EP0404801B1 - Silencer for a gas flow - Google Patents

Silencer for a gas flow Download PDF

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Publication number
EP0404801B1
EP0404801B1 EP89903496A EP89903496A EP0404801B1 EP 0404801 B1 EP0404801 B1 EP 0404801B1 EP 89903496 A EP89903496 A EP 89903496A EP 89903496 A EP89903496 A EP 89903496A EP 0404801 B1 EP0404801 B1 EP 0404801B1
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EP
European Patent Office
Prior art keywords
silencer
casing
packing
section
fluid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP89903496A
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German (de)
French (fr)
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EP0404801A1 (en
Inventor
François Noel GRAS
Claude Charles Henri Friou
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Bertin Technologies SAS
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Bertin et Cie SA
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Priority to AT89903496T priority Critical patent/ATE97463T1/en
Publication of EP0404801A1 publication Critical patent/EP0404801A1/en
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Publication of EP0404801B1 publication Critical patent/EP0404801B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/02—De-icing means for engines having icing phenomena
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
    • F01N1/082—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling the gases passing through porous members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2310/00—Selection of sound absorbing or insulating material
    • F01N2310/04—Metallic wool, e.g. steel wool, copper wool or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2310/00—Selection of sound absorbing or insulating material
    • F01N2310/14—Wire mesh fabric, woven glass cloth or the like

