JP2008534842A - Complex compressor control system - Google Patents

Abstract

At least one of the plurality of compressors (C1-C7) connected to the fluid distribution system is loaded and / or unloaded based on the capacity of the fluid distribution system.
[Selection] Figure 2

Description

  The present invention relates to compression, distribution, and compressible fluid control that efficiently optimizes demand and supply without affecting the integrity of the associated process.

  Pressurized compressed fluids such as air, carbon dioxide, helium, argon, nitrogen, freons, liquids, etc. are commonly used to provide energy in the form of pressure in various industrial applications. Devices using pressurized fluids known as load devices include robots, coloring jobs, turbines, generators, jet engines, air tools, cold rooms, air conditioners and others. The compressed fluid is usually pressurized by a compressor, and there are various forms such as a centrifugal compressor, a reciprocating compressor, a rotating screw, a rotor and stator stack, and other forms.

  The compressor takes in compressible fluid from the inlet, compresses the volume of the compressible fluid to a small amount and high pressure, and discharges the compressed fluid from the outlet. Individual compressors supply compressed fluid at a flow rate specified by the amount of free fluid per hour at the compressor inlet. The individual compressors also provide a discharge pressure selected from the outlet as normal operation of the compressor. This selected discharge pressure generally varies below the maximum discharge pressure specified for the compressor.

  The specified flow rate and selected discharge pressure are selected to suit the specific application for which this compressor is intended. For example, some typical compressors applied to chemical manufacturing and packaging factories have a discharge pressure in the normal range of 90 to 125 pounds per square inch (PSIG) and a flow rate of 2,000 to 2,000 per minute at standard conditions. 4,000 cubic feet (SCFM) is selected. SCFM is defined as “cubic feet per minute at 60 degrees Fahrenheit under the standard conditions of 14.7 pounds per square inch (psiA)”. Many other discharge pressures and flow rates are possible as needed for a particular application.

  Each load device has a required flow rate, which is the fluid velocity used by the load device in its operation. Each load device also has a specification of the suction pressure required for normal operation. The required flow rate may be quite constant or often changed depending on the application. In any load device, the required flow rate drops at least temporarily due to failure of maintenance or failure.

  In facilities where many load devices operate, it is common to supply the load device with the required pressurized fluid in a single fluid distribution system with the load device connected to the downstream outlet. This single fluid distribution system can conversely connect various numbers of compressors that supply pressurized fluid to the distribution system from the upstream inlet of the system. This single distribution system is more flexible than if each load device is connected to its own compressor because it can average the change in demand flow rate.

  However, the required flow rate collected by the load device still varies during operation. This amount of variation depends on the type of equipment using the load device and the operational properties. If too few compressors are operating, the flow limit from the compressor will be exceeded if the required flow rate is increased particularly high. As a result, the distribution pressure decreases, and the normal operation of the load device stops.

  To avoid this type of interruption, a complex compressor system is usually designed and assembled to provide the maximum peak demand flow rate of the required load pressure. Facility operators often operate the maximum installed capacity of all compressors at the maximum pressure so that sufficient pressure is obtained even at the maximum required flow rate of the load device. That is, the fluid discharge capacity of the installed compressor is greater than what is normally required, and these compressors are set higher than the discharge pressure required in most load devices. The extra compressor capacity and discharge pressure both lead to high energy consumption, maintenance costs and capital costs.

  However, good operation of the load device usually has a much higher priority than efficient operation of the compressor. Conventional composite compressor systems thus avoid pressure shortages during peak demand flow periods at the expense of compressor system efficiency.

  FIG. 1 is a schematic diagram showing an example of a composite compressor system 100 according to the prior art. In the example shown in FIG. 1, the composite compressor system 100 is a chemical manufacturing facility and the fluid to be compressed is air. This facility uses the energy of compressed air for circulation valves, cleaning dust bag rooms, equipment, packaging equipment, conveyors, robots, crushing operations, pneumatic tools, etc.

