DE2447108A1 - METHOD AND DEVICE FOR COOLING OR FREEZING ITEMS - Google Patents

Description

Patent attorneys Dipl.-Ing. F. Wh; cxmahn,

Dipl.-Ing. H. Weickmann, Dipl.-Phys. Dr.K. Fincke Dipl.-Ing. F. A. Weickmann, Dipl.-Chem. B. Huber

8 MUNICH 86, DEN

PO Box 860 820

MÖHLSTRASSE 22, CALL NUMBER 98 39 21/22

INTEGRAL PROCESS SYSTEMS, Inc., 70 North Street, Park Forest,

Illinois, V.St.A.

Method and device for cooling or freezing of

Articles.

The invention relates to a method and apparatus for cooling or freezing articles while they are being transported through a ¹ isolated chamber and circulated while a gaseous refrigerant in the chamber in contact with the articles.

The invention aims to provide temperature and gas control for such Kind of provide that the temperature in a recirculation loop is controlled by the flow of a refrigerant fluid and more refrigerant for the chamber when a lower temperature is to be maintained.

According to the invention, a temperature control device is provided for this purpose, the amount of refrigerant introduced per unit of time as a function of the gas temperature in the circulation loop controls, as well as a gas balance control that controls the flow of gas between the recirculation loop and one separate from the main outlet attached vent as a function of the temperature at that vent.

According to the method of the invention, the amount of refrigerant introduced into the chamber is determined by the temperature in the Circulation loop of the gas in the chamber is controlled and gas becomes

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selectively either to the main outlet or to a vent, which are each arranged near the ends of the chamber, depending on the temperature of the gas at the vent.

The invention has the advantage that an optimal cooling temperature is automatically achieved in the chamber.

The following US ^{Pat. No. 1} η are cited in relation to the prior art: 3,345,828; 3,403,527; 3,427,820; 3,431,745 and 3,600,901. None of these publications disclose the features of the present invention.

Further details and advantages of the invention emerge from the following description of an exemplary embodiment based on the attached drawings. Show in it:

Pig.1a and 1b put together a top view of an inventive Contraption;

Mg.2a, 2b and 2c in combination a longitudinal section through the Device of Pig.1a and 1b;

Pig.3 is a side view from the left end of Pig.1a;

Pig.4 a vertical section along the line 4-4 of Pig.2a;

Pig. 5 a fragmentary and semi-schematic horizontal section after line 5-5 of Pig.7;

Pig.6 shows a vertical section along line 6-6 of Pig.2b; Pig.7 is a vertical section along line 7-7 of Pig.2b;

Pig.8 a semi-schematic vertical section through the inventive Contraption·

In the embodiment on which the drawings are based the device 10 for cooling or freezing articles an elongated freezing chamber 11 with a ceiling 12, a floor 13 and side walls 14 and 15, all insulated accordingly. The ceiling 12 consists of insulated walls in Porm of

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2A47108

pivotable covers 16, which can be folded up and lowered in the usual way by means of hydraulic cylinders 17. Only two covers are shown in FIGS 5, 4, 6 and 7 they are shown in side view.

In the freezing chamber 11 is between a product inlet 18 and a product outlet 19 a conventional conveyor 20 is attached, which transports the articles in the chamber on a track, which coincides with its upper path 21 between inlet and outlet. Such an article is shown schematically in Fig. 2c illustrated at 22.

The refrigerant fluid is a liquid and liquid nitrogen is a good example of the device shown. Another example is liquid carbon dioxide. The liquid refrigerant always generates a refrigerant gas in the chamber. In the example shown, the liquid nitrogen is using a spray system 23 initiated, which has an arrangement of nozzles 24, which in the longitudinal direction and transverse direction of the chamber are attached at intervals.

In the example shown in FIG. 4, six nozzles span the width of the chamber 11 and eight nozzles are provided in each longitudinal row, see Fig.2a. The liquid refrigerant becomes the Nozzle arrangement fed via a pipe 25, which is connected to a pipe string 26 is in connection, which connects the nozzles 24 to one another by means of a flexible hose 27. These The arrangement allows the entire spray system 23 for the liquid to be lifted out for cleaning after the cover 16 has been folded up without having to be taken apart.

