JPH09324783A - Oil feed type multistage screw compressor and intermediate cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with injected oil into the working chamber of a high pressure stage compressor so as to reduce oil stirring loss in the high pressure stage compressor by providing an intermediate cooler on the way of an air passage from a low pressure stage compressor to the high pressure stage compressor. SOLUTION: Air is sucked by a low pressure stage compressor 1 through a suction pipe 31, the pressure is raised, oil is injected in the compression process through an oil feed pipe 32b so as to lower the air discharge temperature, and the air is introduced to an intermediate cooler 3 in the condition of containing a large quantity of oil. Air entering from the air inlet 17 of the intermediate cooler 3 collides with the inner wall, and air and oil are separated from each other. Further, the air passes through an air passage 11 and reaches an air outlet 18, a part of separated oil during the time is carried together with air, but the oil is interrupted with a baffle 19. Meanwhile, the separated oil is mixed with air again at the air outlet after being sufficiently cooled by a cooling part 12, so as to lower air temperature. The air is further raised in pressure in a high pressure stage compressor 2, but the air contains oil injected at the low pressure stage compressor 1 in this compression process, and hence it dispenses with oil injection as cooling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil supply type screw compressor and an intercooler for injecting oil into a working chamber.

[0002]

2. Description of the Related Art Conventionally, in a refueling type two-stage screw compressor, oil is injected into the working chamber for cooling the compressed air, lubricating the rotor, and sealing the clearance in each of the low-pressure and high-pressure compressors. . Further, between the low-pressure stage compressor and the high-pressure stage compressor, air passages were formed only in the respective casings, and no intermediate cooling was performed. The air sucked by the low-pressure stage compressor is jet-cooled by oil during compression, and is further jet-cooled by oil even in the high-pressure stage.

The air discharged from the high-pressure stage contains a large amount of oil, and an oil separator for separating air from oil is provided. The clean air separated from the oil by the oil separator is cooled and then used for various purposes. On the other hand, the separated oil is cooled by the oil cooler and re-injected into each compressor.

As a relation to the prior art, Japanese Patent Laid-Open No. 57-65895.
There is an official gazette.

[0005]

The oil injected in the low pressure stage cools the compressed air, but the discharge air temperature is 10 to 30 ° C. higher than the oil supply temperature, and heat exchange is sufficiently completed in the low pressure stage. Therefore, it is necessary to cool the compressed air by oil injection again in the high pressure stage. Oil injection has three functions of cooling, lubrication, and sealing, but a large amount of oil is unnecessary for lubrication and sealing, and a large amount of oil is only for cooling air. Large amounts of oil have the greatest advantage of cooling the air,
On the other hand, there is a disadvantage of stirring loss due to the rotor.

The heat exchange of the oil injected by the low-pressure stage machine has been completed by the time it is discharged, and the oil injected by the low-pressure stage machine has no effect of cooling the compressed air for the high-pressure stage machine, resulting in oil agitation loss. Will only increase.

[0007]

An intercooler is provided between the low-pressure stage machine and the high-pressure stage machine to stop the oil injection of the high-pressure stage machine.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a system diagram of a refueling type two-stage screw compressor of the present invention. Reference numeral 1 is a low-pressure stage compressor, 2 is a high-pressure stage compressor, and an intercooler 3 is provided between them. An oil separator 4 and a post-stage cooler 5 are provided downstream of the high-pressure stage compressor 2. A separation filter 6 is provided on the upper part of the oil separator 4, and oil 7 is filled on the lower part. An oil pipe 8 is attached to a lower portion of the oil separator 4, and is connected to a bearing and a working chamber of the low pressure stage compressor 1 and the high pressure stage compressor 2 via an oil cooler 9.

The intercooler 3 is shown in FIGS. 2 and 3. The intercooler 3 includes the partition wall 20 and the air passage portion 11 and the oil cooling portion 1.
It is divided into two. A baffle plate 19a projects from the partition wall 20 in the air passage part 11, and baffle plates 19b, 19c, 19d, 19e are provided in the oil cooling part 12. Water jackets 13 a and 13 b are provided at both ends of the intercooler 3, and the water jacket 13 has a water inlet 14 and a water outlet 15.
Is provided. The water jackets 13a and 13b are connected by a copper pipe 16, and cooling water flows from the water jacket 13a through the copper pipe 16 to the water jacket 13b.
An air inlet 17 is provided on the side surface of the intercooler 3 and an air outlet 18 is provided on the lower surface thereof.

The operation of the oil-filled two-stage screw compressor constructed as described above will be described. The low-pressure stage compressor 1 sucks air through the suction pipe 31 and boosts the pressure to about 1.8 kgf / cm ² G. In the compression process, 50 ° C through the oil supply pipe 32b
A certain amount of oil is injected, and the discharge temperature at the outlet of the low pressure stage compressor 1 becomes 60 to 80 ° C. The air discharged from the low-pressure compressor 1 contains a large amount of oil and is guided to the intercooler 3 in that state.

The air entering from the air inlet 17 of the intercooler 3 collides with the inner wall of the intercooler 3 and separates air and oil. Further, the air passes through the air passage 11 and the air outlet 18
A part of the oil 33 separated during this time is carried away with the air, but is blocked by the baffle plate 19a. on the other hand,
The separated oil 33 is sufficiently cooled in the cooling unit 12 and then mixed again at the air outlet 18. Mixing air and oil lowers the air temperature by tens of degrees. Baffles 19b, 19c, 19
d and 19e enhance the cooling effect by the separated oil 33 efficiently crossing the copper pipe 16, and the baffle plate 19e also has the effect of the oil sump.

In the high pressure stage compressor 2, the pressure is further increased to 7 kgf.
/ Cm ² G In this compression process, the low pressure stage compressor 1
Since the cooling oil injected in the above is included, the oil injection for cooling is unnecessary. The discharge air in the high-pressure stage compressor 2 becomes 60 to 80 ° C. as in the low-pressure stage compressor 1. The discharged air is used as a factory air source after the air and oil are separated in the oil separator 4 and the air is cooled in the post-stage cooler 5.

The oil separated by the oil separator 5 falls to the lower part, and is refueled and recirculated due to the pressure difference between the oil separator 5 and the compressors 1 and 2. The oil cooled by the oil cooler 9 is supplied with oil 32a, 32c to the bearings of the low-pressure compressor 1 and oil 32b to the working chamber, and bearings 32d, 32e of the high-pressure compressor.
Supplied to

4 and 5 show another embodiment of the intercooler. A spiral plate 21 and a copper pipe 16 are provided on the circumference of the inner tube of the intercooler. A guide 22 is provided inside the spiral plate 19. The air inlet 17 and the air outlet 18 are offset from the inner cylinder axis.

In the intercooler of FIG. 4, when air containing oil enters from the air inlet 17, the air and the oil swirl, and oil having a high density flows to the outer peripheral side. The guide 22 of the spiral plate 21 prevents a part of the separated oil 33 from flowing inward, and the separated oil 33 is positively cooled via the copper pipe 16 that flows along the upper surface of the spiral plate. Then, the cooled separated oil 33 is supplied to the air outlet 18
It is mixed with air and cooled.

[0017]

According to the present invention, the oil that has been conventionally injected into the working chamber of the high-pressure compressor becomes unnecessary, and the oil agitation loss in the high-pressure compressor is reduced. In the past, the amount of oil circulating in the oil cooler was low, and was the sum of the bearings and working chambers of the high-pressure compressors 1 and 2, but since oil injection to the high-pressure compressor was eliminated, oil cooling The container 9 can be miniaturized.

Further, since the intercooler separates air and oil from each other and cools only the oil having a large heat capacity per volume, the intercooler can be made compact and have high performance.

[Brief description of drawings]

FIG. 1 is a system diagram of a refueling type two-stage screw compressor of the present invention.

FIG. 2 is a vertical sectional view of an intercooler.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a cross-sectional view of another embodiment of the intercooler.

FIG. 5 is a sectional view taken along line BB of FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Low-pressure stage compressor, 2 ... High-pressure stage compressor, 3 ... Intercooler, 11 ... Air passage part, 12 ... Oil cooling part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Suzuki 390 Muramatsu, Shimizu City, Shizuoka Prefecture Hitachi Ltd. Air Conditioning Systems Division

Claims (4)

[Claims] 1. A refueling multi-stage screw compressor in which a low pressure compressor is connected to a high pressure compressor by an air passage, and an intercooler is provided in the middle of the air passage. Machine. 2. The intercooler has a function of selectively cooling only oil in a two-phase flow of gas and oil, and further has a function of separating gas and oil near an inlet and a function of separating gas and oil near an outlet. The refueling multi-stage screw compressor according to claim 1, which has a mixing function. 3. The intercooler according to claim 2, wherein the gas and the oil are separated by gravity. 4. The intercooler according to claim 2, wherein gas and oil are separated by centrifugal force.