Impingement Freezer
The present invention relates to an impingement freezer (1) comprising an outer housing (2) having side walls (3), ceiling (4) and floor (5), where the outer housing (2) comprises gas condition means (6), preferably for cooling gas and encloses a high-pressure chamber (7) formed by one or more ventilators (8) for circulating the gas, side panels (9) and a perforated plate (10), where the high-pressure chamber (7) is positioned so that the perforated plate (10) is facing a conveyor belt (11) for transporting products allowing the gas to be impinged through the perforated plate (10) onto the conveyor belt (11), which is arranged in a zone (19) between the perforated plate (10) and a plate member (12), and where the side walls (3) and the side panels (9) provides a return access channel (18) for the circulated gas, and the zone (19) is provided with at least one open side (20), which is open towards the return access channel (18).
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The present invention relates to an impingement freezer comprising an outer housing having side walls, ceiling and floor, where the outer housing comprises gas condition means, preferably for cooling gas and encloses a high-pressure chamber formed by one or more ventilators for circulating the gas, and side panels and a perforated plate, where the high-pressure chamber is positioned so that the perforated plate is facing a conveyor belt for transporting products allowing the gas to be impinged through the perforated plate onto the conveyor belt, which is arranged in a zone between the perforated plate and a plate member, and where the side walls and the side panels provide a return access channel for the circulated gas and that the zone is provided with at least one open side, which is open towards the return access channel.
BACKGROUND OF THE INVENTIONImpingement freezers are provided to quickly freeze products. By the use of impingement freezers products are placed on a conveyor belt running either below or above a perforated plate where through cooled gas is impinged onto the products causing the products to freeze or cool down.
U.S. Pat. No. 4,584,849 describes a food freezing tunnel where the conveyor belt is positioned above a high pressure chamber and the products are impinged from below. The conveyor belt is arranged inside a tunnel and the gas returns to a return access channel through an overhead structure.
EP-B1-1143814 describes an apparatus for gas treatment of products where the conveyor belt is positioned below a high pressure chamber, and the products are impinged from above and below. The conveyor belt is arranged inside a tunnel, and the gas returns to a return access channel through end openings of channels in the bottom construction.
The drawback of the aforementioned apparatus is that the conveyor belt is arranged inside a tunnel, which provides high pressure resistance because the gas cannot easily escape the tunnel, and furthermore the impingement of gas causes high pressure on the conveyor belt. Both decreases the efficiency of the impingement freezer, because the ventilator must be dimensioned to overcome the pressure resistance and the conveyor must be dimensioned to overcome the impingement pressure. As a result the impingement freezer as described has a large energy consumption and low capacity.
One further drawback is that there is no imminent possibility of controlling the impingement effect described. The only possibility is to regulate either the flow through the gas condition means or the effect of the gas condition means. However, this is not possible as the gas condition means typically works best at a certain gas flow or at a certain effect.
OBJECT OF THE INVENTIONIt is therefore the object of the invention to provide an improved impingement freezer with a controllable and increased impingement effect, and where the conveyor belt is easy to inspect, clean and replace.
This object is obtained with an impingement freezer as described in claim 1 and wherein an impingement freezer comprises an outer housing having side walls, ceiling and floor, where the outer housing comprises gas condition means, preferably for cooling gas and encloses a high-pressure chamber formed by one or more ventilators for circulating the gas, and side panels and a perforated plate, where the high-pressure chamber is positioned so that the perforated plate is facing a conveyor belt for trans-porting products allowing the gas to be impinged through the perforated plate onto the conveyor belt, which is arranged in a zone between the perforated plate and a plate member, and where the side walls and the side panels provide a return access channel for the circulated gas and that the zone is provided with at least one open side, which is open towards the return access channel.
DESCRIPTION OF THE INVENTIONThe impingement freezer comprises an outer housing having side walls, ceiling and floor, whereby a preferably gas tight room is provided, which is necessary for efficient circulation of the gas.
The floor can be a part of the floor in the room wherein the impingement freezer is positioned or can be a separate floor, hence it is possible to position the impingement freezer on e.g. a landing, a deck or on supports or as a hanging unit.
The outer housing comprises gas condition means, preferably for cooling gas, which gas is used for freezing or cooling products. These gas condition means can be e.g. an evaporator, a heat exchanger, pizo-electrical elements, cooling fins or the like. The gas condition means are arranged inside the outer housing so that the circulated gas passes through it at least once whenever the circulated gas is impinged onto the product. Hence the gas condition means are arranged in or at the end of the return access channel.
The gas can be air, nitrogen, carbon oxide or the like. The only parameter is that the product is able to cope with the gas and does not become contaminated by the gas.
The outer housing encloses a high-pressure chamber formed by one or more ventilators, side panels and a perforated plate. The ventilators cause a positive pressure in the high-pressure chamber thus causing the gas to be circulated inside the impingement freezer.
