FR2716562A1 - Soundproofing installation of a machine, such as a turbo combustion turbine machine. - Google Patents

Abstract

An apparatus comprising a sound-proofing hood (18) enclosing a frame (17) rigidly connected to the base (2) of the machine (1), and surrounding said machine, said hood (18) being resiliently supported on the frame (17) via resilient suspension members (19, 20) for vertically and laterally supporting the hood (18) relative to the frame (17). The apparatus is useful for sound-proofing noisy machines such as combustion turbine engines, and turbo-alternator units in particular.

Description

SOUNDPROOFING INSTALLATION OF A MACHINE. SUCH AS
TURBO COMBUSTION TURBINE MACHINE.

 The invention relates to a soundproofing installation for noisy machines in operation, as are rotary machines, of large sizes and powers, such as turbo combustion turbine machines, in particular turbo generator group, turbo pump or turbo compressor, or even as are compressors, blowers, and other aeraulic machines, the operation of which generates great noise pollution for the environment.

 The invention relates to such a soundproofing or acoustic protection installation, which makes it possible simultaneously to provide protection against wind, rain and other atmospheric agents such as snow, hail and winds of sand, as well as '' mechanical protection against the penetration of foreign bodies into the rotating part (s) of the soundproofed machine (s).

 It is known that rotary machines of the aforementioned types are generally installed on a chassis, itself anchored on a foundation solid implanted in the ground of the installation site, and are at least partially surrounded by a soundproofing enclosure and / or mechanical protection.

 The presence of such a casing, also called enclosure or casing, has been made necessary to solve the problems of noise emissions of power machines and dimension increasingly important such as high power industrial turbo alternators, including alternators are driven by combustion turbines, supplied with gas or oil, for the generation of electricity, and in particular for the reinforcement of electrical distribution networks, in order to meet peak energy demands.

 Initially, the acoustic treatment of the body of these machines, in particular the exhaust box or the combustion chambers of the turbine, or the alternator, as well as auxiliary equipment of these machines, was carried out using a cowling made up of a framework and acoustically insulating panels rigidly fixed to the chassis of the machine. Such an embodiment is schematically shown in cross section in Figure 1, where the machine 1 is received on a frame 2 rigidly anchored on the concrete block 3. The acoustic and mechanical protection casing 4, which is rigidly fixed to the chassis 2, comprises a load-bearing framework 5, which supports, on the one hand, vibrating internal equipment, such as cooling elements, for fire protection , pumps, fans, piping and piping of fluid, cables and electrical equipment, walkways and traveling crane, schematically represented and designated as a whole by the reference 6, and, on the other hand, acoustically insulating panels, forming an envelope of soundproofing 7.

 Although this embodiment has the advantages of allowing attachment in the workshop, on the one hand, of the vibrating internal equipment 6 on the framework 5, and, on the other hand of a shroud 4 of reduced size on the chassis 2 of the machine, and to protect the machine from the weather during transport, its structure provides poor acoustic protection performance, due to the solidary transmission of vibrations (represented by wavy lines ending in arrows indicating the direction of propagation) propagating from the machine 1 and vibrating equipment 6 to the walls of the cowling 4 restoring these vibrations in the form of noise (shown diagrammatically by undulations external to the cowling 4 and to the chassis 2).

 For machines from 25 MW to 130 MW, for example, the noise level at one meter outside the cowling 4 of FIG. 1 is around 90 to 95 dbA.

 To make such installations conform to the new noise legislation, it has already been proposed, as shown in FIG. 2, to dissociate the cowling 4 from the chassis 2 of the machine 1 by decoupling its framework 5 from the chassis 2. The base of the framework 5 is then connected to the upper face of the chassis 2 by systems 8 with elastic springs or studs, and seals 9 are mounted between the chassis 2 and the base of the soundproofing casing 7. In addition, lower side skirts 10, having an acoustically insulating structure, have been proposed to improve the acoustic protection in line with the chassis 2.

