JP2013104327A - Water-injected screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply drain from a dehumidifier into a compressor body without reducing suction efficiency, and also extend a service life of a lip seal provided at a suction side rotor shaft.SOLUTION: A water-injected screw compressor includes a compressor body 1, an air-water separator 6 separating compressed air and water, ejection passages 19a, 19b leading the compressed air from the air-water separator, body water supply passages 7, 9, 9a returning the water separated by the air-water separator to the compressor body, a dehumidifier 21 provided at the ejection passage, and a drain discharge passage 22 discharging the drain subjected to condensation separation by the dehumidifier. A partition wall 28 is provided at a casing 1A between a lip seal 29 provided at a suction side rotor shaft 3B of the compressor body and a suction side end surface of a rotor tooth part 3A. An axially sealed water injection channel 26 is provided in the partition wall. The drain discharge passage is connected to the axially sealed water injection channel, and the drain is supplied between the lip seal and the suction side end surface of the rotor tooth part.

Description

  The present invention relates to a water injection type screw compressor in which water is injected into a compressor main body so as to perform sealing and cooling in a compression operation space.

  Conventionally, a water injection screw compressor (also referred to as a water lubricated screw compressor) in which water is injected into the compressor body to seal and cool the compression working space is known. Such a water-injection screw compressor is characterized in that the compression efficiency can be increased without including oil in the compressed air.

  As this kind of prior art, there are those described in Japanese Patent No. 3008933 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2009-162129 (Patent Document 2).

  The thing of the said patent document 1 can carry out continuous operation for a long time without replenishing water, and also reduces the impurity concentration of circulating water and cleans for a long time, without using a pure water device or a water purification apparatus. A water-injection type screw compressor that can be maintained at the same level is disclosed. Moreover, the thing of this patent document 1 also discloses the water quality management method which can suppress the propagation of bacteria and reduce the amount of bacteria in circulating water without exchanging circulating water.

  In Patent Document 2, a lip is provided between a suction flow path for sucking a target gas into a rotor chamber that houses a screw rotor that engages male and female, and a bearing that supports a rotor shaft on the suction side of the screw rotor. A seal is provided, and a gap between the partition between the suction flow path and the lip seal and the rotor shaft is 0.5 mm or more, and a lubricating fluid is introduced between the lip seal and the partition. A water jet screw compressor is disclosed in which a lubrication space is formed and a lubrication flow path for introducing a lubrication fluid into the lubrication space is provided. With this configuration, it is described that even if dust enters the periphery of the lip seal, the dust is not discharged into the suction flow path and the life of the lip seal is not shortened.

Japanese Patent No. 3008933 JP 2009-162129 A

  In the thing of the said patent document 1, the check valve which discharges the compressed air which was provided in the water outlet of the said water tank, and was provided in the air outlet of the said water tank, and the water | moisture content was removed by the said steam / water separator, A dehumidifier that condenses and separates the moisture by cooling the compressed air exiting the water tank against the check valve to a moisture saturation temperature or lower, and the air separated from the dehumidifier together with the air of the compressor It has a water recovery line that supplies directly to the suction port. However, in this Patent Document 1, since the water separated by the dehumidifier is directly supplied to the air intake port (air introduction line) of the compressor together with the air, the water directly supplied to the air intake port ( Drain) or the like obstructs the flow of intake air and causes suction resistance. For this reason, the pressure loss at the time of inhaling air increases and there exists a subject that inhalation efficiency falls.

  In addition, in Patent Document 1, the life of a low-pressure side shaft seal device (lip seal or the like) provided between the screw rotor and the bearing that supports the suction-side rotor shaft is prevented from being shortened. No consideration is given to this.

  The above-mentioned Patent Document 2 describes that even if dust enters the periphery of the lip seal, the dust is discharged into the suction passage so that the life of the lip seal is not shortened. It is described that the cooling water from which the water is removed is introduced into the lubrication space through the lubrication flow path. However, the filter can remove only foreign substances having a certain size or larger. For example, an ion exchange resin or the like is used as a component indicating water hardness such as calcium ion or magnesium ion, and a component such as ionic silica. It cannot be removed without using a pure water purifier. For this reason, components contained in the cooling water supplied to the lubrication flow path and the lubrication space are deposited in the lubrication flow path and the lubrication space over time and become solid matter, and the solid matter becomes the lip seal. There is a problem of damaging or excessive wear.

  An object of the present invention is to supply drain (water) separated by a dehumidifier into the compressor main body without lowering the suction efficiency of the compressor main body, and to support a rotor shaft on the suction side and a screw An object of the present invention is to obtain a water jet screw compressor capable of extending the life of a low pressure side shaft seal device provided between the rotor and the rotor.

  To achieve the above object, the present invention relates to a screw rotor having a rotor tooth portion, a suction side rotor shaft provided on the suction side of the rotor tooth portion, and a discharge side rotor shaft provided on the discharge side of the rotor tooth portion. A casing that houses the screw rotor, a bearing that is provided in the casing and supports the suction-side rotor shaft and the discharge-side rotor shaft, a bearing that supports the suction-side rotor shaft, and a suction side of the rotor tooth portion A compressor body having a low-pressure side shaft seal device provided in the casing so as to seal between the end faces, an air-water separator for separating compressed air and water discharged from the compressor body, and the air A discharge path for guiding compressed air separated by the water separator, a main body water supply path for returning the water separated by the steam separator to the compressor body, and the compressed air separated by the steam separator A water injection screw provided with a dehumidifier that is provided in a discharge path that leads and condenses and separates water vapor contained in compressed air as drain, and a drain discharge path that discharges the drain condensed and separated by the dehumidifier from the dehumidifier In the compressor, a partition provided in the casing between the low pressure side shaft seal device and the suction side end surface of the rotor tooth portion, and partitions between the low pressure side shaft seal device and the suction side end surface of the rotor tooth portion. And a shaft sealing water passage for supplying water between the low pressure side shaft sealing device and the suction side end surface of the rotor tooth portion, and the drain discharge path is formed in the partition wall. It is connected to the irrigation channel.

  According to the present invention, the drain separated by the dehumidifier is supplied into the compressor main body without reducing the suction efficiency of the compressor main body, and the screw rotor and the bearing that supports the rotor shaft on the suction side are provided. A water jet screw compressor that can extend the life of the low-pressure side shaft seal device provided therebetween can be obtained.

It is a systematic diagram which shows Example 1 of the water injection type screw compressor of this invention. It is sectional drawing which expands and shows the principal part of the compressor main body shown in FIG. It is a systematic diagram which shows Example 2 of the water injection type screw compressor of this invention.

  Hereinafter, specific examples of the water jet screw compressor of the present invention will be described with reference to the drawings. In addition, the part which attached | subjected the same code | symbol in each figure has shown the part which is the same or it corresponds.

  A first embodiment of the water injection screw compressor of the present invention will be described with reference to FIGS. FIG. 1 is a system diagram showing a first embodiment of a water-injection screw compressor according to the present invention, and FIG.

  In FIG. 1, reference numeral 1 denotes a compressor main body. The compressor main body 1 contains a screw rotor 3 in its casing 1A, and is provided with a motor 2 for rotationally driving the screw rotor 3. Yes. The screw rotor 3 includes a rotor tooth portion 3A, a suction side rotor shaft 3B provided on the suction side of the rotor tooth portion 3A, a discharge side rotor shaft 3C provided on the discharge side of the rotor tooth portion 3A, and the like. Has been.

The casing 1A includes a suction portion 5 for sucking external air through a suction valve (not shown) at a position corresponding to the suction side of the rotor tooth portion 3A, and the rotor tooth portion 3A. A discharge unit 50 for discharging compressed air is provided.
In the casing 1A, a bearing 30 for rotating and supporting the suction side rotor shaft 3B of the screw rotor 3 and bearings 31 to 33 for rotating and supporting the discharge side rotor shaft 3C of the screw rotor 3 are provided. . The bearings 30 and 31 are constituted by, for example, roller bearings, and the bearings 32 and 33 are constituted by angular ball bearings so as to support a thrust force acting on the rotor shafts 3B and 3C.

