Method for determining retention of wire section in paper machine

Abstract

A method and apparatus for determining the retention of a wire section in a paper machine. The mass flow of a paper web on the wire section is determined by means of web properties measured after the wire section. In addition, the mass flow of a headbox and/or white water is determined. The retention of the wire section is determined on the basis of the mass flows of the paper web and the headbox and/or the mass flow of the white water.

1 . A method for determining the retention of a wire section in a paper machine, comprising: 
 determining the mass flow of a paper web on the wire section by means of paper web properties measured after the wire section;    determining the mass flow of a headbox and/or the mass flow of white water; and    determining the retention of the wire section on the basis of the mass flow of the paper web and the mass flow of the headbox and/or the mass flow of the white water.    
     
     
         2 . A method according to  claim 1 , wherein the retention of the wire section to be determined in the paper machine represents a total retention of the wire section.  
     
     
         3 . A method according to  claim 2 , wherein the mass flow of the paper web to be determined represents a total mass flow of the paper web on the wire section, the mass flow being determined on the basis of production corresponding to the dry weight of the paper web.  
     
     
         4 . A method according to  claim 3 , comprising: determining the mass flow of the white water, the mass flow of the white water to be determined representing a total mass flow of the white water determined on the basis of a headbox flow rate or a white water flow rate and a total consistency of the white water.  
     
     
         5 . A method according to  claim 4 , further comprising: 
 determining a total mass flow of the headbox on the basis of the total mass flow of the paper web and the total mass flow of the white water;    determining a total consistency of the headbox on the basis of the total mass flow of the headbox; and by    determining a total retention of the wire section on the basis of the total consistency of the headbox.    
     
     
         6 . A method according to  claim 3 , comprising: determining the mass flow of the headbox, the mass flow of the headbox to be determined representing the total mass flow of the headbox determined on the basis of the flow rate of the headbox and the total consistency of the headbox.  
     
     
         7 . A method according to  claim 6 , further comprising: 
 determining the total mass flow of the white water on the basis of the total mass flow of the paper web and the total mass flow of the headbox;    determining the total consistency of the white water on the basis of the total mass flow of the white water; and by    determining the total retention of the wire section on the basis of the total consistency of the white water.    
     
     
         8 . A method according to  claim 3 , comprising: determining both the mass flow of the headbox and the mass flow of the white water, the headbox mass flow to be determined representing the total mass flow of the headbox and the white water mass flow to be determined representing the total mass flow of the white water.  
     
     
         9 . A method according to  claim 8 , comprising: determining the total mass flow of the white water on the basis of the headbox flow rate or the white water flow rate and the measured total consistency of the white water and by determining the total mass flow of the headbox on the basis of the headbox flow rate and the measured total consistency of the headbox.  
     
     
         10 . A method according to  claim 8 , further comprising: 
 determining the total mass flow of the headbox on the basis of the total mass flow of the paper web and the total mass flow of the white water;    determining the total consistency of the headbox on the basis of the total mass flow of the headbox;    determining the total mass flow of the white water on the basis of the total mass flow of the paper web and the total mass flow of the headbox;    determining the total consistency of the white water on the basis of the total mass flow of the white water; and by    determining the total retention of the wire section on the basis of the total consistency of the headbox and the total consistency of the white water.    
     
     
         11 . A method according to  claim 2 , further comprising: determining a target value for the total consistency of the headbox on the basis of a total production target set for the production after the wire section or the total production after the wire section and a target value for the total retention of the wire section.  
     
     
         12 . A method according to  claim 2 , further comprising: determining a target value for the total consistency of the white water on the basis of a total production target set for the production after the wire section or the total production after the wire section and a target value for the total retention of the wire section.  
     
     
         13 . A method according to  claim 1 , wherein the retention of the wire section to be determined in the paper machine represents a filler retention of the wire section.  
     
     
         14 . A method according to  claim 13 , wherein the mass flow of the paper web to be determined represents the filler mass flow of the paper web on the wire section and it is determined on the basis of the amount of filler in the paper web.  
     
     
         15 . A method according to  claim 14 , comprising: determining the mass flow of the white water, the mass flow of the white water to be determined representing a filler mass flow of the white water determined on the basis of the headbox flow rate or the white water flow rate and the filler consistency of the white water.  
     
     
         16 . A method according to  claim 15 , further comprising: 
 determining a filler mass flow of the headbox on the basis of the filler mass flow of the paper web and the filler mass flow of the white water;    determining a filler consistency of the headbox on the basis of the filler mass flow of the headbox; and by    determining a filler retention of the wire section on the basis of the filler consistency of the headbox.    
     
     
         17 . A method according to  claim 14 , comprising: determining the mass flow of the headbox, the headbox mass flow to be determined representing the filler mass flow of the headbox determined on the basis of the headbox flow rate and the filler consistency of the headbox.  
     
     
         18 . A method according to  claim 17 , further comprising: 
 determining the filler mass flow of the white water on the basis of the filler mass flow of the paper web and the filler mass flow of the headbox;    determining the filler consistency of the white water on the basis of the filler mass flow of the white water; and by    determining the filler retention of the wire section on the basis of the filler consistency of the white water.    
     
     
         19 . A method according to  claim 14 , comprising: determining both the mass flow of the headbox and the mass flow of the white water, the headbox mass flow to be determined representing the filler mass flow of the headbox and the white water mass flow to be determined representing the filler mass flow of the white water.  
     
     
         20 . A method according to  claim 19 , comprising: determining the filler mass flow of the white water on the basis of the headbox flow rate or on the basis of the white water flow rate and the measured white water filler consistency and by determining the headbox filler mass flow on the basis of the headbox flow rate and the measured filler consistency of the headbox.  
     
     
         21 . A method according to  claim 19 , further comprising: 
 determining the filler mass flow of the headbox on the basis of the filler mass flow of the paper web and the filler mass flow of the white water;    determining the filler consistency of the headbox on the basis of the filler mass flow of the headbox;    determining the filler mass flow of the white water on the basis of the filler mass flow of the paper web and the filler mass flow of the headbox;    determining the filler consistency of the white water on the basis of the filler mass flow of the white water; and by    determining the filler retention of the wire section on the basis of the filler consistency of the headbox and the filler consistency of the white water.    
     
     
         22 . A method according to  claim 13 , further comprising: determining a target value for the filler consistency of the headbox on the basis of a production target set for the filler production after the wire section or on the basis of the filler production after the wire section and the target value for the filler retention of the wire section.  
     
     
         23 . A method according to  claim 13 , further comprising: determining a target value for the filler consistency of the white water on the basis of the production target set for the filler production after the wire section or on the basis of the filler production after the wire section and the target value for the filler retention of the wire section.  
     
     
         24 . A method for adjusting the retention of a wire section in a paper machine, in which method the retention of the wire section is adjusted by controlling the flow rate of a retention agent, comprising: 
 determining the mass flow of a paper web on the wire section by means of paper web properties measured after the wire section;    determining the mass flow of a headbox and/or the mass flow of white water;    determining the retention of the wire section on the basis of the mass flow of the paper web and the mass flow of the headbox and/or on the basis of the mass flow of the white water; and    adjusting the retention of the wire section by controlling the flow rate of the retention agent on the basis of the determined retention of the wire section.    
     
     
         25 . An apparatus for determining the retention of a wire section in a paper machine, the apparatus comprising: 
 means for determining the mass flow of a paper web on the wire section by means of the paper web properties measured after the wire section;    means for determining the mass flow of a headbox and/or the mass flow of white water; and    means for determining the retention of the wire section on the basis of the mass flow of the paper web and on the basis of the mass flow of the headbox and/or the mass flow of the white water.    
     
     
         26 . An apparatus according to  claim 25 , wherein the apparatus is configured to determine the total retention of the wire section.  
     
     
         27 . An apparatus according to  claim 26 , wherein the mass flow of the paper web to be determined represents the total mass flow of the paper web on the wire section, the headbox mass flow to be determined represents the total mass flow of the headbox and/or the white water mass flow to be determined represents the total mass flow of the white water.  
     
     
         28 . An apparatus according to  claim 27 , wherein the apparatus is configured to determine the total mass flow of the paper web on the basis of the production corresponding to the dry weight of the paper web.  
     
     
         29 . An apparatus according to  claim 27 , wherein the apparatus is configured to determine the total mass flow of the headbox on the basis of the flow rate of the headbox and the total consistency of the headbox and/or the apparatus is configured to determine the total mass flow of the white water on the basis of the headbox flow rate or the white water flow rate and the total consistency of the white water.  
     
     
         30 . An apparatus according to  claim 29 , wherein the apparatus further comprises 
 means for determining the total mass flow of the headbox on the basis of the total mass flow of the paper web and the total mass flow of the white water;    means for determining the total consistency of the headbox on the basis of the total mass flow of the headbox; and    means for determining the total retention of the wire section on the basis of the total consistency of the headbox.    
     
