EP3388678B1 - Pulsation sound damper for compressors - Google Patents

Description

The invention relates to a pulsation silencer for a gaseous media flow which is supplied by a compressor, in particular by a compressor. Such a silencer comprises a housing extending along a central axis with a media flow inlet and a media flow outlet as well as one or more absorber elements which are made of a sound-absorbing material and are used for sound absorption.

A wide variety of compressor designs are known for compressing gaseous media, in particular for generating compressed air. For example, the DE 601 17 821 T2 a multi-stage screw compressor with two or more compressor stages, each compressor stage comprising a pair of rotors for compressing a gas. Furthermore, two or more variable speed drive means are provided, each drive means driving a respective compressor stage. A control unit controls the speeds of the drive means, the torque and speed of each drive means being monitored so that the screw compressor provides gas at a required flow delivery rate and at a required pressure while minimizing the energy consumption of the screw compressor.

In general, the problem arises with compressors, especially with machines working according to the displacement principle, that due to the discontinuous extension process on the pressure or extension side of the compressor, in the downstream components, such as pipelines, Cooler, pressure vessel, etc., undesirable pulsations, ie pressure changes occur. These downstream components are subjected to considerable stress due to the pressure changes and / or the vibrations excited thereby, which can lead to material damage due to fatigue, for example. The pressure changes also cause considerable noise emissions, based on structure-borne noise introduction, sound transmission and sound radiation. In addition, the pulsations can have repercussions on the compressor stage, which can affect the compression process itself. These problems occur particularly drastically in the case of dry-compressing screw compressors, in which in some cases considerable pulsations occur at the outlet of the compressor stages. Since the extension processes are pulse-like processes, the harmonics of the basic pulsation frequency are also very pronounced, in some cases even stronger than the basic frequency itself.

Due to the above-mentioned processes and reinforced by the fact that many compressors are equipped with a speed control for adapting the delivery rate, the frequency spectrum of the pulsations is correspondingly large. This places high demands on the pulsation silencers used in the compressors, since a correspondingly large frequency spectrum has to be damped.

From the DE 699 20 997 T2 A pulsation damper for a pump is known, which comprises a device body and a membrane, the membrane dividing an interior of the device body into a liquid chamber which can temporarily store a liquid to be transported by a piston pump, and a gas chamber which is filled with a gas for suppression is filled with pulsations and expands and contracts to change a capacity of the liquid chamber. This dampens pulsations due to an initial pressure of the transported liquid.

The DE 698 18 687 T2 describes a pulsation damper for damping low-frequency gas pulses with a container having an inlet, an outlet and sound-absorbing elements which are arranged in the container. At least one of the inlet and outlet is provided with a diffuser which comprises a tubular part which is provided with first openings. The tubular part comprises an element which is provided with a number of second openings and is delimited by reinforcing bodies which extend around the circumference, at least one of the second openings being covered by a plate which is provided with the first openings, which are smaller than the second openings are.

The aforementioned pulsation silencers have a complex structure and are therefore expensive and maintenance-intensive. Simple pulsation silencers are also known from practice, which are essentially formed in the manner of an elongated tube with absorber materials attached inside and which aim at damping both by absorption and reflection of the sound. However, these known mufflers have several disadvantages. First of all, a great length of the absorber part is decisive for achieving sufficient damping. Since the absorber materials used show constant attenuation over the length, the sound attenuation takes place gradually from the entry into the muffler to the exit, which means that a relatively large amount of sound is still radiated to the outside via the housing in the entry area of the muffler. In addition, the sound penetrates, especially at high frequencies through the elongated damper tube, so that certain frequencies of the pulsations can pass the absorber almost undamped.

The DE 10 2016 100 140 A1 describes a noise damper for a compressed air system of a commercial vehicle. The silencer has a housing with an air inlet, an air outlet and an insulating structure in the manner of a labyrinth. An insulating material can be arranged in the housing, but the aim is to minimize this insulating material.

The FR 2 713 702 A1 shows a silencer for a gas flow of a compressor with a housing which has a gas flow inlet and a gas flow outlet. An inner side wall of the housing has an acoustically absorbent coating, preferably made of fibrous material such as mineral wool, which is held by a grid. An outer side wall has an acoustically absorbent coating which is held by a grille. The gas flow is guided through the flow space delimited by the grids.