  A low pressure side shaft seal device 29 is provided in the casing 1A so as to seal between the bearing 30 that supports the suction side rotor shaft 3B and the suction side end surface of the rotor tooth portion 3A. The low-pressure side shaft seal device 29 is constituted by a lip seal in this embodiment. Further, a high pressure side shaft seal device 37 is provided in the casing 1A so as to seal between the bearings 31 to 33 that support the discharge side rotor shaft 3C and the discharge side end face of the rotor tooth portion 3A. The high-pressure side shaft seal device 37 is constituted by a mechanical seal in this embodiment.

  In this embodiment, the screw rotor 3 is composed of a pair of male and female screw rotors. For example, when the male screw rotor is driven to rotate by the motor 2, the female screw is connected via the timing gear 4. The rotor is also driven to rotate. At this time, the male screw rotor and the female screw rotor are rotated in a non-contact manner while maintaining a minute gap therebetween. Thus, air is sucked from the suction part 5 and compressed, and is discharged from the discharge part 50.

  In the water injection type screw compressor, by injecting water into the compression working space formed by the rotor tooth portion 3A composed of a pair of male and female screw rotors, leakage of compressed air in the compression working space is limited. At the same time, the compression heat of the air is cooled to prevent the screw rotor 3 from being seized.

The bearings 30 to 33 are configured to be lubricated with oil in this embodiment. That is, in this embodiment, an oil sump 47 is formed in the casing 1A so as to communicate with the bearing 30, and an oil sump 48 is formed so as to communicate with the bearings 31-33.
The oil in the oil reservoir 47 is splashed up by a spring-up member 38 fixed to the suction side rotor shaft 3 </ b> B and supplied to the bearing 30. An oil seal 34 is provided so that oil supplied to the bearing 30 does not leak to the rotor tooth portion 3A side. An oil seal 35 is provided so that the oil splashed by the splashing member 38 does not leak to the motor 2 side.
The oil in the oil reservoir 48 is splashed up by the timing gear 4 and supplied to the bearings 31 to 33. An oil seal 36 is provided so that oil supplied to the bearings 31 to 33 does not leak to the rotor tooth portion 3A side.

  On the other hand, the low pressure side shaft seal device (lip seal) 29 is in contact with the suction side rotor shaft 3B to form a sliding surface, thereby injecting the air sucked from the suction portion 5 and the compression working space. The generated water is prevented from leaking to the bearing 30 side, and the high-pressure side shaft seal device (mechanical seal) 37 prevents compressed air and water from leaking to the bearings 31 to 33 side.

  A steam / water separator 6 is provided on the discharge side of the compressor body 1, and the steam / water separator 6 includes compressed air discharged from the discharge portion 50 of the compressor body 1 and water contained therein. Are separated from each other. The steam separator 6 also has a function as a tank for storing water.

  The water separated by the steam / water separator 6 is once stored in the lower part of the steam / water separator 6, and then the main water supply path 7, 9 and 9a are returned to the compressor body 1. That is, the water separated by the steam separator 6 is sent to the water cooler 8 through the water supply pipe 7 constituting the main body water supply path and cooled, and the water cooled by the water cooler 8 is supplied to the main body water supply water. After the impurities are removed by the water filter 10 through the main body water supply pipe 9 constituting the path, the vicinity of the rotor tooth portion 3A via the main body water supply path 9a formed in the casing 1A of the compressor main body 1 It is comprised so that it may be injected. A main body water supply valve 11 is provided in the main body water supply pipe 9 on the downstream side of the water filter 10. The water cooler 8 cools the water sent from the steam separator 6 with cooling air from the cooling fan 12.

