JP2948421B2 - Compressor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a compressor used for pressurizing a gas in a chemical plant such as a gas pipeline or an ammonia plant.

[0002]

2. Description of the Related Art Conventionally, a control device of a compressor used in a gas pipeline, an ammonia plant, or the like has a structure as shown in FIG. 7, for example. As shown in the figure, a centrifugal compressor 1 is driven by a drive unit 2. As the driving device 2, for example, a gas turbine or a steam turbine is used. When the compressor 1 is in operation, the gas enters the compressor 1 via the suction side pipe 3 and the suction drum 5 and is compressed. The gas that has left the compressor 1 flows out of the pipe 4 on the discharge side and is supplied to the process.

[0003] The outlet side of the compressor 1 is adapted to recirculate the gas to the suction drum 5 via a pipe 7 so that the flow rate of the gas flowing into the compressor 1 does not fall below a predetermined value. The flow rate is adjusted by operating the control valve 6 to prevent the surging phenomenon of the compressor 1. Reference numeral 10 denotes a flow rate detector.

[0004] Next, the behavior when the operation of the compressor 1 changes in the surging direction will be described with reference to FIGS.

First, the horizontal axis represents time, and the vertical axis represents state quantities (pressure,
This will be described with reference to FIG.

Up to the point A, the compressor 1 is in operation, and the inlet pressure, the outlet pressure, the flow rate, and the number of revolutions are rated. At this time, since the compressor flow rate is larger than the set value, the opening of the control valve 6 is fully closed.

[0007] It is assumed that the outlet pressure of the compressor 1 rapidly increases at the point A. The reason for this is that, although the process downstream of the compressor 1 is stopped, the outlet pressure is rapidly increased because the rotation speed of the compressor 1 is constant even though the consumption flow rate of the process is rapidly reduced. And so on.

At this time, the flow rate rapidly decreases and becomes smaller than the set value of the flow controller 11 at the point B. At this time, the opening of the control valve 6 is gradually increased by the flow controller 11 so as to keep the flow rate at the set value. However, generally, the gain of the flow controller 11 cannot be made large because of the stability of the process. For this reason, the opening of the control valve 6 cannot be rapidly increased in response to a rapid decrease in the flow rate.

As a result, the pressure further rises, and at the same time, the flow rate decreases and enters the surging region, and the compressor 1 is operated in the surging region at the point C. Then, the outlet pressure starts to decrease gradually, and the flow rate starts to increase, and is maintained at the set value of the flow controller 11 at the point D.

FIG. 8 shows the operation state from the point A to the point D on the performance curve of the compressor.

In this conventional operation method, the flow controller 11
Since it is not possible to increase the gain of the above, it is not possible to cope with a rapid decrease in the flow rate, and the operation may occur in the surging region. Operating the compressor in the surging area leads to severe damage to the compressor. In addition, if the gain of the flow controller 11 is increased, it is possible to cope with a rapid change in the flow rate, but the control valve 6 operates even during normal operation, and the process becomes unstable.

[0012]

In the conventional operation, the gain of the flow controller 11 cannot be increased.
It is not possible to cope with the rapid decrease in the flow rate, and operation in the surging region occurs. Operating the compressor in the surging area leads to severe damage to the compressor. Further, if the gain of the flow controller 11 is increased, it is possible to cope with a rapid change in the flow rate, but the control valve 6 operates even during the normal operation, and the process system becomes unstable.

