Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
  • F04C28/02—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids specially adapted for several pumps connected in series or in parallel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
  • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
  • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
  • F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
  • F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
  • F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
  • F04C28/08—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by varying the rotational speed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2270/00—Control; Monitoring or safety arrangements
  • F04C2270/56—Number of pump/machine units in operation

Definitions

• the present invention relates to a method for producing compressed gas as well as an installation for producing compressed gas for its implementation.
• the compressors are not always operated at their set operating points; Some of them sometimes operate partially when idle, especially when the air flow falls below the air production capacity of the fixed compressor. This results in unnecessary energy consumption, which consequently induces an increase in the ratio, energy consumption per cubic meter of gas produced (specific energy) and therefore an increase in the cost price of this cubic meter.
• the object of the present invention is to overcome the aforementioned drawbacks and to propose an installation for supplying compressed gas which is economical, in particular as regards energy consumption. Another object is a compressed gas supply installation which has a low maintenance cost.
• the subject of the invention is an installation for producing a compressed fluid, comprising: - n compressors, the discharge side of which is connected to a network of compressed fluid, n being greater than or equal at 2
• a first connection line with a switch allowing individually, the establishment or the interruption of the connection of the compressor directly to the energy source, - a speed variator, adapted to vary continuously the rotation speed of one of the compressors as a function of a speed setpoint, and intended to be connected to the energy source,
• a second connection line with a switch allowing individually, the establishment or the interruption of the connection of the compressor, via the variable speed drive, to the energy source, characterized in that she understands :
• - means forming a switch, suitable for selectively connecting one and only one of the compressors to the variable speed drive, and ensuring the transition phases between direct connection and connection via variator, and in that:
• said switch means are adapted so that one of the n compressors is connected to said variator
• the compressors used in the installation which is the subject of the present invention are preferably of the "all - or - nothing" type.
• all-or-nothing type compressor we mainly mean commercial compressors classified in this category and more particularly screw compressors.
• the invention particularly relates to an installation as defined above, in which the compressors are screw compressors whose rotational speed can be continuously adjusted in a first speed range located between a minimum speed and a speed of transition greater than the minimum speed.
• compressed fluid is meant a fluid whose total pressure is greater than one atmosphere and more particularly: air, oxygen (O 2 ), nitrogen (N 2 ), argon (Ar), carbon dioxide (C0 2 ), carbon monoxide (CO), helium (He), nitrous oxide (N 2 0), nitrogen monoxide (NO) , mixtures of nitrous oxide and oxygen, carbon dioxide and oxygen, nitrogen and carbon monoxide, helium and oxygen, such as, for example, the mixtures (50 % by volume (v / v) N 2 0 + 50% v / v O 2 ), (5% v / v C0 2 , 95% v / v O 2 ), (200 to 800 ppm NO in N 2 ), (78% He + 22% v / v 0 2 ), (65% He + 35% O 2 ) 80% v / v He + 20% v / v 0 2 ), mixtures of nitrogen and carbon dioxide or again refrigerant gases from cold stations or water
• the installation as defined above is an installation for producing compressed air.
• the installation as defined above comprises from two to six compressors.
• the installation as defined above comprises means suitable for starting the compressors one after the other via the speed controller and for stopping the compressor connected to the speed controller, when the speed reference of the compressor is situated in a speed range delimited by speed 0 and the minimum speed greater than 0, and adapted to operate this compressor with the speed reference when this speed reference is greater than the minimum speed.
• the installation as defined above comprises a gas pressure sensor adapted to measure the gas pressure prevailing in the compressed gas network, and control means adapted to control the switches and the switch means as a function of the gas pressure measured by the pressure sensor.
• control means very particularly comprise means for regulating the speed reference continuously according to a regulation law, in particular a proportional, integral, differential law (PID; in English Proportional, Intégral Differential), and / or they are very particularly connected to switching means of the means forming a switch, as well as to individual actuation means of each of the switches.
• a regulation law in particular a proportional, integral, differential law (PID; in English Proportional, Intégral Differential)
• PID proportional, integral, differential law
• control means comprise means for exclusive connection which are suitable for connecting a determined compressor to the variable speed drive only when the switch associated with this compressor is open and / or the control means particularly include selection means for selecting one of the compressors to be started or stopped, these selection means comprising a counter adapted to count the number of starts of each of the compressors, and means adapted to select as compressor to be started, the compressor which has the least operating time or as compressor to be stopped, the compressor with the longest operating time.
• control means comprise a programmable automaton characterized in that it comprises a central unit, a memory and possibly means allowing its remote control and that it is able to operate by means of a suitable program to regulate the variable speed drive in PID regulation mode.
• the compressors are connected in parallel by their discharge side, to a buffer reservoir of compressed fluid by means of a first connecting pipe, said buffer tank being connected to the compressed fluid network by a second connecting pipe provided with a cut-off valve.
• the first connecting pipe is preferably provided with a filter.
• the invention also relates to a method for producing a compressed fluid implementing the installation as defined above, characterized in that it comprises, over time, one or other of the following operating steps : - when the fluid pressure in the compressed fluid network downstream of said installation is within a value range between a high pressure threshold (hereinafter referred to as: PSH) and a low pressure threshold (designated below) -after by: PSL), the pressure of the fluid in said network is maintained within this value range by means of the compressor connected to the speed variator;
• PSH high pressure threshold
• PSL low pressure threshold
• either the compressor connected to the variable speed drive is stopped, and in this case, it is started at the minimum speed; be the compressor connected to the speed controller is operated at a speed greater than or equal to the minimum speed and less than the maximum speed, and in this case its speed is brought to the maximum speed, i.e. the compressor connected to the speed controller is operated at the maximum speed and in this case, if the direct connection interrupter of at least one of the compressors is open, the means forming a switch connect another compressor, the switch of which is open to the speed controller and the switch of direct connection of the compressor that was previously connected to the drive is closed;
• the compressor connected to the variable speed drive is operated above the minimum speed, and in this case it is slowed down to the minimum speed, exits the compressor connected to the speed controller is operated at minimum speed, and in this case it is stopped, outputs the compressor connected to the speed controller is stopped and if the direct connection switch of at least one of the compressors is closed, in this case open.
• it comprises, prior to the connection of the variable speed drive to one of the compressors, a step of selecting said compressor, by which the chosen compressor is the one which has operated least long over time.
• it comprises, before stopping a compressor in direct connection, a step of selecting the compressor to be stopped, by which the selected compressor is the one which has operated the longest over time.
• the process as described above is particularly suitable for the production of compressed air.
• FIG. 1 is a schematic view of a compressed gas production installation according to the invention.
• FIGS. 2A and 2B are diagrams showing the patterns of gas pressure over time and the corresponding regulation of a compressor.
• This installation 2 comprises three compressors 4, 6, 8 which are connected in parallel to the inlet 10 of a buffer tank 12 of compressed gas via a first connecting pipe 14 provided with a filter 16.
• a outlet 18 of the buffer tank 12 is connected to a compressed air user network (not shown) via a second connecting line 20 provided with a cut-off valve 22.
• the compressors 4, 6, 8 are lubricated screw compressors. This type of compressor allows operation in a certain range of rotational speeds. Within this range, the rotational speed can be adjusted continuously. The range is delimited by a maximum rotation speed FMAX, 100% and a minimum rotation speed FMIN, other than 0, which amounts for example to 50% of the maximum rotation speed FMAX. Exceptionally, the compressors 4, 6, 8 can be operated, for a short duration, at a variable speed also continuously up to a transition speed FTRA, greater than the maximum speed FMAX.
• compressor 4, 6 or 8 considered must be stopped, since the lubrication of the screw is insufficient in this range of rotation speeds.
• the compressed air flow is substantially directly proportional to the speed of rotation.
• Such compressors are for example compressors of the DSD 201 / 7.5 bar type sold by the company KAESER.
• the installation 2 also comprises a source of electrical energy, in this case a source of three-phase power current 24.
• the installation 2 comprises three first lines 26, 28, 30 for connection to three wires. Each of the first connection lines 26, 28, 30 connects one of the compressors 4, 6, 8 to the current source 24.
• Each of the first connection lines 26, 28, 30 is provided with a first switch 32, 34, 36 allowing an individual establishment or interruption of the connection between the compressors 4, 6, 8 and the current source 24.
• the installation 2 further comprises a variable speed drive VAR connected to the current source 24 by a second connection line 44 with three wires.
• the variable speed drive is suitable for generating a power current whose frequency quence determines the speed of rotation of a compressor 4, 6, 8 connected to this VAR drive.
• the VAR variable speed drive is for example an ATV-68 type drive sold by the company SCHNEIDER.
• the installation 2 comprises three second switches 46, 48, 50, and a third connection line 52 with three wires.
• the connection line 52 is subdivided into three branches 52A, 52B, 52C, each of which connects the variable speed drive VAR to one of the compressors 4, 6, 8, in parallel with the first connection lines 26, 28, 30.
• Each second switches 46, 48, 50 is interposed in one of the branches 52A, 52B, 52C.
• Each of the compressors 4, 6, 8 can therefore be individually connected to the VAR variable speed drive.
• a gas pressure sensor 54 is placed downstream of the compressors 4, 6, 8 in the gas network, for example in the buffer tank 12.
• the installation 12 also includes a control device, in this case a CMD programmable controller.
• This CMD control device comprises an input 56 which is connected to the pressure sensor 54 by a sensor line 58, in order to observe the gas pressure P established in the gas network.