In order to support the heat transfer, the refrigerant gas is passed over the articles in the chamber 11. This circulation brings the refrigerant gas into intimate contact with the articles, particularly when the conveyor 20 is of the most convenient type wide-meshed metal construction. To the circulation

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middle includes a horizontal plate 28 under the conveyor 20 and thus also among the articles 22 transported on the conveyor, one end 29 of which is a short distance in front the product inlet 18 of the chamber 11 is located. The circulating flow created by a rotating fan-30, takes the one indicated by the arrows 31 in Pig. 2b, 2c, 5, 6 and 7 Course.

The circulation path also includes, as shown in Pig. 2b and 6 can clearly be seen, a channel 32 which lies outside the chamber 11. This channel is, as Fig. 6 shows, under and arranged to the side of the device 10 and is connected to the bottom of the chamber 11 via a vertical connection piece 33, directs the gas vertically downward into channel 32. From there, the circulated gas flows on the side through a passage 34 upwards into the fan 30, where it is directed back laterally into the chamber, around there from curved, spaced-apart Wings 35 in a longitudinal flow towards the product inlet 18, see Fig.5 to be deflected.

Under the spray system 23, a trough 36 is provided, which is inclined towards the circulation channel 32, to coolant gas and excess To direct liquid from the spray zone 37 into the channel 32 due to its inherent gravity.

The product inlet 18 of the chamber 11 is next to it Gas outflow device 38 in connection, the refrigerant gas from the circulation loop 31 discharges through a gas outlet 39. The plate 28, which is close to the product inlet 18 to the chamber and so reaches up to the gas discharge device 38, divides the chamber 11 into a first upper section 40 and a second, lower section Section 41 of the circulation loop 31. As in FIGS. 2b and 2c show, the path 40 provides direct countercurrent contact with the articles 22 for heat exchange. The second Route 41 has no direct contact with the articles.

Above the conveyor 20 are in the chamber 11 in communication

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with the upper path 40 several gas-moving devices 42 are provided, which in the example shown fan with vertical axis which produce a vertical axial flow as indicated by arrows 43. The fans 42 are longitudinally spaced from each other and in the shown For example, six are provided. Depending on the size of the device, however, more or fewer such devices can be used to be appropriate.

As the arrows 43 in FIG. 2b indicate, the blowers discharge downwards through the conveyor and over the articles 22 carried thereon and the flow is then deflected back up again by the impact on the plate 28. The fans 42 serve as turbulence generators for better heat transfer between the articles transported by the conveyor 20 through the chamber and the gas. This has the consequence that the exhaust gases exiting at 39 in FIG. In a practical embodiment of the device according to the invention, the temperature of the exhaust gases 39 was only 80 ^° F (44 ^° G) lower than the temperature of the arriving articles 22. In addition, the transverse and, in the exemplary embodiment, vertical output of the axial fan 44 runs in a direction transverse to the longitudinal The flow path 31 and the combination of gas flows that meet at 90 ° increases the turbulence and thereby improves the heat transfer, so that a shorter chamber 11 can be used for a specific freezing capacity.

The device 10 is in disassemblable for more convenient cleaning Constructed in sections. Such a separable arrangement is described in US Pat. No. 3,580,000.

In the elongated chamber 11 a number of triangular baffle plates 45 are provided which, as can be seen in FIG. This transverse baffle plates 45 ₉ the

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extend through the chamber from one side to the other serve to restrict flow between the inlet end of the Plate 28 and the gas outlet at 38 to the flow volume 46 of the gas from the circulation loop 31 to the gas discharge device 38 limit. This flow limitation by the baffle plates also increases the flow volume in the circulation loop 31 and thus also the linear flow velocity, whereby the heat transfer between the gas in the circulation loop and the transported articles 22 to be cooled is improved.

