AU2017205123A1

AU2017205123A1 - Relay connection device for forced ventilation equipment, relay connection system including same, and forced ventilation equipment provided with such systems

Info

Publication number: AU2017205123A1
Application number: AU2017205123A
Authority: AU
Inventors: Chris Norris
Original assignee: Etudes Et Constructions Electromecaniques
Current assignee: Etudes Et Constructions Electromecaniques
Priority date: 2016-01-05
Filing date: 2017-01-04
Publication date: 2018-08-23
Anticipated expiration: 2037-01-04
Also published as: AU2017205123B2; EP3190346B1; CN106940061A; ES2774460T3; FR3046456A1; FR3046456B1; WO2017118816A1; EP3190346A1

Abstract

The invention relates to a relay connection device (3) for forced ventilation equipment (1) having relay fan(s) (8), which includes a duct assembly (6) forming an inner channel (6c) of which the ends (6a, 6b) are open and provided with attachment means (13c, 14c) designed for a sealed connection between a so-called upstream line section (7) and a subsequent line section (7) provided with a relay fan (8), so as to establish fluid communication therebetween, the duct assembly (6) also being provided with means (9) for measuring at least one parameter of the flow with a view to controlling the operation of the relay fan (8) so as to obtain the desired flow conditions at the end of the upstream line section (7). The invention also describes a relay connection system (2) including said relay connection device (3) and forced ventilation equipment (1) including such relay connection systems (2).

Description

(57) Abrege :

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Un dispositif de connexion relais (3) pour une installation de ventilation forcee (1) a ventilateur(s) relais (8), qui comprend un en semble conduit (6) formant un canal interieur (6c) dont les extremites (6a, 6b) sont ouvertes et munies de moyens de fixation (13c, 14c) configures pour un raccordement etanche entre un troncon de ligne (7), dit amont, et un troncon de ligne (7) suivant muni d'un ventilateur relais (8), de I’aeon a les mettre en communication fluidique, l'ensemble conduit (6) etant en outre muni de moyens (9) de mesure d'au moins un parametre de l'ecoulement en vue de commander le fonctionnement du ventilateur relais (8) pour ob tenir a la fin du tiOiicon de ligne (7) amont des conditions d'ecoulement recherchees. Sont egalement decrits un systeme de connexion relais (2) comprenant ledit dispositif de connexion relais (3) et une installation de ventilation forcee (1) comprenant de tels systemes de connexion relais (2).

RELAY CONNECTION DEVICE FOR FORCED VENTILATION SYSTEM, RELAY CONNECTION SYSTEM COMPRISING THE SAME, AND FORCED VENTILATION SYSTEM EQUIPPED WITH SUCH SYSTEMS

The present invention relates to the field of the ventilation of tunnels, and particularly to a relay connection device for a forced ventilation system, a relay connection system comprising such device, and a forced ventilation system equipped with at least one such system.

In order to ventilate a tunnel during excavation work, it is common to collect air outside the tunnel and supply it along the tunnel, via a ventilation line extending to the tunnel face and at the beginning of which is provided a fan by which the outside air is sucked.

In the case of a particularly long and/or small-section tunnel, it is necessary to use one or several so-called relay fans which are interposed between two successive sections of the ventilation line which is, in this case, divided into a series of line sections, with a gap being provided between the end of a section and the corresponding relay fan, such that the end of a section is with free discharge. In other words, each line section generally consists in a ventilating duct at the beginning of which is provided a fan sucking the outside air into the ventilating duct. This is referred to as a relay forced ventilation system.

