JPS63198794A - Controller for following-up load fluctuation in pneumatic machinery - Google Patents

Abstract

PURPOSE:To reduce any loss of power by separating the operation of capacity adjustors from the press-feed state based on a discharge pressure when the operating point of a compressor reaches a blow control line relating to the operating limit of the capacity adjustors. CONSTITUTION:By means of a pressure controller 6 are operated capacity adjustors 3-a, 3-b on the suction sides of respective independent compressing mechanisms 10-1, 10-b so as to control press-feed quantity in such as way as to keep the pressure in a press-feed main pipe 5 constant. When a load decreases and an operating point reaches a capacity control line 12, a pressure control signal from the pressure controller 6 is cut and the capacity adjustors 3-a, 3-b are held so as to be separated from the press-feed state so that blowers 8-a, 8-b are opened to release gas. Therefore, it is possible to prevent a blowing operation in the press-feed state even in the region beyond the quantity decreasing range of a booster at the time of decreasing the load, thereby reducing any loss of power.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a load fluctuation follow-up control device for air machinery, and in particular to a pressure boosting mechanism used in gas pumping equipment with severe load fluctuations, such as a compressor load control device. The present invention relates to a load fluctuation follow-up control device for an air machine suitable for fluctuation follow-up control.

[Conventional technology]

Generally, in gas pressure transmission equipment used for multiple purposes,
Multiple compressors are used in the piping system of such gas pumping equipment, where load usage fluctuates widely but pressure is often kept constant, and the capacity or number of compressors changes depending on load fluctuations. need to be adjusted.

In order to adjust the capacity, the compressor has a capacity adjustment device, and the means for capacity control in the case of a centrifugal compressor will be explained with reference to FIGS. 3 and 4.

Here, FIG. 3 is a system diagram of a compressor capacity control device in a conventional gas pumping facility, and FIG. 4 is an operating point characteristic diagram of the compressor in FIG. 3.

As shown in FIG. 3, in conventional gas pressure feeding equipment, a plurality of compressors 1, 2, . ...is controlled.

That is, when the load decreases, the pressure in the pressure main pipe 5 increases, so the pressure control device 6 adjusts the capacity adjustment device (for example, suction valve) 3 to reduce the amount of pressure delivered by each compressor 1, 2. , 4 are narrowed down. As a result, the operating point of the compressor shifts from point A to point B on the constant air pressure, as shown in Figure 4, and when the pressure is further reduced, the boundary becomes the surging region. It will move to point 0, which is the intersection with line (hereinafter referred to as surge line) 11.

On the other hand, in order to prevent operation in the surge line 11, a so-called air discharge control line 1 is installed in front of the surge line 11, which releases pressurized air to the atmosphere and performs no-load operation.
2' is provided to prevent the compressor from operating on the smaller air volume side than point D on the air blowing control line 12', as shown in FIG. 73! (For example, a blow-off valve) 8 is controlled by a blow-off control device @7 to release gas.

During this operation, if the total amount of gas discharged from the air blowing device 8 of each compressor exceeds the capacity of any of the compressors, the relevant compressor is stopped and the compressor is Adjust the number of vehicles in operation.

Regarding this type of device, Japanese Patent Application Laid-Open No. 1986-
[Problems to be solved by the invention] The above-mentioned conventional control device b! If there is a large fluctuation range in the number of load used in a certain plant, etc., during a transition period when adjusting the number of operating compressors in the gas pressure piping system, air is discharged under the pressure state, resulting in power loss, and load fluctuations. If f is repeated frequently, the frequency of starting and stopping the compressor increases, which causes the problem of troublesome operation management and the problem of shortening the mechanical life of the equipment.To prevent this, There was a problem in that the ventilation operation had to be continued.

The present invention was made in order to solve the problems of the above-mentioned Juto technology, and it expands the control range of the pressure boosting mechanism (for example, a compressor) in gas pressure feeding equipment where the load fluctuates, and reduces the pressure of the pressure boosting mechanism when the load is reduced. To provide a load fluctuation follow-up control device for an air machine, which can prevent group 1!1i1i$1 rotation in a pumping pressure state even in an area exceeding the width, reduce power loss, and improve the mechanical life of the device. Its purpose is to

[Means for solving problems]

In order to achieve the above object, the configuration of the load fluctuation follow-up control device for an air machine according to the present invention includes a multi-shaft parallel pressure boosting mechanism having a plurality of suction ports in a gas pressure transmission piping system subject to load fluctuations. A capacity control device is provided for narrowing down the operating point of the pressure boosting mechanism during capacity control operation of the pressure boosting mechanism by separating it from the pumping pressure state set by the capacity adjusting devices respectively equipped at the plurality of suction ports. .