  The combined compressor system 100 comprises a plurality of individual compressors C1-C7, each of which is connected to the main fluid distribution header 102 via a drying and filtering device D1-D7. The compressors C1-C7 can be located in one or more areas of the facility. The compressors C1-C7 take in the atmosphere from the respective intake ports, compress the air to a high pressure, and discharge the compressed air from the respective discharge ports. The energy that increases the pressure of the fluid is supplied from one or more motive forces, which drive the shaft of each compressor. Each compressor has a specified flow rate and a specified maximum discharge pressure. The discharge pressures of the compressors C1-C7 can be adjusted within a range that is usually less than the maximum discharge pressure of the specification. FIG. 1 shows an example of setting the discharge pressure of the compressors C1-C7. For example, the compressor C5 compresses fluid air to a discharge pressure of 115 gauge psi (pounds per square inch gage: PSIG). Gauge pressure is the amount by which the total absolute pressure exceeds the ambient pressure. All compressors are set to be regulated in the upper region so as not to blow down.

  The discharge ports of the compressors C1-C7 are connected to the drying / filter devices D1-D7, respectively. Drying / filtering devices D1-D7 remove moisture, dust and other contaminants from the compressed air and supply clean, dry air to the main distribution header 102.

  The main distribution header 102 is interconnected by welding or other suitable securing means with or without a functional or non-functional isolation valve. For example, the main distribution header 102 may comprise a combination of pipes having a diameter of 1 inch to 4 inches.

  Load devices such as L1 and L2 may be coupled to outlets along the main distribution header 102. As described above, the load devices L1 and L2 are a circulation valve, a cleaning dust bag chamber, equipment, a packaging facility, a conveyor, a robot, a crushing operation, a pneumatic tool, and the like. Each of the load devices L1 and L2 has a required flow rate, which is a flow rate of a flow rate (gas in this embodiment) used during operation of the load device. The load devices L1, L2 usually have a desirable input pressure that is further required for normal operation. In the example shown in FIG. 1, the load devices L1 and L2 require a pressure of at least 90 gauge psi.

  The total required flow rate of the main distribution header 102 may be approximately constant or often vary depending on the needs of the system 100. For this reason, the conventional composite compressor system as shown in FIG. 1 is designed and assembled to meet the required maximum required flow rate. If the compressors C1-C7 do not operate sufficiently when the demands of the load devices L1, L2 increase, the outflow from this system will be greater than the inflow, and the density of air in the system and thus the atmospheric pressure will be low. If the pressure drops, production at this facility will be hindered. Excessive pressure drop in the system is also caused by, for example, downsizing of cleaning equipment and piping, accumulation of dirt in the system, and the like.

  In order to prevent pressure drops during periods of varying demand, the facility operator operates the combined compressor system to always supply all compressors of the system at the set maximum flow rate and maximum discharge pressure. In this type of operation, the average required flow rate is always lower than the set discharge flow rate. For this reason, the compressors C1-C7 are forced to operate on "partial load". Partial load is defined as the required flow rate (SCFM) divided by the discharge flow rate (SCFM). A compressor is said to be in partial load if it can supply a flow rate higher than the required flow rate at a selected discharge pressure.

  Partial loading reduces the efficiency of the system 100. This efficiency is defined as “average compressed CFCM / average consumed kW”, where SCFM is the cubic foot per minute of each compressor inlet, and kW is the energy consumed by the compressor power source in kilowatts. It is a representation. The total efficiency of the system is “averaged compressed air total SCFM / total average consumed kW” in system 100.

  As a general rule, every time the discharge pressure increases by 2 PSIG in various positive displacement compressors, the energy consumption increases by 1%. Similarly, energy consumption is reduced by 1% for every PSPS reduced by 2 positive displacement compressors. Thus, a compressor driven 10 PSIG above the required pressure consumes about 5% more energy than needed.