 Although such installations could have been expected to present not only the same advantages as the installation according to FIG. 1, but also improved acoustic protection performances, installations according to FIG. 2 have practical, not carried out by the manufacturers, because they have the disadvantages of having great instability in the wind, as well as an acoustic protection efficiency which remains very limited, due to the support, by the framework 5, of the vibrating internal equipment. 6, the vibrations of which always propagate in the walls of the cowling 4 which restore them in the form of noise. In addition, the embodiment of FIG. 2 imposes complex interfaces, in particular to ensure sealing at the wall crossings, which are always necessary on this type of machine.

 For these reasons, rather than using the theoretical architecture of FIG. 2, the builders have mostly produced installations according to FIG. 3.

In this installation, the proximity casing 4 ′, essentially ensuring the mechanical protection of the machine 1, is rigidly connected to the chassis 2 by its framework 5 ′, supporting the vibrating equipment 6, and by its envelope 7 ′ of mechanical protection resting on the framework 5 ′, and the soundproofing is essentially ensured by a second cowling 11, enveloping the proximity cowling 4 ′ and the chassis 2 with spacing, and dissociated from the chassis 2 of the machine 1 and of the bed 3 by resting its framework 12, supporting its acoustically insulating envelope 13, on slabs or studs 14 decoupled from the block 3 of the machine by flexible joints 15.

 For a machine in the power range mentioned above, such an installation makes it possible to obtain sound levels at one meter, from 80 to 85 dbA when the installation is mounted inside a building, and around 75 to 80 dbA for outdoor installations.

 The advantages of such an installation are therefore high acoustic protection performances, as well as facilitated maintenance of the machine in outdoor installations, due to the presence of the external casing 11.

 However, the presence of the outer casing 11 is also the cause of numerous drawbacks: when the installation is mounted in a building, it is particularly expensive because of the oversizing of the main building which it requires. Even in the open air, its dimensions are large and the framework 12 of the soundproofing casing 11 is larger to ensure the wind resistance.

The transport of the outer casing 11 must be dissociated from that of the machine 1 with its chassis 2 and its proximity casing 4 ', the mounting of the outer casing 11 is carried out on site and requires more extensive civil works, due slabs 14 and flexible joints 15.

 I1 follows that, in an installation according to FIG. 3, the cost of the means ensuring the protection of the environment with regard to noise pollution coming from the machine represents a significant fraction of the overall costs of the installation and relating to the environment.

 By the invention, it is proposed to remedy the drawbacks of known installations, and the invention aims to propose a soundproofing installation for machines of the aforementioned type, which combines the advantages of known embodiments without having the drawbacks thereof, and which, in general, is better suited than the achievements known to the various desiderata of the practice.

 An object of the invention is to provide a soundproofing installation allowing in particular its workshop mounting on the machine and its chassis, the possibility of fixing vibrating internal equipment, without transmission of vibrations to the acoustically insulating wall, of reduced size. and offering high acoustic protection performance, the installation also ensuring the protection of the machine against bad weather during transport and on site, on which it provides good wind resistance.

 Another object of the invention is to propose such a soundproofing installation making it possible to obtain modular performance as required, and to provide installation interfaces with its environment without rigid connection.

 To this end, the invention proposes an installation for soundproofing a noisy machine in operation, such as a turbo combustion turbine machine, in particular a turbo generator group, mounted on a chassis anchored on a solid mass implanted in the ground of the installation site, and which is characterized in that it comprises a soundproofing bell, which envelops a load-bearing frame, supporting equipment associated with the machine, and rigidly fixed to the chassis by surrounding the machine, so that the bell envelopes at least the top and the sides of the machine, the bell being resiliently mounted on the frame by elastic means of suspension and vertical support of the bell with respect to the frame.

 Thus, the bell forms an acoustic protection envelope, which is close to sources of noise, while being dissociated from its frame or load-bearing framework, which, due to its rigid attachment to the chassis, fulfills its essential functions of ensuring the mechanical resistance to wind, and to support internal vibrating equipment, without transmitting their vibrations to the soundproofing bell, due to the support of the acoustic protection envelope provided by means of elastic support and suspension means.

