JP4029261B2 - Screw compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil injection type tandem screw compressor that compresses gas while injecting oil.
[0002]
[Prior art]
An example of a conventional oil injection type tandem screw compressor is shown in FIGS. In the figure, 1 is a low-stage compressor provided with a low-stage screw rotor 2, 3 is a suction port of the low-stage compressor 1, and 4 is a discharge port of the low-stage compressor 1. Reference numeral 5 denotes a high-stage compressor provided with the high-stage screw rotor 6, 7 denotes a suction port of the high-stage compressor 5, and 8 denotes a discharge port of the high-stage compressor 5. Further, reference numeral 9 denotes a driving device such as an electric motor. By driving the driving device 9, the low-stage screw rotor 2 and the high-stage screw rotor 6 can be driven to rotate.
[0003]
Reference numeral 10 denotes an intermediate pipe that connects the discharge port 4 of the low-stage compressor 1 and the suction port 7 of the high-stage compressor 5. The intermediate pipe 10 is connected to the high-stage compressor 5 from the low-stage compressor 1 side. It is squeezed on the way to the side. Thus, the inner peripheral lower portion of the large diameter portion on the low stage compressor 1 side of the intermediate pipe 10 is positioned lower than the inner peripheral lower portion of the small diameter portion on the high stage compressor 5 side of the intermediate pipe 10. ing.
[0004]
Reference numeral 11 denotes a pipe that connects the discharge port 8 of the high stage compressor 5 and the lower side surface of the oil separator 12. Further, when driving the screw compressor, the oil separator 12 and the low-stage compressor 1 are injected so that oil can be injected from the oil separator 12 into the low-stage compressor 1 and the high-stage compressor 5. And it connects with the high stage side compressor 5 by the oil piping provided with the oil supply pump in the middle part (not shown).
[0005]
The upper limit of the level of the oil 13 stored in the oil separator 12 is controlled so as to be positioned below the innermost lowermost portion formed in the large diameter portion of the intermediate pipe 10.
[0006]
When compressing gas with the screw compressor, the drive unit 9 is driven to drive the low-stage screw rotor 2 and the high-stage screw rotor 6, and an oil pump (not shown) is driven, The oil 13 in the oil separator 12 is injected between the low-stage screw rotor 2 of the low-stage compressor 1 and the casing, and between the high-stage screw rotor 6 of the high-stage compressor 5 and the casing. Let
[0007]
The gas sucked into the low-stage compressor 1 from the suction port 3 is compressed by the low-stage screw rotor 2, and sent together with the injected oil from the discharge port 4 to the intermediate pipe 10, and from the intermediate pipe 10 to the suction port 7. And is sucked into the high stage compressor 5. In the high stage side compressor 5, the gas is compressed by the high stage side screw rotor 6, sent together with the injected oil from the discharge port 8 to the pipe 11, and sent from the pipe 11 to the oil separator 12. Thus, in the oil separator 12, the high-pressure gas separates the oil and is sent from the oil separator 12 to the next process.
[0008]
[Problems to be solved by the invention]
In the above screw compressor, when the driving device 9 is stopped, it is necessary to stop the refueling. However, when the driving device 9 is stopped, the refueling is not stopped by mistake. Oil 13 accumulates in the lower portion of the large diameter portion of the intermediate pipe 10. In this case, when the drive device 9 is driven and the screw compressor is restarted, the oil 13 accumulated in the intermediate pipe 10 is suddenly sent together with the gas from the intermediate pipe 10 to the high-stage compressor 5, causing various troubles. May occur.
[0009]
Therefore, conventionally, when the oil 13 is accumulated in the intermediate pipe 10, before the screw compressor is restarted, the low-stage compressor 1 side is pressurized, or the high-stage compressor 5 side. The oil 13 accumulated in the intermediate pipe 10 is returned to the oil separator 12 through the high-stage compressor 5 and the pipe 11.
[0010]
However, if the oil 13 accumulated in the intermediate pipe 10 is returned to the oil separator 12 as described above, the pressurizing means and the vacuum means are required, and the equipment cost and the operation maintenance cost become expensive. In addition, there is a problem that handling becomes complicated.
[0011]
In view of the above circumstances, the present invention can easily and reliably return the oil accumulated in the intermediate pipe to the oil separator, and has a simple structure for returning the oil collected in the intermediate pipe to the oil separator. The purpose is to provide a screw compressor that is inexpensive and inexpensive.
[0012]
[Means for Solving the Problems]
The screw compressor of the present invention is a tandem type screw compressor that performs compression while injecting oil into the compressor during gas compression, and gas is supplied from a low-stage compressor to a high-stage compressor. An intermediate pipe for feeding oil, a pipe for feeding oil and gas discharged from the high- stage compressor, and an oil separator capable of separating oil from the gas and oil fed from the pipe The space portion above the oil reservoir portion of the intermediate pipe and the space portion above the oil reservoir portion of the oil separator are connected by a pressure equalizing pipe having a first on-off valve in the middle. is, the the oil-the accumulated part and the oil separator oil of accumulated portion of the intermediate pipe are connected by a return oil with a second on-off valve to the intermediate portion piping, yet the oil accumulated in the intermediate pipe levels, is configured to be higher than the level of oil in the oil separator It is intended.
[0014]
According to the present invention, when oil supply is not stopped when the screw compressor is stopped and oil has accumulated in the intermediate pipe, the first and second on-off valves are opened. Then, the oil separator and the intermediate pipe are equalized, and as a result, the oil accumulated in the intermediate pipe is returned from the oil return pipe to the oil separator.
[0015]
In the present invention, the oil accumulated in the intermediate pipe can be easily and reliably returned to the oil separator simply by opening the first and second on-off valves, and as means for returning the oil to the oil separator. Since it is only necessary to provide a pressure equalizing pipe, an oil return pipe, and first and second on-off valves, the structure is simple, and the equipment cost and operation and maintenance cost are low.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 3 denote the same components, and the basic configuration is the same as the conventional one shown in FIG. It is. Thus, as shown in FIG. 1, the feature of the illustrated example is that the top end of the intermediate pipe 10 and the portion above the oil 13 of the oil separator 12 are connected to the on-off valve 14 and the reverse valve in the middle. The pressure equalizing pipe 16 provided with the stop valve 15 is connected, and the bottom end of the intermediate pipe 10 and the lower side portion of the oil separator 12 are connected to the oil return pipe provided with the on-off valve 17 and the check valve 18 in the middle. 19 is the point connected.
[0017]
The intermediate pipe 10 is squeezed on the way from the low-stage compressor 1 side to the high-stage compressor 5 side, and the diameter of the low-stage compressor 1 side is the same as that shown in FIG. The diameter is larger than the diameter on the compressor 5 side.
[0018]
The check valve 15 is provided so that gas does not flow back from the intermediate pipe 10 side to the oil separator 12 side, and the check valve 18 prevents the oil 13 from flowing back from the oil separator 12 side to the intermediate pipe 10 side. Is provided.
[0019]
Next, the operation of the illustrated example will be described.
When the screw compressor of the illustrated example is driven to compress the gas, the on-off valves 14 and 17 are closed, but otherwise the operation is performed in the same manner as in the conventional case. Description of the operation itself is omitted.
[0020]
In the screw compressor of the illustrated example, when the oil supply is not stopped and the oil 13 is accumulated in the lower part of the large diameter portion of the intermediate pipe 10 even though the drive device 9 is stopped, the on-off valves 14 and 17 are provided. open. Then, the gas in the oil separator 12 flows from the pressure equalizing pipe 16 into the intermediate pipe 10, and the gas pressure in the oil separator 12 and the gas pressure in the intermediate pipe 10 are equalized. Further, since the level of the oil 13 accumulated in the intermediate pipe 10 is higher than the level of the oil 13 stored in the oil separator 12, the oil 13 in the intermediate pipe 10 flows through the oil return pipe 19 and flows through the oil return pipe 19. Returned to the separator 12.
[0021]
In the screw compressor of the illustrated example, the oil 13 accumulated in the intermediate pipe 10 can be easily and reliably returned to the oil separator 12 simply by opening the on-off valves 14 and 17. Further, since it is only necessary to provide a pressure equalizing pipe 16 having an on-off valve 14 and a check valve 15 and an oil return pipe 19 having an on-off valve 17 and a check valve 18, a simple structure is required. Equipment costs and operation and maintenance costs are low.
[0022]
FIG. 2 shows another example of the embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components. In this example, the diameter of the intermediate pipe 10 on the low stage compressor 1 side is larger than the diameter on the high stage compressor 5 side, as in FIG. However, the height of the top end of the intermediate pipe 10 is different from that in FIG. 1 in that the height is the same on both the low-stage compressor 1 side and the high-stage compressor 5 side. Yes. Therefore, the position of the lower end of the intermediate pipe 10 on the lower stage compressor 1 side is lower than the lower end position of the higher stage compressor 5 as in the case of FIG.
[0023]
By adopting such a configuration, the same operational effects as the screw compressor shown in FIG. 1 can be obtained.
[0024]
In addition, the screw compressor of this invention is not limited only to the above-mentioned illustration example, Of course, a various change can be added in the range which does not deviate from the summary of this invention.
[0025]
【The invention's effect】
As described above, according to the screw compressors of the first and second aspects of the present invention, the oil accumulated in the intermediate pipe can be easily and reliably separated by simply opening the first and second on-off valves. The equipment can be returned to the tank, and as the means for returning the oil to the oil separator, it is only necessary to provide a pressure equalizing pipe, an oil return pipe, and first and second on-off valves. Various excellent effects such as low cost and operation and maintenance costs can be obtained.
[Brief description of the drawings]
FIG. 1 is an overall side view showing an example of an embodiment of a screw compressor according to the present invention.
FIG. 2 is an overall side view showing another example of the embodiment of the screw compressor of the present invention.
FIG. 3 is an overall side view showing an example of a conventional screw compressor.
4 is a view taken in the direction of arrows IV-IV in FIG. 3;
FIG. 5 is a view taken in the direction of arrows VV in FIG. 3;
[Explanation of symbols]
1 Low stage compressor 5 High stage compressor 10 Intermediate piping
11 piping 12 oil separator 13 oil 14 on-off valve (first on-off valve)
16 Pressure equalizing piping 17 On-off valve (second on-off valve)
19 Oil return piping

Claims (1)

A tandem screw compressor configured to perform compression while injecting oil into the compressor during gas compression, and an intermediate pipe for supplying gas and oil from the low-stage compressor to the high-stage compressor; A pipe for feeding the gas and oil discharged from the high- stage compressor, and an oil separator capable of separating the oil from the gas and the oil fed from the pipe. The space portion above the oil reservoir portion and the space portion above the oil reservoir portion of the oil separator are connected by a pressure equalizing pipe having a first on-off valve in the middle, and the oil in the intermediate pipe the partial and oil of accumulating portions of the oil separator accumulated, are connected by a return oil with a second on-off valve to the intermediate portion piping, yet the level of the oil accumulated in the intermediate pipe, oil in the oil separator screw, characterized in that it is configured to be higher than the level Compressor.

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