Lecture (12): Water Desalination

Lecture (12): Water Desalination Lecture (12): Lecture objectives: By the end of this lecture students should be able to: To know the description of desalination stages. To know the desalination technologies classification To know desalination plants in KSA.

Introduction Many regions in the world do not have easy access to fresh drinking water Desalination process helps remove salts from sea water to make it drinkable Pros: Brings drinking water to many dry regions Cons: Expensive In some parts of Middle East, a liter of water is more expensive than a liter of gasoline

Description of desalination stages

Desalination technologies classification based on the separation process adopted

Desalination technologies classification based on the type of energy used

PROCEDURES Reverse Osmosis Distillation Electro dialysis Multistage flash (MSF) Multiple effect distillation (MED) Vapor compression Electro dialysis Vacuum freezing

Reverse Osmosis Water pressure increased Pumped through permeable membranes Salts separated from water due to membranes Most desalination plants utilize this technology

Multi Stage flash Steam is used to heat tubes of saline water Heated water flows into “stages” that are at lower pressure Water boils rapidly and “flashes” into steam

Installed Capacity (m3/day) Existing Plants Type of Technology Installed Capacity MW Installed Capacity (m3/day) Year of Commission Plant Name Location # Single Purpose (MED) - 9,000 2009 Alwajih (3) Alwajih 1 Single Purpose (MSF) 11 22,886 1986 Khafji (2) Khafji 2 Single Purpose (RO) 4,400 Umlujj (2) Umlujj 3 Umlujj (3) 4 Farasan (2) Farasan 5 18,000 Rabigh (2) Rabigh 6 1989 Duba (3) Duba 7 2,270 1983 ALBirk 8 4,500 1987 ALAzizih 9 1990 Haql 10 2008 ALQunfutha ALlith 12 Dual Purpose (MSF) 710 223,000 Khobar (2) Khobar 13 479 280,000 2000 Khobar (3) 14

Installed Capacity (m3/day) Existing Plants Type of Technology Installed Capacity MW Installed Capacity (m3/day) Year of Commission Plant Name Location # Dual Purpose (MSF) 360 137,729 1982 Jubail (1) Jubail 15 1225 947,890 1983 Jubail (2) 16 Single Purpose (RO) - 90,909 2000 Jubail (RO) 17 357 108,074 1981 Yanbu (1) Yanbu 18 150 144,000 1998 Yanbu (2) 19 128,182 Yanbu (RO) 20 256 88,357 1979 Jeddah (3) Jeddah 21 590 221,575 Jeddah (4) 22 56,800 1989 Jeddah (RO1) 23 1994 Jeddah (RO2) 24 240,000 2013 Jeddah (RO3) 25 263 223,000 Shoaiba (1) Shoaiba 26 520 454,545 2001 Shoaiba (2) 27 108 97,014 Shoqaiq 28

Water Demand in KSA – Main Figures 2010 2025 Population (Million) 27.2 34 (*) Water demand (Million m3/day) 6.8 8.5 (*) Desalination share in water 53% (3.3 Million m3/day) 63% (5.2 Million m3/day) (*): assuming an average annual growth rate of 1.5%

Multi Stage flash (cont…) Generally, only a small amount converts to steam since rapid vaporization results in cooling of water Thus water is flashed multiple times in different stages at lower pressures, requiring no extra heat But, multi stage flashing reduces thermal efficiency 85% of world’s desalinated water is generated through MSF Recently the equipment has become cheaper

Shoaiba Desalination Plant Largest desalination plant in the world Produces 450,000 m³/day Per year 150 million m³ of water is desalinated Total cost is $1.06 billion To increase the thermal efficiency of this plant, the maximum number of stages is set to 25 (MSF) Research in the field is resulting in more plants coming up in Florida and California

Reverse Osmosis https://www.youtube.com/watch?v=mZ7bgkFgqJQ https://www.youtube.com/watch?v=aVdWqbpbv_Y