US3722620A - Silencer - Google Patents

Silencer Download PDF

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Publication number
US3722620A
US3722620A US00163835A US3722620DA US3722620A US 3722620 A US3722620 A US 3722620A US 00163835 A US00163835 A US 00163835A US 3722620D A US3722620D A US 3722620DA US 3722620 A US3722620 A US 3722620A
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United States
Prior art keywords
sections
flow
slots
gas flow
orifices
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
US00163835A
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English (en)
Inventor
J Erskine
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
Original Assignee
Imperial Chemical Industries Ltd
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Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
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Publication of US3722620A publication Critical patent/US3722620A/en
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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30—Injector mixers
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/02—Energy absorbers; Noise absorbers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/02—Energy absorbers; Noise absorbers
    • F16L55/027—Throttle passages
    • F16L55/02709—Throttle passages in the form of perforated plates
    • F16L55/02727—Throttle passages in the form of perforated plates placed parallel to the axis of the pipe

Definitions

  • the present invention relates to apparatus for use as silencing, fluid mixing, and fluid flow-smoothing equipment on chemical plant.
  • This invention is aimed at the provision of a gas flow conduit capable of beneficially controlling the pattern of gas flow therethrough whereby, for example acoustic noise' may be reduced or eliminated, for example in vents and in the hoods of safety suits, and/or better gas flow measurement achieved.
  • the present invention provides a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and the communication between the sections being afforded by slots formed in the wall of the over-lapped terminal portion of the inner flow section, the collective area of the said slots being larger than the cross-sectional area be in either direction.
  • the slots may be discontinuous or may extend around the entire wall.
  • the hollow I cylinder may be conveniently and simply formed by joining together a series of hoops, spaced apart from one another and linked by short lengths of rodding.
  • a further form of the invention comprises a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and the communication between the sections being afforded by orifices formed in the wall of the overlapped terminal portion of the inner flow section, the collective area of the said orifices being larger than the crosssectional area of the flow path provided by the outer flow section, immediately adjacent to the orifices, in combination with flow monitoring apparatus which is positioned downstream of the first and second flow sections.
  • the flow monitoring apparatus may conveniently, for example, be an orifice plate and differential pressure cell or a pitot tube.
  • Another form of the invention comprises a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and the communication between the sections being afforded by orifices formed in the wall of the overlapped terminal portion of the inner flow section, the collective area of the said orifices being larger than the crosssectional area of the flow path provided by the outer flow section immediately adjacent to the orifices, included in fluid mixing apparatus.
  • the present invention also provides a method of reducing or eliminating acoustic noise caused by gas flow which comprises interposing in the path of the gas flow a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and the communication between the sections being afforded by slots'formed in the wall of the overlapped terminal portion of the inner flow section, the collective area of the said slots being larger than the cross-sectional area of the flow path provided by the .outer flow section immediately adjacent to the slots.
  • the present invention also provides a method of mixing at least two fluids which comprises providing a gas flow conduit comprising first and second sections in series,'through both of which one of the fluids flows, terminal portions of the sections being in overlapping relation with annular clearance therebetween and the communication between the sections being afforded by orifices formed in the wall of the overlapped terminal portion'of the inner flow section, the collective area of the said orifices being larger than the cross-sectional area of the flow path provided by the outer flow section immediately adjacent to the orifices, and flowing a second fluid past the zone of exit of the first fluid from the orifices.
  • FIG. 1 is a perspective view of the inner section of a gas flow conduit according to the invention
  • FIG. 2 is a side elevation of a gas flow conduit
  • FIG. 3 is a schematic plan of a gas flow conduit
  • FIG. 4 is a diagram illustrating the effect of a gas flow conduit on the measurement of fluid flow rates
  • FIG. 5 is a side elevation of a gas flow conduit arranged for mixing condensible fluids
  • FIG. 6 is a side elevation of a gas flow conduit arranged as a vent acoustic silencer
  • FIG. 7 is a side elevation of a gas flow conduit acting as an acoustic silencer for a safety suit.
  • one form of the inner section of a gas flow conduit consists of a hollow tube 1, a
  • section 2 of its wall being solid and a further section 3 of the wall being perforated with transverse slots 4.
  • the end 5 of the tube 1 which is adjacent to the slots 4 is solid.
  • the opposite end 6 is open.
  • FIG. 2 illustrates a gas flow conduit forming part of a pipe line.
  • the conduit consists of a hollow tube 1 within the pipe line 11, a series of hoops 8 being attached to the tube by interconnecting rods 7.
  • the final hoop 9 is solid.
  • the collective area'of the slots formed by the hoops 8 is greater than the cross-sectional area of the annulus formed by pipe 11 around tube 1 and into which the gas emerges from the slots.
  • the hollow tube 1 is positioned in a neck 10 of the pipe line 11 by means of a flange 12.
  • a fluid e.g. oxygen
  • the fluid exits from the tube through the hoops 8.
  • FIG. 3 illustrates a further arrangement of a gas flow conduit forming part of a pipe line.
  • the pipe line 11 has a section 13 of wider diameter intowhich is fitted a hollow tube 1 provided with a series of slots 4.
  • the end 6 of the tube is open, and end 5 is solid.
  • the collective area of the slots 4 is greater than the cross-sectional area of the annulus formed by pipe 13 around the tube 1.
  • FIG. 4 The effect of the gas flow conduit of FIG. 2 on gas flow perturbations is illustrated in FIG. 4.
  • Twoorifice plates A and B were inserted in a pipe line, the plates being separated by a right angle bend. Measurements of a flow of oxygen were taken at each orifice plate, each of which ideally should record the same flow rate.
  • the flow rates were plotted as shown in FIG. 4.
  • Line A represents the theoretical and'curve B shows the actual In operation, two different fluids are flowing in lines 11 and 14 respectively in the direction of the arrows in FIG. 5.
  • the fluid in line 14 encounters the solid end 5 of tube 1 and is forced into the widened section 13 of the tube 11 through the slots 4, where it encounters and mixes with the fluid from line 11.
  • FIG. 6 illustrates an arrangement of a gas flow conduit acting as a vent acoustic silencer.
  • the hollow tube 1 is provided with slots 4, a solid end 5 and, up stream from the slots, with a pressure reducing valve 15.
  • the hollow tube is inserted in a vent 16 which is open to atmosphere, the hollow tube being positioned so that the 7 slots 4 are open to the atmosphere.
  • the collective area plot obtained.
  • Gas flow conduits according to the invention were fitted on the upstream side of each orifice plate and readings of oxygen flow were again taken.
  • Curve C shows the plot of these readings showing that the conduits have considerably reduced the fluctuations caused by the perturbations and brought the readings very close to the theoretical.
  • This form of silencer' has been found to reduce the acoustic noise of a'fluid flow by up to 25 db more than conventional silencers and moreover has been found to operate at much higher temperatures than conventional silencers, because conventional sound absorbtion materials, e.g. glass wool and stillite, suffer damage at high temperatures and in a system which can be saturated with water (either carried in-a gas or from rain) these materials tend to collapse and so become ineffective.
  • conventional sound absorbtion materials e.g. glass wool and stillite
  • FIG. 7 illustrates an arrangement of a gas flow conduit acting as an acoustic silencer in the plastic hood of a safety suit, such as might be used in a dangerous atmosphere.
  • the flexible tubing 1 enters the hood 17 of a safety suit and it is provided-with slots 4 and a solid end 5
  • This'silencer greatly increases the time for which the hood can be comfortably worn.
  • air fed to the hood through the open end of a flexible tube causes considerable acoustic noise which very quickly discomforts the wearer of the hood.
  • the hood cannot'be worn for more than an hour at a time and the hearing of the wearer may be affected for some time thereafter. Fitting the silencer shown in FIG. 7 to the hood increases the length of time. for which the hood can be worn without discomfort by 4 to 8 hours.
  • a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and slots formed in the wall of the overlapped terminal portion of the inner flow section affording communication between the sections, the collective area of the said slots being larger than the crosssectional area of the flow path provided by the outer flow section immediately adjacent to the slots.
  • a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween, and orifices formed in the wall of the overlapped terminal portion of the inner flow section affording communication between, the sections, the collective area of the said orifices being larger than the cross-sectional area of the flow path provided by the outer flow section immediately adjacent to the orifices, in combination with flow monitoring apparatus which is positioned downstream of the first and second flow sections.
  • a gas'flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween, and orifices formed in the wall of the overlapped terminal portion of the inner flow section affording communication between the sections, the collective area of the said orifices being larger than the cross-sectional area of the flow path provided by the outer flow section, immediately adjacent to the orifices, included in-fluid mixing apparatus.
  • YA method of reducing or eliminating acoustic noise caused by gas flow which comprises interposing in the path of the gas flow a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and slots formed in the wall of the overlapped terminal portion of the inner flow section affording communication between the sections, the collective area of the said slots being larger than the cross-sectional area of the flow path provided by the outer flow section immediately ad- 10 jacent to the slots.
  • a method of controlling gas flow along a conduit which comprises causing the gas to flow through a gas flow conduit comprising first and second flow sections in series, terminal portions of the sections being in overlapping relation with annular clearance therebetween and slots formed in the wall of the overlapped terminal portion of the inner flow section affording communication between the sections, the collective area of the said slots being larger than the crosssectional area of the flow path provided by the outer flow section immediately adjacent to the slots.
  • a method of mixing at least two fluids which comprises providing a gas flow conduit comprising first and second sections in series, through both of which one of the fluids flows, terminal portions of the sections being in overlapping relation with annular clearance therebetween, orifices formed in the wall of the overlapped terminal portion of the inner flow section affording communication between the sections, the collective area of the said orifices being larger than the cross-sectional area of the flow path provided by the outer flow section immediately adjacent to the orifices, and flowing a second fluid past the zone of exit of the first fluid from the orifices.
US00163835A 1970-07-28 1971-07-19 Silencer Expired - Lifetime US3722620A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3650570 1970-07-28

