Present DayDust Suppression SystemsA CASE STUDYBY PRASHANT MEHROTRA &MUKESH DUBEYDEPARTMENT OF MECHANICAL ENGINEERINGG.B.T...
The Dust Suppression System is meant to suppress the coal dustgenerated during transfer of coal at feed/discharge points o...
water pump. The metering pump will stop the operation by sensinglow chemicals in tank. After insuring proper level the sol...
driven acoustic oscillator for fogging liquids by passing them througha field of high frequency sound waves. This is accom...
Alternate TechnologiesFor EffectiveDust SuppressionA CASE STUDYBY MAKARAND JOSHIDEPARTMENT OF MECHANICAL ENGINEERINGR.G.TE...
This system uses water and compressed air to produce micron sizeddroplets that are able to suppress respirable dust withou...
LIGHT SCATTERING PROPERTY BASED SUPPRESSIONSYSTEMS:-When air-borne dusts or suspended particulate are irradiated withlight...
DUST SUPPRESSION SYSTEMS BASED ON SOUND:-The sound generator generates sound beam. The stainless steelreflector on the oth...
SYSTEMS FOR DUST CONTROL INTHERMAL POWER PLANTA CASE STUDYBY        ANKUSH               KUMAR             &         SUMIT...
STAGES FOR DUST CONTROL IN POWER PLANT:-                                                    Stage 1:-Whencoal             ...
Stage 5:-Last stage is unloading from relay to boiler section.Usualamount of moisture is added for moisture removal since ...
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The above fig is an important device for dust collection at each andevery level of a thermal power plant.It is a centrifug...
cONCLUSION:-A wet centrifugal dust collector with automaticdischarge can reduce airborne dust particles and minimize water...
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report: DUST IDENTIFICATION & SUPPRESSION SYSTEMS

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report: DUST IDENTIFICATION & SUPPRESSION SYSTEMS

  1. 1. Present DayDust Suppression SystemsA CASE STUDYBY PRASHANT MEHROTRA &MUKESH DUBEYDEPARTMENT OF MECHANICAL ENGINEERINGG.B.TECHNICAL UNIVERISTYJHANSIThe literature study of modern day dust suppression system revealsthat many thermal power plants use coal as their fuel. To handle thecoal, each power station is equipped with a coal handling plant. Thecoal has to be sized, processed, and handled which should be doneeffectively and efficiently. While working in the coal handling plantthe major factor which reduces staff efficiency is the workingenvironment i.e. a dusty atmosphere. Lots of care is always taken toreduce dust emission.Generally all systems used in power station coal handling plants arewet dust suppression systems. In this paper the reasons for failure ofthese type of dust suppression system are discussed. The remedy forthe improvement of this system is also given in this paper. Theexisting system can be easily modified by using ultrasonic system.The spray discharge should be proportional with dust emission. Thesolenoid valve should be open with proportion with quantity of dustgeneration. 1
  2. 2. The Dust Suppression System is meant to suppress the coal dustgenerated during transfer of coal at feed/discharge points ofconveyors in various transfer towers. There are several existingmethods of controlling dust but many are ineffective, costly and havedetrimental effects on plant and machinery. An effective system forthe control of fugitive dust in industry should meet the followingobjectives.1. Must be efficient to meet Health & Safety requirements.2. Be practical and simple in operation.3. Have low initial cost.4. Have low operating costs.5. No adverse effects on product quality or plant and machineryshould be created.But the system used in the plant is not meeting the entirerequirement, especially it does not meet Health & Safetyrequirements.OPERATING PRINCIPLE:-Auto control or manual control governs the system. It has to beinsured that main tank is filled with water. The water is pumped byfeed water pump from main tank to feed water tank and at the sametime metering pump doses proper quantity of chemical. The feedwater pump operation is controlled by float switch automatically.The pump picks up at low level and stopped at high level. Theinterlock with low level of main tank will not allow to pickup the feed 2
  3. 3. water pump. The metering pump will stop the operation by sensinglow chemicals in tank. After insuring proper level the solution pumpswill start. If the pressure increase the pressure relief valve keeps thesystem in recalculation. The sensing system for controlling spray atproper header ensures spraying solution if conveyor is running withcoal. And will not allow spraying solution if conveyors are runningempty.The solenoid valve headers are energized if conveyor isrunning with coal. If all or some of the solenoid valves are notenergized the system will realize pressure through pressure reliefvalve, which protects the system. A solenoid valve is provided withbypass line, which operates when none of the spray header solenoidvalves are operative.Nozzle:-The design of the system is based on a very unique device which canproduce a very dense fog of 1 - 10 micron size water droplets whichliterally blanket the dust source and keep the dust particles frombecoming airborne. It does this at low cost, both from a capital and amaintenance standpoint, while achieving all of the goals statedabove for an ideal dust suppression system. The fogger is an air 3
  4. 4. driven acoustic oscillator for fogging liquids by passing them througha field of high frequency sound waves. This is accomplished bycompressing air upstream of a specially designed converge section ofthe fogger. To further enhance the fogging capabilities, a resonatingchamber in the path of the air stream reflects the air stream back atitself to amplify and complement the primary shock wave. Once thisstanding shock wave is generated, water is delivered through annularorifices where it is first sheared into relatively small droplets. Thesesmall droplets are then carried by the primary air stream into theintense shock wave where the sound energy is converted into workby exploding the droplets into thousands of micron size droplets.After having done its work, the air then escapes around theresonating chamber and carries the droplets downstream in a soft,low velocity fog. The design of this fogger has obvious benefitsregarding the control of respirable dust. 4
  5. 5. Alternate TechnologiesFor EffectiveDust SuppressionA CASE STUDYBY MAKARAND JOSHIDEPARTMENT OF MECHANICAL ENGINEERINGR.G.TECHNICAL UNIVERISTYITM UNIVERSE GWALIORINTRODUCTION:-The existing system is not effective on respirabledust.Typical water droplet sizes are 200 to 600 microns, which aremuch greater than the respirable dust. And it does not operate onthe emission quantity.The spray of the system should be operated onemission quantity.Thus, water sprays can be improved by increasing pressure or bydesigning nozzles which produce smaller droplets.And alsodeveloping the control system which sense quantity of dust. Most ofthe improvements in this direction already have been made. Theproblem with this approach, and one, which prevents muchadditional improvement, is that introduction of very small waterdroplets into an atmosphere.Hence arises the need for alternate dustsuppression tehnologies.ULTRASONIC DUST SUPPRESSION SYSTEMS:- 5
  6. 6. This system uses water and compressed air to produce micron sizeddroplets that are able to suppress respirable dust without adding anydetectable moisture to the process. Ideal for spray curtains tocontain dust within hoppers. Generally the system consists of threemain parts. These are as follows.1. Air compressor units.2. Spray headers with pipe lines & pumping system.3. Control units with electrical systems.The theory behind the Ultrasonic Atomizing System is based onresearch considering a water droplet from a spray that is about toimpinge on a dust particle. The probability of impaction increases asthe size of the water spray droplet decreases. This explains whyconventional hydraulic water sprays are not effective onrespirabledust. With typical diameters of 200-600 microns the droplets aremuch larger than the dusts they are attempting to suppress.Nozzles mounted on or above screen areas will suppress dust cloudsdue to the particulates being encouraged to become air-bournethrough natural vibration and fall of the conveying bulk. 6
  7. 7. LIGHT SCATTERING PROPERTY BASED SUPPRESSIONSYSTEMS:-When air-borne dusts or suspended particulate are irradiated withlight, the light is scattered in all directions. The intensity of lightscattered at any particular angle depends on the wavelength of thelight and the size, volatility, and mass concentration of the dust orsuspended particlesBoth theory and experiment indicate that at a scattering angle ofaround 200 to 300, the size and volatility of respirable coal dustshave a negligible impact on the measured intensity so that thisintensity is directly proportional to the mass concentration of thedust. At an angle of 150, equal concentrations of eitherrespirablecoal dust or diesel particulate matter (DPM) yield equalintensities of scattered light. At larger angles, the intensities fromDPM are significantly greater. Specific angles in the range of 150 to 300offer significant promise for respirable dust or DPM measurementand, possibly, for determination of mass fractions of dust/DPMmixture. 7
  8. 8. DUST SUPPRESSION SYSTEMS BASED ON SOUND:-The sound generator generates sound beam. The stainless steelreflector on the other side reflects the sound beam. The receiverwho is built with sound generator receives the reflected soundbeam. The dust particles absorb some of the energy of sound beamand also deflect sound beam. The sound signal received is inverselyproportional to the dust emission.CONCLUSION:-The existing system is failing due to very lowworking pressure. In addition to this the control of the system is notdepend on the quantity of dust emission.Using ultrasonic spray method existing system can be modified withless effort.And the other two systems based on light and sound aremore effective on dust particles of smaller range compared toultrasonic so they are likely to be more prominently used in thefuture because it is a cost effective time reducing method. 8
  9. 9. SYSTEMS FOR DUST CONTROL INTHERMAL POWER PLANTA CASE STUDYBY ANKUSH KUMAR & SUMITCHAKRABORTYDEPARTMENT OF MECHANICAL ENGINEERINGNIT HAZRATBAL,SRINAGARABSTRACT:-Theaim of the work is to propose measures anddevice methods to reduce and prevent dust at Coal Handling plant(CHP) of a coal fired thermal power plant. This paper discussesqualitative methods for preventing dust including design of a wetcentrifugal dust collector.Since wet dust suppression system uses optimum amount of waterfor suppressing dust, therefuse of dust collector which dischargesdust in the form of slurry is very elegant approach to control dust atlarge scale. Every thermal power plant is equipped of a large CHPwhere coal is handled. Such plants consume large quantity of waterin order to suppress dust properly which is undesirable. Thereforeuse of dust collector units at particular places of CHP plant wheredust particles are airborne is highly recommended, since itdischarges dust in the form of slurry. 9
  10. 10. STAGES FOR DUST CONTROL IN POWER PLANT:- Stage 1:-Whencoal is transportedfrom wagon tippler to reclaimer large amount of dust is generatedand addition of moisture is most efficient technique as water acts asa binding solvent.Diverging nozzles are used for moisture addition.Stage 2:-This is the reclaiming stage.Here water can be futile so windplays an important role as storage area is large.So here blocking windspeed is concentrated upon to prevent dust from being airborne.Sowind shields or wind forests are used.Stage 3:-Reclaimer piles up coal at a large area for storage.At thisstage surface compaction method is used for dust suppression.6-12%water solution of very good binding substance prevents dust frombeing airborne.Moisture is supplied for controlled flow of solutionover coal pile and suppress dust without affecting coal quality.Stage4:-Here dust particle is as low as 1-10 microns.Dust collector isused to reduce concentration as low as 1% in the concerned area.Itdischarges dust in concentrated form to reduce water intake.At thisstage coal is transferred from coal stack through conveyor to relaysection. 10
  11. 11. Stage 5:-Last stage is unloading from relay to boiler section.Usualamount of moisture is added for moisture removal since dust is insmall amount here. 11
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  13. 13. The above fig is an important device for dust collection at each andevery level of a thermal power plant.It is a centrifugal dustcollector. Centrifugal collectors use cyclonic action toseparate dust particles from the gas stream. In a typical cyclone, thedust gas stream enters at an angle and is spun rapidly.The centrifugal force created by the circular flow throws the dustparticles toward the wall of the cyclone. After striking the wall, theseparticles fall into a hopper located underneath.This device uses the principle of dynamic precipitation technique inwhich very high suction pressure suck the dusty air and allowtocentrifuge through it. Centrifugal action separates dust from freshair and fresh air is allowed to escape from other end of dustcollector.The dust collector has a small tank full of water which has two valves.These two springs loaded valves are operated to allow passage ofconcentrated dust and automatic filling of fresh water using sensors.The dust collector uses automatic discharge technique and hencesave time for manual operations for discharging and refilling. Alsodischarge is recycled in order to have minimum water wastage. Thiscentrifugal dust collector is very efficient and requires minimumamount of water since it discharges dust in concentrated form. 13
  14. 14. cONCLUSION:-A wet centrifugal dust collector with automaticdischarge can reduce airborne dust particles and minimize waterwastage. Also other methods of dust collection reduce dust andwater wastage as discussed earlier.This has great impact not only at workplace but also in environment.Proper implementation of dust suppression and prevention methodsreduces health hazards of workers, employees and people residingnearby. Since current situation demands eco-friendly methods ofdust suppression without much water wastage, above mentionedergonomic designs are noteworthy. 14

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