     
         31 . An apparatus according to  claim 29 , wherein the apparatus further comprises 
 means for determining the total mass flow of the white water on the basis of the total mass flow of the paper web and the total mass flow of the headbox;    means for determining the total consistency of the white water on the basis of the total mass flow of the white water; and    means for determining the total retention of the wire section on the basis of the total consistency of the white water.    
     
     
         32 . An apparatus according to  claim 29 , wherein the apparatus further comprises 
 means for determining the total mass flow of the headbox on the basis of the total mass flow of the paper web and the total mass flow of the white water;    means for determining the total consistency of the headbox on the basis of the total mass flow of the headbox;    means for determining the total mass flow of the white water on the basis of the total mass flow of the paper web and the total mass flow of the headbox;    means for determining the total consistency of the white water on the basis of the total mass flow of the white water; and    means for determining the total retention of the wire section on the basis of the total consistency of the headbox and the total consistency of the white water.    
     
     
         33 . An apparatus according to  claim 26 , wherein the apparatus further comprises means for determining a target value for the total consistency of the headbox on the basis of a total production target set for the production after the wire section or the total production after the wire section and a target value for the total retention of the wire section.  
     
     
         34 . An apparatus according to  claim 26 , wherein the apparatus further comprises means for determining a target value for the total consistency of the white water on the basis of the total production target for the production after the wire section or the total production after the wire section and the target value for the total retention of the wire section.  
     
     
         35 . An apparatus according to  claim 25 , wherein the apparatus is configured to determine the filler retention of the wire section.  
     
     
         36 . An apparatus according to  claim 35 , wherein the mass flow of the paper web to be determined represents a filler mass flow of the paper web on the wire section, the headbox mass flow to be determined represents a filler mass flow of the headbox and/or the mass flow of the white water to be determined represents a filler mass flow of the white water.  
     
     
         37 . An apparatus according to  claim 36 , wherein the apparatus is configured to determine the filler mass flow of the paper web on the basis of the amount of the filler in the paper web.  
     
     
         38 . An apparatus according to  claim 36 , wherein the apparatus is configured to determine the filler mass flow of the headbox on the basis of the headbox flow rate and the filler consistency of the headbox and/or that the apparatus is configured to determine the filler mass flow of the white water on the basis of the headbox flow rate or the white water flow rate and the filler consistency of the white water.  
     
     
         39 . An apparatus according to  claim 38 , wherein the apparatus further comprises 
 means for determining the filler mass flow of the headbox on the basis of the filler mass flow of the paper web and the filler mass flow of the white water;    means for determining the filler consistency of the headbox on the basis of the filler mass flow of the headbox; and    means for determining the filler retention of the wire section on the basis of the filler consistency of the headbox.    
     
     
         40 . An apparatus according to  claim 38 , the apparatus further comprising 
 means for determining the filler mass flow of the white water on the basis of the filler mass flow of the paper web and the filler mass flow of the headbox;    means for determining the filler consistency of the white water on the basis of the filler mass flow of the white water; and    means for determining the filler retention of the wire section on the basis of the filler consistency of the white water.    
     
     
         41 . An apparatus according to  claim 38 , the apparatus further comprising: 
 means for determining the filler mass flow of the headbox on the basis of the filler mass flow of the paper web and the filler mass flow of the white water;    means for determining the filler consistency of the headbox on the basis of the filler mass flow of the headbox;    means for determining the filler mass flow of the white water on the basis of the filler mass flow of the paper web and the filler mass flow of the headbox;    means for determining the filler consistency of the white water on the basis of the filler mass flow of the white water; and    means for determining the filler retention of the wire section on the basis of the filler consistency of the headbox and the filler consistency of the white water.    
     
     
         42 . An apparatus according to  claim 35 , the apparatus further comprising means for determining a target value for the filler consistency of the headbox on the basis of a production target set for the filler production after the wire section or on the basis of the filler production after the wire section and the target value for the filler retention of the wire section.  
     
     
         43 . An apparatus according to  claim 35 , the apparatus further comprising means for determining a target value for the filler consistency of the white water on the basis of the production target set for the filler production after the wire section or on the basis of the filler production after the wire section and the target value for the filler retention of the wire section.  
     
     
         44 . An apparatus for adjusting the retention of a wire section in a paper machine, the apparatus comprising: 
 means for determining the mass flow of a paper web on the wire section by means of paper web properties measured after the wire section;    means for determining the mass flow of a headbox and/or the mass flow of white water;    means for determining the retention of the wire section on the basis of the mass flow of the paper web and the mass flow of the headbox and/or the mass flow of the white water, and    means for adjusting the retention of the wire section by controlling the retention agent flow on the basis of the determined retention of the wire section.