Desalination of SeawaterKeerthi Gnanavel Blaine BensurChen Xu

Overview1.Background

2.Methodsa. Multiple Effect Distillation

b. Multi-stage Flash Distillation

c. Reverse Osmosis

3.Results

4.Summary and Conclusions

1.BackgroundPlaces where Desalination is common…

Hot, arid climates

India, Middle East, Some parts of Central US

Wherever transporting drinking water is expensive

2a. Multiple Effect Distillation (MED)Background

Classic Desalination Method

Tolerant to external conditions

Cost-Effective

Utilizes increased surface area to vaporize water (highly effective)

External condenser needed

MED Diagram

2b. Multi-stage Flash Distillation (MSF)Background

Tolerant to external conditions

Utilizes change in pressure to vaporize water

Product is fresh liquid water (no condenser needed)

Very little energy required

MSF Diagram

2c. Reverse OsmosisBackground

Relatively new Technology

Sensitive to conditions

Can be expensive

Has potential to be a promising method

RO Diagram

3. Results Product water

capacity50,600 m3/day = 2,108 m3/hr

Product water concentration

500 mg/solid solute

Pressure across membranes

Ranges from 800psi - 1000psi

pH of product water

~5

Annual Cost ~365,000 USD/m3

Product water output capacity

68,000 m3/day = 2,833 m3/hr

Product water salt content

<2ppm

Seawater feed temperature

Varies

Waste brine temperature

60oC

Concentration of brine

~1.5 x feed concentration

Brine heater steam requirements

130oC, ranges from 0.35 - 1 bar

Plant life ~25 years

Power consumption

Ranges from 1.5KWh - 15.0 KWh

Overall annual cost

~1 Million USD

Product water output

4500 m3/day = 187.5 m3/hr

Product water salt content

<50ppm

Seawater feed requirement

375 m3/hr

Seawater feed temperature

29oC

Waste brine temperature

40oC

Concentration of brine

~2 x feed concentration

Brine heater steam requirements

130oC, 2.8 bar

Performance ratio 9 kg water produced/kg steam input

Power consumption 500KWh (pumping) + 100KWh (lighting/other) = 600KWh

Overall annual cost 73.369 Million Indian Rupees = 1.1 Million USD

4. Summary and ConclusionsMED seems to be more effective given cost, power consumption,

product quantity, etc.

References1. Cohen-Tanugi, David, and Jeffrey C. Grossman. "Water Desalination across Nanoporous Graphene." Nano Letters Nano Lett. 12.7 (2012): 3602-608.

Web. (DOI: 10.1021/nl3012853) (NANO Graphene) (article)

2. Wade, Neil M. "Technical and Economic Evaluation of Distillation and Reverse Osmosis Desalination Processes." Desalination 93.1-3 (1993): 343-63. Web. (DOI: 10.10160011916493801132) (RO MED MF) (article)

3. Manolakos, D., G. Papadakis, S. Kyritsis, and K. Bouzianas. "Desalination." Experimental Evaluation of an Autonomous Low-temperature Solar Rankine Cycle System for Reverse Osmosis Desalination 203.1-3 (Feb 2007): 366-74. Print. (DOI: 10.1016/j.desal.2006.04.018) (RO)(article)

4. https://www.oas.org/dsd/publications/Unit/oea59e/begin.htm#Contents -URL Secretariat, General, comp. "2.1-2.5." Source Book of Alternative Technologies for Freshwater Augmentation in Latin America and the Caribbean. Osaka, Japan: UNEP, 1998. N. pag. Print.(RO)(print)

5. http://www.engr.uky.edu/~aseeched/SummerSchool/2007/session_handouts/Spreadsheets/3%20Spreadsheet%20Applications%20Across%20The%20Curriculum/3%20Documents/TripleEffect.pdf (MED)(paper-lecture)

6. Krishnan, Mangala Sunder, Professor, comp. "Modeling of Evaporators." Multiple Effect Evaporator System (n.d.): n. pag. Web. 10 Oct. 2015. <http://nptel.ac.in/courses/103107096/25>. (MED)(Paper-lecture)