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Non-Destructive Dust Removal

ACOUSTIC CLEANING SYSTEMS...BLACK MAGIC, OR DO THEY REALLY WORK?

THE ROLE OF FREQUENCY AND INTENSITY

The principle behind acoustic cleaning is very simple: sound is a vibration through airthat can be heard. Vibrations are effective at dislodging dust from surfaces, and thesource of the vibration doesn’t matter. If a vibration is imparted to a dust-coated sur-face with enough intensity, dust will be dislodged from that surface, whether thevibration is caused by sound waves or a mechanical impact. Nothing magical aboutacoustic energy...it’s just a source of vibratory energy.

The frequency and intensity of the vibration are critical factors in acoustic cleaning. Tobe effective, the frequency should be low, but not too low, and the intensity of thesound (decibel level) must be great enough to remove the collected particulate.

BHA’s Powerwave® acoustic horns are scientifically designed to produce powerfulpulses of sound energy that will resonate and dislodge dust from fabric filters, boilertubes and heat exchangers, precipitator collecting plates and high voltage discharge elec-trodes, hoppers and dust lines, even SCR catalyst. Acoustic energy has been used suc-cessfully for more than 20 years to improve the efficiency of air pollution controlequipment in many applications, and has even enabled some plant operators to useacoustic horns as their sole cleaning devices!

Typically, the lower the frequency, the more effective a horn will be at dislodging dustor particulate. However, extremely low-frequency sound waves (produced by infrason-ic devices) can be dangerously close to the resonate frequency of the structure or vesseland can cause damage to the structure or loosen or crack welded or bolted connec-tions. Powerwave acoustic horns operate at 75 hertz or above, well above the frequen-cy of the structure, and cannot damage structural components. Low frequency, highdecibel sound is proven to be the most effective at removing particulate, without dam-aging the equipment.

Acoustic cleaning is accomplished through particle displacement, changes in pressurethat break the bond of the particles from themselves and the structure. Lower frequen-cies produce greater displacement (or changes in air pressure) and will clean a largercross sectional area. BHA’s family of acoustic products are engineered and tested toproduce the cleaning power you need, with moderate cost, low maintenance, and highefficiency. We publish the frequency and intensity ratings of our horns, so you knowwhat you’re getting. (See inside)

Compressed air is introduced to the driverassembly of an acoustic horn. The pressurebuilds up rapidly, causing the diaphragmplate to flex.

Air escapes past the flexed titaniumdiaphragm plate into the horn, reducing the air pressure in the driver. The pressurereduction allows the diaphragm to snapback quickly, creating a strong pulse in the horn body.

The pulses travel through the horn, wherethey are amplified by the bell shape, andbecome powerful bursts of acoustic energycapable of blasting dust away from surfaces.

Horn Body

Air pressure

Driver

Diaphragm

The length of the horn’s “bell” isone factor that determines the main,or fundamental, frequency of thehorn. The longer the bell, the lowerthe frequency. The horn picturedhas a long, curved bell, and isoften used to dislodge slag fromboiler tubes.

PROVEN APPLICATIONS FOR BHA POWERWAVE® ACOUSTIC CLEANING SYSTEMS

BOILER TUBES/HEAT EXCHANGERSPowerwave horns can be used to supplement or replace steam sootblowers in industrial or utilityboilers. Many boiler operators have found that they can reduce or eliminate opacity spikes associatedwith sootblower use by using Powerwave horns to keep the tubes clean. The horns can be operatedmore frequently than sootblowers, and keep the tubes cleaner without parasitic steam use. Annualmaintenance expenses are much lower than for retractable sootblowers, as Powerwave horns havejust one moving part, a tough titanium diaphragm plate. Powerwave acoustic horns are alsoextremely effective for removing particulate from rotary or tubular heat exchanger surfaces.

BAGHOUSE FABRIC FILTERS/ELEMENTSTraditional fabric filter cleaning methods (shaking, air flow reversal, or pulsing) create motion inthe filters that can shorten filter life by causing abrasion and flexing of the fibers. Acoustic energy isgentle to the fabric, but effectively resonates and dislodges dust accumulations from the filters.Acoustic energy can allow reduced frequency of traditional cleaning cycles, and in some cases caneliminate the need to use any other method of cleaning. (Pulse-jet baghouses usually require sometraditional pulsing, unless BHA-TEX® membrane filters are used.)

PRECIPITATOR COMPONENTSPrecipitator internals are cleaned using either externally-mounted rappers, or internally-mountedrotating hammers. Both types of conventional cleaning systems literally “hammer” the dust free fromthe surfaces, allowing it to fall into the hoppers. Cleaning cycles often result in some re-entrainmentof the dust, and the effect of the mechanical impacts used tend to cause cracks, distortion, andfatigue of the collecting surfaces, along with failures of the discharge electrodes. Powerwave hornsclean these surfaces without imparting mechanical stress and fatigue, and sometimes prove to be soeffective that the conventional rapping systems are no longer necessary.

SELECTIVE CATALYTIC REDUCTION (SCR) EQUIPMENTHistorically, SCR cleaning was done using steam sootblowers, although the parasitic steam usagecould cost many thousands of dollars per year, and sootblower maintenance costs were often high.Because sootblowers are operated infrequently, the amount of ash dislodged is excessive, and canresult in re-entrainment and "puffing" at the stack, as well as reduced catalytic reaction betweensootblowing cycles. Moreover, the action of steam sootblowers tends to erode and shorten the lifeof SCR catalyst. Acoustic energy is a viable, effective, and comparatively inexpensive method forcleaning SCR catalyst. Advantages: lower cost and operating expense, low maintenance cost, andvery small size compared with steam sootblowers.

MATERIAL HANDLING (HOPPERS, FANS, SILOS, DUCTWORK) Powerwave horns are designed in many different configurations that allow them to be used in hoppers,I. D. fans, bins, and ductwork. The more compact models can be used to fluidize dust in pneumaticconveyor lines and hopper emptying valves, while specialized models are used to keep fan bladesclean, balanced, and vibration-free. Acoustic horns can eliminate the need for sledgehammering,rodding out hopper poke holes, or dangerous work unclogging ash vessels.

Fundamental Frequency (Hertz)...................................................75 HzOutput Power Level (Decibels) ....................................................147 dBMaterial. ...................................................................Cast Malleable Iron Weight...........................................................................174 lbs. (78.43 kg)Length.............................................................................92.3”(234.44 cm)Air Consumption..............................................60-80 SCFM @ 70-90 PSI

(28-38 l/s @ 5-6 bar)

ESP-75

DC-75

Fundamental Frequency (Hertz)...................................................230 HzOutput Power Level (Decibels)......................................................150 dBMaterial.........................................................................................Cast IronWeight (one piece bell)..................................................64 lbs. (29.03 kg)Weight (two piece bell)...................................................62 lbs. (28.12 kg)Length......... ......................................................................27.30”(69.3 cm)Air Consumption..............................................60-80 SCFM @ 70-90 PSI

(28-38 l/s @ 5-6 bar)

D-230

D-360D-FluidizerFundamental Frequency (Hertz):................................................220 HzOutput Power Level:.....................................................................150 dBMaterial: ....................................................................Cast Stainless SteelWeight:.............................................................................32 lbs. (14.5 kg)Length...............................................................................15.2”(38.61 cm)Air Consumption..............................................60-80 SCFM @ 70-90 PSI

(28-38 l/s @ 5-6 bar)

Fundamental Frequency (Hertz)...................................................75 HzOutput Power Level (Decibels) ....................................................147 dB Material ....................................................................Cast Malleable Iron

(Stainless steel fabricated cone) Weight...........................................................................114 lbs. (51.71 kg)Length.............................................................................91.9”(233.43 cm)Air Consumption..............................................60-80 SCFM @ 70-90 PSI

(28-38 l/s @ 5-6 bar)

D-75

ACOUSTIC HORN SPECIFICATIONS

Fundamental Frequency (Hertz)...................................................360 HzOutput Power Level (Decibels) .....................................................150 dBMaterial.......................................................................Cast Stainless SteelWeight..............................................................................37 lbs. (16.78 kg)Length............... ................................................................16.25”(41.3 cm)Air Consumption..............................................60-80 SCFM @ 70-90 PSI

(28-38 l/s @ 5-6 bar)

Flange and Tube Installation Options

BHA supplies all the flanges and penetra-tions needed to install horns through thesides of hoppers, bins, or any vesselrequiring cleaning.

Custom throat flange kits from BHA makepositioning horns easy in nearly any location.

Fundamental Frequency (Hertz) ..........................75 HzOutput Power Level (Decibels) ..........................147 dBMaterial ......................................Cast iron/carbon steel

(Stainless steel fabricated cone)Weight ..................................................130 lbs. (58.97 kg)Length ..................................................58.8” (149.35 cm)Height....................................................52.7” (133.86 cm)Air Consumption ......................60-80 SCFM@70-90 PSI

(28-38 l/s @ 5-6 bar)

®

Fundamental Frequency (Hertz): ..........................................125 HzAvg. Power Level <300 Hz (decibels): ..................................145 dBMaterial: ..........................................................................Carbon Steel

**(Stainless steel available;Food Grade available on request)

Maximum Operating Temperature: ........................650° F (343° C)Weight: ..........................................................................40 lbs. (18 kg)Air Consumption: ..........................................50–60 SCFM @ 55 PSI

(23–28 l/s @ 3.8 bar)

AH-10

AH-15Fundamental Frequency (Hertz): ..........................................125 HzAvg. Power Level <300 Hz (decibels): ..................................145 dBMaterial: ..........................................................................Carbon Steel

**(Stainless steel available)Maximum Operating Temperature: ........................650° F (343° C)Weight: ..........................................................................70 lbs. (32 kg)Air Consumption: ................................................65 SCFM @ 65 PSI

(31 l/s @ 5.5 bar)

Fundamental Frequency (Hertz): ..........................................125 HzAvg. Power Weighted Mean Frequency:..............................164 HzAvg. Power Level <300 Hz (decibels): ..................................145 dBMaterial: ..........................................................................Carbon Steel

**(Stainless steel available)Maximum Operating Temperature: ........................650° F (343° C)Weight: ..........................................................................110 lbs. (50kg)Air Consumption: ................................................75 SCFM @ 75 PSI

(35 l/s @ 6.2 bar)

AH-25A

ACOUSTIC HORN SPECIFICATIONS

The D-fluidizer horn is installed on a tube to facilitate hopper mountingat the correct angle in order to direct the sound energy to the problem area.

Mouth-flange mountings are used for roofs of baghouses or silos.

®

Powerwave™ Horns are easier to install than you mightthink. Most horns are designed to fit inside existingopenings, like access doors, inspection ports, or pokeholes. Standard plant air can be used to drive the horns;instrument quality air is not required.

Installation Options

Horns can be chain-hunginside baghouses or vessels,although most operatorsprefer to have easier on-lineaccess to the drivers.

Air supply requirements are fairlysimple, and are customized foreach installation. Controls can be as sophisticated as rapper controls, or as simple as sole-noids and timers.

Horn Driver

StainlessSteel Flex

Hose

Solenoid Valve

Locking BallValve

Regulator Air Filter

Mouth-flange mountingsare also used on precipitator roof

installations.

The D-Series horns utilize tube mountings tofacilitate ease of instal-

lation on vessel wallsand other enclosures.

Note: For higher temperatures or corrosion resistance, hornscan be manufactured from various alloys.

tube wall

horn

POWERWAVE® ACOUSTIC CLEANING SYSTEMS ARE USED IN MANY APPLICATIONS...EL

ECTR

OSTA

TIC

PREC

IPIT

ATOR

S

◆ Supplements or replaces rappers or tumbling hammers.◆ Eliminates hopper bridging, ratholing, and sidewall buildup.◆ Reduces re-entrainment.◆ Reduces mechanical fatigue of collecting and discharge electrodes.◆ Increases electrical field strength and collection efficiency.

BAGH

OUSE

S

◆ Enhances dust removal from filter elements or bags.◆ Reduces differential pressure.◆ Reduces filter wear (especially in shaker or reverse air baghouses).◆ Helps eliminate blinding.◆ Increases filter life expectancy. Powerwave acoustic horns eliminate common material buildup problems in bins, hoppers, silos, and

pneumatic conveying lines. Easily installed through poke holes or access doors, Powerwave horns provideintense acoustic energy to break up and remove blockages and stubborn deposits, without the mechanicalfatigue caused by vibrators, shakers, or sledgehammers.

FlangeMounting

Powerwave acoustic horns provide excellentcleaning of rotary or tubular heat exchangers.

Powerwave acoustic horns offer reduced SCRmaintenance costs, as compared to cleaningwith sootblowers.

Supplement (or eliminate) sootblowers withacoustic energy! Horns are supplied in a varietyof materials for operation in high temperatures.

Powerwave acoustic horns can be chain-hunginside baghouses to provide effective cleaningof filters, without the abrasion and flexing.

Powerwave horns cleaned the internal componentsof this precipitator so well, the plant stoppedusing the conventional tumbling hammers.

Viewing the roof of a precipitator that is cleanedusing only Powerwave acoustic horns.

Powerwave horns can be positioned in existingsootblower openings.

Compact, curved Powerwave horns can easilybe retrofit in existing boiler access doors.

Powerwave horns can be positioned across catalyst beds to remove flyash without the need for sootblowers.

◆ Increases catalyst exposure to flue gases. ◆ Reduces or eliminates sootblower use, steam consumption.◆ Dramatically reduces maintenance requirements.◆ Reduces catalyst erosion.

SCREQUIPM

ENT

◆ Stops bridging, arching, or ratholing in hoppers, bins. ◆ Eliminates fatigue and cracks caused by vibrators. ◆ Eliminates “sledgehammering” of stubborn clogs.◆ Eliminates hazardous “rodding” or cleaning jobs.

HOPPERS, M

ATERIALHANDLING

BOILER

TUBES

ANDA

IRH

EATERS

Powerwave AH-25 horns keep this baghouseoperating at low differential pressure and highcollection efficiency.

◆ Keeps heat transfer surfaces clean for maximum heat rate efficiency.◆ Reduces or eliminates sootblower use, steam consumption.◆ Dramatically reduces maintenance requirements.◆ Increases air heater efficiency.◆ Extends boiler duty cycles.

ACCESSORIES

The Powerwave ® Thermal Wrap isdesigned to easily install around theexposed bell sections of the acousticcleaner, keeping the process gastemperature inside the bell fromdropping below the dew point. Thehigh temperature conditions found inSCRs, baghouses, boilers, and pre-cipitators are areas where thePowerwave Thermal Wrap could pro-vide benefits to the operation of theacoustic cleaning system.

The Powerwave ® Insulator is aneffective way to minimize externalnoise created by acoustic cleaners inareas where external noise levelsare a concern. Also, on high temper-ature applications where the temper-ature of the external parts on theacoustic cleaner are a safety issue,the Powerwave Insulator can elimi-nate danger to personnel and protectthe acoustic cleaner from condensa-tion and corrosion.

The PVS™ (Powerwave VerificationSystem) is designed to detect a fail-ure of acoustic cleaners in a multi-horn system. This detection can pro-vide an immediate warning to plantpersonnel of a potential malfunction.The PVS system is capable of beingused in high temperature and dustyenvironments, such as SCRs, bag-houses, boilers, and precipitators.

For additional information, call your BHA account representative at our toll free number, 800-821-2222.

P6MK200 Rev. C Lit. No. 1136 7/11/03

8800 East 63rd Street • Kansas City, Missouri USA 64133800-821-2222 • +1-816-356-8400 • Fax +1-816-353-1873

www.bhagroup.com • info@bhagroup.com

Other BHA Manufacturing Facilities: Slater, Missouri USANewport News, Virginia USA, and Folkston, Georgia USA. BHA has service and technical

engineers in the United States, Mexico, Canada, Australia, and Japan

GERMANY +49-2528+300 e-mail: info-germany@bha.com

SPAIN +34-93-720-7676 e-mail: info-spain@bha.com

SWITZERLAND +41-62-386-7777 e-mail: info-switzerland@bha.com

MEXICO +52-449-9732140 e-mail: info@bha.com

PHILIPPINES +63-2-753-3555 e-mail: info-pacific@bha.com

CHINA +86-21-6357-7100 e-mail: info-china@bha.com

UNITED KINGDOM +44-01254-268900 e-mail: info-uk@bha.com

INDIA +91-20-567-8500 e-mail: info-india@bha.com

BRAZIL +55-48-225-6601 e-mail: info@bha.com

CANADA +819-374-0111 e-mail: plambert@bha.com

ITALY +39-31-970-359 e-mail: pgrimoldi@bha.com

BHA KNOWS ACOUSTIC CLEANING SYSTEMS...WITH OVER 20 YEARS EXPERIENCE IN THE FIELD

Acoustic Cleaning Systems Help To:◆ Increase production by maximizing equipment performance.◆ Decrease energy costs resulting from high differential pressure in baghouses.◆ Improve performance of precipitators with poor electrical field strength.◆ Reduce excessive material buildup which leads to unscheduled maintenance expenses and downtime.◆ Reduce material flow problems.

POWERWAVE ACOUSTIC HORN ADVANTAGES◆ Low fundamental frequencies and high decibel output produces more energy for superior cleaning.◆ Increased power means each horn cleans more surface area. ◆ Horns are constructed with superior quality steel bells and drivers. Stainless steel is also available for high temperature,

corrosive, and food grade applications.◆ Ease of installation through existing openings and access doors.◆ Simple, inexpensive maintenance (only one moving part).◆ No exotic air supply or special plumbing required.◆ Low cost, compared with other cleaning systems.◆ Variety of horn control options available, including existing timers or rapper control systems.

WIDE RANGE OF PROVEN APPLICATIONS◆ Boiler tubes and air heater thermal transfer surfaces◆ Electrostatic precipitators◆ Fabric filter dust collectors (baghouses)◆ Hoppers, bins, silos, pneumatic conveyors, ductwork◆ Selective Catalytic Reduction (SCR) equipment◆ Material handling equipment

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