Liquid freezer

Abstract

To provide a liquid freezer capable of efficiently performing quick freezing with a simple structure even if a cooling liquid is set to about - 50 °C.SOLUTION: A partition plate (21) for placing an article to be frozen is arranged in the middle of a freezing tank (3), a stirring blade (13) is arranged so as to penetrate the wall surface of the freezing tank (3) and to face a cooling coil (14) arranged on the lower side of the partition plate (21), a liquid passing space is provided at the front and rear ends of the partition plate (21), and a liquid flow generated on the lower side of the partition plate (21) by the rotation of the stirring blade (13) exits from the front end side liquid passing space to the upper side of the partition plate (21), flows in the opposite direction to the liquid flow on the lower side of the partition plate (21), and flows from the rear end side liquid passing space to the lower side of the partition plate (21) to circulate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid freezer, and more particularly to a liquid freezer that has a simple configuration and high refrigeration efficiency. [Background technology]

[0002] Many frozen products (mainly food) are processed by the air blast method, which involves freezing in cold air. This method is particularly used for mass production in food processing factories. Recently, however, liquid freezers, which freeze products in a brine solution (antifreeze), have been gaining attention due to the need for rapid freezing. Liquid freezers use a compressor to compress a refrigerant gas, which condenses into a liquid. The resulting liquid is then supplied to tubes inside a freezing tank, cooling the brine solution (antifreeze) inside the tank. With liquid freezers, the product comes into direct contact with the low-temperature brine solution, resulting in a greater surface heat transfer coefficient than with the air blast method, which has the advantage of shortening the freezing time.

[0003] In order to increase the efficiency of removing heat from the surface of the frozen product, it is necessary to increase the heat transfer coefficient (ease of heat transfer), and to do so, it is necessary to cause a flow of brine in the freezing tank. For example, Patent Documents 1 and 2 disclose a food freezing device configured to jet-stir the cooled cooling liquid in the freezing tank using a jet screw pump type jet stirrer with a cooling liquid jet inlet and jet outlet formed in a jet pipe, and to control the temperature, thereby enabling food immersed in the cooling liquid to be frozen uniformly at an ultra-high speed.

[0004] Furthermore, when looking at the inside of the item holding shelves of this conventional liquid freezing type food freezing device, the flow of the cooling liquid is still insufficient, resulting in differences in freezing time between the center and periphery of the item holding shelves, resulting in areas of high quality and areas of low quality among the frozen items, making it difficult to maintain a consistent level of product quality, and the invention disclosed in Patent Document 3 solves this problem. The item freezing method according to this invention includes the steps of immersing items to be frozen placed on the item holding shelves in cooling liquid contained in a freezing tank, and moving the item holding shelves together with the items in the cooling liquid to agitate the cooling liquid, characterized in that the movement is an up and down movement (however, movement of lifting or rotating while processing is excluded). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-121178 [Patent Document 2] Special Publication No. 7-28710 [Patent Document 3] Patent No. 6668563 Summary of the Invention [Problem to be solved by the invention]

[0006] In the inventions of Patent Documents 1 and 2, the jet agitator is installed vertically, and the jet is deflected horizontally at the curved portion at the bottom of the jet agitator. As noted in Patent Document 3, this results in insufficient flow of the cooling liquid, resulting in, for example, different freezing times between the center and periphery of the shelf, resulting in high-quality and low-quality frozen products, making it difficult to maintain a consistent level of product quality. Furthermore, the invention of Patent Document 3 requires not only a propeller-type cooling liquid agitator to move the cooling liquid, but also a shelf drive mechanism to move the frozen products up and down. This results in a complex configuration, which requires laborious maintenance and leads to high costs. Furthermore, the cooling liquid temperature in this case is limited to -35°C to -40°C, and cannot be used at temperatures below that, around -50°C, where the viscosity of the cooling liquid increases.

