SO₃ Migration and Emission Characteristics of CFB Boilers

Inner Mongolia Electric Power Scientific Research Institute Branch, Inner Mongolia Electric Power (Group) Company Limited, Inner Mongolia Autonomous Region, Hohhot 010020, China

^* nmdkyzyj@sina.cn

Abstract

In order to study the migration and transformation of SO₃ from circulating fluidized bed boiler (CFB) in the air preheater and flue gas treatment facilities, 10 circulating fluidized bed boilers with installed capacities between 150 MW and 330 MW were measured by controlled condensation method. Ten circulating fluidized bed boilers with installed capacities ranging from 150 MW to 330 MW were measured using the controlled condensation method. It is showed that the SO₃ removal rate of the air preheater was affected by the air preheater flue gas exit temperature, which ranged from 6.7 % to 36.5 %, and the SO₃ removal rate of the rotary air preheater was higher than that of the tubular air preheater. The SO₃ removal rate of cloth bag filter and electric bag filter is above 40 %; the SO₃ removal rate of electrostatic precipitator is between 6.1 % and 10.8 %. The SO₃ removal rate of wet desulfurization method ranges from 41.7 % to 73.4 %, with the highest SO₃ removal rate of double tower double cycle. The SO₃ removal rate of off-furnace CFB semi-dry desulfurization reached 89.7 %~97.9 %, and the dry process inside the furnace + off-furnace CFB semi-dry process could reduce the SO₃ at the desulfurization outlet to below 0.3 mg/m³ under the tested conditions. The conclusions of the test analysis in this paper can provide reference for SO₃ control in circulating fluidized bed boilers and related policy formulation.