Induced vortex particle separator

The induced vortex particle separator is a device for separating solid particulate matter from a liquid containing such particulate matter. The liquid enters a housing through an inlet port and is driven about a helical vane to form a helical flow path. Upon exiting the helical vane, the liquid is received within a central portion of the housing where a centralized structure including an annular stator and an inverted diffuser cone drive the liquid to form a free vortex. Under centrifugal force, the solid particulate matter is separated from the liquid and flows, under the force of gravity, into a lower region of the housing. Due to a negative pressure differential, the liquid is driven upwards within an inner cylindrical shell mounted within the housing to flow into a siphon for output through an outlet port.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to centrifugal particle separators, and particularly to an induced vortex particle separator in which solid particulate matter is separated from a liquid through the inducement of a free vortex within the liquid.

2. Description of the Related Art

Solid particulate matter suspended in a liquid is commonly removed from the liquid through use of a hydroclone or cyclone type separator. In such a separator system, the fluid is driven into a forced-vortex path, with centrifugal forces driving the relatively heavy-density particulate matter to the wall of the separator, similar in action to a centrifuge. Such systems typically include some sort of filtering apparatus located against the wall of the separator for collecting the particulate matter.

Such filters or collectors, however, must be removed from the separator and separately cleaned, which can be a messy and laborious process. Further, such systems are ineffective in removing fine particulate matter, which may remain suspended in the liquid. By the fluid dynamic nature of the forced vortex, the particulate matter only migrates towards a region where it can be easily removed and collected when there is a substantial difference in densities between the particulate matter and the liquid.

A free or irrotational vortex is a non-forced vortex. Such vortices are typically found in weather patterns and drainage systems; i.e., the vortex generated by the Coriolis Effect is a free vortex. Such free vortices have pressure variations in the fluid flow which are dependent upon the radius within the vortex. A forced vortex separator, such as a hydroclone separator, is not capable of taking advantage of these effects to aid in the removal of fine particulate matter. It would be desirable to provide a cyclonic or vortex-type particle separator that takes advantage of the free vortex properties. Thus, an induced vortex particle separator solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The induced vortex particle separator includes a housing having a substantially cylindrical sidewall, and closed upper and lower ends. The housing is divided into an upper region, a central region and a lower region, with an inlet port being formed through the upper region of the housing and an outlet port being formed through the lower region of the housing.

An inner cylindrical shell having a diameter associated therewith which is less than a diameter of the substantially cylindrical sidewall of the housing is mounted to the closed upper end of the housing and is positioned coaxially therewith. The inner cylindrical shell extends between the closed upper end and the central region of the housing. A helical vane is mounted to an outer surface of the inner cylindrical shell and an inner surface of the substantially cylindrical sidewall, with the helical vane extending therebetween.

An annular stator is mounted to the inner surface of the substantially cylindrical sidewall within the central region of the housing, with the annular stator defining a central opening, and having at least one flow passage defined therethrough. An inverted diffuser cone is mounted within the central opening of the annular stator and extends upwardly therefrom. The inverted diffuser cone has a central passage formed therethrough.

Further, a siphon nozzle having an open upper end, an open lower end, and a central portion is provided, with the central portion thereof being received within the central passage of the inverted diffuser cone such that the open upper end of the siphon nozzle is positioned within a lower end of the inner cylindrical shell. The open lower end of the siphon nozzle is joined to the outlet port of the housing.

A collector ring having a central passage formed therethrough is mounted to the siphon nozzle with the siphon nozzle projecting through the central passage. The collector ring is mounted above the inverted diffuser cone.

In operation, liquid containing particulate matter is input into the induced vortex particle separator through the inlet port. The liquid is induced into a helical flow path by the helical vane, and a free vortex region is formed between the annular stator, an outer surface of the inverted diffuser cone, a lower end of the inner cylindrical shell, a lower surface of the collector ring and the inner surface of the substantially cylindrical sidewall. Within the free vortex formed in the liquid, particulate matter is separated from the liquid under centrifugal force.

Relatively high density particulate matter achieves the greatest diameter in the vortex path and settles adjacent the inner surface of the housing. Particulate matter having a lower density is deflected by the outer surface of the inverted diffuser cone, and both streams of particulate matter (and some remaining liquid) pass through the at least one flow passage of the annular stator, under the force of gravity. The particulate matter (and some liquid) collects within the lower region of the housing for later retrieval and disposal thereof. The liquid flows into the lower end of the inner cylindrical shell due to the fluid pressure in this region being less than that within the free vortex region, and then passes into the siphon nozzle to be selectively expelled through the outlet port.

