Desulfurization reactant gas-solid coupled diffusion within CaO grain aggregate in the flue gas of coal-fired power plant

ABSTRACT

There is still room for further improvement in the SO₂ removal efficiency of dry limestone desulfurization in the coal-fired power plant. The micro-structure of limestone particle is experimentally investigated by thermogravimetric analysis, scanning electron microscopy, and Mercury porosimeter. Gaseous diffusion theory and solid-state ion diffusion theory are coupled to derive dimensionless mass transfer equations, which are verified by thermogravimetric analysis in 3,000 ppm SO₂. It is derived that solid-state ion diffusion controls the initial reaction stage. More attention should be paid to the fact that any pathway to improve solid-state ion diffusion velocity is useful for limestone desulfurization efficiency.

KEYWORDS:

• Aggregate
• gas-solid coupled diffusion
• limestone
• product layer
• SO₂

Additional information

Funding

The authors gratefully acknowledge the support granted by the National Key Technology R&D Program of China (2012BAC24B01), National Natural Science Foundation of China (51276064), Beijing Postdoctoral Research Foundation (2012ZZ-19), and Beijing Natural Science Foundation (3132028).