EP1585901A1

EP1585901A1 - Plant for producing compressed gas and method for using said plant

Info

Publication number: EP1585901A1
Application number: EP03799723A
Authority: EP
Inventors: Stéphane Laroye; François PANCRAZI
Original assignee: Air Liquide SA; LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2003-01-10
Filing date: 2003-12-12
Publication date: 2005-10-19
Anticipated expiration: 2023-12-12
Also published as: CN1738974A; US20060099085A1; FR2849906B1; AU2003299425A1; ATE402341T1; WO2004070206A1; FR2849906A1; RU2005125419A; DE60322435D1; EP1585901B1; JP2006513360A

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

INSTALLATION AND METHOD FOR PRODUCING A COMPRESSED GAS

The present invention relates to a method for producing compressed fluid as well as an installation for producing compressed fluid for its implementation.

As a known compressed air production installation, there is for example that described in the article entitled: "Compressed air, feedback on a sale by the cubic meter, published in ENERGIE PLUS, n ° 224 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 sized to so that it runs 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 according to the pressure observed in the air network. When the installation includes more than two compressors, only one has a variable flow rate.

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 that is hardly compatible with the expected energy gain, and it can only be envisaged for higher-end installations such as air conditioning stations or cold production systems.

The object of the present invention is to overcome the drawbacks mentioned, 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 above. after. 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 compressed fluid network, - 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 suitable for measuring the pressure of the fluid prevailing in the compressed fluid network, and

- at least one control means suitable for controlling one or the other of the switching means, characterized in that: the control means (s) are connected to one or more individual actuation means for 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, spell started, spell passed in idle state, spell passed in charge mode, spell passed when stopped , 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 the present 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, we mean 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 (O ₂ ), nitrogen (N ₂ ), argon (Ar), dioxide carbon monoxide (CO ₂ ), carbon monoxide (CO), helium (He), nitrous oxide (N ₂ O), nitrogen monoxide (NO), mixtures of carbon dioxide nitrogen and oxygen, carbon dioxide and oxygen, nitrogen and carbon monoxide, helium and oxygen, such as, for example, mixtures (50% by volume (v / v) NO + 50% v / v O ₂ ), (5% v / v CO ₂ , 95% v / v O ₂ ), (200 to 800 ppm NO in N ₂ ), (78% He + 22% v / v O ₂ ), (65% He + 35% O ₂ ), (80% v / v He + 20% v / v O ₂ ) 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 is meant in the context of the present invention, the set of measurements and / or counts and / or calculations to be carried out which gives rise to the choice to change or not to change, 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 compressor permanently or discontinuously over 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

- Ne _: Maximum number of compressor starts per hour; this parameter is set by the manufacturer of the compressor.

- TMAV: Minimum idling time before stopping; - T _p : Duration of use before forced changeover;

- TMAV: Minimum duration of no-load operation before switching on to load.

Variable calculated continuously - T: Date by current time.

Variables calculated for each compressor at each change of state of one of the compressors

- Tc _/ v: Date of the last change of state (running on charge to running on idle) in the last hour;

- TMG: Number of hours of overall operation, since the start of the installation (overall operation time);

- T ^ T ₂ ... T _NC : Set of start dates in the last hour, from Ti from the most recent start to T _N c the oldest start; - N _D : Number of starts made in the last hour;

- TRDEM: Duration remaining 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 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 (s) which, at a given time t, must be, spell started, spell passed idling, spell passed under load, or stopped, thanks to the protocol of choice as defined above. This programmable controller 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 implementing the installation as defined above, characterized in that that it includes, over time, one or other of the following operating steps:

(a) - when the fluid pressure in the compressed fluid network downstream of said installation is situated in a value range between the high pressure threshold, PSH, and the low pressure threshold, PSL, the fluid pressure in said network is maintained in this value range 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) - s jt 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) - several compressors in the installation are stopped, the others being running under load and in this case, the compressor stopped with the most starts per hour in the last hour (N _D ) is the most small, has switched to load operation and if several of the stopped compressors have this same minimum (N), the one with the shortest overall operating time (TMG) is switched to load operation;

(iii) - outputs all the compressors in the installation are stopped and in this case, the stopped compressor whose (N) is the smallest, is switched on and if several of the stopped compressors have this same (N _D ) minimum, the one with the shortest (TMG), is switched on under load;

(iv) - spjt only one of the compressors of the installation is in idle mode, the others being in charge mode or stopped and in this case said compressor in idle mode is in charge;

(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 whose remaining time before next available start (TRDEM) is the longest, went into load operation and if several compressors in no-load operation have this same maximum (TRDEM), the one with the largest (N _D ), has gone into load operation and if several no-load compressors have this same (TRDEM) maximum and this same (N _D ) maximum, the one with the shortest (TMG) is loaded; (vi) - spjt 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 (N _D ) is switched on and if several of the stopped compressors have this same maximum (TRDEM) and this same maximum (N _D ), the one with the (TMG) is the shortest passed on on load;

(c) - when the fluid pressure in said network becomes greater than PSH for a configurable period, (i) - spjt 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 compressor is switched to no-load operation;

(ii) - spjt 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 (Ne - N _D ) is the largest, has switched to no-load mode and if several of the compressors in operation under load have this same maximum number (Ne - N _D ), the one with the longest TMG is switched to no-load mode;

(iii) - spjt all the compressors of the installation are running under load and in this case, the compressor running under load with the largest number of starts per hour available (Ne - N _D ) is switched on unladen and if several of the compressors in operation under load have the same maximum number (Ne - N _D ), the one with the longest TMG is switched to idle. In the method as defined above, the number Ne generally between 2 and 8.

By considering that Ne 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 (1 / N _c ) 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 TMAV, it has come to a stop.

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 time called T _P) and that 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 appended drawings, in which:

- Figure 1 is a schematic view of a compressed fluid production installation according to the invention; and

- Figure 2 shows the diagrams showing the patterns of 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, idling and running under load, 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 d compressed air (not shown) via a second connection 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 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.

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 also 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 connected to first 66, second 68 and third 70 control lines of the switching means 32, 34 and 36.

The outputs 60, 62, 4 and the associated control lines 66, 68, 0, 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 according to the fluid pressure P.

In addition to the central processing unit CPU, the programmable controller CMD includes a memory MEM in which the high pressure PSH and low pressure PSL thresholds are stored, and all of the data acquired relating to the parameters and variables indicated above and a PRG program for control of the installation 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 be, spjt started, spell switched to idling, spjt switched to loaded, spell 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 of one hour, the pressure P prevailing in the air network as well as two diagrams of the change of state of three compressors in parallel (CO1, CO2, CO3), 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 under load; MV: running under 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 according to the invention made it possible to save up to approximately 10% of energy compared to an installation of the prior art.

Claims

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 compressor, 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 compressed fluid network, and

- at least one control means suitable for controlling one or the other of the switching means, characterized in that: the control means (s) are connected to one or more individual actuation means for 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, spjt started, spjt switched to idle, spjt switched to load, output switched off , 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 which the compressors are identical.

4 - Installation as defined in any one of claims 1 to 3, wherein the compressed fluid is compressed air.

5 - Installation as defined in one of claims 1 to 4, comprising from two to six compressors. 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 over 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 observed exceeds the PSH or PSL pressure thresholds, the compressor (s) which, at a given time t, must be, start started, spjt switched to no-load operation, spjt switched to load operation, spjt 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.

10 - 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 input (10) d 'a buffer tank (12) of compressed fluid via a first connecting line (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 automaton

CMD, comprising: a central processing 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 (s) which, at a given time t, must be, output started, spjt switched to idle, output switched to load, spjt stopped, an input (56) connected to the pressure sensor (54) by a sensor line (58), means for detecting 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 command lines (66), (68) and (70), being ad adapted to switch each of the compressors into one or other of the following three states: stop, idle run and load run; 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 - Process for producing a compressed fluid using 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:

(b) - when the fluid pressure in said network becomes lower than PSL for a configurable period, (i) - spjt 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) - several compressors in the installation are stopped, the others being running under load and in this case, the compressor stopped with the most starts per hour in the last hour (N _D ) is the most small, went on to charge and if several of the stopped compressors have this same minimum (N _D ), the one with the shortest overall running time (TMG) is switched on to charge;

(iv) - spjt 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) - spjt several of the compressors of the installation are in idle mode, the others being in charge mode or stopped and in this case, the compressor in idle mode whose remaining time 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 (N _D ), went to load and if several of the compressors when idling have this same maximum (TRDEM) and this same maximum (N _D ), the one with the shortest (TMG) is charged;

(vi) - spjt 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 (N _D ) 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) - spjt only one of the compressors of the installation is running under load, the others being stopped or running under no load and in this case said compressor is switched to no load; (ii) - spjt several of the compressors of 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 (N _c - N _D ) is the largest, has switched to no-load mode and if several of the compressors in operation under load have the same maximum number (N _c - N _D ), the one with the longest TMG is switched to no-load mode;

(iii) - spjt all 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 (N _c - N _D ) has switched to no load and if several of the compressors running under load have the same maximum number (Ne - ND), the one with the longest TMG is switched to no load.

12 - Method as defined in claim 11 wherein, when a compressor has been in idle mode for a duration greater than the minimum duration of idle idle time before stop (TMAV), and that the number (Ne - N _D ) 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 on load is switched off.

14 - Method as described in one of claims 11 to 13, wherein the compressed fluid is compressed air.

15 - Computer program for carrying out the process as defined in one of claims 11 to 14.