Such a division of the line into several line sections reduces the static pressure inside each of them, and in particular inside the first section of the ventilation line. Indeed, the static pressure at the end of a free-discharge ventilating duct is inevitably equal to the atmospheric pressure at the same location. If considering that the atmospheric pressure at the inlet of a fan is equal to that of the discharge of the fan at the end of the corresponding line section, the static pressure rise of each fan of the series of fans will be divided in the same way as the line. The leakage rate caused by imperfections and wear of the line depends on the static pressure inside the latter: the higher the static pressure, the larger the leaks. Decreasing the static pressure inside the line thus reduces the leaks and, accordingly, the required flow rate at the beginning of the line. Since the consumed power is the product of the total pressure (static pressure + dynamic pressure) and of the volumetric flow rate of the fan, this decrease in the flow rate necessarily represents a decrease in the consumed power of the fan and, thus, a power saving. The decrease in pressure and power of the fan at the beginning of the line, in some cases, can allow one stage of the fan to be omitted or enable a ventilation system which would otherwise require too much electric power or would exceed the admissible maximum pressure of the line.

FIG.l is a graph showing the evolution of the static pressure and the volumetric flow rate inside a ventilating duct as a function of the total distance of the ventilating duct, for a simple forced ventilation system, namely a line composed of a ventilating duct with a fan at the beginning of the line, and for a forced ventilation system comprising a relay fan, and thus a line divided into two sections. Both systems are also schematically shown in FIG.l.

It can be noted from FIG.l that, theoretically, in the example of a 3 km line, the total electric power consumed by the relay fans in the relay forced ventilation system is 103 kW, while that consumed by the single fan of the simple forced ventilation system is 141 kW.

However, in practice the forced ventilation with relay fan(s) has disadvantages.

The first disadvantage results from the fact that a gap is present between the end of a line section and the relay fan following it. It causes a risk of intake of surrounding contaminated air (dust, pollution, etc.), which then would be injected in the fresh air flow, even though it is essential that the air sucked by a relay fan entirely comes from the air provided by the upstream fan.

In order to solve this problem, it is known to rely on boosting the relay fan: the relay fan is supplied with more air than its own capacity, which ensures an air overflow around the inlet of the relay fan and prevents the contaminated air of the tunnel from entering the air inlet of the relay fan. The recommendations of the French Association for Tunnels and Underground Space (AFTES) advise a flow rate at the end of the section of the upstream fan from 110% to 120% of the capacity of the relay fan. However, as indicated above, the power consumed by a fan is the product of the total pressure and of the volumetric flow rate of the fan (aeraulic efficiency of the fan not included) . Thus, an increase in volumetric flow rate will cause an increase in power consumed by the upstream fan.

FIG.2 is a view similar to FIG.l, but in which the relay forced ventilation system is configured for boosting the relay fan. The curves associated with the simple forced ventilation system are unchanged.

It can be noted from FIG. 2 that the technique of boosting the relay fan leads to a total electric power consumed by the fans in the forced ventilation system of 146 kW, that is a consumed power higher than that of the single fan of the simple forced ventilation system, which is 141 kW.

Accordingly, the boosting technique almost systematically causes the effect opposite to the desired one, that is, a power saving.

A second disadvantage of the forced ventilation with relay fan(s) is that it does not take the evolution of the construction work into account.

Indeed, the selection of the fans is established to meet the needs of the construction work at the end of the excavation, that is, when the tunnel and thus the line reach their maximum length. The or each relay fan will be installed at the predetermined location when the tunnel reaches the corresponding kilometric point. First, the resistance induced by the short-length ventilating duct, namely the ventilating duct located behind the relay fan, will be less large than that taken into account in the calculations, thereby implying that the relay fan will operate at a lower pressure and, therefore, a higher flow rate (for an identical rotation speed). The air surplus of 10-20% initially expected for the boosting and provided to the relay fan will thus be reduced, or even exceeded by the flow rate of the relay fan. Besides the problem of recirculation of contaminated air from the tunnel by the relay fan, this evolution of the ratio between the air provided at the end of the line section by the upstream fan and the air sucked by the relay fan causes a risky management of the primary ventilation of the construction work.

The present invention aims to provide a solution allowing to benefit, in practice, from the power saving theoretically provided by the use of relay fan(s), while ensuring the absence of recirculation of contaminated air from the tunnel and allowing the evolution of the length of the ventilation line to be taken into account during the construction work.

