FR2849906A1 - Compressed fluid producing installation for air conditioning station, has three compressors, each including one commutation unit , and control program selecting one compressor based on pressure of fluid in compressor - Google Patents

Abstract

The installation (2) has three compressors (4,6,8), each including a commutation unit. Three connection lines couple the respective compressors to a current source. A fluid pressure transducer (54) measures a pressure of fluid in the compressors. A control device is coupled to three command lines of the commutation units. A control program selects a compressor before being stopped, or being loaded based on the fluid pressure. The commutation units are coupled in parallel to an inlet of a compressed fluid reservoir stopper by a connecting duct having a filter. An exit of the stopper is coupled to a compressed user network by another connecting duct having a chopping valve. Independent claims are also included for the following: (1) a process of production of compressed fluid implementing the compressed fluid producing installation (2) a computer program for executing the process of production of compressed fluid.

Description

The present invention relates to a method for producing compressed fluid

  as well as a compressed fluid production installation for its implementation

covers.

  As a known compressed air production installation, there is for example 5 that described in the article entitled: "Compressed air, feedback on a sale by the cubic meter, published in ENERGIE PLUS, n0224 of April 15, 1999, periodical of the Technical Association for Energy Environment. It includes at least two compressors, the discharge side of which is connected to a compressed air network; at least one of these compressors is at fixed speed and is dimensioned so that it operates continuously at 100% of its capacity; another is at variable speed and is adjusted so as to top up the required fluid flow rate. This last compressor is started or stopped depending on the pressure found in the air network When the installation includes more than two compressors, only one has a variable flow.

  However, this type of installation cannot be operated economically over a wide range of fluid flow rates.

  European patent application EP 1 249 675 describes a method for controlling a compressor battery by means of a frequency converter. However, this method often requires a financial investment 20 that is hardly compatible with the expected energy gain, and it is only possible for higher-end installations such as air conditioning stations or cold production systems.

  The object of the present invention is to overcome the aforementioned drawbacks, and to propose an installation for supplying compressed fluid which is economical, in particular as regards energy consumption. Another object is a compressed fluid supply installation which has a low maintenance cost.

  In the context of its research to achieve the aforementioned objectives, the applicant has noticed that, unexpectedly, it was possible to significantly improve the overall specific energy of a compressor installation by implementing the device described below. .

  This is why, according to a first aspect, the subject of the invention is an installation for producing a compressed fluid comprising: - n compressors, n being greater than or equal to 1, the discharge side of which is connected to a fluid network compressed, - for each of the compressors, a connection line with a power source, - for each of the compressors, at least one switching means, adapted to trigger the change of state of each of the compressors, - at least one sensor pressure adapted to measure the pressure of the fluid prevailing in the compressed fluid network, and - at least one control means adapted to control one or the other of the switching means, characterized in that: the means or control means are connected to one or more individual actuation means of each of the switching means, and the control means or means comprise one or more selection means, capable of selecting one or more of the compr esseurs to be either started, or switched to idle, or switched to load, or switched to stop, according to a predetermined choice protocol, depending on the pressure of said compressed fluid in said network.

  By state, the following three states are used in the context of the present invention for each compressor: the compressor is stopped; the compressor is running with no load; the compressor is running under load.

  The compressors used in the installation which is the subject of this invention are preferably of the "all-or-nothing" type.

  According to another preferred aspect of the present invention, the compressors are identical.

  By all-or-nothing type compressor is meant mainly commercial compressors classified in this category and more particularly screw compressors.

  By compressed fluid is meant a fluid whose total pressure is greater than one atmosphere and more particularly: air, oxygen (02), nitrogen (N2), argon (Ar), carbon dioxide (CO2), carbon monoxide (CO), helium (He), nitrous oxide (N20), nitrogen monoxide (NO), mixtures of nitrous oxide and oxygen, carbon dioxide and oxygen, nitrogen and carbon monoxide, helium and oxygen, such as, for example, mixtures (50% by volume (v / v) N20 + 50% v / v 02 ), (5% v / v CO2, 95% v / v 02), (200 to 5800 ppm NO in N2), (78% He + 22% v / v 02), (65% He + 35% 02 ), (80% v / v He + 20% v / v 02) OR mixtures of nitrogen and carbon dioxide.