 Advantageously, the soundproofing bell is also mounted elastically on the frame by elastic means for lateral suspension of the bell with respect to the frame, said elastic lateral suspension means cooperating with mechanical stops positively limiting the relative lateral displacements of the bell and of the frame, after a determined lateral course of suspension of said elastic means.

 The installation may include elastic suspension means participating in the vertical and lateral suspensions. Indeed, the transverse guiding with damping of the bell on the frame can be ensured by elastic devices stressed in shearing, and simultaneously fulfilling, by compression or tensile stress, the function of vertical support and suspension.

 Preferably, however, the elastic suspension means and vertical support are distinct from the elastic lateral suspension means with stops, although both may include springs, for example steel coil springs, absorbing the medium and low frequencies, and / or elements made of viscoelastic material, for example in the form of studs or layers mounted in a joint, these materials absorbing high frequencies. Of course, any combination of springs and viscoelastic elements can be envisaged for the production of elastic suspension means, taking into account the forces and frequencies involved.

 In an advantageous embodiment, the bell comprises at least one belt frame connected to the frame by at least said elastic suspension and vertical support means, and removably supporting, on the one hand, a roof covering the frame and the machine, and, on the other hand, at least one side facade, the roof and each facade consisting of at least one acoustically insulating wall.

 The bell may include several belt frames, spaced in a vertical direction, and each connected to the frame by means of elastic vertical suspension means, constituting anti-vibration supports, also mounted at different height levels. However, preferably, the bell comprises a single belt frame, substantially at the upper level of the frame, and connected to the latter by the set of anti-vibration supports ensuring the vertical elastic suspension.

 In this case, it is advantageous for at least part of the elastic lateral suspension means to be mounted between at least one front of the soundproofing bell and the frame. Preferably, these elastic lateral suspension means are distributed at different height levels, to more effectively limit the relative lateral deflections of the bell and of the frame.

The acoustically insulating material used to make the walls of the roof and of the facades of the bell can comprise, in a well known manner, synthetic foam or cellular materials with open cells, but, advantageously, at least one acoustically insulating wall, and preferably each of them comprises an assembly of soundproofing panels, each of which comprises, from the outside to the inside of the wall:
- a full external sheet, on the internal face of which are fixed stiffeners parallel to each other, spaced by a determined pitch, and transverse to the wall,
- at least one layer of viscoelastic material bonded to the internal face of the external sheet, between the stiffeners,
- a complex of at least two layers of fibrous mineral material, of different thicknesses and / or densities, extending between the stiffeners, and of which a layer of thinner thickness and / or density is doubled inwards by a layer of greater thickness and / or density, the complex preferably being protected inwards by a veil of glass fibers, and
- A perforated internal sheet of mechanical protection of said complex of fibrous mineral material, and retained by stiffeners.

 Such a panel structure is particularly suitable in the areas of the bell facing medium or low noise parts of the machine (s).

On the other hand, facing the noisiest parts, the sound insulation panel further comprises, from the outside towards the inside of the wall, and between the viscoelastic material and the layer of thinner thickness and / or density of the complex of fibrous mineral matter:
- a lining sheet, fixed to stiffeners and ensuring permanent compression of the viscoelastic material, and
an additional layer of the complex of fibrous mineral material, said additional layer being of greater thickness and / or density than the layer of the complex to which it is adjacent.

 Advantageously, to ensure the continuity of the sound insulation of the right of the chassis, the installation according to the invention further comprises at least one lateral soundproof skirt, removably fixing, on the one hand, to the base of the bell to which it is suspended, and, on the other hand, on the solid mass by means of elastic adjustable support supports, along at least one side of the chassis, each skirt having a wall structure acoustically insulating, advantageously analogous to that of the bell, each skirt being shaped so as to delimit simultaneously, laterally to the chassis, a clearance for housing equipment associated with the machine.