The solution according to the present invention relies on the interposition of a duct assembly providing a leak-proof connection of the end of a line section to the relay fan following it, associated with means allowing to measure at least one flow parameter, in order to control the relay fan such that the flow rate of the latter allows to achieve desired flow conditions .

The present invention thus relates to a relay connection device for a relay forced ventilation system comprising a line divided into a series of line sections formed by ventilating ducts, two successive line sections being spaced from each other, in which ventilation system a so-called primary fan is provided at the beginning of the first line section of said series, and a so-called relay fan, whose speed is adjustable in real time, is provided at the beginning of each line section from the second section of said series, at a distance from the end of the previous line section, characterized in that it comprises a duct assembly forming an inner channel both ends of which are open and provided with fixing means configured to provide a leak-proof connection between two line sections so as to put a so-called upstream line section in fluidic communication with the relay fan of the next line section, the duct assembly being further provided with measuring means for measuring at least one parameter of the air flow inside said line, in order to control the operation of said relay fan to achieve desired flow conditions at the end of the upstream line section.

The desired flow conditions could be, for example, that the static pressure at the end of a line section be close to the atmospheric pressure, such that the downstream line section becomes invisible for the upstream fan. This condition is considered as satisfied if the flow rate of the relay fan is adapted to the flow rate at the end of the ventilating duct. In this case, and as indicated below, said air flow parameter (s) measured by said measuring means could be a flow pressure and/or velocity.

Of course, it is possible to contemplate other desired flow conditions such as, for example, a negative pressure at the end of the line section, thereby relieving the upstream fan. As explained below, such condition could be provided only if the line sections are formed by rigid ventilating ducts.

It can be stressed here that the present invention is not limited to line sections formed by flexible ventilating ducts or rigid ventilating ducts, but can be applied to both types of ventilating ducts.

The duct assembly may be formed by a single piece or several pieces leak-proof connected to each other.

The fixing means of the duct assembly can be configured to provide a leak-proof connection to a relay fan in the case where the relay fan forms the beginning of a line section, or to a ventilating duct section in which the relay fan is located only in the downstream end region of a line section.

Preferably, said measuring means are means for measuring, on one hand, the static pressure of the air inside the inner channel of the duct assembly and, on the other hand, the atmospheric pressure outside the duct assembly. In other words, at least one air flow parameter being measured is the pressure .

Said measuring means can be arranged to measure the static pressure of the air in the region of the end provided with fixing means configured to provide a leak-proof connection to the relay fan, so as to measure the static pressure at the inlet of the relay fan.

According to a particular embodiment, said measuring means comprise a differential pressure sensor whose first terminal is connected to measuring components for measuring static pressure in the inner channel of the duct assembly and whose other terminal is in ambient air, preferably at the same altitude as the axis of the inner channel, in order to measure the atmospheric pressure, said measuring components preferably consisting in at least four pressure tappings connected in parallel to the first terminal of the differential pressure sensor .

If the free-air terminal is at an altitude different from that of the axis of the inner channel, this difference in altitude is then taken into account in the calculations of the flow conditions inside the duct assembly.

Obviously, it will also be desirable to take the geometry of the inner channel and the position of the pressure sensor(s) into account when the flow conditions are calculated from the measurements that have been taken.

Of course, according to the present invention, alternatively or in addition, it is possible to measure the air flow velocity as another parameter, for example by means of anemometers or a set of Pitot tubes in order to control the device ,

However, the of the pressure is measurement advantageous in that the pressure is constant on a section of the inner channel, contrary to the velocity. Furthermore, the implementation of pressure sensors is simpler. Therefore, preferably a control based on the pressure will be selected. It can be noted that one or several parameters different from the one or those used to define the desired flow conditions could be measured, to the extent that in many cases one can arrive at said flow conditions by calculation from said parameters rather than by direct measurement.

