CA2197721A1 - Jet noise silencer - Google Patents
Jet noise silencerInfo
- Publication number
- CA2197721A1 CA2197721A1 CA 2197721 CA2197721A CA2197721A1 CA 2197721 A1 CA2197721 A1 CA 2197721A1 CA 2197721 CA2197721 CA 2197721 CA 2197721 A CA2197721 A CA 2197721A CA 2197721 A1 CA2197721 A1 CA 2197721A1
- Authority
- CA
- Canada
- Prior art keywords
- fluid
- silencer
- chamber
- flow rate
- swirler
- 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.)
- Abandoned
Links
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
- F01D25/30—Exhaust heads, chambers, 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
- 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
- F01N1/081—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling by passing the gases through a mass of particles
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/161—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general in systems with fluid flow
-
- 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
- F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
- F01N2240/20—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a flow director or deflector
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Fluid Mechanics (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Exhaust Silencers (AREA)
Abstract
A device is invented to attenuate excessive noise generated by a free jet during high pressure fluid (a gas or a vapor) release. The silencer consists of a chamber surrounded by perforated walls, and filled with a granular packing which creates large contact surface with the fluid flowing through the chamber. The high pressure energy of fluid is effectively dissipated by the friction between the fluid and the surface of solid packing. The fluid, before it enters the chamber, is swirled by motionless vanes in the silencer swirler. The swirling distributes uniformly the fluid through the granular packing in the chamber. The fluid flow rate can be controlled by the valve installed upstream of the swirler. The flow rate during first period of blowdown can be kept constant in spite of the pressure drop of evacuated fluid. This option of the controlled fluid rate would allow for small size of the silencer without increasing time required for full discharge of the fluid, so the silencer is amenable to portable application.
The jet noise silencer can find application in the installations operating with high pressure, e.g., power plants, chemical plants, pipelines systems, cryogenic facilities, compressor stations, etc.
The jet noise silencer can find application in the installations operating with high pressure, e.g., power plants, chemical plants, pipelines systems, cryogenic facilities, compressor stations, etc.
Description
2 1 9772 ~
JET NOISE SILENCER
Abstract of the Invention A device is invented to attenuate excessive noise generated by a free jet during high pressure fluid (a gas or a vapor) release. The silencer consists of a chamber surrounded by 10 pelrurdled walls, and filled with a granular packing which creates large contact surface with the fluid flowing through the chamber. The high pressure energy of fluid is effectively dissipated by the friction between the fluid and the surface of solid packing. The fluid, before it enters the chamber, is swirled by motionless vanes in the silencer swirler. The swirling distributes uniformly the fluid through the granular packing in the chamber. The fluid flow rate can be controlled by the 15 valve installed upstream of the swirler. The flow rate during first period of blowdown can be kept constant in spite of the pressure drop of evacuated fluid. This option of the controlled fluid rate would allow for small size of the silencer without increasing time required for full discharge of the fluid, so the silencer is amenable to portable application.
The jet noise silencer can find application in the installations operating with high 20 pressure, e.g., power plants, chemical plants, pipelines systems, cryogenic facilities, compressor stations, etc.
Field of the Invention The invention relates to attenuation of high level noise generated by a jet of a high 25 pressure gas or vapor, referred to later as a "fluid", released into the atmosphere.
Background of the Invention Many industrial processes require release of large volume of fluid at high pressure into the atmosphere. The fluid is released from safety or relief valves installed e.g., in power plants, 30 chemical plants, cryogenic facilities, compressor stations, gas metering stations, etc. Fluid 2 1 q772 1 pressures can reach e.g. 15 MPa and the noise generated by the jet can approach an A-weighted sound level of 150 dB. The severe noise of the jet is recognized as a form of pollution which is the subject to regulations, especially in populated areas. Devices are needed to obtain the jet noise at acceptable levels. However, most of commercially available silencers are very large and 5 expensive.
The invented silencer is simple to manufacture, effective and has small dimensions. Its operation is based on the concept of attenuating the noise of fluid jet at the source, which is mostly the high jet velocity resulting from conversion of the fluid high pressure energy. This conversion process progresses in the silencer as fluid flows through the silencer chamber filled 10 with the granular packing material. Due to large friction between fluid and surface of packing material, fluid flow is throttled and the pressure energy is fluently ~1issiratin9~ preventing from development of high fluid velocities. A spacious volume of uniform packing in the silencer chamber has no macro geometrical discontinuities, what eliminates occurrence of vibrations or oscillations which might contribute to noise generation. Small size of the solid packing material is 15 pertinent to noise generation at high frequencies, which is less harmful and easier to attenuate.
Summary of the Invention The invented silencer attenuates the excessive noise generated by a free jet during high release of pressure fluid. The silencer can be used for a range of pressures, exceeding 5 MPa, 20 and for fluid rate releases, which may exceed 100 kg/s.
Attenuation of jet noise occurs as the fluid flows through the silencer chamber made of the inlet and outlet perforated walls and filled with tightly packed granular material. The geometric configuration of the chamber is such that the total cross section area of perforation openings at the chamber outlet is appropriately larger than the total cross section area of 25 perforation openings at the chamber inlet. This condition can be fulfilled for different shapes of the chamber inlet and outlet walls. These walls should be concentric, and they can have either identical geometrical shapes such as the frustum of cones, cone, cube, pyramid, or they can be any combination of the said shapes, e. 9. inlet wall is a cone and outlet wall is a frustum of cone - 219772l with different inclination angle. The ultimate design of the chamber shape depends on the properties of the released jet, effectiveness and fabrication cost.
A granular filling of the silencer chamber creates a large surface of contact with the fluid flowing through the chamber. As the fluid propagates through the chamber, its high pressure S energy is effectively dissipated due to the friction between the fluid and the large solid surface of packing. In order to avoid excessive motion of filling particles caused by fluid flow, which can damage the particles, compact packing is required.
Before the fluid enters the chamber, it is swirled by motionless vanes of the silencer swirler located in the stack upstream of the chamber, close to the chamber inlet. Swirling helps 10 to distribute the fluid entering the inner wall of silencer in uniform way and, consequently, through the packing space in the chamber.
The silencer can operate in two optional modes: with the non-controlled fluid flow rate during relatively small releases or with the controlled flow rate through the silencer. The fluid flow rate can be controlled with the valve installed downstream of the swirler. The opening of the 15 valve can be controlled (programmed) to maintain the following flow rate schedule: during the controlled flow rate release, fluid flow rate is reduced and kept constant in the first period of the release, in spite of the pressure drop of evacuated fluid. This maintained constant flow rate, which is below the maximum flow rate attainable with the initial high pressure level in the evacuated fluid, prevents the excessive jet noise generation during the first phase of the 20 discharge. As the pressure in the evacuated fluid decreases, valve opening can be gradually increased to compensate for the initial reduced flow rate. As a result, the total evacuation time is not extended, and the maximum noise level generated in the very first period of evacuation is avoided. This strategy of the controlled flow rate allows for small size of the silencer. As the size and weight of the silencer is small, it can be easily transported, e.g., as a mobile silencer unit.
2~ The fluid leaving the silencer flows into the shroud of cylindrical or divergent cone shape.
The shroud is used to further reduce the noise and direct vertically the expanded jet into atmosphere.
The silencer has simple construction and is easy to fabricate.
21 ~7~ l D~eailed Description Further details of the invented silencer are given in the following, non-limiting example.
The invention is described with reference to the acco",pan~;ng Figure 1, which is a half side 5 view and a half side view of a section of a silencer, according to the invention.
Referring to Figure 1, the silencer must contain a chamber which is formed by the perforated frustum of outer (outlet) cone 1 and perforated frustum of inner (inlet) cone 2, and the non-perforated annular plate 3. Packing contained within the chamber consists of plurality of separate pieces, tightly packed, made of the erosion, stress and thermal resistive solid material.
