JP2611928B2 - Food freezing method and food freezing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for freezing fresh foods and / or processed foods such as agricultural products, livestock products and marine products.

[0002]

2. Description of the Related Art As one method for preserving fresh foods and processed foods, freezing and refrigeration of these foods is widely performed. , Air blast freezing, low temperature liquefied gas freezing, brine indirect contact freezing, and a combination thereof are often used.

[0003] In the case of the air blast freezing method, cold air generated by using a refrigerant circulation type heat exchanger or a blower is supplied into a freezer to freeze food. In the case of the low-temperature liquefied gas freezing method, a refrigerant such as liquefied nitrogen or liquefied carbonic acid is directly injected into a food from an injection nozzle in a freezer to freeze it. In the case of the brine indirect contact freezing method, the food carried into the freezer via a belt conveyor is brought into contact with the brine in the freezer and frozen.

[0004]

SUMMARY OF THE INVENTION Each of the above-mentioned freezing methods comprises:
Although they have almost reached the mature technical field, the following problems remain in practicing them rationally.
In other words, in the case of the air blast freezing method, the food is cooled by cold air dependent on a heat exchanger, so that the freezing time of the food is prolonged, thereby deteriorating the quality of the food and the initial cost. Get higher. In the case of the low-temperature liquefied gas freezing method, a large amount of expensive refrigerant is consumed, so that the running cost increases. In addition, since the low-temperature liquefied gas adheres to the metal conveyor belt for food transportation in the liquid state, the conveyor belt is supercooled and causes local freezing, which causes trouble during food transportation I do.
In the case of brine indirect contact freezing method, food is frozen by contact with brine, so it is not suitable for freezing foods with small surface area (heat exchange area) and foods with uneven surface, and should be frozen. Are limited. When air blast freezing method and low temperature liquefied gas freezing method are used together,
Trouble of the transport equipment caused by freezing of the conveyor belt occurs. Further, when the low-temperature liquefied gas freezing method and the brine indirect contact freezing method are used in combination, not only troubles at the time of transporting the food but also a situation where the brine solidifies occur.

SUMMARY OF THE INVENTION In view of the above technical problems, the present invention reduces food freezing time, reduces running costs, freezes various kinds of foods, and freezes foods while stabilizing food transportation. It is intended to provide a method and a food freezing device.

[0006]

According to the present invention, in order to achieve a desired object, a method for freezing food in a freezer in which food is carried in through a transporting means is performed with an atmosphere gas in the freezer. The method is characterized in that a low-temperature liquefied gas is mixed with a cold air generating means to generate a frozen air stream whose temperature is controlled, and the frozen air stream is brought into contact with food in a freezer to freeze the food.

[0007] In order to achieve the intended purpose, the food freezing apparatus according to the present invention comprises a freezer having an internal space for receiving the food, and an endless rotating body for carrying the food in and out of the freezer. Combined with the conveyor unit
In addition, in the food freezing device in which the endless rotating body of the conveyor unit extending inside and outside the freezer passes through the entrance of the freezer, the inside of the freezer, and the exit of the freezer, to generate a frozen air flow in the freezer. A cool air generation unit, a casing having an outlet and a suction port, an injection nozzle for injecting a low-temperature liquefied gas into the casing, and an atmosphere gas introducing device for introducing an atmosphere gas in a freezer into the casing, A temperature measuring device for measuring the temperature of the cold air in the casing, wherein the cold air generating unit is disposed in the freezer and the outlet thereof is directed to the endless rotating body in the freezer. I do.

