Secondary refrigerant cooling circulation device and cooling circulation method

Abstract

To enable inexpensive device cost and operation cost and stable circulation supply of a secondary refrigerant.SOLUTION: A cooling circulation device 1 includes: a liquefied gas supply line 2; a secondary refrigerant reserve tank 5 that stores a secondary refrigerant as liquid; a secondary refrigerant circulation line 8 that circulates the secondary refrigerant supplied from the secondary refrigerant reserve tank 5; and a secondary refrigerant heat exchanger 9 that exchanges heat between liquefied gas in the liquefied gas supply line 2 and the secondary refrigerant in the secondary refrigerant circulation line 8. A refrigerator refrigerant line 18 for circulating a refrigerant from a refrigerator 16 is inserted into the secondary refrigerant reserve tank 5, so as to form a secondary refrigerant condensation section for condensing and liquefying the secondary refrigerant supplied to the secondary refrigerant reserve tank 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for circulating a secondary refrigerant, and more particularly to an apparatus and method for circulating a secondary refrigerant while cooling it to perform heat exchange with a load. [Background technology]

[0002] Conventionally, a method and an apparatus used for the method are known in which the secondary refrigerant in a liquid state is circulated and controlled by utilizing the cold of a low-temperature liquefied gas such as liquid nitrogen to maintain a low temperature in a load section (see Patent Documents 1 and 2). An example of the apparatus is shown in FIG. 2. In the above method, since the secondary refrigerant is liquid, the lower limit of the control temperature needs to be higher than the freezing temperature of the liquid, and in this respect there is a limit. In addition, when a lower temperature is required in the load section 51, if a refrigerant that is gaseous at room temperature and normal pressure and relatively easily liquefied is used as the secondary refrigerant, there is a possibility that the lower limit of cooling can be controlled and circulated at a temperature lower than that of a refrigerant that is liquid at room temperature and normal pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4068108 [Patent Document 2] Patent No. 5306708 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when using the cold of low-temperature liquefied gas to cool and circulate the secondary refrigerant, which is a gas that is relatively easy to liquefy, a part that liquefies the secondary refrigerant (gas-liquid separation part 52) ​​and a part that further cools and circulates it (heat exchanger 53) are required, and a continuous control panel that can precisely control each of them is required, which is expensive in terms of cost. Also, since the secondary refrigerant is a liquid (liquefied gas), there is a possibility that vapor lock will occur in the path under conditions where it is easy to vaporize on the discharge side of the circulation pump or the load supply side of the load part, so further ingenuity was required to achieve stable circulation.

[0005] In view of the above, an object of the present invention is to provide a cooling circulation method and a cooling circulation device for a secondary refrigerant that have low overall equipment and operating costs and can perform stable circulation. [Means for solving the problem]

[0006] In order to achieve the above object, a secondary refrigerant cooling and circulating device of the present invention circulates a secondary refrigerant cooled by heat exchange with a liquefied gas to a load section, the secondary refrigerant cooling and circulating device comprising a liquefied gas supply line for supplying liquefied gas, a secondary refrigerant reserve tank for storing the secondary refrigerant as a liquid, a secondary refrigerant circulation line for circulating the secondary refrigerant supplied from the secondary refrigerant reserve tank, and a secondary refrigerant heat exchanger for cooling the secondary refrigerant by heat exchange between the liquefied gas in the liquefied gas supply line and the secondary refrigerant in the secondary refrigerant circulation line, a refrigerator refrigerant line for circulating refrigerant from a refrigerator is inserted into the secondary refrigerant reserve tank, and a secondary refrigerant condensing section is formed for condensing and liquefying the secondary refrigerant supplied to the secondary refrigerant reserve tank. A secondary refrigerant bypass line that branches off from the secondary refrigerant circulation line and returns liquid secondary refrigerant to the secondary refrigerant reserve tank, and a secondary refrigerant gas vent line that returns gaseous secondary refrigerant are provided. It is characterized by the above.

