EP3550225A1 - Device for cooling products - Google Patents

Abstract

A device for cooling products comprises a cyclone (2), the housing of which has a circular cylindrical rear section (3) and an adjoining, conically shaped front section (4), which opens into an outlet opening (5). At the rear section (3) there is a cover (6) with a gas discharge line (7) which runs concentrically through it and which opens out inside the cyclone (2), a supply line for a cryogenic refrigerant and supply line (18) which opens tangentially into the rear section (3). In order to improve the efficiency of the cooling process, according to the invention a product discharge (20) is provided which adjoins the outlet opening (5) of the front section (4) and in which means (21, 22, 23) for building up a Back pressure against the flow pressure of the outflowing product generated in the cyclone (2) are arranged.

Description

The invention relates to a device for cooling products, comprising a cyclone having a housing with a circular cylindrical rear portion and an adjoining, conically shaped front portion, wherein on the front portion opposite the upper end side of the rear portion of a lid with a concentrically passed therethrough , in the interior of the cyclone spaced from the lid with a circular gas outlet opening opening gas discharge line is arranged with a connected to a supply line for a cryogenic refrigerant supply nozzle, which opens tangentially into the rear portion m area of the upper end side, and with at least one opening into the rear portion supply line for a product to be cooled.

Liquid, pasty or powdered products, especially foods such as cake fillings, sauces and marinades, which are prepared at high temperatures often need to be rapidly cooled after their preparation, for example to preserve the internal structure of the product or counteract bacterial growth. Cooling can be done for example by means of electrically operated, conventional cooling units, but this is associated with a considerable use of energy. Alternatively, direct contact of the product to be cooled with a cryogenic refrigerant is recommended. The refrigerant absorbs part of the heat of the product and evaporates or sublimates without residue.

In the following, "liquid cryogenics" are understood as meaning liquid, solid or gaseous media which have a temperature of -20 ° C. and below on contact with the product to be cooled. In particular, the cryogenic refrigerant is a liquified gas, such as liquid nitrogen, or carbon dioxide in solid or liquid form.

When using carbon dioxide as a cryogenic refrigerant this is usually in liquid form under a pressure of about 5.18 bar abs. introduced and relaxed at a nozzle, the so-called expansion nozzle to atmospheric pressure (1 bar). The carbon dioxide cools to a Temperature of minus 78.9 ° C (194 K), resulting in a mixture of carbon dioxide snow and cold carbon dioxide gas. At least the carbon dioxide particles are then used to cool products and, for example, applied to the surface of a product to be cooled or, in the case of a liquid, pasty or powdery product, mixed into the product.

From the EP 1734 320 A2 a device is known in which a cooled to be pumped product and a cryogenic refrigerant, such as liquid nitrogen, liquid carbon dioxide, liquid argon or liquid air, in a vortex worm cooler in contact and intimately mixed. The mixture is then fed to a separator at which the evaporated cryogenic refrigerant is withdrawn. The cooled product is then ready for further processing or packaging.

From the WO 2005/053440 A1 a device for cooling liquid products is known in which in a container filled with the product to be cooled, a cryogenic refrigerant, for example, liquid nitrogen or liquid carbon dioxide is introduced. The refrigerant vaporizes upon thermal contact with the product and is withdrawn at a headspace of the container. After the cooling process, the cooled product is removed via a line branching off from the bottom of the container.

The WO 2016/060869 A1 relates to a device for cooling liquid foods, such as sauces. In this article, the product is passed through a pipeline into which a cryogenic refrigerant, such as liquid nitrogen, is introduced at one or more locations. However, the device described is quite complex in construction, especially since the evaporation of strongly expanding refrigerant requires a pressure-stable design of the pipeline.

In the EP 3 234 485 A1 describes a method in which a product to be cooled is brought into contact with expanding carbon dioxide in a cyclone. It forms a mixture of solid carbon dioxide particles and the product, which is withdrawn from a arranged in the bottom region of the cyclone outlet becomes. The only short contact of product and carbon dioxide particles, however, only leads to a relatively minor cooling of the product.

The invention is therefore based on the object to provide an efficient and easy-to-use way to cool flowable, especially liquid or powdery products.

This object is achieved by a device having the features of patent claim 1 and by a method using a device according to the invention having the features of patent claim 7. Advantageous embodiments are specified in the subclaims.

A device of the type and purpose mentioned above is thus according to the invention characterized in that the outlet opening of the front portion is fluidly connected to a product discharge for cooled product, are arranged in the means for establishing a counter-pressure to the flow pressure of the effluent product through the discharge product counteracting.

The device according to the invention thus comprises a cyclone whose housing has, in a manner known per se, a cylindrical rear section and an adjoining, conically formed front section, which opens into an outlet opening. On the opposite side of the front portion of the rear portion of a lid with a guided through this, spaced inside the cyclone from the lid with a gas outlet opening out gas outlet line (also called dip tube) is arranged. The cyclone is usually vertical, wherein the outlet opening of the front portion is directed downwards and the gas outlet opening upwards. In the rear section of the cyclone opens tangentially a supply line for a refrigerant, which is equipped with an end nozzle opening. Furthermore, a supply line for supplying a product to be cooled opens into the rear section. For example, the supply line for the product opens substantially perpendicular or at an acute angle to the flow direction of the refrigerant in the rear portion and spaced from the nozzle opening of the Supply line for the refrigerant. To avoid freezing of the product on the walls of the cyclone, they can be equipped with a - for example electric - heater.

In use of the device, a considerable flow pressure is exerted in the direction of the outlet opening of the front section in the cyclone due to the supply of the refrigerant and its relaxation and / or evaporation. Surprisingly, it has now been found that a particularly efficient cooling of the product can be achieved if a certain backpressure is built up against this flow pressure. The reason for the increase in cooling capacity is not completely clear, possibly the back pressure leads to a longer residence time of the product in the cyclone and thus to a longer contact time with the cryogenic refrigerant. The invention therefore provides that means for generating such a counterpressure are arranged in a product outlet adjoining the outlet opening.

The means for building up a counter-pressure may include flow resistances within the product discharge, such as, for example, a diaphragm or other constriction of the free flow cross-section. In an advantageous embodiment, they comprise a throttle valve, by means of which a specific counterpressure to be achieved can be set. This embodiment is particularly recommended when different products are to be cooled in the device and a certain cooling capacity, depending on the nature and properties of the product, such as temperature or viscosity and / or the temperature to be set is required. The throttle valve may also be controllably configured and during the cooling process, a back pressure in response to a measured parameter, such as the output side temperature of the product, regulated.

In another advantageous embodiment, the means for establishing the back pressure comprise a section of the product outlet, which is designed in the manner of a siphon and comprises at least one geodetically upwardly extending line section. During operation of the device, a section consisting of cooled product is formed in the line section extending vertically upwards Column whose weight (for liquid products: hydrostatic pressure) acts as a back pressure against the flow pressure at the outlet of the cyclone. Of course, the means for building a back pressure can also be combined with each other, so for example, a diaphragm or a throttle valve in the product supply line with a vertically upwardly extending line section.

A particularly advantageous embodiment of the invention provides that the supply line for the product to be cooled opens into the rear section in such a way that a product stream flowing out of it is directed into the flow of the refrigerant introduced at the feed nozzle. As a result, an intimate mixing of product and refrigerant is effected immediately after the product has been introduced.

The entry of the product preferably takes place via a supply line which leads in perpendicular to the refrigerant flow and which is guided, for example, through the cover of the rear section and runs at least with its end section substantially parallel to a longitudinal axis of the cyclone. The product is thus entered in this case substantially perpendicular to the flow direction of the refrigerant in the cyclone. However, the supply line for the product can also open at an acute angle in the rear section, each with a directional component parallel and perpendicular to the refrigerant flow. Incidentally, the supply line for the product can also be equipped with a spray nozzle on the outlet side.

