Compression refrigerating machine and semiconductor manufacturing system

Abstract

To provide a compression type refrigerating machine capable of preventing deterioration of a CoefficientofPerformance (COP) during hot gas bypass operation.SOLUTION: The compression refrigerating machine 1 includes an evaporator 3 for evaporating a refrigerant liquid to generate refrigerant vapor, a compressor 2 for compressing the refrigerant vapor, a condenser 4 for condensing the compressed refrigerant vapor to generate a refrigerant liquid, a hot gas bypass line 18 for guiding the compressed refrigerant vapor to the evaporator 3 while bypassing the condenser 4, an expander 20 disposed in the hot gas bypass line 18, a generator 22 connected to the expander 20 and driven by the expander 20, and a flow control valve 24 for adjusting the flow rate of the compressed refrigerant vapor flowing through the hot gas bypass line 18.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a compression refrigerator equipped with a compressor for compressing refrigerant vapor, and more particularly to a compression refrigerator suitable for cooling a heat medium used to regulate the temperature of semiconductor manufacturing equipment. [Background technology]

[0002] Semiconductor manufacturing equipment (e.g., etching equipment, CVD equipment, and PVD equipment) for manufacturing semiconductor devices is configured to perform manufacturing processes while controlling the processing temperature. For example, in etching equipment, the processing temperature of the wafer is controlled by flowing a temperature-controlled liquid as a heat medium through a flow path formed in a susceptor that supports the wafer.

[0003] The temperature of the heat transfer medium supplied to the semiconductor manufacturing equipment is adjusted directly or indirectly by a cooling device and a heating device. For example, a temperature-adjusted heat transfer medium is generated by mixing a heat transfer medium cooled by a cooling device with a heat transfer medium heated by a heating device, and the heat transfer medium is supplied to the semiconductor manufacturing equipment, thereby adjusting the processing temperature in the semiconductor manufacturing equipment.

[0004] The cooling device uses a compression-type refrigerator such as a turbo refrigerator. Semiconductor manufacturing equipment carries out manufacturing processes while changing the processing temperature in accordance with the manufacturing process. Therefore, the compression-type refrigerator is required to quickly cool the heat transfer medium according to the processing temperature required by the semiconductor manufacturing equipment. Furthermore, depending on the manufacturing process, the compression-type refrigerator may be required to perform no-load operation, which does not require cooling the heat transfer medium.

[0005] To operate in response to such diverse refrigeration loads, compression refrigeration machines are configured to perform hot gas bypass operation using a hot gas bypass circuit in addition to compressor rotation control using an inverter (see Patent Document 1). Hot gas bypass operation is an operation in which, when the refrigeration load is small, refrigerant vapor (hot gas) compressed by the compressor bypasses the condenser and is led to the evaporator. Because the refrigerant vapor is led directly to the evaporator, it does not contribute to the cooling action of the evaporator, and the hot gas reduces the refrigeration capacity, allowing low-load operation or no-load operation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-74318 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in hot gas bypass operation, the refrigerant vapor that bypasses the condenser flows to the compressor via the evaporator, which increases the compression power required by the compressor, resulting in increased energy loss and a decrease in the coefficient of performance (COP) of the compression chiller.

[0008] Therefore, the present invention provides a compression refrigerator that can prevent a decrease in the coefficient of performance (COP) during hot gas bypass operation. [Means for solving the problem]

[0009] In one aspect, there is provided a compression type refrigerator including: an evaporator that evaporates a refrigerant liquid to generate refrigerant vapor; a compressor that compresses the refrigerant vapor; a condenser that condenses the compressed refrigerant vapor to generate the refrigerant liquid; a hot gas bypass line that guides the compressed refrigerant vapor to the evaporator, bypassing the condenser; an expander disposed in the hot gas bypass line; a generator connected to and driven by the expander; and a flow control valve that adjusts the flow rate of the compressed refrigerant vapor flowing through the hot gas bypass line.

[0010] According to the present invention, the following effects can be obtained. The refrigerant vapor flowing through the hot gas bypass line does not contribute to increasing the refrigeration capacity of the compression refrigerator, but it can drive the expander and generate electricity from the generator. Therefore, by using this electricity, it is possible to prevent a decrease in the coefficient of performance (COP) of the compression refrigerator. In particular, since the refrigerant vapor is in the gas phase, it can efficiently drive the expander. Controlling the flow rate of refrigerant vapor flowing through the hot gas bypass line allows for linear changes in the refrigeration capacity of the compression refrigerator. This feature allows for rapid response to fluctuations in the refrigeration load by controlling the opening of the flow control valve. By passing refrigerant vapor through the hot gas bypass line, the compression refrigerator can continue to operate stably even when the refrigeration load remains low. By passing refrigerant vapor through the hot gas bypass line, the compressor temperature is stabilized (the discharge temperature of the refrigerant vapor is kept low even during low refrigeration loads).

[0011] In one embodiment, the compression refrigerator further includes a power line that supplies the electric power generated by the generator to an electric motor of the compressor. According to the present invention, the electric power generated by the generator can be consumed in the compression refrigerator, thereby preventing a decrease in the coefficient of performance (COP) of the compression refrigerator.

[0012] In one aspect, the compression refrigerator further includes a refrigerant branch line that supplies the refrigerant liquid as a cooling liquid to an electric motor of the compressor, a refrigerant pump that is arranged in the refrigerant branch line and transports the refrigerant liquid, and a power line that supplies electric power generated by the generator to the electric motor of the refrigerant pump. According to the present invention, the electric power generated by the generator can be consumed in the compression refrigerator, thereby preventing a decrease in the coefficient of performance (COP) of the compression refrigerator.