  Table 1 is a list of possible characteristics of compressors C1-C7 where system 100 uses air for 8,400 hours a year and the main distribution header maintains about 90 PSIG. These characteristics are: compressor type, model, manufacturer, designed maximum discharge pressure, flow rate (SCFM), energy rate consumed by motive power (kW), maximum efficiency (SCFM / kW), and SCFM · kW · Includes an estimate of SCFM / kW.

Table 1

  As shown in Table 1, all compressors are operating on partial load, which is below maximum efficiency. The compressor C4 is shown in standby mode. One of the main causes of resistivity is that the supply rate is greater than the required rate.

  Table 2 summarizes the system efficiency of the composite compressor system 100 shown in FIG.

Table 2

  The compressor of system 100 averages 51.5% partial load at flow rate, with a total average efficiency of only 3.01 SCFM / kW.

  FIG. 2 is a schematic diagram of a composite compressor control system 300 according to one embodiment. System 300 typically includes a plurality of compressors C1-C7, each of a plurality of drying and filtering devices D1-D7, a main distribution header 302, and one or more load devices L1, L2.

  The compressors C1-C7 are selectively connected to the main distribution header 302 via the drying / filter devices D1-D7, respectively. The compressors C1-C7 are located in one or more areas of the facility, and various numbers of compressors can be used. The compressors C1-C7 may be a combination of various compressor types, manufacturers, and models. For example, the compressors C1 to C7 may be reciprocating, rotary screw, centrifugal, or scroll vane compressors. Each compressor has a specified flow rate and a specified maximum discharge pressure. The discharge pressure of the compressors C1 to C7 can be adjusted within a predetermined range that is less than or equal to the maximum discharge pressure of the specification. In an alternative embodiment, one or more compressors C1-C7 are fixed discharge pressures, which are selected for the particular application in which the compressor is used. The driving force of the compressors C1 to C7 is driven by, for example, electricity, fossil fuel or other fuel, steam or the like.

The outlets of the compressors C1-C7 are connected to the drying / filter devices D1-D7, respectively. Drying / filtering devices D1-D7 remove moisture, dust and other contaminants from the compressed air and supply clean, dry air to the main distribution header 102. In alternative embodiments, one or more devices D1-D7 may be located elsewhere in system 300, such as at the outlet side of each compressor. Also, any one device D1-D7 may be used for drying / filtering air from more than one compressor.

  The main distribution header 302 may comprise one or a series of pipes or other functionally similar channels that carry pressurized fluid to one or more outlets, for example to the load devices L1, L2. The flow paths are interconnected by welding or other suitable fastening means with or without functional or non-functional isolation valves. In one embodiment, main distribution header 302 may comprise a combination of pipes having a diameter of 1 inch to 12 inches. Other size pipes may be used.

  The load devices L1 and L2 are a circulation valve, a cleaning dust collection bag chamber, equipment, a packaging facility, a conveyor, a robot, a crushing operation, a pneumatic tool, and the like. Each of the load devices L1 and L2 has a demand flow rate (demand flow rate), which is a flow rate of a flow rate (gas in this embodiment) used during operation by the load device. The load devices L1, L2 usually have a desirable input pressure that is further required for normal operation.

  In the example shown in FIG. 2, a minimum pressure of 90 gauge psi is required in the main distribution header 302 for normal operation of the load devices L1 and L2. The compressors C1-C7 are connected to the main distribution header 302. A compressed air tank 303 that is an assembly standard unit is connected to the main distribution header 302. A correctly calibrated temperature transmission device 304 and pressure transmission device 305 are connected to the transmission header 302, preferably to the tank 303 portion.

  As will be described in detail below, an electronic control unit 306 is connected to the new compressor system 300, and is connected to the compressors C1 to C7 and the temperature / pressure transmission units 304 and 305 via control cables. In another embodiment, the control unit 306 may be connected to the compressors C1 to C7 and another means such as an optical cable such as a local area network or wireless.