[0007] The present invention has been made to solve the problems in the above-mentioned conventional technology, and its object is to provide a liquid freezer that has a simple configuration and can efficiently perform quick freezing even when the cooling liquid is set to around -50°C. [Means for solving the problem]

[0008] The invention described in claim 1 to solve the above problem is a liquid freezer having a freezing chamber and a machine chamber, This liquid freezer is characterized in that a partition plate on which the frozen product is placed is placed in the middle of the freezing tank of the freezing compartment, an agitator blade is installed through the wall of the freezing tank so as to face a cooling coil arranged below the partition plate, and liquid passage spaces for the cooling liquid are provided between the agitator blade side end of the partition plate and the inner surface of the freezing tank, and between the end of the partition plate opposite to the agitator blade side and the inner surface of the freezing tank, respectively, and a liquid flow generated below the partition plate by rotation of the agitator blade flows from the liquid passage space on the opposite end side of the partition plate to the upper side of the partition plate, flows in the opposite direction to the liquid flow below the partition plate, and flows from the liquid passage space on the agitator blade side end of the partition plate to the underside of the partition plate and circulates.

[0009] In one embodiment, each of the liquid-permeable spaces is closed with a wire mesh liquid-permeable material.

[0010] In one embodiment, the machine room is equipped with a refrigerator including a compressor and a condenser, a refrigerant pipe extending from the refrigerator and connected to the cooling coil via an expansion valve, and a motor that rotates the agitator blade.

[0011] In one embodiment, the cooling coil, the compressor, the condenser, the expansion valve, and the cooling coil form a refrigeration cycle, and a heat exchanger is provided midway through the cycle.

[0012] In one embodiment, the heat exchanger is arranged so that heat exchange occurs between the refrigerant piping through which low-temperature, low-pressure refrigerant gas returning from the freezing compartment flows and the refrigerant piping through which high-temperature, high-pressure refrigerant liquid flows toward the expansion valve via the compressor and the condenser.

[0013] In one embodiment, the bearing of the rotating shaft of the agitator blade on the freezer tank side is flanged, and a gasket is sandwiched between the flange and the inner surface of the freezer chamber wall, and the flange is tightened with a bolt inserted from the inside of the wall, thereby achieving a liquid seal on the freezer tank side of the rotating shaft.

[0014] In one embodiment, a stuffing box with a male thread on its outer periphery and a gland packing inserted therein is fixed to the outer surface of the freezing chamber, and a gland packing retainer that presses against the gland packing tightens an outer cylinder with a female thread on its inner periphery to the stuffing box, thereby achieving a liquid seal on the outer surface side of the freezing chamber of the rotating shaft of the agitating blade.

[0015] In one embodiment, the walls and bottom of the freezer compartment are made up of three plates: an outer plate, an intermediate plate, and an inner plate; the space between the outer plate and the intermediate plate is an insulating layer filled with insulating material; and the space between the intermediate plate and the inner plate is an ice pack layer filled with ice packs. [Effects of the Invention]

[0016] The liquid freezer of the present invention is as described above, and has a simple configuration that satisfies liquid sealing inside and outside the freezer chamber for the rotating shaft of the horizontally arranged agitator blade. Even when the liquid coolant temperature is set to around -50°C, by changing the flow direction of the liquid coolant above and below the partition plate, it is possible to supply liquid coolant at a sufficient flow rate to the frozen products placed above the partition plate, thereby achieving the effect of efficient quick freezing. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a front view showing an example of the configuration of a liquid freezer according to the present invention. FIG. [Figure 2] 1 is a side view showing an example of the configuration of a liquid freezer according to the present invention. FIG. [Figure 3] 1 is a plan view showing an example of the configuration of a liquid freezer according to the present invention. FIG. [Figure 4] FIG. 2 is a perspective view showing the internal configuration of the freezing tank in the liquid freezer according to the present invention. [Figure 5] FIG. 2 is a perspective view showing the internal configuration of the freezing tank in the liquid freezer according to the present invention. [Figure 6] FIG. 2 is a vertical cross-sectional view showing the installation state of the stirring blades in the liquid freezer according to the present invention. [Figure 7] FIG. 2 is an exploded perspective view showing the configuration of an agitating blade in the liquid freezer according to the present invention. [Figure 8] FIG. 1 is a diagram showing a refrigeration cycle in a liquid freezer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail with reference to the accompanying drawings. The liquid freezer of the present invention is a liquid freezer that freezes items, mainly food, by immersing them in a cooling liquid in a freezing tank, and is composed of a machine chamber 1 installed on the lower level, a freezing chamber 2 placed above it, and a sealing lid 4 that opens and closes the top of the freezing chamber 2, as in the example shown in the figure.

