JPH0960992A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the degree of separation of a final separation component, to improve purity of a low boiling point component, to increase the degree of cooling of a substance to be cooled, and to stabilize a cooling temperature by providing a cooling means having the same number of stages as the number of components of a mixture refrigerant. SOLUTION: The outlet of the outer pipe of a fourth intermediate heat- exchanger 15 is connected to the inlet of a fifth gas liquid separator 50. A gas phase part 50a of the fifth gas liquid separator 50 is connected to the inlet of a cooler 19 through a fifth intermediate heat-exchanger 21 and a throttle 18. The liquid phase part 50b is connected to the inlet of the inner pipe of the fifth intermediate heat-exchanger 21 through a fifth throttle 22. After most of liquid R14 and a part of an R50 are reduced in a pressure by the fifth throttle 22, the R14 and the R50 flow in the inner pipe of the fifth intermediate heat- exchanger 21 and joined with a feedback refrigerant therein for vaporization. Since re-distillation operation of the high boiling point component R14 is effected by the fourth intermediate heat-exchanger 15 and the additionally mounted fifth gas liquid separator 50, the degree of separation of the high boiling point component R14 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic refrigerating apparatus adopting a multistage fractional distillation system.

[0002]

2. Description of the Related Art Conventionally, as an ultra-low temperature refrigerating apparatus at -100 ° C. or lower, for example, as shown in Japanese Patent Application No. 06-264336, one compressor and condenser, and a plurality of gas-liquid separators and heat exchangers. A multi-component non-azeotropic mixed refrigerant with different boiling points is enclosed in a one-way refrigeration cycle consisting of, and condensation and gas-liquid separation are repeated to carry out fractional distillation to separate the high-boiling refrigerant, extracting the low-boiling refrigerant and guiding it to the cooler. There is a multi-stage fractionation type ultra-low temperature refrigeration system that directly cools the object to be cooled or cools the secondary refrigerant.

FIG. 4 is a refrigerant system diagram of the conventional refrigeration system (direct cooling system). In the figure, the discharge side of the compressor 1 is connected to the inlet of a condenser 3 via an oil separator 2. The outlet of the condenser 3 is connected to the inlet of the first gas-liquid separator 5 via the auxiliary condenser 4. The gas phase part 5a of the first gas-liquid separator 5 is connected to the outer pipe inlet of the first intermediate heat exchanger 6, and the liquid phase part 5b of the first intermediate heat exchanger 6 is connected via the first throttle 7. It is connected to the inner pipe entrance.

The first intermediate heat exchanger 6 is formed of a double tube, and in order to enhance the efficiency of heat exchange between the refrigerant flowing in the outer tube and the refrigerant flowing in the inner tube, the outer tube inlet and the inner tube outlet are provided. Is provided at one end of the intermediate heat exchanger 6, and the outer pipe outlet and the inner pipe inlet are provided at the other end. In this way, the first
The gas-liquid separator 5, the first intermediate heat exchanger 6, and the first throttle 7 form a first-stage cooling means 1S. Similarly, the second
The gas-liquid separator 8, the second intermediate heat exchanger 9, and the second throttle 10 form the second-stage cooling means 2S, and the third gas-liquid separator 11, the third intermediate heat exchanger 12, and the third throttle 13 make the first cooling means 2S. In the three-stage cooling means 3S, the fourth-stage cooling means 4S is formed by the fourth gas-liquid separator 14, the fourth intermediate heat exchanger 15, and the fourth throttle 16.

The outer tube outlet of the fourth intermediate heat exchanger 15 is connected to the inlet of a cooler 19 provided in the ultra-low temperature storage via an auxiliary cooler 17 and a throttle 18. The outlet of the cooler 19 is connected to the inner pipe inlet of the fourth intermediate heat exchanger 15 via the auxiliary cooler 17. An inner pipe outlet of the fourth intermediate heat exchanger 15 is an inner pipe inlet of the third intermediate heat exchanger 12, an inner pipe outlet of the third intermediate heat exchanger 12 is an inner pipe inlet of the second intermediate heat exchanger 9, The inner pipe outlet of the second intermediate heat exchanger 9 is at the inner pipe inlet of the first intermediate heat exchanger 6, and the inner pipe outlet of the first intermediate heat exchanger 6 is at the suction side of the compressor 1 via the auxiliary condenser 4. It is connected to the.