Preferably, the duct assembly is provided with at least one vacuum relief valve configured to put the inner channel of the duct assembly in communication with the outside air when the pressure inside the inner channel is lower than a defined pressure threshold, namely with respect to the atmospheric pressure. For a relay forced ventilation system whose line sections are formed by flexible ventilating ducts, the pressure threshold will preferably be 0 Pa, so as to prevent the ventilating duct from collapsing, such pressure lower than 0 Pa could be caused, for example, by a late control of the speed of the relay fan.

Preferably, the duct assembly is provided with at least one pressure-relief valve configured to put the inner channel of the duct assembly in communication with the outside air when the pressure inside the inner channel is higher than a defined pressure threshold, in particular with respect to the atmospheric pressure. The pressure threshold could be set at a threshold value which, when exceeded, could cause a pressure overload at the upstream fan.

For a relay forced ventilation system whose line sections are cylindrical, the duct assembly may comprise a middle part with a square cross section, from a first side of which extends a generally cylindrical first end part whose end is provided with said fixing means, which are configured to provide a leak-proof connection to a line section provided with a relay fan, and from a second side of which a second end part extends, for example with widening generally as a truncated cone, to a cylindrical end region having said fixing means, which are configured to provide a leak-proof connection to the end of a line section.

The present invention also relates to a relay connection system for a relay forced ventilation system comprising a line divided into a series of line sections formed by ventilating ducts, two successive line sections being spaced from each other, in which ventilation system a so-called primary fan is provided at the beginning of the first line section of said series, and a so-called relay fan, whose speed is adjustable in real time, is provided at the beginning of each line section from the second section of said series, at a distance from the end of the previous line section, characterized in that it comprises, for the or each relay fan, a relay connection device as defined above, and an automatic control unit configured to determine, from the measurements took by the measuring means, air flow conditions at the end of the upstream line section to which the relay connection device is intended to be connected, and to control in real time, via a speed controller, the speed of the relay fan in order to achieve desired flow conditions at the end of the upstream line section.

When the relay connection system comprises a relay connection device whose measuring means are means for measuring, on one hand, the static pressure of the air inside the inner channel of the duct assembly and, on the other hand, the atmospheric pressure outside the duct assembly, the automatic control unit is preferably configured so that the static pressure at the end of the upstream line section, which is upstream of the relay fan, is equal to a target value, namely a target value of 0 Pa or slightly higher than 0 Pa.

The present invention also relates to a forced ventilation system comprising a line divided into a series of line sections formed by ventilating ducts, two successive line sections being spaced from each other, in which ventilation system a so-called primary fan is provided at the beginning of the first line section of said series, and a so-called relay fan, whose speed is adjustable in real time, is provided at the beginning of each line section from the second section of said series, at a distance from the end of the previous line section, characterized in that it is equipped, between two successive line sections, with a relay connection system as defined above, whose relay connection device is leak-proof connected between said two successive line sections.

To better illustrate the subject-matter of the present invention, a particular embodiment will be described below, for indicative and non-limiting purposes, with reference to the appended drawings .

On these drawings:

- FIG.l is a graph showing the evolution of the static pressure and the volumetric flow rate inside a ventilating duct as a function of the total distance of the ventilating duct, both for a simple ventilation system and a forced ventilation system with a relay fan;

- FIG.2 is a graph similar to that of FIG.l, for a simple ventilation system and a forced ventilation system with a relay fan and boosting of the latter;

- FIG. 3 is a schematic diagram of a part of the ventilation system according to a particular embodiment of the present invention;

- FIG.4 is a schematic diagram of an alternative to FIG.3;

- FIGS. 5, 6 and 7 are perspective, top respectively, of the relay connection ventilation system of FIG.4; and and end views, device of the

- FIG.8 is a cross-sectional view along the line VII-VII in FIG.7 .

