Compressor drain mixing prevention structure

Abstract

To prevent a drain of a dehumidifier from being carried out to a consumption side along with a compressed gas.SOLUTION: A dehumidifier 60, such as an after cooler 61 and a dryer 62, is provided in a supply flow path 40 in which one end is connected to a compressed gas supply part, such as a receiver tank 20 provided in a compressor 1, and the other end is connected to a consumption side, and a restriction 70, such as Venturi tube, is provided in the supply flow path 40 in a secondary side of the dehumidifier 60. The restriction 70 is formed in a flow path area to be choked when a flow velocity of the compressed gas within the supply flow path 40 reaches a predetermined upper-limit flow velocity. The upper-limit flow velocity is set as a flow velocity that is lower by a predetermined margin than the flow velocity of the compressed gas that is obtained in advance by an experiment or the like and is within the supply flow path 40 in which drain accumulated within the dehumidifier 60 starts to be carried out to the consumption side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a drain mixing prevention structure for a compressor, and more specifically, to a drain mixing prevention structure for preventing drain accumulated in a dehumidifying device from mixing with the compressed gas supplied to the consumption side in a compressor in which equipment for dehumidifying compressed gas such as an aftercooler, dryer, drain separator, and afterwarmer (collectively referred to as "dehumidifying equipment" in this specification) is provided in a supply flow path that supplies compressed gas discharged from the compressor body to the consumption side. [Background technology]

[0002] In an oil-cooled screw compressor, which uses lubricating oil to lubricate, cool, and seal the compression space, the gas to be compressed that is drawn into the compressor body through the intake port is compressed together with the lubricating oil and discharged as a gas-liquid mixed fluid.

[0003] Therefore, the compressed gas discharged from the compressor body together with the lubricating oil is temporarily stored in a receiver tank where gas and liquid are separated, and the compressed gas from which the oil has been separated is supplied to the consumer side.

[0004] In such compressors, depending on the type of air working machine connected to the consumption side, it may be necessary to supply dry compressed gas that has not only been oil-free but also has moisture removed.

[0005] In such a case, as shown in FIG. 4, compressed gas from a receiver tank (not shown) is passed through a dehumidifying device 160 to be dehumidified, and then supplied to the consumer side.

[0006] As an example, in the compressor 100 shown in Figure 4, a dehumidifying device 160 consisting of an aftercooler 161, a drain separator 163, and piping connecting the aftercooler 161 and the drain separator 163 is provided in a supply flow path 140 that supplies compressed gas that has passed through an oil separator 121 provided in a receiver tank (not shown) to the consumption side.

[0007] This dehumidifying device 160 is used to introduce the compressed gas into an aftercooler 161 for cooling, thereby condensing the moisture present in the compressed gas as water vapor, and the drain generated by this condensation is collected and removed by a drain separator 163, thereby obtaining dried compressed gas that can be supplied to the consumer side.

[0008] In addition, the aforementioned drain separator 163, which collects the drainage generated by condensation due to cooling in the aftercooler 161, is provided with a float valve (not shown), and when the drainage collected in the drain separator 163 reaches a predetermined water level or above, this float valve opens, and the drainage is discharged outside the machine through the drain piping 163b by the pressure of the compressed gas flowing in the supply flow path 140, thereby preventing the collected drainage from being transported to the consumption side (see Figure 1 of Patent Document 1). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 3771205 Summary of the Invention [Problem to be solved by the invention]

[0010] In the compressor 100 equipped with the dehumidifying device 160 described above, the drain generated by condensation caused by cooling of the compressed gas falls into the drain separator 163 provided in the dehumidifying device 160, where it is collected and discharged outside the machine, thereby preventing the drain from being mixed into the compressed gas supplied to the consumer side.

[0011] However, if the flow rate of the compressed gas passing through the dehumidifier 160 becomes excessively high, the drain accumulated in the dehumidifier 160 will be picked up by the compressed gas passing through at high speed and carried along by the flow of the compressed gas, resulting in the inconvenience that the drain that should fall into the drain separator 163 and be collected will not be collected by the drain separator 163 but will instead be mixed into the compressed gas and transported to the consumer side.