In the refrigerant circuit of this refrigeration system, a refrigerant composition prepared by mixing five kinds of refrigerants having different boiling points, that is, refrigerant RC318 (octafluorocyclobutane) and refrigerant R
32 (difluoromethane), refrigerant R23 (trifluoromethane), and refrigerant R14 (tetrafluoromethane)
And a non-azeotropic mixed refrigerant composed of the refrigerant R50 (methane) is sealed in a premixed state. At the atmospheric pressure, the boiling point of each refrigerant is RC5.7 at −5.75 ° C., R32
Is −51.69 ° C., R23 is −82.15 ° C., R14 is −127.9 ° C., and R50 is −161.5 ° C. The composition of each refrigerant is, for example, RC318 of 56% by weight,
5% by weight of R32, 17% by weight of R23, 17 of R14
% By weight and R50 is 5% by weight.

Next, the operation of this apparatus will be described. The high-temperature and high-pressure gaseous mixed refrigerant discharged from the compressor 1 enters the oil separator 2, where the oil is separated and removed, and then flows into the condenser 3,
Here, after being cooled to about 30 ° C. by cooling water,
It flows into the auxiliary condenser 4. Here, the high boiling point refrigerant therein, that is, all of RC318 and a part of R32 are liquefied and further flow into the first gas-liquid separator 5 by being further cooled to about 15 ° C. by the return refrigerant.

[0008] Here, all of the high boiling point refrigerant RC318 and R3
Liquid refrigerant consisting of a part of 2 and low boiling point refrigerants R50, R
The residual gaseous refrigerant consisting of 14, R23 and uncondensed R32 is separated. All of the separated liquid refrigerant RC318 and a part of R32 are decompressed by the first throttle 7, then flow into the inner pipe of the first intermediate heat exchanger 6, where they are combined with the return gas refrigerant and evaporated.

On the other hand, a part of the residual gaseous refrigerant R32 and R
All of 23, R14, and R50 exchange heat with the return refrigerant and the separated residual gaseous refrigerant that flow through the inner tube in the process of flowing through the outer tube of the first intermediate heat exchanger 6, for example, −1.
By cooling to about 5 ° C., all of R32 and part of R23 therein are liquefied.

Next, this refrigerant flows into the second gas-liquid separator 8 where it is separated into a liquid refrigerant and a residual gaseous refrigerant.
The entire liquid R32 and a part of R23 are decompressed by the second throttle 10, and then flow into the inner pipe of the second intermediate heat exchanger 9, where they are combined with the return refrigerant and evaporated.

On the other hand, a part of the residual gas refrigerant R23 and R1
4, all of R50 are cooled to, for example, about −40 ° C. by the refrigerant flowing through the inner pipe of the second intermediate heat exchanger 9 in the process of flowing through the outer pipe, so that all of R23 and a part of R14 therein. Liquefies.

This refrigerant flows into the third gas-liquid separator 11,
Here, it is separated into a liquid refrigerant and a gaseous refrigerant. Liquid R
A part of 23 and R14 is decompressed by the third throttle 13, then flows into the inner pipe of the third intermediate heat exchanger 12, where it joins with the refrigerant flowing through the outer pipe and evaporates.

On the other hand, a part of the residual gaseous refrigerant R14 and R5
0 is cooled to about −70 ° C. by the refrigerant flowing through the inner pipe in the process of flowing through the outer pipe of the third intermediate heat exchanger 12, so that most of R14 therein and one of R50. The part is liquefied and flows into the fourth gas-liquid separator 14, where it is separated into a liquid refrigerant and a gaseous refrigerant.

Most of the liquid R14 and a part of R50 are reduced in pressure by the fourth throttle 16, then flow into the inner pipe of the fourth intermediate heat exchanger 15, where they are combined with the return refrigerant and evaporated. On the other hand, part of the residual gas refrigerant R14 and most of R50 are the fourth
During the process of flowing through the outer pipe of the intermediate heat exchanger 15, the refrigerant flowing through the inner pipe cools the mixture to about -100 ° C., for example, so that all of R14 and R50 are liquefied to the auxiliary cooler 17. It flows in, and is further cooled here by the return refrigerant from the cooler 19 to, for example, about −115 ° C., and most of R50 is liquefied.