The ceiling 12 of the chamber is raised on a section 47, namely where the angled deflection vanes 35 the circulated Direct gas 31 back into the beginning of the upper section 40 of the circulation loop, in which the gas is countercurrent to the Direction of transport of the items 22 on the conveyor. 20 flows, as indicated by the arrow 31 in Figure 2c. At this entry point 48 to the circulation loop 31 is a gas balance control provided that the gas flow between the circulation loop and a vent 49 next to the product outlet 19 proportioned.

In the embodiment shown, this includes gas balance control a first damper flap 50 which is hinged so that it is between a position in which it is on top of the Ceiling 12 (Fig.8) and one against that of Fig.8 is pivotable by 90 ° offset position to in this way the gas flow between the circulation loop 31 and thus the Gas outlet 38 at product inlet 18 to chamber and gas vent 49 at the product outlet 19 of the chamber in the correct ratio. This damper flap 50 of the gas balance control also serves to control the gas flow rate in the circulation loop 31, which is the upper The product contact stretch 40 and the lower stretch 41 separated by the plate 28 as described above are. The position of the damper flap 50 is controlled by a thermocouple 51 of the usual type, which is a servomotor

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51, which is also of a common type as embodied in the motor 62 in US Pat. No. 3,600,901.

The gas outflow through the vent 49 is at least sufficiently strong to be under all during operation Operating conditions to prevent the ambient air from flowing into the chamber, so that not warm air, moisture and the like. penetrates. The temperature in the chamber 11 is controlled, by controlling the amount of refrigerant introduced in the unit of time, as by the liquid spray system 23 Nitrogen is indicated. In the illustrated embodiment, liquid nitrogen is passed through a pipe 54 and an adjustable valve 55 is directed to the spray system 23. The flow through valve 55 is automatically controlled by a Servomotor 56 regulated, the activity of which is regulated by a temperature control instrument 57 of known type, which in turn is controlled by a thermocouple 58 located in the outer channel 32 of the recirculation loop. Like Pig. 6 shows, this thermocouple 58 is preferably in the side portion 34 of the duct 32 near the inlet to the circulation fan 30 attached. The temperature control for the interior of the chamber 11 thus works partly by controlling the initiated Amount of coolant as a puncture of the gas temperature in the Circulation loop 31 and specifically in the example described the temperature in the outer part 32 of this circulation loop.

The chamber 11 is also provided with a second damper flap 59, which are arranged at the entry point 60 to the outer channel 32 and next to the adjacent end 61 of the plate 28 is. This second damper flap 59 is by hand between a almost closed position and a fully open position adjustable. The device works as follows: The manually adjustable damper flap 59 is left a little open, as indicated schematically in Pig. 8, and after the start-up the state of equilibrium is a low outflow through vent 49 and exhaust through 38

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achieved with the help of the temperature-controlled damper flap 50. If, due to abnormal conditions in the chamber, this is not sufficient to establish the desired balance, the manually adjustable damper flap 59 is set to a wider gap 60 so that a larger proportion of the gas is drawn from the spray zone directly into the circulation loop, whereby the The outflow through the vent opening 49 is reduced and correspondingly more gas escapes through the outflow device 38. No further adjustments are made to damper flap 59 unless the conditions change to such an extent that readjustment is required. Typical operating conditions that require such a readjustment of the manually adjustable damper flap 59 are a stronger throttling of the flow in the circulation path 31 due to an accumulation of refrigerated goods 22 or due to the construction of the chamber as an exceptionally long tunnel, which by itself is an obstacle to flow in the Circulation path 31 forms, or the like. In the case of a flow balance, cooling gas is blown out slightly through the vent opening 49, which is due to the desired temperature between -23 ⁰ O and -12 ⁰ O (-10 ° to + 10 ⁰ F) or about -18 ⁰ O ( ^{0 0} P) is displayed on the thermocouple 51 so that no circulating air enters.

Once this state has been reached, this is done manually adjustable damper flap 59 no longer touches and all the necessary adjustments for the various loads and different Introduced amounts of heat take place by lowering and raising the first damper flap 50 depending on the Temperature fluctuations at the thermocouple 54 attached to the vent 49. With minimal load, if the passage of articles 22 is minimal or even temporarily interrupted, the damper flap 50 takes its lowest position one that is raised by about 90 ° compared to that shown in Fig.8 Position is pivoted.

