Arrangement for feeding pulp to a bleaching tower

Abstract

The present invention relates to an arrangement in connection with bleaching pulp having a consistency of 7-20%, preferably 8-16%, said arrangement comprising a bleaching tower having at least one inlet opening and at least one outlet opening for pulp, a transfer line comprising a feed line operatively connected to the inlet of the tower and a discharge line operatively connected to the outlet of the tower, and at least one pump arranged in the feed line. The arrangement further comprises at least two propeller or turbine type devices for increasing the pressure of the pulp flowing in the transfer line.

1 . An arrangement in connection with bleaching pulp having a consistency of 7-20%, preferably 8-16%, said arrangement comprising: 
 a bleaching tower having at least one inlet opening and at least one outlet opening for pulp,    a transfer line comprising a feed line operatively connected to the inlet of the tower and a discharge line operatively connected to the outlet of the tower, and    at least one pump arranged in the feed line, characterized in that the arrangement further comprises at least two propeller or turbine type devices for increasing the pressure of the pulp flowing in the transfer line.    
     
     
         2 . An arrangement according to  claim 1 , characterized in that at least one propeller or turbine type device is arranged in a chamber located in the feed line, said chamber having at least one inlet opening and a plurality of outlet openings for the pulp flowing through the feed line, each of said outlet openings being connected to one of the inlet openings of the tower.  
     
     
         3 . An arrangement according to  claim 1  or  2 , characterized in that at least one stationary element for creating turbulence is mounted at the backside of at least one of the propeller or turbine type devices.  
     
     
         4 . An arrangement according to  claim 1  or  2 , characterized in that the propeller or turbine type devices are arranged to raise the pressure of the pulp so that the total pressure increase of the pulp is at least one bar, preferably at least two bar, most preferably three bar.  
     
     
         5 . An arrangement according to  claim 1 , characterized in that the feed line comprises a standpipe having an outlet and a first pump located downstream of the standpipe, and that a first propeller or turbine type device is arranged at the outlet of the standpipe and upstream of the pump and at least a second turbine or propeller type device is arranged downstream of the pump.  
     
     
         6 . An arrangement according to  claim 4 , characterized in that means for introducing bleaching chemicals and/or steam into the pulp are arranged between the first propeller or turbine type device and the pump in the feed line.  
     
     
         7 . An arrangement according to  claim 4  or  5 , characterized in that the pump is devoid of gas removal means.  
     
     
         8 . An arrangement according to  claim 4 ,  5  or  7 , characterized in that a third propeller or turbine type device is arranged at the inlet of the bleaching tower.  
     
     
         9 . An arrangement according to  claim 8 , characterized by means for introducing bleaching chemicals and/or steam into the pulp for mixing arranged in the second or third propeller or turbine type device.  
     
     
         10 . An arrangement according to any of claims  4 - 8 , characterized in that the turbine or propeller type devices are arranged to raise the pressure of the pulp so that the total pressure increase of the pulp is at least one bar, preferably at least two bar, most preferably three bar.  
     
     
         11 . An arrangement according to any of claims  1 - 8 , characterized in that at least one propeller or turbine type device is arranged in a chamber having at least one inlet opening connected to the outlet opening of the bleaching tower and an outlet opening connected to the discharge line of the bleaching tower.  
     
     
         12 . An arrangement according to  claim 11 , characterized in that at least one mixing bar is positioned upstream of the propeller or turbine type device and rotating therewith and extending in the bleaching tower.  
     
     
         13 . An arrangement according to  claim 1 , characterized in that at least one propeller or turbine type device is arranged both at the inlet and at the outlet of the bleaching tower.  
     
     
         14 . An arrangement according to  claim 13 , characterized in that the devices are arranged to raise the pressure of the pulp so that the total pressure increase of the pulp is at least one bar, preferably at least two bar, most preferably three bar.  
     
     
         15 . An arrangement in connection with bleaching pulp having a consistency of 7-20%, preferably 8-16%, characterized in that the arrangement comprises 
 a propeller or turbine type device located in a flow channel for increasing the pressure of the pulp flowing in said flow channel, which device is connected to a washer or press, the flow channel between the device and the washer or press serving as a bleaching reactor, and    means for introducing chemicals to the pulp downstream of the device for mixing chemicals into the pulp.    
     
     
         16 . An apparatus according to  claim 15 , characterized in that stationary elements are located downstream of the turbine or propeller type device for creating agitation or turbulence.  
     
     
         17 . An arrangement according to any of the preceding claims  1 - 15 , characterized in that the propeller or turbine type device comprises a rotatably mounted shaft extending at least partly in the flow channel of the feed line/discharge line and a propeller with blades or wings or a turbine with blades or wings coupled to the shaft, the device being arranged so that the wings or the blades extend substantially close to the inner surface of the flow channel.  
     
     
         18 . An arrangement according to any of the preceding claims  1 - 17 , characterized in that at least one of the propeller or turbine type devices is provided with a gas separating means.  
     
     
         19 . An arrangement according to  claim 16 , characterized in that the rotational speed of the device is 1000 to 3000 rpm, preferably 1500-2500 rpm.