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Blow Down cooling water systemIs ZLD the optimal process?
Ella kotlar (M.Sc.)
Environmental Licensing & Protection Unit
Israel Electric Corp.
THE ISRAEL ELECTRIC CORP. Ltd.
Environmental licensing and protection unit
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Content
Background - IECs project
Available Solutions for power stations cooling towersBlow down
Environmental aspects
and cross media effects of ZLD
Summary
Gezer power station ZLD system,IlanMalester PhdGezer power station ZLD system,IlanMalester Phd
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Background
IECs project included three Combined Cycle Electric
Power generation units of 370MW (Gezer & Alon TavorPower stations)
The combined cycle units are cooled by industrial
induced draft wet cooling towersThe water source for the cooling has been set asreclaimed municipal waste water and raw water asbackup.
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Background
IEC's project was the first major project using municipaltreated wastewater in induced draft wet cooling towersin the Israeli industry.
In order to achieve the demanded water quality for thecooling towers, IEC built a tertiary treatment plantincluding nitrification, softening and filtration.
Blow down of cooling water must be preformed due toevaporation and rising salts concentration in the coolingtowers.
The project raised the challenge of determining the bestsolution for the disposal of the cooling tower Blow down.
The cooling tower Blow down treatment plant must
operate at varies feed water composition.
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nitrificationnitrification
softenersoftener
filtrationfiltration
Dovrat - Tertiary and ZLD treatment plant Dovrat - Tertiary and ZLD treatment plant
ZLD treatment plantZLD treatment plant
Blow down
tank
Blow down
tank
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systemwaterBlow down cooling
50 - 150 m3/hr per unit
Approximately 50 container trucks per day per unit
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Solutions for cooling tower Blow down
Discharging Blow down to the sea using tankers (50 tankersper day per unit)
Discharging Blow down to the sea by a brine dischargepipeline from the inland site to the sea
Operating the cooling towers on a low number of cycles and
discharging the Blow down to the Ayalon River
Operating the cooling towers on a low number of cycles anddischarging the Blow down to wastewater reservoirs
Treating the Blow down in a Zero Liquid Discharge (ZLD)plantTreating the Blow down in a Zero Liquid Discharge (ZLD)plant
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ZLD and near ZLD
Blow down treatment alternative technologies
1. Full Thermal technology - Evaporator system(brine
concentrator) followed by a Crystallizer + filter press2. Semi Thermal technology - Brine Concentrator +
Concentrated brine truck disposal
GE Seeded sl urry brine concentrator
GE Crystallizer
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ZLD and near ZLD
Blow down treatment alternative technologies
3. Combination of membrane and Thermal
technologies - Chemical Pretreatment + RO systems +Brine Concentrator + Crystallizer + filter press
4. Combination of membrane and Thermal
technologies - Chemical Pretreatment + RO systems +
Brine Concentrator + Concentrated brine truck disposal
5. Full membrane Filtration technologies - Concentratedbrine truck disposal
Recovery is in the range of 92%-98%Recovery is in the range of 92%-98%
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ZLD treatment plant
Blow down treatment technologyMost ZLD facilities in the world that treat Blow downfrompower plant cooling towers use thermal
technologies (with/without RO as a pretreatment forreducing the blow down capacity).
Evaporator system
(brine concentrator)followed by a crystallizer
HPD Seeded slurry brine concentrator
ZLD treatment plant - Gezer power station (IlanMalester, Phd)ZLD treatment plant - Gezer power station (IlanMalester, Phd)
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Main reasons for adopting ZLD process
Environmental compliance
High operating cost (blow down disposal)
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Environmental aspects and cross
media effects
High energy consumption (electric and steam)
Solid waste / Concentrated Brine disposal
Usage of chemicals (pretreatment processes)
Main environmental Cross media effects
Prevention of water body pollution disposal of the
waste (ground water, sea, river)
Water reuse (recovered water is returned to the coolingtower or to the deminerlized water production system)
Air pollution (from electricity/steam generation,transportation)
Chemicals (Hazardous chemicals)
Land use
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Estimated Environmental parameters*
Semi Thermal
technologies
Full Thermal
technologies
Outlet:
2,5003,000Energy
consumption (kWh)
30Brine disposal
(m3/hr)
01,000 Salt cake disposal
(kg/hr)97%98%% Recovery
* for two 375MW Units, According to RFI answers* for two 375MW Units, According to RFI answers
Inlet (Blow down): 100-200 m3/hr
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Solid waste (Salt)
Gezer power station (Ilan Malester, Phd)Gezer power station (IlanMalester, Phd)
Concentrated brineConcentrated brine
Disposal
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Disposal of the waste
Concentrated brine:
- discharged to a near water body, when available- discharged to the waste water area treatment system- evaporating in evaporation ponds
Solid waste ("salt") from the crystallizer:Usually dumped in landfills, local abandoned quarry sitesetc.
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Liquid and solid residual disposal
in Israel
Because of unique environmental conditions regarding
land and groundwater salinity, land filling of the solidwaste and discharging the brine into the river or to wastewater reservoirs is prohibited.
According to Israel environmental authorities, the solidwaste and the concentrated brine must be discharged
to the sea.
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Estimated air Emissions
(Ton/year)*
Unit 21 (148MW)
Gezer PS(2011)
Semi
Thermal
technologies
Full Thermal
technologies
140,00015,00018,000CO2
1143744NOX
4.71.11.3PM
includes emissions from: Electricity generation, steam generation andtransportation
includes emissions from: Electricity generation, steam generation andtransportation
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Summary
Solutions for treatment of cooling tower Blow down
depends essentially on;- Local conditions
- Local regulatory demands
Due to the local conditions, treating the Blow down
up to a concentrated brine may be the optimal
solution.
Alon Tavor power station, Ilan Malester, Phd Alon Tavor power station, Ilan Malester, Phd
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Thank you