Method and device in a paper or board machine

Abstract

The invention relates to a method in a paper or board machine, in which method water is removed from a paper or board web (W) by pressing in a press section ( 30 ), in which pressing stage the web (W) is pressed in at least one press nip ( 35; 36 ), and in which method the web (W) is dried after pressing by impingement drying, in which method the web (W) is passed as a closed draw from the press section ( 30 ) to a dryer section ( 40 ), and the method applies full-width threading from the press section ( 30 ) to the dryer section ( 40 ). The web (W) is dried by impingement drying by means of impingement units ( 46 ) placed around at least one large-diameter impingement roll ( 45 ). In the method, the web (W) is passed after impingement drying as a closed draw through the dryer section ( 40 ) to a calender ( 60 ), and in the method threading is accomplished as of full width through the dryer section ( 40 ). The invention also relates to a device in a paper or board machine, which device comprises at least one press nip ( 35, 36 ) and an impingement roll ( 45 ) and impingement drying unit ( 46 ) arranged in connection therewith and means ( 36 A, 38, 36 Y) for passing a web from a press section ( 30 ) onto the impingement drying roll ( 45 ) as a closed draw, as well as means for accomplishing threading. Means ( 50, 51 ) for passing the web (W) as a closed draw to a calender ( 60 ) and means for accomplishing full-width threading through a dryer section are arranged after the impingement roll ( 45 ).

1 . A method in a paper or board machine, in which method water is removed from a paper or board web (W) by pressing in a press section ( 30 ), in which pressing stage the web (W) is pressed in at least one press nip ( 35 ;  36 ), and in which method the web (W) is dried after pressing by impingement drying, in which method the web (W) is passed as a closed draw from the press section ( 30 ) to a dryer section ( 40 ), and the method applies full-width threading from the press section ( 30 ) to the dryer section ( 40 ), characterized in that the web (W) is dried by impingement drying by means of impingement units ( 46 ) placed around at least one large-diameter impingement roll ( 45 ), that in the method the web (W) is passed after impingement drying as a closed draw through the dryer section ( 40 ;  40 ′) to a calender ( 60 ), and that in the method threading is accomplished as of full width through the dryer section ( 40 ;  40 ′).  
     
     
         2 . A method according to  claim 1 , characterized in that, in the method, threading is accomplished as of full width from the press section ( 30 ) to the dryer section ( 40 ) and through the dryer section ( 40 ;  40 ′) and further to the calender ( 60 ).  
     
     
         3 . A method according to  claim 2 , characterized in that, in the method, the threading of the web (W) is accomplished as of full width to a reel ( 70 ).  
     
     
         4 . A method according to  claim 1 , characterized in that, in the method, the web (W) is passed as a closed draw to the reel ( 70 ).  
     
     
         5 . A method according to  claim 1 , characterized in that, in the method, the web (W) is dried on the impingement roll ( 45 ) by means of the impingement units ( 46 ) arranged in connection therewith, the properties of the web (W) are measured by means of a measuring beam ( 47 ) arranged in connection with the impingement roll ( 45 ), the moisture profile of the web (W) is profiled by means of a profiling unit ( 42 ) arranged in connection with the impingement roll ( 45 ), the curl of the web (W) is controlled by means of a curl control device ( 43 ) arranged in connection with the impingement roll ( 45 ), and after that the web (W) is transferred on a transfer suction roll ( 51 ) to the calender ( 60 ) by means of a transfer fabric ( 50 ) as a substantially closed draw.  
     
     
         6 . A method according to  claim 1  or  2 , characterized in that the web (W) is calendered in a belt calender (FIGS. 2, 4,  6 ).  
     
     
         7 . A method according to  claim 1  or  2 , characterized in that the web (W) is calendered in a multi-nip calender (FIGS. 5, 7,  8 ).  
     
     
         8 . A method according to  claim 1  or  2 , characterized in that the web (W) is calendered in a single-nip calender (FIG. 3).  
     
     
         9 . A method according to  claim 1 , characterized in that the web (W) is dried on the impingement roll ( 45 ) by means of the impingement units ( 46 ), the web (W) is passed from impingement drying to a sizing/coating unit ( 80 ), after which the web (W) is transferred on a transfer fabric ( 82 ) to impingement drying onto a large-diameter roll ( 45 ′) having impingement units ( 46 ′) arranged in connection therewith, and that the web (W) is passed to the calender ( 60 ) by means of a transfer fabric ( 50 ), and that the web (W) is reeled on a reel ( 70 ).  
     
