Applications of ultrafine limestone sorbents for the desulfurization process in CFB boilers
Desulfurization by limestone injection into the furnace is one of the most competitive merits of circulating fluidized bed (CFB) boilers, however, with the implement of the strict emission regulation, the conventional CFB designs and the sorbent technology are difficult to meet the requirements of ultra-low emission of SO2,especially for those burning high-sulfur coals.Achieving the sufficiently high sulfur removal requires a considerable increase in Ca/S molar ratios, and even the installation of wet flue gas desulfurization systems, which will easily lead to the raised NOx, the reduced combustion efficiency, the increased investment cost and some other operation problems.Therefore, in this paper, applications of natural ultrafine limestone sorbents,whose Saunter mean particle size was less than 20 μm, were tested and verified by batch-scale, pilot-scale and commercial-scale experiments for realizing the high-efficiency sulfur retention in CFB furnaces.The batch-scale results showed that ultrafine limestone could reach 40% sulfation conversion within several minutes at 1000 ppm SO2, and the desulfurization performance of it was much better than that of coarse limestone at low SO2 concentrations.Then the same limestone with ultrafine and coarse particle sizes were compared in a 3 MWth pilot-scale CFB boiler for their desulfurization performance, and the results showed that the ultrafine limestone had the competent sulfur removal efficiency to the coarse limestone, but much less catalytic effect on NOx formation.The field tests in four commercial-scale CFB boilers revealed that when the high-efficiency cyclones applied to CFB boilers, the mass inventory of fine particles can be significantly increased and the residence time will be accordingly lengthened.Thus the ultrafine limestone can be used to realize the high desulfurization efficiency and even the ultra-low SO2 emission.
Ultrafine Limestone CFB Sulfur Dioxide Ultralow
R.Cai Y.Huang Y.Li M.Zhang X.Ke J.Cai H.Yang J.Lyu
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,, Tsinghua University, Beijing 100084,China
国际会议
Proceeding of 2nd Conference of Circulating Fluidized Bed Boiler ( 第二届国际循环流化床锅炉会议)
青岛
英文
73-85
2019-07-19（万方平台首次上网日期，不代表论文的发表时间）