Compression system

Abstract

To provide a compression system that reduces the gas pressure in a gas pipe and lowers the temperature of the gas being pumped to other gas pipes without improving the cooling capacity of the cooling device. [Solution] The compression system according to this embodiment comprises a compressor, a cooling device, and a control unit. The intake side of the compressor is connected to a sealed pipe to be drawn in. The exhaust side of the compressor is connected to a pipe to be supplied. The compressor can draw gas from the pipe to be drawn in and reduce the pressure of the gas in the pipe to be drawn in to a predetermined pressure. The compressor can compress the drawn-in gas to a pressure higher than the pressure of the gas in the pipe to be supplied and supply it to the pipe to be supplied. The cooling device can cool the gas supplied from the compressor to the pipe to be supplied. The control unit operates the compressor at a constant reference rotational speed to supply gas from the compressor to the pipe to be supplied. If the temperature of the gas cooled by the cooling device exceeds a threshold below the allowable temperature of the pipe to be supplied, the control unit lowers the rotational speed of the compressor to a lower than the reference rotational speed.

Description

Technical Field

[0001] The present invention relates to a compression system.

Background Art

[0002] In the construction of gas pipes buried underground through which city gas or the like flows, the gas pipes are cut. In order to avoid the gas inside the gas pipes being released to the outside and mixing with air due to the cutting of the gas pipes, in the construction of gas pipes, before cutting the gas pipes, blocking members such as balloons for blocking the flow of gas from the gas pipes to the outside are arranged. When the gas pressure is high, the balloon cannot be arranged on the gas pipe, so when the gas pressure is high, the gas pressure is reduced. When a pressure regulator capable of reducing the gas pressure is not near the construction site, there is a method of reducing the pressure by discharging the gas to the atmosphere using a purge vehicle or the like. However, for example, since the global warming potential of methane, which is the main component of gas, is about 25 times higher than that of carbon dioxide, a compression system for reducing the gas pressure without discharging the gas to the outside has been proposed (see, for example, Patent Document 1). This compression system sucks and decompresses the gas in the gas pipe where the balloon is arranged, and pumps the sucked gas to another gas pipe connected to the gas demand destination. This compression system has a configuration including, for example, a truck and is movable to the construction site.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology described above, when gas is compressed by the compressor of the compression system, the temperature of the gas rises. Generally, due to the material of the gas pipes and the gas utility's transmission regulations, the temperature of the gas flowing through the gas pipes must be below the permissible temperature. The gas heated by the compressor is cooled by the cooling device of the compression system, but the cooling capacity of the cooling device in the technology described above is insufficient to sufficiently lower the temperature of the gas supplied to other gas pipes to below the permissible temperature. It is conceivable to lower the gas temperature by adopting a cooling device with a higher cooling capacity, but increasing the cooling capacity increases the size and weight of the cooling device, resulting in a larger truck to carry the cooling device. From the standpoint of mobility to construction sites and cost, it is desirable for the truck to be as small as possible. Therefore, there is a need for a technology that reduces the pressure of the gas in the gas pipes and lowers the temperature of the gas being pumped to other gas pipes without increasing the cooling capacity of the cooling device.

[0005] Therefore, the present invention aims to provide a compression system that reduces the gas pressure in a gas pipe and lowers the temperature of the gas being pumped to other gas pipes without improving the cooling capacity of the cooling device. [Means for solving the problem]

[0006] The compression system according to this embodiment comprises a compressor, a cooling device, and a control unit. The intake side of the compressor is connected to a sealed pipe to be drawn in. The exhaust side of the compressor is connected to a pipe to be supplied. The compressor can draw gas from the pipe to be drawn in and reduce the pressure of the gas in the pipe to a predetermined pressure. The compressor can compress the drawn-in gas to a pressure higher than the pressure of the gas in the pipe to be supplied and supply it to the pipe to be supplied. The cooling device can cool the gas supplied from the compressor to the pipe to be supplied. The control unit operates the compressor at a constant reference rotational speed to supply gas from the compressor to the pipe to be supplied. If the temperature of the gas cooled by the cooling device exceeds a threshold below the allowable temperature of the pipe to be supplied, the control unit lowers the rotational speed of the compressor to a lower than the reference rotational speed. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a compression system that reduces the pressure of the gas in a gas pipe and lowers the temperature of the gas being pumped to other gas pipes without improving the cooling capacity of the cooling device. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example of how the compression system according to this embodiment is used. [Figure 2] Figure 2 shows an example of the configuration of a compression system according to an embodiment. [Figure 3] Figure 3 is a flowchart showing an example of the operation of the compression system according to the embodiment. [Figure 4] Figure 4 shows an example of the relationship between the temperature of the exhaust gas on the compressor and the pressure of the intake gas on the compressor according to the embodiment. [Figure 5] Figure 5 shows an example of the time changes of the compressor rotation speed, the pressure and temperature of the gas on the intake side of the compressor, the temperature of the gas cooled by the cooling device, the amount of gas discharged by the compressor, and the amount of heat of the gas discharged by the compressor, according to the embodiment. [Figure 6] Figure 6 shows the time changes of the compressor rotation speed, the temperature of the gas cooled by the cooling device, and the amount of heat in the gas delivered by the compressor in the comparative example compression system. [Modes for carrying out the invention]

[0009] (Embodiment) The compression system 1 is used, for example, before cutting gas pipes in construction work such as adding or replacing gas pipes buried underground. In gas pipe construction, the compression system 1 reduces the pressure by sucking in the gas from the gas pipe to be cut, compresses the sucked-in gas, and transfers it to another gas pipe. Figure 1 shows an example of how the compression system 1 is used according to this embodiment.

