JP2018116565A - Compression air supply control device and compression air supply control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve power saving when a plurality of air pressure compressors are used.SOLUTION: A compression air supply control device comprises: an air pressure common pipe 2 for supplying compressed air discharged from a plurality of air pressure compressors 1 to a compressed air use facility 3; and a plurality of control mechanisms 4 for respectively controlling the plurality of air pressure compressors 1. Each control mechanism includes: a first operation amount setting unit 9 for calculating an opening operation amount of an intake valve 7 so as to adjust the armature current of a motor of the air pressure compressor 1 to set current that is preset; a second operation amount setting unit 10 for calculating an opening operation amount of the intake valve 7 so as to adjust the discharge pressure of the air pressure compressor 1 to set discharge pressure that is preset on the basis of a measurement value of the discharge pressure; an operation amount selection unit 11 for selecting a smaller amount between two opening operation amounts; and an intake value adjustment unit 12 for adjusting an opening of the intake valve 7 to the opening operation amount selected by the operation amount selection unit 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for supplying compressed air to a common compressed air use facility (process) using a plurality of compressed air compressors.

  As a conventional compressed air supply technique, for example, there is a technique described in Patent Document 1. In the technique described in Patent Document 1, pressures at a plurality of points in a compressed air pipe are constantly measured, a point at which a deviation between a set pressure and a measured pressure at each measurement point is maximized is selected, and the point becomes equal to or higher than the set pressure. Thus, the discharge pressure of the compressed air compressor is controlled.

Japanese Patent Laid-Open No. 9-138710

However, the pressure at multiple points in the compressed air piping that is sending compressed air is constantly measured, and the point where the deviation between the set pressure and the measured pressure at each measurement point is maximized is selected, and the set pressure or higher is selected at the selected point. In the low selector control that adjusts the pressure to be stable, stable supply of compressed air can be achieved, but the supply pressure tends to increase as a whole.
The present invention has been made paying attention to the above points, and aims to save power when supplying compressed air to a common compressed air use facility using a plurality of compressed air compressors. To do.

  In order to solve the problem, a compressed air supply control device according to one aspect of the present invention includes a compressed air common pipe that supplies compressed air discharged from a plurality of compressed air compressors to a facility that uses compressed air, and a plurality of compressed air compressors. A plurality of control mechanisms for controlling, each of the control mechanisms includes a suction valve that adjusts an amount of air sucked from a suction port of the compressed air compressor, and a pressure gauge that detects a discharge pressure of the compressed air discharged from the compressed air compressor. A first operation amount setting unit for obtaining an opening operation amount of the suction valve for adjusting an armature current of a motor of the compressed air compressor to a preset set current, and a compressed air compressor based on a measured value of the pressure gauge A second operation amount setting unit for obtaining an opening operation amount of the suction valve for adjusting the discharge pressure of the suction valve to a preset set discharge pressure; The operation amount selection unit for selecting a smaller value among the opening operation amount obtained by the operation amount setting unit and the opening operation amount obtained by the second operation amount setting unit, and the opening selected by the operation amount selection unit. A suction valve adjusting unit that adjusts the opening degree of the suction valve toward the operation amount.

  The compressed air supply control method according to one aspect of the present invention is a method of supplying compressed air discharged from a plurality of compressed air compressors to a common compressed air use facility when air is sucked from an intake port of each compressed air compressor. A suction valve that adjusts the amount, and a first opening operation amount that is an opening operation amount of the suction valve for adjusting the armature current of the motor of the compressed air compressor to a preset set current; A second opening operation amount that is an opening operation amount of the suction valve for adjusting the discharge pressure to a preset set discharge pressure is obtained, and the first opening operation amount and the second opening amount are obtained. The opening of the suction valve is adjusted toward a small opening operation amount of the operation amount.

  According to one aspect of the present invention, by adopting a low selector control of an opening operation amount that is adjusted to a set discharge pressure and an opening operation amount that is used to adjust the consumption of a compressed air compressor to a set current, compressed air is supplied to the entire facility. It is possible to save power when supplying.

It is a figure explaining the compressed air supply control apparatus which concerns on embodiment based on this invention. It is a figure which shows the example of a track record of an electric power basic unit.

