African Journal of
Pure and Applied Chemistry

  • Abbreviation: Afr. J. Pure Appl. Chem.
  • Language: English
  • ISSN: 1996-0840
  • DOI: 10.5897/AJPAC
  • Start Year: 2007
  • Published Articles: 357

Full Length Research Paper

Microstructure contradistinction for indirect/direct desulfurization product layer of limestone particle in coal-fired flue gas

Jian-yu Shang1*, Zhong-liang Liu1 and Chun-bo Wang2
1College of Environmental and Energy Engineering, Beijing University of Technology, Beijing City, Chaoyang, 100124, China. 2School of Energy and Power Engineering, North China Electric Power University, Hebei Province, Baoding, 071003, China.
Email: [email protected]

  •  Accepted: 25 October 2013
  •  Published: 30 November 2013

Abstract

The micro morphology of limestone sorbent is a key for improving the SO2 removal efficiency in the coal-fired power plant. The tube furnace system was built for imitating the indirect desulfurization reaction in traditional boiler atmosphere (65%N2, 15%CO2, 4.7%O2, 15%H2O, 0.3%SO2) and the direct desulfurization reaction in oxygen-fired atmosphere (80%CO2, 4.7%O2, 15%H2O, 0.3%SO2). The reacted limestone particle samples were observed by SEM and are analyzed by Fourier transformation 3-D reconstruction technique. It is shown that the sizes of internal pore within sorbent particle in two kind atmospheres differ by an order of magnitude, one is about 200 nm for indirect desulfurization, and the other is about 20 nm for direct desulfurization. The CaSO4 products of indirect desulfurization are chaotic derivatives with serious blockage, and the direct desulfurization product layer belongs to uniform honeycombed micro-structure without blockage. Those numerous micro-porous passages can guarantee continuous reactive substance transmission.

Key words: Limestone powder, SO2 removal, particle surface, 3-D reconstruction, product layer.