FEATURES OF HCSD SYSTEM

- Reduction in water consumption by 60%.

- Reduction in land requirement by 79%

- Reduction in power consumption by 50% .

- Environment friendly ash disposal and coagulated ash doesnt fly under wind.

- Chances of accidents in ash pond are completely nullified due to low quantity of water in ash pondASSUMPTIONS:Ash Content= 42 % Water to Ash ( Conventional)= 80 to 20 % Water to Ash ( HCSD)= 40 to 60 % Re-circulation ( Conventional)= 60 %

Water reqt. for ash disposal of 100 MW power plant.500197WATER & LAND USAGE FOR ASH DISPOSAL

Conventional Vs HCSD (High concentration slurry disposal)

Adoption of HCSD in KORBA region power plants alone may result in an annual availability 21 MCM of water which may be utilized to generate 700-900 MW electricity.

. 15032Land reqt. for ash disposal of 100 MW power plant for 25 years(000 cubic meter / yr)(acre)

363.08329.79359.66310.00345.66292.60316.00Sill level of irrigation sluice 310.0034.65Draw down level of dam 329.79370.00Crest level (radial gate) 345.661468.00Full reservoir level 359.663416.00Maximum water level 363.084002.65riverIn the shown line diagram:

Live capacity of dam = 3046 MCM

Reserve Stock for emergency = 336.35 MCM .

329.79 m is the design driving head to drive the turbine.ParticularsReduced level in metersGross capacity in MCMpenstockturbineHASDEO BANGO DAM an OVERVIEWHasdeo BarrageLBC = 70 CumecsRBC = 117 CumecsdownstreamElevation level (mtrs)Reserve StockDead stockParsahi lift irrigation area of flow 7 Cumecs (=220 MCM) from RBCyet to be developed.(MCM = million cubic meter)

100 MW requires approx. 7 lacs MTPA coal annually = 2.94 lac MT ash annually(Considering 42% ash in coal)

Water through HCSD to handle above quantity of ash:

(67/100) X 294000= 197000Approx.=197000 cum/yr(40 ton water required to dispose 60 ton ash)

Water through Conventional system to handle above quantity of ash:

(170/100) X 294000= 500000 cum/yrWith 60% re-circulation.(80 ton water required to dispose 20 tonAnd 34 ton water required for above with 60% re-circulation)

BRIEF CALCULATION OF WATER CONSUMPTION:

BHARAT ALUMINIUM COMPANY LIMITED, KORBA(A UNIT OF VEDANTA GROUP)ASH POND AREA CALCULATION FOR 2x600MW POWER PLANTCoal Requirement with 100% PLF600x24x0.742 = 10685MT/dayAsh generationConsidering 42% ash content,Total ash generation per day (10685*0.42)=4488MT/dayAssuming fly ash 80% of total ash generation,The Fly ash quantity (4488*0.8)=3590MT/dayAssuming bottom ash 20% of total ash generation,The Fly ash quantity (4488*0.2)=898MT/dayAssuming the Plant life of 25 years,Total ash generation for (25*365*4488)=40949496MTSay41Million MT

Considering ash density 0.8MT/cum, (Conventional) the ash volume =51Million CumConsidering ash density 1.0MT/cum, (HCSD) the ash volume =41Million Cum

Ash Pond area for conventional method of disposalAssuming 15m height,Area required (51000000/15)=3412458SqmDyke construction area required =149383SqmApproach area required=75491SqmTotal area required=3637332SqmSay899Acres Say364Hectares Ash Pond area for High Concentration slurry Disposal methodAssuming 80m height, considering a pond width of minimum 400mArea required (41000000/80)=511869SqmDyke construction area required =237135SqmApproach area required=34168SqmTotal area required=783622SqmSay194AcresSay78HectaresReduction in corridor required for piping By50%SUMMARY-ASH POND LAND REQUIREDPLANT PLANT ASH GENERATION CONVENTIONAL HCSDCAPACITY LIFE VOLUME HEIGHT AREA HEIGHTAREA1x600MW 25 years 51x106 Cum 15 899 Acres25194 Acres2x600MW 25 years 102x106 Cum 15 1798 Acres25388 Acres

Types of Ash Disposal Systems used in India & Abroad

Conventional Lean Slurry Disposal method using an effective ash to water ratio of 100:170 after considering 60% recirculation of water. (Normal pumping is at 100: 400)

Mechanical Disposal method to form Ash mounds using an ash to water ratio of 100:35 (no recirculation of water is required)

High Concentration Slurry Disposal method using an ash to water ratio of 100:67 (no recirculation of water is required)

Conventional Lean Slurry Disposal method

High quality water retaining structure is required for the pond

Accidents like ash pond breakages may occur with disastrous consequences

Overall height of ash pond is limited

Holding capacity per unit area is very low

Water from the pond leaches into the ground water system

Expensive water recycling & treatment system is required

Slurry requires high velocity to prevent settlement, hence high wear & tear of the pipes

Initial cost is lower but cost of water consumption and land required is very high per tonnage. Also the power consumption cost is very high.

Mechanical Disposal method to form Ash Mounds

Very few plants have such system. 2-3 outside India and one at NTPC - Dadri

Power consumption is reasonable comparable to HCSD

Requires long belt conveyor system to transfer ash, stackers, sprinkling, dozers, compacting equipments

Extensive man power requirement for ash mound management.

Requires expensive chemicals to consolidate the ash

Ash has to be very timely consolidated to avoid fly off by strong winds creating massive air pollution

During monsoon, water collection system is required at periphery thru drains to prevent out flow of contaminated ash

Height of ash pond can be upto 50 60 M which gives good storage

Extensive maintenance required due to mechanical equipments

Initial cost is very high

Not a perfect system due to its complication & heavy maintenance

High Concentration Slurry Disposal method

This is the latest technology developed over last 15 20 years. With its perfection new generation power plants can enjoy its benefits. Also existing plants can be converted to this new concept

Water consumption is very low. No water retaining structure is required for the pond, except for a small toe dyke for rain water collection

No ground water contamination as literally no water is released from the slurry.

No water recycling system is required

Power consumption is comparable to Dry ash mound type disposal & much lower than the conventional system

Due to cementing properties of fly ash, the ash density at ash pond is much higher by 20 30%, Hence that much extra ash can be stored per unit area

Ash pond height can be above 100Mtrs giving a massive storage per unit area

High Concentration Slurry Disposal method

Pipe sizes are lesser by half of the conventional slurry pipes

Slurry is highly viscous & soft, hence less abrasive. It conveys at 60 65% of velocity of conventional system. Hence wear is very low and pipe line rarely requires any replacement

Initial cost is slightly higher by 15 20% which will be recovered in few months on account of lower power consumption. Additionally cost of water consumption and land required is very low per tonnage

Maintenance cost is low