In view of the above prior art, the present invention controls a compressor to operate without entering a surging region.
An object of the present invention is to provide a control device for a compressor.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the structure of the present invention comprises a compressor which pressurizes a gas sucked from an inlet side and discharges the gas from an outlet side, and sends a gas from an outlet side of the compressor to an inlet side. A first pressure detector for detecting an inlet pressure of a compressor, wherein the control device has a control valve interposed in a recirculating pipe and whose opening degree changes in accordance with an input operation signal; A first change speed calculator for inputting an output signal of the detector and outputting a signal indicating a change speed of the output signal; and inputting an output signal of the same change speed calculator, the direction of the change speed indicates occurrence of surging. A first function generator for calculating and outputting a change component only in the heading direction, and a first function for inputting an output signal of the function generator and limiting a rate of change only when the rate of change of the inlet pressure decreases. Check the change rate limiter and the inlet temperature of the compressor. Temperature detector, a second change speed calculator for inputting an output signal of the detector and outputting a signal indicating a change speed of the output signal, and a changer for inputting an output signal of the change speed calculator. A second function generator that calculates and outputs a change component only when the speed direction is in the direction of the occurrence of surging, and changes only when the change speed of the inlet temperature decreases by inputting the output signal of the function generator A second rate-of-change limiter for limiting the rate, a flow rate detector for detecting a suction flow rate to the compressor, and a second signal for inputting an output signal of the detector and outputting a signal indicating a rate of change of the signal. 3 change speed calculator;
A third function generator that receives an output signal of the same change speed calculator, calculates and outputs a change component only when the direction of the change speed is in the direction of occurrence of surging, and outputs an output signal of the function generator. A third rate-of-change limiter that limits the rate of change only when the rate of change of the suction flow rate is inputted, a speed detector that detects the speed of the compressor, and an output signal of the speed detector. A fourth changing speed calculator for inputting and outputting a signal indicating the changing speed of the output signal, and inputting the output signal of the changing speed calculating device only when the changing speed is in the direction of surging A fourth function generator that calculates and outputs a change component, a fourth change rate limiter that receives an output signal of the function generator and limits the change rate only when the change speed of the rotation speed decreases, A second pressure detector for detecting an outlet pressure of the compressor; And a fifth change speed calculator for outputting a signal indicating the change speed of the output signal, and a direction in which the change speed direction indicates the occurrence of surging by inputting the output signal of the change speed calculator. A fifth function generator for calculating and outputting a change component only when the fifth condition is satisfied, and a fifth change rate for inputting an output signal of the function generator and limiting the change rate only when the rate of change of the outlet pressure decreases. A limiter, a controller that receives an output signal of the flow rate detector and outputs a signal corresponding to the signal, an output signal of the first rate-of-change limiter, and an output signal of the second rate-of-change limiter. One or more of the output signal of the third rate-of-change limiter, the output signal of the fourth rate-of-change limiter, the output signal of the fifth rate-of-change limiter, and the output signal of the controller Input, and output the operation signal obtained based on the largest signal to the control valve. A maximum value selecting calculation unit that, characterized in that it comprises an.

[0015]

According to the above-mentioned means, the inlet pressure Ps and the outlet pressure Pd of the compressor are detected by the first and second pressure detectors, the inlet temperature Ts of the compressor is detected by the temperature detector, and the flow rate detector is detected. Detects the inlet flow rate q of the compressor, the rotational speed detector detects the rotational speed n of the compressor, and the output signals of the respective detectors are sent to the respective change speed calculators. The change speed of each detected value is calculated by each change speed calculator and sent to each function generator.
The output signal of each function generator is sent to a respective rate limiter. When the rate of change of the output signal of the function generator is equal to or more than a certain value, each rate-of-change limiter performs an operation for setting a predetermined rate of change, and sends the result to the maximum value selection calculator. An output signal from the flow detector is sent to a flow controller. In the flow controller, a signal q from the flow detector is input as a control signal, and the operation signal fc is sent to the maximum value selection calculator. The maximum value selection calculator selects the maximum value from one or more of the signals from the rate-of-change limiter and the output signal of the flow controller, outputs the control valve operation signal, and outputs the control signal. Sent to the valve. The control valve adjusts the valve opening according to the input. In this way, the compressor can be operated without entering the surging region.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the same reference numerals are given to portions that perform the same functions as those of the conventional technology, duplicate descriptions are omitted, and portions related to the present invention will be mainly described.

FIG. 1 is a diagram showing the overall configuration of the embodiment. As shown in the figure, in the present embodiment, the inlet pressure Ps of the compressor 1
A first pressure detector 12 is provided at the inlet to detect the pressure, a temperature detector 23 is provided at the inlet to detect the inlet temperature Ts of the compressor 1, and an inlet flow rate q of the compressor 1 is provided. A flow rate detector 10 is provided at the inlet for detecting the pressure, a speed detector 22 is provided for detecting the speed n of the compressor 1, and an outlet is provided for detecting the outlet pressure Pd of the compressor 1. Is provided with a second pressure detector 21, and outputs of the respective detectors 12, 23, 10, 22, and 21 are output from respective change speed calculators 24, 25, 26, and 2.
7, 28. Each change speed calculator 24,
The outputs of 25, 26, 27, 28 are sent to respective function generators 29, 30, 31, 32, 32. The outputs of the respective function generators 29, 30, 31, 32, 33 are sent to respective rate-of-change limiters 34, 35, 36, 37, 38. Each change rate limiter 34, 35, 36,
The outputs of 37 and 38 are all sent to the maximum value selection calculator 39. The output fe of the flow controller 11 is also sent to the maximum value selection calculator 39. The maximum value selection calculator 39 selects the maximum value from the input signals, and sends the selected signal to the control valve 6 installed in the pipe 7.