The high-pressure chamber is positioned so that the perforated plate is facing a conveyor belt for transporting products allowing the gas to be impinged through the perforated plate onto the conveyor belt.
The conveyor belt is arranged in a zone between the perforated plate and a plate member and extends through the length of the outer housing, e.g. with a first end part outside the outer housing for placing products on the conveyor belt and with a second end part outside the outer housing allowing the removal of the treated products. Preferably, the conveyor belt is very open such that the gas may easily pass through the conveyor belt.
The side walls of the outer housing and the side panels of the high-pressure chamber provide a return access channel for the circulated gas on at least one side of the conveyor belt. The circulated gas is returned into the high-pressure chamber after having passed the gas condition means.
To obtain an improved impingement freezer with a controllable and increased impingement effect, the zone is provided with at least one open side, which is open towards the return access channel. Hence, the impinged circulated gas is able to quickly exit the zone through the return access channel, and it is possible to circulate more gas around each product on the conveyor belt thus increasing the impingement effect.
One advantage is that the side, which is open towards the return access channel, reduces the back-pressure in the zone containing the conveyor belt, thus it is possible for the ventilators to circulate the necessary amount of gas with reduced energy consumption.
One further advantage is that a part of the circulated gas flows on the plate member in a direction perpendicular to the direction of the conveyor belt, hence helping to treat the products.
Therefore, a multidirectional gas flow is achieved, which may be advantageous for certain shapes of products to be frozen.
According to a preferred embodiment of the present invention the high-pressure chamber is positioned above the conveyor belt, and the plate member is part of a bottom construction positioned below the conveyor belt. To ensure access of circulated gas for impingement from below, an access for the circulated gas is provided from the high-pressure chamber to the bottom construction.
This construction is preferred as the products typically are positioned on the upper side of the conveyor belt, and the main impingement occurs from above through the perforated plate, where the circulated gas is in direct contact with the products, and the secondary impingement occurs from below through the plate member, where the circulated gas bypasses the conveyor belt to get in contact with the products.
To ensure optimal effect of the impingement freezer, the plate member is provided with perforated channels and non-perforated channels, which are arranged preferably perpendicular to the travelling direction of the conveyor belt, and where the perforated channels have at least one access for gas from the high-pressure chamber.
Thus it is possible to impinge products on the conveyor belt from above and below, hence securing faster and better freezing of the products on the conveyor belt, and the capacity of the impingement freezer is increased significantly.
The construction of the plate member with perforated channels and adjacent non-perforated channels allows the circulated gas to circulate through the perforated channels and impinge the products on the conveyer belt and then to escape through the non-perforated channels to the return access channel.
The non-perforated channels ensure that a large part of the circulated gas having impinged the products on the conveyor belt and which contains absorbed heat, is led directly into the return access channel without defrosting the products lying near the outer side of the conveyor belt.
To control the impingement effect, the plate member is replaceable, and the non-perforated channels constitute between 20-70% of the plate member. Hence, it is possible to use a plate member, which is adapted to fit either the specific product on the conveyor belt or the level of necessary impingement of the product. The smaller the area of the plate member, which is constituted of non-perforated channels, the higher impingement effect is obtained, and vice versa the larger the area of the plate member which is constituted of non-perforated channels, the lower impingement effect is obtained.
To secure uniform impingement effect throughout the width of the plate member, the perforated channels are formed with at least one inclined bottom part. The inclined bottom part causes the channel to have a height increasing from the point of gas access towards the return access channel. Hence, the back-pressure in the perforated channels decreases throughout the length of the perforated channels, and the circulating gas has a uniform flow from the perforated channels of the plate member into the adjacently arranged non-perforated channels whatever position along the channels.
According to one embodiment of the present invention the impingement freezer is built with multiple conveyor belts, where the high-pressure chamber extends above a number of the conveyer belts, and where the access for gas from the high-pressure chamber to the bottom construction is arranged between the conveyer belts.
Typically the impingement freezer is built having two conveyor belts arranged symmetrically inside the outer housing so that the access for gas from the high-pressure chamber to the bottom construction is arranged in the centerline of the outer housing and between the two conveyer belts.
Hence, the circulated gas is led through the gas condition means into the high-pressure chamber and causes impingement on each conveyor belt from above through the perforated plate and from below through the plate member of the bottom construction. Thus the gas on both sides of the impingement freezer leaves the zone containing a conveyor belt through the channels in the plate member and the open side into the return access channel.
To inspect or clean the high-pressure chamber or the perforated plate, the high-pressure chamber is provided with side panels, which can be opened wholly or partly.
To inspect or clean the perforated plate or the underlying conveyor belt, the perforated plate is pivotally hinged. Hence, it is possible to get access to the conveyor belt from above.
To enter the outer housing for either inspection of the impingement freezer or cleaning of the high-pressure chamber, the conveyor belt and the bottom construction, the outer housing is provided with side panels, which can be opened wholly or partly.
As an alternative to openable side walls part of the side wall can be formed of a transparent material, hence it is possible to inspect the conveyor belt during the impingement process, without entering the outer housing.
The impingement freezer according to the present invention can be used for freezing for example fish, meat, cookies, dough, vegetables or the like. Alternatively, the impingement freezer is applicable for cooling liquid in e.g. bottles. One further alternative is to use the impingement freezer to heat/bake products, however, to do so it is necessary to use gas condition means like e.g. a heater, heating grills, heat exchanger or the like.
The invention is described in details in the following drawing, wherein
The outer housing 2 comprises gas condition means 6 for cooling air and encloses a high-pressure chamber 7 formed by one or more ventilators 8 for circulating the gas, side panels 9 and a perforated plate 10.
The high-pressure chamber 7 is positioned above the conveyor belt 11 so that the perforated plate 10 is facing the conveyor belt 11 allowing the gas to be impinged through the perforated plate 10 onto the conveyor belt 11, which is arranged in a zone (not shown) between the perforated plate 10 and a plate member 12
The plate member 12 is part of a bottom construction 13 positioned below the conveyor belt 11 and the plate member 12 is provided with perforated channels 14 and non-perforated channels 15, which are arranged preferably perpendicular to the travelling direction of the conveyor belt 11.
The conveyor belt 11 has a first end part 16 outside the outer housing 2 for placing the products (not shown) on the conveyor belt 11 and a second end part 17 outside the outer housing 2 allowing the removal of the treated products (not shown).
The outer housing 2 comprises gas condition means 6 for cooling air and encloses a high-pressure chamber 7 formed by ventilator 8 for circulating the gas, side panels 9 and a perforated plate 10.
The side walls 3 and the side panels 9 provides a return access channel 18 for the circulated gas.
The gas condition means 6 are arranged at the end of the return access channel 18, thus causing the circulated gas to pass through before entering the high pressure chamber 7.
The perforated plate 10 is pivotally hinged allowing access into the zone 19 from above.
The conveyor belt 11 is arranged in the zone 19 between the perforated plate 10 and a plate member 12, and the zone 19 is provided with at least one open side 20, which is open towards the return access channel 18.
The perforated channels 14 are provided with one access 21 for gas from the high-pressure chamber 7, and the perforated channels 14 are formed with inclined bottom part 22, hence causing uniform distribution of the circulated gas.
Claims
1. Impingement freezer (1) comprising an outer housing (2) having side walls (3), ceiling (4) and floor (5), where the outer housing (2) comprises gas condition means (6), preferably for cooling gas, and encloses a high-pressure chamber (7) formed by one or more ventilators (8) for circulating the gas, side panels (9) and a perforated plate (10), where the high-pressure chamber (7) is positioned so that the perforated plate (10) is facing a conveyor belt (11) for transporting products allowing the gas to be impinged through the perforated plate (10) onto the conveyor belt (11), which is arranged in a zone (19) between the perforated plate (10) and a plate member (12), and where the side walls (3) and the side panels (9) provide a return access channel (18) for the circulated gas, and that the zone (19) is provided with at least one open side (20), which is open towards the return access channel (18).
2. Impingement freezer (1) according to claim 1, wherein the high-pressure chamber (7) is positioned above the conveyor belt (11), and the plate member (12) is part of a bottom construction (13) positioned below the conveyor belt (11), and where there is access (21) for the gas from the high-pressure chamber (7) to the bottom construction (13).
3. Impingement freezer (1) according to claim 1, wherein the plate member (12) is provided with perforated channels (14) and non-perforated channels (15), which are arranged preferably perpendicular to the travelling direction of the conveyor belt (11), and where the perforated channels (14) have at least one access (21) for the gas from the high-pressure chamber (7).
4. Impingement freezer (1) according to claim 1, wherein the plate member (12) is replaceable, and the non-perforated channels (15) constitute between 20-70% of the plate member (129.
5. Impingement freezer (1) according to claim 3, wherein the perforated channels (14) are formed with at least one inclined bottom part (22).
6. Impingement freezer (1) according to claim 1, wherein the high-pressure chamber (7) extends above a number of the conveyer belts (11) and where the access (21) for the gas from the high-pressure chamber (7) to the bottom construction (13) is arranged between the conveyer belts (11).
7. Impingement freezer (1) according to claim 1, wherein the high-pressure chamber (7) is provided with side panels, which can be opened wholly or partly (9).
8. Impingement freezer (1) according to claim 1, wherein the perforated plate (10) is pivotally hinged.
9. Impingement freezer (1) according to claim 1, wherein the outer housing (2) is provided with side walls (3), which can be opened wholly or partly.
Type: Application
Filed: Mar 2, 2006
Publication Date: Jul 10, 2008
Applicant:
Inventor: Erik Benned Petersen (Sundby)
Application Number: 11/885,661
International Classification: F25D 13/06 (20060101);