[0008] In one embodiment of the food freezing apparatus according to the present invention, a forward-flow-type cold-air generating unit for generating a frozen airflow that goes forward in the rotation direction of the endless rotating body, and And a counter-flow type cold air generation unit for generating a reversing frozen air flow is arranged in the freezer, and the outlet of the forward flow type cold air generation unit is directed to the endless rotating body at the inlet side in the freezer. Along with
The outlet of the counter-current type cold air generating unit is directed toward the endless rotating body on the outlet side in the freezer. In another embodiment of the food freezing apparatus according to the present invention, the upper part of the endless rotating body in the freezer has a cool air circulation inlet at a longitudinal end and a cool air circulation outlet at a middle part in the longitudinal direction. It is covered with a hood, and the outlet of the cool air generation unit is connected to the cool air circulation inlet of the hood. The outlet of the cool air generation unit in the above is formed by a duct as an example.
As another embodiment of the food freezing apparatus according to the present invention other than the above, a brine tank may be arranged below the endless rotating body in the freezer.

[0009]

In the method of freezing food according to the present invention, an atmosphere gas (low temperature) in the freezer and a low temperature liquefied gas (extremely low temperature) are mixed in order to create a frozen air flow for freezing food. Since the obtained refrigerated gas stream is composed of a mixed gas of a low-temperature gas and a cryogenic gas, it has a control temperature (thermal equilibrium temperature) determined by the mixing ratio of these two gases, and the low-temperature liquefied gas contained in the gas is an atmosphere. It is completely vaporized by mixing with gas. Therefore, the food can be rationally frozen in a short time by bringing the frozen air stream into contact with the food in the freezer.

[0010] In the food freezing apparatus according to the present invention, since the above-described cold air generating unit for generating the frozen airflow is disposed in the freezer, it can be used to freeze the food in the same manner as described above. it can.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of a food freezing method / food freezing apparatus according to the present invention will be described with reference to FIG. In FIG. 1, 11 is a freezer having an internal space for receiving food, 21 is a conveyor unit for loading and unloading food into and out of the freezer, 31 is a cool air generating unit for generating a frozen air flow, and 41 is a control unit. The board 51 indicates food.

The freezer 11 is formed of a well-known heat insulating wall material and has a box shape. An inlet 12 and an outlet 13 are formed on both sides of the freezer 11, and an exhaust port 18 is provided on the upper surface of the freezer 11. Are formed. Entrance 12 of freezer 11
The outlet 13 and the outlet 13 are covered by air curtains (air jet films) 16 and 17 formed through known or well-known air jets 14 and 15 provided near them. An exhaust pipe 20 having an exhaust blower 19 is connected to an exhaust port 18 of the freezer 11.

The conveyor unit 21 includes the endless rotating body 2
2, a driving wheel 23 and a driven wheel 24, a speed adjustable electric motor (motor) 25, a transmission belt 26, a base 2
7 is a main component, and a long tunnel-shaped hood 28 is a related component. In the conveyor unit 21, a driven wheel 24 disposed outside the entrance 12 of the freezer 11 and a driving wheel 23 disposed outside the exit 13 of the freezer 11 are each rotatably supported via a base 27. The endless rotating body 22 wound around the driving wheel 23 and the driven wheel 24 is connected to the entrance 1 of the freezer 11.
2. In addition to the endless rotation inside and outside the freezer 11 via the inside of the freezer 11 and the outlet 13 of the freezer 11, the transmission belt 26 is arranged on the driving wheel 23 side of the conveyor unit 21. It is wound around an electric motor (motor) 25 and its driving wheel 23. As shown in FIG. 1, a tunnel-type hood 28 for covering the endless rotating body 22 of the conveyor unit 21 has cool air circulation inlets 29a and 29b at both ends in the longitudinal direction, and cool air at an intermediate portion (central portion) in the longitudinal direction. It has circulation outlets 30a, 30b,
And covers the upper part (ascending part) of the endless rotating body 22. In the above-described conveyor unit 21, when the endless rotating body 22 is formed of, for example, a metal belt (steel belt), a pulley type or a roller type is used as the driving wheel 23 and the driven wheel 24. As another example, when the endless rotating body 22 is composed of a pair of parallel chain belts and a number of metal belt pieces attached to these chain belts, a sprocket gear type is used as the driving wheel 23 and the driven wheel 24. Is used. The tunnel-type hood 28 may be made of any material, for example, metal, synthetic resin, or a composite thereof, regardless of whether or not the material has heat insulation.

