WO2014083810A1

WO2014083810A1 - Refrigerant cooling device and method

Info

Publication number: WO2014083810A1
Application number: PCT/JP2013/006837
Authority: WO
Inventors: 高広石川; 英一郎小林
Original assignee: 日曹エンジニアリング株式会社
Priority date: 2012-11-27
Filing date: 2013-11-21
Publication date: 2014-06-05
Also published as: JPWO2014083810A1

Abstract

[Problem] To enable, by means of a simple configuration, temperature controllability of ±1°C for a target refrigerant in a refrigerant cooling device and method. [Solution] A refrigerant cooling device equipped with a reservoir (1) storing a low-temperature liquid, a container (2) containing a refrigerant that cools an object to be cooled, a heat exchanger (3) that exchanges heat energy between a liquefied gas of the low-temperature liquid and the refrigerant, a supply pipeline (10) that supplies the low-temperature liquid in the reservoir (1) or a liquefied gas thereof to the heat exchanger (3), a valve means (6) provided in the supply pipeline (10), a discharge pipeline (11) that discharges liquefied gas from the heat exchanger (3) to outside of the system, and a control means (7) that controls the supply of the low-temperature liquid or the liquefied gas thereof to the heat exchanger (3), or the amount supplied, by controlling the opening/closing of or the degree of opening of the valve means (6), the refrigerant cooling device being characterized in that the control means (7) has a temperature sensor (8) provided on a discharge pipe section (11a) of the discharge pipeline (11) which is inside the container, with the valve means (6) being controlled and the refrigerant being maintained at a set temperature on the basis of the temperature of the used liquefied gas flowing in the discharge pipeline (11), as detected by the temperature sensor (8).

Description

Refrigerant cooling apparatus and method

The present invention particularly relates to a refrigerant cooling apparatus and method for cooling a refrigerant used as a cooling source for a low-temperature reaction or the like to a target set temperature using cold when vaporizing a low-temperature liquid such as liquid nitrogen.

For example, when a substance is cooled to a set temperature or a chemical reaction is performed at a low set temperature, a refrigerant (such as methanol, ethanol, acetone, or methylene chloride as a low-temperature refrigerant) is often used. The refrigerant is cooled by a cryogen in addition to being cooled by a refrigerator. In addition, dry ice and various low-temperature liquefied gases such as liquid nitrogen, liquid oxygen, and liquid air are used as cryogens for cooling the refrigerant to a low temperature, for example, −50 ° C. or lower, which is difficult with a refrigerator.

5 (a) and 5 (b) show two device structures disclosed in Patent Document 1 as refrigerant cooling devices for cooling the refrigerant with a cryogen. The basis of each device is a storage tank 1 storing a cryogenic liquid, a tank or container 2 containing a refrigerant for cooling an object to be cooled, a heat exchanger 5 for exchanging thermal energy between the liquefied gas of the cryogenic liquid and the refrigerant, The low temperature liquid in the storage tank 1 or the liquefied gas thereof is supplied to the heat exchanger 5, the valve means (switching valve) V 1 provided in the supply pipe, and the liquefied gas is discharged from the heat exchanger 5 to the outside of the system. A control means (TIC: temperature indicating controller) 3 is provided for controlling the valve opening and closing of the valve means V1 with respect to the supply of the low temperature liquid or the liquefied gas supplied to the exhaust pipe 12 and the heat exchanger 5 or the supply amount thereof. Reference numeral 4 denotes an evaporator for liquid nitrogen communicated with the storage tank 1 by a pipe 11. The pipe 11 has a valve means (switching valve) V2 that is operated by a signal from the control means 3 in the same manner as the valve means V1. A discharge line 12 of the heat exchanger 5 communicates with the line 11 between the valve means V2 and the evaporator 4.

5A, the heat exchanger 5 is disposed in the container 2, and the control means 3 detects the temperature of the refrigerant in the container 2 with a temperature sensor, and based on the detected temperature. The valve means V1 is controlled to open or close to cool the refrigerant to the set temperature. On the other hand, in the apparatus structure of FIG. 5B, the heat exchanger 5 is attached outside the container 2 and the refrigerant in the container 2 is circulated to the heat exchanger 5 by the pump P, and the control means 3 is in the container 2. The temperature of the refrigerant is detected by a temperature sensor, and the valve means V1 is controlled to open or close based on the detected temperature to cool the refrigerant to a set temperature.

More specifically, if the low-temperature liquid is liquid nitrogen, the liquid nitrogen sent from the storage tank 1 exchanges heat with the refrigerant by the heat exchanger 5 to cool the refrigerant (methane dichloride). When the refrigerant is cooled to a predetermined temperature, the temperature indicating controller which is the control means 3 is operated to operate the valve means V1 and V2, that is, the valve means V1 is closed and the valve means V2 is opened. To the evaporator 4 where it is vaporized and sent out of the system where it is used. On the other hand, the refrigerant is used for cooling outside the container 2 and returned to the container 2 again. When the refrigerant temperature in the container 2 rises, the control means 3 is actuated again, the valve means V1 is opened, the valve means V2 is closed, and the liquid nitrogen in the storage tank 1 is in the container 2 or a heat exchanger outside the container 2. Through 5, the refrigerant is cooled to the set temperature.

Japanese Utility Model Publication No. 60-4049

In the above refrigerant cooling apparatus, the control means detects the temperature of the refrigerant in the container with a temperature sensor, and opens and closes the valve means and adjusts and controls the valve opening based on the detected temperature. In this control method, it has been considered that it is appropriate to directly detect the temperature of the refrigerant to be cooled and control the valve means on the supply line side based on the detected temperature (for example, Japanese Patent Laid-Open No. 9-4954). Temperature control method).

As a result of verifying the above conventional method as a method for controlling the temperature of the medium in the container using the refrigerant cooling device as shown in FIG. 1, the present inventors have shown FIG. 3 as a comparative example of the present invention. As shown in (b), it was found difficult to achieve temperature controllability of ± 1 ° C. as the temperature of the refrigerant. Accordingly, an object of the present invention is to make it possible to realize a temperature controllability of ± 1 ° C. as a target refrigerant in a refrigerant cooling device and method with a simple configuration, thereby improving quality and contributing to expanded applications.

In order to achieve the above object, the present invention according to claim 1 includes a storage tank storing a low-temperature liquid such as liquid nitrogen, a container containing a refrigerant for cooling an object to be cooled, a liquefied gas of the low-temperature liquid, and the refrigerant. A heat exchanger for exchanging thermal energy with the heat exchanger, a supply line for supplying the low-temperature liquid of the storage tank or the liquefied gas thereof to the heat exchanger, valve means provided in the supply line, and the heat The exhaust pipe for discharging the liquefied gas from the exchanger to the outside of the system, the low-temperature liquid supplied to the heat exchanger or the supply of the liquefied gas, or the supply amount thereof, the valve opening / closing of the valve means or the valve opening degree is controlled. In the refrigerant cooling apparatus provided with the control means, the control means has a temperature sensor provided in a discharge pipe portion in the container, and the discharge pipe is detected by the temperature sensor. Based on the detected temperature of spent liquefied gas flowing through It is characterized in that it allows maintaining the refrigerant by controlling the valve means to the set temperature Te.

In the configuration example of the present invention shown in FIG. 1, the heat exchanger 3 is not limited to the configuration provided in the container containing the refrigerant as shown in FIG. 1 and FIG. 5 (a), but outside the container as shown in FIG. 5 (b). A configuration may be employed in which the refrigerant in the container is circulated by a pump or the like. The valve means 6 may be either an inexpensive switching valve that switches between opening and closing or an expensive flow rate adjusting valve that adjusts the valve opening. A configuration in which the used liquefied gas discharged from the exhaust pipe 11 is exhausted into the air, and a structure in which the used liquefied gas is transferred from the evaporator communicated to the storage tank via the pipe and the valve means as illustrated in FIG. But you can. In addition, the container containing the refrigerant of the present invention has a configuration in which an object to be cooled such as a reactor is immersed in the refrigerant in the container as shown in FIG. 1 and is cooled. Any configuration may be employed in which it is sent to an evaporator (see, for example, FIG. 1 and FIG. 2 of Japanese Patent No. 4666347 and FIG. 2 of Japanese Patent No. 4679199) and cooled.

The present invention as described above is more preferably embodied as follows.
(A) The heat exchanger has a liquefied gas conduit wound in a coil shape or a spiral shape as in claim 2.
(A) The pipe line is composed of a copper pipe as in claim 3 and has a plurality of grooves formed along the longitudinal direction of the pipe on the inner surface of the copper pipe.
(C) A refrigerant cooling method according to a fourth aspect uses the refrigerant cooling device according to any one of the first to third aspects to heat a liquefied gas of liquid nitrogen and a refrigerant that cools an object to be cooled by a heat exchanger. It is characterized by keeping the refrigerant at a constant temperature by exchanging.

According to the first aspect of the present invention, the control means has a temperature sensor provided in the exhaust pipe portion of the exhaust pipe in the exhaust pipe, and detection of the used liquefied gas flowing through the exhaust pipe detected by the temperature sensor. When the valve means attached to the supply pipe line is controlled to open and close based on the temperature, or the valve opening degree is controlled so as to maintain the refrigerant at the set temperature, as illustrated in FIG. As the target refrigerant, a temperature controllability of ± 1 ° C. can be easily realized, thereby improving the refrigerant quality.

In the invention of claim 2, since the heat exchanger is a liquefied gas pipe wound in a coil shape or a spiral shape, that is, a general-purpose product that is generally used, simplicity can be maintained.

In the invention of claim 3, since the conduit is made of a copper tube and has a plurality of grooves formed along the longitudinal direction of the tube on the inner surface of the copper tube, the smooth tube is evident from the comparison of FIG. Compared with the above, the use efficiency of the low temperature liquid such as liquid nitrogen can be improved by the function of the droplet separation by centrifugal force and the increase of the heat transfer coefficient.

In the invention of claim 4, the above-described advantages can be provided as a refrigerant cooling method, and since liquid nitrogen is used as the low-temperature liquid, the refrigerant can be controlled at any temperature from 0 to −120 ° C. and with an automatic temperature controllability of ± 1 ° C. It becomes possible.

It is a block diagram which shows typically the refrigerant | coolant cooling device of an example. (A) is the A section enlarged view of FIG. 1, (b) is sectional drawing of the piping part in a container among the exhaust pipe paths of FIG. (A) And (b) is a graph which shows the relationship between heat-medium temperature and time when it controls by the control means of this invention, and the conventional control means. (A) And (b) is a graph when the cooling capacity when investigating a smooth pipe and a grooved pipe as a pipe line which forms the heat exchanger of Drawing 1 is examined. (A) And (b) has shown two structures of patent document 1. FIG.

(Apparatus structure) The refrigerant cooling apparatus of FIG. 1 includes a storage tank 1 storing liquid nitrogen as a cryogen or a low-temperature liquid, a container 2 containing a refrigerant for cooling an object to be cooled 4, a liquefied gas of liquid nitrogen, and a refrigerant. A heat exchanger 3 for exchanging heat energy between them, a supply line 10 for supplying liquid nitrogen in the storage tank 1 or its liquefied gas to the heat exchanger 3, and valve means 5 and 6 provided in the supply line 10; The exhaust pipe 11 for discharging the liquefied gas from the heat exchanger 3 to the outside of the system, and the supply or supply amount of liquid nitrogen or the liquefied gas supplied to the heat exchanger 3 are controlled by opening and closing the valve means 6. A control unit 7 is provided. And as for the principal part, the control part 7 has the temperature sensor 8a provided in the exhaust pipe part 11a in the container 2 among the exhaust pipe paths 11, and flows through the exhaust pipe path 11 detected by this temperature sensor 8a. The valve means 6 is controlled based on the detected temperature of the used liquefied gas (nitrogen gas) so that the refrigerant in the container 2 can be maintained at the set temperature.

The storage tank 1 is called a self-pressurized container, and a tank 1A storing liquid nitrogen is disposed in a protective tank 1B on the outside while maintaining a high vacuum. The tank 1A includes a replenishing port 10a, a pressurizing pipe 14, a discharge pipe 15, and the like. And structurally, when the gas release valve 16 is closed and the pressurization valve 17 is opened, the liquid nitrogen evaporates in the pressurization pipe 14, and the internal pressure rises to push the internal liquid nitrogen toward the supply pipe line 10. It has become. In order to stop pumping out liquid nitrogen, the gas release valve 16 is opened, and the pressurizing valve 17 and the liquid take-out switching valve as the valve means 5 are closed. The gas release valve 16 is normally opened. The tank 1A is additionally provided with a pressure gauge 19 indicating internal pressure, safety valves 18a and 18b for releasing gas when the internal pressure rises excessively, and the like. Reference numeral 13 denotes a carriage.

The container 2 includes a main body 20 that is large enough to accommodate the refrigerant and the heat exchanger 3 in the inner space, an upper cover 21 that closes the upper opening of the main body 20, and a door 22 provided on the upper cover 21. A heat insulating material 24 is attached to the outer peripheral wall of the main body 20. The door 22 opens and closes an opening provided in the upper cover 21 so that the object to be cooled 4 can be taken in and out of the refrigerant in the main body 20. Inside the main body 20, the heat exchanger 3 is installed in a state of being held by a plurality of support members 23 and the like.

The heat exchanger 3 has a liquefied gas conduit 30 in which a copper pipe excellent in heat conduction is wound in a coil shape or a spiral shape. A plurality of grooves 31 extending along the pipe longitudinal direction as shown in FIG. 2B are provided on the inner peripheral surface of the pipe 30 so as to equally divide the periphery. The inlet side of the pipe line 30 constituting the heat exchanger 3 is connected to a corresponding end of the supply pipe line 10 for supplying liquid nitrogen in the storage tank side tank 1A. The outlet side of the conduit 30 is connected to the corresponding end of the exhaust conduit 11.

The supply pipe line 10 and the discharge pipe line 11 are disposed inside and outside the container through the upper cover 21 together. The supply pipe line 10 has a liquid take-out switching valve which is a valve means 5 provided on the tank 1A side, and a valve means 6 which is provided on the downstream side of the supply pipe 10 and operates according to a signal from the control unit 7. ing. The valve means 6 is an example of a switching valve that switches between opening and closing, but may be replaced with a flow rate adjusting valve that variably adjusts the valve opening.

The exhaust pipe 11 is a pipe for exhausting used nitrogen gas, but it may be sent to a use location through a processing system as shown in FIG. A temperature sensor 8 a is attached to the inside of the exhaust pipe portion 11 a in the container 2 in the exhaust pipe path 11. The temperature sensor 8 a detects the temperature of the used nitrogen gas flowing through the exhaust pipe portion 11 a and transmits it to the control unit 7.

That is, when the switching valve is used as the valve means 6 on the basis of the detected temperature of the used nitrogen gas flowing through the exhaust pipe portion 11a detected by the temperature sensor 8a, the control unit 7 controls the opening / closing or When a flow rate adjusting valve is used as the means 6, the valve opening degree is controlled. As the control device, a commercially available temperature indicating controller or the like can be used. In the examples described later, a temperature indicating controller manufactured by Nisso Engineering Co., Ltd. was used.

In the above refrigerant cooling device, as the object to be cooled 4, a pipe-type flow mixing device or a reaction bottle for a low temperature reaction test is placed in the refrigerant in the container 2 as shown in FIG. It is assumed that it is cooled to a set temperature in a state where it is supported by immersion. The reaction bottle shown in the figure is provided with a stirrer 9 for mixing the reaction solution in the bottle, a temperature sensor 8c for detecting temperature, and the like. However, the usage is not limited to this, and for example, the refrigerant cooled to the set temperature in the container 2 may be circulated and supplied to other use locations by a pump or the like.

(Example 1) FIG. 3 shows the following Table 1 obtained in a test as a method of controlling the temperature using the above-described refrigerant cooling device and using hydrofluoroether (hereinafter referred to as a heat medium) as a refrigerant. The graph shows the relationship between the passage of time and the heat medium temperature. (A) shows the test result when controlled by the control means of the present invention, and (b) shows the test result when controlled by the conventional control means. Each graph of (a) and (b) plots the time (min) on the horizontal axis and the heat medium temperature (° C.) on the vertical axis on judging the superiority or inferiority of the temperature controllability. .

In this test example, the heat medium was filled in the stirring tank as the container 2, the above-described coiled pipe line was used as the heat exchanger 3, and a switching valve was used as the valve means 6. In addition, the temperature indicating controller is used as the control unit 7 and the heat medium in the container 2 is set to be kept at the set temperature TS = −120 °. In the temperature control of the present invention, the temperature indicating controller is the valve means 6 based on the detected temperature of the used nitrogen gas flowing through the exhaust pipe portion 11a detected by the temperature sensor 8a attached to the exhaust pipe portion 11a. Is automatically controlled to open or close the switching valve. On the other hand, in the conventional temperature control, the temperature indicating controller is the valve means 6 based on the detected temperature of the refrigerant in the container 2 detected by the sensor 8b provided in the container 2 shown in FIG. A signal was sent to the valve to automatically control the switching valve to open or close.

Here, in the conventional temperature control, the set temperature TS (° C.) of the heat medium, the temperature TE (° C.) of the heat medium, and the temperature difference are ΔT (° C.) = TE−TS. Then, depending on the value of ΔT, the flow rate of liquid nitrogen or its liquefied gas (hereinafter referred to as cryogen) is increased when ΔT is large. If ΔT is small, reduce the flow rate of the cryogen. When ΔT ≦ 0, the cryogen flow is stopped. In the case of a switching valve (open / close valve), the open / close time is adjusted according to the value of ΔT. In the case of a flow rate adjustment valve, the valve opening is adjusted by the value of ΔT.

FIG. 3 (b) shows the result when liquid nitrogen is used as a cryogen according to the above-mentioned conventional concept. This result shows that it is not easy to achieve the target temperature controllability of ± 1 ° C. In addition, it is considered as follows that it is not easy to achieve the temperature controllability of ± 1 ° C. Since cooling with liquefied nitrogen is performed using latent heat and sensible heat of vaporized gas, control that takes into account or reflects the amount of cooling heat Qc (latent heat and sensible heat) present in the conduit 30 of the heat exchanger 3 is required. That is, it is necessary to perform the valve opening / closing operation in consideration of Qc together with the detection of ΔT, but it is actually not easy due to the following circumstances. First, since Qc increases as TS decreases, further detection of ΔT and valve opening / closing operation methods that take this into account are required. Second, when the liquefied nitrogen pressure varies, Qc also varies, which affects the temperature controllability.

On the other hand, the temperature control of the present invention is performed by setting the set temperature TS (° C.) of the heat medium, the used nitrogen gas of liquid nitrogen, that is, the temperature TV (° C.) of the nitrogen gas flowing through the exhaust pipe portion 11a, ° C) = TV-TS. For example, in the case of a switching valve (open / close valve), when ΔT> 0, the valve is opened. When ΔT ≦ 0, the valve is closed.

FIG. 3 (a) shows the results when liquid nitrogen is used as a cryogen in accordance with the above-described concept of the present invention, and it can be seen that the intended temperature controllability of ± 1 ° C. is obtained. As the achievement factor, the residence time in the pipe 30 of the vaporized nitrogen gas and the exhaust pipe 11 is about 0.2 seconds. Thereby, the temperature TV of nitrogen gas is considered to be a Qc index having a quick response, and the valve opening / closing operation by the detection of TV results in an operation that leads to Qc control.

