Energy Reports (Jul 2022)
Study on the effect of supercritical CFB boiler air preheater and flue gas treatment facilities on sulfur trioxide emission characteristics
Abstract
The current situation of air pollution in China is very serious, and the control of non-conventional pollutants in addition to conventional air pollutants has received more and more attention. The emission of SO3 in flue gas has attracted widespread attention due to the environmental hazards and equipment problems caused by it, and the study of its emission characteristics and control strategies is the basis for national, local and industry to formulate relevant policies and implement emission control work. The SO3 monitoring and emission control study of a supercritical circulating fluidized bed boiler was carried out based on the controlled condensation method of on-site flue gas sampling, laboratory testing, and instrumental analysis of coal and ash samples, and the synergistic SO3 removal capability of the air preheater and flue gas treatment facilities was explored and summarized. The results showed that the SO3 co-removal rate of the four operating conditions of the test unit ranged from 74.34% to 88.51%, and the highest SO3 co-removal rate (88.51%) was achieved when the SNCR ammonia to nitrogen molar ratio was 1.2 and the slurry pH of the desulfurization system was 5.45 (primary tower) and 6.28 (secondary tower). During the test period, the differential pressure of the air preheater basically fluctuated between 1.245 kPa–1.326 kPa under the operating conditions of working condition 2, with no significant increase. For the same type of unit, the ammonia to nitrogen molar ratio and wet FGD slurry pH can be adjusted to reduce SO3 emissions.
