JPS6344609B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention moves a top-open container containing liquid at a constant speed under a discharge hole through which a constant flow of low-temperature liquefied gas is continuously flowing down, thereby depositing a predetermined amount into the container. The present invention relates to a method of adding low temperature liquefied gas. (Background of the invention) A method for quantitatively filling a container with low-temperature liquefied gas is
The above method, which uses inert low-temperature liquefied gas, is required in various industrial fields, but it is not a foaming liquid that contains carbon dioxide gas like beer, but a non-foaming liquid. Liquid contents (e.g. fruits pickled in syrup, fruit juice drinks, mandarin orange drinks with fruit particles,
It is a preferred method to use when packaging (and coffee beverages) using a hot filling method or the like. In other words, in the case of canned goods filled by hot filling method etc., when the temperature of the liquid inside the can decreases after the lid is rolled up and sealed, the inside of the can becomes negative pressure. Cans with thick body walls that do not dent even when exposed to water are used, but in recent years, cans with thin body walls have been used. A method of increasing the internal pressure of the can after the liquid in the can has cooled (at this time, the liquefied gas has become vaporized gas) by filling a predetermined amount of an inert gas in a liquefied state (for example, liquid nitrogen) that will not be replaced. is proposed. The present invention is a method used to achieve this objective. (Prior art and its problems) Many methods have been proposed for filling a container with an inert low-temperature liquefied gas (hereinafter simply referred to as "low-temperature liquefied gas" even though it is inert). For example, Japanese Patent Application Laid-Open No. 49-134855 discloses that after filling a can with a drinking liquid and sealing the lid with an elastic member through which a needle member can penetrate, a syringe needle is inserted from above the elastic member. An invention is disclosed in which an inert low temperature liquefied gas is injected through the hole of the injection needle. However, this invention is not suitable for commercial production because it requires the use of a can lid with a special structure and the injection rate of low-temperature liquefied gas is too slow. Furthermore, in Japanese Patent Application Laid-Open No. 56-4521, after dropping liquid nitrogen into a can that has already been filled with contents, before double-sealing the can lid to the can mouth, nitrogen gas is applied from the outside of the can lid and can mouth. A method for manufacturing cans containing liquid nitrogen is disclosed, in which the cans are double-sealed and sealed while being sprayed with nitrogen. The method that this invention uses to add liquid nitrogen into the can is called the drip nozzle method. For example, a required amount of liquid nitrogen is dripped from the dripping nozzle into the can by opening the valve body of the dripping nozzle. A low-temperature liquefied gas dropping method using a similar dropping nozzle system is also disclosed in JP-A-56-109996. This dripping nozzle system opens and closes the valve body in order for the can to pass below the dripping nozzle, so it can be used on normal beverage canning production lines (more than 200 cans/min even at low speeds, and more than 1200 cans/min on high speed lines). ), the valve body should be opened and closed according to 3.3.
It is necessary to perform this at a speed of more than 3 times per second, and due to heat generation caused by repeated collisions and/or friction between the valve body and the valve seat, the low temperature liquefied gas vaporizes around the valve, and the low temperature liquefied gas and the vaporized gas Since it is dropped in a gas-liquid mixture with
