Paper production machine

Abstract

A paper production machine includes a sheet formation mechanism having a mixture chamber, a liquid flow line embodied to provide liquid flow to the mixture chamber, a valve for controlling liquid passage in the liquid flow line, and a control unit configured to provide controlling of the valve. The cellulose and liquid mixture, which is needed for production of the wet paper sheet, is kept in the mixture chamber. Accordingly, at least one pressure sensor is provided for measuring the liquid pressure in the mixture chamber. The pressure sensor is configured to transfer the pressure measurements to the control unit, and the control unit is configured to turn off the valve in case it is detected that the pressure measurements received from the pressure sensor exceeds at least one predetermined reference value.

What we claim is: 
     
         1 . A paper production machine, comprising a sheet formation mechanism comprising:
 a mixture chamber, configured for keeping a mixture of cellulose and liquid for production of a wet paper sheet;   a liquid flow line, embodied to provide liquid flow to the mixture chamber;   a first valve for controlling liquid passage in the liquid flow line; and   a control unit, configured to provide controlling of the first valve,   wherein at least one pressure sensor is provided for measuring a liquid pressure in the mixture chamber, and the at least one pressure sensor is configured to transfer pressure measurements to the control unit; and   wherein the control unit is configured to turn off the first valve when the pressure measurements received from the at least one pressure sensor exceeds at least one first predetermined reference pressure value.   
     
     
         2 . The paper production machine according to  claim 1 , further comprising a user interface configured to provide realization of command input to the control unit. 
     
     
         3 . The paper production machine according to  claim 1 , wherein the at least one pressure sensor is positioned in a vicinity of a base of the mixture chamber. 
     
     
         4 . The paper production machine according to  claim 1 , further comprising:
 a liquid discharge line for discharging the liquid in the mixture chamber,   a second valve connected to the liquid discharge line,   wherein the control unit is configured to operate the second valve for discharging the liquid in case the liquid is detected to exist in the mixture chamber and reach the at least one predetermined first reference pressure value.   
     
     
         5 . The paper production machine according to  claim 4 , wherein the control unit is embodied to provide opening of cover automatically in case a pressure measurement is taken with a second predetermined reference pressure value from the pressure measurements taken from the at least one pressure sensor. 
     
     
         6 . The paper production machine according to  claim 4 ,
 wherein the second valve is a three-way valve, and the three-way valve comprises a first end connected to the liquid discharge line, a second end connected to a vacuum line, and a third end connected to a free discharge line, and   wherein the three-way valve is configured to operate at a first position where water passage between the liquid ends is prevented optionally, at a second position where water passage between the first end and the second end is permitted, and at a third position where water passage between the first end and the third end is permitted.