[0019] A partition plate 21 for placing frozen products is disposed in the vertical center of the freezing tank 3 of the freezing compartment 2. An appropriate amount of frozen products are placed in baskets on the partition plate 21 (bottled alcoholic beverages, for example, may be placed directly on the partition plate 21). The partition plate 21 is typically a single stainless steel plate, and is installed by placing both left and right ends on ledges 32 protruding from the inner surface of the freezing tank 3 (see FIG. 5). When installed, liquid-permeable spaces for the refrigerant are provided between the front edge (left end in FIG. 4) of the partition plate 21 and the inner surface of the freezing tank 3, and between the rear edge (right end in FIG. 4) and the inner surface of the freezing tank 3, respectively. While the liquid-permeable spaces may be simple openings, wire mesh liquid-permeable materials 33, 33a are typically disposed therein (see FIG. 4).

[0020] Agitator blade 13 is installed through wall surface 2a of freezing compartment 2 so as to face cooling coil 14 disposed below partition plate 21. Agitator blade 13 causes a flow in coolant 25 below partition plate 21, and as it rotates, a liquid flow generated below partition plate 21 rises as it hits the inner surface of the opposing freezing tank 3, passes through the liquid-permeable material 33 at the front, emerges above partition plate 21, flows above partition plate 21 in the opposite direction to the liquid flow below, and flows back to the bottom of partition plate 21 through rear liquid-permeable material 33a (see arrows in Figure 1), circulating above and below partition plate 21 in the same manner.

[0021] Agitator blade 13 is installed so as to penetrate wall surface 2a of freezing compartment 2. That is, rotating shaft 13a of agitator blade 13 is loosely inserted into pipe 34 arranged to penetrate wall surface 2a of freezing compartment 2, and is journaled on the inner and outer surfaces of wall surface 2a, and liquid seals are provided to prevent liquid leakage from the inner and outer ends of rotating shaft 13a (Figs. 6 and 7).

[0022] Bearing 35 on the refrigeration tank 3 side has a flange 36, and packing 37 is sandwiched between this flange 36 and the inner surface of wall surface 2a, and bolts 38 inserted from the inside of wall surface 2a are tightened with nuts 39, thereby achieving a liquid seal on the refrigeration tank 3 side of rotating shaft 13a. The bolting work for flange 36 is performed before filling the inside of wall surface 2a with insulating material.

[0023] A liquid seal on the outer surface of the freezing compartment 2 is achieved by a gland packing 41, which is a shaft sealing member. A stuffing box 42, which has a male thread on its outer periphery and contains the gland packing 41, is fixed to the outer surface of the freezing compartment 2. A packing gland 43, which presses against the gland packing 41, is tightly fixed by tightly screwing an outer cylinder 44, which has a female thread on its inner periphery, into the stuffing box 42. Preferably, a lock bolt 45 is threaded from the outer cylinder 44 toward the stuffing box 42 to prevent loosening of the outer cylinder 44. The pulley 17 is fixed via a collar 46 to the tip of the rotating shaft 13a protruding from the outer cylinder 44.

[0024] Conventionally, there has been no device in which the rotating shaft 13a of the agitating blade 13 is arranged horizontally through the wall surface of the freezing chamber 2, as in the present invention, because it is thought that it is difficult to achieve a liquid seal on the inner and outer surfaces of this rotating shaft 13a in the freezing chamber 2.

