P. Balasubramanian ¹, V. E. Nethaji Mariappan ², D. Joshua Amarnath ²

Affiliations
1 Centre for Remote Sensing and Geo informatics, Department of Chemical & Environmental Engineering, Sathyabama University, Chennai, Tamil Nadu, IN
2 Centre for Remote Sensing and Geo informatics, Department of Chemical & Environmental Engineering, Sathyabama University, Chennai, Tamil Nadu, IN

Abstract

Thermal stations use coal as combustion material for fuel and the chemical energy stored in coal, which is converted successively into thermal energy, mechanical energy and finally electrical energy for continuous use and distribution across a wide geographic area. A study was conducted on a particular thermal power station to identify the ash disposal & storage system and the alternate design of the existing ash storage system since thermal stations use pulverized coal as fuel to generate electrical energy and produce ash as by-product. As such, Ennore thermal power station draws coal from Indian mines like Mahanadhi coal fields, Orissa (IB Valley, Talchar), Eastern coal field, Ranikanj and also imported coal from Australia & Indonesia is used. Indian coal has a high ash content exceeding 40%, with low calorific value but economical. In comparison the imported coal has a low ash content of less than 13%, high calorific value but costlier. As the residual end product of ash is more in Indian coal the concern on the need for safe storage, disposal for effective utilisation of flyash, a strategic approach evolving potential remedial measures to mitigate leaching of toxic minerals from the ash storage pond is necessary and the same is carried out in this study since wet ash is stored in ash ponds apart from disposal of dry ash at the source. Ash storage pond is constructed with high mounds of earth with filter media. To avoid contamination of the adjoining lands, streams and aquifers a reinforced cement channel drain along the ash bund is designed to collect the seepage of chemicals with a sloped gradient for further treatment of the leachate. Also as a Phyto-remediation specific species of plants as hyper-accumulators are planted along the downstream side slope of the bund and this absorbs the toxic minerals as well as strengthens the bund from breaching.

Keywords

Coal, Fly Ash, Leachate, Collection Drain, Phyto-remediation

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P. Balasubramanian ¹, V. E. Nethaji Mariappan ¹, Joshua Amarnat ²

Affiliations
1 Centre for Remote Sensing and Geo informatics, Sathyabama University, Chennai, IN
2 Department of Chemical & Environmental Engineering, Sathyabama University, Chennai, IN

Abstract

Thermal stations use coal as combustion material for fuel and the chemical energy stored in coal is converted successively into thermal energy, mechanical energy and finally electrical energy for continuous use and distribution across a wide geographic area. The steam exits the boiler, turbines and passes over cool tubes in the condenser. The condensers capture the used steam and transform it back to water. The cooled water is then pumped back to the boiler to repeat the heating processes. At the same time, water is piped from sea to keep the condensers constantly cool. This cooling water, now warm from the heat exchange in the condensers, is released from the plant. Large quantity of sea water is drawn to the tune of 1760 MLD in the Ennore thermal power station for cooling of condenser tubes. After the cooling purposes the return warm water is cooled and discharged back into the sea through tunnel of 2.50m diameter and subsequently through an open channel near outfall structure of the coast. Discharged hot water at the very first source of exit from the thermal station with a temperature of about 8°C can be used for heat conversion. The method of LTTD (Low Temperature Thermal Desalination) offers ideal scope for utilization of the already hot water which need not require pre-heating as the method of desalination utilizes 38°C of temperature in the flash chambers by evaporation and subsequent condensation in the shell and tube condensers of the steam using the sea water with low temperature. Thus an emphasis is made here for avoidance of purchase of raw water for all purposes and avoids tapping of ground water with zero environmental pollution. The brine thus emulated from the process is diluted using the already drawn effluent and discharged into the sea. The study of desalination is to determine and combine available technologies to optimize water production costs and quality. For which a number of factors determine the capital and operating costs for desalination: capacity and type of facility, location, feed water, labour, energy, financing, and concentrate disposal.

Keywords

Coolant Water, Desalination, Flash Chamber, Vacuum Pump, Brine

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