If referring first to FIG.3, is shown a schematic diagram of a part of a forced ventilation system 1 according to a particular embodiment of the present invention, in particular the region between the end of the first line section and the beginning of the next section.

The system 1 differs from a conventional forced ventilation system with relay fan in that it is equipped with a relay connection system 2 comprising a relay connection device 3 and an automatic control unit 4. A speed controller 5, already used in the conventional systems, is also provided.

As it will be described in more detail with reference to FIGS.5-8, the relay connection device 3 comprises a duct assembly 6 having a first end 6a which is leak-proof connected to the end of the ventilating duct 7 forming the first line section and a second end 6b which is leak-proof connected to a relay fan 8, more precisely to its air inlet 8a. The relay fan 8 is speed adjustable by the speed controller 5 and its discharge is connected to a ventilating duct 7 forming another line section .

Thus, the inner channel, designated by 6c in FIGS.5, 7 and 8, puts the ventilating duct 7 in fluidic communication with the relay fan 8, such that all the air from the fan at the beginning of the line (not shown), namely that at the beginning of the ventilating duct 7, is provided to the relay fan 8.

There are measuring means 9 for measuring the static pressure of the air inside the inner channel 6c, in the region of the second end 6b, and for measuring the atmospheric pressure at the vicinity of said second end 6b. The measuring means 9 are here formed by four normalized pressure tappings (ISO 5801 standard), for measuring the static pressure inside the inner channel 6c, connected in parallel to a terminal of a differential pressure sensor 9a whose second terminal remains in ambient air so as to measure the atmospheric pressure.

The differential pressure sensor 9a is connected to the automatic control unit 4 such that an analog output (4-20 mA or other) of said sensor 9a allows to acquire, through the automatic control unit 4, the pressure difference measured between the static pressure inside the inner channel 6c and the atmospheric pressure.

The automatic control unit 4 is configured to send instructions to the speed controller 5 so that the latter can vary the speed of the relay fan 8, by increasing or reducing it, so that the pressure difference measured between the static pressure inside the device and the atmospheric pressure outside the device is close to zero, thereby implying that the flow rate of the relay fan 8 is substantially equal to the flow rate of the air at the end of the ventilating duct 7.

Indeed, if the suction flow rate of the relay fan is lower than the flow rate inside the upstream ventilating duct 7, the pressure inside said ventilating duct 7 will increase, thereby causing an excessive consumed power for the upstream fan (here, at the beginning of the line, since the system 1 has only one relay fan 8). If the suction flow rate of the relay fan 8 is higher than that of the ventilating duct 7, the latter is likely to have a negative pressure with respect to the atmospheric pressure and will be collapsed.

Preferably, the automatic control unit 4 is configured to maintain a slightly positive pressure inside the ventilating duct 7, such that the latter remains expanded. The diameter of the ventilating duct 7 being normally larger than the nominal diameter of the relay fan 8, and the static pressure immediately upstream the relay fan 8 being normally negative, it is just necessary to maintain the static pressure at the inlet of the relay fan 8 at about 0 Pa for the static pressure at the end of the ventilating duct 7 to be positive. In the embodiment shown, it will be equal to the dynamic pressure difference between the ventilating duct 7 and the relay fan 8, plus the head loss due to the conical part of the relay connection device 3.

The relay connection system 2 as a whole is autonomous. Indeed, since it allows to automatically adapt the speed of the relay fan 8 to the flow rate provided by the fan at the beginning of the line, the flow rate provided at the end of the line, thus at the tunnel face during excavation work, can be determined as from the fan at the beginning of the line, thereby allowing to take into account, during the construction work, the increase in ventilating duct length behind the fan relay 8.

Furthermore, since the entire flow rate provided by the fan at the beginning of the line is relayed toward the tunnel face without any recirculation of contaminated air by the relay fan 8, the plots of flow rate and pressure inside the ventilating duct, as well as the powers consumed by the fans, will be close to the theoretical plots of FIG.l.

