Liquid oxygen conversion circulating system

Abstract

The utility model discloses a liquid oxygen conversion circulating system, which belongs to the technical field of liquid oxygen vaporizers, and is characterized in that a cooling pipe is wound on a kiln, the inlet end of the cooling pipe is connected with a cooling tower, the outlet end of the cooling pipe is connected with a circulating pool, and an air temperature type vaporizer is placed in the circulating pool, so that a closed-loop heat energy recovery and utilization system is formed. By means of the design, efficient heat energy supply of the air temperature type vaporizer is achieved. Compared with a traditional air temperature type vaporizer which depends on ambient air as a heat source, the waste heat of the kiln, which is lost originally, is effectively captured and used for the vaporization process of liquid oxygen, so that the energy waste is reduced, the overall energy utilization efficiency is improved, and the energy consumption is reduced. As the system does not depend on the ambient air completely, but partially utilizes the waste heat of the kiln, the requirement on an external heat source is reduced, and the operation cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid oxygen vaporizers, in particular to a liquid oxygen conversion circulation system. Background Art

[0002] At the beginning of the 20th century, with the development of the Industrial Revolution, the demand for oxygen increased significantly, especially in the process of steel smelting and chemical production, which required a large amount of oxygen as an oxidant. Oxygen production technology has become an important part of the industrial production process. At present, air-temperature vaporizers are widely used in the oxygen production process. The basic principle is to use ambient air as a heat source medium to heat and vaporize liquid oxygen.

[0003] However, this traditional air-temperature vaporizer has some shortcomings. First, due to the fluctuation of ambient temperature, the heating effect of the air-temperature vaporizer is greatly affected, resulting in an unstable vaporization process. Second, the ambient air temperature is low, and the heat transfer efficiency is low, which makes the energy consumption of the vaporizer high. In addition, in a cold environment, the air temperature is even lower, and the performance of the air-temperature vaporizer is more difficult to meet actual needs. Utility Model Content

[0004] The utility model aims to provide a liquid oxygen conversion circulation system, which improves thermal efficiency, controls ambient temperature, reduces losses, improves system stability, saves energy and enhances heating effect by utilizing water with a certain temperature as a heat source medium of an air-temperature vaporizer.

[0005] In order to solve the above technical problems, the utility model adopts a technical solution:

[0006] Liquid oxygen conversion circulation system, including:

[0007] Kiln;

[0008] A cooling pipe is wound around the kiln and is used to cool the kiln;

[0009] A circulation pool is provided at one side of the kiln, and the outlet end of the cooling pipe is connected to the inlet end of the circulation pool through a pipeline;

[0010] A cooling tower is arranged on the upper part of the circulation pool, the outlet end of the cooling tower is connected to the inlet end of the cooling pipe through a pipeline, the outlet end of the circulation pool is connected to the inlet end of the cooling tower through a pipeline, and the cooling tower is used to provide cooling water to the cooling pipe;

[0011] A water pump, provided on the pipeline between the circulation pool and the cooling tower, for pumping water in the circulation pool into the cooling tower;

[0012] The air-temperature vaporizer is arranged in the circulation pool.

[0013] According to some embodiments, the inlet end of the air-temperature vaporizer is connected to a liquid oxygen tank via a pipeline for storing liquid oxygen carbon;

[0014] The outlet end of the air-temperature vaporizer is connected to a bottle-making workshop through a pipeline.

[0015] According to some embodiments, the air-temperature vaporizer comprises:

[0016] upper plate;

[0017] A lower plate, disposed below the upper plate;

[0018] A connecting column, disposed between the upper plate and the lower plate;

[0019] A fin tube group is arranged on the inner side between the upper plate and the lower plate, and the fin tube group array is arranged in multiple groups;

[0020] The upper parts of each adjacent group of fin tube groups are connected by a first connecting tube, and the lower parts of each adjacent group of fin tube groups are connected by a second connecting tube;

[0021] One group of the finned tube groups is connected to an air inlet pipe via a pipe, and the other group of the finned tube groups is connected to an air outlet pipe via a pipe;

[0022] The air inlet pipe is connected to the liquid oxygen tank, and the air outlet pipe is connected to the bottle making workshop.

[0023] According to some embodiments, the fin tube assembly comprises:

[0024] The fin tube bodies are provided in a plurality, the upper parts of two adjacent fin tube bodies are connected by the first connecting tube, and the lower parts of two adjacent fin tube bodies are connected by the second connecting tube;

[0025] A plurality of first fin leaves are arranged on the fin tube body, and a plurality of second fin leaves are arranged on the first fin leaves.

[0026] According to some embodiments, the second fin blade is in a strip-shaped structure, and rectangular fins are connected between the four adjacent fin tube bodies.

[0027] According to some embodiments, a vaporizer is provided between the liquid oxygen tank and the air-temperature vaporizer, the inlet end of the vaporizer is connected to the outlet end of the liquid oxygen tank via a pipeline, and the outlet end of the vaporizer is connected to the inlet end of the air-temperature vaporizer via a pipeline, and the vaporizer is used to convert liquid oxygen into gaseous oxygen.

[0028] According to some embodiments, a first switch valve is provided on the pipeline between the cooling tower and the cooling pipe, and a second switch valve is provided on the pipeline between the cooling pipe and the circulation pool.

[0029] Beneficial effects:

[0030] 1. By winding a cooling pipe around the kiln, connecting the inlet end of the cooling pipe to the cooling tower, connecting the outlet end to the circulation pool, and placing the air-temperature vaporizer in the circulation pool, a closed-loop heat recovery and utilization system is formed. This design realizes the efficient heat supply of the air-temperature vaporizer. Specifically, the heat generated by the kiln during operation is absorbed by the cooling pipe, and the cooling water enters the cooling pipe again after being cooled in the cooling tower to form a cycle. In this process, the heat absorbed by the cooling water is used to provide a heat source for the air-temperature vaporizer, so that liquid oxygen can be efficiently converted into gaseous oxygen at a lower temperature. In this way, not only the waste heat of the kiln is effectively utilized, reducing energy waste, but also a stable heat input is provided for the air-temperature vaporizer, improving the vaporization efficiency and reducing the operating cost. Therefore, this design realizes the efficient heat energy utilization of the air-temperature vaporizer and the optimization of the overall performance of the system.

[0031] 2. By recovering the waste heat of the kiln and utilizing it in the air-temperature vaporizer, compared with the traditional air-temperature vaporizer that relies on ambient air as a heat source, the waste heat of the kiln that would otherwise be lost is effectively captured and used in the vaporization process of liquid oxygen, reducing energy waste and improving overall energy efficiency. Since it is no longer completely dependent on ambient air, but partially utilizes the waste heat of the kiln, it reduces the demand for external heat sources, thereby reducing operating costs.

[0032] Additional aspects and advantages of the utility model will be given in part in the following description, and in part will become apparent from the following description, or will be understood through the practice of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation of the utility model or the technical solution in the prior art, the following is a brief introduction to the drawings required for the specific implementation or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0034] Figure 1 It is a connection diagram of the utility model;

[0035] Figure 2 for Figure 1 A schematic diagram of an air-temperature vaporizer is shown in FIG.

[0036] Figure 3 for Figure 2A local enlarged view of point A shown in FIG.

[0037] In the figure, 1 is a kiln, 2 is a cooling pipe, 21 is a second switch valve, 3 is a circulating pool, 4 is a cooling tower, 41 is a first switch valve, 5 is a water pump, 6 is an air-temperature vaporizer, 61 is an upper plate, 62 is a lower plate, 63 is a connecting column, 64 is a fin tube group, 641 is a fin tube body, 642 is a first fin blade, 643 is a second fin blade, 644 is a rectangular fin, 65 is a first connecting pipe, 66 is a second connecting pipe, 67 is an air inlet pipe, 68 is an air outlet pipe, 7 is a liquid oxygen tank, 8 is a bottle making workshop, and 9 is a vaporizer. DETAILED DESCRIPTION

[0038] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0039] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] In the description of the present utility model, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0041] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0042] Combination Figures 1 to 3 As shown, the liquid oxygen conversion circulation system includes a kiln 1, a cooling pipe 2, a circulation pool 3, a cooling tower 4, a water pump 5 and an air-temperature vaporizer 6.

