Gas compressor

Abstract

To provide a technique capable of detecting the position and degree of a drain discharge abnormality. A two-stage gas compressor 100 comprises: a low-pressure-stage compressor main body 3 that compresses gas; a compressed gas cooler 5 that cools compressed gas compressed by the low-pressure-stage compressor main body 3; a drain separator 7 that separates drain from the compressed gas cooled by the compressed gas cooler 5; a drain discharge path 71, 72 that sends drain separated by the drain separator 7 to the outside of the two-stage gas compressor 100; a drain discharge valve 13 that opens and closes at predetermined intervals to discharge the separated drain; a drain discharge path pressure sensor 17 that is provided downstream of the drain discharge valve 13 and measures pressure in the drain discharge path 72; and a control unit 10 that determines the position and degree of a drain discharge abnormality based on pressure measured by the drain discharge path pressure sensor 17.

Description

TECHNICAL FIELD

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

[0002] A gas compressor is known in which a gas compressed by a compressor body is cooled by a cooler, and a mechanism for discharging drain generated during cooling of the compressed gas is provided. In such a gas compressor, if discharge of the drain is not properly performed, the drain may flow into a path of the compressed gas, resulting in a problem in which the quality of the compressed gas deteriorates.

[0003] In particular, in a multi-stage gas compressor having a plurality of compressor bodies and configured to further compress, by second-stage and subsequent compressor bodies, a gas that has been compressed by a first-stage compressor body, if discharge of drain generated during cooling of the compressed gas in the first-stage compressor body is not properly performed, the drain flows into the second-stage and subsequent compressor bodies, causing problems such as damage to the second-stage and subsequent compressor bodies.

[0004] As a technique for detecting poor drain discharge in a gas compressor, Patent Document 1 is known. Patent Document 1 describes that, in a drain discharge circuit of an air compressor, a strainer for removing foreign matter mixed in the drain, an on-off valve located downstream of the strainer, and a pressure sensor located upstream of the strainer to detect pressure in a drain pipe are provided, and that, when a pressure detection value detected by the pressure sensor while the valve is open does not become lower than a pressure detection value detected while the valve is closed, it is determined that there is a discharge failure.CITATION LISTPATENT DOCUMENT

[0005] [Patent Document 1] Patent Publication No. 2014-145325 ASUMMARY OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTION

[0006] In the technique disclosed in Patent Document 1, it is possible to detect that drain can no longer be discharged due to clogging or the like in a drain discharge path, at a location downstream of a pressure sensor in the drain discharge path, such as a strainer, an on-off valve, or piping downstream thereof. However, it is not possible to determine at which specific location downstream of the pressure sensor the problem has occurred. Therefore, when poor drain discharge is detected, it is necessary to check all possible locations that may be the cause.

[0007] In the technique disclosed in Patent Document 1, no determination is made regarding the degree of clogging in a drain discharge path, such as whether the path is completely clogged or whether there is still space despite a reduction in flow. Therefore, in a case where clogging gradually accumulates in the drain discharge path, it is not possible to address the cause before the path becomes completely clogged.

[0008] The present invention has been made in view of the above-described issues, and an object thereof is to provide a technique capable of detecting both the location and the degree of abnormality in drain discharge.SOLUTIONS TO PROBLEMS

[0009] To solve the above issues, one representative example of a gas compressor according to the present invention includes: a compressor body that compresses a gas; a compressed gas cooler that cools compressed gas by the compressor body; and a drain separator that separates drain from the compressed gas cooled by the compressed gas cooler, wherein the gas compressor includes: a drain discharge path that sends the drain separated by the drain separator to the outside of the gas compressor; a drain discharge valve that is provided in the drain discharge path and discharges the separated drain by opening and closing at predetermined intervals; a drain discharge path pressure sensor that is provided downstream of the drain discharge valve and measures pressure in the drain discharge path; and a control unit that determines a location and a degree of abnormality in drain discharge based on the pressure measured by the drain discharge path pressure sensor.EFFECTS OF THE INVENTION

[0010] According to the present invention, it is possible to detect both the location and the degree of abnormality in drain discharge.

[0011] Other problems, configurations, and effects not mentioned above will become apparent from the following description of embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 shows an example of the configuration of a two-stage gas compressor in Embodiment 1. FIG. 2 shows an example of the detailed configuration of drain discharge section A in FIG. 1. FIG. 3 shows an example of pressure measured by a drain discharge path pressure sensor when drain is normally discharged. FIG. 4 shows an example of pressure measured by a drain discharge path pressure sensor when clogging has occurred in a portion of the drain discharge path located upstream of the drain discharge path pressure sensor. FIG. 5 shows an example of pressure measured by a drain discharge path pressure sensor when complete clogging has occurred in a portion of the drain discharge path located upstream of the drain discharge path pressure sensor. FIG. 6 shows an example of pressure measured by a drain discharge path pressure sensor when the drain discharge valve fails to fully close or the like. FIG. 7 shows an example of pressure measured by a drain discharge path pressure sensor when clogging has occurred in a portion of the drain discharge path located downstream of the drain discharge path pressure sensor. FIG. 8 shows an example of pressure measured by a drain discharge path pressure sensor when severe clogging has occurred in a portion of the drain discharge path located downstream of the drain discharge path pressure sensor. FIG. 9 shows an example of pressure measured by a drain discharge path pressure sensor when high-pressure fluid has entered the drain discharge path. FIG. 10 shows an example of pressure measured by a drain discharge path pressure sensor when complete clogging has occurred in a portion of the drain discharge path located downstream of the drain discharge path pressure sensor. FIG. 11 shows a flowchart illustrating an example of abnormality detection processing executed by a control unit of the two-stage gas compressor. FIG. 12 shows a flowchart illustrating an example of upstream-side recording processing. FIG. 13 shows a flowchart illustrating an example of upstream-side determination processing. FIG. 14 shows a flowchart illustrating an example of downstream-side recording processing. FIG. 15 shows a flowchart illustrating an example of downstream-side determination processing. FIG. 16 shows an example of a yellow alert screen displayed on a monitor. FIG. 17 shows an example of a red alert screen displayed on a monitor. FIG. 18 shows an example of pressure measured by a drain discharge path pressure sensor when clogging has occurred in both a portion of the drain discharge path located upstream and a portion located downstream of the drain discharge path pressure sensor. FIG. 19 shows an example of pressure measured by a drain discharge path pressure sensor when a large amount of drain passes through the drain discharge path pressure sensor. FIG. 20 shows an example of the configuration of a two-stage gas compressor in Embodiment 3. FIG. 21 shows an example of the configuration of a two-stage gas compressor in Embodiment 5. MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments will be described with reference to the drawings.[Embodiment 1]

[0014] In Embodiment 1, a two-stage gas compressor, which is an example of a multi-stage gas compressor having a plurality of compressor bodies for compressing gas and equipped with two compressor bodies, will be described as an example.

[0015] FIG. 1 shows an example of the configuration of the two-stage gas compressor in Embodiment 1.

[0016] A two-stage gas compressor 100 includes: an suction port 1 for introducing outside air from the outside; a first-stage low-pressure compressor body 3 that initially compresses the gas introduced from the outside; a compressed gas cooler 5 that cools the gas compressed by the low-pressure compressor body 3; and a drain separator 7 that separates drain from the compressed gas cooled by the compressed gas cooler 5.

[0017] The two-stage gas compressor 100 further includes: a suction gas path 2 that sends the gas introduced from the suction port 1 to the low-pressure compressor body 3; a compressed gas path 41 that sends the gas compressed by the low-pressure compressor body 3 to the compressed gas cooler 5; and a compressed gas path 42 that sends the compressed gas cooled by the compressed gas cooler 5 to the drain separator 7.

[0018] The low-pressure compressor body 3 has, for example, two pairs of screw rotors housed inside a casing, and is of an oil-free type that does not contain lubricating oil in a compressed gas path within the casing, but is not limited thereto.

[0019] The compressed gas cooler 5 is, for example, a water-cooled type that performs heat exchange between cooling water and compressed gas, but may also cool by using air or the like.

[0020] Further, the two-stage gas compressor 100 includes: a second-stage high-pressure compressor body 4 that further compresses the gas compressed by the first-stage low-pressure compressor body 3; a compressed gas cooler 6 that cools the gas compressed by the high-pressure compressor body 4; and a drain separator 8 that separates drain from the compressed gas cooled by the compressed gas cooler 6.

[0021] Further, the two-stage gas compressor 100 includes: a compressed gas path 43 that sends the compressed gas from the drain separator 7 to the high-pressure compressor body 4; a compressed gas path 44 that sends the gas compressed by the high-pressure compressor body 4 to the compressed gas cooler 6; a compressed gas path 45 that sends the compressed gas cooled by the compressed gas cooler 6 to the drain separator 8; and a compressed gas path 46 that sends the compressed gas from the drain separator 8 to an outlet outside the gas compressor.

[0022] Further, the two-stage gas compressor 100 includes: a drain discharge section A that discharges the drain separated by the drain separator 7 to the outside of the two-stage gas compressor 100; and a drain discharge section B that discharges the drain separated by the drain separator 8 to the outside of the two-stage gas compressor 100.

[0023] FIG. 2 shows an example of the detailed configuration of drain discharge section A in FIG. 1.

[0024] Drain discharge section A includes: a strainer 65 that removes foreign matter mixed in the drain separated by the drain separator 7; a drain discharge valve 13 that opens and closes at predetermined intervals to discharge the drain from which foreign matter has been removed by the strainer 65; and an orifice 69 that discharges the drain discharged from the drain discharge valve 13 to the outside of the two-stage gas compressor 100.

[0025] Drain discharge section A further includes: a drain discharge path 71 that sends the drain from the drain separator 7 to the drain discharge valve 13; a drain discharge path 72 that discharges the drain from the drain discharge valve 13 to the outside of the two-stage gas compressor 100; a drain discharge path 75 that bypasses the drain discharge valve 13 and connects from the drain discharge path 71 to the drain discharge path 72; a check valve 63 that is disposed in the drain discharge path 71 and prevents backflow to the drain separator 7; a three-way valve 64 that is provided downstream of the check valve 63 in the drain discharge path 71 and opens one of a path to the drain discharge valve 13 or a path to the drain discharge path 75 while closing the other; and a drain discharge path pressure sensor 17 that is provided downstream of the drain discharge valve 13 and measures pressure in the drain discharge path 72.

[0026] The drain discharge path pressure sensor 17 indicates a value other than atmospheric pressure when the three-way valve 64 opens the path to the drain discharge valve 13 and the drain discharge valve 13 is open, and indicates atmospheric pressure in other cases.

[0027] Returning to FIG. 1, drain discharge section B includes: a strainer 68 that removes foreign matter mixed in the drain separated by the drain separator 8; a drain discharge valve 14 that opens and closes at predetermined intervals to discharge the drain from which foreign matter has been removed by the strainer 68; and an orifice 70 that discharges the drain discharged from the drain discharge valve 14 to the outside of the two-stage gas compressor 100.

[0028] Drain discharge section B further includes: a drain discharge path 73 that sends the drain from the drain separator 8 to the drain discharge valve 14; a drain discharge path 74 that discharges the drain from the drain discharge valve 14 to the outside of the two-stage gas compressor 100; a drain discharge path 76 that bypasses the drain discharge valve 14 and connects from the drain discharge path 73 to the drain discharge path 74; a check valve 66 that is disposed in the drain discharge path 73 and prevents backflow to the drain separator 8; a three-way valve 67 that is provided downstream of the check valve 66 in the drain discharge path 73 and opens one of a path to the drain discharge valve 14 or a path to the drain discharge path 76 while closing the other; and a drain discharge path pressure sensor 18 that is provided downstream of the drain discharge valve 14 and measures pressure in the drain discharge path 74.

[0029] The drain discharge path pressure sensor 18 indicates a value other than atmospheric pressure when the three-way valve 67 opens the path to the drain discharge valve 14 and the drain discharge valve 14 is open, and indicates atmospheric pressure in other cases.

[0030] Further, the two-stage gas compressor 100 includes: a compressed gas path pressure sensor 19 that measures the pressure in the compressed gas path 43 through which the compressed gas compressed by the low-pressure compressor body 3 passes; a compressed gas path pressure sensor 20 that measures the pressure in the compressed gas path 46 through which the compressed gas compressed by the high-pressure compressor body 4 passes; and an electric motor 9 that receives control commands from the control unit 10 and drives the low-pressure compressor body 3 and the high-pressure compressor body 4.

[0031] Further, the two-stage gas compressor 100 includes: a power transmission unit 12 that transmits the power of the electric motor 9 to the low-pressure compressor body 3 and the high-pressure compressor body 4; and a control unit 10 that controls the electric motor 9 and collects data from the drain discharge path pressure sensor 17, the drain discharge path pressure sensor 18, the compressed gas path pressure sensor 19, and the compressed gas path pressure sensor 20.

[0032] An example of the flow from gas compression to drain discharge in the two-stage gas compressor 100 will be described with reference to FIG. 1.

[0033] When the operation of the two-stage gas compressor 100 is started, the electric motor 9 is driven by a command from the control unit 10, and power is transmitted from the power transmission unit 12 to the low-pressure compressor body 3 and the high-pressure compressor body 4. Gas is drawn into the two-stage gas compressor 100 from the suction port 1 and through the suction gas path 2, and is compressed by the low-pressure compressor body 3. The compressed gas then passes through the compressed gas path 41 and is sent to the compressed gas cooler 5. Since the compressed gas becomes high in temperature, it is cooled by the compressed gas cooler 5.

[0034] By cooling, water vapor contained in the compressed gas is condensed, and drain is generated. Therefore, after cooling by the compressed gas cooler 5, the compressed gas and the drain are in a mixed state. If the compressed gas is supplied downstream while remaining mixed with the drain, there is a possibility that the receiving equipment may malfunction. Accordingly, the drain separator 7 separates the drain from the compressed gas cooled by the compressed gas cooler 5. By passing through the drain separator 7, the compressed gas is supplied to the high-pressure compressor body 4 in a state with reduced moisture content, and the drain is discharged from the drain discharge valve 13 through the drain discharge path 72.

[0035] The gas further compressed by the high-pressure compressor body 4 becomes high in temperature, and is therefore cooled by the compressed gas cooler 6. The compressed gas cooled by the compressed gas cooler 6 is subjected to separation of drain by the drain separator 8, and the compressed gas is supplied downstream through the compressed gas path 46, while the drain is discharged from the drain discharge valve 14.

[0036] As the drain separator 7, there are methods that separate compressed gas and drain using a filter, and methods that separate them by centrifugal separation. The drain discharge valves 13 and 14 are controlled to open and close by the control unit 10, and the drain is discharged by being pushed out with compressed gas when the drain discharge valves 13 and 14 are open.

[0037] Here, the drain discharge valves 13 and 14 may be controlled by the control unit 10 to open and close simultaneously, or may be controlled to open and close individually.

[0038] In the above configuration, for example, if a drain discharge failure occurs in the compressed gas cooler 5, the drain generated in the compressed gas cooler 5 is drawn into the high-pressure compressor body 4 together with the compressed gas. When drain flows into the high-pressure compressor body 4, it promotes rust formation inside the high-pressure compressor body 4, which significantly increases the possibility of malfunctions in the operation of the high-pressure compressor body 4 due to the resulting rust.

[0039] Possible causes of drain discharge failure in the compressed gas cooler 5 include clogging of the strainer 65, malfunction of the drain discharge valve 13, clogging of the orifice 69, and improper installation of the drain piping, any of which may result in improper drain discharge.

[0040] Note that, similarly to the compressed gas cooler 5, drain is also generated in the compressed gas cooler 6. In the event of a drain discharge failure here, although it does not directly affect the components within the two-stage gas compressor 100, it may affect downstream equipment connected to the compressed gas path 46. Therefore, a drain discharge section B similar to the drain discharge section A of the compressed gas cooler 5 is provided. However, with respect to the drain discharge path of the compressed gas cooler 6, the provision of the drain discharge path pressure sensor 18 and the abnormal drain discharge detection process described below using it may be omitted if the purpose is only to prevent malfunctions within the two-stage gas compressor 100.

[0041] Here, the pressure measured by the drain discharge path pressure sensor 17 will be explained with reference to FIGS. 3 to 10, in conjunction with the pressure measured by the compressed gas path pressure sensor 19.

[0042] In the graphs shown in FIGS. 3 to 10, the upper graph indicates the pressure measured by the drain discharge path pressure sensor 17 with a solid line, and the pressure measured by the compressed gas path pressure sensor 19 with a dotted line. The lower graph indicates the timing at which the drain discharge valve 13 opens.

[0043] FIG. 3 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when the drain is being discharged normally.

[0044] In FIG. 3, the drain discharge valve 13 repeatedly opens and closes. The pressure measured by the drain discharge path pressure sensor 17 rises to a value below the pressure measured by the compressed gas path pressure sensor 19 when the drain discharge valve 13 opens, and returns to atmospheric pressure when the drain discharge valve 13 closes.

[0045] Here, since the slope of the waveform of the drain discharge path pressure sensor 17 becomes gentler as it approaches the pressure measured by the compressed gas path pressure sensor 19, it can be confirmed that the time during which the pressure of the drain discharge path pressure sensor 17 sufficiently approaches the pressure of the compressed gas path pressure sensor 19 is clearly shorter than the time for which the drain discharge valve 13 remains open (for example, two seconds).

[0046] Here, "sufficiently approaches" indicates that the ratio of the value of the drain discharge path pressure sensor 17 to the value of the compressed gas path pressure sensor 19 falls within the range observed when the drain is being discharged normally. How closely the value of the drain discharge path pressure sensor 17 approaches that of the compressed gas path pressure sensor 19 varies depending on factors such as the orifice diameter of the orifice 69, the configuration of the drain discharge path outside the two-stage gas compressor 100, and the amount of generated drain.

[0047] FIG. 4 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when a clog occurs in the drain discharge path upstream of the drain discharge path pressure sensor 17.

[0048] In FIG. 4, the timing at which the drain discharge valve 13 opens and the rise in the value of the drain discharge path pressure sensor 17 are synchronized, as in the normal state shown in FIG. 3. However, when the drain discharge valve 13 opens, the value of the drain discharge path pressure sensor 17 does not sufficiently approach the value of the compressed gas path pressure sensor 19.

[0049] In this case, it can be inferred that a clog has occurred in the drain discharge path upstream of the drain discharge path pressure sensor 17. This represents a state in which, for example, due to clogging of the strainer 65 or the like, the drain discharge path upstream of the drain discharge path pressure sensor 17 has become narrower than in the normal state.

[0050] FIG. 5 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when a complete clog has occurred in the drain discharge path upstream of the drain discharge path pressure sensor 17.

[0051] In FIG. 5, it can be confirmed that when the drain discharge valve 13 opens, the value of the drain discharge path pressure sensor 17 either does not rise from atmospheric pressure or increases only very slightly.

[0052] In this case, it can be inferred that a complete clog has occurred in the drain discharge path upstream of the drain discharge path pressure sensor 17. Such a complete clog in the drain discharge path upstream of the drain discharge path pressure sensor 17 may occur, for example, when the drain discharge valve 13 fails to open or when the strainer 65 is completely clogged.

[0053] FIG. 6 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when the drain discharge valve 13 fails to close completely or the like.

[0054] In FIG. 6, it can be confirmed that the waveform of the drain discharge path pressure sensor 17 remains above atmospheric pressure at all times, regardless of the opening or closing of the drain discharge valve 13.

[0055] In this case, it can be inferred that the drain discharge valve 13 is not fully closed due to a malfunction or the like.

[0056] FIG. 7 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when a clog occurs in the drain discharge path downstream of the drain discharge path pressure sensor 17.

[0057] In FIG. 7, compared to the waveform of the drain discharge path pressure sensor 17 in FIG. 3, which shows the case where the drain is being discharged normally, the slope does not significantly become gentler when the drain discharge valve 13 opens and the value of the drain discharge path pressure sensor 17 approaches the value of the compressed gas path pressure sensor 19. Therefore, the duration in which the value of the drain discharge path pressure sensor 17 sufficiently approaches the value of the compressed gas path pressure sensor 19 is longer and closer to the duration for which the drain discharge valve 13 remains open.

[0058] In this case, it can be inferred that a clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17. For example, this corresponds to a situation in which a clog has started to form in the external drain discharge path of the two-stage gas compressor 100, resulting in the drain discharge path becoming narrower than in the normal state.

[0059] The greater the degree of clogging, the longer the duration in which the pressure of the drain discharge path pressure sensor 17 remains close to the pressure of the compressed gas path pressure sensor 19.

[0060] FIG. 8 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when a significant clog that makes drain discharge difficult has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17.

[0061] In FIG. 8, similar to the waveform of the drain discharge path pressure sensor 17 in FIG. 7, the duration during which the value of the drain discharge path pressure sensor 17 approaches the value of the compressed gas path pressure sensor 19 when the drain discharge valve 13 opens is long and close to the duration for which the drain discharge valve 13 remains open. Also, similar to the waveform of the drain discharge path pressure sensor 17 in FIG. 6, the value of the drain discharge path pressure sensor 17 remains above atmospheric pressure regardless of the opening or closing of the drain discharge valve 13.

[0062] In this case, it can be inferred that a clog making it significantly difficult to discharge the drain has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17. The term "significantly difficult to discharge" refers to a state in which the external drain discharge path of the two-stage gas compressor 100 has become narrowed due to some cause, resulting in the rate of drain discharge being slower than the rate at which the drain is generated.

[0063] FIG. 9 is a diagram illustrating an example of the pressure measured by the drain discharge path pressure sensor 17 when a high-pressure fluid enters the drain discharge path.

[0064] In FIG. 9, when the drain discharge valve 13 is opened, the pressure measured by the drain discharge path pressure sensor 17 is clearly higher than the pressure measured by the compressed gas path pressure sensor 19.

[0065] This is an example of the pressure measured by the drain discharge path pressure sensor 17 when a high-pressure fluid backflows into the drain discharge path 72 from an external path of the two-stage gas compressor 100 that has a pressure higher than that at the drain discharge path pressure sensor 17.

[0066] FIG. 10 is a diagram showing an example of the pressure measured by the drain discharge path pressure sensor 17 when a complete clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17.

[0067] In FIG. 10, regardless of the opening and closing of the drain discharge valve, the value measured by the drain discharge path pressure sensor 17 consistently rises to approximately the same level as the value measured by the compressed gas path pressure sensor 19.

[0068] In this case, it can be inferred that a complete clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17. A "complete clog" refers to a state in which the external drain discharge path of the two-stage gas compressor 100 is entirely clogged due to some cause, making it impossible to discharge the drain at all.

[0069] A method for detecting a drain discharge failure based on the above-described tendencies will be described. The following description is based on detection in the drain discharge section A shown in FIG. 2.

[0070] FIG. 11 is a flowchart illustrating an example of an abnormality detection process executed by the control unit 10 of the two-stage gas compressor 100.

[0071] The process shown in FIG. 11 starts after a predetermined number of seconds has elapsed from the start of operation of the two-stage gas compressor 100 and after the drain has begun to be generated. Thereafter, steps S102 to S107-comprising data collection, calculation, and judgment of discharge failure-are repeated at predetermined intervals. These predetermined intervals are set in advance to be shorter than the time during which the drain discharge valve 13 remains open.

[0072] First, the control unit 10 acquires the pressure values measured by the drain discharge path pressure sensor 17 and the compressed gas path pressure sensor 19 (step S102), and stores the value from the drain discharge path pressure sensor 17 in variable N1 and the value from the compressed gas path pressure sensor 19 in variable M1 (step S103).

[0073] Subsequently, upstream-side recording processing is executed (step S104) to collect data regarding clogs on the upstream side of the drain discharge path pressure sensor 17. Then, upstream-side determination processing is executed (step S105) to determine the presence and degree of clogging on the upstream side of the drain discharge path pressure sensor 17 based on the data collected in step S104.

[0074] Next, downstream-side recording processing is executed (step S106) to collect data regarding clogs on the downstream side of the drain discharge path pressure sensor 17. Then, downstream-side determination processing is executed (step S107) to determine the presence and degree of clogging on the downstream side of the drain discharge path pressure sensor 17 based on the data collected in step S106, and the process returns to step S102.

[0075] Note that the upstream-side processing in steps S104 and S105 may be executed after the downstream-side processing in steps S106 and S107.

[0076] In the flowcharts shown in FIGS. 12 to 15 below, variables U1, U2, U3, D1, D2, D3, and D4 are used, all of which are initialized to 0. These variables serve as counters that increment by +1 when certain conditions are met and reset to 0 under other conditions. When the process in FIG. 11 is repeated, variables U1, U2, U3, D1, D2, and D3 may be incremented on each cycle, which indicates that a certain state continues over time.

[0077] In the flowcharts shown in FIGS. 12 to 15, a yellow alert is output when the drain discharge path is clogged but the two-stage gas compressor 100 can continue operating, while a red alert is output when an abnormality in the drain discharge path requires stopping the operation of the two-stage gas compressor 100.

[0078] FIG. 12 is a flowchart illustrating an example of the upstream-side recording process in step S104 of FIG. 11, and FIG. 13 is a flowchart illustrating an example of the upstream-side determination process in step S105 of FIG. 11.

[0079] Through the processes shown in FIGS. 12 and 13, it is determined whether there is a malfunction on the upstream side (the drain discharge path 71 side) of the drain discharge path pressure sensor 17.

[0080] In FIG. 12, the control unit 10 compares the value of N1 with the value obtained by multiplying the value of M1 by a predetermined first constant smaller than 1, and determines whether the value of N1 is smaller than the value of M1 multiplied by the first constant (Step S121). Here, the first constant is set to determine whether the value of the drain discharge path pressure sensor 17 is sufficiently close to the value of the compressed gas path pressure sensor 19. "Sufficiently close" indicates, as explained in FIG. 3, that the ratio of the value of the drain discharge path pressure sensor 17 to the value of the compressed gas path pressure sensor 19 falls within a range observed when the drain is being discharged normally.

[0081] When the state in which the value of N1 is smaller than the value of M1 multiplied by the first constant continues, it can be inferred, as shown in FIG. 4, that the value of the drain discharge path pressure sensor 17 does not sufficiently approach the value of the compressed gas path pressure sensor 19 when the drain discharge valve 13 is opened, and that a clog has occurred in the drain discharge path upstream of the drain discharge path pressure sensor 17.

[0082] If, in step S121, the value of N1 is smaller than the value of M1 multiplied by the first constant, 1 is added to the variable U1 (step S122), and the process proceeds to step S124. On the other hand, if the value of N1 is equal to or greater than the value of M1 multiplied by the first constant in step S121, the variable U1 is reset to 0 (step S123), and the process proceeds to step S124. Accordingly, if the variable U1 is incremented while the drain discharge valve 13 is closed, the system will not judge the condition as abnormal as long as the value of the drain discharge path pressure sensor 17 sufficiently increases when the drain discharge valve 13 is opened.

[0083] Next, the control unit 10 compares the value of N1 with the maximum measurement error of the drain discharge path pressure sensor 17, and determines whether the value of N1 is smaller than the maximum measurement error of the drain discharge path pressure sensor 17 (step S124).

[0084] When the value of N1 continuously remains smaller than the maximum measurement error of the drain discharge path pressure sensor 17, as shown in FIG. 5, the waveform of the drain discharge path pressure sensor 17 shows no increase from atmospheric pressure or only a very slight increase, suggesting that a complete clog has occurred in the drain discharge path upstream of the drain discharge path pressure sensor 17.

[0085] In step S124, if the value of N1 is smaller than the maximum measurement error of the drain discharge path pressure sensor 17, 1 is added to the variable U2 (step S125), and the process proceeds to step S127. On the other hand, if the value of N1 is equal to or greater than the maximum measurement error of the drain discharge path pressure sensor 17 in step S124, the variable U2 is reset to 0 (step S126), and the process proceeds to step S127.

[0086] Next, the control unit 10 compares the value of N1 with a value obtained by multiplying the value of M1 by a second predetermined constant smaller than 1, and determines whether the value of N1 is greater than the value obtained by multiplying the value of M1 by the second predetermined constant (step S127). Here, the second constant is set to a value less than 1 and greater than 0 so that the value obtained by multiplying M1 by the second constant is greater than atmospheric pressure.

[0087] If the state in which the value of N1 is greater than the value obtained by multiplying the value of M1 by a second predetermined constant less than 1 continues, it can be inferred, as shown in FIG. 6, that the waveform of the drain discharge path pressure sensor 17 always exceeds atmospheric pressure regardless of the opening and closing of the drain discharge valve 13, suggesting that the drain discharge valve 13 is not fully closed.

[0088] If, in step S127, the value of N1 is greater than the value obtained by multiplying the value of M1 by the second constant, 1 is added to the variable U3 (step S128), and the process ends. On the other hand, if the value of N1 is less than or equal to the value obtained by multiplying the value of M1 by the second constant in step S127, the variable U3 is reset to 0 (step S129), and the process ends.

[0089] Next, in FIG. 13, the control unit 10 determines whether the value of the variable U1 exceeds a predetermined number of times (step S132). In the process shown in FIG. 13, the predetermined number of times is set to be greater than the number of times the process in FIG. 11 is repeated between one opening of the drain discharge valve 13 and the next.

[0090] If, in step S132, the value of the variable U1 exceeds the predetermined number of times, then, as shown in FIG. 4, it is determined that the value of the drain discharge path pressure sensor 17 does not sufficiently approach the value of the compressed gas path pressure sensor 19 when the drain discharge valve 13 opens, and that there is a clog in the drain discharge path upstream of the drain discharge path pressure sensor 17. A yellow alert is then output (step S133), and the process proceeds to step S134. On the other hand, if the value of the variable U1 does not exceed the predetermined number of times in step S132, the process also proceeds to step S134.

[0091] Next, the control unit 10 determines whether the value of the variable U2 exceeds a predetermined number of times (step S134).

[0092] If, in step S134, the value of the variable U2 exceeds the predetermined number of times, then, as shown in FIG. 5, it is determined that the waveform of the drain discharge path pressure sensor 17 does not rise from atmospheric pressure or rises only slightly, and that there is a complete clog in the drain discharge path upstream of the drain discharge path pressure sensor 17. A red alert is then output (step S135), and the process proceeds to step S136. On the other hand, if the value of the variable U2 does not exceed the predetermined number of times in step S134, the process proceeds to step S136.

[0093] Next, the control unit 10 determines whether the value of the variable U3 exceeds a predetermined number of times (step S136).

[0094] If the value of the variable U3 exceeds the predetermined number of times in step S136, it is determined that the drain discharge valve 13 is not closing properly, as indicated in FIG. 6, since the waveform of the drain discharge path pressure sensor 17 remains above atmospheric pressure regardless of the opening or closing of the drain discharge valve 13. In this case, a yellow alert is output (step S137), and the process is terminated. On the other hand, if the value of the variable U3 does not exceed the predetermined number of times in step S136, the process is terminated.

[0095] Note that, in order to distinguish the downstream discharge abnormality determined in step S157 of FIG. 15, which will be described later, the predetermined count in step S137 is preferably sufficiently longer than that in step S157.

[0096] Here, when a complete clog occurs in the drain discharge path upstream of the drain discharge path pressure sensor 17, it is not possible to determine whether the downstream drain discharge path is normal. Therefore, when a red alert for a complete upstream clog is output, the downstream path is also checked for clogging.

[0097] FIG. 14 is a flowchart illustrating an example of the downstream recording process of step S106 in FIG. 11, and FIG. 15 is a flowchart illustrating an example of the downstream determination process of step S107 in FIG. 11.

[0098] Through the processes shown in FIGS. 14 and 15, it is determined whether there is a malfunction in the downstream side (the drain discharge path 72 side) of the drain discharge path pressure sensor 17.

[0099] In FIG. 14, the control unit 10 compares the value N1 with the value obtained by multiplying the value M1 by a predetermined third constant greater than 1, and determines whether the value N1 is greater than the value obtained by multiplying the value M1 by the third constant (Step S140). Here, the third constant is set to a value greater than 1 so that it can be determined that the value N1 is clearly greater than the value M1.

[0100] When the value N1 is greater than the value obtained by multiplying the value M1 by the third constant, it can be inferred, as shown in FIG. 9, that when the drain discharge valve 13 is opened, the pressure measured by the drain discharge path pressure sensor 17 is clearly higher than the pressure measured by the compressed gas path pressure sensor 19, indicating that high-pressure fluid is backflowing into the drain discharge path 72 from an external path of the two-stage gas compressor 100 that has a pressure higher than that of the drain discharge path pressure sensor 17.

[0101] If the value N1 is greater than the value obtained by multiplying the value M1 by the third constant in step S140, 1 is added to the variable D1 (step S141), and the process proceeds to step S143. On the other hand, if the value N1 is less than or equal to the value obtained by multiplying the value M1 by the third constant in step S140, the variable D1 is reset to 0 (step S142), and the process proceeds to step S143.

[0102] Next, the control unit 10 compares the value N1 with the value obtained by multiplying the value M1 by a predetermined first constant that is less than 1, and determines whether the value N1 is greater than the value obtained by multiplying the value M1 by the predetermined first constant that is less than 1 (step S143).

[0103] If the condition in which the value N1 is greater than the value obtained by multiplying the value M1 by a predetermined first constant that is less than 1 continues, then, as shown in FIG. 10, the value of the drain discharge path pressure sensor 17 remains consistently as high as the value of the compressed gas path pressure sensor 19 regardless of the opening and closing of the drain discharge valve, suggesting that a complete clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17.

[0104] If, in Step S143, the value N1 is greater than the value obtained by multiplying the value M1 by a predetermined first constant that is less than 1, then 1 is added to the variable D2 (Step S144), and the process proceeds to Step S146. On the other hand, if, in Step S143, the value N1 is equal to or less than the value obtained by multiplying the value M1 by the predetermined first constant that is less than 1, then the variable D2 is reset to 0 (Step S145), and the process proceeds to Step S148.

[0105] Next, the control unit 10 determines whether the value of the variable D2 is equal to a predetermined number of times (Step S146). This predetermined number is set to be smaller than the number of times the process in FIG. 11 is repeated while the drain discharge valve 13 remains open, and to a value that the variable D2 would not reach when the drain is being discharged normally.

[0106] If the value of the variable D2 is equal to the predetermined number in step S146, 1 is added to the variable D4 (step S147), and the process proceeds to step S148. On the other hand, if the value of the variable D2 is not equal to the predetermined number in step S146, the process proceeds to step S148.

[0107] When the state in which the value of the variable D2 is equal to the predetermined number continues, it can be inferred, as shown in FIG. 7, that the time during which the pressure value of the drain discharge path pressure sensor 17 sufficiently approaches the pressure value of the compressed gas path pressure sensor 19 becomes long and approaches the time during which the drain discharge valve 13 remains open, indicating that a clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17.

[0108] This process is intended to detect a state in which the pressure of the drain discharge path pressure sensor 17 rapidly rises due to narrowing of the drain discharge path downstream of the drain discharge path pressure sensor 17, but then drops when the drain discharge valve 13 closes.

[0109] A clog in the upstream drain discharge path of the drain discharge path pressure sensor 17 can be determined by observing for a predetermined period that the value of the drain discharge path pressure sensor 17 is lower than during normal operation. On the other hand, when there is a clog in the downstream drain discharge path of the drain discharge path pressure sensor 17, the waveform of the drain discharge path pressure sensor 17 sharply rises when the drain discharge valve 13 opens and returns to around atmospheric pressure when the valve closes. Therefore, it is necessary to observe multiple instances in which the value of the drain discharge path pressure sensor 17 rises sharply. Accordingly, it is appropriate to use variable D4 as described above and to increment variable D4 by 1 only when the value of variable D2 reaches the predetermined count.

[0110] If a yellow alert is to be output even when a rapid increase in the value of the drain discharge path pressure sensor 17 is observed only once, then variable D4 does not need to be used, and a yellow alert may be output when D2 exceeds the predetermined count.

[0111] Next, the control unit 10 compares the value N1 with a value obtained by multiplying the value M1 by a predetermined second constant that is smaller than 1, and determines whether the value N1 is greater than the value obtained by multiplying M1 by the second constant (Step S148). Here, the second constant is set to a value smaller than 1 and greater than 0 such that the value obtained by multiplying M1 by the second constant becomes greater than atmospheric pressure.

[0112] In a case where the state in which variable D2 is equal to the predetermined count continues, and the state in which the value of N1 is greater than the value obtained by multiplying the value of M1 by a predetermined second constant less than 1 also continues, then, as shown in FIG. 8, the time during which the value of the drain discharge path pressure sensor 17 sufficiently approaches the value of the compressed gas path pressure sensor 19 becomes long and close to the time during which the drain discharge valve 13 is open, and regardless of the opening and closing of the drain discharge valve 13, the value of the drain discharge path pressure sensor 17 remains constantly above atmospheric pressure, and it can be inferred that a clog that makes it sufficiently difficult to discharge the drain has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17.

[0113] In step S148, when the value of N1 is greater than the value obtained by multiplying the value of M1 by the second constant, 1 is added to variable D3 (step S149), and the process ends. On the other hand, in step S148, when the value of N1 is equal to or less than the value obtained by multiplying the value of M1 by the second constant, variable D3 is set to 0 (step S150), and the process ends.

[0114] Next, in FIG. 15, the control unit 10 determines whether the value of variable D1 exceeds 1 (step S153).

[0115] In step S153, when the value of variable D1 exceeds 1, as shown in FIG. 9, it is determined that the pressure measured by the drain discharge path pressure sensor 17 when the drain discharge valve 13 is opened is clearly higher than the pressure measured by the compressed gas path pressure sensor 19, and that high-pressure fluid is flowing back into the drain discharge path 72 from an external path of the two-stage gas compressor 100 that has a pressure higher than the pressure of the drain discharge path pressure sensor 17. A red alert is output (step S154), and the process proceeds to step S155. On the other hand, when the value of variable D1 does not exceed 1 in step S153, the process proceeds to step S155.

[0116] Next, the control unit 10 determines whether the value of variable D4 exceeds a predetermined count (step S155). This predetermined count is set to a value of 2 or more.

[0117] When the value of variable D4 exceeds the predetermined count in step S155, then, as shown in FIG. 7, it is determined that the time during which the value of the drain discharge path pressure sensor 17 sufficiently approaches the value of the compressed gas path pressure sensor 19 is long and close to the time for which the drain discharge valve 13 remains open, and that a clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17. A yellow alert is output (step S156), and the process proceeds to step S157. On the other hand, when the value of variable D4 does not exceed the predetermined count in step S155, the process proceeds to step S159.

[0118] In step S157, the control unit 10 determines whether the value of variable D3 exceeds the predetermined count. This predetermined count is set to a value greater than at least the number of times the process in FIG. 11 is repeated during the time from when the drain discharge valve 13 opens until it opens again.

[0119] In step S157, when the value of variable D3 exceeds the predetermined count, it is determined, as shown in FIG. 8, that the time during which the value of the drain discharge path pressure sensor 17 sufficiently approaches the value of the compressed gas path pressure sensor 19 is long and is close to the time during which the drain discharge valve 13 is open, and that the value of the drain discharge path pressure sensor 17 always exceeds atmospheric pressure regardless of the opening and closing of the drain discharge valve 13. It is thereby determined that a clog that makes it difficult to sufficiently discharge the drain has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17, and a red alert is output (step S158), after which the process proceeds to step S159. On the other hand, if the value of variable D3 does not exceed the predetermined count in step S157, the process proceeds to step S159.

[0120] In step S159, the control unit 10 determines whether the value of variable D2 exceeds the predetermined count.

[0121] If, in step S159, the value of variable D2 exceeds the predetermined count, then, as shown in FIG. 10, it is determined that the value of the drain discharge path pressure sensor 17 remains consistently high to the same level as the value of the compressed gas path pressure sensor 19 regardless of the opening and closing of the drain discharge valve 13, and that a complete clog has occurred in the drain discharge path downstream of the drain discharge path pressure sensor 17. A red alert is then output (step S160), and the process ends. On the other hand, if, in step S159, the value of variable D2 does not exceed the predetermined count, the process ends.

[0122] The determination results of clogging in the drain discharge path described above can be displayed and checked on a monitor 98 provided on the front face of the two-stage gas compressor 100 by outputting a signal from the control unit 10.

[0123] FIG. 16 is a diagram showing an example of a screen of a yellow alert displayed on the monitor 98, and FIG. 17 is a diagram showing an example of a screen of a red alert displayed on the monitor 98.

[0124] The yellow alert in FIG. 16 is output when the drain discharge path is clogged but the two-stage gas compressor 100 can still operate. In the yellow alert, the location where the clog has occurred is displayed.

[0125] The red alert in FIG. 17 is output when the operation of the two-stage gas compressor 100 is to be stopped due to an abnormality in the drain discharge path. In the red alert, the location where the clog has occurred is displayed along with an indication on the monitor that the drain cannot be discharged, and the control unit 10 stops the operation of the two-stage gas compressor 100.

[0126] According to Embodiment 1, the drain discharge valve 13 opens and closes at a predetermined interval, and the control unit 10 determines the position and degree of the drain discharge abnormality based on the waveform of the drain discharge path pressure sensor 17, which measures the pressure in the drain discharge path 72, thereby enabling detection of the position and degree of the drain discharge abnormality.[Embodiment 2]

[0127] The configuration of the two-stage gas compressor in Embodiment 2 is the same as in Embodiment 1. In Embodiment 2, the waveform of the drain discharge path pressure sensor 17, as shown in FIGS. 3 to 10 and the like, is displayed on the monitor 98, whereby the operator can check the position and degree of clogging in the drain discharge path in detail.

[0128] For example, in Embodiment 1, when a yellow alert is issued due to clogging on the upstream side of the drain discharge path pressure sensor 17, there are the following two possible patterns in which the abnormality detection processing in FIG. 11 cannot determine the detailed condition of the drain discharge path. In Embodiment 2, this can be confirmed from the waveform of the drain discharge path pressure sensor 17 displayed on the monitor 98. In Embodiment 2, this can be confirmed from the waveform of the drain discharge path pressure sensor 17 displayed on the monitor 98.

[0129] The first pattern is a case where both the upstream and downstream of the drain discharge path pressure sensor 17 are clogged, but fluid can still pass through the piping. In the abnormality detection process in FIG. 11, a yellow alert is issued based on a clog in the upstream drain discharge path of the drain discharge path pressure sensor 17. In this case, a waveform such as that shown in FIG. 18 is displayed on the monitor 98.

[0130] Figure 18 shows an example of the pressure measured by the drain discharge path pressure sensor 17 when clogs occur in both the upstream and downstream drain discharge paths of the drain discharge path pressure sensor 17.

[0131] In Figure 18, the value of the drain discharge path pressure sensor 17 does not rise until it is determined that the drain is being discharged normally. Additionally, the time during which the pressure of the drain discharge path pressure sensor 17 is sufficiently close to the pressure of the compressed gas path pressure sensor 19 is long.

[0132] The second pattern is a case where there is no clog in the drain discharge path, but a large amount of drain passes through the drain discharge path pressure sensor 17. Depending on the value of the first constant in step S121 of Figure 12, a yellow alert is output on the assumption that there is a clog in the drain discharge path upstream of the drain discharge path pressure sensor 17. In this case, a waveform as shown in Figure 19 is displayed on the monitor 98.

[0133] FIG. 19 is a diagram showing an example of the pressure measured by the drain discharge path pressure sensor 17 when a large amount of drain passes through the drain discharge path pressure sensor 17.

[0134] In FIG. 19, the value of the drain discharge path pressure sensor 17 increases more gradually compared to the case in which the drain is being discharged normally.

[0135] The second pattern occurs, for example, when a large amount of drain is generated due to high temperature and high humidity around the two-stage gas compressor 100. Although no clog has occurred in the drain discharge path, it is possible that the open duration of the drain discharge valve 13 is short, and therefore, a countermeasure can be implemented by changing the setting to increase this duration.

[0136] According to Embodiment 2, by displaying the waveform of the drain discharge path pressure sensor 17 on the monitor 98, the operator can check in detail the location and degree of the clog in the drain discharge path.[Embodiment 3]

[0137] Embodiment 3 is the same as Embodiment 1 in that the abnormality detection process shown in FIG. 11 is executed.

[0138] FIG. 20 is a diagram illustrating an example of the configuration of the two-stage gas compressor 100 of Embodiment 3.

[0139] The two-stage gas compressor 100 shown in FIG. 20 differs from FIG. 1 only in that a temperature sensor 77 and a humidity sensor 78 are provided in the suction port 1 that introduces outside air from the outside. The same reference numerals are assigned to components that are the same as those in FIG. 1, and detailed description thereof is omitted.

[0140] The temperature sensor 77 and the humidity sensor 78 respectively measure the temperature and humidity of the outside air introduced from the outside through the suction port 1.

[0141] The first constant used in the abnormality detection process is made variable based on the values measured by the temperature sensor 77 and the humidity sensor 78. The amount of drain generated can be estimated from the temperature and humidity of the outside air introduced from the outside, and the constant used to determine the condition of the drain discharge path is changed according to the behavior when a large amount of drain is generated or when little to no drain is generated.

[0142] For example, when the outside air is hot and humid, it is estimated that a large amount of drain flows, and in this case, the value of the drain discharge path pressure sensor 17 may not increase as much as usual. Therefore, by lowering the first constant used to determine a clog in the drain discharge path upstream of the drain discharge path pressure sensor 17, it is possible to avoid a false determination of a clog in the upstream side.

[0143] According to Example 3, by changing the constant used in the abnormality detection process based on the temperature and humidity of the outside air, it becomes possible to determine the drain discharge abnormality in accordance with the amount of drain generated, thereby reducing the incidence of false determinations.[Embodiment 4]

[0144] Embodiment 4 is similar to Embodiment 1 in that the location and degree of a clog in the drain discharge path are determined based on the waveform of the drain discharge path pressure sensor 17. However, the abnormality detection processing shown in Fig. 11 is not executed. Instead, the location and degree of the clog are determined based on waveform analysis using machine learning applied to the waveform of the drain discharge path pressure sensor 17 displayed on the monitor 98, and an alert is displayed on the monitor 98 according to the settings.

[0145] This waveform determination does not need to be continuously performed. It may be executed based on the waveform shape at predetermined time intervals, or it may be executed at any arbitrary timing.

[0146] According to Embodiment 4, it is possible to detect the position and degree of a drain discharge abnormality from the complex patterns of the waveform of the drain discharge path pressure sensor 17 without confirmation by an operator.[Embodiment 5]

[0147] Embodiment 5 is the same as Embodiment 1 in that it executes the abnormality detection process shown in Fig. 11.

[0148] Fig. 21 is a diagram showing an example of the configuration of the two-stage gas compressor 100 according to Embodiment 5.

[0149] The two-stage gas compressor 100 shown in Fig. 21 differs from that shown in Fig. 1 only in that it has an antenna 99 capable of external communication from the control unit 10. The same reference numerals are given to components having the same configuration as those in Fig. 1, and their description is omitted.

[0150] The result of an abnormality in the drain discharge path detected by the abnormality detection process shown in Fig. 11 is transmitted to an external device via the antenna 99. This allows the person in charge of maintaining the two-stage gas compressor 100 to be notified of the abnormality in the drain discharge path and to respond promptly.

[0151] According to Embodiment 5, since the two-stage gas compressor 100 has a function of notifying the outside of the position and degree of the drain discharge abnormality, the position and degree of the drain discharge abnormality can be notified to the operator at an early stage. This makes it possible to more quickly prepare the necessary countermeasures and parts to be replaced according to the position and degree of the drain discharge abnormality, and to respond to the drain discharge abnormality.

[0152] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the above-described embodiments have been described in detail to facilitate understanding of the present invention and are not necessarily limited to those including all the configurations described. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, part of the configuration of each embodiment may be added to, deleted from, or replaced with another configuration.REFERENCE SIGNS LIST

[0153] 3 Low-pressure stage compressor body 5 Compressed gas cooler 7 Drain separator 10 Control unit 13 Drain discharge valve 17 Drain discharge path pressure sensor 19 Compressed gas path pressure sensor 71 Drain discharge path 72 Drain discharge path 100 Two-stage gas compressor

Claims

1. A gas compressor comprising: a compressor main body that compresses gas; a compressed gas cooler that cools compressed gas compressed by the compressor main body; and a drain separator that separates drain from compressed gas cooled by the compressed gas cooler, wherein the gas compressor further comprises: a drain discharge path that sends drain separated by the drain separator to the outside of the gas compressor; a drain discharge valve provided in the drain discharge path, the drain discharge valve opening and closing at predetermined intervals to discharge the separated drain; a drain discharge path pressure sensor provided downstream of the drain discharge valve, the drain discharge path pressure sensor measuring pressure in the drain discharge path; and a control unit that determines the position and degree of a drain discharge abnormality based on pressure measured by the drain discharge path pressure sensor.

2. The gas compressor according to claim 1, further comprising: a compressed gas path through which compressed gas compressed by the compressor main body passes; and a compressed gas path pressure sensor that measures pressure in the compressed gas path, wherein the control unit records a time during which a ratio of pressure measured by the drain discharge path pressure sensor to pressure measured by the compressed gas path pressure sensor is within a predetermined range, and determines the position and degree of a drain discharge abnormality based on the recorded time.

3. The gas compressor according to claim 2, further comprising: a display unit, wherein the control unit displays the position and degree of a drain discharge abnormality on the display unit.

4. The gas compressor according to claim 2, further comprising: a temperature sensor that measures a temperature of outside air, and a humidity sensor that measures a humidity of the outside air, wherein the control unit changes the predetermined range based on the measured temperature of the outside air and the measured humidity of the outside air.

5. The gas compressor according to claim 2, further comprising: a display unit, wherein the gas compressor displays, on the display unit, waveforms of the pressure measured by the drain discharge path pressure sensor and the pressure measured by the compressed gas path pressure sensor.

6. The gas compressor according to claim 2, wherein the control unit determines the position and degree of the drain discharge abnormality based on waveforms of pressure measured by the drain discharge path pressure sensor and the compressed gas path pressure sensor, using waveform analysis by machine learning.

7. The gas compressor according to claim 2, further comprising: an antenna capable of communicating with an external device, wherein the control unit transmits the position and degree of the drain discharge abnormality to the external device via the antenna.

8. The gas compressor according to claim 2, wherein the compressor main body comprises: a low-pressure-stage compressor main body that compresses gas taken from outside the gas compressor; and a high-pressure-stage compressor main body that further compresses the gas compressed by the low-pressure-stage compressor main body, wherein the compressed gas cooler comprises: a first cooler that cools the gas compressed by the low-pressure-stage compressor main body; and a second cooler that cools the gas compressed by the high-pressure-stage compressor main body, wherein the drain separator separates drain from the compressed gas cooled by the first cooler.

9. The gas compressor according to claim 2, wherein the compressor main body includes a screw rotor.

10. The gas compressor according to claim 2, wherein the compressed gas path does not contain lubricating oil.

11. The gas compressor according to claim 2, wherein the compressed gas cooler cools the compressed gas by exchanging heat between cooling water and the compressed gas.

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