In the above configuration, the first pressure detector 1
At 2, the inlet pressure Ps of the compressor 1 is detected and sent to the change speed calculator 24. The change speed calculator 24 calculates the change speed Ps ′ of the inlet pressure and sends it to the function generator 29.
The function generator 29 calculates the change rate component of the inlet pressure only in the change direction of the inlet pressure to the surging, and sends the calculated change rate component to the change rate limiter 34. The rate-of-change limiter 34 calculates so as to limit the rate of change only when the rate of change of the inlet pressure decreases, and sends it to the maximum value selection calculator 39.

The temperature detector 23 detects the inlet temperature Ts of the compressor 1 and sends it to the change speed calculator 25. The change speed Ts' of the inlet temperature Ts is calculated by the change speed calculator 25 and sent to the function generator 30. The function generator 30 calculates the change speed component only for the change direction of the inlet temperature Ts to the surging, and sends it to the change rate limiter 35. The change rate limiter 35 calculates so as to limit the change rate only when the change rate of the inlet temperature decreases, and sends it to the maximum value selection calculator 39.

The flow rate detector 10 detects the flow rate q of the inlet of the compressor 1 and sends it to the change speed calculator 26. The change speed calculator 26 calculates the change speed q 'of the inlet flow rate,
Sent to function generator 31. The function generator 31 calculates the change rate component of the inlet flow rate only in the change direction of the inlet flow rate to the surging, and sends it to the change rate limiter 36. The change rate limiter 36 calculates so as to limit the change rate only when the change rate of the inlet flow rate decreases, and sends it to the maximum value selection calculator 39.

The rotation speed detector 22 detects the rotation speed n of the compressor 1 and sends it to the change speed calculator 27. A change speed calculator 27 calculates a change speed n ′ of the rotation speed n,
It is sent to the function generator 32. Number of rotations n by function generator 32
The change rate component of the number of rotations in only the direction of change to surging is calculated and sent to the change rate limiter 37. The change rate limiter 37 performs an operation so as to limit the change rate only when the change speed of the rotation speed n decreases, and sends the result to the maximum value selection calculator 39.

Further, the outlet pressure Pd of the compressor 1 is detected by the second pressure detector 21 and sent to the change speed calculator 28. The change speed calculator 28 calculates the change speed Pd ′ of the outlet pressure and sends it to the function generator 33. Function generator 33
, The change rate component of the outlet pressure in only the direction in which the outlet pressure changes to surging is calculated and sent to the change rate limiter 38.
The rate-of-change limiter 38 calculates so as to limit the rate of change only when the rate of change of the outlet pressure decreases, and sends it to the maximum value selection calculator 39.

The output fc of the flow controller 11 is sent to a maximum value selection calculator 39. Maximum value selection calculator 39
By selecting the maximum value from among the input signals, an operation signal is output which responds to a rapid change to surging and operates without entering the surging region. Sent to The control valve 6 adjusts the valve opening according to the input.

As shown in FIG. 2, the change speed calculators 24 and 2
Reference numerals 5, 26, 27, and 28 each include a filter and a differentiator. Also, function generators 29, 30, 31, 32, 3
3 has the characteristics shown in FIGS. 3A, 3B, 3C, 3D, and 3E.

Function generators 29, 30, 31, 32, 33
Is output only when the direction of the change speed of each state quantity is in the direction toward the occurrence of surging. That is, taking the inlet pressure Ps as an example, approaching the surging region means that the pressure increase ratio (= outlet pressure / inlet pressure) increases. Assuming that the outlet pressure is constant, as the inlet pressure decreases, it approaches the surging region. In other words, the function generator 29 outputs 1 when the change speed Ps 'becomes negative because the approach speed approaches the surging region when the change speed Ps' of the inlet pressure is directed in the negative direction.

The same applies to other state variables. In the case of the inlet temperature Ts, the inlet temperature change speed Ts 'increases, in the case of the inlet flow, the inlet flow change speed q' decreases, and in the case of the rotation speed. The function generators 30, 31, 32, and 33 output 1 in the direction in which the rotational speed change speed n 'decreases, and in the case of the outlet pressure Pd, the outlet pressure change speed Pd' increases.

