Compressed air manufacturing equipment and its operating method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a compressed air production facility whose capacity can be controlled and an operation method thereof. In particular, a compressor that adjusts the compressor capacity by changing the rotation speed and a compressor that operates at a constant rotation speed are combined to have a capacity. Regarding the compressed air production equipment to be controlled and its operation method.

【0002】

[Conventional technology]

An example of a conventional compressed air production facility is disclosed in Japanese Patent Application Laid-Open No. 9-250485. In the compressor described in this publication, a pressure sensor for detecting the discharge pressure of compressed air is provided at the outlet of the compressor, and the rotation speed of the compressor is changed by using PID control to control the capacity of the compressor. There is.

【0003】

[Problems to be Solved by the Invention]

In the above-mentioned conventional technique, when the compressor is operated independently, the power consumption is significantly reduced as compared with the conventional method of controlling the capacity by keeping the rotation speed of the compressor constant. However, in a compressed air production facility that operates by connecting multiple compressors in parallel, although a certain degree of power saving effect can be obtained, a significant reduction in power consumption can be obtained compared to the conventional control of operating multiple compressors. There was a problem that there was no such thing.

【0004】

The present invention has been made in view of the above-mentioned defects of the prior art, and an object of the present invention is to reduce power consumption when operating a plurality of compressors in parallel in a compressed air production facility as much as possible. Another object of the present invention is to achieve power saving in a compressed air production facility without adopting a complicated configuration.

【0005】

[Means for solving problems]

The first feature of the present invention for achieving the above object is a variable speed in a compressed air production facility including at least one variable rotation speed compressor and at least one fixed rotation speed compressor. Means for merging the discharged air discharged from each of the compressor and the fixed speed compressor on the discharge side, a pressure detecting means for detecting the pressure of the merged discharged air, and the detected pressure and a preset pressure. A control means for stopping or starting the compressor is provided based on the above, and this control means stops the accelerating speed compressor after all the fixed speed compressors have stopped.

【0006】

The variable speed compressor is provided with a suction throttle valve, and the control device controls the capacity of the compressor by changing the rotation speed until the rotation speed of the variable speed compressor drops to a predetermined rotation speed. The capacity of the compressor is controlled by the suction throttle valve when the temperature is reached; a control valve for controlling the discharge pressure is provided in the vicinity of the merging means, and the control device operates the suction throttle valve when the variable speed compressor reaches a predetermined rotation speed. It is closed and controlled to reduce the discharge pressure using a control valve; it is desirable that the control device have a storage means that stores at least one step of starting and stopping the fixed speed compressor.

【0007】

Further, preferably, an individual discharge pressure detecting means for detecting the pressure of the discharged air discharged from each of the fixed speed compressor and the variable speed compressor is provided, and when a problem occurs in the discharge pressure detecting means, the individual discharge pressure detection is performed. The control device controls each compressor based on the detection pressure of the means.

【0008】

The second feature of the present invention for achieving the above object is a method of operating a compressed air production facility including at least one compressor having a variable rotation speed and a plurality of compressors having a fixed rotation speed. , The first control means for controlling the variable speed compressor is prioritized, and this first control means controls each of the plurality of fixed speed compressors and the second control provided for each fixed speed compressor. It sends start and stop commands to the means.

【0009】

And preferably, priority is given to each of the plurality of fixed speed compressors, and the first control means starts from the one with the highest priority at the time of starting and stops from the one with the lowest priority at the time of stopping. Execute; prioritize each of the plurality of fixed speed compressors, and the first control means executes rotary control in which control is started from the one with the highest priority both at the time of starting and at the time of stopping; When one of the multiple fixed speed compressors fails, the compressor with a higher priority than the failed compressor is given the same priority, and the compressor with a lower priority than the failed compressor is given the same priority. Reassign priorities below this failed compressor in order from the lowest priority compressor; when the variable speed compressor fails, each fixed speed compressor is independent of the second controller. It is designed to be controlled by.

【0010】

BEST MODE FOR CARRYING OUT THE INVENTION

Some embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the compressed air production facility according to the present invention. FIG. 2 is an example of a timing chart when operating the compressed air production facility shown in FIG. 1, and is an example of so-called turnback control. Further, FIGS. 5 to 7 are flowcharts of turnback control.

【0011】

This embodiment is a compressed air production facility equipped with a compressor driven by three electric motors, but it goes without saying that the number is not limited to three. Further, the compressor is premised on a screw compressor, but is not limited to this. A_CV, B_CC, C_CCAmong the three compressors consisting of Unit No. A_CVUnit No. is a variable speed compressor with a variable rotation speed of the electric motor. B_CCUnit and C_CCUnit No. is a compressor in which the rotation speed of the electric motor is constant. The air compressed by each compressor is collected at the outlet of each compressor, guided to the air tank 1, and supplied to the compressed air use line.

【0012】

Pressure sensor Z in air tank 1_SIs installed and this signal is from controller A_CIs taken in. Controller A_C, B_C, C_CThe control upper limit pressure H and the control lower limit pressure L are set in advance. In normal operation, pressure sensor Z_SDetected pressure and controller A_CThe control upper limit pressure H and the control lower limit pressure L stored in are constantly compared.

【0013】

In addition, control device A_C, B_C, C_CThe order of the compressors to be operated is set in advance. For example, A_CVUnit (top machine) to C_CCTo Unit (lowest machine) A_CV B_CC C_CCDrive in the order of. If the pressure in the air tank is higher than the control lower limit pressure L and less than the control upper limit pressure H during the operation of the compressor, the compressor A_CVUnit controls capacity including rotation speed control, and compressor B_CCUnit and C_CCUnit will operate at full load without capacity control. Pressure sensor Z indicates that the pressure in the air tank 1 has exceeded the control upper limit pressure H_SIs detected, controller A_CStarts the A timer integration.

【0014】

Control device A from the start of integration_CWhen the preset time elapses in, controller A_CFrom controller B_CAnd controller C_CFinally, through the controller C in this order._CCompressor C_CCA command to generate a signal to stop the unit is sent, and control device C_CIs the compressor C_CCStop Unit. If the pressure drops below the control upper limit pressure H before issuing the signal to stop the compressor, the A timer is reset to 0. Each time the consumption amount is smaller than the amount of air discharged from the compressed air production facility and the pressure reaches the control upper limit pressure H, this operation is repeated and the compressors at the ends are sequentially stopped.

【0015】

On the contrary, the pressure sensor Z_SWhen it detects that the pressure is less than or equal to the control lower limit pressure L, controller A_CStarts the B timer integration. Control device A from the integration start time_CWhen the preset time elapses, the order opposite to the stop order, that is, the command to start the compressor from the upper side is issued to the control device A._CCommand. And the compressor to start is compressor A_CVIn the case of No. 1, compressor A_CVCapacity control of Unit including rotation speed control. The compressor to start is compressor B_CCIf it is on the terminal side of Unit, operate at full load. If the pressure exceeds the control lower limit pressure L before starting the compressor, the B timer is reset to 0. Here, the setting time of the A timer and the B timer can be arbitrarily set in consideration of the stability of the compressed air production equipment and the like.

【0016】

Compressor A for capacity control_CVUnit is operated by changing the rotation speed so that the pressure becomes constant. Compressor A_CVAs shown in Fig. 2, the variable rotation speed range of Unit is set to 30 to 100%. This control pressure is set to an arbitrary pressure between the control lower limit pressure L and the control upper limit pressure H. This pressure is also pressure sensor Z_SDetect with. The state of the above control is detailed in the flowcharts shown in FIGS. 5 to 7, but FIG. 5 shows compressor A._CVIt is a flowchart about the operation of the unit, and Fig. 6 shows the compressor B._CCFlowchart for Unit operation, Figure 7 shows Compressor C_CCIt is a flowchart about operation of Unit. When the number of compressors in operation reaches four or more, the compressor C shown in FIG. 7_CCFollow the same procedure as the control flowchart of the unit, and each compressor D_CC, E_CC, ... is controlled.

【0017】

FIG. 3 shows a timing chart when the compressed air production facility is controlled by using a control method different from that of the above embodiment. The equipment shown in Fig. 1 is used as the compressed air equipment. This control method is a so-called rotary control. 8 and 9 show a flowchart during rotary control.

【0018】

Controller A_C, B_C, C_CHas both a turnback control function and the following rotary control functions. Each controller A_C, B_C, C_CThe order of the compressors to start and stop is preset. For example, compressor A_CVStart Unit (top unit), then Compressor B_CCUnit, then compressor C_CCUnit (lowest machine) A_CV B_CC C_CCThe point of starting in order is the same as the above turnback control.

【0019】

If the pressure in the air tank is higher than the control lower limit pressure L and less than the control upper limit pressure H during the operation of the compressor, the compressor A_CVCapacity control including rotation speed control for Unit No. Compressor B_CCUnit and compressor C_CCIt is the same as the above turnback control in that the unit is operated at full load without capacity control. However, when the capacity control operation is started, the compressor A that can control the rotation speed_CVCompressor B at all times, except for Unit_CCCompressor C first_CCStart or stop Unit later. That is, when the capacity decreases, the compressor B_CCStop Unit 1 first, Compressor C_CCStop Unit later. In addition, the operation can be resumed with compressor B._CCStart Unit first, Compressor C_CCThe unit will be started later. The details are shown below.

【0020】

Pressure sensor Z indicates that the pressure in the air tank 1 has exceeded the control upper limit pressure H_SIs detected, controller A_CStarts the A timer integration. Control device A from the start of integration_CWhen the preset time elapses in, controller A_CHowever, controller B_CAnd controller C_CCompressor A via each control device in the order of_CVA command to stop the compressor is sent to the control device of the next unit of the last stopped unit except the unit, and the compressor of this unit is stopped. If the last stopped machine is the last machine (lowest machine), compressor B_CCReturn to Unit. Compressor A_CVWhen all compressors except Unit 3 are stopped, Compressor A_CVStop Unit. If the pressure drops below the control upper limit pressure H before issuing the signal to stop the compressor, the A timer is reset to 0. Every time the consumption amount decreases from the amount of air discharged from the compressed air production facility and the pressure reaches the control upper limit pressure H, this operation is repeated and the compressor is sequentially stopped.

【0021】

On the contrary, the pressure sensor Z indicates that the pressure has fallen below the control lower limit pressure L._SIs detected, controller A_CStarts the B timer integration. From the integration start time, controller A_CAfter the preset time has elapsed, controller A_CFrom controller B_C, Then controller C_CCompressor A via each control device in the order of_CVA command to start the compressor is sent to the control device of the next unit after the last started unit except the unit. Then, the control device corresponding to the stop command stops the corresponding compressor.

【0022】

Here, the last started machine is the last machine (lowest machine), or it is still compressor B._CCCompressor B if everything is not in operation after Unit B_CCStop Unit. Compressor A_CVCompressor A when Unit is stopped_CVStart Unit.

【0023】

The started compressor is compressor A_CVIn the case of Unit, capacity control including rotation speed control is performed, and compressor B_CCIn the case of Unit and after, full load operation is performed. If the pressure exceeds the control lower limit pressure L before starting the compressor, the B timer is reset to 0. Regarding the above control, the details of the flowchart are shown in FIGS. 8 and 9.

【0024】

Figure 8 shows compressor A_CVThe flow chart of the control related to the unit, and Fig. 9 is typically the compressor B._CCIt shows the flow chart of the control about the unit. Compressor C_CCFor Unit, the control flowchart is the same as in FIG. When the number of compressors is 4 or more, the flow chart for controlling the increased amount is the same as in FIG. Furthermore, FIG. 3 is a control timing chart, and compared to the turnback control shown in FIG. 2, compressor B_CCUnit and C_CCThe characteristic of rotary control is that the start and stop timings of Units are different. Also in the rotary control shown in Fig. 3, compressor A_CVThe rotation speed control range of Unit is set to 30 to 100%.

【0025】

Turnback control is effective when adopted when the maximum discharge air amount of each compressor is different, and compressor A_CVFrom models with a large maximum discharge air volume of other compressors except Unit B_CCUnit, C_CCIt is better to set in order with the unit. On the other hand, rotary control is for compressor A._CVSince the operating time of each compressor except the No. 1 compressor can be averaged, it is particularly effective when a plurality of almost the same compressors are used.

【0026】

Compressor A_CVIf a compressor other than the No. 1 compressor fails, the control device of the failed compressor is disconnected from the turnback control or rotary control control system. At this time, regarding the start / stop of the compressor of the unit whose priority is lower than that of the failed compressor, the compressor A_CVThe priority is sequentially from the lowest priority so that the command from the unit is transmitted to the control device of the compressor with the lowest priority, then the control device of the compressor one before the lowest priority, and so on. It goes through the upper control device.

【0027】

Pressure sensor Z_SIn case of failure, pressure sensor Z_SIs disconnected from the above turnback control or rotary control control system, and the pressure related to control is reduced to the compressor A._CVUnit pressure sensor A_STo detect with. Furthermore, pressure sensor A_SIn case of failure, pressure sensor A_SAlso disconnected from the control system and the pressure related to control is compressed B_CCUnit pressure sensor B_STo detect with. In this case, controller B_CFrom controller A_CThe pressure detection value is transmitted to the controller A._CControls based on its pressure value. As a result, the capacity of the compressed air production equipment can be stably controlled until all the pressure sensors of the compressed air production equipment fail.

【0028】

Compressor A_CVIf Unit fails, disconnect all compressors from the control system. And compressor A_CVThe capacity of each compressor other than Unit is controlled independently by the pressure sensor that each compressor has.

【0029】

Figures 10 and 11 show the amount of air used Q and the power consumption L for one compressor used in this compressed air production facility._DThe relationship is shown. In these figures, the amount of discharged air at full load is normalized to 100%, and the power consumption of the compressor at that time is normalized to 100%.

【0030】

FIG. 10 is a diagram showing a change in power consumption when the rotation speed of the compressor is kept constant and the opening degree of the throttle valve provided on the suction side of the compressor is changed to adjust the flow rate. FIG. 11 is a diagram showing a change in power consumption when the flow rate of the compressor is adjusted by using a compressor having a variable rotation speed. When the amount of air is in the range of 30% to 100%, the rotation speed is controlled, and in the range of the amount of air of 30% or less, the flow rate is adjusted by the same suction throttle as in FIG. When using only one compressor, the combined rotation speed control shown in Fig. 11 is significantly superior in capacitance control characteristics. Then, the power consumption when the load fluctuates can be greatly improved.

【0031】

By the way, if five suction throttle type compressors with a constant rotation speed are used, only one of them is capacity-controlled, and the others are operated at full load, the power consumption shown in Fig. 4 II. It becomes a characteristic. This is a control method widely used as a conventional method for controlling the number of compressors.

【0032】

Further, by simply operating five compressors with variable rotation speeds in parallel, the power consumption characteristics shown by I in FIG. 4 can be obtained. In the comparison between I and II in Fig. 4, the power consumption of II is partially lower than that of II, and it can be said that the control method by variable rotation speed is superior to the suction throttle control in terms of power saving. Absent.

【0033】

On the other hand, since the compressed air production equipment of the present invention is provided with one compressor having a variable rotation speed and a plurality of compressors having a constant rotation speed, the power consumption characteristics shown in III in FIG. Can be obtained. That is, even in a compressed air production facility equipped with a plurality of compressors, it is possible to obtain an ideal power consumption characteristic in which the power consumption decreases substantially linearly with respect to the amount of air consumption.

【0034】

In this case, compared with the method II in which five compressors with variable rotation speeds are used, the inclined portion in FIG. 4 saves power. Specifically, when five 37 kW compressors are used, the embodiment of the present invention saves up to 18 kWh of power. This corresponds to the difference between the point P in FIG. 10 and the point Q in FIG. This comparison is for five compressors, but it goes without saying that even if the number of compressors is other than this, power saving will be achieved according to the number of compressors.

【0035】

In addition, since the compressor with variable rotation speed can be controlled so that the discharge pressure is set to a constant value, if this set pressure is set slightly higher than the control lower limit pressure L, unnecessary pressure rise will occur. It is possible to prevent and reduce power consumption in this respect as well.

【0036】

[Effect of the invention]

According to the present invention, in a compressed air production facility having a plurality of compressors, the power consumption can be almost linearly generated in response to a decrease in the amount of air used by simply providing the minimum number of compressors having variable rotation speeds. It becomes possible to reduce it, and wasteful power consumption due to capacity control can be reduced.

[Simple explanation of drawings]

[Figure 1]

The block diagram of the Example of the compressed air production facility which concerns on this invention.

[Figure 2]

The time chart when the turnback control of the embodiment shown in FIG. 1 is performed.

[Fig. 3]

A time chart of the example shown in Fig. 1 when rotary control is performed.

[Fig. 4]

The figure explaining the power consumption characteristic of a compressed air production facility.

[Fig. 5]

The flowchart at the time of turnback control of the Example shown in FIG.

[Fig. 6]

The flowchart at the time of turnback control of the Example shown in FIG.

[Fig. 7]

The flowchart at the time of turnback control of the Example shown in FIG.

[Fig. 8]

The flowchart at the time of rotary control of the Example shown in FIG.

[Fig. 9]

The flowchart at the time of rotary control of the Example shown in FIG.

[Fig. 10]

The figure explaining the power consumption characteristic of a compressor.

[Fig. 11]

The figure explaining the power consumption characteristic of a compressor.

[Explanation of symbols]

1 ... Pneumatic trough, A_S, B_S, C_S, Z_S...pressure sensor, A_C, B_C, C_C...Control device, A_CV... variable speed compressor, B_CC, C_CC, D_CC, E_CC... fixed speed compressor, H ... Control upper limit pressure, L ... Control lower limit pressure.