gas compressor

Abstract

Provided is a technology capable of reducing pressure loss due to cooling of a compressed gas.　A gas compressor 100 comprises: a bypass passage 11 for bypassing an aftercooler 10; a bypass valve 13 provided in the bypass passage 11; a cooler bypass valve 12 provided between a connection part 19b and the aftercooler 10; an ammeter 16 for detecting a current value of a motor 1; a temperature sensor 14 for detecting a temperature of a compressed gas recovered from waste heat by a high-pressure stage waste heat recovery heat exchanger 9; a temperature sensor 22 for detecting a temperature around the gas compressor 100; and a control device 17 for opening and closing the bypass valve 13 and the cooler bypass valve 12 on the basis of the current value detected by the ammeter 16, the temperature detected by the temperature sensor 14, and the temperature detected by the temperature sensor 22.

Description

Technical Field

[0001] The present invention relates to a gas compressor.

Background Art

[0002] In a gas compressor provided with a cooling heat exchanger for cooling the gas compressed by the compressor body, it is known to recover heat from the compressed gas by passing the compressed gas through a waste heat recovery heat exchanger disposed upstream of the cooling heat exchanger. The waste heat recovery heat exchanger recovers the compression heat from the compressed gas and warms the passing water by exchanging heat between the compressed gas and the passing water.

[0003] In a gas compressor of a load / unload machine provided with a waste heat recovery heat exchanger, when changing from load to unload, waste heat recovery becomes unnecessary. In Patent Document 1, a shut-off valve is provided in a pipe connected to the waste heat recovery heat exchanger, a bypass valve is provided in a path bypassing the waste heat recovery heat exchanger, and a water supply valve is provided in the water supply line of the waste heat recovery heat exchanger. When bringing the waste heat recovery heat exchanger into a water-passing state, the valves are operated in the order of opening the water supply valve, opening the shut-off valve, and closing the bypass valve. When bringing the waste heat recovery heat exchanger into a water-stop state, the valves are operated in the order of opening the bypass valve, closing the shut-off valve, and closing the water supply valve.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology described in Patent Document 1, it is possible to switch whether the compressed gas from the compressor is passed through a heat exchanger for waste heat recovery or through a bypass path. However, when the compressed gas passes through both the heat exchanger for waste heat recovery and the heat exchanger for cooling, the pressure loss of the compressed gas increases compared to when the heat exchanger for waste heat recovery is bypassed.

[0006] Gas compressors generally work by detecting the pressure of the compressed gas at the package outlet and controlling the power of the compressor itself to maintain a predetermined pressure. Therefore, if pressure loss occurs and the pressure of the compressed gas drops, it is necessary to increase the pressure to compensate for the loss, which increases the power of the compressor itself.

[0007] One potential negative consequence of increased power to the compressor is that, for example, if the maximum current value of components such as the motor is exceeded, the temperature of the components may rise, potentially leading to component failure. Furthermore, as the compressor's pressure increases and the temperature of the compressed gas rises, there is a concern that the compressor itself may also fail.

[0008] The present invention aims to provide a technology that can reduce pressure loss due to the cooling of compressed gas. [Means for solving the problem]

[0009] To solve the above problems, one representative gas compressor of the present invention comprises a motor, a compressor body driven by the motor, a heat exchanger for waste heat recovery that recovers waste heat from the compressed gas compressed by the compressor body, and a cooling heat exchanger that cools the compressed gas from which waste heat has been recovered by the heat exchanger. The gas compressor comprises a first pipe that sends the compressed gas from the heat exchanger for waste heat recovery to the cooling heat exchanger, a second pipe that sends the compressed gas from the cooling heat exchanger to the outside of the gas compressor, and the first pipe and the second pipe are connected at a first connection part and a second connection part, respectively, for cooling The system includes a bypass path that bypasses the heat exchanger, a bypass valve provided in the bypass path, a cooler bypass valve provided in the first piping between the first connection and the cooling heat exchanger, an ammeter for detecting the motor current, a temperature sensor for detecting the temperature of the compressed gas recovered by the waste heat recovery heat exchanger, an ambient temperature sensor for detecting the temperature around the gas compressor, and a control device that opens and closes the bypass valve and the cooler bypass valve based on the current detected by the ammeter, the temperature detected by the temperature sensor, and the temperature detected by the ambient temperature sensor. [Effects of the Invention]

[0010] According to the present invention, pressure loss due to the cooling of compressed gas can be reduced.

