COOKING EXHAUST FILTER SYSTEM

Abstract

A cooking exhaust filter system 10 includes a collection duct structure 12 positionable over a cooking location CL. The transfer duct 14 receives the cooking exhaust from the collection duct structure 12 and changes the direction of flow of the cooking exhaust to direct such exhaust against an abutment. From such abutment, the cooking exhaust flows through the baffle assembly 18 which forces the cooking exhaust to flow in a helical path thereby forcing the particles in the cooking exhaust to the outside of the flow stream and against the walls of the baffle assembly to adhere thereto. The exhaust gas then flows through an outlet duct system into the atmosphere.

Description

BACKGROUND

The exhaust from cooking and frying processes mainly consists of steam, water vapor, smoke, lipid, and other entrained particles. When such exhaust is released into the atmosphere without sufficient removal of the lipids and other entrained particles, some of the lipid particles drift and some coalesce or are captured by condensing water and fall back to earth. As a result, the surface directly surrounding the exhaust ducting from the cooking and frying operations can be damaged by oil puddling when the water evaporates. Removing oil particles, especially larger oil particles, prior to releasing the exhaust gas to atmosphere improves the environmental condition and prevents structural deterioration.

Moreover, the emissions from food processing operations are subject to environmental regulations. One source of such emissions is the exhaust from cooking and frying processes. Entrained particulates which are not removed from the cooking or frying process exhaust are subject to air quality regulations. As such, efforts have been made to remove particulates, including lipid particles, from cooking and frying exhaust. However, to date, such efforts typically have required either expensive equipment and/or the frequent cleaning of the filter system or replacement of filters or other components thereby causing significant costs in either personnel or replacement parts.

Past efforts to separate particulate matter from the cooking or frying exhaust include the use of filters, whether alone or in conjunction with mist eliminators. Such filters typically are composed of a mesh or screens. Particulates from the exhaust are trapped between the wires of the mesh/screen filter and begin to fill the open area within the filter, thereby requiring the filter to either be cleaned or replaced to remain functional.

Failure to clean or replace a filter can result in less exhaust being removed and eventually complete clogging of the filter. Also, if the exhaust fan pulls too much exhaust through the filters, particulates and oil droplets which have been trapped can be forced through the filter and entrained back into the air stream and thus into the environment.

Other efforts to remove particulate matter from cooking and frying exhaust include water scrubbers, which require a constant spraying water source. In turn, the water must be recycled or reused for the process to be economically and environmentally acceptable. This adds to the cost of the water scrubber.

Rotocyclones also have been utilized in an effort to remove particulate matter from cooking and frying exhaust. However, such cyclones are expensive and require electricity for operation and often also require water.

In addition, thermal oxidizers have been used to remove particulate matter from cooking or frying exhaust. Such thermal oxidizers have high initial cost and require a continuous fuel source to operate the oxidizers. Thus, there is a need for an inexpensive, low maintenance but effective system for removing particulate matter from cooking and frying exhaust.

SUMMARY

A cooking exhaust filter system separates entrained particles from cooking exhaust gas. The system includes a collection duct structure positionable at a cooking location, with the duct structure having one or more inlet openings to receive cooking exhaust from the cooking location. The filter system also includes a transfer duct in fluid flow communication with the collection duct structure and configured to change the direction of flow of the cooking exhaust received from the collection duct, thereby to induce exhaust gas particles to fall out of suspension from the cooking exhaust gas. The filter system also includes a baffle assembly in fluid flow communication with the transfer duct. The baffle assembly includes a baffle structure configured to receive the cooking exhaust gas from the transfer duct and cause such cooking exhaust gas to flow in a non-linear path thereby to induce particulates to shift or otherwise fall out of the flow stream of the cooking exhaust thereby to separate from the cooking exhaust gas.

In a further aspect of the present disclosure, the collection duct structure includes an elongated duct positionable to extend over the cooking location. One or more inlet openings are provided in the collection duct structure through which the cooking exhaust gas flows into the duct structure.

In a further aspect of the present disclosure, the transfer duct includes an outlet at a location remote from the collection duct structure, and an abutment is provided adjacent the outlet of the transfer duct against which the cooking exhaust flowing through the transfer duct impinges, thereby to induce the particulates in the cooking exhaust to fall out of suspension from the cooking exhaust gas.

In accordance with a further aspect of the present invention, the transfer duct includes a section extending in the downward direction and including an outlet at the bottom of the transfer duct. The impingement surface is spaced below the outlet of the transfer duct against which the cooking exhaust exiting the transfer impinges.

In accordance with a further aspect of the present disclosure, the baffle assembly surrounds at least a portion of the downwardly directed transfer duct section. In this regard, the baffle assembly includes walls that direct the exhaust gas to flow in a path that is at least partially in a shape selected from curved, arcuate, circular, spiral, helical, serpentine, and toroidal.

In a further aspect of the present invention, a baffle assembly is provided for a cooking exhaust filter system for separating entrained particulates from a cooking exhaust gas stream. The baffle assembly includes walls which direct the cooking exhaust gas stream to flow along a path that is at least partially non-linear and configured to force particles entrained in the cooking exhaust gas stream to the outside of the cooking exhaust gas stream so as to coalesce on surfaces of the baffle walls and thereby fall out of suspension from the cooking exhaust gas stream.

In accordance with a further aspect of the present disclosure, the non-linear path of the cooking exhaust stream through the baffle assembly is selected from the group consisting of arcuate, curved, circular, spiral, helical, serpentine, and toroidal.

In accordance with a further aspect of the present disclosure, the baffle assembly is in fluid flow communication with a transfer duct, which in turn is in fluid flow communication with the source of cooking exhaust gas.

The transfer duct ends at an outlet in fluid flow communication with the baffle assembly. Also, the outlet of the transfer duct is spaced from an abutment against which the cooking exhaust gas stream flowing through the transfer duct impinges.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is an elevational view of the present disclosure with portions shown in cross section and portions shown schematically;

FIG. 2 is an enlarged cross-sectional view of FIG. 1;

FIG. 3 is an isometric view of FIG. 1; and

FIG. 4 is a schematic view of another embodiment of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings, where like numerals reference like elements, is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that many embodiments of the present disclosure may be practiced without some or all of the specific details. In some instances, well-known process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein.

A cooking exhaust filter system 10 includes in basic form a collection duct structure 12 which is positionable over a cooking location CL. The system 10 also includes a transfer duct 14 in fluid flow communication with the collection duct structure 12 to change the direction of flow of the cooking exhaust and direct the cooking exhaust against an abutment 16. From such abutment, the cooking exhaust flows through a baffle assembly 18 which forces the cooking exhaust to flow in a helical path thereby forcing the particles in the exhaust gas to the outside and against the walls of the baffle assembly to adhere thereto. The exhaust gas then flows through an outlet duct system 20 to the atmosphere.

Next, describing the cooking exhaust filter system 10 in greater detail, the collection duct structure 12, as shown in FIGS. 1 and 2, is in the form of an elongated duct 22 extending laterally over a cooking location CL. The duct 22 may be supported by a frame structure 24 for supporting the duct 22 stationary relative to the cooking location CL.

An inlet opening in the form of a slot 23 is formed along the bottom of the duct 22. Cooking exhaust is drawn through the slot 23 and into the duct 22 for travel through system 10. The curtain of cooking exhaust entering the duct 22 through slot 23 hits or impacts against the upper inside wall of the duct opposite the slot and separates and swirls to the left and right as schematically depicted by arrows 26 and 28 in FIG. 2, and then moves along the duct toward the transfer duct 14. The sudden change in direction of the cooking exhaust hitting the upper inside surface of the duct 22 forces larger entrained particulates out of suspension causing the particulates to run or drain down the inside surface of the duct 22 and then downwardly out through the inlet slot 23 and back into the cooking location CL. This is the first location in which particulates are separated from the cooking exhaust by the present filter system 10.

The duct 22 includes an inlet end opening 29 to allow makeup air to enter the duct 22. It is desirable to maintain a high exhaust velocity of the cooking exhaust passing through the filter system 10. It is not desirable to pull all of the flow through the system 10 from the cooking location. Rather, it is desirable to maintain a steam blanket over the hot oil at the cooking location which helps prevent degradation of the cooking oil. If the steam blanket is removed by the exhaust system 10, then the cooking oil will be detrimentally degraded. Thus, the opening 24 at the end of the duct 22 allows ambient air to be drawn into the system 10 to maintain a high exhaust velocity while retaining the steam blanket over the cooking location. Although the inlet end opening 29 is shown as located in the end of the duct 22, it is to be understood that the inlet opening for the makeup air can be at other locations along the duct 22.

The exhaust gas that is collected in the collection duct structure 12 flows along the duct 22 and into the transfer duct 14. The transfer duct 14 includes an upper elbow 30 that directs the cooking exhaust downwardly through an upright or vertical section 32 as represented by arrow 34. The upright section 32 terminates at a bottom outlet 36. The exhaust gas exiting the transfer duct 14 at outlet 36 impinges against an abutment 16 in the form of the bottom wall of baffle assembly 18. When the cooking exhaust changes direction within elbow 30, such change in direction causes entrained particles to fall out of suspension in the cooking exhaust and flow down the sidewalls of the transfer duct upright section 32 out the outlet 36 to be collected in a collection container 40 disposed below baffle assembly 18. Also, the impingement of the cooking exhaust against the abutment 16 causes particulates in the cooking exhaust to fall out of suspension and drain downwardly into the collection container 40.

Referring particularly to FIG. 1, the lower portion of outlet duct system 20 is in the form of a baffle assembly 18 which is structured around the upright section 32 of the transfer duct 14. The baffle assembly 18 includes a series of auger-shaped partitions 44 that fill the annular space between the inside diameter of the circular baffle assembly 18 and the circular exterior of transfer duct upright section 32. The partitions 44 create a helical path through which the cooking exhaust must pass upwardly through the baffle assembly 18. The minimal open area within the spiral path created by the partitions 44 increases the flow velocity of the cooking exhaust, and the constant rotational forces acting on the cooking exhaust forces particulates, including smaller particulates, to the outside of the flow and against the inside wall of the baffle assembly. Such particles coalesce on the wall such that the velocity of the cooking exhaust is not able to maintain such particles in suspension. As such, the particles migrate to the bottom of the baffle assembly and into the collection canister 40.

The cooking exhaust, minus the particulates that have been separated from the exhaust gas, continue up the exhaust stack 50 of the outlet ducting system 20 past a damper plate 52 and eventually to the ambient A. An exhaust fan, not shown, is located downstream of the exhaust stack 50, to draw the exhaust and makeup air through system 10 to the ambient A.

The exhaust fan is sized and the dimensions and placement of the partitions 44 are designed for the quantity of exhaust desired to be passed through system 10. The exhaust fan at full power should not pull so much cooking exhaust so as to re-entrain particles that have separated from the exhaust gas. Also, it is desirable that the cooking exhaust passing through baffle assembly 18 flow at high enough speed to cause smaller particulates to coalesce on the inside walls of the baffle assembly.

As in FIGS. 1 and 3, brackets 60 extend laterally from baffle assembly 18 for mounting of the system 10 in place. Also referring to FIGS. 1 and 3, a fire or smoke detector 70 is located in the exhaust stack 50 to monitor the presence of a fire within the system 10. If a fire is detected, a fire suppression system will release CO₂ through a nozzle in the exhaust stack 50 (not shown) to suppress the fire. Also, if a fire occurs, the damper plate 52 can be closed.

Also, although not shown, one or more cleaning nozzles may be incorporated into exhaust stack 50 or other locations in the system 10 to spray detergent or degreaser and hot water into the exhaust stack 50 for cleaning the stack as well as the baffle assembly 18.

It will be appreciated that system 10 is quite straightforward in structure, requiring no water and no power source other than to power the exhaust fan 52. Further, no cleaning of the system 10 is required during the cooking or frying process.

It will be appreciated that the size of the particulates forced out of suspension from the cooking exhaust will be dependent on the velocity of the cooking exhaust through the system 10. The smallest particles, as discussed above, are removed from the cooking exhaust in the baffle assembly 18. In the baffle assembly 18, particles as small as 5 μm (0.005 mm) can be removed. It is estimated that a high percentage, i.e., up to 99%, of the particulates in the cooking exhaust can be removed via system 10.

FIG. 4 illustrates a further embodiment for the present disclosure wherein cooking exhaust filter system 10′ includes the cooking exhaust filter system 10 described above with additional components located downstream of the baffle assembly 18. Accordingly, those portions of the cooking exhaust filter system 10′ that are the same as cooking exhaust filter system 10 are identified with the same part numbers.

Cooking exhaust filter system 10′ may include a heat exchanger 70 positioned downstream of baffle assembly 18. The heat exchanger 70 serves to remove or recapture heat from the cooking exhaust stream flowing through exhaust stack 40. The extracted heat can be used for different purposes, for example, as part of a facilities heating system, to heat water, or for other purposes. Inlet and outlet lines 72 and 74 are provided for directing the medium to be heated into the heat exchanger 70 and removing the heated medium from the heat exchanger in a well-known manner.

The cooking exhaust filter system 10′ may also include a water mist system 80 which helps reduce the odor in the cooking exhaust stream. Such water mist systems are articles of commerce.

The cooking exhaust filter system 10′ further includes an exhaust fan 90 to draw the cooking exhaust and makeup air through the cooking exhaust filter system 10′. Such exhaust fan has been described above with respect to cooking exhaust filter system 10, and thus such description will not be repeated here.

It will be appreciated that cooking exhaust filter system 10′ may optionally include heat exchanger 70 and/or water mist system 80. Also, heat exchanger 70 and/or water mist system 80 may be positioned in orientations other than as shown in FIG. 4.

While an embodiment of the present disclosure has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the present invention. In this regard, filter system 10 or 10′, rather than utilize a transfer duct, such as transfer duct 14, can be configured so that the collection duct structure 12 communicates directly with the baffle assembly 18. Perhaps to compensate for the function of the elbow 30 of the transfer duct and/or abutment 16, the configuration of the baffle assembly may be adjusted, for example in size or length, to remove from the cooking exhaust stream the particulates that would otherwise have been removed by the transfer duct.

Further, it is to be appreciated that the baffle assembly, similar to baffle assembly 18, can be employed or installed as a unit to new or existing cooking exhaust systems for the purpose of moving entrained particulates from the cooking exhaust. In this regard, the baffle assembly 18 may have to be modified somewhat so as to be compatible for use in such new or existing cooking exhaust systems. The baffle assembly 18 may be designed to be compatible with a particular volumetric flow rate of the cooking exhaust as well as to be compatible with the space available for installation of the baffle assembly.

In addition, the orientations of the components of system 10 can be other than as illustrated and described. For example, the transfer duct 14 may be disposed other than in a downward vertical direction as shown. Also, the baffle assembly 18 may be other than in an upright vertical orientation as shown, for example, the baffle assembly may be in tilted, horizontal, or other orientation. Further, the baffle assembly 18 may be configured so that the arcuate travel path of the cooking exhaust stream may be other than helical. For instance, the travel path may be, at least in part, in a circular, in a spiral, in a serpentine, or in a toroidal shape, or other non-linear, arcuate, or curved shape, thereby to force particulates to the outside of the exhaust gas flow and against the wall of the baffle assembly 18.

In addition, rather than utilizing a singular slot or slit 23 as an entrance/inlet opening to duct 22, openings of other shapes may be employed in the duct 22. Also, rather than allowing the larger entrained particles that fall out of suspension within duct 22 to simply fall back into the cooking zone, a collection device can be utilized to collect such particulates, for either reuse or disposal. In addition, other than being located at the bottom of duct 27, the slot(s), slit(s), or other opening(s) can be positioned at the top or on the side(s) or at other locations, about the circumference of the duct, thereby the particles that fall out of suspension may be directed to a desired location rather than simply falling back into the cooking location (CL). Moreover, the duct 22 can be inclined so that the entrained particles exit the duct 22 at a specific location for falling back into the cooking zone or into a collection receptacle.

Claims

1. A cooking exhaust filter system for separating entrained particles from the cooking exhaust gas, comprising: (a) a collection duct structure positionable at a cooking location, said collection duct structure comprising one or more inlet openings in the collection duct structure to receive cooking exhaust from the cooking location;(b) a transfer duct in fluid flow communication with the collection duct structure and configured to change the direction of flow of the cooking exhaust received from the collection duct, thereby to induce the exhaust gas particulates to fall out of suspension from the cooking exhaust gas; and(c) a baffle assembly in fluid flow communication with the transfer duct, said baffle assembly comprising a baffle structure configured to receive the cooking exhaust gas from the transfer duct and cause such cooking exhaust gas to flow in a non-linear path to induce exhaust particulates to shift out of the flow stream of the cooking exhaust gas thereby to separate from the cooking exhaust gas.

2. The cooking exhaust filter system according to claim 1, wherein the collection duct structure comprises an elongated duct positionable to extend over the cooking location.

3. The cooking exhaust filter system according to claim 2, wherein the one or more inlet openings of the collection duct structure extend along at least one of the underside, sides, and top of the elongated collection duct.

4. The cooking exhaust filter system according to claim 3, wherein the one or more inlet openings of the exhaust duct structure comprises one or more slits in the elongated collection duct.

5. The cooking exhaust filter system of claim 1, wherein the collection duct structure is in fluid flow communication with a source of makeup air to mix with the cooking exhaust flowing through the collection duct structure.

6. The cooking exhaust filter system according to claim 1, wherein the transfer duct includes an outlet at a location remote from the collection duct structure, and further comprising an abutment adjacent the outlet of the transfer duct, against which the cooking exhaust flowing through the transfer duct impinges, thereby to induce the exhaust particulates to fall out of suspension from the cooking exhaust gas.

7. The cooking exhaust filter system according to claim 1, wherein the transfer duct comprising a section extending in the downward direction and including an outlet at the bottom end of the transfer duct.

8. The cooking exhaust filter system according to claim 7, further comprising an impingement surface spaced below the outlet of the transfer duct, against which the cooking exhaust exiting the transfer duct impinges, thereby to induce particulates to fall out of suspension from the cooking exhaust gas.

9. The cooking exhaust filter system according to claim 7, wherein the baffle assembly surrounds at least a portion of the downwardly directed transfer duct section.

10. The cooking exhaust filter system according to claim 9, wherein said baffle assembly comprising baffle walls that direct the exhaust gas to flow in a path that is at least partially in a shape selected from circular, spiral, helical, serpentine, and toroidal.

11. The cooking exhaust filter system according to claim 9, wherein the baffle assembly comprised baffle walls that force the exhaust gas to flow in a non-linear path to facilitate the exhaust particles to separate out of suspension from the cooking exhaust gas.

12. The cooking exhaust filter system according to claim 11, wherein the non-linear path of flow of the cooking exhaust gas is in the upward direction.

13. The cooking exhaust filter system according to claim 1, wherein the baffle assembly at least partially surrounds the transfer duct.

14. The cooking exhaust filter system according to claim 1, wherein the baffle assembly comprises baffles arranged to force the cooking exhaust gas to flow in an arcuate path to induce the particulates in the cooking exhaust gas to fall out of suspension.

15. The cooking exhaust filter system according to claim 14, wherein the arcuate path of flow of the exhaust gas through the baffle assembly extends around the transfer duct.

16. The cooking exhaust filter system according to claim 14, wherein said baffle assembly comprises baffles positioned to force the cooking exhaust gas to flow in a path that is at least partially in a shape selected from circular, spiral, helical, serpentine, or toroidal.

17. The cooking exhaust filter system according to claim 1, further comprising one or more of the following components located downstream of the baffle assembly: (a) a water mister to remove odors from the cooking exhaust;(b) a heat exchanger to remove heat from the cooking exhaust; and(c) a fan to draw the cooking exhaust through the cooking exhaust filter system.

18. A cooking exhaust filter system for separating entrained particulates from cooking exhaust gas, comprising: (a) an elongated collection duct disposable over a cooking location, said collection duct comprising one or more inlet openings extending along the duct to receive the cooking exhaust from the cooking location; and(b) a baffle assembly in fluid flow communication with the collection duct, said baffle assembly comprising baffle walls which direct the cooking exhaust to flow along a path that is at least partially arcuate in shape and calculated to force particles entrained in the cooking exhaust to the outside of the cooking exhaust flow to coalesce on the surfaces of the baffle walls and thereby fall out of suspension from the cooking exhaust gas.

19. The cooking exhaust filter system according to claim 18, wherein the path of travel of the cooking exhaust through the baffle assembly is selected from the group consisting of arcuate, circular, spiral, helical, serpentine, and toroidal.

20. The cooking exhaust filter system according to claim 18, further comprising: (a) a transfer duct in fluid flow communication with the collection duct, said transfer duct having a section ending at an outlet in flow communication with the baffle assembly; and(b) an abutment spaced from the transfer duct outlet against which the cooking exhaust flowing through the transfer duct impinges.

21. A baffle assembly for a cooking exhaust filter system for separating entrained particulates from a cooking exhaust gas stream, said baffle assembly comprising: baffle walls which direct the cooking exhaust gas stream to flow along a path that is at least partially non-linear and configured to force particles entrained in the cooking exhaust gas stream to the outside of the cooking exhaust gas stream to coalesce on the surfaces of the baffle walls and thereby fall out of suspension from the cooking exhaust gas stream.

22. The baffle assembly according to claim 21, wherein the non-linear path of travel of the cooking exhaust stream through the baffle assembly is selected from the group consisting of arcuate, circular, spiral, helical, serpentine, and toroidal.

23. The baffle assembly according to claim 21, in fluid flow communication with the transfer duct, said transfer duct in fluid flow communication with a source of cooking exhaust gas, said transfer duct ending at an outlet in fluid flow communication with the baffle assembly, said transfer duct outlet spaced from an abutment against which the cooking exhaust gas stream flowing through the transfer duct impinges.