In a particularly advantageous embodiment of the invention, the supply line for the product does not open directly in front of the feed nozzle for the refrigerant in the rear portion, but axially spaced from this. The feed line for the product preferably flows into the rear section 1 cm to 10 cm in front of the feed nozzle, more preferably 2 cm to 5 cm. The product flow in this embodiment meets an already broadened refrigerant flow and is entrained by this.

The object of the invention is also provided with a method for cooling products, using a device according to the invention, with the Characteristics of claim 7 solved. In this case, tangentially a cryogenic refrigerant is introduced into the cyclone at a feed nozzle opening into the rear section of a cyclone. At the same time a product to be cooled is supplied in a directed to the flow of the refrigerant introduced product flow. The mixture of refrigerant and product is separated in the cyclone, wherein the product is discharged via a product discharge, which opens out of a conically shaped front section adjoining the rear section. Evaporated refrigerant is removed via a gas discharge line in the rear section of the cyclone.

According to the invention, a back pressure which counteracts the flow pressure of the outflowing product is produced downstream of the product outlet in the product outlet. The back pressure is adjusted by suitable means to a predetermined value or regulated in dependence on a measured value. As a means, for example, a throttle valve or a bottleneck in the product discharge or the maintenance of a liquid column, against the hydrostatic pressure, the outflow of the cooled product has to be made, are used. By means of the counter-pressure, the flow conditions inside the cyclone are changed in such a way that there is a longer contact time of product and refrigerant and thus more efficient cooling of the product.

Preferably, the backpressure is adjusted to a value of 0.03 to 0.2 bar, more preferably to a value between 0.05 and 0.1 bar. As a cryogenic refrigerant is preferably liquid nitrogen or liquid carbon dioxide, which relaxes when entering the cyclone to a mixture of gaseous and solid carbon dioxide used.

The inventive method and the device according to the invention is suitable for cooling liquid, fluidized or powdery product. In particular, the device according to the invention is used for cooling food products based on fat or water, in particular liquid food products, such as sauces, soups or juices, with or without solid constituents. After cooling in the device according to the invention, the product can then be subjected to further processing steps or a Packaging unit to be supplied. The resulting during the cooling process gaseous refrigerant, such as carbon dioxide gas is withdrawn from the gas discharge line and can be used, for example, for pre-cooling of the cyclone supplied refrigerant.

Example:

The rear portion of the cyclone of a device according to the invention have a tube diameter of for example 250 mm to 300 mm. In the rear section, an aqueous product is introduced at a flow rate of between 2.5 m ³ / h. At the same time liquid carbon dioxide is added as a refrigerant with a flow rate of 1.2 t / h. In the product discharge, for example, by means of a throttle valve, a back pressure between 0.05 bar and 0.1 bar is generated. The product withdrawn at the outlet of the product discharge has a temperature which is up to 40 ° C lower than the temperature of the product supplied.

• Fig. 1: Eine erfindungsgemäße Vorrichtung in einer Schnittansicht längs der Linie I-I in Fig. 2,
• Fig. 2: Die Vorrichtung aus Fig. 1 in einer Schnittansicht längs der Linie II-II in Fig. 1,

Reference to the drawings, an embodiment of the invention will be explained in more detail. In schematic views show:

• Fig. 1 A device according to the invention in a sectional view along the line II in FIG Fig. 2 .
• Fig. 2 : The device off Fig. 1 in a sectional view taken along the line II-II in Fig. 1 .

The apparatus 1 shown in the drawings for cooling products comprises a cyclone 2, the housing in a conventional manner has a rear portion 3 with circular cylindrical cross-section with radius Rz and an adjoining, conically shaped front portion 4, in an outlet opening 5 with Radius Rp discharges. The cyclone 2 is made of a poor thermal conductivity material, such as stainless steel or titanium, and moreover, not shown here, be equipped with a thermally insulating sheath.