FIG. 4 shows the change rate limiters 34, 35, 36, 3
7, 38 are shown. The rate-of-change limiter has a rate of change of the output signal y of the function generators 29, 30, 31, 32, and 33, which is an input signal, that is, a differential coefficient y 'of the input signal y is greater than a predetermined value of the rate of change in the negative direction. When the value becomes, a value obtained by subtracting the value corresponding to the default value is output as z. That is, the output z is determined by the following equations (1) and (2).

[0028]

(Equation 1)

Here, referring to FIG. 5 and FIG.
The behavior when the operation of the vehicle changes in the surging direction will be described.

First, the horizontal axis represents time, and the vertical axis represents state quantities (pressure,
The flow rate will be described with reference to FIG.

The compressor 1 is in operation, and the inlet pressure, the outlet pressure, the flow rate, and the rotation speed are rated up to the point A. At this time, since the compressor flow rate is larger than the set value, the opening of the control valve 6 is fully closed.

It is assumed that the outlet pressure of the compressor 1 increases rapidly at the point A. The reason for this is that, although the process downstream of the compressor 1 is stopped, the outlet pressure is rapidly increased because the rotation speed of the compressor 1 is constant even though the consumption flow rate of the process is rapidly reduced. And so on.

Thereafter, the outlet pressure increases rapidly and the flow rate decreases rapidly. At point E, the outlet pressure change speed calculator 28 outputs the outlet pressure change speed in the rising direction with the rapid rise of the outlet pressure, and the function generator 33 outputs the change speed in the forward direction. Are output, and the rate of change of the signal is in the positive direction (ascending direction) by the rate-of-change limiter 38, so that the function generator 3
3 is output as it is, and the maximum value selection arithmetic unit 3
9 is input.

In the maximum value selection calculator 39, the outputs of the rate-of-change limiters 34, 35, 36, 37, 38 and the flow controller 1
The maximum value is selected from the outputs of unity. At this time, the output of the flow controller 11 is small because the gain is small, and the maximum value selection calculator 39 selects the output of the change rate limiter 38 and adjusts the opening of the control valve 6. As a result, the opening of the control valve 6 rapidly increases. This causes the outlet pressure to drop rapidly and the flow to increase rapidly.

At point F, the rate of change of the outlet pressure is output by the rate-of-change calculator 28, and the rate of change of the outlet pressure in the descending direction is output. . The change rate limiter 38 receives the output signal of the function generator 33 as an input, but since the input signal is zero, outputs a signal reduced by a predetermined change rate to the maximum value selection calculator 39.

In the maximum value selection calculator 39, the flow controller 1
1 is small, the output signal of the change rate limiter 38 is selected and output to the control valve 6. Therefore, the control valve 6
, The opening gradually decreases. Accordingly, the outlet pressure gradually increases, and the flow rate gradually decreases.

At point G, the flow rate becomes smaller than the set value. However, since the output signal of the flow controller 11 is still smaller than the output signal of the change rate limiter 38, the outlet pressure gradually increases and the flow rate continues to decrease gradually.

At the point H, the output signal of the flow controller 11 becomes larger than the output signal of the rate-of-change limiter 38, so that the maximum value selection computing unit 39 selects the output signal of the flow controller 11 and adjusts it. The opening of the valve 6 increases again.

At the point I, the opening of the control valve 6 is adjusted so that the flow rate is maintained at the set value by the output signal of the flow controller 11.

FIG. 5 shows the operating state of the compressor 1 from the point A to the point I on a performance curve of the compressor. From FIG. 5, it can be seen that the compressor 1 is operated while avoiding the surging region despite the rapid change in the outlet pressure.

In the above embodiment, a flow controller to which a signal indicating the flow rate q is input is used as the controller. Instead, an inlet pressure Ps, a pressure increase ratio (outlet pressure Pd / inlet pressure Ps), A controller to which a signal indicating the number of revolutions n or the pressure ratio / flow rate is input may be used.

Further, even if not all the signals of the rate-of-change limiters 34, 35, 36, 37 and 38 are inputted to the maximum value selection computing unit 39, a part of them may be inputted. At that time, the detectors, the change speed calculators, the function generators, and the change rate limiters corresponding to the signal systems not used may be omitted.

[0043]

According to the present invention, the compressor can be operated without entering the surging region even if the outlet pressure rises rapidly as described in detail with the above embodiments.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a change speed calculator according to the embodiment;

FIG. 3 is a characteristic diagram showing an evaluation function of the function generator according to the embodiment.

FIG. 4 is an explanatory diagram showing a change rate limiter according to the embodiment.

FIG. 5 is a characteristic diagram showing a performance curve and an operation trajectory of the compressor of the embodiment.

FIG. 6 is a characteristic diagram illustrating a time change of a state quantity according to the embodiment.