I0 The frustum of cones 1 and 2 are fastened to plate 3 with flanges 4 and 5. The conical shroud 6 is fastened to plate 3 with flange 7. The plate 3 is also used as a flange to connect the chamber ~, with diffuser 8, which reduces the flow velocity of the fluid. The diffuser 8 contains swirling vanes 9. The swirling results in uniform distribution of fluid within the hemispherical solid angle at the diffuser outlet. A cylindrical connector 10, with flange 11, connects diffuser 8 with the blowdown 15 valve 12. The valve controls the flow rate of fluid through the chamber. Noise sensor could be used to control the valve opening; the valve opens more as noise level decreases. As an alternative to the noise sensor, other sensors could be used, e.g., a pressure sensor; which increases valve opening in the second phase of evacuation, when pressure in evacuated fluid decreases. The silencer described above is mounted on the vertical stack used, for discharge of 20 fluid.
JET NOISE SILENCER
Abstract of the Invention A device is invented to attenuate excessive noise generated by a free jet during high pressure fluid (a gas or a vapor) release. The silencer consists of a chamber surrounded by 10 pelrurdled walls, and filled with a granular packing which creates large contact surface with the fluid flowing through the chamber. The high pressure energy of fluid is effectively dissipated by the friction between the fluid and the surface of solid packing. The fluid, before it enters the chamber, is swirled by motionless vanes in the silencer swirler. The swirling distributes uniformly the fluid through the granular packing in the chamber. The fluid flow rate can be controlled by the 15 valve installed upstream of the swirler. The flow rate during first period of blowdown can be kept constant in spite of the pressure drop of evacuated fluid. This option of the controlled fluid rate would allow for small size of the silencer without increasing time required for full discharge of the fluid, so the silencer is amenable to portable application.
The jet noise silencer can find application in the installations operating with high 20 pressure, e.g., power plants, chemical plants, pipelines systems, cryogenic facilities, compressor stations, etc.
Field of the Invention The invention relates to attenuation of high level noise generated by a jet of a high 25 pressure gas or vapor, referred to later as a "fluid", released into the atmosphere.
Background of the Invention Many industrial processes require release of large volume of fluid at high pressure into the atmosphere. The fluid is released from safety or relief valves installed e.g., in power plants, 30 chemical plants, cryogenic facilities, compressor stations, gas metering stations, etc. Fluid 2 1 q772 1 pressures can reach e.g. 15 MPa and the noise generated by the jet can approach an A-weighted sound level of 150 dB. The severe noise of the jet is recognized as a form of pollution which is the subject to regulations, especially in populated areas. Devices are needed to obtain the jet noise at acceptable levels. However, most of commercially available silencers are very large and 5 expensive.
The invented silencer is simple to manufacture, effective and has small dimensions. Its operation is based on the concept of attenuating the noise of fluid jet at the source, which is mostly the high jet velocity resulting from conversion of the fluid high pressure energy. This conversion process progresses in the silencer as fluid flows through the silencer chamber filled 10 with the granular packing material. Due to large friction between fluid and surface of packing material, fluid flow is throttled and the pressure energy is fluently ~1issiratin9~ preventing from development of high fluid velocities. A spacious volume of uniform packing in the silencer chamber has no macro geometrical discontinuities, what eliminates occurrence of vibrations or oscillations which might contribute to noise generation. Small size of the solid packing material is 15 pertinent to noise generation at high frequencies, which is less harmful and easier to attenuate.
Summary of the Invention The invented silencer attenuates the excessive noise generated by a free jet during high release of pressure fluid. The silencer can be used for a range of pressures, exceeding 5 MPa, 20 and for fluid rate releases, which may exceed 100 kg/s.
Attenuation of jet noise occurs as the fluid flows through the silencer chamber made of the inlet and outlet perforated walls and filled with tightly packed granular material. The geometric configuration of the chamber is such that the total cross section area of perforation openings at the chamber outlet is appropriately larger than the total cross section area of 25 perforation openings at the chamber inlet. This condition can be fulfilled for different shapes of the chamber inlet and outlet walls. These walls should be concentric, and they can have either identical geometrical shapes such as the frustum of cones, cone, cube, pyramid, or they can be any combination of the said shapes, e. 9. inlet wall is a cone and outlet wall is a frustum of cone - 219772l with different inclination angle. The ultimate design of the chamber shape depends on the properties of the released jet, effectiveness and fabrication cost.