The relay connection system 2 according to the present invention thus achieves a power saving without any risk of recirculation of contaminated air, while enabling to manage the ventilation in accordance with the evolution of the construction work.

The relay connection device 3 is also provided with vacuum relief valves 10 and pressure-relief valves 11, both being configured to put the inner channel 6c in communication with the outside in case of temporary or permanent dysfunction of the system for controlling the flow rate of the relay fan.

The vacuum relief valves 10 are intended to prevent the duct assembly 6 from collapsing in case a particularly rapid decrease in flow rate at the end of the ventilating duct 7 could not be corrected sufficiently by the decrease in speed of the relay fan 8.

The vacuum relief valves 10 are thus configured to open in case the pressure inside the upstream ventilating duct is negative with respect to the atmospheric pressure.

The pressure-relief valves 11 are intended to protect the fan at the beginning of the line in case of an emergency stop or a failure of the relay fan 8. Indeed, in such a case, the fan at the beginning of the line would be connected to a ventilating duct length going to the tunnel face, which could mean a resistance which is too high for a safe operation of the fan at the beginning of the line.

The pressure-relief valves 11 are thus configured to open in case the static pressure is higher than a maximum static pressure value inside the duct assembly 6. The opening pressure of the valves must be taken into account when sizing the upstream fan .

Thus, in case of emergency stop or failure of the relay fan 8, the pressure inside the duct assembly 6 will increase until the pressure-relief valves 11 open, thereby limiting the static pressure at the fan at the beginning of the line to the resistance of the ventilating duct 7 of the first section, plus the opening pressure of the pressure-relief valves 11. The ventilation of the first section of the tunnel will be ensured.

If now referring to FIG. 4, an alternative to the embodiment described above is shown, the only difference being that the measuring means 9 are here arranged on the conical connecting piece (second end part 14 in FIGS. 5-8) of the duct assembly 6, with two differential pressure sensors measuring two pressure deltas and two rows of pressure tappings located on two circular sections of this conical connecting piece. The first sensor, on the left in FIG.4, is intended to measure the pressure difference (first pressure delta) between the measurement tappings of the first row of measurement tappings and the atmospheric pressure, this pressure difference being used for the control by the automatic control unit. The second sensor, on the right, is intended to measure a second pressure delta between the measurement tappings of both respective circular sections. This second pressure delta represents a dynamic pressure difference due to the velocity variation between both sections, allowing the flow rate of the relay fan to be calculated and displayed (the display of flow rate is schematized by the rectangle to which the arrow from the second sensor is oriented, the other rectangle schematizing the automatic control unit).

A specific embodiment of the relay connection device 3 will now be described in more detail, with reference to FIGS.58 .

The duct assembly 6 comprises a middle part 12 from two sides of which a first end part 13 and a second end part 14 extend.

The middle part 12 is formed by a tube with a square cross section ending, at each of its two ends, into a peripheral flange with which it is leak-proof fixed, by bolts, to corresponding peripheral flanges of the first 13 and second 14 end parts, respectively at 15 and 16.

The vacuum relief valves 10 and the pressure-relief valves 11 are of gravity control type, are located on the upper and lower faces of the middle part 12 and are of hinge type: they take the form of pivoting flaps 10a, 11a configured to pivot around hinges 10b, lib between a first position, in which the pivoting flaps each sealingly close the opening provided in the middle part 12 and in which it is mounted, and a second position in which they are pivoted, toward the inside of the middle part 12 for the vacuum relief valves 10, toward the outside for the pressure-relief valves 11, in order to leave said opening unobstructed and, thus, put the inner channel 6c in communication with the outside.

The control for the pivoting of the vacuum relief valves 10 and the pressure-relief valves 11 is performed by the balance between the force of gravity and the pressure on the surfaces of the flaps.

A hinge-type cover door 17 is provided on a third side of the middle part 12, in order to provide access to the inside of the duct assembly 6 if needed.

The first end part 13 is formed by a piezometric chamber 13a and an intermediary piece 13b.

