High velocity and high dilution exhaust system

Abstract

A nozzle for an exhaust fan that has a primary, central aperture for exhaust. Arranged around the periphery of the central aperture is a plurality of side apertures. The nozzle fits over the fan outlet. A stack may extend upwardly from the central aperture. Exhaust exiting the side apertures induces a flow of ambient air, especially when a windband encircles the nozzle. The ambient air increases the volume of exhaust exiting the windband.

Description

BACKGROUND OF THE INVENTION

Industrial and institutional processes often produce fumes required to be exhausted and removed from the immediate area of the building. Exhaust systems include ducts, hoods, and exhaust fans to extract the contaminated fumes. Specific applications, such as laboratory or processing exhaust, are hazardous and must be exhausted to insure the safety of those working in close proximity to the source of the exhausted effluent. Safety concerns extend not only to those in the immediate area where the fumes are generated, but also to others located in the building as well as occupants in surrounding buildings.

Improperly designed exhaust systems that ineffectively discharge high concentrations of effluent can result in entrainment of the hazardous or noxious exhaust into the building air conditioning system, contaminating the fresh air brought into the building.

Problems are encountered in particular where the contaminated exhaust is heavier than air, is corrosive or has a foul odor. In these instances it is necessary to displace the exhaust at a height allowing dispersement to negate the possibility of concentration of the effluent at ground level.

In applications where exhaust needs to be displaced high above ground level, exhaust fans and stacks are typically placed on roof tops. To insure the displacement at levels high above ground level, it is known to use long exhaust stacks having an exit orifice at the desired height. Often, the stacks are so long as to be unstable and require the use of guy wires or other braces to ensure their stability, especially if high wind conditions are ever expected.

There is a need in the prior art for an improvement in the design of a fan and stack to deliver fumes to a maximum possible height, before dispersion of the exhaust within the environment occurs to allow complete dissipation and prevent concentration and contamination of the buildings at lower levels.

It is an object of the invention to provide an exhaust fan having a high plume height.

It is another object of the invention to have an exhaust fan and nozzle having a compact configuration.

It is yet another object of the invention to provide a exhaust fan with a nozzle requiring low energy but having a high exhaust velocity.

It is another object of the invention to provide an exhaust fan and a nozzle allowing dispersement at a height preventing exhaust from reentering a building through an air conditioning system or other roof mounted equipment.

It is still another object of the invention to allow dispersement of exhaust eliminating costly corrosion caused by exhaust vapors.

It is another objective of the invention to provide an exhaust for diluting the exhaust before exiting the exhaust stack.

These and other objects of the invention will become apparent to one of ordinary skill in the art after reviewing disclosure of the invention.

SUMMARY OF THE INVENTION

A nozzle for an exhaust fan that has a primary, central aperture for exhaust. Arranged around the periphery of the central aperture is a plurality of side apertures. The nozzle fits over the fan outlet. A stack may extend upwardly from the central aperture. Exhaust exiting the side apertures induces flow of ambient air, especially when a windband encircles the nozzle. The ambient air increases the volume of exhaust exiting the windband.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the nozzle;

FIG. 2 is a perspective view of the nozzle with a tapered stack;

FIG. 3 is a view of the exhaust stack used with an exhaust fan;

FIG. 4 is a view of the exhaust stack used with an exhaust fan with the windband shown in cross section; and

FIG. 5 is a cross-sectional view of the exhaust stack with sound insulation.

DETAILED DESCRIPTION OF THE INVENTION

The nozzle 10 depicted in FIG. 1 has a central aperture 12 formed by an upstanding wall 14. A lip 15 may be formed in the wall, as will be more fully explained later. Extending outwardly from the upstanding wall 14 is a peripheral flange 16. A plurality of side apertures 18 are formed in the peripheral flange 16. Any number of side nozzles may be used and they may be any shape, such as the four depicted nozzles having an arcuate shape.

FIG. 2 shows the nozzle fitted with a tapered stack 20. The decreasing diameter of the stack increases the velocity of the exhaust traveling through the stack. The stack 20 may be attached to the nozzle 10 in any conventional manner, such as being unitarily formed or joined by welding. In the illustrated embodiment, the bottom edge of the tapered stack 20 fits over the top of the peripheral wall 14 and rests upon the lip 15.

FIG. 3 shows the nozzle and tapered stack 20 fitted within an exhaust stack 40 and connected to an exhaust fan 30. The exhaust fan 30 is a direct drive inline centrifugal fan, but the nozzle and tapered stack may be used with any type of fan, including, but not limited to, a direct drive centrifugal fan, a belt drive inline centrifugal fan, or a belt drive centrifugal fan. As seen in FIG. 3, the tapered stack 20 and exhaust stack 40 are concentric. The flange 16 fits over the outlet of the fan. A series of apertures 42 formed in the bottom of the exhaust stack 40 allow for ambient air to be pulled up into the exhaust stack 40.

The nozzle and stack are seen on a direct drive centrifugal fan of FIG. 4. Depicted in this view is the nozzle 10 over the outlet to cause flow through the stack 20 and between the stack and windband 40. Ambient air flow is induced about the tapered stack 20, mixing with the exhaust exiting the side nozzles 18. Upon exiting the windband 40, the flow of exhaust exiting the tapered stack 20 and side apertures 18 is increased by the ambient air.

The exhaust stack 40 may be provided with sound insulation 50 as seen in FIG. 5. The sound insulation covers the top portion and outwardly extending flange, but does not block the apertures 42, allowing ambient air to flow up into the exhaust stack.

While the invention has been described with reference to preferred embodiment, various variations and modifications would be apparent to one of ordinary skill in the art. The invention encompasses such variations and modifications.

Claims

1. An exhaust nozzle comprising

a central aperture,

a peripheral flange extending from said central aperture, and

a plurality of side apertures formed in the peripheral flange.

2. The nozzle of claim 1, wherein

the peripheral flange has four side apertures.

3. The nozzle of claim 1, wherein

the side apertures are arcuate.

4. The nozzle of claim 1, further comprising an upstanding wall around the central aperture.

5. The nozzle of claim 1, further comprising

a lip formed in the upstanding wall, and

a stack extending upward from said upstanding wall, the bottom of the stack resting upon the lip.

6. The nozzle of claim 5, wherein the stack is tapered.

7. The nozzle of claim 1, further comprising a stack extending from the central aperture.

8. The nozzle of claim 7, wherein the stack is tapered.

9. An exhaust system comprising

a fan having an outlet,

a nozzle over said outlet,

an exhaust stack extending upwardly from said fan,

the nozzle comprising a central aperture, a peripheral flange extending from said central aperture, and a plurality of side apertures formed in the peripheral flange.

10. The exhaust system of claim 9, wherein

the peripheral flange has four side apertures.

11. The exhaust system of claim 9, wherein

the side apertures are arcuate.

12. The exhaust system of claim 9, further comprising an upstanding wall around the central aperture.

13. The exhaust system of claim 9, further comprising

a lip formed in the upstanding wall, and

a stack extending upward from said upstanding wall, the bottom of the stack resting upon the lip.

14. The exhaust system of claim 13, wherein the stack is tapered.

15. The exhaust system of claim 9, further comprising a stack extending from the central aperture.

16. The exhaust system of claim 15, wherein the stack is tapered.

17. The exhaust system of claim 9, wherein said exhaust stack has apertures located below the fan outlet, whereby ambient air entering the apertures flows through said side apertures.