A granular filling of the silencer chamber creates a large surface of contact with the fluid flowing through the chamber. As the fluid propagates through the chamber, its high pressure S energy is effectively dissipated due to the friction between the fluid and the large solid surface of packing. In order to avoid excessive motion of filling particles caused by fluid flow, which can damage the particles, compact packing is required.
Before the fluid enters the chamber, it is swirled by motionless vanes of the silencer swirler located in the stack upstream of the chamber, close to the chamber inlet. Swirling helps 10 to distribute the fluid entering the inner wall of silencer in uniform way and, consequently, through the packing space in the chamber.
The silencer can operate in two optional modes: with the non-controlled fluid flow rate during relatively small releases or with the controlled flow rate through the silencer. The fluid flow rate can be controlled with the valve installed downstream of the swirler. The opening of the 15 valve can be controlled (programmed) to maintain the following flow rate schedule: during the controlled flow rate release, fluid flow rate is reduced and kept constant in the first period of the release, in spite of the pressure drop of evacuated fluid. This maintained constant flow rate, which is below the maximum flow rate attainable with the initial high pressure level in the evacuated fluid, prevents the excessive jet noise generation during the first phase of the 20 discharge. As the pressure in the evacuated fluid decreases, valve opening can be gradually increased to compensate for the initial reduced flow rate. As a result, the total evacuation time is not extended, and the maximum noise level generated in the very first period of evacuation is avoided. This strategy of the controlled flow rate allows for small size of the silencer. As the size and weight of the silencer is small, it can be easily transported, e.g., as a mobile silencer unit.
2~ The fluid leaving the silencer flows into the shroud of cylindrical or divergent cone shape.
The shroud is used to further reduce the noise and direct vertically the expanded jet into atmosphere.
The silencer has simple construction and is easy to fabricate.
21 ~7~ l D~eailed Description Further details of the invented silencer are given in the following, non-limiting example.
The invention is described with reference to the acco",pan~;ng Figure 1, which is a half side 5 view and a half side view of a section of a silencer, according to the invention.
Referring to Figure 1, the silencer must contain a chamber which is formed by the perforated frustum of outer (outlet) cone 1 and perforated frustum of inner (inlet) cone 2, and the non-perforated annular plate 3. Packing contained within the chamber consists of plurality of separate pieces, tightly packed, made of the erosion, stress and thermal resistive solid material.
I0 The frustum of cones 1 and 2 are fastened to plate 3 with flanges 4 and 5. The conical shroud 6 is fastened to plate 3 with flange 7. The plate 3 is also used as a flange to connect the chamber ~, with diffuser 8, which reduces the flow velocity of the fluid. The diffuser 8 contains swirling vanes 9. The swirling results in uniform distribution of fluid within the hemispherical solid angle at the diffuser outlet. A cylindrical connector 10, with flange 11, connects diffuser 8 with the blowdown 15 valve 12. The valve controls the flow rate of fluid through the chamber. Noise sensor could be used to control the valve opening; the valve opens more as noise level decreases. As an alternative to the noise sensor, other sensors could be used, e.g., a pressure sensor; which increases valve opening in the second phase of evacuation, when pressure in evacuated fluid decreases. The silencer described above is mounted on the vertical stack used, for discharge of 20 fluid.
Claims (7)
1. The silencer consists of a valve with the controlled and programmed opening, a stationary swirler to swirl a fluid jet, a silencer chamber through which the fluid jet is discharged and the exit shroud.
2. The silencer, in which a fluid flow rate through the silencer chamber can be programmed and appropriately adjusted during the entire period of fluid discharge.
