JPH07180694A - Supply pressure control method of industrial air - Google Patents

Abstract

PURPOSE:To maintain air pressure constant to air demand with large load fluctuation so as to aim at stable supply by enabling the start-stop of air compressors with appropriate timing on the basis of demand prediction in air demand places. CONSTITUTION:In air load provided at the respective plants A-E, advance notice signals 7 to be triggers immediately before executing the preset start-stop of use, and the corresponding increase-decrease quantity of industrial air are taken into a centralized control part 9, and the advance notice is displayed (8). At the same time, the absorption quantity of guide vanes 1 is computed, and the guide vane adjusting quantity is displayed (6). Under the appropriate timing corresponding to the transmission of the advance notice signals 7, when the fluctuation absorbable total quantity by the discharge adjustment of each air compressor 2 in operation is large in comparison to the increase quantity and decrease quantity, each discharge is regulated to adjust the supply quantity, and at the time of being small inversely, the required number of air compressors 2 corresponding to the under-and-over quantity are started-stopped in addition to the adjustment of the supply quantity so as to enable air supply relaxing the fluctuation of supply pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial air supply system provided in an air demanding place such as a factory where a large amount of pressure air is used and a large fluctuation range is used.
The present invention relates to a method for controlling the supply pressure of industrial air capable of reducing the supply pressure fluctuation.

[0002]

2. Description of the Related Art In order to supply air to a plurality of demand points that require a large amount of such industrial air, as shown in FIG. Air compressors 2 and 2 are connected in parallel to an air supply main 4 formed in a looped pipe and selectively operated, whereby a plurality of air branches are connected to the air supply main 4. Industrial air supply systems are often used to supply industrial air to demand points such as factories A, B, C, ....
In this case, since the amount of industrial air used fluctuates greatly, as a method of controlling the supply pressure, the air flow rate is adjusted by the guide vanes 1 and 1 for the individual air compressors 2 and 2, and the guide vane 1 is adjusted. , 1, when the adjustment cannot be completed, the air compressors 2 and 2 are selectively started and stopped for adjustment. At this time, there is a problem that the supply pressure P fluctuates greatly before the start and stop operations of the air compressors 2 and 2.

[0003]

FIG. 4 shows the fluctuation of the supply pressure by the supply system shown in FIG. 3. The supply pressure P detected by the mains pressure gauge 3 is, for example, in a steel mill. 5.0 kg / cm ² although is controlled by G, by demand changes in plant air, the pressure is varied up to ^{4.5Kg / cm 2 G ~5.4Kg / cm} 2 G. This is because the pressure fluctuation cannot be completely absorbed only by adjusting the discharge amount by the guide vanes of the operating air compressor, and it depends on the start / stop of the compressor. This is because it is unavoidable that pressure fluctuations occur by the time the start and stop of is completed.

The present invention has been made in order to solve such a problem, and an object of the present invention is to make an appropriate adjustment based on a demand forecast of industrial air at an air demand point such as a factory. By enabling the air compressor to be started and stopped at various timings, it is possible to maintain a constant air pressure for air demand with large load fluctuations, thereby contributing to a stable supply.

[0005]

The present invention has the following constitution in order to achieve the above object. That is, according to the present invention, a plurality of air compressors whose discharge amounts can be individually adjusted are connected in parallel to an air supply main pipe composed of a loop pipe to selectively operate the air compressors. In an industrial air supply system that supplies industrial air of a predetermined pressure to multiple air demand points that are branched and connected to pipes, a notice indicating the time immediately before the start and stop of use of industrial air at each air demand point A signal and the corresponding increase / decrease of industrial air are incorporated into the operation control system, and fluctuations can be absorbed by adjusting the discharge rate of each air compressor during operation under appropriate timing according to the transmission of a warning signal. When the amount is larger than the increase amount and the decrease amount, the discharge amount is adjusted to adjust the supply amount. On the contrary, when the amount is small, the supply amount is adjusted by adjusting each discharge amount, and the excess amount is insufficient. The required number of empty spaces according to the quantity And to perform the start and stop of the compressor, a supply pressure control method for an industrial air, characterized in that form allows the supply of air that may mitigate variations in the supply pressure.

[0006]

According to the present invention, a notice signal issued immediately before the start / stop of the use of industrial air is taken in, and at the stage when this signal is issued, the amount that can be absorbed by the guide vanes or the like of the air compressor currently in operation. Compared with the expected increase / decrease in air demand, first adjust the individual discharge amount while the absorbable amount is available, and if it is not possible, start / select the additional air compressor. It is possible to stop at an appropriate timing. In this way, the supply of air that can mitigate the fluctuation of the supply pressure is performed stably.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a supply system diagram in which an operation control system for factory air according to an embodiment of the method of the present invention is also shown, and the operation control system is also shown. This factory air supply system is formed into a loop-shaped pipe and is laid across a plurality of factory A to factory E, and an air supply main 4 is connected in parallel to the discharge side. A plurality of air compressors 2 and 2, a centralized control unit 9 that collectively controls the operation of these air compressors 2 and 2, and a main pressure gauge 3 that measures the supply pressure in the air supply mains 4. And the air loads of the factories A, B, C, D and E that are branched and connected to the air supply main 4. Each of the air compressors 2 and 2 has a guide vane 1 for adjusting the discharge amount (air amount).

The air loads provided in each of the factories A, B, C, D, and E are triggers immediately before the start and stop of use because the start and stop times of use are set in advance. The signal is taken out as the advance notice signal 7, and this is taken into the central control unit 9 and the advance notice display 8 is made on the side of the central control room. Also, the absorption amount (adjustable flow rate) of each guide vane 1 of the air compressors 2 and 2 in the current operation.
Is calculated from the guide vane% by the computer 5, and the guide vane adjustment amount display 6 is displayed. The warning signal 7 is
It is possible to use mechanical signals of various machines equipped with air loads, business computer signals, programmable controller signals, and as a specific example, continuous casting equipment in which a large amount of mist that is a mixture of pressurized air and water is consumed. In the case of, the signal as described below can be used as the advance notice signal 7. That is, as the warning signal 7 corresponding to immediately before the start of use of factory air, a signal generated by pouring molten steel in the ladle into the tundish,
, There is a signal issued when the tundish slide valve opens, and a signal issued when the dummy bar is pulled out. On the other hand, as the notice signal 7 corresponding to immediately before the stop of the use of the factory air, there are a signal issued when the inside of the tundish is emptied, a signal issued when the extraction is completed, and the like.

FIG. 2 schematically shows a mode of operation control of the air compressors 2, 2, ... In the centralized control unit 9. In FIG. 2, in step 1, the warning signal 7 of the air load is fetched. Based on the notice signal 7, the process proceeds to step 2 and it is determined whether the supply air is increasing or decreasing. For example, when it is determined that the air volume fluctuates toward the increasing side, the process proceeds to step 3 and the previously known increase amount of air use Q ₁ corresponding to the advance notice signal 7 is compared with the margin amount Y ₁ by adjusting the guide vanes. The surplus amount Y ₁ is the total amount of surplus air supply due to the adjustment of the guide vanes 1 in the air compressor 2 during operation. If this comparison result is Q ₁ ≦ Y ₁ , it can be dealt with by increasing the capacity of the air compressor 2 in operation. Therefore, the process proceeds to step 4 to perform pressure control by adjusting the guide vanes 1 to increase fluctuations. Correspond to. On the other hand, if the comparison result is Q ₁ > Y ₁ , the process proceeds to step 5,
The difference is compared with the capacity of one air compressor 2, and when the difference is smaller, the process proceeds to step 6 and one air compressor 2 is activated after α seconds, which is an appropriate timing, to increase. It corresponds to the fluctuation of the side. On the other hand, when the difference is larger, the process proceeds to step 7 and the two air compressors 2 are started after α seconds, which is an appropriate timing, to cope with the fluctuation on the increasing side. In this way, it is possible to stably supply air under the condition that the pressure of the air supply main pipe 4 is kept constant against the fluctuation of the air load toward the increasing side.

On the other hand, if it is determined in step 2 that the air pressure will fluctuate toward the decreasing side, the process proceeds to step 8 to adjust the air use reduction amount Q ₂ and the guide vane, which are known in advance in accordance with the warning signal 7. The absorption amount Y ₂ by The absorption amount Y ₂ is the total amount of throttled air supply by adjusting the guide vanes 1 in the air compressor 2 during operation. Here, from step 8 to step 12, an operation for reducing the air supply capacity is shown, and except for the difference between start and stop, it is similar to the mode of step 3 to step 7, so avoid duplication. And the description is omitted.

[0011]

As is apparent from the above description, the present invention makes it possible to predict the demand situation of an air demand location such as a factory and start the air compressor at an appropriate timing faster than the supply pressure fluctuates. It can be stopped, problems such as abnormally low pressure and abnormally high pressure can be prevented, it is possible to supply air under stable pressure, and wasteful operation due to high pressure is avoided and running cost is reduced. Can be reduced.

[Brief description of drawings]

FIG. 1 is a factory air supply system diagram according to an embodiment of the method of the present invention.

2 is a flowchart showing an operation control mode of air compressors 2, 2, ... In a centralized control unit 9 shown in FIG.

FIG. 3 is a conventional factory air supply system diagram.

FIG. 4 is a development view of recording paper showing a supply pressure fluctuation state by the supply system shown in FIG.

[Explanation of symbols]

1 ... Guide vane, 2 ... Air compressor, 4 ... Air supply main, 5 ... Calculator, 6 ... Adjustment amount display,
7 ... Warning signal, 8 ... Warning display, 9 ... Centralized control unit.

Claims (1)

[Claims] 1. A plurality of air compressors whose discharge amounts can be adjusted individually are connected in parallel to an air supply main consisting of a loop-shaped pipe to selectively operate the air compressor, so that the air supply mains can be selectively operated. In an industrial air supply system that supplies industrial air of a predetermined pressure to a plurality of air demand points that are branched and connected to each other, a warning signal indicating the time immediately before the start and stop of use of the industrial air at each air demand point And the corresponding increase / decrease amount of industrial air is incorporated into the operation control system, and the total amount of fluctuations that can be absorbed by adjusting the discharge amount of each air compressor during operation under appropriate timing according to the transmission of the warning signal. Is larger than the increase amount and the decrease amount, the discharge amount is adjusted to adjust the supply amount. Conversely, when the discharge amount is smaller than the increase amount and the decrease amount, the excess amount and the shortage amount are adjusted together with the adjustment of the supply amount by adjusting each discharge amount. Required air pressure according to A method for controlling the supply pressure of industrial air, which comprises starting and stopping a compressor to enable supply of air capable of mitigating fluctuations in supply pressure.