Furthermore, since the dropping speed of the low-temperature liquefied gas dripped from the dripping nozzle is inevitably high, when it collides with the liquid in the can, a considerable amount of the gas is scattered outside the can or rapidly vaporized. As a result, the amount of low-temperature liquefied gas remaining in the can after sealing decreases (liquefied gas loss increases), and the variation in the amount of residual liquefied gas (can internal pressure for each can) also increases. I get used to it. There is a large variation in the amount of residual liquefied gas for each can, which means canned goods with insufficient internal pressure (canned goods that are difficult to distinguish from canned goods with poor sealing, and moreover, are prone to dents on the can body) and canned goods with excessive internal pressure (canned goods with poor seals or This is clearly undesirable because it means that cans with bulging deformation of the bottom etc. are likely to occur. Furthermore, with the drip nozzle method, the valve body moves once to the open and closed positions each time a can passes below the drip nozzle, making it suitable for can production at line speeds of 500 cans/min or higher. When used in a line, there is a problem with the ability to follow the opening and closing operations of the valve body (if used in such a high-speed line, the dropped low-temperature liquefied gas may not enter the can in a timely manner, or the metered drop may not be possible). (As a result, the loss of low-temperature liquefied gas becomes quite large, and the internal pressure of each can also varies greatly.) As mentioned above, the problem with the known drip nozzle method is that very low-temperature liquefied gas is dripped at high speed into a can that is moving at high speed, resulting in a mixture of gas and liquid dripping, and the possibility of splashing outside the can. There is a large loss of liquefied gas due to rapid vaporization, etc., and the internal pressure after sealing varies greatly from can to can, and it cannot be used in high-speed can manufacturing lines. One of the countermeasures is disclosed in Japanese Unexamined Patent Publication No. 161915/1983. In other words, the dropping speed of liquid nitrogen when it is discharged from the discharge hole and collides with the liquid level in the can is 200
cm/sec or less (temperature of the contents at 95°C), the ratio of the amount of residual liquid nitrogen in the can to the amount of supplied liquid nitrogen increases, reducing loss. The method disclosed in JP-A-56-161915 is quite effective in reducing loss of liquid nitrogen when the can into which liquid nitrogen is dripped is left standing, but it is not suitable for commercial production. In canning production lines, it is necessary to drip a desired amount of low-temperature liquefied gas into cans that are moving at high speed in a timely manner, so unless the dripping speed is considerably increased, the cans will pass under the dripping nozzle. In reality, it is not possible to make the residual rate of low-temperature liquefied gas very high inside the can, and in addition to the liquid nitrogen scattering outside the can, there is a risk of the liquid nitrogen dropping between the moving can and the low-temperature liquefied gas. The timing of gas dropping is likely to be misaligned, and since the dropping is a mixture of gas and liquid, the amount of residual low-temperature liquefied gas for each can still varies considerably. As mentioned above, low-temperature liquefied gas (for example, liquid nitrogen has a boiling point of approximately -196°C) is a cryogenic liquid, so it comes into contact with the surrounding atmosphere while being discharged from the discharge hole and reaching the liquid level in the container. However, it is fully expected that the low-temperature liquefied gas will vaporize and escape outside the can. Since this vaporization is proportional to the surface area of the discharged liquefied gas, a method has been proposed in which the required amount of liquefied gas is discharged from one discharge hole. As mentioned above, the dripping nozzle method cannot be used in high-speed canning production lines, so the inventors developed a system in which a constant flow rate (flow rate per unit time) of low-temperature liquefied gas continues to flow down from the discharge hole. devised a method of adding a fixed amount of low-temperature liquefied gas into each can by moving the can under it at a constant speed. This method can easily reduce the flow rate of low-temperature liquefied gas per unit time by changing the size of the discharge hole or changing the liquid level of the low-temperature liquefied gas in the low-temperature liquefied gas storage tank that has a discharge hole at the bottom. Since the amount can be changed, there is an advantage that it can be used whether the canning line is a low-speed line or a high-speed line. However, even with the method of flowing low-temperature liquefied gas into the can as a continuous flow downstream, there is a lot of loss of liquefied gas due to scattering outside the can or rapid vaporization when the liquefied gas collides with the liquid level inside the can. In addition, there are many variations in the amount of residual liquefied gas in each can after sealing.
As it was, it could not be used in an actual canning production line. The present invention uses a low-temperature liquefied gas continuous flow method that can be used not only in low-speed but also high-speed container filling manufacturing lines, to increase the proportion of the low-temperature liquefied gas that remains inside the container. The purpose of the present invention is to reduce the amount of low-temperature liquefied gas used and to provide a method for adding low-temperature liquefied gas that reduces the variation in the amount of low-temperature liquefied gas remaining in each container after sealing. (Findings of the Inventors and Means for Solving the Problems) According to the experiments of the present inventors, when low-temperature liquefied gas is injected as a continuous flow into a container containing liquid that moves at high speed, the low-temperature liquefied gas The scattering and rapid vaporization caused by collision with the liquid surface in the container increase in proportion to the impact force at the time of collision, and if the same amount of low-temperature liquefied gas is to be discharged, the continuous downstream flow of low-temperature liquefied gas must be Using multiple strips to reduce the impact force upon collision with the liquid surface in the container has a great effect on suppressing the scattering and rapid vaporization of low-temperature liquefied gas. If this is the case, if the downstream arrangement of these continuous flows is made approximately parallel to the traveling direction of the moving top-opening container, the flow rate will be lower when the liquid in the container collides with the surface of the container, compared to other arrangements. It was found that the rapid vaporization of the low-temperature liquefied gas and the blowing of the low-temperature liquefied gas by the vaporized gas were reduced, and furthermore, the variation in the internal pressure of the container after sealing was reduced. However, if there are multiple continuous flow downstream lines to discharge and add a predetermined amount of low-temperature liquefied gas into a container, it will take 1
Since the surface area of the entire downstream of the continuous flow discharged from the nozzle is larger than in the case of continuous flow, it is expected that the amount of vaporized liquid before it contacts the liquid surface of the container will increase. This disadvantage can be alleviated by reducing the distance between the lower surface of the nozzle discharge hole and the upper end of the container (preferably approximately 35 mm or less, particularly preferably 10 mm or less); on the other hand, the shortening of this distance will reduce the aforementioned impact force accordingly. Since it is made smaller, the effect of preventing scattering etc. is further enhanced, and the disadvantage of a larger surface area is sufficiently compensated for. The present invention was born from this knowledge, and it is possible to move an upper open container containing liquid at a constant speed under the discharge hole through which a constant flow of low-temperature liquefied gas is continuously flowing down. A method of adding a predetermined amount of low-temperature liquefied gas to a container, wherein the continuous flow downstream of the low-temperature liquefied gas is a downstream line formed from a plurality of downstream lines arranged substantially parallel to the traveling direction of the container. This is a method for adding low-temperature liquefied gas. (Function) In the present invention, since the continuous flow downstream of the low temperature liquefied gas is made into multiple streams, each stream becomes a trickle, compared to the case where the same flow rate is made to flow down as one stream.
As a result, the impact force upon collision with the liquid surface in the container is reduced, making it possible to suppress scattering and rapid vaporization of the low-temperature liquefied gas. Furthermore, in the present invention, since the plurality of downstream streams of low-temperature liquefied gas are arranged approximately parallel to the traveling direction of the container moving at a constant speed, referring to FIG. As the container moves, the low-temperature liquefied gas that has flowed down from the discharge hole 5 at the far end (on the left side in Figure 1) falls to the same position as the liquid level of the liquid in the container. The low-temperature liquefied gas from the second discharge hole from the end falls, then the low-temperature liquefied gas from the third discharge hole falls on top of it, and then the low-temperature liquefied gas from the fourth discharge hole falls on top of it. Like falling,
After a short period of time, the low-temperature liquefied gas will fall one after another in almost the same position, so the low-temperature liquefied gas discharged from the second and subsequent discharge holes will be substantially smaller than the liquid in the container. It falls on top of the low-temperature liquefied gas, which is at a low temperature, and comes into contact with it. Therefore, the amount of vaporization of the low-temperature liquefied gas at the time of collision on the content liquid level decreases, and accompanied by intense vaporization of the low-temperature liquefied gas. The scattering of low-temperature liquefied gas is also reduced. In combination, these factors reduce the variation in the internal pressure of each container after the container is sealed. (Example) Next, an example of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view of a main part of an apparatus for carrying out the method of the present invention, and FIG. 2 is a bottom view of the nozzle shown in FIG. 1. Note that the arrow in FIG. 2 indicates the direction of movement of the container. Reference numeral 1 denotes a low temperature liquefied gas storage tank with a double-walled heat insulating structure, and a vacuum is created between the inner wall 2 and outer wall 3. 