In the case of the cool air generating unit 31, the outlet 3
2, a casing 34 having a suction port 33, an injection nozzle 35, an atmospheric gas introducing device 36, and a temperature measuring device 37. The members forming the wall surface and the like of the casing 34 are also made of a metal, a synthetic resin, and / or a composite material thereof, with or without heat insulation. Casing 3
The 4 outlets 32 are formed by ducts. The injection nozzle 35 for injecting the low-temperature liquefied gas is made of a ready-made one, and is connected to a liquefied gas cylinder (not shown) via a pipe having a valve. Atmospheric gas introduction machine 3
Reference numeral 6 denotes a well-known electric fan, and the temperature measuring device 37 is also a commonly used one for low temperature measurement. In the above, the injection nozzle 35 is provided inside the casing 34, and the atmospheric gas introducing device 36 is
The temperature measuring device 37 is mounted in an air outlet (duct) 32 of a casing 34. Inside the freezer 11, two cold air generating units 31 assembled in this manner are arranged symmetrically. For convenience of explanation, when one (forward flow type) cool air generation unit is 31A and the other (counter flow type) cool air generation unit is 31B, the outlet 32 of the cool air generation unit 31A is connected to the cool air circulation inlet 29a of the hood 28, The outlets 32 of the cool air generating unit 31B are connected to the cool air circulation inlets 29b of the hood 28, respectively, and these outlets 32 are directed to the endless rotating body 22 in the freezer 11.

The control panel 41 receives a temperature measurement signal (a gas temperature measurement signal in the casing 34) from the temperature measuring device 37, and injects the low-temperature liquefied gas by the injection nozzle 35 and the casing 34 by the atmospheric gas introducing device 36. For automatically controlling the amount of gas introduced into the air (the amount of intake air). For this purpose, the conveying speed of the food 51 by the endless rotating body 22 and the amount of gas discharged from the freezer by the exhaust blower 19 are controlled. Functions are added as needed. Such a control panel 41
Is composed of a computer mainly composed of a CPU, and is electrically or electronically connected to a self-evident controlled device. As a control method based on the temperature measuring device 37 and the control panel 41, feedback control is adopted as an example, and PID control is adopted as another example.

The foods 51 to be frozen include fresh foods such as agricultural products (eg, vegetables and fruits), livestock products (eg, beef, pork, chicken), marine products (eg, seafood), and / or
Alternatively, processed foods (eg, various processed foods, processed cereals, cooked products, various confections including frozen desserts, and dairy products) can be given.

When the food is frozen using the apparatus illustrated in FIG. 1, the following is an example. In the case of the conveyor unit 21, the electric motor 2 is
5 is transmitted to the endless rotating body 22, and the endless rotating body 22 is rotated clockwise in FIG. The rotation mode of the endless rotating body 22 may be either continuous rotation or intermittent rotation.

In the case of both the cool air generating units 31A and 31B, a low-temperature liquefied gas (for example, liquefied nitrogen or liquefied carbon dioxide) is injected into the casing 34 through these injection nozzles 35, and at the same time, through an atmosphere gas introducing device 36. Freezer 1
1 is introduced into the casing 34, and a mixed gas flow of the low-temperature liquefied gas and the atmospheric gas, that is, a refrigerated gas flow is generated in the casing 34 of each of the cool air generating units 31A and 31B. Since the low-temperature liquefied gas injected into the casing 34 is completely vaporized when it is mixed with the in-compartment atmosphere gas, the low-temperature liquefied gas does not exist in the frozen airflow in a liquid state.

The frozen air flow on the side of the cold air generating unit 31A is:
Blow outlet 32 of casing 34, cool air circulation inlet 29a of hood 28, inside hood 28, cool air circulation outlet 3 of hood 28
0a, etc., after passing through them, becomes atmospheric gas in the freezer 11, and a part of the atmospheric gas is passed through the atmospheric gas introducing device 36 to the casing 3 on the side of the cold air generating unit 31 </ b> A.
In order to be re-introduced into 4, it circulates through a predetermined route in freezer 11. The cold air flow on the side of the cool air generating unit 31B is also controlled by the outlet 32 of the casing 34, the cool air circulation inlet 29b of the hood 28, the inside of the hood 28, and the cool air circulation outlet 30 of the hood 28.
b, etc., after passing through them, becomes atmospheric gas in the freezer 11, and a part of the atmospheric gas is
6, the casing 34 on the side of the cool air generating unit 31B
In order to be re-introduced into the inside, it circulates through a predetermined route in the freezer 11.

In the initial stage of the generation of the above-mentioned frozen air flows, the temperature is measured by a temperature measuring device 37 provided in the outlet 32 of each casing 34, and the temperature measurement signal (electric signal) is sent to the control panel 41. Is entered. The control panel 41 receiving such a measurement signal determines whether or not each frozen air flow is within the set temperature range, and when these are different from the set temperature, the control panel 41 sends the information to the injection nozzle 35 and / or the atmospheric gas introducing device 36. A predetermined control signal (electric signal) is input to adjust the amount of low-temperature liquefied gas injected into the casing 34 and the amount of intake air, and each frozen air stream is maintained at a predetermined temperature corresponding to the food 51 to be frozen. By the way, the cold air generation unit 31B
The temperature T ₁ in the air outlet 32 and the temperature T ₂ in the latter half in the hood 28 in the above-mentioned operation state are T ₂
> To establish the T ₁ the relationship.

When the apparatus of FIG. 1 is in such an operating state, the food 51 placed on the endless rotating body 22 of the conveyor unit 21 enters the freezer 11 through the inlet 12 and the freezer 11 through the outlet 13. It passes through the hood 28 before going outside. The food 51 in the freezer 11 is
When moving in the first half of the hood 28, it comes into contact with the frozen airflow (forward flow) from the forward-flow type cold air generating unit 31 </ b> A,
1B, and contacts the vortex and turbulent refrigerated airflow in the first and second half hood boundary regions (regions where the forward flow and the countercurrent collide). Therefore, even if the food 51 has a complicated shape or has a small surface area (heat exchange area), the food 51 is sprayed from all directions such as a forward flow, a vortex, a turbulent flow, and a countercurrent. Is frozen in a short time by the freezing air flow.
In addition, since the low-temperature liquefied gas contained in the frozen airflow is completely vaporized, the low-temperature liquefied gas in a liquid state does not come into contact with the endless rotating body 22, and the food caused by the local freezing of the endless rotating body 22. No transport problems occur.

In the freezing method of the present invention (combined use of the air blast method and the liquefied low-temperature gas method), the conventional air blast method, and the conventional liquefied low-temperature gas (LN ₂ ) method, the remaining two when the air blast method is set to 1. The running cost ratio of the method is as follows. Air blast method: Freezing method of the present invention = 1: 2.3 Air blast method: Liquefied low-temperature gas method = 1: 3.5

Atmosphere gas in the freezer 11 when the food is frozen is exhausted to the outside from the exhaust port 18 and the exhaust pipe 20 via the exhaust blower 19 in a timely or steady manner. In this exhaust, care must be taken in some cases to avoid a reduction in the working environment due to the exhaust gas.

The food 51 frozen as described above is stored in the freezer 11 via the endless rotating body 22 of the conveyor unit 21.
After going out, if necessary, it is stored by refrigeration means.

