es9b04747_si_001.pdf (558.5 kB)
Applications of Ultrafine Limestone Sorbents for the Desulfurization Process in CFB Boilers
journal contribution
posted on 2019-11-08, 19:46 authored by R. Cai, X. Ke, Y. Huang, S. Zhu, Y. Li, J. Cai, H. Yang, J. Lyu, M. ZhangWith
the stringent emission regulation taking effect, it is difficult
for the conventional desulfurization technology in circulating fluidized
bed (CFB) boilers to meet the requirements of ultralow SO2 emission. Therefore, in this paper, the application of natural ultrafine
limestone, with a Sauter mean diameter of less than 20 μm, was
tested by conducting bench-scale, pilot-scale, and commercial-scale
experiments to realize highly efficient desulfurization in CFB furnaces.
In the past, such small-size limestone was considered unsuitable for
CFB boilers. However, as demonstrated by bench-scale results, the
desulfurization performance was clearly superior to that of coarse
limestone, especially at low SO2 concentrations. In a 3
MWth pilot-scale CFB boiler, the ultrafine limestone exhibited
competent desulfurization efficiency to that of the coarse limestone
but clearly less significant catalytic effects on NOx formation. As
revealed by field tests in four commercial-scale CFB boilers, when
high-efficiency cyclones were applied to CFB boilers, the mass inventory
of ultrafine particles was significantly increased and the residence
time would be extended accordingly; thus, the ultrafine limestone
can be used to achieve high desulfurization efficiency and even ultralow
SO2 emission with a favorable Ca/S ratio. Furthermore,
a technical roadmap was drawn for the cost-effective control of SO2 emission.