THERMAL SCIENCE

International Scientific Journal

COUPLED SIMULATION ON FLUE GAS AND STEAM DEVIATION OF FINAL REHEATER IN A 600 MW TANGENTIALLY FIRED BOILER WITH REVERSED SEPARATED OVERFIRE AIR UNDER DIFFERENT LOADS

ABSTRACT
Flue gas and steam deviation of the final reheater is an inevitable problem in the tangentially fired boiler due to the remaining gas spinning at the furnace exit. An in-house 1-D process simulation code coupled with comprehensive 3-D combustion simulation was adopted to accurate investigate the characteristics of the flue gas and steam maldistribution of the final reheater in a 600 MW supercritical tangentially fired boiler. Firstly, the combustion simulation result was validated by the in-house fire-side heat transfer calculation data, then the effect of boiler loads and reversed separated overfire air (SOFA) deflection angles on the gas temperature deviation, velocity deviation and outlet steam temperature of reheater were conducted. The results showed that the deviation of flue gas temperature and velocity increases as the boiler load decreases. The reversed SOFA deflection angle plays a crucial role in improving the gas distribution under low loads, and the deviation of flue gas temperature and velocity is the smallest when the angle is –18° under 100% boiler maximum continuous rating (BMCR), 75% and 50% turbine heat acceptance (THA), but it is the smallest when the angle is –9° under 35% BMCR load. Moreover, the maximum outlet steam temperature difference between parallel heating surfaces of the final reheater increases from 84.68-106.48 K as the boiler load decreases from 100% BMCR to 75% THA, and it is mainly affected by the flue gas temperature deviation rather than the mass-flow rate maldistribution when the deflection angle changes from –9° to –18°.
KEYWORDS
PAPER SUBMITTED: 2024-05-17
PAPER REVISED: 2024-07-25
PAPER ACCEPTED: 2024-08-01
PUBLISHED ONLINE: 2024-10-12
DOI REFERENCE: https://doi.org/10.2298/TSCI240517217W
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2025, VOLUME 29, ISSUE Issue 2, PAGES [983 - 997]
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2025 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence