AU2008350648A1

AU2008350648A1 - Device for freezing and/or cooling products

Info

Publication number: AU2008350648A1
Application number: AU2008350648A
Authority: AU
Inventors: Rudolf Erwin Berghoff
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2008-02-14
Filing date: 2008-12-09
Publication date: 2009-08-20
Also published as: WO2009100747A2; CA2715084A1; WO2009100747A3; US20110197621A1; MX2010008780A; EP2247902A2; BRPI0822268A2

Description

1 Description Device for Freezing and/or Cooling-Down Products The invention relates a device for freezing and/or cooling down products comprising a cooling chamber, which encompasses a transport device for conveying the products through the cooling chamber, at least one device for generating a cold gas atmosphere for the cooling chamber and an extraction device for the cold gas as well as at least one axially conveying ventilator for conveying the cold gas. A use of this device is furthermore the object of the instant invention. A series of devices and methods is known for cooling-down products, wherein cooling-down is to refer to herein as to cooling as well as to freezing and deep freezing. Cooling tunnels and spiral freezers, for example, can be listed as state of the art, in the case of which products are in each case transported through the device and are cooled-down by means of the contact with cryogenic gases. Cryogenic gases in liquid and/or gaseous state are often used for this purpose. The use of liquid nitrogen or liquid carbon dioxide is well known. Conventionally, the liquid nitrogen, e.g., is guided through a heat exchanger and is expanded by means of a throttling valve as expansion device, so as to then be introduced into a cooling tunnel. There, the expanded gas accommodates heat from the products, which are to be cooled-down. The gas, which is heated through this, leaves the cooling tunnel as abstracted gas. To impact the flow through the device, an extraction device is typically used, which extracts the heated gas from the cooling tunnel by means of extraction.

2 Ventilators, for the most part axially conveying ventilators, are furthermore used to improve the flow and to increase the convective heat transfer. It is the object of the instant invention to provide a device for freezing and/or cooling down, which is improved as compared to the state of the art. The posed object is solved in that the axis of the at least one ventilator is attached at an angle to the vertical, wherein the vertical to the moving direction of the products serves as reference direction and the at least one ventilator is attached to the ceiling of the cooling chamber, wherein the axis of the ventilator includes an angle b with a vector, which represents the moving direction of the products, wherein the origin of the vector is placed at the lower end of the axis. The deviation of the axis of the ventilator as compared to embodiments, which typically extend vertically downwards, provides for a specific impacting of the fluid flow of the cold gas through the cooling chamber. The embodiment of a directed fluid flow or agitation of the cold gas is thus preferably made possibly, whereby the convective heat transfer between cold gas and product can be increased considerably with particular advantage. In individual cases, it can also be advantageous to attain a non-directed fluid flow, which is also possible by means of the instant invention. Contrary thereto, the cold gas atmosphere in the case of a common ventilator axis, which extends vertically downwards, is pressed centrally downwards only in the area of the ventilator and rises again directly next thereto. This movement of the cold gas does not represent an embodiment of a fluid flow in terms of the invention, because the cold gas 3 does not leave the close-up range of the ventilator thereby. In the case of devices comprising commonly attached ventilators, the embodiment of a cold gas fluid flow is only possible via the use of an extraction device. In the case of the afore-used wording, a moving direction of the products in the horizontal is assumed. In the event that the moving direction of the products deviates from the horizontal, vertical in terms of the invention can also refer to vertical to the moving direction. In the case of a conveyor belt as transport device, e.g., which rises relative to the horizontal, this leads to the correct positioning for the axis of the ventilator according to the instant invention. As a rule, axially conveying ventilators are equipped with rotor blades comprising a curved profile. The preferred fluid flow direction for the cold gas is opposite to the moving direction of the products, which are moved by means of the transport device, thus in counter flow. For certain applications, however, the reverse, thus the fluid flow direction of cold gas parallel to and in the moving direction of the products, which are to be cooled-down and/or frozen (coflow), can be more advantageous. Preferably, the angle b between the axis and the vector is smaller than 90*, thus acute angled. In the case of counterflow equipment, the fluid flow of the cold gas is supported by means of this arrangement. In the case of the coflow, this arrangement has a delaying or slow-down effect, respectively, on the fluid flow of the cod gas. The relative dwell time of a certain quantity of cold gas in the range of a certain quantity of product, which is to be cooled-down, can thus be varied via the selection, which is made for the 4 arrangement. Different cool-down characteristics can thus be realized, that is, the speed of the cool-down process can thus be adjusted, that is, by how many degrees (*C) the temperature of a product decreases in a certain period of time. According to another advantageous embodiment of the instant invention the angle b between the axis and the vector is greater than 900, thus obtuse angled. In the case of this embodiment, the fluid flow of the cold gas is slowed dcwn in the case of counterflow equipment. In the case of a coflow arrangement, the fluid flow of the cold gas is accelerated, thus supported through this. The possibilities to impact the cool-down process in a device according to the invention through this are the same as already described in the preceding paragraph. Advantageously, the angle a, which the axis of the ventilator draws with the vertical, lies in the range of from 10 to 80, preferably in the range of from 1 to 5'. As was already described with the information, which was provided with reference to angle b, the axis can thereby be deflected in or against the moving direction of the products. Both alternatives are to be covered herein by means of the afore claimed area for the angle a. In the case of more than one ventilator, all of the axes can encompass the same inclination (deviation from the vertical). However, it is also possible, for preparing a course for the fluid flow characteristic, to individually select the inclination of an axis in each case and to attach this axis accordingly.

5 According to an advantageous development of the invention, provision is made for a device for injecting cold gas. Advantageously, provision is made for a cold gas reservoir, in particular for a cold gas reservoir for liquefied cold gas. In the case of such an embodiment, the cooling medium, e.g., which is removed from the cold gas reservoir under a first higher pressure (e.g. approx. 3.5 bar for nitrogen; e.g. approx. 15 bar for carbon dioxide), is fed to an expansion device and is expanded to ambient pressure. The temperature of the cooling medium decreases through this. The cold gas flow generated in that way is supplied into the space for accommodating the products, which are to be cooled down, e.g. to the interior of a cryogenic cooling tunnel, and is used at that location for cooling-down the products. In a particularly advantageous manner, provision is made for liquid nitrogen and/or for liquid carbon dioxide for generating the cold gas. The object of the instant invention is furthermore solved by the use of the device according to one of claims 1 to 7 for freezing and/or cooling-down foods. The instant invention is particularly interesting for sensitive products, which are to be cooled-down, such as foods or pharmaceuticals, for example, because it is particularly advantageous in the case of these products to be able to influence the cool-down characteristics in the described manner. The invention provides a series of further advantages, only a few of which will be mentioned below in an exemplary manner: By specifically embodying a cold gas fluid flow by means of the ventilators, the convective heat transfer between cold 6 gas and product, which is to be cooled, can be increased in an advantageous manner. It would not be possible to reach this goal by means of the extraction capacity of the extraction device or it would not be possible to reach an increase thereof, because it would thereby not be possible to adjust the length of dwell time of the cold gas in the cooling tunnel independent on the extraction capacity. However, the instant invention provides for a further adjusting possibility, which makes it possible to choose the dwell time in certain limits independent on the extraction capacity. Expensive and extensive reconstruction is not necessary for existing equipment. Only the attachment of the ventilator or of the ventilators to the ceiling of the cooling chamber must be modified so as to provide for a suitable attachment. Existing equipment can be upgraded and converted by means of the invention. The already available equipment parts can thereby be reused for the most part. Contrary to conventional methods, an additional energy yield is possible by means of the invention. The invention as well as further embodiments of the invention will be defined in more detailed below by means of the exemplary embodiment, which are illustrated in the figures. Figure 1 shows a freezing tunnel (overview) according to the invention, Figures 2 to 5 show schematic illustrations of different inclination possibilities for the axis of a ventilator according to the invention.

7 Figure 1 shows a freezing tunnel comprising all of the substantial components as overview. The inclination of the axes of the ventilators cannot be seen in detail in this illustration, because the deviation is very small. In Figures 2 to 5, this deviation is illustrated in an exaggerated. manner, which first makes it visible. The freezing tunnel thus encompasses a cooling chamber 1 and a transport device 2, on which the products 6, which are to be cooled-down, rest, and by means of which these products are transported through the cooling chamber, namely from left to right in this example. The fluid flow of the cold gas, which escapes from the device 3 for generating a cold gas atmosphere, which is sprayed onto the products 6 or which acts upon the products 6 in the area of the device 3, respectively, is oriented in this example opposite to the transport direction of the products. The cold gas thus flows herein from right to left through the cooling chamber 1. The fluid flow is supported by two ventilators 4, the axes 5 of which are deflected out of the vertical such that the angle b between the axis 5 and the vector, which represents the moving direction of the products 6, is in each case smaller than 90*, thus acute angled. The fluid flow is supported through this, is thus accelerated as compared to a device comprising ventilators, which are conventionally attached vertically. Both of the areas A and B illustrated in Figure 1 can be characterized as precooling area A and as cooling area B. Figure 2 shows an angle b between the axis 5 and the vector of less than 900, thus acute angled. In the case of counterflow equipment, the fluid flow of the cold gas is supported by means of this arrangement.