These liquefied R14 and R50 are reduced in temperature by being depressurized by the fifth throttle 18 to, for example, -15.
It flows into the cooler 19 at about 5 ° C., and evaporates there to cool the inside of the ultra-low temperature storage to a low temperature of −150 ° C.

The refrigerant evaporated in the cooler 19 is the auxiliary cooler 1
7. Return to the compressor 1 through the intermediate heat exchangers 15, 12, 9, 6, and the condenser 4 in this order. Lubricating oil mixed with the discharge refrigerant from the discharge pipe of the compressor 1 and flowing out is separated in the oil separator 2 and flows out through the pipe 20 to join the return refrigerant to the compressor 1 to the compressor 1. Will be returned.

[0017]

In the conventional multistage fractional distillation ultra-low temperature refrigeration system described above, refrigerants having different boiling points (for example, RC318, R32, R23, R14,
R50 (5 components) are mixed and compressed into a non-azeotropic mixed refrigerant, and then gas-liquid separation and cooling processes are repeated to extract a low boiling point refrigerant (R50) [number of mixed refrigerant components] -1] (for example, 4) gas-liquid separators 5, 8,
Cooling means 1S, 2S including 11, 14, throttles 7, 10, 13, 16 and intermediate heat exchangers 6, 9, 12, 15.
It had 3S and 4S.

For convenience of description, the definition of terms will be confirmed. In chemical engineering, the operation of evaporating and condensing and dividing the liquid component into each component is called "distillation". Generally, a case where a mixture containing three or more multi-components is separated by distillation is called "rectification" or "fractional distillation", and a treatment for a mixture of two components is called "single distillation". The liquid obtained by condensation is called "distillate". Since the degree of separation of the target component is generally insufficient in a single distillation, the distillate is distilled again to further increase the degree of separation.
This is called "re-distillation".

In the above conventional ultra-low temperature refrigeration system, the high boiling point refrigerant RC318 is first distilled in the first gas-liquid separator 5 and redistilled in the second and third gas-liquid separators 8 and 11. R
32 is first distilled in the second gas-liquid separator 8 and redistilled in the third and fourth gas-liquid separators 11 and 14. R23 is the third
It is first distilled in the gas-liquid separator and redistilled in the fourth gas-liquid separator 14. Thus RC318, R32 and R2
Since 3 is redistilled, it can be separated to a sufficient degree. However, regarding R14, the fourth
Since only one distillation is performed in the gas-liquid separator 14, the degree of separation is low and the refrigerant supplied to the cooler 19 is not pure R50 but a non-azeotropic mixture of R50 and R14. There is a problem that it becomes a mixed refrigerant.

When the refrigerant supplied to the cooler 19 is a two-component non-azeotropic mixed refrigerant in which R50 and R14 are mixed as described above, a temperature difference occurs at the inlet and outlet of the cooler 19 (the cooler outlet temperature is the inlet temperature. Therefore, the average temperature of the cooler 19 rises, the cooling degree of the object to be cooled deteriorates, and the mixing degree of R14 changes depending on operating conditions.
Since the temperature difference also fluctuates, there arises a problem that the temperature of the cooled object is not stable.

The present invention solves the above-mentioned drawbacks of the prior art, reduces the temperature difference at the inlet and outlet of the cooler, increases the cooling degree of the object to be cooled, and stabilizes the cooling temperature.

[0022]

Means for Solving the Problems The present invention has been made to solve the above problems, and is a compressor for enclosing a mixed refrigerant composed of a plurality of types of refrigerants having different boiling points, and compressing the mixed refrigerant. A condenser that cools the high-temperature and high-pressure mixed refrigerant compressed by this compressor, a gas-liquid separator that separates the cooled and partially liquefied mixed refrigerant into a high-boiling-point liquid refrigerant and a residual gas refrigerant, and this gas-liquid A throttling mechanism for depressurizing the liquid refrigerant separated by the separator and an intermediate heat exchange for cooling the residual gas refrigerant separated by the gas-liquid separator by exchanging heat with the liquid refrigerant depressurized by the throttling mechanism and the return gas refrigerant. Cooling means for separating and cooling the low boiling point refrigerant from the high boiling point refrigerant sequentially, a cooler for depressurizing and evaporating the low boiling point liquid refrigerant cooled by the final cooling means, and this cooling After performing the cooling function in the vessel A refrigerating apparatus comprising a pipe for returning the discharged refrigerant to the compressor through the intermediate heat exchanger at the final stage and sequentially through the intermediate heat exchanger at the first stage, The present invention relates to a refrigerating device.

(1) The cooling means is provided in the same number of stages as the number of components of the mixed refrigerant.

(2) In the refrigerating apparatus according to the above item (1), the final stage gas-liquid separator is replaced with a rectification column to further enhance the extraction purity of the low boiling point refrigerant R50,
The gist of this is that most of the high boiling point refrigerant is separated and cooled by the cooling means in the preceding stage of the final stage, and the mixed refrigerant that has been cooled and partly liquefied is received and this is redistilled repeatedly in the column to obtain a high purity low boiling point refrigerant. A rectification column for separating a refrigerant and a high-boiling-point liquid refrigerant, a throttling mechanism for decompressing the liquid refrigerant separated by the rectification column, and the high-purity low-boiling-point gas refrigerant separated by the rectification column. An intermediate heat exchanger for cooling by exchanging heat with the liquid refrigerant and the return gas refrigerant decompressed by the throttle mechanism, and a reflux pipe for returning a part of the liquefied refrigerant cooled by the intermediate heat exchanger to the rectification tower. A final stage cooling means was provided.

In the means of the above item (1), the mixed refrigerant is, for example, RC318, R32, R23, R1 in the order of high boiling points.
Assuming that it is composed of five components of R4 and R50, the final separation component R14 is first distilled in the fourth gas-liquid separator which is the previous stage of the final stage, and most of R14 and a part of R50 are obtained. Separated as a liquid. And most of R50 and R1
Part of the residual gas refrigerant of No. 4 is cooled and enters the fifth gas-liquid separator at the final stage, where it is redistilled and most of a part of R14 in the residual gas refrigerant is separated as a liquid. The degree of separation of R14 can be increased as compared with the conventional one which is completed by the first distillation operation.

In the means of the above item (2), for example, in the mixed refrigerant of the above five components, R1 in the fourth gas-liquid separator is used.
Most of R50 remaining as gas in the first distillation of No. 4 and a part of the residual gas refrigerant of R14 are cooled and cooled to the fifth stage of the final stage.
After entering the rectification column that constitutes the cooling means, gas-liquid contact involving mass transfer is performed between the reflux liquid flowing down in the column and the gas refrigerant rising in the column, resulting in repeated redistillation. Be seen. Therefore, the degree of separation of R14 can be further increased.

[0027]

1 is a refrigerant system diagram of a refrigerating apparatus according to a first embodiment of the present invention. In the figure, 50 is a fifth gas-liquid separator, 21 is a fifth intermediate heat exchanger, and 22 is a fifth.
A diaphragm 5S is a fifth cooling unit including the above-mentioned devices.
This means is installed in place of the conventional auxiliary cooler 17. The pipe connection will be described later. Since the other parts than the above are the same as those of the conventional technique (FIG. 4), the description of the configuration will be omitted.

In the above system, the fourth intermediate heat exchanger 15
The outer tube outlet of is connected to the inlet of the fifth gas-liquid separator 50. The gas phase portion 50a of the fifth gas-liquid separator 50 has the fifth
It is connected to the inlet of the cooler 19 via the intermediate heat exchanger 21 and the throttle 18. The liquid phase portion 50b is connected to the inner pipe inlet of the fifth intermediate heat exchanger 21 via the fifth throttle 22.

Thus, the third intermediate heat exchanger 12 and the fourth
Most of R14 is liquefied and separated by the R14 fractional distillation operation by the gas-liquid separator 14, and the R50 gaseous mixed refrigerant containing a small amount of the remaining R14 flows into the fourth intermediate heat exchanger 15 and is cooled there. , R14 and a part of R50 are liquefied and flow into the fifth gas-liquid separator 50, where they are separated into a liquid refrigerant and a gaseous refrigerant. Most of the liquid R14 and part of R50 are decompressed by the fifth throttle 22, then flow into the inner pipe of the fifth intermediate heat exchanger 21, where they are combined with the return refrigerant and evaporated.

