JPH09145179A - Binary type cryogenic refrigerator with mixed refrigerant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a cooling action, with a simple installation and control, and in a stable operation. SOLUTION: A mixed refrigerant refrigerating circuit 11 is provided which uses a vapor phase mixture of a plurality of refrigerants having different boiling points, and a refrigerating circuit 12 of independent order of the mixed refrigerant refrigerating circuit 11 is formed by a compressor 40, condenser 41, expansion valve 42 and a cooler 43. The condenser 41 of the independent refrigerating circuit 12 is thermally connected to the last cooler 38 in the mixed refrigerant refrigerating circuit 11.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stable state--
The present invention relates to a refrigerator capable of developing a temperature of 100 ° C. or lower, and particularly to a mixed refrigerant binary ultra-low temperature refrigerator using a mixed refrigerant refrigeration circuit.

[0002]

2. Description of the Related Art Conventionally, there are a few refrigerators that exhibit temperatures of -100.degree. C. or less, but two types of refrigerators that are currently in practical use will be described below. The first of these types is a type in which refrigeration circuits are connected in multiple stages, and the second type is called a mixed refrigerant refrigeration circuit.

Prior to the description, the principle of a refrigeration circuit which is generally used will be described with reference to FIG. First, as a device of the refrigerating circuit, a compressor 1, a condenser 2, an expansion valve 3 and a cooler 4 are sequentially connected as a closed circuit in which a refrigerant is sealed. The action is that the refrigerant vapor is compressed in the compressor 1 and reaches up to + 30 ° C. in the condenser 2. By exchanging heat with outside air or water in the condenser 2, the refrigerant vapor is condensed and a condensed liquid is generated. This condensate is adjusted to a low pressure, vaporized by the expansion valve 3, exerts a cooling effect in the cooler 4, and the evaporated refrigerant returns to the compressor 1. Then, it is compressed again and the same cycle is repeated. Such a refrigeration circuit is referred to as a unitary refrigeration circuit 5. The limit of the cooling temperature by the unitary refrigeration circuit 5 is -40 ° C to -50 ° C.

Refrigerating capacity varies depending on the refrigerant used. Now, the case of using Freon Gas R-403B (nominal Refrigeration Society of America) will be described. This Pione diagram (Moriel diagram) of this Freon gas R-403B
Is shown in FIG. 5 and its thermodynamic properties are explained on the basis of this P-i diagram. Here, is a compression process, is a condensation process, is an expansion process, is an evaporation process, and shows the state of discharge refrigerant temperature +50 degreeC. First, the boiling point of Freon gas R-403B is, in the gauge pressure 0 kg / cm ^2, was -49.5 ° C., in the gauge pressure 15 kg / cm ^2, a + 33.1 ° C.. In order for the compressed refrigerant vapor to exchange heat with air or water to cool and condense, it is necessary to exchange heat with air or water at + 33.1 ° C- (5 to 10) ° C, and +33.
It is possible to obtain temperatures of 1 ° C- (5-10) ° C. When the condensed liquid refrigerant is vaporized by adjusting to 1 kg / cm ² , for example, a low temperature of about −35.1 ° C. appears.
Since the condensing pressure (high pressure) of 15 kg / cm ² and the evaporation pressure (low pressure) of 1 kg / cm ² in the refrigeration circuit are in a healthy state, it is possible to use Freon gas R-403B in the one-way refrigeration circuit 5. Thereby, a low temperature of −35 ° C. or lower can be revealed.

Next, as a conventional first type, there is a binary refrigeration circuit 6 in which a unitary refrigeration circuit 5 is combined to obtain a further low temperature, which is shown in FIG. This dual refrigeration circuit 6 is a combination of two sets of the single refrigeration circuit 5, and includes a cooler 4 of the first-stage single refrigeration circuit 5 and a condenser 2 of the second-stage single refrigeration circuit 5. And are arranged in the same atmosphere to form the heat exchanger 7. Therefore, the operation of the first-stage unitary-type refrigeration circuit 5 is as described above, and the cooler 4 exhibits a refrigerating action. The cooler 4 cools the heat of the second-stage condenser 2. Therefore, the second stage condenser 2
Is cooled at a temperature of −40 ° C. to −50 ° C., and the cooling temperature in the second stage cooler 4 is −70 ° C. to −8.
Reachs up to 0 ° C.

