JPH06147190A - Tandem centrifugal compressor device - Google Patents

Abstract

PURPOSE:To drive two compressors by one driving machine with a high efficiency by providing a suction valve and a discharge pressure detecting device on each of plural centrifugal compressors tandem-driven by a single variable speed driving machine, taking in a discharge pressure detection value and controlling the rotational frequency of a driving machine in such a manner that the discharge pressure of the centrifugal compressors attains individual target discharge pressure. CONSTITUTION:Two compressors 2a, 2b are respectively provided with discharge pressure detecting devices 3a, 3b, suction valves 7a, 7b, surge monitoring parts 11a, 11b, by-pass pipes 4a, 4b, by-pass control valves 9a, 9b and suction valve full-opening detecting devices 12a, 12b and with a common speed controller 5. The discharge pressure of the discharge pressure detecting devices 3a, 3b and the throttle valve openings of the full opening detecting devices 12a, 12b are input to a control part 20, and the control part controls the opening of the suction valves 7a, 7b and the speed of the speed setting device 5 through a controller 6. The volume flow on the input side and the rotating speed of the driving machine are input to the surge monitoring parts 11a, 11b, to detect whether the compressors 2a, 2b enter the surge region or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor device in which two or more centrifugal compressors (including fans and blowers) are operated in a tandem type with a single drive.

[0002]

2. Description of the Related Art A conventional example in which one compressor is driven by one drive is a "blower and compressor" (Takefumi Ikui, published by Asakura Shoten, first edition December 1, 1960) ( Pages 322-3
29).

This prior art example describes a surging prevention and flow rate control system. The compressor capacity control system includes a suction valve throttle system and a rotation speed (speed) control system (ibid., Page 324 et seq.). What is the suction valve throttle system?
This is for controlling the opening degree of a suction valve provided on the suction side of the compressor, and the rotation speed control method is for controlling the rotation speed of a drive device (electric motor, turbine, etc.) that drives the compressor.

An example of rotational speed control is shown in FIG. 2, and an example of suction valve control is shown in FIG. The horizontal axis is the discharge air volume, and the vertical axis is the discharge pressure. To the operating point a ₁ in the rotational speed N ₁ in FIG. 2, the rotational speed N ₁ → N ₂
By controlling → N ₃ → N ₄ , the operating point a ₁ also changes to a ₁ → a ₂
→ a ₃ → a ₄ indicates the movement. In FIG. 3, by adjusting the suction valve of the compressor, the compressor inlet pressure is p ₁ →
p ₂ → p ₃ → p ₄ and the operating point is c ₁ → c ₂ → c ₃ → c ₄
And move.

FIG. 4 is a rotation speed control system diagram, and shows an example in which the compressor 2 is driven by the driving machine 1. The drive unit 1 is an example of a turbine (which may be an electric motor), and the opening of the suction valve (input flow rate control valve 5) is controlled by the opening adjuster 6 to substantially control the rotational speed of the turbine 1. The discharge pressure of the compressor 2 is detected by the discharge pressure detector 3 (pc), and the opening degree of the opening degree adjuster 6 is indicated by the magnitude of the detected value.

FIG. 5 is a suction valve control system diagram, in which the opening of the regulator 8 is specified by the detection value of the discharge pressure detector 3 and the opening of the throttle valve 7 is controlled.

FIG. 6 shows a conventional example for preventing surging. A bypass pipe 4 is provided between the discharge side and the inlet side of the compressor 2 via a bypass control valve 9, and a flow rate detection / detection system on the inlet side (generally a surge monitor and various other detection parameters). When the approach to the surge region is sensed in (10), the control valve 9 is opened via the adjuster 11 and a part of the discharge amount is kicked back to the inlet side to avoid the transition to the surge region.