Preferably, a sludge drainage port is formed through the closed lower end of the housing, and a drainage nozzle is mounted to an exterior surface of the housing, with the drainage nozzle covering and selectively sealing the sludge drainage port. A secondary annular stator may be mounted to the inner surface of the substantially cylindrical sidewall, within the lower region of the housing. A secondary diffuser cone is mounted within the stator, similar to the primary stator and diffuser cone described above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed towards an induced vortex particle separator10. As shown inFIG. 1, the induced vortex particle separator10includes a housing14having a substantially cylindrical sidewall, and closed upper and lower ends15,17, respectively. The housing14is divided into an upper region16, a central region26and a lower region18. An inlet port13is formed through the upper region16of the housing14, and an outlet port19is formed through the lower region18of the housing14. An inlet nozzle12, shown inFIGS. 1 and 2, is mounted to housing14and covers inlet port13for selective insertion of fluid therethrough. Similarly, an outlet or discharge nozzle20covers outlet port19, for selective expulsion of liquid therethrough, as will be described in greater detail below. Preferably, the housing14has a diameter of D1and the height of housing14is at least 6D1. Discharge nozzle20is preferably positioned at least 4D1from the upper end15of housing14.

An inner cylindrical shell24having a diameter D2associated therewith, which is less than the diameter D1of the substantially cylindrical sidewall of the housing14, is mounted to the closed upper end15of the housing14and is positioned coaxially therewith. The inner cylindrical shell24extends between the closed upper end15and the central region26of the housing14, as shown inFIG. 1. As shown inFIGS. 1 and 3, a helical vane22is mounted to an outer surface of the inner cylindrical shell24and an inner surface of the substantially cylindrical sidewall, with the helical vane22extending therebetween. The particular contouring of the helical vane22will be described in detail below.

As best shown inFIGS. 1 and 5, an annular stator34is mounted to the inner surface of the substantially cylindrical sidewall within the central region26of the housing14, with the annular stator34defining a central opening35, and having at least one flow passage37defined therethrough. An inverted diffuser cone32is mounted within the central opening35of the annular stator34and extends upwardly therefrom. The inverted diffuser cone32has a central passage39formed therethrough.

Further, a siphon nozzle30having an open upper end, an open lower end, and a central portion is provided, with the central portion thereof being received within the central passage39of the inverted diffuser cone32such that the open upper end of the siphon nozzle30is positioned within a lower end of the inner cylindrical shell24. The open lower end of the siphon nozzle30is joined to the outlet port19of the housing14, as shown inFIG. 1. Siphon nozzle30preferably has a length between approximately 0.5D1and 1.5D1in order to generate a proper pressure differential, as will be described in detail below.

A collector ring28having a central passage41formed therethrough is mounted to the siphon nozzle30with the siphon nozzle30projecting through the central passage41. The collector ring28is mounted above the inverted diffuser cone32. As will be described in detail below, fluid flows along flow path F2between collector ring28and inner cylindrical shell24. The fluid flows through a region having a cross-sectional area of A4(best shown inFIG. 4), which preferably is between approximately 0.5 and 1.5 times the cross-sectional area of the helical flow path A3(to be described below in greater detail). The area A4is determined by the physical characteristics of the fluid in order to generate the proper pressure differential for generating flow path F2.

In operation, liquid containing particulate matter is input into the induced vortex particle separator10through the inlet nozzle12. Input liquid is shown by directional flow arrow I inFIGS. 1 and 2. The liquid is induced into a helical flow path F1by the helical vane22(within upper region16). Upon exiting upper region16and entering central portion26(best shown inFIG. 5), a free vortex is formed between the annular stator34, an outer surface of the inverted diffuser cone32, a lower end of the inner cylindrical shell24, a lower surface of the collector ring28and the inner surface of the substantially cylindrical sidewall of housing14. Within the free vortex formed in the liquid, particulate matter is separated from the liquid under centrifugal force.