Specifically, the refrigerant used in the first stage refrigeration circuit is Freon gas R-403B as described above, but the refrigerant used in the second stage refrigeration circuit is Freon gas. R-23 (nominal American Refrigeration Association). Boiling point of the Freon gas R-23, in the gauge pressure 0 kg / cm ^2, was -82.0 ° C., in the gauge pressure 10 kg / cm ^2, is -30 ° C.. In order for the compressed refrigerant vapor to be heat-exchanged and cooled and condensed, a cooling medium having a temperature as low as about 5 ° C from -30 ° C is required. However, the refrigerant and heat of -35 ° C developed in the first stage refrigeration circuit It can be cooled and condensed by exchange. The refrigerant condensed and liquefied by cooling in this way exhibits a low temperature of about −75 ° C. when adjusted to 0.5 kg / cm ² and vaporized. Condensation pressure (high pressure) 10 kg / cm ² in the refrigeration circuit, evaporation pressure (low pressure) 0.5 k
Since g / cm ² is in a healthy state, it is possible to use Freon gas R-23 in the binary refrigeration circuit 6, whereby a low temperature of −75 ° C. or lower can be exhibited. This state is clear from the P-i diagram which is a partial excerpt shown in FIG.

Further, as a refrigeration circuit capable of expressing a low temperature, a ternary refrigeration circuit 8 as shown in FIG. 7 is implemented. It is recognized that the ternary refrigeration circuit 8 is a combination of three one-component refrigeration circuits 5 or a binary refrigeration circuit 6 to which the one-component refrigeration circuit 5 is further connected. That is, the first heat exchanger 9 is formed by the first-stage cooler 4 and the second-stage condenser 2, and the second heat exchanger 9 is formed by the second-stage cooler 4 and the third-stage condenser 2. Exchanger 10
Is formed. Therefore, in the portion of the first heat exchanger 9, the condenser 2 of the second stage is cooled at a temperature of -40 ° C to -50 ° C, and in the portion of the second heat exchanger 10,
The condenser 2 of the third stage will be cooled at a temperature of -70 ° C to -80 ° C. Therefore, the cooling temperature in the cooler 4 of the third stage can be set to -120 ° C to -130 ° C. In this way, the temperature of −100 ° C. or lower can be brought out by adopting the ternary refrigeration circuit 8.

The refrigerant used in the ternary refrigeration circuit 8 is Freon gas R-403B in the first stage, Freon gas R-23 in the second stage, and Freon gas R in the third stage. -14 (American Refrigeration Association Nominal). The boiling point of this Freon gas R-14 is -128.0 ° C when the gauge pressure is 0 kg / cm ² , and the gauge pressure is 16 kg / cm ^2.
Is -70 ° C. To cool and condense the compressed refrigerant vapor by heat exchange, a cooling medium having a temperature as low as about 5 ° C. from −70 ° C. is required, but with the refrigerant at −75 ° C. developed in the second stage refrigeration circuit. It can be cooled and condensed by heat exchange. The refrigerant that is cooled, condensed, and liquefied in this way exhibits a low temperature of about -122 [deg.] C. when adjusted to 0.5 kg / cm < ² > and vaporized. Condensation pressure (high pressure) 16 kg / cm ² in the refrigeration circuit, evaporation pressure (low pressure) 0.
Since 5 kg / cm ² is in a healthy state, it is possible to use Freon gas R-14 in the binary refrigeration circuit 6, whereby a low temperature of −122 ° C. can be realized. This state is clear from the P-i diagram shown in FIG.

What is common to each of the above-mentioned multi-source refrigeration circuits is that the evaporation temperature of the pre-stage refrigeration circuit must be lower than the condensation temperature of the post-stage refrigeration circuit, and that the pre-stage refrigeration circuit is That is, the refrigerating capacity (evaporating capacity) must be greater than the condensing capacity of the subsequent refrigeration circuit.

Next, the second type is referred to as a mixed refrigerant refrigeration circuit and utilizes a vapor phase mixture of a plurality of refrigerants having different boiling points. As an example, the technique is described in Japanese Utility Model Publication No. 55-2374. That is, a vapor phase mixture of a plurality of refrigerants having different boiling points is used, and a plurality of intermediate cooling stages are connected in series so that the refrigerant having a lower boiling point is sequentially cooled by the refrigerant having a higher boiling point. That is, one compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points, a mixture of compressed condensate and uncondensed compressed vapor by partially condensing the compressed refrigerant vapor And a plurality of gas-liquid separators for separating the compressed condensate and the uncondensed compressed vapor. The compressed condensate in the gas-liquid separator after passing through the intermediate condenser is vaporized and evaporated at a low pressure to the next condenser passing therethrough, exerts a cooling condensing effect, and returns to the compressor. The uncondensed compressed vapor passes through the condenser of the next stage and is partially condensed. In this way, a plurality of refrigerants having different boiling points are sequentially condensed and evaporated, and the final low-boiling-point refrigerant is adjusted to a low pressure and vaporized and evaporated, so that a low temperature is revealed. After that, the intermediate condenser is returned to the compressor together with other refrigerant vapors, and is compressed again to repeat the above-mentioned refrigeration cycle.
According to this mixed refrigerant refrigeration circuit, -120 ° C to -130 ° C.
Temperatures of ° C can be developed.