From the DE 90 14 888 U1 a silencer is known which is designed as a detachably attachable component. The silencer has baffles in its interior for a multiple deflection of a gas flow. A gas flow inlet and a gas flow outlet are located in the area of an end face of the silencer.

One object of the present invention is to provide an improved pulsation silencer which is suitable for use in compressors, in particular in screw compressors, an inexpensive and simple one Structure and shows high attenuation values in a wide frequency spectrum. In particular, the aim is to achieve the highest possible damping of the pulsations occurring in compressors over a short overall length, while at the same time only a small pressure loss may occur in the compressed medium. In addition, any remaining sound radiation from the housing of the pulsation silencer should be minimized.

These and other objects are achieved by a pulsation silencer according to the appended claim 1. The subclaims name some preferred embodiments. In addition, the invention provides a compressor with such a pulsation silencer.

The pulsation silencer according to the invention is suitable for the damping of pulsations and the sound resulting therefrom in a gaseous media flow that is produced by a compressor is delivered. The pulsation silencer initially has a housing extending along a central axis with a media flow inlet and a media flow outlet. Furthermore, several sleeve-shaped absorber elements are provided, which consist of sound-absorbing material and are arranged concentrically to one another in the housing. In this respect, the pulsation silencer differs significantly from known silencers, because in the prior art either only a single absorber element is used or several absorber elements are arranged axially one behind the other. Each sleeve-shaped absorber element has an inlet area and an outlet area, which are positioned axially spaced apart from one another, and are preferably arranged on the opposite end faces of the absorber element. The inlet area of the aerodynamically forwardmost absorber element is connected to the media flow inlet of the housing, the outlet area of the aerodynamically forwardmost absorber element is connected to the inlet area of the aerodynamically downstream absorber element and so on, and the outlet area of the aerodynamically rearmost absorber element is connected to the media outlet of the housing. Between each radially adjacent wall sections of different absorber elements there remains a flow space through which the media flow is guided.

As a result of the construction explained, the multiple absorber elements thus form multiple stages that are nested within one another. Each of these stages works like a separate absorber. The media flow changes direction several times in the silencer, preferably it meanders along the individual absorber elements.

A major advantage of the pulsation silencer is that the overall length is considerably reduced due to the nested arrangement of the absorber elements and the resulting meander-like guidance of the media flow. With comparable damping of the overall system, the silencer according to the invention is more than half shorter than a conventional silencer with a straight line for the flow of media.

According to a first embodiment, the absorber elements consist of the same sound-absorbing material, so that they all act on the same frequency range. In a modified embodiment, the individual absorber elements are matched to the damping of different frequency ranges, in particular by using different sound-absorbing materials. The absorber elements preferably consist of mineral material, metal or plastic fabric, metal or ceramic foams, with chamber-like structures being advantageous. Multi-layer absorber material layers can also be used.

A preferred embodiment of the pulsation silencer uses rotationally symmetrical absorber elements which interlock telescopically and are arranged in an axially fixed manner in the housing. In modified versions, however, the absorber elements can also have a rectangular or polygonal cross section. According to the invention, at least three or more absorber elements are arranged in a ring to one another, with a difference remaining between the inner diameter of each outer absorber element and the outer diameter of an opposite inner absorber element in order to form the flow space there, for example with a width of 5 - 10 mm. The absorber elements extend over almost the same axial length, so that at least 80%, preferably at least 90% of the longitudinal extent of the absorber elements axially overlap.

According to a preferred embodiment, the inlet area and the outlet area are each arranged at the end faces of the absorber elements, the direction of flow of the media flow being reversed by 180 ° at the transition from one absorber element to the next absorber element. Since, due to the nested arrangement of the sleeve-shaped absorber elements, there is also an increase in cross-section for the media flow at the transition between the adjacent absorber elements (even with the same gap width in the flow space), the flow velocity is reduced, which results in additional damping. Depending on the design, it is easy to double the cross-sectional area through which the flow passes, and thus a significant reduction in speed from one stage to the next. The reversal of direction when the media flow passes from one absorber element to the next can also be used positively to improve the damping properties, because the deflections mean that there is no direct "line of sight" between the media flow inlet and the media flow outlet, which means that pulsations of higher frequencies are directly transmitted downstream components prevented.

By using sleeve-like absorber elements with annular flow spaces remaining in between, generous cross-sections for the flow guidance of the media flow can be achieved, which results in very low pressure losses.