[0043] The cooling pipe 2 is wound around the kiln 1 and is used for cooling the kiln 1; the circulating pool 3 is arranged on one side of the kiln 1, and the outlet end of the cooling pipe 2 is connected to the inlet end of the circulating pool 3 through a pipeline; the cooling tower 4 is arranged on the upper part of the circulating pool 3, and the outlet end of the cooling tower 4 is connected to the inlet end of the cooling pipe 2 through a pipeline, and the outlet end of the circulating pool 3 is connected to the inlet end of the cooling tower 4 through a pipeline, and the cooling tower 4 is used for providing cooling water to the cooling pipe 2; the water pump 5 is arranged on the pipeline between the circulating pool 3 and the cooling tower 4, and is used for pumping water in the circulating pool 3 into the cooling tower 4; the air-temperature evaporator 6 is arranged in the circulating pool 3.

[0044] Among them, by winding a cooling pipe 2 around the kiln 1, connecting the inlet end of the cooling pipe 2 to the cooling tower 4, connecting the outlet end to the circulation pool 3, and placing the air-temperature vaporizer 6 in the circulation pool 3, a closed-loop heat recovery and utilization system is formed, and this design realizes the efficient heat supply of the air-temperature vaporizer 6. Specifically, the heat generated by the kiln 1 during operation is absorbed by the cooling pipe 2, and the cooling water enters the cooling pipe 2 again after being cooled in the cooling tower 4 to form a cycle. In this process, the heat absorbed by the cooling water is used to provide a heat source for the air-temperature vaporizer 6, so that liquid oxygen can be efficiently converted into gaseous oxygen at a lower temperature. In this way, not only the waste heat of the kiln 1 is effectively utilized, reducing energy waste, but also a stable heat input is provided for the air-temperature vaporizer 6, improving the vaporization efficiency and reducing the operating cost. Therefore, this design realizes the efficient heat utilization of the air-temperature vaporizer 6 and the optimization of the overall performance of the system. By recovering the waste heat of the kiln 1 and utilizing it in the air-temperature vaporizer 6, compared with the traditional air-temperature vaporizer 6 which relies on ambient air as a heat source, the waste heat of the kiln 1 that would otherwise be lost is effectively captured and used in the vaporization process of liquid oxygen, thereby reducing energy waste and improving the overall energy utilization efficiency. Since it is no longer completely dependent on ambient air, but partially utilizes the waste heat of the kiln 1, the demand for external heat sources is reduced, thereby reducing operating costs.

[0045] The water pump 5 is used to pump water in the circulation pool 3 into the cooling tower 4 for cooling. When it is necessary to pump water in the circulation pool 3 into the cooling tower 4 for cooling, the water pump 5 is started.

[0046] The system works as follows:

[0047] 1. Cooling process: When the kiln 1 is in operation, a large amount of heat will be generated. The cooling pipe 2 surrounds the outer surface of the kiln 1, absorbs this part of the heat, and heats up the water or other cooling medium in the cooling pipe.

[0048] 2. Heat energy transfer: The heated water flows through the pipeline to the circulation pool 3, and then is pumped by the water pump 5 to the cooling tower 4. In the cooling tower 4, the hot water comes into contact with the ambient air and releases heat into the atmosphere through evaporation, thereby reducing the water temperature.

[0049] 3. Heat recovery: The cooled water returns to the inlet end of the cooling pipe 2 through the pipeline, forming a closed cycle and continuing to absorb the heat generated by the kiln 1.

[0050] 4. Utilization of heat energy: In the circulation pool 3, this part of water containing heat is used in the air-temperature vaporizer 6. The heat energy is transferred to the liquid oxygen, so that it is efficiently vaporized into gaseous oxygen at a lower temperature.