[0007] In addition, the secondary refrigerant cooling and circulating device of the present invention is A branch point of the secondary refrigerant bypass line from the secondary refrigerant gas vent line is downstream of a circulation pump provided in the secondary refrigerant circulation line. It is characterized by the above.

[0008] Furthermore, the secondary refrigerant cooling and circulation device of the present invention further includes a load heat exchanger that cools the thermal fluid by exchanging heat between the secondary refrigerant in the secondary refrigerant circulation line and the thermal fluid of the load section, and is characterized in that the flow position of the secondary refrigerant circulation line in the load heat exchanger is set to a position lower than the lowest position of the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank that is set in advance.

[0009] The secondary refrigerant cooling and circulation method of the present invention is a method for circulating the secondary refrigerant to a load section using the above-mentioned cooling circulation device, characterized in that when the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank is below the lowest position, the refrigerator is started and the secondary refrigerant is condensed by the secondary refrigerant condensing section, and when the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank is above the lowest position, the opening and closing of a temperature control valve provided in the liquefied gas supply line is controlled based on the temperature of the secondary refrigerant circulating through the secondary refrigerant circulation line.

[0010] Furthermore, the method for cooling and circulating the secondary refrigerant of the present invention is characterized in that the temperature of the gas phase in the secondary refrigerant reserve tank is detected, and when the detected temperature is below a set value, operation of the refrigerator is stopped, and when the detected temperature exceeds the set value, operation of the refrigerator is resumed. Effect of the Invention

[0011] According to the cooling and circulating method and cooling and circulating device of the secondary refrigerant of the present invention, by adopting a refrigerator system in the secondary refrigerant condensation section, the amount of liquefied gas used during standby when the secondary refrigerant is not cooled and circulated can be reduced, and the operating cost can be kept low. In addition, by providing a secondary refrigerant gas vent line in the circulation path, the secondary refrigerant can be circulated stably without causing vapor lock due to evaporation. Furthermore, the secondary refrigerant vaporized by heat exchange in the load heat exchanger is easily released into the secondary refrigerant reserve tank due to the height difference.

[0012] In addition, by detecting the temperature of the gas phase in the secondary refrigerant reserve tank and stopping and restarting the refrigerator, it is possible to avoid refrigerator breakdowns, and even when the circulation supply of the secondary refrigerant is stopped, evaporation of the secondary refrigerant in the secondary refrigerant reserve tank can be prevented, making it possible to prepare for the next circulation supply. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a secondary refrigerant cooling and circulating device according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a diagram showing an example of a conventional refrigerant circulation type cooling device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1 shows a secondary refrigerant cooling circulation device 1 according to an embodiment of the present invention. The cooling circulation device 1 is generally composed of a liquefied gas supply line 2, a secondary refrigerant supply line 3, a nitrogen gas supply line 4, a secondary refrigerant reserve tank 5, a nitrogen and secondary refrigerant exhaust line 6, a secondary refrigerant downflow line 7, a secondary refrigerant circulation line 8, a secondary refrigerant heat exchanger 9, a load section 10, a load section heat exchanger 11, a secondary refrigerant bypass line 12, a secondary refrigerant gas vent line 13, and a refrigerator refrigerant line 18 for circulating the refrigerant of a refrigerator 16.

[0015] The liquefied gas supply line 2 is a path for supplying liquefied gas (such as liquid nitrogen) for condensing and liquefying the secondary refrigerant by heat exchange, and is provided with a temperature control valve (TCV) 14 and a temperature indicator controller (TIC) 15. The TCV 14 is connected to the TIC 15, TICs 21 and 26, which will be described later, and a flow meter (FIT) 27, and opening and closing of the TCV 14 is controlled by these.

[0016] Moreover, the refrigerator refrigerant line 18 is inserted into a secondary refrigerant reserve tank 5 described later, and a secondary refrigerant condensing section 17 that performs heat exchange is formed in the secondary refrigerant reserve tank 5. In the secondary refrigerant reserve tank 5, the secondary refrigerant condensing section 17 is disposed so as not to come into contact with the liquid surface of the secondary refrigerant.

[0017] The secondary refrigerant supply line 3 is a path for supplying the secondary refrigerant from a supply source (left side of the figure) to a secondary refrigerant reserve tank 5 described later, and is provided with a pressure control valve (PCV) 19 midway.

[0018] The nitrogen gas supply line 4 is a path for supplying the nitrogen gas to be sealed in the gas phase portion of the secondary refrigerant reserve tank 5 together with the secondary refrigerant, and a pressure control valve (PCV) 20 is provided midway.

[0019] The secondary refrigerant reserve tank 5 is a tank that stores the secondary refrigerant in a liquid phase, which is obtained by liquefying the secondary refrigerant supplied through the secondary refrigerant supply line 3 by the secondary refrigerant condenser 17. A temperature indicator controller (TIC) 21 and a liquid level indicator alarm (LIA) 22 are provided on the wall of the secondary refrigerant reserve tank 5. The TIC 21 is connected to the TCV 14 of the liquefied gas supply line 2 and the refrigerator 16. The LIA 22 is provided with sensors corresponding to a preset minimum position (L) and maximum position (H) in order to detect the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank 5. When the liquid level exceeds L, the secondary refrigerant starts to flow down to the secondary refrigerant flow-down line 7 described later. When the liquid level exceeds H, an alarm is issued and the PCV 19 is closed to stop the supply of the secondary refrigerant gas to the secondary refrigerant reserve tank 5.

[0020] The nitrogen and secondary refrigerant exhaust line 6 is a path for discharging the gas-phase secondary refrigerant and nitrogen gas at the top of the secondary refrigerant reserve tank 5 when the pressure inside the tank 5 reaches or exceeds a certain level, and is provided with a pressure control valve (PCV) 23 and a check valve (CV) 24 along the way.

[0021] The secondary refrigerant downflow line 7 is a path that supplies the secondary refrigerant stored at the bottom of the secondary refrigerant reserve tank 5 to the secondary refrigerant circulation line 8 described later, and has one end connected to the secondary refrigerant reserve tank 5 and the other end connected to the secondary refrigerant circulation line 8.

[0022] The secondary refrigerant circulation line 8 is a path for circulating the secondary refrigerant liquefied in the secondary refrigerant reserve tank 5 for use in the load heat exchanger 11 described below, and is provided with a circulation pump (RP) 25, a temperature indicator controller (TIC) 26, and a flow meter (FIT) 27 along the way. The RP 25 is connected to the LIA 22 of the secondary refrigerant reserve tank 5, and is designed to start only when the liquid level in the tank is above L. The TIC 26 and FIT 27 are also connected to the TCV 14.

[0023] The secondary refrigerant heat exchanger 9 is a heat exchanger that exchanges heat between the liquefied gas supplied to the liquefied gas supply line 2 and the secondary refrigerant supplied to the secondary refrigerant circulation line 8, thereby making the temperature of the secondary refrigerant in the secondary refrigerant circulation line 8 lower.

[0024] The load section heat exchanger 11 is a heat exchanger for lowering the temperature of the thermal fluid generated in the load section 10 by heat exchanging between the secondary refrigerant supplied to the secondary refrigerant circulation line 8 and the thermal fluid generated in the load section 10, thereby reducing the load on the load section 10. The liquid level position of the secondary refrigerant circulation line 8 in the load section heat exchanger 11 is lower by a height h than the lowest position (L) of the liquid level in the secondary refrigerant reserve tank 5 (see FIG. 1).

[0025] The secondary refrigerant bypass line 12 is a path for returning the secondary refrigerant to the liquid phase portion of the secondary refrigerant reserve tank 5 at a branch point 28 immediately after the RP 25 in the secondary refrigerant circulation line 8. By using the secondary refrigerant bypass line 12 to return and circulate the secondary refrigerant to the secondary refrigerant reserve tank 5, it is possible to prevent the RP 25 from running dry and to properly maintain the startup of the RP 25, thereby protecting the RP 25.