8 The fluid flow direction of the cold gas is indicated in Figures 2 to 5 in each case by means of a dashed arrow. Figure 3 shows the acute angled arrangement in the case of the coflow, in which said arrangement has a delaying or slow down effect on the flow of the cold gas, respectively. Figure 4 shows another advantageous embodiment of the instant invention, in the case of which the angle b between the axis 5 and the vector is greater than 900, thus obtuse angled. In the case of this embodiment, the fluid flow of the cold gas is slowed down in the case of a counterflow arrangement. Figure 5 shows the obtuse angled arrangement for the case of a coflow arrangement. The fluid flow of the cold gas is accelerated through this, is thus supported. The relative dwell time of a certain quantity of cold gas in the area of a certain quantity of product, which is to be cooled-down, can thus be varied via the selection, which is made for the arrangement. Different cool-down characteristics can thus be realized, that is, the speed of the cool-down process can thus be adjusted, that is, by how many degrees

(

0 C) the temperature of a product decreases in a certain period of time. The extraction capacity of the extraction device 7 (see Fig. 1) can thereby be held so as to be constant in an advantageous manner.

Claims

1. A device for freezing and/or cooling-down products comprising a cooling chamber (1), which encompasses a transport device (2) for conveying the products (6) through the cooling chamber (1), at least one device (3) for generating a cold gas atmosphere for the cooling chamber (1) and an extraction device (7) for the cold gas as well as at least one axially conveying ventilator (4) for conveying the cold gas, characterized in that the axis (5) of the at least one ventilator (4) is attached at an angle to the vertical, wherein the vertical to the moving direction of the products (6) serves as reference direction and the at least one ventilator (4) is attached to the ceiling of the cooling chamber (1), wherein the axis (5) of the ventilator (4) includes an angle b with a vector, which represents the moving direction of the products (6), wherein the origin of the vector is placed at the lower end of the axis (5).

2. The device according to claim 1, characterized in that the angle b between the axis (5) and the vector is smaller than 900, thus acute angled.

3. The device according to claim 1, characterized in that the angle b between the axis (5) and the vector is greater than 90*, thus obtuse angled.

4. The device according to one of claims 1 to 3, characterized in that the angle a, which the axis (5) of the ventilator (4) draws with the vertical, lies in the range of from 10 to 8*, preferably in the range of from 10 to 50. 10

5. The device according to one of claims 1 to 4, characterized in that provision is made for a device for injecting cold gas.

6. The device according to one of claims 1 to 5, characterized in that provision is made for a cold gas reservoir, in particular for a cold gas reservoir for liquefied cold gas.

7. The device according to one of claims 1 to 6, characterized in that provision is made for liquid nitrogen and/or liquid carbon dioxide for generating the cold gas.

8. A use of the device according to one of claims 1 to 7 for freezing and/or cooling-down foods. 11 Summary Device for Freezing and/or Cooling-Down Products The invention relates to a device for freezing and/or cooling-down products comprising a cooling chamber (1), which encompasses a transport device (2) for conveying the products (6) through the cooling chamber (1), at least one device (3) for generating a cold gas atmosphere for the cooling chamber (1) and an extraction device (7) for the cold gas as well as at least one axially conveying ventilator (4) for conveying the cold gas, characterized in that the axis (5) of the at least one ventilator (4) is attached at an angle to the vertical, wherein the vertical to the moving direction of the products (6) serves as reference direction and the at least one ventilator (4) is attached to the ceiling of the cooling chamber (1), wherein the axis (5) of the ventilator (4) includes an angle b with a vector, which represents the moving direction of the products (6), wherein the origin of the vector is placed at the lower end of the axis (5). The invention furthermore relates to a use of the device (Fig. 1)