Characteristics of Fly Ash from Thermal Power Plants and its Management along with Settling Pond Design
Abstract
World over for production of power pulverized coal fired boilers are extensively used. In India also 80% power is produced by pulverized coal fired boilers in National Thermal Power Plants. A very huge amount of ash is produced from these boilers. The quality of ash varies from plant to plant and from coke to coke depending on source of supply and type of combustion. In this dissertation an attempt has been made to categories problems and solutions related to it as given below:
For disposal of fly ash various kinds of ash ponds have been discussed, Design and economic aspects have been given. The effect of various type of ash/fly ash on air, land, water, agriculture living creature and human beings have been described. Some solutions have also been suggested. Experimental effect of addition of polymer carboxy methyl cellulose in slurry have been found to increase ash settling rates. For getting optimum ash settling rates 2ppm addition of carboxy methyl cellulose is found to be satisfactory. Utilization of fly ash for production of useful products has been mentioned.
Keywords
Download Options
Introduction
World over for production of power pulverized coal fired boilers are extensively used. In India also 80% power is produced by pulverized coal fired boilers in National Thermal Power Plants.[1] A very huge amount 200 million tons of ash is produced from thermal plants. The quality of ash varies from plant to plant and from coke to coke depending on source of supply and type combustion. Fly ash is a very fine material produced by burning of pulverized coal in a thermal power plan. Fly ash is a general name used for the residual products of combustion that rise with flue gase. Fly ash, also known as flue ash, it is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. In an industrial context, fly ash usually refers to ash produced during combustion of coal. It is carried by the flue gas and is collected by the electrostatic precipitators or cyclones. Chemically and physically, fly ash can have many forms like C-fly ash and F-fly ash depending upon the type of fuel burned and handling methods. A typical fly ash contains a significant amount of silicon dioxide and calcium oxide, which make it frictional and abrasive. Usually, fly ash has a fine particle size distribution with most less than 100 microns. Given the fine particle size, frictional nature and high temperature, fly ash can be a difficult material to handle reliably. Quantity does pose challenging problems, in the form of land usage, health hazards, and environmental dangers [2].
In India coal/lignite based thermal power plants account for more than 55% of the electricity installed capacity and 65% of electricity generation. The ash content of the coal used at the thermal power plants ranges from 30-40%, with the average ash content around 38%. Since low ash, high grade coal is reserved for metallurgical industries. The thermal power plants have to use high ash, low grade coal. The thermal power plants ash generation has increased from about 40 million tonnes during 1993-94, to 120 million tons during 2005-06, and is expected to be in the range of 210 million tons per year 2012.
Conclusion
For disposal of fly ash various kinds of ash ponds have been discussed, Design and economic aspects have been given. The effect of various type of ash/fly ash on air, land, water, agriculture living creature and human beings have been described. Some solutions have also been suggested. Experimental effect of addition of polymer carboxy methyl cellulose in slurry has been found to increase ash settling rates. For getting optimum ash settling rates 2ppm addition of carboxy methyl cellulose is found to be satisfactory. Utilization of fly ash for production of fly ash bricks/blocks, cellular concrete product, light weight aggregates, cement production, agricultural land fills, mine filling and in road construction have been suggested.