[0026] The secondary refrigerant gas vent line 13 is a path that branches off from the secondary refrigerant bypass line 12 and returns the secondary refrigerant to the gas phase portion of the secondary refrigerant reserve tank 5, thereby releasing gas generated in the secondary refrigerant. By releasing gas in the circulating secondary refrigerant using the secondary refrigerant gas vent line 13, it serves to prevent cavitation and vapor lock from occurring in the secondary refrigerant circulation line 8.

[0027] Using the cooling circulation device 1 configured as above, the cooling circulation method of the present invention is carried out as follows.

[0028] First, in the secondary refrigerant supply line 3, the gasified secondary refrigerant is supplied to the secondary refrigerant reserve tank 5 via the PCV19.

[0029] On the other hand, while the refrigerator 16 is started, the refrigerant circulates in the refrigerator refrigerant line 18, and the liquid level detected by the LIA 22 provided on the wall surface of the secondary refrigerant reserve tank 5 is lower than the lowest position (L), TIC21 is controlled to be constant, and the refrigerator refrigerant line 18 in the secondary refrigerant reserve tank 5 functions as the secondary refrigerant condensation section 17.

[0030] The gasified secondary refrigerant comes into contact with the secondary refrigerant condenser 17 in the secondary refrigerant reserve tank 5, exchanges heat with it, and liquefies and flows down to the bottom of the tank. At this time, nitrogen gas supplied from the nitrogen gas supply line 4 via the PCV 20 is sealed in the gas phase part in the secondary refrigerant reserve tank 5, and an inactive state is maintained. The liquefied secondary refrigerant (liquid phase part) is stored in the bottom part of the secondary refrigerant reserve tank 5. When the pressure inside the secondary refrigerant reserve tank 5 reaches a certain level or higher, the PCV 23 opens, and the non-liquefied secondary refrigerant (gas phase part) is discharged from the nitrogen and secondary refrigerant exhaust line 6 together with the sealed nitrogen gas.

[0031] When the secondary refrigerant continues to accumulate in the secondary refrigerant reserve tank 5 and the liquid level reaches a position above L, it is determined that a sufficient amount of secondary refrigerant is present in the secondary refrigerant reserve tank 5, and the RP 25 starts up, causing the secondary refrigerant to flow through the secondary refrigerant downflow line 7 to the secondary refrigerant circulation line 8. The temperature and flow rate of the secondary refrigerant flowing through the secondary refrigerant circulation line 8 can be confirmed by the TIC 26 and the FIT 27.

[0032] When the secondary refrigerant has circulated to a certain extent and the value indicated by FIT 27 has reached a certain value, the TCV 14 is controlled to adjust the supply amount of liquefied gas so that TIC 26 becomes the set value for the secondary refrigerant circulating through the secondary refrigerant circulation line 8. Also, there is no problem if the temperature indicated by TIC 15 is equal to or higher than the set value (e.g., -100°C), but if it is equal to or lower than the set value, the TCV 14 is forcibly shut off to prevent the secondary refrigerant from freezing in the secondary refrigerant heat exchanger 9.

[0033] Thereafter, when a sufficient amount of secondary refrigerant is stored in the secondary refrigerant reserve tank 5 and the liquid level position reaches a position above H, an alarm is issued by LIA22 and at the same time, PCV19 is controlled to stop the supply of secondary refrigerant to the secondary refrigerant reserve tank 5.

[0034] Meanwhile, in the secondary refrigerant circulation line 8, the secondary refrigerant is circulated by the RP 25. Just after passing through the RP 25, a part of the secondary refrigerant branches at a branch point 28. From the branch point 28, a secondary refrigerant bypass line 12 and a secondary refrigerant gas vent line 13 are connected to the secondary refrigerant reserve tank 5, and both are connected to a liquid phase portion and a gas phase portion of the secondary refrigerant reserve tank 5, respectively.