4 is a nozzle formed at the bottom of the storage tank 1 to discharge and flow down the low-temperature liquefied gas, and 5 is a discharge hole provided in the nozzle 4 (Figures 1 and 2 show five discharge holes arranged in a row). example). Reference numeral 6 indicates a container (a two-piece can in the figure) that is already filled with the liquid content, and 7 is attached at equal intervals to an endless chain (not shown) that moves at a constant speed, and the body of the container is inserted from the rear. This is a claw that is pushed to move the container at a constant speed. 8 is a guide rail for regulating the movement of the moving container in a direction perpendicular to the traveling direction, and 9 is a table on which the container slides. Here, the relationship between each of the discharge holes 5 of the nozzle 4 and the container 6 to be transferred is such that each of the discharge holes 5 passes through the center of the opening of the container 6 to be transferred (i.e., If the container has a circular cross section, the diameter line parallel to the direction of travel of the container and the row of discharge holes 5 are
It is preferable to make them almost identical. That is, in this case, when low-temperature liquefied gas is continuously discharged and flowed down from each discharge hole 5, each continuous flow downstream from each discharge hole 5 falls almost on the diameter line with the smallest interval between the containers. , the amount of low-temperature liquefied gas that falls between containers can be reduced. The liquid level of the low-temperature liquefied gas in the storage tank 1 is
The pressure is atmospheric pressure, and the liquid level is determined by a liquid level control sensor (not shown) and a solenoid valve that is attached to the low-temperature liquefied gas supply pipe and opens and closes in response to signals from the liquid level control sensor. Therefore, the total amount of low temperature liquefied gas discharged from the discharge holes 5 within a certain period of time is always substantially constant. When this device is used, the amount of low-temperature liquefied gas flowing down per hour (ml/s) is always approximately constant, so the top-opening container is placed below the nozzle that is continuously discharging low-temperature liquefied gas. If it is moved at a constant speed, a constant amount of low temperature liquefied gas will be added into the container. Then, the container to which the low-temperature liquefied gas is added is immediately sealed to prevent the liquefied gas from evaporating and dissipating, and to maintain a constant gas pressure within the container. Next, an experimental example of the method of the present invention will be explained. For this experiment, a diameter of approximately 52.6 mm (so-called 202 diameter) was used.
A tin DI can with a height of approximately 132 mm and an internal volume of 250 ml was used. Water at 90℃ is poured into this DI can at a rate of 450 cans/min.
After filling 240g (240±1g), the liquid is passed under the discharge holes of liquid nitrogen discharge nozzles with different arrangement of discharge holes at the same speed, so that the liquid continuously flows down from each discharge hole. Immediately after nitrogen was received into the can, the lid of the easy-open can was tightened using a lid tightening machine to seal the can. Experimental conditions ●Amount of liquid nitrogen added; approx. 0.22ml/can ●Time required from adding liquid nitrogen to tightening the lid;
1.8 seconds ● Distance between the bottom of the nozzle and the top of the can flange (vertical distance): approx. 5 mm ● Liquid level height in the liquid nitrogen storage tank: approx. 140 mm ● Number of nozzle discharge holes, diameter, pitch between discharge holes (discharge Distance between centers of holes): 5 each for A, B, C, and D, 12 each for 0.8 mm, 2.5 mm, and E only
0.52 mm, 2.0 mm The row of discharge holes in A was made to almost coincide with the diameter line of the opening of the can parallel to the direction of travel. Experimental result

[Table] From Table 1, if the number of nozzles has the same number of discharge holes, nozzle A whose discharge holes are arranged parallel to the can traveling direction
When liquid nitrogen is added using a method of adding liquid nitrogen, that is, when the downstream arrangement of multiple lines of liquid nitrogen flow is arranged parallel to the can advancing direction (this example), the average can internal pressure of the packed can is the highest, and It can be seen that there is little variation in the internal pressure of each can. Furthermore, it can be seen that the average can internal pressure is higher and the variation in the can internal pressure is smaller as the liquid nitrogen is added to the can using a nozzle whose discharge holes are arranged closer to parallel to the traveling direction of the can. Since the total amount of liquid nitrogen discharged from the discharge hole is the same no matter which nozzle is used, the higher the average can internal pressure, the less loss of liquid nitrogen after being discharged from the nozzle discharge hole. become. When nozzle A is used, the loss of liquid nitrogen is small when the can is nozzle 4 from the second from the front in the direction of travel of the can.
The liquid nitrogen that has flowed down from the discharge holes has already fallen and is floating on the liquid level inside the can at an extremely low temperature (approximately -196℃)
Because it falls onto the liquid nitrogen at 90°C, there is less rapid vaporization upon impact on the liquid content surface compared to cases B, C, and D, which drop directly onto the liquid content surface at 90°C.
Along with this, the amount of rapidly vaporized nitrogen gas being blown out of the can is reduced, and furthermore, it is discharged between the cans (since the cans are cylindrical, the flow of nitrogen gas parallel to the direction of travel is reduced). The more the diameter line of the opening and the discharge hole deviate from each other, the more the continuously flowing liquid nitrogen will fall out of the can. This seems to be because the closer you are to the diameter line of the Furthermore, from the comparison between E and A, it is found that instead of increasing the number of nozzle discharge holes, if the diameter of each discharge hole is made smaller and the discharge amount per discharge hole is reduced (the total discharge amount is (This is the same as when the number of discharge holes is small), it can be seen that there is less loss of liquid nitrogen, and there is also less variation in the internal pressure of each canned material to which it is added. This is because the impact force when each of the liquid nitrogen discharged from each discharge hole and flowing down collides with the liquid level inside the can is weakened, so that the liquid nitrogen bounces off the liquid level inside the can and goes out of the can. This seems to be because there is less scattering. FIG. 3 is a bottom view of another nozzle used in the method of the present invention, in which the number of discharge holes 5 of the nozzle 4 is 12, the array is arranged in two rows of 6 discharge holes, and each row of discharge holes is arranged in a can. (The nozzle in this example was used in Experimental Example E). (For ease of viewing, the size of the discharge hole in the figure is the same as the discharge hole in Figure 2.) the same). In this example, the nozzle 4 and the container 6 to be transferred are arranged so that the liquid nitrogen discharged from each discharge hole row falls on both sides of the diameter line of the circle drawn by the cross section of the opening of the container 6. Adjusting the position is desirable from the viewpoint of reducing the discharge of liquid nitrogen outside the container. As is clear from the results of the experimental example, the nozzle 4 of this example has a smaller size of each discharge hole 5 than the example shown in FIG. There is little loss of liquid nitrogen. FIG. 4 is a bottom view of yet another nozzle used in the method of the present invention, in which the number of discharge holes 5 of the nozzle 4 is 18.
This is an example in which the nozzles are arranged in 3 rows of 6 nozzles, and each row of discharge holes is parallel to the direction of travel of the container (direction of the arrow). , written in the same way as the examples in Figures 2 and 3). In this example, the arrangement of the nozzle 4 and the container 6 to be transferred is adjusted so that the continuous downstream flow of liquid nitrogen from the central discharge hole row falls on the diameter line of the circle drawn by the opening of the container 6. However, it is desirable from the viewpoint of reducing discharge to the outside of the container 6. The number of discharge holes 5 of the nozzle 4 of this example is increased by 50% compared to the nozzle 4 shown in FIG. 3, and the diameter of each discharge hole 5 is reduced by slightly less than 20% ( Therefore, the total discharge amount of the nozzle is the same as in the example shown in Fig. 3), so the impact force when each stream collides with the liquid level inside the container becomes weaker, and therefore, the liquid nitrogen rebounds to the outside of the container. Less scattering. FIG. 5 is a sectional view of a main part of another apparatus for carrying out the method of the present invention. The difference from the device shown in FIG. 1 is that two nozzles 4 formed at the bottom of the low-temperature liquefied gas storage tank 1 are provided in series (three discharge holes 5 are arranged in series in the direction of travel of the container). ). This means that even if you change the filling speed of the liquid in the container 6, the amount of liquid nitrogen added to the container 6 (or the amount filled)
This is to ensure that it does not change. That is, the filling speed of the content liquid into the container 6 is determined by the capacity of the filling line, but if two nozzles 4 and three discharge holes 5 are provided as in this example, it will be easier to fill the container 6 at high speed. When used (i.e., when the container is moving at a high speed), liquid nitrogen is discharged and flowed down from the six discharge holes 5 of the two nozzles 4, 4. On the other hand, while the filling speed is low (i.e., when the container is moving) When the speed is 1/2 that of the high-speed line), if the discharge hole of one nozzle 4 is closed with a valve (not shown), liquid nitrogen flows down only from the three discharge holes 5 of one nozzle 4. Therefore, in either case, the amount of liquid nitrogen added to the container 6 is the same. In this example, the number of ejection holes 5 of each nozzle 4 is three, but as described above, it is of course preferable to increase the number of ejection holes 5. In all of the above embodiments, the discharge holes of the nozzles are all arranged in a straight line.