[0010] In an example shown in Figure 1, the compression system 1 according to the embodiment includes, for example, a first medium-sized truck 2, a second medium-sized truck 3, a compression device 10, and a power supply device 70. As shown in Figure 1, the compression device 10 is mounted on the first medium-sized truck 2. The power supply device 70 is mounted on the second medium-sized truck 3. The intake side of the compressor of the compression device 10 is connected to the suction target pipe 121 of the piping system 100 via the main intake pipe 21 of the compression device 10. The exhaust side of the compressor of the compression device 10 is connected to the supply target pipe 122 of the piping system 100 via the main exhaust pipe 22 of the compression device 10. The compression device 10 is connected to the generator 73 of the power supply device 70 via the piping 72 of the power supply device 70. The generator 73 is connected to the control device of the compression device 10 via a cable 74.

[0011] Figure 2 shows an example of the configuration of the compression system 1. The compression device 10 comprises a housing 11, a gas transfer system 20, and a safety pressure adjustment system 60.

[0012] The enclosure 11 is positioned on the first medium-sized track 2. The enclosure 11 is designed to prevent operating noise generated inside from leaking to the outside.

[0013] The gas transfer system 20 transfers gas by drawing gas from the pipe to be drawn in 121 and supplying it to the pipe to be supplied 122. The gas transfer system 20 includes, for example, an intake main pipe 21, an exhaust main pipe 22, a bypass pipe 23, a control device 31, an inverter 32, a power meter 321, an electric motor 33, a belt 34, a compressor 35, a gas storage unit 36, a cooling device 40, a temperature sensor 50, a first solenoid valve 51, a second solenoid valve 52, and a third solenoid valve 53. The control device 31, inverter 32, power meter 321, electric motor 33, belt 34, compressor 35, gas storage unit 36, cooling device 40, temperature sensor 50, first solenoid valve 51, second solenoid valve 52, and third solenoid valve 53 are arranged, for example, inside the housing 11. In Figure 2, the temperature sensor is indicated as TI (Temperature indicator), the pressure sensor as PI (Pressure indicator), the power meter 321 as WI (Watt indicator), and the tachometer 331 as XI.

[0014] The intake main pipe 21 is connected to the intake side 35a of the compressor 35. The intake main pipe 21 can also be connected to a first connection part 131 attached to the pipe to be drawn in 121. In one embodiment, as shown in Figure 2, the intake main pipe 21 is equipped with an on / off valve 211, a temperature sensor 212, a pressure sensor 213, and a pressure sensor 214. The temperature sensor 212 measures the temperature of the gas drawn into the compressor 35. The measurement data from the temperature sensor 212 is used for verification. The pressure sensor 213 measures the pressure of the gas drawn into the compressor 35. The pressure sensor 214 measures the pressure of the gas drawn into the compressor 35 and transmits the measurement data to the control device 31.

[0015] The main exhaust pipe 22 is connected to the exhaust side 35b of the compressor 35. Also, the main exhaust pipe 22 can be connected to a second connection part 132 attached to the supply target pipe 122. For example, a sub-pipe 221 is connected to the main exhaust pipe 22. An on-off valve 222 and a safety valve 223 are arranged in the sub-pipe 221. The sub-pipe 221, the on-off valve 222, and the safety valve 223 suppress damage to the compressor 35, the main exhaust pipe 22, etc. caused by blockage or the like occurring in the main exhaust pipe 22 or the like. Also, an on-off valve 224 is arranged in the main exhaust pipe 22. Also, a pressure sensor 225 is arranged between the after-cooler 42 and the connection part 24. The pressure sensor 225 is used to compare the pressure of the gas flowing through the main intake pipe 21 and the pressure of the gas flowing through the main exhaust pipe 22.

[0016] The bypass pipe 23 is connected to the main intake pipe 21 and the main exhaust pipe 22. For example, the bypass pipe 23 is connected to a portion of the main intake pipe 21 between the first solenoid valve 51 and the compressor 35. Also, for example, the bypass pipe 23 is connected to a portion of the main exhaust pipe 22 between the after-cooler 42 of the cooling device 40 and the second solenoid valve 52.

[0017] The control device 31 includes, for example, a distribution board 31a, an uninterruptible power supply device 31b (UPS (Uninterruptible Power Supply)), and a control unit 31c. The distribution board 31a supplies the power supplied from the generator 73 to the uninterruptible power supply device 31b and the control unit 31c. The uninterruptible power supply device 31b can supply power to the control unit 31c etc. even during a power outage. The control unit 31c controls each component of the compression system 1 such as the inverter 32 and the cooling device 40 by power supply from the distribution board 31a or the uninterruptible power supply device 31b. [[ID=q]]

[0018] The inverter 32 supplies power to the motor 33 based on the control of the control unit 31c. The wattmeter 321 measures the power supplied from the inverter 32 to the motor 33.

[0019] The electric motor 33 is supplied with power from the inverter 32. The rotating shaft 33a of the electric motor 33 rotates at a rotational speed corresponding to the power. The rotational speed of the electric motor 33 can be continuously changed. The rotating shaft 33a is connected to the rotating shaft 35c of the compressor 35 via, for example, a belt 34. The rotational force generated by the electric motor 33 is transmitted to the rotating shaft 35c of the compressor 35 via the belt 34. For example, a tachometer 331 is attached to the electric motor 33 to measure the rotational speed of the rotating shaft 33a of the electric motor 33.

[0020] The compressor 35 operates when a rotational force is transmitted from the electric motor 33. Specifically, the compressor 35 includes, for example, a rotating shaft 35c, a main body 35d, and a rotor. The rotating shaft 35c rotates when a rotational force is transmitted from the electric motor 33 via the belt 34. The main body 35d includes a storage portion that houses the rotor inside, and a shaft penetration portion in which a cylindrical hole through which the rotating shaft 35c can penetrate is formed. The storage portion is formed adjacent to the shaft penetration portion. The storage portion and the shaft penetration portion communicate with each other. The rotating shaft 35c is connected to the rotor in a state of being inserted into the main body 35d. Specifically, the rotating shaft 35c is connected to the rotor housed in the storage portion of the main body 35d in a state of penetrating the shaft penetration portion and being inserted to the storage portion. The rotor rotates by the rotation of the rotating shaft 35c. The compressor 35 inhales gas and compresses the inhaled gas when the rotor rotates. The amount of gas delivered by the compressor 35 changes according to the rotational speed. In the following description, the upstream side in the gas flow direction is referred to as the primary side, and the downstream side is referred to as the secondary side. For example, a tachometer 351 that measures the rotational speed of the compressor 35 is attached to the compressor 35 to measure the rotational speed of the compressor 35.

[0021] The intake side 35a of the compressor 35 is connected to the suction target pipe 121 via the intake main pipe 21 and the first connection portion 131. The exhaust side 35b of the compressor 35 is connected to the supply target pipe 122 via the exhaust main pipe 22 and the second connection portion 132. Due to the operation of the compressor 35, in the intake main pipe 21, gas flows from the suction target pipe 121 to the compressor 35, and in the exhaust main pipe 22, gas flows from the compressor 35 to the supply target pipe 122.

[0022] Gas inside the compressor 35 may leak from the compressor 35. Specifically, for example, a gap 35e is formed between the inner circumferential surface of the shaft penetration portion of the compressor body 35d and the outer circumferential surface of the rotating shaft 35c. A seal is placed in the gap 35e to suppress the gas from the storage section from flowing out to the outside through the gap 35e. However, some of the gas inside the compressor 35 may leak out through the gap 35e. If gas leaks from inside the compressor 35, the gas flows to the gas storage unit 36 ​​or to the piping 72 of the power supply device 70. The gas storage unit 36 ​​stores the gas that has leaked from the compressor 35.

[0023] The cooling device 40 is capable of cooling the gas supplied from the compressor 35 to the supply pipe 122. The cooling device 40 is also capable of cooling the gas flowing through the exhaust main pipe 22. In the following description, the maximum amount of heat that the cooling device 40 can remove from the gas flowing through the exhaust main pipe 22 per unit time is described as the cooling capacity. In one example of the embodiment, the cooling capacity is 20 kW.

[0024] The cooling system 40 includes, for example, a refrigerator 41, an aftercooler 42, refrigerant pipes 43, 44, 45, and a gas detector. The refrigerator 41 is located outside the housing 11. The refrigerant pipe 43 is connected to the refrigerator 41 and the aftercooler 42. A temperature sensor 431, an on-off valve 432, and a pressure sensor 433 are located on the refrigerant pipe 43. The pressure of the refrigerant flowing through the refrigerant pipe 43 is confirmed based on the measurement result from the pressure sensor 433. The refrigerant pipe 44 is connected to the aftercooler 42 and the compressor 35. The refrigerant pipe 45 is connected to the compressor 35 and the refrigerator 41. A temperature sensor 451 and an on-off valve 452 are located on the refrigerant pipe 45. The output of the refrigerator 41 is adjusted based on the measurement results from the temperature sensors 431 and 451. The gas detector is located, for example, inside the refrigerator 41 and detects the gas inside the refrigerator 41. Outside the housing 11, for example, a temperature sensor 411 is positioned to measure the ambient temperature and transmit the measurement data to the control device 31.

[0025] The aftercooler 42 can cool the gas flowing through the exhaust main pipe 22 between the compressor 35 and the temperature sensor 50. The aftercooler 42 can cool the primary side gas at the connection point 24 between the exhaust main pipe 22 and the bypass pipe 23, for example. When the on-off valve 432 is open, the aftercooler 42 is supplied with refrigerant from the chiller 41 via the refrigerant pipe 43. The refrigerant is, for example, water. The aftercooler 42 cools the gas flowing through the exhaust main pipe 22 by heat exchange between the refrigerant supplied from the chiller 41 and the gas flowing through the exhaust main pipe 22. The refrigerant that has passed through the aftercooler 42 is supplied to the compressor 35 via, for example, the refrigerant pipe 44, to cool the compressor 35. When the on-off valve 452 is open, the refrigerant that has passed through the compressor 35 flows to the chiller 41.

[0026] The temperature sensor 50 measures the temperature of the gas flowing on the secondary side of the aftercooler 42 in the exhaust main pipe 22 and transmits the measurement data to the control device 31. Specifically, the temperature sensor 50 measures the temperature of the gas flowing on the secondary side of the second solenoid valve 52 in the exhaust main pipe 22. In one embodiment, a pressure sensor 501 is placed together with the temperature sensor 50 in the portion of the exhaust main pipe 22 on the secondary side of the aftercooler 42. The pressure sensor 501 is placed to confirm whether the pressure of the gas flowing to the supply pipe 122 is appropriate.

[0027] The first solenoid valve 51, the second solenoid valve 52, and the third solenoid valve 53 are valves whose open / closed state is switched by control of the control unit 31c. The first solenoid valve 51 is located, for example, in the primary side portion of the intake main pipe 21 relative to the connection 25 between the intake main pipe 21 and the bypass pipe 23. The second solenoid valve 52 is located, for example, in the secondary side portion of the exhaust main pipe 22 relative to the connection 24 between the exhaust main pipe 22 and the bypass pipe 23. In one embodiment, a check valve 521 is located in the portion of the exhaust main pipe 22 between the connection 24 and the second solenoid valve 52. The third solenoid valve 53 is located in the bypass pipe 23.

[0028] The safety pressure adjustment system 60 adjusts the pressure of the gas supplied from the exhaust main pipe 22 to the generator 73 during the depressurization process, which involves drawing gas from the suction target pipe 121 to reduce its pressure. After the depressurization process, the safety pressure adjustment system 60 adjusts the pressure of the gas in the suction target pipe 121 to the safety pressure. The safety pressure adjustment system 60 includes, for example, piping 61, piping 62, a safety pressure regulator 63, and piping 64. Piping 61 is connected to the intake main pipe 21 and piping 72. In one embodiment, on-off valves 611 and 612 are arranged in piping 61. Piping 62 is connected to the exhaust main pipe 22 and piping 61. The safety pressure regulator 63 adjusts the pressure of the gas flowing through piping 62. For example, on-off valve 621 is arranged in piping 62. Piping 64 is connected to piping 61 and piping 62. A valve section 641 is arranged in piping 64.

[0029] The power supply device 70 is capable of supplying power to the control unit 31c. The power supply device 70 includes piping 72, a generator 73, and a cable 74.

[0030] Piping 72 is connected to the compressor 35 and the generator 73. In piping 72, gas leaking from the compressor 35 flows to the generator 73. A branch pipe 721 is connected to piping 72. A safety valve 722 is installed in the branch pipe 721. The branch pipe 721 and safety valve 722 prevent damage to the compressor 35 and piping 72 caused by blockages in piping 72, etc. Also, for example, an on-off valve 723 is installed in piping 72. Also, for example, a branch pipe 724 is connected to piping 722. An on-off valve 725 and a safety valve 726 are installed in the branch pipe 724. The branch pipe 724, on-off valve 725, and safety valve 726 prevent damage to the compressor 35 and piping 72 caused by blockages in piping 72, etc. Also, an on-off valve 727, an electric valve 728, and an on-off valve 729 are installed in piping 72.

[0031] The generator 73 can supply the power it generates to the distribution panel 31a of the control device 31 via the cable 74. The generator 73 is connected to, for example, the piping 72. The generator 73 generates mechanical energy using, for example, gas supplied from the compressor 35 via the piping 72 or gas supplied from the exhaust main pipe 22 via the piping 72, and uses this mechanical energy to generate electricity.

[0032] The piping system 100 includes a valve 110, a valve 111, a pipe to be drawn in 121, a pipe to be supplied in 122, a first connection 131, and a second connection 132. The pipe to be drawn in 121 is the pipe from which the compression system 1 draws in gas. The pipe to be drawn in 121 includes a cut section 140 that is cut during gas pipe construction. The pipe to be drawn in 121 is connected, for example, to valves 110 and 111. The pipe to be drawn in 121 becomes sealed, for example, when the two valves 110 and 111 are closed, preventing gas from flowing out of the pipe to be drawn in 121. The pipe to be supplied in 122 is the pipe from which the compression system 1 supplies gas. The pipe to be supplied in 122 is connected, for example, to the pipe to be drawn in 121 via valve 110. The pipe to be supplied in 122 is connected, for example, to the destination of gas demand.

[0033] Gas pipes carry gases such as city gas. Gas pipes carry gases with a pressure of 0.3 MPa or higher. Gas pipes are made of polyethylene, for example. The temperature of the gas flowing through the gas pipes must be below the permissible temperature. The permissible temperature of the gas pipes, including the pipe to be drawn 121 and the pipe to be supplied 122, is determined based on, for example, the material of the gas pipes and the transmission regulations set by the gas utility company. For example, if the gas pipe is a polyethylene pipe, if the temperature of the gas flowing through the pipe exceeds 40°C, the heat resistance properties of polyethylene may cause the gas pipe to expand or the joints of the gas pipe to come loose. For this reason, in the case where the gas pipe is a polyethylene pipe, the permissible temperature of the gas pipe is set to, for example, 40°C. In gas pipes, the temperature of the gas is adjusted so that the gas flows at a temperature below the threshold set as the temperature below the permissible temperature, so that the temperature of the gas does not exceed the permissible temperature. The temperature of the gas in the pipe to be drawn 121 is adjusted to below the threshold. Therefore, the temperature of the gas on the intake side 35a of the compressor 35 is below the threshold.

[0034] Next, we will explain the operation of the compression system 1 during gas depressurization and the time changes of gas-related parameters. The compression system 1 is moved to the construction site. Then, one end of the intake main pipe 21 is connected to the first connection part 131, so the intake side 35a of the compressor 35 is connected to the pipe to be sucked 121. Before one end of the intake main pipe 21 is connected to the first connection part 131, the pipe to be sucked 121 is sealed, and the outflow of gas to the outside of the pipe to be sucked 121 is prevented. Also, one end of the exhaust main pipe 22 is connected to the second connection part 132, so the exhaust side 35b of the compressor 35 is connected to the pipe to be sucked 121.

[0035] Figure 3 is a flowchart illustrating an example of the operation of the compression system 1. The control unit 31c starts control when the pipe to be sucked 121 is sealed. In one embodiment, the control unit 31c controls the inverter 32 to increase the rotational speed of the compressor 35 until it reaches a reference rotational speed (S10). The reference rotational speed is, for example, the rated rotational speed of the compressor 35. The control unit 31c continuously increases the rotational speed of the electric motor 33.

[0036] From the start of operation of the compressor 35 until its rotational speed reaches the reference rotational speed, the control unit 31c controls, for example, the first solenoid valve 51 to be in the open state, the second solenoid valve 52 to be in the closed state, and the third solenoid valve 53 to be in the open state. The control unit 31c also controls, for example, the on-off valves 211 and 224 to be in the open state. As a result, when the compressor 35 operates, the gas in the suction target pipe 121 is drawn in by the compressor 35. Since the compression system 1 is connected to the suction target pipe 121 while the suction target pipe 121 is sealed, the gas in the suction target pipe 121 flows out only through the first connection part 131. As a result, the gas in the suction target pipe 121 is drawn in by the compression system 1, and the pressure of the gas in the suction target pipe 121 is reduced. The drawn-in gas flows from the suction target pipe 121 to the compressor 35 in the intake main pipe 21, as shown by arrow A1 in Figure 2. The gas flowing from the compressor 35 flows through the exhaust main pipe 22 and then, as shown by arrow A2 in Figure 2, flows into the bypass pipe 23. The gas flowing through the bypass pipe 23 then flows back to the compressor 35 via the intake main pipe 21. In this way, the gas circulates through the compressor 35, the exhaust main pipe 22, the bypass pipe 23, and the intake main pipe 21.

[0037] When the rotational speed of the compressor 35 rises to the reference rotational speed, the control unit 31c switches the second solenoid valve 52 from the closed state to the open state and switches the third solenoid valve 53 from the open state to the closed state (S20). The compressor 35 compresses the inhaled gas to a pressure higher than the pressure of the gas in the supply pipe 122 and supplies it to the supply pipe 122 via the second solenoid valve 52 and the second connection part 132, as shown by arrow A3 in Figure 2. The temperature sensor 50 starts monitoring the temperature of the gas cooled by the cooling device 40.

[0038] Next, the operation of the compression system 1 after the rotational speed of the compressor 35 has risen to the reference rotational speed, and the time changes of gas-related parameters will be explained with reference to Figures 3 to 5. In the following explanation, the amount of heat supplied to the gas supplied by the compressor 35 per unit time due to the operation of the compressor 35 will be explained as the supplied gas heat quantity. Figure 4 is a diagram showing an example of the difference between the gas temperature on the exhaust side 35b of the compressor 35 and the gas temperature on the intake side 35a of the compressor 35, with respect to the gas pressure on the intake side 35a of the compressor 35 according to this embodiment. Figure 5 is a diagram showing an example of the time changes of the rotational speed of the compressor 35, the gas pressure and temperature on the intake side 35a of the compressor 35, the temperature of the gas cooled by the cooling device 40, the amount of gas supplied by the compressor 35 to the exhaust main pipe 22, and the supplied gas heat quantity according to this embodiment. In Figure 5, the gas pressure on the intake side 35a of the compressor 35 is shown by line l1. In Figure 5, line l2 indicates the temperature of the gas on the intake side 35a of the compressor 35. Line l3 indicates the amount of gas that the compressor 35 sends to the exhaust main pipe 22. Line l4 indicates the heat content of the sent gas. Line l5 indicates the temperature of the gas cooled by the cooling device 40. Line l6 indicates the time change of the rotational speed of the compressor 35. Time 0 is shown when the rotational speed of the compressor 35 reaches the reference rotational speed and the gas begins to flow to the supply pipe 122 via the second solenoid valve 52. In Figure 5, the cooling capacity of the cooling device 40 is shown by the dashed line C. In Figure 5, the temperature threshold is shown by the dashed line T1. In Figure 5, the allowable temperature of the gas pipe is shown by the dashed line T2. As shown by the dashed lines T1 and T2 in Figure 5, the temperature threshold is set to a value less than or equal to the allowable temperature of the gas pipe.

[0039] As shown by line l1 in Figure 5, when the gas in the target pipe 121 is continuously drawn in by the compressor 35, the gas pressure on the intake side 35a of the compressor 35 decreases over time. Also, as shown by line l2 in Figure 5, the gas temperature on the intake side 35a of the compressor 35 remains constant or nearly constant over time, and is maintained below a temperature threshold. When the gas pressure on the intake side 35a is increased to a pressure higher than the gas pressure in the target pipe 122, as shown in Figure 4, the lower the gas pressure on the intake side 35a, the greater the difference between the gas temperature on the exhaust side 35b of the compressor 35 and the gas temperature on the intake side 35a of the compressor 35. From the above, the gas temperature on the exhaust side 35b of the compressor 35 increases over time.

[0040] The amount of gas delivered by the compressor 35 is determined based on the product of the compressor 35's gas compression capacity and rotational speed. When the gas pressure on the intake side 35a of the compressor 35 decreases, the gas compression capacity decreases. Therefore, as shown by line l3 in Figure 5, the amount of gas delivered decreases over time.

[0041] The amount of heat in the delivered gas is determined based on the product of the difference between the gas temperature on the exhaust side 35b of the compressor 35 and the gas temperature on the intake side 35a of the compressor 35, and the amount of gas delivered. When the compressor 35 starts compressing the gas and supplying it to the target pipe 122, the amount of heat in the delivered gas increases over time for a predetermined period of time. If the amount of heat in the delivered gas is less than or equal to the cooling capacity, for example, heat exchange occurs between the gas and the refrigerant for the amount of heat in the delivered gas. In this case, the difference between the amount of heat in the gas cooled by the cooling device 40 and the amount of heat in the gas on the intake side 35a of the compressor 35 is 0 or approximately 0. Therefore, the difference between the temperature of the gas cooled by the cooling device 40 and the temperature of the gas on the intake side 35a of the compressor 35 is 0 or approximately 0. On the other hand, as shown by line l4 and dashed line C in Figure 5, if the amount of heat in the delivered gas exceeds the cooling capacity, no heat exchange occurs for the amount of heat obtained by subtracting the cooling capacity from the amount of heat in the delivered gas. Therefore, when the heat output of the delivered gas exceeds the cooling capacity, the temperature of the gas cooled by the cooling device 40 rises and becomes higher than the temperature of the gas on the intake side 35a of the compressor 35. After the heat output of the delivered gas exceeds the cooling capacity, the temperature of the gas cooled by the cooling device 40 exceeds a threshold.

[0042] Here, t1 is defined as the elapsed time from the moment the gas begins to flow from the compressor 35 to the supply pipe 122 until the temperature of the gas cooled by the cooling device 40 exceeds a threshold. Between elapsed times 0 and t1, as shown in Figure 3, the temperature of the gas cooled by the cooling device 40 is below the threshold (Yes in S30), and the rotational speed is at the reference rotational speed (Yes in S40), so the control unit 31c maintains the rotational speed at the reference rotational speed (S51). The pressure sensor 214 measures the pressure of the gas drawn into the compressor 35 and transmits it to the control device 31. If the pressure of the gas drawn into the compressor 35 is below a predetermined pressure (Yes in S60), the control unit 31c stops the operation of the compressor 35 and terminates the depressurization process. On the other hand, if the pressure of the gas drawn into the compressor 35 is above a predetermined pressure (No in S60), the control unit 31c continues the depressurization process (returns to S30). In one example of the embodiment, the pressure of the gas drawn into the compressor 35 does not fall below a predetermined pressure until an elapsed time t4, which is greater than the elapsed times t2 and t3 shown in Figure 5 later, and the depressurization process continues.

[0043] Then, if the temperature of the gas cooled by the cooling device 40 exceeds a threshold (No in S30), the control unit 31c reduces the rotational speed of the compressor 35 to a lower than the reference rotational speed (S53). The control unit 31c reduces the rotational speed by, for example, a predetermined number of rotations. After a predetermined time has elapsed since the rotational speed was reduced, the control unit 31c compares the temperature of the gas cooled by the cooling device 40 with the threshold again. If the temperature of the gas cooled by the cooling device 40 exceeds the threshold (No in S30), the control unit 31c further reduces the rotational speed by a predetermined number of rotations (S53). In this way, if the temperature of the gas cooled by the cooling device 40 exceeds the threshold, the rotational speed of the compressor 35 is reduced to a lower than the reference rotational speed to bring the temperature of the gas cooled by the cooling device 40 below the threshold. The elapsed time from the moment the gas begins to flow from the compressor 35 to the supply pipe 122 until the temperature of the gas cooled by the cooling device 40 rises above the threshold and then falls below the threshold again is defined as t2 (>t1).

[0044] At elapsed time t2, the temperature of the gas cooled by the cooling device 40 is below the threshold (Yes in S30), and the rotational speed is below the reference rotational speed (No in S40), so the control unit 31c increases the rotational speed of the compressor 35 (S52). The control unit 31c increases the rotational speed by, for example, a predetermined number of rotational speeds. After a predetermined time has elapsed since increasing the rotational speed, the control unit 31c again compares the temperature of the gas cooled by the cooling device 40 with the threshold. If the gas temperature is again below the threshold, the control unit 31c increases the rotational speed by a predetermined number of rotational speeds. In one example of the embodiment, the elapsed time from the moment the gas begins to flow from the compressor 35 to the supply pipe 122 until the rotational speed changes from decreasing to increasing and returns to the reference rotational speed is defined as t3 (>t2). In the example shown in Figure 5, after elapsed time t2, the temperature of the gas cooled by the cooling device 40 is below the threshold.

[0045] After elapsed time t3, in one example of the embodiment, the temperature of the gas cooled by the cooling device 40 is below a threshold (Yes in S30), and the rotational speed is the reference rotational speed (Yes in S40). Therefore, the control unit 31c maintains the reference rotational speed (S51). Then, in one example of the embodiment, when the elapsed time from the moment the gas began to flow from the compressor 35 to the supply pipe 122 is t4 (>t3), the pressure of the gas drawn into the compressor 35 becomes less than a predetermined pressure (Yes in S60), and the depressurization process ends. In this way, during the depressurization process, the temperature of the gas cooled by the cooling device 40 is maintained not to exceed the allowable temperature of the gas pipe. As the pressure in the suction pipe 121 becomes less than a predetermined pressure due to the depressurization process, for example, a balloon, which is a blocking member that blocks the flow of gas, can be placed in the suction pipe 121, and the cut portion 140 is cut.

[0046] While the compressor 35 is operating, some of the gas leaking from the compressor 35 flows to the generator 73 via the piping 72, as shown by arrow A4 in Figure 2. The generator 73 generates electricity using the supplied gas and supplies the generated electricity to the control unit 31c.

[0047] According to the embodiment described above, the compression system 1 according to the embodiment comprises a compressor 35, a cooling device 40, and a control unit 31c. The intake side 35a of the compressor 35 is connected to a sealed pipe to be drawn in 121. The exhaust side 35b of the compressor 35 is connected to a pipe to be supplied in 122. The compressor 35 can draw gas from the pipe to be drawn in 121 and reduce the pressure of the gas in the pipe to be drawn in 121 to a predetermined pressure. The compressor 35 can compress the drawn-in gas to a pressure higher than the pressure of the gas in the pipe to be supplied in 122 and supply it to the pipe to be supplied in 122. The cooling device 40 can cool the gas flowing from the compressor 35 to the pipe to be supplied in 122. The control unit 31c operates the compressor 35 at a constant reference rotational speed to supply gas from the compressor 35 to the pipe to be supplied in 122. The control unit 31c lowers the rotational speed of the compressor 35 to a reference rotational speed if the temperature of the gas cooled by the cooling device 40 exceeds a threshold below the allowable temperature of the supply pipe. With this configuration, it is possible to provide a compression system 1 that reduces the pressure of the gas in the gas pipe and lowers the temperature of the gas being pumped to other gas pipes without improving the cooling capacity of the cooling device 40.

[0048] Here, the effects of the compression system 1 according to this embodiment will be explained by comparing it with a compression system according to a comparative example that is different from the compression system 1. Figure 6 is a diagram showing the time changes of the compressor rotation speed, the temperature of the gas cooled by the cooling device, and the amount of heat output of the gas in the compression system according to the comparative example. In Figure 6, the time change of the compressor rotation speed is shown by line l7. In Figure 6, the amount of heat output of the gas from the compressor is shown by line l8. Also, in Figure 5, the temperature of the gas cooled by the cooling device is shown by line l9. Also, in Figure 6, the cooling capacity of the cooling device 40 is shown by the dashed line C. Also, in Figure 6, the threshold is shown by the dashed line T.

[0049] In the comparative example compression system, as shown by line l7 in Figure 6, the rotational speed is constant, and even if the temperature of the gas cooled by the cooling device rises above a threshold at elapsed time t1, the rotational speed is not reduced from the reference rotational speed. Therefore, as shown by line l8 and dashed line C in Figure 6, after elapsed time t1, the amount of heat delivered by the gas significantly exceeds the cooling capacity compared to the compression system 1 according to this embodiment. As a result, as shown by line l9 and dashed line T in Figure 6, the temperature of the gas cooled by the cooling device 40 significantly exceeds the allowable temperature. Therefore, in a compression system that keeps the rotational speed constant, it is not possible to lower the temperature of the gas supplied to the target pipe unless a cooling device 40 with a higher cooling capacity is adopted.

[0050] On the other hand, in the compression system 1 according to this embodiment, when operating at a constant reference rotational speed, if the temperature of the gas cooled by the cooling device 40 exceeds a threshold, the rotational speed is lowered below the reference rotational speed. This is intended to lower the temperature of the gas supplied to the supply target pipe 122. Specifically, in the compression system 1 according to this embodiment, the amount of heat in the delivered gas does not significantly exceed the cooling capacity of the cooling device 40, and the temperature cooled by the cooling device 40 does not significantly exceed the threshold. Therefore, as shown by line l5 and dashed line T2 in Figure 5, the temperature of the gas cooled by the cooling device 40 can be kept below the allowable temperature of the gas pipe without improving the cooling capacity.

[0051] Furthermore, if the vehicle for the compression system 1 is to be a smaller vehicle, the compressor 35 and cooling device 40, etc., can be mounted on the first medium-sized truck 2, and the power supply device 70 can be mounted on the second medium-sized truck 3. In the compression system according to the comparative example, it is required to use a cooling device 40 with higher cooling capacity, but a cooling device with higher cooling capacity is larger and heavier. For this reason, in the case of the compression system according to the comparative example, the vehicle must be a truck of medium size or larger from the standpoint of the dimensions and weight of the cooling device 40, and the compressor 35 and cooling device 40 cannot be mounted on a medium-sized truck. On the other hand, in the compression system 1 according to this embodiment, the temperature of the gas supplied to the target pipe 122 can be lowered without improving the cooling capacity of the cooling device. For this reason, it is possible to avoid increasing the size and weight of the cooling device 40, and the compressor 35 and cooling device 40, etc., can be mounted on the first medium-sized truck 2. As a result, the truck for the compression system 1 can be a smaller truck, and the mobility of the compression system 1 to construction sites can be improved. Furthermore, generally speaking, obtaining a license for a semi-medium-sized truck is easier than obtaining a license for a medium-sized truck. Since a semi-medium-sized truck license allows one to operate the compression system 1 even without a medium-sized truck license, it helps to reduce the concentration of workload on workers who do hold a medium-sized truck license.

[0052] Furthermore, according to the embodiment, if the rotational speed of the compressor 35 is lower than the reference rotational speed and the temperature of the gas cooled by the cooling device 40 is below a threshold, the control unit 31c increases the rotational speed of the compressor 35. By setting the rotational speed to the highest possible value in this way, the gas transfer efficiency from the suction target pipe 121 to the supply target pipe 122 can be increased. If the temperature of the gas cooled by the cooling device 40 exceeds the threshold due to the increase in the rotational speed of the compressor 35, the control unit 31c reduces the rotational speed until the temperature falls below the threshold.

[0053] Furthermore, according to the embodiment, the compression system 1 further includes an electric motor 33 whose rotational speed can be continuously controlled by a control unit 31c. The compressor 35 is driven by the electric motor 33. Therefore, the rotational speed of the compressor 35 can be controlled more easily than with other drive devices such as an engine.

[0054] Furthermore, according to the embodiment, the compression system 1 includes a power supply device 70. If gas leaks from the compressor 35, the leaked gas is supplied to the power supply device 70. The power supply device 70 can also generate electricity using the gas leaked from the compressor 35 and supplies the generated electricity to the control unit 31c. This allows the gas leaked from the compressor 35 to be effectively used as fuel for power generation without being released into the atmosphere. In addition, electricity can be generated using the gas in the gas pipe as fuel. This extends the operating time of the compression system 1. Moreover, power can be supplied to each component of the compression system 1 without using the fuel stored in the fuel tank mounted on the compression system 1.

[0055] Furthermore, according to this embodiment, the first solenoid valve 51, the second solenoid valve 52, and the third solenoid valve 53 are controlled by the control unit 31c. This eliminates the need for workers to manually open and close them, thus reducing their workload. In particular, the first solenoid valve 51, the second solenoid valve 52, and the third solenoid valve 53 are each located inside the housing 11. Therefore, even if the construction personnel are not familiar with the work inside the housing 11, the switching of the open and closed states of the first solenoid valve 51, the second solenoid valve 52, and the third solenoid valve 53 can be achieved.

[0056] Furthermore, the control to lower the rotation speed below the reference rotation speed when the temperature of the gas cooled by the cooling device 40 exceeds a threshold is not limited to the control described in the above-described embodiment. When the temperature of the gas cooled by the cooling device 40 exceeds a threshold, the control unit 31c may, for example, continuously or stepwise reduce the rotation speed from the reference rotation speed regardless of the temperature of the gas cooled by the cooling device 40. Also, when the temperature of the gas cooled by the cooling device 40 exceeds a threshold, the control unit 31c may continuously or stepwise reduce the rotation speed from the reference rotation speed until the amount of heat output from the gas is below the cooling capacity. Also, when the amount of heat output from the gas exceeds the cooling capacity, the control unit 31c may continuously or stepwise reduce the rotation speed from the reference rotation speed until the amount of heat output from the gas is below the cooling capacity. Furthermore, after changing the rotation speed from the reference rotation speed, when the temperature of the gas cooled by the cooling device 40 is below a threshold, the control unit 31c may, for example, continuously or stepwise increase the rotation speed regardless of the temperature of the gas cooled by the cooling device 40. Furthermore, the control unit 31c may be configured to perform rotational speed control based on information such as ambient temperature and disturbances.

[0057] Furthermore, although the above-described embodiment explained using a configuration in which the compression system 1 comprises a first medium-sized truck 2 and a second medium-sized truck 3 as an example, it is not limited to this configuration. The compression system 1 may also comprise two vehicles other than medium-sized trucks. The compression system 1 may also comprise one or more vehicles. The compression system 1 may also comprise a ship instead of vehicles. Furthermore, the compression system 1 does not necessarily have to have a configuration that makes the compression system 1, such as vehicles or ships, movable.

[0058] Furthermore, by using the compression system 1 as appropriate, gas can flow from the supply pipe 122 to the suction pipe 121 via the exhaust main pipe 22 and the intake main pipe 21.

[0059] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these constituent elements deleted can be extracted as an invention. [Explanation of Symbols]

[0060] 1... Compression system, 2... First medium-sized truck, 3... Second medium-sized truck, 10... Compressor, 11... Enclosure, 20... Gas transfer system, 21... Intake main pipe, 22... Exhaust main pipe, 23... Bypass pipe, 24, 25... Connection parts, 31... Control device, 31a... Distribution board, 31b... Uninterruptible power supply, 31c... Control unit, 32... Inverter, 33... Motor, 33a... Rotating shaft, 34... Belt, 35... Compressor, 35a... Intake side, 35b…Exhaust side, 35c…Rotating shaft, 35d…Main body, 35e…Gap, 36…Gas storage section, 40…Cooling device, 41…Refrigeration unit, 42…Aftercooler, 43~45…Refrigerant pipe, 50…Temperature sensor, 51…First solenoid valve, 52…Second solenoid valve, 53…Third solenoid valve, 60…Safety pressure adjustment system, 61, 62…Piping, 63…Safety pressure regulator, 64…Piping, 70…Power supply device, 72…Piping, 73… Generator, 74…Cable, 100…Piping system, 110, 111…Valve, 121…Suction target pipe, 122…Supply target pipe, 131…First connection point, 132…Second connection point, 140…Cut section, 211…On-off valve, 212…Temperature sensor, 213, 214…Pressure sensor, 221…Sub-pipe, 222…On-off valve, 223…Safety valve, 224…On-off valve, 225…Pressure sensor, 321…Power meter, 331, 351 ...tachometer, 411...temperature sensor, 431...temperature sensor, 432...on-off valve, 433...pressure sensor, 451...temperature sensor, 452...on-off valve, 501...pressure sensor, 521...check valve, 611, 612, 621...on-off valve, 641...valve section, 721...sub-pipe, 722...safety valve, 723...on-off valve, 724...sub-pipe, 725...on-off valve, 726...safety valve, 727...on-off valve, 728...motorized valve, 729...on-off valve.

Claims

1. A compressor having an intake side connected to a sealed pipe to be drawn in and an exhaust side connected to a pipe to be supplied, capable of drawing gas from the pipe to be drawn in and reducing the pressure of the gas to a predetermined pressure, and capable of compressing the gas drawn in to a pressure higher than the pressure of the gas in the pipe to be supplied and supplying it to the pipe to be supplied, A cooling device capable of cooling the gas supplied from the compressor to the supply pipe, A control unit operates the compressor at a constant reference rotational speed to supply gas from the compressor to the supply target pipe, and if the temperature of the gas cooled by the cooling device exceeds a threshold below the allowable temperature of the supply target pipe, the control unit lowers the rotational speed of the compressor to the reference rotational speed. A compression system equipped with [the following features].

2. The compression system according to claim 1, wherein the control unit increases the rotation speed when the rotation speed is lower than the reference rotation speed and the temperature is below the threshold.

3. The control unit further comprises an electric motor capable of continuously controlling the rotational speed, The compression system according to claim 1, wherein the compressor is driven by the electric motor.

4. The compression system according to claim 1, further comprising a power supply device that can generate electricity from gas leaked from the compressor and supplies the generated electricity to the control unit.

5. A power supply device capable of supplying power to the control unit, A first medium-sized truck equipped with the compressor and the cooling device, A second medium-sized truck equipped with the aforementioned power supply device, The compression system according to any one of claims 1 to 4, further comprising:

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