 In this case, it is advantageous for each lateral skirt to form, by its base connected to the solid block, an acoustic insulation interface in cooperation with an acoustically insulating joint, which extends over a sufficient height, parallel to the base of the skirt. , inside the latter from which it is separated by a small distance, so as to define between the acoustically insulating joint and the base of the skirt, a baffle of sound absorption.

 In addition, the upper part of the skirt can be advantageously fitted as a gangway by the addition of checker plate or gratings.

 Finally, to maintain a good air tightness between the bell and the frame, despite their relative vertical movements allowed by the elastic means of vertical suspension, the base of the bell is connected to the top of the frame by at least one gasket. air tightness, mounted sliding substantially vertically along the internal face of the base of the bell.

Other characteristics and advantages of the invention will emerge from the description given below, without implied limitation, of an exemplary embodiment described with reference to the appended drawings in which:
- Figures 1 to 3 show schematically, in cross section, three embodiments of the prior art;
- Figure 4 is a view similar to Figures 1 to 3, of an embodiment according to the invention;
- Figure 5 is a partial view of Figure 4 schematically the structure and the method of connection of the soundproofing bell to the frame;
- Figure 6 is a schematic cross-sectional view of an example of an acoustically insulating wall of the bell;
- Figure 7 is a partial view similar to Figure 6 of another example of an acoustically insulating wall; and
- Figure 8 is also a partial view of Figure 4, showing a side skirt and its cooperation with the base of the bell, the frame and the solid.

 In FIG. 4, as in FIGS. 1 to 3, a machine is schematically represented in 1, for example a turbo generator group driven by a gas turbine, mounted on a rigid metal frame 2 and anchored on a concrete block 3 .

 As in the embodiments of FIGS. 1 and 2, a proximity cowling 16, simultaneously forming the soundproofing and mechanical protection cowling of the machine 1, envelops the sides and the top of this machine 1 while being mounted on its chassis 2.

 The cowling 16 essentially comprises, on the one hand, a rigid frame 17, or supporting framework, rigidly fixed on the chassis 2, and surrounding the machine 1, and, on the other hand, a soundproofing bell 18, constituting the acoustic protection enclosure proper, which envelops the frame 17, and therefore also the top and sides of the machine 1.

 The frame 17 is a mechanically welded metal frame, conventionally comprising vertical uprights and horizontal crosspieces, the upper crosspieces of which support the vibrating internal equipment 6 of the machine 1, and which provides the mechanical resistance to the wind of the installation as well as the support of the soundproofing bell 18, as described below.

 The bell 18 is elastically linked to the frame 17, on the one hand, by anti-vibration assemblies 19, ensuring the vertical support with elastic suspension of the bell 18 on the frame 17, and, on the other hand, by sets of suspensions lateral ion 20, allowing the load to be picked up in the wind. The latter include elastic lateral suspension means, such as viscoelastic elastomer studs, combined with mechanical stops limiting, by their mutual supports, the lateral deflections of the bell 18 relative to the frame 17, after a determined lateral stroke of elastic suspension, less than the maximum admissible stroke of extension and / or compression, or even of shearing, of viscoelastic studs, the mechanical stops being, for example, constituted by extensions of the rigid supports between which the studs are mounted viscoelastic, reason why the lateral suspension assemblies 20 are called "elastic stops" in the remainder of this specification.

 In FIG. 4, these elastic stops 20 are mounted at two different height levels on the opposite sides of the cowling 16, between the frame 17 and the bell 18, while the anti-vibration supports 19 are mounted only at the upper part of the frame 17, on which the bell 18 is in elastic support, as shown in Figure 4, or to which the bell 18 is elastically suspended, as shown in Figure 5 and described below, thanks to their elastic suspension means vertical, such as springs, preferably combined with elements of viscoelastic elastomer.

