Method and apparatus for combined removal and in-situ biodegradation of grease material from a kitchen ventilator

Abstract: Grease biodegrading bacteria consortia are continuously mixed with a flow of air loaded with grease which is sent through an exhaust hood. Preferably, the exhaust hood includes a filter device which comprises a narrowing passageway which is located immediately below a baffle filter thereby regularly distributing the air flow through the entire area of the baffle filter. The hood is constructed to cause a swirling motion to the air flow.

Description: (a) Field of the Invention This invention relates to a method and an apparatus for combined removal and biodegradation of grease material from a kitchen ventilator. This invention relates specifically to an exhaust hood for separating and biodegrading grease particles. More particularly, the invention relates to a device which makes it possible to separate grease particles in air loaded with grease, produced by a cooking unit and to further biodegrade any grease that has not been drained away and that may remain on filters or deflectors used to separate it from air. (b) Description of Prior Art All kinds of devices are currently used to separate grease particles contained in air loaded with grease which is produced by a cooking unit. These devices include filters, baffles, deflectors, as well as combinations thereof. However, even though drain systems may be provided to remove excess grease from exhaust hoods and grease extractors, it remains that some grease remain therein and even some is cooked onto the filters, baffles, deflectors. US-A-4753218 discloses a cooking hood where the air is washed by a detergent liquid to remove grease before passing the filter. On the other hand, there is a known grease biodegrading bacteria consortia sold in liquid form under the trademark BIO-KUT® which may be sprayed manually against some parts of exhaust hoods in an effort to biodegrade as much as possible of the grease which remain attached to the hood. It is not easy to have access to all the parts of the hood where some grease may be found on the one hand. On the other hand, it is just about impossible to introduce the right amount of bacteria consortia into the hood to provide a satisfactory treatment. If not enough is added, the treatment is not suitable. If too much is added, the excess is costly and will remain free in ambient air which is not normally acceptable. It is therefore an object of the present invention to provide a system which automatically delivers an exact amount of grease biodegrading bacteria consortia to an exhaust hood so that any grease still remaining therein will be continuously biodegraded. SUMMARY OF INVENTION According to the present there is provided an exhaust hood for separating and biodegrading grease particles and for mounting above a cooking unit. A hood including an exhaust fan is provided to draw air loaded with grease produced by the cooking unit into the hood. Means is mounted in the hood to separate grease particles from air while allowing substantially clean air to be expelled through the exhaust fan. Baffle means is adapted to cause a flow of air loaded with grease to be deflected before entering the hood and hitting the separating means, wherein the hood comprises a supply of grease biodegrading bacteria consortia. An injection device is mounted for feeding the bacteria consortia into the flow of air loaded with grease. A duct connects the supply of grease biodegrading bacteria consortia to the injection device, and there is provided a control means effective to provide predetermined amounts of bacteria consortia to the injection device for feeding same into the flow of air. The separating means consists of a baffle filter. Preferably, the exhaust hood comprises means to prevent radiation originating from the cooking unit to cook grease particles against the baffle filter. In accordance with a preferred embodiment a wedge shaped member is mounted upwardly slanted in said hood. The baffle filter is disposed in the wedge shaped member to define a passageway for the air loaded with grease which decreases from an entrance thereof until it becomes substantially flush with the baffle filter. The injection device feeds the bacteria consortia at the passageway entrance. Preferably the wedge shaped member has an outer face defining the baffle. Wings are provided longitudinally on both sides of the outer face, the wings being formed with slides along edges thereof. The baffle filter is engaged by the slides and the outer face defines an arcuate angle with respect to the baffle filter. The wedge shaped member may be provided with at least one grease drain at a downstream end of the passageway, and a grease cup is provided to receive grease delivered through the drain. In accordance with yet another embodiment, the hood may comprise a plurality of wedge shaped members and baffle filters mounted side by side, each having its own bacteria consortia injection device. The injection devices are connected to a single supply of grease biodegrading bacteria consortia. The latter may consist of BI0-KUT®. In accordance with yet another embodiment, a path is provided through the hood and deflector means are provided therein to cause a swirling motion of the air loaded with grease along the path. The injection device is mounted to direct the bacteria consortia into the path either against or along the swirling air loaded with grease. BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by means of the following drawings but is not restricted thereto. In the drawings: FIG. 1 is a vertical cross-section view of the device taken along line 1-1 of Fig. 3; FIG. 2 is an exploded perspective