Multiple vortex waste separator apparatus

A multiple vortex separator for drawing a substantially moisture-free airstream from a waste stream having an annular channel defining a first vortex flow path for separating liquid and solid waste from this waste stream and an inverted conical cavity between nested inverted cones defining a second vortex flow path that is isolated from the first vortex flow path for separating additional liquid and solid waste from the waste stream before it exits the vortex separator.

FIELD OF THE INVENTION

This invention pertains to systems for separating aircraft waste and, more particularly, to a multiple vortex apparatus for removing solid and liquid waste from a waste stream from aircraft toilets or other receptacles while withdrawing a substantially moisture-free airstream under suction.

BACKGROUND OF THE INVENTION

Various systems are available in the art that employ a vacuum to transport liquid and solid waste material from aircraft toilets or other receptacles to a waste tank for storage. The waste material that is transported includes solid human waste, urine, water, optionally cleansing and disinfecting chemicals, air, toilet paper, food, and often unexpected discarded items, all of which are drawn from the aircraft toilets or other receptacles to one or more waste tanks. The waste tanks, of course, are emptied during ground servicing of the aircraft.

The suction that transports the waste material to a waste tank is usually provided by a vacuum generator when the aircraft is on the ground or at low altitudes. At higher altitudes, the system typically will be vented to the external lower pressure atmosphere, creating a pressure differential between the exterior atmosphere and the interior of the aircraft to draw the waste material from the aircraft toilets or other receptacles for transport to the waste tank for storage.

As the waste material is transported to the waste tank, the air which was drawn along with the waste material must be released to the atmosphere. This air must be free of moisture and particulate solids for sanitary and for safety reasons. As to sanitary concerns, it is obviously undesirable to release particulate human waste into the atmosphere, either when the aircraft is airborne or when it is on the ground. Additionally, there is a danger that if a substantial amount of water escapes the aircraft from such a vacuum driven aircraft waste collection system, it may build up on the aircraft fuselage to form ice.

Conventional aircraft waste material separation systems are large and so require excessive space in the aircraft while contributing unnecessarily to the aircraft weight, reducing its fuel efficiency. Also, conventional waste material separation systems require frequent servicing, which is often difficult and time-consuming to perform because of inconvenient access to the separator apparatus. Additionally, conventional waste material separation systems typically have two separators, one at the inlet and another at the outlet of the systems. Finally, conventional separation apparatus, while often effective in removing moisture from the waste material under optimal conditions, could nevertheless be improved by ensuring that the apparatus consistently prevents the escape of moisture.

Thus, the need exists for an improved waste material separation system using a single separator making for an overall system that is compact and lightweight without compromising its performance. It should also be consistently effective in minimizing or preventing the escape of moisture in the outgoing airstream. Additionally, the apparatus must be capable of being easily and safely replaced with minimal exposure to the collected waste. Finally, the apparatus should also be capable of being easily installed in the limited space available in the aircraft. The present invention satisfies all of these requirements and has other benefits as well.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a multiple vortex separator for drawing a substantially moisten-free airstream from a waste stream containing liquid and solid waste. The separator is particularly well adapted for use in aircraft. The separator of the invention includes a housing, which is preferably cylindrical in shape, and has a waste inlet for receiving the waste stream. The top of the cylindrical housing is enclosed and has an exhaust port for drawing the substantially moisture-free airstream from the housing by way of suction force provided by a vacuum generator or, at high altitudes, the pressure differential between the exterior atmosphere and the interior of the aircraft.

An annular channel is positioned along the inner surface of the cylindrical wall of the housing. This channel defines a first vortex path for separating liquid and solid waste from the waste stream. The annular channel is in communication with the waste inlet.

A pair of nested inverted cones is located within the cylindrical housing. These cones define an inverted conical cavity that is in communication with the exhaust port. A second vortex flow path which forms within the conical cavity thus is isolated from the first vortex path.

Accordingly, a waste stream containing liquid and solid waste is drawn into the housing through the waste inlet by a suction force applied to the exhaust port. The entering waste stream encounters the annular channel along the inner surface of the housing wall, moving in a first vortex flow path in which liquid and solid wastes are separated from the waste stream by centrifugal force. As a result, the heavier waste materials move to the outside of the annular channel and fall downwardly for collection as appropriate. The remaining lighter airstream enters the inverted conical cavity between the nested cones in a second vortex path that is isolated from the first vortex path. Additional liquid and solid waste is removed from the airstream moving through the conical cavity again by centrifugal force to produce a substantially moisture-free airstream which exits from the vortex separator through the exhaust port. The source of suction will be either the cabin to atmosphere differential at high altitudes or a vacuum generator at low altitudes.