  The electronic control unit 306 is designed to control various numbers of compressors as long as they are connected to the compressed air system 300 of this embodiment. The electronic control unit 306 is configured to control the control system 300 by a closed loop control method or an open loop control method. One or more sensors (not shown) may be distributed to the system 300 at desired locations to provide the electronic controller 306 with appropriate measurements from various ones in the system. For example, these sensors are pressure sensors, temperature sensors, and flow sensors.

  The electronic controller 306 includes a processing unit configured to purify the control signal toward one or more compressors C1-C7. In one embodiment, such control signals are generated based on the capacity of the fluid distribution system. For the purposes of this disclosure, the term “processing unit” refers to a conventionally known or future developed processing unit that executes a sequence of instructions stored in memory. Execution of this instruction sequence causes the processing unit to generate a control signal. The instructions are stored in a medium 307 including, for example, random access memory (RAM) readable by a computer or processor, and executed from a read only memory (ROM), mass memory, or other non-volatile memory to the processing unit. . In one embodiment, the memory 307 is removable and portable to the control unit 306. In another embodiment, a wiring circuit may be used instead, or the above functions may be implemented in combination with software instructions. The control unit 306 is not limited to a combination of a specific hardware circuit and software, and is not limited to a specific instruction source executed by the processing unit.

  The electronic control unit 306 may include various control devices such as a programmable logic controller (PLC), a microprocessor type controller, or a personal computer type controller. The electronic controller 306 may be a digital or analog control unit. In alternative embodiments, the electronic controller 306 may be replaced with a plurality of individual controllers, each controller controlling one or more elements in the system 300. Further, the electronic control unit 306 may be a manual control unit, a different electronic control unit, or a combination thereof.

  The tank size is similar to the prior art, with changes in the air demand at the SCFM during the period, the startup required for the compressors C1 to C7 (T1, T2, etc.), the set pressure (Ps for PSIG), plant operation Depends on the permissible amplitude (for example, plus or minus 3 PSIG). The tank 303 is designed to have a capacity of 6,000 gallons (780 CF), but a tank having a different capacity may be used. The total capacity of the distribution header pipe, including the amount of filters and cleaning equipment, is measured as 40 CF (same as the system of FIG. 2), so the total capacity of this system 300 is 820 CF.

  One factor that affects the control algorithm is a useful reservoir or storage capacity (C). Storage capacity is defined as the standard cubic foot value of free air (standard state atmosphere) in the air system, which changes the pressure in the system by 1 PSI (plus or minus). This is calculated by the equation P1V1 = P2V2, where P1 and V1 are the pressure and volume of period 1, and P2 and V2 are the pressure and volume of period 2. The capacity of various systems can approximate C = V / Pa, where C is the system capacity in standard cubic feet (SCF) / PSIA, and V is the capacity of the entire system in cubic feet (CF). , Pa is the atmospheric pressure around the standard state and is 14.7 PSIA.

  In the example shown in FIG. 2, the system 300 needs to supply a compressed air with an average flow rate of 2,990 SCFM to the main distribution header 302 at a minimum of 90 PSIG. Table 4 shows specs for the compressors C1-C7 in this example.

  The minimum compressors C1, C2, and C4 are selected and operated at each given compressor fluid capacity and efficiency. C1 and C2 are operated at full load (the intake valve is fully open) by the electronic control unit and supplies 2,400 SCFM to the distribution header. The remaining 590 DFM is supplied from C4 (90% of the cycle time is full load and 10% of the period is completely unloaded). These compressors are set to supply a minimum discharge pressure that practically allows normal operation of the load device. The minimum required pressure in the main header 302 of this plant is 90 PSIG.