3. The silencer, which is portable.
4. The silencer chamber is characterized by:
(a) The chamber inlet and outlet walls, which are both made of the perforated material containing plurality of perforations with the same opening size between 3 and 10 mm (b) The chamber inlet and outlet walls which are concentric.
c) The chamber inlet and outlet walls which are of identical geometry and they both assume any of the geometrical shapes listed below, (i-viii), or the chamber inlet and outlet walls which are of different shapes, representing any combination of the listed below shapes, (i-viii):
(i) partial sphere (ii) cylinder (iii) cone or frustum of cone (iv) pyramid or frustum of pyramid (v) polyhedron (vi) paraboloid (vii) cube (viii) rectangular d) A volume between the inlet and outlet walls of the silencer chamber, which is tightly packed with granular material characterized by:
(i) the uniform or different sizes of granules (ii) the size of uniform granules or the minimum size of non-uniform granules is larger than the perforation openings
(a) The chamber inlet and outlet walls, which are both made of the perforated material containing plurality of perforations with the same opening size between 3 and 10 mm (b) The chamber inlet and outlet walls which are concentric.
c) The chamber inlet and outlet walls which are of identical geometry and they both assume any of the geometrical shapes listed below, (i-viii), or the chamber inlet and outlet walls which are of different shapes, representing any combination of the listed below shapes, (i-viii):
(i) partial sphere (ii) cylinder (iii) cone or frustum of cone (iv) pyramid or frustum of pyramid (v) polyhedron (vi) paraboloid (vii) cube (viii) rectangular d) A volume between the inlet and outlet walls of the silencer chamber, which is tightly packed with granular material characterized by:
(i) the uniform or different sizes of granules (ii) the size of uniform granules or the minimum size of non-uniform granules is larger than the perforation openings
5. A swirler of the silencer is located upstream of the silencer chamber, at the chamber inlet.
The swirler comprises the stationary vanes to swirl the fluid and ensure uniform fluid distribution in the silencer chamber inlet.
The swirler comprises the stationary vanes to swirl the fluid and ensure uniform fluid distribution in the silencer chamber inlet.
6. A valve of the silencer is used in the mode of controlled flow operation. The valve is equipped with an automatic control system which is characterized by:
a) The program which controls the valve opening appropriately to adjust the flow rate of fluid entering the swirler in such a way that during the entire period of fluid discharge the generated noise does not exceed the required level.
b) The control system is programmed to reduce the flow rate at the beginning of the discharge to prevent generation of the maximum attainable noise level, and to increase low rate in the last phase of the discharge, when generated noise is below the required level. This mode of flow rate control results in maintaining almost constant noise level during the entire fluid discharge.
a) The program which controls the valve opening appropriately to adjust the flow rate of fluid entering the swirler in such a way that during the entire period of fluid discharge the generated noise does not exceed the required level.
b) The control system is programmed to reduce the flow rate at the beginning of the discharge to prevent generation of the maximum attainable noise level, and to increase low rate in the last phase of the discharge, when generated noise is below the required level. This mode of flow rate control results in maintaining almost constant noise level during the entire fluid discharge.
7. The shroud of the silencer can be a cylindrical or a reversed frustum of cone shape.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2197721 CA2197721A1 (en) | 1997-02-17 | 1997-02-17 | Jet noise silencer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2197721 CA2197721A1 (en) | 1997-02-17 | 1997-02-17 | Jet noise silencer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2197721A1 true CA2197721A1 (en) | 1998-08-17 |
Family
ID=4159952
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2197721 Abandoned CA2197721A1 (en) | 1997-02-17 | 1997-02-17 | Jet noise silencer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2197721A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120202407A1 (en) * | 2011-02-04 | 2012-08-09 | Phuong Taylor Nguyen | Air Blast Blowdown Silencer System for Blast Pot |
-
1997
- 1997-02-17 CA CA 2197721 patent/CA2197721A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120202407A1 (en) * | 2011-02-04 | 2012-08-09 | Phuong Taylor Nguyen | Air Blast Blowdown Silencer System for Blast Pot |
| US8708779B2 (en) * | 2011-02-04 | 2014-04-29 | Phuong Taylor Nguyen | Air blast blowdown silencer system for blast pot |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |