JPS61126399A - Capacity controller for compressor or blower - Google Patents

Abstract

PURPOSE:To reduce the calculated electric power on off-load by throttling the amount of wind by an outlet guide-vane apparatus and then operating an inlet-vane control apparatus and controlling a compressor and the amount and pressure of the wind of a blower as small as possible. CONSTITUTION:In the inlet vane 2 control, capacity is controlled by providing previous turn for the flow at the inlet of a vane wheel 1 by revolving an inlet vane 2, and in the outlet guide-vane 3 control, the capacity on the outlet side of the vase wheel 1 is controlled by revolving the outlet guide vane 3. In the first stage, the capacity is throttled to 50% or less by the outlet guide vane 3, and the inlet vane 2 is revolved in the second state, and then the flow speed at the inlet vane 2 part is reduced, and the pressure loss can be reduced, and the previous turn can be provided. Therefore, the operation with high efficiency is permitted, and the consumption electric power on off-load can be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to capacity control of centrifugal compressors and blowers. The present invention relates to a capacity control device suitable for when it is necessary to reduce power.

[Background of the invention]

FIG. 5 shows the characteristic curve of the compressor or blower.

The characteristic surface 11aa, which is characterized by the required dose of the plant during normal operation Q6 and the required pressure, shows the characteristic curve of the compressor or blower passing through point A at this time. Point B is the minimum air volume and wind pressure required by the plant. Q is 50% of Q
In the following cases, the control range of the inlet vane control device and discharge guide vane is generally exceeded, and it is almost impossible to obtain a characteristic curve that passes through point B in Figure 5. be. Also, if a suction valve is installed in place of the inlet vane control, it is possible to obtain a characteristic curve that passes through point B, but there are disadvantages of the first-order point and rjJ,
There is a point a.

The disadvantage is that throttling by the suction valve is a method of lowering the pressure by pressure loss, and it is less efficient than the inlet vane control control method or the discharge guide vane control method.The problem is that the pressure drop is excessive. Therefore, the suction pressure of the compressor or blower after the suction valve drops significantly. Therefore, if the suction pressure is around atmospheric pressure, the suction pressure after the suction valve will be very low, and the outside air will be sucked in through the seal part of the shaft penetration, making it unsuitable if the purity of the handled gas is a problem. It is.

Therefore, a need arose for a capacity control method other than the suction valve that would enable operation as shown at point B in FIG.

Related publicly known examples include: ■Special Publication No. 57-49759, ``Vane Control Device'' ■Utility Model Publication No. 53-162404, Inlet Guide Vane Device for Centrifugal Fluid Machines'' ■Special Publication No. 1977, ``Vane Control Device''
-43737 "Diffuser for centrifugal fluid machine" etc.

[Purpose of the invention]

The purpose of the present invention is to efficiently achieve a small capacity, low pressure operating point such as point B, which cannot be achieved by inlet vane control control or discharge guide vane control alone, compared to normal operating point A, thereby saving energy in a plant. It is. Furthermore, in order to suppress pressure loss at the inlet vane and prevent outside air from being sucked in through the shaft seal, the opening relationship between the inlet vane and the outlet vane must be determined.

[Summary of the invention]

In Fig. 1, the inlet vane control control controls the capacity by giving a pre-swirl to the flow of one blade by rotating the inlet vane 2, and by rotating the outlet guide vane 3, the flow of the impeller is controlled. Exit guide vane control controls the capacity on the 8-port side of No. 1. Second
In fig.

The pressure loss due to the inlet vane, which shows the relationship between the opening degree αtv of the inlet vane and the pressure loss coefficient S due to the inlet vane, is α, 7
The larger the value, the larger it is, and it is proportional to the square of the flow velocity. Therefore, for efficient operation, α and 7 should be small, and υ should not become excessive.

Therefore, in order to minimize the drop in efficiency and achieve the operation at point B in Figure 5, the discharge guide vane (2 in Figure 1) is moved in the first step to increase the capacity as much as the discharge guide vane can throttle. The present invention attempts to achieve the operation shown at point B in Figure 5 by a method of narrowing down the capacity and further narrowing down the capacity by giving a pre-turn by inlet vane control as a second step. In this way, the inlet vane control is activated when the capacity of the discharge vane becomes 50% or less, so the flow velocity at the inlet vane section is slowed down, and the pressure loss due to the inlet vane can be kept small and can be controlled in advance. Since turning can be appropriately applied, operation at point B can be achieved efficiently. Also, because the control is based on the head drop caused by pre-swinging, the pressure loss will not be excessive as it would be when the suction valve is throttled.

This control method is suitable for machines where purity is an issue, since outside air is not sucked in from the seal labyrinth 6 in the shaft penetrating portion.

[Embodiments of the invention]

FIG. 1 shows an embodiment in which an inlet vane control device and an outlet guide vane control device are provided. FIG. In this case, it indicates fg1 stage. Although it is possible to provide the inlet vane control device and the outlet guide vane device in each stage, in the present invention, since the main purpose is to control the capacity to a small level, they are provided in the first stage. It shall not be installed on steps.

The details of the exit guide vane control mechanism are omitted, but each guide vane is uniformly rotated by a ring mechanism. The discharge guide vane is controlled to change the capacity until the characteristic curve curves out from curve a during normal operation of the characteristic curve shown in FIG. At this time, the inlet vane of the inlet vane control device remains fully open and does not operate.

The installation position of the air vane should be determined by considering the air volume on the curve.
Determine the vane installation position. The vane installation position is such that the flow velocity at the inlet vane is approximately 30% when the air volume is throttled by the discharge guide vane.
The vane setting position is important because if the flow velocity is too fast, the whirl effect will not be produced effectively. After completing the characteristic curve, operate the inlet vane for the first time and change the characteristic curve from b to C.
to reach the target flow rate C point.

FIG. 4 shows an example of the control angle of the control method for the outgoing and incoming movements.

The exit guide vane is generally operated at an angle of about 0 to 10 degrees. The inlet vane is about 0~606.

Keep the opening at a level where you can expect a whirl effect. If the inlet vane is throttled too much, the pressure loss at the inlet vane section will be excessive, and outside air will be sucked in through the shaft sealing section, causing a drop in purity. Furthermore, if the outlet vane is not controlled first, the pressure loss caused by the inlet vane will occur, causing the same problem as above.

A simple driving method is to attach an actuator to each of the outlet vane control and the inlet vane control.

〔Effect of the invention〕

According to the present invention, it is now possible to reduce the capacity of the compressor or blower to 50% or less, which was previously impossible, and it is greatly useful for energy-saving operation in plants where it is impossible to completely stop the compressor or blower. be. In addition, in the case of suction valve throttling, the issue of outside air being mixed in from the seal part caused by the drop in suction pressure after the valve is solved by reducing the head using the whirl effect using the isolette vane control method after throttling the capacity with a discharge guide vane. Therefore, the suction pressure does not become excessively negative.

Therefore, it is suitable for handling gases whose purity is a problem due to the mixing of outside air from the sealed portion.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an inlet vane control device and an outlet guide vane control machine for a compressor or blower according to an embodiment of the present invention, and Fig. 2 is a line showing the relationship between the vane opening degree and pressure loss of the inlet vane control device. Figure 3 is a diagram showing the capacity change due to control of the discharge vane and inlet vane, Figure 4 is a control pattern diagram of the inlet vane and outlet vane, and Figure 5 is a characteristic diagram of a conventional compression machine or blower. 1... Impeller, 2... Inlet vane, 3... Outlet vane. 4... Suction bell mouth, 5... Casing,
6... Seal labyrinth, 7... Shaft, 8...
・Link No. Z Figure C destination) (b) f33 Figure Q Lice 1 quantity Figure 4 End 5 Figure li Q

Claims (1)

[Claims] 1. In a centrifugal compressor or blower whose capacity is controlled by an inlet vane control device or an outlet guide vane control device, the The first step is to narrow down the air volume using the outlet guide vane control device, and the second step is to operate the inlet vane control device installed at an appropriate location upstream of the impeller to reduce the air volume and pressure of the compressor or blower to the maximum possible level. A capacity control device for a compressor or blower, which is characterized by small control and reducing the power consumption of the compressor or blower when off-loading.