Next, embodiments of the present invention will be described with reference to the drawings.
The compressed air supply control method of the present embodiment is configured to adjust the amount of air sucked from the suction port of each compressed air compressor when supplying compressed air discharged from a plurality of compressed air compressors to a common compressed air use facility. A first opening operation amount that is an opening operation amount of a suction valve for adjusting the armature current of the motor of the compressed air compressor to a preset set current, and a discharge pressure of the compressed air compressor are preset. A second opening operation amount that is an opening operation amount of the suction valve for adjusting to the set discharge pressure is obtained, and a small opening amount of the first opening operation amount and the second opening operation amount is obtained. The opening degree of the suction valve is adjusted toward the operation amount.

An example of a compressed air supply control device that realizes the supply control will be described below.
The compressed air supply control device of this embodiment has a plurality of compressed air compressors 1 as shown in FIG. The number of compressed air compressors 1 used (operated) while the operator observes the use status of compressed air (the amount of air supplied to the compressed air use facility 3) in the compressed air use facility 3 (steel process equipment, etc.) Adjust.
The number of units used is, for example, the difference between the sum of the air supply capacities of the operating compressed air compressors 1 and the current air supply amount actually supplied to the compressed air use facility 3 (also referred to as an air supply margin amount). When the air supply margin amount is less than or equal to the predetermined value, the number of the compressed air compressors 1 to be operated is increased.

(Constitution)
The compressed air discharged from the plurality of compressed air compressors 1 is configured to be supplied to the compressed air using facility 3 that uses the compressed air through the compressed air common pipe 2.
Each compressed air compressor 1 is configured to be controlled by an individual control mechanism 4. Each of the compressed air compressors 1 may be controlled at a constant rotational speed in which the rotational speed of the impeller is constant, or may be controlled in a variable speed so that the discharge pressure becomes equal to or higher than a set minimum pressure.
The individual control mechanism 4 will be described. As shown in FIG. 1, the air introduction pipe 5 is connected to the suction port of the compressed air compressor 1 and the compressed air common pipe 2 is connected to the discharge port of the compressed air compressor 1. The discharge side pipe 6 is connected.

As shown in FIG. 1, each control mechanism 4 includes a suction valve 7, a pressure gauge 8, a first operation amount setting unit 9, a second operation amount setting unit 10, an operation amount selection unit 11, and a suction valve adjustment unit. 12 is provided. In FIG. 1, reference numeral 20 denotes a manual valve.
The suction valve 7 is provided in the middle of the air introduction pipe 5, and adjusts the flow path cross section of the air introduction pipe 5 to an opening degree corresponding to the opening degree command value from the suction valve adjustment unit 12. As a result, the amount of air sucked into the compressed air compressor 1 through the atmosphere introduction pipe 5 is adjusted.
The pressure gauge 8 measures the discharge pressure of the compressed air compressor 1 by detecting the pressure in the discharge side pipe 6.

The first operation amount setting unit 9 detects an armature current (hereinafter also referred to as a detection current) of the driving motor corresponding to a load current that rotationally drives the impeller in the compressed air compressor 1, and the detected armature current Obtains a first opening operation amount MT1 for the opening amount of the suction valve 7 for adjusting to a preset set current.
The first operation amount setting unit 9 obtains the first opening operation amount MT1 by the following equation (1), for example.
First opening manipulated variable MT1 = current opening of the suction valve 7
+ K1 x (Setting current-Detection current)
... (1)
Here, k1 is a positive coefficient for converting the current into the amount of opening.

When this equation (1) is adopted, when the detected current is lower than the set current, a first opening manipulated variable MT1 that increases the opening by an amount corresponding to the current difference is calculated. Is higher than the set current, a first opening manipulated variable MT1 for reducing the opening by an amount corresponding to the current difference is calculated.
The value of the coefficient k1 may be different depending on whether (set current−detection current) is a positive value or a negative value.
The set current is, for example, a rated current.