[0025] Disposed within machine room 1 are an air-cooled refrigerator 11 including a compressor and a motor 12 that rotates and drives agitator blades 13 to create a flow in coolant 25 within freezing tank 3, and refrigerant piping 5, which serves as a passage for the refrigerant extending from refrigerator 11, is disposed from the outer surface of machine room 1 toward freezing chamber 2. Refrigerant piping 5 is connected to cooling coil 14 via expansion valve 15 at the upper portion of the outer surface of freezing chamber 2, and cooling coil 14 is drawn from the upper portion of freezing tank 3 toward the inner bottom surface, and is disposed in a serpentine manner (see FIG. 5 in particular).

[0026] Drive shaft 16a of motor 12 protrudes outward from the wall of machine chamber 1, and belt 18 is wound around pulley 16 fixed to drive shaft 16a and pulley 17 fixed to rotating shaft 13a of agitator blade 13 that protrudes outward through one wall of freezer compartment 2. In this way, the rotational output of motor 12 is transmitted to agitator blade 13 via pulley 16, belt 18, and pulley 17, and agitator blade 13 rotates to agitate coolant 25 in freezer tank 3. Note that there is no specified size for pulleys 16 and 17, but it goes without saying that the rotational speed of agitator blade 13 and the flow rate of coolant 25 can be increased by making the diameter of pulley 17 on the rotating shaft 13a side smaller.

[0027] The liquid coolant 25 placed in the freezing tank 3 in a predetermined amount is, for example, an antifreeze such as ethanol-based ethanol brine. The liquid freezer of the present invention is designed for the liquid coolant 25 to be at or below -50°C. At such low temperatures, the viscosity of the liquid coolant 25 increases significantly, making it thick and mushy, so it must be thoroughly stirred. To achieve this, the present invention uses horizontally installed stirring blades 13 below the partition plate 21 to create a horizontal water flow directly toward the cooling coil 14, creating a circular flow above and below the partition plate 21. This allows for efficient stirring without waste, making it suitable for liquid coolant 25 at or below -50°C.

[0028] The cooling coil 14, compressor 43, condenser 45, expansion valve 15, and cooling coil 14 form a refrigeration cycle, and it is preferable to interpose a heat exchanger 41 somewhere along the cycle. For example, the heat exchanger 41 is arranged so that heat exchange occurs between the refrigerant pipe 5 through which low-temperature, low-pressure refrigerant gas returning from the freezing chamber 2 (cooling coil 14) flows and the refrigerant pipe 5a through which high-temperature, high-pressure refrigerant liquid flows toward the expansion valve 15 via the compressor 43 and condenser 45 (see FIG. 8). By providing the heat exchanger 41 in this manner, it is possible to lower the temperature of the refrigerant, and therefore the temperature of the liquid coolant 25, to a greater extent than before. Specifically, it is possible to lower the temperature of the liquid coolant 25 to -50°C or below.

[0029] By providing the heat exchanger 41 in this way, it is possible to lower the temperature of the refrigerant, and in turn to lower the temperature of the liquid coolant 25 to a greater extent than before. Specifically, it is possible to lower the temperature of the liquid coolant 25 to -50°C or lower.

[0030] It is preferable to attach an inverter to the motor 12. This stabilizes the rotation of the motor 12 and makes it easy to adjust the rotation speed, in other words, the speed of the liquid flow toward the frozen items on the partition plate 21.

[0031] An operation panel 19 equipped with a main switch, a coolant temperature display, etc. is installed on the front side of the machine room 1, and pulleys 16, 17 and belt 18 exposed on the sides of the machine room 1 and freezer room 2, as well as piping and expansion valve 15, are covered with a safety cover 20. Note that reference numeral 6 in Figure 1 denotes a drain pan.

[0032] In the liquid freezer of the present invention, when refrigerator 11 is operated, refrigerant gas is compressed by compressor 43 to become high-temperature, high-pressure refrigerant gas, and the high-temperature, high-pressure refrigerant liquid is cooled and condensed in condenser 45. The pressure and flow rate are adjusted by expansion valve 15 and the liquid is sent to cooling coil 14, which is drawn from the top of freezing tank 3 to the lower half. Thus, liquid coolant 25 is cooled by cooling coil 14 and maintained at a predetermined temperature while being stirred and circulated by the action of the stirring blades. The frozen products are packed in baskets and placed on partition plate 21, and exposed to the strong flow of liquid coolant on partition plate 21 caused by stirring blade 13, allowing them to be frozen evenly in a short period of time.

