Actual overview of desalination processes by Dr. Raphael Semiat from the Grand Water Research Institute

1. Technion - Israel Institute of Technology
Grand Water Research Institute
Rabin Desalination Laboratory
Chemical Engineering Department
Energy Issues in Desalination Processes
by Raphael Semiat - Cyprus Institute 2011
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2. Middle East Desalination Research Center
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3. Driving Forces for Desalination R&D
RelatedWater
Need for Documents
Global need, Industry, Agriculture, Remote
Locations, Desertification, Etc.‫‏‬
Cost Difference - (Industry/Urban - Agriculture)‫‏‬
Cost Difference - (Thermal Processes - Membrane Processes)‫‏‬
Technologies for Export
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RDL GWRI Technion 4

4. Sea Water Desalination
According to government decisions (between the years 2001-2008) sea water
desalination facilities are being built :‫‏‬
(100)‫‏‬
Hadera
Construction phase.‫‏‬
Production at 10/09‫‏‬
Completed facilities
Ashkelon -BOT 108 MCM/Y (VID)‫‏‬
Pre tendering stage
Palmachim -BOO 30 MCM/Y (Via
Full production
(140)‫‏‬ Maris)‫‏‬
Planed
‫‏‬Sorek
Since 9/07‫‏‬ Ashdod – 100 MCM/Y (TK Mekorot)‫‏‬
(30)‫‏‬ In PQ process
Palmachim
Pre tendering stage.‫‏‬ (100)‫‏‬ Sorek – more than 140 MCM/Y
Financial Agreement Ashdod In Construction
Full production 12/10‫‏‬ Hadera- BOT 100 MCM/Y (H2ID(‫‏‬
(108)‫‏‬ In bidding process
Ashkelon
Enlargement of about 100 MCM/Y
Full production
Since 12/05‫‏‬ Overall until 2013 = 600 MCM/Y
Until 2020 = 750 5MCM/Y

5. Eilat Plants
Sabha A: 25,500m3/day BW
Sabha B: 10,000 BW
Sabha C: 10,000 SW
RDL GWRI Technion
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6. Ashkelon Plant
On Sept 2006 completed first 100 Million m3‫‏‬
‫7‏‬

7. m
m 0
80
0 ,0
13
e, ip ,
e
l ip Ina ep
fal p tk
ot
u
DPE DE
P
4”H 4”H
6 6
To
w
pipe
pipe
rete
e
cret
6 ” Conc
Con
96 ”
9
Palmachim 30MMm3/y. April 2006‫‏‬

8. Hadera – 2010
Desalination plant H
G
100-129 million F
M3/y E
D
A: Product water tank C
B: Post-treatment
building
C: East SWRO, stage 2-4
D: East SWRO, stage 1 B
E: East gravity filter
F: West gravity filter
G: Admin, lab, control A
room
H. West SWRO, stage 2-4
I: West SWRO, stage 1

9. Man made polluted waters: Industrial, agriculture and urban effluents
Modern Sewage Treatment
Straining
Secondary
treatment
Sludge/ solids
treatment
Adsorption
Micro/Ultra- Energy Compost
MBR Filtration
Reverse-Osmosis Polishing
Concentrate disposal
10 or Nano-Filtration
RDL GWRI Technion

11. Desalination
(Desalting, Desalinization)
Process of removing salt from water –
Practically – removing water from salt solutions
‫‏‬
Major processes:
Ion Exchange
Electro-Dialysis Other techniques
Reverse Osmosis :‫ ‏‬olar distillers
S
Distillation Freezing
Use of renewable energies
(Solar, wind, nuclear, waves, etc.)‫‏‬
Solvent extraction, clathrates
Forward Osmosis, Membrane Distillation
electrolytic capacitance
RDL GWRI Technion Air humidification

12. Thermodynamics – the concept of minimal energy and
Irreversibility
Minimal energy needed to separate a component from
binary solution is equal to:‫‏‬
p n
  a n
 R nR n
W n l 0
nT
2
F lw
d d Td
n
1 p
06 n
.9 2
2T p

W lg 0n
1 1
0 n0
02 0
o d
1
0
p
  2 T ga
W . 9 o0 w
0 6l 1
Energy needed per 1m3 produced from an infinite
source of 3.5% salt concentration seawater is
0.79 KWh/m3. For 50% recovery, the energy
demand is 1.09 Kwh/m3.‫‏‬

13. . Different energy requirement for industrial
desalination techniques
‫‏‏‬ .
Source Technique Heat requirements Electricity Combined
‫‏‏‬
KWh/m3 (Thermal) required Energy
‫‏‏‬
KWhe/m3 demand
‫‏‏‬
KWhe/m3
‫‏‏‬
Blank et al. (2006) RO ‫‏‏‬
- ‫‏‏‬4-6 ‫‏‏‬
4-6
MSF ‫‏‏‬
40-120 (Thermal) ‫‏‏‬
2.5-5 ‫‏‏‬
12-58
MED ‫‏‏‬
30-120 (Thermal) ‫‏‏‬
2-2.5 ‫‏‏‬
4-58
El-Nashar MSF ‫‏‏‬
25-114 (Thermal) ‫‏‏‬4.8 Not clear
‫‏‏‬
El-Sayed (2001) MSF variations ‫‏‏‬
34-102 ‫‏‏‬
2-2.2 ‫‏‏‬
17-47
‫‏‏‬
Ophir & Gendel (2006) MVC ‫‏‏‬
7.2-11.1 (electricity) ‫‏‏‬
1.2 ‫‏‏‬
8.4-12.3
‫‏‏‬
Ophir & Lukiec (2007) MED ‫‏‏‬
4.8 ‫‏‏‬
1.2 ‫‏‏‬6
‫‏‏‬
Glueckstern, (2004) MED ‫‏‏‬
6-12
MSF ‫‏‏‬10-16
RO ‫‏‏‬
3.8
‫)4002( ‏‏‬
Wilf RO ‫‏‏‬
3-4
Estimations for thermal units depend on GOR achieved in plant

14. Ireversibilties are accounted for energy
losses due to friction, heat losses to the
environment, heat losses due to minimal
driving forces and more.‫‏‬
Actual energy needed is much higher
than the thermodynamic minimal energy.‫‏‬
How can we compare the different
techniques in terms of energy usage?‫‏‬

15. Efficient pumps
Ep=PQ

16. Concentrate Energy
Recovery Devices

17. Energy
‫‏‏‬ balance, large scale plant (Glueckstern and Priel, 2002)
Pumps Flow Diff. Energy KWh Specific Energy
Head
3
No. m /h Bar Pump Total KWh/m3 Product
Intake 6 2,200 1.0 77 462 0.07
Raw Water Supply 6 2,200 2.5 192 1,154 0.18
Feed Booster 12 1,042 7.7 281 3,368 0.54
Turbine operation for power saving
High-Pressure
Aggregate: 12 1,042 69.3 2,381 28,567
Pumps
Turbine 12 521 73.0 -980 -11,763
Motors 12 1,444 17,323 2.77
Auxiliary + Lighting 400 400 0.06
Total 3.63
Pressure exchangers for power saving (estimate)
High-Pressure
Aggregate: 6 1,042 69.3 2381 14284
Pumps
Pressure Depend 6252/n 66.0 - -
exchangers on size/n
Auxiliary pumps 6 1042 3.3 132 792
Motors 12 1,444 15,076 2.41
Auxiliary + 400 400 0.06
Lighting
Total 3.26

18. Evaporation- distillation desalination
Evaporation of seawater, consumes
about 650 KWh per m3…
Pumping energy is needed to move water
to and from the plant
Pumping of cooling water for condensation
Reuse of the energy allowed reduction of the
total consumption by a factor of GOR
GOR – Gained Output Ratio- usually 8-14‫‏‬
Energy consumption is reduced in
connection with a power station

19. MSF DISTILLER
(3,500 ton/unit, 30m W x 90m L x 15m H)‫‏‬
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20. Typical Flow Diagram (Brine Recycle Type)‫‏‬
Seawater Distillate
Steam Non-Condensable Gas
Brine
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21. Multi Effect Distillation - Horizontal Tubes - IDE Design
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22. Horizontal pipe
Drop-wise or
condensation - evaporation film-wise
condensation
Falling seawater
film
Falling
condensate film
Condensate out
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23. Vapor Compression
Units
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24. Water Flow
Distribution,‫‏‬
The Dry Patch
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25. Steam from power
plant
Thermal
Desalination
plant
Schematics of a simple
power plant

26. O
}
Rankine Cycle on Pressure-Enthalpy Diagram 1-2 – electricity
Steam engine for electricity production production line

27. Energy consumption for distillation techniques, based on
exhausted steam and heat losses, at different temperatures.
BPE values of seawater are included.
‫‏‏‬
Energy values -from steam tables.
‫‏‏‬
Temperature Electrical Boiling Point Energy consumption
working range power potential elevation range GOR=10 GOR=16‫‏‬
of exiting steam in Power (Fabuss, 1980)‫‏‬ Including pumping
station 0C Kwhe/m3‫‏‬
KWhe
70-350C MED 17‫‏‬ 0.98-0.34‫‏‬ 6‫‏‬
100-350C MED 30.7‫‏‬ 1.18-0.34‫‏‬ 5.6 5‫‏‬
120-350C MSF 38.9‫‏‬ 1.31-0.34‫‏‬ 8.4 6.9‫‏‬

29. Distillation
Forward Osmosis
Direct osmosis
Possible energy
production
Membrane cleaning
In comparison with RO.
Real energy
consumption?‫‏‬
Pumping energy
Magnetic separation needed, distillation,
cooling, etc.

30. Forward Osmosis
Vapor
compressor
Gases to NCG out
adsorb
Concentrated
seawater
Diluted
draw
solution
Feed
seawater
Concentrated
draw solution
Product water
FO System Distillation Adsorption
Basic sections in Forward Desalination

31. Energy recovery estimation in the FO process.
Assuming 50% recovery, numbers are given
per 1 m3 of product.
Estimated Energy
Demand Consumption Comments
‫‏‏‬
(KWh/m3 product)
Pretreatment and concentrate Pumping, filtration, etc. Similar
disposal
‫‏‏‬
1.7
to RO plant
Pumping of water and draw solutions
through the membranes
‫‏‏‬
0.3
Equivalent value of 17 KWh/
Evaporator distillation energy ton steam purged from
consumption
‫‏‏‬
4 electrical plant (only 0.25 tons
‫‏‏‬
needed)
Cooling water at the distillation Energy needed to pump the
column
‫‏‏‬
3
cooling water required
Cooling water for adsorbing draw Energy needed to pump the
solution gases
‫‏‏‬
4
cooling water required
Vacuum compressor to pump non-
condensable gases
‫‏‏‬
4
Credit for cooling water for steam Heat removal from 250 kg of
condensation at power station
‫‏‏‬
-3
steam at the plant
Total ‫‏‏‬
14 ±20% estimation error

32. Membrane Distillation - using‫“‏‬waste‫‏‬energy”‫‏‬
Condensation chambers
Stage
Feed Water 1 n-2 n-1 n
2 ` Concentrate out
External
Heat
source c c c c c
o W o W W o W o W o W
n a n a a n a n a n a
d t d t t d t d t d t
e e e e e e e e e e e
n r n r r n r n r n r
s s s s s
a f a f f a f a f a f
ti l ti l l ti l ti l ti l
Back o o o o o o o o o o o
to sea n w n w w n w n w n w
Heat Recovery
To
reservoir
Vacuum
pump
Condensate out
(product) Brine flow Distillation membranes
Feed pump chambers
From Sea
Schematic view of Membrane distillation design, based on MED technology

33. Osmosis-energy generation
Ql-Q (P1-P1)‫‏‬
Low-concentration Q
High-concentration
salt solution Ql (P1)‫‏‬
salt solution Qh (P2)‫‏‬
Qh+Q
(P2-P2)‫‏‬
Diluted salt solution
Pressure Feed
Exchange Seawater
To Sea
Power Generation
Turbine
Emax~Lpπ 2 /4 -QhP2

34. Subject Fuel Gas Gasoil Heavy fuel Coal
Energy usage in Desalination - comparison7700
Caloric value Kcal/Kg fuel
9000 10750 10000
Caloric Value Kwht/Kg fuel 10.5 12.5 11.6 9
Electricity production (45% eff.)
Kwhe/Kg fuel large Power station 4.7 5.6 5.2 4
Electricity production (80% eff.)
High efficiency gas turbine
Kwh/Kg fuel 8.4
Capacity - Seawater Desal (50%
Recovery) m3/ kg fuel 1.3 1.6 1.5 1.2
80% efficiency 2.4
Fuel consumption/ ton
Desalinated water Kg fuel /m3 0.7 0.6 0.7 0.9
80% efficiency 0.4
How many km can I drive with 1
m3 Desal water fuel consumption? 2-7 2-6
How many hours of AC - single
room (2.5 Kw-h) can I operate? 1.4

35. Household Energy Consumption
Electricity, transportation and desalinated water…
A small family, consumes water at a rate of 18 m3/month,
1200 KWh of electricity /month, Drives 1500 km/month, consumes 160 liter
gasoil/month
Energy consumption assuming only desalinated seawater used - 140
KWh/month (fuel value)
Energy consumption - driving a car - 1500 KWh/month (fuel value)
Energy consumption - electricity - 1200/0.45=2667 KWh/month (fuel value)
Energy for desalination/ energy for transportation - 9.3%
Energy for desalination/ energy for electricity - 2.6%
Energy for desalination/ total energy consumption - 3.4%
Can we save 3.4% in our household energy consumption?
Where we should put our energy for use? In water? In high energy consuming
cars? In overused AC?
A nature trip of 300Km from Tel Aviv to the Negev or the Galilee, in
a four wheels drive, is equivalent in terms of energy to
desalinated seawater consumption of a family of four people
(16m3/month) of 7 months!!!

36. ‫צריכת האנרגיה בישראל – ויקיפדיה‬
Energy consumption in Israel
Total energy imported and produced in Israel in 2006 is 24.06
equivalent million tons oil – 1.04*10^18Joul
Electricity – 40%. Fuels products – 43%. Palestinian Authority – 13%.
Solar heaters – 3%.
Electricity production – 46,175 millions KWh (2006) 50,161 millions
KWh (2008) Rate of change – 1.7-2,7%/year.
Yearly energy consumption expected by 2013 for desalinated water –
3.7KWh/m^3*600 million m^3 = 2220 millions KWh
Electricity for desalination/total electricity production – 4.42%
Electricity for desalination/total energy consumption – 1.77% !!!!!!!!!!
Correction for PA – 2.0%
Correction for 10% increase in total energy consumption – 1.85%

37. Desalination and proper water usage
Other costs should be included
besides Energy
• Cost of water in negligible for regular household
• Cost of water is tolerable for most industries
• Cost of water is significant in agriculture
Make better usage of water:‫‏‬
– Use of greenhouses
– Use Drip-Irrigation – save 30-90% of water
consumption by other irrigation techniques – reduce
the cost problem

38. 200-250 m2 are needed
to make 1 m3 water a
day!‫‏‬
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39. Solar Desalination
Aqaba Jordan
Sept 2005‫‏‬
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40. Water is needed in locations where agriculture is
still the basis for life.
Simple agriculture cannot afford even
the currently relatively low costs.
It is a global question
of the same type
as the usage
of alternative energy
sources to solve
environmental-pollution problems.
The future of mankind depends
on finding the proper answers
to those questions,
in addition to the quest for
global peace.
41 41
RDL GWRI Technion

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