Numerical simulation of the heat transfer and NO X emissions in a 660 MW tangentially fired pulverised-coal supercritica
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ORIGINAL
Numerical simulation of the heat transfer and NOX emissions in a 660 MW tangentially fired pulverised-coal supercritical boiler Sankar G 1 & Chandra Sekhar Dhannina 2 & Santhosh Kumar D 1 & Balasubramanian K R 3 Received: 7 September 2019 / Accepted: 10 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Numerical simulation of the influence of operating conditions of the furnace on its performance characteristics like heat flux distribution, Furnace Exit Gas Temperature (FEGT) and NOx emission levels was performed for a tangentially fired pulverised coal boiler. The results revealed that the FEGT and NOx emission are slightly higher when the top seven coal nozzles are in operation compared to the bottom seven coal nozzles. While the increase in burner tilt led to an increased FEGT, the least NOx emission was obtained for the burner tilt with 0°. The NOx emission started to increase with both increase and decrease in tilt from 0°. In addition, the FEGT and NOx emission were directly and inversely proportional to the percentage of SOFA (Separated OverFire Air) opening respectively. NOx emission was lower by around 7.5% when the air staging was done with the top-most SOFA nozzle instead of the bottom-most SOFA nozzle. However, the FEGT was higher in the former case. Keywords Heat flux distribution . Tangentially fired boiler . Indian coal . NOx emission levels . Tilt . SOFA opening
1 Introduction Coal-fired thermal power plants contribute to nearly 60 to 65% of the electrical power generated in India. Boilers of these power plants are expected to meet the following requirements: i) quick and effective response to frequent variations in grid demand due to the surge of non-renewable power generation methods and ii) operation at a higher efficiency to mitigate the pollutants like NOx and SOx in order to concur with the recent environmental standards [1]. These requirements pose a greater challenge to the boiler designer in arriving at an optimum furnace design. FEGT and NOx emission levels
* Sankar G [email protected] Chandra Sekhar Dhannina [email protected] Santhosh Kumar D [email protected] Balasubramanian K R [email protected] 1
Bharat Heavy Electricals Limited, Tiruchirappalli, India
2
Indian Institute of Technology, Madras, India
3
National Institute of Technology, Tiruchirappalli, India
are two critical parameters monitored to evaluate the performance of boiler furnace in a boiler industry. It is necessary to monitor the FEGT continuously since it affects the entire dynamics of the operation of the boiler. A typical practice is to measure the heat flux absorbed by the waterwalls and compute the FEGT by solving an inverse heat conduction problem [2]. However, it is not preferred to measure the heat flux at various locations since it is not cost effective. The other vital parameter that needs to be monitored is the amount of NOx emission at the boiler outlet. It is always required to closely monitor NOx emission levels in a powerplant after the recent enforcement of st
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