[0051] In this way, the waste heat of kiln 1 is effectively utilized, reducing the impact on the environment, while also reducing dependence on external energy, improving the energy efficiency of the system, and reducing operating costs. The entire system achieves efficient recovery and reuse of heat energy through a carefully designed heat transfer path, which is both energy-saving and environmentally friendly.

[0052] Combination Figure 1 As shown, the inlet end of the air-temperature vaporizer 6 is connected to a liquid oxygen tank 7 through a pipeline for storing liquid oxygen carbon; the outlet end of the air-temperature vaporizer 6 is connected to a bottle-making workshop 8 through a pipeline. The liquid oxygen stored in the liquid oxygen tank 7 is transported to the air-temperature vaporizer 6 through a pipeline, and the liquid oxygen is converted into gaseous state under the action of the air-temperature vaporizer 6, and then supplied to the bottle-making workshop 8.

[0053] Combination Figure 2 As shown, the air-temperature vaporizer 6 includes: an upper plate 61, a lower plate 62, a connecting column 63, a fin tube group 64, a first connecting pipe 65, a second connecting pipe 66, an air inlet pipe 67 and an air outlet pipe 68. The lower plate 62 is arranged below the upper plate 61; the connecting column 63 is arranged between the upper plate 61 and the lower plate 62; the fin tube group 64 is arranged on the inner side between the upper plate 61 and the lower plate 62, and the fin tube group 64 array is arranged in multiple groups; the upper parts of each adjacent group of fin tube groups 64 are connected by the first connecting pipe 65, and the lower parts of each adjacent group of fin tube groups 64 are connected by the second connecting pipe 66; one group of fin tube groups 64 is connected to the air inlet pipe 67 through a pipeline, and the other group of fin tube groups 64 is connected to the air outlet pipe 68 through a pipeline; the air inlet pipe 67 is connected to the liquid oxygen tank 7, and the air outlet pipe 68 is connected to the bottle making workshop 8.

[0054] Among them, the upper plate 61 and the lower plate 62 form a frame to provide support for the fin tube group 64 and create a closed space so that liquid oxygen can flow through the fin tubes. The fin tube group 64 is the core part of the vaporizer. The fins increase the surface area of ​​the tubes, allowing the liquid oxygen to contact the surrounding air faster, thereby accelerating vaporization. The arrangement of multiple groups of fin tube arrays increases the vaporization efficiency. The first connecting pipe 65 and the second connecting pipe 66 form a connecting channel between the fin tube group 64, so that the liquid oxygen can be evenly distributed throughout the vaporizer, while also allowing the vaporized oxygen to flow between each group of fin tubes. The air inlet pipe 67 is connected to the liquid oxygen tank 7 to introduce the liquid oxygen into the air-temperature vaporizer 6; the air outlet pipe 68 delivers the gaseous oxygen to the bottle making workshop 8. This design ensures the continuous supply of liquid oxygen and the smooth output of gaseous oxygen.

[0055] In some embodiments, a high-efficiency component is provided in the fin tube group 64, and the specific structure of the high-efficiency component can refer to the patent application number CN202222675574.1 which discloses a new type of high-efficiency LNG air-temperature vaporizer, and the working principle of the above-mentioned air-temperature vaporizer is the same as the working principle of the LNG air-temperature vaporizer in the patent.

[0056] Combination Figure 2 and Figure 3 As shown, the fin tube group 64 includes: a fin tube body 641, a first fin leaf 642 and a second fin leaf 643. The fin tube body 641 is provided in plurality, the upper part between two adjacent fin tube bodies 641 is connected by a first connecting tube 65, and the lower part between two adjacent fin tube bodies 641 is connected by a second connecting tube 66; a plurality of first fin leaves 642 are provided on the fin tube body 641, and a plurality of second fin leaves 643 are provided on the first fin leaf 642. The second fin leaf 643 is in a strip-shaped structure, and rectangular fins 644 are also connected between four adjacent fin tube bodies 641.

