Compressor
The compressor design with a bypass line and control unit addresses instability in exhaust heat recovery systems by managing fluid flow rates, ensuring stable operation and consistent heat recovery during state transitions.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- KOBELCO COMPRESSORS CORP
- Filing Date
- 2025-10-28
- Publication Date
- 2026-07-23
AI Technical Summary
Existing exhaust heat recovery systems face instability due to delayed temperature control valve operation, leading to rapid fluid temperature rises and potential compressor shutdowns.
A compressor design with a bypass line and control unit that adjusts the flow rate of the working fluid through a temperature control valve, ensuring stable operation by gradually changing flow rates during state transitions.
The design stabilizes compressor operation by preventing rapid temperature rises and ensuring consistent heat recovery, even during state changes, by using a bypass line and control unit to manage fluid flow.
Smart Images
Figure JP2025037714_23072026_PF_FP_ABST
Abstract
Description
Compressor
[0001] The present disclosure relates to a compressor.
[0002] Patent Document 1 discloses an exhaust heat recovery system that recovers exhaust heat from a compressed gas. The above exhaust heat recovery system includes a gas compressor that compresses a gas, a heat exchanger for exhaust heat recovery, an exhaust heat recovery liquid pipe through which a fluid (exhaust heat recovery water in Patent Document 1) that exchanges heat with the gas in the heat exchanger flows, a temperature sensor disposed downstream of the heat exchanger in the exhaust heat recovery liquid pipe, and a temperature control valve that adjusts the temperature of the fluid. When the temperature of the fluid measured by the temperature sensor exceeds a set temperature (recovery water temperature in Patent Document 1), the temperature control valve is closed to adjust the temperature of the fluid.
[0003] Japanese Unexamined Patent Application Publication No. 2021 - 96043
[0004] In a system for recovering exhaust heat as disclosed in Patent Document 1, if the opening and closing of the temperature control valve are delayed with respect to the temperature rise of the fluid, the temperature of the fluid rises suddenly. In particular, when the flow rate of the fluid for recovering exhaust heat is restricted, the temperature of the fluid may rise rapidly. In this case, for example, if the compressor is configured to stop when the temperature of the fluid exceeds a threshold value, the compressor may not be able to operate stably.
[0005] The present disclosure has been made in view of the above problems, and provides a compressor that can operate stably.
[0006] One aspect of the present disclosure includes an oil-free compressor body for compressing gas, a heat recovery unit for recovering waste heat from the compressor body using a working fluid, a working fluid line to which the heat recovery unit is connected and through which the working fluid flows, a temperature control valve connected to the working fluid line for adjusting the temperature of the working fluid, a bypass line that branches off from the working fluid line at a branching point upstream of the temperature control valve and downstream of the heat recovery unit in the direction of flow of the working fluid, and rejoins the working fluid line at a confluence point downstream of the temperature control valve, and a device connected to the bypass line for controlling the flow rate of the working fluid flowing through the bypass line. The present invention provides a compressor comprising a control valve and a control unit that controls the operation of the control valve, wherein when the operating state of the compressor body switches from a first state to a second state in which the amount of heat generated from the compressor body is less than that of the first state, the control unit controls the control valve to increase the flow rate of the working fluid flowing through the bypass line, thereby reducing the flow rate of the working fluid passing to the temperature control valve, and when the operating state of the compressor body switches from the second state to the first state, the control valve controls the control valve to gradually decrease the flow rate of the working fluid flowing through the bypass line, thereby gradually increasing the flow rate of the working fluid passing to the temperature control valve.
[0007] A temperature control valve attempts to reduce the flow rate of the working fluid when its temperature drops. However, with the above configuration, when the operating state of the compressor body switches from the first state to the second state, the working fluid bypasses the temperature control valve, and the flow rate of the working fluid flowing through the bypass line increases. As a result, the flow rate of the working fluid flowing through the working fluid line, that is, the flow rate of the working fluid from which heat is recovered from the compressor body, does not decrease. Furthermore, when the operating state of the compressor body switches from the second state to the first state, the flow rate of the working fluid flowing through the bypass line does not decrease abruptly but gradually. Therefore, immediately after switching from the second state to the first state, a sufficient flow rate of the working fluid from which heat is recovered is ensured, thus avoiding a rapid rise in the temperature of the working fluid and allowing the compressor to operate stably.
[0008] The first state may be a startup state or a load operation state, and the second state may be a stopped state or an unloaded operation state.
[0009] According to the above configuration, immediately after switching from a stopped or no-load operation state to a started or loaded operation state, a sufficient flow rate of the working fluid from which waste heat is recovered is ensured. This prevents a rapid rise in the temperature of the working fluid and allows the compressor to operate stably.
[0010] The temperature control valve may be a self-operating control valve that adjusts its opening degree according to the temperature of the working fluid.
[0011] As described above, the temperature control valve is a self-operating control valve, and even if the temperature control valve opens after a delay in the temperature rise of the working fluid, a rapid rise in the temperature of the working fluid can be avoided. Here, "self-operating" refers to a system in which the opening degree is automatically adjusted according to the temperature of the working fluid, without electronic control. For example, a self-operating temperature control valve is a tube in which a fluid that has the property of expanding or contracting according to the temperature of the working fluid is arranged in a ring shape, and the working fluid flows through the inside of it.
[0012] The cross-sectional area of the flow path of the piping constituting the bypass line may be greater than or equal to the cross-sectional area of the flow path of the piping constituting the working fluid line between the branching point and the confluence point.
[0013] With the above configuration, the pressure loss of the working fluid flowing through the bypass line (hereinafter referred to as "pressure loss") can be reduced, and a decrease in the flow rate of the working fluid that recovers waste heat from the compressor body can be avoided. Therefore, even when the operating state of the compressor body switches from the second state to the first state, a rapid rise in the temperature of the working fluid can be avoided.
[0014] The compressor body comprises a first-stage compressor body and a second-stage compressor body that further compresses the gas discharged from the first-stage compressor body, and the heat recovery unit comprises an intercooler that cools the gas discharged from the first-stage compressor body and an aftercooler that cools the gas discharged from the second-stage compressor body, and the intercooler and the aftercooler may be arranged in series in the working fluid line.
[0015] With the above configuration, exhaust heat can be recovered by both the intercooler and the aftercooler, thus improving the efficiency of exhaust heat recovery.
[0016] The heat recovery unit further includes an oil cooler for cooling the oil supplied to the first-stage compressor body and the second-stage compressor body, and the oil cooler, the intercooler, and the aftercooler may be arranged in series in the working fluid line.
[0017] With the above configuration, waste heat can be recovered by the oil cooler, intercooler, and aftercooler, thus improving the efficiency of waste heat recovery.
[0018] The heat recovery unit further comprises a first cooling jacket for cooling the first-stage compressor body and a second cooling jacket for cooling the second-stage compressor body, and the oil cooler, the first cooling jacket, the second cooling jacket, the intercooler, and the aftercooler may be arranged in series in the working fluid line.
[0019] With the above configuration, exhaust heat can be recovered by the oil cooler, the first cooling jacket, the second cooling jacket, the intercooler, and the aftercooler, thus improving the efficiency of exhaust heat recovery.
[0020] The control unit may further include a first temperature sensor located upstream of the branching point to acquire a first temperature of the working fluid after heat recovery, and a second temperature sensor located downstream of the confluence point to acquire a second temperature of the working fluid before heat utilization. If the control unit determines that the first temperature is higher than the second temperature and that the difference between the first and second temperatures is greater than or equal to a preset threshold temperature, it may control the control valve to increase the flow rate of the working fluid flowing through the bypass line.
[0021] According to the above configuration, a malfunction of the temperature control valve or control valve can be detected.
[0022] The control unit may stop the compressor body if it determines that the first temperature is equal to or above a preset stop temperature relative to the temperature of the working fluid.
[0023] According to the above configuration, it is possible to avoid excessive temperature rise of the working fluid.
[0024] The system further comprises a housing that accommodates the compressor body and the heat recovery unit, and the temperature control valve, the bypass line, and the control valve may be located inside the housing.
[0025] With the above configuration, since the temperature control valve, bypass line, and control valve are located inside the housing, the temperature drop of the working fluid can be suppressed, and the decrease in the efficiency of heat recovery can be suppressed.
[0026] The system further comprises a housing that accommodates the compressor body and the heat recovery unit, and the temperature control valve, the bypass line, and the control valve may be located outside the housing.
[0027] With the above configuration, the temperature control valve, bypass line, and control valve are located outside the housing, allowing for a more compact compressor housing and increasing the flexibility of the layout design around the housing.
[0028] According to this disclosure, it is possible to provide a compressor that can operate stably.
[0029] A schematic diagram of the compressor according to the embodiment. A schematic diagram showing the water flow when the operating state of the compressor shown in Figure 1 is switched. A schematic diagram showing the water flow when the operating state of the compressor shown in Figure 1 is switched. A schematic diagram of the compressor according to a modified embodiment.
[0030] Embodiments will be described below with reference to the drawings. The same or corresponding elements are denoted by the same reference numerals throughout the drawings, and redundant detailed descriptions will be omitted.
[0031] (Embodiment) The compressor 100 shown in Figure 1 compresses gas G such as air or refrigerant, supplies the compressed gas G (hereinafter referred to as compressed gas G) to the customer, and provides heated water W (hot water) to the customer using the heat generated during compression.
[0032] The compressor 100 comprises a housing 1, a compressor body 2 (an example of a compressor body), a heat recovery unit 3, a temperature control valve 4, a bypass unit 5, a temperature acquisition unit 6, a control unit 10, a first fluid line L1, and a second fluid line L2 (an example of a working fluid line). Gas G flows through the first fluid line L1. A pump (not shown) is connected to the second fluid line L2, and when the pump operates, water W (an example of a working fluid) flows through it. The water W may be industrial water, groundwater such as well water, tap water, reclaimed water, or saline water containing salt, and the working fluid may be a heat transfer medium (liquid or gas) other than water.
[0033] The housing 1 contains the compressor body 2, the exhaust heat recovery unit 3, the control unit 10, the first fluid line L1, and a portion of the second fluid line L2. In this embodiment, the temperature control valve 4 and the bypass unit 5 are also located inside the housing 1.
[0034] (Compressor Body) The compressor body 2 is a two-stage compressor, comprising a first-stage compressor body 21 on the low-pressure side and a second-stage compressor body 22 on the high-pressure side. The first-stage compressor body 21 and the second-stage compressor body 22 are oil-free screw compressors, and the first-stage compressor body 21 and the second-stage compressor body 22 are operated by the rotation of a motor (not shown) controlled by an inverter (not shown). In this embodiment, the first-stage compressor body 21 and the second-stage compressor body 22 are configured to stop when the temperature of the water W after heat recovery reaches a stop temperature (for example, 96°C) or higher, in order to prevent the temperature of the water W supplied to the customer from rising excessively, as will be described later.
[0035] The first-stage compressor body 21 compresses and discharges gas G that has been drawn in from outside the housing 1 through the suction port. The second-stage compressor body 22 further compresses the gas G discharged from the first-stage compressor body 21 and supplies it to the outside of the housing 1 (the customer) through the discharge port.
[0036] The first-stage compressor body 21 and the second-stage compressor body 22 are configured to be switchable between a first state and a second state in terms of operating conditions. The second state is a state in which the amount of heat generated from the compressor body 2 is less than that of the first state. For example, the first state is the starting state and the second state is the stopped state. Alternatively, the first state is the load operation state and the second state is the no-load operation state.
[0037] (Heat Recovery Unit) The heat recovery unit 3 uses water W to recover heat from the compressor body 2 as waste heat. The heat recovery unit 3 includes an oil cooler 31, an intercooler 32, an aftercooler 33, a first cooling jacket 34, and a second cooling jacket 35.
[0038] The oil cooler 31, intercooler 32, aftercooler 33, first cooling jacket 34, and second cooling jacket 35 are connected to the second fluid line L2 through which water W flows. The oil cooler 31, first cooling jacket 34, second cooling jacket 35, intercooler 32, and aftercooler 33 are arranged in this order from upstream to downstream in the direction of water W flowing through the second fluid line L2. In other words, the oil cooler 31, first cooling jacket 34, second cooling jacket 35, intercooler 32, and aftercooler 33 are arranged in series in the second fluid line L2. The intercooler 32 and aftercooler 33 are connected to the first fluid line L1 through which gas G flows. The first stage compressor body 21, intercooler 32, second stage compressor body 22, and aftercooler 33 are arranged in this order from upstream to downstream in the direction of gas G flow.
[0039] The oil cooler 31 exchanges heat between the oil and water W supplied to the first-stage compressor body 21 and the second-stage compressor body 22. This cools the oil and heats the water W. The oil is supplied to the screw bearings of the compressor body 2 for cooling, lubrication, etc.
[0040] The intercooler 32 exchanges heat between the compressed gas G discharged from the first-stage compressor main body 21 and the water W flowing through the second fluid line L2. Similarly, the aftercooler 33 exchanges heat between the compressed gas G discharged from the second-stage compressor main body 22 and the water W flowing through the second fluid line L2. Thereby, the compressed gas G is cooled and the water W is heated.
[0041] The first cooling jacket 34 is disposed outside the first-stage compressor main body 21 and exchanges heat with the first-stage compressor main body 21. Thereby, the first-stage compressor main body 21 is cooled and the water W is heated. Similarly, the second cooling jacket 35 is disposed outside the second-stage compressor main body 22 and exchanges heat with the second-stage compressor main body 22. Thereby, the second-stage compressor main body 22 is cooled and the water W is heated.
[0042] (Temperature control valve) The temperature control valve 4 is connected to the second fluid line L2 to adjust the temperature of the water W flowing through the second fluid line L2. The temperature control valve 4 is a self-operated control valve that adjusts the opening degree by expanding or contracting according to the temperature of the water W. When the temperature of the water W drops, the temperature control valve 4 expands and reduces (constricts) the flow rate of the water W passing through the temperature control valve 4. On the other hand, when the temperature of the water W rises, the temperature control valve 4 contracts and increases the flow rate of the water W passing through the temperature control valve 4.
[0043] (Bypass section) The bypass section 5 is configured such that the water W bypasses the temperature control valve 4. The bypass section 5 has a bypass line L3 and an electric valve 51 (an example of a control valve).
[0044] The bypass line L3 branches from the second fluid line L2 at a branch point P1 upstream of the temperature control valve 4 and downstream of the aftercooler 33, and merges into the second fluid line L2 at a confluence point P2 downstream of the temperature control valve 4.
[0045] The flow path cross-sectional area of the pipe constituting the bypass line L3 is not less than the flow path cross-sectional area of the pipe constituting the second fluid line L2 between the branch point P1 and the confluence point P2.
[0046] The electric valve 51 is connected to the bypass line L3 and controls the flow rate of the water W flowing through the bypass line L3. In the present embodiment, the electric valve 51 is a flow rate control type configured to be able to adjust the opening degree according to the opening degree of the temperature control valve 4, but the electric valve 51 may be an on-off control type.
[0047] (Temperature acquisition unit) The temperature acquisition unit 6 acquires the temperature of the working fluid flowing through the second fluid line L2. The temperature acquisition unit 6 includes a first temperature sensor 61 and a second temperature sensor 62.
[0048] The first temperature sensor 61 is disposed upstream of the branch point P1 (between the branch point P1 and the aftercooler 33) and acquires the temperature of the water W after the exhaust heat recovery. The second temperature sensor 62 is disposed downstream of the confluence point P2 (outside the housing 1 in the present embodiment) and acquires the temperature of the water W before the exhaust heat utilization (before supply to the demand destination).
[0049] (Control unit) The control unit 10 controls the operations of each part of the compressor 100 (the compressor main body part 2 and the exhaust heat recovery part 3). The control unit 10 is composed of hardware such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and software installed on them.
[0050] When the operating state of the compressor main body part 2 changes, the control unit 10 executes a flow path switching process. The control unit 10 detects the switching of the operating state by receiving a signal indicating the operating state (for example, a load operation signal) from the compressor main body part 2.
[0051] In the flow path switching process, as shown in FIGS. 2A and 2B, when the operating state of the compressor main body part 2 switches from the first state to the second state, the control unit 10 controls the electric valve 51 so that the flow rate of the water W flowing through the bypass line L3 increases (in the present embodiment, the electric valve 51 is fully opened), and reduces the flow rate of the water W passing through the temperature control valve 4.
[0052] On the other hand, when the operating state of the compressor body 2 switches from the second state to the first state, the control unit 10 controls the electric valve 51 so that the flow rate of water W flowing through the bypass line L3 gradually decreases (in this embodiment, gradually closing from fully open), thereby gradually increasing the flow rate of water W passing through the temperature control valve 4. Specifically, the control unit 10 keeps the valve open for a first period (for example, 30 seconds), and after the first period has elapsed, slowly reduces the opening over a second period (for example, 20 seconds or more). Note that the times set as the first and second periods are not limited to those described above and are appropriately changed according to the rotational speed of the compressor body 2, the discharge pressure of the compressor body 2, the pipe diameter (flow path cross-sectional area) of the second fluid line L2, and the pipe diameter (flow path cross-sectional area) of the bypass line L3.
[0053] Furthermore, the control unit 10 determines whether the first condition is met, which is that the temperature of the water W obtained by the first temperature sensor 61 (hereinafter referred to as the "first temperature") is higher than the temperature of the water W obtained by the second temperature sensor 62 (hereinafter referred to as the "second temperature"), and the difference between the first temperature and the second temperature is greater than or equal to a preset threshold temperature. If the control unit 10 determines that the first condition is met, it increases the opening degree of the electric valve 51 so that the flow rate of the water W flowing through the bypass line L3 increases. If the control unit 10 determines that the first condition is not met, it does not change the opening degree of the electric valve 51.
[0054] Furthermore, in order to prevent the temperature of the water W supplied to the customer from rising excessively, the control unit 10 determines whether a second condition is met, namely that the first temperature (the temperature of the water W obtained by the first temperature sensor 61) is equal to or above a preset stop temperature (for example, 96°C). If the control unit 10 determines that the second condition is met, it stops the first-stage compressor body 21 and the second-stage compressor body 22. If the control unit 10 determines that the second condition is not met, it does not stop the first-stage compressor body 21 and the second-stage compressor body 22.
[0055] (Effects of the Embodiment) As described above, the temperature control valve 4 attempts to reduce the flow rate of water W when the temperature of water W decreases. However, according to this embodiment, when the operating state of the compressor body 2 switches from the first state to the second state, water W bypasses the temperature control valve 4, and the flow rate of water W flowing through the bypass line L3 increases. As a result, the flow rate of water W flowing through the second fluid line L2, that is, the flow rate of water W from which exhaust heat is recovered from the compressor body 2, does not decrease. Furthermore, when the operating state of the compressor body 2 switches from the second state to the first state, the flow rate of water W flowing through the bypass line L3 does not decrease rapidly but gradually. Therefore, immediately after switching from the second state to the first state, a sufficient amount of water W from which exhaust heat is recovered is secured, so a rapid rise in the temperature of water W can be avoided, and the compressor 100 can be operated stably.
[0056] As described above, in this embodiment, the first-stage compressor body 21 and the second-stage compressor body 22 are configured to stop when the temperature of the water W exceeds the stop temperature. In a configuration where the temperature control valve 4 closes (opens and closes) with a delay in the temperature rise (temperature change) of the water W, for example, if the set temperature of the water W is close to the stop temperature (96°C) (for example, 90°C), the temperature of the water W may rise rapidly (overshoot), exceed the stop temperature, and the compressor 100 may stop. For this reason, when the set temperature of the water W (supply temperature to the customer) is close to the stop temperature, it is necessary to avoid load fluctuations of the first-stage compressor body 21 and the second-stage compressor body 22 (load fluctuations from the second state to the first state in this embodiment) that increase the amount of heat discharged, in order to avoid stopping the first-stage compressor body 21 and the second-stage compressor body 22. However, according to the above embodiment, a rapid rise in the temperature of the water W can be avoided, so the compressor 100 can be operated stably.
[0057] (Modified embodiment) As shown in Figure 3, the temperature control valve 4 and the bypass section 5 may be located outside the housing 1. This makes the housing 1 more compact.
[0058] (Another Embodiment) In the above embodiment, the control unit 10 performed a flow path switching process when it received a signal indicating the operating state from the compressor body 2. However, the flow path switching process may also be performed by detecting the operating state of the first-stage compressor body 21 and the second-stage compressor body 22 based on the first temperature acquired by the first temperature sensor 61, or the discharge pressure of the gas G discharged from the first-stage compressor body 21 and the second-stage compressor body 22, and performing the flow path switching process based on the detected operating state.
[0059] Furthermore, the flow path switching process may be performed only when the set temperature of the water W (hot water) supplied to the customer is equal to or above a specified temperature (for example, 80°C). In this case, the control unit 10 determines whether the set temperature is equal to or above the specified temperature, and if it determines that the set temperature is equal to or above the specified temperature, it executes the flow path switching process. If the control unit 10 determines that the set temperature is below the specified temperature, it does not execute the flow path switching process. The specified temperature can be changed arbitrarily, and information indicating the set temperature and the specified temperature is stored in the memory area (ROM) included in the control unit 10.
[0060] In the above embodiment, the control of the electric valve 51 is illustrated by the control unit 10 which controls the operation of each part of the compressor 100 (compressor body 2 and heat recovery unit 3). However, the control of the electric valve 51 may also be performed by a separate control unit (controller) dedicated to the electric valve 51, distinct from the control unit 10.
[0061] In the above embodiment, the case in which the compressor body 2 is configured as a two-stage type was described, but the compressor body 2 is not limited to a two-stage type, and may be a one-stage type or a three-stage or more type.
[0062] Furthermore, although the electric valve 51 in the above embodiment was a two-way valve, it may be a valve with three or more directions that can be switched in more than two directions. Also, although an electric electric valve 51 was described as an example of a control valve, the control valve may be an electromagnetic solenoid valve instead of the electric valve 51.
[0063] In the above embodiment, the heat recovery unit 3 had a first cooling jacket 34 and a second cooling jacket 35, but the first cooling jacket 34 and the second cooling jacket 35 can be omitted.
[0064] This disclosure may include the following aspects:
[0065] (Aspect 1) An oil-free compressor body for compressing gas; a heat recovery unit for recovering waste heat from the compressor body using a working fluid; a working fluid line to which the heat recovery unit is connected and through which the working fluid flows; a temperature control valve connected to the working fluid line for adjusting the temperature of the working fluid; a bypass line that branches off from the working fluid line at a branching point upstream of the temperature control valve and downstream of the heat recovery unit in the flow direction of the working fluid, and rejoins the working fluid line at a confluence point downstream of the temperature control valve; a control valve connected to the bypass line for controlling the flow rate of the working fluid flowing through the bypass line; and a control unit for controlling the operation of the control valve, wherein when the operating state of the compressor body switches from a first state to a second state in which the amount of heat generated from the compressor body is less than in the first state, the control unit controls the control valve to increase the flow rate of the working fluid flowing through the bypass line, thereby reducing the flow rate of the working fluid passing to the temperature control valve. A compressor that, when the operating state of the compressor body switches from the second state to the first state, controls the control valve so that the flow rate of the working fluid flowing through the bypass line gradually decreases, thereby gradually increasing the flow rate of the working fluid passing through the temperature control valve. (Aspect 2) The compressor according to aspect 1, wherein the first state is a starting state or a load operation state, and the second state is a stopped state or an unload operation state. (Aspect 3) The compressor according to aspect 1 or 2, wherein the temperature control valve is a self-operating control valve that adjusts its opening degree according to the temperature of the working fluid. (Aspect 4) The compressor according to any one of aspects 1 to 3, wherein the flow path cross-sectional area of the piping constituting the bypass line is greater than or equal to the flow path cross-sectional area of the piping constituting the working fluid line between the branching point and the confluence point.(Aspect 5) The compressor according to any one of aspects 1 to 4, wherein the compressor body comprises a first-stage compressor body and a second-stage compressor body that further compresses the gas discharged from the first-stage compressor body, and the heat recovery unit comprises an intercooler that cools the gas discharged from the first-stage compressor body and an aftercooler that cools the gas discharged from the second-stage compressor body, and the intercooler and the aftercooler are arranged in series in the working fluid line. (Aspect 6) The compressor according to aspect 5, wherein the heat recovery unit further comprises an oil cooler that cools the oil supplied to the first-stage compressor body and the second-stage compressor body, and the oil cooler, the intercooler and the aftercooler are arranged in series in the working fluid line. (Aspect 7) The compressor according to aspect 6, wherein the heat recovery unit further comprises a first cooling jacket for cooling the first-stage compressor body and a second cooling jacket for cooling the second-stage compressor body, and the oil cooler, the first cooling jacket, the second cooling jacket, the intercooler, and the aftercooler are arranged in series in the working fluid line. (Aspect 8) The compressor according to any one of aspects 1 to 7, further comprising: a first temperature sensor arranged upstream of the branching point to acquire a first temperature of the working fluid after heat recovery; and a second temperature sensor arranged downstream of the confluence point to acquire a second temperature of the working fluid before heat utilization, wherein the control unit controls the control valve to increase the flow rate of the working fluid flowing through the bypass line when it determines that the first temperature is higher than the second temperature and the difference between the first temperature and the second temperature is greater than or equal to a preset threshold temperature. (Aspect 9) The compressor according to aspect 8, wherein the control unit determines that the first temperature is equal to or above a preset stop temperature relative to the temperature of the working fluid, and stops the compressor body. (Aspect 10) The compressor according to any one of aspects 1 to 9, further comprising a housing that accommodates the compressor body and the exhaust heat recovery unit, wherein the temperature control valve, the bypass line, and the control valve are arranged inside the housing.(Aspect 11) A compressor according to any one of aspects 1 to 9, further comprising a housing that accommodates the compressor body and the exhaust heat recovery unit, wherein the temperature control valve, the bypass line, and the control valve are arranged outside the housing.
[0066] This application is based on a Japanese patent application, Japanese Patent Application No. 2025-005403, filed on January 15, 2025. Japanese Patent Application No. 2025-005403 is incorporated herein by reference.
[0067] 1 Housing 2 Compressor body (compressor unit) 3 Heat recovery unit 4 Temperature control valve 5 Bypass unit 6 Temperature acquisition unit 10 Control unit 21 First stage compressor body 22 Second stage compressor body 31 Oil cooler 32 Intercooler 33 Aftercooler 34 First cooling jacket 35 Second cooling jacket 51 Electric valve (control valve) 61 First temperature sensor 62 Second temperature sensor 100 Compressor G Compressed gas (gas) L1 First fluid line L2 Second fluid line (working fluid line) L3 Bypass line P1 Branch point P2 Confluence point W Water (working fluid)
Claims
1. The compressor comprises: an oil-free compressor body for compressing gas; a heat recovery unit for recovering waste heat from the compressor body using a working fluid; a working fluid line to which the heat recovery unit is connected and through which the working fluid flows; a temperature control valve connected to the working fluid line for adjusting the temperature of the working fluid; a bypass line that branches off from the working fluid line at a branching point upstream of the temperature control valve and downstream of the heat recovery unit in the direction of flow of the working fluid, and rejoins the working fluid line at a confluence point downstream of the temperature control valve; a control valve connected to the bypass line for controlling the flow rate of the working fluid flowing through the bypass line; and a control unit for controlling the operation of the control valve, wherein when the operating state of the compressor body switches from a first state to a second state in which the amount of heat generated from the compressor body is less than that of the first state, the control unit controls the control valve to increase the flow rate of the working fluid flowing through the bypass line, thereby reducing the flow rate of the working fluid passing to the temperature control valve. A compressor that, when the operating state of the compressor body switches from the second state to the first state, controls the control valve so that the flow rate of the working fluid flowing through the bypass line gradually decreases, and gradually increases the flow rate of the working fluid passing through the temperature control valve.
2. The compressor according to claim 1, wherein the first state is a starting state or a load operation state, and the second state is a stopped state or an unloaded operation state.
3. The compressor according to claim 1 or 2, wherein the temperature control valve is a self-operating control valve that adjusts its opening degree according to the temperature of the working fluid.
4. The compressor according to claim 1 or 2, wherein the flow path cross-sectional area of the piping constituting the bypass line is equal to or greater than the flow path cross-sectional area of the piping constituting the working fluid line between the branching point and the confluence point.
5. The compressor according to claim 1 or 2, wherein the compressor body comprises a first-stage compressor body and a second-stage compressor body for further compressing the gas discharged from the first-stage compressor body, and the heat recovery unit comprises an intercooler for cooling the gas discharged from the first-stage compressor body and an aftercooler for cooling the gas discharged from the second-stage compressor body, and the intercooler and the aftercooler are arranged in series in the working fluid line.
6. The compressor according to claim 5, wherein the heat recovery unit further includes an oil cooler for cooling the oil supplied to the first-stage compressor body and the second-stage compressor body, and the oil cooler, the intercooler, and the aftercooler are arranged in series in the working fluid line.
7. The compressor according to claim 6, wherein the heat recovery unit further comprises a first cooling jacket for cooling the first-stage compressor body and a second cooling jacket for cooling the second-stage compressor body, and the oil cooler, the first cooling jacket, the second cooling jacket, the intercooler, and the aftercooler are arranged in series in the working fluid line.
8. The compressor according to claim 1 or 2, further comprising: a first temperature sensor located upstream of the branching point for acquiring a first temperature of the working fluid after heat recovery; and a second temperature sensor located downstream of the confluence point for acquiring a second temperature of the working fluid before heat utilization, wherein the control unit determines that the first temperature is higher than the second temperature and that the difference between the first temperature and the second temperature is greater than or equal to a preset threshold temperature, and controls the control valve to increase the flow rate of the working fluid flowing through the bypass line.
9. The compressor according to claim 8, wherein the control unit determines that the first temperature is equal to or greater than a preset stop temperature relative to the temperature of the working fluid, and stops the compressor body.
10. The compressor according to claim 1 or 2, further comprising a housing that accommodates the compressor body and the exhaust heat recovery unit, wherein the temperature control valve, the bypass line, and the control valve are arranged inside the housing.
11. The compressor according to claim 1 or 2, further comprising a housing that accommodates the compressor body and the exhaust heat recovery unit, wherein the temperature control valve, the bypass line, and the control valve are arranged outside the housing.