Liquid freezer

Abstract

To provide a liquid freezer that can suppress increase in temperature of liquid in a refrigeration tank for a long period even when operation of a refrigeration machine is stopped when a freezing work is not conducted and can significantly shorten the time required for returning the temperature of liquid to the original temperature, thereby eliminating unnecessary operation of the refrigeration machine and electricity cost thereof.SOLUTION: Disclosed is a liquid freezer for freezing packaged articles by immersing the articles into cooling liquid in a refrigeration tank, comprises: a refrigeration tank 3 including a circumferential wall surface and a bottom surface which are constituted of three stainless steel plates, an outside plate 5, an intermediate plate 6, and an inside plate 7; a heat insulation material layer 8 configured by a heat insulation material filling a space between the outside plate 5 and the intermediate plate 6; and a cold insulator layer 9 configured by a cold insulator directly filling a space between the intermediate plate 6 and the inside plate 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid freezer, and more particularly to a liquid freezer equipped with a refrigeration tank that exhibits energy-saving effects. [Background technology]

[0002] Many frozen products are processed using the air blast method, which involves freezing in cold air. This method is especially common in mass-produced food processing plants. Recently, however, liquid freezers, which freeze products in a brine solution (antifreeze), have become increasingly popular due to the need for rapid freezing. Liquid freezers use a compressor to compress a refrigerant gas, condensing it into a liquid, which is then supplied to cooling pipes inside the freezer, cooling the brine solution (antifreeze) inside the freezer. Liquid freezers have the advantage of bringing products into direct contact with the low-temperature brine solution, resulting in a higher surface heat transfer coefficient than air blast freezers, shortening the freezing time.

[0003] The freezing tank of a liquid freezer is typically made of a double stainless steel frame with an insulated wall filled with an insulating material such as urethane foam, giving it an insulating and cold-retaining function (see JP-B No. 7-28710, JP Patent No. 2575321, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 7-28710 [Patent Document 2] Patent No. 2575321 Summary of the Invention [Problem to be solved by the invention]

[0005] In a typical liquid freezer, the brine is kept at around -30°C to -40°C, but once the compressor is stopped, the liquid temperature rises rapidly to around -10°C, and it takes several hours to lower it back down to -30°C to -40°C, meaning that during this time freezing operations cannot be performed.To eliminate this wasted time and enable operations to begin immediately at any time, the current practice is to operate the compressor continuously 24 hours a day to maintain the liquid temperature in the freezer tank.

[0006] As mentioned above, the freezer tank has an insulating cold-keeping effect by having its surrounding walls insulated with insulating material such as urethane foam, and this is sufficient if the compressor is operated continuously 24 hours a day to maintain the liquid temperature inside the freezer tank. However, running the compressor continuously 24 hours a day increases the electricity bill, and since the freezing process of putting items in and taking them out of the freezer tank is not carried out continuously 24 hours a day, there is waste.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a liquid freezer that can suppress an increase in the liquid temperature in the freezing tank for a long period of time even when the freezing machine is stopped when no freezing operation is being performed, and can significantly shorten the time required for the liquid temperature to return to its original level, thereby eliminating idle operation of the freezing machine and reducing electricity costs. [Means for solving the problem]

[0008] The invention described in claim 1 to solve the above problem is a liquid freezer that freezes packaged items by immersing them in a cooling liquid in a freezing tank, The peripheral wall surface of the freezing tank is 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. This liquid freezer is characterized by the above.

[0009] In one embodiment, the bottom surface of the freezing tank, which is continuous with the peripheral wall surface, is made up of three plates: an outer plate, an intermediate plate, and an inner plate, and 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.

[0010] In one embodiment, the ice pack layer has a thickness of 10 to 20 mm.

[0011] In one embodiment, the ice pack layer is formed by directly injecting a gel-like ice pack that has been heated and liquefied between the intermediate plate and the inner plate, and then freezing it with the cooling liquid.

[0012] In one embodiment, the gel ice pack is made by gelling normal paraffin.

[0013] In one embodiment, the cooling of the cooling liquid in the freezing tank is performed by a refrigerator including a compressor. Alternatively, the cooling of the cooling liquid in the freezing tank is performed by a Stirling refrigerator. [Effects of the Invention]

[0014] The liquid freezer of the present invention is as described above, and even if the freezer is stopped when freezing is not being performed, the wall surface of the freezer tank, which is made up of a heat insulating material layer and a cold pack layer, acts to prevent the temperature of the liquid in the freezer tank from rising for a long period of time, and the time required to restore the liquid temperature to its original level can be significantly reduced, which has the effect of eliminating idle operation of the freezer and reducing electricity costs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a partially cutaway front view showing one embodiment of a liquid freezer according to the present invention. FIG. [Figure 2] 1 is a side view showing an embodiment of a liquid freezer according to the present invention. FIG. [Figure 3] 1 is a plan view showing an embodiment of a liquid freezer according to the present invention. FIG. [Figure 4]FIG. 2 is an enlarged view of a broken portion in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail with reference to the accompanying drawings. The liquid freezer according to the present invention is a device that freezes packaged items by immersing them in a cooling liquid in a freezing tank, and, as shown in the example shown, is composed of a machine chamber 1, a freezing chamber 2 having a freezing tank 3 disposed above it, and a sealing lid 4 that opens and closes the top of the freezing chamber 2.

[0017] The peripheral wall of the freezer tank 3 is typically made of three stainless steel metal plates: an outer plate 5, an intermediate plate 6, and an inner plate 7. The space between the outer plate 5 and the intermediate plate 6 is an insulating layer 8 filled with insulating material, and the space between the intermediate plate 6 and the inner plate 7 is an ice pack layer 9 filled with and frozen with gel-like ice packs. Typically, the bottom surface adjacent to the peripheral wall also has a two-layer structure consisting of the same ice pack layer 9 as the peripheral wall 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.

[0018] The cooling liquid to be 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 a cooling liquid at 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 polymer of a thermoplastic resin or styrene-butadiene rubber can be used as the gelling agent. Alternatively, a vegetable spray agent can be used.

[0019] The gel ice pack is heated, for example, to 80°C to turn it into a thin liquid, and then poured directly into the space between the intermediate plate 6 and the inner plate 7. 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 intermediate plate 6 and the inner plate 7 is sealed. This sealing of the top surfaces of the intermediate plate 6 and the inner plate 7 can be performed 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.

[0020] Inside the machine room 1 are disposed a refrigerator 11 including a compressor, and a motor 12 that rotates and drives a propeller 13 to agitate the coolant in the freezing tank 3. A cooling coil 14 extending from the refrigerator 11 is drawn into the lower half of the freezing tank 3 from the top of the freezing chamber 2 via an expansion valve 15 and arranged in a serpentine shape, with a porous partition plate 21 covering the top of the coil for placing items to be frozen. The rotational output of the motor 12 is transmitted to the propeller 13 via a pulley 16 fixed to the drive shaft and a belt 18 wound around a pulley 17 fixed to the rotating shaft of the propeller 13, and the inside of the freezing tank 3 is agitated by the rotation of the propeller 13.

[0021] 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 a safety cover 20 is placed over the pulleys 16, 17 and belt 18, as well as the piping, exposed on the sides of the machine room 1 and the freezer room 2.

[0022] In the liquid freezer of the present invention, the refrigerant gas is compressed when the refrigerator 11 is operated, and the condensed liquid is reduced in pressure through the expansion valve 15 and sent to the cooling coil 14, which is drawn from the top of the freezing chamber 4 into the lower half of the freezing tank 3. In this way, the cooling liquid in the freezing tank 3 is cooled and maintained at a predetermined temperature. Items to be frozen can be frozen in a short period of time by placing them in a packaged state on the porous partition plate 21. At this time, the cooling liquid in the freezing tank 3 can be stirred by the propeller 13 to freeze evenly.

[0023] The refrigerant gas used in the refrigerator 11 of the present invention is a non-fluorocarbon gas, and preferably a natural refrigerant gas. Natural refrigerant gas does not destroy the ozone layer, has a low global warming potential, and is highly energy efficient, and therefore has recently been put to practical use in the commercial field.

[0024] Furthermore, a Stirling refrigerator can be used instead of the compression refrigerator 11. A Stirling refrigerator is a refrigerator that applies the theory of the long-known Stirling engine, which converts temperature differences into energy, and various types are commercially available. A Stirling refrigerator operates with low power consumption of about 800 W and mainly uses helium gas as the working gas, so it can contribute to decarbonization (elimination of fluorocarbons).

[0025] The Stirling refrigerator is placed with its head side facing downwards, facing the coolant 2. The head of a Stirling refrigerator is covered with a head cap because it reaches a low temperature of about -110°C, but in the present invention, a heat diffusion plate is attached via a metal head cover that holds the head cap. The heat diffusion plate is used to widely and quickly transfer the cold from the head to the coolant, and is shaped with appropriate fins to maximize its surface area. [Industrial Applicability]

[0026] The liquid freezer of the present invention is as described above, and even if the freezer is stopped when freezing operations are not being performed, the wall surface of the freezer tank, which is made up of a heat insulating material layer and a cold pack layer, acts to prevent the temperature of the liquid in the freezer tank from dropping for a long period of time, and the time required to restore the liquid temperature to its original level can be significantly reduced, which has the effect of eliminating unnecessary operation of the freezer and reducing electricity costs, and has great industrial applicability. [Explanation of symbols]

[0027] 1 Main unit case 2 Freezer 3 Freezer 4 Sealing lid 5 Outer plate 6 Intermediate plate 7 Inner plate 8. Insulation Layer 9 Ice pack layer 11 Refrigeration machine 12 motors 13 Propeller 14 Cooling pipe 15 Expansion valve 19 Operation Panel 20 Safety Cover 21 Porous partition board

Claims

1. A liquid freezer that freezes packaged items by immersing them in a cooling liquid in a freezing tank, The peripheral wall surface of the freezing tank is composed of three plates: an outer plate, an intermediate plate, and an inner plate; an insulating layer filled with insulating material is formed between the outer plate and the intermediate plate; and an ice pack layer filled with ice packs is formed between the intermediate plate and the inner plate.

2. 2. The liquid freezer according to claim 1, wherein the bottom surface of the freezing tank, which is continuous with the peripheral wall surface, is made up of three plates: an outer plate, an intermediate plate, and an inner plate, and the space between the outer plate and the intermediate plate is an insulating material 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.

3. 3. The liquid freezer according to claim 1, wherein the ice pack layer has a thickness of 10 to 20 mm.

4. 3. The liquid freezer according to claim 1, wherein the ice pack layer is formed by directly injecting a gel-like ice pack, which has been heated and liquefied, between the intermediate plate and the inner plate, and then freezing the gel-like ice pack with the cooling liquid.

5. 5. The liquid freezer according to claim 4, wherein the gel-like ice pack is made by gelling normal paraffin.

6. 3. The liquid freezer according to claim 1, wherein the cooling of the cooling liquid in the freezing tank is performed by a refrigerator including a compressor.

7. 3. The liquid freezer according to claim 1, wherein the cooling of the cooling liquid in the freezing tank is performed by a Stirling refrigerator.

Images