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Presentation toETEs 2015-16

Trends in Ash Handling Systems

Date: 3rd September 2015

TRENDS INASH HANDLING SYSTEMSINDEXChallenges of Ash Handling System in IndiaCriteria for Selection of systemsBottom Ash HandlingFly Ash handlingAuxiliary System

CHALLENGES OF ASH HANDLING SYSTEMS IN INDIAHighashcontentInconsistent Coal PropertiesSystemhastobeenvironmentallyfriendly.Systemhastobereliablewithleast maintenance problems.Systemhastobeenergyefficient.CRITERIA FOR SELECTION OF SYSTEMCommercial Utility of AshSite Specific Limitations: Facility AgePhysical LayoutBoiler DesignWater AvailabilityAmbient ConditionsEnvironmental IssuesZero water dischargeEmission RegulationsEconomic analysis

BOTTOM ASH HANDLINGEXISTING TECHNOLOGIESWaterImpoundedBottomAshHopperwith Jet Pump SystemLean Slurry Disposal SystemDewatering Bin SystemBottomAshHopperwith submerged scraper chain conveyor system

WATERIMPOUNDED BOTTOMASHHOPPER WITH JET PUMP SYSTEMLEAN SLURRY DISPOSAL SYSTEMFor disposal of ash slurry in dilute form, generated at various power plants and are still in demand. Such systems comprise centrifugal slurry pumps for disposal and clarifloculator or tube settler for recovery of the water. DE-WATERING BIN SYSTEMIt is used for bottom ash available in slurry form to be disposed off through trucks or through high concentration slurry disposal system along with fly ash. De-watering bins with the decanting system removes water from the bottom ash and this water can be recycled through a set of settling tanks, surge tanks, transfer pumps, etc. The bottom ash collected in the bin can be either periodically removed through trucks or can be fed to high concentration slurry disposal system for disposal in paste form along with fly ash. BOTTOMASHHOPPERWITH SUBMERGED SCRAPER CHAIN CONVEYOR SYSTEM

LATEST

TRENDSDry Bottom Ash ConveyingSystem DescriptionAdvantages

DRY BOTTOM ASH CONVEYING

SYSTEM DESCRIPTIONUnique system for dry extraction, air cooling and mechanical handling of bottom ash from pulverized coal-fired boilers.Ash cooling is carried out by ambient air, naturally drawn into the system by the furnace negative pressure. That air recovers a significant amount of energy in the form of ash sensible heat, ash chemical energy from unburned particles and boiler radiation flux through the throat.The dry cooling process has been proven to have no negative effects on the main combustion. Thesystem,compared to conventional wet systems, can improve the boiler efficiency by a factor in the range 0.1-0.6%.Facilitates lower operation & maintenance costsADVANTAGES

The table below shows the main factors which compare between the two methods of conveying: FLY ASH HANDLINGTRADITIONAL TECHNOLOGIESPNEUMATICCONVEYINGVacuum ConveyingPressure ConveyingDisadvantages of Conventional Pressure ConveyingWET ASH CONVEYINGFlushingApparatusforFlyAshLean Slurry Disposal System

VACUUM CONVEYING Sequential Extraction with Low Ash to Air Ratio Continuous Power Consumption Points => Vacuum Pump, Fluidizing System, Vent SystemRedundancies & Line maintenances increase Conveying Time/Power OPTIMIZING OPERATION SEQUENCES AND TUNING SYSTEM DESIGNS CAN RESULT IN SIGNIFICANT REDUCTION IN TIME/POWER !!!ENERGO EXPERTISE Image Courtesy: lbindustrial systems

PRESSURE CONVEYINGContinuous Power Consumption Points => COMPRESSOR/BLOWER, Fluidizing System, Vent System2. Redundancies & Line maintenances increase Conveying Time/Power Streamlining Flow, Multiple Air Injection Practices Higher Material Conveying Lesser Time/POWERENERGO EXPERTISE WET ASH SYSTEMSADVANTAGESLESS DUST CREATIONDISADVANTAGEHIGH WATER & POWER REQUIREMENTADDITIONAL REQUIREMENTS OF RECOVERY WATER SYSTEMSLARGE AREAS FOR SLURRY DUMPINGADVANCED TRENDS IN FLY ASH HANDLINGBy-Pass Pneumatic ConveyingAdvantagesHigh Concentration Slurry Disposal SystemEconomical AdvantagesEcological AdvantagesComparison (Positive Displacement Pumps used in HCSD System Vs Centrifugal Pumps)

BY-PASS PNEUMATIC CONVEYINGThe most common by-pass systems employ a small pipe running inside the conveying line, having fixed ports, or flutes, at regular intervals along its length. An alternative arrangement is to have the by-pass external to the conveying pipeline and connected to it at intervals along the length.

The by-pass pipe allows air to be advanced to a point where it is capable of splitting up the plug at the forward end and so allow conveying to continue. As the by-pass pipe is much smaller in diameter than the conveying pipeline, the air will be forced back into the pipeline through subsequent flutes, and this will effect a break-up of the plug of material causing the blockage. A long plug of material is thus divided up into short slugs that are readily conveyed. REDUCED AIR CONSUMPTION INCREASED EFFICIENCYADVANTAGESEnergyEfficientHighreliabilityLongPlantLifeLeastmaintenanceEnvironmentconcern:Inaperiod,whenenvironmentalprotectionandawareness is a major industrial and social concern,Dense Phase pneumatic conveying, bytotally enclosed handling system, Is particularlyamenable tothe environment.Allconventionalproblems of spillage, dust, contamination and storage are efficiently and successfully eradicated.Planthousekeepingisgreatlyimproved.HCSD SYSTEMECONOMICAL ADVANTAGES Substantial energy savings to run system. The volumes transported are smaller and pipeline sizes can be reduced by more than 50%. By discharging from a central ramp or side-hill, it is possible to avoid raising perimeter dams altogether. Theself-draining, sloping (2-6%) deposit offers long-term stability and can be reclaimed progressively at minimum cost. Significant cost savings in disposal area and dyke construction of up to 60%. Method allows for the creation of small hills by stacking the disposed ash. Extending life time of existing landfill area under restricted slurry conditions.HCSD SYSTEMECOLOGICAL ADVANTAGES Water consumption: high concentration ash slurries use up to afactor 12 less waterthan dilute slurries. No or minimal contamination by water leaking to the environment. Pipeline transportation is safe, silent and reliable without ash spills. No or minimal run-off water and water reclaim system capacity. Thickenedash is not subject to run-out. Dusting is substantially reduced. Slurry hardens out allowing rehabilitation.

Positive Displacement PumpCentrifugal Pumps

COMPARISONAUXILIARY SYSTEMCompressor OptimizationHigh Capacity compressor unit to accommodate for air requirement of entire plant, with medium/low capacity stand-by compressors for instantaneous requirement, to optimize air supply.

TOPICS FOR PRESENTATIONTraditional Bottom Ash Technologies (Covering the entire process and various types)Latest Trends in Bottom Ash Handling Systems (Covering the entire process and various types)Vacuum Based Fly Ash handling Systems (Covering the entire process)Pneumatic Conveying Systems (Lean and Dense)Latest Trends in Pneumatic Conveying Systems (Pipe in Pipe & Molar, Pipe Over Pipe)Silo Systems and Unloading Systems to Barge & Train with multiple discharge pointsWater Pumping Systems, Slurry Pumping System & HCSD Systems (Covering the Operational Philosophy)THANK YOU !!!