[0035] The secondary refrigerant that has passed through the secondary refrigerant bypass line 12 is returned to the liquid phase portion of the secondary refrigerant reserve tank 5, and is supplied again to the secondary refrigerant circulation line 8 via the secondary refrigerant downflow line 7, and passes through the RP 25. Circulating the secondary refrigerant in this manner serves to prevent the RP 25 from running dry, and to properly start and protect the RP 25.

[0036] The secondary refrigerant that has passed through the secondary refrigerant gas vent line 13 is returned to the gas phase portion of the secondary refrigerant reserve tank 5, and the gas in the secondary refrigerant is separated in the gas phase portion of the secondary refrigerant reserve tank 5. Releasing the gas in the circulating secondary refrigerant in this manner serves to prevent cavitation and vapor lock from occurring within the secondary refrigerant circulation line 8.

[0037] The secondary refrigerant circulating through the secondary refrigerant circulation line 8 has its temperature and flow rate controlled by the TIC 26 and the FIT 27, and can efficiently exchange heat with the load section 10 in the load section heat exchanger 11. In other words, the load section 10 can be efficiently cooled. The temperature control of the secondary refrigerant by the TIC 26 is performed by controlling the opening and closing of the TCV 14 connected to the TIC 26.

[0038] Furthermore, if the secondary refrigerant flow position in the load heat exchanger 11 is arranged at a position lower than the liquid level position L of the secondary refrigerant reserve tank 5 (see FIG. 1), the secondary refrigerant vaporized by heat exchange in the load heat exchanger 11 is likely to be discharged into the secondary refrigerant reserve tank 5 through the secondary refrigerant downflow line 7 due to the height difference h. The secondary refrigerant is also likely to be discharged into the secondary refrigerant reserve tank 5 through the secondary refrigerant gas vent line 13 provided alongside. This makes it possible to prevent vapor lock from occurring in the path of the secondary refrigerant circulation line 8, thereby enabling stable circulation of the secondary refrigerant.

[0039] Furthermore, in order to prevent the secondary refrigerant returned from the secondary refrigerant gas vent line 13 to the gas phase portion of the secondary refrigerant reserve tank 5 from freezing due to a drop in the temperature around the secondary refrigerant condenser 17, a lower limit value for TIC21 is set, and the operation of the refrigerator 16 is controlled to stop below the lower limit value. Thereafter, when TIC21 becomes higher than the set lower limit value, the refrigerator 16 is allowed to resume operation.

[0040] By controlling in this manner, breakdowns in the refrigerator 16 are avoided, and even when the circulating supply of the secondary refrigerant is stopped, evaporation of the secondary refrigerant in the secondary refrigerant reserve tank 5 is prevented, making it possible to prepare for the next circulating supply, thereby enabling safe operation of the device.

[0041] As an apparatus, a method of forming a secondary refrigerant condensation section by extending the liquefied gas supply line 2 and inserting it into the secondary refrigerant reserve tank 5 is also conceivable, but by adopting a refrigerator system for the secondary refrigerant condensation section 17 as in this embodiment, the amount of liquefied gas used during standby when the secondary refrigerant is not cooled and circulated can be reduced, which is advantageous in terms of operating costs. Also, rather than extending the liquefied gas supply line 2, installing a refrigerator 16 and providing a refrigerator refrigerant line 18 is more advantageous in terms of the initial cost of the apparatus. EXAMPLES

[0042] The following describes the case where tetrafluoromethane is used as the secondary refrigerant and liquid nitrogen is used as the liquefied gas. Tetrafluoromethane has a boiling point of -128°C at atmospheric pressure, a freezing point of -184°C at atmospheric pressure, a critical point temperature of -45.6°C, and a critical point pressure of 3.7MPa. It is a liquefied gas that is easily liquefied at an atmosphere of -80°C.