Next, another embodiment of the food freezing method / food freezing apparatus according to the present invention will be described with reference to FIG. The embodiment shown in FIG. 2 is a combination of the cold air freezing means shown in FIG. 1 and the brine freezing means. Therefore, in this embodiment, the brine tank 38 is provided in the above-mentioned freezer 11. Are located in The brine tank 38 for cooling the brine includes, for example, a refrigerant circulation type heat exchanger. The brine 39 accommodated in the brine tank 38 includes calcium chloride, sodium chloride, magnesium chloride, Methanol, denatured alcohol, ethylene glycol, glycerin and the like are optionally used. Of these, sodium chloride brine includes:
Corrosion inhibitors may be added.

In the embodiment shown in FIG. 2, two open brine tanks 38 are used. For convenience of explanation, one brine tank and brine are 38A and 39A, respectively, and the other brine tank and brine are 38B and 3B respectively.
9B, the two brine tanks 38A and 38B are disposed adjacent to each other below the ascending portion of the endless rotating body 22 in front and rear, and the ascending portion of the endless rotating body 22 is
A and 38B are in contact with the brines 39A and 39B. The number of the brine tanks arranged in the freezer 11 may be one, or three or more.

In the embodiment of FIG.
Other configurations except for A, 38B and brine 39A, 39B are substantially the same as those of the embodiment shown in FIG.

When the food is frozen using the apparatus illustrated in FIG. 2, the conveyor unit 21 and both the cool air generating units 31A and 31B are set to the same operation state as the case of FIG. In this case, the food 51 placed on the endless rotating body 22 of the conveyor unit 21 enters the freezer 11 from the inlet 12 and goes out of the freezer 11 through the outlet 13 during the endless rotating body. 22, both brine tanks 38A,
It passes through the hood 28 while being in contact with the brines 39A and 39B in 38B. In the above, when the food 51 when moving in the first half of the hood 28 comes into contact with the brine 39A in the brine tank 38A while receiving the frozen airflow in the forward flow state, and reaches the hood first half, the latter half boundary region. Food 51 is in contact with the vortex, turbulent frozen airflow,
The food 51 when moving in the latter half of the food 28 is
While receiving the countercurrent frozen airflow, the brine tank 38B
With the brine 39B inside. Therefore, food 51
Is frozen in a shorter time than the above as a synergistic effect of these cold air freezing action and brine freezing action. Of course, since the frozen airflow does not contain a low-temperature liquefied gas in a liquid state, not only does the endless rotating body 22 not locally freeze when the food 51 is frozen, but also the brines 39A and 39B do not exhibit an ice crystal state.

Next, another embodiment of the food freezing method / food freezing apparatus according to the present invention will be described with reference to FIG. In the embodiment shown in FIG. 3, a cool air generating unit 31 having a different form from the above and a cool air generating unit 61 having a different form from the above are arranged in the freezer 11. In the case of the cool air generating unit 31 in FIG. 3, an injection nozzle 35 and a temperature measuring device 37 are provided in a casing 34 having an outlet 32 and a suction port 33, and an atmosphere gas introducing device 36 is provided on the suction port 33 side of the casing 34. The outlet 32 of the casing 34 is formed by a simple opening unlike the above-described duct. As such a cold air generating unit 31, FIG.
Can be adopted. In the case of the cold air generating unit 31 illustrated in FIG. 4, the inside of the casing 34 is divided into two chambers R ₁ and R ₂ by a partition wall W having an opening P.
Is partitioned into a blowing port 32 and the suction ports 33 are formed in the chamber R _2. In the above, the injection nozzle 35 is one chamber R _1, the temperature measuring device 37 is equipped, respectively other chamber R _2, atmospheric gas introduction unit 36 is attached to the suction port 33 side of the other chamber R ₂ ing.

Referring to FIG. 3, in the case of the cool air generating unit 61, a refrigerant circulation type heat exchanger 65 is provided in a casing 64 having an outlet 62 on the lower surface and a suction port 63 on the upper surface. The blower-type atmospheric gas introducing device 66 including the above-described fan is attached to the opening 63 side. As such a cool air generation unit 61, the one illustrated in FIG. 5 can also be employed. In the case of the cool air generating unit 61 illustrated in FIG. 5, a casing 6 having an outlet 62 on the lower surface and suction ports 63 on the front and rear surfaces is provided.
4, the heat exchanger 65 and the atmospheric gas introducing device 66 are provided.
On the side.

Referring to FIG. 3, two freeze air generating units 31 and 61 are arranged in freezer 11 respectively. For convenience of explanation, one cold air generating unit is 31A,
When the other cool air generating unit is 31B, the other cool air generating unit is 61A, and the other cool air generating unit is 61B, each of the cool air generating units is on the ascending portion of the endless rotating body 22 and freezes. From the entrance 12 side to the exit 13 side in the warehouse 11, 61A → 31A →
61B → 31B are arranged in this order, and these cold air generating units are connected to the respective outlets 32 of 31A, 31B, 61A, 61B,
62 faces the endless rotating body 22 in the freezer 11.

In the embodiment shown in FIG. 3, the hood 28 for covering the ascending portion of the endless rotating body 22 is omitted, but brine tanks 38A and 38B are provided. In the embodiment of FIG. 3, the description of which is omitted is substantially the same as in each of the above embodiments.

When the food is frozen using the apparatus illustrated in FIG. 3, the conveyor unit 21 and the two cold air generating units 31A and 31B are operated in the same operating state as the case of FIG. , 61B also rotate these atmospheric gas introducers 66 to an operating state. In this case, the food 51 placed on the endless rotating body 22 of the conveyor unit 21 enters the freezer 11 from the inlet 12 and generates cold air during the time from the outlet 13 to the outside of the freezer 11. Units 61A, 31A, 61B,
Brine 39 in both brine tanks 38A, 38B while receiving a predetermined frozen airflow respectively blown from 31B.
B, 39B and is frozen by these cold air freezing and brine freezing. When the food is frozen in this way, the temperature of the frozen airflow blown out from both cold air generating units 61A and 61B can also be controlled via the temperature control means (temperature measuring device, control panel, etc.).

[0034]

According to the method for freezing food according to the first aspect of the present invention, a predetermined temperature-controlled frozen air flow, that is, a mixed gas of atmospheric gas and low-temperature liquefied gas in the freezer is stored in the freezer. Because it comes into contact with the food inside, the food can be reasonably frozen in a short time, and the initial cost is reduced compared to the conventional air blast method,
The running cost can be reduced as compared with the conventional liquefied low-temperature gas method.

A food freezing apparatus according to a second aspect of the present invention includes a casing having an air outlet, a suction port, a nozzle for injecting low-temperature liquefied gas, a gas atmosphere introducing device, and a temperature measuring device for frozen air flow. The cold air generating unit is arranged in the freezer and the outlet is directed to the endless rotating body in the freezer, so that it can be used to freeze food rationally in a short time, Moreover, since the low-temperature liquefied gas contained in the frozen airflow is completely vaporized, machine troubles due to local freezing of the endless rotating body do not occur, and stability in food transportation can be ensured.

In the food freezing apparatus according to the present invention, as described in claim 3, the outlet of the forward-flow type cold air generating unit is directed to the endless rotating body at the inlet side in the freezer, and When the outlet of the cool air generation unit is directed to the endless rotating body on the outlet side in the freezer,
Since frozen airflow can be blown from all directions, such as forward flow, vortex, turbulence, and countercurrent, a wide variety of foods, including foods with complicated shapes and foods with small surface areas, can be shortened by each airflow. Can be frozen in time.

In the food freezing apparatus according to the present invention, when the upper portion of the endless rotating body is covered with a hood for circulating cool air, the frozen air flow is passed through the hood. The food can be efficiently contacted.