     
         10 . A method according to any one of  claims 1  to  9 , characterized in that, in the method, the web (W) is passed from the press ( 30 ) to impingement drying on the surface of a fabric ( 36 A;  36 Y) of the last press nip ( 36 ) of the press, and that the web is detached from the fabric by means of a transfer suction roll ( 38 ), the web being transferred on a transfer fabric ( 39 ) arranged in connection with said transfer suction roll onto a drying wire ( 41 ) of the large-diameter impingement roll ( 45 ) used in impingement drying.  
     
     
         11 . A method according to any one of  claims 1  to  9 , characterized in that, in the method, the web (W) is transferred from a press fabric ( 36 A,  36 Y) onto a drying wire ( 41 ) of the large-diameter impingement roll ( 45 ) used in impingement drying.  
     
     
         12 . A device in a paper or board machine, which device comprises at least one press nip ( 35 ,  36 ) and an impingement roll ( 45 ) and impingement drying units ( 46 ) arranged in connection therewith and means ( 36 A,  38 ,  31 ,  36 Y) for passing a web from a press section ( 30 ) onto the impingement drying roll ( 45 ) as a closed draw, as well as means for accomplishing threading, characterized in that means ( 50 ,  51 ) for passing the web (W) as a closed draw to a calender ( 60 ) and means for accomplishing full-width threading through a dryer section are arranged after the impingement roll ( 45 ).  
     
     
         13 . A device according to  claim 12 , characterized in that the device comprises a measuring beam ( 47 ), a profiling unit ( 42 ) and/or a curl control device ( 43 ) arranged in connection with the impingement roll ( 45 ).  
     
     
         14 . A device according to  claim 12  or  13 , characterized in that the calender ( 60 ) is a belt calender.  
     
     
         15 . A device according to  claim 12  or  13 , characterized in that the calender ( 60 ) is a shoe calender.  
     
     
         16 . A device according to  claim 12  or  13 , characterized in that the calender ( 60 ) is a multi-nip calender.  
     
     
         17 . A device according to  claim 12  or  13 , characterized in that the calender ( 60 ) is a single-nip calender.  
     
     
         18 . A device according to  claim 12 , characterized in that the device comprises a sizing/coating unit ( 80 ) which is placed between two large-diameter impingement rolls ( 45 ,  45 ′) and that means ( 51 ,  50 ) for passing the web (W) as a closed draw to the calender ( 60 ) are placed after the latter impingement roll ( 45 ′).  
     
     
         19 . A device according to  claim 12 , characterized in that the device comprises a reel ( 70 ) to which the web can be passed as a closed draw by means of a transfer fabric ( 63 ) arranged around a belt roll ( 62 ) of the calender ( 60 ).  
     
     
         20 . A device according to  claim 12  or  13 , characterized in that a transfer fabric ( 39 ) is arranged between the press section ( 30 ) and the dryer section ( 40 ) based on impingement drying, a transfer suction roll ( 38 ) being provided in connection with said transfer fabric for passing the web from the press section ( 30 ) to the dryer section ( 40 ).  
     
     
         21 . A device according to  claim 12  or  13 , characterized in that the web (W) is arranged to be passed from the press section ( 30 ) to the dryer section ( 40 ) based on impingement drying by means of a press fabric running through a press nip ( 36 ) of the press.  
     
     
         22 . A device according to  claim 12  or  13 , characterized in that the device comprises a transfer fabric ( 50 ) for passing the web (W) from the dryer section ( 40 ;  40 ′) based on impingement drying to the calender ( 60 ).  
     
     
         23 . A device according to  claim 22 , characterized in that a measuring device ( 59 ,  59 ′) is arranged in connection with the transfer fabric for measuring the properties of the web (W).  
     
     
         24 . A device according to  claim 12  or  13 , characterized in that the device further comprises a transfer fabric ( 63 ) for passing the web from the calender ( 60 ) to a reel ( 70 ).  
     
     
         25 . A device according to  claim 12  or  13 , characterized in that the device comprises vacuum boxes ( 37 ) for keeping the web in contact with a transfer fabric ( 39 ).  
     
     
         26 . A device according to  claim 12  or  13 , characterized in that, in the device, the draw from the calender ( 60 ) to a reel ( 70 ) is closed.