A DEVICE FOR MODIFYING FLUID FLOW THROUGH A CONDUIT

Field of Invention

The present invention relates to the field of conduit transfer of fluids and in particular, but not exclusively, the transfer of slurries.

Background of Invention

Dense medium separator (DMS) plant are used to concentrate target mineral from a feed comprising a mixture of both the target mineral and gangue material . The ¹ concentration of the target mineral is achieved by mixing the feed with a dense liquid medium having a specific gravity between the specific gravity of the target mineral and the gangue material. Due to the relative specific gravities one of the target mineral and the gangue material floats, forming a "float fraction" and the other sinks, forming what is known as the "sink" . Various well known separators such as a cone separator or a drum separator may be used to then separate the float fraction from the sink, both of which leave the separator as a slurry comprising the dense liquid medium together with the target mineral or the gangue material.

The slurries are transferred in conduits to other stations or locations in the DMS plant for further processing. Some of these conduits transfer a slurry between different vertical levels within the DMS plant and include sections that maybe inclined to the vertical and/or include one or more bends. Due to its abrasive nature the flowing slurry abrades or wears the ' conduits from the inside. The abrasion or wear is concentrated at locations along the conduit where there is a change in direction of the flowing slurry. The changes in direction of the flowing slurry in the conduit are typically in the form of bends

and are an unavoidable design feature in the conduits. Although at other times there may be more subtle variations in the layout of the conduit or the interior shape or configuration that cause a change of direction to the slurry flow.

Failure of a conduit during operation of the DMS plant is undesirable. Accordingly operators of DMS similar plants, implement a maintenance program to replace all such conduits at ■regular intervals to minimize the risk and expenses associated with conduit failure. A typical replacement period is every 6 weeks of production time.

The present invention was devised with the view to extending the time between the required replacement of the slurry conduit. However resultant embodiments of the invention are believed to be applicable to other industries, processes and plants where conduits ducts or flow channels are worn by action of flowing fluids.

Summary of Invention

In one aspect the present invention provides a device for increasing turbulence in a fluid flowing through a conduit, the device comprising: two or more elements each of which is provided with an orifice through which fluid flowing through the conduit passes, wherein the orifice of each element is of a shape and/or configuration that increases turbulence in fluid flowing through the conduit downstream of the device when coupled with the conduit, and wherein at least two of the elements are spaced by a region through which fluid flows, the region having a shape and/or configuration different to that of both the two or more elements .

It has been found that by placing a device in accordance with an embodiment of the present invention upstream of a point in the conduit where it is desired to reduce wear, particularly localised wear points which may correspond to a location where the flow under goes a change in direction, i.e. a bend, abrasion and wear is reduced to the extent that the routine replacement of conduits can be extended significantly beyond the current 6 week period. Without wishing to be bound by theory it is believed that this occurs due to the device inducing turbulent flow that is maintained at least adjacent an inner circumferential surface of the conduit for at least a part of the length of the bend and has the effect of dispersing fluid energy over a greater volume of the flowing fluid. While this may increase overall wear over the length of the conduit subject to the turbulent flow, wear of localised points have found to be reduced.

In one embodiment, each element has an inner circumferential surface which defines the orifice and a radius of the inner circumferential surface along any line on the inner circumferential surface and parallel with a central axis of that element is constant.

Each element may also have an upstream face and a downstream face each of which lie in respective parallel planes, the planes being perpendicular to the central axis .

In one embodiment, the device comprises a housing defining a fluid flow path and in which the two or more elements are retained. The housing may have an outer dimension to allow insertion of the device into a conduit in a manner

where substantially all of the fluid flowing through the conduit flows through the fluid flow path. In this embodiment the device can function as a coupling for coupling two conduits together.

In one embodiment the device further comprises a first stop located at a first end of the housing and a second stop located at a second end of the housing, wherein each stop is provided with an orifice to allow fluid to flow therethrough, and wherein the one or more elements are retained between the first and second stops .

In one embodiment at least one of the first and second stops is demountably attached to the housing. In a further embodiment both of the first and second stops are demountably attached to the housing.

Each of ₍ the elements may take a general form of a washer having an outer circumferential surface and an inner circumferential surface, the inner circumferential surface defining the respective orifice.

The device may further comprise one or more spacers disposed between adjacent elements, to define the region spacing the two elements.