Definitions

  • the present invention relates to an injector silencer or ejector for the expansion of a gaseous fluid and, more particularly, to a blowing device equipped with a set of such silencers.
  • the expansion of a fluid such as a gas is an operation which generates acoustic emissions which it is important to eliminate or at least reduce to a level considered to be tolerable, so as to mitigate the effects harmful sound and / or mechanical emissions. This is particularly the case when it is desired to relax gases or vapors to the atmosphere, empty pressurized gas tanks, relax hot air to defrost air intake filters for gas turbines or gas compressors, for example.
  • the gas or vapor injectors or ejectors used in such applications include holes or openings through which the gas to be expanded enters an environment at atmospheric pressure.
  • the acoustic emissions are reduced by externally covering the part of the injector or ejector which has these lights with a piece of sintered metal, or of sintered plastic.
  • This arrangement is not without drawbacks. Indeed, in addition to a temperature resistance of the sintered parts which may be insufficient and an increase in the overall size due to the external position of the sintered part, clogging of the sintered part with materials entrained by the gas to be relaxed. is to be feared, due to the low porosity of the sintered part.
  • a silent expansion of the gas is ensured by arranging, externally, on an exhaust pipe, an expansion chamber, a throttling member or other exhaust means, a more or less extensive and thick annular lining, this annular lining being able to be made of various materials such as, for example, a metallic wool or fabric, a glass wool or synthetic fibers, asbestos free, metal shavings or wood, metal fabrics or knits. Examples of such silent expansion devices are described in French patents No. 1,561,483, 2,250,379, 2,372,373 and 2,498,681.
  • the object of the present invention is to produce a injector or ejector muffler for the expansion of a gaseous fluid which does not have the drawback or blockage drawbacks of the prior art mufflers.
  • the present invention also aims to achieve such a silencer composed of standard, simple and interchangeable members, so as to lend itself to an inexpensive embodiment.
  • the present invention also aims to achieve such a silencer which is in the form of a removable cartridge easy to install or replace in a device equipped with such silencers.
  • an injector silencer or ejector for the expansion of a gaseous fluid comprising a member for mounting the silencer on a source of fluid under subsonic flow pressure and a casing having a first end covered by a throttle piece pierced with holes of cumulative surface (S2) reduced compared to the section (S1) of an inlet end piece of the silencer and carried by this member so as to communicate internally with the fluid source, this envelope having a second end distant from the first and breakthrough of lights for the passage into an external medium of the fluid admitted into the envelope, a lining completely filling the interior space of the envelope, from the perforated part to the second end of this envelope, with internal covering openings in this second end of the casing, characterized in that the ratio of the cumulative surface (S2) of the holes in the throttle piece (8) to that of the inlet section (S1) is such that the flow through this part (8) is noted at sonic speed and in that the ratio of the cumulative section
  • the lining is constituted by a knitted wire, formed in a tight roll.
  • this lining takes the form of a metallic fabric in a tight roll or even of a metallic foam with open cells.
  • the present invention also provides a device for blowing a gaseous fluid over an extended surface, equipped with a set of silencers according to the invention, characterized in that it comprises several parallel ramps mounted on a common collector itself connected at a source of a gaseous fluid, each ramp carrying several injector silencers or fluid ejectors regularly distributed and oriented so that the gaseous fluid is uniformly distributed by all of the silencers over the entire surface to be treated by blowing.
  • blowing device shown in Figure 1 is likely to be used in many applications as will be recognized by those skilled in the art, such as defrosting the air inlet of a gas turbine or compressor, purging or expanding tanks of compressed air or vapors under pressure, blowing steam on a surface to be cleaned for example and, more generally, in the silent decompression of all gases or vapors at all temperatures.
  • the blowing device shown in FIG. 1 is installed, by way of nonlimiting example of application of the invention, opposite the inlet section 1 of a gas turbine or compressor (not shown ).
  • This inlet section is usually fitted with one or more filters which can, in wet and cold weather, become clogged with ice, thereby cutting off the air intake, or at least reducing it. In this hypothesis, it is then necessary to unblock the air inlet by melting the ice, for example by means of a blowing of hot air into the filter.
  • the device of FIG. 1 comprises a source of pressurized hot air (not shown), supplying along the arrow F a pipe 2 provided with an adjustment valve 3.
  • the pipe 2 in turn feeds a manifold tubular 4, for example horizontal, on which are regularly and parallel distributed, vertical ramps 5, 5 ', etc ... which each carry several silent injectors and air regulators 6, 6', etc ... according to invention, distributed regularly and oriented so as to blow hot air over the entire extent of the air intake section 1 of the turbine, to thus ensure uniform defrosting of the filter placed in this air inlet .
  • the mesh of the silencers can advantageously be between 300 x 300 mm and 1000 x 1000 mm, depending on the dimensions thereof.
  • the silencers 6, 6 ′ which simultaneously act as injectors, achieve sonic silent expansion of the hot gases.
  • the silencers according to the invention a good distribution of the hot air is obtained in the air inlet section 1 and it is possible to use between the valve 3 and these silencers, small diameter pipes, therefore less costly, in which the pressure can be adjusted, by dimensioning the passage section of the throttle piece, to a value between 5 and 15 bars, or more if the source of hot air allows.
  • the first end of this tubular casing is mounted in a mounting member 10 taking the form a tip for fixing the silencer to a source of gas fluid supply (not shown in Figure 2).
  • the end piece 10 is fixed by screwing or welding to the source to ensure communication between the source and the casing 7 of the silencer through the throttle piece 8. This rests on an annular shoulder 11 formed in the bore 12 of this end piece which receives the adjacent end of the tubular casing 7.
  • the end piece 10 can be a commercial end-piece produced by turning or forging and has a thread for fixing the casing 7. The latter could also be soldered on this tip.
  • the other end of the envelope is pierced with lights 13, 13 ', 13'', ... regularly distributed around the envelope in the vicinity of the disc 9.
  • the disc 9, fixed to the envelope 7 by welding or screwing, can itself be pierced of lights.
  • the cumulative surface of all these lights is preferably in a ratio 5 to 40 with the open surface of the throttle piece 8.
  • the throttle piece takes the form of a circular plate pierced with holes of the same diameter and regularly distributed.
  • This plate can be produced by punching a sheet of perforated sheet metal, or by drilling. Its thickness is a function of the pressure in the ramp 5 and its diameter.
  • this plate 8 An essential characteristic of this plate 8 is that the cumulative S2 of the sections of these holes must be reduced relative to the inlet section S1 of the nozzle 10, so as to ensure a sonic flow of gas at the inlet in the envelope 7, while maintaining the same mass flow and a subsonic flow of said gas in the pipes upstream of the device according to the invention, for a purpose which will appear later.
  • An essential characteristic of the silencer according to the invention, linked to the presence of shock waves downstream of the plate 8, is that the tubular casing 7 is completely filled, from the perforated plate 8 to the disc 9, a lining 14 made of fine metal wire (inside 1 mm), of the knitted or tightly wound fabric type.
  • the length L of the lining must not be less than 20 mm for an envelope 7 of small diameter and should be between 20 and 300 mm, if possible, whatever the diameter of the envelope.
  • the porosity of such a knitted fabric is greater than 80%.
  • the operation of the silencer according to the invention is then established as follows.
  • the gas which enters the envelope 7 undergoes a sonic expansion at the level of the plate 8 and the metal wire lining 14 then reduces the noise of the trigger by stabilizing and splitting the shock waves and by homogenizing the flow. Thanks to the fact that it internally covers the lights 13, 13 ', 13'', ..., the lining also reduces the emission towards the outside of noises generated by the passage of gas through these lights.
  • the presence of a sonic flow prevents any rise of noise upstream, therefore in the rest of the installation.
  • the increase in pressure in the installation due to the throttle piece, has the effect, for the same mass flow, of reducing the speed of the fluid and therefore the noise in the supply. Downstream of the plate 8, the flow takes place at low speed and at low pressure and the tubular casing 7 is therefore not subjected to high internal pressures.
  • a metallic foam with open ones of porosity greater than 50% should exhibit good mechanical resistance to the pressure developed by the gas entering through the holes in the perforated plate 8, so as not to be forced back towards the other end of the envelope and to continue to fill it completely.
  • tests have shown that the metallic knitted fabric referenced G 270, stainless steel 304 L, embossed, double and tightly wound, in the catalogs of the GANTOIS Company, gives excellent results.
  • the silencer according to the invention lends itself to embodiments in all diameters at low costs using commercial organs, end pieces, tubes, etc. It can be entirely metallic in steel or stainless steel and withstands high pressures, the upstream pressure being applied only to part 8. It can also withstand high temperatures by making it in refractory stainless steel, including the metallic knitting. One can, by providing a fixing by screwing, give it the character of a removable and interchangeable cartridge.
  • the sonic silencer according to the invention also forms a screen for the upward noise rise in the supply piping. Thanks to the invention, and because of the low speeds of the fluid in the supply, it is possible to envisage replacing the control valve by an all or nothing less expensive valve, or by several valves in parallel if several operating flow rates are required.
  • the characteristics of porosity, cohesion and elasticity of the lining combine to ensure effective unclogging of the latter under the effect of the agitation developed by the shock waves which propagate in the silencer according to l 'invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Exhaust Silencers (AREA)
  • Pipe Accessories (AREA)

