Cooling mechanism

Abstract

To provide a cooling mechanism for CO2 refrigerant capable of operating below a critical pressure even with a realistic flow rate of industrial water.SOLUTION: Control means 4 of a cooling mechanism 2 controls an opening degree of a variable expansion valve 32 and a rotation speed of a compressor 6 according to a path regulated by a set pressure value and a set temperature within a range in which a CO2 refrigerant does not exceed a critical point specified by a critical temperature of 31.1°C and a critical pressure of 7.38 MPa, so that a value of a first temperature sensor 36 or a second temperature sensor 38 becomes the set temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cooling mechanism for cooling a processing liquid used in a processing device. [Background technology]

[0002] A wafer has a number of devices such as ICs and LSIs formed on its front surface along planned dividing lines, and the back surface is ground by a grinding machine to form it to a specified thickness. The wafer is then divided into individual device chips using a dicing machine and laser processing machine, and each of the divided device chips is used in electrical equipment such as mobile phones and personal computers.

[0003] When processing a wafer, if the spindle unit on which the processing tools constituting the grinding or dicing device are attached generates heat and expands, high-precision grinding or cutting becomes impossible. For this reason, a temperature control device is used to control the temperature of the spindle unit to be constant (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-40396 A Summary of the Invention [Problem to be solved by the invention]

[0005] The temperature control device described in the above Patent Document 1 is a CO 2 This type of equipment uses as a refrigerant, and can achieve high cooling efficiency. It can also cool the heat source to a low temperature of 10℃ or less.

[0006] However, when the set temperature of the processing liquid (for example, the circulating water that cools the heat source) used in the processing equipment is set to a low temperature, the amount of CO 2The pressure of the refrigerant drops. In this case, the CO 2 If the compressor is operated at a pressure higher than the critical pressure of the refrigerant, the pressure difference between the inflow and outflow of the compressor increases, placing a heavy load on the compressor, which can lead to problems such as a shortened compressor lifespan and increased power consumption.

[0007] Therefore, CO 2 It is conceivable that the load on the compressor can be reduced by compressing the refrigerant. This would extend the compressor's lifespan and reduce the compressor's power consumption. However, the CO 2 The condensation temperature of is close to that of typical industrial water, and the CO 2 The density of CO in gas state is high. Therefore, CO can be reduced by controlling the amount of industrial water. 2 The flow rate of industrial water required to keep the refrigerant below the critical pressure would be unrealistically large.

[0008] The objective of this invention is to develop a CO2 suction device that can be operated below the critical pressure even with a realistic industrial water flow rate. 2 The object of the present invention is to provide a cooling mechanism for the refrigerant. [Means for solving the problem]

[0009] According to the present invention, there is provided the following cooling mechanism that solves the above problems. "A cooling mechanism for cooling the processing liquid used in the processing device, A control means; CO 2 A compressor that compresses a refrigerant; The CO compressed by the compressor and carrying the heat of compression 2 a water-cooled gas cooler for cooling the refrigerant; Chilled CO 2 an internal heat exchanger into which a refrigerant is pumped; CO sent out from the internal heat exchanger 2 An evaporator that vaporizes a refrigerant to generate heat of vaporization and cools a processing liquid used in a processing device; a first passage connecting the compressor and the water-cooled gas cooler; a second passage connecting the water-cooled gas cooler and the evaporator; a third passage connecting the evaporator and the compressor; a fourth passage for introducing industrial water into the water-cooled gas cooler and having a water control valve; a bypass passage connected to the first passage by a first connection part connected to the first passage and a second connection part connected to the second passage, the bypass passage including a variable bypass valve; The internal heat exchanger is configured to convert the CO 2 The refrigerant is CO sent out from the water-cooled gas cooler. 2 a heat exchanger disposed across the second path and the third path so as to remove heat from the refrigerant; The second pathway includes cooled CO 2 a variable expansion valve for adjusting a flow rate of the refrigerant is disposed between the internal heat exchanger and the second connection; CO compressed by the compressor is supplied to either the first path or the second path between the compressor and the variable expansion valve. 2 A pressure sensor is provided to measure the pressure of the refrigerant. A first temperature sensor for measuring a temperature of the processing liquid used in the processing device when the processing liquid flows out of the evaporator; A second temperature sensor that measures the temperature of the processing liquid flowing into the evaporator; a third temperature sensor for measuring the temperature of the industrial water flowing into the water-cooled gas cooler; CO discharged from the internal heat exchanger in the second path. 2 a fourth temperature sensor for measuring the temperature of the refrigerant; the control means includes a setting unit that sets a pressure value to be detected by the pressure sensor, a first temperature to be detected by the first temperature sensor or a second temperature to be detected by the second temperature sensor, and a fourth temperature to be detected by the fourth temperature sensor; The CO 2The present invention provides a cooling mechanism that controls the opening of the variable expansion valve and the rotation speed of the compressor according to a path defined by the set pressure value and temperature within a range in which the refrigerant does not exceed a critical point specified by a critical temperature of 31.1°C and a critical pressure of 7.38 MPa.

[0010] Preferably, when the control means reduces the amount of cooling of the processing liquid used in the processing device, the control means reduces the opening degree of the variable expansion valve to reduce the amount of CO flowing through the evaporator. 2 The flow rate of the refrigerant is reduced, and the opening degree of the variable bypass valve of the bypass path is increased to reduce the amount of CO flowing into the evaporator so that the compressor does not reach the lower limit. 2 Increase the flow rate of the refrigerant.

[0011] When the amount of cooling of the processing liquid used in the processing device is increased, the control means increases the opening degree of the variable expansion valve and increases the rotation speed of the compressor to reduce the amount of CO flowing through the evaporator. 2 Increasing the flow rate of the refrigerant and the associated CO2 output from the evaporator 2 Liquid CO remaining in the refrigerant 2 It is desirable to vaporize the refrigerant in the internal heat exchanger to reduce the load on the compressor.

[0012] The control means The CO detected by the pressure sensor based on the temperature of the industrial water detected by the third temperature sensor. 2 Set the condensation pressure of the refrigerant, CO obtained from the condensation pressure 2 a value to be detected by the fourth temperature sensor is set based on a condensation temperature of the refrigerant and a rotation speed of the compressor; adjusting an opening of the water control valve so that the detection value of the fourth temperature sensor becomes the set value, thereby adjusting a flow rate of industrial water introduced into the water-cooled gas cooler; It is preferable to control the condensation pressure by decreasing the opening of the variable expansion valve to increase the value detected by the pressure sensor, and by increasing the opening of the variable expansion valve to decrease the value detected by the pressure sensor. Effect of the Invention

[0013] The cooling mechanism of the present invention comprises: A control means; CO 2 A compressor that compresses a refrigerant; The CO compressed by the compressor and carrying the heat of compression 2 a water-cooled gas cooler for cooling the refrigerant; Chilled CO 2 an internal heat exchanger into which a refrigerant is pumped; CO sent out from the internal heat exchanger 2 An evaporator that vaporizes a refrigerant to generate heat of vaporization and cools a processing liquid used in a processing device; a first passage connecting the compressor and the water-cooled gas cooler; a second passage connecting the water-cooled gas cooler and the evaporator; a third passage connecting the evaporator and the compressor; a fourth passage for introducing industrial water into the water-cooled gas cooler and having a water control valve; a bypass passage connected to the first passage by a first connecting portion connected to the first passage and a second connecting portion connected to the second passage, the bypass passage including a variable bypass valve; The internal heat exchanger is configured to convert the CO 2 The refrigerant is CO sent out from the water-cooled gas cooler. 2 a heat exchanger disposed across the second path and the third path so as to remove heat from the refrigerant; The second pathway includes cooled CO 2 a variable expansion valve for adjusting a flow rate of the refrigerant is disposed between the internal heat exchanger and the second connection; CO compressed by the compressor is supplied to either the first path or the second path between the compressor and the variable expansion valve. 2 A pressure sensor is provided to measure the pressure of the refrigerant. A first temperature sensor for measuring a temperature of the processing liquid used in the processing device when the processing liquid flows out of the evaporator; A second temperature sensor that measures the temperature of the processing liquid flowing into the evaporator; a third temperature sensor for measuring the temperature of the industrial water flowing into the water-cooled gas cooler; CO discharged from the internal heat exchanger in the second path. 2 a fourth temperature sensor for measuring the temperature of the refrigerant; the control means includes a setting unit that sets a pressure value to be detected by the pressure sensor, a first temperature to be detected by the first temperature sensor or a second temperature to be detected by the second temperature sensor, and a fourth temperature to be detected by the fourth temperature sensor; The CO 2 The opening of the variable expansion valve and the rotation speed of the compressor are controlled according to a path defined by the set pressure value and temperature within a range in which the refrigerant does not exceed the critical point specified by a critical temperature of 31.1°C and a critical pressure of 7.38 MPa, making it possible to operate below the critical pressure even with a realistic flow rate of industrial water. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a circuit diagram of a cooling mechanism according to the present invention. [Diagram 2] CO2 pH diagram. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a cooling mechanism according to the present invention will be described with reference to the drawings.

[0016] (Cooling mechanism 2) Figure 1 shows the processing fluid used in the processing equipment. 2 A cooling mechanism 2 for cooling by a refrigerant is shown. The cooling mechanism 2 comprises a control means 4, a compressor 6, a water-cooled gas cooler 8, an internal heat exchanger 10 and an evaporator 12.

[0017] (Control Means 4) The control means 4 is composed of a computer having a processor and a memory. The control means 4 in this embodiment includes a setting unit 4a and a control unit 4b. The setting unit 4a controls the temperature of the CO 2 The control unit 4b sets the pressure and temperature of the refrigerant. The control unit 4b controls the opening of the variable expansion valve 32 and the rotation speed of the compressor 6 so that the actual temperature of the processing liquid becomes the set temperature (the temperature input by the operator). The details of the control by the control unit 4b will be described later in detail.

[0018] (Compressor 6) The compressor 6 is configured to compress the CO circulating through the cooling mechanism 2. 2 The compressor 6 compresses the refrigerant. As shown in FIG. 1, the motor 6a that drives the compressor 6 is provided with an inverter 6b. The inverter 6b changes the frequency of the power supplied to the motor 6a within a predetermined range (for example, 20 Hz to 120 Hz). This changes the rotation speed of the motor 6a and changes the rotation speed of the compressor 6 within the range of the allowable rotation speed (between a lower limit and an upper limit). The inverter 6b is electrically connected to the control means 4 and is controlled by a control unit 4b of the control means 4.

[0019] (Water-cooled gas cooler 8) The water-cooled gas cooler 8 cools the CO 2 compressed by the compressor 6 with heat of compression. 2 As shown in FIG. 1, the water-cooled gas cooler 8 cools the refrigerant. 2 Industrial water is introduced to cool the refrigerant. Although not shown, CO 2 A refrigerant passage through which the refrigerant flows and a water passage through which industrial water flows are formed. In the water-cooled gas cooler 8, CO 2 By exchanging heat between the refrigerant and the industrial water in the waterway, the CO 2 The refrigerant is cooled.

[0020] (internal heat exchanger 10) The internal heat exchanger 10 is supplied with CO cooled by a water-cooled gas cooler 8.2 Although not shown, the internal heat exchanger 10 is supplied with CO refrigerant cooled by a water-cooled gas cooler 8. 2 A first passage through which the refrigerant passes, and the CO after cooling the processing liquid in the evaporator 12 2 In the internal heat exchanger 10, the CO 2 Refrigerant and CO in the second passage 2 Heat exchange occurs between the refrigerant and the evaporator 12. As a result, the CO 2 The refrigerant is CO in the first passage sent from the water-cooled gas cooler 8. 2 This removes heat from the refrigerant, leaving the CO 2 The refrigerant becomes completely gaseous (details will be given later).

[0021] (Evaporator 12) The evaporator 12 evaporates the CO 2 The refrigerant is vaporized to generate heat of vaporization, and the generated heat of vaporization is used to cool the processing liquid used in the processing device. 2 A refrigerant passage through which the refrigerant flows and a processing contributing liquid passage through which the processing contributing liquid flows are provided. 2 By exchanging heat between the refrigerant and the processing liquid in the processing liquid passage, 2 The processing liquid is cooled by the heat of vaporization of the refrigerant.

[0022] (First to fourth routes 14, 16, 18, 22, bypass route 30) 1, the cooling mechanism 2 further includes a first path 14 connecting the compressor 6 and the water-cooled gas cooler 8, a second path 16 connecting the water-cooled gas cooler 8 and the evaporator 12, a third path 18 connecting the evaporator 12 and the compressor 6, a fourth path 22 that introduces industrial water to the water-cooled gas cooler 8 and is equipped with a water control valve 20, and a bypass path 30 that is connected by a first connecting part 24 connected to the first path 14 and a second connecting part 26 connected to the second path 16 and is equipped with a variable bypass valve 28. The second path 16 introduces cooled CO 2 A variable expansion valve 32 that adjusts the flow rate of the refrigerant is disposed between the internal heat exchanger 10 and the second connecting portion 26. In addition, the internal heat exchanger 10 is disposed across the second path 16 and the third path 18.

[0023] (Water control valve 20, variable bypass valve 28, variable expansion valve 32) 1, the water control valve 20, the variable bypass valve 28, and the variable expansion valve 32 are provided with motors 20a, 28a, and 32a for adjusting the opening degree, respectively. The motors 20a, 28a, and 32a are all electrically connected to the control means 4. The opening degrees of the water control valve 20, the variable bypass valve 28, and the variable expansion valve 32 are adjusted by the motors 20a, 28a, and 32a, respectively, based on instructions from the control unit 4b of the control means 4.

[0024] Cooling mechanism 2 CO 2 The refrigerant passes through the first to third paths 14, 16, and 18 in this order, and circulates through the compressor 6, the water-cooled gas cooler 8, the internal heat exchanger 10, the evaporator 12, and the internal heat exchanger 10 in this order. 2 The refrigerant passes through the internal heat exchanger 10 twice in principle before returning to the compressor 6. Specifically, the CO 2 The refrigerant passes through an internal heat exchanger 10, then through an evaporator 12, and then through the internal heat exchanger 10 again.

[0025] However, when the variable bypass valve 28 is opened, the CO compressed by the compressor 6 2A portion of the refrigerant is sent to the evaporator 12 through a bypass path 30 without passing through the water-cooled gas cooler 8 and the internal heat exchanger 10.

[0026] (Pressure Sensor) The cooling mechanism 2 is provided with CO compressed by a compressor 6. 2 A pressure sensor 34 that measures the pressure of the refrigerant is provided. The pressure sensor 34 may be provided in either the first path 14 or the second path 16 between the compressor 6 and the variable expansion valve 32. In this embodiment, the pressure sensor 34 is provided in the first path 14, between the compressor 6 and the water-cooled gas cooler 8. The value measured by the pressure sensor 34 is sent to the control means 4.

[0027] (Temperature sensor) The cooling mechanism 2 is provided with processing liquid, industrial water, and CO 2 A plurality of temperature sensors are provided to measure the respective temperatures of the refrigerants. The values ​​measured by each temperature sensor are all sent to the control means 4.

[0028] (Sensor that measures the temperature of the processing liquid) As sensors for measuring the temperature of the processing-contributing liquid, first and second temperature sensors 36, 38 are provided. The first temperature sensor 36 measures the temperature of the processing-contributing liquid flowing out of the evaporator 12. On the other hand, the second temperature sensor 38 measures the temperature of the processing-contributing liquid flowing into the evaporator 12.

[0029] (Sensor for measuring temperature of industrial water) As a sensor for measuring the temperature of the industrial water, a third temperature sensor 40 is provided. The third temperature sensor 40 measures the temperature of the industrial water flowing into the water-cooled gas cooler 8.

[0030] (CO 2 Sensor that measures the refrigerant temperature) CO 2A fourth temperature sensor 42 is provided as a sensor for measuring the temperature of the refrigerant. The fourth temperature sensor 42 is a sensor for measuring the temperature of the refrigerant discharged from the internal heat exchanger 10 in the second path 16. 2 The fourth temperature sensor 42 measures the temperature of the refrigerant. For this purpose, the fourth temperature sensor 42 is disposed between the internal heat exchanger 10 and the variable expansion valve 32.

[0031] (Processing contribution liquid) The processing-contributing liquid cooled by the cooling mechanism 2 is used, for example, in a dicing device (not shown) that cuts a semiconductor wafer. The dicing device is equipped with cutting means for cutting the semiconductor wafer. FIG. 1 shows an exploded perspective view of a spindle housing 44 that rotatably houses a spindle of the cutting means, and the spindle housing 44 is connected to the evaporator 12 by a pipe 46. The processing-contributing liquid is circulated between the spindle housing 44 and the evaporator 12 via the pipe 46.

[0032] However, the processing equipment using the processing-contributing liquid cooled by the cooling mechanism 2 is not limited to a dicing equipment, and various processing equipment such as a grinding equipment for grinding and thinning a semiconductor wafer can be the target. Note that the processing-contributing liquid includes not only the circulating liquid circulating in the processing equipment, but also fluids that are used as processing water and discarded, such as cutting water.

[0033] (Operation of cooling mechanism 2) From here on, we will explain the operation of the above-mentioned cooling mechanism 2. First, we will explain the basic operation of the cooling mechanism 2, and then we will explain the operation when increasing or decreasing the cooling amount of the processing-contributing liquid.

[0034] (Basic operation) First, in the cooling mechanism 2, when an operation command is input to the control means 4 by an operator, the setting unit 4a of the control means 4 sets values ​​(set values) to be detected by each sensor in response to the input operation command. 2The setting unit 4a sets the set pressure and temperature of the refrigerant. The set temperature of the processing liquid is the temperature input by the operator. 2 The set pressure and temperature of the coolant are determined by the control means 4 based on the set temperature of the processing liquid.

[0035] (Set temperature of processing liquid) First, the setting unit 4a sets, as the set temperature of the processing contributing liquid, a first temperature to be detected by the first temperature sensor 36 or a second temperature to be detected by the second temperature sensor 38. The first temperature is the set temperature of the processing contributing liquid flowing out of the evaporator 12. On the other hand, the second temperature is the set temperature of the processing contributing liquid flowing into the evaporator 12. For example, the first temperature can be set to 23°C, and the second temperature can be set to 25°C.

[0036] (CO 2 Refrigerant pressure setting) In addition, the setting unit 4a 2 The pressure value to be detected by the pressure sensor 34 is set as the set pressure of the refrigerant. This pressure value is the pressure of the CO 2 This is the set pressure of the refrigerant. The pressure value is CO 2 The critical pressure of the sintered body is set to a value not exceeding 7.38 MPa (for example, 6.5 MPa).

[0037] (CO 2 Coolant temperature setting) Furthermore, the setting unit 4a 2 As the set temperature of the refrigerant, a fourth temperature to be detected by the fourth temperature sensor 42 is set. The fourth temperature is the temperature of the CO 2 discharged from the internal heat exchanger 10 through the second path 16. 2 Refrigerant (CO sent to the evaporator 12 via the variable expansion valve 32) 2 The fourth temperature is the set temperature of the CO 2 The condensation temperature is set to a temperature lower than that of the

[0038] In this way, the setting unit 4a sets the pressure value to be detected by the pressure sensor 34, the first temperature to be detected by the first temperature sensor 36 or the second temperature to be detected by the second temperature sensor 38, and the fourth temperature to be detected by the fourth temperature sensor 42.

[0039] (Control by control unit 4b) The setting unit 4a sets the set temperature of the processing liquid, CO 2 When the set pressure and set temperature of the refrigerant are set, the control unit 4b controls the CO 2 The opening of the variable expansion valve 32 and the rotation speed of the compressor 6 are controlled according to a route defined by a pressure value and a temperature set within a range in which the refrigerant does not exceed the critical point.

[0040] (Opening degree of variable expansion valve 32) By controlling the opening degree of the variable expansion valve 32, 2 The pressure of the refrigerant and the temperature of the processing liquid can be adjusted. When the opening degree of the variable expansion valve 32 is increased, the CO 2 Since the flow rate of the refrigerant increases, the value of the pressure sensor 34 decreases. Also, when the opening degree of the variable expansion valve 32 increases, the amount of CO 2 As the flow rate of the refrigerant increases, the values ​​(temperature of the processing liquid) of the first and second temperature sensors 38, 40 decrease. On the other hand, as the opening degree of the variable expansion valve 32 decreases, the value of the pressure sensor 34 increases and the values ​​of the first and second temperature sensors 38, 40 increase.

[0041] (Compressor 6 rotation speed) In addition, the rotation speed of the compressor 6 is controlled to reduce the amount of CO 2 The pressure of the refrigerant can be adjusted. When the rotation speed of the compressor 6 increases, the amount of CO discharged from the compressor 6 decreases. 2 As the amount of refrigerant increases, the value of the pressure sensor 34 increases. Conversely, as the rotation speed of the compressor 6 decreases, the value of the first pressure sensor 34 decreases.

[0042] (critical point) The critical point is generally a point specified by the temperature and pressure at which a substance is in a supercritical state. 2 The critical temperature is 31.1°C and the critical pressure is 7.38MPa, where CO 2 The critical point of CO is indicated by the symbol P. 2 This is a pH diagram (Mollier diagram) of the above, with the vertical axis representing pressure and the horizontal axis representing enthalpy.

[0043] (Routes that do not exceed the critical point) Pathways that do not exceed the critical point (CO 2 The route (defined by the pressure and temperature values ​​set within a range where the refrigerant does not exceed the critical point) is, for example, route R passing through points A, B, C, D, E, and F in Fig. 2. Points A to F in Fig. 2 are points plotted based on the temperatures and pressures at points A to F shown in Fig. 1.

[0044] In this embodiment, as shown in FIG. 1, the outlet of the compressor 6 is point A, the outlet of the water-cooled gas cooler 8 is point B, the outlet of the second path 16 in the internal heat exchanger 10 is point C, the outlet of the variable expansion valve 32 is point D, the outlet of the evaporator 12 is point E, and the outlet of the third path 18 in the internal heat exchanger 10 is point F.

[0045] From now on, the temperature, pressure, and enthalpy at each of points A to F will be explained using the following symbols. The temperature at point A is TA, the pressure is PA, and the enthalpy is EA. At point B, the temperature is TB, the pressure is PB, and the enthalpy is EB. The temperature at point C is TC, the pressure is PC, and the enthalpy is EC. At point D, TD is the temperature, PD is the pressure, and ED is the enthalpy. At point E, the temperature is TE, the pressure is PE, and the enthalpy is EE. The temperature at point F is TF, the pressure is PF, and the enthalpy is EF. This is explained as follows.

[0046] (CO 2 Refrigerant flow: Point F → Point A) When the above-described control is started, first, the CO 2 The refrigerant is compressed by the compressor 6 and reaches point A. At this time, CO 2 The temperature of the refrigerant changes (increases) from TF to TA, and CO 2 The pressure of the refrigerant changes (increases) from PF to PA, and CO 2 The enthalpy of the refrigerant changes (increases) from EF to EA, provided that the pressure PA is below the critical pressure.

[0047] (Point A → Point B) Next, the CO sent from point A to the water-cooled gas cooler 8 2 The refrigerant is cooled by the water-cooled gas cooler 8 and reaches point B. At this time, CO 2 The temperature of the refrigerant changes (decreases) from TA to TB, and CO 2 The pressure of the refrigerant does not change (PA=PB), and CO 2 The enthalpy of the refrigerant changes (decreases) from EA to EB. The temperature difference between TA and TB and the enthalpy difference between EA and EB are 2 The heat of the refrigerant is absorbed by the industrial water and is discharged to the outside by the water-cooled gas cooler 8. As shown in FIG. 2, point B is located inside the saturated liquid line and the saturated vapor line. 2 The refrigerant is in a gas / liquid mixture state.

[0048] (Point B → Point C) Next, the CO sent from point B to the internal heat exchanger 10 2 The refrigerant is CO sent from the evaporator 12. 2 The refrigerant removes heat and reaches point C. At this time, CO 2 The temperature of the refrigerant changes (decreases) from TB to TC, and CO 2 The pressure of the refrigerant does not change (PB=PC), and CO 2 The enthalpy of the refrigerant changes (decreases) from EB to EC. As shown in Figure 2, when going from point B to point C, the refrigerant exceeds the saturated liquid line, so at point C, the CO 2 The entire amount of refrigerant is liquefied.

[0049] (Point C → Point D) Next, the CO 2 The refrigerant is decompressed by the variable expansion valve 32 and reaches point D. 2 The temperature of the refrigerant changes (decreases) from TC to TD, and CO 2 The pressure of the refrigerant changes (decreases) from PC to PD, and CO 2 The enthalpy of the refrigerant does not change (EC = ED). Also, since the refrigerant is inside the saturated liquid line when going from point C to point D, the CO 2 The refrigerant is in a mixed state of gas and liquid.

[0050] (Point D → Point E) Next, the CO sent to the evaporator 12 from point D 2 The refrigerant absorbs energy from the processing liquid by the evaporator 12 and reaches point E. At this time, the heat absorbed from the processing liquid is converted into liquid CO 2 Used to vaporize refrigerant, CO 2 The temperature of the refrigerant does not change (TD=TE). 2 The pressure of the refrigerant also does not change (PD=PE). However, CO 2 The enthalpy of the refrigerant changes (increases) from ED to EE.

[0051] (Point E → Point F) Next, the CO sent from point E to the internal heat exchanger 10 2 The refrigerant is CO sent from point B to the internal heat exchanger 10. 2 Heat is removed from the refrigerant. Therefore, at point E, CO 2 Even if liquid remains in the refrigerant, CO 2 The liquid in the refrigerant becomes a gas. That is, CO reaches point F, which is outside the saturated vapor line. 2 The refrigerant is all gas. Therefore, the CO 2 Since the refrigerant is only a gas, liquid compression does not occur, and the load on the compressor 6 can be reduced. 2 When the refrigerant travels from point E to point F, CO 2The temperature of the refrigerant changes (increases) from TE to TF, and CO 2 The pressure of the refrigerant does not change (PE=PF), and CO 2 The enthalpy of the refrigerant changes (increases) from EE to EF.

[0052] In this way, in the cooling mechanism 2, the CO 2 The control unit 4b controls the opening degree of the variable expansion valve 32 and the rotation speed of the compressor 6 according to a route R defined by a pressure value and a temperature (fourth temperature) set within a range in which the refrigerant does not exceed the critical point P. That is, in the cooling mechanism 2, the CO 2 The refrigerant is compressed, cooled, and evaporated repeatedly. 2 The pressure of the refrigerant and the CO flowing out of the compressor 6 2 The pressure difference with the pressure of the refrigerant is reduced. As a result, the load on the compressor 6 is reduced, so that the life of the compressor 6 can be extended and the power consumption of the compressor 6 can be reduced.

[0053] In addition, in the cooling mechanism 2, CO 2 The pressure of the refrigerant is controlled to be equal to or lower than the critical pressure, but the flow rate of the industrial water introduced into the water-cooled gas cooler 8 may be a practical value. 2 After the refrigerant is cooled by the water-cooled gas cooler 8, it is further cooled by the internal heat exchanger 10. Therefore, it is sufficient to achieve a required amount of condensation at the outlet (point C) of the internal heat exchanger 10, and the amount of CO 2 It is not necessary to achieve the required condensation amount of the refrigerant. Therefore, the flow rate of the industrial water introduced into the water-cooled gas cooler 8 may be a realistic value.

[0054] Here, the set temperature (fourth temperature) at the outlet (point C) of the internal heat exchanger 10 will be described. The fourth temperature is an important temperature for achieving a required condensation amount at point C. Regarding the fourth temperature, in the setting unit 4a of this embodiment, the fourth temperature is set based on the temperature of the industrial water detected by the third temperature sensor 40, and the CO 2 Set the condensation pressure of the refrigerant and calculate the CO 2 A value (fourth temperature) to be detected by the fourth temperature sensor 42 is set based on the condensation temperature of the refrigerant and the rotation speed of the compressor 6. In short, the setting unit 4a sets the fourth temperature (the set temperature at point C) according to the temperature of the industrial water.

[0055] For example, when the temperature of the industrial water is 20° C., the setting unit 4a of the control means 4 sets 2 The condensation pressure of the refrigerant is set to about 6.5 MPa. 2 The relational expression between the condensation pressure and the condensation temperature at 2 When the condensation pressure of the refrigerant is about 6.5 MPa, CO 2 The condensation temperature of the refrigerant is determined to be about 25° C. The setting unit 4a also determines the CO 2 The relationship between the pressure of the refrigerant and the rotation speed of the compressor 6 is stored, and the CO 2 It is derived that the frequency of the power supplied to the motor 6a of the compressor 6 should be 30 to 40 Hz in order to set the pressure of the refrigerant to about 6.5 MPa. 2 Based on the condensation temperature of the refrigerant (approximately 25°C in the above example) and the rotation speed of the compressor 6 (in the above example, the frequency of the power supplied to the motor 6a is 30 to 40 Hz), the value (fourth temperature) to be detected by the fourth temperature sensor 42 is set to 24 to 22°C.

[0056] The setting section 4a of the control means 4 includes 2The following relationships are registered in advance for the condensation pressure and condensation temperature of the refrigerant, the rotation speed of the compressor 6 (the frequency of the power supplied to the motor 6a), and the fourth temperature. Note that the relationships shown below are only a part of the relationships registered in the setting unit 4a. The setting unit 4a adjusts the CO 2 Even if the condensation pressure of the refrigerant is set to any value other than the three below, the CO 2 The condensation temperature of the refrigerant, the rotation speed of the compressor 6, and the fourth temperature can be set. Condensation pressure (MPa) Condensation temperature (℃) Compressor speed (Hz) Fourth temperature (℃) Approx. 6.5 Approx. 25 30~40 24~22 Approx. 5.8 Approx. 20 60~70 15~13 About 5.1 About 15 90~100 0~-2

[0057] Then, when the value (fourth temperature) to be detected by the fourth temperature sensor 42 is set, the control unit 4b of the control means 4 adjusts the opening of the water control valve 20 to adjust the flow rate of industrial water introduced into the water-cooled gas cooler 8 so that the detection value (temperature at point C) of the fourth temperature sensor 42 becomes the set value (fourth temperature).

[0058] When the opening degree of the water control valve 20 increases, the amount of industrial water flowing into the water-cooled gas cooler 8 increases, and the amount of CO 2 Since the cooling of the refrigerant is promoted, the detection value (temperature at point C) of the fourth temperature sensor 42 decreases. On the other hand, when the opening degree of the water control valve 20 becomes smaller, the amount of industrial water flowing into the water-cooled gas cooler 8 decreases, and the amount of CO 2 Since the cooling of the refrigerant is suppressed, the detection value of the fourth temperature sensor 42 (the temperature at point C) increases.

[0059] In this way, the control means 4 controls the amount of CO 2 The condensation pressure of the refrigerant is set, and the CO obtained from this condensation pressure 2The fourth temperature is set from the condensation temperature of the refrigerant and the rotation speed of the compressor 6, and the opening of the water control valve 20 is adjusted so that the temperature of point C becomes the fourth temperature. Therefore, in the cooling mechanism 2 of the present embodiment, even if the temperature of the industrial water fluctuates, the required condensation amount can be achieved at the outlet (point C) of the internal heat exchanger 10, so that operation below the critical pressure is possible even with a realistic flow rate of industrial water.

[0060] As described above, in the cooling mechanism 2, since it is possible to achieve the required condensation amount, the relationship between the rotation speed of the compressor 6 and the cooling amount of the evaporator 12 has high continuity and linearity. As a result, in the cooling mechanism 2, even if the first and second temperatures are set to low temperatures (for example, about 5 to 10° C.), high-precision temperature control is possible.

[0061] Next, an operation in the case where the cooling amount of the processing contributing liquid used in the processing device is increased or decreased (that is, the set temperature of the processing contributing liquid is changed) will be described.

[0062] (When reducing the amount of cooling of the processing liquid) First, a case where the cooling amount of the processing-contributing liquid used in the processing device is decreased (a case where the set temperature of the processing-contributing liquid is increased) will be described. In this case, the control unit 4b of the control means 4 reduces the opening degree of the variable expansion valve 32. As a result, the CO 2 Since the flow rate of the coolant is reduced, the amount of cooling of the processing liquid can be reduced, which results in an increase in the value of the first temperature sensor 36 or the second temperature sensor 38.

[0063] On the other hand, the CO 2 When the flow rate of the refrigerant is reduced, the value measured by the pressure sensor 34 increases. Therefore, the value of the pressure sensor 34 may exceed the set value (the above pressure value). Therefore, in order to reduce the value of the pressure sensor 34 to the set value, the control unit 4b appropriately reduces the rotation speed of the compressor 6 according to the increase in the set temperature of the processing-contributing liquid.

[0064] In this case, even if the rotation speed of the compressor 6 reaches the lower limit of the allowable rotation speed, the value of the pressure sensor 34 may not drop to the set value. In such a case, the control unit 4b further operates the variable bypass valve 28, which is normally closed, from closed to open to increase the opening degree, thereby reducing the amount of CO 2 The flow rate of the refrigerant is increased. This makes it possible to reduce the value of the pressure sensor 34 to the set value without reducing the rotation speed of the compressor 6 below the lower limit of the allowable rotation speed.

[0065] Therefore, in the cooling mechanism 2, even if the set temperature of the processing-contributing liquid is increased, the value measured by the pressure sensor 34 does not fluctuate significantly, that is, the discharge pressure of the compressor 6 is maintained below the critical pressure.

[0066] In this way, when the control unit 4b reduces the amount of cooling of the processing-contributing liquid, the control unit 4b reduces the opening degree of the variable expansion valve 32 to reduce the amount of CO 2 The flow rate of the refrigerant is reduced, and the opening degree of the variable bypass valve 28 of the bypass path 30 is increased to prevent the rotation speed of the compressor 6 from reaching the lower limit value, thereby reducing the amount of CO flowing into the evaporator 12. 2 The flow rate of the refrigerant is increased.

[0067] (When increasing the amount of cooling of the processing liquid) Conversely, when the cooling amount of the processing-contributing liquid used in the processing device is increased in the cooling mechanism 2 (when the set temperature of the processing-contributing liquid is lowered), the control unit 4b of the control means 4 increases the opening degree of the variable expansion valve 32. 2 Since the flow rate of the coolant increases, the amount of cooling of the processing liquid can be increased, which results in a decrease in the value of the first temperature sensor 36 or the second temperature sensor 38.

[0068] However, the CO 2When the flow rate of the refrigerant is increased, the value measured by the pressure sensor 34 decreases. Therefore, the value of the pressure sensor 34 may fall below the set value (the above pressure value). Therefore, the control unit 4b appropriately increases the rotation speed of the compressor 6 according to the reduction in the set temperature of the processing-contributing liquid. This allows the value of the pressure sensor 34 to increase to the set value.

[0069] Therefore, in the cooling mechanism 2, even if the set temperature of the processing-contributing liquid is lowered, the value measured by the pressure sensor 34 does not fluctuate significantly, that is, the discharge pressure of the compressor 6 is maintained below the critical pressure.

[0070] However, when the set temperature of the processing liquid is low, the CO 2 The amount of refrigerant vaporized is reduced, so liquid CO 2 There is a risk that the refrigerant may be sucked into the compressor 6. However, in the cooling mechanism 2 of the present embodiment, the CO 2 Refrigerant and CO from water-cooled gas cooler 8 2 The refrigerant exchanges heat with the evaporator 12 in the internal heat exchanger 10. In this heat exchange, the CO 2 The refrigerant is CO from the water-cooled gas cooler 8. 2 This removes heat from the refrigerant. 2 Even if liquid remains in the refrigerant, CO 2 The liquid in the refrigerant becomes a gas.

[0071] In this way, when the cooling amount of the processing-contributing liquid is increased, the control unit 4b increases the opening degree of the variable expansion valve 32 and increases the rotation speed of the compressor 6 to reduce the amount of CO 2 Increasing the flow rate of the refrigerant and the associated CO 2 Liquid CO remaining in the refrigerant 2 The refrigerant is vaporized in the internal heat exchanger 10, thereby reducing the load on the compressor 6.

[0072] As described above, in the cooling mechanism 2, CO2 The refrigerant is repeatedly compressed, cooled, and evaporated, so the CO 2 The pressure of the refrigerant and the CO flowing out of the compressor 6 2 The pressure difference with the refrigerant pressure is reduced. As a result, the load on the compressor 6 is reduced, so that the life of the compressor 6 can be extended and the power consumption of the compressor 6 can be reduced. In addition, since the required condensation amount can be achieved at the outlet (point C) of the internal heat exchanger 10, operation below the critical pressure is possible even with a realistic flow rate of industrial water. [Explanation of symbols]

[0073] 2: Cooling mechanism 4: Control means 4a: Setting section 4b: Control section 6: Compressor 8: Water-cooled gas cooler 10: Internal heat exchanger 12: Evaporator 14: First Route 16: Second Path 18: The third path 20: Water control valve 22: The Fourth Path 24: First connection 26: Second connection 28: Variable bypass valve 30: Bypass route 32: Variable expansion valve 34: Pressure sensor 36: First temperature sensor 38: Second temperature sensor 40: Third temperature sensor 42: Fourth temperature sensor

Claims

1. A cooling mechanism for cooling a processing liquid used in a processing device, A control means; CO ２ A compressor that compresses a refrigerant; The CO compressed by the compressor and carrying the heat of compression ２ a water-cooled gas cooler for cooling the refrigerant; Cooled CO ２ an internal heat exchanger into which a refrigerant is pumped; CO discharged from the internal heat exchanger ２ An evaporator that vaporizes a refrigerant to generate heat of vaporization and cools a processing liquid used in a processing device; a first passage connecting the compressor and the water-cooled gas cooler; a second passage connecting the water-cooled gas cooler and the evaporator; a third passage connecting the evaporator and the compressor; a fourth passage for introducing industrial water into the water-cooled gas cooler and having a water control valve; a bypass passage connected to the first passage by a first connecting portion connected to the first passage and a second connecting portion connected to the second passage, the bypass passage including a variable bypass valve; The internal heat exchanger is configured to convert the CO ２ The refrigerant is CO sent out from the water-cooled gas cooler. ２ a heat exchanger disposed across the second path and the third path so as to remove heat from the refrigerant; The second route includes cooled CO ２ a variable expansion valve for adjusting a flow rate of the refrigerant is disposed between the internal heat exchanger and the second connection; The CO compressed by the compressor is supplied to either the first path or the second path between the compressor and the variable expansion valve. ２ A pressure sensor is provided to measure the pressure of the refrigerant. A first temperature sensor for measuring a temperature of the processing liquid used in the processing device when the processing liquid flows out of the evaporator; A second temperature sensor that measures the temperature of the processing liquid flowing into the evaporator; a third temperature sensor for measuring the temperature of the industrial water flowing into the water-cooled gas cooler; CO discharged from the internal heat exchanger in the second path. ２ a fourth temperature sensor for measuring the temperature of the refrigerant; the control means includes a setting unit that sets a pressure value to be detected by the pressure sensor, a first temperature to be detected by the first temperature sensor or a second temperature to be detected by the second temperature sensor, and a fourth temperature to be detected by the fourth temperature sensor; The CO ２ A cooling mechanism that controls the opening of the variable expansion valve and the rotation speed of the compressor according to a path defined by the set pressure value and temperature within a range in which the refrigerant does not exceed a critical point specified by a critical temperature of 31.1°C and a critical pressure of 7.38 MPa.

2. When the amount of cooling of the processing liquid used in the processing device is to be reduced, the control means reduces the opening degree of the variable expansion valve to reduce the amount of CO flowing through the evaporator. ２ The flow rate of the refrigerant is reduced, and the opening degree of the variable bypass valve of the bypass path is increased to reduce the amount of CO flowing into the evaporator so that the compressor does not reach the lower limit. ２ 2. The cooling mechanism of claim 1, which increases the flow rate of the refrigerant.

3. When the amount of cooling of the processing liquid used in the processing device is increased, the control means increases the opening degree of the variable expansion valve and increases the rotation speed of the compressor to reduce the amount of CO flowing through the evaporator. ２ Increasing the flow rate of the refrigerant and the associated CO ２ Liquid CO remaining in the refrigerant ２ 2. The cooling mechanism according to claim 1, wherein the refrigerant is vaporized in the internal heat exchanger to reduce a load on the compressor.

4. The control means The CO detected by the pressure sensor based on the temperature of the industrial water detected by the third temperature sensor. ２ Set the condensation pressure of the refrigerant, CO obtained from the condensation pressure ２ a value to be detected by the fourth temperature sensor is set based on a condensation temperature of the refrigerant and a rotation speed of the compressor; adjusting an opening of the water control valve so that the detection value of the fourth temperature sensor becomes the set value, thereby adjusting a flow rate of industrial water introduced into the water-cooled gas cooler; 2. The cooling mechanism according to claim 1, wherein the condensation pressure is controlled by decreasing the opening of the variable expansion valve to increase the value detected by the pressure sensor, and by increasing the opening of the variable expansion valve to decrease the value detected by the pressure sensor.

Images