In the food freezing apparatus according to the present invention, as described in claim 5, when the outlet of the cool air generating unit is formed by a duct, the frozen air flow is passed through the duct type outlet. We can spray on food efficiently.

In the food freezing apparatus according to the present invention, as described in claim 6, when a brine tank is disposed in the freezer, the food is frozen by using the cold air freezing means and the brine freezing means together. Can be frozen in a short time.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a first embodiment of a food freezing method / food freezing apparatus according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a food freezing method / food freezing apparatus according to a second embodiment of the present invention.

FIG. 3 is a sectional view schematically showing a third embodiment of the food freezing method / food freezing apparatus according to the present invention.

FIG. 4 is a cross-sectional view schematically showing another example of a cool air generating unit (for a refrigerated air flow) used in a third embodiment of the present invention.

FIG. 5 is a perspective view schematically showing another example of the cool air generating unit (for air blast) used in the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Freezer 12 Freezer inlet 13 Freezer outlet 21 Conveyor unit 22 Endless rotating body 23 Driving wheel 24 Follower wheel 25 Motor 26 Transmission belt 27 Base 28 Hood 29a Cold air circulation inlet 29b Cold air circulation inlet 30a Cold air circulation outlet 30b Cold air Circulating outlet 31 Cold air generating unit (31A, 31B) 32 Outlet 33 Suction port 34 Casing 35 Injection nozzle 36 Atmospheric gas introducing device 37 Temperature measuring instrument 38 Brine tank (38A, 38B) 39 Brine (39A, 39B) 41 Control panel 51 Food 61 Cold air generating unit (61A, 61B) 62 Outlet 63 Suction port 64 Casing 65 Heat exchanger 66 Atmospheric gas introducing machine

Claims (6)

(57) [Claims] 1. In a freezer in which food is carried in via a conveying means, an atmosphere gas in the freezer and a low-temperature liquefied gas are mixed by a cold air generating means to generate a temperature-controlled frozen airflow, A food freezing method, wherein the frozen airflow is brought into contact with food in a freezer to freeze the food. 2. A freezer having an internal space for receiving food, and a conveyor unit having an endless rotating body for carrying in and out the food into and out of the freezer, and a conveyor extending in and out of the freezer. In a food freezing device in which the endless rotating body of the unit passes through the entrance of the freezer, the inside of the freezer, and the exit of the freezer, a cold air generating unit for generating a freezing air flow in the freezer includes an outlet and A casing having a suction port, an injection nozzle for injecting a low-temperature liquefied gas into the casing, an atmosphere gas introducing machine for introducing an atmosphere gas in a freezer into the casing, and measuring a cool air temperature in the casing. A cold air generating unit is disposed in the freezer and the outlet is directed to the endless rotating body in the freezer. Food freezing equipment. 3. A forward-flow-type cold-air generating unit for generating a refrigeration airflow that goes forward in the direction of rotation of the endless rotating body, and a direction for generating a refrigeration airflow that goes backward in the direction of rotation of the endless rotating body. A flow-type cold air generation unit is arranged in the freezer, and an outlet of the forward flow type cold air generation unit is directed to the endless rotating body at the entrance side in the freezer, and a counter-current type cold air generation unit is provided. 3. The food freezing device according to claim 2, wherein the outlet is directed toward the endless rotating body on the outlet side in the freezer. 4. An upper end of an endless rotating body in a freezer is covered with a hood having a cool air circulation inlet at a longitudinal end and a cool air circulation outlet at a middle part in a longitudinal direction. The food freezing device according to claim 2 or 3, wherein an outlet of the cool air generating unit is connected to the cool air circulation inlet. 5. The food freezing apparatus according to claim 2, wherein the outlet of the cool air generating unit is formed by a duct. 6. The food freezing apparatus according to claim 2, wherein a brine tank is disposed below the endless rotating body in the freezer.