JP7223663B2 - Granular freezing apparatus and method - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies Monthly magazine "Food and Development" published on December 1, 2018 by UBM Japan Co., Ltd., Vol. 53, No. 12

TECHNICAL FIELD The present invention relates to a granular freezing apparatus and method, and more particularly, to an apparatus and method for freezing liquid raw materials into granular form using cryogenic liquefied gas.

In the food-related industrial field, as a method or apparatus for freezing liquid raw materials using low-temperature liquefied gas such as liquid nitrogen, raw materials are continuously dripped into a gutter-shaped channel through which low-temperature liquefied gas is flowed. It is known to drip and cool to produce a granular frozen product. In particular, to prevent the droplets of the dropped raw material from adhering to each other, the gutter-shaped channel is inclined to increase the flow rate of the low-temperature liquefied gas, and the width of the channel is gradually increased toward the end. A granular freezing apparatus has been proposed in which a plurality of partition plates are provided in the channel so as to secure the depth of the low-temperature liquefied gas by narrowing it, and to correspond between the plurality of drip nozzles arranged in parallel (for example, patent Reference 1).

In addition, a structure is known in which an inclined channel is divided into upper and lower parts, and the low-temperature liquefied gas flows from the upper part of the channel to the lower part, thereby lengthening the channel and lengthening the freezing time of the raw material. (See Patent Document 2, for example).

Japanese Patent No. 6327721 JP-A-7-8240

By the way, in an apparatus for obtaining frozen granules by dripping a raw material into a flow path through which a low-temperature liquefied gas is flowed, it is necessary to make the flow path long enough to obtain freezing time so that the dropped raw material can be frozen to the core. There is Therefore, if the flow path is formed in a straight line, the necessary flow path becomes too long, resulting in an increase in the size of the device.

On the other hand, in the apparatus described in Patent Document 1, a flow path having a length that freezes the surface of the dropped raw material is adopted, and the raw material whose surface is frozen after passing through the flow path is transferred to the terminal end of the flow path. After storing it in a basket, it is immersed in the low-temperature liquefied gas together with the basket again to freeze it to the core.

However, there is a possibility that these raw materials stick to each other and form lumps due to the step of storing the raw materials whose surface is frozen only in one place. In addition, since there is a blank period in the production of the frozen granules while the raw materials are stored in the basket, the frozen granules cannot be produced continuously.

In addition, in the configuration of Patent Document 2, the flow of the low-temperature liquefied gas is disturbed at the point where it falls from the upper stage to the lower stage of the flow path, so the raw materials whose surfaces are frozen collide one after another at that point to form lumps. In addition, there is a problem that the mass enlarges and clogs the flow path.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a granular freezing apparatus and method capable of stably and continuously producing granular frozen raw materials while preventing raw materials dripped into low-temperature liquefied gas from clumping during freezing. and

In order to achieve the above object, the granular freezing apparatus of the present invention includes a gutter-shaped channel for flowing a low-temperature liquefied gas, a low-temperature liquefied gas delivery unit for delivering the low-temperature liquefied gas to the channel, and a raw material to the channel. In a granular freezing apparatus comprising a raw material dropping unit that continuously drops and a solid-liquid separation unit that separates the frozen material of the raw material from the low-temperature liquefied gas, the channel has a narrow section with a narrow channel width upstream. wherein the narrow section and the wide section have the same depth, the raw material dropping section is arranged to drop the raw material upstream of the narrow section, and the low temperature liquefied gas delivery section is a storage tank for storing the low-temperature liquefied gas; and a pump for pumping up the low-temperature liquefied gas from the storage tank and sending the low-temperature liquefied gas to the flow path, wherein the flow path receives the low-temperature liquefied gas from the pump. , a U-shaped folded portion, and a terminal portion for flowing the low-temperature liquefied gas to the solid-liquid separation portion, and the low-temperature liquefied gas from which the frozen matter is separated by the solid-liquid separation portion is returned to the storage tank. and the end portion is arranged so as to be located directly above the storage tank.

Furthermore, the flow path is characterized in that the upstream side of the folded portion is formed in a straight line, and that the flow path is arranged horizontally.
It is characterized by having a length of 1,000 to 10,000 mm and a width of 50 mm or more, and a width ratio of the narrow section to the wide section of 1.1 to 2.0 times. Further, the storage tank and the liquid pump are covered with an outer tank, and the starting end and the terminal end are arranged so as to be inserted into openings provided in the outer tank.

