Runru Zhu1, Yiyang Zhang 2, Ye Yuan3, Shuiqing Li4


State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
CFB Department, Huaneng Clean Energy Research Institute, Beijing 102209, China
Key laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China



Received: November 26, 2017
Revised: April 20, 2018
Accepted: April 30, 2018
Download Citation: ||https://doi.org/10.4209/aaqr.2017.11.0523 

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Cite this article:
Zhu, R., Zhang, Y., Yuan, Y. and Li, S. (2018). Deposition Loss of Particles in the Sampling Lines of Continuous Emission Monitoring System (CEMS) in Coal-fired Power Plants. Aerosol Air Qual. Res. 18: 1483-1492. https://doi.org/10.4209/aaqr.2017.11.0523


HIGHLIGHTS

  • Increasing Reynolds number leads to increase deposition of the sampling line.
  • Deposition velocity of PM1-2.5 will sharply increase with temperature difference.
  • The influence of pipe roughness is most profound for the loss of PM10 particles.

ABSTRACT


Due to the severe air pollution situation, more stringent regulations on pollutant emissions are being promulgated in China, necessitating more accurate and reliable monitoring of particulate matter (PM) emission in coal-fired power plants. In this work, we study the sampling loss of continuous emission monitoring system (CEMS) under different conditions by numerically solving the particle transport equation in the sampling line. With a high Reynolds number, the particle deposition loss is higher than in conventional laminar sampling and increases with the Reynolds number when the plant load changes. The temperature difference between the hot sampling gas and the pipe wall has a great effect on the sampling loss of PM10. A small temperature difference of 2 K, which is very likely to exist even with thick thermal insulation, will increase the deposition velocity of PM1-2.5 by ten times. The surface roughness, from either the pipe itself or deposited particles, also enhances the deposition loss by partly shifting the capture boundary to a higher diffusivity region. Combining all the possible factors, the loss ratio of 10-µm particles can reach 69% after 0.2 s and 95% after 0.5 s. The loss ratios of 2.5- and 1-µm particles are much lower but also reach 4.1% and 7.9%, respectively, after 1 s, which cannot be neglected when high accuracy monitoring is needed.


Keywords: Deposition; CEMS; Sampling; Coal-fired power plant

 



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