[0013] In one aspect, the compression type refrigeration machine further includes an inverter that changes the rotation speed of the motor of the compressor, and an operation control unit that controls the operation of at least one of the flow control valve and the inverter so that the temperature of the heat medium flowing out of the evaporator reaches a target temperature. In one aspect, the operation control unit is configured to select either the flow control valve or the inverter based on the difference between the temperature of the heat medium flowing out of the evaporator and the temperature of the heat medium flowing into the evaporator, and to control the operation of the selected flow control valve or the selected inverter. According to the present invention, it is possible to follow fluctuations in the refrigeration load on the compression refrigerator by controlling at least one of the rotation of the inverter and the flow rate of the refrigerant vapor flowing through the hot gas bypass line.

[0014] In one aspect, the compression type refrigerator further includes an inlet guide vane that adjusts the intake flow rate of the refrigerant vapor into the compressor, and an operation control unit that controls the operation of at least one of the flow rate control valve and the inlet guide vane so that the temperature of the heat medium flowing out of the evaporator reaches a target temperature. In one aspect, the operation control unit is configured to select either the flow control valve or the inlet guide vane based on the difference between the temperature of the heat medium flowing out of the evaporator and the temperature of the heat medium flowing into the evaporator, and to control the operation of the selected flow control valve or inlet guide vane. According to the present invention, it is possible to follow fluctuations in the refrigeration load on the compression refrigerator by controlling the suction flow rate of refrigerant vapor using the inlet guide vane or by controlling the flow rate of refrigerant vapor flowing through the hot gas bypass line.

[0015] In one aspect, the compression refrigerator further includes an inverter that changes the rotation speed of the compressor's motor, and the operation control unit is configured to control the operation of at least one of the flow control valve, the inlet guide vane, and the inverter so that the temperature of the heat medium flowing out of the evaporator reaches a target temperature. According to the present invention, fluctuations in the refrigeration load on the compression refrigerator can be followed by at least one of inverter rotation control, refrigerant vapor intake flow rate control by the inlet guide vane, and refrigerant vapor flow rate control through the hot gas bypass line.

[0016] In one embodiment, the compressor includes a magnetic bearing that supports a rotating shaft. In one embodiment, the expander includes a magnetic bearing that supports a rotating shaft.

[0017] In one aspect, a semiconductor manufacturing system is provided, comprising a semiconductor manufacturing apparatus and the compression refrigerator. [Effects of the Invention]

[0018] According to the present invention, the following effects can be obtained. The refrigerant vapor flowing through the hot gas bypass line does not contribute to increasing the refrigeration capacity of the compression chiller, but it can drive the expander and the generator to generate electricity. This helps prevent a decrease in the coefficient of performance (COP) of the compression chiller. In particular, since the refrigerant vapor is in gas phase, it is highly effective in efficiently driving the expander. Controlling the flow rate of refrigerant vapor flowing through the hot gas bypass line allows for linear changes in the refrigeration capacity of the compression refrigerator. This feature allows for rapid response to fluctuations in the refrigeration load by controlling the opening of the flow control valve. By passing refrigerant vapor through the hot gas bypass line, the compression refrigerator can continue to operate stably even when the refrigeration load remains low. · By actively flowing refrigerant vapor through the hot gas bypass line, the compressor temperature condition is stabilized (the discharge temperature of the refrigerant vapor is kept low even during low refrigeration loads). [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram illustrating an embodiment of a compression refrigerator. [Figure 2] FIG. 10 is a diagram showing another embodiment of a compression refrigerator. [Figure 3] FIG. 10 is a diagram showing still another embodiment of the compression refrigerator. [Figure 4] FIG. 10 is a diagram showing still another embodiment of the compression refrigerator. [Figure 5] 10 is a graph showing the relationship between the refrigeration capacity and the flow rate in the hot gas bypass line when the refrigeration capacity is adjusted by controlling the flow rate in the hot gas bypass line. [Figure 6] FIG. 10 is a diagram comparing the COP of capacity control using only flow rate adjustment of a hot gas bypass without an expander and capacity control using only flow rate adjustment of a hot gas bypass with an expander. [Figure 7] 7 is a graph showing the ratio of COPs in FIG. 6. [Figure 8]FIG. 5 is a diagram showing an embodiment in which the compression refrigerator according to any one of the embodiments shown in FIGS. 1 to 4 is used in a cooling device of a semiconductor manufacturing system. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing one embodiment of a compression chiller (turbo chiller). As shown in FIG. 1, compression chiller 1 includes an evaporator 3 that evaporates refrigerant liquid to produce refrigerant vapor, a compressor 2 that compresses the refrigerant vapor, and a condenser 4 that condenses the compressed refrigerant vapor to produce refrigerant liquid. The suction port of compressor 2 is connected to evaporator 3 by refrigerant piping 5A. The discharge port of compressor 2 is connected to condenser 4 by refrigerant piping 5B. An expansion valve 7 is attached to refrigerant piping 5C extending from condenser 4 to evaporator 3. Expansion valve 7 is an actuator-driven flow control valve configured so that its opening is adjustable, and is configured, for example, by a variable-opening motor-operated valve.

[0021] In this embodiment, the compressor 2 includes an impeller 11 and an electric motor 13 that rotates the impeller 11. The impeller 11 may be a single-stage impeller or a multi-stage impeller. The compression refrigerator 1 includes an inverter 15 that changes the rotation speed of the electric motor 13. Power is supplied to the inverter 15 from a commercial power source. The inverter 15 is configured to supply variable-frequency power to the electric motor 13.