[0012] In particular, immediately after starting the compressor 100, when the pressure in the receiver tank (not shown), supply flow path 140, and dehumidification equipment 160 has not yet risen sufficiently, the flow rate of the compressed gas flowing through the supply flow path 140 increases, making it easier for drainage to become mixed into the compressed gas.

[0013] To explain this point in more detail, when the temperature and pressure of the compressed gas sucked into the compressor body remain constant and do not change, and the compressor body continues to operate at full load at the rated rotation speed, the compressor body discharges a fixed amount (fixed volume) of compressed gas per unit time.

[0014] In other words, the compressor body discharges compressed gas at a constant "mass flow rate."

[0015] On the other hand, the "flow velocity" of the compressed gas can be calculated by dividing the "volumetric flow rate" of the compressed gas passing through the measurement position by the flow path area at the measurement position (flow velocity = volumetric flow rate ÷ flow path area).

[0016] Here, the "volumetric flow rate" is the "mass flow rate" divided by the density (volumetric flow rate = mass flow rate ÷ density), so even if the "mass flow rate" is the same for compressed gas, the "volumetric flow rate" will decrease if the pressure (density) increases, and will increase if the pressure (density) decreases.

[0017] For this reason, even if the compressor body discharges compressed gas at a constant "mass flow rate," the "volumetric flow rate" and "flow velocity" of the compressed gas passing through the supply flow path 140, and therefore the dehumidification equipment 160, will increase when the compressed gas discharged from the compressor body passes through the supply flow path 140 at a low pressure (low density) compared to when the compressed gas is passed through the supply flow path 140 at a high pressure (high density) close to the rated pressure.

[0018] Therefore, immediately after starting the compressor 100, when the pressure in the receiver tank, supply flow path 140, and dehumidifier 160 is low, the flow rate of the compressed gas passing through the dehumidifier 160 may become excessively high, and as a result, the drainage accumulated in the dehumidifier 160 may be easily picked up by the compressed gas passing through at high speed and carried out to the consumption side.

[0019] In this way, if the flow rate of the compressed gas flowing through the supply flow path 140 increases excessively, the drain accumulated in the dehumidification equipment 160 will be transported from the consumption side and introduced into an air work machine or the like (not shown), so it is necessary to suppress excessive increases in the flow rate of the compressed gas passing through the supply flow path 140.

[0020] On the other hand, applying resistance that suppresses the speed of the compressed gas passing through the supply passage 140 to a flow rate below a rate at which the drainage accumulated in the dehumidifying equipment 160 is not likely to be stirred up by the compressed gas will result in a decrease in the performance of the compressor 100.

[0021] Therefore, it is desirable that the control for suppressing such flow rate be configured to be activated only when the flow rate of the compressed gas increases to a speed that can lift up the drainage accumulated in the dehumidification equipment 160.

[0022] In the above explanation, an example was given in which the compressor body is an oil-cooled screw compressor, and therefore an example was given in which the compressed gas supply section that supplies compressed gas to the supply flow path is a receiver tank.

[0023] However, the above-mentioned problem can also occur in compressors that do not require a receiver tank in the device configuration, such as oil-free screw compressors that do not require lubricating oil to lubricate and seal the compression working space, and the compressed gas supply section that supplies compressed gas to the supply flow path 140 is not limited to the above-mentioned receiver tank, and can also occur in compressor configurations in which the compressor body is the direct compressed gas supply section to the supply flow path.

[0024] Therefore, the present invention has been made to eliminate the drawbacks of the above-mentioned conventional technology, and aims to provide a condensate mixing prevention structure for a compressor, which can suppress a further increase in flow rate when the flow rate of compressed gas in the supply flow path increases excessively, thereby preventing condensate accumulated in the dehumidifying equipment from mixing with the compressed gas, and therefore preventing the condensate mixed in this way from being transported to the consumer side. [Means for solving the problem]

[0025] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are used to clarify the correspondence between the description of the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0026] In order to achieve the above object, the drain mixing prevention structure of the compressor 1 of the present invention is as follows: In a drain mixing prevention structure for a compressor (1) having a structure in which one end of a supply flow path (40) equipped with a dehumidifying device (60) consisting of an aftercooler (61), a dryer (62), and a flow path connecting these devices is connected to a compressed gas supply part such as a receiver tank (20), and the other end is connected to a consumption side, The flow velocity of the compressed gas in the supply flow path 40 at which the drain accumulated in the dehumidifying device 60 starts to be carried out to the consumption side is determined in advance by an experiment or the like, and a flow velocity lower than the flow velocity by a predetermined margin is set as an upper limit flow velocity, A throttle 70 is provided in the supply flow path 40 on the secondary side of the dehumidifying device 60, The throttle 70 is formed with a flow path area that chokes when the flow velocity of the compressed gas in the supply flow path 40 reaches the upper limit flow velocity (claim 1).