On the other hand, a part of the residual gas refrigerant R14 and R50
Of the intermediate heat exchanger 21 is liquefied by being cooled to about −115 ° C. by the refrigerant flowing through the inner pipe in the process of flowing through the outer pipe of the fifth intermediate heat exchanger 21 and decompressed by the throttle 18 to the cooler 19. Inflow. In this way, since the redistillation operation of the high boiling point component R14 is performed by the fourth intermediate heat exchanger 15 and the fifth gas-liquid separator 50 additionally provided, the degree of separation of the high boiling point component R14 is higher than that in the conventional circuit. Can be increased.

FIG. 2 is a refrigerant system diagram of a refrigerating apparatus according to the second embodiment of the present invention, FIG. 3 is a diagram of a rectification column used in the same system, (a) is a longitudinal sectional view, and (b) is a sectional view. [Fig. 3] is a detailed view of a B part in (a). In the figure, 30 is a rectification column, 21 is a fifth intermediate heat exchanger, 22 is a fifth throttle, 23 is a reflux pipe, and 5S 'is a fifth cooling means including the above-mentioned devices. This means is installed in place of the conventional auxiliary cooler 17 or the fifth cooling means 5S in the first embodiment. The pipe connection will be described later. The parts other than the above are the same as those of the conventional technique (FIG. 4) or the first embodiment (FIG. 1), and therefore the description of the configuration is omitted.

In the above system, the fourth intermediate heat exchanger 15
The outer tube outlet of is connected to the inlet of the rectification column 30. The gas outlet at the top of the rectification column 30 is connected to the inlet of a cooler 19 provided in the ultralow temperature storage via a fifth intermediate heat exchanger 21 and a throttle 18. The liquid outlet at the bottom of the rectification column 30 is connected to the inner pipe inlet of the fifth intermediate heat exchanger 21 via the fifth throttle 22. A reflux pipe 23 for returning a part of the liquid refrigerant to the rectification column 30 is connected to the upper part of the rectification column 30 at the outer pipe outlet of the fifth intermediate heat exchanger 21. The outlet of the cooler 19 is connected to the inner pipe inlet of the fourth intermediate heat exchanger 15 via the fifth intermediate heat exchanger 21.

Next, an example of the structure and operation of the rectification column 30 will be described with reference to FIGS. 2 (a) and 2 (b). In the figure, the inside of the rectification column 30 is partitioned by an appropriate number of plate plates 31, and a large number of small holes 32 are formed in the plate plate 31. Further, an overflow pipe 33 is attached to one end of the perforated plate 31 so that the overflow pipe 33 comes out above the lower stage. And, an inlet 34 is provided at a stage in the middle of the tower, a gas outlet 35 is provided at the top,
A liquid outlet 36 is provided at the bottom, and a reflux liquid inlet 37 is provided at the top of the tower.

Thus, the third intermediate heat exchanger 12 and the fourth
Most of R14 is liquefied and separated by the R14 fractional distillation operation by the gas-liquid separator 14, and the R50 gaseous mixed refrigerant containing a small amount of the remaining R14 flows into the fourth intermediate heat exchanger 15 and is cooled there. Then, a part thereof is condensed and liquefied to be in a gas-liquid two-phase state (conventionally, in this state, the gas was supplied to the cooler 19 via the auxiliary cooler 17 and the throttle 18). Then, in this state, it flows into the rectification column 30 through the inlet 34.

A part of the liquefied refrigerant cooled in the fifth intermediate heat exchanger 21 flows through the reflux pipe 23 from the reflux liquid inlet 37 to the uppermost upper part of the tower. This reflux liquid is a plate 3
The water accumulates on one side, flows from one corner toward the overflow pipe 33 on the other side, goes over the weir of the overflow pipe 33, and descends on the lower plate 31. On the other hand, R14 and R5 flowing from the inlet 34
The gas portion of the mixed refrigerant with 0 passes through the fine holes 32 on the perforated plate 31 and forms a bubble through the above reflux liquid, and further rises to the upper stage.

In this way, gas bubbles pass through the reflux liquid. This is a gas-liquid contact operation involving mass transfer, in which the high boiling point component (R14) remaining in the gas condenses and moves into the liquid, and the low boiling point component (R50) in the liquid condenses in the former case. It gets latent heat, evaporates and moves into gas. Further, the liquid portion of the mixed refrigerant of R14 and R50 that has flowed in from the inlet 34 re-evaporates the low boiling point component (R50) while flowing downward through the perforated plate 31.