[0022] At the suction port of the compressor 2, inlet guide vanes 16 are arranged to adjust the suction flow rate of refrigerant vapor into the impeller 11. The inlet guide vanes 16 are located on the suction side of the impeller 11. The inlet guide vanes 16 are arranged radially, and each inlet guide vane 16 rotates synchronously around its own axis by a predetermined angle, changing the opening of the inlet guide vanes 16. The smaller the opening of the inlet guide vanes 16, the smaller the suction flow rate of refrigerant vapor and the lower the refrigeration capacity. The refrigerant vapor sent from the evaporator 3 passes through the inlet guide vanes 16 and is then pressurized by the rotating impeller 11. The pressurized refrigerant vapor is sent to the condenser 4 through the refrigerant piping 5B.

[0023] The evaporator 3 produces a refrigerating effect by evaporating the refrigerant liquid by removing heat from the heat transfer medium (the fluid to be cooled). The compressor 2 compresses the refrigerant vapor produced in the evaporator 3, and the condenser 4 cools and condenses the compressed refrigerant vapor with a cooling fluid (e.g., cooling water) to produce a refrigerant liquid. The refrigerant liquid is decompressed by passing through an expansion valve 7. The decompressed refrigerant liquid is sent to the evaporator 3. In this way, the compression refrigerator 1 is configured as a closed system in which a refrigerant is sealed. An example of a heat transfer medium, which is the fluid to be cooled, is brine. Specific examples of brine include ethylene glycol, propylene glycol, calcium chloride, silicone oil, and fluorine-based inert liquids.

[0024] The compression type refrigerator 1 includes a hot gas bypass line 18 that guides compressed refrigerant vapor to the evaporator 3, bypassing the condenser 4, an expander 20 disposed on the hot gas bypass line 18, a generator 22 connected to the expander 20 and driven by the expander 20, and a flow control valve 24 that adjusts the flow rate of the compressed refrigerant vapor flowing through the hot gas bypass line 18. The hot gas bypass line 18 extends from the compressor 2 via the expander 20 to the evaporator 3. More specifically, one end of the hot gas bypass line 18 is connected to the compressor 2 at a position on the discharge side of the impeller 11, and the other end of the hot gas bypass line 18 is connected to the evaporator 3 or the refrigerant pipe 5A.

[0025] The configuration of the expander 20 is not particularly limited as long as it is driven by refrigerant vapor, and examples include a turbine expander equipped with a turbine or a scroll expander equipped with a scroll. The compressed refrigerant vapor (hot gas) flows through the hot gas bypass line 18 and rotates the turbine or scroll of the expander 20. The refrigerant vapor (hot gas) further flows through the hot gas bypass line 18 and flows into the evaporator 3. The generator 22 is connected to the expander 20 and is rotated by the expander 20 to generate electricity.

[0026] The generator 22 is electrically connected to the inverter 15 via a power line 30. The power generated by the generator 22 is supplied to the inverter 15 through the power line 30. The power generated by the generator 22 can supplement the power to be supplied to the inverter 15, thereby reducing the amount of power supplied from the commercial power source. In particular, the power generated by the generator 22 can be consumed within the compression chiller 1, preventing a decrease in the coefficient of performance (COP) of the compression chiller 1. In principle, the amount of power generated by the operation of the motor 13 does not exceed the power consumption of the motor 13, so all of the power generated by the generator 22 can be consumed, which is rational and safe.

[0027] The flow control valve 24 is connected to the hot gas bypass line 18 at a position between the compressor 2 and the expander 20. The flow control valve 24 is an actuator-driven flow control valve, and is configured, for example, by an electric valve with a variable opening. As the opening of the flow control valve 24 increases, the flow rate of the refrigerant vapor flowing through the hot gas bypass line 18 increases, and as a result, the amount of power generated by the generator 22 increases. The amount of power generated by the generator 22 can be controlled by the opening of the flow control valve 24.

[0028] The compression chiller 1 includes an operation control unit 27 that controls the operations of the inverter 15, the inlet guide vane 16, and the flow rate control valve 24. More specifically, the operation control unit 27 is configured to give a command to the inverter 15 to rotate the electric motor at a target rotation speed. The operation control unit 27 is also configured to give a command to the inlet guide vane 16 to maintain the inlet guide vane 16 at a target opening degree. The operation control unit 27 is also configured to give a command to the flow rate control valve 24 to maintain the flow rate control valve 24 at the target opening degree.

[0029] The operation control unit 27 is composed of at least one computer. The operation control unit 27 includes a storage device 27a that stores programs for controlling the operations of the inverter 15, the inlet guide vane 16, and the flow rate adjustment valve 24, and an arithmetic unit 27b that executes calculations according to instructions included in the programs. The storage device 27a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the arithmetic unit 27b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the operation control unit 27 is not limited to these examples.

[0030] The compression refrigerator 1 further includes a temperature sensor S1 as an inlet temperature measuring device that measures the temperature of the heat medium flowing into the evaporator 3, and a temperature sensor S2 as an outlet temperature measuring device that measures the temperature of the heat medium flowing out from the evaporator 3. The temperature sensors S1 and S2 are electrically connected to the operation control unit 27, and the measured values ​​of the temperature of the heat medium flowing into the evaporator 3 and the measured values ​​of the temperature of the heat medium flowing out from the evaporator 3 are sent to the operation control unit 27.

[0031] The operation control unit 27 controls the operation of at least one of the flow rate control valve 24, the inlet guide vane 16, and the inverter 15 so that the temperature of the heat medium flowing out of the evaporator 3 reaches a target temperature. In one embodiment, the operation control unit 27 sequentially controls the operation of the inverter 15, the inlet guide vane 16, and the flow rate control valve 24 so that the temperature of the heat medium flowing out of the evaporator 3 reaches the target temperature. That is, when the difference between the temperature of the heat medium flowing into the evaporator 3 and the temperature of the heat medium flowing out of the evaporator 3 (hereinafter referred to as the temperature difference) is greater than a first threshold, the operation control unit 27 controls the operation of the inverter 15 (i.e., controls the rotation speed of the compressor 2) to reduce the temperature difference. The flow rate control valve 24 is closed. The inlet guide vane 16 is maintained at an opening degree (e.g., fully open) that increases the flow rate. A temperature difference greater than the first threshold means that the refrigeration load on the compression chiller 1 is large.

