US-12623194-B2 - Double shaft paddle mixer and arrangement and methods for producing paste

Abstract

A double shaft paddle mixer, including a barrel chamber, and a first paddle screw and a second paddle screw. The first paddle screw is provided with first paddles and the second paddle screw is provided with second paddles. The barrel chamber includes a crushing zone and a mixing zone. The crushing zone is partly separated from the mixing zone by a partition member. A first inlet is connected to the crushing zone and a second inlet is connected to the mixing zone and an outlet connected to the mixing zone. The double shaft paddle mixer can be part of an arrangement and part of a method for producing paste.

Inventors

• Janne Kauppi
• Vesa Koponen

Assignees

• METSO FINLAND OY

Dates

Publication Date

20260512

Application Date

20191231

Claims (20)

1. 1 . A double shaft paddle mixer, comprising: a barrel chamber that is elongated and that extends axially; a first paddle screw and a second paddle screw configured to rotate together in the barrel chamber in an intermeshing relationship, the first paddle screw being provided with first paddles extending from a first shaft and the second paddle screw being provided with second paddles extending from a second shaft, the barrel chamber comprising a crushing zone and a mixing zone, the crushing zone being partly separated from the mixing zone by a partition member, a first inlet connected to an upstream region of the crushing zone, a second inlet being connected to an upstream region of the mixing zone and an outlet connected to a downstream region of the mixing zone, and wherein the average paddle angle of the first paddles with respect to the centerline of the first paddle screw and the second paddles with respect to the centerline of the second paddle screw is larger in the mixing zone than in the crushing zone, wherein the partition member extends from an inner surface of the barrel chamber, wherein a limited passage is provided at the partition member between the crushing zone of the barrel chamber and the mixing zone of the barrel chamber essentially correspond to the cross section of the shape the first paddle screw and the second paddle screw together form as they rotates in the barrel chamber, and wherein the relative number of first paddles and second paddles as calculated along a first rotation axis of the first paddle screw and as calculated along a second rotation axis of the second paddle screw is larger in the crushing zone than in the mixing zone.
2. 2 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the crushing zone being between 1 and 10°.
3. 3 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the mixing zone being between 5 and 25°.
4. 4 . The double shaft paddle mixer according to claim 1 , wherein the mixing zone comprises a fluid adding zone and a homogenization zone, wherein the fluid adding zone extends between the partition member and the second inlet, and wherein the homogenization zone extends between the fluid adding zone and the outlet.
5. 5 . The double shaft paddle mixer according to claim 1 , wherein the first paddle screw and the second paddle screw extend in parallel in the barrel chamber, and wherein the first paddle screw and the second paddle screw are configured to rotate in opposite directions about their rotational axis.
6. 6 . The double shaft paddle mixer according to claim 1 wherein at least some of first blades being at least partly paddle shaped, propeller blade shaped, or curved.
7. 7 . The double shaft paddle mixer according to claim 1 wherein at least some of the second blades being at least partly paddle shaped, propeller blade shaped, or curved.
8. 8 . The double shaft paddle mixer according to claim 1 wherein the first inlet has an opening capable of receiving pieces having a size between 100 and 200 mm.
9. 9 . The double shaft paddle mixer according to claim 1 wherein the second inlet is in fluid connection with a source for fluid such as liquid, suspension or slurry.
10. 10 . The double shaft paddle mixer according claim 1 , wherein the partition member is adjustable arranged in the barrel chamber so at to adjust the size and/or form of the limited passage at the partition member between the crushing zone of the barrel chamber and the mixing zone of the barrel chamber.
11. 11 . The double shaft paddle mixer according to claim 1 , wherein the partition member is releasable arranged in the barrel chamber.
12. 12 . The double shaft paddle mixer according to claim 1 wherein the first paddle screw and the second paddle screw are mirror identical.
13. 13 . The double shaft paddle mixer according to claim 1 wherein at least one of the crushing zone and the mixing zone of the barrel chamber have an at least partly replaceable inner lining.
14. 14 . The double shaft paddle mixer according to claim 1 wherein at least one of the fluid adding zone and the homogenization zone of the barrel chamber have a third inlet for adding a chemical.
15. 15 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the crushing zone is between 2.5 and 7.5°.
16. 16 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the crushing zone is about 5°.
17. 17 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the mixing zone is between 1° and 20°.
18. 18 . The double shaft paddle mixer according to claim 1 , wherein the average paddle angle in the mixing zone is between 1° and 15°.
19. 19 . An arrangement for producing fluid such as paste or slurry, wherein the arrangement comprising: a filter press for dehydrating feeding material, wherein the filter press is in fluid connection with a gravity-based separator; a double shaft paddle mixer according to claim 1 ; and wherein the first inlet of the double shaft paddle mixer is in fluid connection with the filter press and is configured to receive pieces of particulate material from the filter press.
20. 20 . The arrangement according to claim 19 , further comprising a tank for paste in fluid connection with the outlet of the double shaft paddle mixer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. national stage application of International Application PCT/FI2019/050937, filed Dec. 31, 2019, which international application was published on Jul. 8, 2021, as International Publication WO 2021/136871 A1 in the English language. FIELD The invention relates to a double shaft paddle mixer as defined in the preamble of independent claim 1. The invention relates also to and arrangement methods for producing paste. OBJECTIVE The object is to provide a double shaft paddle mixer that is capable of making fluid such as paste or slurry of pieces comprising particulate material such as finer clay, silt, filtered solids, or sand sized material, which pieces having a size that can be between 50 and 400 mm. SHORT DESCRIPTION The idea is based on dividing the barrel chamber of the double shaft paddle mixer into a crushing zone and a mixing zone by means of a partition member preventing pieces of comprising particulate material having a too large size from exiting the crushing zone and enter the mixing zone. A first inlet that can be capable of receiving pieces comprising particulate material, which pieces having a size between 100 and 200 mm is connected to an upstream region of the crushing zone of the barrel chamber and a second inlet that can be configured to receive fluid such as liquid, suspension or slurry is connected to an upstream region of the mixing zone of the barrel chamber. Because the average paddle angle of the first paddles and of the second paddles with respect to the centerline of the first paddle screw and of the second paddle screw is larger in the mixing zone of the barrel chamber than in the crushing zone of the barrel chamber, the material that is fed into the crushing zone of the barrel chamber via the first inlet will move slower in the crushing zone of the barrel chamber than material in the mixing zone of the barrel chamber, after said material having been shredded in the crushing zone of the barrel chamber and having entered the mixing zone of the barrel chamber and after fluid being added to said material via the second inlet. The result of this is an increased residence time in the crushing zone of the barrel chamber which is an advantage, because the size of the pieces that exits the crushing zone of the barrel chamber to enter the mixing zone of the barrel chamber must be small enough to pass the partition member between the crushing zone and the mixing zone. The crushing in the crushing zone can be autogenous. LIST OF FIGURES In the following the double shaft paddle mixer will described in more detail by referring to the figures of which FIG. 1 shows an embodiment of the double shaft paddle mixer, FIG. 2 shows the double shaft paddle mixer shown in FIG. 1 from another angle, FIG. 3 shows the double shaft paddle mixer shown in FIG. 1 as seen from above, FIG. 4 shows the double shaft paddle mixer shown in FIG. 1 as cut along plane A-A in FIG. 3, FIG. 5 shows the double shaft paddle mixer shown in FIG. 1 as seen from one end, FIG. 6 shows the double shaft paddle mixer shown in FIG. 1 as cut along plane D-D in FIG. 4, and FIG. 7 is a flow sheet of an embodiment for producing paste. DETAILED DESCRIPTION The figures show an embodiment of the double shaft paddle mixer. The double shaft paddle mixer comprising a barrel chamber 1 that is elongated and that extends axially. The double shaft paddle mixer comprising a first paddle screw 2 and a second paddle screw 3 configured to rotate together in the barrel chamber 1 in an intermeshing relationship. For the rotation of the first paddle screw 2 and the second paddle screw 3 can either a common or separate rotation means 18 such as electric motors be provided. The first paddle screw 2 is provided with first paddles 4 and the second paddle screw 3 is provided with second paddles 5. The barrel chamber 1 comprises a crushing zone 6 and a mixing zone 7 so that the crushing zone 6 is partly separated from the mixing zone 7 by a partition member 8. In other words, the partition member 8 is arranged in the barrel chamber 1 so that a limited passage 15 is provided at the partition member 8 between the crushing zone 6 of the barrel chamber 1 and the mixing zone 7 of the barrel chamber 1. The purpose of the limited passage 15 is to prevent that pieces having a too large size moves from the crushing zone 6 of the barrel chamber 1 to the mixing zone 7 of the barrel chamber 1. This assures that the first paddles 4 of the first paddle screw 3 and that the second paddles 5 of the second paddle screw 3 have to a sufficient degree fine-divided the matter that passes through the limited passage 15 at the partition member when matter exits the crushing zone 6 of the barrel chamber 1 and to enter the mixing zone 7 of the barrel chamber 1 The thickness of the first paddles 4 and the second paddles 5 is preferably, but not necessarily, between 10 and 40 mm at least in the crushing zone 6 of the barrel