  According to another preferred aspect of the present invention, the installation as defined above, is an installation for producing compressed air.

  By predetermined choice protocol, within the context of the present invention, is meant all of the measurements and / or counts and / or calculations to be carried out which give rise to the choice of changing or not changing, the state of the one or more of the compressors of said installation, when the pressure found in the compressed fluid network crosses one of the two limit values which are the low threshold pressure (PSL) and the high threshold pressure (PSH).

  According to a first particular aspect of the present invention, the installation as defined above, comprises from two to six compressors.

  According to a second particular aspect of the present invention, the installation as defined above comprises at least one data acquisition means, capable of dating and determining each change of state of each presser permanently or discontinuously in the time.

  According to this particular aspect of the present invention, the choice protocol is defined using all of the following parameters: Variables set at initialization - Nc: Maximum number of compressor starts per hour; this parameter is set by the manufacturer of the compressor.

  - TMAV: Minimum idling time before stopping; - Tp: Duration of use before forced permutation; - TMAV ': Minimum duration of no-load operation before switching on to load.

  Variable permanently calculated - T: Date by current time.

  Variables calculated for each compressor at each change of state of one of the compressors - TcN: Date of the last change of state (running on load towards idling) in the last hour; - TMG: Number of hours of overall operation, since the start of the installation (overall operation time); - T1, T2 ... TNC: Set of start dates in the last hour, from T1 from the most recent start to TNC the oldest start - ND: Number of starts made in the last hour; TRDEM: Remaining time before next start possible.

  According to a variant of the method which is the subject of the present invention, instead of the overall running time of each TMG compressor, their running time under overall load (TMCG) is followed, which represents the number of hours of running under load, from the start of the installation.

  According to a preferred mode of this particular aspect, the control means comprise a programmable automaton characterized in that it comprises a central unit comprising a memory and a computer program able to select, when the pressure P observed exceeds the pressure thresholds PSH or PSL, the compressor or compressors which, at a given time t, must either be started, or switched to no-load operation, or switched to loaded operation, or stopped, using the choice protocol as defined above. This pro20 grammable automaton possibly includes means allowing its remote control.

  According to a fourth particular aspect of the present invention, in the installation as defined above, the compressors are connected in parallel by their discharge side, to a buffer reservoir of compressed fluid by means of a first connection 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 30 covering the installation as defined above, characterized in that it comprises, over time, one or the other of the operating steps. following: (a) - when the pressure of the fluid in the compressed fluid network downstream of said installation is within a value range between the high pressure threshold, PSH, and the low pressure threshold, PSL, the pressure fluid in said network is maintained in this range of value by means of at least one of the compressors of the installation; (b) - when the fluid pressure in said network becomes lower than PSL for a configurable period, (i) - either only one of the compressors of the installation is stopped, the others being in operation under load and in this case said compressor stopped is de10 funny and went on load; (ii) - either several of the compressors in the installation are stopped, the others being in operation under load and in this case, the compressor stopped whose number of starts per hour in the last hour (ND) is the smallest , has switched on to charging and if several of the stopped compressors have this same minimum (ND), the one with the shortest overall running time (TMG) is switched on to charging; (iii) - either all of the compressors in the installation are stopped and in this case, the stopped compressor with the smallest (ND) is switched on and if several of the stopped compressors have the same (ND) minimum, the one with the shortest (TMG), is switched on under load; (iv) - either only one of the compressors of the installation is in idle mode, the others being in load mode or stopped and in this case said compressor in idle mode is loaded; (v) - either several of the installation's compressors are in idle mode, the others being in charge mode or stopped and in this case, the compressor in idle mode, the time remaining before next available start (TRDEM) is the longest, went on to load and if several of the compressors when idle have this same maximum (TRDEM), the one with the largest (ND) is switched on and if several 30 of the no-load compressors have this same maximum (TRDEM) and this same maximum (ND), the one with the shortest (TMG) is loaded; (vi) - either all the compressors of the installation are in idle mode and in this case, the compressor in idle mode whose (TRDEM) is the longest, has gone on in charge mode and if several of the compressors stopped have this same maximum (TRDEM), the one with the largest (ND) is switched on and if several of the stopped compressors have this same maximum (TRDEM) and this same maximum (ND), the one with the (TMG ) is the shortest is switched on under load; (c) - when the fluid pressure in said network becomes greater than PSH for a configurable period, (i) - either only one of the compressors of the installation is running under load, the others being stopped or running at no load and in this case said presser com10 is switched to idling; (ii) - either several of the installation's compressors are running under load, the others being stopped or running under no load and in this case, the compressor running under load including the number of starts per hour available (NC - ND) is the largest, went to idle and if several of the 15 compressors on load have this same number (NC - ND) maximum, the one with the longest TMG goes to idle; (iii) - either all of the compressors in the installation are operating under load and in this case, the compressor operating under load of which the number of starts per hour available (NC ND) is greatest has switched on 20 to empty and if several of the compressors in operation under load have the same maximum number (NC - ND), the one with the longest TMG is switched to idle.