FIG. 7 is a block diagram showing the entire configuration of a conventional technique.

FIG. 8 is a characteristic diagram showing a performance curve and an operation locus of a conventional compressor.

FIG. 9 is a characteristic diagram showing a time change of a state quantity in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Drive 3 Pipe 4 Pipe 5 Suction drum 6 Flow control valve 7 Pipe 10 Flow detector 11 Flow controller 12 First pressure detector 21 Second pressure detector 22 Rotation speed detector 23 Temperature detector 24, 25, 25, 27, 28 Change speed calculator 29, 30, 31, 32, 33 Function generator 34, 35, 36, 37, 38 Change rate limiter 39 Maximum value selection calculator Ps Inlet pressure Ts Inlet air Temperature q Inlet air flow rate n Rotational speed Pd Outlet pressure fc Controller output

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F04D 27/02

Claims (3)

(57) [Claims] 1. A compressor which pressurizes a gas sucked in from an inlet side and discharges the gas from an outlet side, and a pipe which recirculates gas from an outlet side to an inlet side of the compressor to interpose an operation signal inputted thereto. A first pressure detector for detecting an inlet pressure of a compressor, and an output signal of the detector for inputting an output signal of the detector. And a first change speed calculator for outputting a signal indicating the change in speed and a change component calculated and output only when the output signal of the change speed calculator is input and the direction of the change speed is in the direction toward the occurrence of surging. No. 1 function generator, a first change rate limiter that receives an output signal of the function generator and limits the rate of change only when the rate of change of the inlet pressure decreases, and detects the inlet temperature of the compressor. Input the temperature detector and the output signal of the detector A second change speed calculator for outputting a signal indicating the change speed of the output signal of the first and second shift speed calculators, and a change component is input only when the output speed of the change speed calculator is equal to the direction of the surging. A second function generator that calculates and outputs the output, a second change rate limiter that receives an output signal of the function generator and limits the rate of change only when the rate of change of the inlet temperature decreases, and the compressor. A flow rate detector for detecting the flow rate of suction into the apparatus, a third change rate calculator for receiving an output signal of the detector and outputting a signal indicating a change rate of the signal, and an output signal of the change rate calculator And a third function generator for calculating and outputting a change component only when the direction of the change speed is in a direction toward the occurrence of surging, and a change speed of the suction flow rate by inputting an output signal of the function generator. Third rate-of-change limiter that limits the rate of change only at the time of falling A rotation speed detector for detecting a rotation speed of the compressor, a fourth change speed calculator for receiving an output signal of the rotation speed detector and outputting a signal indicating a change speed of the output signal; A fourth function generator for inputting the output signal of the change speed calculator and calculating and outputting the change component only when the direction of the change speed is in the direction of the occurrence of surging; and inputting the output signal of the function generator A fourth rate-of-change limiter that limits the rate of change only when the rate of change in the number of revolutions falls; a second pressure detector that detects the outlet pressure of the compressor;
A fifth changing speed calculator for inputting an output signal of the detector and outputting a signal indicating a changing speed of the output signal; and a surging occurs in a changing speed direction by inputting the output signal of the changing speed calculator. A fifth function generator for calculating and outputting a change component only in the direction toward the second direction, and a fifth function for inputting an output signal of the function generator and limiting the rate of change only when the rate of change of the outlet pressure decreases. A rate-of-change limiter, a controller that receives an output signal of the flow rate detector and outputs a signal corresponding to the signal, and an output signal of the first rate-of-change limiter and a second rate-of-change limiter. One or more output signals of the output signal, the output signal of the third rate-of-change limiter, the output signal of the fourth rate-of-change limiter, and the output signal of the fifth rate-of-change limiter; Input the output signal and adjust the operation signal obtained based on the largest signal among them Control device of a compressor, characterized in that it comprises an, a maximum value selecting calculation for outputting a. 2. The controller according to claim 1, wherein, instead of the output signal of the flow rate detector, a signal indicating an output pressure is provided to the controller.
A signal indicating one of a signal indicating a pressure increase ratio obtained by dividing the outlet pressure by the inlet pressure, a signal indicating the number of revolutions of the compressor, and a signal indicating a value obtained by dividing the pressure increase ratio by the flow rate is input. Control device for compressor. 3. The detector according to claim 1, wherein each of the detectors, the change rate calculator, the function generator, and the change rate of the output signals of the first to fifth change rate limiters that are not input to the maximum value selection calculator are provided. A control device for a compressor, wherein a limiter is omitted.