Showing papers by "P.K. Tewari published in 2007"

Nuclear desalination by waste heat utilisation in an advanced heavy water reactor

Abstract: The use of thorium for nuclear power generation is an important element of the Indian atomic energy programme. The design and development of the Advanced Heavy Water Reactor (AHWR) is a step in this direction. Intensive design activity is underway to set up a 300-MWe AHWR. The design of the AHWR incorporates several features to simplify the design and to eliminate certain systems and components, making it economically competitive with other available options for power generation. Utilisation of low-grade or waste heat is an additional feature incorporated in the overall design of the reactor system. A proposal to utilise waste heat from the Main Heat Transport (MHT) purification circuit to produce high-quality desalinated water by the low-temperature evaporation process has been envisaged. This paper presents the proposed nuclear desalination system utilising MHT purification circuit waste heat of AHWR along with its coupling arrangement and technical details.

Mechanical vapour compression desalination plant at Trombay

Abstract: Desalination plants based on Mechanical Vapour Compression (MVC) technology are inherently the most thermodynamically efficient. The thermodynamic efficiency of the MVC process is derived from the application of the heat pump principle. A single unit of a two-effect MVC desalination pilot plant of 50 m 3 /day capacity has recently been commissioned at Trombay, Mumbai. The desalination unit is very compact and unique in the seawater desalination technologies and is being operated by using electricity only. Horizontal tube thin-film spray desalination evaporators are used for efficient heat transfer. It is suitable for a site where feed water is highly saline and condenser cooling water is absent, and where a thermal heat source is not available. The unit produces high-quality water, nearly demineralised (DM) quality directly from seawater. There is no need for a polishing unit and product water can be used directly as make-up of boiler feed and for other high-quality process water requirements in industry. This paper includes the design and highlights the technical features of this unit.

Safety and reliability aspects of seawater reverse osmosis desalination plant of nuclear desalination demonstration project

Abstract: Desalination systems are mostly based on membrane (RO) and thermal (MSF and MED) processes. High-pressure operation and high level of corrosion are the major aspects of concern in a Seawater Reverse Osmosis (SWRO) Plant. Selection of the appropriate material for construction and the following of the proper design, fabrication and testing codes, and safe operational procedures ensure the safety of the plant. Proper selection of feed seawater source, provision of standby equipment, proper instrumentation and controls, and periodical maintenance improve the reliability. When the desalination plant is integrated into a nuclear power plant, safety measures have to be more stringent, in order to achieve smooth operation and public acceptance. In this paper, the safety and reliability aspects of SWRO desalination plants are discussed in detail, including the case study of an SWRO plant integrated with a nuclear desalination system.

The potential for desalination in India

Abstract: The demand for water in India is increasing rapidly owing to progressive increase in the use of water for irrigation, rapid industrialisation, population growth and improving life standards. A holistic approach is therefore required to cope with the freshwater needs of the country. It includes: seawater desalination in coastal areas; brackish water desalination; water purification; water reuse; rainwater harvesting; water supply schemes. The contribution of seawater and brackish water desalination would play an important role in augmenting the freshwater needs of the country.

Spray flash evaporator for low-temperature saline water desalination application

Abstract: A new spray-type flash evaporator is suggested for the application of saline water desalination. The flash evaporator is 1000 mm in height and 1200 mm in diameter, with a water injection arrangement inside. The evaporator design is based on experiments conducted at vacuum pressures between 10 and 18 mm of Hg, and at saline feed water temperatures between 26?C and 32?C. The saline water is injected into a vapouriser through a pair of high-flow swirl injectors with a nominal flow rate of 1.5 litre/sec. per jet and the distance between the injectors is taken as 200 mm for design. The influence of the different thermal, hydrodynamic and geometric parameters on the evaporator performances was investigated. The results obtained are presented, which prove the validity of the proposed system.

Seawater desalination utilising waste heat by low-temperature evaporation

Abstract: Utilisation of waste heat is one of the ecofriendly ways to produce low-cost desalted water. Keeping this in mind, Low-Temperature Evaporation (LTE) desalination technology utilising low-quality waste heat in the form of hot water (as low as 50?C) or low-pressure steam (0.13 bar) has been developed to produce high-purity water (conductivity <2 ?S/cm) directly from seawater. LTE technology has found major applications in nuclear reactors to produce high-quality desalted water for make-up water requirements. Continuous and successful operation of a 30 Te/day LTE desalination plant utilising waste heat from the CIRUS nuclear research reactor has demonstrated the safety, reliability, exceptional plant availability and economics of nuclear desalination by LTE technology. Utilisation of waste heat from the Main Heat Transport (MHT) purification circuit of an Advanced Heavy Water Reactor (AHWR) to produce about 250 Te/day of high-quality desalinated water is also proposed. Recently, we have commissioned a 50 Te/day two-effect low-temperature desalination plant with cooling tower where the specific energy and cooling water requirements are significantly reduced. This paper discusses the salient features of the LTE desalination plant, its applications and advantages.