The piezometric chamber 13a is a cylindrical tubular piece whose inner diameter is equal to the inner diameter of the relay fan and having, at a first end, a flange 13c constituting a means for fixing to the air inlet of the relay fan 8, and thus provided with openings for bolts, and, at its second end, a flange with which it is sealingly fixed, by bolts, at 18, to a flange formed at a first end of the intermediary part 13b.

The intermediary piece 13b is a tubular piece whose inner wall is formed by triangular sections 13d gradually joining the cylindrical section of the end piece 13a to the square section of the middle part 12a. The second end of the intermediary piece 13b is sealingly fixed to the middle part 12a by bolting the flanges, at 15.

The second end part 14 is also formed by an end piece 14a and an intermediary piece 14b.

The end piece 14a is a cylindrical short tube whose first-end region 14c is intended to be inserted into the end of the ventilating duct 7, in order to be fixed thereto, and whose diameter is thus normally larger than the length of one side of the middle part 12a, although this is not necessary. The other end of the end piece 14a is sealingly fixed, by bolting the flanges, at 19, to an end of the intermediary piece 14b.

The intermediary piece 14b is a tubular piece whose other end is sealingly fixed, by bolting the flanges, at 16, to the middle part 12a, and whose inner wall is formed by triangular sections 13d widening outwards from the middle part 12a, so as to gradually join the square section of the middle part 12a to the cylindrical section of the end piece 14a, while taking the increase in dimensions of the inner channel 6c into account. The inside of the intermediary piece 14b thus globally has a truncated cone shape.

The duct assembly 6 thus defined allows a leak-proof connection of the end of the ventilating duct 7 to the relay fan 8, while taking into account the fact that the diameter of the ventilating duct 7 is larger than the nominal diameter of the relay fan 8, without excessively disrupting the air flow exiting the ventilating duct 7.

The static pressure tappings will be provided in the end part 13a of the first end part 13, thus on the relay fan 8 side .

Obviously, said embodiment of the present invention is given at indicative and non-limiting purposes, and modifications could be made without departing from the scope of the present invention .

Claims

1 - A relay connection device (3) for a relay forced ventilation system (1) comprising a line divided into a series of line sections (7) formed by ventilating ducts, two successive line sections (7) being spaced from each other, in which ventilation system a so-called primary fan is provided at the beginning of the first line section (7) of said series, and a so-called relay fan (8), whose speed is adjustable in real time, is provided at the beginning of each line section (7) from the second section of said series, at a distance from the end of the previous line section (7), characterized in that it comprises a duct assembly (6) forming an inner channel (6c) both ends (6a, 6b) of which are open and provided with fixing means (13c, 14c) configured to provide a leak-proof connection between two line sections (7) so as to put a so-called upstream line section (7) in fluidic communication with the relay fan (8) of the next line section (7), the duct assembly (6) being further provided with measuring means (9) for measuring at least one parameter of the air flow inside said line, in order to control the operation of said relay fan (8) to achieve desired flow conditions at the end of the upstream line section (7).

2 - The relay connection device (3) according to claim

1, characterized in that said measuring means (9) are means for measuring, on one hand, the static pressure of the air inside the inner channel (6c) of the duct assembly (6) and, on the other hand, the atmospheric pressure outside the duct assembly (6).

3 - The relay connection device (3) according to claim

2, characterized in that said measuring means (9) comprise a differential pressure sensor (9a) whose first terminal is connected to measuring components for measuring static pressure in the inner channel (6c) of the duct assembly (6) and whose other terminal is in ambient air, preferably at the same altitude as the axis of the inner channel (6c), in order to measure the atmospheric pressure, said measuring components preferably consisting in at least four pressure tappings connected in parallel to the first terminal of the differential pressure sensor (9a).

