Low-temperature thermal desalination
Encyclopedia
Low-temperature thermal desalination (LTTD) is a desalination
technique takes advantage of the fact that water boils at low pressures, even as low as ambient temperature. The system uses vacuum pumps to create a low pressure, low-temperature environment in which water boils at a temperature gradient of 8 to 10 °C between two volumes of water. Cooling water is supplied from sea depths of as much as 600 metres (1,968.5 ft). This cold water is pumped through coils to condense the evaporated water vapor. The resulting condensate is purified water. The LTTD process may also take advantage of the temperature gradient available at power plants, where large quantities of warm waste water are discharged from the plant, reducing the energy input needed to create a temperature gradient.
The principle of LTTD is known for a long time, originally stemming from ocean thermal energy conversion
research. Some experiments were conducted in U.S. and Japan to test the low-temperature driven desalination technology. In Japan, a spray flash evaporation system was tested by Saga University. In US, at Hawaii Islands, the National Energy Laboratory tested an open-cycle OTEC plant with fresh water and power production using a temperature of 20 °C between surface water and water at a depth of around 500 m. LTTD was studied by India's National Institute of Ocean Technology (NIOT) from 2004. Their first LTTD plant was opened in 2005 at Kavaratti in the Lakshadweep
islands. The plant's capacity is 100000 litres (211,337.9 US pt)/day, at a capital cost of INR 50 million (€922,000). The plant uses deep water at a temperature of 7 to 15 °C (44.6 to 59 F). In 2007, NIOT opened an experimental floating LTTD plant off the coast of Chennai
with a capacity of 1000000 litres (2,113,378.5 US pt)/day. A smaller plant was established in 2009 at the North Chennai Thermal Power Station to prove the LTTD application where power plant cooling water is available.
Desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...
technique takes advantage of the fact that water boils at low pressures, even as low as ambient temperature. The system uses vacuum pumps to create a low pressure, low-temperature environment in which water boils at a temperature gradient of 8 to 10 °C between two volumes of water. Cooling water is supplied from sea depths of as much as 600 metres (1,968.5 ft). This cold water is pumped through coils to condense the evaporated water vapor. The resulting condensate is purified water. The LTTD process may also take advantage of the temperature gradient available at power plants, where large quantities of warm waste water are discharged from the plant, reducing the energy input needed to create a temperature gradient.
The principle of LTTD is known for a long time, originally stemming from ocean thermal energy conversion
Ocean thermal energy conversion
Ocean Thermal Energy Conversion uses the difference between cooler deep and warmer shallow or surface ocean waters to run a heat engine and produce useful work, usually in the form of electricity....
research. Some experiments were conducted in U.S. and Japan to test the low-temperature driven desalination technology. In Japan, a spray flash evaporation system was tested by Saga University. In US, at Hawaii Islands, the National Energy Laboratory tested an open-cycle OTEC plant with fresh water and power production using a temperature of 20 °C between surface water and water at a depth of around 500 m. LTTD was studied by India's National Institute of Ocean Technology (NIOT) from 2004. Their first LTTD plant was opened in 2005 at Kavaratti in the Lakshadweep
Lakshadweep
Lakshadweep , formerly known as the Laccadive, Minicoy, and Amindivi Islands, is a group of islands in the Laccadive Sea, 200 to 440 km off the coast of the South West Indian state of Kerala...
islands. The plant's capacity is 100000 litres (211,337.9 US pt)/day, at a capital cost of INR 50 million (€922,000). The plant uses deep water at a temperature of 7 to 15 °C (44.6 to 59 F). In 2007, NIOT opened an experimental floating LTTD plant off the coast of Chennai
Chennai
Chennai , formerly known as Madras or Madarasapatinam , is the capital city of the Indian state of Tamil Nadu, located on the Coromandel Coast off the Bay of Bengal. Chennai is the fourth most populous metropolitan area and the sixth most populous city in India...
with a capacity of 1000000 litres (2,113,378.5 US pt)/day. A smaller plant was established in 2009 at the North Chennai Thermal Power Station to prove the LTTD application where power plant cooling water is available.