[0011]

According to the first aspect of the present invention,
The condenser of the refrigeration circuit provided with the cooler completed independently of the dimension is thermally coupled to the cooling section of the mixed refrigerant refrigeration circuit.

According to a second aspect of the present invention, a compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points in a mixed refrigerant refrigeration circuit and a refrigerant vapor compressed by the compressor are partially condensed. And a condenser for forming a mixture of compressed condensate and uncondensed compressed vapor, a gas-liquid separator, an expansion valve, and a heat exchanger for cooling the uncondensed compressed vapor by the heat of vaporization of the compressed condensate. And an intermediate cooling stage that is connected in a plurality of stages, and a final cooling stage that is located at the final stage of these intermediate cooling stages and that includes an expansion valve and a final cooler.

According to a third aspect of the present invention, a refrigeration circuit of a dimension independent of the mixed refrigerant refrigeration circuit is formed by a compressor, a condenser, an expansion valve and a cooler.

According to a fourth aspect of the present invention, the mixed-refrigerant refrigeration circuit develops a temperature of -100 ° C or lower.

According to a fifth aspect of the present invention, a compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points, and a refrigerant condensate partially condensed by the compressor to form a compressed condensate. Multiple stages including a condenser for forming a mixture of uncondensed compressed vapor, a gas-liquid separator, an expansion valve, and a heat exchanger for cooling the uncondensed compressed vapor by the heat of vaporization of the compressed condensate. A mixed refrigerant refrigeration circuit including a connected intermediate cooling stage and a final cooling stage having an expansion valve and a final cooler located at the final stage of these intermediate cooling stages is provided. An independent dimensional refrigeration circuit is formed by a compressor, a condenser, an expansion valve and a cooler, and a cascade condenser is formed by the condenser of the independent refrigeration circuit and the final cooler of the mixed refrigerant refrigeration circuit. Than it is.

According to a sixth aspect of the present invention, a hot gas supply path for supplying the refrigerant compressed and heated by the compressor to the cooler is formed in the dimensional refrigeration circuit.

According to a seventh aspect of the present invention, a compression vapor switching valve is provided between the compressor and the cascade condenser of the dimensional refrigeration circuit, and the expansion valve and the cooler are provided between the compression vapor switching valve and the compressor. And between and are connected via a hot gas feed valve.

According to an eighth aspect of the present invention, a supercooling prevention switch for detecting the refrigerant pressure between the cascade condenser and the expansion valve of the dimensional refrigeration circuit is provided, and mixing is performed according to the opening / closing of the supercooling prevention switch. A mixed refrigerant refrigeration circuit operation control means for controlling the operation of the refrigerant refrigeration circuit is provided.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the refrigerating circuit 1 is provided with the mixed refrigerant refrigerating circuit 11 in the front stage and the independent circuit as the dimensional refrigerating circuit in the rear stage.
2 is provided.

First, the mixed refrigerant refrigeration circuit 11 in the preceding stage uses a vapor phase mixture of a plurality of refrigerants having different boiling points. A compressor 13 is provided as the device, and a condenser 14 and an auxiliary condenser 15 are connected to the compressor 13. This auxiliary capacitor 15 is
The cooling side 16 and the cooled side 17 are provided. Further, the auxiliary condenser 15 is connected to first, second and third intermediate cooling stages 18, 19, 20. These first, second and third intermediate cooling stages 18, 19, 20
Are a primary heat exchanger 23, a secondary heat exchanger 24, a tertiary heat exchanger 25, and a primary gas-liquid separator 26, a secondary gas-liquid separator 27, and a tertiary gas consisting of a cooling side 21 and a cooled side 22. Liquid separator 2
8, the primary expansion valve 29, the secondary expansion valve 30, the tertiary expansion valve 3
It consists of 1. The primary gas-liquid separator 26 connected to the cooled side 17 of the auxiliary condenser 15 is connected to the cooled side 22 of the primary heat exchanger 23 and the primary expansion valve 29, and this primary expansion valve 29 It is connected to the cooling side 21 of the exchanger 23. The secondary gas-liquid separator 27 connected to the cooled side 22 of the primary heat exchanger 23 is connected to the cooled side 22 of the secondary heat exchanger 24 and the secondary expansion valve 30. 30 is connected to the cooling side 21 of the secondary heat exchanger 24. The tertiary gas-liquid separator 28 connected to the cooled side 22 of the secondary heat exchanger 24 is connected to the cooled side 22 of the tertiary heat exchanger 25 and the tertiary expansion valve 31, and the tertiary expansion valve 31 is , Is connected to the cooling side 21 of the tertiary heat exchanger 25. Then, the third intermediate cooling stage 20 is connected to a quaternary heat exchanger 34 including a cooling side 32 and a cooled side 33 and a quaternary expansion valve 35, and further connected to a final cooling stage 36. There is. This final cooling stage 36
It comprises a cascade condenser 39 having a final expansion valve 37 and having a final cooler 38 incorporated therein.