Publications (1)

Publication Number Publication Date
US3722620A true US3722620A (en) 1973-03-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00163835A Expired - Lifetime US3722620A (en) 1970-07-28 1971-07-19 Silencer

Country Status (6)

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US (1) US3722620A (de)
JP (1) JPS5513778B1 (de)
DE (1) DE2137830C2 (de)
FR (1) FR2107041A5 (de)
GB (1) GB1352838A (de)
NL (1) NL175225C (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4333499A (en) * 1980-04-15 1982-06-08 Conoco Inc. Pressure dissipation apparatus
GB9007896D0 (en) * 1990-04-06 1990-06-06 Atomic Energy Authority Uk Mixing device
DE29616900U1 (de) * 1996-09-27 1998-01-29 Bosch Gmbh Robert Einrichtung zur differenzdruckabhängigen Steuerung eines Strömungskanals, insbesondere Wassermengenbegrenzer für Wassererhitzer

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3133557A (en) * 1960-11-14 1964-05-19 Aerojet General Co Multiple disc valve

Also Published As

Publication number Publication date
NL175225B (nl) 1984-05-01
DE2137830A1 (de) 1972-02-03
DE2137830C2 (de) 1982-06-03
NL7110264A (de) 1972-02-01
NL175225C (nl) 1984-10-01
GB1352838A (en) 1974-05-15
JPS5513778B1 (de) 1980-04-11
FR2107041A5 (de) 1972-05-05

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