Title : CHALLENGES INVOLVED IN DESIGN AND CONSTRUCTION OF 275M TALL CHIMNEYS
Authors : Vinay Gupta
Publication : 23 - 26 October 2013
Volume :
Pages :
Price : 250
Abstract : Thermal power has been found to produce large production capacity compared to hydropower. In order to exit the gases produced during burning of coal in thermal power plant, as per the latest pollution norms, 275 m tall chimney is required to exit the gases at that height. There are broadly two types of chimneys, namely (i) single-flue chimney and (ii) multi-flue chimney. Chimneys require ining, which can be in brick or metal (with insulation). Number of flues in case of Multi-Flue Chimney can be as many as 5, but usually there are two. The maximum size of each metallic flue has been of the order of 8.0m diameter. The concrete Wind Shield is mostly designed for wind loads namely Along Wind and Across Wind. While along wind effects are straightforward, across wind loads are caused due to vortex shedding and are complex to analyse. Wind analysis can be done using mean-hourly wind using gust factor or 3 second gust wind effect. The former is internationally more recognized as latest theory. Two closely spaced chimneys are adversely affected by aerodynamic interference, which needs to be accounted for. In addition to the above, chimney is designed for earthquake loads and temperature effects apart from vertical loads. Foundations may be spread footing or pile foundation, solid circular or annular, depending upon the sub-surface characteristics. Chimney is constructed using slip-forming or jump- forming technique.