[0043] When tetrafluoromethane is applied to the cooling circulation system 1 of FIG. 1, the inside of the secondary refrigerant reserve tank 5 should be sufficiently purged with nitrogen gas in advance, and care should be taken to prevent moisture from being mixed in.

[0044] Next, the set value of TIC 21 is set to −80° C., and refrigerator 16 is started. At this time, the set value of TIC 15 is set to −100° C., which is a temperature sufficiently higher than the freezing point of tetrafluoromethane.

[0045] Then, tetrafluoromethane (boiling point: approximately -75°C) decompressed to about 1.0 MPa by PCV 19 is supplied to secondary refrigerant reserve tank 5 and gradually liquefied by heat exchange with the refrigerant of the refrigerator in secondary refrigerant condenser 17. The liquefied tetrafluoromethane begins to be supplied from the bottom of secondary refrigerant reserve tank 5 through secondary refrigerant downflow line 7 to secondary refrigerant circulation line 8. As the amount of liquefaction increases further, it begins to accumulate at the bottom of secondary refrigerant reserve tank 5, and the liquid level gradually rises within tank 5. Condensation continues in secondary refrigerant condenser 17 while the liquid level detected by LIA 22 is below the lowest position (L).

[0046] When it is detected that the liquid level has risen and reached or exceeded the minimum position (L) of LIA22, RP25 is activated, and tetrafluoromethane circulates in the secondary refrigerant circulation line 8, first exchanging heat with liquid nitrogen in the secondary refrigerant heat exchanger 9, and then being supplied to the load section heat exchanger 11, where heat exchange with the load section 10 takes place.

[0047] If the liquid level in the secondary refrigerant reserve tank 5 rises further and reaches the highest position (H) of the LIA 22, an alarm is issued, the secondary refrigerant supply source (left side of the figure) and PCV 19 are closed, and the supply of secondary refrigerant to the secondary refrigerant reserve tank 5 is stopped.

[0048] Meanwhile, in the secondary refrigerant circulation line 8, the flow rate of tetrafluoromethane is detected by the FIT 27, and when the flow rate reaches a set value, the TCV 14 is controlled by the TIC 26, and the tetrafluoromethane is cooled to the set value (for example, -150°C). After the liquid temperature of the sufficiently cooled tetrafluoromethane is increased to a certain degree by heat exchange with the load section 10 in the load section heat exchanger 11, it is circulated to the secondary refrigerant heat exchanger 9 and cooled again, repeating this cycle. Since the circulatory supply is performed in this manner, the tetrafluoromethane can be stably cooled and circulated in a liquid state.

[0049] In addition, for the circulating tetrafluoromethane, a secondary refrigerant bypass line and a secondary refrigerant gas vent line 13 are provided at branch point 28, so that a portion of the liquid phase and gas phase can be returned to the secondary refrigerant reserve tank 5, making it possible to perform a more stable circulatory supply.

[0050] In addition, when the load applied to the load section 10 is large, some of the tetrafluoromethane vaporizes in the load section heat exchanger 11 and remains in the path, which may cause vapor lock. However, in the cooling circulation device 1 of the present invention, the flow position of the secondary refrigerant circulation line 8 in the load section heat exchanger 11 is set to a position lower than the position L of the secondary refrigerant reserve tank 5 (see h in FIG. 1), so that the height difference h makes it easier for the vaporized tetrafluoromethane to return to the secondary refrigerant reserve tank 5 through the secondary refrigerant downflow line 7. In addition, it also makes it easier for the tetrafluoromethane to return to the secondary refrigerant reserve tank 5 through the secondary refrigerant gas vent line 13 provided in parallel. Therefore, the circulation of tetrafluoromethane is more stable.

[0051] In the above embodiment, tetrafluoromethane is used as the secondary refrigerant, but other liquefied gases such as trifluoromethane or highly volatile liquids (fluorine-based solvents, etc.) can also be used. In addition, liquid nitrogen is used as the liquefied gas, but other liquefied gases can also be used. In addition, the positions at which the temperature indicator / regulator 26 and the flow meter 27 are provided in the secondary refrigerant circulation line 8 are not necessarily fixed, and it is sufficient that they are installed so that the secondary refrigerant circulates without any hindrance. [Explanation of symbols]

[0052] 1···Cooling circulation system, 2···Liquefied gas supply line, 3···Secondary refrigerant supply line, 4···Nitrogen gas supply line, 5···Secondary refrigerant reserve tank, 6···Nitrogen and secondary refrigerant exhaust line, 7···Secondary refrigerant flow-down line, 8···Secondary refrigerant circulation line, 9···Secondary refrigerant heat exchanger, 10···Load section, 11···Load section heat exchanger, 12···Secondary refrigerant bypass line, 13···Secondary refrigerant gas vent line, 14···Temperature control valve (TCV), 15···Temperature indicator controller (TIC), 16·· Refrigeration unit, 17...Secondary refrigerant condensation section, 18...Refrigeration unit refrigerant line, 19...Pressure control valve (PCV), 20...Pressure control valve (PCV), 21...Temperature indicating controller (TIC), 22...Liquid level indicator alarm (LIA), 23...Pressure control valve (PCV), 24...Check valve (CV), 25...Circulation pump (RP), 26...Temperature indicating controller (TIC), 27...Flow meter (FIT), 28...Branch point, 51...Load section, 52...Gas-liquid separation section, 53...Heat exchanger, h...Height difference

Claims

1. In a secondary refrigerant circulation device, a secondary refrigerant cooled by heat exchange with a liquefied gas is circulated to a load section, a liquefied gas supply line for supplying liquefied gas; a secondary refrigerant reserve tank for storing the secondary refrigerant in liquid form; a secondary refrigerant circulation line for circulating the secondary refrigerant supplied from the secondary refrigerant reserve tank; a secondary refrigerant heat exchanger that exchanges heat between the liquefied gas in the liquefied gas supply line and the secondary refrigerant in the secondary refrigerant circulation line to cool the secondary refrigerant; Equipped with a secondary refrigerant condensing section that condenses and liquefies the secondary refrigerant supplied to the secondary refrigerant reserve tank by inserting a refrigerator refrigerant line through which the refrigerant from the refrigerator circulates into the secondary refrigerant reserve tank; A secondary refrigerant circulation device characterized in that a secondary refrigerant bypass line branching off from the secondary refrigerant circulation line for returning liquid secondary refrigerant to the secondary refrigerant reserve tank and a secondary refrigerant gas vent line for returning gaseous secondary refrigerant are provided.

2. A cooling circulation device as described in claim 1, characterized in that the branching point of the secondary refrigerant bypass line from the secondary refrigerant gas vent line is downstream of a circulation pump provided in the secondary refrigerant circulation line.

3. The secondary refrigerant circulation line further includes a load heat exchanger for exchanging heat between the secondary refrigerant and the thermal fluid of the load to cool the thermal fluid, 3. The cooling circulation device according to claim 1, wherein the flow position of the secondary refrigerant circulation line in the load heat exchanger is set to a position lower than a predetermined minimum position of the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank.

4. A method for circulating a secondary refrigerant to a load section by using the cooling circulation device according to claim 3, comprising the steps of: When the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank is lower than the lowest position, the refrigerator is started and the secondary refrigerant is condensed by the secondary refrigerant condensing unit; A method for circulating a secondary refrigerant, characterized in that when the liquid level of the secondary refrigerant in the secondary refrigerant reserve tank is above the lowest position, opening and closing of a temperature control valve provided in the liquefied gas supply line is controlled based on the temperature of the secondary refrigerant circulating through the secondary refrigerant circulation line.

5. 5. The method for circulating a secondary refrigerant according to claim 4, further comprising the steps of: detecting a temperature of a gas phase portion in said secondary refrigerant reserve tank; stopping operation of said refrigerator when the detected temperature is below a set value; and restarting operation of said refrigerator when the detected temperature is above the set value.

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