Next, a refrigerating circuit 12 formed by an independent circuit as a dimensional refrigerating circuit is disposed in the subsequent stage of the mixed refrigerant refrigerating circuit 11 described above. This refrigeration circuit 1
Reference numeral 2 is a refrigerant circuit independent of the mixed refrigerant refrigeration circuit 11, and Freon gas R is used as a refrigerant.
-14 (American Refrigeration Association Nominal) is used. A Pi diagram (Mollier diagram) of this Freon gas R-14 is shown in FIG. Here, is a compression process, is a condensation process, is an expansion process, is an evaporation process, and shows the state of discharge refrigerant temperature +70 degreeC. Then, the compressor 40, the condenser 41, the expansion valve 42, and the cooler 43
And are formed as a closed loop circuit, and the condenser 41
Is a part of the cascade capacitor 39. Further, a compression vapor switching valve 44 is provided between the compressor 40 and the cascade condenser 39 of the dimensional refrigeration circuit 12, and between the compression vapor switching valve 44 and the compressor 40, the expansion valve 42 and the cooling. It is connected to the container 43 via a hot gas feed valve 45.

A supercooling prevention switch 46 for detecting the refrigerant pressure between the cascade condenser 39 and the expansion valve 42 of the one-dimensional refrigeration circuit 12 is provided, and the subcooling prevention switch 46 is opened / closed. A mixed-refrigerant refrigeration circuit operation control means (not shown) for controlling the operation of the mixed-refrigerant refrigeration circuit 11 is provided.

In such a structure, the cooler 43 of the refrigeration circuit 12 is installed at a place to be cooled, for example, a freezing room or the like. In this state, the mixed refrigerant refrigeration circuit 11 and the refrigeration circuit 12 are operated. First, in the mixed-refrigerant refrigeration circuit 11, the compressor 13 compresses a vapor-phase mixture of a plurality of refrigerants having different boiling points, heat-exchanges it with the condenser 14, and then cools it with the auxiliary condenser 15 to obtain the primary gas-liquid mixture. It is separated into a gas and a liquid by the separator 26, the liquid component is expanded by the primary expansion valve 29, is sent to the cooling side 21 of the primary heat exchanger 23 of the intermediate cooling stage 18, and is separated by the primary gas-liquid separator 26. The gas component is cooled, and a part thereof is liquefied depending on the temperature. The gas-liquid mixture passed through the primary heat exchanger 23 is
The secondary gas-liquid separator 27 separates it into a gas and a liquid, and the liquid component is expanded by the secondary expansion valve 30 and the intermediate cooling stage 19
Sent to the cooling side 21 of the secondary heat exchanger 24, the gas component separated by the secondary gas-liquid separator 27 is cooled, and a part thereof is liquefied according to the temperature. The gas-liquid mixture that has passed through the secondary heat exchanger 24 is separated into a gas and a liquid by the tertiary gas-liquid separator 28, and the liquid component is expanded by the tertiary expansion valve 31 and the tertiary heat exchanger 25 of the intermediate cooling stage 20. Sent to the cooling side 21, and the gas component separated by the tertiary gas-liquid separator 28 is cooled, and a part thereof is liquefied according to the temperature. Then, after being further cooled by the quaternary heat exchanger 34, a part thereof is expanded by the expansion valve 35 and contributes to the cooling action by the quaternary heat exchanger 34, and is expanded by the final expansion valve 37 and finally. Cooler 38
Cools with.

As described above, in the mixed-refrigerant refrigeration circuit 11, the first, second, and third intermediate cooling stages 18, 19,
20 and the final stage cooling stage 36 are sequentially passed to lower the temperature, and in the final cooling unit 38, a low temperature of −100 ° C. or lower is revealed. An imaginary P-i diagram (Mollier diagram) of the mixed refrigerant refrigeration circuit 11 and a P-i of Freon gas R-14.
The relationship with the diagram is shown in FIG.

In the final cooler 38 cooled in this state, the refrigerant compressed by the compressor 40 of the refrigeration circuit 12 is cooled, so that the cooler 43 portion of the refrigeration circuit 12 is -12.
A low temperature of 0 ° C to -130 ° C appears. That is, the refrigerant used is Freon gas R-14 as described above.
And the thermodynamic properties of the Freon gas R-14 has a boiling point at a gauge pressure of 0 kg / cm ² is is -128 ° C., a gauge pressure 11 kg / cm ² at -80 ° C.. Therefore, in order for this refrigerant vapor to be heat-exchanged and to be cooled and condensed, it is completely condensed and liquefied as the temperature becomes lower than −80 ° C. As described above, by the mixed refrigerant refrigeration circuit 11, −
Since 100 ° C. appears, the compressed vapor is completely cooled, condensed and liquefied in the refrigeration circuit 12 in the next stage. When the liquefied refrigerant is adjusted to 0.5 kg / cm ² and vaporized, it exhibits a low temperature of about -122 ° C.