[0033] The refrigerant gas used in the refrigerator 11 of the present invention is a non-fluorocarbon gas, preferably a natural refrigerant gas. Natural refrigerant gases do not deplete the ozone layer, have a low global warming potential, and are highly energy efficient, and therefore have recently been put to practical use in the commercial field.

[0034] The peripheral wall surface of the freezing tank 3 is typically made of stainless steel. In one embodiment, the freezing tank 3 is composed of three metal plates: an outer plate, an intermediate plate, and an inner plate. The space between the outer plate and the intermediate plate is an insulating layer 8 filled with insulating material 7, and the space between the intermediate plate and the inner plate is an ice pack layer 9 filled with and frozen as a gel ice pack. Typically, the bottom surface connected to the peripheral wall surface also has a two-layer structure consisting of the same ice pack layer 9 as the peripheral wall surface and the insulating layer 8. In one example, the thickness of the insulating layer 8 is 50 to 100 mm, and the thickness of the ice pack layer 9 is 10 to 20 mm. The reason for limiting the thickness of the ice pack layer 9 to 10 to 20 mm is that a thickness of 10 mm or less does not provide sufficient cooling effect, while a thickness of 20 mm or more does not provide a significant increase in cooling effect compared to a thickness less than 10 mm, resulting in waste and increasing the overall weight and making the ice pack difficult to handle.

[0035] The cooling liquid 25 placed in the freezing tank 3 in a predetermined amount is, for example, an antifreeze liquid such as ethanol-based ethanol brine. Since the liquid freezer according to the present invention is designed to freeze cooling liquid at temperatures of approximately -35°C to -50°C, the ice pack must be capable of keeping the cooling liquid at that temperature. To meet this requirement, the present invention uses, for example, normal paraffin gelled by adding a gelling agent. In this case, it is preferable to select a gelling agent from among conventionally known ice pack gelling agents that allows for easy filling of the gel ice pack, as described below. For example, a high molecular weight thermoplastic polymer or styrene-butadiene rubber can be used as the gelling agent. Alternatively, a vegetable spray agent can be used.

[0036] The gel ice pack is heated to, for example, 80°C to become a thin liquid, and then poured directly into the space between the middle plate and the inner plate. Because the gel ice pack is in liquid form at this stage, it fills evenly from the peripheral wall to the bottom, and then turns into a gel as the temperature drops. After the gel ice pack is filled, the top surface between the middle plate and the inner plate is sealed. This sealing of the top surfaces of the middle plate and the inner plate can be done at the same time as sealing the insulation layer 8. Then, after filling the freezer tank 3 with a predetermined amount of coolant, the freezer 11 is operated, and the gel ice pack freezes to form the ice pack layer 9, which then keeps the coolant cold. [Example]

[0037] As an example of a liquid freezer according to the present invention, one having the following specifications was manufactured. The dimensions of the freezer tank 3 are width 500 mm, depth 450 mm, and height 450 mm (effective internal volume :75L). The refrigerator 11 has a rated voltage of three-phase 200V, a rated frequency of 60Hz, and an electric capacity of 750 W's air-cooled refrigerator. Stirring motor 12: rated voltage: three-phase 200V, rated frequency: 60Hz, electric capacity: It is a 200W indoor, totally enclosed, external fan type. The coolant is food-grade alcohol with an alcohol content of 88% (melting point -80°C).

[0038] When the liquid freezer with the above specifications was started, the temperature of the cooling liquid dropped to -50°C after 8 hours. The flow rate on the partition plate 21 at that time was 150 m / min. After that, 8 kg of packaged fruit juice was placed in a basket on the partition plate 21, and it was completely frozen after about 100 minutes. The reason for such a short freezing time was that the cooling liquid, which comes into contact with the frozen product, was sufficiently agitated.

[0039] Incidentally, if the same frozen product as above were to be frozen in a liquid freezer currently on the market, it would take at least three hours, which shows just how excellent the quick-freezing function of the liquid freezer of the present invention is. The liquid freezer of the present invention freezes the water in food at such low temperatures in a short time, preventing cell destruction in the food, significantly reducing the amount of dripping during thawing, and preserving the freshness and flavor of the food. [Industrial Applicability]

[0040] The liquid freezer of the present invention is as described above, and has a simple configuration. It satisfactorily seals the liquid inside and outside the freezer chamber around the rotating shaft of the horizontally arranged agitator blade. Even when the liquid coolant temperature is set to around -50°C, by changing the flow direction of the liquid coolant above and below the partition plate, it is possible to supply the liquid coolant at a sufficient flow rate to the frozen products placed above the partition plate, thereby achieving the effect of efficient quick freezing, and therefore has great industrial applicability. [Explanation of symbols]

[0041] 1 Machine room 2 Freezer 3 Freezer 4 Sealing lid 5,5a Refrigerant piping 11 Refrigeration machine 12 motors 13 Stirring blade 14 Cooling coil 15 Expansion valve 21 Partition 41 Heat exchanger

Claims

1. A liquid freezer having a freezing compartment and a machine compartment, a partition plate on which the commodity to be frozen is placed is disposed in the middle of the freezing tank of the freezing compartment; an agitator blade is installed through the wall of the freezing tank so as to face a cooling coil disposed below the partition plate; liquid passage spaces for the cooling liquid are provided between the agitator blade side end of the partition plate and the inner surface of the freezing tank, and between the end of the partition plate opposite to the agitator blade side and the inner surface of the freezing tank, respectively; a liquid flow generated below the partition plate by the rotation of the agitator blade flows from the liquid passage space on the opposite end side of the partition plate to the upper side of the partition plate, flows in the opposite direction to the liquid flow below the partition plate, and flows from the liquid passage space on the agitator blade side end of the partition plate to the underside of the partition plate to circulate.

2. 2. The liquid freezer according to claim 1, wherein each of the liquid-permeable spaces is sealed with a wire mesh liquid-permeable material.

3. 2. The liquid freezer according to claim 1, wherein the machine room is equipped with a refrigerator including a compressor and a condenser, a refrigerant pipe extending from the refrigerator and connected to the cooling coil via an expansion valve, and a motor for rotating the agitator blade.

4. 4. The liquid freezer according to claim 3, wherein a refrigeration cycle is formed by the cooling coil, the compressor, the condenser, the expansion valve and the cooling coil, and a heat exchanger is provided midway through the cycle.

5. 5. The liquid freezer according to claim 4, wherein the heat exchanger is disposed so that heat exchange occurs between the refrigerant pipe through which low-temperature, low-pressure refrigerant gas returning from the freezing compartment flows and the refrigerant pipe through which high-temperature, high-pressure refrigerant liquid flowing toward the expansion valve via the compressor and the condenser.

6. 2. The liquid freezer according to claim 1, wherein a bearing of the rotating shaft of the agitating blade on the freezing tank side is flanged, and a packing is sandwiched between the flange and the inner surface of the freezing compartment wall, and a bolt inserted from the inside of the wall is tightened with a nut, thereby achieving a liquid seal on the freezing tank side of the rotating shaft.

7. 7. The liquid freezer of claim 6, wherein a stuffing box having a male thread on its outer periphery and containing a gland packing is fixed to the outer surface of the freezing chamber, and a packing gland presses against the gland packing by fastening an outer cylinder having a female thread on its inner periphery to the stuffing box, thereby achieving a liquid seal on the outer surface side of the freezing chamber of the rotating shaft of the agitating blade.

8. 2. The liquid freezer according to claim 1, wherein the walls and bottom of the freezer compartment are made up of three plates: an outer plate, an intermediate plate, and an inner plate; the space between the outer plate and the intermediate plate is an insulating layer filled with insulating material; and the space between the intermediate plate and the inner plate is an ice pack layer filled with ice packs.

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