IMPACT OF FLUE GAS RECIRCULATION ON DISTRIBUTIONS OF TEMPERATURE AND SOLIDS CONCENTRATION INSIDE A LARGE-SCALE SUPERCRITICAL CFB BOILER

摘要

The purpose of this work was to determine the impact of a flue gas recirculation (FGR) on the furnace temperature and the solids suspension in a 966MWth supercritical circulating fluidized bed (CFB) boiler. A performance test on a 1296t/h supercritical CFB boiler was carried out for 80% unit load at high level of bed pressure (ca. 7.0kPa) and also under excess air ratio in the range of 1.21-1.30. Furthermore, the recirculation flue gas mass flow (20.5 m_n~3·s~(-1)) and the ratio of secondary air to the primary air (0.11-0.33) were considered as experimental variables. Measurement data for FGR test run was compared with data from the others tests. Whereas flue gas recirculation into CFB furnace, the vertical temperature profile had quasi-linear character as opposed to air staging test runs. A significant difference (ca. 560 times) in the suspension density between the grid zone and the upper part of the furnace was observed.The results obtained from this work remain in agreement with the experimental data for the CFB boilers.