To solve the serious deposition problems on the heating surface from a biomass-fired grate boiler in china, which had affected the normal operation of the plant, the characteristic of deposits from different heating surfaces was analyzed. The micromorphology characteristic and element analysis of the deposits was conducted by scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS), the crystal structure of the deposits were analyzed by X-ray diffraction(XRD). Influencing factors during the formating of the deposit including boiler designing, operating conditions, fuel properties were discussed. The results show that the high content of K,Ca,Cl and S in the fuels is the main reason for the deposition, KCl is the main component of the deposit, the high-Ca and low-Si in the fuel result in high-CaCO3 and low SiO2 and low silicate in the deposit; the content of Cl increases in the deposits from the water wall, high temperature superheater and low temperature superheater, while Ca and Si decrease with the decreasing flue gas temperature; the content of S increases rapidly in all the deposits layer close to the tube which exists in the form not only K3Na(SO4)2 but also CaSO4; because of the lacking of secondary air, the combustion of volatiles may cause reducing atmosphere in the upper space of the boiler, this favors the formation of K3Na(SO4)2 and eventually enhance the deposition problem.
GONG Bin, YU Chun-jiang, WANG Zhun, LUO Zhong-yang. Characteristic of deposits on different heating surfaces from a biomass-fired grate boiler. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2015, 49(8): 1578-1584.
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