GB2298376A

GB2298376A - Improvements relating to extraction apparatus

Info

Publication number: GB2298376A
Application number: GB9503956A
Authority: GB
Inventors: James Fitzpatrick
Original assignee: MACDET HYGIENE SERVICES Ltd
Current assignee: MACDET HYGIENE SERVICES Ltd
Priority date: 1995-02-28
Filing date: 1995-02-28
Publication date: 1996-09-04
Also published as: GB9503956D0

Abstract

The present invention relates to extraction apparatus (50) used to remove heat and fumes (10) from a kitchen environment. Accordingly, there is provided an extraction apparatus (50) providing means for the entrapment of vaporised products comprising filter means (40') traversing an extraction path of said vaporised products, wherein said filter means are cooled by cooling means (55). The cooling means (55) may incorporate a vapor compression cycle, an absorption cycle or apparatus exhibiting, for example, the Peltier effect. The extraction apparatus (50) may further be used to recover waste heat.

Description

Improvements Relating to Extraction Apparatus This invention relates to extraction apparatus and in particular, though not exclusively, to extraction apparatus used to remove heat and fumes from a kitchen environment.

In almost all commercial kitchens there is provided an extraction system, usually directly above the cooking apparatus, designed to remove the heat and fumes produced by cooking processes. The extraction system usually comprises a fume catching canopy above the cooking apparatus, duct work associated with the canopy providing a path between the source of the heat and fumes and a suitable outlet vent, a fan within the ducting to provide a stream of air from the source to the outlet, and one or more filter elements traversing the duct work between the canopy and the fan.

Some forms of cooking, e.g. the preparation of fast food using frying oil and the grilling of beef burgers, produce large quantities of vaporised grease which is also drawn into the extraction system. It is intended that the vaporised grease should condense upon the filter elements, which are usually manufactured from teflon or stainless steel mesh, and hence drain into a gutter running around the periphery of the canopy. The gutter can then be drained periodically and the grease disposed of in an appropriate manner. The filters are in most cases easily detachable, and it is normal procedure in most kitchens for the staff to remove them periodically and clean them by soaking them in a suitable chemical solution.

Most of the systems currently in use work satisfactorily, but the following disadvantages have been identified: 1. Significant amounts of vaporised grease pass through the filters and condense on the inside of the ducting, the fan or the outlet vent. This constitutes a fire hazard which must be removed manually at regular intervals by specialised cleaning equipment.

2. Most of the heat produced by the cooking processes is wasted as it is vented to atmosphere along with the fumes.

It is an object of the present invention to obviate or mitigate at least some of the aforementioned disadvantages.

According to a first aspect of the present invention there is provided an extraction apparatus providing means for the entrapment of vaporised products comprising filter means traversing an extraction path of said vaporised products, wherein said filter means are cooled by cooling means.

Said extraction apparatus may form part of an extraction system located in the vicinity of cooking apparatus.

The cooking apparatus may be provided within a commercial catering establishment.

The vaporised products may comprise oils, fats and grease liberated by the preparation of food using heated cooking apparatus.

Preferably said cooking apparatus may include gas or electrically powered grills, hobs, ovens, steamers, hot plates and/or fat fryers.

The filter means may be constructed from any appropriate material including teflon or stainless steel mesh or aluminium mesh.

The cooling means may take the form of apparatus employing a vapour compression cycle, an absorption cycle or apparatus exhibiting electromechanical phenomena such as the Peltier effect.

An evaporator component of the cooling means may comprise one or more filters incorporating a matrix of tubes through which a working fluid may flow, or one or more filters placed in intimate thermal contact with a frame through which the heat pump working fluid may flow, or any other suitable arrangement.

The cooling means may be fully or at least partially contained within the extraction apparatus.

According to second aspect of the present invention there is provided an apparatus for recovering waste heat generated by a process comprising a heat pump circuit, an evaporator component of which is placed in an extraction path of said waste heat.

Preferably the waste heat is generated by a cooking process, the apparatus being arranged in association with the extraction system for removing heat/fumes produced by the cooking process.

The evaporator component may comprise one or more filters incorporating a matrix of tubes through which a working fluid may flow, or one or more filters placed in intimate thermal contact with a frame through which the heat pump working fluid may flow, or any other suitable arrangement.

The working fluid may include any refrigerant suitable for the temperatures likely to be experienced by the apparatus.

The heat pump circuit may be fully or at least partially contained within the extraction apparatus.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1. Shows a schematic representation of an existing extraction system, and Figure 2. Shows a schematic representation of extraction apparatus in accordance with an embodiment of the present invention, and Figure 3. Depicts extraction apparatus incorporating an alternative embodiment of the present invention.

Referring firstly to Figure 1. there is shown an arrangement of a typical extraction system 5. Heat and fumes 10 are generated by cooking apparatus 15, e.g. a deep fat fryer.

The apparatus 15 is surmounted by a canopy 20 designed to funnel the heat and fumes 10 towards ducting 25, so as to seek to prevent the heat and fumes 10 from escaping into the rest of the kitchen area.

Once within the canopy 20 the heat and fumes 10 are caused to enter the ducting 25 by the action of a fan 30 provided at the end of the ducting 25 remote from the canopy 20. The fan 30 is used to provide a through flow of air from the canopy 20 to the outlet vent 35.

Vaporised fats and oils present within the fumes 10 partly prevented from passing through the ducting 25 and hence to the outlet vent 35 by the presence of filters 40 within the canopy 20. The filters 40 are usually manufactured from teflon or a stainless steel mesh or aluminium mesh and act to cause some of the vaporised oils and fats to condense upon their surfaces. The condensed oils and fats then drain into canopy gutter 45 which runs around the periphery of the canopy 20. The oils and fats can then be collected and disposed of in an appropriate manner.

Figure 2. depicts extraction apparatus 50 in accordance with the present invention, wherein the filter 40' acts as the evaporator component of heat pump circuit 55. The heat pump circuit 55 comprises the filter/evaporator 40', a compressor 60, a condenser/heat exchanger 65, pipework 70 connecting the components to each other and a suitable working fluid (not shown). As described substantially hereinbefore heat, fumes and vaporised grease are drawn from within the canopy 20' through the filter/ evaporator 40' towards the ducting 25' by the fan (not shown). However the presence of the heat pump circuit 55 causes elements of the filter/evaporator 40' to be cooled to a temperature below that of the dew point for the vaporised grease. It will be understood that the term dew point refers to the temperature at which a vapour begins to condense.

The filter/evaporator 40' may be cooled either by the provision of a matrix of tubes in the filter/evaporator 40' or by the filter/evaporator 40' being in intimate contact with a frame through which the working fluid flows. The filter/evaporator 40' thus cooled is more efficient at condensing the vaporised grease which drains into the canopy gutter.

The action of condensing the vaporised grease, along with exposure to the waste heat of the cooking processes, causes the working fluid to evaporate. The said fluid can then transport the heat energy absorbed in a low pressure portion of the circuit 55 to the condenser/heat exchanger 65 in a high pressure portion. The heat energy thus emitted can be used to supplement the heat budget of the building in which the extraction system is installed.

Referring now to Figure 3. there is shown an alternative embodiment of the present invention 75 wherein the heat pump circuit 55' is fully contained within the ducting 25''. As before the filter/evaporator 40'' is cooled below the dew point temperature of the vaporised grease. The heat energy absorbed by the filter/evaporator 40'' is discharged by the condenser/heat exchanger 65', within the ducting 25'', with the assistance of the air flow generated by the fan 30'.

This embodiment does not permit the recovery of waste heat but it is considerably more compact than the embodiment disclosed in Figure 2.

It should be understood that the embodiments of the invention described hereinbefore are given by way of example only, and are not meant to limit its scope in any way. It should also be appreciated that the invention herein disclosed provides a simple and relatively easily constructed solution to long-standing problems experienced in this art.

Claims

1. An extraction apparatus providing means for entrapment of vaporised products comprising filter means traversing an extraction path of said vaporised products, wherein said filter means are cooled by cooling means.

2. An extraction apparatus as claimed in claim 1 forming part of an extraction system located in the vicinity of cooking apparatus.

3. An extraction apparatus as claimed in claim 1 or claim 2, wherein the filter means are constructed from any appropriate material including teflon or stainless steel mesh or aluminium mesh.

4. An extraction apparatus as claimed in any preceding claim, wherein the cooling means takes the form of apparatus employing a vapour compression cycle, an absorption cycle or apparatus exhibiting electromechanical phenomena such as the Peltier effect.

5. An extraction apparatus as claimed in any preceding claim, wherein an evaporator component of the cooling means comprises one or more filters incorporating a matrix of tubes through which a working fluid flows, or one or more filters placed in intimate thermal contact with a frame through which the heat pump working fluid may flow, or any other suitable arrangement.

6. An extraction apparatus as claimed in any preceding claim, wherein the cooling means is either fully or at least partially contained within the extraction apparatus.

7. An extraction apparatus as claimed in any preceding claim, wherein the cooking apparatus is provided within a commercial catering establishment and comprises gas or electrically powered grills, hobs, ovens, steamers, hot plates and/or fat fryers.

8. An extraction apparatus as claimed in any preceding claim, wherein the vaporised products comprise oils, fats and grease liberated by the preparation of food using heated cooking apparatus.

9. An apparatus for recovering waste heat generated by a process comprising a heat pump circuit, an evaporator component of which is placed in an extraction path of said waste heat.

10. An apparatus as claimed in claim 9, wherein the waste heat is generated by a cooking process, the apparatus being arranged in association with the extraction system for removing heat/fumes produced by the cooking process.

11. An apparatus as claimed in claim 9 or claim 10, wherein the evaporator component comprises one or more filters incorporating a matrix of tubes through which a working fluid flows, or one or more filters placed in intimate thermal contact with a frame through which the heat pump working fluid flows, or any other suitable arrangement.

12. An apparatus as claimed in claim 11, wherein the working fluid comprises any refrigerant suitable for the temperatures likely to be experienced by the apparatus.

13. An apparatus as claimed in claim 10, wherein the heat pump circuit is either fully or at least partially contained within the extraction system.

14. An extraction apparatus as hereinbefore described with reference to Figs 2 or 3.

15. An apparatus for recovering waste heat as hereinbefore described with reference to Figs 2 or 3.