The second manipulated variable setting unit 10 is configured to adjust the discharge valve 7 for adjusting the discharge pressure of the compressed air compressor 1 to a preset set discharge pressure based on the measured value of the pressure gauge 8 (hereinafter also referred to as a detected discharge pressure). A second opening operation amount MT2 is obtained as the opening amount.
The second operation amount setting unit 10 obtains the second opening operation amount MT2 by, for example, the following equation (2).
2nd opening manipulated variable MT2 = current opening of suction valve 7
+ K2 x (set discharge pressure-detected discharge pressure)
... (2)
Here, k2 is a positive coefficient for converting the pressure into the opening amount.

When this equation (2) is adopted, when the detected discharge pressure is lower than the set discharge pressure, a second opening manipulated variable MT2 that increases the opening by an amount corresponding to the discharge pressure difference is calculated. When the detected discharge pressure is higher than the set discharge pressure, a second opening operation amount MT2 that reduces the opening by an amount corresponding to the discharge pressure difference is calculated.
The value of the coefficient k2 may be different depending on whether the (set discharge pressure−detected discharge pressure) is a positive value or a negative value.
The operation amount selection unit 11 is a smaller value between the first opening operation amount MT1 obtained by the first operation amount setting unit 9 and the second opening operation amount MT2 obtained by the second operation amount setting unit 10. Select. That is, the operation amount selection unit 11 performs a select low of the two opening operation amounts MT1 and MT2.

The suction valve adjustment unit 12 adjusts the opening of the suction valve 7 toward the opening operation amount selected by the operation amount selection unit 11. The opening degree of the suction valve 7 is output to the first operation amount setting unit 9 and the second operation amount setting unit 10.
Here, although the case where the pressure gauge 8 is provided for each of the compressed air compressors 1 is illustrated in the above description, the pressure gauges 8 common to the plurality of compressed air compressors 1 are provided in the compressed air common pipe 2, and the pressure gauges 8 A detection value may be adopted. In this case, the pressure detected by the pressure gauge 8 is not the discharge itself of each compressed air compressor 1 but the pressure of the compressed air blown to the compressed air use facility 3. In this case, the second operation amount setting unit 10 is a common setting unit for the plurality of control mechanisms 4.

(Operation other)
When the amount of compressed air used in the compressed air use facility 3 is small, the amount of air supplied is small, so the load on each compressed air compressor 1 is small. For this reason, since the detected current is smaller than the set current, the first opening operation amount MT1 is set larger than the current opening as the current load is smaller. On the other hand, the pressure detected by the pressure gauge 8 approaches the set discharge pressure, so that the second opening operation amount MT2 becomes a value close to the current opening. That is, the second opening operation amount MT2 is smaller than the first opening operation amount MT1.

As a result, the opening amount of the suction valve 7 is adjusted by the second opening operation amount MT2, that is, the opening amount of the suction valve 7 is adjusted to the set discharge pressure. Specifically, when the detected discharge pressure is smaller than the set discharge pressure, the opening amount of the suction valve 7 is adjusted to increase, and when the detected discharge pressure is larger than the set discharge pressure, the suction valve 7 is adjusted. The amount of opening is adjusted to be smaller and the discharge pressure is feedback-controlled to the set discharge pressure.
Further, from this state, as the amount of compressed air used in the compressed air using facility 3 increases, the detected discharge pressure becomes smaller than the set discharge pressure, and the second opening operation amount MT2 gradually increases. Since the load of the compressed air compressor 1 increases, the detected current approaches the set current, and the first opening operation amount MT1 gradually decreases.

When the first opening degree manipulated variable MT1 becomes smaller than the second opening degree manipulated variable MT2 and the amount of compressed air used in the compressed air use facility 3 further increases, the load of the compressed air compressor 1 is increased. A transition is made to a control state in which the opening amount of the suction valve 7 is adjusted by the first opening operation amount MT1 corresponding to the current (armature current).
Specifically, in a state where the detected current is smaller than the set current, the opening amount at which the detected current becomes the set current is gradually adjusted in the direction in which the opening amount of the suction valve 7 is increased to increase the air supply amount. In addition, the opening amount of the suction valve 7 is controlled. That is, since it is possible to supply air to near the maximum value of the electric capacity set for each compressor 1, it is possible to suppress the number of compressors 1 to be used as compared with the conventional case.