[0032] The first threshold value corresponds to the minimum rotation speed of the compressor 2 at which surging of the compressor 2 does not occur. Surging is a phenomenon in which the vibration and noise of the compressor 2 gradually increase due to stalling of the flow of refrigerant vapor when the rotation speed of the compressor 2 is too low. The first threshold value is set in advance based on the minimum rotation speed of the compressor 2 at which surging of the compressor 2 does not occur depending on the operating state. The minimum rotation speed of the compressor 2 is the point at which the compressor becomes highly efficient, and when the temperature difference is greater than the first threshold value, the inverter 15 controls the compressor to achieve the most efficient operation.

[0033] If the temperature difference is smaller than the first threshold value and larger than the second threshold value, the operation control unit 27 reduces the temperature difference by controlling the opening of the inlet guide vane 16 while maintaining the minimum rotation speed of the compressor 2 according to the operating state and keeping the flow control valve 24 closed. The second threshold value is smaller than the first threshold value.

[0034] If the temperature difference is smaller than the second threshold value, the operation control unit 27 reduces the temperature difference by controlling the aperture of the flow rate adjustment valve 24 (i.e., controlling the flow rate of the refrigerant vapor flowing through the hot gas bypass line 18). In this hot gas bypass control, the aperture of the inlet guide vane 16 is maintained at its lower limit, and the rotation speed of the compressor 2 is maintained at the minimum rotation speed that can avoid surging.

[0035] A temperature difference smaller than the second threshold value means that the refrigeration load on the compression chiller 1 is small. For example, in no-load operation where there is no need to cool the heat medium, the temperature difference is substantially zero. In such a case, control of the inverter 15 and the inlet guide vane 16 cannot be sufficient. Therefore, in this embodiment, the operation control unit 27 controls the aperture of the flow rate adjustment valve 24 (i.e., controls the flow rate of the refrigerant vapor flowing through the hot gas bypass line 18), thereby enabling the compression chiller 1 to perform no-load operation or low-load operation.

[0036] Assuming that the flow rate of the compressor 2 is constant, the relationship between the flow rate of the refrigerant vapor flowing through the hot gas bypass line 18 and the refrigeration load is approximated by a linear function. The relationship between the opening of the flow control valve 24 and the refrigeration load is linear, providing high controllability. When controlling the inlet guide vanes 16, the relationship between the opening of the inlet guide vanes 16 and the refrigeration load is not linear, and the temperature of the heat transfer medium is prone to hunting when the refrigeration load suddenly changes. Because the flow control valve 24 has linear control characteristics and can be opened and closed at a high speed, hot gas bypass control can also follow sudden changes in the refrigeration load. Therefore, when the opening of the inlet guide vanes 16 cannot follow sudden load changes—for example, when the load suddenly drops and the temperature of the heat transfer medium flowing out of the evaporator 3 drops significantly—the opening of the flow control valve 24 may be controlled without waiting for the inlet guide vanes 16 to close to their lower limit.

[0037] With rotational speed control by the inverter 15, the relationship between rotational speed and refrigeration load is nearly proportional, providing high controllability. It also allows for the refrigeration capacity to be reduced without reducing the efficiency of the compressor 2. However, with a compression-type chiller 1, the minimum rotational speed of the compressor 2 is set to avoid surging caused by the head, which in the case of a centrifugal chiller is primarily determined by the refrigerant temperature, and the control range is limited. In contrast, hot gas bypass control is unrelated to the refrigerant temperature and can be used across the entire operating range, including no-load operation, eliminating the risk of surging due to a decrease in refrigeration load. For this reason, the combination of rotational speed control by the inverter 15 and opening control of the flow control valve 24 enables operation up to no-load operation with high compressor efficiency.

[0038] Furthermore, by opening the flow control valve 24 when the compression refrigerator 1 is stopped, the refrigerant flow rate that flows back inside the compression refrigerator 1 can be dispersed, minimizing the impact on the compressor 2. As described above, controlling the refrigeration capacity using hot gas bypass is the most stable control method that allows operation even at low loads.

[0039] The refrigerant vapor flowing through the hot gas bypass line 18 does not contribute to increasing the refrigeration capacity of the compression chiller 1, but this refrigerant vapor drives the expander 20, and the generator 22 can generate electricity. This prevents a decrease in the coefficient of performance (COP) of the compression chiller 1. In other words, by providing the expander 20 in the hot gas bypass line 18, it is possible to minimize the decrease in the COP during low-load operation. In particular, because the refrigerant vapor is in a gas phase, it can drive the expander 20 efficiently.

[0040] In the embodiment shown in FIG. 1, the compression refrigerator 1 is provided with both an inlet guide vane 16 and an inverter 15 for controlling the refrigeration load, but in one embodiment, the compression refrigerator 1 may be provided with either the inlet guide vane 16 or the inverter 15.

[0041] For example, if the compression chiller 1 includes the inlet guide vane 16 but does not include the inverter 15, the operation control unit 27 sequentially controls the operation of the inlet guide vane 16 and the flow rate control valve 24 so that the temperature of the heat medium flowing out of the evaporator 3 reaches a target temperature. That is, if the temperature difference (the difference between the temperature of the heat medium flowing into the evaporator 3 and the temperature of the heat medium flowing out of the evaporator 3) is greater than a threshold value, the operation control unit 27 reduces the temperature difference by controlling the aperture of the inlet guide vane 16. If the temperature difference is smaller than the threshold value, the operation control unit 27 reduces the temperature difference by controlling the aperture of the flow rate control valve 24 (i.e., controlling the flow rate of refrigerant vapor flowing through the hot gas bypass line 18) while maintaining the aperture of the inlet guide vane 16 at a lower limit value.

