Device for dispersing a water-soluble polymer

Abstract

A device for dispersing a water-soluble polymer includes a primary water inlet circuit that feeds an overflow, at the bottom end of the cone, an assembly including a chamber for grinding and draining the dispersed polymer, having a rotor driven by a motor provided with knives, a stator, over all or part of the periphery of the chamber, a ring fed by a secondary water circuit, the ring communicating with the chamber by way of slots for spraying pressurized water onto the stator The slots of the stator and/or the knives of the rotor are tilted at an angle of between 20 and 80 relative to the horizontal plane of the stator and the lateral face of the blade next to the stator is curved in such a way as to make the distance separating the two components substantially constant.

Claims

1. A device for dispersing a water-soluble polymer with a particle size of less than 1.5 mm, said device comprising: a wetting cone wherein the polymer is metered, said cone being connected to a primary water inlet circuit at the bottom end of the cone: a chamber for grinding and draining the dispersed polymer including: a rotor driven by a motor and provided with a center, a periphery and blades having a rear face and a front face, a fixed stator having the form of a cylinder including slots, over all or part of the periphery of the chamber, a ring fed by a secondary water circuit, the ring communicating with the chamber in such a way as to guarantee the spraying of pressurized water onto the stator, wherein the slots of the stator and/or the blades of the rotor are tilted at an angle between 20 and 80 relative to a horizontal plane of the stator and the lateral face of the blade next to the stator is curved in such a way as to make the distance separating the two components substantially constant, wherein an upper side of each blade has a first portion having a first height and a second portion having a second height, the second height being less than the first height, and wherein the first height is between 35 and 40 mm and the second height is between 30 and 34.5 mm, both portions being separated by a tilted portion forming an angle with the second portion of between 130 and 140.

2. The device according to claim 1, wherein the front face of each blade connecting the center of the rotor to the periphery is of a generally rounded shape.

3. The device according to claim 1, wherein the front face and the rear face of each blade connecting the center of the rotor to the periphery is of a generally rounded shape.

4. The device according to claim 1, wherein the front face of each blade has a first portion having a first bend radius and a second portion having a second bend radius which is longer that the first bend radius and the rear face of the blade has a constant bend radius which is identical to the bend radius of the second portion.

5. The device according to claim 4, wherein the first bend radius is between 30 and 50 mm and the second bend radius is between 55 and 70 mm.

6. The device according to claim 1, wherein the blades are offset in relation to a radius of the rotor at an angle between 1 and 15.

7. The device according to claim 6, wherein the blades are offset in relation to the radius of the rotor at an angle between 2 and 10.

8. The device according to claim 1, wherein the slots of the stator and the blades of the rotor are tilted at an angle of between 30 and 70 relative to the horizontal plane of the stator.

9. The device according to claim 1, wherein the slots of the stator and the blades of the rotor are tilted at an angle of between 40 and 60 relative to the horizontal plane of the stator.

10. The device according to claim 1, wherein the slots are rectilinear and parallel to one another.

11. The device according to claim 1, wherein the slots and the blades are tilted at two inclinations and the two inclinations are symmetrically opposed.

12. The device according to claim 1, wherein slots of the stator are cut into part of a height of said cylinder.

13. The device according to claim 1, wherein: the slots in the stator have a width of between 50 and 1200 microns, the stator cylinder has a thickness of between 5 and 30 mm, a height of the stator is between 20 and 100 mm a diameter of the stator is between 100 and 500 mm a number of stator slots is between 50 and 1500, the slots in the stator are regularly spaced apart at a distance of between 1 and 50 mm, the slots have a length of between 10 mm and 100 mm.

14. The device according to claim 1, wherein a distance separating a free end of the rotor blades and the stator slots is between 50 and 300 microns.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic side view of the device of the invention;

(2) FIG. 2 is a sectional view taken along the line AA.

(3) FIG. 3 is a schematic side view of the stator of the device of the invention wherein the slots are tilted in relation to the horizontal plane of the stator.

(4) FIG. 4 is a schematic three-dimensional view of the stator of the device of the invention wherein the slots are tilted in relation to the horizontal plane of the stator.

(5) FIG. 5 is a top view of the rotor of the device of the invention wherein the blades are tilted in relation to the horizontal plane of the stator.

(6) FIG. 6 is a three-dimensional view of the rotor of the device of the invention wherein the blades are tilted in relation to the horizontal plane of the stator.

DETAILED DESCRIPTION OF THE INVENTION

(7) According to FIG. 1, the device of the invention is composed of: a wetting cone (1) connected at the top of same to a column (2) metering the polymer of standard particle size, most usually by means of a metering screw, the bottom part of the cone (1) being connected to a primary water inlet circuit (3) that feeds an overflow (4), at the bottom end of the cone, an assembly (5) composed of: a chamber (6) for grinding and draining (FIG. 2) the dispersed polymer, composed of: a rotor (7) driven by a motor (8) provided with blades (9), a stator (10), over all or part of the periphery of the chamber, a ring (11) fed by a secondary water circuit (12), the ring (11) communicating with the chamber (6) by means of slots (13) for spraying pressurized water onto the stator (10).

(8) According to FIGS. 3 and 4, the slots (14) of the stator (10) are tilted in relation to the horizontal plane of the device. The dimensional characteristics of the stator are reported in the table below.

(9) According to FIGS. 5 and 6, the blades (15) of the rotor (7) are tilted in relation to the horizontal plane of the device. As these figures show, the lateral face (16) of the blade next to the stator is curved in such a way as to make the distance separating the two components substantially constant. Similarly, the inclined face (front face 17 and rear face 18) of each blade connecting the center of the rotor to the periphery is of a generally rounded shape. Starting from the center to the periphery of the rotor, the front face (17) of each blade has a first portion having a first bend radius between 30 and 50 mm and a second portion having a second bend radius between 55 and 70 mm and the rear face (18) of the blade has a constant bend radius which is identical to the one of the second portion. Additionally, the upper side of each blade has a first flat portion (19) having a first height between 35 and 40 mm and a second flat portion (20) having a second height between 30 and 34.5 mm, both portions being separated by a titled portion (21) forming an angle with the second flat portion of between 130 and 140. As illustrated, the rotor has 9 blades.

(10) A device according to the invention wherein the slots are tilted at 45 to the horizontal plane of the stator and wherein the blades are perpendicular to the horizontal plane of the stator is compared to the device according to the example in the document WO 2011/107683 wherein the slots and the blades are perpendicular to the horizontal plane of the stator.

(11) The vibrations of the apparatus in operation were measured using a PCE-VT 1000 vibration meter. The vibrations are expressed in mm/s. The lower the value, the lower the vibrations. Values lower than 1 are typical of a good result in terms of vibration. However, values below 1.8 are acceptable.

(12) The results are reported in the following table.

(13) TABLE-US-00001 PSU 300 according to PSU 300 document WO according to the 2011/107683 Invention Cutting diameter (mm) 200 200 Number of slots 110 110 Height of the slots (mm) 16.6 16.6 Width of the slots (microns) 200 200 Inclination of the slots in relation to 0 45 the horizontal plane Number of blades (rotor) 9 9 Motor power (kW) 7.5 7.5 Rotor speed [rpm] 4500 4500 Vibration (mm/s) 2.8 0.46 Maximum primary water flow rate 15 17 (m.sup.3/h) Secondary water flow rate (m.sup.3/h) 20 23 Powder flow rate (continuous 300 450 mode) kg/h

(14) The 45 inclination of the slots within the device according to the invention allows for a significant reduction in vibration from 2.8 mm/s to 0.45 mm/s, an 84% decrease in vibration. The life expectancy of the bearings is therefore greatly increased.

(15) It is also apparent that this makes it possible to increase the rate at which polyacrylamide powder dissolves from 300 kg/h to 450 kg/h in continuous mode, i.e., when the apparatus functions continuously for a long period of several days or several weeks.

(16) When necessary this flow rate may occasionally be increased to a so-called maximum flow rate for a short period.

(17) The apparatus according to the invention increases the flow rate of the polymer solution up to 40 m.sup.3/h and a maximum powder quantity of 550 kg/h can be reached without blocking the apparatus.

(18) Other devices wherein the slots are inclined at 10, 30, 60, and 80 in relation to the horizontal plane of the stator have been tested, the blades remaining not-inclined. The vibration values measured were respectively 2.5 mm/s, 0.8 mm/s, 0.9 mm/s, and 1.6 mm/s.

(19) A significant reduction in vibration is observed when the inclination angle of the slots in relation to the horizontal plane of the stator is greater than 20. Better results are obtained for angles between 30 and 70.

(20) This solution of inclining only the slots of the stator is the simplest from the point of view of machining. However, a rotor with angled blades was also tested giving similar vibration and flow rate results.