Here, the density of air varies depending on the temperature, and the lower the temperature, the higher the density of the air. Therefore, pressure fluctuations occur depending on the temperature. Therefore, in the case of only the discharge pressure control configuration in which the opening degree of the suction valve 7 is adjusted so that the second opening operation amount MT2, that is, the discharge pressure of the compressor becomes the set discharge pressure (hereinafter also referred to as comparison control). In view of the pressure fluctuation, the maximum current value set for each compressor must be set smaller than the rated current on the safe side.
On the other hand, in the present embodiment, when the necessary air supply amount increases, the opening degree is controlled by the load current (armature current) of the compressor 1, so that the set current is set to the rated current, and the comparison control is performed. The electric capacity can be used up to the maximum value. For this reason, even if the amount of air supply increases, the number of operating compressors can be suppressed as compared with the comparative control. That is, power saving can be achieved.

Here, the performance of the power consumption rate of the compressed air compressor 1 for the air supply to the same compressed air using facility 3 was obtained for two years. The results are shown in FIG. In FIG. 2, the range of the symbol A is a period in which the comparison control is adopted, and the range of the symbol B is a period in which the control of the present embodiment is adopted.
As described above, the number of compressed air compressors to be operated was changed based on the air supply margin.
As can be seen from FIG. 2, in the case of comparative control, it can be seen that the power intensity varies with the season and that the power intensity is larger than the control of the embodiment. That is, it can be seen that the control of the embodiment can reduce the power consumption rate throughout the year, and hence the number of compressed air compressors to be used can be reduced.
Here, although it is assumed that the discharge pressure in each compressed air compressor 1 varies, the pressure gauge detects the pressure of the compressed air actually supplied to the compressed air use facility 3 to supply air. It becomes possible to suppress the pressure fluctuation when the amount is small.

DESCRIPTION OF SYMBOLS 1 Compressed air compressor 2 Compressed air common piping 3 Compressed air use equipment 4 Control mechanism 5 Atmospheric introduction pipe 6 Discharge side piping 7 Suction valve 8 Pressure gauge 9 First operation amount setting unit 10 Second operation amount setting unit 11 Operation amount selection unit 12 Suction Valve Adjustment Unit MT1 First Opening Operation Amount MT2 Second Opening Operation Amount

Claims (4)

A compressed air common pipe that supplies compressed air discharged from a plurality of compressed air compressors to a facility that uses compressed air, and a plurality of control mechanisms that respectively control the plurality of compressed air compressors,
Each of the above control mechanisms
A suction valve for adjusting the amount of air sucked from the suction port of the compressed air compressor;
A pressure gauge for detecting the discharge pressure of the compressed air discharged from the compressed air compressor;
A first operation amount setting unit for obtaining an opening operation amount of the suction valve for adjusting an armature current of a motor of a pneumatic compressor to a preset setting current;
A second operation amount setting unit for obtaining an opening operation amount of the suction valve for adjusting a discharge pressure of the compressed air compressor to a preset set discharge pressure based on a measurement value of the pressure gauge;
An operation amount selection unit that selects a smaller value among the opening operation amount obtained by the first operation amount setting unit and the opening operation amount obtained by the second operation amount setting unit;
A compressed air supply control device, comprising: a suction valve adjustment unit that adjusts an opening of the suction valve toward an opening operation amount selected by the operation amount selection unit.   The compressed air supply control device according to claim 1, wherein the set current is a rated current of the motor.   The compressed air supply control device according to claim 1, wherein the pressure gauge detects a pressure of the compressed air common pipe. When supplying compressed air discharged from multiple compressed air compressors to common compressed air equipment,
Equipped with a suction valve that adjusts the amount of air sucked from the suction port of each compressed air compressor,
A first opening operation amount that is the opening operation amount of the suction valve for adjusting the armature current of the motor of the compressed air compressor to a preset set current, and a set discharge pressure in which the discharge pressure of the compressed air compressor is set in advance. A second opening operation amount that is an opening operation amount of the suction valve to adjust to
A compressed air supply control method, characterized by adjusting an opening of the suction valve toward a smaller opening operation amount of the first opening operation amount and the second opening operation amount.

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