[0027] The throttle 70 is preferably a Venturi tube (see FIG. 3) (claim 2).

[0028] Furthermore, it is preferable that the one end of the supply flow path 40 communicates with the compressed gas supply unit such as the receiver tank 20 via a pressure maintaining valve 30 (claim 3). [Effects of the Invention]

[0029] With the configuration of the present invention described above, the compressor 1 equipped with the drain mixing prevention structure of the present invention can achieve the following significant effects.

[0030] A restrictor 70 is provided in the supply flow path 40 on the secondary side of the dehumidifying equipment 60, and this restrictor 70 is formed with a flow path area that chokes when the flow velocity of the compressed gas in the supply flow path 40 reaches an upper limit flow velocity.As a result, when the flow velocity of the compressed gas in the supply flow path 40 is in a range below the aforementioned upper limit flow velocity, the volumetric flow rate of the compressed gas passing through the restrictor 70 is variable, and the restrictor 70 does not act as a resistance that suppresses the flow velocity of the compressed gas flowing in the supply flow path 40.

[0031] On the other hand, when the flow velocity of the compressed gas in the supply flow path 40 reaches the upper limit flow velocity mentioned above, the flow velocity of the compressed gas passing through the orifice 70 becomes sonic and choked, causing the flow velocity of the compressed gas passing through the orifice 70, and therefore the volumetric flow rate of the compressed gas passing through the orifice 70, to plateau and no longer increase.

[0032] As a result, the flow rate of the compressed gas passing through the dehumidifying device 60 on the primary side of the restrictor 70 was also prevented from rising above the upper limit flow rate mentioned above.

[0033] Here, the aforementioned "upper limit flow rate" is set as a flow rate that is a predetermined margin lower than the flow rate of the compressed gas in the supply flow path 40 at which the condensate accumulated in the dehumidifier 60 begins to be rolled up, which has been determined in advance through experiments, etc., and therefore the choke created by the orifice 70 suppresses the flow rate of the compressed gas in the supply flow path 40 so that it does not exceed this "upper limit flow rate," thereby effectively preventing the condensate accumulated in the dehumidifier 60 from mixing with the compressed gas and being transported from the consumption side.

[0034] In the configuration in which the aforementioned orifice 70 is a Venturi tube, the pressure loss of the compressed gas that occurs when passing through the orifice (Venturi tube) 70 can be significantly reduced compared to when the orifice is configured as an orifice (not shown) or the like.

[0035] Furthermore, in a configuration in which one end of the supply flow path 40 is connected to a compressed gas supply section such as the receiver tank 20 via the pressure maintaining valve 30, the pressure maintaining valve 30 also functions as a check valve, so that even if the pressure in the compressed gas supply section such as the receiver tank 20 drops due to the compressor being stopped, it is possible to prevent the compressed gas in the supply flow path 40 from flowing back to the compressed gas supply section, and to prevent the drain of the dehumidification equipment 60 from being introduced into the compressed gas supply section along with this backflowing compressed gas. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is an explanatory diagram of a compressor equipped with a drain mixing prevention structure of the present invention. [Figure 2] 10 is an explanatory diagram of a modified example of a compressor equipped with a drain mixing prevention structure of the present invention. [Figure 3] Cross-sectional diagram of a venturi tube. [Figure 4] FIG. 1 is an explanatory diagram of a conventional compressor equipped with a dehumidifying device. DETAILED DESCRIPTION OF THE INVENTION

[0037] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0038] [Overall configuration of compressor] The symbol 1 in Figure 1 is a compressor equipped with the drain mixing prevention structure of the present invention, and this compressor 1 comprises a compressor main body 10, a driving source such as an engine or motor (not shown) that drives the compressor main body 10, and a receiver tank 20 that stores compressed gas discharged from the compressor main body 10, and is configured so that the compressed gas discharged from the compressor main body 10 can be stored in the receiver tank 20 and then supplied to an air work machine or the like (not shown) connected to the consumption side via a pressure maintenance valve 30 and a supply flow path 40.

[0039] In this embodiment, the compressor body 10 is an oil-cooled screw-type compressor body 10 that compresses the gas to be compressed together with lubricating oil for lubrication, cooling, and sealing, and the compressed gas discharged by the compressor body 10 as a gas-liquid mixed fluid with the lubricating oil is introduced into the receiver tank 20 via the discharge flow path 12, and the receiver tank 20 is configured so that the lubricating oil can be separated, and the lubricating oil recovered in the receiver tank 20 can be supplied to the compression working space via the oil supply flow path 22 and the oil supply port 13 provided in the compressor body 10.

[0040] Furthermore, the compressor body 10 provided in the compressor 1 targeted by the present invention is not limited to such an oil-cooled type, but may also be an oil-free compressor body that does not require lubricating oil to compress the gas to be compressed, in which case the aforementioned receiver tank 20 and the oil supply passage 22 for supplying the lubricating oil recovered in the receiver tank 20 to the compressor body 10 can be omitted.

[0041] [Intake adjustment device] The compressor body 10 of the compressor 1 configured as described above is provided with an intake control valve 51 that controls the opening and closing of the intake port, and an intake adjustment device 50 that performs intake adjustment by throttling or closing this intake control valve 51 when the secondary side pressure of the compressor body 10, in this embodiment the pressure in the receiver tank 20, approaches a predetermined rated pressure, and by fully opening the intake control valve 51 when the pressure in the receiver tank 20 falls below the rated pressure.

[0042] In the illustrated embodiment, a control flow path 52 is provided that connects the receiver tank 20 and the closed valve pressure chamber of the intake control valve 51, and an on-off valve 53, which is an electromagnetic control valve, is provided to open and close this control flow path 52, and the aforementioned intake adjustment device 50 is provided, which is composed of the intake control valve 51, the control flow path 52, and the on-off valve 53.

[0043] In this embodiment, the receiver tank 20 is provided with a pressure detection means (not shown) that detects the pressure within the receiver tank 20, and when this pressure detection means detects that the pressure within the receiver tank 20 has reached the aforementioned rated pressure, it opens the on-off valve 53 to introduce compressed gas within the receiver tank 20 into the closed-valve pressure chamber of the intake control valve 51, thereby throttling or closing the intake control valve 51, and when it detects that the pressure within the receiver tank 20 has fallen below the rated pressure, it closes the on-off valve 53 to stop the introduction of compressed gas into the closed-valve pressure chamber of the intake control valve 51, thereby closing the intake control valve 51, thereby controlling the pressure within the receiver tank 20 to approach the aforementioned rated pressure.

[0044] The intake adjustment device 50 provided in the compressor 1 is not limited to the example shown in the figure, and it is possible to adopt intake adjustment devices of various known configurations.

[0045] [Supply Channel] One end of a supply passage 40 is connected to the receiver tank 20 of the compressor 1 described above via an oil separator 21 and a pressure maintaining valve 30, and the other end of this supply passage 40 is connected to the consumption side.

[0046] This allows the compressed gas generated by the compressor main body 10 and introduced into the receiver tank 20 to be supplied to an air work machine (not shown) connected to the consumption side via the pressure maintaining valve 30 and the supply flow path 40 after the oil has been removed by the oil separator 21.

[0047] This supply flow path 40 is provided with a dehumidifying device 60 so that moisture contained in the compressed gas passing through the supply flow path 40 can be removed, thereby enabling dry compressed gas to be supplied to the consumption side.

[0048] The aforementioned pressure maintaining valve 30 opens and begins introducing compressed gas into the supply flow path 40 when the primary pressure of the pressure maintaining valve 30, in the illustrated example the pressure in the receiver tank 20, exceeds the activation pressure of the pressure maintaining valve 30 (0.4 MPa as an example in this embodiment), and closes and stops introducing compressed gas into the supply flow path 40 when the pressure is below the aforementioned activation pressure.This allows compressed gas at or above the activation pressure of the pressure maintaining valve 30 to be introduced into the supply flow path 40 and the dehumidification equipment 60, and by maintaining the pressure in the receiver tank 20 at or above the activation pressure of the pressure maintaining valve 30, the pressure in the receiver tank 20 can be used to supply lubricating oil in the receiver tank 20 to the compressor main body 10.

[0049] In addition, this pressure-retaining valve 30 also functions as a check valve that prevents the compressed gas from flowing back from the supply flow path 40 toward the receiver tank 20, thereby preventing the compressed gas in the supply flow path 40 from flowing back into the receiver tank 20 together with the drainage accumulated in the dehumidification equipment 60 described below that is installed in the supply flow path 40 when purging is performed to release the compressed gas in the receiver tank 20 when the compressor 1 is stopped and being introduced into the receiver tank 20.

[0050] The dehumidifying device 60 is not limited to the combination shown in the figure, and various known dehumidifying devices can be combined and used.

[0051] As an example, in the embodiment shown in Figure 1, the dehumidification equipment 60 is composed of an aftercooler 61 that cools the compressed air from the receiver tank 20, a dryer (refrigerated dryer) 62 that further cools the compressed air after passing through this aftercooler 61 and condenses and removes the moisture in the compressed air, and a flow path that connects the aftercooler 61 and the dryer 62.

[0052] In this embodiment, the drain generated by condensation during cooling by the aftercooler 61 is introduced into the dryer 62 together with the compressed gas, and is simultaneously collected in a drain trap (not shown) provided in the dryer 62 together with the drain generated during cooling in the dryer 62.

[0053] The drain collected in the drain trap (not shown) of this dryer 62 is introduced into a drain treatment device 625 such as a drain dryer via a drain pipe 621 connected at one end to the drain trap, and after the oil contained in the drain is removed in this drain treatment device 625, the drain is discharged outside the machine as clean water (drain water).

[0054] The aforementioned drain piping 621, which connects the drain trap (not shown) of the dryer 62 to the drain treatment device 625, is provided with a stop valve 622 for opening and closing the drain piping 621, and a strainer 623 and an electromagnetic opening / closing valve 624 are provided on the secondary side of the stop valve 622.

[0055] By configuring the drain piping 621 for the dryer 62 in this manner, when the electromagnetic on-off valve 624 is opened with the stop valve 622 open, the drain accumulated in the drain trap of the dryer 62 is pushed by the pressure of the compressed air in the supply flow path 40 and sent to the drain treatment device 625 via the drain piping 621.

[0056] In the illustrated embodiment, the drain generated in the aftercooler 61 is described as being collected together in the dryer 62, but it is also possible to provide a separate drain trap in the aftercooler 61 to collect the drain generated in the aftercooler 61, and to provide a separate drain pipe having a structure similar to the drain pipe 621 for the dryer 62 described above, which connects this drain trap to the drain treatment device 625.

[0057] Furthermore, in the embodiment shown in Figure 1, an example is shown in which the dehumidifying equipment 60 is configured by an aftercooler 61, a dryer 62, and a flow path connecting these, but in addition to the configuration shown in Figure 1, the dehumidifying equipment 60 may also be configured by an aftercooler 61, a drain separator 63 that collects drainage caused by condensation due to cooling by the aftercooler 61, an afterwarmer 64 that heats the compressed gas after the drainage has been removed by the drain separator 63 to reduce the relative humidity, and a flow path connecting each of these devices, as shown in Figure 2.

[0058] In the embodiment shown in Figure 2, when the water level of the drain collected in the drain separator 63 rises above a certain level, the float valve 632 opens, and the drain accumulated in the drain separator 63 is discharged outside the machine through the drain pipe 631 and a silencer 633 attached to the tip of the drain pipe 631 by the pressure of the compressed gas in the supply flow path 40.