 Thanks to the absence of rigid connection between the bell 18 and the frame 17, the vibrations generated by the machine 1 and its internal equipment 6 propagate to the frame 17 and to the frame 2, without being transmitted to the bell 18. The latter , although close to the sources of noise, is essentially produced in the form of an acoustically insulating wall against the noise transmitted by air from the machine 1, the internal equipment 6 and the frame 17. Examples of embodiment of this acoustically insulating wall are described below with reference to Figures 6 and 7.

 In the event of an exceptional lateral or transverse overload, in extreme wind, earthquake or for certain maintenance operations, for example, the mechanical stops of the elastic stops 20 ensure the stability of the assembly; but, in this case, the antivibration insulation between the bell 18 and the frame 17 is no longer effective.

 To ensure the continuity of the sound protection on the right of the sides of the chassis 2 of the machine 1, side soundproofing skirts 21, each having an L-shaped cross section, extend along the sides of the chassis 2, being, d 'On the one hand, removably suspended from the base of the corresponding side of the bell 18, and, on the other hand, fixed to the block 3 in a removable manner by elastic support supports 22, preferably adjustable.

While the machine 1, its chassis 2, the frame 17 and the vibrating internal equipment 6 of the machine, and also the bell 18 (except, possibly, its removable upper part or roof 29, as described below with reference to the FIG. 5, when the bell 18 is of great height) are transported in one piece, after assembly in the workshop, on the installation site by means of the lateral lifting studs 23 of the chassis 2, the skirts 21 are, on the contrary, reported on the installation site. Each skirt 21 has an acoustically insulating wall structure, similar to that of the bell 18, and its cross-sectional shape
L allows it to delimit, on the corresponding side of the chassis 2, a lateral clearance 24 housing equipment 25 associated with the machine 1, such as conduits, pipes, cable bundles, electrical cabinets, etc. In addition, the horizontal upper part 26 of the skirt 21 is arranged as a gangway and supports for this purpose a coating of tear sheet or grating 27, to facilitate the access of maintenance personnel to the inspection hatches, doors and other openings arranged. for this purpose in bell 18.

The structure and mounting of each skirt 21, as well as the acoustic interface at its base and the airtightness interface at the base of the bell 18 are shown in more detail in FIG. 8.

 In the embodiment of FIG. 5, the bell 18 comprises, opposite the upper part of the frame 17, a belt frame 28, of substantially U-shaped or n-shaped profile, on which the peripheral edge rests in support lower part of the upper part or roof 29 of the bell 18, which roof 19 covers the frame 7 and the machine 1 and is removably fixed, by bolting 30, to the upper wing of the profile frame 28. To this frame 28 are suspended from the side and vertical facades 31 of the bell 18, which facades 31 are removably fixed by bolting 32 to the lower wing of the profile frame 28. The roof 19 and the facades 31 are thus elements which can be dismantled independently others.

 The frame 28, the profile of which is open towards the frame 17, is closed, in locations distributed around its periphery, by vertical plates 33 each supporting a horizontal console 34 towards the inside of the bell 18. This console 34 is pierced a through hole for a vertical threaded stud 35, fixed in an axially adjusted position on the console 34 by a nut-against-nut assembly 36, 37, the stud 35 also passing through a hole in the base of a support piece U 38 secured under the upper I-beam 39 of the frame 17, as well as a helical compression spring 40, of steel, resting at its lower end on the base of the support piece 38 and loaded at its upper end by two plates rigid support 41, between which a plate 42 of viscoelastic silicone is compressed, and which are retained on the stud 35 by a nut 43.

 In this way, the spring 40 and the viscoelastic plate 42 are loaded in compression by the elastic suspension of the profile 28, and therefore of the entire bell 18, to the frame 17. In this example, the spring assembly 40 and viscoelastic plate 42 described above, and interposed between the frame 17 and the frame 28 of the bell 18, corresponds to the antivibration support 19 of FIG. 4. As a variant, these elastic means of suspension and vertical support can comprise two springs such as 40 , or more, mounted in parallel and each around a stud such as 35, in which case the viscoelastic plate 42 and the plates 41 which compress it can be applied simultaneously against the upper ends of all the springs bearing on the same piece of support 38.

 In such an arrangement, the spring (s) 40 absorb (s) the low and medium frequencies, while the viscoelastic plate 42, or several similar plates possibly stacked, absorb (s) the high frequencies.

Thus, in the part of the bell 18 enveloping the alternator, the springs 40 are particularly effective, while in the part of bell 18 enveloping the turbine, the elastomer plates 42 are more effective than the springs 40, which can possibly be omitted.

 Opposite the base of the profile 28, on the external face of the bell 18, a sheet 44, forming a seal protecting against the flow of rainwater, extends from the roof 29 to the facade 31 and is fixed on the profile 28 by a bolt 45 applying simultaneously against the base of the profile 28 a plate of viscoelastic material 46 forming an acoustic protection joint in line with the profile 28.

 The roof 29 and each facade 31 are produced in the form of an acoustically insulating wall, constituted by the assembly of acoustically insulating panels, as shown in FIGS. 6 and 7.

 In FIG. 6, the acoustically insulating wall, used to constitute the one-piece bell 18 facing the noisiest parts of the machine, is made up, from the outside towards the inside of the bell, of a full external sheet 47 , on the internal face of which are fixed, by welding or gluing, the external wings 49 of stiffening members 48, in Z-folded profile, which are parallel to each other and transverse to the wall, and spaced apart by a pitch determined, function of the natural frequency of the wall, therefore of the acoustic attenuation to be obtained, these members 48 being vertical in the wall of the facades 31, then a layer 50 of a viscoelastic material bonded against the internal face of the external sheet 47, between the members 48, then a prestressing sheet 51, or preformed lining sheet, ensuring permanent and uniform compression of the viscoelastic material of the layer 50, and which is fixed by welding at 52 to the them members 48 between which it extends, this prestressing sheet 51 making it possible to absorb residual vibrations, to avoid creep over time of the viscoelastic material 50, and to increase the mass of the assembly, then a complex 53 of fibrous mineral material, consisting of an outer layer 54 thick of high density mineral wool (greater than 100 kg / m3), of a thinner central layer 55 of low density mineral wool (less than 50 kg / m3 ), and of an internal thick layer 56 of high density mineral wool, and finally of an internal perforated sheet 57, with, possibly, interposition of a veil of fiberglass for protecting the complex 53, between the latter and the perforated sheet 57. The perforated sheet 57, retained inside the internal wings 58 of the frames 48 and angles 59 welded to the latter, provides mechanical protection of the complex 53 of mineral wool and has a perforation rate d sealed to optimize sound absorption inside the wall. At its upper and lower edges, each front wall is closed by U-shaped sheets overlapping the structure shown in Figure 6, and allowing in particular the removable fixing of the wall to the frame 28 of the bell 18 by the bolting 32 of the figure 5.

 The acoustically insulating wall structure of FIG. 7 is suitable for constituting the bell 18 in its parts opposite the less noisy areas of the machine. To this end, the wall of FIG. 7 differs from the wall of FIG. 6 only by the fact that it does not include a prestressing sheet 51 or an external layer 54 of mineral wool, so that its material complex fibrous mineral consists only of the layer 55 of small thickness and density and of the internal layer 56 of large thickness and density. For this reason, the elements of Figure 7 similar to those of Figure 6 are identified by the same references.

 FIG. 8 shows that the airtightness between the base of each lateral facade 31 of the bell 18 and the upper face of the chassis 2 is ensured by a seal 60, in the form of a plate mounted slidably or sliding substantially vertically, along the internal face of the base of the facade 31, between the latter and the base of the frame 17, under elastic stops 20 of the lower level. The seal 60 is supported by its lower edge in a guide 61 welded or bolted to the frame 2 and retained by its upper edge between the facade 31 and a wing of a Z-profile 62, bolted at 63 by its other wing against the U-shaped profile 64 which closes the base of the facade 31, the maximum stroke of the seal 60 in the Z-shaped profile 62 corresponding to the maximum vertical displacement of the bell 18 relative to the frame 17 and to the frame 2, under the action anti-vibration supports 19 for vertical suspension.

 This FIG. 8 also shows that, by the internal end of its upper part 26, the skirt 21, consisting for example of an acoustically insulating wall as shown in FIG. 6 or 7, is suspended from the base of the facade 31 , thanks to an extension of an external sheet 65 of the skirt 21 and a sheet 66 folded at right angles around an internal edge profile 67 of the skirt 21, these sheets 65, 66 being secured and bolted at 68 on an angle secured under the profile 64 of the base of the facade 31.

A flap 70, bolted to the external face of the base of the facade 31, and resting against the external sheet 65 of the skirt 21 by an elastomer seal, ensures the protection of this removable junction against dust, sand and water runoff.

 FIG. 8 also shows that the vertical part 71 of the skirt 21 is fixed to its horizontal part 26 by a closed angle profile 72, and that the base of this vertical part 71 is in abutment against an edge 73, continuous over all the periphery of the cowling and anchored projecting from the block 3, by support supports 22 made of elastic studs adjustable in height and screwed under a closed profile of the lower edge 74 of the skirt 21, to cooperate with feet 75, adjustable height, mounted on a base plate 76 welded to the edge 73. A flap 77 with compressible gasket pressing against the plate 76, outside the feet 75, is screwed onto the external face of the edge profile 74, and another flap 78, made of sheet metal, is screwed against the external sheet metal 65 of the skirt 21 and extends outwards and downwards as far as under the plate 76, to protect this junction against atmospheric agents. Finally, a sound absorption baffle is produced at the base of the skirt 21, between the latter and an acoustically insulating joint 79, screwed by its base to the plate 76 in a position in which it extends vertically, substantially up to halfway up the skirt 21 and parallel to the vertical part 71 thereof, inside this vertical part, the joint of which is separated by a small distance. This joint 79 is constituted like the acoustically insulating wall of FIG. 6 or of FIG. 7, but it is mounted so that its full sheet is placed towards the frame 2, and its perforated sheet towards the outside, that is to say that is to say facing the perforated internal sheet of the vertical part 71 of the skirt 21. An effective acoustic insulation interface is thus produced between the skirt 21 and the block 3.

 The casing produced according to FIGS. 4 to 8 simultaneously fulfills the same functions as the casing 4 'of mechanical protection and that the acoustic protection casing 11 of the embodiment of FIG. 3, while providing the same performance, but being d '' a much more economical cost, because of its reduced size, and the considerable reduction of the work required on site, in particular of assembly and civil engineering.

Claims (13)

 1. Soundproofing installation of a noisy machine (1) in operation, such as a rotary machine, in particular of the turbo type, combustion turbine machine, or other aeraulic machine, mounted on a chassis (2) anchored on a solid (3) located in the ground of the installation site, characterized in that it comprises a soundproofing bell (18), which envelops a load-bearing framework (17), supporting equipment (6) associated with the machine ( 1), and rigidly fixed to the frame (2) surrounding the machine (1), so that the bell (18) envelops at least the top and the sides of the machine (1), the bell (18) being resiliently mounted on the frame (17) by elastic means (19) for suspension and vertical support of the bell (18) relative to the frame (17).  2. Soundproofing installation according to claim 1, characterized in that the soundproofing bell (18) is also resiliently mounted on the frame (17) by means (20) of elastic lateral suspension of the bell (18) by relative to the frame (17), said elastic lateral suspension means (20) cooperating with mechanical stops positively limiting the relative lateral displacements of the bell (18) and of the frame (17), after a determined lateral suspension suspension stroke elastic means (20).  3. Soundproofing installation according to claim 2, characterized in that it comprises elastic suspension means (19, 20) participating in the vertical and lateral suspensions.  4. Soundproofing installation according to any one of claims 1 to 3, characterized in that the elastic suspension means comprise springs (40) and / or elements (42) of viscoelastic elastomeric material.  5. Soundproofing installation according to any one of claims 1 to 4, characterized in that the bell (18) comprises at least one frame (28) of belt connected to the frame (17) by at least said elastic means ( 40, 42) of suspension and vertical support, and removably supporting, on the one hand, a roof (29) covering the frame (17) and the machine (1), and, on the other hand, at least a side facade (31), the roof (29) and each facade (31) consisting of at least one acoustically insulating wall.  6. Soundproofing installation according to claim 5, as attached to claim 2, characterized in that at least part of said elastic means (20) for lateral suspension is mounted between at least one front (31) of the bell soundproofing (18) and the frame (17).  7. Soundproofing installation according to any one of claims 5 and 6, characterized in that at least one acoustically insulating wall comprises an assembly of soundproofing panels, each of which comprises, from the outside to the inside of Wall:  - a full external sheet (47), on the internal face of which are fixed stiffeners (48) parallel to each other, spaced apart by a determined pitch, and transverse to the wall,  - at least one layer (50) of viscoelastic material bonded to the internal face of the external sheet (47), between the stiffeners (48),  - A complex (53) of at least two layers (55, 56) of fibrous mineral material, of different thicknesses and / or densities, extending between the stiffeners, and including a layer (55) of thinner thickness and / or density is doubled inwards by a layer (56) of greater thickness and / or density, the complex (53) being preferably protected inwards by a veil of glass fibers, and  - A perforated internal sheet (57) of mechanical protection of said complex (53) of fibrous mineral material, and retained by stiffeners (48).  8. Soundproofing installation according to claim 7, characterized in that at least one soundproofing panel further comprises, from the outside towards the inside of the wall, and between the viscoelastic material (50) and the layer (55) of smaller thickness and / or density of the complex (53) of fibrous mineral material:  a lining sheet (51), fixed to stiffeners (48) and ensuring permanent compression of the viscoelastic material (50), and  - An additional layer (54) of the complex (53) of fibrous mineral material, said additional layer (54) being of greater thickness and / or density than the layer (55) of the complex (53) to which it is adjacent.  9. Soundproofing installation according to any one of claims 5 to 8, characterized in that at least one belt frame (28) of the bell (18) is resiliently suspended from and / or resting on the frame ( 17) by elastic suspension assemblies (19) each comprising at least one helical spring (40), preferably associated with at least one layer of viscoelastic elastomer (42).  10. Soundproofing installation according to any one of claims 1 to 9, characterized in that it further comprises at least one skirt (21) lateral soundproofing, removably fixing, on the one hand, to the base of the bell (18) to which it is suspended, and, on the other hand, on the block (3) by means of elastic supports (22) of adjustable support, along at least one side of the chassis (2), each skirt (21) having an acoustically insulating wall structure, so as to ensure the continuity of the sound insulation to the right of the chassis (2), delimiting laterally to the latter a clearance (24) for the housing of equipment associated with the machine (1).  11. Soundproofing installation as claimed in claim 10, characterized in that each side skirt (21) forms, by its base (71) connected to the solid block (2), an acoustic insulation interface in cooperation with a seal (79 ) acoustically insulating, which extends over a sufficient height, parallel to the base (71) of the skirt (21), inside the latter from which it is separated by a small distance, so as to define between the acoustically insulating joint (79) and the base of the skirt (21), a sound absorption baffle.  12. Soundproofing installation according to one of claims 10 and 11, characterized in that the upper part (26) of the skirt (21) is arranged as a gangway (27) by the addition of tear sheet or grating.  13. Soundproofing installation according to any one of claims 1 to 12, characterized in that the base of the bell (18) is connected to the top of the frame (2) by at least one seal (60) the air, mounted sliding substantially vertically along the internal face of the base of the bell (18).