Accept tank mixing arrangement
An accept tank arrangement for mixing of pulped fiber suspension including sidewalls ( 3,4 ) including opposite arched ends ( 2 ) and an elongated section ( 1 ) between the arched ends ( 2 ). The accept tank has mixers ( 10 ) each located within one of the arched ends ( 2 ). The mixers ( 10 ) have axles ( 11 ) on which are mounted propellers ( 12 ). The mixers ( 10 ) are aligned horizontally and each axle points to a respective point on the elongated section ( 1 ) of the sidewall ( 3 ) which away from an end of the elongate section by at least 25% of the length of the elongated section ( 1 ). The propellers ( 12 ) are symmetrically positioned with respect to a center-point of the accept tank. Within the center of the elongated section is an elongated centerpiece ( 6 ) having rounded ends. The accept tank has a substantially flat bottom at least at the elongated section ( 1 ) of the accept tank.
1 . An accept tank arrangement for mixing of pulped fiber suspension, the accept tank arrangement comprising:
an accept tank configured to receive the pulped fiber suspension and the accept tank comprises sidewalls including a first elongated sidewall and a second elongated sidewall on an opposite side of the accept tank from the first elongated sidewall, and a first arched sidewall end and a second arched sidewall end;
an accept outlet in one of the first and second elongated sidewalls, wherein the accept outlet is configured to discharge accepts from the pulped fiber suspension,
a first mixer configured to mix the pulped fiber suspension in the accept tank and the first mixer including a first axle driving a first propeller in a region within the tank boarded by the first arched sidewall end, wherein a first axis of the first axle projects through a first point on the first elongated sidewall no less than twenty-five percent (25%) of a length of the first elongated sidewall away from the first arched sidewall end,
a second mixer configured to mix the pulped fiber suspension in the accept tank and the first mixer including a second axle driving a second propeller in a region within the tank boarded by the second arched sidewall end, wherein a second axis of the second axle projects through a second point on the second elongated sidewall no less than twenty-five percent (25%) of a length of the second elongated sidewall away from the second arched sidewall end, and
a reject outlet configured to discharge rejects from the pulped fiber suspension from the accept tank and the reject outlet is proximate a bottom of the accept tank,
wherein the first arched sidewall end is joined to first ends of each of the first and second elongated sidewalls,
wherein the second arched sidewall end is jointed to second ends of each of the first and second elongate sidewalls, and the second ends are opposite to the first ends, and
wherein the first and second arched sidewall ends each have a curvature greater than any curvature of the first and second elongated sidewalls.
2 . The accept tank arrangement of claim 1 , wherein the first axle is on a side of accept tank opposite a longitudinal center line of the accept tank from the accept outlet.
3 . The accept tank arrangement of claim 1 , wherein the first mixer and the second mixer are the only mixers in the accept tank.
4 . The accept tank arrangement of claim 1 , wherein the first and second propellers are arranged symmetrically about a center point of the accept tank.
5 . The accept tank arrangement of claim 1 , further comprising an elongated centerpiece aligned with a longitudinal centerline of the accept tank and extending upward from the bottom of the accept tank, wherein the elongated centerpiece has a length no less than 50% of the length of the first elongated sidewall.
6 . The accept tank arrangement of claim 5 , wherein the elongated centerpiece has rounded ends and a width no greater than 30% of a width of the accept tank.
7 . The accept tank arrangement of claim 1 , wherein the bottom of the accept tank includes a flat bottom region between each of the first and second elongated sidewalls, wherein a depth of the accept tank varies over the flat bottom region by less than 5% of the length of the first elongated sidewall.
8 . The accept tank arrangement of claim 1 , wherein the reject outlet is located at least partially at a bottom of the accept tank, is at an elevation below the accept outlet and is at least partially boarded by of the first and second arched sidewall ends.
9 . The accept tank arrangement of claim 1 , wherein at least a part of the accept outlet is at least one of: between the first elongated sidewall and second elongated sidewall, the accept outlet is proximate ends for the first and second elongated sidewalls, or the accept outlet is on a side of an elongated centerline of the accept tank opposite to the first or second propeller nearest the accept outlet.
10 . The accept tank arrangement of claim 1 , wherein the reject outlet is downstream of the accept outlet along a flow direction within the accept tank and adjacent the first or second elongated sidewall nearest the accept outlet.
11 . The accept tank arrangement of claim 1 , wherein the first axle and the second axle are each oriented in a horizontal plane at an angle in a range of 15 to 35 degrees from a longitudinal center line of the accept tank.
12 . The accept tank arrangement of claim 11 , wherein the range is 20 to 30 degrees.
13 . The accept tank arrangement of any of claim 1 , wherein a length of the accept tank is in a range of 1.5 to 2 times a width of the accept tank.
14 . The accept tank arrangement of claim 1 , wherein the first and second propellers each have a diameter in a range of 10% to 20% of a width of the accept tank.
15 . An accept tank assembly for mixing of pulped fiber suspension, the accept tank comprising:
an accept tank with a bottom, wherein the accept tank is configured to receive the pulped fiber suspension;
sidewalls of the accept tank extending around a periphery of the bottom, the sidewalls including a first elongated sidewall, a second elongated sidewall opposite to the first elongated sidewall, a first arched sidewall end at first ends of the first and second elongated sidewalls and a second arched sidewall end at second ends of the first elongated sidewall and the second elongated sidewall,
an accept outlet for the accept tank, wherein the accept outlet is configured to discharge accepts from the pulped fiber suspension in the accept tank;
a first mixer configured to mix the pulped fiber suspension in the accept tank and the first mixer includes a first axle driving a first propeller boarded by the first arched sidewall end, wherein a first axis of the first axle projects through a first point on the first elongated sidewall at least twenty-five percent (25%) of a total length of the first elongated sidewall away from the first arched sidewall end, and
a second mixer configured to mix the pulped fiber suspension in the accept tank and the first mixer includes a second axle driving a second propeller in a region within the tank boarded by the second arched sidewall end, wherein a second axis of the second axle projects through a second point on the second elongated sidewall at least twenty-five percent (25%) of a total length of the second elongated sidewall away from the second arched sidewall end, and
a reject outlet configured to discharge rejects from the pulped fiber suspension in the accept tank, wherein the reject outlet is at least partially in an end section of the bottom
wherein the first and second arched sidewall ends each have a curvature greater than any curvature of the first and second elongated sidewalls.
16 . The accept tank assembly of claim 15 , further comprising an elongated centerpiece aligned with a longitudinal centerline of the accept tank and extending upward from the bottom, wherein the elongated centerpiece has a length no less than 50% of the length of the first elongated sidewall.
17 . The accept tank assembly of claim 15 , wherein the reject outlet is in the bottom, at an elevation below the accept outlet, and at least partially bordered by one of the first and second arched sidewall ends.
18 . The accept tank assembly of claim 15 , wherein the accept outlet is on a side of an elongated centerline of the accept tank opposite to the first or second propeller nearest the accept outlet.
19 . The accept tank assembly of claim 15 , wherein the first axle and the second axle are each oriented in a horizontal plane at an angle in a range of 15 to 35 degrees from a longitudinal center line of the accept tank.
20 . The accept tank assembly of claim 15 , wherein the first and second propellers each have a diameter in a range of 10% to 20% of a width of the accept tank.