  Electronic controller 306 is therefore programmed to maintain a minimum header pressure of 90 PSIG in distribution header 302. In this example, the plant header pressure is always detected by the pressure converter 307 subsequent to the drying / cleaning devices D1 to D7, so that the pressure loss in the drying / cleaning device is the load efficiency, the load of the compressors C1 to C7, the start / Does not affect the outage.

  In the example shown in Table 3, the discharge capacity of the compressor C1 is 1,500 SCFM, and the discharge capacity of the compressor C2 is 900 SCFM. The system 300 therefore requests the remaining 590 SCFM with a minimum of 90 PSIG, which is supplied from the compressor C3 with a capacity of 650 SCFM.

Table 3

  Looking at Table 3, compressors C1 and C2 are operating at maximum flow rate and C4 is operating very close to full load capacity, but these compressors are more SCFM / kW efficient than the same compressor of the conventional system shown in Table 1. Is expensive.

  Table 4 summarizes the overall efficiency of the system 300 when compared to the efficiency of the system 100 shown in Table 3.

Table 4

  When actually implemented, the system operation configurations defined in Tables 3 and 4 are the same.

  With the control possible with the prior art, the same situation of operating an optimal number of compressors is not reliable and cannot be realized without contradiction. Since it is not the control which loads or unloads the compressor in consideration of the system capacity, this reliability and consistency are not completely obtained in the prior art. The plant operator feels reliable and secure that the system is consistent and reliable. If the plant operator is not confident and reassured, he usually ignores the controls and energy saving or efficient projects fail.

  The control algorithm of the controller 306 eliminates the steam-like situation and automatically calculates and selects the lead time on a dynamic basis whenever system parameters change.

  This control algorithm is needed to load on-line with possible capacity, changing demands, regularly changing sample times and corresponding recovery and lead times, minimum allowable pressure and tolerance, possible capacity for each compressor Developed based on minimum time. Also, the need for flow control and tedious construction effort in the system 300 is avoided without compromising system pressure requirements. This greatly reduces the construction cost.

  According to one embodiment, all compressors running in system 300 are fully loaded except for one compressor that performs floating adjustments. Considering the same example as above, the required flow rate of 2,990 SCFM of system 300 was C1 and C2 at full load and C3 loaded at 90 PSIG and unloaded at 96 PSIG (93 PSIG had an allowable range of plus or minus 3 PSIG. Supplied by three compressors (pressure setting). Except for 650 SCFM compressed by C3, it is consumed by load devices L1 and L2, and the remaining 60 SCFM raises the header 302 pressure from 90 to 96 PSIG. The system capacity is 820CF / 14.7 PSI = 55.7 SCF / PSI. If the system demand rises to 360 SCFM, if the system pressure is 91 PSIG and the compressor C3 is unloaded, the electronic controller 306 waits for the lead time required to load C3, in this case about 1 second. Immediately load running compressor # 3. The total required air is 3,350 SCFM and the total supply capacity of all compressors is only 3,050 SCFM, which will be less than 300 SCFM or 5 CF / sec. The pressure in the system continues to drop. The control algorithm of the present embodiment calculates a recovery period and a response time (instead of 5 seconds set in the prior art) corresponding to the sampling period before operating and loading the compressor C7 having a capacity of 450 SCFM. The capacity of the system 300 is 55.7 SCF / PSI. The shortage is 5 CF / sec, the current system pressure is 91 PSIG, and the pressure setting lower limit is 90 PSIG. The control unit 306 sets the maximum response period corresponding to the sampling period ((91− 90) * 55.7CF / PSI) / (5CF / c) = 11.14. The control unit determines that the shortage is 5 CF / sec, and searches for a compressor having a capacity close to 5 CF / sec from the compressors that are immediately available. This control unit selects C7 having a capacity of 7.5 SCF / sec that is closest to 5 SCF / sec which is insufficient from Table 3 (from Table 3). After selecting C7, the determined sampling period and maximum response period are compared and matched to the response time required for C7. If the C7 response period is shorter than the maximum response period determined by 306, the controller sends a signal to start and load C7 and the appropriate time. For example, if the start and load response time is 5 seconds, the control unit 306 starts the compressor at the 6th second of 11.14 seconds possible. Then, the supply capacity is 3,490 SCFM with respect to the required 3,350 SCFM. Too much 140 SCFM will increase the pressure of the system 300 from about 90.5 PSIG to 96 PSIG (set pressure 93 PSIG plus 3PSIG tolerated) in 131 seconds, unless the system demands increase further during this increase. Thus, the system does nothing for 131 seconds (as opposed to prior art controls) and waits for almost 113 seconds after unloading a compressor with a capacity close to excessive flow. In other words, the control unit unloads C7. Here again, the required 5 SCF / sec is insufficient, and the control unit determines that the sampling period is at least 66 seconds in the same manner as described above before loading C7 again. This cycle of compressors C1 and C2 and cycling (loading and unloading) of compressor C7 continues until the demand approaches 3,350.