In this way, in the dimensional refrigeration circuit 12,
Condensation pressure (high pressure) 11 kg / cm ² , evaporation pressure 0.5 kg / cm ²
It can be said that (low pressure) is in a healthy state, and Freon gas R-14 can be used in the refrigerating circuit 12 provided independently of the mixed refrigerant refrigerating circuit 11, whereby about -1
It is possible to develop a low temperature of 22 ° C.

The mixed-refrigerant refrigerating circuit 11 and the refrigerating circuit 12 are independent of each other, so that they can be easily installed and the device can be easily managed. In particular, focusing on the mixed refrigerant refrigeration circuit 11, since the refrigeration circuit 12 is interposed between the final cooling device 43 and the final cooling device 43, the mixed refrigerant refrigeration circuit 11 itself is not overloaded, and Also, it is not easily affected by load fluctuations. Therefore, stable operation of the mixed refrigerant refrigeration circuit 11 can be performed. Moreover, since the refrigerating circuit 12 including the final cooler 43 also has an independent one-stage structure, it is easy to manage the refrigerating element and perform stable operation.

As a system for expressing a temperature of -100 ° C., there is an ultra-low temperature evaporation system using a mixed refrigerant refrigeration circuit. This ultra-low temperature evaporation system is a refrigeration device that uses the thermal siphon principle without using the refrigeration circuit completed on the ultra-low temperature evaporation side.This is a refrigerant enclosed in a closed circuit called a secondary refrigerant. Is the use of the principle that the refrigerant is circulated according to the density difference and weight of the liquid phase and the gas phase of the refrigerant generated by heat exchange with the cooling section of the mixed refrigerant refrigeration circuit, and the embodiment of the present invention in which forced circulation is performed It is a very different one from the refrigeration circuit described in.

Then, when the operation is continued, the cooler 4
Frost is formed on the three parts, and it is necessary to defrost it. At this time, the compressed vapor switching valve 44 is closed and the hot gas feed valve 45 is opened. As a result, the refrigerant that has been compressed by the compressor 40 and has increased in temperature is directly sent to the cooler 43, and heats the cooler 43 from the inside. That is, the temperature rises to + 70 ° C. immediately before being cooled and condensed to the condensation pressure (high pressure) of 11 kg / cm ² . Therefore, the refrigerant compressed in the compressor 40 and having the increased temperature is directly sent to the cooler 43 to rapidly defrost the cooler 43 (hot gas defrosting action). When the defrosting ends, the compressed vapor switching valve 44 is opened and the hot gas feed valve 45 is closed to restore the circuit for performing the normal refrigeration operation. Such a defrosting operation may be automatically performed by detecting frost on the cooler 43 portion, or may be automatically performed by time control, and further manually if necessary. You may let me do it.

The refrigeration system has a system that defrosts the refrigeration operation by interrupting the refrigeration operation when the evaporator is covered with frost or ice. For example, a defrosting method for a compression refrigeration system disclosed in U.S. Pat. No. 2,271,770 does not send a refrigerant from a compressor to a condenser but supplies it to an evaporator through a heater provided separately, The high temperature refrigerant dissolves frost attached to the surface of the evaporator. That is, the point that the pressure of the compressor is indispensable during defrosting is the same as the embodiment of the present invention, but in the embodiment of the present invention, the heater is basically not used. Is different.

Further, at the time of starting, the mixed refrigerant refrigeration circuit 11
It is necessary to start the operation of the refrigeration circuit 12 after the temperature of the final cooler 38 has decreased to some extent. That is, first, the mixed refrigerant refrigeration circuit 11
Startup time is required to cool down the condenser 41 of the completed independent refrigeration circuit 12 of the dimensions. However, if the time until the refrigeration circuit 12 is activated is too long, the refrigerant in the refrigeration circuit 12 is strongly cooled and condensed to be liquefied. Therefore, starting the refrigeration circuit 12 in that state results in a compression operation in a state in which the refrigerant vapor is lean, and there is a risk of causing a physical obstacle to the compressor 40. Therefore, after the mixed refrigerant refrigeration circuit 11 is started, the state of the supercooling prevention switch 46 is observed. That is, the supercooling prevention switch 46
Constantly detects the gas pressure in the condenser 41 portion, and if the gas pressure in the condenser 41 portion falls below a preset value due to continued operation of the mixed refrigerant refrigeration circuit 11, mixed refrigerant refrigeration circuit operation control is performed. The operation of the mixed refrigerant refrigeration circuit 11 is stopped by the means. In this state, the refrigeration circuit 1
2 is a state in which it can be activated, so to speak, a standby state. Then, if the operation of the mixed refrigerant refrigeration circuit 11 is interrupted, the cooling operation by the final cooler 38 is interrupted, so that the gas pressure in the condenser 41 portion increases. Therefore, when the gas pressure becomes equal to or higher than the set pressure, the supercooling prevention switch 46 is switched, and the operation of the mixed refrigerant refrigeration circuit 11 is restarted. Turning on the switch 46 for preventing overcooling
The standby state is embodied so that the cooling operation can be always performed without adversely affecting the refrigeration circuit 12 by repeatedly turning off.

The mixed-refrigerant binary type ultra-low temperature refrigerator thus formed is used as a vacuum device. First, the exhaust equipment in the conventional vacuum apparatus includes the following. Here, the type of exhaust equipment and the vacuum range that exhibits the exhaust function are specified.

[0033] 1. Oil rotary pump 760 to 1 × 10 to ² Torr 2. Mechanical roots pump 10~5 × 10 ~ ³ Torr ^3. Dry pump 4. Oil diffusion ejector 1 × 10 to ^{1 to} 5 × 10 to ⁴ Torr 5. Oil diffusion pump 5 × 10 to ² to 1 × 10 to ⁷ Torr 6. Turbo molecular pump 7. Helium cryopump Then, as the vacuum range that exerts the exhaust function shows,
In order to reach 1 × 10 to ⁷ Torr from atmospheric pressure (760 Torr), a method is adopted in which pumps are sequentially operated to successively increase the degree of vacuum.

The structure of the exhaust pump of a general vacuum apparatus is as follows. Oil rotary pump 760 to 1 × 10 to ² Torr B. Mechanical roots pump 10~5 × 10 ~ ³ Torr C. Oil diffusion pump 5 × 10 to ² to 1 × 10 to ⁷ Torr. That is, the oil rotary pump alone cannot reach a high vacuum of 1 × 10 to ⁷ Torr, and the oil diffusion pump alone cannot operate from atmospheric pressure. In order to quickly operate the above structure, each pump is always operated and the vacuum valves are sequentially switched to operate in the vacuum range where the exhaust function is exhibited. Also, when breaking the vacuum of the high-vacuum tank (leaving the vacuum tank), each vacuum valve is closed to break the vacuum so that each pump is not exposed to the atmospheric pressure. Such a method requires a long time to reach the pressure due to the configuration of many parts and the securing of a complicated operating system.
There is a problem that it becomes a very expensive device. Higher capacity
When (high vacuum) and large capacity (high speed exhaust) are required, it becomes more expensive.

Therefore, the capacity of the main exhaust pump can be reduced by using a refrigerator in combination with the vacuum device. The principle and usage of the pump will be described below. That is, by removing the water in the vacuum chamber, it is possible to contribute to the improvement of the exhaust speed,
This is because the water molecules change in volume with pressure. Table 1 shows the degree of volume expansion due to the pressure change of water vapor.

[0036]

[Table 1]

According to this Table 1, 1 in the vacuum chamber
When there is g of water, 1x inside the vacuum chamber
At 10 to ⁶ Torr, water evaporates and expands to 1 billion liters of water vapor. If this water is allowed to condense without expanding, it will turn into 1 g of ice, reducing the capacity of the main exhaust pump in the vacuum device. The reason that the cryogenic cooler condenses the water in the vacuum system and is efficient at pumping speed is related to the saturated vapor pressure of water. The saturated vapor pressure of water and the temperature have a mutual relationship, and show a constant pressure under a constant temperature. Table 2 shows the saturated vapor pressure of water based on theoretical values.

[0038]

[Table 2]

According to Table 2, in order to condense water in a vacuum chamber of 1.0 × 10 to ⁵ Torr, a cooling section cooled to -100 ° C. is required. In the -90 ° C cooling section,
In the vacuum chamber of 1.0 × 10 to ⁵ Torr, water molecules cannot be condensed, and there is no adsorption effect (exhaust capacity).
Here, the term “adsorption effect” is used because water molecules are adsorbed by the cooling unit. That is, normally, the molecules in the vacuum chamber are reflected and fly at a speed of hundreds of US per second, but when the water molecules hit the ultra-low temperature wall, they are adsorbed as they are without being reflected. Generally, it is said that the molecules in the vacuum chamber go to a low temperature region. From this, similarly to the fact that the bore diameter of the oil diffusion pump is proportional to the exhaust speed, the larger the area of the cooling section, the larger the area of collision of water molecules, which contributes to the exhaust capacity.

