WO2004052514A2

WO2004052514A2 - Mixer

Info

Publication number: WO2004052514A2
Application number: PCT/IB2003/005816
Authority: WO
Inventors: Pieter Johann Jansen
Original assignee: Pieter Johann Jansen
Priority date: 2002-12-10
Filing date: 2003-12-10
Publication date: 2004-06-24
Also published as: WO2004052514A3; AU2003302880A8; AU2003302880A1; ZA200400707B

Abstract

An apparatus (10) for mixing a fluid with an immiscible fluid. The apparatus comprises a mixing chamber having inlets for the liquid (22) and the fluid (24) at or towards one end and an outlet (28) for a mixture of the liquid and the fluid at or towards an opposite end. An elongate flow pathway (14) which is generally zig-zag in shape, when seen in longitudinal section, extends between the inlets and the outlet. The generally zig-zag pattern provides a sharp change in direction of the pathway along its length thereby generating a cross-flow of the liquid and the fluid down the pathway to enhance mixing of the first liquid and the fluid before being discharged from the chamber.

Description

MIXER

THIS INVENTION relates to a process and apparatus for mixing a liquid with a fluid which is not miscible with the liquid and which may be a gas, a liquid or a solid.

According to a first aspect of the invention, there is provided an apparatus for mixing a first liquid with a fluid that is not miscible with the first liquid, said apparatus comprising a mixing chamber which defines an elongated pathway; an inlet for the first liquid at or towards one end of the pathway; an inlet for the fluid at or towards the same end of the pathway; an outlet for a mixture of the first liquid and the fluid at or towards an opposite end of the pathway; the pathway, in longitudinal cross-section, being defined by a pair of opposite sides which, in succession, slope at an angle to a longitudinal axis of the mixing chamber, then are substantially parallel to the longitudinal axis, followed by sloping at substantially the same angle to the longitudinal axis thereby providing changes in direction along the pathway, the changes in direction being sharply defined and free from curved portions. Mixing may occur by the fluid and liquid impacting a sloping side of the pathway, followed by deflection towards an opposite sloping side of the pathway, and so forth, thereby generating a cross-flow of fluid and liquid down the pathway.

The sides of the pathway may slope at angles of 30 - 65°. In one embodiment of the invention, the sides of the pathway may slope at angles of 30 - 40°, preferably 33 - 37°, most preferably 35°, relative to the longitudinal axis. In another embodiment of the invention, the sides of the pathway may slope at angles of 54 - 64°, preferably 57 - 61°, most preferably 59°, relative to the longitudinal axis.

Whereas the first liquid is a liquid at the temperature for carrying out the mixing (e.g. about room temperature), the fluid may be a second liquid which is not miscible with the first liquid. Alternatively the fluid may be a gas or may be a solid in sufficiently finely divided form that it can be mixed in the process and apparatus with the first liquid. Thus, the invention is useful for processes which require good mixing of a liquid with a further liquid or with a gas or solid which may be finely divided. The invention can be used for the aeration of waste liquids, e.g. aeration of sewage or other waste liquids including waste liquids from commercial, industrial or mining processes. Environmental limitations frequently require the treatment of such liquids before they are acceptable to the environment and the present invention provides an apparatus and process for enabling this to be done.

When solid material is present in the liquid, the liquid obtained after treatment by the process and apparatus will be in the form of a slurry. Another area of use is in froth flotation processes for separating minerals from their ores, or for treating waste water with aerobic microorganisms to make the treated liquid suitable for further use, e.g. discharge into a stream or re-use.

The pathway is closed apart from the inlets and outlets, i.e. it is defined between walls which cause the mixture being formed to pass along the pathway.

In one preferred embodiment, the elongated pathway can be arranged in a container with the inlets leading into the container towards the top thereof and an outlet leading from a container towards the bottom thereof. The container may be of circular cross-section and the pathway, in horizontal cross-section, may be an annular pathway the distance of which from the wall of the container varies at different lengths along the container. Alternatively, instead of a single annular pathway of annular cross-section, a plurality of separate pathways may have common inlets and/or a common outlet.