A granular freezing method for freezing a raw material into granules by the granular freezing apparatus of the present invention includes a low-temperature liquefied gas sending step of sending a low-temperature liquefied gas from the starting end of the flow path, and a raw material into the flow path through which the low-temperature liquefied gas flows. a raw material dropping step of dropping the raw material, a surface freezing step of freezing the surface of the raw material dropped into the flow channel, a core freezing step of freezing the raw material with the frozen surface up to the core, and a raw material at the end of the flow channel and a low-temperature liquefied gas circulation step of sending the low-temperature liquefied gas from which the frozen matter has been separated to the starting end of the flow path.

According to the granular freezing apparatus of the present invention, since the channel for flowing the low-temperature liquefied gas has a narrow section, the liquid level of the low-temperature liquefied gas flowing through the section rises and the depth of the liquid increases, so the liquid is dripped. The surface of the dropped raw material can be frozen without causing the raw material to adhere to the bottom surface of the channel. In addition, since the width of the flow path is widened in the wide section downstream from the narrow section, the raw materials can be flowed while maintaining a sufficient interval, so that the raw materials whose surfaces are frozen collide with each other and agglomerate. It is possible to stably obtain a granular frozen product in which the dropped raw material is frozen up to the core.

In addition, since the size of the flow path can be made compact by forming the flow path in a U-shape by providing a folded portion instead of a straight line, an increase in the size of the apparatus can be suppressed while ensuring a sufficient freezing distance. In addition, the low-temperature liquefied gas can be supplied to the flow path by the low-temperature liquefied gas delivery unit, and the low-temperature liquefied gas that has flowed through the flow path can be recovered in the storage tank and flowed back into the flow path using the pump as a driving force. As long as the cryogenic liquefied gas is supplied from the cryogenic liquefied gas supply source, the cryogenic liquefied gas can be continuously flowed through the flow path.

Furthermore, according to the granular freezing method using the granular freezing apparatus of the present invention, the low-temperature liquefied gas is kept flowing through the channel by the low-temperature liquefied gas delivery step and the low-temperature liquefied gas circulation step, and the raw material dropping step. , the surface freezing process, the core freezing process, the solid-liquid separation process, and the frozen material recovery process, the raw material dropped into the flow path becomes granular frozen material at the end of the flow path. Since the raw material is separated from the low-temperature liquefied gas and recovered, continuous production of the granular frozen material can be performed without stagnation by continuing to drop the raw material into the flow path.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view schematically showing one embodiment of a granular freezing apparatus capable of implementing the granular freezing method of the present invention; It is also a plan view.

As shown in FIGS. 1 and 2, the granular freezing apparatus 11 includes a gutter-shaped channel 12 for flowing a low-temperature liquefied gas represented by liquid nitrogen. A gas delivery unit 13, a raw material dropping unit 14 that continuously drops raw materials into the flow channel 12, and a solid-liquid separation unit that separates the frozen material dropped into the flow channel 12 by the raw material dropping unit 14 from the low-temperature liquefied gas. 15 and a frozen material recovery unit 16 that recovers the frozen material separated by the solid-liquid separation unit 15 . Further, the flow path 12 is housed inside an external air blocking tank 17 having an upper lid 17a.

The flow path 12 is arranged horizontally and has a starting end 12a at which the flow of the low temperature liquefied gas begins, a terminal end 12b at which the flow of the low temperature liquefied gas ends, and from the starting end 12a to the terminal end 12b. A folded portion 12c that folds back into a U shape is provided in the middle, and the portions from the starting end portion 12a to the folded portion 12c and from the folded portion 12c to the terminal end portion 12b are formed linearly.

Further, the channel 12 has a narrow section 12d with a narrow channel width upstream, and a wide section 12e with a wider channel width than the narrow section 12d downstream of the narrow section 12d. Here, the length of the narrow section 12d is such that the surface of the dropped raw material can be frozen in the flow of the low-temperature liquefied gas. The width of the wide section 12e is set to be 1.1 to 2.0 times, preferably 1.3 to 1.5 times the width of the narrow section 12d. .

The overall dimensions of the flow path 12 can be changed according to the ease with which the raw material to be dropped is frozen and the number of droplets dropped by the raw material dropping section 14 at one time, but the depth is within the range of 5 to 100 mm. , the length is in the range of 1,000 to 10,000 mm, and the width is preferably 50 mm or more.