If a discharge hole is used that has an inclined passage so that the liquefied gas discharged from the discharge hole falls diagonally instead of straight down, it is not necessary to arrange the discharge holes in a straight line. That is, to explain using an example of a nozzle with three discharge holes, two of the three discharge holes are aligned in a straight line with the container traveling direction, and the remaining one discharge hole is aligned with the previous two discharge holes. Two of the three discharge holes are arranged in a straight line, and the low temperature liquefied gas is discharged directly below. One discharge hole provided in the is a discharge hole with a passage inclined toward the two discharge hole rows, so that the low-temperature liquefied gas flowing down from the three discharge holes above the liquid level in the container is substantially one after another. Overlapping (that is, low-temperature liquefied gas discharged from the discharge holes on the front side in the direction of travel of the container in the row of discharge holes arranged in a straight line and falling onto the liquid surface of the container, the low-temperature liquefied gas is liquefied from the discharge holes with inclined passages. The gas falls, and on top of that,
In some cases, the low-temperature liquefied gas falls from the remaining discharge holes in a row of discharge holes arranged in a straight line, or two discharge holes arranged in a straight line are placed on the discharge hole side slightly laterally. The discharge hole has an inclined passage, and one discharge hole provided slightly to the side is used as the discharge hole described above.
In the case where the discharge holes have passages inclined toward the row of discharge holes so that the low-temperature liquefied gas from the three discharge holes overlaps one after another on the liquid level in the container, the discharge holes can be arranged in a straight line. This is because it can produce the same effect as arranging them on a line. The low-temperature liquefied gas that can be used in the method of the present invention is
In addition to the liquid nitrogen shown in the examples, for example, liquid argon may also be used.In addition to the metal can, there are two types of containers, such as a plastic container consisting of one or more layers, metal foil, paper, and plastic. A composite container formed from the above may also be used. Furthermore, when low-temperature liquefied gas is added into a container containing liquid by the method of the present invention, residual air in the container is expelled by the vaporized gas until the container is sealed, so that the liquid and contents of the container are not affected during storage. Deterioration of product quality can be prevented. Therefore, high-quality packaged foods can be produced by using not only the hot filling method but also the cold filling method as a method for filling containers with the liquid contents. (Effects of the Invention) As shown in the experimental data, the present invention has the following advantages:
The proportion of low-temperature liquefied gas remaining in the container (which becomes vaporized gas within a short period of time after the container is sealed) compared to the case where the downstream arrangement of multiple continuous streams of low-temperature liquefied gas is not approximately parallel to the container traveling direction. This has the effect of reducing the total amount of low-temperature liquefied gas used to obtain the desired amount of residual liquefied gas, and reducing the variation in the amount of residual low-temperature liquefied gas in each container after sealing. This has the effect of reducing or preventing the occurrence of defective products due to bulging deformation of the lid etc. due to excessive gas filling or denting of the container body due to insufficient gas filling. Furthermore, the present invention can significantly reduce the total amount of low-temperature liquefied gas used and reduce the cost of filling gas-filled containers, compared to a method in which low-temperature liquefied gas is added into a container using a continuous stream downstream. This has the effect of greatly reducing or preventing the occurrence of non-defective products. Furthermore, compared to a method using a dropping nozzle method, the present invention can be used in a high-speed container packaging production line, and has the advantage that the occurrence of defective products in manufactured gas-filled containers can be greatly reduced or prevented. has.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the main parts of an apparatus for carrying out the method of the present invention, Figure 2 is a bottom view of the nozzle of the apparatus shown in Figure 1, and Figures 3 and 4 are for carrying out the method of the present invention. Bottom view of the nozzle of each separate device, No. 5
The figure is a sectional view of a main part of another apparatus for carrying out the present invention, and FIG. 6 is a bottom view of the nozzle of the apparatus used for comparative experiments. 4... Nozzle, 5... Discharge hole, 6... Container.

Claims (1)

[Claims] 1. A predetermined amount of low-temperature liquefied gas is introduced into the container by moving a top-open container containing liquid at a constant speed under a discharge hole through which a constant flow of low-temperature liquefied gas is continuously flowing down. A method for adding low-temperature liquefied gas, characterized in that the continuous flow downstream of the low-temperature liquefied gas is a downstream stream formed from a plurality of downstream streams arranged substantially parallel to the traveling direction of the container. How to add gas. 2. The method according to claim 1, characterized in that there are a plurality of downstream rows of low-temperature liquefied gas. 3. Claim 1 or 3, wherein the cross-sectional shape of the opening of the top-opening container is circular, and the arrangement of the plurality of downstream streams of the low-temperature liquefied gas substantially coincides with the diameter line of the opening of the container. The method described in Section 2.