Study On Co-Disposal Domestic Waste Of Villages And Towns In NSP KILN

On the basis of research of domestic waste in villages and towns and the distribution of new suspension preheater (NSP) kiln in Guang-xi, a new co-processing model is proposed to handle domestic waste by using NSP kiln. The trial was completed relying on the NSP kiln production line with capacity of 4500 t/d in a cement plant. The pre-processed domestic waste was feed into the end of tertiary air duct, then completely burned in the calciner. The study has been conducted to analyze the effect on the operation parameters and yield of the kiln system, clinker quality and pollutant emission when feeding the domestic waste at 20 t/d,50 t/d,80 t/d respectively. The main achievements of this study are summarized as follows:(1) It can be seen that domestic waste has plenty water and low calorific value. The chemical composition of incineration ash of waste is similar with that of the coal.Both of their silicon content was the highest, and followed by Ca, Fe, Al.(2) The kiln system can reduce the heat consumption of cement clinker without affecting the yield of cement clinker, and the heat consumption could be decreased by 10% at maximum relative to blank trial, when the amount of feeding domestic waste is less than 80 t/d.(3) The fluctuations of temperature and negative pressure of preheater system is more obvious during the stage of feeding the domestic waste, especially when the amount of feeding domestic waste reached 50 t/d. However, after stable feeding the temperature and negative pressure will change to normal state, and the parameter fluctuations of the production condition is still in the controllable range. At the same time, it has little effect on the average temperature and negative pressure within the limits of the feeding of the domestic waste at 80 t/d. Besides, the hazard to refractory of the kiln is not found during the trail.(4) The KH of clinker could be slightly reduced, while SM and IM have little change during feeding the domestic in NSP kiln. The clinker 28 d strength may be decreased slightly by co-incinerating domestic waste, but still meets the requirements of P·I 42.5 of timely state standard "Common Portland Cement".(5) The content of 14 species of heavy metals in waste ash and clinker is measured by ICP-MS. The results show that Cr, Mn, Ni and Pb are the most in the waste. After heated in kiln system, the majority of heavy metals will be fixed on the clinker finally due to alkaline and oxidizing atmosphere of NSP kiln.(6) There is no negative impact on the emissions of NOX、SO2 and particulate matter in the kiln gas within the limits of the feeding of the domestic waste at 80 t/d. The content of volatilizable heavy metals of particulate matter will increase as the feeding of domestic waste increased, and the content of non-volatile heavy metals is very low, both of which are in line with the timely state standards.(7) The detection result of dioxin in the flue gas from the stack of the kiln system is 0.0040 ng TEQ/Nm3 when the feeding of the domestic waste is 80 t/d. It is far below the limits of 0.100 ng TEQ/Nm3 of state standard.