In addition, depending on the size of the droplet of the dropped material, not only the freezing time but also the ease with which the core of the droplet freezes on the surface of the droplet changes. It may also be desirable to vary the ratio of the narrow section 12d to the core frozen wide section 12e. For example, if the droplets of the dropped raw material are small, the freezing time will be short, and if the surface freezes, the core will also freeze immediately. It is desirable to keep it short. In addition, when the size of the droplet of the raw material to be dropped is large, the freezing time becomes long, and even if the surface freezes, the core does not freeze immediately. It is desirable to take longer than the section 12d.

The raw material dropping unit 14 is arranged so as to drop the raw material upstream of the narrow section 12d, and has a plurality of dropping nozzles (not shown) so that a plurality of droplets can be dropped into the channel 12 at the same time. is configured to

The outside air blocking tank 17 has a heat insulating structure (not shown) consisting of an air phase in which air is enclosed in the wall surface and a heat insulating phase formed by a heat insulating material, so temperature changes in the flow path 12 are suppressed. As a result, evaporation of the low-temperature liquefied gas flowing through the flow path 12 can be suppressed. A drip hole 17b is provided in an upper lid 17a of the outside air blocking tank 17 at a position directly below the raw material dripping portion 14 so that the dripping of the raw material into the flow path 12 is not hindered.

The low-temperature liquefied gas delivery unit 13 has a vacuum-insulated bottom surface and wall surface, and has an open upper surface. Liquid pump 19, low temperature liquefied gas supply source 20 with solenoid valve 20a for supplying low temperature liquefied gas to storage tank 18, liquid level sensor 21 for detecting the height of liquid level in storage tank 18, liquid level A liquid level control unit 22 is provided for controlling the solenoid valve 20a to keep the level of the liquid level in the storage tank 18 constant by opening and closing the solenoid valve 20a according to the detection information of the sensor 21. FIG.

The liquid pump 19 is a pump having a cylindrical case 19b under a motor 19a which is a driving force, and a vertical screw (not shown) arranged inside the case 19b is rotated by the motor 19a. It is configured so that the liquid can be pumped up by An inflow port 19c for inflowing the low-temperature liquefied gas is provided in the lower part of the case 19b and is arranged so as to be inserted into the storage tank 18 . Further, a discharge port 19d for discharging the low-temperature liquefied gas pumped into the case 19b by the screw is provided on the upper part of the case 19b. Therefore, the liquid pump 19 can pump up the low-temperature liquefied gas in the storage tank 18 from the inflow port 19c and send it out from the discharge port 19d.

The storage tank 18 and the case 19b of the liquid pump 19 are covered with an outer tank 23, which is a housing capable of keeping the inside cool, so that the temperature of the low-temperature liquefied gas in the storage tank 18 and the liquid pump 19 can be maintained. is configured to An opening 23a is provided in the upper part of one side surface of the outer tank 23, and a discharge port 23b is provided in the lower part. The opening 23a is connected to the external air blocking tank 17, and is arranged so that the starting end 12a and the terminal end 12b of the flow path 12 are inserted from the external air blocking tank 17 into the external tank 23 through the opening 23a. It is Further, outside the discharge port 23b, a frozen product recovery unit 16, which is a housing with an open top, is arranged adjacently.

In the opening 23 a , the starting end 12 a of the flow path 12 is positioned directly below the discharge port 19 d of the liquid pump 19 , and the terminal end 12 b of the flow path 12 is positioned directly above the storage tank 18 . A solid-liquid separator 15 consisting of a mesh plate 15a is attached to the end of the terminal portion 12b. The mesh plate 15a of the solid-liquid separation unit 15 is vertically installed so that the upper part blocks the traveling direction of the flow path 12, and the lower part is inclined to extend to the end of the discharge port 23b so as to avoid the storage tank 18, and to the outside. It is arranged so as to protrude outside the tank 23 and reach above the frozen material recovery section 16 .

Since the solid-liquid separation unit 15 is the mesh plate 15a, the low-temperature liquefied gas that has flowed to the end portion 12b of the flow path 12 passes through the mesh plate 15a and flows down to the storage tank 18 located below. The granular frozen material of the raw material that flows along with the low-temperature liquefied gas is received by the vertical portion of the mesh plate 15a, separated from the low-temperature liquefied gas, rolled on the inclined portion, and guided to the discharge port 23b, where the frozen material is recovered. Collected in the unit 16 .

Therefore, when the low-temperature liquefied gas is discharged from the discharge port 19d of the liquid pump 19, the discharged low-temperature liquefied gas is sent to the starting end portion 12a of the flow path 12, flows through the flow path 12, and ends at the end portion 12b. , it passes through the mesh plate 15a of the solid-liquid separation section 15 from the end portion 12b and is returned to the storage tank 18. The low-temperature liquefied gas returned to the storage tank 18 is sent out to the flow path 12 again by the pump 19 .

Further, the liquid level controller 22 opens the solenoid valve 20a of the low temperature liquefied gas supply source 20 when the liquid level sensor 21 detects that the liquid level of the storage tank 18 has fallen below the set lower limit. , and when it is detected that the height of the liquid surface has returned to the set upper limit value, a command is issued to close the electromagnetic valve 20a. Therefore, the low-temperature liquefied gas in the storage tank 18 is kept at a predetermined level by the liquid level control section 22 .

A granular freezing method using the granular freezing apparatus 11 described above will be described below. First, in the low-temperature liquefied gas delivery unit 13, the liquid level control unit 22 supplies the low-temperature liquefied gas from the low-temperature liquefied gas supply source 20 to the storage tank 18 until the liquid level reaches a predetermined level. is driven to pump up the low temperature liquefied gas from the storage tank 18 and deliver it to the starting end portion 12a of the flow path 12 so that the low temperature liquefied gas flows through the entire flow path 12 (low temperature liquefied gas delivery step).

After a sufficient amount of low-temperature liquefied gas has flowed through the flow path 12, the raw material is dropped from the raw material dropping section 14 (raw material dropping step). The dropped raw material is first immersed in the flow of the low-temperature liquefied gas in the narrow section 12d, thereby freezing the surface of the droplet, granulating it, and flowing it downstream (surface freezing step). After passing through the narrow section 12d, the raw material whose surface is frozen enters the wide section 12e, spreads in the width direction of the channel 12, and is frozen to the core (core freezing step). When the raw material frozen to the core reaches the end portion 12b of the flow path 12, it is separated from the low-temperature liquefied gas by the mesh plate 15a of the solid-liquid separation section 15 (solid-liquid separation step), and is guided to the mesh plate 15a. and sent to the frozen material recovery unit 16 to be recovered as granular frozen material (frozen material recovery step). On the other hand, the low-temperature liquefied gas from which the frozen matter has been separated is returned to the storage tank 18 and sent again to the starting end 12a of the flow path 12 by the liquid pump 19 (low-temperature liquefied gas circulation process).

In the granular freezing apparatus 11 of the present invention, the channel 12 is provided with the narrow section 12d, so that the liquid level of the low-temperature liquefied gas flowing through the section rises by the narrowness of the channel width. Since the depth is increased, the droplets of the raw material dropped from the raw material dropping part 14 can be frozen and granulated on the surface without adhering to the bottom surface of the channel 12, and placed on the flow of the low-temperature liquefied gas.

Further, if the width of the flow path downstream of the narrow section 12d remains narrow, the grains of the raw material that are frozen only on the surface in the narrow section 12d may cluster together and collide with each other to form agglomerates. A wide section 12e having a wider flow path is provided downstream of 12d, so that grains of raw material frozen only on the surface can be flowed at sufficient intervals.

That is, in the granular freezing apparatus 11 of the present invention, the narrow section 12d is provided in the flow path 12, and the wide section 12e is downstream of the narrow section 12d. While flowing into the low-temperature liquefied gas, it is possible to prevent the material from colliding with each other in the flow and forming agglomerates, so that the dropped raw material can be frozen to the core while remaining granular, and the raw material can be frozen. A granular frozen product can be stably obtained.

In addition, since the flow path 12 is substantially horizontal and has almost no height difference, the height for pumping the low-temperature liquefied gas from the storage tank 18 can be kept low. It can be reduced more than if there is a difference.

In addition, the size of the flow path 12 can be made compact by forming the flow path 12 in a U-shape by providing the folded portion 12c instead of in a simple linear shape, so that the size of the apparatus can be suppressed while securing a sufficient freezing distance. .

In addition, the low-temperature liquefied gas is supplied to the flow path 12 by the low-temperature liquefied gas delivery unit 13, and the low-temperature liquefied gas that has flowed to the flow path 12 is recovered in the storage tank 18. Therefore, as long as the low temperature liquefied gas is supplied from the low temperature liquefied gas supply source 20 , the low temperature liquefied gas can be continuously flowed through the flow path 12 .

Furthermore, by circulating the low-temperature liquefied gas between the storage tank 18 covered with the outer tank 23 and the channel 12 covered with the outside air blocking tank 17, the low-temperature liquefied gas can be made difficult to evaporate. It is possible to suppress the loss of low-temperature liquefied gas and reduce the amount used.