(Embodiment 2) FIG. 4 is a test in which the above-described refrigerant cooling device is used and the cooling capacity is examined, that is, a normal copper smooth tube is used as the conduit 30 of the heat exchanger 3, and FIG. The relationship between the passage of time and the temperature shown in Table 2 below, obtained when the copper grooved pipe of No. 1) is used, is shown as a cooling capacity curve. Each cooling capacity curve of (a) and (b) plots time (min) on the horizontal axis and temperature (° C.) on the vertical axis in evaluating the cooling capacity.

In this test, the heat medium was ethanol, and 2.6 kg of ethanol was filled in the stirring tank as the container 2 in the same manner as in Example 1. Liquid nitrogen is supplied at a supply rate of 4.95 kg / hr in the case of a smooth tube and at a supply rate of 8.67 kg / hr in the case of a grooved tube. In this test result, as can be seen from each cooling capacity curve, the grooved tube is improved in response by several steps compared to the smooth tube, and the liquid nitrogen utilization efficiency calculated as follows is also excellent. Yes. This is presumably because a grooved tube has the function of splash separation by centrifugal force and an increase in heat transfer coefficient.

The liquid nitrogen utilization efficiency was defined as follows. The cooling heat amount A of ethanol is obtained by (temperature at the time of final cooling−temperature at the start) × specific heat (0.52 kcal / kg / ° C.) × ethanol amount. The calorific value B of liquid nitrogen is obtained by latent heat (47.6 kcal / kg) + (temperature at the time of final cooling−vaporization temperature (−196 ° C.) × specific heat (0.25 kcal / kg / ° C.) × liquid nitrogen supply amount Liquid nitrogen utilization efficiency = (calculated heat amount of ethanol A / heat amount B of liquid nitrogen) x 100. The result shows that the utilization efficiency of liquid nitrogen is 76.6% in the smooth tube (liquid nitrogen supply rate) 4.95 kg / hr), and the grooved tube was 87.4% (liquid nitrogen supply rate 8.67 kg / hr).

It should be noted that the present invention is only required to have the configuration specified in the claims, and the details can be changed or developed with reference to form examples. As an example, the low temperature liquid is not limited to liquid nitrogen in the device structure, and the refrigerant or thermal refrigerant may be other than ethanol.

1 ... Storage tank for storing cryogenic liquid (1A is tank, 1B is protection tank)
2 ... Container with refrigerant (20 is main body, 21 is upper cover, 22 is door)
3 ... Heat exchanger (30 is pipe line)
4 ... object to be cooled 5 ... switching valve 6 ... switching valve (valve means)
7. Control unit (control means)
8a, 8b, 8c ... Temperature sensor 10 ... Supply pipe 11 ... Drain pipe (11a is a drain pipe part in the container)

Claims

A storage tank storing a low-temperature liquid such as liquid nitrogen, a container containing a refrigerant for cooling an object to be cooled, a heat exchanger for exchanging thermal energy between the liquefied gas of the low-temperature liquid and the refrigerant, and the storage tank Supply line for supplying the low-temperature liquid or liquefied gas thereof to the heat exchanger, valve means provided in the supply line, and an exhaust line for discharging the liquefied gas out of the system from the heat exchanger In the refrigerant cooling device comprising a low temperature liquid supplied to the heat exchanger or a supply of the liquefied gas, or a control means for controlling the valve opening / closing of the valve means or the valve opening degree,
The control means has a temperature sensor provided in a discharge pipe portion in the container of the discharge pipe, and is based on a detected temperature of the used liquefied gas flowing through the discharge pipe detected by the temperature sensor. The refrigerant cooling device is characterized in that the valve means is controlled so that the refrigerant can be maintained at a set temperature.
The refrigerant cooling apparatus according to claim 1, wherein the heat exchanger has a liquefied gas pipe wound in a coil shape or a spiral shape.
3. The refrigerant cooling apparatus according to claim 2, wherein the pipe is made of a copper pipe and has a plurality of grooves formed along the pipe longitudinal direction on the inner surface of the copper pipe.
Using the refrigerant cooling device according to any one of claims 1 to 3, heat exchange is performed between a liquefied gas of liquid nitrogen and a refrigerant that cools an object to be cooled by a heat exchanger, and the refrigerant is kept at a constant temperature. A refrigerant cooling method.