As described above, in the gas portion of the mixed refrigerant flowing into the rectification column 30, the high boiling point component (R14) in the gas is separated every time it passes through each stage in the column, and the extremely high boiling point component (R14) is separated. Is obtained, the gas flows out from the gas outlet 35, is cooled and liquefied in the fifth intermediate heat exchanger 21, and the throttle 18
And flows into the cooler 19. In this way, the rectification tower 30
One stage of the inner plate 31 has a function of redistillation once. It is a rectification tower without fail because it is a continuous device that repeats redistillation repeatedly. On the other hand, the low boiling point component (R50) in the liquid is separated every time the liquid portion of the mixed refrigerant of R14 and R50 flowing from the inlet 34 descends to the lower stage, and together with the reflux liquid flowing down to the lower stage, the rectification column 30 It is stored in the inner bottom portion, flows out from the liquid outlet 36, is decompressed by the fifth throttle 22, then flows into the inner pipe of the fifth intermediate heat exchanger 21, and merges with the return refrigerant.

[0038]

In the first aspect of the present invention, since the cooling means having the same number of stages (for example, 5 stages) as the number of components (for example, 5 components) of the mixed refrigerant is provided, the degree of separation of the final separated component (R14) can be improved. The purity of the low boiling point component (R50) can be increased. As a result, the temperature difference between the inlet and outlet of the cooler can be almost eliminated, the degree of cooling of the object to be cooled can be increased, and the cooling temperature can be stabilized.

In the second invention, since the rectification column is provided in place of the final-stage gas-liquid separator in the first invention, the purity of the low boiling point component (R50) is further increased as compared with the first invention. be able to. As a result, the same effect as that of the first invention can be further enhanced.

[Brief description of drawings]

FIG. 1 is a refrigerant system diagram of a refrigeration apparatus according to a first embodiment of the present invention.

FIG. 2 is a refrigerant system diagram of a refrigerating apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram of a rectification column used in the same system, (a)
Is a longitudinal sectional view, and (b) is a detailed view of a portion B of (a).

FIG. 4 is a refrigerant system diagram of a conventional refrigeration system.

[Explanation of symbols]

1 Compressor 3 Condenser 5,8,11,14,50 Gas-liquid separator 6,9,12,15,21 Intermediate heat exchanger 7,10,13,16,22 Throttling mechanism 19 Cooler 30 Fractionation tower 1S, 2S, 3S, 4S, 5S, 5S 'Cooling means

Claims (2)

[Claims] 1. A compressor for enclosing a mixed refrigerant composed of a plurality of kinds of refrigerants having different boiling points, and a compressor for compressing the mixed refrigerant, and a condenser for cooling the high-temperature and high-pressure mixed refrigerant compressed by the compressor. A gas-liquid separator for separating the cooled and partially liquefied mixed refrigerant into a high-boiling-point liquid refrigerant and a residual gas refrigerant, and a throttle mechanism for decompressing the liquid refrigerant separated by the gas-liquid separator, and the gas-liquid. It consists of an intermediate heat exchanger that cools the residual gas refrigerant separated by the separator by exchanging heat with the liquid refrigerant decompressed by the throttling mechanism and the return gas refrigerant. A plurality of stages of cooling means, a cooler for depressurizing and evaporating the low-boiling-point liquid refrigerant cooled by the cooling means of the final stage, and a refrigerant flowing out after performing the cooling action in this cooler, on the contrary to the final stage First stage from the intermediate heat exchanger In the refrigerating apparatus having a pipeline for returning to the compressor via the intermediate heat exchanger, the refrigerating apparatus is provided with the same number of cooling means as the number of components of the mixed refrigerant. 2. A mixed refrigerant in which most of the high boiling point refrigerant is separated by the cooling means in the preceding stage of the final stage and cooled and a part of which is liquefied is received, and this is redistilled repeatedly in the column to obtain a high purity low boiling point refrigerant. A rectification column that separates into a high-boiling-point liquid refrigerant, a throttling mechanism that depressurizes the liquid refrigerant that is separated in the rectification column, and the high-purity low-boiling-point gas refrigerant that is separated in the rectification column is the throttling mechanism. An intermediate heat exchanger that cools the liquid refrigerant and the return gas refrigerant that have been decompressed by heat exchange, and a reflux pipe that returns a part of the liquefied refrigerant that is cooled by the intermediate heat exchanger to the rectification tower. The refrigerating apparatus according to claim 1, further comprising: