FR2589195A1 - Soundproofed chimney for hot gases ejected from an exhaust pipe - Google Patents

Abstract

Soundproofed chimney for hot gases ejected from an exhaust pipe. The present invention relates to a soundproofed chimney 20 for hot gases ejected from an exhaust pipe 1, enveloping a dispersion basket 21 pierced with holes 23 and whose end opposite the gas inlet is closed by a solid bottom 22, characterised in that the main axis of the basket and the main axis of the chimney are coincident, the basket being pierced with holes 23 over its entire periphery, the main axis of each orifice 23 being perpendicular to the internal faces of the chimney 20 covered by a thermo-acoustic coating 27. Application to exhaust chimneys for test beds.

Description

Soundproof chimney for hot gases ejected from an exhaust pipe
The present invention relates to a soundproof gas fireplace
hot ejected from an exhaust pipe.

In installations ejecting hot gases, such as, for example
examples, a turbojet or powder engine test bench, or
a gas turbine installation with the motor shaft on the side
suction, the ejection of gases is generally done by
through a horizontal exhaust pipe, this one being ra
ccorded to a vertical chimney which it is necessary to arrange to
avoid noise due to the release of gases into the atmosphere.

This arrangement of the chimney must ensure regulation of the
flow and a good distribution of gas speeds, and also a
good attenuation of the sound level.

There are known vertical chimneys whose bottom is provided with a
spark gap basket with holes on most of its circumference
and placed directly in the axis of the hori exhaust pipe
zontal. This basket, placed horizontally in a vertical chimney,
therefore comprises rows of orifices opening into the axis of the
vertical chimney, then rows opening perpendicular to
the axis of the chimney, and finally several intermediate rows.

The holes in this basket create multijets ensuring
correct flow regulation but the non-symmetrical distribution of these
orifices relative to the main axis of the chimney, causes
on the one hand an asymmetry in the distribution of speeds and on the other hand
a partial attenuation of the noise level because the gases leaving the
orifices located in the main axis of the chimney do not meet
no absorbent surface. The installation of several rows of
acoustic baffles above the basket is therefore essential.

The present invention aims to ensure, in all chemi
exhaust from hot gases, perfect flow regulation,
a good distribution of speeds and a reduction in the level of
noise greater than that of the prior art.

This goal is achieved by placing the main axis of the basket in
the axis of the exhaust chimney, the concentric chimney and basket assembly being installed vertically or horizontally.

 The present invention relates to a soundproof chimney for hot gases ejected from an exhaust tube, enveloping a sparkling basket pierced with orifices and the end opposite to the gas inlet is closed by a solid bottom, characterized in that the main axis of the basket and the main axis of the chimney are combined, the basket being pierced with orifices over its entire periphery, the main axis of each orifice being perpendicular to the internal faces of the chimney covered by a coating thermo-acoustic.

 According to a first embodiment, a chimney installed vertically, perpendicular to the exhaust tube, surrounds an elbow connected at one of its ends to the horizontal exhaust tube, and at the other of its ends to the vertical sparkler basket. This chimney may also include, above the basket, acoustic baffles.

 According to a second embodiment, a chimney installed horizontally, in the extension of the exhaust tube, is extended by an elbow allowing the vertical discharge of the gases into the atmosphere.

 It is described below, with reference to the accompanying drawings, a chimney of the prior art and three exemplary embodiments of the chimney according to the invention.

 Figure 1 shows a fireplace of the prior art and Figures 2, 3 and 4 each show an embodiment of the fireplace according to the invention.

 Figure 1 shows a chimney 10 placed at the outlet of an exhaust tube 1 of a test bench for reactors for example. A seal 2 seals between the chimney 10 and the tube 1. The chimney 10, installed perpendicular to the tube 1, comprises a separator basket 11 placed horizontally, in the extension of the tube 1.

 This sparkling basket is closed at its end opposite the tube 1 by a rounded domed bottom 12, and it is pierced with orifices 13 over approximately two thirds of its circumference, that is to say outside of an area low 14 symmetrical about the vertical axis of the basket. This basket is placed on a base 15 and retained by a flange 16. The chimney 10 is coated, on its internal faces, with a thermal coating 17, and it includes flat acoustic baffles 18A, 18B.

 The orifices 13 of the basket ensure correct regulation of the flow rate, but the non-symmetrical distribution of the orifices relative to the chimney results in different gas flow velocities as shown by the speed distribution line 19.

 The upper holes of the basket, located in the main axis of the chimney, project the gases upwards in a direction parallel to the main axis. These gases therefore do not encounter any surface attenuating the sound waves and to have the presence of the acoustic baffles 18A and 18B is essential.

 Figure 2 shows a chimney 20 perpendicular to an exhaust tube 1, a seal 2 ensuring the seal between the two.

 This chimney comprises, according to the invention, an elbow 29 placed on a support 29A and connected at one end to the tube 1 and at its other end to a spark basket 21, this basket being concentric with the chimney, drilled with orifices 23 over its entire circumference and provided of a rounded domed bottom 22. The internal walls of this chimney are necessarily covered with a thermo-acoustic coating 27.

 This chimney 20 is in this case bidirectional and it does not require any acoustic baffle, except naturally in the case where exceptional acoustic performance would be desired, a single row of baffles 28, or another sound-absorbing device would then be installed above the basket.

 FIG. 3 shows a cylindrical chimney 20 equivalent to that of FIG. 2, and provided with an equivalent elbow 29 and an equivalent basket 21. In the case where the acoustic baffles would be necessary, these would be concentric rings 28A , 28B, 28C, covered with an absorbent product.

 In these Figures 2 and 3, the gases are straightened upwards by crossing the elbow 29, then they exit the basket, over its entire circumference, in horizontal planes and symmetrically, thus ensuring aerodynamically: good regulation flow, homogeneous and concentric speed rings represented by the distribution lines 30, and a perfect distribution of speeds in the chimney. Acoustically, the gases meet, on the walls of the chimney, an acoustically absorbent surface normal to their direction, which causes a noise attenuating elbow effect. The acoustic coating 27 also performs a thermal insulation role.

 FIG. 4 shows a chimney according to the invention, installed at the outlet of the exhaust tube 1.

 The chimney 20 according to the invention comprises a sparkler basket 21, the respective axes of the chimney, the basket and the tube, being combined. The basket 21 has a rounded domed bottom 22 and orifices 23 distributed over its entire circumference. This chimney is extended by a bend 29 possibly comprising a hatch 29B allowing energy recovery. The chimney and the elbow are supported by supports 25, 25A, the supports 25 being fixed and the supports 25A movable along the main axis.

 The internal faces of the chimney and the elbow are covered with a thermo-acoustic coating 27.

 The gases exit the basket around its entire circumference and in a symmetrical manner, thus ensuring good regulation of the flow rate and good distribution of the speeds represented by the lines 30. They undergo a first acoustic elbow effect by meeting the surface 27 then a second effect in the elbow 29.

Claims (5)

1 / Soundproof chimney (20) for hot gases ejected from an exhaust tube (1), enveloping a spark basket (21) pierced with orifices (23) and whose end opposite to the gas inlet is closed by a solid bottom (22), characterized in that the main axis of the basket and the main axis of the chimney are merged, the basket being pierced with orifices (23) over its entire periphery, the main axis of each orifice (23) being perpendicular to the internal faces of the chimney (20) covered by a thermo-acoustic coating (27). 2 / Chimney according to claim 1, installed vertically, perpendicular to the exhaust tube, characterized in that it envelops an elbow (29) connected at one of its ends to the exhaust tube (1) and to the other of its ends to the vertical sparkler basket (21). 3 / Chimney according to claim 2, whose section is pedic parallelepi, characterized in that it comprises, above the sparkler basket (21), flat acoustic baffles (28). 4 / Chimney according to claim 2, whose section is cylindrical, characterized in that it comprises, above the spark basket (21), acoustic baffles consisting of rings (28A, 28B, 28C) covered with a coating acoustic. 5 / Chimney according to claim 1, installed horizontally, in the extension of the exhaust tube (1), characterized in that it is extended by an elbow (29) allowing the vertical discharge of gases into the atmosphere.