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Condition Monitoring of Limestone and Soft Sensing Model of SO2 Emissions in a Circulating Fluidized Bed Boiler

Zhang, Wenguang, Zhang, Yue, Sun, Yazhou, Liu, Jizhen, Gao, Mingming, Zeng, Deliang
Energy & Fuels 2016 v.30 no.4 pp. 3519-3528
calcium carbonate, calcium oxide, desulfurization, emissions, flue gas, fluidized beds, furnaces, limestone, models, monitoring, prediction, sorbents, sulfur dioxide, China
Soft sensing models of the desulfurization process are developed in a circulating fluidized bed (CFB) boiler that can capture sulfur dioxide (SO₂) with the limestone sorbent in the furnace. First, calcining utilization of CaCO₃ and sulfating utilization of CaO are proposed by mechanism analysis of the theoretical air and flue gas, and the online prediction method is achieved by using an adaptive-tree-structure-based fuzzy inference system (ATSFIS). Second, condition monitoring models of active CaCO₃, active CaO, and soft sensing model of SO₂ emissions are studied by using the experimental data of a CFB boiler in China, which can monitor the storage and condition of the limestone in the furnace and predict SO₂ emissions. Finally, a nonlinear proportional–integral–derivative (PID) control system based on the above models is designed to control the feed rate of limestone for the reduction of SO₂ emissions. The simulation results show that the soft sensing models are consistent with the mechanism test results and can accurately predict SO₂ emissions. The control system of limestone is also proven to be effective.