Abstract

The silencer comprises a tubular envelope (7) supported by an end-piece (10) for fixture to a gas supply source in which the pressure is to be reduced. A perforated plate (8) and a disc (9) close off the ends of the envelope which is drilled with escape apertures (13, 13', 13''...) in the region of the disc (9). According to the invention, the gas flows at sonic speed through the plate (8) to enter the envelope (7) which is completely filled with a packing (14) consisting of a tightly-wound roll of wire mesh. Said packing absorbs the shock waves developed by the supersonic flow of the gas in the packing. The latter maintains a subsonic flow with a low noise level upstream of the silencer. Application to the treatment of a surface by blasting of a gas flow.

Description

La présente invention est relative à un silencieux injecteur ou éjecteur pour la détente d'un fluide gazeux et, plus particulièrement, à un dispositif de soufflage équipé d'un ensemble de tels silencieux.The present invention relates to an injector silencer or ejector for the expansion of a gaseous fluid and, more particularly, to a blowing device equipped with a set of such silencers.

Dans de nombreuses applications industrielles, la détente d'un fluide tel qu'un gaz est une opération qui engendre des émissions acoustiques qu'il importe de supprimer ou tout au moins de réduire à un niveau considéré comme tolérable, de manière à atténuer les effets sonores et/ou mécaniques nuisibles de ces émissions. C'est le cas notamment lorsqu'on souhaite détendre des gaz ou des vapeurs à l'atmosphère, vidanger des réservoirs de gaz sous pression, détendre de l'air chaud pour dégivrer des filtres d'entrée d'air de turbines à gaz ou de compresseurs de gaz, par exemple.In many industrial applications, the expansion of a fluid such as a gas is an operation which generates acoustic emissions which it is important to eliminate or at least reduce to a level considered to be tolerable, so as to mitigate the effects harmful sound and / or mechanical emissions. This is particularly the case when it is desired to relax gases or vapors to the atmosphere, empty pressurized gas tanks, relax hot air to defrost air intake filters for gas turbines or gas compressors, for example.

Les injecteurs ou éjecteurs de gaz ou de vapeur utilisés dans de telles applications comportent des trous ou lumières par lesquels le gaz à détendre entre dans un milieu à la pression atmosphérique. Suivant une première disposition connue, on réduit les émissions acoustiques en recouvrant extérieurement la partie de l'injecteur ou éjecteur qui présente ces lumières avec une pièce en métal fritté, ou en matière plastique frittée. Cette disposition n'est pas sans inconvénient. En effet, outre une tenue en température des pièces frittées qui peut être insuffisante et un accroissement de l'encombrement d'ensemble du à la position extérieure de la pièce frittée, un colmatage de la pièce frittée par des matériaux entraînés par le gaz a détendre est à craindre, du fait de la faible porosité de la pièce frittée.The gas or vapor injectors or ejectors used in such applications include holes or openings through which the gas to be expanded enters an environment at atmospheric pressure. According to a first known arrangement, the acoustic emissions are reduced by externally covering the part of the injector or ejector which has these lights with a piece of sintered metal, or of sintered plastic. This arrangement is not without drawbacks. Indeed, in addition to a temperature resistance of the sintered parts which may be insufficient and an increase in the overall size due to the external position of the sintered part, clogging of the sintered part with materials entrained by the gas to be relaxed. is to be feared, due to the low porosity of the sintered part.

Suivant une autre disposition connue, on assure une détente silencieuse du gaz en disposant, extérieurement, sur un pot d'échappement, une chambre de détente, un organe d'étranglement ou autre moyen d'échappement, une garniture annulaire plus ou moins étendue et épaisse, cette garniture annulaire pouvant être réalisée en divers matériaux tels que, par exemple, une laine ou toile métallique, une laine de verre ou de libres synthétiques, des libres d'amiante, des copeaux métalliques ou de bois, des tissus ou tricots métalliques. Des exemples de tels dispositifs de détente silencieuse sont décrits aux brevets français No. 1.561.483, 2.250.379, 2.372.373 et 2.498.681. On remarquera que les garnitures utilisées dans ces exemples accroissent, du fait de leur forme annulaire, l'encombrement des dispositifs équipés de ces garnitures, à volume égal de garniture acoustiquement absorbante utilisée. On connaît encore de la demande de brevet anglais No. 2.084.245 un silencieux conforme au préambule de la revendication 1 annexée à la présente description.According to another known arrangement, a silent expansion of the gas is ensured by arranging, externally, on an exhaust pipe, an expansion chamber, a throttling member or other exhaust means, a more or less extensive and thick annular lining, this annular lining being able to be made of various materials such as, for example, a metallic wool or fabric, a glass wool or synthetic fibers, asbestos free, metal shavings or wood, metal fabrics or knits. Examples of such silent expansion devices are described in French patents No. 1,561,483, 2,250,379, 2,372,373 and 2,498,681. It will be noted that the linings used in these examples increase, due to their annular shape, the size of the devices fitted with these linings, for the same volume of acoustically absorbent lining used. There is also known from English patent application No. 2,084,245 a silencer in accordance with the preamble of claim 1 appended to this description.

La présente invention a pour but de réaliser un silencieux injecteur ou éjecteur pour la détente d'un fluide gazeux qui ne présente pas les inconvénients de colmatage ou d'encombrement des silencieux de la technique antérieure.The object of the present invention is to produce a injector or ejector muffler for the expansion of a gaseous fluid which does not have the drawback or blockage drawbacks of the prior art mufflers.

La présente invention a aussi pour but de réaliser un tel silencieux composé d'organes standard, simples et interchangeables, de manière à se prêter à une réalisation peu coûteuse.The present invention also aims to achieve such a silencer composed of standard, simple and interchangeable members, so as to lend itself to an inexpensive embodiment.

La présente invention a encore pour but de réaliser un tel silencieux qui se présente sous la forme d'une cartouche amovible facile à installer ou à remplacer dans un dispositif équipé de tels silencieux.The present invention also aims to achieve such a silencer which is in the form of a removable cartridge easy to install or replace in a device equipped with such silencers.

On atteint ces buts de l'invention, ainsi que d'autres qui apparaîtront dans la suite de la description, avec un silencieux injecteur ou éjecteur pour la détente d'un fluide gazeux comprenant un organe de montage du silencieux sur une source de fluide sous pression en écoulement subsonique et une enveloppe présentant une première extrémité couverte par une pièce d'étranglement percée de trous de surface cumulée (S2) réduite par rapport à la section (S1) d'un embout d'entrée du silencieux et portée par cet organe de manière à communiquer intérieurement avec la source de fluide, cette enveloppe présentant une deuxième extrémité distante de la première et percée de lumières pour le passage dans un milieu extérieur du fluide admis dans l'enveloppe, une garniture remplissant entièrement l'espace intérieur à l'enveloppe, de la pièce perforée jusqu'à la deuxième extrémité de cette enveloppe, avec recouvrement intérieur des lumières percées dans cette deuxième extrémité de l'enveloppe, caractérisé en ce que le rapport de la surface cumulée (S2) des trous de la pièce d'étranglement (8) à celle de la section d'entrée (S1) est tel que l'écoulement à travers cette pièce (8) est relevé à vitesse sonique et en ce que le rapport de la section cumulée des lumières à la surface cumulée (S2) est compris entre 5 et 40 de manière que l'écoulement à travers les lumières soit subsonique.These objects of the invention are achieved, as well as others which will appear in the following description, with an injector silencer or ejector for the expansion of a gaseous fluid comprising a member for mounting the silencer on a source of fluid under subsonic flow pressure and a casing having a first end covered by a throttle piece pierced with holes of cumulative surface (S2) reduced compared to the section (S1) of an inlet end piece of the silencer and carried by this member so as to communicate internally with the fluid source, this envelope having a second end distant from the first and breakthrough of lights for the passage into an external medium of the fluid admitted into the envelope, a lining completely filling the interior space of the envelope, from the perforated part to the second end of this envelope, with internal covering openings in this second end of the casing, characterized in that the ratio of the cumulative surface (S2) of the holes in the throttle piece (8) to that of the inlet section (S1) is such that the flow through this part (8) is noted at sonic speed and in that the ratio of the cumulative section of the lights to the cumulative surface (S2) is between 5 and 40 so that the flow through the lights be subsonic.

Suivant un mode de réalisation préféré de l'invention, la garniture est constituée par un tricot de fil métallique, formé en rouleau serré.According to a preferred embodiment of the invention, the lining is constituted by a knitted wire, formed in a tight roll.

Suivant d'autres modes de réalisation non limitatifs, cette garniture prend la forme d'un tissu métallique en rouleau serré ou encore d'une mousse métallique à cellules ouvertes.According to other nonlimiting embodiments, this lining takes the form of a metallic fabric in a tight roll or even of a metallic foam with open cells.

La présente invention fournit aussi un dispositif de soufflage d'un fluide gazeux sur une surface étendue, équipé d'un ensemble de silencieux suivant l'invention, caractérisé en ce qu'il comprend plusieurs rampes parallèles montées sur un collecteur commun lui-même raccordé à une source d'un fluide gazeux, chaque rampe portant plusieurs silencieux injecteurs ou éjecteurs de fluide régulièrement distribués et orientés de manière que le fluide gazeux soit uniformément distribué par l'ensemble des silencieux sur toute la surface à traiter par soufflage.The present invention also provides a device for blowing a gaseous fluid over an extended surface, equipped with a set of silencers according to the invention, characterized in that it comprises several parallel ramps mounted on a common collector itself connected at a source of a gaseous fluid, each ramp carrying several injector silencers or fluid ejectors regularly distributed and oriented so that the gaseous fluid is uniformly distributed by all of the silencers over the entire surface to be treated by blowing.

