JPH06249190A - Controller of number of turbo compressor - Google Patents

Abstract

PURPOSE:To constantly control force-feed pressure by detecting force-feed flow rate to load from a common discharge piping for connecting to compressive medium discharge load sides of a plurality of turbo compressors, and selecting the number of machines to be driven according to the detected flow rate. CONSTITUTION:Respective turbo compressors 10, 20, 30 suck atomosphere by suction throttle valves 13, 23, 33, and forcibly feed it by main bodies 14, 24, 34, and pressure-detect it by pressure controllers 16, 26, 36 and control the suction throttle, valves 13, 23, 33 according to the load fluctuation. And it forcibly feed the atmosphere to the load through a common discharge pipe through the respective check valves 17, 27, 37. Two flow meters 2 are interposed in this discharge piping, so as to detect the flow rate in the discharge piping and input in the number control board 1. The number control board 1 determines the number of machines to be driven according to the detected flow rate, and outputs the starting/stopping command to respective machine side boards 11, 21, 31 so as to control them.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo compressor facility used for general industry such as a factory air source, and more particularly to a turbo compressor number control device for efficiently operating a compressor in response to various load fluctuations. It is a thing.

[0002]

2. Description of the Related Art As a conventional technology of a control device for the number of compressors, "Hitachi Review Vol. 70 No. 2 (February 1988)
Page 41 to page 46) ".
The above-mentioned conventional technology is a number control device of a plurality of screw type or reciprocating type positive displacement compressors, and performs load / unload switching operation of the compressors according to increase / decrease in the pumping pressure of the compressed air storage receiver tank, Further, it is a control for starting and stopping the compressor by calculating the load state of the compressor from the load operation time.

Further, in a turbo compressor, when the flow rate on the discharge side decreases, surging causes pressure fluctuation, which makes it impossible to carry out pressure feeding and causes excessive load on gears and bearings due to rotor vibration and transient fluctuation torque, resulting in damage to equipment. There is a phenomenon that operation becomes impossible. As a method of preventing this surging and continuing the operation, when the flow rate on the discharge side approaches the surging generation flow rate, the air blow valve provided in the discharge line is opened and air is released to the atmosphere, A method is generally used in which the blow-off valve is controlled so that the total flow rate pumped to the wake does not fall below the surging generation flow rate.

Incidentally, as a device related to this kind of device, for example, JP-A-56-77583 and JP-A-56-775.
84, JP-A-60-1394, JP-A-61-534.
79 and JP-A-63-239399.

[0005]

[Problems to be Solved by the Invention]
L. The technology described in "70 No. 2" has the following problems. That is, the pressure upper limit setting value and the pressure lower limit setting value are detected by a pressure switch or the like as the pumping pressure increases or decreases and the load / unload switching is performed, so the pumping pressure cannot be kept constant (pressure deviation of about 0.5 kg / cm ² G). For this reason, when it is required to keep the pumping pressure constant, the above conventional technique cannot be used.

Further, in the case where the constant pressure feeding pressure control is performed to solve the above-mentioned problem, the following problems occur because the prior art uses the positive displacement compressor. That is, there is the following method for controlling the constant pumping pressure of the positive displacement compressor. There is a method to adjust the opening of the suction throttle valve so that the pressure feed pressure becomes constant according to the load change of the compressor by providing a pressure controller that detects the pressure feed pressure of the compressor and a suction throttle valve of the compressor suction section. . However, since the power consumption of the positive displacement compressor is calculated by the following formula, even if the suction load is reduced and the suction throttle valve is throttled, the suction pressure Ps decreases but the pressure ratio Pd / P
Since s increases, there is a problem that the effect of reducing power consumption is small.

[Equation 1] L: Power consumption (kw) Ps: Suction pressure (ata) Qs: Suction flow rate (m ³ / s) Pd: Discharge pressure (ata) k: Specific heat ratio

The constant wind pressure / non-surge control of the turbo compressor has the following problems. In other words, even if the flow rate that actually needs to be pumped to prevent the occurrence of surging decreases, it means that the air is blown into the atmosphere to pump more than the surging generation flow rate. Since it is determined by the flow rate and the pressure ratio, the power for compressing the flow released to the atmosphere is all lost. That is, the power of the turbo compressor is given by the following formula.

[Equation 2] L: Power consumption (kw) R: Gas constant Ts: Suction temperature (° K) Pd: Discharge pressure (ata) Ps: Suction pressure (ata) K: Specific heat ratio At that point, the flow rate to the atmosphere is ΔG. If so, the power ΔL required for the compression is given by the following equation, and it is consumed as a loss.

[Equation 3]

Further, in the prior art, in order to reduce the increase / decrease in the pressure-feeding pressure, a receiver tank for storing the compressed air is provided, and the compressed air is stored in the receiver tank so that the pressure-feeding can be performed against the fluctuation of the pressure-feeding flow rate. The pressure fluctuation was kept low.

A first object of the present invention is to provide a number controller for turbo compressors capable of suppressing fluctuations in the pressure-feeding pressure of the compressor and performing constant pressure-feeding pressure control. A second object of the present invention is to use a turbo compressor as a number-of-units control device for controlling the pumping pressure to be constant, to reduce the blowing operation as much as possible, and to reduce the power consumption according to the load fluctuation of the compressor with good efficiency. It is to provide a unit control device for a turbo compressor. A third object of the present invention is to eliminate the range of blow-off operation and reduce power loss by combining turbo compressors having different capacities. A fourth object of the present invention is to provide a number of turbo compressors capable of keeping the pumping pressure constant by predictive control according to the change in air volume without using a receiver tank for storing compressed air for reducing the increase or decrease of the pumping pressure. It is to provide a control device.

[0010]

In order to achieve the first object, the number control device for a turbo compressor according to the present invention adjusts the gas supply amount on the suction side of the turbo compressor to adjust the discharge pressure of the compressor. To control the discharge pressure of the compressor by controlling the discharge pressure of the compressor and the suction throttle valve for controlling the discharge pressure of the compressor by discharging the compressed gas to the outside. A plurality of parallel-operated turbo compressors for constant discharge pressure control, each of which has a valve and a pressure controller for controlling the opening degree of the blow-off valve, and a flow meter for measuring a pumping flow rate to the compressor facility load. The number of required turbo compressors is started / stopped or the load / unload switching operation is performed by the unit control panel according to the flow rate detected by the flow meter (Claim 1, Claim 1). Item 2).

In order to achieve the second object, the blower operation can be performed as much as possible by using the constant discharge pressure control turbo compressor instead of the positive displacement compressor in the unit number control device of the present invention. By reducing the power consumption, the power consumption is reduced according to the load fluctuation of the compressor to improve the efficiency.

Further, in order to achieve the third object, by combining three or more turbo compressors having different capacities, for example, the range that can be adjusted without blowing air by a suction throttle is 70 to 100%, 100-140%, 140-200%
If one of the turbo compressors is combined and the number of units is controlled according to the flow rate, the number of units can be controlled without loss due to blowing up to 70 to 440% (claim 3).

Further, in order to achieve the above-mentioned fourth object, when the receiver tank is omitted, when the load use flow rate increases rapidly, the time until the start of pumping becomes a control delay time and causes a pressure drop. However, in order to prevent pressure drop due to the time delay until the start of pumping, the flow rate change is predicted and calculated, the flow rate is always predicted in advance by the time delay, and this flow rate is compared with the set flow rate for unit control. A command for starting or loading is issued (claim 4).

[0014]

According to the present invention, a plurality of turbo compressors having constant discharge pressure control are required to be detected by the flow meter to detect the flow rate of pumping to the compressor equipment load, and the unit control panel is required according to the flow rate detected by the flow meter. Since it is a device number control device that starts and stops a large number of compressors or performs load / unload switching operation, the pumping pressure can be controlled to be constant without fluctuations (claims 1 and 2). .

Further, according to the present invention, the unit number control device is constituted by a plurality of turbo compressors for constant discharge pressure control. Since the power consumption of the turbo compressors is given by the above equation (Equation 2), the load is reduced. Since the weight flow rate G is reduced when the suction throttle valve is throttled, the power consumption reduction effect at the time of load reduction is large and efficient unit number control can be performed as compared with the discharge pressure constant control by the positive displacement compressor.

Further, according to the present invention, by combining three or more turbo compressors having different capacities, the combination of compressors to be operated is changed according to the flow rate required for pumping, so that a small flow rate to a large flow rate is discharged. This enables operation without loss of power due to wind (claim 3).

Further, in the present invention, since the capacity of each turbo compressor is adjusted according to the flow rate, there is no pressure fluctuation, and the receiver tank for storing compressed air becomes unnecessary.

[0018]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram showing an embodiment of compressor equipment to which a number control device for turbo compressors according to the present invention is applied. FIG. 2 is a control flow diagram of an embodiment in which the number control system of FIG. 1 starts and stops the compressor in response to a load change, and FIG. 3 shows the number control system of FIG. It is a control flow figure of an example which carries out load / unload switching operation. 4 (a) and 4 (b) are compressors 3 having different capacities in the claim device of FIG.
FIG. 5 is a control flow diagram of an embodiment in which three compressors having the same capacity are combined and an embodiment in which three compressors having the same capacity are combined, and FIG. 5 is an operation of an embodiment in which predictive control is performed according to a flow rate change in the unit number control device of FIG. FIG.

The compressor equipment of the embodiment shown in FIG. 1 comprises three turbo compressors 10, 20, 30 and a flow meter 2 for measuring the flow rate of the gas pumped from these compressors to the compressor equipment load. And a unit number control panel 1 for controlling the number of compressors according to the flow rate. The turbo compressors 10, 20, 30 are suction throttle valves 13, 23 for adjusting the supply amount of gas on the compressor suction side of the compressor bodies 14, 24, 34 and controlling the discharge pressure of the compressor to be constant. , 33, blow-off valves 15, 25, 35 for preventing surging by releasing the compressed gas to the outside and controlling the discharge pressure constant, and the suction throttle valve and the discharge valve for detecting the discharge pressure of the compressor. Pressure controllers 16, 26, 36 for controlling the opening of the wind valve, and machine side panels 11, 21, 3 for performing start / stop or load / unload switching operation, etc.
1, low limit relays 12, 22, 32 for narrowing the suction throttle valve to a constant opening degree, and check valves 17, 27, 37 for preventing reverse flow on the compressor outlet side.

With the above configuration, each turbo compressor 10, 2
0, 30 pressure-feeds the air sucked from the suction throttle valves 13, 23, 33 by the compressor bodies 14, 24, 34, detects the pressure-feeding pressure by the pressure regulators 16, 26, 36, and changes in the load of the compressor. Suction throttle valve 1 when the load decreases
When the load of pumping is reduced by narrowing the openings of 3, 23, 33 and the load is greatly reduced, the low limit relay 1
Blow-off valve 1 while maintaining the state in which the openings of suction throttle valves 13, 23, 33 are throttled to a constant opening by 2, 22, 32.
5,25,35 is a device for controlling the pumping pressure to be constant while avoiding the surging of the compressor by discharging a larger amount of air than required to the atmosphere. The flow rate of the gas pressure-fed from the turbo compressors 10, 20, 30 is measured by the flow meter 2 and input to the measured flow rate unit control panel 1. In the unit number control panel 1, the operating number of turbo compressors required for pumping is selected according to the flow rate input from the flow meter 2, and a start / stop command is issued to the machine side panels 11, 12, 13 of each compressor. A load / unload switching command is output, and each command causes the compressor to start / stop or load / unload switching operation by the machine side panel. Note that the load operation refers to an operating state in which the suction throttle valve and the blow-off valve are controlled to be pressure-fed to the load. Not refers to the operating state. In addition, start / stop depends on turning the power on / off.
As a result, as the compressor equipment, the minimum number of compressors required for the equipment load always perform the pressure feeding, so that the labor of the entire equipment can be saved.

FIG. 2 shows a unit control panel 1 in the embodiment of FIG.
The control flow of the embodiment in which the turbo compressors 10, 20, and 30 are started / stopped is shown. In the embodiment of FIG. 2, when the pumping pressure is constant and the pumping flow rate increases, the compressors are sequentially started to increase the number of operating units so that the pumping flow rate to the equipment load is not insufficient, and conversely When it decreases, the compressor is stopped one after another so that the pumping flow rate to the equipment load is not excessive.

FIG. 3 shows a unit control panel 1 in the embodiment of FIG.
2 shows a control flow of an embodiment in which the turbo compressors 10, 20, 30 are switched between load / unload switching operations.
In the embodiment of FIG. 2, when the pumping flow rate increases, the number of compressors performing load operation is increased so that the pumping flow rate of the equipment does not become insufficient, and conversely, when the pumping flow rate decreases, unloading operation is performed. It is a device that increases the number of machines and prevents the excess pumping flow to the equipment load.

In both the embodiment shown in FIG. 2 and the embodiment shown in FIG. 3, the number of compressors that perform the pumping operation is increased or decreased according to the pumping flow rate, so that the labor of the compressor equipment can be saved. Moreover, since the number of units is controlled by the pressure-feeding flow rate, the pressure-feeding pressure can be kept constant. Furthermore, since each compressor is a turbo compressor with constant pressure control by a suction throttle valve, if the pumping flow rate of each compressor decreases, the power consumption also decreases according to the flow rate, so a device using a positive displacement compressor It is a more efficient device.

FIGS. 4 (a) and 4 (b) are flow charts of control of an embodiment in which three compressors having different capacities are combined in the embodiment of FIG. 1 and an embodiment in which three compressors having the same capacity are combined. is doing. In the embodiment of FIG. 4 (a), the flow rate range that can be adjusted without being blown by the blowoff valves 15, 25, 35 by the throttles of the suction throttle valves 13, 23, 33 is 7
0-100%, 100-140%, 140-200% turbo compressors, each one combined, flow meter 2
Controlling the number of units in the unit control panel 1 based on the detected flow rate of, for example, load / unload switching operation
It is possible to realize unit control without power loss due to blown air up to 0%. An embodiment in which the characteristics of FIG. 4 (a) are combined in FIG. 4 (b), for example, a turbo compressor having the same adjustable flow rate range of 70 to 100% without being blown, and the same number control is performed Compared with the characteristics of, the power loss due to the blown air in the range shown by the diagonal line is obviously smaller. Note that the same applies when starting and stopping.

Further, in any of the embodiments shown in FIGS. 1 to 4 (a) and 4 (b), the turbo compressor having the constant pumping pressure control adjusts the capacity according to the fluctuation of the pressure and the flow rate, and starts each compressor. -Since the stop or load / unload switching operation is performed by detecting the change in the pressure feed flow rate, not the load pressure feed pressure, a receiver tank for storing compressed air is not required. However, if there is no receiver tank, a sudden increase in the used flow rate may cause a pressure drop due to the delay until the actual pumping starts, so to prevent this, predictive control according to the flow rate change is required. Is preferably performed.

FIG. 5 shows the operation of the number-of-units control device in the embodiment of FIG. 1 to perform the advance prediction control according to the flow rate change. In the embodiment of FIG. 5, the unit control panel 1 detects the detected flow rate f (t) of the flow meter 2 with respect to the change Δt of the time t,
Time t and the flow rate f rate f at time t = t _O the characteristics of (t) (t ₀₎ from the time t = t ₀ + prediction in Delta] t flow f (t ₀ + Δt) obtained by the following prediction equation.

[Equation 4] When this predicted flow rate f (t ₀ + Δt) is compared with the set flow rate f _N and the following discriminant is satisfied, the number of parallel operation units is increased by 1 and one additional start or load operation is performed.

[Equation 5] Although the above equation (Equation 4) is a linear approximation equation, it is not limited to this.

[0027]

According to the present invention, a novel function for detecting the pumping flow rate and predicting the change in the pumping flow rate and for starting / stopping a plurality of turbo compressors or switching between load / unload switching operations is obtained. It is effective. Further, as a result, the compressor is started / stopped or the load / unload switching operation is carried out in accordance with the flow rate of the pressure to be fed, so that the compressor is not wastefully operated and the equipment can be saved in labor. Further, since the turbo compressor whose pressure is controlled by the suction throttle valve is used, the load also decreases as the flow rate decreases, so the labor of the compressor equipment can be saved. In addition, the turbo compressor with constant pumping pressure control adjusts each amount according to the fluctuation of pressure and flow rate, and the start / stop of each compressor or load / unload switching is detected by detecting the change of the flow rate instead of the pumping pressure. Since this is performed, there is an effect that a receiver tank for storing compressed air is unnecessary. In addition, since the number of units is controlled by the pumping flow rate, there is no pressure fluctuation and the pressure is constant. In addition, it is possible to improve the performance and efficiency because the pressure drop can be prevented even if the load suddenly increases due to advance prediction. There is.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of compressor equipment to which a number control device for turbo compressors according to the present invention is applied.

2 is a control flow diagram of an embodiment in which the compressor is started / stopped according to a load change in the unit number control apparatus of FIG. 1. FIG.

FIG. 3 is a control flow diagram of an embodiment in which the compressor is operated to switch between loading and unloading in accordance with load fluctuations in the unit number control device of FIG. 1.

4A and 4B are control flow charts of an embodiment in which three compressors having different capacities are combined in the unit number control apparatus of FIG. 1 and an embodiment in which three compressors having the same capacity are combined. Is.

5 is an explanatory diagram of an example of performing predictive control according to a flow rate change in the unit number control device of FIG. 1. FIG.

[Explanation of symbols]

 1 Number control panel 2 Flow meter 10,20,30 Turbo compressor 13,23,33 Suction throttle valve 14,24,34 Compressor body 15,25,35 Blow-off valve 16,26,36 Pressure regulator 17,27 , 37 Check valve

Claims (5)

[Claims] 1. A suction throttle valve that throttles a flow rate of a suction gas of a turbo compressor, a blow-off valve that blows the discharge gas of the compressor, and a suction valve that detects the discharge pressure of the compressor and controls the discharge pressure to be constant. A plurality of turbo compressors each having a throttle valve and a pressure controller for controlling a blow-off valve opening; and a common discharge pipe in which the compressed gas discharge load sides of the plurality of turbo compressors are commonly connected. A turbo compressor comprising: a flow meter for detecting a flow rate of pressure fed from the pipe to the load; and a unit control panel for selecting the number of operating compressors according to the detected flow rate of the flow meter and for starting / stopping the compressor. Number control device. 2. A suction throttle valve that throttles a flow rate of a suction gas of a turbo compressor, a blowoff valve that blows off the discharge gas of the compressor, and a suction valve that detects the discharge pressure of the compressor and controls the discharge pressure to be constant. A plurality of turbo compressors each having a throttle valve and a pressure controller for controlling a blow-off valve opening; and a common discharge pipe in which the compressed gas discharge load sides of the plurality of turbo compressors are commonly connected. A flow meter for detecting the flow rate of the pressure fed from the pipe to the load, and the number of compressors operating according to the flow rate detected by the flow meter, and then controlling the suction throttle valve and blow-off valve opening to the load. A unit control device for a turbo compressor, which comprises a unit control panel for switching between load operation in which pressure is fed and unload operation in which the suction throttle valve is fully closed and the blowoff valve is fully opened and pressure is not fed to the load. 3. The different-capacity turbo compressors in which the plurality of parallel-operated turbo compressors are combined in combination of three or more in order to eliminate a pumping flow rate range to the compressor load, which is a blowing operation by a blow valve of the turbo compressor. The number control device of the turbo compressor according to claim 2 or 3 which consists of a compressor. 4. The unit control panel of the flow meter is provided with a time delay from when the start or load command of the unit control panel enters the turbo compressor to when the compressor starts to discharge gas pressure. The number control device of the turbo compressor according to claim 1 or 2, wherein the start or load command is issued by predicting a change in the detected flow rate in advance. 5. A turbo compressor number control apparatus according to claim 1, wherein a check valve for preventing backflow is provided between the compressed gas discharge load side of said plurality of turbo compressors and a common discharge pipe. . [0001]