The pathway may be defined between complimentary shaped inner and outer formations which have alternating sloping and straight-sides thereby to define the elongated pathway. Thus, both the inner and outer modular blocks may be of overall circular horizontal cross-section but are devoid of curved portions in vertical cross- section and are so designed to form the pathway when a plurality of such modular blocks are placed on top of each other. The outer (i.e. inner facing) modular blocks can be of annular cross-section with an outer diameter substantially equal to the inner diameter of the container.

As the first liquid and fluid pass downwardly through the pathway, thorough mixing takes place as they are forced along straight paths towards, substantially parallel to, and then away from the central rod of the container. The mixture is thereby caused to change its direction in sharply defined non-curved manner at frequent intervals.

The distance between the sides of the pathway may be constant over most of the length of the pathway, or may vary. In one embodiment, the distance between the sides of the pathway may alternatively narrow and widen between adjacent modular blocks. In other words, the distance between the sides of the pathway may vary over at least a portion of the length of the pathway. For instance, the sides of the pathway defined by the inner modular blocks may slope at an angle somewhat greater than the angle at which the sides of the pathway defined by the outer modular blocks slope, relative to the longitudinal axis, i.e. the slope of the inner modular blocks may be closer to the peφendicular, relative to the longitudinal axis, than the slope of the outer modular blocks. In such case, the pathway will alternately narrow and widen along its course, becoming wider as it slopes towards the inner modular blocks, and narrowing as it slopes away from the inner modular blocks.

The pathway may be of wider cross-section at the inlets and outlet. For example, the first part of the pathway can be of triangular vertical cross-section, i.e. funnel-shaped, leading to the pathway of narrower internal cross-section before broadening out into an outlet of greater cross-section than the cross-section of the remainder of the pathway.

The first liquid may enter the container axially from the top and may pass over a diverting cone into the top of the pathway where the fluid, preferably a gas, is injected through an annular inlet. The mixture can be retrieved from the outlet at the bottom of the annular pathway.

With the apparatus of the invention, a frequently changing flow path is caused to occur, thereby effecting good mixing of the first liquid with the fluid.

Preferably, the inner and outer formations each may be provided by a plurality of modular outwardly and inwardly facing elements or blocks which are stacked on top of one another.

A longitudinally extending elongate support rod may be provided onto which the inner (outwardly facing) modular elements or blocks are slidably received.

According to a second aspect of the invention, there is provided a process for mixing a first liquid with a fluid that is not miscible with the first liquid, said process comprising; passing the first liquid through an inlet into an elongated pathway having the inlet at or towards one end thereof; passing the fluid through an inlet at or towards the same end into the elongated pathway; allowing the first liquid and the fluid to pass along the elongated pathway, said pathway, in longitudinal cross-section, being defined by a pair of opposite sides which, in succession, slope at an angle to a longitudinal axis, then are substantially parallel to the longitudinal axis, followed by sloping at substantially the same angle to the longitudinal axis thereby providing changes in direction along the pathway, the changes in direction of the pathway being sharply defined and free from curved portions to create a cross- flow of the fluid and liquid down the pathway by allowing the fluid and liquid to impact on a sloping side of the pathway, followed by deflection towards an opposite sloping side of the pathway; and removing the mixture of the first liquid and the fluid from an outlet at or towards an opposite end of the elongated pathway.

The distance between the sides of the pathway may be varied along at least a portion of the flow path.

The invention will now be further described, by way of non-limiting example, in the accompanying drawings in which

Figure 1 is a vertical cross-section through an apparatus in accordance with the invention;

Figure 2 is a plan view of the apparatus of Figure 1 ;

Figure 3 is a cross-section through an upper part of the apparatus of Figure 1 ;

Figures 4(a) to Figure 4(e) show modular elements or blocks for forming the pathway of the apparatus of Figure 1 ; and

Figure 5 is a view corresponding to Figure 1 of a further embodiment of an apparatus in accordance with the invention.

Referring to Figure 1 of the drawings, an apparatus shown generally at 10 comprises a vertical container 12 having a mixing chamber which defines an elongated pathway 14. The pathway 14 is formed between an outer formation provided by a plurality of outer modular blocks 16.1 to 16.5 and an end block 18, on the one hand, and an inner formation provided by a plurality of inner modular blocks 20.1 to 20.5, on the other hand.

A first liquid inlet 22 is situated at the top of the container 12. An inlet for a fluid (preferably a gas) is shown at 24 towards the same end as the inlet 22. The inner modular blocks 20.1 to 20.5 are annular in shape and fit over a central support in the form of an upwardly extending rod 26. The outer blocks 16.1 to 16.5 and end block 18 also are annular in shape and are of a size to fit tightly against an inner wall 23 of the container 12. An outlet for the mixture of the first liquid and the fluid is shown at 28 i.e. towards an opposite end of the pathway 14.

The gas, or other fluid, introduced through inlet 24 passes through a manifold 30 into a frustoconical upper part 32. Similarly, the first liquid passing through inlet 22 passes down over a central diverting cone 34 into the frustoconical part 32 and then together they pass downwardly through the elongated pathway 14. The fluid and liquid typically impact one of the sloping sides of one of the upper blocks 16.1 or 20.1 and are then deflected toward the opposite side of the pathway 14, thereby generating a cross-flow of liquid and fluid down the pathway 14.

As can be seen from Figure 1 , the elongated pathway 14 has vertical portions 36 substantially parallel to a longitudinal axis of the mixing chamber, as well as portions 38 which slope at an angle to the longitudinal axis, towards the central rod 26, and portions 40 which slope at substantially the same angle but downwardly away from the central rod 26. Thus, this generally zig-zag pattern provides a sharp change in direction of the pathway between the edges of each vertical portion 36 and inwardly pointing portion 38 as well as between each vertical portion 36 and outwardly pointing portion 40. There are no curved portions or edges along the pathway 14.

The pathway 14 broadens out into portion 42 towards the outlet 28. A base part 48 (see Figure 4(e)) has a central opening 50 in which the rod 26 is seated. The upper end of the rod 26 fits in aperture 52 of the cone 34 (see Figure 3).

As can be seen from Figures 4(a) - (c), the modular blocks forming most of the pathway 14 can be symmetrical as is shown in block 16.1 of Figure 4(a) or can be asymmetrical as shown in blocks 16.2 and 16.3 of Figures 4(b) and 4(c). The bottom block 18 (see Figure 4(d)), which faces modular block 20.5 (see Figure 1) causes the end of the pathway 14 to be of larger cross-section than all except the inlet 22 of the pathway 14.

As can be seen from Figure 1, the cross-section of the pathway 14 when the pathway 14 is inclined downwardly towards the centre is of smaller cross-section than when the pathway is inclined away from the centre i.e the pathway narrows at the circle parts 54 and then broadens out again. It can furthermore be seen that every change in direction of the pathway 14, whether from an inwardly inclined part to a vertical part or from a vertical part, to an outwardly inclined part or from an outwardly inclined part to a vertical part, is sharply defined with only straight edges and no curved portion.

Preferred angles for the surface of the pathway are as follows for the different blocks indicated: block 16.1 - 33 - 37° angle of deflection relative to the longitudinal axis

block 16.2 - 33 - 37° angle of deflection relative to the longitudinal axis

block 16.3 - 33 - 37° angle of deflection relative to the longitudinal axis

block 18 - 13 - 17° angle of deflection relative to the longitudinal axis

The distances between opposite walls may depend on the first liquid and fluid being mixed together, e.g. from about 5 to 20 mm, more usually from about 10 to 15 mm.

In Figure 5, reference numeral 60 generally indicates a further embodiment of an apparatus in accordance with the invention, like reference numerals indicating like parts in Figures 1 - 4 and in Figure 5, unless otherwise indicated.

The apparatus 60 of Figure 5 is similar to the apparatus 10 of Figure 1 , a main distinction being that the inner modular blocks 120.1 to 120.5 and the outer modular blocks 116.1 to 116.5 are shaped such that portions 138 of the pathway 14 which slope towards the central rod 26 and portions 140 which slope away from the central rod 26 are at a greater angle to the rod 26 than is the case in the apparatus 10 of Figure 1. In this example, the pathway alternatively slopes towards and away from the rod 26 at an angle of about 60° relative to the longitudinal axis of the mixing chamber.

More particularly, the inner modular blocks 120.1 to 120.5 are shaped such that their sloping portions slope at an angle of 60° to the longitudinal axis, while the sloping portions of the outer modular blocks 116.1 to 116.5 slope at an angle of 59° to the longitudinal axis. The result is that the pathway 14 alternately narrows and widens as it slopes towards and away from the rod 26. it will be appreciated that the pathway 14 narrows or converges as it approaches the rod 26, and widens or diverges as it slopes radially outwardly away from the rod 26.

Furthermore, vertical portions 136 of the pathway 14 are longer or more extensive than is the case with the apparatus of Figure 10, to resist erosion and consequent rounding of the associated rectilinear edges, in use.

The Inventor believes that, with the apparatus of the invention having the pathway 14 as defined above, and with changes in direction of it being sharply defined and free from curved portions so as to enhance the impacting and deflection of the fluid and liquid, a very good mixing of the first liquid and the fluid (preferably a gas) is obtained.

Claims

CLAIMS:

1. An apparatus for mixing a first liquid with a fluid that is not miscible with the first liquid, said apparatus comprising a mixing chamber which defines an elongated pathway; an inlet for the first liquid at or towards one end of the pathway; an inlet for the fluid at or towards the same end of the pathway; an outlet for a mixture of the first liquid and the fluid at or towards an opposite end of the pathway; the pathway, in longitudinal cross-section, being defined by a pair of opposite sides which, in succession, slope at an angle to a longitudinal axis of the mixing chamber, then are substantially parallel to the longitudinal axis, followed by sloping at substantially the same angle to the longitudinal axis thereby providing changes in direction along the pathway, the changes in direction being shaφly defined and free from curved portions.

2. An apparatus as claimed in claim 1 , in which the sides of the pathway slope at an angle of 30 - 65°.

3. An apparatus as claimed in Claim 2 in which the sides of the pathway slope at an angle of 30 - 40°.

4. An apparatus as claimed in Claim 3, in which the sides of the pathway slope at an angle of 33 - 37°.

5. An apparatus as claimed in claim 2, in which the sides of the pathway slope at an angle of 57° to 61°.

6. An apparatus as claimed in any one of the preceding claims, in which the pathway is defined between complimentary shaped inner and outer formations which have alternating sloping and straight-sides thereby to define the elongated pathway.

7. An apparatus as claimed in Claim 6, in which the inner and outer formations are each provided by a plurality of modular outwardly and inwardly facing elements which are stacked on top of one another.

8. An apparatus as claimed in Claim 7, in which a longitudinally extending elongate support is provided onto which the inner (outwardly facing) modular elements are slidably received.

9. An apparatus as claimed in Claim 7 or 8, in which the outer (inwardly facing) modular elements are of annular cross-section with an outer diameter substantially equal to the inner diameter of the mixing chamber.

10. An apparatus as claimed in any one of the preceding claims, in which the distance between the sides of the pathway varies over at least a portion of the length of the pathway.

11. An apparatus as claimed in any one of the preceding claims in which the elongated pathway is arranged in a container of circular cross-section with the inlets leading into the container towards the top thereof and an outlet leading from the container towards a bottom thereof, and in which the pathway in horizontal cross-section is annular in shape the distance of which from a wall of the container varies at different lengths along the container.

12. A process for mixing a first liquid with a fluid that is not miscible with the first liquid, said process comprising; passing the first liquid through an inlet into an elongated pathway having the inlet at or towards one end thereof; passing the fluid through an inlet at or towards the same end into the elongated pathway; allowing the first liquid and the fluid to pass along the elongated pathway, said pathway, in longitudinal cross-section, being defined by a pair of opposite sides which, in succession, slope at an angle to a longitudinal axis, then are substantially parallel to the longitudinal axis, followed by sloping at substantially the same angle to the longitudinal axis thereby providing changes in direction along the pathway, the changes in direction of the pathway being sharply defined and free from curved portions to create a cross- flow of the fluid and liquid down the pathway by allowing the fluid and liquid to impact on a sloping side of the pathway, followed by deflection towards an opposite sloping side of the pathway; and removing the mixture of the first liquid and the fluid from an outlet at or towards an opposite end of the elongated pathway.

13. A process as claimed in Claim 12, in which the distance between the sides of the pathway is varied along at least a portion of the flow path.

14. A new apparatus, substantially as herein described and illustrated with reference to the accompanying diagrammatic drawings.

15. A new process, substantially as herein described and illustrated with reference to the accompanying drawings.