In a preferred embodiment, radially disposed vanes are positioned adjacent the entrance of the conical cavity. These vanes are angled about their radial axes to form angled slots for inducing and enhancing rotary motion in the airstream passing through the slots into the conical cavity.

The inner surface of the inner cone defines an inner conical chamber. A barrier extends between the cones forming a top closure of the conical cavity. Finally, at least one interconnecting port is located in this top closure communicating between the conical cavity and the inner conical chamber. Thus, the airstream moving through the separator passes from the conical cavity into the inner conical chamber through the interconnecting port.

The inner conical chamber may have a check valve at its bottom adapted to open when the separator is not drawing a waste stream into the cylindrical housing. When this happens, liquid and solid waste that has collected in the inner conical chamber will fall from the chamber to be collected as appropriate. Also, a filter medium may be disposed in the chamber to coalesce moisture remaining in the airstream that passes through the chamber.

Finally, an exhaust member may be generally centered in the conical chamber. The exhaust member has an annular shelf positioned above the chamber and the top closure of the cones. It also has a central tubular portion projecting downwardly into the chamber defining an exit conduit leading from the chamber to the top of the cylindrical housing of the separator. Thus, the airstream exiting the chamber will pass through the tubular portion before being removed from the top of the housing via the exhaust port. Finally, a demister filter may be disposed across the top opening of the tubular portion to help remove any remaining moisture in the exiting airstream.

The embodiment of the invention described below is not intended to be exhaustive or to limit the invention to the precise structure and operation disclosed. Rather, the embodiment described in detail below has been chosen and described to explain the principles of the invention and its application, operation and use in order to best enable others skilled in the art to follow its teachings.

Turning now toFIG. 1, the exterior of a waste tank10having a multiple vortex waste separator12in accordance with the invention is illustrated. The vortex separator12includes a housing14that is preferably cylindrical as shown and an exhaust cap16with an exhaust port atop the housing. The exhaust cap may be removably clamped to the top of the cylindrical housing to permit access to the interior of the separator when desired. Exhaust tube18will be connected as shown diagrammatically to a source of suction comprising a vacuum generator22at low altitudes or the external atmosphere at high altitudes24to draw waste from aircraft toilets or other receptacles by way of the vortex separator. The switching is achieved with an altitude-sensitive bypass check valve20.

Vortex separator12has an inlet tube26which in an aircraft functions to transport the waste stream from an aircraft toilet or other receptacle to the separator. The inlet tube thus, e.g., receives a waste stream comprising air, waste water, waste solids, and other materials from the aircraft toilet when it is flushed. This stream, which is represented diagrammatically by arrow WS1, is drawn into vortex separator12by suction provided either by the pressure differential at high elevations or by the operation of a vacuum generator at low altitudes applied at exhaust tube18. The vacuum generator preferably will produce a vacuum of about 3-9 inches Hg. At an altitude of about 16,000 feet, the system will switch from the vacuum generator to the cabin-to-atmosphere differential by way of the operation of check valve20to draw the waste stream into the separator. Finally, waste tank10includes a drain tube28at its bottom which will be connected to a waste removal port on the outside of the aircraft (not shown) through which waste collected in tank10will be drained during servicing of the aircraft.

As can be seen in the cut-away view ofFIG. 2which illustrates the internal structure of vortex separator12, the vortex separator includes an annular channel30in communication with inlet tube26formed into inner wall31of annular wall32of cylindrical housing14. It should be noted that the lower portion33of wall32extends into waste tank10with an outer annular lip35encircling the outer surface32A of the wall resting on a corresponding lip29of the tank so that the two may be removably clamped together (FIG. 1).

Thus, the vacuum applied at exhaust tube18is transmitted across the vortex separator to draw stream WS1into inlet tube26under high velocity. This high velocity stream is directed by inlet tube26into annular channel30which defines a first vortex flow path V1. As stream WS1moves in flow path V1a lighter airstream WS2migrates to the center of the separator cylindrical housing as most of the heavier solids and liquids move to the outside and fall out of stream WS1to the bottom of waste tank10.

The next important feature is an inverted truncated conical cavity34between an inner inverted cone36nested within an outer inverted cone38. Thus, the inner surface37of outer inverted cone38and the outer surface39of inner inverted cone36define inverted conical cavity34which is generally centered within housing14. Nested cones36and38are mounted below exhaust cap16, and are interconnected by a support structure40at the entrance to the conical cavity having vanes41extending radially outwardly from a hub43. The vanes are angled about their radial axes to form angled slots for inducing rotary motion in the airstream passing through the slots into conical cavity34to the second vortex path. Support structure40maintains the spacing between the cones without obstructing passage of material from the conical cavity in the space between the vanes. A funnel47is located below the nested cones. The funnel47positioned below the nested cones has a maximum radius less than the minimum radius of the outer inverted cone38for diverting the airstream WS2into the conical cavity34. The outer surface51of the funnel helps divert the lighter airstream WS2into inverted conical cavity34.

The nested truncated cones also define an annular opening45(FIG. 3) along their bottom edge into which airstream WS2is drawn, and from which heavier material will fall from conical cavity34past vanes41as will be explained in more detail below. Finally, the top edge of the nested cones is generally closed off by an annular top closure44which has a port46through which air may be transported from the conical cavity. A second like port is located 180° opposite port46but is hidden in the Figures.

Airstream WS2therefore is drawn up through the conical cavity by the suction force applied at exhaust tube18. Due to the nesting of the cones this stream can only travel between the walls of the cones. As a result of the fan-like strut structure, the conical shape of cavity34, and the high velocity, stream WS2will move through cavity34in a second vortex flow path V2which, as can be seen inFIG. 2, is isolated from vortex flow path V1. Vortex flow path V2again produces a centrifugal force that causes remaining heavier materials (particulate waste & liquid) to move to the outside where it will fall down through conical cavity34and annular opening45at the bottom of the nested cones into tank10. Meanwhile, the remaining lighter airstream WS3will pass upwardly through port46in top closure44to be drawn down into an inner inverted truncated conical chamber50defined by the inner surface48of cone36.

A waste check valve60is located at the bottom54of chamber50. This check valve comprises an inverted umbrella-shaped rubber membrane52supported below strut structure56by a central upwardly projecting locking member58that is mounted in a hole at the center of the strut structure. The check valve allows solids and liquids to fall from truncated conical chamber50to funnel47and out bottom funnel opening49to waste tank10but does not allow contaminated air from below the check valve to enter the chamber, as explained below. As is illustrated diagrammatically inFIG. 3, chamber50also contains a first filter material62which helps coalesce remaining moisture as the stream moves through truncated conical chamber50to leave a further portion of waste stream WS3with at most minimal amounts of moisture as it exits chamber50.

Stream WS3next enters an exhaust member63having an annular shelf64resting at the top of cone36and a tubular portion66centered above chamber50, with tubular portion66extending partially into the chamber and the annular flange supporting the exhaust member across the top of the nested cones. Shelf64rests below exhaust cap16of the vortex separator. Preferably, a demister filter material72is disposed across the top opening of tubular portion66to trap moisture and help demist entrained moisture moving past the mesh through cap16and out exhaust tube18. Both filter materials62and72preferably are in the form of a dense knitted mesh of metal, nylon or propylene. Thus, filter material72is positioned to remove most if not all of the moisture remaining in stream WS3, so that the airstream moving out through exhaust tube18to the outside atmosphere will be free of moisture.

The device will operate when the flush cycle of the airplane toilet is initiated. When this happens, waste stream WS1will be drawn from the toilet through inlet tube26into annular channel30and first vortex flow path V1in which the resulting centrifugal force causes the heavier components of the waste mixture to move to the outside and fall into waste tank10, as discussed earlier.

Meanwhile, a remaining rapidly moving vortex comprising stream WS2enters inverted truncated conical cavity34through the angled slots between vanes41and the remaining solids and water are further separated by the centrifugal force produced in a second vortex flow path V2causing additional solids and water to fall into waste tank10, leaving remaining waste stream WS3as an airstream substantially free of solids and with a substantially reduced level of liquids. WS3is then drawn from the center of the separator cylindrical housing into conical cavity34through port46along annular channel55of closure44and into inverted conical chamber where it passes up through first filter material62which helps coalesce entrained liquid in stream WS3so that it accumulates and falls to the bottom of the inverted conical chamber. As a result, when the vacuum in the system is no longer applied, check valve60will open under the weight of the accumulated material at the bottom of chamber50so that this waste material can move past the check valve into funnel47from which it will fall through bottom funnel opening49to the bottom of tank10joining the earlier separated waste.

It should be noted that vortices V1and V2do not intersect. This is an important feature of the invention since intermingling of crossing high velocity waste streams moving through the vortices would cause additional particulate moisture and solids to be formed significantly reducing the effectiveness of the separator.

Finally, the remaining stream WS3passes from exhaust chamber tubular portion66of exhaust member63through demister filter72where it passes through exhaust cap16into exhaust tube18to either the vacuum generator or the atmosphere if the aircraft is operating at a high altitude. Typically, the above process, from the application of the vacuum through the completion of the separation process will take about 1 to 4 seconds.