[0042] At partial loads where the temperature difference is less than a threshold, the expander 20 is driven by the refrigerant vapor flowing through the hot gas bypass line 18, allowing the generator 22 to generate electricity, thereby improving the COP using the expander 20. If the opening of the inlet guide vanes 16 becomes small, the compression head decreases, and a lower limit on the opening may be determined due to restrictions on the occurrence of surging. By providing the expander 20 in the hot gas bypass line 18, it becomes possible to increase the proportion of the flow rate of the refrigerant vapor in the hot gas bypass line 18, enabling stable operation without the risk of surging throughout the entire operating range and increasing the design freedom of the impeller 11.

[0043] In another example, when the compression chiller 1 includes the inverter 15 but does not include the inlet guide vane 16, the operation control unit 27 sequentially controls the operation of the inverter 15 and the flow rate control valve 24 so that the temperature of the heat medium flowing out of the evaporator 3 reaches the target temperature. That is, when the temperature difference is greater than a threshold value, the operation control unit 27 controls the operation of the inverter 15 (i.e., controls the rotation speed of the compressor 2) to reduce the temperature difference. This threshold value is set in advance based on the minimum rotation speed of the compressor 2 at which surging of the compressor 2 does not occur. When the temperature difference is smaller than the threshold value, the operation control unit 27 controls the opening degree of the flow rate control valve 24 (i.e., controls the flow rate of the refrigerant vapor flowing through the hot gas bypass line 18) to reduce the temperature difference.

[0044] At partial loads where the temperature difference is less than the threshold, the expander 20 is driven by the refrigerant vapor flowing through the hot gas bypass line 18, allowing the generator 22 to generate electricity, thereby improving the COP. Additionally, controlling the refrigeration load using the hot gas bypass eliminates the need for a complex mechanism, reducing the number of parts and the risk of breakdowns. The inclusion of the expander 20 makes it possible to maintain a high level of COP even at low loads, making it practical to control capacity with the flow control valve 24 instead of the complex inlet guide vane 16. This allows for the compressor 2 to be made smaller and the risk of breakdown reduced, making it particularly suitable for use in cooling systems for mini-centrals in semiconductor manufacturing equipment, where compactness and reliability are required.

[0045] In this way, the compression chiller 1 can perform normal operation in which the heat transfer medium is cooled and no-load operation in which the heat transfer medium is not cooled by combining at least one of control of the opening of the inlet guide vane 16 (control of the suction flow rate of the refrigerant vapor) and control of the rotational speed of the compressor 2 (control of the rotation of the inverter 15) with control of the flow rate of the refrigerant vapor flowing through the hot gas bypass line 18. Furthermore, by combining the advantage of flow rate control using the hot gas bypass with the generation of power by the expander 20 and the generator 22, it is also possible to configure a compression chiller in which capacity is controlled only by the flow rate adjustment valve 24 and the expander 20. In particular, the compression chiller 1 of this embodiment is suitable for use as a cooling device for a mini-central in semiconductor manufacturing equipment that requires no-load operation.

[0046] As shown in FIG. 2, the compression chiller 1 further includes a refrigerant branch line 31 branching from the refrigerant pipe 5C and a refrigerant pump 35 disposed in the refrigerant branch line 31. The refrigerant branch line 31 is provided to transfer refrigerant liquid as a cooling liquid to the electric motor 13 of the compressor 2. The refrigerant branch line 31 includes a first section 31A extending downward from the refrigerant pipe 5C and connected to the refrigerant pump 35, and a second section 31B extending from the refrigerant pump 35 to the electric motor 13 of the compressor 2. One end of the first section 31A is connected to the refrigerant pipe 5C, and the other end of the first section 31A is connected to the suction port of the refrigerant pump 35. One end of the second section 31B is connected to the discharge port of the refrigerant pump 35, and the other end of the second section 31B is connected to a refrigerant nozzle 36 disposed in the electric motor 13 of the compressor 2. The refrigerant nozzle 36 is disposed facing components of the electric motor 13, such as the motor stator.

[0047] The refrigerant pump 35 is located below the refrigerant pipe 5C. Most of the refrigerant liquid flowing through the refrigerant pipe 5C flows to the evaporator 3, but some of the refrigerant liquid flowing through the refrigerant pipe 5C flows into the refrigerant branch line 31 and is sent to the refrigerant nozzles 36 by the refrigerant pump 35. The refrigerant liquid is sprayed from the refrigerant nozzles 36 into the interior of the electric motor 13, cooling the interior of the electric motor 13. The interior of the electric motor 13 is connected to the interior of the condenser 4 by a refrigerant liquid return line 38. More specifically, one end of the refrigerant liquid return line 38 is connected to the bottom of the electric motor 13, and the other end of the refrigerant liquid return line 38 is connected to the top of the condenser 4. The refrigerant liquid sprayed from the refrigerant nozzles 36 is collected inside the electric motor 13 and returned to the condenser 4 through the refrigerant liquid return line 38. The refrigerant liquid return line 38 extending from the bottom of the electric motor 13 may be connected to the evaporator 3.

[0048] The compression chiller 1 further includes a power line 39 that supplies the electric power generated by the generator 22 to the electric motor of the refrigerant pump 35. The power line 39 extends from the generator 22 to the refrigerant pump 35. According to this embodiment, the electric power generated by the generator 22 can be consumed within the compression chiller 1. As a result, a decrease in the coefficient of performance (COP) of the compression chiller 1 can be prevented.

[0049] In one embodiment, the power generated by the generator 22 may supply both the electric motor 13 of the compressor 2 and the electric motor of the refrigerant pump 35 .

[0050] FIG. 3 is a diagram showing another embodiment of the compression refrigerator 1. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment shown in FIG. 1 , and therefore, redundant description will be omitted. In this embodiment, the compressor 2 includes a magnetic bearing 43 that supports its rotating shaft 42. The compression refrigerator 1 further includes a power line 45 that supplies power generated by the generator 22 to the magnetic bearing 43. The power line 45 extends from the generator 22 to the magnetic bearing 43. According to this embodiment, the power generated by the generator 22 can be consumed within the compression refrigerator 1. As a result, a decrease in the coefficient of performance (COP) of the compression refrigerator 1 can be prevented. The use of the magnetic bearing 43 as the bearing that supports the rotating shaft 42 provides contactless, oil-free support, reducing maintenance such as bearing replacement and lubricant replacement.

[0051] FIG. 4 illustrates another embodiment of the compression refrigerator 1. The configuration and operation of this embodiment, unless otherwise specified, are the same as those of the embodiment shown in FIG. 1 , and therefore, redundant explanations will be omitted. In this embodiment, the expander 20 includes a magnetic bearing 51 supporting its rotating shaft 50. The compression refrigerator 1 further includes a power line 52 that supplies power generated by the generator 22 to the magnetic bearing 51. The power line 52 extends from the generator 22 to the magnetic bearing 51. According to this embodiment, the power generated by the generator 22 can be consumed within the compression refrigerator 1. As a result, a decrease in the coefficient of performance (COP) of the compression refrigerator 1 can be prevented. Furthermore, the expander 20 itself can generate power to supply levitation power to the magnetic bearing 51 even during a power outage, enabling self-maintenance of levitation. The use of the magnetic bearing 51 as the bearing supporting the rotating shaft 50 provides contactless, oil-free support, reducing maintenance such as bearing replacement and lubricant oil replacement.

[0052] The embodiments shown in Figures 1 to 4 may be combined as appropriate. For example, the embodiment shown in Figure 3 and the embodiment shown in Figure 4 may be combined.

[0053] Figure 5 is a graph showing the relationship between the refrigeration capacity and the flow rate in the hot gas bypass line 18 when the refrigeration capacity is adjusted by controlling the flow rate in the hot gas bypass line 18, and shows the results obtained by simulation. The vertical axis is the ratio of the flow rate of the hot gas flowing in the hot gas bypass line 18 to the discharge flow rate of the compressor 2. For example, if this value is 50%, it indicates that half of the compressed refrigerant vapor flows into the hot gas bypass line 18 and bypasses to the evaporator 3 without passing through the condenser 4.

[0054] This simulation was calculated based on the actual results of a two-stage compression, one-stage economizer cycle. As shown in Figure 5, the relationship between the hot gas bypass flow rate and refrigeration capacity is approximated by a straight line with a negative slope. In other words, there is a linear relationship between the hot gas bypass flow rate and refrigeration capacity. If the relationship between the opening of the flow control valve 24 and the hot gas flow rate is close to linear, the relationship between the opening of the flow control valve 24 and refrigeration capacity will also be close to linear, resulting in high controllability and easy stability of the heat medium temperature. It is also clear from this figure that the smaller the refrigeration capacity, the greater the amount of power generation.

[0055] Figure 6 compares the COP between capacity control using only hot gas bypass flow rate adjustment without the expander 20 and capacity control using only hot gas bypass flow rate control with the expander 20. A simulation of a two-stage compression, one-stage economizer cycle was performed with constant compressor and expander efficiencies. With capacity control using only hot gas bypass without the expander 20, the COP decreases almost linearly. This is because with hot gas bypass capacity control, the compression power of the compressor 2 remains nearly constant across the entire operating range, but the refrigeration capacity decreases due to the hot gas bypass. This graph shape is obtained using the formula COP = refrigeration capacity / input power. With the expander 20 and generator 22, the COP improves across the entire range except for 100% load, where the hot gas bypass flow rate is zero.

[0056] FIG. 7 is a graph showing the COP ratios in FIG. 6. The graph shows the ratio of the COP of flow control of the hot gas bypass equipped with the expander 20 to the COP of flow control of the hot gas bypass without the expander 20 under the same operating conditions. In other words, it shows the energy-saving effect when the expander 20 and the generator 22 are installed in the hot gas bypass line 18. For example, if the COP ratio is 2, power consumption is halved. It can be seen that the effect of the expander 20 becomes more pronounced as the load becomes lower. The tendency of this effect is due to the difference in the amount of power generated by the hot gas bypass flow rate in FIG. 6. In the simulation results, the COP ratio exceeded 2 when the refrigeration load was 20% or less.

[0057] 8 is a diagram showing an embodiment in which the compression refrigerator 1 of any of the embodiments shown in FIGS. 1 to 4 is used as a cooling device in a semiconductor manufacturing system. The semiconductor manufacturing system includes a temperature control system 101 and a plurality of semiconductor manufacturing apparatuses 102. The temperature control system 101 is configured to supply a heat medium to the plurality of semiconductor manufacturing apparatuses 102 (e.g., etching apparatus, CVD apparatus, PVD apparatus, etc.) to adjust the temperatures of the plurality of semiconductor manufacturing apparatuses 102.

[0058] The temperature control system 101 is configured to use a first heat medium, a second heat medium, and a third heat medium to control the temperature of the heat medium used in a plurality of semiconductor manufacturing apparatuses 102. The temperature control system 101 includes a first circulation circuit 111 through which the first heat medium circulates, a second circulation circuit 112 through which the second heat medium circulates, a plurality of third circulation circuits 113 through which the third heat medium circulates, a compression refrigerator 1 as a cooling device that cools the first heat medium flowing in the first circulation circuit 111, and a heating device 108 that heats the second heat medium flowing in the second circulation circuit 112.

[0059] The temperature control system 101 further includes a plurality of first heat exchangers 121 and a plurality of second heat exchangers 122. The plurality of first heat exchangers 121 are connected to the first circulation circuit 111 and the plurality of third circulation circuits 113. The plurality of second heat exchangers 122 are connected to the second circulation circuit 112 and the plurality of third circulation circuits 113. The plurality of first heat exchangers 121 are configured to perform heat exchange between the first heat medium cooled by the compression refrigerator 1 and the third heat medium circulating through the plurality of third circulation circuits 113. The plurality of second heat exchangers 122 are configured to perform heat exchange between the second heat medium heated by the heating device 108 and the third heat medium circulating through the plurality of third circulation circuits 113.

[0060] The compression refrigerator 1 serving as a cooling device is connected to a first circulation circuit 111. The heating device 108 is connected to a second circulation circuit 112. The temperature control system 101 includes a plurality of first variable speed pumps 114 connected in series to a plurality of first heat exchangers 121 by the first circulation circuit 111, and the first heat medium is circulated through the first circulation circuit 111 by the first pumps 114. The temperature control system 101 includes a second pump 115 connected to the second circulation circuit 112, and the second heat medium is circulated through the second circulation circuit 112 by the second pump 115.

[0061] The semiconductor manufacturing equipment 102 is respectively connected to a plurality of third circulation circuits 113. A third heat medium circulates through each third circulation circuit 113 and each semiconductor manufacturing equipment 102. The processing temperature in each semiconductor manufacturing equipment 102 is adjusted by the third heat medium flowing through the corresponding third circulation circuit 113. The temperature of the third heat medium is adjusted by the first heat medium and the second heat medium, as described below. The flow rate of the third heat medium circulating through the third circulation circuit 113 and flowing to the first heat exchanger 121 and the second heat exchanger 122 is adjusted by a pump, a valve, etc. (not shown).

[0062] Different heat media can be used for the first, second, and third heat media. For example, common brine is used as the first heat medium for cooling. Examples of brine include ethylene glycol, propylene glycol, and calcium chloride. An example of the second heat medium for heating is silicone oil. An example of the third heat medium is a fluorine-based inert liquid. The third heat medium is an insulator that is chemically stable from low to high temperatures to directly adjust the processing temperature within the semiconductor manufacturing equipment 102.

[0063] The lower limit usable temperature of the third heat medium is lower than the lower limit usable temperatures of the first heat medium and the second heat medium. The upper limit usable temperature of the third heat medium is higher than the upper limit usable temperatures of the first heat medium and the second heat medium. In other words, the usable temperature range of the third heat medium is wider than the usable temperature ranges of the first heat medium and the second heat medium. The usable temperature is the temperature at which the viscosity (fluidity) of the heat medium can be maintained and the heat medium does not change phase (does not boil or solidify).

[0064] The temperature control system 101 includes a first buffer tank 116 that holds a first heat medium and a second buffer tank 117 that holds a second heat medium. The first buffer tank 116 is connected to the first circulation circuit 111, and the second buffer tank 117 is connected to the second circulation circuit 112. In one embodiment, the first buffer tank 116 and the second buffer tank 117 may not be provided.

[0065] The multiple first heat exchangers 121 are connected in parallel by a first circulation circuit 111. More specifically, the first circulation circuit 111 has a first heat medium supply line 131 for supplying the first heat medium cooled by the compression refrigerator 1 to the multiple first heat exchangers 121, a first heat medium return line 132 for returning the first heat medium that has exchanged heat with a third heat medium in the multiple first heat exchangers 121 to the compression refrigerator 1, and multiple first branch lines 133 connected to the first heat medium supply line 131 and the first heat medium return line 132. One end of each first branch line 133 is connected to the first heat medium supply line 131, and the other end of each first branch line 133 is connected to the first heat medium return line 132.

[0066] The plurality of first variable speed pumps 114 are respectively connected to the plurality of first branch lines 133. The plurality of first variable speed pumps 114 are located upstream of the plurality of first heat exchangers 121 and downstream of the compression refrigerator 1 in the flow direction of the first heat medium.

[0067] The plurality of first heat exchangers 121 are respectively connected to a plurality of first branch lines 133. The first heat medium cooled by the compression refrigerator 1 is transferred to the plurality of first heat exchangers 121 through the first heat medium return line 132 and the plurality of first branch lines 133. The first heat medium that has exchanged heat with the third heat medium in the plurality of first heat exchangers 121 passes through the plurality of first branch lines 133 and the first heat medium return line 132, and is returned to the compression refrigerator 1 via the first buffer tank 116.

[0068] The multiple second heat exchangers 122 are connected in parallel by a second circulation circuit 112. More specifically, the second circulation circuit 112 has a second heat medium supply line 141 for supplying the second heat medium heated by the heating device 108 to the multiple second heat exchangers 122, a second heat medium return line 142 for returning the second heat medium that has exchanged heat with the third heat medium in the multiple second heat exchangers 122 to the heating device 108, and multiple second branch lines 143 connected to the second heat medium supply line 141 and the second heat medium return line 142. One end of each second branch line 143 is connected to the second heat medium supply line 141, and the other end of each second branch line 143 is connected to the second heat medium return line 142.

[0069] The plurality of second heat exchangers 122 are respectively connected to a plurality of second branch lines 143. The second heat medium heated by the heating device 108 is transferred to the plurality of second heat exchangers 122 through the second heat medium return line 142 and the plurality of second branch lines 143. The second heat medium that has exchanged heat with the third heat medium in the plurality of second heat exchangers 122 is returned to the heating device 108 through the plurality of second branch lines 143 and the second heat medium return line 142.