An explanatory view of this surging and kickback is shown in FIG. The dotted line L is the surge boundary line, the right side of which is the safety area (operating area), and the left side is the surge area.
Therefore, at the operating point b ₁ , the normal operation is performed, and at the operating point b ₂ , the bypass valve 9 is opened due to the boundary with the surge region.
Control is performed so that the operating point does not reach the b ₃ point in the surge area. To this may do it back to the input side through the bypass pipe 4 a flow comprising (Q ₂ -Q _3). This (Q ₂ −
Q ₃₎ is the kick-back amount.

[0009]

It is no problem to drive the two compressors separately by the two drive machines, but two compressors having different applications can be used as one drive machine. It is not easy to drive. The two compressors having different applications include, for example, compressed air for general work and compressed air for special work requiring special strong blow in FA management. Further, there are cases where two substances are separated from one liquid or gas in centrifugal separation.

When two compressors having different purposes are driven by one driving machine, two speed control signals obtained from each compressor are used as they are for one speed of the driving machine. Putting it in the setting device (5 in Fig. 4) does not solve the problem. In other words, it is necessary to decide one goal by some idea.

An object of the present invention is to provide a tandem type centrifugal compressor device which enables two compressors to be efficiently driven by one driver.

A further object of the present invention is to provide a tandem type centrifugal compressor device which enables flow rate control and surge region avoidance control.

Specific aspects of the present invention for achieving the above object are as follows. (1) If the number of rotations is set as high as possible, at least one compressor is operated without suction restriction, and the other compressor is controlled by the suction throttle to obtain the minimum power of the plant. It should be possible to operate two compressors.

(2) As the air volume handled by the compressor decreases,
The compressor approaches the surging range, and kickback operation may be used to perform further reduction operation. However, comparing the rotational speed control and the suction throttle, the suction throttle system can obtain a wider operating range. In addition, even if kickback is performed, it is possible to reduce axial power by performing kickback from the suction throttle system state having a wide operating range. Therefore, when anti-surge control is needed following the capacity control with the above-mentioned rotation speed priority, priority is given to anti-surge, and the rotation speed up suction throttle system is used.
It suffices to cover a wide operating range with less power.

[0015]

The present invention provides a plurality of centrifugal compressors having different applications, a suction valve and a discharge pressure detector provided in each of the plurality of centrifugal compressors, and the plurality of compressors. A single variable speed drive unit that operates in tandem and the discharge pressure detection value of the discharge pressure detector are fetched so that the discharge pressure of at least one arbitrary centrifugal compressor becomes an individual target discharge pressure. And a means for controlling the number of revolutions (claim 1).

Further, the present invention is directed to a plurality of centrifugal compressors having different applications, a suction valve and a discharge detector provided in each of the plurality of centrifugal compressors, and a single tandem driving of the plurality of compressors. Opening of the suction valve of its own so that the discharge pressure detection values of the variable speed drive and the discharge pressure detector are taken in so that the discharge pressures of at least one or more centrifugal compressors become individual target discharge pressures. (Claim 2).

Further, the present invention is directed to a plurality of centrifugal compressors having different uses, a suction valve and a discharge pressure detector provided in each of the plurality of centrifugal compressors, and a single tandem driving of the plurality of compressors. Of the variable speed drive and the discharge pressure detection value of the discharge pressure detector, and controls the rotational speed of the drive machine so that the discharge pressure of at least one arbitrary centrifugal compressor becomes an individual target discharge pressure. The first means and the discharge pressure detection value of the discharge pressure detector are taken in, and the opening degree of the suction valve of the self is adjusted so that the discharge pressure of the centrifugal compressor other than the arbitrary one becomes the individual target discharge pressure. And a second means for controlling (Claim 3).

Further, according to the present invention, each centrifugal compressor is provided with a bypass pipe for kicking back the discharge flow rate to the suction side, and is used for preventing the surge region operation (claim 4).

Further, the present invention is directed to first and second centrifugal compressors having different uses, a suction valve and a discharge pressure detector provided in each of the first and second centrifugal compressors, and the first and second centrifugal compressors. , A single variable speed drive that drives the second compressor in tandem,
Control means for taking in the discharge pressure detection value of the discharge pressure detector and controlling the rotation speed of the drive machine and controlling the opening degree of the suction valve of the centrifugal compressor so that each discharge pressure becomes an individual target discharge pressure. And (claim 5).

Further, the present invention is directed to first and second centrifugal compressors having different uses, a suction valve and a discharge pressure detector provided in each of the first and second centrifugal compressors, and the first and second centrifugal compressors. , A single variable speed drive that drives the second compressor in tandem,
The discharge pressure detection value of the discharge pressure detector is taken in
The centrifugal speed is controlled so that the discharge pressure of the one centrifugal compressor becomes the individual target discharge pressure, and the discharge pressure of the other centrifugal compressor becomes the individual target discharge pressure. Means for controlling the opening degree of the suction valve of the machine (claim 6).

Further, according to the present invention, the above-mentioned control means sets the target pressure to each target discharge pressure by reducing or increasing the rotation speed of the driving machine driven when the pressure increases or decreases. It was decided to control so as to obtain (Claim 7).

Further, according to the present invention, the control means obtains the target pressure by squeezing or opening the corresponding suction valve when the pressure rises or falls with respect to each target discharge pressure. Thus, each centrifugal compressor is individually controlled (claim 8).

Further, according to the present invention, the control means responds by lowering the rotation speed so that at least one of the two suction valves fully opens to satisfy the specified pressure, and the discharge pressure of the other compressor becomes high. On the other hand, it was decided to control so that the throttle of the suction valve of the corresponding compressor would correspond (step 9).

Further, according to the present invention, a bypass pipe for kicking back the discharge flow rate from the discharge side to the suction side and a kickback control valve for controlling the opening degree of the bypass pipe are provided in each of the first and second centrifugal compressors. It is provided (claim 10).

Further, according to the present invention, the control means responds by lowering the rotation speed so that at least one of the two suction valves fully opens to satisfy the specified pressure, and the discharge pressure of the other compressor becomes high. On the other hand, if the suction valve throttle of the corresponding compressor is controlled so as to cope with it, and if a surging prevention measure is required during the control by the control means, the compressor is prioritized over the control by the control means. The control is performed to increase the rotation speed of the to increase the operating range (claim 11).

Further, according to the present invention, the control for opening the kickback control valve is performed after the rotational speed of the compressor reaches the maximum allowable speed (claim 12).

[0027]

According to the present invention, a plurality of centrifugal compressors can be tandem driven by a single drive (claims 1 to 4).

Furthermore, the present invention enables tandem drive by one driver for two centrifugal compressors (claims 5-6), and further, suction of each of the two compressors and One of the throttle valves provided in is adjusted in rotation speed so as to be fully opened, and the other compressor whose pressure is too high at this rotation speed is suctioned and controlled (controls 5 to 9). With this, the driving force of the compressor can be minimized.

Further, when the required air volume decreases and any one of them requires treatment to prevent surging, first, the rotational speed is increased to widen the operation range (claims 10 to 1).
1). This rotation speed control has priority over the above-described rotation speed control for pressure adjustment (claim 12). As a result, in the operation in the small air volume region, the suction throttle is prioritized, the bypass amount for antisurge is minimized, and the required shaft power is also minimized.

[0030]

FIG. 1 is a diagram showing an embodiment of the present invention. In this embodiment, the controller 20 is provided, and the two compressors 2a,
2b includes discharge detectors 3a and 3b suction valves 7a and 7b, respectively.
b, surge monitoring units 11a and 11b, bypass pipes 4a and 4
b, the bypass control valves 9a and 9b, the suction valve full opening detectors 12a and 12b are provided, and the common speed controller 5 is provided.
Is provided, and the like.

The control unit 20 controls the discharge pressures P ₁ and P ₂ of the discharge pressure detectors 3a and 3b, and the throttle valve opening degrees V ₁ and V _{2 of the} total opening degree detectors 12a and 12b (a signal indicating whether or not the valve is fully opened). ) And are input, the opening control of the suction valves 7a and 7b and the speed control of the speed setting device 5 are performed via the adjuster 6. The opening control of the throttle valves 7a and 7b is for realizing the flow rate control by the throttle, and the speed control of the speed setting device 5 is for realizing the flow rate control by the speed.

The surge monitoring units 11a and 11b receive the volume flow rate QC on the input side and the rotation speed N of the driving machine as inputs.
It is detected whether or not the compressors 2a, 2b are in the surge area or there is a possibility of entering the surge area. To monitor surges,
There is also an example in which the ratio between the suction pressure and the discharge pressure and the flow rate Q are monitored.
If the suction pressure is known, the discharge pressure and the flow rate Q may be used for the determination.

The throttle valve full-open detectors 12a and 12b detect whether or not the throttle valves 7a and 7b are operated at full opening, and one of the intake valves 7a and 7b is fully opened. Degree, the compressor to which the throttle valve of this full opening performs rotation speed control (that is, rotation speed control of the drive machine),
The other compressor controls the flow rate by controlling the opening degree of the suction valve belonging to it.

The drive unit 1 is an example of a turbine, and the rotation speed is controlled by the opening of the valve 5. Other driving means such as an electric motor may be used.

In the compressors 2a and 2b, first, 2a is the throttle valve 7
It takes in the flow rate through a, does the work for the first purpose at this discharge flow rate, then 2b takes in the flow rate from 2a and does the work for the second purpose at this discharge flow rate. There is an example of application of pneumatic pressure, in which compressed air for work (for example, 5 Kg pressure to 7 Kg pressure) is used in the first compressor 2a, and instrumented compressed air (10 Kg pressure to 30 Kg pressure) is used in the second compressor 2b. There is an example to gain. In the case of separating and extracting chemical substances A and B contained in the same flow source in a chemical plant such as oil refining,
There is also an application example in which 2a is used for taking out the chemical substance A and 2b is used for taking out the chemical substance b.

The discharge detectors 3a and 3b are used to monitor the discharge pressure. The control unit 20 controls the rotation speed by the adjuster 6 and the throttle control of the suction valves 7a and 7b by observing the discharge pressure.

The operation of FIG. 1 will be described. FIG. 8 shows a control flow. In the compressors 2a and 2b, both discharge pressures 2a and 2b are set to be higher than the discharge pressures required by the process. As a means for adjusting the discharge pressure to a specified value from this state, a signal is output from the control unit 20 to the adjuster 6 in the direction of decreasing the rotation speed of the driving machine 1. By decreasing the rotation speed, either the compressor 2a or 2b becomes the specified discharge pressure. In this state, the detector 12a or 12b detects whether or not the suction valve 7a or 7b of the compressor whose pressure has reached the specified value is fully opened. A control signal is sent from 20 to fully open either the suction valve 7a or 7b.
When either one of the suction valves 7a or 7b is fully opened, the discharge pressure increases, and the control unit 20 controls the rotation speed reduction via the adjuster 6. Then, finally, the specified discharge pressure is created by adjusting the rotation speed with the suction valve fully opened.

The control method for achieving this fully opening is as follows. (1) Either one of 7a and 7b is set as the suction valve to be fully opened, and when the suction valve is not fully opened, the opening degree of the suction valve is opened so as to be fully opened. Which of the intake valves to be fully opened, 7a or 7b, is arbitrary. (2) The suction valve that should be fully opened is not determined, and if both suction valves 7a and 7b are not fully opened, a full open command is sent to both, and when either one becomes fully open, the generation of the opening command is stopped. To do.

At this time, in the other compressor, as the rotation speed decreases, the suction valve moves in the opening direction to adjust the discharge pressure. At this time, if any of the compressors outputs a suction valve fully open signal and the discharge pressure thereof satisfies a specified value, the rotation speed is determined in that state.

In order to satisfy the discharge pressure, the rotational speed is adjusted to be lower, and the required shaft power is the minimum when the suction throttle valve is not throttled. The point of this control is that the suction throttle valve of either compressor is fully opened to lower the rotation speed. In any of the compressors 2a and 2b, the above control is possible when the operating point of the compressor is not in the surge region. The case where the operating point of either compressor is in the surge region will be described below.

The antisurge control is shown in FIG. L ₁ is the surging boundary line in the rotational speed control, L ₂ is the surging boundary line in the throttle valve opening control, and the oblique line side is the surge region in both cases. As can be seen from this figure, the suction throttle valve control can obtain a wider operating range than the rotation speed control, and the suction control without the bypass control is more preferable than the bypass control (use of the pipe 4). Requires less axial movement.

In consideration of this, when any of the compressors enters the surging due to the above-mentioned decrease in rotation speed,
When it is detected that it is in the surge region, the rotation speed is lowered in preference to the control for minimizing the rotation speed. As a result, the required discharge pressure increases, and the suction throttle valve moves in the throttle direction for pressure adjustment. If the operating point enters from the surge area to the operable area by this movement, the opening degree and the rotation speed of the suction valve are determined in that state. The movement for avoiding this surge region is continued if necessary until the rotational speed reaches the maximum rotational speed. Even if the maximum rotation speed is reached, if the surge range cannot be avoided, the rotation speed remains at the maximum rotation speed and bypass control (the valve 9 of the pipe 4a or 4b is performed.
By opening either a or 9b), the surge is avoided. This control enables operation with the least power.

When there is a large difference in shaft power between the two compressors, it is advisable to weight the control in the above control. The surge monitoring units 10a and 10b are the control unit 20.
You may give the function in. Furthermore, the centrifugal compressor
There may be two or more units.

[0044]

According to the present invention, in controlling a plurality of compressors, for example, two compressors operated by one driving machine, the rotation speed is minimum, and the suction suction valve of one of the compressors is fully opened. Since the specified discharge pressure can be created, it is possible to operate with the minimum shaft power. Furthermore, when either of them enters the surge area in this state, or when there is a risk of entering it, the control with the minimum rotation speed is given priority and the operation range is expanded by the throttle valve throttle control method, and Since the kickback control is performed only when necessary, it is possible to operate with the minimum shaft power even when the surge area is entered.

[Brief description of drawings]

FIG. 1 is an embodiment diagram of a centrifugal compressor device of the present invention.

FIG. 2 is a diagram showing an example of rotational speed control.

FIG. 3 is a diagram showing an example of aperture opening control.

FIG. 4 is a system diagram of rotation speed control.

FIG. 5 is a system diagram of throttle opening control.

FIG. 6 is a kickback control system diagram.

FIG. 7 is a diagram showing an example of kickback control.

FIG. 8 is a control flow chart of the present invention.

FIG. 9 is a diagram showing an example of surge region avoidance operation in rotation speed control and throttle opening control.

[Explanation of symbols]

1 Driver 2a, 2b Centrifugal compressor 3a, 3b Discharge pressure detector 4a, 4b Bypass pipe 5 Speed setting device 6 Regulator 7a, 7b Suction valve 9a, 9b Bypass control valve 10a, 10b Volume flow detector 12a, 12b Throttle Valve full opening detector L, L ₁ , L ₂ Surge boundary line 20 Control unit

Claims (12)

[Claims] 1. A plurality of centrifugal compressors having different applications, a suction valve and a discharge pressure detector provided in each of the plurality of centrifugal compressors, and a single variable speed tandem-driving the plurality of compressors. A drive unit, and means for taking in the discharge pressure detection value of the discharge pressure detector, and controlling the rotational speed of the drive unit so that the discharge pressure of at least one arbitrary centrifugal compressor becomes an individual target discharge pressure, Tandem centrifugal compressor device consisting of. 2. A plurality of centrifugal compressors having different applications, a suction valve and a discharge detector provided in each of the plurality of centrifugal compressors, and a single variable speed drive for tandem driving the plurality of compressors. Of the discharge pressure of the compressor and the discharge pressure detector, and controls the opening degree of its own suction valve so that the discharge pressures of at least any one or more centrifugal compressors become individual target discharge pressures. A tandem centrifugal compressor device comprising means. 3. A plurality of centrifugal compressors having different applications, a suction valve and a discharge pressure detector provided in each of the plurality of centrifugal compressors, and a single variable speed tandem-driving the plurality of compressors. A first control for fetching the discharge pressure detection value of the drive machine and the discharge pressure detector, and controlling the rotational speed of the drive machine so that the discharge pressure of at least one arbitrary centrifugal compressor becomes an individual target discharge pressure. And a discharge pressure detection value of the discharge pressure detector, and controls the opening degree of its own suction valve so that the discharge pressures of the centrifugal compressors other than the arbitrary one become individual target discharge pressures. A tandem centrifugal compressor device comprising the second means. 4. The tandem centrifugal compressor device according to any one of claims 1 to 3, wherein each centrifugal compressor is provided with a bypass pipe for kicking back a discharge flow rate to a suction side to prevent surge region operation. Tandem centrifugal compressor equipment used for. 5. First and second centrifugal compressors having different applications, suction valves and discharge pressure detectors respectively provided in the first and second centrifugal compressors, and the first and second centrifugal compressors. A single variable speed drive that drives the compressor in tandem and the discharge pressure detection value of the discharge pressure detector is taken in, and the rotation speed control of the drive machine is performed so that each discharge pressure becomes an individual target discharge pressure. And a control means for controlling the opening degree of the suction valve of the centrifugal compressor, and a tandem type centrifugal compressor device. 6. First and second centrifugal compressors having different applications, suction valves and discharge pressure detectors respectively provided in the first and second centrifugal compressors, and the first and second centrifugal compressors. A single variable speed drive that drives the compressor in tandem, and the detection value of the discharge pressure detector is taken in so that the discharge pressure of any one centrifugal compressor becomes an individual target discharge pressure. A tandem centrifugal compressor comprising means for controlling the rotational speed of the compressor and controlling the opening degree of the suction valve of this centrifugal compressor so that the discharge pressure of the other centrifugal compressor becomes an individual target discharge pressure. apparatus. 7. The tandem centrifugal compressor apparatus according to claim 5, wherein the control means lowers or raises the rotational speed of a driving machine to be driven when the pressure rises or falls with respect to each target discharge pressure. By doing so, the tandem centrifugal compressor device was controlled to obtain the target pressure. 8. The tandem centrifugal compressor device according to claim 5, wherein the control means throttles or opens the corresponding suction valve when the pressure rises or falls with respect to each target discharge pressure. , A tandem centrifugal compressor device in which each centrifugal compressor is individually controlled so as to obtain a target pressure. 9. The tandem centrifugal compressor device according to claim 5, wherein the control means responds by lowering the rotation speed so that at least one of the two suction valves fully opens to satisfy a specified pressure, The tandem centrifugal compressor system is designed to control the discharge pressure of the other compressor by adjusting the suction valve of the corresponding compressor. 10. The tandem centrifugal compressor device according to claim 5, wherein a bypass pipe for kicking back the discharge flow rate from the discharge side to the suction side and opening of the bypass pipe are provided to each of the first and second centrifugal compressors. A tandem centrifugal compressor device equipped with a kickback control valve for controlling the degree. 11. The tandem centrifugal compressor device according to claim 10, wherein the control means responds by lowering the rotational speed so that at least one of the two suction valves fully opens to satisfy a specified pressure, If the discharge pressure of another compressor is high, the suction valve throttle of the corresponding compressor is used to control it. If a surging prevention measure is required during the control by such control means, the above control is performed. A tandem type centrifugal compressor device in which control is performed to increase the rotation speed of the compressor to widen the operating range in preference to the control by the means. 12. The tandem centrifugal compressor device according to claim 11, wherein the kickback control valve is opened after the rotational speed of the compressor reaches an allowable maximum speed. Compressor equipment.