JPH11201094A - Turbo-compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge a weight reduction range, and achieve energy-saving operation. SOLUTION: In a turbo-compressor comprising a compressor housing 30 in which compression parts containing impellers 31 are connected in multiple stages, an inlet guide vane is connected to the suction side of the compression part at the first stage, and a bleed passage 42 to return air in start of compression to the suction side is formed at a shroud part 38 of the compressor housing 30 facing the impeller 31 in the compression part on the back stage side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo-compressor having a multi-stage compressor, and more particularly to a turbo-compressor capable of expanding a range of weight reduction.

[0002]

2. Description of the Related Art In a multi-stage turbo compressor, a compressor section in which a scroll section is formed and an impeller is rotatably provided is connected in multiple stages, an intercooler is connected therebetween, and an aftercooler is provided in a final stage. It is configured by being connected.

In this turbo compressor, a load-no-load operation control for opening and closing a suction valve at two set pressures and a change in pressure of a discharge pipe system caused by a change in the amount of used air are returned to a set point. There is constant-pressure non-surge control which adjusts the capacity while keeping the discharge pressure constant by automatically controlling the opening of the suction valve.

In any of the control methods, the intake valve is automatically throttled to reduce the load so that the current value does not exceed the set value, thereby preventing an overload of the motor caused by an excessive amount of air used and a change in intake air condition. Like that.

[0005]

By the way, when the opening degree of the intake valve is reduced, the compressor enters the surging region, so that the intake air capacity cannot be reduced to 60% or less of the design flow rate.

Normally, a blow-off line is connected to the discharge pipe system of this compressor, and a blow-off valve connected to the line is opened to supply air to the discharge pipe system while controlling blow-off. Although it is possible to reduce the range of the used flow rate, there is a problem in energy saving because waste air and compressed air are wasted.

Recently, an inlet guide vane (IGV) is connected as an intake valve, and by changing the angle of the guide vane, the valve opening is adjusted to change the intake capacity. Since the inlet guide vane changes the opening degree of the valve according to the angle of the guide vane, the intake air entering the first stage compression section is given a swirling flow while flowing in the axial direction, so that the reduction range can be widened.

However, in a multi-stage turbo compressor, there is a problem that even if the reduction range of the intake capacity of the first stage is expanded, the compression section is multi-stage, and surging and stall are likely to occur in the latter stage, so that the reduction range cannot be expanded. .

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, to provide a turbo compressor capable of widening a weight reduction range and operating with energy saving.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a turbo compressor in which a compressor housing accommodating an impeller is connected in multiple stages, and an inlet is provided on the suction side of the first stage compressor. A bleed passage is formed in the shroud portion of the compressor housing, which is connected to the guide vane and faces the impeller of the rear compression portion, to return the air at the start of compression to the suction side.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

First, the flow of the turbo compressor of the present invention will be described with reference to FIG.

FIG. 2 shows an example of a turbo compressor in which three stages of compression units 10, 11, and 12 are connected by an air pipe 13. An inlet guide vane 14 is provided on the suction side of the first stage compression unit 10.
Is connected, and a suction filter 15 is connected to the suction side of the guide vane 14.

A first intercooler 16 is connected between the first-stage compression section 10 and the intermediate-stage compression section 11, and a second intercooler 17 is connected between the intermediate-stage compression section 11 and the last-stage compression section 12. An aftercooler 19 is connected to the discharge side of the compression section 12 of the stage through a check valve 18, and is supplied from the aftercooler 19 to a receiver tank (not shown) through a discharge pipe 20. Compressed air is supplied to the compressed air supply system.

A pressure sensor 24 for detecting the intake air pressure is connected to the suction side of the inlet guide vane 14, and a pressure sensor 25 for detecting the pressure of the compressed air is connected to the discharge side of the check valve 18. Thermometers 26 and 27 are connected to the discharge sides of the first and second intercoolers 16 and 17.

The discharge side of the final stage compression section 12 and the check valve 18
A blow-off line 21 is connected between them, and a blow-off valve 22 and a blow-off silencer 23 are connected to the line 21.

As shown in FIG. 3, the compressors 10, 11, and 12 each include a compressor housing 30 in which an impeller 31 is rotatably housed.

The impeller 31 has a rotating shaft 32 on which a mountain-shaped disk 33 is provided. In the circumferential direction of the surface of the disk 33 and radially, blades 34 having a long blade length and blades 35 having a short blade length are alternately arranged. Attached and formed.

The compressor housing 30 has a suction port 36 formed in front of the impeller 31 and an inflow passage 37.
And a shroud portion 38 formed in a flared shape along the curvature of the blades 34, 35 of the impeller 31,
Following the shroud portion 38, a fuser portion 40 is provided on the outer periphery of the impeller 31 to define a diffuser flow channel 39, and a scroll portion 41 for introducing compressed air passing through the flow channel 39 of the diffuser portion 40 is provided.

In the present invention, as described above, the inlet guide vane 14 is connected to the suction side of the first-stage compression section 10, and the compression sections 11, 11 subsequent to the first-stage compression section 10 are connected.
In particular, a bleed passage 42 for returning the air at the start of compression to the suction side is formed in the compression section 12 of the last stage.
0 is formed on the shroud portion 38.

The structure of the bleed passage 42 will be described in detail with reference to FIG.

A bleed passage 42 is provided in the shroud portion 38.
An annular chamber 43 is formed, and air at the start of compression is located at the tip of the blade 34 having a short blade length.
An introduction passage 44 for introducing the gas into the impeller 3 is formed.
The return path 45 is formed in the inflow passage 37 in front of the bleed passage 37 to form the bleed passage 42.

The bleed passage 42 has an introduction passage 44
Return path 45 so that the pressure of
The inside diameter of the shroud portion 38 before and after is set to have a step Δs so that the front is small and the rear is large, and the angle α of the return path 45 is set to 15 ° to 45 °. To occur.

The bleed passage 42 is provided in the compression section 1 in the final stage.
2 and, if necessary, also in the compression section 11 of the intermediate stage. The amount of bleed air passing through the bleed passage 42 is
6 to about 5 to 15% of the amount of air flowing into the inflow passage 37.

As described above, in the present invention, by connecting the inlet guide vane 14 to the first stage, the range of weight reduction in the first stage compression unit 10 can be expanded, and the bleed to the second stage compression units 11 and 12 can be achieved. By forming the passage 42, the amount of air passing through the impeller 31 increases, so that stall and surging hardly occur and the range of weight reduction can be expanded.

By connecting the inlet guide vane 14 to the first stage, the range of weight reduction in the first stage compression unit 10 can be expanded, and by forming the bleed passage 42 in the second stage compression units 11 and 12, the impeller Since the amount of air passing through 31 increases, stall and surging hardly occur and the weight reduction range can be expanded.

This will be described with reference to FIG.

FIG. 1A shows the operation characteristics of the first stage compression section 10 in the turbo compressor of the present invention.

In the figure, the horizontal axis represents the intake capacity Q, the vertical axis represents the pressure P, and c represents the valve opening 1 of the inlet guide vane.
A characteristic curve at the time of 00% is shown, and S1 shows a surging line when a conventional butterfly valve is used.
0 indicates a surging line when the inlet guide vane is used, and a point p indicates a design pressure and a capacity of 1
If the capacity is reduced with the design pressure from this state, the conventional system enters the surging line S1 with the capacity Q1 and cannot operate. However, the surging line S0 is formed by using the inlet guide vane. The volume can be reduced to the capacity Q0, and the range of weight reduction can be expanded.

Further, by providing the bleed passages 42 in the compression units 11 and 12 at the subsequent stage, it is possible to widen the weight reduction range.

FIG. 1B shows the operation characteristics of the compression section 12 (or 11) on the rear stage.

In the drawing, Sb denotes a surging line when there is no bleed passage, Sa denotes a surging line when a bleed passage is provided, and b denotes a first stage compression unit 1.
0 shows a characteristic curve when the inlet guide vane of 0 is fully opened and there is no bleed passage in the compression section 12 at the subsequent stage,
a shows a characteristic curve when the inlet guide vane of the first stage compression unit 10 is fully opened and a bleed passage is provided in the second stage compression unit 12.

As can be seen from FIG. 1 (b), the characteristic curve a with the bleed passage is wider than the characteristic curve b without the bleed passage, and the maximum capacity is increased. be able to.

Further, by providing the bleed passage 42,
The air circulating in the bleed passage 42 can increase the flow velocity of the air passing between the blades 34 and 35 of the impeller 31,
It is possible to prevent a stall caused by the separation of air from the blades 34, 35.

[0035]

In summary, according to the present invention, by connecting the inlet guide vane to the first stage and forming the bleed passage in the compression portion on the rear stage, the weight reduction range can be widened as a whole, and In the compression section, the amount of air passing through the impeller increases, so that stall and surging hardly occur.

[Brief description of the drawings]

FIG. 1 is a diagram showing operating characteristics of a turbo compressor of the present invention.

FIG. 2 is a diagram showing a flow of the turbo compressor of the present invention.

FIG. 3 is a partial detailed cross-sectional view of a compression section on a rear stage side of the turbo compressor of the present invention.

[Explanation of symbols]

 10, 11, 12 Compressor 14 Inlet guide vane 30 Compressor housing 31 Impeller 38 Shroud 42 Bleed passage

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirofumi Adachi 3934 Inatomi, Tatsuno-cho, Kamiina-gun, Nagano Prefecture Ishikawajima-Harima Heavy Industries, Ltd. Ishikawajima Harima Heavy Industries, Ltd.

Claims (1)

[Claims] In a turbo compressor in which a compressor section containing an impeller in a compressor housing is connected in multiple stages, an inlet guide vane is connected to a suction side of a first-stage compression section and opposed to an impeller of a latter-stage compression section. A turbo compressor characterized in that a bleed passage is formed in a shroud portion of a compressor housing to return air at the start of compression to a suction side.