JP5758818B2 - Compressor system and operation control method thereof - Google Patents

Description

  The present invention relates to a compressor system and an operation control method thereof, and more particularly to a compressor system and an operation control method thereof suitable when a plurality of compressors are used in combination.

  In a compressor facility used for a factory air source or the like, an optimum operation according to the amount of air used is attempted by combining a plurality of compressors. At that time, compressors with different capacities and formats may be combined. By the way, the types of compressors are roughly classified into a displacement type compressor and a turbo type compressor, and exhibit different characteristics.

  A positive displacement compressor such as a screw compressor, a reciprocating compressor, or a scroll compressor forcibly contracts the volume of the compression target gas to increase the pressure. Then, a predetermined pressure fluctuation range is allowed with respect to the target discharge gas pressure, and the full load operation and the no load operation are repeated to adjust the capacity. Further, in a positive displacement compressor including an inverter, the motor speed is PI (or PID) controlled using the deviation between the discharge gas pressure and the target pressure to adjust the capacity. In this type of rotational speed control type positive displacement compressor, it is possible to operate with less power consumption than a conventional compressor that adjusts the capacity by repeatedly performing full-load operation and no-load operation. In addition, since the inverter is included, it is possible to avoid a large current from flowing to the motor at the time of start-up, and there are almost no restrictions on the number of start-ups or the start-up frequency.

  A turbo compressor is designed to increase the pressure by reducing the speed after giving kinetic energy to the compression target gas by centrifugal force. A suction throttle valve is provided at the suction port, and based on the deviation between the discharge gas pressure and the target pressure. The capacity of the suction throttle valve is adjusted by PI (or PID) control. That is, the suction throttle valve angle is adjusted to turn the intake gas, and the capacity is adjusted by changing the flow rate of the intake gas.

  The suction throttling control has high energy saving because the power consumption decreases in proportion to the decrease in the gas consumption flow rate. However, when the gas flow rate is reduced by the suction throttle valve, an unstable phenomenon called surging occurs, and for example, the suction throttle valve control in the case of a three-stage turbo compressor is limited to a capacity of about 70 to 100%.

  Therefore, in order to realize a wider range of capacity control in the turbo compressor, a lower limit value is set in the capacity control by the suction throttle valve (for example, 70% load in the above example), and operation is performed in a capacity range below this lower limit value. Therefore, on / off control that repeats full-load operation and no-load operation is used in combination as in the displacement compressor. This is called dual control. Alternatively, the constant air pressure control for releasing the discharge gas from the discharge valve to the atmosphere according to the discharge gas pressure fluctuation is also used.

  Examples of capacity control methods when using a plurality of compressors are described in Patent Document 1 and Patent Document 2. In the compressor equipment described in these publications, the capacity of the positive displacement compressor is adjusted by on / off control in which full load operation and no load operation are repeated, and the turbo compressor is used as a base load machine for full load operation.

  An example of the number control when using a plurality of compressors is described in Patent Document 3. In the compressor facility described in this publication, several turbo compressors are used to further improve energy saving, and the discharge gas pressure is kept almost constant by the suction throttle control of the turbo compressor. The fluctuation of the is suppressed.

  Moreover, in the compressor installation described in Patent Document 4, a plurality of turbo compressors are connected in parallel, and suction compression control is performed using all the compressors as capacity adjusters. When all the turbo compressors in operation exceed the range in which the suction throttle control can be performed, the capacity control is performed by switching to the air discharge control or the on / off control.

  In the method described in Patent Document 4, when a required amount of gas is small, on-off control or ventilating control by a turbo compressor must be used to avoid surging, and energy saving is improved in the entire region. It becomes difficult. Therefore, in Patent Document 5, the load capacity is divided into a plurality of ranges so that the number of operating compressors is minimized, and the operation is switched to a combination of operating compressors set in advance for each divided range. Then, the capacity of the dual-controllable turbo compressor is preferentially adjusted, and when the capacity of the turbo-type compressor exceeds the adjustable range, the positive displacement compressor which is controlled on and off is preferentially used as the capacity adjuster.

JP-A-7-332248 JP-A-7-119644 Japanese Patent Laid-Open No. 6-249190 JP 2006-63813 A JP 2000-12058A

  In each example of the conventional compressor unit number control operation, an optimum compressor combination operation can be obtained at a specific air consumption. However, when the load fluctuation becomes large and the combination and number of compressors to be operated have to be changed, some of the compressors in operation need to be stopped. A large current flows through the electric motor that drives the compressor, and the coil temperature rises. Therefore, in order to shorten the life of the motor coil and prevent burnout, there are restrictions on the number of startups and the startup frequency of the motor. In particular, when large load fluctuations such as the required number of compressors change frequently occur, compressors that are not used for a while are placed on standby in a no-load operation for a predetermined time and reused when demand recovers. The power of the compressor that is on standby in no-load operation is useless power consumption, and is a control contrary to energy saving.

  In addition, positive displacement compressors and turbo compressors have advantageous ranges of use from the viewpoint of capacity and controllability. When used in combination, one is a capacity adjuster and the other is a base load machine. It was limited to operation. For example, focusing on capacity, a positive displacement compressor is advantageous for small capacity from a viewpoint of power consumption, and a turbo compressor is advantageous for large capacity. A turbo compressor is used as a base load machine, and a positive displacement compressor is used as a capacity adjuster. In general, the capacity efficiency of the positive displacement compressor is improved when the power consumption is 500 kW or less, and the operation efficiency of the turbo compressor is improved when the power consumption is 500 kW or more. Although some reports have been made on the combination of a positive displacement compressor and a turbo compressor, a turbo compressor operated by suction throttle control and an energy-saving rotational speed control displacement compressor In the past, sufficient consideration has not been given to energy saving by combining the above.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to realize unit control of a plurality of compressors that have higher energy savings and prevent the shortening of the service life of the motors that drive the compressors. There is. Another object of the present invention is to realize compressor unit control that avoids surging that does not require a complicated input signal system in a compressor facility that combines a positive displacement compressor and a turbo compressor. .

  A feature of the present invention that achieves the above object is that the present invention has a suction throttle valve, and has at least one turbo compressor that adjusts the volume of intake gas by the suction throttle valve and a motor, and an electric motor. These turbo compressors include at least one rotational speed control type positive displacement compressor that adjusts the capacity by controlling the rotational speed, and an on-off positive displacement compressor that adjusts the capacity by repeating load operation and no-load operation. A compressor system in which the discharge sides of the displacement-controllable displacement compressor and the on-off displacement compressor are connected in parallel with each other, the turbo compressor, the rotation-control displacement compressor, and the on-off volume Each type compressor has compressor control means, and discharge pressure detection means for detecting discharge pressure, which is pressure downstream of the parallel pipe connection portion, and discharge pressure detected by the discharge pressure detection means are input. And a unit control panel for outputting a control command to each compressor control panel, and the unit control panel is configured to control the capacity of the turbo compressor so that the turbo compressor preferentially controls the capacity during operation of the turbo compressor. The control command is output to the control panel of the compressor, and when the turbo compressor is stopped or during no-load operation or when the suction throttle control range is at the lower limit, the rotational speed control type positive displacement compressor performs the capacity control. The purpose is to output a control command to the compressor control panel of the number control type positive displacement compressor.

  In this feature, when the turbo compressor is in a capacity control state, it is preferable that the control panel of the turbo compressor controls the capacity using the suction throttle valve without using the number control panel, and the turbo compressor The lower limit of the suction throttle control range of the type compressor is not more than the sum of the rated capacities of the on-off positive displacement compressor and the rotational speed control positive displacement compressor, and the rated capacity of the turbo compressor is the on-off type It may be greater than or equal to the sum of the rated capacities of the positive displacement compressor and the rotational speed control positive displacement compressor.

  Another feature of the present invention that achieves the above object is that it has a suction throttle valve, and has at least one turbo compressor that adjusts the capacity by adjusting the amount of intake gas by the suction throttle valve, and an electric motor. And at least one rotational speed control type positive displacement compressor that adjusts the capacity by controlling the rotational speed of the electric motor, and an on-off positive displacement compressor that adjusts the capacity by repeating load operation and no-load operation. In the operation control method of the compressor system in which the discharge side of the turbo compressor, the rotational speed control type positive displacement compressor, and the on-off positive displacement compressor is connected in parallel, the turbo compressor has priority during operation. The turbo-type compressor performs capacity control, and the turbo-type compressor performs capacity control when the turbo-compressor is stopped or during no-load operation or at the lower limit of the suction throttle control range.

  According to the present invention, since the compressor system in which a plurality of compressors are connected in parallel has the rotational speed control type positive displacement compressor, the on / off positive displacement compressor or the turbo compressor with a limited number of start / stop operations. It is possible to reduce the no-load operation time, reduce the number of start / stop times of the on-off positive displacement compressor and turbo compressor, increase energy savings, and prevent the shortening of the life of the motor that drives the compressor. Can control the number of compressors. In addition, it is possible to realize control of the number of compressors that avoids surging that does not require a complicated input signal system.

1 is a system diagram of an embodiment of a compressor according to the present invention. It is a graph explaining an example of the combination state when operating combining a plurality of compressors. It is an example when it drive | operates combining several compressors, and is a figure which shows transition of an operating state. It is a flowchart when carrying out unit number control operation of a plurality of compressors. It is a flowchart when carrying out unit number control operation of a plurality of compressors. It is a flowchart when carrying out unit number control operation of a plurality of compressors.