Au dessin annexé, donné seulement à titre d'exemple :

  • la figure 1 est une vue en perspective d'un dispositif de soufflage d'un fluide gazeux équipé d'un ensemble de silencieux suivant la présente invention, et
  • la figure 2 est une vue en coupe longitudinale d'un des silencieux suivant l'invention monté sur le dispositif de la figure 1.
In the attached drawing, given only by way of example:
  • FIG. 1 is a perspective view of a device for blowing a gaseous fluid equipped with a set of silencers according to the present invention, and
  • FIG. 2 is a view in longitudinal section of one of the silencers according to the invention mounted on the device of FIG. 1.

Le dispositif de soufflage représenté à la figure 1 est susceptible d'être utilisé dans bien des applications ainsi que le reconnaîtra l'homme de métier, comme le dégivrage de l'entrée d'air d'une turbine ou d'un compresseur à gaz, la purge ou la détente de réservoirs d'air comprimé ou de vapeurs sous pression, le soufflage de vapeur sur une surface à nettoyer par exemple et, d'une manière plus générale, dans la décompression silencieuse de tous gaz ou vapeurs à toutes températures.The blowing device shown in Figure 1 is likely to be used in many applications as will be recognized by those skilled in the art, such as defrosting the air inlet of a gas turbine or compressor, purging or expanding tanks of compressed air or vapors under pressure, blowing steam on a surface to be cleaned for example and, more generally, in the silent decompression of all gases or vapors at all temperatures.

Le dispositif de soufflage représenté à la figure 1 est installé, à titre d'exemple non limitatif d'application de l'invention, en face de la section d'entrée 1 d'une turbine ou d'un compresseur à gaz (non représenté). Cette section d'entrée est ordinairement équipée d'un ou plusieurs filtres qui peuvent, par temps humide et froid, se colmater par de la glace en coupant ainsi l'admission d'air, ou du moins en réduisant celle-ci. Dans cette hypothèse, il faut alors déboucher l'entrée d'air en faisant fondre la glace, par exemple à l'aide d'un soufflage d'air chaud dans le filtre.The blowing device shown in FIG. 1 is installed, by way of nonlimiting example of application of the invention, opposite the inlet section 1 of a gas turbine or compressor (not shown ). This inlet section is usually fitted with one or more filters which can, in wet and cold weather, become clogged with ice, thereby cutting off the air intake, or at least reducing it. In this hypothesis, it is then necessary to unblock the air inlet by melting the ice, for example by means of a blowing of hot air into the filter.

Pour ce faire, le dispositif de la figure 1 comprend une source d'air chaud sous pression (non représentée), alimentant suivant la flèche F une canalisation 2 munie d'une vanne de réglage 3. La canalisation 2 alimente à son tour un collecteur tubulaire 4, par exemple horizontal, sur lequel sont distribuées régulièrement et parallèlement, des rampes verticales 5, 5', etc... qui portent chacune plusieurs silencieux injecteurs et détendeurs d'air 6, 6', etc... suivant l'invention, distribués régulièrement et orientés de manière à souffler de l'air chaud sur toute l'étendue de la section d'entrée 1 de l'air de la turbine, pour assurer ainsi un dégivrage uniforme du filtre placé dans cette entrée d'air. Le maillage des silencieux peut être compris avantageusement entre 300 x 300 mm et 1000 x 1000 mm, suivant les dimensions de ceux-ci.To do this, the device of FIG. 1 comprises a source of pressurized hot air (not shown), supplying along the arrow F a pipe 2 provided with an adjustment valve 3. The pipe 2 in turn feeds a manifold tubular 4, for example horizontal, on which are regularly and parallel distributed, vertical ramps 5, 5 ', etc ... which each carry several silent injectors and air regulators 6, 6', etc ... according to invention, distributed regularly and oriented so as to blow hot air over the entire extent of the air intake section 1 of the turbine, to thus ensure uniform defrosting of the filter placed in this air inlet . The mesh of the silencers can advantageously be between 300 x 300 mm and 1000 x 1000 mm, depending on the dimensions thereof.

Avec des injecteurs d'air classiques en lieu et place des silencieux 6, 6'... suivant l'invention, une telle alimentation à basse pression exige des rampes 5, 5' de fort diamètre et donc coûteuses, si on veut limiter la vitesse de l'écoulement et le bruit dans les tuyauteries 2, 4, 5, 5'... en particulier dans les coudes ou les raccordements en "T".With conventional air injectors in place of the mufflers 6, 6 '... according to the invention, a such a low pressure supply requires ramps 5, 5 'of large diameter and therefore costly, if one wishes to limit the speed of the flow and the noise in the pipes 2, 4, 5, 5' ... in particular in elbows or "T" connections.

Suivant la présente invention, les silencieux 6, 6'..., qui jouent simultanément le rôle d'injecteurs, réalisent une détente silencieuse sonique des gaz chauds.According to the present invention, the silencers 6, 6 ′, which simultaneously act as injectors, achieve sonic silent expansion of the hot gases.

Grâce aux silencieux suivant l'invention, on obtient une bonne répartition de l'air chaud dans la section 1 d'entrée d'air et on peut utiliser entre la vanne 3 et ces silencieux, des tuyauteries de faible diamètre, donc moins coûteuses, dans lesquelles la pression peut être réglée, par dimensionnement de la section de passage de la pièce d'étranglement, à une valeur comprise en 5 et 15 bars, ou plus si la source d'air chaud le permet.Thanks to the silencers according to the invention, a good distribution of the hot air is obtained in the air inlet section 1 and it is possible to use between the valve 3 and these silencers, small diameter pipes, therefore less costly, in which the pressure can be adjusted, by dimensioning the passage section of the throttle piece, to a value between 5 and 15 bars, or more if the source of hot air allows.

On décrira maintenant plus en détail un silencieux injecteur suivant l'invention, en se référant à la figure 2 du dessin qui représente un tel silencieux en coupe longitudinale.We will now describe in more detail an injector silencer according to the invention, with reference to Figure 2 of the drawing which shows such a silencer in longitudinal section.

Celui-ci comprend essentiellement une enveloppe tubulaire cylindrique 7 fermée à une première extrémité par une pièce d'étranglement 8 et à une deuxième extrémité par un disque 9. La première extrémité de cette enveloppe tubulaire est montée dans un organe de montage 10 prenant la forme d'un embout de fixation du silencieux sur une source d'alimentation en fluide gazeux (non représentée à la figure 2). L'embout 10 est fixé par vissage ou soudure sur la source pour assurer une communication entre la source et l'enveloppe 7 du silencieux à travers la pièce d'étranglement 8. Celle-ci s'appuie sur un épaulement annulaire 11 formé dans l'alésage 12 de cet embout qui reçoit l'extrémité adjacente de l'enveloppe tubulaire 7. L'embout 10 peut être un embout du commerce réalisé par tournage ou forgeage et présente un filetage pour la fixation de l'enveloppe 7. Celle-ci pourrait aussi être soudée sur cet embout. L'autre extrémité de l'enveloppe est percée de lumières 13, 13', 13'',... réparties régulièrement autour de l'enveloppe au voisinage du disque 9. Le disque 9, fixé sur l'enveloppe 7 par soudure ou vissage, peut lui-même être percé de lumières. La surface cumulée de toutes ces lumières est, de préférence, dans un rapport 5 à 40 avec la surface ouverte de la pièce d'étranglement 8.This essentially comprises a cylindrical tubular casing 7 closed at a first end by a throttle piece 8 and at a second end by a disc 9. The first end of this tubular casing is mounted in a mounting member 10 taking the form a tip for fixing the silencer to a source of gas fluid supply (not shown in Figure 2). The end piece 10 is fixed by screwing or welding to the source to ensure communication between the source and the casing 7 of the silencer through the throttle piece 8. This rests on an annular shoulder 11 formed in the bore 12 of this end piece which receives the adjacent end of the tubular casing 7. The end piece 10 can be a commercial end-piece produced by turning or forging and has a thread for fixing the casing 7. The latter could also be soldered on this tip. The other end of the envelope is pierced with lights 13, 13 ', 13'', ... regularly distributed around the envelope in the vicinity of the disc 9. The disc 9, fixed to the envelope 7 by welding or screwing, can itself be pierced of lights. The cumulative surface of all these lights is preferably in a ratio 5 to 40 with the open surface of the throttle piece 8.

Suivant un mode de réalisation préféré de l'invention, la pièce d'étranglement prend la forme d'une plaque circulaire percée de trous de même diamètre et régulièrement répartis. Cette plaque peut être réalisée par poinçonnage d'une feuille de tôle perforée, ou bien par perçage. Son épaisseur est fonction de la pression dans la rampe 5 et de son diamètre.According to a preferred embodiment of the invention, the throttle piece takes the form of a circular plate pierced with holes of the same diameter and regularly distributed. This plate can be produced by punching a sheet of perforated sheet metal, or by drilling. Its thickness is a function of the pressure in the ramp 5 and its diameter.

Une caractéristique essentielle de cette plaque 8 tient en ce que le cumul S2 des sections de ces trous doit être réduit par rapport à la section d'entrée S1 de l'embout 10, de manière à assurer un écoulement sonique du gaz à l'entrée dans l'enveloppe 7, tout en maintenant un même débit-masse et un écoulement subsonique dudit gaz dans les tuyauteries amont du dispositif suivant l'invention, pour un but qui apparaîtra plus loin.An essential characteristic of this plate 8 is that the cumulative S2 of the sections of these holes must be reduced relative to the inlet section S1 of the nozzle 10, so as to ensure a sonic flow of gas at the inlet in the envelope 7, while maintaining the same mass flow and a subsonic flow of said gas in the pipes upstream of the device according to the invention, for a purpose which will appear later.

