Aiming at the problems occurred on a circulating fluidized bed(CFB) boiler in 2×300 MW unit

such as serious abrasion of the vortex finder

low separation efficiency of the separator and high urea consumption

the vortex finder of the separator was optimized and retrofitted.The performance test was carried out after the retrofitting.The result shows that

the thermal efficiency increased due to the improvement of external circulating efficiency.The consumption of urea solution greatly reduced

which has decreased by about 77% under the full load condition.The differential pressure on the upper part of the boiler furnace increased by 0.2 kPa averagely

and the pressure drop of the separator increased by about 100 Pa.The bed temperature decreased by 24～40 ℃ at the test loads.The average particle size of fly ash decreased.The particle size with the cumulative distribution of 50% decreased from 26.0 μm to 13.3 μm

and the proportion of fine particles increased significantly.The separator efficiency improved significantly.