view of a filter holder for the device illustrated in Fig. 1; FIG. 3 is a front view of a system according to the invention incorporating six filter assemblies mounted side by side; FIG. 4 is a vertical cross-section view of an alternative system according to the invention; and FIG. 5 is a vertical cross-section view of another alternative system. DESCRIPTION With reference to the drawings, more particularly Figs. 1 and 2, it will be seen that the exhaust hood 1 which has been illustrated comprises a rectangular enclosure made of four vertical walls 3 and one horizontal top wall 5, and an exhaust duct 7 to lead filtered air to the outside in the direction indicated by arrows 9. A filter assembly 11 which will be more specifically described hereinbelow is mounted upwardly slanted as shown inside hood 1 by means of lower support bracket 13 and upper support bracket 15. It will of course be understood by one skilled in the art that those brackets 13, 15 may take any shape that are convenient provided mounting of filter assembly 11 can be achieved substantially as shown. More particularly bracket 13 consists of an L-member which is mounted against the rear wall of the enclosure, and is terminated at its outer end by a small support finger 17. Of course, the mounting of L-shaped bracket 13 against the rear wall of the enclosure can be achieved in any way well known by those skilled in the art. With respect to support bracket 15, it consists of a rectangular trapezoidal member in which the perpendicular leg 19 is fixed against the horizontal face 5 of the hood while the other leg 21 which downwardly extends is used to support the upper end of filter 11. Turning now to the filter per se, reference will also be made to Fig. 2 of the drawings wherein it will be seen that it consists of a wedge shaped member 23 which has a rectangular outer face 25, the latter defining a baffle which forces the air loaded with grease to be deflected in the direction indicated by arrows 27 before arriving at entrance 29 of filter assembly 11. Wedge member 23 also comprises wings 31, 33 on both longitudinal sides of wedge member 23. As shown, these wings 31, 33 are triangular for more convenience. At the top edge of triangular wings 31, 33, there are provided rectangular slides 35, 37 which are shaped to engage baffle filter 39 as particularly shown in Fig. 2 of the drawings. Once wedge shaped member 23 and baffle filter 39 are assembled the filter assembly defines a passageway 30 for air loaded with grease which decreases from its entrance 29 until it becomes substantially flush with baffle filter 39 at the lower end thereof. This arrangement of a narrowing passageway allows the air and grease particles to be regularly distributed throughout the entire surface area of baffle filter 39 thereby providing a filter assembly which is much more efficient since the grease removal is not concentrated at a specific location of baffle filter 39. In addition to providing a swirling motion of the air loaded with grease particles towards entrance 29, the particular shape of the filter assembly 11, more specifically, outer face 25 of wedge member 23, enables to prevent the radiation originating from the cooking unit to literally cook some of the grease particles against baffle filter 39. In practice filter assembly 11, including wedge member 23 and baffle filter 39, is made of galvanized steel, stainless steel or aluminum. Of course, any other suitable material can be used within the scope and spirit of the present invention. Turning now to Fig. 3, in conjunction with Fig. 1, it will be seen that, for convenience, more than one filter assembly 11 may be provided, such as six in the case illustrated in Fig. 3. It will further be seen that the exhaust hood which has been illustrated is connected to a pressurized tank 41 containing grease biodegrading bacteria consortia, here BIO-KUT®. Pressurized tank 41 is connected through pressure regulator 42 and valve 43 on the one hand to a plastic or copper pipe 45 leading to a spray nozzle 47 which is constructed to inject the bacteria consortia into the flow 27 of air loaded with grease circulating in passageway 29 defined by wedge member 23 and baffle filter 39. Mounting of the spray nozzle 47 is achieved through support bracket 21 as shown in Fig. 1. The control for injecting a predetermined amount of bacteria consortia is made possible by the operation of the exhaust fan control station 51 which is calibrated to inject a predetermined amount of bacteria consortia from pressurized tank 41 just before stopping the exhaust fan completely. Any excess grease which has not reached baffle filter 39, or which has just flowed down towards the bottom of the triangular passageway 30 defined by outer face 25 and baffle filter 39, flows out through drain 55 into grease cup 57. Turning now to Figs. 4 and 5, the hood mainly includes a baffle 59 at the lower part thereof, and a plurality of deflectors 61 distributed along passageway 63 which leads to the exhaust duct 65. In Fig. 4, injection device (spray nozzle) 47 is mounted in the upper portion of the grease extractor and directs the bacteria consortia against the flow of air loaded with grease. Oppositely, with reference to Fig. 5, spray nozzle 47 is mounted in the lower part and directs the bacteria consortia along the flow of air loaded with grease. Operation of the exhaust hood is obvious to one skilled in the art. It is merely sufficient to preprogram the desired quantity of bacteria consortia to be introduced into the exhaust hood while the latter is in operation. Of course, modifications are possible without departing from the scope and spirit of the present invention as long as they are provided by the appended claims.