The spray system 23 is located between the plate 28 and the product outlet 19 of the chamber. The generated in the spray zone

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te gas flows both in countercurrent to the articles, as indicated by the arrows 62 in Figures 2a and 2b, so also to the Part in the channel 32, where it enters the circulation loop 31. The temperature in the chamber is then determined by the temperature in the circulation loop, measured by the thermocouple 58, controlled, by varying the amount of liquid nitrogen supplied to the spray system 23 through line 62.

It has hitherto been customary to discharge gas from the chamber, for example through the gas discharge device 38, in order to remove the incoming fresh gas 62 to balance out the introduced refrigerant. Since the amount of gas that evaporates from the fresh refrigerant depends on the The load of refrigerated goods that runs through the chamber, depends and therefore changes, must be discharged through the discharge device 38 The amount of gas can be changed in order to adapt to the changes in charge. However, it has proven difficult to control the refrigerant, and particularly the freezing conditions, by itself Regulating the amount of gas discharged at 38 to regulate and equalize. This is because even minimal gas withdrawal from the circulation loop 31 stronger with minimal charges is than the rate of gas generation such that air flows in at product outlet 19 of the chamber.

In accordance with the method and apparatus of the invention, there is always at least a small amount of gas escaping from the vent 4-9 and at 46 to prevent any amount of circulating air from entering. The amount of fresh refrigerant introduced and thus the amount of gas generated is controlled for varying charge conditions by the thermocouple 58, which, as described, controls the amount of fresh refrigerant introduced. In fact, the temperature control shown and described is so sensitive that under all operating conditions the temperature at the vent 49 is kept at about -18 ⁰ G and the temperature at the discharge device 38 is about 44 ⁰ C (80 ⁰ P) below the temperature of the incoming Refrigerated items. This mode of operation is both

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through the adjustable damper flap 50 and its thermocouple 51 at the product outlet of the chamber as well as through the guide of the gas in the recirculation loop 31 reaches through the chamber and in countercurrent to the articles passing through the chamber, the portion circulated through the loop at least partially through the baffle plates 45 described above is controlled.

Different parts of the in the pig. The device shown correspond to parts in the following older German patent applications P 23 31 271.2, filed 6/19/1973; P 23 62 072.6, filed on December 13, 1973 and P 24 18 545.3, filed on April 17, 1974. In the first of these applications is a device described, which uses liquid carbon dioxide as a coolant and also a plate used for circulation corresponding to the plate 28 mentioned above. The control ■ and regulating devices according to the present invention are Applicable in the same way to a cooling system using liquid carbon dioxide as to the system using liquid nitrogen. the The second of the above applications discloses a system in which a throttle element is located between the grass circulation path and the gas outlet is arranged, which serves approximately the same control of the outflow and acceleration of the circulation as the above mentioned baffle plates 45

In the last-mentioned application, a system is described which is similar to the one explained above, but in which the flow-inhibiting Baffles and the temperature and gas balance controls are missing. The damper flaps 50 and 59 for control the gas balance and the temperature control elements 55-58 are already known per se.

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Claims (16)

Expectations 1. Method of cooling or freezing articles using a refrigerant gas characterized in that the articles are passed through an isolated chamber that the gas in the chamber is passed through a recirculation loop into contact with the articles moving through the chamber, that fresh gas is introduced into the chamber to a desired maintain low temperature so that gas is removed from the chamber closest to a product inlet, to compensate for the amount of freshly introduced gas that the gas flow from the recirculation loop to the gas outlet · on the amount is limited, which is necessary to compensate for the freshly introduced gas, and a rapid flow of the circulating gas over the product It is maintained, for efficient cooling, that gas is vented from the chamber to allow inflow of circulating air into the chamber to prevent further the crowd of introduced refrigerant is controlled by the temperature in the circulation loop in such a way that a desired Temperature in the chamber is maintained and that under the control of the temperature of the vented gas selectively Gas is directed from the circulation loop to the gas outlet. 2. Device for performing the method according to claim 1, characterized by a thermally insulated chamber (11) with defining walls (12,13,14,15), a product inlet (18) and a product outlet (19) for passing through the chamber on a conveyor (20) article (22) to be transported, a device (23,24,25,26,27) for introducing a refrigerant into the chamber (11), which forms refrigerant gas in the chamber, an arrangement (28) for circulating the gas in a circulating loop (31), which has a first path (40) with direct heat exchange contact with the articles and a second 509826/0259 2A47108 The route (41) without direct contact with the articles, a gas discharge device (38, 39) from the chamber, which at a distance from the circulation loop (31) on the to the product inlet (18) is arranged towards the side, flow-restricting means (45) in the chamber between the Umwälzschleife (31) and the Grasabströmeinrichtung (38), the the flow volume of the gas from the circulation loop to the Limit the gas outlet and thereby maintain a rapid gas flow in the circulation loop, a vent opening (49) for withdrawing gas from the chamber, which is arranged next to the product outlet (19), a temperature control device (58) that controls the amount of refrigerant introduced per unit time as a function controls the gas temperature in the circulation loop, and a gas balance control (50,51,52) that controls the gas flow between the circulation loop (31) and the vent opening (49) as a puncture of the gas temperature at the vent opening brings into the right proportion. 3. Apparatus according to claim 2, characterized in that the gas balance control has a first damper flap (50) in of the circulating loop (31), which between a fully open position and a constricting the circulating loop Position is adjustable to selectively and proportionally gas from the recirculation loop to the vent (49) conduct. 4. Apparatus according to claim 3, characterized in that the circulating loop (31) has an area (32) which has an exit point of the second route (41) and an entry point to the first route (40), and that the first Damper flap (50) is arranged in this area. 5. Device according to one of claims 2 to 4, characterized in that that the temperature control device has a temperature 509826/0259 temperature sensor (58), which measures the temperature of the gas measures in the second section. 6. Device according to one of claims 2 to 5, characterized by a second damper flap (59), which is by hand is adjustable and is located between the device for introducing the refrigerant and the second path (41). 7. Apparatus according to claim 6, characterized in that the chamber (11) has the shape of a tunnel with a ceiling (12) and a floor (13) and that the first damper flap (50) on the ceiling (12) and the second damper flap (59) is arranged next to the bottom (13). 8. Device according to one of claims 2 to 7, characterized in that that the device (23-27) for introducing the refrigerant between the circulation loop (31) and the Product outlet (19) is arranged. 9. Device according to one of claims 2 to 8, characterized in that that the arrangement for circulating the gas comprises a plate (28) which is arranged in the chamber in this way is that they the circulation loop (31) in the first and second Route (40, 41) divided. 10. Apparatus according to claim 9, characterized in that the plate (28) extends in the longitudinal direction of the chamber between the top and bottom of which extends and that the first track (40) and the conveyor (20) extend over the plate and the second route (41) including the connection area (32) are located below the plate. 11. Device according to one of claims 2 to 10, characterized in that that the chamber (11) has the shape of a tunnel and that a second section of the circulation loop (31) channel (32) located outside the tunnel belongs to the one 50 9 8 26/0259 Entry point for the intake of gas from the chamber and
an exit point for transferring gas into the first
Track (40) of the circulation loop. 12. Device according to claim 5 and 11, characterized in that that the temperature sensor (58) of the temperature control device detects the temperature of the gas in the channel (32). 13. Apparatus according to claim. 6 and 11, characterized in that the second damper flap (59) at the entry point
of the channel (32) is arranged. 14. Device according to one of claims 11 to 13 * thereby
characterized in that the means for introducing a
Refrigerant in the chamber between the channel (32) and
the product outlet (19) is arranged. 15. Device according to one of claims 2 to 14, characterized in that the chamber has the shape of a long tunnel and that the flow-restricting means consist of at least one baffle plate (45) which extends from the ceiling (12)
of the tunnel is down and has sufficient distance from the conveyor (20) to allow the articles to pass through. 16. The device according to claim 15, characterized in that
that several baffle plates (45) are provided, which are arranged at intervals between the circulation loop and the gas discharge device (38). 509826/0259