Industry Insights - Waste Water Treatment and Desalination in China
Solar desalination, 040324
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Transcript of Solar desalination, 040324
16-Mar-12 1
Solar Desalination
Prof. Moustafa Elsayed
16-Mar-12 2
Introduction
� WHO: 480 millions of human beings are suffering from acute lack of water
� 5 million died per year due to this
� 23 million m3 seawater is desalinated every day
� 46 000 m3 (0.02 %) is produced by means of
renweable energy
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Solar Desalination Methods
� Solar Thermal Methods
� Solar Power Methods
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Solar Thermal Methods
� Generation of heat energy from sun
� Use heat energy in a desalination process
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Solar Thermal Methods
� Solar still
� Solar diffusion still
� Multi-effect evaporation
� Multi stage flash evaporation
� Humidification-dehumidification
� Freezing using absorption cooling process
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Solar Power Methods
� Vapor compression
� Reverse osmosis
� Freezing
� Electro dialysis
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Energy Requirements
Method kJ/kg PR
Reserve Osmosis 30 77
Electrodialysis 50 46
Absorption vacuum freeze 63 37
Vacuum freeze/ vapor compression 102 25
Multi-effect, multistage distillation 125 19
Multistage, flash/vertical tube distillation 175 13
Vapor compression distillation 186 12
Vertical tube evaporator distillation 204 11
Multistage flash distillation 251 9
Single-effect roof-type solar still 4350 0.53
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Solar Still
A well-designed
solar still can
produce 2 to 4
liters (or quarts)
of water per
square meter of
basin area
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Arrangements of Solar Stills
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Productivity of Solar Still
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Output of a solar still
� Q = E x G x A/2.3
� Daily output = 0.30 x 18.0 x 1/2.3
= 2.3 liters (per square meter)
� yearly output: approximately one cubic meter
per square meter
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Heat Fluxes in Solar Still
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Greenhouse-Integrated Stills
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Greenhouse-Integrated Stills
� Solar still
– o Roof-integrated
– o Only partly light-transparent
� Greenhouse
– o Lowered temperature
– o Less water demand
� Production: 1 litre/m2day
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Double Basin Solar Still
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Wick-Type Solar Still
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Cascade-Type Solar Still
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Cover Cooling Solar Still
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Double Effect Solar Still
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Single Effect Diffusion Solar
Still
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Multi-Effect Diffusion Solar
Still
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Single Stage Evaporation
Desalination
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Multi-Effect Evaporation
Desalination
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Multi-Effect Evaporation
Desalination
�Water production > 100 m3/day
�Seawater evaporates stepwise by heat transfer
from tubes with condensing steam
�Primary steam source is produced externally
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Solar Multi-Effect
Humidification Unit
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Solar Multi-Effect
Humidification Unit
�Development: Technical University of Munich
(1999)
�Principle: the evaporation of water and the
condensation of steam to and from humid air,
that flows in a circuit driven by natural
convection between condenser and evaporator.
�Pilot plant: Canary Islands, Spain, operating
since 1992
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Abhu Dhabi Solar
Desalination Plant
�Location: the United Arab Emirates
�Purpose: demonstration unit.
�Commissioned in 1984, with an average
of 85 m3/day of fresh water using sea
water with a salinity of 55,000 ppm.
�Sub-systems: the solar collector field,
heat accumulator and evaporator.
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Abhu Dhabi Solar
Desalination Plant
�Multiple effect stack-type (MES) evaporator of a rated capacity of 120m3/day
�An array of evacuated tube, flat plate collectors with a total absorber area of 1,862 m2.
�A thermally stratified heat accumulator, with a capacity of 300 m3
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Abhu Dhabi Solar
Desalination Plant
�The main grid supplies electricity
required by the different pumps.
�The performance of the collector field
and evaporator sub-systems have not
suffered in performance decline to any
appreciable degree up to today.
�Water cost: US$7/m3 to US$10/m3
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Multi-Stage Flash
Evaporation
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Multi-Stage Flash
Evaporation
�Global water production ≈ 10 million
m3/day
�Heated seawater is flash-evaporated in
low-pressure chamber
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(MSF) driven by solar pond
�Combining solar pond technology with desalination technologies
�The reject concentrate from the primary desalination process provides make-up water to the salinity gradient
�Environmental issues: – Reusing the brine concentrate thereby negating the
need for disposal (zero discharge)
– Pollution-free renewable energy for the desalting process.
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(MSF) driven by solar pond
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Solar Single-Stage Flash
Evaporation Unit
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Solar Single-Stage Flash
Evaporation Unit
�Development: Technical University of
Munich (1999)
�Sections: pressurized section and an
ambient pressure section
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Humidification-
Dehumidification Desalination
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Humidification-
Dehumidification Desalination
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Humidification-
Dehumidification Desalination
�1st step
– Heating from 25°C to 50°C
– Humidified to saturation (20 g/kg),
temperature decreases to 23°C
�15th step
– Heating from 58°C to 78°C
– Humidified to saturation (148 g/kg),
temperature decreases to 60°C
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Humidification-
Dehumidification Desalination
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Humidification-
Dehumidification Desalination
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Humidification-
Dehumidification Desalination
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Humidification-
Dehumidification Desalination
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Freezing Desalination Using
Absorption Refrigeration
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Solar Power Desalination
Vapor Compression
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Vapor Compression
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Freezing Desalination
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Reverse Osmosis Desalination
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Reverse Osmosis Desalination
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Solar RO Desalination
� The plant was designed and constructed in1995 by Water Re-use Promotion Center(Japan)
� Heat and electricity by solar energy
� Solar collector: 3 units of evacuated-tubecollectors each 4 m wide by 1 m long.
� Photovoltaic power generation system
� Fresh water production: 40 liters/hour, onaverage.
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Solar RO Desalination
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Solar RO Desalination
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Cost of Desalination Methods
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Cost of Desalination Methods
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Conclusions-1
�Solar Desalination is a cheap way to
produce fresh water.
�There are several available solar systems
for the production of fresh water from
saline or brackish water.
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Conclusions-2
� The preference of one solar desalination
method over other methods depends on:
� Location
� Amount of water to be produced
� Quality of water to be desalinated
� Quality of water to be produced
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Thank you