According to a further aspect of the present invention there is provided a conduit through which a fluid can flow, the conduit having a plurality of first fluid flow zones a first hydraulic diameter and a plurality of second fluid flow zones having a second hydraulic diameter, at least two of the first fluid flow zones being spaced by a second fluid flow zone, and wherein the first hydraulic

diameter is different to the second hydraulic diameter to induce or increase turbulence in fluid flowing through the conduit downstream of the first and second zones.

In one embodiment the conduit further comprises a bend downstream of the two first fluid zones. The two first fluid flow zones are located relative to the bend so that turbulent flow exists in the fluid prior to entry to the bend. The two first zones may be located relative to the bend and/or have respective hydraulic diameters arranged so, that at least a substantially turbulent flow is maintained for at least one half of an arc length of the bend and preferably for at least the arc length of the bend.

According to a further aspect of the present invention there is provided a method of processing ore comprising: forming a slurry from the ore; directing said slurry to flow through a conduit having one or more bends or points of change in direction to a slurry processing station; and, at one or more locations along the conduit, upstream of at least one of the bends or points inducing or increasing turbulence in the slurry flow.

In one embodiment the inducing or increasing of turbulence in the flow of the slurry is achieved by installing a device in accordance with the first aspect of this invention in the conduit at each of the one or more locations.

According to a further aspect of the present invention there is provided a mineral processing plant comprising:

a supply of a slurry; a processing station to which at least a portion of the slurry from the supply is to be delivered; and, a conduit providing fluid communication between the supply and the processing station, wherein either (a) a device in accordance with the first aspect of the present invention is coupled with the conduit; or (b) the conduit is in accordance with the second aspect of the present invention.

A further embodiment of the invention comprises a slurry line for conveying a slurry, the slurry line having at least two spaced apart flow influencing elements for influencing a flow of slurry through said slurry line, each flow influencing element having an aperture for flow of said slurry therethrough and said apertures having a hydraulic diameter different to the hydraulic diameter of the slurry line immediately upstream of the flow influencing elements and said hydraulic diameter of said apertures being at least 45% of the hydraulic diameter of the slurry line upstream of the flow influencing elements.

In one embodiment said flow influencing elements are separated by a distance of at least two and a half times an expected maximum dimension of a particle in the slurry.

Each aperture is bound by a respective edge. In one embodiment the edge is spaced by a substantially constant radial distance from the central axis of the conduit. However in an alternate embodiment the edge is spaced from a central axis of the conduit by a distance that varies between a first radius and a second radius. The variation between the first and second radius may be at least two

and one half times an expected maximum dimension of a particle within said slurry.

In one embodiment the edge has a substantially sinusoidal circumferential profile. The radius of the sinusoidal profile is at least one and one quarter times the expected maximum dimension of a particle in said slurry.

The flow influencing elements can be separated by a distance up to 45% of the hydraulic diameter of the slurry line upstream of the flow influencing elements .

In one embodiment said flow influencing elements have an axial thickness of at least 3% of the hydraulic diameter of the slurry line upstream of the flow influencing elements .

Additionally the thickness of said flow influencing elements may be limited to 45% of the hydraulic diameter of the slurry line upstream of the flow influencing elements .

In one embodiment of the slurry line the flow influencing elements extend over a distance of at least 50% of the hydraulic diameter of the slurry line upstream of the flow influencing elements .

In another embodiment of the slurry line the influencing elements extend axially over a distance of at least 75% of the hydraulic diameter of the slurry line upstream of the flow influencing elements .

One embodiment of the slurry line can be formed so that the axial length of said flow influencing elements extend over a distance not exceeding five hydraulic diameters of the slurry line upstream of the flow influencing elements.

A method of processing an abrasive ore comprising: treating said ore at a first processing station; supplying a slurry of processed ore from said first processing station to a slurry line; transporting said slurry in said slurry line to a second processing station; and causing said slurry to flow through at least two flow influencing elements each having an aperture through which said slurry flows and each being located between said first processing station and said second processing station and having a hydraulic diameter of at least 55% of the hydraulic diameter of the slurry line upstream of the flow influencing elements .

In an embodiment of the method of processing ore the flow influencing elements are separated by a distance of up to 45% of the hydraulic diameter of the slurry line immediately upstream of the flow influencing elements.

The method of processing ore may further comprise spacing the flow influencing elements by a distance of at least two and one half times an expected maximum dimension of a particle within said slurry.

According to a further aspect of the present invention there is provided a device for modifying fluid flow through a conduit having a hydraulic diameter dc the device comprising:

a fluid flow path having at least two flow zones Zl and Z2 and an intermediate zone Zi between the flow zones Zl and Z2 , where the two flow zones Zl and Z2 have respective hydraulic diameters dzl,dz2 both being less than dc, and the intermediate zone Zi has a hydraulic diameter dzi greater than each of dzl and dz2, and the intermediate zone Zi has a axial flow path length of at least 0.03dc.

In one embodiment the zones Zl and Z2 may each have a hydraulic diameter governed by: Adc ≤ dzl, dz2 ≤ Bdc [A = 0.45, B = .9]

The intermediate zone Zi may have a hydraulic diameter in the range: .7d2 ≤ dzi ≤ 1.3dc. However in an alternative embodiment the hydraulic diameter may be in the range .9d2 ≤ dzi < dc.

The zones zl, z2 may each have an axial flow path length up to .45dc. Moreover the fluid path length of the device may be between 0.03dc x nz to 0.5 x nz, where nz is the number of zones in the device .

Each zone may comprise an element having an inner circumferential surface where respective zones are defined by the inner circumferential surface of its respective element .

In a simple embodiment each of the flow zones may be formed with an inner circumferential surface of constant radius . However in a more complex embodiment each of the flow zones may be formed with an inner circumferential surface may follow an undulating path such as, but not limited to, a sinusoidal path. More particularly each flow zone may have an inner circumferential surface comprising first and second portions having different radius. Further it is envisaged that adjacent flow zones

may be arranged so that the portions of different radius are circumferentially offset.

Brief Description of Drawings

The embodiments of the present invention will now be described, by way of example only with reference to the accompanied drawings in which:

Figure 1 is a section view of an embodiment or device in accordance with the present invention installed in a conduit;

Figure 2 is a partial section view of the device shown in

Figure 1 ;

Figure 3 is an end view of the device shown in Figures 1 and 2;

Figure 4 is a partial exploded view of the device shown in

Figures 1-3;

Figure 5 is a perspective view of the device shown in

Figures 1-4; Figures 6A is an end view of a first element incorporated in the device shown in Figures 1-5;

Figure 6B is a side view in partial section of the element shown in Figure 6A;

Figure 6C is a perspective view of the elements shown in Figures 6A and 6B;

Figure 7A is an end view of a second element incorporated in the device shown in Figurel-5;

Figure 7B is a side view and partial section of the second element shown in 7A; Figure 7C is a perspective view of the second element shown in figure 7A and 7B;

Figure 8A is a first end view of a stop incorporated in the device shown in Figures 1-5;

Figure 8B is a side view in partial section of the stoption in Figure 8A;

Figure 8C is a perspective view of the stoption Figures 8A and 8B; and

Figure 9 is a schematic representation of an embodiment of a mineral processing plant incorporating a flow influencing device.

Detailed description of the preferred embodiment

The present embodiment is described with reference to a dense medium separator (DMS) plant used for concentrating iron ore (the "target mineral") from a feed material comprising iron based mineral together with gangue material. In this particular process the feed material is added to a dense liquid medium which comprises a mixture of water and ferro silicon. The liquid medium has a specific gravity of approximately 3.0. The iron based mineral has a greater specific gravity and therefore sinks in the liquid medium. The gangue material on the other hand has a lower specific gravity than the liquid medium and therefore floats. Various processing stations are used to separate the gangue material from the iron based mineral on the basis of the difference in specific gravity. The iron based feed material is comprised of generally coarse hard particles with sharp edges and is relatively abrasive. Together with the liquid medium the feed material forms an abrasive slurry that is gravity fed through conduits between various processing stations of the DMS plant . The conduits are in the form of polyurethane hoses that extend substantially vertically from the separator to the further processing station. The hoses however do not always hang perfectly vertically and may also include one or more bends of tight radius along their length. The wear in the hoses is typically concentrated at the bends .

The embodiments of the present invention have in preliminary testing been found to assist in reducing the wear rate of the hoses at the bends.

The accompanied drawings illustrate one possible embodiment of the present invention in the form of a device 10 that is coupled to or installed in a conduit 12. Thus all fluid flowing through the conduit 12 also passes through device 10. The device 10 comprises two or more elements 14.1, 14.2 (here and after referred to in general as 'elements 14') each of which is provided with a respective orifice 16.1, 16.2 (here and after referred to in general as Orifices 16') through which the fluid flowing through the conduit 12 passes.

In the illustrated embodiment, there are four the elements 14.1, and four the elements 14.2. However it is believed that the total number of elements 14 may be varied from a minimum of two. The elements 14 are spaced by regions 18 defined by respective spacers 20. Each region 18 is defined by an orifice 22 formed in a corresponding spacer 20. The orifice 16 of each of elements 14 is of a shape and/or configuration that induces turbulence in fluid flowing through the device 10. The orifice 22 of the region 18 (i.e. spacer 20) has a different shape and/or configuration to that of both the orifices 16 and may also contribute to turbulence induced by the device.

Possible shapes and/or configurations of the orifices 16 that have the effect of increasing turbulence in fluid flowing through the conduit are ones which provide the orifice 16 with a hydraulic diameter different to and typically less than the hydraulic diameter of the conduit 12.

The hydraulic diameter d is defined as: d = 4 x cross sectional area / wetted perimeter.

Thus assuming the conduit 12 to have a circular cross section, the hydraulic diameter dc of the conduit 12 is simply the internal diameter of the conduit 12. The

hydraulic diameters d ₁₍ d ₂ of the elements 14.1, 14.2 may be defined as follows: • 45 _dc < (d _x , d ₂ )< .9 _dc

The orifice 22 of the spacer 20 which forms an intermediate zone between the two elements 14 may have a hydraulic diameter di as follows :

.7dc - di ≤ 1.3d _c and various ranges within these limits such as .9d _c ≤ di ≤ d _c

The turbulent flow created by the elements 14 need not exist across the entire diameter of the conduit 12. Turbulence in an annular zone adjacent an inner circumferential surface of the conduit 12 is believed sufficient to achieve reduction in wear notwithstanding the existence of lamina flow of slurry interior of the annu1ar turbulent flow.

Looking at the present embodiment in greater detail, the device 10 comprises an outer housing 24 in which the elements 14 and spacers 20 are disposed, and first and second stops 26, 28 coupled at opposite axial ends of the housing 24. The device further comprises a flanged element 30 located midway along the axial length of the housing 24.

The housing 24 defines fluid flow path for slurry flowing through the device 10 and conduit 12 and comprises two cylindrical sleeves 32 each of which has one end fixed to the flanged spacer 30. The fixing may be achieved by any conventional means including by screw threads, for a demountable fixing (or coupling) or by welding for a permanent fixing. The flanged spacer 30 has a flange 34 that extends radially outwards from a circumferential surface of the sleeves 32. The elements 14 and spacers 20 are inserted into the housing 24 through ends of the respective sleeves 32 distant the flange spacer 30. The elements 14 and spacers 20 are then retained in the

housing 24 by the stops 26 and 28 that are fixed to the ends of the housing. Demountably fixing the stops 26, 28 to the housing has a potential benefit of allowing reconditioning of the device 10 for example by replacement of selected elements 14 and/or spacers 20.

The outer diameter of the stops 26 and 28, and the housing 24 are substantially the same as each other, and marginally less than the inner diameter of the conduit 12, with the flanged element 30 having a diameter greater than the inner diameter of the conduit 12. Accordingly the sleeves 32 and stops 26, 28 fit within the conduit 12 with a degree of clearance, and ends of separate lengths of the conduit 12 can abutt opposite sides of the flange 34. Clamps (not shown) may be provided to secure the lengths of the conduit 12 to the device 10. However in an alternative embodiment a plurality of ribs may be formed on the outer circumferential surface of the sleeves 32 to engage and grip, the inner surface of the lengths of the conduit 12. Alternatively, the housing may be provided with flanges that connect with corresponding flanges on conduit 12.

With particular reference to Figures 6a-6c each element 14.1 of the preferred embodiment is in a form of a planar disc or washer having an outer circumferential surface 36 of constant radius but an inner circumferential surface 38 that is profiled, having a radius measured from a central axis A of the device 10 (and conduit 12) that varies between a minimum radius rl and a maximum radius r2. The inner circumferential surface of the elements 14 define the orifice 16. While the radius varies between rl, and r2 in a circumferential direction, the radius is constant along any line on the inner circumferential surface that is parallel to the central axis A. For example in Figure 6c the radius ra is constant along the line Ia. Thus the shape and orientation of upstream and downstream inner

circumferential edges 17a, 17b of any particular element are identical. It will also be apparent that upstream and downstream faces 19a, 19b of each element lie in respective parallel planes, the planes being perpendicular to the central axis A.

Figures 7a-7c depict an embodiment of the flanged element 30. This element is of the same general configuration of the element 14.1 but with the addition of the outer flange 34 that extends in a radial direction. The flange 34 is located centrally of an axial length of the element 30. The element 30 also has a greater axial length than the element 14.1 so as to produce outer shoulders or seats 40 that fit within, and facilitate fixing to, the sleeves 32. The element 30 has an inner circumferential surface 42 of the same configuration as the inner surface 38 of the element 14.1.

With reference to Figure 4 , both the elements 14.2 and the spacers 20 are in the form of disc or washer having inner and outer circumferential surfaces of constant radius. The radius of the outer circumferential surface of the elements 14.2 and spacer 20 are the same as each other. However radius r ₃ of the inner circumferential surface 44 of the element 14.2 is less than radius r ₄ of the inner circumferential surface 46 and the spacer 20. Further, the radius r4 is greater than the radius r2 (Fig 6a) , and the radius r3 is equal to rl (Fig 6a) though it may also be of a different size to either or both rl and r2.

From the view point of fluid flow through the device 10, the elements 14.1, 14.2 and spacers 20 are equivalent to the fluid flow zone of a shape and/or configuration identical to that of respective orifices 16.1,16.2 and 22

Figures 8a-8c depict an embodiment of the stops 26,28. Each stop 26,28 is in the form of an annular ring 48.

Each ring 48 has an outer circumferential surface having a major section 50 of an outer diameter equal to the outer diameter of the sleeves 32, and a contiguous second section 52 of a reduced outer diameter. The section 52 fits within an end of a sleeve 32, sleeve 32 abutting the section 50. The ^" rings 48 can be fixed to the sleeves 32 by any conventional means including welding or the use of mating screw threads. Inner circumferential surface of 54 of each ring 48 is formed with a radius that decreases in a direction from the section 50 to the section 52. The minimum radius r5 of the ring 44 is greater than the radius r4 of the spacers 20.

Figure 9 depicts an embodiment of a mineral processing plant 60 incorporating a device 10. The plant 60 comprises mineral processing stations 62 and 64, and a hose or conduit 66 through which slurry is conveyed or transported from station 62 to 64. The hose or conduit 66 may be made of a material that is flexible and softer than the materials being conveyed. Examples of this include, but are not limited to, hoses made of polymeric substances such as polyurethane; and, rubber including reinforced rubber. As previously described the materials being conveyed are typically abrasive in nature and in order to extend the service life of the device 10 it is prudent to arrange for the portions or components of the device 10 through which material flows, e.g. the elements 14 and spacers 20 to be made of a material of a comparable or greater hardness than the hardness of particles within the slurry. In the plant 60 the station 62 is physically above the station 64 and the device 10 is placed upstream of bend 68 in the conduit 66. The above relationship between the device 10, hoses and slurry material is exemplified in the test described below.

Preliminary tests have been conducted in relation to a device in accordance with the above described embodiment

of a DMS plant for concentrating iron ore. This device was installed in a 200mm polyurethane conduit or hose used for the transport of slurry between processing stations of the DMS plant. The slurry comprised iron ore in a liquid medium comprising a mixture of water and ferro silicon in the approximate ratio 1:10. The iron ore comprises particles that were passed through a 6mm screen. The effect of the installation of the device 10 in the conduit was to extend the time between routine replacements of the conduit from 6 weeks to 12 weeks of production time. In the devices tested, each of the elements 14, spacers 20, and stops 26,28 were made from mild steel. The outer radius of the housing 24 was 197mm with radiuses rl-r5 as follows : rl = 60mm r2 = 80mm r3 = 60mm r4 = 75mm r5 = 182.5mm The outer radius of the elements 14, and spacers 20 is 91mm. The outer radius of the flange 34 of the flanged element 30 is 115mm. Each of the elements 14 and spacers 20 have a thickness or axial width of approximately 16mm, with the width or axial iength of the flange element 30 being in the order of 30mm.

Given these dimensions, the hydraulic diameters for various components of the device 10 are as follows: Hydraulic diameter of the elements 14.1(dl) = approximately 95 - 100mm. The Hydraulic diameter of the elements 14.2 (d2) = 120mm

The hydraulic diameter of the spacers 20 (di) = 150mm The hydraulic diameter dc of the conduit 12 equals 200mm.

Inspection of embodiments of the device 10 in use indicate substantial wear of the first element 14.1 and element

14.2 at the upstream end of the device 10 with reduced wear on the adjacent downstream elements 14.1 and 14.2.

Initial testing indicates noticeable effects of the device 10 when the axial length of the elements 14.1 , 14.2 is at least 0.03d _c (i.e. 3% of the hydraulic diameter of the conduit 12) . The axial length of the elements 14 and spacers 20 may be up to approximately .45d _c (i.e. 45% of the hydraulic diameter) . The overall length of the device 10 may be between 0.03d _c n to 0.5d _c n where n is the number of individual elements 14 and spacers 20 within the device 10, and d _c is the hydraulic diameter of the conduit 12. ^"

The elements 14.1 that comprise the profiled inner circumferential surface maybe the axially aligned or axially offset relative to each other. In the event that the elements 14.1 are axially aligned their respective radii rl and r2 are aligned. However in the event of a maximum offset, the radius rl of one element 14.1 is axially aligned with the radius r2 of an adjacent element 14.1. Of course the offset between adjacent elements 14.1 and 14.2 can range anywhere there between.

In the above embodiment, the device 10 is described as being comprised of individual elements and spacers.

However it is also envisaged that the device 10 maybe formed as a single integrated unit for example by way of molding. In such an embodiment it would be more appropriate to refer to fluid flow zones (as described above) rather than elements 14 and spacers 20.

Various parameters of the device 10 may also be defined in terms of the maximum expected dimension of particles within a slurry flowing through the device. It should be understood that while the particles may be passed through say a mesh screen prior to mixing with a liquid to form the slurry the maximum dimension of a particle can readily

exceed the mesh size of the screen. For example a particle having dimension of 4mm x 4mm x 8mm can pass through a 5mm square mesh screen.

In terms of particle size it is believed that in one embodiment the elements 14 may be separated by a distance of at least two and a half times an expected maximum dimension of a particle in the slurry. In addition the shape and configuration of the inner circumferential surface of the elements may be arranged to provide an increase in turbulent flow while minimising the probability of blockage due to accumulation of particles in a slurry. This may be achieved by providing an inner- circumferential surface that is profiled or that has protrusions or surface irregularities. A minimum gap or space between such profiled elements, protrusions or irregularities is preferably greater than the expected maximum dimension of the particles forming the slurry. Thus with reference in particular to Figure 6a the difference between the radii rl and r2 (representing a

"depth" of a trough in the inner surface) may be at least 1.25 times and preferably at least 2.5 times a maximum particle size.

Additionally the distance between adjacent peaks on the inner surface may be at least 1.25 times and preferably at least 2.5 times a maximum particle size.

Now that the embodiment of the present invention has been described it would be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts . For example while the embodiment depicts the device 10 comprising four elements 14.1, four elements

14.2, eight spacers 20, and a flanged element 30, different numbers of such elements and spacers maybe used however it is believed that a minimum of two spaced apart elements 14 is required. Additionally, the flanged element 30 maybe replaced by forming the housing 24 as a single sleeve with a flange extended radially outward from an outer circumferential surface of the sleeve. While the elements 14.1 are depicted as having an inner circumferential surface following a substantially sinusoidal path, different configurations may be incorporated. Indeed, it is not a requirement that the elements 14.1 have a profiled inner circumferential surface. In an alternate embodiment the elements 14 (or corresponding fluid flow zones) may be provided with an inner circumferential surface that is oval shaped, non- symmetric or even of constant radius . In yet a further embodiment the elements 14.1 or fluid flow zones may be formed with orifice of constant radius or generally identical shape but with their central axis radially offset from a central axis of the device 10. In such an embodiment the/ center of the orifice of such elements may also be offset relative to each other about the central axis of the device 12. In yet another embodiment each of the elements 14 and the spacers 20 may be provided with radially extending flanges similar to the flange 34 on the flanged element 30, and a plurality of such flanged elements 14 and 20 could then be coupled by mechanical fasteners such as bolts, to flanges provided at adjacent ends of lengths of conduit 10. Such an embodiment may also incorporate seals and/or gaskets between the flanges on the conduit and flanges on the elements 14 and spacers 20. This embodiment does not require the use of the housing 24 nor the stops 26,28 as all of the elements 14 and spacers 20 are coupled to each other and respective flanges on the conduit by the mechanical fasteners.