• the CMD command also comprises three outputs 60, 62, 64 which are connected to first 66, second 68 and third 70 control lines of the first switches 32, 34, 36, and three outputs 72A, 72B, 72C which are connected to first 74A, second 74B and third 74C control lines of the second switches 46, 48, 50.
• Another output 76 of the CMD control is connected to a control line 78 of the variator VAR.
• the second switches 46, 48, 50 form switching means by which one of the compressors can be connected to the variable speed drive VAR.
• the outputs 60, 62, 64, 72A, 72B, 72C and the associated control lines 66, 68, 70, 74A, 74B, 74C are adapted to open or close the switches 32, 34, 36, 46, 48, 50.
• the output 76 and the control line 78 are adapted to adjust the output frequency of the VAR drive. Outputs 60, 62, 64, 72A,
• the programmable controller CMD includes a memory MEM in which the high pressure threshold PSH and low pressure PSL thresholds are stored, and a program PRG for controlling the installation.
• the memory MEM stores, for each of the compressors 4, 6, 8, the total operating time of the associated compressor 4, 6, 8.
• the PRG program is suitable for regulating the variable speed drive VAR according to a regulation law, in this case in PID regulation mode when the pressure P observed is between the two pressure thresholds PSH and PSL.
• the PID fart mode varies the output frequency of the drive as a function of the integral and the derivative of the difference between the actual value and the set value over a predetermined time interval.
• the CMD control device further comprises means for selecting from the compressors whose first switch 32, 34, 36 is open and which is not connected to the VAR variator, a compressor 4, 6, 8 having to be connected to the variator VAR speed according to the following condition.
• the compressor with the least total operating time.
• the PRG program implemented in the CMD command controls the first switches 32, 34, 36 and the second switches 46, 48, 50 according to an exclusive connection mode. This mode does not allow the closing of one of the second switches of a specific compressor 4, 6, 8, until the first switch 32, 34, 36, associated with this compressor is open.
• this mode does not allow the closing of one of the second switches 46, 48, 50 unless all the second switches 46, 48, 50 are open.
• the CMD command is furthermore provided with means for detecting a failure of one of the components of the installation 2.
• These means are connected to a telephone line 80 in order to warn the maintenance personnel in the event of a failure.
• FIGS. 2A and 2B show an example of the patterns over time of the pressure P prevailing in the air network as well as of the variation of the rotation speed of a compressor during the operation of the installation.
• the abscissas of the two diagrams represent the time elapsed during fifteen phases I to XV, which are not shown to scale.
• the ordinates of diagram 2A show the pressure P established in the air network and observed by the pressure sensor 54.
• the ordinates of diagram 2B indicate the speed of rotation of the compressor. On the ordinate axis are marked the three determining speeds of the compressor, namely, the minimum speed FMIN (50%), the maximum speed (100%), as well as the transition speed FTRA (120%).
• the compressor is connected to the VAR frequency converter and is operated in PID control. Due to the variation in the compressed air flow, the variable compressor speed is adjusted within the range between the minimum speed FMIN and the maximum speed FMAX, so that the pressure P remains substantially the pressure PREG.
• phase II the demand for compressed air drops so that the variable compressor is brought to its minimum speed FMIN during this phase.
• FMIN the pressure of the variable compressor
• the pressure P rises during phase III.
• the pressure P reaches the high pressure threshold PSH.
• phase V due to the decrease in the gas flow produced, the pressure P falls to the low pressure threshold PSL, and remains there for a time T6 (phase VI), sufficient for the CMD command to restart the compressor with the minimum speed FMIN, after which the pressure P rises again to the high pressure threshold PSH (phase VII), and crosses this pressure.
• phase VI a time sufficient for the CMD command to restart the compressor with the minimum speed FMIN, after which the pressure P rises again to the high pressure threshold PSH (phase VII), and crosses this pressure.
• the pressure P remains above the high pressure threshold PSH and after a time T4 (phase VIII), sufficient for the variable compressor to be stopped again, the variable compressor is then stopped.
• phase IX the pressure P falls below the high pressure threshold PSH before the time T7 has elapsed, then below PSL.
• phase X which lasts time T6
• the pressure P remains below the low pressure threshold PSL and, consequently, the compressor is started at its FMIN speed.
• phase XII continuous PID mode
• phase XIV the CMD command increases the speed of the compressor to the transition speed FTRA, disconnects this variator compressor (DC point) and closes the corresponding switch 32, 34, 36.
• the compressor is operated in fixed mode at FMAX speed.
• the speed reference of the VAR variator is brought to 0, then another compressor is selected and is connected to the variator. Then, this compressor is started at FMIN speed.
• FMIN the flow of compressed air produced
• the installation uses only one variable speed drive, hence a low investment cost.
• the compressor starts are all done with the variator and are distributed evenly over all the compressors, which leads to regular wear of these.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Control Of Positive-Displacement Pumps (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=29286464

Family Applications (1)

Country Status (4)

Families Citing this family (1)

Family Cites Families (10)

• 2002
  • 2002-05-14 FR FR0205906A patent/FR2839755B1/fr not_active Expired - Fee Related
• 2003
  • 2003-04-29 EP EP03749908A patent/EP1511938A1/de not_active Withdrawn
  • 2003-04-29 AU AU2003246870A patent/AU2003246870A1/en not_active Abandoned
  • 2003-04-29 WO PCT/FR2003/001339 patent/WO2003095841A1/fr not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events