  In the method as defined above, the number NC generally between 2 and 8.

  By considering that Nc is determined on the basis of a homogeneous distribution of the compressor starts in a given hour, it is possible to determine a duration during which the compressor is stopped and cannot be started again. This duration, called the remaining time before the next available start or TRDEM, expressed in hours, is therefore less than 30 (1 / Nc) h. TRDEM is equal to 0 when there has been no start-up during the previous hour.

  It is generally accepted that a compressor cannot go directly from the operating state under load to the stopped state without it having remained in the idle operating state for a minimum duration, here called minimum duration no load before stop or TMAV.

  In the method as defined above, TMAV is generally greater than or equal to 30 seconds.

  In the process as defined above, the TMG or overall running time, expresses the number of hours during which a given compressor has operated since the installation was started up.

  According to a third particular aspect of the method as defined above, when a compressor has been in idle mode for a duration greater than 10 TMAV, it has come to a standstill.

  According to a fourth particular aspect of the method as defined above, when in the installation at least one of the compressors is stopped, and at least one of the compressors is running under load, when the duration since the last starting of said compressor in operation is greater than a permutation duration called Tp, and its TMG is greater than the TMG of the compressor in stop, the compressor in stop is switched on in charge and the compressor in charge in charge went to a standstill.

  The process as described above is particularly suitable for the production of compressed air.

  According to a last aspect of the invention, its subject is a computer program for carrying out the method as defined above.

  The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the accompanying drawings, in which: - Figure 1 is a schematic view of a production installation of compressed fluid according to the invention; and - Figure 2 represents the diagrams showing the stages of the fluid pressure over time and the corresponding regulation of a compressor.

  This installation 2 comprises three compressors 4, 6, 8, each provided with a switching means, 32, 34 and 36 capable of causing them to toggle in one of the three states of stopping and idling. and the step under load, which are connected in parallel to the inlet 10 of a buffer tank 12 of compressed fluid by means of a first connecting pipe 14 provided with a filter 16. An 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. 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 of connection to 10 three wires. Each of the first connection lines 26, 28, 30 connects one of the compressors 4, 6, 8 to the current source 24.

  A fluid pressure sensor 54 is placed downstream of the compressors 4, 6, 8 in the fluid network, for example in the buffer tank 12.

  The installation 12 further comprises a control device, in this case a programmable automatic controller CMD.

  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 fluid pressure P established in the fluid network.

  The CMD command also comprises three outputs 60, 62, 64 which are linked to first 66, second 68 and third 70 control lines of the switching means 32, 34 and 36.

  The outputs 60, 62, 64 and the associated control lines 66, 68, 70 are adapted to control the switching of the compressors 4, 6 and 8.

  The outputs 60, 62, 64 are controlled by a central unit CPU of the CMD control depending on the fluid pressure P. In addition to the central unit CPU, the programmable controller CMD includes a memory MEM in which the high PSH and low pressure PSL thresholds, and all of the data acquired relating to the parameters and variables indicated above and a PRG program for controlling the installation capable of selecting, when the pressure P observed exceeds the pressure thresholds PSH or PSL, the compressor (s) which, at a given time t, must either be started, or switched to no-load mode, or switched to load mode, or stopped.

  In addition, 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 implemented in the CMD command controls the switching means 32, 34 and 36 according to an exclusive connection mode.

  The CMD control 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.

  Figure 2 shows an example of the pace over a time interval 10 of one hour, of the pressure P prevailing in the air network as well as two diagrams of the change of state of three compressors in parallel (CO1, C02 , C03), according to the invention (new control law) and according to the state of the art (old law.

  The abscissas of the two diagrams represent the different states of the three compressors: (MC running on load; MV: running on no load; SB: off).

  This figure shows that the process according to the new control law makes it possible to eliminate a large part of the vacuum steps existing in the process according to the old control law (gray areas of the diagram).

  At the end of the experiment described below, it was found that the installation 20 according to the invention made it possible to save up to approximately 10% of energy compared to an installation of the prior art .

Claims (10)

  1 - Installation for producing a compressed fluid comprising: - n compressors, n being greater than or equal to 1, the discharge side of which is connected to a network of compressed fluid, - for each of the compressors, a connection line with an energy source, - for each of the compressors, at least one switching means, adapted to trigger the change of state of each of the compressors, - at least one pressure sensor adapted to measure the pressure of the fluid prevailing in the network of compressed fluid, and - at least one control means adapted to control one or the other of the switching means, characterized in that: the control means or are connected to one or more individual actuation means of each of the switching means, and the control means or means comprise one or more selection means, capable of selecting one or more of the compressors to be either started or switched to idle , either switched to load, or switched to stop, according to a predetermined choice protocol, depending on the pressure of said compressed fluid in said network.   2 - Installation as defined in claim 1, in which the compressors used are preferably of the "all-or-nothing" type.   3 - Installation as defined in one of claims 1 or 2, in la25 which the compressors are identical.   4 - Installation as defined in any one of claims 1 to 3, wherein the compressed fluid is compressed air.   - Installation as defined in one of claims 1 to 4, comprising from two to six compressors.   3 0 6 - Installation as defined in one of claims 1 to 5, comprising at least one data acquisition means, capable of dating and determining each change of state of each compressor permanently or discontinuously in the time.   7 - Installation as defined in one of claims 1 to 6, wherein the control means comprise a programmable controller characterized in that it comprises a central unit comprising a memory and a computer program capable of selecting, when the pressure P noted d5 passes the PSH or PSL pressure thresholds, the compressor (s) which, at a given time t, must either be started, or switched to no-load mode, or switched to load mode, or stopped and possibly means allowing its remote control and that it is able to operate by means of a program suitable for the protocol of choice as defined above.   8 - Installation as defined in one of claims 1 to 7, in which 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.   9 - Installation as defined in claim 8, wherein the first connecting pipe is provided with a filter.   - Installation (2) as defined in one of claims 1 to 9, comprising: - three compressors (4), (6) and (8), each provided with a switching means (32), (34 ) and (36), which are connected in parallel to the inlet (10) of a buffer tank (12) of compressed fluid via a first connecting pipe (14) provided with a filter (16 ); an outlet (18) of the buffer tank (12), is connected to a user network of compressed fluid, via a second connecting pipe (20) provided with a cut-off valve 22; - a three-phase power current source (24); - three lines (26), (28), (30) connecting to three wires connecting one of the compressors (4), (6) and (8) to the current source (24); - a pressure sensor (54) of the fluid placed downstream of the compressors (4), (6) and (8) in the fluid network, for example in the buffer tank (12); A control device, in this case a programmable automatic controller CMD, comprising: a central unit (CPU), a memory (MEM) in which the high pressure PSH and low pressure PSL thresholds are stored, and all of the acquired data relating to the parameters and variables indicated above, a program (PRG) for controlling the installation suitable for selecting, when the pressure P observed exceeds the pressure thresholds PSH or PSL, the compressor or compressors which, at a given time t , must be either started or switched to no-load operation, or switched to load operation, or stopped, an input (56) connected to the pressure sensor (54) by a sensor line (58), detection means of a failure of one of the components of the installation (2), connected to a telephone line (80), three outputs (60), (62) and (64) connected to first (66), second ( 68) and third (70) control lines of the switching means (32), (34) and (36), the outputs (60), (62) and (64) and the associated control lines (66), 15 (68) and (70), being adapted to switch each of the compressors in one of the following three states: off, idle and loaded; the outputs (60), (62) and (64) being controlled by the central unit CPU of the CMD control, at the pressure of the fluid P. 11 - Method for producing a compressed fluid covering the installation as defined in one of claims 1 to 10, characterized in that it comprises, over time, one or the other of the following operating steps: (a) - when the pressure of the fluid in the network of compressed fluid downstream of said installation is situated in a value range between the high pressure threshold, PSH, and the low pressure threshold, PSL, the pressure of the fluid in said network is maintained in this value range at means of at least one of the compressors of the installation; (b) - when the fluid pressure in said network becomes lower than PSL for a configurable period, (i) - either only one of the compressors of the installation is stopped, the others being in operation under load and in this case said compressor stopped is started and switched on under load; (ii) - either several of the compressors in the installation are stopped, the others being in operation under load and in this case, the compressor stopped whose number of starts per hour in the last hour (ND) is the smallest , has switched to charging operation and if several of the stopped compressors have this same minimum (ND), the one with the shortest overall operating time (TMG) is switched to charging operation; (iii) - either all of the compressors in the installation are stopped and in this case, the stopped compressor with the smallest (ND) is switched on and if several of the stopped compressors have the same (ND) minimum, 10 the one with the shortest (TMG), is switched on under load; (iv) - either only one of the compressors of the installation is in idle mode, the others being in load mode or stopped and in this case said compressor in idle mode is loaded; (v) - either several of the installation's compressors are in idle mode, the others being in load mode or stopped and in this case, the compressor in idle mode, the time remaining before next available start (TRDEM) is the longest, went on to load and if several of the compressors when idle have this same maximum (TRDEM), the one with the largest (ND) is switched on and if several 20 of the no-load compressors have this same maximum (TRDEM) and this same maximum (ND), the one with the shortest (TMG) is loaded; (vi) - either all the compressors of the installation are in idle mode and in this case, the compressor in idle mode whose (TRDEM) is the longest, has gone on in charge mode and if several of the compressors stopped 25 have this same maximum (TRDEM), the one with the largest (ND) is switched on and if several of the stopped compressors have this same maximum (TRDEM) and the same maximum (ND), the one with ( TMG) is the shortest is switched on under load; (c) - when the fluid pressure in said network becomes greater than 30 PSH for a configurable period, (i) - either only one of the compressors of the installation is running under load, the others being stopped or running at vacuum and in this case said compressor is switched to idle; (ii) - either several of the compressors in the installation are running under load, the others being stopped or running under no load and in this case, the compressor running under load including the number of starts per hour available (NC - ND) is the largest, has switched to no-load operation and if several of the 5 compressors in operation under load have the same maximum number (NC - ND), the one with the longest TMG is switched to no-load; (iii) - either all of the compressors in the installation are running under load and in this case, the compressor running under load with the largest number of starts per hour available (Nc ND) is switched on 10 to empty and if several of the compressors in operation under load have this same maximum number (NC - ND), the one with the longest TMG is switched to idle.   12 - Method as defined in claim 11 wherein, when a compressor has been in idle mode for a duration greater than the minimum duration 15 min of idle operation before stop (TMAV), and that the number (Nc ND) is greater than or equal to 1, it is stopped.   13 - Method as defined in one of claims 11 or 12, wherein, when in the installation at least one of the compressors is stopped, and at least one of the compressors is running under load, when the duration since the last start of said compressor in operation is greater than a permutation duration called Tp, and that its TMG is greater than the TMG of the compressor at stop, the compressor at stop is switched on under load and the compressor running on load went to stop.   14 - Method as described in one of claims 11 to 13, wherein the compressed fluid is compressed air.   - Computer program to carry out the process as defined in one of claims 1 1 to 14.