[0057] Among them, the fin tube body 641 is the main working part of the vaporizer, liquid oxygen is introduced into the inside, and the outside is in contact with the ambient air. By increasing the surface area of ​​the tube body, the vaporization process of liquid oxygen can be accelerated. The first fin leaf 642 is a thin sheet structure attached to the fin tube body 641, which increases the contact surface area of ​​liquid oxygen and air, making heat exchange more effective. When liquid oxygen contacts the fins, it will quickly absorb the heat of the surrounding air and begin to convert into a gaseous state. The second fin leaf 643 is arranged on the first fin leaf 642, further refining the fin structure, increasing the contact surface area, and making heat transfer more rapid and uniform. Such a design helps to increase the vaporization rate, reduce heat loss, and improve system efficiency. The first connecting pipe 65 and the second connecting pipe 66 connect the adjacent fin tube bodies 641 to form a continuous channel, so that the liquid oxygen can be evenly distributed throughout the vaporizer, while allowing the vaporized oxygen to flow smoothly from one end to the other. The second fin leaf 643 is in a strip structure, and a rectangular fin 644 is connected between the four adjacent fin tube bodies 641. The strip structure increases the contact area between the fin and the air, making the heat exchange more sufficient. This shape helps to reduce the resistance of liquid oxygen during the vaporization process, promotes the uniform vaporization of the liquid, and can better guide the airflow, improve the overall heat exchange efficiency. The rectangular fin 644 is arranged between the four adjacent fin tube bodies 641, and expands the surface area of ​​the entire vaporizer, so that more liquid oxygen can contact the air at the same time, accelerating the vaporization speed. In addition, the rectangular fin 644 also plays a role in supporting and strengthening the structure, improving the mechanical strength of the vaporizer, and preventing deformation caused by temperature changes or pressure fluctuations. Combined with the strip-shaped second fin leaf 643 and the rectangular fin 644, the fin tube structure formed is more complex, which not only improves the heat exchange efficiency, but also ensures that the liquid oxygen is evenly distributed and flows during the vaporization process, thereby achieving a more efficient and stable vaporization effect.

[0058] Combination Figure 1 As shown, a vaporizer 9 is provided between the liquid oxygen tank 7 and the air-temperature vaporizer 6, the inlet end of the vaporizer 9 is connected to the outlet end of the liquid oxygen tank 7 through a pipeline, and the outlet end of the vaporizer 9 is connected to the inlet end of the air-temperature vaporizer 6 through a pipeline. The vaporizer 9 is used to convert liquid oxygen into gaseous oxygen.

[0059] Among them, the vaporizer 9 arranged between the liquid oxygen tank 7 and the air-temperature vaporizer 6 plays the role of intermediate conversion, and its main function is to ensure that liquid oxygen is safely and effectively converted into gaseous oxygen for use in the bottle making workshop 8. The vaporizer 9 can be used as a pretreatment device to further heat the liquid oxygen to a suitable temperature to adapt to the working conditions of the air-temperature vaporizer 6. This helps to improve the vaporization efficiency and avoid the situation where the air-temperature vaporizer 6 cannot be effectively vaporized due to the low temperature of the liquid oxygen. The vaporizer 9 can assist in regulating the temperature of the liquid oxygen to ensure that the liquid oxygen entering the air-temperature vaporizer 6 is within a suitable temperature range, which helps to prevent the air-temperature vaporizer 6 from freezing or reducing efficiency due to the low temperature. The vaporizer 9 can also help stabilize the pressure of oxygen, ensure the stability of the oxygen flow entering the furnace, and help maintain the combustion process of the furnace. During the liquid oxygen vaporization process, the vaporizer 9 can be used as a safety device to prevent the liquid oxygen from vaporizing too quickly and causing a sudden increase in pressure, thereby ensuring the safe operation of the entire system. By pre-vaporizing the vaporizer 9, the workload of the air-temperature vaporizer 6 can be reduced, thereby improving the efficiency of the entire system.

[0060] Combination Figure 1 As shown, a first switch valve 41 is provided on the pipeline between the cooling tower 4 and the cooling pipe 2, and a second switch valve 21 is provided on the pipeline between the cooling pipe 2 and the circulating pool 3, so that the first switch valve 41 and the second switch valve 21 can be opened or closed according to actual conditions.

[0061] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. Liquid oxygen conversion circulation system, characterized in that: include: Kiln (1); A cooling pipe (2) is wound around the kiln (1) and is used to cool the kiln (1); A circulation pool (3) is arranged on one side of the kiln (1), and the outlet end of the cooling pipe (2) is connected to the inlet end of the circulation pool (3) through a pipeline; A cooling tower (4) is arranged on the upper part of the circulation pool (3), the outlet end of the cooling tower (4) is connected to the inlet end of the cooling pipe (2) through a pipeline, the outlet end of the circulation pool (3) is connected to the inlet end of the cooling tower (4) through a pipeline, and the cooling tower (4) is used to provide cooling water to the cooling pipe (2); A water pump (5) is provided on the pipeline between the circulation pool (3) and the cooling tower (4) and is used to pump water in the circulation pool (3) into the cooling tower (4); An air-temperature vaporizer (6) is arranged in the circulation pool (3).

2. The liquid oxygen conversion circulation system according to claim 1, characterized in that: The inlet end of the air-temperature vaporizer (6) is connected to a liquid oxygen tank (7) through a pipeline for storing liquid oxygen and carbon; The outlet end of the air-temperature vaporizer (6) is connected to a bottle-making workshop (8) via a pipeline.

3. The liquid oxygen conversion circulation system according to claim 2, characterized in that: The air-temperature vaporizer (6) comprises: Upper board(61); A lower plate (62) is disposed below the upper plate (61); A connecting column (63) is provided between the upper plate (61) and the lower plate (62); A fin tube group (64) is arranged on the inner side between the upper plate (61) and the lower plate (62), and the fin tube group (64) is arranged in an array of multiple groups; The upper parts of each adjacent group of fin tube groups (64) are connected via a first connecting tube (65), and the lower parts of each adjacent group of fin tube groups (64) are connected via a second connecting tube (66); One group of the fin tube groups (64) is connected to an air inlet pipe (67) via a pipe, and another group of the fin tube groups (64) is connected to an air outlet pipe (68) via a pipe; The air inlet pipe (67) is connected to the liquid oxygen tank (7), and the air outlet pipe (68) is connected to the bottle making workshop (8).

4. The liquid oxygen conversion circulation system according to claim 3, characterized in that: The fin tube assembly (64) comprises: The fin tube bodies (641) are provided in plurality, the upper parts of two adjacent fin tube bodies (641) are connected via the first connecting tube (65), and the lower parts of two adjacent fin tube bodies (641) are connected via the second connecting tube (66); A plurality of first fin leaves (642) are arranged on the fin tube body (641), and a plurality of second fin leaves (643) are arranged on the first fin leaves (642).

5. The liquid oxygen conversion circulation system according to claim 4, characterized in that: The second fin blade (643) is in a strip-shaped structure, and rectangular fins (644) are connected between the four adjacent fin tube bodies (641).

6. The liquid oxygen conversion circulation system according to claim 2, characterized in that: A vaporizer (9) is arranged between the liquid oxygen tank (7) and the air-temperature vaporizer (6); the inlet end of the vaporizer (9) is connected to the outlet end of the liquid oxygen tank (7) via a pipeline, and the outlet end of the vaporizer (9) is connected to the inlet end of the air-temperature vaporizer (6) via a pipeline. The vaporizer (9) is used to convert liquid oxygen into gaseous oxygen.

7. The liquid oxygen conversion circulation system according to claim 1, characterized in that: A first switch valve (41) is provided on the pipeline between the cooling tower (4) and the cooling pipe (2), and a second switch valve (21) is provided on the pipeline between the cooling pipe (2) and the circulation pool (3).

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