According to the granular freezing method of the present invention, the low-temperature liquefied gas is kept flowing through the channel 12 by the low-temperature liquefied gas delivery step and the low-temperature liquefied gas circulation step, and the raw material dropping step and the surface freezing step are performed. , the core portion freezing step, the solid-liquid separation step, and the frozen material recovery step, the raw material dropped into the flow path 12 becomes granular frozen material at the end portion 12b of the flow path 12, and is liquefied at a low temperature. Since the raw material is separated from the gas and recovered, continuous dripping of the raw material into the flow path 12 enables continuous production of the granular frozen material without stagnation.

In the present invention, raw materials to be frozen in granular form are mainly assumed to be those in the food field, but in addition to this, materials in the fields of materials and pharmaceuticals can also be used as targets for granular freezing. be. In addition to the raw material dropping section, by providing a raw material dropping section capable of dropping solid materials, the freezer can be applied not only to liquid raw materials but also to freezing solid materials such as cut fruits.

Moreover, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the invention. For example, in this embodiment, the channel has one U-shaped folded portion. It is not necessary to have one folded portion, and an odd number of U-shaped folded portions may be provided to form a shape that is folded multiple times.

DESCRIPTION OF SYMBOLS 11... Granular freezing apparatus 12... Flow path 12a... Starting end part 12b... Terminating part 12c... Folding part 12d... Narrow width section 12e... Wide width section 13... Low-temperature liquefied gas delivery part 14... Raw material dropping part , 15 Solid-liquid separation section 15a Mesh plate 16 Frozen matter recovery section 17 External air shielding tank 17a Top cover 17b Drip hole 18 Storage tank 19 Lifting pump 19a Motor 19b Case 19c Inlet 19d Discharge port 20 Low-temperature liquefied gas supply source 20a Solenoid valve 21 Liquid level sensor 22 Liquid level controller 23 Outer tank 23a Opening 23b …Vent

Claims (6)

A low-temperature liquefied gas delivery unit that supplies the low-temperature liquefied gas to the channel, a raw material dropping unit that continuously drops the raw material into the channel, and a frozen material of the raw material. A granular freezing device comprising a solid-liquid separation unit for separating from a low-temperature liquefied gas,
The flow path includes a narrow section having a narrow flow path width upstream, and a wide section having a wider flow path width than the narrow section downstream of the narrow section. The sections have the same depth, and the raw material dropping section is arranged to drop the raw material upstream of the narrow section,
The low-temperature liquefied gas delivery unit includes a storage tank for storing the low-temperature liquefied gas, and a pump for pumping up the low-temperature liquefied gas from the storage tank and sending it to the flow path,
The flow path includes a beginning portion for receiving the low-temperature liquefied gas from the liquid pump, a U-shaped folded portion, and a terminal portion for flowing the low-temperature liquefied gas to the solid-liquid separation portion. The low-temperature liquefied gas from which the frozen matter is separated is returned to the storage tank,
The granular freezing apparatus, wherein the end portion is positioned directly above the storage tank. 2. The granular freezing apparatus according to claim 1, wherein the channel is formed linearly on the upstream side of the folded portion. 3. The granular freezing apparatus according to claim 1, wherein said flow path is arranged horizontally. The overall dimensions of the channel are 5 to 100 mm in depth, 1,000 to 10,000 mm in length, and 50 mm or more in width, and the ratio of the channel width between the narrow section and the wide section is 1.1 to 1.1. 4. The granular freezing apparatus according to any one of claims 1 to 3, wherein the magnification is 2.0 times. The storage tank and the liquid pump are covered with an outer tank,
5. The granular freezing apparatus according to any one of claims 1 to 4, wherein said starting end and said terminal end are arranged so as to be inserted into an opening provided in said outer tank. A granular freezing method for freezing a raw material in granular form by the granular freezing apparatus according to any one of claims 1 to 5,
a low-temperature liquefied gas delivery step of delivering low-temperature liquefied gas from the starting end of the flow path;
a raw material dropping step of dropping a raw material into the channel through which the low-temperature liquefied gas is flowed;
a surface freezing step of freezing the surface of the raw material dropped into the channel;
A core portion freezing step of freezing the surface frozen raw material up to the core portion;
a solid-liquid separation step of separating the frozen material of the raw material from the low-temperature liquefied gas at the terminal end of the flow path;
and a low-temperature liquefied gas circulation step of sending the low-temperature liquefied gas from which the frozen matter has been separated to the beginning end of the flow path.

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