As an additional note, the above purpose is to increase the capacity to separate each boosting mechanism from the pumping pressure state in, for example, a multi-shaft parallel compressor in which a single drive machine can drive multiple boosting mechanisms with independent suction ports. This is achieved by employing a control mechanism.

[Effect]

By throttling the capacity adjusting device installed on the suction side of the pressure boosting mechanism of the compressor, the air volume-air pressure characteristic curve of the compressor decreases both the air volume and the pressure, as shown in FIG. 4 above. Therefore, when the load decreases during load fluctuations, the operating point of the compressor is to reduce the capacity adjustment device to the point where it intersects with the air discharge control line at the pumping state pressure, and then narrow it down further, the pressure will drop below the pumping state pressure. At the same time, in a state where the air volume also decreases, the compressor discharge gas can be separated from the pumping shape 711 by discharging it to the atmosphere or the suction side via the air blowing device. In this operating state, the amount of work is reduced compared to the pressure-feeding, pressure-discharging state, so power loss can be saved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a system diagram of a capacity control device for a two-shaft parallel compressor according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of operating points of the compressor in FIG. 1. In FIG. 1, the same reference numerals as in FIG. 3 indicate parts equivalent to those of the conventional device.

The device shown in FIG. 1 is related to gas pressure feeding equipment, similar to the device shown in FIG. 3 which explained the prior art. ) is controlled, and in the figure, solid line arrows indicate the flow of gas, and broken line arrows indicate the control signal system.

Note that the pressure control device [¥6] controls so that the deviation between the set pressure and the measured pressure becomes 0. For example, a pressure indicating regulator is used, and 6a is a pressure converter that converts the process pressure into an electronic signal.

In FIG. 1, the compressor is driven by a drive machine 13 and includes two compression mechanism sections 10-a and 10-b having independent suction ports 14-a and 14-b.
A shaft-in-line compressor 10 is shown.

The pressure control device 6 controls the capacity adjustment devices (for example, suction throttle valves) 3a and :(-
b is activated to control the pumping amount so that the pressure in the pumping main pipe 5 remains constant according to load fluctuations.

9 in the middle of the control signal of the pressure control device 6 is the surge line 11 (generic name for 11-8, 11-b) shown in FIG.
The capacity control line 12 (12-a) is related to the air discharge control line which is calculated based on the pumping pressure and flow rate signals so that the air volume is slightly larger.

12-b) is a capacity control device for setting. This capacity control device 9 uses, for example, a program calculation processing type flow rate indicating controller, and 9a and 9b are as follows:
A flow converter that converts process flow into an electronic signal. The capacity control device 9 includes so-called cascade control devices 9A and 9B that are controlled by two signals of flow rate and pressure. These capacity control devices 9 are configured to adjust the operating point of the compressor 10 to a second level when the load amount decreases during load fluctuations in the plant.
Capacity control line 12 (12-a) shown in the figure.

12-b), the pressure control signal from the pressure control device 6 is cut and the capacity i1 [device (suction throttle valve) 3-a, 3-b is controlled to be held and disconnected from the pumping pressure state. At the same time, the capacity adjusting devices 3-a and 3-b are narrowed down, and at the same time, the air blowing devices (for example, blowing valves) 8-a and 8-b are opened to release the gas.

In particular, the load fluctuation follow-up control operation of the compressor capacity control device having such a configuration will be described.

In the diagram illustrating the operating points of the compressor shown in FIG. 2, in state (2), both the compression mechanisms 10-a and 10-b are in a pressure-feeding state, and the respective operating points and the compression mechanisms 10-a, 1. The 0-b combination state is shown with air volume on the horizontal axis and pressure on the vertical axis. Further, state (2) indicates a minimum discharge opening control state in which the compression mechanism section 10-a is separated from the pumping state pressure and air volume.

2-shaft parallel compressor], 0 is a compression mechanism section 10-8 and 10-b having independent suction ports 14n and 14-b.
are operating in parallel, the maximum air volume of each compression mechanism section at constant air pressure is set as Qa and Qb, and the capacity control lines 12-a and 12 at constant air pressure are -b If the throttle air volume at the operating point is 1/2 Qa and 1/2 Qb, the operating range air volume of this compressor at constant air pressure is 1/2 (Qa + Qb) at the minimum air volume, and 1/2 (Qa + Qb) at the maximum When the air volume is (Qll + Qb), it will be in between.

Therefore, when following load fluctuations in the entire operating range of the two-shaft in-line compressor 10, each compression mechanism section 10-
8 and 10-b capacity adjustment device (suction throttle valve) 3-a
The capacity control device 9 is controlled in response to the pressure control signal from the pressure control device 6 so as to provide a follow-up priority order for the lines 12-8 and 3-b, and the follow-up control is performed sequentially during load reduction control so that both the capacity control lines 12-8 and When reaching 12-b, as shown in "Status ■" in Figure 2, the capacity control line 12-;i is first reached and the capacity adjustment device that was holding; 3-a is changed from the pumping state pressure and air volume. At the same time, the discharge device 8-a (blowing valve) is controlled to discharge this minimum discharge gas. In this case, the capacity that reached the appetite control line 12-b later?
The 14-regulating device 3-b continues to control the pumping state as shown in "state 2" in FIG.

Furthermore, when the load of the plant decreases and follow-up control is performed, the capacity adjustment device 3-
b is also controlled in the same way as the control that reached the capacity control line first and was disconnected from the pumping state.

Note that during load increase control, control is performed in a completely reverse order to the above-mentioned decrease control.

Therefore, if this control method is adopted for the two-axis aligned centrifugal compressor 10, and if the capacity of the above-mentioned independent compression mechanism sections 0-8 and 10-b is the same, the operational control width in the pumping state will be the same as before. The operational control width of the control method will be expanded to twice that of the previous control method. Further, even in a region where the load is reduced in a range exceeding the reduction range of the compressor, air blowing operation in the pumping state can be prevented, so power loss can be reduced. In this case, the power when the pumping state is disconnected is generally about 40% of the power during the pumping state air discharge operation in the case of a power air source with a discharge pressure of about 5 to 8 kg/cdG.

According to this embodiment, in gas pressure transmission equipment where load fluctuations occur, the range of compressor operation control is expanded, so operation management is improved.
It is possible to prevent misalignment, and even in a region where the compressor exceeds the reduction range when the load is reduced, it is possible to prevent the pumping state from operating at several air volume, which has the effect of saving power loss.

In the above embodiment, an example of a two-axis parallel compressor in gas pressure equipment was explained, but the present invention is not limited to this, and the present invention is not limited to this. This type of pressure boosting mechanism can be widely applied to air machines such as blowers.

〔Effect of the invention〕

As described above, according to the present invention, the control range of the pressure boosting mechanism (for example, a compressor) in gas pressure feeding equipment where load changes is expanded, and the pumping pressure can be increased even in a region exceeding the pressure reduction range of the pressure boosting mechanism when the load is reduced. prevent air discharge operation in the state,
It is possible to provide a load fluctuation tracking control device for an air machine that can reduce power loss and improve the mechanical life of the device.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a capacity control device for a two-shaft in-line compressor according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of the compressor in Fig. 1, and Fig. 3 is a conventional FIG. 4 is a system diagram of a capacity control device for a compressor in a gas pumping facility, and is an operating point characteristic diagram of the compressor in FIG. 3. 3-a, 3-b... Capacity adjustment device, 5... Pressure feeding main pipe, 6... Pressure control device, 8-a, 8-b... Air blowing device, 9... Capacity control Apparatus, ] 0... 2-axis in-line compressor, 1.0-a, 1'0-b --- Compression mechanism section, 12
-a. 12-b- Capacity control line, 14-a, 14-b
...Suction port.

Claims (1)

[Claims] 1. A gas pressure transmission piping system with load fluctuations is equipped with a multi-shaft parallel pressure boosting mechanism having multiple suction ports, and during capacity control operation of the pressure boosting mechanism, the operating point of the pressure boosting mechanism is at the plurality of suction ports. A capacity control device for separating and narrowing down the operation of the capacity adjustment device from the pumping pressure state based on the discharge pressure when reaching the air discharge control line related to the operating limit of each installed capacity adjustment device. A load fluctuation follow-up control device for an air machine, characterized in that: