JP2010053733A - Method and device for controlling the number of operated air compressors - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce initial cost by improving workability and by securing measurement reproducibility of an index required for controlling the number of operated air compressors. <P>SOLUTION: The air compressors 1-1 to 1-n are provided with wattmeters 4-1 to 4-n. Electric power values Epv1 to Epvn of the air compressors 1-1 to 1-n measured by the wattmeters 4-1 to 4-n and a pressure value (a measured value of header pressure) Ppv in a header 2 measured by a pressure transmitter 3, are sent to a device for controlling the number of operated air compressors 5. The device for controlling the number of operated air compressors 5 sets one of the asir compressors 1 being a stopping state in a load state, when an allowance of capacity determined from the electric power value of the whole air compressors 1 in the load state becomes a threshold value or less, when a state where the measured value Ppv of the header pressure is less than an increased stage pressure lower limit value PL, continues for a predetermined time or more, when a load increases. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for controlling the number of operating air compressors for controlling the number of operating air compressors that send compressed air to an air tank based on the state of compressed air sent from an air tank to a load.

  Conventionally, as a compressed air supply system for building equipment power and instruments, a plurality of air compressors that generate compressed air, and an air tank in which compressed air sent from these air compressors is stored, 2. Description of the Related Art An air compressor operation number control system that controls the number of operating air compressors based on the state of compressed air sent from an air tank to a load is used.

  As this type of system, for example, in the air compressor operation number control system shown in Patent Document 1, the flow rate of compressed air to the load sent out from the air tank is measured, and the measured flow rate of this compressed air is preset. If one of the air compressors that are not in the loaded state (the state in which compressed air is being sent out) is unloaded (compressed air is being operated, but the compressed air is being sent out) The air compressor that is in the state of not being in the load state is prioritized over the air compressor that is in the stopped state, while the flow rate change of the compressed air to the load sent from the air tank from the previous value and the current value of the measured flow rate Calculate the time from the change in the compressed air flow rate until the current flow rate reaches the nearest step increase flow rate as the step increase point arrival time. If it is shorter than the rise time from the stopped state, it is assumed that there is no unloaded air compressor, and one of the air compressors in the stopped state is unloaded from the plurality of air compressors. The load state is set.

  In addition, when the pressure in the air tank is measured and this measured pressure is less than or equal to a preset pressure lower limit value, any one of the plurality of air compressors that are not in a loaded state is unloaded. The air compressor in the loaded state is preferentially placed in the loaded state. Also, measure the flow rate of compressed air to the load sent out from the air tank, measure the pressure in the air tank, and to the load with the measured pressure in the air tank above the preset pressure lower limit value. If the measured flow rate of compressed air is less than or equal to the preset nearest stepped flow rate, or if the measured pressure in the air tank exceeds the preset upper pressure limit, multiple air compressors Among them, any one of the air compressors in the loaded state is set to the unloaded state.

  In this air compressor operation number control system, a load state and an unload state are provided in the operation state of the air compressor so that the air compressor can be shifted from the unload state to the load state instead of from the stopped state. By doing so, it is possible to immediately respond to the load fluctuation.

JP 2003-214354 A

  However, according to the air compressor operation number control system shown in Patent Document 1 described above, in addition to the sensor (pressure transmitter) for measuring the pressure in the air tank, the compressed air to the load sent from the air tank A flow meter for measuring the flow rate is required, and reproducibility of the flow rate measurement is required to obtain the effect. In order to ensure the reproducibility of the flow rate measurement, a straight pipe part is required before and after the installation position, and the installation position is restricted. In addition, since it takes time and effort at the time of construction, the barrier to the introduction of this technology is increased.

  The present invention has been made in order to solve such problems, and its purpose is to ensure the reproducibility of measurement of an index necessary for controlling the number of operating air compressors and improve the workability. Therefore, an object of the present invention is to provide a method and an apparatus for controlling the number of operating air compressors that can reduce the initial cost.

  In order to achieve such an object, the present invention includes a plurality of air compressors that generate compressed air, and an air tank in which compressed air sent from these air compressors is stored, from the air tank to the load. In the air compressor operation number control method for controlling the number of operating air compressors based on the state of compressed air sent out, a pressure measuring step for measuring the pressure of the compressed air to the load sent out from the air tank, and the air compressor A power measurement step for measuring the current power consumption for each of the air compressors, a capacity margin calculating step for calculating the capacity margin from the power consumption measured for each of the air compressors, and a measurement of the pressure of the compressed air An operation number control step for controlling the number of operating air compressors based on the value and the capacity of the air compressor is provided.

  In the present invention, in the operation number control step, for example, a state where the measured value of the pressure of compressed air falls below a preset first pressure threshold value continues for a predetermined time or more, and there is a margin of capacity for each air compressor. If the capacity margin of all the air compressors in the loaded state where compressed air is being sent falls below the preset minimum capacity margin value, one of the stopped air compressors is in the loaded state. And

  In this case, the load increases and the measured value of the pressure of the compressed air falls below the first pressure threshold value (stepped pressure lower limit value PL (for example, PL = 0.50 MPa)) for a predetermined time (for example, 60 seconds), and if the capacity margin of all the air compressors in the loaded state is less than the minimum capacity margin value (for example, 0%) or less, one of the air compressors in the stopped state is Switch to loading state.

  In this invention, the measured value of the pressure of compressed air can be obtained from an existing pressure transmitter, and the capacity of the air compressor can be obtained by using a wattmeter. The power meter is less expensive than the flow meter and has less restrictions on installation conditions to ensure measurement reproducibility. For example, when the measured power is Epv and the rated power unique to the device is Ecs, the capacity allowance η of the air compressor can be obtained as η = (1−Epv / Ecs) × 100 [%]. This makes it possible to improve workability and reduce initial costs without using a flow meter. As a result, the barrier to introduction becomes lower than in the past.

  In the present invention, the air tank may be a header, a tank provided between the air compressor and the header, or a combination of the header and the tank may be an air tank. Further, the capacity margin of the air compressor can be obtained by using an ammeter instead of the wattmeter. For example, when the measured current is Ipv and the rated current specific to the device is Ics, the capacity η of the air compressor can be obtained as η = (1−Ipv / Ics) × 100 [%]. Thus, in the present invention, the current Ipv may be measured instead of the power Epv. The definition of the measurement of power consumption in the present invention includes not only the measurement of the power Epv but also the measurement of the current Ipv.

  Further, in the present invention, in the operation number control step, for example, an air compressor that was in a load state that is sending compressed air is switched to an unload state that is being operated but not sending compressed air, When the unloaded state continues for a predetermined time or more, or the capacity margin of all the air compressors in the loaded state out of the capacity margin for each air compressor exceeds the preset capacity margin threshold Is continued for a predetermined time or longer, one of the air compressors in the unloaded state is brought into a stopped state.

  In this way, when the load decreases and the unloading state of the air compressor that has been switched from the loading state to the unloading state continues for a predetermined time (for example, 5 minutes) or longer, 1 of the air compressor in the unloading state The stand is stopped. Alternatively, a state in which the load decreases and the capacity margin of all the air compressors in the loaded state exceeds a preset capacity margin threshold (for example, 15%) is a predetermined time (for example, 5 minutes) or more. When continuing, one of the air compressors in the unloaded state is brought into a stopped state.

  Further, the first pressure threshold value in which the measured value of the compressed air pressure is set in advance in the operation number control step in combination with the switching from the stopped state to the loaded state and the switching from the unloaded state to the stopped state. The minimum capacity margin that the capacity margin of all the air compressors in the load state where compressed air is sent out of the capacity margin for each air compressor continues for a predetermined time or more and is set in advance. If the value is less than or equal to the value, one of the air compressors that are in a stopped state is placed in the load state, while the air compressor that was in the load state that is sending out compressed air is being operated, but is sending out compressed air. When the unloading state is switched over to the unloaded state and the unloaded state continues for a predetermined time or more, or all of the load state is out of the capacity margin for each air compressor. When the capacity of the air compressor exceeds the preset capacity margin threshold for a predetermined time or longer, one of the uncompressed air compressors is set to the stop state. Also good.

  In the present invention, when the upward trend of the measured value of the compressed air pressure continues for a predetermined time (for example, 20 minutes) or more, or the first pressure threshold value in which the measured value of the compressed air pressure is preset. When the air pressure exceeds a second pressure threshold value (unload switching pressure value PH (for example, PH = 0.75 MPa)) that is greater than or equal to, one of the air compressors in the loaded state is switched to the unloaded state. May be. Further, in the present invention, a third pressure threshold (load switching pressure value PLA (for example, PLA = for example, PLA =) is greater than the preset pressure threshold of 1 and smaller than the second pressure threshold. 0.55 MPa)) When the following state continues for a predetermined time (for example, 1 second) or more, one of the air compressors in the unloaded state may be switched to the loaded state.

  In addition, when the unloading state of the air compressor switched from the loading state to the unloading state continues for a predetermined time (for example, 5 minutes) or when the load value is measured out of the measurement values of the power consumption for each air compressor. The capacity of all the air compressors in the state is in the unloaded state when the state exceeding the preset capacity margin threshold (for example, 15%) continues for a predetermined time (for example, 5 minutes) or more. On condition that the current number of air compressors exceeds a predetermined minimum operating number (for example, one), one of the air compressors in the unloaded state is brought into a stopped state. It may be.

  Further, the present invention can be realized not only as a method for controlling the number of operating air compressors but also as a device for controlling the number of operating air compressors. The invention according to claims 8 to 14 implements the air compressor operation number control method according to claims 1 to 7 as an air compressor operation number control device, respectively.

  According to the present invention, the pressure of the compressed air to the load delivered from the air tank is measured, the current power consumption is measured for each of the air compressors, and the current power measured for each of the air compressors The capacity margin is calculated from the amount of air consumed, and the number of operating air compressors is controlled based on the measured value of the compressed air pressure and the capacity capacity of the air compressor. All the air compressors in a load state in which the measured value is lower than the preset first pressure threshold value continues for a predetermined time or more and the compressed air is sent out of the capacity margin of each air compressor When the capacity margin of the engine is less than the preset minimum capacity margin value, one of the air compressors that are in a stopped state is put into a load state, or the air compressor that is in a load state that is sending out compressed air But driven Is switched to an unloaded state in which compressed air is not sent out and the unloaded state continues for a predetermined time or more, or all the air compressors in the loaded state within the capacity margin for each air compressor When the capacity surplus exceeds the preset capacity surplus threshold for a predetermined time or longer, one of the air compressors in the unloaded state is stopped and the flow meter Without using the above, the number of operating air compressors can be controlled and controlled using an existing pressure transmitter or a cheap and easy-to-work wattmeter, and energy saving can be achieved. In addition, it is possible to improve workability at the time of introduction and to reduce the initial cost.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an instrumentation diagram showing an example of an air compressor operation number control system used for implementing an air compressor operation number control method according to the present invention.

  In the figure, 1-1 to 1-n are air compressors (compressors) that generate compressed air, 2 is a header into which compressed air from the air compressors 1-1 to 1-n is sent, and 3 is in the header 2 Pressure transmitters 4-1 to 4-n measure the current power consumption for each of the air compressors 1-1 to 1-n as a power value Epv1. ˜Epvn wattmeter, 5 is an air compressor operation number control device.

  In this embodiment, the air compressors 1-1 to 1-n are a compressor group regardless of manufacturer and capacity, and are constituted by a plurality of constant speed machines or inverter machines. In this example, the air compressors 1-1 to 1-n are constant speed machines having the same manufacturer and capacity.

  The air compressor operation number control device 5 is sent from the pressure value (measured value of header pressure) Ppv of the compressed air to the load sent from the pressure transmitter 3 and the wattmeters 4-1 to 4-n. The power values (measured values of power) Epv1 to Epvn of the air compressors 1-1 to 1-n are input, and the measured values Ppv of the header pressure and the power of the air compressors 1-1 to 1-n are input. The number of operating air compressors 1-1 to 1-n is controlled based on the measured values Epv1 to Epvn.

  As described in the conventional example, there are three operating states of the air compressor 1 (1-1 to 1-n): “load state”, “unload state”, and “stop state”. The state in which 1 is sending out compressed air is called a load state, the state in which the air compressor 1 is operated but not sending out compressed air is called the unload state, and the air compressor 1 is not in operation Is called a stopped state.

  FIG. 2 shows an outline of an internal configuration of an air compressor operation number control device (hereinafter simply referred to as a control device) 5. The control device 5 includes a CPU 5-1, a ROM 5-2, a RAM 5-3, and interfaces 5-4 to 5-6. The CPU 5-1 receives the measured value Ppv of the header pressure from the pressure transmitter 3 via the interface 5-4, and the air compressor 1- 4-n from the wattmeters 4-1 to 4-n via the interface 5-5. Measurement values Epv1 to Epvn of powers 1 to 1-n are given. The CPU 5-1 executes processing while accessing the RAM 5-3 according to the program stored in the ROM 5-2 on the basis of the input header pressure measurement value Ppv and the power measurement values Epv 1 to Epvn. Create control commands to machines 1-1 to 1-n.

In addition to the above-described program, the ROM 5-2 is set with an increase pressure lower limit value PL, a forced increase pressure lower limit value P _LIM , an unload switching pressure value PH, and a load switching pressure value PLA, which will be described later. In this example, the step-up pressure lower limit (first pressure threshold) PL is 0.50 MPa, the forced step-up pressure lower limit P _LIM is 0.45 MPa, and the unload switching pressure value (second pressure threshold) PH is 0. The load switching pressure value (third pressure threshold) PLA is 0.55 MPa. FIG. 3 shows a relationship among the step-up pressure lower limit value PL, the forced step-up pressure lower limit value P _LIM , the unload switching pressure value PH, and the load switching pressure value PLA. Further, the ROM 5-2 is set with a minimum operation number N _{MIN of} unloaders described later. In this example, it is assumed that the set number of the minimum operation number N _MIN of unloaders is one.

  Hereinafter, processing operations unique to the present embodiment executed by the CPU 5-1 will be described with reference to an image diagram of the increase / decrease stage logic shown in FIG. 4 and flowcharts shown in FIGS. 5 to 8.

[Stop → Load operation switching]
The CPU 5-1 measures the header pressure measurement value Ppv from the pressure transmitter 3 and the power measurement values Epv <b> 1 to 1-n of the air compressors 1-1 to 1 -n from the power meters 4-1 to 4 -n at a predetermined cycle. Epvn is read (FIG. 5: Steps S101 and S102).

(Forced increase)
Assume that the air compressor 1-1 is in a loaded state and the air compressors 1-2 to 1-n are in a stopped state. It is assumed that the header pressure measurement value Ppv is equal to or less than the forced step-up pressure lower limit value PLIM. In this case, the CPU 5-1 confirms that the state in which the header pressure measurement value Ppv is below the forced increase pressure lower limit value P _LIM (0.45 MPa) has continued for a certain time (for example, 1 second) or more. (YES in steps S103 and S104), one of the air compressors 1-2 to 1-n, for example, the air compressor 1-2 is switched from the stopped state to the loaded state (step S109, arrow shown in FIG. 4). (1)). Thereby, the operation of the stopped air compressor 1-2 is started, and the compressed air generated by the air compressor 1-2 is sent out to the header 2.

[Increase]
Assume that the air compressor 1-1 is in a loaded state and the air compressors 1-2 to 1-n are in a stopped state. Further, it is assumed that the header pressure is decreasing as the load increases.

  In this case, the CPU 5-1 confirms whether or not the state in which the header pressure measurement value Ppv is lower than the step-up pressure lower limit PL (0.50 MPa) has continued for a certain time (60 seconds) or more (step S105, S106).

  Further, with respect to all the air compressors 1 in the loaded state, a capacity margin is obtained from the measured power value, and it is confirmed whether or not the capacity margin is 0% or less (step S107). Here, when the measured power is Epv and the rated power specific to the device is Ecs, the capacity η of the air compressor can be obtained as η = (1−Epv / Ecs) × 100 [%]. In this case, since the air compressor 1 in the loaded state is only the air compressor 1-1, it is confirmed whether or not the capacity margin of the air compressor 1-1 is 0% or less.

  Here, the state where the measured value Ppv of the header pressure is below the step-up pressure lower limit PL is continued for a certain time (60 seconds) or more, and the capacity of the air compressor 1-1 is 0% or less. Upon confirmation (YES in step S108), the CPU 5-1 switches one of the air compressors 1-2 to 1-n, for example, the air compressor 1-2, from the stopped state to the loaded state (step S109, Arrow (1) shown in FIG.

  As a result, not only the header pressure information on the demand side but also the power at the time of full operation of all the air compressors 1 in the load state can be increased, and wasteful operation can be eliminated. The operation that maximizes the capacity of the air compressor 1 can be performed.

[Switching from load operation to unload operation]
Assume that the air compressors 1-1 and 1-2 are in a loaded state and the air compressors 1-3 to 1-n are in a stopped state. Further, it is assumed that the header pressure is increasing as the load decreases.

  In this case, the CPU 5-1 reads the header pressure measurement value Ppv from the pressure transmitter 3 at a predetermined cycle (FIG. 6: step S201), and measures the header pressure measurement value Ppv and the unload switching pressure value PH (0. 75MP), and if the measured value Ppv of the header pressure exceeds the unload switching pressure value PH (YES in step S202), it is confirmed that there is at least one air compressor 1 in the loaded state (step One of them is switched from the loaded state to the unloaded state (step S207, arrow (2a) shown in FIG. 4). In this case, since the air compressor 1 in the loaded state is the air compressors 1-1 and 1-2, for example, the air compressor 1-2 is switched from the loaded state to the unloaded state.

  In parallel with the process of step S202, the CPU 5-1 calculates a change ΔP (ΔP = current value−previous value) of the header pressure measurement value Ppv (step S203). Here, when it is confirmed that the state of 0 <ΔP has continued for a certain time (20 minutes) or longer (YES in steps S204 and S205), that is, the increasing tendency of the header pressure measurement value Ppv continues for a certain time (20 minutes) or longer. After confirming that the CPU 5-1 confirms that there is at least one air compressor 1 in the loaded state (YES in step S206), one of them is switched from the loaded state to the unloaded state. (Step S207, arrow (2a) shown in FIG. 4). In this case, since the air compressor 1 in the loaded state is the air compressors 1-1 and 1-2, for example, the air compressor 1-2 is switched from the loaded state to the unloaded state.

  As a result, before the header pressure reaches the unload switching pressure value PH, the air compressor 1 in the loaded state is switched to the unloaded state with the increasing tendency of the header pressure, thereby saving energy.

[Unload operation → Load operation switching]
Assume that the air compressor 1-1 is in a loaded state, the air compressor 1-2 is in an unloaded state, and the air compressors 1-3 to 1-n are in a stopped state. Further, it is assumed that the header pressure is decreasing as the load increases.

  In this case, the CPU 5-1 reads the measured value Ppv of the header pressure from the pressure transmitter 3 at a predetermined cycle (FIG. 7: Step S301), and measures the measured value Ppv of the header pressure and the load switching pressure value PLA (0.55 MPa). ) And the state where the measured value Ppv of the header pressure is lower than the load switching pressure value PLA continues for a certain time (1 second) or longer (YES in steps S302 and S303), the air compressor 1 in the unloaded state Is confirmed (YES in step S304), one of them is switched from the unloaded state to the loaded state (step S305, arrow (2b) shown in FIG. 4). In this case, since the air compressor 1 in the unloaded state is only the air compressor 1-2, the air compressor 1-2 is switched from the unloaded state to the loaded state.

[Unload operation → Stop switching: Case 1]
Assume that the air compressor 1-1 is in a loaded state, the air compressor 1-2 is in an unloaded state, and the air compressors 1-3 to 1-n are in a stopped state. Further, it is assumed that the header pressure is increasing as the load decreases.

When the CPU 5-1 switches the air compressor 1-2 from the loaded state to the unloaded state (FIG. 8: Step S401), the CPU 5-1 checks the duration of the unloaded state (Step S402). Here, if the unloading state of the air compressor 1-2 continues for a certain time (5 minutes) or longer (YES in step S402), the current number of air compressors 1 in the unloading state is the minimum number of unloading machines. It is checked whether or not the operating number N _MIN (N _MIN = 1) has been exceeded (step S406).

In this case, the air compressor 1 in the unloaded state is only the air compressor 1-2, and does not exceed the minimum operating number N _MIN of the unloaded machines. Therefore, the CPU 5-1 does not stop the air compressor 1-2 and continues the unloading state of the air compressor 1-2.

In this state, it is assumed that the CPU 5-1 switches the air compressor 1-1 from the load state to the unload state. In this case, the CPU 5-1 checks the duration of the unload state of the air compressor 1-1 (step S402). Here, when the unloading state of the air compressor 1-1 continues for a certain time (5 minutes) or longer (YES in step S402), the CPU 5-1 determines that the current number of air compressors 1 in the unloading state is unloaded. It is checked whether or not the minimum operating number N _MIN of the load machine is exceeded (step S406).

In this case, the two air compressors 1 and 1-2 in the unloaded state exceed the minimum operating number N _MIN (N _MIN = 1) of the unloader. Therefore, the CPU 5-1 proceeds to step S407 in response to YES in step S406, and selects one of the air compressors 1-1 and 1-2 in the unloaded state, for example, the air compressor 1-2. Switching from the unloaded state to the stopped state (arrow (3) shown in FIG. 4). This restricts the number of unloaded air compressors, that is, minimizes the number of unloaded operations, thereby saving energy.

[Unload operation → Stop switching: Case 2]
On the other hand, in parallel with the processing of steps S401 and S402, the CPU 5-1 reads the measured values Epv1 to Epvn of the power of the air compressors 1-1 to 1-n from the wattmeters 4-1 to 4-n ( Step S403), the capacity margin is obtained for all the air compressors 1 in the load state, and whether or not this capacity margin exceeds a predetermined capacity margin threshold value (15% in this example). Is confirmed (step S404).

  It is assumed that the air compressor 1-1 is in a loaded state, the air compressors 1-2 and 1-3 are in an unloaded state, and the air compressors 1-4 (not shown) to 1-n are in a stopped state. . Further, it is assumed that the header pressure is increasing as the load decreases.

  In this case, since the air compressor 1 in the loaded state is only the air compressor 1-1, the CPU 5-1 confirms whether the capacity margin of the air compressor 1-1 exceeds 15%. . Under this situation, since the air compressor 1-1 is in a light load state, the power consumption thereof decreases.

Here, when the state in which the capacity of the air compressor 1-1 exceeds 15% continues for a certain time (5 minutes) or more (YES in step S405), the CPU 5-1 compresses the air in the unloaded state. It is checked whether or not the current number of machines 1 exceeds the minimum operating number N _MIN (N _MIN = 1) of the unloading machine (step S406).

In this example, the air compressor 1 in the unloaded state is two air compressor 1-2 and 1-3, has exceeded the minimum number of operating N _MIN unloading machine. Therefore, the CPU 5-1 proceeds to step S407 in response to YES in step S406, and sets one of the air compressors 1-2 and 1-3 in the unloaded state, for example, the air compressor 1-3. Switching from the unloaded state to the stopped state (arrow (3) shown in FIG. 4).

