| With the rapid development of economy,much environmental problems caused by solid hazardous wastes are becoming more and more prominent.Meanwhile,the management of hazardous waste safely is also harder since its large variety,wide distribution and complex composition.So far,the heat treatment of hazardous waste has been widely used because of its large degree of reduction and harmlessness,and rotary kiln incineration is one of its important disposal processes.This work is focus on the technique research and data analysis on the harmless disposal of typical hazardous waste in Ningxia which based on actual processing of hazardous waste and medical waste disposal facilities of Ningxia Dekun Environmental Protection Technology Industry Group Co.,Ltd(formerly Ningxia Hazardous waste and Medical waste disposal Center).Also the influence of tilt angle,rotational speed,furnace temperature and material residence time on incineration efficiency was studied by using single factor method.Through the above research,the basic data of physical and chemical characteristics and incineration efficiency of typical hazardous waste were obtained.The results are as follows:(1)Under the condition of the counter flow rotary kiln as the basic furnace type,the basic incineration process model was explored using coal as the basic material.Furthermore,the incineration process was studied by controlling the incineration process parameters of countercurrent rotary kiln system,such as the incineration efficiency of basic material,flue gas composition and heavy metal migration.The ideal incineration efficiency of countercurrent rotary kiln was also analyzed by the rotary kiln inclination angle,rotation speed,incineration temperature,incineration time.It is found that when the incineration temperature is 900℃ and the residence time is 30 min,the incineration efficiency is relatively stable and changed within the standard range.On the basis of above research,combination the actual operation process,it shows that the overall incineration efficiency was in good condition when the furnace body inclination angle and rotating speed are about 3 degrees and 1.5 R/min respectively.(2)The stable furnace temperature has obvious effects on the incineration removal rate(DRE),weight loss rate and thermal ignition loss rate(P).Under the optimized conditions,the incineration removal rate and weight loss rate increased with the increase of the incineration temperature and the residence time in the furnace;the thermal ignition loss rate is just the opposite.In addition,when the final temperature reaches 1000℃,the removal rate by incineration(DRE)and the weight loss rate reach a stable state,and the thermodynamics get the end.(3)Since the different of the characteristics of medical waste,the process of incineration and the gas production of incineration tail gas shows a big difference.Also the content of hydrocarbons in the exhaust gas of the medical waste incineration is relatively higher because of the large amount of oxygen-containing compounds.Meanwhile,the negative pressure state may cause air leakage in the back section of the counter flow rotary kiln system in actual operation,the concentration of CO2 and CO in the incineration tail gas were fluctuated,which can affected the actual thermodynamic rate of the incineration reaction.(4)The incineration efficiency of typical hazardous wastes such as waste mineral oil,residues from distillation and heavy metal sludge increased with the increase of the temperature of the rotary kiln.Meanwhile,some heavy metal components may migrated when the hazardous waste contains high heavy metals(such as electroplating residues,etc.),.In addition,the increase of temperature may cause the migration of some heavy metal components;and for some hazardous wastes with high chlorine content(more than 0.2%).In this condition,it needs dechlorination treatment to achieve compliance with exhaust gas emissions. |
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