An advantageous embodiment is characterized in that the aerodynamically frontmost absorber element is arranged radially on the inside and the aerodynamically rearmost absorber element is arranged radially on the outside. The housing preferably has an absorber element receiving area with a circular cross section; an end plate on which the media inlet is designed as a centrally located inlet opening which opens into a central inlet area of the foremost absorber element in terms of flow; and a flange, which lies opposite the end plate, forms the media outlet and into which an annular outlet region of the absorber element which is at the rear in terms of flow opens. Since the media entry into the silencer is in the inner area in this construction, the place with the greatest sound energy is there, i.e. H. far from the outer casing wall. In the case of a silencer equipped with three absorber elements, the next stage in the flow direction is also located inside the damper. In the last stage, which is formed by the absorber element adjoining the housing, the sound energy has already been reduced in such a way that the sound energy still radiated by the housing is minimal.

According to a preferred embodiment of the pulsation silencer, the ratio of the axial length to the maximum cross-sectional extension (e.g. diameter) of each absorber element is less than 5, preferably less than 2.5. In the case of the radially outermost absorber element, this ratio is particularly preferably less than 1, preferably less than 0.75. It is also advantageous if the ratio of the overall axial length of the pulsation silencer to the length of the media flow through the absorber elements The distance covered is less than 1, preferably less than 0.5.

The compressor provided by the invention for compressing gaseous media comprises a compressor and a pulsation silencer which is arranged downstream of the compressor in terms of flow technology and is designed according to the embodiments described above or combinations of these embodiments. The compressor is preferably designed as a screw compressor or a double screw compressor. A significant advantage of using the pulsation silencer according to the invention is the drastic reduction in the required size, which has a positive effect on the design of the entire compressor.

A further developed embodiment of the pulsation silencer is characterized in that one or more of the absorber elements have additional cavities which act as resonator chambers. The resonator chambers preferably extend at an angle to the flow spaces and serve for additional pulsation and sound dampening using reflection and resonance effects.

Fig. 1

einen Längsschnitt eines erfindungsgemäßen Pulsations-Schalldämpfers mit drei hülsenartigen Absorberelementen;

Fig. 2

einen Querschnitt des Pulsations-Schalldämpfers gemäß Fig. 1.

Further advantages and details emerge from the following description of a preferred embodiment with reference to the drawing. Show it:

Fig. 1

a longitudinal section of a pulsation silencer according to the invention with three sleeve-like absorber elements;

Fig. 2

a cross section of the pulsation muffler according to Fig. 1 .

Fig. 1 shows a simplified longitudinal sectional view of a pulsation silencer 100 according to the invention, while Fig. 2 whose cross-section shows. In this example, the muffler 100 has an essentially cylindrical housing 101 with an absorber element receiving area 102, an end plate 103 closing the housing at the end and a flange 104 axially opposite the end plate Compressor compressed gaseous media flow 107, in particular compressed air, is supplied.

A plurality of sleeve-like absorber elements 108 are arranged in the absorber element receiving area 102, in the example shown a front absorber element 108a in terms of flow, a middle absorber element 108b in terms of flow and a rear absorber element 108c in terms of flow. The three absorber elements are telescopically inserted into one another and have essentially the same length in the axial direction. All absorber elements consist of sound-absorbing material, whereby the specific properties of the material can be selected to be differentiated between the individual absorber elements.

The media flow inlet 106 opens into the centrally located inlet area of the front absorber element 108a, so that the media flow initially flows inside the front absorber element 108a and is dampened by its material. The interior of the front absorber element 108a can be hollow or filled with gas-permeable material, the flow resistance having to be kept low. On that of the faceplate 103 facing away from the end of the front absorber element 108a, an outlet area is provided so that the media flow can exit from the front absorber element 108a. There, the media flow flows in a first ring-shaped alternating region 110 into the inlet region of the central absorber element 108b, with a reversal of direction in the media flow 107. The middle absorber element 108b surrounds the aerodynamically front absorber element 108a in a ring shape, a centering pin 111 provided on the middle absorber element 108b serving to hold the front absorber element 108a. The media flow 107 now flows through a first cylindrical flow space 112, which extends in the axial direction between the front absorber element 108a and the middle absorber element 108b.

At the end of the middle absorber element 108b directed towards the end plate 103, the media flow leaves the first cylindrical flow space 112 via an outlet area and flows into the inlet area of the rear absorber element 108c in a second annular changing area 113. The media flow 107 now flows through a second cylindrical flow space 114, which extends in the axial direction between the middle absorber element 108b and the rear absorber element 108c. The flow direction in the second flow space 114 is axially opposite to the flow direction in the first flow space 112.

At the end of the aerodynamically rear absorber element 108c facing away from the end plate 103, the media flow 107 leaves the absorber element receiving area 102 via an outlet region of the aerodynamically rear absorber element 108c and then flows through a media flow outlet 116 in the flange 104 to the downstream units of the Compressor. It can be seen from the figures that the cross section available for the media flow increases significantly in the changing areas and is ultimately significantly larger at the media flow outlet 116 than at the media flow inlet 106.

It can also be seen from the figures that all three absorber elements 108 each have a plurality of resonator chambers 117a, 117b and 117c in their wall.

List of reference symbols

100

Pulsation silencer

101

casing

102

Absorber element receiving area

103

Faceplate

104

flange

105

-

106

Media flow inlet

107

Media flow

108

Absorber elements

109

-

110

first change area

111

Centering pin

112

first flow space

113

second change area

114

second flow space

115

-

116

Media flow outlet

117

Resonator chamber

Claims (9)

1. Pulsation silencer (100) for a gaseous media flow (107), which is supplied by a compressor, comprising:

   - a housing (101), which extends along a central axis, having a media flow inlet (106) and a media flow outlet (116);

   - a plurality of sleeve-shaped absorber elements (108), which consist of sound-absorbing material and are arranged concentrically in relation to one another in the housing (101), wherein

   ∘ at least three absorber elements (108) are arranged in an annular manner in relation to one another, wherein at least 80% of the longitudinal extent of the absorber elements (108) overlap one another axially,

   ∘ each sleeve-shaped absorber element (108) possesses an inlet region and an outlet region, which are positioned axially spaced apart from one another,

   ∘ the inlet region of the fluidically foremost absorber element (108a) is connected to the media flow inlet (106) of the housing (101), the outlet region of the fluidically foremost absorber element (108a) is connected to the inlet region of the fluidically subsequent absorber element (108b) and so forth, and the outlet region of the fluidically rearmost absorber element (108c) is connected to the media flow outlet (116) of the housing (101),

   o in each case a flow space (112, 114) for the media flow (107) remains between in each case radially adjacent wall sections of various absorber elements (108).
2. The pulsation silencer (100) according to Claim 1, characterised in that the absorber elements (108) are formed to be rotationally symmetrical and engage in one another in a telescopic but axially fixed manner.
3. The pulsation silencer (100) according to any one of Claims 1 to 2, characterised in that the inlet region and the outlet region are each arranged on the end faces of the absorber elements (108), and in that the flow direction of the media flow (107) experiences a direction reversal of 180° in each case during transition from one absorber element to the next absorber element.
4. The pulsation silencer (100) according to any one of Claims 1 to 3, characterised in that the fluidically foremost absorber element (108a) is arranged radially internally in the housing (101) and the fluidically rearmost absorber element (108c) is arranged radially externally in the housing (101).
5. The pulsation silencer (100) according to Claim 4, characterised in that the housing (101) possesses an absorber element receiving region (102) having a circular cross-section, in that the media flow inlet (106) is formed as an inlet opening situated centrally in an end plate (103), which inlet opening opens into a central inlet region of the fluidically foremost absorber element (108a), and in that the media flow outlet (116) is formed as a flange (104) on the housing (101), which flange (104) lies opposite the end plate (103) and has an annular outlet region of the fluidically rearmost absorber element (108c) opening into it.
6. The pulsation silencer (100) according to any one of Claims 1 to 5, characterised in that the ratio of the axial length to the maximum cross-sectional extent of each absorber element is smaller than 2.5, wherein this ratio is preferably smaller than 0.75 in the radially outermost absorber element (108c).
7. The pulsation silencer (100) according to any one of Claims 1 to 6, characterised in that the ratio of the axial outer total length of the pulsation silencer to the length of the path travelled by the media flow (107) through the absorber elements (108) is smaller than 1.
8. A compressor for compressing gaseous media, comprising a compressor and a pulsation silencer (100) arranged fluidically downstream of the compressor, which pulsation silencer (100) is formed according to any one of Claims 1 to 7.
9. The compressor according to Claim 8, characterised in that the compressor is formed as a screw compressor or twin-screw compressor.

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