  Reference numeral 13 denotes an external water supply pipe for supplying water to the compressor body 1 from the outside when the compressor body 1 is in operation and the amount of water stored in the steam separator 6 is reduced. This is the piping. That is, an operating water supply valve 15 is provided in the middle of the external water supply pipe 13, and its downstream end is connected to a main body water supply hole 9b formed in the casing 1A of the compressor main body 1, so By opening the water valve 15, external water can be injected into the compressor body 1 via the external water supply pipe 13.

  Reference numeral 14 denotes a stop-time water supply pipe branched from the upstream side of the operation-time water supply valve 15 in the external water supply pipe 13. When the amount of water stored in 6 is decreasing, this steam / water separator 6 is a pipe for replenishing water from the outside. That is, the downstream side of the stop-time water supply pipe 14 is connected to the upstream side of the main body water supply valve 11 of the main body water supply pipe 9, and the stop-time water supply pipe 14 is provided with a stop-time water supply valve 16. When the compressor main body 1 is stopped (the main body water supply valve 11 is closed at this time), the stop-time water supply valve 16 is opened, so that water from the external water supply pipe 13 is supplied to the stop-time water supply pipe 14, It is configured so that it can be supplied to the steam / water separator 6 via the main body water supply pipe 9, the water cooler 8 and the water supply pipe 7.

  A drain pipe 17 connects the bottom of the steam / water separator 6 to the outside. The drain pipe 17 is provided with a drain valve 18. By opening the drain valve 18, the steam / water separator 6 has a drain pipe 18. The water collected in can be discharged to the outside. Thereby, the fall of the separation efficiency by a large amount of water accumulating in the steam-water separator 6 can be prevented.

  Compressed air discharged from the compressor body 1 and entering the steam / water separator 6 from the discharge path 19 where water has been separated is discharged from the steam / water separator 6 and then discharged to the discharge path (discharge pipe) 19a. The dehumidifier 21 is sent to the dehumidifier 21 and dehumidified by the dehumidifier 21, and then supplied to the customer from the discharge path (discharge pipe) 19 b. The discharge passage 19a is provided with a check-function holding pressure valve 20 in which compressed air flows only in the discharge direction and has a pressure holding function. Instead of the pressure retaining valve with check function 20, a check valve and a pressure retaining valve may be provided separately.

  The water vapor contained in the compressed air flowing into the dehumidifier 21 is separated as drain by the dehumidifier 21, and the separated drain passes through the drain discharge path (drain pipe) 22 from the dehumidifier 21. Further, it is injected between the low pressure side shaft sealing device (lip seal) 29 and the suction side end surface of the rotor tooth portion 3A through a shaft sealing water passage 26 provided in the casing 1A of the compressor body 1. .

  That is, the casing 1A between the low pressure side shaft seal device 29 and the suction side end surface of the rotor tooth portion 3A has a space between the low pressure side shaft seal device 29 and the suction side end surface of the rotor tooth portion 3A. A partition wall 28 is provided, and the shaft sealing water channel 26 for supplying water between the low pressure side shaft seal device 29 and the suction side end face of the rotor tooth portion 3A is formed in the partition wall 28. Has been. The drain discharge path 22 is connected to the shaft sealing water passage 26, and the drain generated by the dehumidifier 21 is injected between the low pressure side shaft sealing device 29 and the suction side end face of the rotor tooth portion 3A. The sliding surface of the lip seal constituting the low pressure side shaft seal device 29 is lubricated and the drain can be directly supplied to the rotor tooth portion 3A. The low-pressure side shaft seal device 29 also functions to suppress leakage of the supplied drain to the oil seal 34 side.

  On the drain discharge path (drain pipe) 22, a strainer 23 for removing impurities, a drain discharge valve 24 that opens and closes at a certain time interval, and a reverse for preventing the backflow of drain and air from the compressor body 1. The stop valve 25 is provided with an orifice 39 for reducing the pressure of the drain discharged from the dehumidifier 21 at a pressure close to the discharge air pressure (for example, about 0.7 MPa (G)).

  The drain discharge valve 24 has a preset opening / closing frequency so as to open, for example, every 60 seconds for 1 second. Alternatively, when a sensor for detecting the humidity of the surrounding atmosphere is provided, and the detected humidity value exceeds a certain level, the drain discharge valve 24 is frequently opened and closed (for example, opened every 30 seconds for 1 second). You may control so that it may become.

FIG. 2 is an enlarged sectional view showing the periphery of the low pressure side shaft seal device 29 in FIG.
As shown in FIG. 2, the shaft sealing water channel 26 is formed in a partition wall 28 that partitions between the low pressure side shaft sealing device 29 and the suction side end face of the rotor tooth portion 3A. The drain (condensed water) guided from the path 22 to the shaft sealing water path 26 is injected into a radial gap 40 formed between the inner peripheral surface of the partition wall 28 and the outer peripheral surface of the suction side rotor portion 3B. Is done. The radial gap 40 is formed over the entire circumference in the circumferential direction of the suction side rotor shaft 3B, and the drain injected into the radial gap 40 flows in the circumferential direction and is configured by a lip seal or the like. The sliding surface between the low pressure side shaft seal device 29 and the suction side rotor shaft 3B is configured to be lubricated and cooled.

  The radial gap 40 formed between the partition wall 28 and the suction side rotor shaft 3B is configured to be larger than the axial gap 41 formed between the partition wall 28 and the rotor tooth portion 3A. . As a result, the drain injected into the radial gap 40 from the shaft sealing water channel 26 can easily flow in the circumferential direction of the low pressure side shaft sealing device 29, and the low pressure side shaft sealing device 29 configured by a lip seal slides. The surface can be effectively lubricated and cooled.

  Further, since the drain injected into the radial space 40 then flows directly into the tooth groove of the rotor portion 3A from the axial gap 41, the flow of air sucked from the suction portion 5 is not hindered. For this reason, the drain can be supplied into the compressor main body without reducing the suction efficiency of the compressor main body 1 by injecting the drain (moisture).

  Further, since the drain discharged from the dehumidifier 21 is close to pure water and has few impurities, water such as calcium ions and magnesium ions is more than that when normal tap water is injected from the shaft sealing water channel 26. The component which shows the hardness of this, and also components, such as an ionic silica, are hardly contained. For this reason, it can suppress that a solid substance precipitates in the said radial space 40 grade | etc.,. Therefore, it is possible to prevent the lip seal constituting the low-pressure side shaft seal device 29 from being damaged or excessively worn by the precipitated solid matter. In addition, even if solid matter is deposited, it is negligible. By injecting drain into the vicinity of the lip seal (low pressure side shaft seal device) 29, solid matter such as silica and wear powder such as lip seal can be washed away. Therefore, the life of the low-pressure side shaft seal device 29 composed of a lip seal or the like can be extended.

  The drain injected into the radial gap 40 flows slightly to the oil seal 34 side after lubricating the low-pressure side shaft seal device 29, but then flows into the atmosphere from the discharge passage 49 formed in the casing 1A. To be discharged.

  In this embodiment, by providing the orifice 39 in the middle of the drain discharge path 22, the pressure of the relatively high-pressure drain close to the pressure of the discharge air is reduced to, for example, 0.1 MPa (G) or less, Although the sliding surface pressure of the low-pressure side shaft seal device 29 configured by a lip seal or the like is prevented from increasing, instead of providing the orifice 39, the hole diameter of the shaft seal water channel 26 is set as follows: By making the diameter of the drain pipe (drain discharge path) 22 sufficiently smaller, the same effect as that obtained when the orifice 39 is provided may be obtained.

  A second embodiment of the water jet screw compressor of the present invention will be described with reference to FIG. FIG. 3 is a system diagram for explaining the water-injection screw compressor according to the second embodiment. The same reference numerals as those in FIGS. 1 and 2 denote the same or corresponding parts, and the same parts are explained. Is omitted. Hereinafter, the parts of the second embodiment that are different from the first embodiment will be described.

  In this embodiment, a drain branch pipe 27 is branched from between a check valve 25 and an orifice 39 of a drain pipe (drain discharge path) 22, and a drain trap 42 is provided in the drain branch pipe 27. A drain discharge pipe 45 for discharging the drain to the outside is connected to the drain trap 42.

  In a season with high humidity, or in a place with high humidity, the amount of drain generated in the dehumidifier 21 increases, and the dehumidifier 21 is larger than the amount of drain injected into the compressor body from the shaft sealing water channel 26. When the amount of the drain generated in the flow increases, surplus drain flows from the drain branch pipe 27 into the drain trap 42 and is stored. A float 43 and a valve 44 linked to the float 43 are provided inside the drain trap 42. When a preset amount of drain is stored in the drain trap 42, the position of the float 43 is changed. The valve 44 is opened in conjunction with the initial position. Thereby, the drain stored in the drain trap 42 is discharged to the outside from the drain discharge pipe 45.

  According to the present embodiment, the same effect as in the first embodiment can be obtained, and further, the drain trap 42 is provided as described above, so that the amount of drain generated in the dehumidifier 21 is large, and the compressor Even when water cannot be poured into the main body 1, it is possible to prevent the drain from overflowing into the dehumidifier 21. Therefore, it is possible to prevent a large amount of drain from being mixed into the compressed air discharged from the dehumidifier 21.

The drain trap 42 is a float-operated type in this embodiment, but is not limited to this. For example, a drain trap having a water surface detection method may be used.
In the present embodiment, a drain switching valve 46 is provided upstream of the drain trap 42 in the drain branch pipe 27. On days with low humidity such as in winter, the amount of drain generated by the dehumidifier 21 is reduced, so the low-pressure side shaft seal device (lip seal) 29 is expected to be poorly lubricated. In such a case, by closing the drain switching valve 46, the entire amount of drain generated in the dehumidifier 21 can be injected into the shaft sealing water channel 26, and thus the low pressure side shaft sealing device 29. The lubrication state of can be maintained satisfactorily. The drain switching valve 46 is not always necessary.

  In the first embodiment and the second embodiment described above, the case of the water jet screw compressor provided with a pair of male and female screw rotors having a timing gear has been described. However, such a water jet screw compressor is not necessarily used. The present invention is not limited, and can be applied to a structure without a timing gear.

1: compressor body, 1A: casing,
2: Motor,
3: Screw rotor,
3A: rotor tooth portion, 3B: suction side rotor shaft, 3C: discharge side rotor shaft,
4: Timing gear,
5: suction part, 50: discharge part,
6: Steam-water separator,
7: Body water supply route (water supply piping)
8: Water cooler
9: Main body water supply path (main body water supply pipe), 9a: Main body water supply path, 9b: Main body water supply hole,
10: Water filter, 11: Main body water supply valve,
12: Cooling fan,
13: External water supply pipe, 14: Stop water supply pipe,
15: Water valve during operation, 16: Water valve during stop,
17: Drain piping, 18: Drain valve,
19, 19a, 19b: discharge path (discharge pipe),
20: Holding valve with check valve function,
21: Dehumidifier
22: Drain discharge path (drain pipe),
23: Strainer, 24: Drain discharge valve, 25: Check valve,
26: Shaft sealed water channel,
27: Drain branch piping,
28: partition wall,
29: Low pressure side shaft seal device (lip seal),
30, 31, 32, 33: bearings,
34, 35, 36: oil seal,
37: High pressure side shaft seal device (mechanical seal),
38: Bounce-up member,
39: Orifice,
40: radial clearance, 41: axial clearance,
42: Drain trap, 43: Float, 44: Valve,
45: Drain discharge piping, 46: Drain switching valve,
47, 48: Oil sump,
49: Discharge path.

