Approach flow system

Abstract

The invention relates to an arrangement for feeding a fibrous suspension ( 1 ) to at least one headbox ( 8 ) of a paper or cardboard machine with at least one diluting device ( 5 ), in which the fibrous suspension ( 1 ) is produced by mixing a high-consistency suspension ( 6 ) with a diluting liquid, wherein the diluting liquid is formed at least in part by backwater ( 2 ) of the paper or cardboard machine, the backwater ( 2 ) is pre-degassed in at least one open channel ( 3 ) and subsequently is guided into a diluting device ( 5 ) via a degassing device ( 4 ). The expenditure is to be reduced thereby in that the potential energy of the fibrous suspension ( 1 ) in the channel ( 3 ) is not above the potential energy of the fibrous suspension ( 1 ) in the diluting device ( 5 ) and the pressure at the outflow of the degassing device ( 4 ) is between −0.3 and 1 bar or that the potential energy of the fibrous suspension ( 1 ) in the channel ( 3 ) is above the potential energy of the fibrous suspension ( 1 ) in the diluting device ( 5 ).

1 . An arrangement for feeding a fibrous suspension ( 1 ) to at least one headbox ( 8 ) of a paper or cardboard machine with at least one diluting device ( 5 ), in which the fibrous suspension ( 1 ) is produced by mixing a high-consistency suspension ( 6 ) with a diluting liquid, wherein the diluting liquid is formed at least in part by backwater ( 2 ) of the paper or cardboard machine, the backwater ( 2 ) is pre-degassed in at least one open channel ( 3 ) and subsequently is guided into a diluting device ( 5 ) via a degassing device ( 4 ), characterized in that the potential energy of the fibrous suspension ( 1 ) in the channel ( 3 ) is not above the potential energy of the fibrous suspension ( 1 ) in the diluting device ( 5 ) and the pressure at the outflow of the degassing device ( 4 ) is between −0.3 and 1 bar. 
     
     
         2 . An arrangement for feeding a fibrous suspension ( 1 ) to at least one headbox ( 8 ) of a paper or cardboard machine with at least one diluting device ( 5 ), in which the fibrous suspension ( 1 ) is produced by mixing a high-consistency suspension ( 6 ) with a diluting liquid, wherein the diluting liquid is formed at least in part by backwater ( 2 ) of the paper or cardboard machine, the backwater ( 2 ) is pre-degassed in at least one open channel ( 3 ) and subsequently is guided into a diluting device ( 5 ) via a degassing device ( 4 ), characterized in that the potential energy of the fibrous suspension ( 1 ) in the channel ( 3 ) is above the potential energy of the fibrous suspension ( 1 ) in the diluting device ( 5 ). 
     
     
         3 . The arrangement according to  claim 2 , characterized in that the difference of the potential energy of the fibrous suspension ( 1 ) in the channel ( 3 ) and the diluting device ( 5 ) corresponds to no more than an equivalent of 8 m difference in height. 
     
     
         4 . The arrangement according to  claim 1 , characterized in that the pressure at the outflow of the degassing device ( 4 ) is higher than the pressure at the inflow ( 19 ) of the diluting device ( 5 ). 
     
     
         5 . The arrangement according to  claim 1 , characterized in that the pressure at the outflow ( 15 ) of the degassing device ( 4 ) is no more than 0.5 bar less than the pressure at the inflow ( 19 ) of the diluting device ( 5 ) and a pump is arranged between the degassing device ( 4 ) and the diluting device ( 5 ). 
     
     
         6 . The arrangement according to  claim 1 , characterized in that the fibrous suspension flow ( 1 ) between the channel ( 3 ) and the degassing device ( 4 ) is preferably restricted in a changeable manner. 
     
     
         7 . The arrangement according to  claim 1 , characterized in that the fibrous suspension flow ( 1 ) between the degassing device ( 4 ) and the diluting device ( 5 ) is preferably restricted in a changeable manner. 
     
     
         8 . The arrangement according to  claim 1 , characterized in that the inflow ( 16 ) of the degassing device ( 4 ) is arranged above the channel ( 3 ). 
     
     
         9 . The arrangement according to  claim 1 , characterized in that the outflow ( 15 ) of the degassing device ( 4 ) is arranged above the inflow ( 19 ) of the backwater ( 2 ) into the diluting device ( 5 ). 
     
     
         10 . The arrangement according to  claim 1 , characterized in that the degassing device ( 4 ) is connected to a vacuum source ( 7 ). 
     
     
         11 . The arrangement according to  claim 10 , characterized in that the degassing device ( 4 ) has a rotating rotor ( 13 ), in the interior of which the backwater ( 2 ) is guided, wherein the gas collecting in the center due to centrifugal forces is suctioned by the vacuum source ( 7 ). 
     
     
         12 . The arrangement according to  claim 1 , characterized in that the diluting device ( 5 ) is embodied as a closed container. 
     
     
         13 . The arrangement according to  claim 1 , characterized in that the diluting device ( 5 ) is embodied as an open container. 
     
     
         14 . The arrangement according to  claim 1 , characterized in that after the diluting device ( 5 ), the fibrous suspension ( 1 ) is guided via a stock pump ( 9 ). 
     
     
         15 . The arrangement according to  claim 14 , characterized in that the stock pump ( 9 ) guides the fibrous suspension ( 1 ) to the headbox  8  in a closed system. 
     
     
         16 . A method for starting up an arrangement according to  claim 14 , characterized in that the stock pump ( 9 ) is started before start-up of the degassing device ( 4 ).