is temporarily sucked in the through holes when they pass in front of the suction chamber and is removed from the through holes due to the centrifugal effect when the through holes pass along the non-suction area of the annular volume. 
     
     
         9 . The machine ( 10 ) of one or more of the previous claims, further comprising a second pressure roller ( 61 ), around which the continuous flexible member ( 17 ) is driven, arranged downstream of the first pressure roller ( 33 ) with respect to the feeding direction of the layer of cellulose pulp (S); wherein the second pressure roller ( 61 ) and the Yankee cylinder ( 35 ) define a second pressure nip ( 63 ), inside which the continuous flexible member ( 17 ) is pressed by means of the second pressure roller ( 61 ) against the cylindrical surface ( 35 S) of the Yankee cylinder ( 35 ); and wherein the second pressure roller ( 61 ) is adapted to remove water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 ). 
     
     
         10 . The machine ( 10 ) of  claim 9 , wherein the second pressure roller ( 61 ) has the same structure as the first pressure roller. 
     
     
         11 . The machine ( 10 ) of  claim 9 , wherein the second pressure roller has a different structure than the first pressure roller, and in particular one of the two pressure rollers has a dead holes configuration whilst the other of the two pressure rollers has a through holes configuration. 
     
     
         12 . The machine ( 10 ) of one or more of the previous claims, comprising a heating device adapted to act on said continuous flexible member ( 17 ) and arranged between said guide roller ( 31 ) and said first pressure roller ( 33 ). 
     
     
         13 . The machine ( 10 ) of  claim 12 , wherein said heating device faces said first surface ( 17 A) carrying the layer of cellulose pulp (S). 
     
     
         14 . The machine ( 10 ) of  claim 12  or  13 , wherein said heating device is a steam heating device and/or an infrared heating device and/or a microwave heating device and/or and electrical heating device, for instance a device for heating through resistance and/or electrical induction. 
     
     
         15 . The machine ( 10 ) of one or more of  claims 12  to  14 , wherein said heating device comprises a steam box adapted to blow steam directly onto said continuous flexible member ( 17 ) carrying the layer of cellulose pulp (S). 
     
     
         16 . The machine ( 10 ) of one or more of  claims 12  to  15 , wherein said heating device comprises a thermal radiation plate facing said continuous flexible member ( 17 ) carrying the layer of cellulose pulp (S). 
     
     
         17 . The machine ( 10 ) of one or more of the previous claims, further comprising a forming wire ( 15 ), adapted to receive the layer of cellulose pulp (S) from a headbox ( 11 ), and configured to transfer, directly or indirectly, the layer of cellulose pulp (S) to the continuous flexible member ( 17 ). 
     
     
         18 . The machine ( 10 ) of one or more of the  claims 1  to  11 , comprising a forming wire ( 15 ), driven around a forming drum ( 19 ), around which also said continuous flexible member ( 17 ) is driven, to form, between the continuous flexible member ( 17 ) and the forming wire ( 15 ), a volume for receiving cellulose pulp from a headbox. 
     
     
         19 . The machine ( 10 ) of one or more of  claims 12  to  15  and one of  claims 16  and  17 , wherein said guide roller ( 31 ) and said heating device are arranged downstream of the area where said forming wire ( 15 ) is separated from said continuous flexible member ( 17 ). 
     
     
         20 . The machine ( 10 ) of one or more of the previous claims, wherein said heating device comprises an air suction module arranged preferably at opposite side from the continuous flexible member and facing it. 
     
     
         21 . The machine ( 10 ) according to one or more of the previous claims, comprising a further heating device arranged immediately upstream of the guide roller. 
     
     
         22 . A method for removing water from a layer of cellulose pulp (S) comprising water and cellulose fibers, the method comprising the following steps:
 forming a layer of cellulose pulp (S) comprising water and cellulose fibers on a first surface ( 17 A) of a continuous flexible member ( 17 );   feeding the layer of cellulose pulp (S) towards a Yankee cylinder ( 35 );   driving the continuous flexible member ( 17 ) around a guide roller ( 31 ), the continuous flexible member ( 17 ) having a second surface ( 17 B) in contact with the guide roller ( 31 ), and removing water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 ) by means of the guide roller ( 31 ), with no contact between the layer of cellulose pulp (S) and the Yankee cylinder ( 35 );   downstream of the guide roller ( 31 ), feeding the layer of cellulose pulp (S) in a first pressure nip ( 34 ) defined by the Yankee cylinder ( 35 ) and by a first pressure roller ( 33 ), around which the continuous flexible member ( 17 ) is driven with the second surface ( 17 B) in contact with the first pressure roller ( 33 ), and removing water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 ) by means of the first pressure roller ( 33 ).   
     
     
         23 . The method of  claim 22 , further comprising the following step: downstream of the first pressure roller ( 33 ), feeding the layer of cellulose pulp (S) in a second pressure nip ( 63 ) defined by the Yankee cylinder ( 35 ) and by a second pressure roller ( 61 ), around which the continuous flexible member ( 17 ) is driven with the second surface ( 17 B) in contact with the second pressure roller ( 61 ), and removing water from the layer of cellulose pulp (S) through the continuous flexible member ( 17 ) by means of the second pressure roller ( 61 ). 
     
     
         24 . The method of  claim 22  or  23 , further comprising a drying step through heating of said layer of cellulose pulp (S) between the are where the continuous flexible member ( 17 ) is driven around the guide roller ( 31 ) and said first pressure nip ( 34 ). 
     
     
         25 . The method of  claim 24 , wherein said drying step occurs through heating generated by means of steam emitted onto said layer of cellulose pulp (S), or through thermal radiation.