4 - The relay connection device (3) according to one of claims 1 to 3, characterized in that the duct assembly (6) is provided with at least one vacuum relief valve (10) configured to put the inner channel (6c) of the duct assembly (6) in communication with the outside air when the pressure inside the inner channel (6c) is lower than a defined pressure threshold.

5 - The relay connection device (3) according to one of claims 1 to 4, characterized in that the duct assembly (6) is provided with at least one pressure-relief valve (11) configured to put the inner channel (6c) of the duct assembly (6) in communication with the outside air when the pressure inside the inner channel (6c) is higher than a defined pressure threshold.

6 - The relay connection device (3) according to one of claims 1 to 5, for a relay forced ventilation system (1) whose line sections (7) are cylindrical, characterized in that the duct assembly (6) comprises a middle part (12a) with a square cross section, from a first side of which extends a generally cylindrical first end part (13) whose end is provided with said fixing means (13c), which are configured to provide a leak-proof connection to a line section (7) provided with a relay fan (8), and from a second side of which a second end part (14) extends, for example with widening generally as a truncated cone, to a cylindrical end region (14a) provided with said fixing means (14c), which are configured to provide a leak-proof connection to the end of a line section (7).

7 - A relay connection system (2) for a relay forced ventilation system (1) comprising a line divided into a series of line sections (7) formed by ventilating ducts, two successive line sections (7) being spaced from each other, in which ventilation system a so-called primary fan is provided at the beginning of the first line section (7) of said series, and a so-called relay fan (8), whose speed is adjustable in real time, is provided at the beginning of each line section (7) from the second section of said series, at a distance from the end of the previous line section (7), characterized in that it comprises, for the or each relay fan (8), a relay connection device (3) as defined in one of claims 1 to 6, and an automatic control unit (4) configured to determine, from the measurements took by the measuring means (9), air flow conditions at the end of the upstream line section (7) to which the relay connection device (3) is intended to be connected, and to control in real time, via a speed controller (5), the speed of the relay fan (8) in order to achieve desired flow conditions at the end of the upstream line section (7).

8 - The relay connection system (2) according to claim 7, comprising a relay connection device (3) whose measuring means (9) are means for measuring, on one hand, the static pressure of the air inside the inner channel (6c) of the duct assembly (6) and, on the other hand, the atmospheric pressure outside the duct assembly (6), characterized in that the automatic control unit (4) is configured so that the static pressure at the end of the upstream line section (7), which is upstream of the relay fan (8), is equal to a target value, namely a target value of 0 Pa or slightly higher than 0 Pa.

9 - A forced ventilation system (1) comprising a line divided into a series of line sections (7) formed by ventilating ducts, two successive line sections (7) being spaced from each other, in which ventilation system a so-called primary fan is provided at the beginning of the first line section (7) of said series, and a so-called relay fan (8), whose speed is adjustable in real time, is provided at the beginning of each line section (7) from the second section of said series, at a distance from the end of the previous line section (7), characterized in that it is equipped, between two successive line sections (7), with a relay connection system (2) as defined in one of claims 7 and 8, whose relay connection device (3) is leak-proof connected between said two successive line sections (7).

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Fig.1

141 kW| |Total: 141 kW η η i

57 kW 46 kW Total: 103 kW

ΓΊ ΓΊ- ΓΊ ΓΊ l

Static pressure (Pa) Static pressure (Pa) (m)

-Static pressure in ventilating duct - system without relay

-Static pressure in ventilating duct - system with relay

----Volumetric flow rate in ventilating duct - system without relay ---Volumetric flow rate in ventilating duct - system with relay

141 kW

Fig.2

Total: 141 kW

82 kW 64 kW Total: 146 kW

η n —jzm

Volumetric flow rate (m³/s) Volumetric flow rate (m³/s) (m)

Static pressure in ventilating duct - system without relay Static pressure in ventilating duct - system with relay Volumetric flow rate in ventilating duct - system without relay Volumetric flow rate in ventilating duct - system with relay

2/3

14d

14a

3/3

6b

14c^\d

13c