Une caractéristique essentielle du silencieux suivant l'invention, liée à la présence d'ondes de choc en aval de la plaque 8, tient en ce que l'enveloppe tubulaire 7 est entièrement remplie, de la plaque perforée 8 au disque 9, d'une garniture 14 en fil métallique fin (intérieur à 1 mm), du type tricot ou tissu enroulé serré. La longueur L de la garniture ne doit pas être inférieure à 20 mm pour une enveloppe 7 de petit diamètre et doit être comprise si possible entre 20 et 300 mm quel que soit le diamètre de l'enveloppe. La porosité d'un tel tricot ou tissu est supérieure à 80%.An essential characteristic of the silencer according to the invention, linked to the presence of shock waves downstream of the plate 8, is that the tubular casing 7 is completely filled, from the perforated plate 8 to the disc 9, a lining 14 made of fine metal wire (inside 1 mm), of the knitted or tightly wound fabric type. The length L of the lining must not be less than 20 mm for an envelope 7 of small diameter and should be between 20 and 300 mm, if possible, whatever the diameter of the envelope. The porosity of such a knitted fabric is greater than 80%.

Le fonctionnement du silencieux suivant l'invention s'établit alors comme suit. Le gaz qui pénètre dans l'enveloppe 7 subit une détente sonique au niveau de la plaque 8 et la garniture en fil métallique 14 réduit alors le bruit de la détente en stabilisant et fractionnant les ondes de choc et en homogénéisant l'écoulement. Grâce au fait qu'elle recouvre intérieurement les lumières 13, 13', 13'',..., la garniture réduit aussi l'émission vers l'extérieur de bruits engendrés par le passage du gaz à travers ces lumières. La présence d'un écoulement sonique empêche toute remontée des bruits vers l'amont, donc dans le reste de l'installation. De surcroît l'augmentation de la pression dans l'installation, due à la pièce d'étranglement, a pour effet, pour un même débit-masse, de réduire la vitesse du fluide et donc le bruit dans l'alimentation. En aval de la plaque 8, l'écoulement s'opère à faible vitesse et à basse pression et l'enveloppe tubulaire 7 n'est donc pas soumise à des pressions intérieures élevées.The operation of the silencer according to the invention is then established as follows. The gas which enters the envelope 7 undergoes a sonic expansion at the level of the plate 8 and the metal wire lining 14 then reduces the noise of the trigger by stabilizing and splitting the shock waves and by homogenizing the flow. Thanks to the fact that it internally covers the lights 13, 13 ', 13'', ..., the lining also reduces the emission towards the outside of noises generated by the passage of gas through these lights. The presence of a sonic flow prevents any rise of noise upstream, therefore in the rest of the installation. In addition, the increase in pressure in the installation, due to the throttle piece, has the effect, for the same mass flow, of reducing the speed of the fluid and therefore the noise in the supply. Downstream of the plate 8, the flow takes place at low speed and at low pressure and the tubular casing 7 is therefore not subjected to high internal pressures.

D'autres matériaux pourraient être choisis pour constituer la garniture 14, par exemple une mousse métallique à celles ouvertes de porosité supérieure à 50%. D'une manière générale, il convient que ce matériau manifeste une bonne résistance mécanique à la pression développée par le gaz entré par les trous de la plaque perforée 8, de manière à ne pas être refoulé vers l'autre extrémité de l'enveloppe et à continuer à remplir complètement celle-ci. A cet égard, des essais ont montré que le tricot métallique référencé G 270, inox 304 L, gaufré, double et enroulé serré, dans les catalogues de la Société GANTOIS, donne d'excellents résultats.Other materials could be chosen to constitute the lining 14, for example a metallic foam with open ones of porosity greater than 50%. In general, this material should exhibit good mechanical resistance to the pressure developed by the gas entering through the holes in the perforated plate 8, so as not to be forced back towards the other end of the envelope and to continue to fill it completely. In this regard, tests have shown that the metallic knitted fabric referenced G 270, stainless steel 304 L, embossed, double and tightly wound, in the catalogs of the GANTOIS Company, gives excellent results.

Le silencieux suivant l'invention se prête à des réalisations en tous diamètres à de faibles coûts à l'aide d'organes, embout, tube, etc... du commerce. Il peut être entièrement métallique en acier ou acier inoxydable et résiste à des pressions élevées, la pression amont n'étant appliquée qu'à la pièce 8. Il peut résister aussi à des températures élevées par une réalisation en acier inoxydable réfractaire, y compris le tricot métallique. On peut, en prévoyant une fixation par vissage, lui donner le caractère d'une cartouche amovible et interchangeable.The silencer according to the invention lends itself to embodiments in all diameters at low costs using commercial organs, end pieces, tubes, etc. It can be entirely metallic in steel or stainless steel and withstands high pressures, the upstream pressure being applied only to part 8. It can also withstand high temperatures by making it in refractory stainless steel, including the metallic knitting. One can, by providing a fixing by screwing, give it the character of a removable and interchangeable cartridge.

Grâce à l'invention, on établit de faibles vitesses dans les tuyauteries d'écoulement du gaz en amont du silencieux, la pression étant alors élevée, le silencieux permettant d'obtenir une réduction de 25 à 45 dB du bruit qui serait créé par une détente sonique directe à l'air libre à travers la section S2.Thanks to the invention, low speeds are established in the gas flow pipes upstream of the silencer, the pressure then being high, the silencer making it possible to obtain a reduction of 25 to 45 dB of the noise which would be created by a direct sonic relaxation in the open air through section S2.

Le silencieux sonique suivant l'invention forme en outre écran à la remontée de bruits vers l'amont dans la tuyauterie d'alimentation. Grâce à l'invention, et du fait des faibles vitesses du fluide dans l'alimentation, on peut envisager le remplacement de la vanne de réglage par une vanne tout ou rien moins coûteuse, ou par plusieurs vannes en parallèle si plusieurs débits de fonctionnement sont nécessaires.The sonic silencer according to the invention also forms a screen for the upward noise rise in the supply piping. Thanks to the invention, and because of the low speeds of the fluid in the supply, it is possible to envisage replacing the control valve by an all or nothing less expensive valve, or by several valves in parallel if several operating flow rates are required.

En outre, les caractéristiques de porosité, de cohésion et d'élasticité de la garniture se combinent pour assurer un décolmatage efficace de celle-ci sous l'effet de l'agitation développée par les ondes de choc qui se propagent dans le silencieux suivant l'invention.In addition, the characteristics of porosity, cohesion and elasticity of the lining combine to ensure effective unclogging of the latter under the effect of the agitation developed by the shock waves which propagate in the silencer according to l 'invention.

Claims (8)

  1. Injector or ejector silencer for the expansion of a gaseous fluid, comprising a member (10) for mounting the silencer on a source of subsonically flowing fluid under pressure and a casing (7) having a first end covered by a throttle piece (8) perforated with holes of total cross-section (S2) lower than that of section (S1) of an input end of the silencer, and carried by this member so as to communicate internally with the fluid source, this casing (7) having a second end distant from the first and pierced with ports (13) for the fluid admitted into the casing (7) to pass into an outside medium, a packing completely filling the space within the casing from the perforated piece to the second end of this casing (7), with an inner overlap of the ports (13) pierced in this second end of the casing, characterized in that the ratio of the total cross-section (S2) of the holes in the throttle piece (8) to the input section (S1) in such that the flow through this piece (8) is raised to a sonic speed, and in that the ratio of the total section of ports (13) to total section (S2) is comprised between 5 and 40 so that the flow through the ports is subsonic.
  2. Silencer according to claim 1, characterized in that the throttle piece consists of a plate having a uniform distribution of holes of identical dimensions.
  3. Silencer according to claim 1 or 2, characterized in that the packing consists of a knitted fabric of metal wire in the form of a closely wound roll.
  4. Silencer according to anyone of claims 1 to 3, characterized in that the packing consists of a woven fabric of metal wires in the form of a closely wound roll.
  5. Silencer according to claim 1 or 2, characterized in that the metal-wire packing is replaced by a metal sponge with open cells.
  6. Silencer according to any one of claims 1 to 5, characterized in that the packing has a porosity higher than 50 %.
  7. Silencer according to any one of the preceding claims, characterized in that the casing takes the form of a cylindrical tube.
  8. Device for blowing a gaseous fluid onto an extensive surface, equipped with an assembly of silencers according to any one of the preceding claims, characterized in that it comprises a plurality of parallel racks (5), mounted on a common manifold (4) itself connected to a source of a gaseous fluid, each rack carrying a plurality of fluid injector or ejector silencers (6, 6', etc.) uniformly distributed and oriented in such a way that gaseous fluid is uniformly distributed over the entire surface to be treated by blowing.
EP89903496A 1988-03-11 1989-03-09 Silencer for a gas flow Expired - Lifetime EP0404801B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89903496T ATE97463T1 (en) 1988-03-11 1989-03-09 SILENCER FOR FLOWING GASES.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8803183A FR2628477B1 (en) 1988-03-11 1988-03-11 EJECTOR OR INJECTOR MUFFLER FOR THE EXPANSION OF A GASEOUS FLUID AND BLOWING DEVICE PROVIDED WITH AN ASSEMBLY OF SUCH A MUFFLER
FR8803183 1988-03-11

Publications (2)

Publication Number Publication Date
EP0404801A1 EP0404801A1 (en) 1991-01-02
EP0404801B1 true EP0404801B1 (en) 1993-11-18

Family

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Application Number Title Priority Date Filing Date
EP89903496A Expired - Lifetime EP0404801B1 (en) 1988-03-11 1989-03-09 Silencer for a gas flow

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US (1) US5166479A (en)
EP (1) EP0404801B1 (en)
DE (1) DE68910816T2 (en)
FR (1) FR2628477B1 (en)
WO (1) WO1989008771A1 (en)

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Also Published As

Publication number Publication date
EP0404801A1 (en) 1991-01-02
US5166479A (en) 1992-11-24
FR2628477A1 (en) 1989-09-15
WO1989008771A1 (en) 1989-09-21
DE68910816D1 (en) 1993-12-23
FR2628477B1 (en) 1993-05-14
DE68910816T2 (en) 1994-06-09

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