es9b06569_si_001.pdf (844.9 kB)
Evolution of Condensable Fine Particle Size Distribution in Simulated Flue Gas by External Regulation for Growth Enhancement
journal contribution
posted on 2020-03-09, 17:06 authored by Chenghang Zheng, Hao Zheng, Jiali Shen, Wenchao Gao, Zhengda Yang, Zhongyang Zhao, Yifan Wang, Hao Zhang, Xiang GaoCondensation
fine particles (CFPs) from coal-fired flue gas harm
humans and the environment after being emitted into the atmosphere.
Given their small size (<0.1 μm), difficulty arises in efficiently
removing CFPs by wet electrostatic precipitators and mist eliminators.
In this work, a laboratory apparatus was used to study the CFP growth
under simulated power plant conditions. Four methods were independently
investigated to increase the particle size: addition of ammonia, addition
of fly ash, decreasing temperature, and applying an electrical discharge.
Results demonstrated that the CFP size distribution possessed a unimodal
structure with peak at 0.05 μm. At increased ammonia concentration
from 10 to 30 ppm, the peak of growth factor shifted rightward and
increased from 1.21 to 1.35 and the range of growth factor >1 was
significantly broadened due to joint action of multiple mechanisms.
Fly ash acted as the core, and CFPs adhered to the ash surface when
forming ash–salt droplets. Cooling flue gas could also enhance
the CFP growth due to vapor condensation. At decreased temperature
from 45 to 30 °C, the median diameter of CFPs increased by 15%.
Finally, the growth and agglomeration of CFPs can be further enhanced
when an external electrical field was utilized. The size range of
growth factor >1 can be broadened, and the peak growth factor significantly
increased at 8 kV applied voltage. The research findings provide valuable
guidance for effectively improving the CFP removal efficiency by external
regulation for growth enhancement.