Study On The Combustion Characteristics And Heavy Metal Emission Characteristics Of Municipal Sewage Sludge In Fluidized Bed

The combustion characteristics and heavy metal emission characteristics of sludge fluidized bed incineration were mainly studied in this paper.Firstly, the origins, kinds and harmfulness of sludge were introduced, and the treatment methods of sludge and the treatment status of sludge in China were analyzed. Based on the review of sludge fluidized bed incineration, the research contents in this paper were determined.The agglomeration characteristics of sludge in fluidized bed incinerators were studied, and the effects of bed temperature, moisture of sludge, feeding size and mixed proportion of coal in the sludge on the agglomeration of sludge were examined. The effects of the moisture content in sludge on energy recovery and theoretical combustion temperature were detailedly analyzed in this paper. Compared with common fuel such as coal, the dried sludge is special and complicated. The combustion characteristics of the dried sludge were studied by using thermogravimetry. Based on the TG, DTG, DTA curves of the dried sludge, the parameters of sludge combustion kinetics were calculated.The incineration experiments of wet sludge (co-firing with auxiliary fuel) and dried sludge (solely firing) in a 150mm fluidized bed incinerator were mainly introduced. The stabilities of bed temperature and bed of materiel were examined, and the secondary pollutant emissions were tested. Through the incineration experiment of dried sludge in fluidized bed incinerator, the operation experience and pollutant emission characteristics of sludge fluidized bed incineration were grasped.The incineration experiment of the sludge of in a lab-scale fluidized bed incinerator was performed. The contents of heavy metal (such as Cu, Ni, Cd, Cr, Hg, Zn and Pb) in dried sludge and its incineration slag of different incineration time and different operation conditions were tested by using atomic absorption method, and the distribution of Hg in the flue gas was also tested. The transformation characteristics of heavy metal in sludge were realized, which provides guidance for the treatment of sludge incineration productions.Based on the problem existing in sludge incinerator of Taopu sewage treatment plant in Shanghai, the calculation and analysis of thermal system of sludge incinerator were performed. Furthermore, the cost-effectiveness analysis about that coal is used as auxiliary fuel was performed.