  Hereinafter, an embodiment of a compressor according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a compressor system 100 according to the present invention. In this embodiment, a plurality of compressors, that is, three compressors 2 to 4 in FIG. The three compressors 2 to 4 are connected in parallel by the gas pipe 6, and the compressed gas collected in the gas pipe 6 is stored in the receiver tank 5. Then, it is sent from the receiver tank 5 to the demand source. Table 1 shows details of the three compressors 2 to 4 used in the compressor system 100.

  The compressor system 100 is a system having three types of compressors V, S, and T. That is, one rotational speed control type positive displacement compressor V, one on / off control type positive displacement compressor S having the same rated air flow as the rotational speed control type positive displacement compressor V, and one rotational speed control type positive displacement compressor V There is one turbo compressor T having a lower limit value of the suction throttle control range than the sum of the rated air volumes of the on-off control type positive displacement compressor S. If the rated air volume of the rotational speed control type positive displacement compressor V and the on / off control type positive displacement compressor S is 100, the full load capacity of the turbo compressor T is 280, and the lower limit capacity in the suction throttle control is the full load. It is 196 which becomes 70% of the above. Returning to FIG. 1, the compressor 2 is a rotational speed control type positive displacement compressor V, the compressor 3 is an on-off positive displacement compressor S, and the compressor 4 is a turbo compressor T.

  The receiver tank 5 is provided with a pressure detector 52, and discharge gas pressure measurement data detected by the pressure detector 52 is taken into the unit control panel 1. Each of the compressors 2 to 4 includes pressure detectors 22, 32, and 42 on the discharge side. The compressor control panels 21, 31, 41 to which the outputs of the pressure detectors 22, 32, 42 are input are also provided. Between the compressor control panels 21, 31, 41 and the unit control panel 1, A contact signal input / output device and an analog input / output signal device or communication device (not shown) are provided.

  The contact signal input / output device is a device that inputs / outputs at least a start / stop command signal of each of the compressors 2 to 4, a compressor operation answerback signal, and a failure signal. Further, the analog input / output signal device or the communication device sets the rotational speed control type positive displacement compressor 2 based on the deviation between the discharge gas measurement pressure taken from the pressure detector 52 and the target pressure in the unit control panel 1 to PI ( Or a device for inputting / outputting a rotational speed command signal and a rotational speed command answerback signal for control. When the suction control of the turbo-type compressor 4 is performed, the control panel 41 of the turbo-type compressor 4 is set to PI (based on the deviation between the measured pressure of the discharge gas detected by the pressure detector 52 of the receiver tank 5 and the target pressure. Or PID) control.

  FIG. 2 shows an optimum combination result of compressors when the number of compressors V, S, and T is used to control the number of such compressors. FIG. 2 shows the relationship between the air consumption and the power consumption. Here, the optimum operating state in the unit control is a combination in which the power consumption is the smallest for each air volume consumed.

  In FIG. 2, when the air consumption is in the range of 0 to 100, the power consumption is the smallest when the capacity is adjusted using the rotational speed control type positive displacement compressor V. This is because when the air consumption is in the range of 20 to 100, the adjustment is performed by the rotational speed control, and the air is not compressed unnecessarily and only the necessary amount is compressed. On / off control is performed in the range of air volume 0 to 20, but since the on / off control is performed at a low rotation speed, the power consumption is higher than the on / off control at the rating (maximum rotation speed) by the on / off displacement compressor S. Few.

  In the range of air consumption 100 to 200, the on-off positive displacement compressor S is operated at full load, and the capacity is adjusted by the rotational speed control positive displacement compressor V. This flow range has an upper air volume that is almost the same as the lower limit (196) of the suction throttle control of the turbo compressor T, and when the turbo compressor T is used, the suction throttle control cannot be applied. In general, this control is called constant wind pressure control with air discharge. Since the constant wind pressure control is accompanied by the release of air, the air compressed by the compressor is discarded, and the wasteful power consumption is naturally increased. Therefore, an optimal combination is the combination of the rotational speed control type positive displacement compressor V that has a proven record in the air volume of 0 to 100 and the on / off positive displacement compressor S that is driven by the maximum air volume.

  If the compressors V, S, and T are used in combination within the range of air consumption 200 to 280, the two compressors V and S cannot generate a predetermined air volume. It must be. However, as described above, when one or both of the positive displacement compressors S and V and the turbo compressor T are combined, the turbo compressor T is in the constant wind pressure control range, and wasteful power generated by ventilating is used. become. Therefore, since the suction throttle control is possible, the capacity is adjusted by using the turbo compressor T alone.

  In the range of air consumption 280 to 300, the required air volume can no longer be achieved by the single operation of the turbo compressor T, so the compressors V, S, and T are two or three combinations. Here, when the on-off positive displacement compressor S is combined, it is desirable that the on-off positive displacement compressor S is continuously operated at the maximum air flow because of the limitation of the number of on / off operations of the on-off positive displacement compressor S.

  In the range of the air consumption 280 to 300, when the on-off displacement compressor S is continuously operated and the turbo compressor T is operated in combination with the on-off displacement compressor S, the turbo compressor T is sucked and throttled. There is a case where operation is performed below the lower limit of control. In other words, in the turbo compressor, air discharge by constant wind pressure control is generated and power consumption increases. Therefore, the on-off type positive displacement compressor S is not used, and a combination of a turbo compressor T and a rotational speed control positive displacement compressor V that can adjust the capacity is adopted. In this case, there are several possible modes of operation, but the turbo compressor T is more efficient in terms of power consumption than the rotational speed control type positive displacement compressor V. The load operation is performed with the air volume 200 close to the lower limit capacity of the suction throttle control that provides the above. Along with this, the capacity is adjusted so that the remaining necessary air volume is obtained by the rotational speed control type positive displacement compressor V.

  Furthermore, in the range of the consumed air volume 300 to 380 where the consumed air volume increases, the compressors V, S, and T are also used in combination of two or three kinds. Here, even if one of the displacement compressors S and V is driven with the maximum air volume, the capacity required for the turbo compressor T is within the range of the suction throttle control, and useless power such as air discharge is eliminated. Therefore, any of the positive displacement compressors V and S and the turbo compressor T are combined. It is empirically known that small fluctuations occur more frequently than large fluctuations when the consumed air volume fluctuates, so it is better to continuously use the compressor used in the air volume range adjacent to this air volume range. The frequency of turning on and off the compressor can be reduced. Therefore, the rotational speed control type positive displacement compressor V used in a smaller air flow range than the air flow range is operated at full load, and the capacity of the turbo compressor T is controlled by suction throttle control.

  If the consumed air volume exceeds 380, the necessary air volume cannot be generated unless all three types of compressors V, S, and T are used. In that case, in order to avoid the constant wind pressure control of the turbo compressor T accompanied by the air discharge, the turbo compressor T is set to a range in which the suction throttle control is possible. That is, the generated air volume of the turbo compressor T is 200 or more. Further, since the on-off positive displacement compressor S is most efficiently operated in the full load operation (100% load) state, the generated air volume of the on-off positive displacement compressor S is set to 100. Accordingly, in the range of 380 to 400, the on-off displacement compressor S is operated at full load, and the turbo compressor T is operated at load at almost the lower limit capacity of the suction throttle control, and the necessary remaining amount is controlled by the rotational speed. The capacity of the positive displacement compressor V is adjusted.

  In the range of air consumption 400 to 480, the full load operation of the on / off displacement compressor S is the same as in the case of the air consumption 380 to 400, but the rotational speed control displacement compressor V is also operated at full load. Let Since the remaining necessary air volume is 200 to 280, and is within the suction throttle control range (196 to 280) of the turbo compressor T, the capacity of the turbo compressor T is adjusted. The same amount of air can be obtained by operating the turbo compressor T at the lower limit of the suction throttle control and controlling the rotational speed control type positive displacement compressor V. However, as described above, the turbo compressor T The suction throttle control operation is more efficient in terms of power consumption than the rotational speed control operation of the rotational speed control type positive displacement compressor V. Therefore, the rotational speed control type positive displacement compressor V is operated at the maximum air volume. It is good.

  When the number of the three compressors shown in FIG. 2 is controlled based on the optimum combination of the V, S, and T airflows, when the airflow is gradually increased from the state of zero airflow consumption to 480, the maximum airflow consumption. The state of each compressor 2-4 is shown in FIG. According to the subdivided states 1 to 26, the operation states of the three types of compressors V, S, and T change as shown in FIG.

In the range _RA of the consumed air volume 0 to 100, when all the compressors V, S, T are stopped, the rotational speed control type displacement compressor V is started (state 1). Thereafter, the capacity is adjusted by the rotational speed control type positive displacement compressor according to the required capacity (abbreviated as "condition" in Table 3) (state 2).

When moving from the range _{R A} consumer air volume 0-100 in the range _{R B} consumption airflow 100-200, first speed control type displacement type compressor V is full-load operation (abbreviated as 100% in Table 3) (state 3). When the discharge gas pressure decreases to the preset lower limit set pressure LL, the on-off positive displacement compressor S is started (state 4). Since the on-off positive displacement compressor S can only perform full load operation or no load operation, the full load operation is performed to reduce the number of on / off operations, and the capacity is adjusted (state 5) by the rotational speed control displacement compressor V.

To shift to the range _{R C} of consumption airflow 200 to 280 from a range _{R B} consumption airflow 100 to 200, the rotational speed controlled positive displacement compressor V also when the became full load operation (state 6), the discharge This is when the gas pressure drops to a preset lower limit pressure LL. In this case, the turbo compressor T is started to further increase the generated capacity of the compressor (state 7).

  During operation of the turbo compressor T, capacity adjustment (state 8) is preferentially performed by suction throttle control. Since the capacity of the turbo compressor T is larger than the lower limit capacity (70%) of the suction throttle control compared to the other compressors V and S, the capacity of the turbo compressor T can be started once the turbo compressor T is started. Is fixed to the lower limit capacity (state 9).

  Since the turbo compressor T is started, the discharge pressure increases rapidly and exceeds the required discharge pressure. Therefore, the capacity of the rotational speed control type positive displacement compressor V is adjusted while comparing with the required discharge pressure (state 10), and if the required discharge pressure is exceeded, the rotational speed control type positive displacement compressor V is stopped ( State 11). When stopping the rotational speed control type positive displacement compressor V, it can be stopped after the rotational speed is reduced to the minimum rotational speed, so that no loadless operation or the like which causes unnecessary power consumption is not required. Further, since the starting current can be kept low, it can cope with frequent start / stop.

  Since the turbo compressor T is activated, the discharge gas pressure exceeds the preset upper limit pressure LL only by stopping the rotational speed control type displacement compressor V. Therefore, the on-off positive displacement compressor S is operated without load (state 12). By the way, in the on-off positive displacement compressor S, since the number of times the motor is started is limited, it is better not to stop it unnecessarily. Therefore, the on-off compressor S is made to stand by in the no-load operation state, and it is confirmed that it does not return to the load operation even after a predetermined time has passed (that is, it does not require compressed air), and is stopped.

  Note that the rotation speed control type positive displacement compressor V does not impose a load on the motor at the time of start-up, so there is no limit on the number of times of start-up. Therefore, it can cope with frequent start and stop. Thus, the rotational speed control type positive displacement type V is always activated and stopped with priority, and the occurrence of damage due to frequent activation / deactivation of the on / off type displacement type compressor S is prevented. Further, if the discharge pressure rises during no-load operation, the on-off positive displacement compressor S is returned to 100% load operation. Since some power is consumed even in no-load operation, the on-off positive displacement compressor S is also stopped when the no-load operation continues for a long time.

  Thereafter, the capacity is adjusted by the suction throttle control of the turbo compressor T (state 13). The on-off positive displacement compressor S continues the no-load operation until a preset set time elapses. When this set time has elapsed, it is determined that the operation of the on-off positive displacement compressor S is unnecessary and is stopped (state 14).

In the state of transition from the range _RC of the air consumption 200 to 280 to the range _RD of the air consumption 280 to 300, the discharge gas pressure is reduced to the preset lower limit pressure LL even when the turbo compressor T is operated at full load. Thus, another compressor is required. In this case, the rotational speed control type positive displacement compressor V, which has no start / stop restrictions and can be easily started, is started (state 15), and the rotational speed control type positive displacement compressor V is operated at full load (state 16). The full capacity operation of the rotational speed control displacement compressor V is considered to exceed the required capacity with the turbo compressor T operating at full load, so the capacity of the turbo compressor T is controlled by suction restriction. Adjust and throttle down to the lower limit capacity (70%) of the suction throttle control (state 17). Even in this state, there is a high possibility that the discharge pressure will exceed the preset upper limit pressure LL, so that the capacity of the rotational speed control type positive displacement compressor V is adjusted from full load operation (state 18).

When migrating to a range R _E consumption airflow 300 to 380 from a range R _D consumption airflow 280-300 and if no capacity adjustment wide turbo-type compressor T of longer capacitance adjustment range, speed control type displacement type compressor Since the machine V is in full load operation (state 19), the required capacity cannot be generated. Therefore, the capacity of the turbo compressor (T) is adjusted by suction throttle control (state 20).

When shifting from the range R _E of the consumed air volume 300 to 380 to the range R _F of the consumed air volume 380 to 400, both the turbo compressor T and the rotational speed control displacement compressor V are in full load operation (state 21). Even so, the discharge gas pressure is in a state of decreasing to a preset lower limit pressure LL. Therefore, the on-off positive displacement compressor S is started as the third compressor (state 22).

  The on-off positive displacement compressor S is operated at full load in order to avoid repeated no load / load. Therefore, the turbo compressor T that has been operating at 100% load is suction throttle controlled to adjust the capacity (state 23), and is throttled to the lower limit capacity (70%) of the suction throttle control (state 24). In this state, since the two displacement type compressors V and S are in full load operation, there is a high possibility that the discharge gas pressure will rise to a preset upper limit pressure LL. Therefore, the capacity is adjusted by the rotational speed control type positive displacement compressor V (state 25).

When migrating to a range _{R G} Consumption air volume 400 to 480 from a range _{R F} consumption airflow 380-400 are two displacement type compressor V, S is both a full-load operation (state 26), turbo-type The required capacity cannot be achieved unless the capacity of the compressor T is adjusted. Therefore, the capacity of the turbo compressor T is adjusted by controlling the suction throttle (state 27).

  The above shows one example of operation of the compressor system according to the present invention using the relationship shown in FIG. The present invention is not limited to this operation example, and can correspond to various operation methods. Therefore, the operation flowchart of the compressor system according to the present invention is shown in FIGS. 4A to 4C in the case of the compressor configuration similar to the above embodiment.

4A to 4C show operation flowcharts during the unit number control operation of the compressor system 100 including the plurality of compressors 2 to 4 shown in FIG. Here, the compressor V is a rotational speed control type positive displacement compressor, the compressor S is an on-off positive displacement compressor, and the compressor T is a turbo compressor. 4A is a flowchart of operation control mainly in R _A and R _B of FIG. 2, and FIG. 4B is a flowchart of operation control in a transition state in which the capacity is increased or decreased mainly from R _C and R _{C of} FIG. 4C is a flowchart of operation control mainly in R _{D to} R _G of FIG.

  When the number control of the compressor system 100 is started, first, the rotational speed control type displacement compressor V is started (step S110). Then, based on the measurement data of the discharge gas pressure detected by the pressure detector 52 and the deviation of the target pressure, the PI (or the motor) driving the rotational speed control type displacement compressor V from the number control panel 1 to the control panel 22 (or A PID control command is transmitted to adjust the capacity of the rotational speed control type positive displacement compressor V (step S140). That is, the number control panel 1 outputs a rotation speed command signal to the control panel 22 of the rotation speed control type positive displacement compressor V. Then, the control panel 22 of the rotational speed control type positive displacement compressor V returns the rotational speed command answerback signal to the number control panel 1 so that the operation state is monitored. If the target pressure has been reached and the target capacity has been achieved in step S150, the next control time is awaited (step S155).

  If the target pressure has not been reached and the turbo compressor T is not in operation in step S160, the unit control panel 1 determines whether or not the rotational speed control type displacement compressor V is in full load operation (step S170). Investigate. If the compressor V is in full load operation, it is determined in step S180 whether or not the operating pressure detected by the pressure detector 52 is higher than the set minimum pressure LL. When the pressure is lower than the set minimum pressure, the capacity of the compressor is insufficient. Therefore, it is checked in step S190 whether there is an on-off positive displacement compressor S that is on standby. If there is an on-off positive displacement compressor S that is on standby, the timer Tm1 during measurement of the no-load operation time of the on-off positive displacement compressor S is reset and the count is stopped (step S192). Then, the on-off positive displacement compressor S that is on standby is started to operate at full load (step S194), and the node A is returned to.

  If the operating pressure is higher than the set minimum pressure in step S180, the capacity is adjusted to return to the node A and the rotational speed control type displacement compressor V is adjusted. If the rotational speed control type positive displacement compressor V is not at full load operation in step S170, it is determined in step S200 whether the rotational speed control type positive displacement compressor V is in minimum load operation. If it is not the minimum load operation, it returns to the node A. If the rotational speed control type positive displacement compressor V is operated at the minimum load and the operating pressure is less than the set maximum pressure HH, the operation returns to the node A.

  If the operating pressure is equal to or higher than the set maximum pressure HH, it is checked in step S220 whether there is an on-off positive displacement compressor S during full load operation. If there is an on-off positive displacement compressor S during full-load operation, the timer Tm1 for counting the no-load operation time of the on-off positive displacement compressor is started (step S222), and the on-off positive displacement compressor is disabled. Load operation is performed (step S224). If there is no on-off positive displacement compressor S during full-load operation, there is no request for the amount of compressed gas generated by the compressor system, so the rotational speed control displacement compressor V is stopped (step S230). In this case, it is confirmed whether the pressure of the compressed air supply line detected by the pressure detector 52 has decreased, and the initial state of the number control flow is restored. If the line pressure has decreased, the rotational speed control type positive displacement compressor V is restarted. If not, it is determined whether or not to restart after a predetermined time has elapsed.

  In FIG. 4A, after the node A, there are a timer Tm1 that measures the no-load operation elapsed time of the on-off positive displacement compressor S and a timer Tm2 that measures the constant wind pressure control operation elapsed time of the turbo compressor T. It includes a step of determining whether or not a predetermined time has elapsed (steps S120 and 130) and a step of stopping the compressors S and T when the measurement time has elapsed (S125 and 135). These are the steps required at the time of transition from the operating state of FIGS. 4B and 4C.

  FIG. 4B is an operation flowchart when the target capacity is large and the turbo compressor T is started. Since the turbo compressor T is started, the constant wind pressure control operation time of the turbo compressor T is measured, and when it continues for a predetermined time, the timer Tm2 for stopping the turbo compressor is reset and stopped (step S310). Then, the turbo compressor T is activated (step S320).

  Since the turbo compressor T is activated, the capacity of the turbo compressor T is adjusted (step S330). That is, the control panel 41 of the turbo compressor T performs PI control or PID control using the deviation between the measurement data of the discharge gas pressure and the target pressure, and controls the suction and throttle of the turbo compressor T. Here, the unit control panel 1 may perform suction throttle control of the turbo compressor T by PI or PID control using the deviation between the measurement data of the discharge gas pressure and the target pressure. Since the suction throttle control range changes depending on the suction gas temperature, it is necessary to take in the suction gas temperature signal, the discharge gas pressure, and the motor current value, which is not preferable. Therefore, in this embodiment, the control panel 41 of the turbo compressor T performs suction throttle control.

  Next, it is determined whether or not the target pressure has been reached in step S340, and if it has reached, the next control time is awaited (step S345). If the target pressure is not reached, it is checked in step S350 whether the turbo compressor T is in the minimum load operation (70% load operation). If the turbo compressor T is operating at the minimum load, it is determined in step S360 whether or not the operating pressure is equal to or lower than the set maximum pressure.

  On the other hand, if the turbo compressor T is operated at the minimum load and the target pressure is exceeded, the supply from the compressor system 100 is excessive, so the capacity of the rotational speed control type displacement compressor V is adjusted (step S370). . If the target pressure is achieved (step S380), the process waits for the next control time (step S385). If the target pressure cannot be achieved, it is determined in step S390 whether or not the rotational speed control type positive displacement compressor V is operating at a minimum load.

  When it is determined that the rotational speed control displacement compressor V is operating at the minimum load and the operating pressure is higher than the set maximum pressure (step S400), the supply of compressed gas is excessive, so that the operation of the compressor system 100 is performed. One of the compressors inside will be stopped. Therefore, in step S410, it is checked whether or not there is an on-off positive displacement compressor S during full load operation. If there is an on-off positive displacement compressor S in full load operation, in preparation for stopping this compressor S, a timer Tm1 that measures the no-load time of the on-off positive displacement compressor S starts counting in step S412. . At the same time, the on-off positive displacement compressor S is operated without load in step S414. Since the ON / OFF type displacement compressor S has a limited number of start / stops, it is first operated without load when the stop condition is reached in order to avoid frequent start / stops, and the no-load operation time continues for a predetermined time. Only when is the on-off positive displacement compressor considered to be unused. When there is no on-off positive displacement compressor S during full load operation, the process proceeds to node D.

  If it is determined in step S350 that the turbo compressor T is not operating at the minimum load, it is determined in step S420 whether the turbo compressor T is operating at full load. When the turbo compressor T is operating at full load, the process proceeds to step S430, and it is determined whether or not the operating pressure exceeds the set minimum pressure. Since the pressure does not increase even when the turbo compressor T is operated at full load, the compressor system 100 is insufficiently supplied, so there is no on-off positive displacement compressor S that is waiting for no load operation or being stopped. Is checked in step S440. If there is no on-off positive displacement compressor S in standby, the capacity of the compressor system 100 is exceeded, so the process proceeds to node X. In this case, compressed gas is supplied from another compressor not included in the compressor system 100, or the control of the number of compressors is stopped. Or the consumption of the demand source is suppressed.

  If there is a waiting on-off type displacement compressor S, the timer Tm1 that has measured the no-load operation time of the on-off type displacement compressor S is reset, and the count is stopped (step S450). At the same time, the on-off positive displacement compressor S is started and operated at full load (step S460).

FIG. 4C shows an operation control flowchart when the operation is performed in the region _RC in FIG. 2 and the region _RC is shifted to another region. In order to shift to the region _{RC in} FIG. 2, the rotational speed control type positive displacement compressor V is stopped in step S510. Since the turbo compressor T is activated, the control panel 41 of the turbo compressor T sucks and throttles the turbo compressor T by PI or PID control using the measured data of the discharge gas pressure and the deviation of the target pressure. Control is performed (step S520). In step S530, it is determined whether or not the target pressure is reached by the capacity control. If the target pressure is reached, the next control timing is awaited in step S535.

  If it is not the target pressure, it is determined in step S540 whether the turbo compressor T is in the minimum load operation, and if it is the minimum load operation, it is checked whether the operation pressure is less than the set maximum pressure HH. (Step S550). In order to stop the turbo compressor T, a timer Tm2 for measuring the no-load operation time of the turbo compressor T is provided in order to stop the turbo compressor T when the turbo compressor T exceeds the set maximum pressure even in the minimum load operation. Counting is started (step S560), and the turbo compressor T is caused to perform no-load operation (air discharge operation) (step S570). Next, instead of the turbo compressor T, the rotational speed control type displacement compressor V is started (step S580) to meet the demand.

  On the other hand, when it is determined in step S540 that the turbo compressor T is not in the minimum load operation, the process proceeds to step S590, and it is checked whether the turbo compressor T is in full load operation (step S590). If the turbo compressor T is operating at full load, it is determined whether or not the operating pressure is lower than the set minimum pressure LL. If the operating pressure is lower than the set minimum pressure, the supply is insufficient. The operation is changed to a combination of a rotational speed control type positive displacement compressor V and a turbo compressor T. Therefore, the turbo compressor T is set to the minimum load operation (step S610), and the rotational speed control type displacement compressor V is started (step S620).

  As described above, according to the present embodiment, the rotational speed control type positive displacement compressor V is combined with the compressor system as a compressor that can be used without limitation on the number of start / stop operations. There is no need to perform no-load operation when the compressor is stopped, and the compressor can be stopped immediately, so that power consumption can be reduced. In addition, an on-off positive displacement compressor and a turbo compressor, which have a limited number of start / stop operations, are combined in accordance with the required air volume so that they can be operated continuously as much as possible. Power loss can be reduced. In addition, since the number of times of starting / stopping the on-off positive displacement compressor and the turbo compressor is reduced, the life of the on-off positive displacement compressor and the turbo compressor can be extended.

  Furthermore, the number control panel only needs to control the number of operating units, and the compressor control panel included in each compressor controls the capacity of the corresponding compressor. In the turbo compressor, since the turbo compressor control panel performs the surging avoidance operation, a complicated input signal system is not required between the number control panel and the compressor control panel. Therefore, the number control panel does not need to be involved in the control to avoid the surging of the turbo compressor, and can realize the number control of the compressor with a simplified signal system.

DESCRIPTION OF SYMBOLS 1 ... Unit control panel, 2 ... Revolution-control type positive displacement compressor, 3 ... On-off positive displacement compressor, 4 ... Turbo compressor, 5 ... Receiver tank, 6 ... Gas piping, 21 ... Compressor control panel, DESCRIPTION OF SYMBOLS 22 ... Pressure detector, 31 ... Compressor control board, 32 ... Pressure detector, 41 ... Compressor control board, 42 ... Pressure detector, 52 ... Pressure detector, 100 ... Compressor system, S ... On-off displacement type Compressor, T ... turbo compressor, V ... rotational speed control type positive displacement compressor.

Claims (4)

At least one turbo-type compressor that has a suction throttle valve, adjusts the amount of intake gas by adjusting the amount of intake gas by the suction throttle valve, and an electric motor, and adjusts the capacity by controlling the rotational speed of the electric motor Equipped with a rotary speed control positive displacement compressor and an on / off positive displacement compressor that adjusts the capacity by repeating load operation and no load operation, and these turbo compressor and rotation control positive displacement compressor are turned on and off. In the compressor system in which the discharge side of the positive displacement compressor is piped in parallel,
Each of the turbo compressor, the rotational speed control type positive displacement compressor and the on / off type positive displacement compressor has a compressor control means, and detects a discharge pressure which is a pressure downstream of the parallel pipe connection portion. And a unit control panel for inputting a discharge pressure detected by the discharge pressure detection unit and outputting a control command to each compressor control panel. The unit control panel is a turbo compressor. When the engine is in operation, it outputs a control command to the control panel of the turbo compressor so that the capacity of the turbo compressor is preferentially controlled, and the turbo compressor is in a stopped or no-load operation or suction throttle control range At the lower limit of the compressor system, the compressor system outputs a control command to a compressor control panel of the rotational speed control type positive displacement compressor so that the capacity of the rotational speed control type positive displacement compressor is controlled.   2. The capacity control of the turbo compressor according to claim 1, wherein when the turbo compressor is in capacity control, the control panel of the turbo compressor performs capacity control using the suction throttle valve without using the number control panel. Compressor system.   The lower limit of the suction throttle control range of the turbo compressor is equal to or less than the sum of the rated capacities of the on-off positive displacement compressor and the rotational speed control positive displacement compressor, and the rated capacity of the turbo compressor is 3. The compressor system according to claim 1, wherein the compressor system is equal to or greater than a sum of rated capacities of the on-off positive displacement compressor and the rotation speed control positive displacement compressor. At least one turbo-type compressor that has a suction throttle valve, adjusts the amount of intake gas by adjusting the amount of intake gas by the suction throttle valve, and an electric motor, and adjusts the capacity by controlling the rotational speed of the electric motor Equipped with a rotary speed control positive displacement compressor and an on / off positive displacement compressor that adjusts the capacity by repeating load operation and no load operation, and these turbo compressor and rotation control positive displacement compressor are turned on and off. In the operation control method of the compressor system in which the discharge side of the positive displacement compressor is pipe-connected in parallel,
When the turbo compressor is operating, the capacity is preferentially controlled by the turbo compressor, and when the turbo compressor is stopped or during no-load operation or at the lower limit of the suction throttle control range, the rotational speed control formula An operation control method for a compressor system, wherein the displacement of the positive displacement compressor is controlled.

Images