Classifications

• • 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
  • F01N1/10—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling in combination with sound-absorbing materials
• • 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
  • F01N1/02—Silencing apparatus characterised by method of silencing by using resonance
• • 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
  • F01N1/089—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling using two or more expansion chambers in series
• • 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
  • F01N1/24—Silencing apparatus characterised by method of silencing by using sound-absorbing materials
• • 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
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
  • F01N3/28—Construction of catalytic reactors
  • F01N3/2882—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices
  • F01N3/2885—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices with exhaust silencers in a single housing
• • 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
  • F01N2470/00—Structure or shape of exhaust gas passages, pipes or tubes
  • F01N2470/30—Tubes with restrictions, i.e. venturi or the like, e.g. for sucking air or measuring mass 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
  • F01N2490/00—Structure, disposition or shape of gas-chambers
  • F01N2490/15—Plurality of resonance or dead chambers
• • 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
  • F01N2490/00—Structure, disposition or shape of gas-chambers
  • F01N2490/15—Plurality of resonance or dead chambers
  • F01N2490/155—Plurality of resonance or dead chambers being disposed one after the other in flow direction

Definitions

• silencers designed according to conventional principles need to be rather long to become effective.
• a typical example is provided by an exhaust silencer for a stationary gas turbine plant. If the silencer could be made short this would in many cases reduce building costs.
• silencing techniques this is difficult, in particular when a broad-banded silencing, covering all audible frequencies, is required, and when the pressure drop is required to be low.
• silencers to be installed immediately upstream of heat recovery boilers, catalysers, filters, or other apparatuses in a piping system. Such apparatuses add to the horizontal space requirement of the system. At the same time, they are usually designed with rather large transverse dimensions. In such cases, short and wide silencers are called for. In addition, many boilers and other air- or gas-treatment equipment, etc., require an even flow distribution across their inlet in order to function effectively.
• the invention relates to a type of silencer which is particularly fit for such applications.
• the total gas flow to be silenced is split into three or more parallel flows which are then each silenced in individual silencer elements which may be relatively small, separate silencer elements.
• Such elements are preferably designed as reflective silencers, often as reflective and absorptive silencers.
• the invention relates to a silencing apparatus which is throughflowed by a gas and which is arranged within a pipe or duct system, the gas flow at one or more stages within the apparatus being divided into three or more subflows which are preferably substantially parallel to each other, each subflow (or substantially each subflow) throughflowing a silencing element causing at least reflective silencing provided by changes in cross-section area, the silencing elements being arranged beside each other within an outer envelope, at least 80% of the volume inside said envelope being constituted by air, gas and/or solid materials, and at least a major part of said volume having silencing functions, said subflows merging downstream of said silencing elements, either within said apparatus or further downstream in said pipe or duct.
• each subflow throughflow s its own silencing element.
• At least 85%, more preferred at least 90%, and even more preferred at least 95% and up to substantially all of the volume inside the envelope is constituted by air gas and/or solid materials, and at least 60%, preferably at least 70%, and more preferably at least 80%, such as up to 90% or even 95% or higher, of the volume has silencing functions, such as will be explained in the following and understood from the drawings.
• the volume inside the envelope is intended to designate the volume defined radially by the exterior envelope and axially by the volume through which the silencers or the majority of the silencers extend.
• At least one of the cross-section area changes (10) preferably takes place inside the silencing elements, the change in cross-section area preferably being at least by a factor two.
• All or substantially all of the subflows preferably derive from an upstream plenum chamber or from an upstream diffuser . At any rate, it is preferred that all or substantially all of the subflows merge into a downstream plenum chamber immediately or substantially immediately downstream of the silencing elements.
• the outflows from the silencing elements are utilized to contribute to a substantially even inflow across the inlet section of a downstream device which takes advantage of such a substantially even inflow, e.g., a heat recovery boiler/heat exchanger, a catalyst, or a filter or other equipment, either by direct inflow or via a plenum chamber.
• a substantially even inflow e.g., a heat recovery boiler/heat exchanger, a catalyst, or a filter or other equipment, either by direct inflow or via a plenum chamber.
• the attenuation characteristic of the apparatus can be tailored to what is optimal in the particular application. For instance, with reciprocating engines, maximum attenuation is usually required at lower frequencies. With gas turbines, a more even attenuation across the frequency range is normally called for. Conventional gas turbine silencers are usually of the 'splitter type ' , relying mainly on absorptive silencing; it has been found that in many cases such silencers do not provide sufficient low-frequent attenuation. The invention compensates for this deficiency by providing a substantial reflective silencing effect, with moderate or no increase in pressure drop.
• a whole series of silencer apparatuses of different sizes can be derived from, e.g., modulized silencing elements manufactured in a limited number of standardised sizes.
• the assembly of silencing elements can be designed in such a way that the various elements support each other mechanically.
• moderate plate thickness and moderately advanced materials can be selected. All these factors will tend to reduce manufacturing costs.
• the subdivision of the gas flow can be designed to contribute to an even inlet flow distribution to the downstream apparatus. * The distance between the silencer and the downstream apparatus can be made short.
• the silencer element assembly will act as a flow straightener, which protects the downstream apparatus from fluid-dynamic forces which could otherwise compromise its mechanical integrity.
• Fig. 1 is a longitudinal section of a first embodiment according to the invention
• Fig. 2 is a longitudinal section of a second embodiment.
• Fig. 3 is a cross-section of the second embodiment.
• Fig. 4 is a further cross-section of the second embodiment.
• Fig. 5 is a longitudinal section of a third embodiment.
• Fig. 6 is a cross-section of the third embodiment.
• Fig. 7 is a longitudinal section of part of a fourth embodiment.
• Fig. 1 illustrates the principle of dividing a gas flow into three or more parallel flows in silencer elements.
• the silencing apparatus is contained within a casing 1 .
• two inlet pipes or ducts, 2a and 2b lead exhaust gas into the apparatus.
• 2a and 2b could be connected to the two exhaust manifolds of a V-type diesel engine.
• An upstream plenum chamber 4 collects the two incoming gas flows and distributes the merged gas flows to a number of silencer elements 6a ... .
• chamber 4 contributes to overall silencing, by sound reflection at inlet and outlet changes in cross-sectional area, and by function of inserted sound absorptive material, Abs.
• Silencer elements 6a... are divided into two main parts, 7 and 8, being mainly reflective and absorptive in their respective acoustic function.
• the gas flow is distributed to in total nine silencer elements 6a ... i.
• a diffuser 14 is fitted onto pipe 9, to recover dynamic pressure, thereby lowering the pressure drop across the apparatus.
• a heat recovery boiler/heat exchanger, a catalyser, a filter, or other equipment with a large cross sectional area, 12, is placed immediately downstream of the assembly 6a ... of silencing elements.
• the parallel part flows merge once again in plenum chamber 5, downstream of apparatus 12. It can be seen that an even inflow to apparatus 12 is achieved with a vanishing distance to the silencing part.
• Inlet pipe or duct 2 is fitted with a diffuser 15, consisting of a conical first part 16 and a combined axial-radial diffuser 17, into which flow-dividing splitters 18 are inserted.
• This diffuser serves, both recovery of dynamic pressure and even distribution of flow to each of the nine silencer elements 6a ... i.
• Plenum chamber 4 is contained within an end cap 19 and a casing 20, which is made up of four curved parts, for the purpose of minimising shell noise transmitted through the casing.
• curved parts 21 have been fitted onto the plane outer sides of silencer elements 6a, b, c, d, f , g, h, and i.
• thermal insulation (not shown) will be fitted onto the entire casing of the apparatus.
• Figs. 5 and 6 show a third embodiment of the invention.
• each silencer element 6a ... f has been made as a separate unit with its own casing 13.
• a downstream apparatus (boiler etc.), 12 is placed downstream of the silencing element assembly, which contributes to an even inflow distribution to apparatus 12, here via plenum chamber 5.
• two cavities, 22 and 23 exist in the centre, between silencing elements, and outside the elements. Both cavities are closed at the left end by division wall 24, so that there is no flow within the cavities, and so that cavities are acoustically isolated at the left end. At the other end the cavities communicate acoustically with plenum chamber 5, via a perforated plate 25.
• the outer cavity, 23, is empty, so that it acts as a quarter-wave sound absorber. By fitting an extra member into cavity 23, the centre frequency of the absorption could be raised, e.g. to target a known peak in the unattenuated frequency spectrum.
• central cavity 22 is provided with sound absorptive material to attain more broad-banded sound 5 absorption.
• first diffuser part 16 of the apparatus is an outlet diffuser of the gas turbine. Instead of an upstream plenum chamber, the entire flow
• This increased flow-dynamic efficiency can be utilised either for gaining gas turbine shaft work or for selecting rather narrow total flow area within pipes of silencer elements, retaining a pressure drop across the unit which is equal to the pressure drop 25 across a conventional silencer. In this way, especially low-frequent sound attenuation can be enhanced.
• fig. 7 shows the inlet part of a fourth embodiment according to the invention, being a variation of the third embodiment.
• a chamber 4 has been fitted onto 30 inlet diffuser 1 5, to communicate acoustically with the pipe /duct system prior to gas entering silencing elements 6a ... .
• This communication is achieved by providing guide plate 27 with apertures 28.
• Chamber 4, which is not throughflowed, is filled with sound absorptive material, Abs.
• space outside diffuser 15 is utilised for sound attenuation, both high- and low-frequent.
• Silencers can be tailored to many forms of inlets (squared, rectangular, circular) to boilers, catalysers, and filters, with an even flow distribution attained within a short distance in flow direction.
• the acoustic attenuation characteristic can be tailored individually to varying demands for low-, mid- and high-frequent attenuation in a particular application.
• broad-banded low- and mid-frequent attenuation is achieved with reflective sound reduction, and mid- and high-frequent attenuation by sound absorption. Peaks in unattenuated spectra can be targeted by frequency-selective built-in resonators.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Exhaust Silencers (AREA)
• Portable Nailing Machines And Staplers (AREA)
• Rigid Pipes And Flexible Pipes (AREA)
• Pipe Accessories (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1998
  • 1998-12-30 AU AU18696/99A patent/AU1869699A/en not_active Abandoned
  • 1998-12-30 EP EP98963397A patent/EP1060328B1/de not_active Expired - Lifetime
  • 1998-12-30 WO PCT/DK1998/000588 patent/WO1999035378A1/en not_active Ceased
  • 1998-12-30 DE DE69807942T patent/DE69807942T2/de not_active Expired - Lifetime
  • 1998-12-30 AT AT98963397T patent/ATE224003T1/de not_active IP Right Cessation

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