Arrangement for and a method of treating pulp, and a method of modernizing a pulp tower
An arrangement for and a method of treating pulp, and a method of modernizing a pulp tower are disclosed. The arrangement and method relate to treating pulp in connection with high-consistency pulp towers, and especially to means ( 36, 42 ) for diluting pulp arranged substantially at the level of the smallest cross-sectional area between the parting member ( 31 ) and the wall ( 12 ) of the pulp tower ( 10 ).
1. An arrangement for treating pulp, said arrangement comprising a high-consistency pulp tower ( 10 ) having an upstanding tower wall ( 12 ), a bottom ( 22 ), and a stationary parting member ( 31 , 31 ″) arranged in the tower, said parting member dividing the tower to an upper part and a bottom part ( 20 ), said bottom part defining a so-called dilution zone of said tower ( 10 ), at least one agitator ( 40 ) arranged in the bottom part ( 20 ) for diluting high-consistency pulp, discharge means ( 60 ) for diluted pulp arranged in the bottom part ( 20 ), and said parting member ( 31 , 31 ″) and said wall ( 12 ) of the tower ( 10 ) defining a first cross-sectional flow area, which is smaller than a corresponding cross-sectional flow area below the parting member ( 31 , 31 ″), wherein the arrangement additionally includes means ( 36 , 42 ; 38 , 39 ; 46 ; 48 ) for diluting pulp arranged at a distance from said wall ( 12 ) between said parting member ( 31 , 31 ″) and said wall ( 12 ) of said tower ( 10 ) substantially at the level of said first cross-sectional flow area.
2. The high-consistency pulp tower as recited in claim 1 , wherein said diluting means comprises at least one baffle ( 36 , 36 ′) arranged to extend at least partially from one of said parting member ( 31 , 31 ″) and said tower wall ( 12 ) towards one of said tower wall ( 12 ) and said parting member ( 31 , 31 ″), respectively.
3. The high-consistency pulp tower as recited in claim 1 , wherein said diluting means comprises at least one baffle ( 36 , 36 ′) arranged to extend from said tower wall ( 12 ) to said parting member ( 31 , 31 ″).
4. The high-consistency pulp tower as recited in claim 2 , wherein said diluting means further comprises openings or nozzles ( 42 ) in said baffles ( 36 , 36 ′).
5. The high-consistency pulp tower as recited in claim 1 , wherein said diluting means comprises at least one annular duct ( 46 ) arranged on supporting members ( 36 ) between said parting member ( 31 , 31 ′) and said tower wall ( 12 ).
6. The high-consistency pulp tower as recited in claim 1 , wherein said diluting means comprises nozzles ( 48 ) or openings in said parting member ( 31 ) for feeding dilution liquid to the pulp.
7. The high-consistency pulp tower as recited in claim 1 , wherein said diluting means ( 36 , 42 ; 38 , 39 ; 46 ; 48 ) is connected to means for introducing dilution liquid in said diluting means ( 36 , 42 ; 38 , 39 ; 46 ; 48 ).
8. The high-consistency pulp tower as recited in claim 7 , wherein said dilution liquid introduction means are arranged in connection with one of said wall ( 12 ) of said tower ( 10 ) and said bottom pillar ( 30 ).
9. The high-consistency pulp tower as recited in claim 7 , wherein said dilution liquid introduction means is a dilution header arranged outside said tower.
10. The high-consistency pulp tower as recited in claim 7 , wherein said dilution liquid introduction means is a piping leading to the parting member ( 31 ) via the bottom pillar ( 30 ).
11. The high-consistency pulp tower as recited in claim 1 , wherein said parting member ( 31 ) has been arranged in the top of a so-called bottom pillar ( 30 ), which is arranged to the bottom ( 22 ) of the tower ( 10 ).
12. The high-consistency pulp tower as recited in claim 1 , wherein said at least one agitator ( 40 ) is arranged to generate a circulating pulp flow in the bottom part ( 20 ) of said tower ( 10 ).
13. The high-consistency pulp tower as recited in claim 12 , wherein said agitator ( 40 ) has a shaft positioned substantially horizontally.
14. The high-consistency pulp tower as recited in claim 1 , wherein two to six agitators ( 40 ) are arranged in the dilution zone of the tower ( 10 ).
15. The high-consistency pulp tower as recited in claim 14 , wherein said agitators ( 40 ) are provided with feed means ( 50 ) for introducing dilution liquid into the pulp.
16. The high-consistency pulp tower as recited in claim 1 , wherein the parting member ( 31 ″) is carried by means of baffles ( 36 ′) on the wall ( 12 ) of the tower ( 10 ).