  As a result, the combined compressor system 300 is stable and this situation conveys to the operator a sense of safety of system stability (as opposed to the previous example where three compressors load / unload in a short time).

  In this way, the control unit 306 can actually save about 462 kW of outstanding power consumption.

  In the above-described embodiment, the compressor C4 is a compressor that performs floating adjustment at the request of 2,990 SCFM, and the compressor C7 is a compressor that performs floating adjustment at the request of 3,350 SCFM. Similarly, the composite compressor controller keeps only one floating regulating compressor in varying demands, both up and down.

  FIG. 3 is a block diagram showing the control function of the electronic control unit 306 in more detail. In one embodiment, the electronic control unit 306 is a programmable logic controller (PLC) 400 that includes a program 401 and a database 402. Program 401 is created to perform desired function control of the composite compressor system based on data stored in database 402 and input parameters received from, for example, pressure sensor 307 and temperature sensor 308. The program 401 can be realized as software, hardware, or a combination thereof.

  The database 402 includes system specific data such as details of each element in the system. These specifications include maximum discharge pressure, selected discharge pressure, maximum discharge capacity and energy consumption rate for each compressor, consumption pressure for each drying / filter device, flow rate for each drying / filter device, overall system flow rate, system 300 Including “total capacity”.

  FIG. 4 is a flowchart illustrating the steps performed by the PLC 500 that controls the various elements of the composite compressor system 300 according to one embodiment.

  In step 500, data is provided from the database 402 (see FIG. 4) and various sensors in the system to the controller of the composite compressor. In step 501, the system is activated and initialized. The controller is activated and the desired compressor to activate and load is selected. Step 401 is executed at the beginning of each work day of the facility or less frequently if the facility is in operation 24 hours a day.

  In step 502, the composite compressor controller 306 uses the system data from 500 to determine at what point in time to start and load or unload and stop response periods based on the total amount of change, system capacity. calculate.

  This operation is based on inputs to the composite compressor controller 306 from sensors, converters, acquired time, internal memory storage, network host databases, and other input sources. The system pressure, the temperature, the set pressure, the tolerance, the capacity, the values of the starting characteristics of the compressors C1 to C7, the time for reaching the upper limit or the lower limit of the sampling time and the set pressure are shown.

In one embodiment, using the air density calculation method, the standard air density under arbitrarily selected conditions forms a standard value, which is modified so that the temperature and pressure are accurate in local conditions. The The air volume of the system 300 can therefore be calculated in the following form:
M _t = (D _s * V _t ) / [(Pa * (T + 460)) / ((Pa + P _t ) * (T _s +460))]
Where M _t is the amount of air in the system 302 (tank 303 and piping), D _s is the standard air density at standard temperature and pressure, V is the total capacity of the system, tank, filter, dryer , The capacity of the piping. T is the measured temperature of air in Fahrenheit, T _s is the standard temperature in Fahrenheit, Pa is the standard ambient pressure in psiA, and Ps is the system pressure in psiG. The value of 460 added to both temperature sets compensates for absolute zero being Fahrenheit and 460 degrees below zero. The details of this formula may vary in different embodiments, for example when the temperature is measured in Kelvin or Celsius, or with further corrections with well-known calculation methods such as overall pressure value, volume, density, etc. Is included. In an alternative embodiment, the overall rate of change is calculated for the tank only. In this embodiment, V is the tank capacity.