[0070] The multiple first heat exchangers 121 and the multiple second heat exchangers 122 constitute multiple groups G1, G2, and G3 of first heat exchangers 121 and second heat exchangers 122. The first heat exchangers 121 and second heat exchangers 122 of the multiple groups G1, G2, and G3 are respectively connected to multiple third circulation circuits 113. The first heat exchangers 121 and second heat exchangers 122 of the multiple groups G1, G2, and G3 are connected to multiple semiconductor manufacturing equipment 102 by the multiple third circulation circuits 113. The processing temperatures in the multiple semiconductor manufacturing equipment 102 are independently controlled by a third heat medium whose temperature is regulated by the first heat exchangers 121 and second heat exchangers 122 of the multiple groups G1, G2, and G3.

[0071] According to the embodiment shown in FIG. 8, the temperature of the third heat medium is adjusted using a first heat medium cooled by a compression refrigerator 1 and a second heat medium heated by a heating device 8, and the temperature-adjusted third heat medium is supplied to a plurality of semiconductor manufacturing apparatuses 102, thereby enabling the processing temperatures in the plurality of semiconductor manufacturing apparatuses 102 to be adjusted using the heat medium.

[0072] The multiple semiconductor manufacturing equipment 102 executes the manufacturing process while changing the processing temperature in accordance with the manufacturing process. When the multiple semiconductor manufacturing equipment 102 executes the manufacturing process while heating the wafers, the refrigeration load on the compression refrigerator 1 is substantially zero. The compression refrigerator 1 of the embodiment shown in FIGS. 1 to 4 can execute no-load operation by flowing refrigerant vapor through the hot gas bypass line 18. Furthermore, the refrigerant vapor flowing through the hot gas bypass line 18 drives the expander 20 and the generator 22, which can generate electricity, thereby realizing a reduction in the power consumption of the cooling device of the semiconductor manufacturing system.

[0073] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0074] 1. Compression Refrigeration Unit 2 Compressor 3. Evaporator 4. Condenser 5A,5B,5C Refrigerant piping 7 Expansion valve 11 Impeller 13 Electric motor 15 Inverter 16 Inlet guide vane 18 Hot gas bypass line 20 Expander 22 Generator 24 Flow control valve 27 Operation control section 30 Power Lines S1, S2 temperature sensors 31 Refrigerant branch line 35 Refrigerant pump 36 Refrigerant nozzle 38 Refrigerant liquid return line 39 Power Lines 42 Rotation axis 43 Magnetic bearings 45 Power Lines 50 Rotational Axis 51 Magnetic bearings 52 Power Lines 101 Temperature Control System 102 Semiconductor manufacturing equipment 108 Heating device 111 1st circulation circuit 112 Second circulation circuit 113 Third circulation circuit 114 First variable speed pump 115 Second Pump 116 First Buffer Tank 117 Second Buffer Tank 121 1st heat exchanger 122 Second heat exchanger 131 First heat transfer line 132 First heat medium return line 133 First Branch Line 141 Second heat transfer line 142 Second heat medium return line 143 Second Branch Line

Claims

1. an evaporator for evaporating a refrigerant liquid to produce a refrigerant vapor; a compressor that compresses the refrigerant vapor; a condenser for condensing the compressed refrigerant vapor to produce the refrigerant liquid; a hot gas bypass line that guides the compressed refrigerant vapor to the evaporator, bypassing the condenser; an expander disposed in the hot gas bypass line; a generator connected to the expander and driven by the expander; a flow control valve for adjusting the flow rate of the compressed refrigerant vapor flowing through the hot gas bypass line;

2. 2. The compression refrigerator according to claim 1, further comprising a power line that supplies the electric power generated by the generator to an electric motor of the compressor.

3. a refrigerant branch line that supplies the refrigerant liquid as a cooling liquid to the electric motor of the compressor; a refrigerant pump disposed in the refrigerant branch line and configured to transport the refrigerant liquid; 2. The compression refrigerator according to claim 1, further comprising a power line for supplying the electric power generated by the generator to an electric motor of the refrigerant pump.

4. an inverter that changes the rotation speed of the motor of the compressor; 2. The compression refrigerator according to claim 1, further comprising an operation control unit that controls operation of at least one of the flow rate adjustment valve and the inverter so that the temperature of the heat medium flowing out of the evaporator reaches a target temperature.

5. 5. The compression refrigerator according to claim 4, wherein the operation control unit is configured to select either the flow rate control valve or the inverter based on a difference between a temperature of the heat medium flowing out of the evaporator and a temperature of the heat medium flowing into the evaporator, and to control operation of the selected flow rate control valve or the selected inverter.

6. an inlet guide vane that adjusts the intake flow rate of the refrigerant vapor into the compressor; 2. The compression refrigerator according to claim 1, further comprising an operation control unit that controls operation of at least one of the flow rate adjustment valve and the inlet guide vane so that the temperature of the heat medium flowing out of the evaporator reaches a target temperature.

7. 7. The compression refrigerator according to claim 6, wherein the operation control unit is configured to select either the flow rate control valve or the inlet guide vane based on a difference between a temperature of the heat medium flowing out of the evaporator and a temperature of the heat medium flowing into the evaporator, and to control an operation of the selected flow rate control valve or the selected inlet guide vane.

8. The compression type refrigerator further includes an inverter that changes the rotation speed of the motor of the compressor, 7. The compression refrigerator according to claim 6, wherein the operation control unit is configured to control operation of at least one of the flow rate adjustment valve, the inlet guide vane, and the inverter so that a temperature of the heat medium flowing out of the evaporator reaches a target temperature.

9. 2. The compression refrigerator according to claim 1, wherein the compressor includes a magnetic bearing that supports a rotating shaft.

10. 2. The compression refrigerator according to claim 1, wherein the expander includes a magnetic bearing that supports a rotating shaft.

11. Semiconductor manufacturing equipment, A semiconductor manufacturing system comprising the compression refrigerator according to any one of claims 1 to 10.

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