From the physical properties of water described above, it has been explained that the cooler cooled to an ultralow temperature exerts its ability to adsorb moisture in the vacuum apparatus and is effective in improving the exhaust speed.
Next, how the ultra-low temperature cooling unit works in conjunction with the exhaust operation of the vacuum device will be described. The mixed-refrigerant binary refrigerator can start cooling at atmospheric pressure and normal temperature.
Therefore, cooling is started simultaneously with rough evacuation of the vacuum device, water adsorption is started during rough evacuation, and the rough evacuation time is shortened.
Since a considerable amount of water molecules are adsorbed during the rough evacuation, the main exhaust pump can exert a rapid exhaust effect at the start of the main evacuation. In addition, when the vacuum is broken (leak), when the mixed refrigerant binary refrigerator rapidly melts the frost adsorbed in the cooling section by the hot gas defrosting action as described above and the vacuum tank is opened to the atmosphere. The cooling unit is heated and stands by as an adsorption unit regenerated without dew condensation. Moreover, since the operation is very fast, it is possible to sufficiently follow the vacuum breaking (leak) speed.

[0041]

According to the first aspect of the present invention, the condenser of the refrigerating circuit having the completed cooling unit of the dimension is thermally coupled to the cooling section of the mixed refrigerant refrigerating circuit. The mixed-refrigerant refrigeration circuit can be operated smoothly without applying an excessive load to the refrigeration circuit, and because the dimensional refrigeration circuit is independent, it can be easily installed in a vacuum device, etc. Also, the structure is simple and the structure is good.

According to a second aspect of the invention, a compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points in a mixed refrigerant refrigeration circuit, and a refrigerant vapor compressed by the compressor are partially condensed. And a condenser for forming a mixture of compressed condensate and uncondensed compressed vapor, a gas-liquid separator, an expansion valve, and a heat exchanger for cooling the uncondensed compressed vapor by the heat of vaporization of the compressed condensate. And the final cooling stage including the expansion valve and the final cooler located at the final stage of these intermediate cooling stages. A mixed refrigerant refrigeration circuit can be used.

According to the third aspect of the present invention, since the refrigerating circuit of a dimension independent of the mixed refrigerant refrigerating circuit is formed by the compressor, the condenser, the expansion valve and the cooler, it can be easily installed in a vacuum device or the like. Yes, maintenance is simple and the structure is simple.

According to the fourth aspect of the present invention, the mixed refrigerant refrigeration circuit is designed to develop a temperature of -100 ° C or lower.
It is easy to select the refrigerant to be used in the three-dimensional refrigeration circuit.

According to a fifth aspect of the present invention, a compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points, and a refrigerant condensate partially condensed by the compressor to form a compressed condensate. Multiple stages including a condenser for forming a mixture of uncondensed compressed vapor, a gas-liquid separator, an expansion valve, and a heat exchanger for cooling the uncondensed compressed vapor by the heat of vaporization of the compressed condensate. A mixed refrigerant refrigeration circuit including a connected intermediate cooling stage and a final cooling stage having an expansion valve and a final cooler located at the final stage of these intermediate cooling stages is provided. An independent dimensional refrigeration circuit is formed by a compressor, a condenser, an expansion valve and a cooler, and a cascade condenser is formed by the condenser of the independent refrigeration circuit and the final cooler of the mixed refrigerant refrigeration circuit. Thus, the mixed-refrigerant refrigeration circuit can be smoothly operated without applying an excessive load to the mixed-refrigerant refrigeration circuit, and the existing completed mixed-refrigerant refrigeration circuit can be used. Since they are independent of each other, they can be easily installed in a vacuum device or the like, maintenance can be simplified, and the structure can be simple.

According to the sixth aspect of the present invention, since the hot gas supply path for supplying the refrigerant compressed and heated by the compressor to the cooler is formed in the dimensional refrigeration circuit, it is possible to effectively remove the hot gas without providing a heater or the like. The one that can make frost.

According to a seventh aspect of the present invention, a compression vapor switching valve is provided between the compressor and the cascade condenser of the dimensional refrigeration circuit, and between the compression vapor switching valve and the compressor, the expansion valve and the cooler. Since and are connected via the hot gas feed valve, the defrosting function can be easily provided.

According to an eighth aspect of the present invention, a supercooling prevention switch for detecting the refrigerant pressure between the expansion valve and the cascade condenser of the dimensional refrigeration circuit is provided, and mixing is performed according to the opening / closing of the supercooling prevention switch. Since the mixed-refrigerant refrigeration circuit operation control means for controlling the operation of the refrigerant-refrigerating circuit is provided, the mixed-refrigerant refrigeration circuit can be put in a standby state in which the cooling operation can be immediately performed even if it is started earlier. It is possible to achieve energy saving without imposing a burden on the refrigeration circuit having independent dimensions.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a Pi diagram of Freon gas R-14.

FIG. 3 is a relationship diagram showing a relative relationship between an imaginary Pi diagram of a mixed refrigerant refrigeration circuit and a refrigerant Pi diagram of a dimensional refrigeration circuit.

FIG. 4 is a circuit diagram illustrating the principle of a refrigeration circuit.

FIG. 5 is a Pi diagram of Freon gas R-14.

FIG. 6 is a circuit diagram of a conventional binary refrigeration circuit.

FIG. 7 is a circuit diagram of a conventional ternary refrigeration circuit.

FIG. 8 is a P-i diagram showing the relative relationship of refrigerants in a ternary refrigeration circuit.

[Explanation of symbols]

 11 Mixed Refrigerant Refrigeration Circuit 12 Refrigeration Circuit 13 Compressor 14 Condenser 18 Intermediate Cooling Stage 19 Intermediate Cooling Stage 20 Intermediate Cooling Stage 23 Heat Exchanger 24 Heat Exchanger 25 Heat Exchanger 26 Gas-Liquid Separator 27 Gas-Liquid Separator 28 Gas Liquid separator 29 Expansion valve 30 Expansion valve 31 Expansion valve 36 Final cooling stage 37 Final expansion valve 38 Final cooler 39 Cascade condenser 40 Compressor 41 Condenser 42 Expansion valve 43 Cooler 44 Compressed vapor switching valve 45 Hot gas feed valve 46 Switch for preventing overcooling

Claims (8)

[Claims] 1. A mixed-refrigerant binary ultra-low temperature refrigeration system characterized in that a condenser of a refrigerating circuit provided with a cooler having independent dimensions is thermally coupled to a cooling section of the mixed-refrigerant refrigerating circuit. Machine. 2. The mixed refrigerant refrigeration circuit comprises a compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points, and a condensed condensate obtained by partially condensing the refrigerant vapor compressed by the compressor. Multiple stages including a condenser for forming a mixture of uncondensed compressed vapor, a gas-liquid separator, an expansion valve, and a heat exchanger for cooling the uncondensed compressed vapor by the heat of vaporization of the compressed condensate. 2. The mixed refrigerant binary system according to claim 1, comprising a connected intermediate cooling stage and a final cooling stage which is located at a final stage of these intermediate cooling stages and includes an expansion valve and a final cooler. Type ultra-low temperature refrigerator. 3. The mixed refrigerant binary system according to claim 1, wherein the refrigeration circuit of a dimension independent of the mixed refrigerant refrigeration circuit is formed by a compressor, a condenser, an expansion valve and a cooler. Ultra low temperature refrigerator. 4. The mixed refrigerant binary ultra-low temperature refrigerator according to claim 1, wherein the mixed refrigerant refrigeration circuit develops a temperature of −100 ° C. or lower. 5. A compressor for compressing a vapor phase mixture of a plurality of refrigerants having different boiling points, and a refrigerant condensate compressed by the compressor to partially condense compressed condensate and uncondensed compressed vapor. A condenser for forming a mixture consisting of
An intermediate cooling stage connected in multiple stages with a gas-liquid separator, an expansion valve, and a heat exchanger that cools uncondensed compressed vapor by the heat of vaporization of the compressed condensate, and the final stage of these intermediate cooling stages. Then, a mixed refrigerant refrigeration circuit including a final cooling stage including an expansion valve and a final cooler is provided, and a refrigeration circuit of a dimension independent of the mixed refrigerant refrigeration circuit is provided for the compressor, the condenser, the expansion valve, and the cooler. The mixed refrigerant binary ultra low temperature refrigerator according to claim 1, wherein a cascade condenser is formed by the condenser of the independent refrigeration circuit and the final cooler of the mixed refrigerant refrigeration circuit. . 6. The mixed refrigerant binary ultra-low temperature refrigerator according to claim 1, wherein a hot gas feed passage for feeding the refrigerant compressed and heated by the compressor to the cooler is formed in the three-dimensional refrigeration circuit. . 7. A compressed vapor switching valve is provided between a compressor and a cascade condenser of a three-dimensional refrigeration circuit, and hot is provided between the compressed vapor switching valve and the compressor and between the expansion valve and the cooler. The mixed refrigerant binary ultra-low temperature refrigerator according to claim 1, wherein the refrigerant is connected via a gas feed valve. 8. A supercooling prevention switch for detecting a refrigerant pressure between a cascade condenser and an expansion valve of a three-dimensional refrigeration circuit is provided, and the mixed refrigerant refrigeration circuit is operated in accordance with opening and closing of the supercooling prevention switch. The mixed-refrigerant binary-type ultra-low temperature refrigerator according to claim 1, further comprising: a mixed-refrigerant refrigeration circuit operation control means for controlling.