[0059] In the embodiment shown in Figures 1 and 2, the dehumidifier 60 is configured to selectively include a dryer 62 (see Figure 1) or an afterwarmer 64 (see Figure 2) in addition to the aftercooler 61. However, the configuration of the dehumidifier 60 shown in Figure 1 may also be further configured with an afterwarmer 64 that heats the compressed gas after passing through the dryer 62. The configuration of the dehumidifier 60 is not limited to the configuration shown in the figures, and various known configurations can be adopted.

[0060] [Drain contamination prevention structure] The aforementioned supply flow path 40 further has a restrictor 70 on the secondary side of the aforementioned dehumidification equipment 60, which prevents the flow rate of the compressed gas in the supply flow path 40 from increasing beyond a predetermined upper limit rate.

[0061] The drainage that condenses during cooling in the dehumidifying equipment 60 described above falls into a drainage separator (not shown) (see Figure 1) provided on the dryer 62 on the secondary side of the aftercooler 61 in the embodiment of Figure 1, or into a drainage separator 63 (see Figure 2) provided on the secondary side of the aftercooler 61 in the embodiment of Figure 2, and is collected, thereby preventing the drainage from mixing with the compressed gas supplied to the consumer side.

[0062] However, if the flow rate of the compressed gas in the supply flow path 40, and therefore the flow rate of the compressed gas passing through the dehumidification equipment 60 (particularly the dryer 62 in the example of Figure 1, and the drain separator 63 in the example of Figure 2), increases excessively, the flow of this compressed gas will pick up the drain that is about to fall into the drain separator (not shown) provided on the dryer 61 in the example of Figure 1, or the drain separator 63 in the example of Figure 2, resulting in the generation of drain that is not recovered in the drain separator but is carried along with the flow of compressed gas and carried to the consumer side together with the compressed gas.

[0063] Therefore, in the present invention, the level at which the flow rate of the compressed gas in the supply flow path 40 must increase before drainage to the consumption side occurs is determined in advance through experiments, etc., and an "upper limit flow rate" is set that is a flow rate that is a predetermined margin lower than the flow rate at which such drainage occurs.

[0064] When the flow velocity of the compressed gas in the supply flow path 40 reaches this "upper limit flow velocity," the flow path area of ​​the aforementioned orifice 70 provided on the secondary side of the dehumidification equipment 60 is designed so that the flow velocity of the compressed gas passing through the orifice 70 becomes sonic and chokes, thereby preventing the flow velocity in the supply flow path 40 from rising above the aforementioned upper limit flow velocity.

[0065] The restrictor 70 may be an orifice (not shown) which can be manufactured relatively easily, but it is preferable to use a Venturi tube as shown in FIG.

[0066] As shown in Figure 3, this Venturi tube 70 is formed by first narrowing the flow path and then gradually expanding it again.Although its structure is more complex and expensive than an orifice, it is preferable in that it can keep pressure loss lower than an orifice.

[0067] [Effect, etc.] When the compressor 1 configured as described above is started, the pressure in the receiver tank 20, supply flow path 40, and dehumidification equipment 60 drops to atmospheric pressure at the time of start-up, so the compressor main body 10 operates at full load with the intake control valve 51 fully open, and discharges compressed gas into the receiver tank 20 at a constant "mass flow rate."

[0068] Thereafter, when the pressure inside the receiver tank 20 reaches the pressure at which the pressure holding valve 30 starts to operate (for example, 0.4 MPa), the pressure holding valve 30 starts to open and the introduction of compressed gas into the supply flow path 40 and the dehumidification equipment 60 begins.

[0069] Thus, at the initial start-up of the compressor 1, the pressure of the compressed gas introduced into the supply flow path 40 and the dehumidification equipment 60 is the pressure at which the pressure-retaining valve 30 starts to operate (for example, 0.4 MPa) or slightly higher than this, and is sufficiently lower than the rated pressure (for example, 0.8 MPa).

[0070] Therefore, even if the "mass flow rate" of the compressed gas discharged from the compressor main body 10 is constant, the "volumetric flow rate" and "flow velocity" of the compressed gas will be significantly higher when passing through the supply flow path 40 and dehumidification equipment 60 at a pressure close to the activation start pressure of the pressure retention valve 30 (for example, 0.4 MPa) than when passing through the supply flow path 40 and dehumidification equipment 60 at the rated pressure (for example, 0.8 MPa).

[0071] However, even if the flow rate of the compressed gas in the supply flow path 40 or the dehumidifier 60 increases, when this flow rate reaches a preset upper limit flow rate, the flow rate of the compressed gas passing through the orifice 70 provided on the secondary side of the dehumidifier 60 reaches the speed of sound and chokes.

[0072] Due to the occurrence of this choking, the flow velocity and volumetric flow rate of the compressed gas passing through the orifice 70 cannot increase any further and reach a plateau, and as a result, the flow velocity and volumetric flow rate of the compressed gas passing through the dehumidifying device 60 installed on the primary side of the orifice 70 also reach a plateau.

[0073] As mentioned above, the upper limit flow rate is set to a flow rate that is lower by a certain margin than the flow rate of the compressed gas in the supply flow path 40 at which the condensate in the dehumidifying equipment 60 begins to be rolled up. Therefore, by providing the restrictor 70 that chokes under the conditions mentioned above, the flow rate of the compressed gas in the supply flow path 40 is suppressed to below the upper limit flow rate, thereby preventing the condensate accumulated in the dehumidifying equipment 60 from being transported out from the consumption side.

[0074] On the other hand, as the compressor main body 10 continues to discharge compressed gas, the pressure inside the receiver tank 20 increases, and the pressure of the compressed gas introduced to the consumption side via the supply flow path 40 and the dehumidification equipment 60 also increases.

[0075] Therefore, even if the compressor main body 10, which continues to operate at full load, continues to discharge compressed gas at a constant mass flow rate since startup, the volumetric flow rate of compressed gas passing through the supply flow path 40 and dehumidification equipment 60 decreases, and the flow rate also decreases.

[0076] When this decrease in flow velocity causes the flow velocity of the compressed gas passing through the supply passage 40 to fall below the upper limit flow velocity mentioned above, the flow velocity of the compressed fluid passing through the orifice 70 falls to a velocity below subsonic speed, the choked state is eliminated, and the orifice 70 no longer functions as a resistance to suppress the flow velocity of the compressed gas in the supply passage 40.

[0077] In this way, the compressed gas introduced into the supply flow path 40 from the receiver tank 20 passes through the dehumidifier 60 to be dehumidified, and then the drainage produced in the dehumidifier 60 is reliably removed, and dry compressed gas without any drainage mixed in is supplied to the consumption side. [Explanation of symbols]

[0078] 1 Compressor 10 Compressor body 12 Discharge flow path 13 Fuel filler 20 Receiver tank (compressed gas supply section) 21 Oil separator 22 Oil supply passage 30 Pressure maintaining valve 40 supply channel 50 Intake adjustment device 51 Intake control valve 52 Control Channel 53 On-off valve (solenoid on-off valve) 60 Dehumidification equipment 61 Aftercooler 62 Dryer (refrigerated dryer) 621 Drain piping 622 Stop valve 623 Strainer 624 Solenoid valve 625 Drain treatment equipment 63 Drain separator 631 Drain piping 632 Float Valve 633 silencer 64 Afterwarmer 70 Constriction (Venturi tube) 100 compressor 121 Oil separator 140 supply channel 160 Dehumidification equipment 161 Aftercooler 163 Drain separator 163b Drain piping

Claims

1. In a drain mixing prevention structure for a compressor having a structure in which one end of a supply flow path equipped with a dehumidifying device that dehumidifies compressed gas is connected to a compressed gas supply part and the other end is connected to a consumption side, a flow velocity of the compressed gas in the supply flow path at which the drain accumulated in the dehumidifying device starts to be carried out to the consumption side is determined in advance, and a flow velocity that is lower than the flow velocity by a predetermined margin is set as an upper limit flow velocity; A throttle is provided in the supply flow path on the secondary side of the dehumidifier, A drainage mixing prevention structure for a compressor, characterized in that the throttle is formed with a flow path area that chokes when the flow velocity of the compressed gas in the supply flow path reaches the upper limit flow velocity.

2. 2. The compressor according to claim 1, wherein the throttle is a Venturi tube.

3. 3. The structure for preventing drainage from entering a compressor according to claim 1, wherein the one end of the supply passage is connected to the compressed gas supply section via a pressure maintaining valve.

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