On its front side opposite the front section 4, the rear section 3 is closed with a cover 6. A cylindrical gas exhaust pipe 7 with inner radius R _G , which is connected in a manner not shown here to a gas discharge line is passed through the lid 6 in the middle, whereby there is an annular space 8 of the width B _R between the outer wall of the gas exhaust pipe 7 and the inner wall of the rear portion 3. The gas exhaust pipe 7 is led deep into the interior of the cyclone 2 and ends with a gas outlet opening 11 approximately at the level of the plane 12 of the transition between the rear section 3 and front section 4 of the cyclone 2. The rear section 3, the front section 4 and the gas exhaust pipe 7 are along a arranged common vertical axis 9, wherein the outlet opening 5 are arranged below and the gas exhaust pipe 7 at the top of the cyclone 2. For example, the radius Rz is between 10 cm and 15 cm, the radius R _G between 5 cm and 10 cm and the radius R _P between 5 cm and 10 cm.

In the rear section 3 of the cyclone 2 opens a feed nozzle 14 for a cryogenic refrigerant, which is flow-connected via a feed line 15 with a source not shown here for a cryogenic refrigerant. The source is, for example, a tank for cryogenic liquefied nitrogen or for liquefied carbon dioxide. An end portion of the supply line 15, at the front end of which the feed nozzle 14 is located, is disposed within a tangential feed section 16 of the cyclone 2 and axially thereto. A flange connection 17 ensures a gastight connection between feed line 15 and feed section 16.

Furthermore, a product supply line 18 is provided which opens at an outlet opening 19 in the lid 6 perpendicular or obliquely, with an additional tangential direction component, in the rear portion 3. The outlet opening 19 is arranged so that it is aligned with the end portion of the supply line 15 and at a distance D, for example, 2 cm to 5 cm axially spaced in front of the feed nozzle 14 opens.

Adjoining the outlet opening 5 of the front section 4 is a product outlet 20 for discharging cooled product, which in the exemplary embodiment shown here has a cross-sectional radius R _P throughout which corresponds to the radius of the outlet opening 5 of the cyclone. The product outlet 20 has the manner of a siphon on a U-shaped line section, which in use of the device 1 with a manifold 21 geodetically down and with his Legs 22, 23 is directed upward, wherein the leg 22 connects directly to the outlet opening 5. Manifold 21 and legs 22, 23 of the U-shaped line section dimensioned so that in it a liquid column of height H, for example, 500 mm to 800 mm can be maintained.

During operation of the device 1, a cryogenic refrigerant, for example pressure-liquefied carbon dioxide, flows via the supply line 15 at a pressure of more than 5.18 bar (abs.), For example a pressure between 18 and 20 bar (abs.), To the feed nozzle 14 guided, in the cyclone 2 a. At the feed nozzle 14, the carbon dioxide expands to form a stream of carbon dioxide gas and carbon dioxide snow which flows tangentially into the annulus 8 between the inner wall of the rear portion 3 and the outer wall of the gas exhaust pipe 7 and is forced thereon on a helical path 25 descending toward the front portion. as in Fig. 2 indicated. Incidentally, instead of carbon dioxide, another cryogenic refrigerant such as liquid nitrogen may also be used.

Simultaneously with the refrigerant, a liquid product to be cooled is supplied via the product supply line 18. The product mixes in front of the orifice 19 intimately with the registered from the feed nozzle 14 refrigerant and is entrained by the flow. In this case, the refrigerant absorbs heat from the product and evaporates or sublimes at least partially, whereby the product cools.

In a manner known per se, the spiral-shaped path 25 of the vaporized refrigerant at the level of the gas outlet opening 11 transforms into a spiral path ascending within the gas exhaust pipe 7. The gaseous refrigerant escaping at the gas outlet pipe 7 is then preferably collected and used, for example, for pre-cooling the supplied refrigerant in the supply line 15. Due to the circular flows inside the cyclone 2, the liquid droplets or particles of the product are thrown at the latest after a few revolutions due to the centrifugal force to the inner wall of the conical front section 4 and braked so far that they detach from the flow and down in the direction of the outlet opening. 5 to run. The Liquid product is then removed via the U-shaped line section of the product outlet 20.

The supply and expansion of the refrigerant in the cyclone 2 leads to a strong flow pressure of the product towards the Produktausleitung 20. When flowing through the Produktausleitung 20, however, the product must the leg 23 of the U-shaped line section and thus a height H corresponding hydrostatic pressure overcome, which acts as a counterpressure to the flow of the product. The backpressure of, for example, 0.05 bar to 0.08 bar leads to a longer average contact time of the liquid droplets of the product with the refrigerant and thus to a much greater cooling of the product compared to a direct downward led discharge. Incidentally, the device 1 according to the invention is equally suitable for cooling a pulverulent product.

LIST OF REFERENCE NUMBERS

1.

contraption

Second

cyclone

Third

rear section

4th

front section

5th

outlet opening

6th

cover

7th

Gas vent pipe

8th.

annulus

9th

axis

10th

-

11th

Gas outlet

12th

level

13th

-

14th

feed nozzle

15th

supply

16th

feeding section

17th

flange

18th

product supply

19th

outlet opening

20th

Produktausleitung

21st

elbow

22nd

leg

23rd

leg

24th

-

25th

train

B _z

Width of the annular gap

R _G

Inner radius of gas discharge

R _P

Inner radius product rejection

R _Z

Inner radius Rear section of the cyclone

H

Height of a liquid column in the product discharge

D

Distance between feed nozzle and product feed line

Claims (10)

An apparatus for cooling products, comprising a cyclone (2) having a housing with a circular cylindrical rear portion (3) and an adjoining, conically shaped front portion (4) with an outlet opening (5), wherein on the front portion (4 ) opposite the upper end side of the rear portion (3) a lid (6) with a concentrically passed through this, inside the cyclone (2) spaced from the lid (6) with a circular gas outlet opening (11) opening out gas discharge line (7) is arranged with a supply nozzle (14) connected to a supply line (15) for a cryogenic refrigerant, which opens tangentially into the rear section (3) in the region of the upper end side, and with at least one supply line (18) leading into the rear section (3) cooling product,
characterized,
in that the outlet opening (5) of the front section (4) is fluidly connected to a cooled product outlet (20) in the means (21, 22, 23) for establishing a counter pressure acting against the flow pressure of the product flowing out through the product outlet (20) are arranged. Apparatus according to claim 1, characterized in that the means (21, 22, 23) for establishing a back pressure comprise a throttle valve. Apparatus according to claim 1 or 2, characterized in that the means (21, 22, 23) for building up the back pressure comprise a geodetically upwardly extending line section (23) of the product outlet (20), in which a liquid column can be built up during operation of the device , whose hydrostatic pressure acts as a back pressure. Device according to one of the preceding claims, characterized in that the feed line (18) for the product opens into the rear section (3) in such a way that a product stream flowing out of it flows into the rear section (3) the flow of the at the feed nozzle (14) registered refrigerant is directed. Device according to one of the preceding claims, characterized in that the supply line (18) for the product axially spaced from the feed nozzle (14) for the refrigerant in the rear portion (3) of the cyclone (2) opens. Device according to one of the preceding claims, characterized in that the supply line (18) for the product is arranged at least with its in the cyclone (2) opening end portion substantially parallel to a longitudinal axis (9) of the cyclone (2). A method of cooling products using a device according to any one of the preceding claims, wherein a cryogenic refrigerant at a feed nozzle (14) is tangentially introduced into the rear portion (3) of the housing of a cyclone (2) via a cyclone (2 ) opening feed line (18) a product to be cooled is introduced into the flow of the refrigerant introduced and mixed with this, then the mixture of refrigerant and product in the cyclone (2) is separated, the product via a from one to the rear portion (3) subsequent conically formed front section (4) discharging product outlet (20) and vaporized refrigerant via a in the rear section (3) opens out gas discharge line (7) is discharged,
characterized,
that in the product outlet (20) downstream of the flow pressure of the effluent product counteracting backpressure is generated. A method according to claim 7, characterized in that the back pressure is adjusted to a value of 0.03 to 0.2 bar, preferably between 0.05 and 0.1 bar. A method according to claim 7 or 8, characterized in that as cryogenic refrigerant liquid carbon dioxide or liquid nitrogen is used. Method according to one of claims 7 to 9, characterized in that the product is a liquid or powdery product.

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