[0011] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing an example of the configuration of the gas compressor in Example 1. [Figure 2] This flowchart shows an example of a route switching process performed by a control device. [Figure 3] This is a schematic diagram showing an example of the configuration of the gas compressor in Example 2. [Modes for carrying out the invention]

[0013] The following examples will be described with reference to the drawings. In the following examples, a two-stage gas compressor will be used as an example, but the invention is not limited to this, and the gas compressor may be a single-stage gas compressor or a multi-stage gas compressor. [Examples]

[0014] One embodiment of the present invention will be described with reference to the drawings.

[0015] Figure 1 is a schematic diagram showing an example of the configuration of the gas compressor in Example 1.

[0016] The gas compressor 100 includes a motor 1, a power transmission mechanism 2 that transmits the power to rotate the motor 1, a low-pressure stage compressor body 3 and a high-pressure stage compressor body 4 that are driven by the motor 1 to compress air (gas), a low-pressure stage waste heat recovery heat exchanger 6 that recovers heat from the compressed gas compressed by the low-pressure stage compressor body 3, an intercooler 7 that cools the compressed gas, a low-pressure stage discharge pipe 5A that sends the compressed gas from the low-pressure stage compressor body 3 to the low-pressure stage waste heat recovery heat exchanger 6, a low-pressure stage discharge pipe 5B that sends the compressed gas from the low-pressure stage waste heat recovery heat exchanger 6 to the intercooler 7, and a low-pressure stage discharge pipe 5C that sends the compressed gas from the intercooler 7 to the high-pressure stage compressor body 4.

[0017] Furthermore, the gas compressor 100 includes a high-pressure stage waste heat recovery heat exchanger 9 that recovers heat from the compressed gas compressed by the high-pressure stage compressor body 4, an aftercooler 10 that cools the compressed gas, a high-pressure stage discharge pipe 8A that sends the compressed gas from the high-pressure stage compressor body 4 to the high-pressure stage waste heat recovery heat exchanger 9, a high-pressure stage discharge pipe 8B that sends the compressed gas from the high-pressure stage waste heat recovery heat exchanger 9 to the aftercooler 10, a high-pressure stage discharge pipe 8C that sends the compressed gas from the aftercooler 10 to the outside of the gas compressor 100, and a bypass path 11 that is connected to the high-pressure stage discharge pipe 8B and the high-pressure stage discharge pipe 8C by connection parts 19B and 19C respectively and bypasses the aftercooler 10.

[0018] Furthermore, the gas compressor 100 includes a cooler bypass valve 12 provided between the connection portion 19B and the aftercooler 10 in the high-pressure stage discharge pipe 8B, and a bypass valve 13 provided in the bypass path 11.

[0019] Furthermore, the gas compressor 100 includes a temperature sensor 14 for detecting the temperature of the compressed gas inside the high-pressure stage discharge pipe 8B, a pressure sensor 15 for detecting the pressure of the compressed gas inside the high-pressure stage discharge pipe 8C, an ammeter 16 for detecting the current value of the motor 1, a temperature sensor 22 for detecting the temperature around the gas compressor 100, and a control device 17 for controlling the gas compressor 100.

[0020] The low-pressure stage waste heat recovery heat exchanger 6 and the high-pressure stage waste heat recovery heat exchanger 9 are part of the waste heat recovery unit 20. The low-pressure stage waste heat recovery heat exchanger 6 is provided upstream of the intercooler 7, and the high-pressure stage waste heat recovery heat exchanger 9 is provided upstream of the aftercooler 10.

[0021] The waste heat recovery unit 20 includes a water supply path 21 through which water passes. By a water supply pump (not shown) provided upstream of the water supply path 21, the water in the water supply path 21 passes through the high-pressure stage waste heat recovery heat exchanger 9 and then through the low-pressure stage waste heat recovery heat exchanger 6, and flows to a water supply tank (not shown) provided downstream of the water supply path 21. By exchanging heat between the compressed gas passing through the low-pressure stage waste heat recovery heat exchanger 6 and the high-pressure stage waste heat recovery heat exchanger 9 and the water passing through the water supply path 21, the compression heat is recovered from the compressed gas to warm the water.

[0022] The cooler bypass valve 12 and the bypass valve 13 open and close under the control of the control device 17 to release or block the flow of the compressed gas.

[0023] The temperature sensor 14 is installed immediately after the high-pressure stage waste heat recovery heat exchanger 9. The difference between the temperature detected downstream of the high-pressure stage waste heat recovery heat exchanger 9 and the temperature around the gas compressor 100 detected by the temperature sensor 22 indicates the cooling capacity of the high-pressure stage waste heat recovery heat exchanger 9.

[0024] The pressure of the compressed gas inside the high-pressure stage discharge piping 8C, as detected by the pressure sensor 15, fluctuates depending on the usage of the compressed gas. If the gas compressor 100 is a load / unload machine, the control device 17 switches the load / unload mode according to the pressure detected by the pressure sensor 15. If the gas compressor 100 is an inverter machine, the control device 17 also switches the operating state according to the pressure detected by the pressure sensor 15.

[0025] The ammeter 16 is connected to the wiring of the motor 1 and detects the current flowing through the motor 1.

[0026] The low-pressure stage compressor body 3 comprises, for example, a pair of male and female screw rotors that mesh with each other, a plurality of bearings that rotatably support the screw rotors, and a casing that houses them, with a plurality of working chambers formed in the tooth grooves of the screw rotors. Each working chamber moves in the axial direction of the rotor as the rotor rotates, and sequentially performs an intake process to draw in air, a compression process to compress the air, and a discharge process to discharge the compressed gas. The high-pressure stage compressor body 4 has substantially the same configuration as the low-pressure stage compressor body 3.

[0027] The intercooler 7 and aftercooler 10 are arranged within a cooling fan 18 and a surrounding duct, and are air-cooled, using the cooling air generated by the cooling fan 18 to cool the compressed gas. A cooler for cooling other than the compressed gas, such as lubricating oil, may also be configured within the duct. Furthermore, the intercooler and aftercooler may be water-cooled, performing heat exchange between cooling water and the compressed gas.

[0028] Next, we will explain the gas flow in the gas compressor 100.

[0029] The compressed gas compressed by the low-pressure stage compressor body 3 passes through the low-pressure stage discharge pipe 5A, where heat is recovered by the low-pressure stage waste heat recovery heat exchanger 6. After that, it passes through the low-pressure stage discharge pipe 5B and is further cooled by the intercooler 7. The cooled compressed gas is further compressed by the high-pressure stage compressor body 4, passes through the high-pressure stage discharge pipe 8A, and heat is recovered by the high-pressure stage waste heat recovery heat exchanger 9.

[0030] If further cooling by the aftercooler 10 is required, the control device 17 outputs a signal to open the cooler bypass valve 12 and close the bypass valve 13. As a result, the compressed gas passes through the high-pressure stage discharge pipe 8B, is further cooled by the aftercooler 10, and is supplied to the outside of the gas compressor 100 via the high-pressure stage discharge pipe 8C.

[0031] When the aftercooler 10 is to be bypassed, the control device 17 outputs a signal to close the cooler bypass valve 12 and open the bypass valve 13. As a result, the compressed gas passes through the bypass path 11 connected to the high-pressure stage discharge pipe 8B, bypasses the aftercooler 10, and is supplied to the outside of the gas compressor 100 via the high-pressure stage discharge pipe 8C.

[0032] Figure 2 is a flowchart showing an example of the route switching process performed by the control device 17.

[0033] In step S101, it is determined whether the current value of the motor 1 detected by the ammeter 16 is equal to or greater than a predetermined threshold. This determines whether the gas compressor 100 is operating at its rated current. This threshold is preset based on the rated current of the gas compressor 100.

[0034] In this case, if the gas compressor 100 is operating at a current value exceeding its rated current, it is possible that the power of the gas compressor 100 is increasing due to the large pressure loss caused by the cooling of the compressed gas, as controlled by the control device 17.

[0035] In step S101, if the current value of motor 1 detected by the ammeter 16 is above a predetermined threshold, the gas compressor 100 is operating at a current value exceeding the rated current, so the process proceeds to step S102. On the other hand, in step S101, if the current value of motor 1 detected by the ammeter 16 is below the predetermined threshold, the gas compressor 100 is operating at the rated current, so the process returns to step S101.

[0036] In step S102, it is determined whether the difference between the temperature of the compressed gas inside the high-pressure stage discharge pipe 8B, detected by the temperature sensor 14, and the ambient temperature around the gas compressor 100, detected by the temperature sensor 22, is below a predetermined threshold. This determines whether the compressed gas is sufficiently cooled by the high-pressure stage waste heat recovery heat exchanger 9. This threshold is preset according to the intended use of the compressed gas supplied from the gas compressor 100.

[0037] In step S102, if the difference between the temperature of the compressed gas inside the high-pressure stage discharge pipe 8B detected by the temperature sensor 14 and the ambient temperature around the gas compressor 100 detected by the temperature sensor 22 is below a predetermined threshold, the compressed gas has been sufficiently cooled by the high-pressure stage waste heat recovery heat exchanger 9, and the process proceeds to step S103. On the other hand, in step S102, if the difference between the temperature of the compressed gas inside the high-pressure stage discharge pipe 8B detected by the temperature sensor 14 and the ambient temperature around the gas compressor 100 detected by the temperature sensor 22 exceeds a predetermined threshold, the compressed gas has not been sufficiently cooled by the high-pressure stage waste heat recovery heat exchanger 9, and the process returns to step S102.

[0038] In step S103, the gas compressor 100 is operating at a current value exceeding its rated current, and the compressed gas is sufficiently cooled by the heat exchanger 9 for high-pressure stage waste heat recovery. Therefore, in order to reduce pressure loss due to the cooling of the compressed gas, the control device 17 outputs a signal to open the bypass valve 13 and close the cooler bypass valve 12, switching the path of the compressed gas to the bypass path 11 which does not pass through the aftercooler 10, and ending the process.

[0039] As described above, according to Embodiment 1, if the current value of the motor 1 detected by the ammeter 16 is above a predetermined threshold, and the difference between the temperature of the compressed gas inside the high-pressure stage discharge pipe 8B detected by the temperature sensor 14 and the ambient temperature around the gas compressor 100 detected by the temperature sensor 22 is below a predetermined threshold, the control device 17 outputs a signal to open the bypass valve 13 and close the cooler bypass valve 12, switching the path of the compressed gas to the bypass path 11 that does not pass through the aftercooler 10, thereby reducing pressure loss due to the cooling of the compressed gas. [Examples]

[0040] In Example 1, the cooler bypass valve 12 is located upstream of the aftercooler 10, but in Example 2, an example will be described in which the cooler bypass valve 12 is located downstream of the aftercooler 10.

[0041] Figure 3 is a schematic diagram showing an example of the configuration of the gas compressor in Example 2. In Figure 3, components identical to those in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted.

[0042] In Figure 3, the cooler bypass valve 12 is located in the high-pressure stage discharge piping 8C, between the aftercooler 10 and the connection section 19C. This ensures that even when the cooler bypass valve 12 is closed, the compressed gas is cooled by the aftercooler 10.

[0043] In the gas compressor 100 shown in Figure 3, the same path switching process as in Figure 2 is performed.

[0044] According to Example 2, similar to Example 1, if the current value of the motor 1 detected by the ammeter 16 is above a predetermined threshold, and the difference between the temperature of the compressed gas inside the high-pressure stage discharge pipe 8B detected by the temperature sensor 14 and the ambient temperature around the gas compressor 100 detected by the temperature sensor 22 is below a predetermined threshold, the control device 17 outputs a signal to open the bypass valve 13 and close the cooler bypass valve 12, switching the path of the compressed gas to the bypass path 11 that does not pass through the aftercooler 10, thereby reducing pressure loss due to the cooling of the compressed gas.

[0045] Furthermore, according to Example 2, even when the cooler bypass valve 12 is closed, the compressed gas is cooled by the aftercooler 10, so there is no need to increase the heat resistance temperature of the cooler bypass valve 12.

[0046] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0047] 1 motor 4. High-pressure stage compressor unit 9. Heat exchanger for high-pressure stage waste heat recovery 11 Bypass Route 12 Cooler bypass valve 13 Bypass valve 14. Temperature sensor 16 Ammeter 17 Control device 22 Temperature Sensor

Claims

1. Motor and, The compressor body is driven by the aforementioned motor, A heat exchanger for waste heat recovery recovers waste heat from the compressed gas compressed by the compressor body, A gas compressor comprising a cooling heat exchanger for cooling the compressed gas from which waste heat has been recovered in the aforementioned waste heat recovery heat exchanger, A piping system for sending the compressed gas, from which waste heat has been recovered in the aforementioned waste heat recovery heat exchanger, to the outside of the gas compressor via the aforementioned cooling heat exchanger, Bypass piping connecting the upstream and downstream of the cooling heat exchanger, A cooler bypass valve is provided between the connection between the aforementioned piping and the bypass piping and the cooling heat exchanger. A bypass valve is provided in the bypass piping, A temperature sensor for detecting the temperature of compressed gas recovered as waste heat by the aforementioned heat exchanger for waste heat recovery, An ambient temperature sensor for detecting the temperature around the gas compressor, A gas compressor comprising a control device that controls the bypass valve and the cooler bypass valve based on the temperature detected by the temperature sensor and the ambient temperature sensor.

2. In claim 1, The system further includes an ammeter for detecting the current value of the motor, The control device is A gas compressor that, when the current value detected by the ammeter is greater than or equal to a preset threshold, and the difference between the temperature detected by the temperature sensor and the ambient temperature sensor is less than or equal to a preset threshold, controls the bypass valve to open and the cooler bypass valve to close.

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