Relatively high density particulate matter achieves the greatest diameter in the vortex path and settles adjacent the inner surface of the housing14. The high density particulate matter falls towards stator34and through passage37under the force of gravity (shown by directional flow line F3inFIG. 5). Particulate matter having a lower density is deflected by the outer surface of the inverted diffuser cone32, and also passes through the at least one flow passage37of the annular stator34, under the force of gravity (shown by directional flow line F4). The annular stator34preferably includes fixed vertical vanes, which prevent any unwanted angular momentum remaining in the particulate matter.

The particulate matter (and some liquid) collects within the lower region18of the housing14for later retrieval and disposal thereof. The remaining liquid flows into the lower end of the inner cylindrical shell24due to the fluid pressure in this region being less than that within the outer and lower free vortex region (shown by directional flow arrow F2), and then passes into the siphon nozzle30(shown by directional flow arrow F5) to be selectively expelled through the outlet port19and nozzle20. Some fine particulate matter may travel along flow path F2with the liquid. These particles, however, fall, under the force of gravity, from the liquid to collect on the upper surface of collector ring28, which forms a receiving shelf. The flow into the siphon nozzle along F5is a substantially liquid-only flow.

In the above, the liquid flow is typically incompressible fluid flow governed by the constant flow equation Q=UA, where Q is flow in cubic feet per second (cfs), U is fluid velocity in feet per second (ft./sec.), and A is the cross-sectional area in square feet (ft.2) of liquid pathway. Flow I, entering the system, preferably has a velocity of between approximately 7.5 ft./sec. and 15 ft./sec.

The flow rate Q remains substantially constant throughout the process so that the mean velocity of the fluid Umwithin upper section16can be expressed as

Um=U1·A1A3=U1·π⁡(d1)2/4w1⁢h3,
where U1is the initial velocity of input flow I, A1is the cross-sectional area of nozzle12, A3is the cross-sectional area of the pathway defined between adjacent walls of helical vane22, d1is the diameter of nozzle12, w1is the width of flow through vane22, and h3is the height of flow through vane22.

When the fluid exits the upper region16and enters the central region26, to form the free vortex, the angular momentum of the fluid remains substantially constant, but the fluid streamlines become undefined. Particulate matter with a density greater than the liquid migrates to the inner wall of the housing14, and moves downward towards the stator34, both under the force of gravity and further due to the fluids downward momentum (from the helical pathway of region16).

Due to the geometry of central region26, the fluid flow streamlines remain concentric, but the particulate matter ceases to rotate about the central axis because the centripetal force, created by the helical vane22and the inner wall of the housing, is no longer present.

The free vortex is similar to natural vortices formed due to the Coriolis Effect. In a forced vortex (such as that driven by vane22), the tangential velocity of the fluid is given by Uθ=ω·r, where ω is the angular velocity of the fluid and r is the mean radius of flow. In a free or Coriolis-type vortex, the tangential velocity is given by

Uθ=Γ2⁢⁢π⁢⁢r,
where Γ is the fluid dynamic circulation. The circulation for a generalized fluid having a fluid velocity of {right arrow over (V)} about a closed path C is given by

Γ=∮C⁢V⇀·ⅆs⇀.
In the expression for Uθ, we see that tangential velocity increases as radius decreases. Thus, the pressure decreases as the radius decreases, causing the flow F2ofFIG. 5.

Helical vane22may have any desired length or contour, though in the preferred embodiment, helical vane22only completes two full revolutions about the inner shell24, and has a pitch angle α defined by

α=Nπ,
where N is the number of revolutions per mean diameter. The mean diameter is expressed in terms of the diameter of the housing14D1and the diameter of the inner cylindrical shell24D2:

Dm=D2+D1-D22.
Preferably, the height of the helical flow path h3is

DmN
and the width w1is simply given by

Preferably, a sludge drainage port51is formed through the closed lower end17of the housing14, and a drainage nozzle40is mounted to an exterior surface of the housing14, with the drainage nozzle40covering and selectively sealing the sludge drainage port51. A secondary annular stator36may be mounted to the inner surface of the substantially cylindrical sidewall, within the lower region of the housing14. A secondary cone38is mounted within the stator36, similar to the primary stator and diffuser cone described above.

The secondary stator36preferably includes vertical vanes, similar to the primary stator, for preventing unwanted angular flow of the particulate matter and remaining liquid, which forms a sludge. The cone38is provided for directing solids into the liquefied sludge region18.