  The change in the total amount is determined by the customized program 502 for the current sampling period (t1), which changes dynamically with system changes, every period t1 seconds. For example, if t1 = 30 seconds and t2 = 1 second, the PLC calculates a total percentage of 6 samples at 1 second intervals over a 30 second period.

  If the rate of system change indicates a downward slope as shown in step 503 of FIG. 4, it is determined in steps 504, 505, and 506 whether the downward slope is negative, positive, or the same. If determined to be 504, no action is required to start and load the compressor, so the loop is complete and returns to 402. If determined to be 505, it is determined in step 506 that the downward slope is due to the floating adjustment compressor, and in step 507 no action is taken to start and load another compressor, and the loop returns to 502. If step 506 is determined, the rate of change is not the same as the downtrend of the floating adjustment compressor and step 508 proceeds to step 509. The step examines the rate of change of the quantity and decides to load the unloaded floating compressor (if it is in the unload cycle), so that based on the capacity and possible quantity, the load time characteristics of the floating compressor, Load the floating compressor at the appropriate time. If the rate of change of the quantity is still falling, the process proceeds to step 505 where the quantity comparison is insufficient and the available sampling and response periods and measurements of the available compressor are made at step 502. In this case, step 510 determines that the rate of change is upper and compares it to the floating regulator, and unloads the floating regulator when the system pressure reaches its upper tolerance.

  This process continues and operation cycles such as sampling period and response period are repeated to control the system pressure to be within acceptable levels while maintaining only one compressor as a floating adjustment.

  If the rate of change slope is upward as determined in step 511, the slope is compared to the floating compressor load cycle in step 512 and if the calculated slope is the same, the operation of unloading the floating compressor Do not do. If the upward slope is not the same and it is time to unload any compressor during the current sampling period, unload the floating adjustment compressor. In step 515, the motive power (motor or generator) is stopped after waiting for a selection stop delay time of the floating compressor. If one particular floating compressor is unloaded, the composite compressor controller will select one of the remaining working compressors as the floating compressor to maintain system stability, and the frequency of more than one compressor Avoid heavy load / unload cycles.

  These steps are dynamic because the system airflow changes. The specific steps for maintaining the pressure in the main distribution header performed by the composite compressor are provided merely as examples. Various modifications can be made in alternative embodiments of the invention. Furthermore, the value of the rate of change can be calculated by various methods. For example, the composite compressor may calculate the rate of change by volume or pressure.

  In summary, the composite compressor control system of the present invention is economically feasible and less expensive to solve the operational system efficiency improvement problem indicated by “total average compression SCFM / total average consumption kW”. Solution. This leads to a reduction in system energy consumption, cost of components used in the system, maintenance fees, and other secondary costs. The system also provides a stable pressure within a narrow tolerance of the desired pressure in the plant header. Pressure stabilization reduces product bursting and improves productivity.

  Although the present invention has been described with reference to preferred embodiments, workers skilled in the art can make changes in form and detail without departing from the spirit and scope of the invention.

FIG. 1 is a schematic diagram of a composite compressor system of Prior Art 1. FIG. 2 is a schematic diagram of a composite compressor control system including an electronic control unit according to an embodiment of the present invention. FIG. 3 is a block diagram of an embodiment of the control unit of FIG. 1 according to one embodiment. FIG. 4 is a flowchart of a routine example applied to the electronic control unit of FIG. 3 for controlling the composite compressor system shown in FIG. 2 according to one embodiment of the present invention.

Claims (20)

  A configured controller (306) configured to selectively perform at least one load or unload of the plurality of compressors (C1-C7) of the fluid distribution system based on the capacity of the fluid distribution system; A device characterized by comprising.   The apparatus of claim 1, wherein the controller (306) selectively performs either loading or unloading based on a mass rate change of the fluid distribution system.   3. The apparatus according to claim 2, wherein the control unit (306) performs either loading or unloading based on a lead time of at least one load or unload of the plurality of compressors (C1-C7). An apparatus configured to selectively execute.   The apparatus of claim 1, wherein the controller (306) is configured to selectively load at least one of the plurality of compressors (C1-C7) based on a capacity of the fluid distribution system. Features device.   The apparatus of claim 4, wherein the controller (306) is configured to selectively load at least one of the plurality of compressors (C1-C7) based on a minimum pressure of the fluid distribution system. A device characterized by.   The apparatus of claim 4, wherein the controller (306) is configured to selectively unload at least one of the plurality of compressors (C1-C7) based on a capacity of the fluid distribution system. A device characterized by.   The apparatus of claim 6, wherein the controller (306) is configured to selectively load or unload at least one of the plurality of compressors (C1-C7) based on tolerances of the fluid distribution system. A device characterized by that.   The apparatus of claim 1, wherein the controller (306) is configured to selectively unload at least one of the plurality of compressors (C1-C7) based on a capacity of the fluid distribution system. A device characterized by.   2. The apparatus according to claim 1, wherein the control unit (306) is based on the capacities of the plurality of compressors (C 1 -C 7), and includes one or more compressors (C 1 -C 7). An apparatus configured to select loading or unloading of C7).   The apparatus of claim 1, wherein the controller (306) is configured to adjust a sampling period for sampling a change in the fluid distribution system based on a capacity of the fluid distribution system. Device to do. The apparatus of claim 1, further comprising:
A fluid distribution system;
A plurality of compressors (C1-C7), wherein at least one of the plurality of compressors (C1-C7) is selectively aerodynamically coupled with the fluid distribution system in response to a control signal of the controller (306). A device characterized in that it is configured to be connected and disconnected from each other. A processor readable medium that:
Instructions are stored that selectively execute at least one of loading and unloading of a plurality of compressors (C1-C7) connected to the fluid distribution system based on the capacity of the fluid distribution system. Feature media.   13. The processor readable medium of claim 12, further comprising: determining a rate of change of floating amount of fluid in the fluid distribution system; and a plurality of compressors connected to the fluid distribution system according to the rate of change of floating amount. A medium in which an instruction to selectively execute at least one of loading and unloading of C1-C7) is stored.   12. The processor readable medium of claim 11, wherein the stored instruction to selectively perform either loading or unloading is to start and load any one of the plurality of compressors (C1-C7). A medium characterized by being based on lead time.   12. The processor readable medium of claim 11, further selecting any one of at least one load and unload of the plurality of compressors (C1-C7) based additionally on an allowable pressure range of the fluid distribution system. A medium in which instructions to be executed are stored.   A method comprising selectively performing at least one load or unload of a plurality of compressors (C1-C7) of the fluid distribution system based on the capacity of the fluid distribution system.   17. The method of claim 16, wherein at least one load or unload of the plurality of compressors (C1-C7) is based on a rate of change of fluid in the fluid distribution system.   17. The method of claim 16, wherein at least one load or unload of the plurality of compressors (C1-C7) is based on a lead time for starting and loading any one of the plurality of compressors (C1-C7). A method characterized by.   17. The method of claim 16, wherein the loading or unloading includes one or more selective loading and unloading of the plurality of compressors (C1-C7) based on an allowable pressure range of the fluid distribution system. And how to.   The method of claim 16, further comprising adjusting a sampling period based on a rate of change of fluid in the fluid distribution system.

Images