Claims: Exhaust hood (1) for separating and biodegrading grease particles and for mounting above a cooking unit, said hood (1) including an exhaust fan to draw air loaded with grease produced by said cooking unit into said hood (1), means (39) mounted in said hood (1) to separate grease particles from air while allowing substantially clean air to be expelled through said exhaust fan, and baffle means (23,25) adapted to cause a flow of air loaded with grease to be deflected before entering said hood (1) and hitting the separating means (39), wherein said hood (1) comprises a supply (41) of grease biodegrading bacteria consortia, an injection device (47) mounted for feeding said bacteria consortia into said flow of air loaded with grease, duct (45) connecting said supply (41) of grease biodegrading bacteria consortia to said injection device (47), and control means (51) effective to provide predetermined amounts of bacteria consortia to said injection device (47) for feeding same into said flow of air. Exhaust hood according to claim 1, wherein the separating means consists of a baffle filter (39). Exhaust hood device according to claim 2, which comprises a wedge shaped member (23) mounted upwardly slanted in said hood (1), said baffle filter (39) being disposed in said wedge shaped member (23) to define a passageway (30) for said air loaded with grease which decreases from an entrance thereof until it becomes substantially flush with said baffle filter (39), said injection device (47) feeding said bacteria consortia at said entrance. Exhaust hood according to claim 3, wherein said wedge shaped member (23) has an outer face (25) defining said baffle, wings (31,33) being provided longitudinally on both sides of said outer face, said wings being formed with slides along edges thereof, said baffle filter (39) being engaged by said slides, said outer face defining an acute angle with respect to said baffle filter (39). Exhaust hood according to claim 4, wherein said wedge shaped member (23) is provided with at least one grease drain (55) at a downstream end of said passageway (30), a grease cup (57) being provided to receive grease delivered through the drain (55). Exhaust hood according to claim 3, which comprises a plurality of wedge shaped members (23) and baffle filters (39) mounted side by side, each having its own bacteria consortia injection device (47), the injection devices (47) being connected to a single supply (41) of grease biodegrading bacteria consortia. Exhaust hood according to claim 1, which comprises a path through said hood (1) and deflector means provided therein to cause a swirling motion of said air loaded with grease along said path, said injection device (47) being mounted to direct said bacteria consortia into said path. Exhaust hood according to claim 7, wherein said injection device (47) is arranged to direct said bacteria consortia against said swirling air loaded with grease. Exhaust hood according to claim 7, wherein said injection device (47) is arranged to direct said bacteria consortia along said swirling air loaded with grease. Exhaust hood according to claim 2, which comprises means to prevent radiation originating from the cooking unit to cook grease particles against the baffle filter. Method for removing grease material from an exhaust hood which comprises providing a swirling motion to a flow of air loaded with grease particles produced by a cooking unit, and causing said swirling flow to move upwardly through said exhaust hood, and injecting grease biodegrading bacteria consortia into said flow to biodegrade grease that may accumulate in said hood. Method according to claim 12, which comprises providing a filter device including a baffle filter in said hood along said swirling flow, forming a decreasing passageway for said swirling flow below said baffle filter thereby regularly distributing said air loaded with grease throughout the entire area of said baffle filter.

Inventors: BOUDREAULT JEAN-PIERRE, COUILLARD DANIEL, TRUDEAU GUY L, BOUDREAULT, JEAN-PIERRE, COUILLARD, DANIEL, TRUDEAU, GUY L.
Applicants: CADEXAIR
Application year: 1998
Main classification: F24C15
IPC codes: F24C15, B08B9, B01D45