Claims (11)

A rotor tooth portion, a suction-side rotor shaft provided on the suction side of the rotor tooth portion, a screw rotor having a discharge-side rotor shaft provided on the discharge side of the rotor tooth portion, and a casing that houses the screw rotor; A bearing provided in the casing for supporting the suction side rotor shaft and the discharge side rotor shaft, and a bearing for supporting the suction side rotor shaft and a suction side end surface of the rotor tooth portion. A compressor body having a low-pressure side shaft seal device provided in the casing;
A steam separator for separating compressed air and water discharged from the compressor body;
A discharge path for guiding compressed air separated by the steam separator, and a main body water supply path for returning the water separated by the steam separator to the compressor body,
A dehumidifier provided in a discharge path for guiding compressed air separated by the steam separator, and condensing and separating water vapor contained in the compressed air as a drain;
In the water jet screw compressor provided with a drain discharge path for discharging the drain condensed and separated by the dehumidifier from the dehumidifier,
A partition provided between the low-pressure side shaft seal device and the suction-side end surface of the rotor tooth portion, and partitioning the low-pressure side shaft seal device and the suction-side end surface of the rotor tooth portion;
A shaft seal pouring channel for supplying water between the low pressure side shaft seal device and the suction side end surface of the rotor tooth portion is formed in the partition wall,
The drain discharge path is connected to the shaft sealing water path. A water jet screw compressor, wherein:   2. The water injection screw compressor according to claim 1, wherein the shaft sealing water channel is communicated with a radial gap formed between an inner peripheral surface of the partition wall and an outer peripheral surface of the suction side rotor shaft. Further, the water-jet screw compression is characterized in that the radial gap is formed larger than the axial gap formed between the partition wall and the suction side end surface portion of the rotor tooth portion. Machine.   3. The water injection screw compressor according to claim 1, wherein a strainer, a drain discharge valve, a check valve, and an orifice are provided in order from the upstream side in the drain discharge path. Screw compressor.   4. The water injection screw compressor according to claim 3, wherein a drain branch pipe is branched from between the check valve and the orifice in the drain discharge path, and a drain trap is provided in the drain branch pipe, and the dehumidification is performed. A water-injection screw compressor characterized in that excess drain generated in the machine can be stored in the drain trap.   5. The water injection screw compressor according to claim 4, wherein the drain trap is configured to automatically discharge the stored drain to the outside when a certain amount of drain is stored. A water jet screw compressor.   6. The water injection screw compressor according to claim 4, wherein a drain switching valve is provided upstream of the drain trap of the drain branch pipe.   The water-injection screw compressor according to any one of claims 1 to 6, wherein a water cooler for cooling water separated by the steam separator in the middle of the main body water supply path, and impurities from the water A water-injection screw compressor, characterized in that a water filter for removing water is provided.   The water-injection screw compressor according to any one of claims 1 to 7, wherein when the compressor body is in operation and the amount of water stored in the steam / water separator is reduced, water is externally supplied. An external water supply pipe for replenishing the compressor main body is provided, and a water supply valve for operation is provided in the external water supply pipe.   9. The water injection screw compressor according to claim 8, wherein a main body water supply valve is provided in the main body water supply path, and an upstream side of the operation water supply valve of the external water supply pipe, and the main body water supply path When the main body water supply valve is connected to the upstream side, the compressor main body is stopped, and the amount of water stored in the steam / water separator is reduced, the steam / water separator is externally connected. A water-injection screw compressor characterized in that a stop-time water supply pipe for supplying water is provided, and the stop-time water supply pipe is provided with a stop-time water supply valve.   The water jet screw compressor according to any one of claims 1 to 9, wherein a check valve and a pressure holding valve or a check valve are provided in the middle of a discharge path connecting the steam separator and the dehumidifier. A water-injection screw compressor, characterized in that a pressure retaining valve with a valve is provided.   11. The water jet screw compressor according to claim 1, wherein the low-pressure side shaft seal device is configured by a lip seal, and further, a bearing that supports the discharge-side rotor shaft and a discharge side of the rotor tooth portion. A water jet screw compressor characterized in that a high pressure side shaft seal device for sealing between the end faces is provided in the casing, and the high pressure side shaft seal device is constituted by a mechanical seal.

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