As a result, if the capacity margin of all the air compressors 1 in the loaded state exceeds 15% for a certain time (5 minutes) or longer, the minimum operating number N _MIN is exceeded and the unloaded state is set. Therefore, the air compressor 1 is stopped early without waiting for a certain time (5 minutes), and energy is saved.

  In the processing operation of the CPU 5-1 described above, the processing in steps S101, S201, and S301 corresponds to the pressure measurement step in the present invention, the processing in steps S102 and S403 corresponds to the power consumption measurement step, and step S107. , The processing for obtaining the capacity margin of all the air compressors in S404 corresponds to the capacity margin calculation processing, and the processing in steps S103 to S109 is the first processing in the operation number control step (stop load switching processing). Corresponding to In addition, the processes in steps S401 and S402 and steps S404 to S407 correspond to the second process (unload stop switching process) in the operation number control step, and the processes in steps S202 to S207 are in the operation number control step. Corresponding to the third process (load / unload switching process), the processes in steps S302 to S305 correspond to the fourth process (unload / load switching process) in the operation number control step.

  In the air compressor operation number control system of the present embodiment, the header pressure measurement value Ppv is obtained from the existing pressure transmitter 3, and the power measurement values Epv1 to Epvn of the air compressors 1-1 to 1-n are It can be obtained from watt meters 4-1 to 4-n that are cheaper and have better workability than a flow meter. Thus, in the air compressor operation number control system of the present embodiment, the existing pressure transmitter 3 and the inexpensive and good workability watt meters 4-1 to 4-n are used without using a flow meter. Since the number of operating air compressors 1 can be controlled, the workability can be improved and the initial cost can be reduced.

  FIG. 9 shows a functional block diagram of the main part of the control device 5 in this air compressor operation number control system. The control storage 5 includes the differential pressure transmitter 3 that measures the header pressure and the wattmeters 4-1 to 4-n that measure the power values of the air compressors 1-1 to 1-n as its constituent elements, and the stop load switching. 5A, an unload stop switching unit 5B, a load / unload switching unit 5C, and an unload / load switching unit 5D.

  In the stop load switching unit 5A, the state in which the header pressure measurement value Ppv is lower than the step-up pressure lower limit PL is continued for a predetermined time (for example, 60 seconds) or more and the air compressors 1-1 to 1-n When the capacity margin of all the air compressors 1 in the loaded state becomes 0% or less, one of the air compressors 1 in the stopped state is set to the loaded state.

The unload stop switching unit 5B is used when the unload state of the air compressor 1 switched from the load state to the unload state continues for a predetermined time (for example, 5 minutes) or more, or the air compressors 1-1 to 1-1. -When the capacity surplus of all air compressors 1 in the loaded state exceeds 15% continues for a predetermined time (for example, 5 minutes) or more, the air compressors 1 in the unloaded state On condition that the current number exceeds the minimum operating number N _MIN , one of the air compressors 1 in the unloaded state is brought into a stopped state.

  In the load / unload switching unit 5C, when the upward trend of the header pressure measurement value Ppv continues for a predetermined time (for example, 20 minutes) or longer, or the header pressure measurement value Ppv becomes equal to or greater than the unload switching pressure value PH. In this case, one of the air compressors 1 in the loaded state is switched to the unloaded state.

  The unload load switching unit 5D is one unit of the air compressor 1 in the unload state when the measured value Ppv of the header pressure is not more than the load switching pressure value PLA for a predetermined time (for example, 1 minute) or longer. To the loading state.

  In the above-described embodiment, the pressure in the header 2 is measured as the pressure value Ppv of the compressed air to the load. However, as shown in FIG. A transmitter 3 is provided, for example, measuring the end pressure of any one system as the pressure value Ppv of the compressed air to the load, or measuring the minimum value of the end pressure as the pressure value Ppv of the compressed air to the load, For example, the terminal pressure of at least one system may be measured as the pressure value Ppv of the compressed air to the load, such as measuring the average value of the terminal pressure as the pressure value Ppv of the compressed air to the load.

  In addition, as shown in FIG. 11, when the tank 6 is provided between the air compressors 1-1 to 1-n and the header 2, the pressure transmitter is applied to the tank 6 instead of the header 2. 3, the pressure in the tank 6 may be measured as the pressure value Ppv of the compressed air to the load. In this case, the tank 6 or a combination of the tank 6 and the header 3 corresponds to the air tank referred to in the present invention.

  In the above-described embodiment, the power values Epv1 to Epvn of the air compressors 1-1 to 1-n are measured using the wattmeters 4-1 to 4-n. You may make it measure the value of the electric current currently supplied to 1-1-n. That is, an ammeter may be used instead of the wattmeter. In this case, if the measured current is Ipv and the rated current unique to the device is Ics, the capacity margin η of the air compressor 1 can be obtained as η = (1−Ipv / Ics) × 100 [%].

Further, in the above-described embodiment, numerical values such as the step-up pressure lower limit value PL, the forced step-up pressure lower limit value P _LIM , the unload switching pressure value PH, the load switching pressure value PLA, and the minimum operating number N _MIN of the unloading machine. Is merely an example, and is not limited to these values. These values may be used as local adjustment items. Further, the minimum number N _MIN of _unloaders need not necessarily be provided.

  In the above-described embodiment, the wattmeters 4-1 to 4-n provided in the air compressors 1-1 to 1-n can be used to verify the effect before and after the introduction of unit control, You may make it perform energy management by a monthly report, an annual report, etc.

It is an instrumentation figure which shows an example of the air compressor operation number control system used for implementation of the air compressor operation number control method which concerns on this invention. It is a figure which shows the outline of the internal structure of the air compressor operation number control apparatus in this air compressor operation number control system. Zodan pressure lower limit PL used in the air compressor operation unit count control device, forced up stage the pressure lower limit value P _LIM, unload switching pressure value PH, is a diagram showing the relationship between the load switching pressure value PLA. It is an image figure of the increase / decrease stage logic which CPU in this air compressor operation number control apparatus performs. It is a flowchart for demonstrating the processing operation at the time of the stop-> load operation switching which CPU performs in this air compressor operation number control apparatus. It is a flowchart for demonstrating the processing operation at the time of switching the load operation-> unload operation which CPU performs in this air compressor operation number control apparatus. It is a flowchart for demonstrating the processing operation at the time of the unload operation-> load operation switching which CPU performs in this air compressor operation number control apparatus. It is a flowchart for demonstrating the processing operation | movement at the time of unload operation-> stop switching which CPU performs in this air compressor operation number control apparatus. It is a functional block diagram of the principal part of this air compressor operation number control apparatus. It is an instrumentation diagram showing an example of an air compressor operation number control system in which at least one system end pressure is measured as a pressure value Ppv of compressed air to a load. It is an instrumentation figure which shows the example applied to the air compressor operation number control system in which the tank is provided between the air compressor group and the header.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 (1-1 to 1-n) ... Air compressor, 2 ... Header, 3 ... Pressure transmitter, 4 (4-1 to 4-n) ... Wattmeter, 5 ... Air compressor operation number control device, 5 -1 ... CPU, 5-2 ... ROM, 5-3 ... RAM, 5-4 to 5-6 ... interface, 5A ... stop load switching unit, 5B ... unload stop switching unit, 5C ... load unload switching unit, 5D: Unload load switching unit, 6: Tank.

Claims (14)

A plurality of air compressors for generating compressed air; and an air tank for storing the compressed air sent from these air compressors, and the air compressor based on the state of the compressed air sent from the air tank to a load In the air compressor operation number control method for controlling the operation number of
A pressure measuring step for measuring the pressure of the compressed air to the load delivered from the air tank;
A power measurement step for measuring current power consumption for each of the air compressors;
A capacity margin calculating step for calculating a margin of the capacity from the measured power consumption for each of the air compressors;
An operating number control step for controlling the number of operating air compressors based on a measured value of the pressure of the compressed air and a capacity margin of the air compressor, . In the air compressor operation number control method according to claim 1,
The operation number control step includes
A load state in which the measured value of the compressed air pressure is lower than a preset first pressure threshold value for a predetermined time or more, and the compressed air is sent out of the capacity of each air compressor. An air compressor characterized in that one of the air compressors in a stopped state is put into a load state when the capacity margin of all the air compressors in the engine is less than a preset minimum capacity margin value. Operation unit control method. In the air compressor operation number control method according to claim 1,
The operation number control step includes
The air compressor that was in a load state that is sending out compressed air is switched to an unload state that is in operation but not sending out compressed air, and the unload state continues for a predetermined time or more, or When the capacity margin of all the air compressors in the loaded state out of the capacity margin for each air compressor exceeds the preset capacity margin threshold for more than a predetermined time, the unload state is entered. A method of controlling the number of operating air compressors, wherein one of the air compressors is stopped. In the air compressor operation number control method according to claim 1,
The operation number control step includes
A load state in which the measured value of the compressed air pressure is lower than a preset first pressure threshold value for a predetermined time or more, and the compressed air is sent out of the capacity of each air compressor. When the capacity margin of all the air compressors in is less than the preset minimum capacity margin value, set one of the air compressors in the stopped state to the load state,
The air compressor that was in a load state that is sending out compressed air is switched to an unload state that is in operation but not sending out compressed air, and the unload state continues for a predetermined time or more, or When the capacity margin of all the air compressors in the loaded state out of the capacity margin for each air compressor exceeds the preset capacity margin threshold for more than a predetermined time, the unload state is entered. A method of controlling the number of operating air compressors, wherein one of the air compressors is stopped. In the air compressor operation number control method described in any one of Claims 2-4,
The operation number control step includes
When the upward trend of the measured value of the compressed air continues for a predetermined time or more, or the measured value of the compressed air pressure is greater than or equal to a second pressure threshold greater than the preset first pressure threshold When this happens, one of the air compressors in a loaded state is switched to an unloaded state. In the air compressor operation number control method described in any one of Claims 2-4,
The operation number control step includes
When the measured value of the pressure of the compressed air is greater than the first pressure threshold that is set in advance and less than the third pressure threshold that is less than the second pressure threshold continues for a predetermined time or longer. A method for controlling the number of operating air compressors, wherein one of the air compressors in a loaded state is switched to a loaded state. In the air compressor operation number control method according to claim 3 or 4,
The operation number control step includes
When the unloaded state of the air compressor switched from the loaded state to the unloaded state continues for a predetermined time or more, or the capacity of all the air compressors in the loaded state out of the capacity margin for each air compressor The current number of uncompressed air compressors exceeds the predetermined minimum operating number when the margin exceeds the preset capacity margin threshold for a predetermined time or longer. A method for controlling the number of operating air compressors, characterized in that one of the air compressors in the unloaded state is stopped. A plurality of air compressors for generating compressed air; and an air tank for storing the compressed air sent from these air compressors, and the air compressor based on the state of the compressed air sent from the air tank to a load In the air compressor operation number control device that controls the operation number of
Pressure measuring means for measuring the pressure of the compressed air to the load delivered from the air tank;
Power measuring means for measuring current power consumption for each of the air compressors;
Capacity margin calculating means for calculating the capacity margin from the measured power consumption for each of the air compressors;
An operating number control unit for controlling the number of operating air compressors based on a measured value of the pressure of the compressed air and a capacity margin of the air compressor, . In the air compressor operation number control device according to claim 8,
The operation number control means is
A load state in which the measured value of the compressed air pressure is lower than a preset first pressure threshold value for a predetermined time or more, and the compressed air is sent out of the capacity of each air compressor. An air compressor characterized in that one of the air compressors in a stopped state is put into a load state when the capacity margin of all the air compressors in the engine is less than a preset minimum capacity margin value. Operation number control device. In the air compressor operation number control device according to claim 8,
The operation number control means is
The air compressor that was in a load state that is sending out compressed air is switched to an unload state that is in operation but not sending out compressed air, and the unload state continues for a predetermined time or more, or When the capacity margin of all the air compressors in the loaded state out of the capacity margin for each air compressor exceeds the preset capacity margin threshold for more than a predetermined time, the unload state is entered. A control apparatus for controlling the number of operating air compressors, wherein one of the air compressors is stopped. In the air compressor operation number control device according to claim 8,
The operation number control means is
A load state in which the measured value of the compressed air pressure is lower than a preset first pressure threshold value for a predetermined time or more, and the compressed air is sent out of the capacity of each air compressor. When the capacity margin of all the air compressors in is less than the preset minimum capacity margin value, set one of the air compressors in the stopped state to the load state,
The air compressor that was in a load state that is sending out compressed air is switched to an unload state that is in operation but not sending out compressed air, and the unload state continues for a predetermined time or more, or When the capacity margin of all the air compressors in the loaded state out of the capacity margin for each air compressor exceeds the preset capacity margin threshold for more than a predetermined time, the unload state is entered. A control apparatus for controlling the number of operating air compressors, wherein one of the air compressors is stopped. In the air compressor operation number control device according to any one of claims 9 to 11,
The operation number control means is
When the upward trend of the measured value of the compressed air continues for a predetermined time or more, or the measured value of the compressed air pressure is greater than or equal to a second pressure threshold greater than the preset first pressure threshold When this happens, one of the air compressors in the loaded state is switched to the unloaded state. In the air compressor operation number control device according to any one of claims 9 to 11,
The operation number control means is
When the measured value of the pressure of the compressed air is greater than the first pressure threshold that is set in advance and less than the third pressure threshold that is less than the second pressure threshold continues for a predetermined time or longer. A device for controlling the number of operating air compressors, wherein one of the air compressors in a loaded state is switched to a loaded state. In the air compressor operation number control device according to claim 10 or 11,
The operation number control means is
When the unloaded state of the air compressor switched from the loaded state to the unloaded state continues for a predetermined time or more, or the capacity of all the air compressors in the loaded state out of the capacity margin for each air compressor The current number of uncompressed air compressors exceeds the predetermined minimum operating number when the margin exceeds the preset capacity margin threshold for a predetermined time or longer. A unit for controlling the number of operating air compressors, wherein one of the air compressors in the unloaded state is stopped.

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