| With advancement of urbanization, amount of sewage sludge is produced in sewage treatment. If mishandled, the sewage sludge will become secondary pollution. The deeply dewatering of sewage sludge will create advantageous condition for the disposal, deeply dewatered sewage sludge will become the main object of sludge disposal. Sewage sludge incineration with the advantages of volume reduction, stabilization, harmlessness and energy recovery, is considered to be the important way among the methods of sludge disposal.In this paper, studying on the combustion characteristics of the deeply dewater sludge after FeCl3/CaO conditioning with the thermogravimetry at first. The research showed that four degradation stages were identified in the combustion process of the deeply dewatered sewage sludge. They were dehydration, the combustion of volatile 1, the combustion of volatile 2 and the fixed carbon, and the decomposition of inorganic matter which was made mainly of CaCO3. As the dosage increased, both the combustion index and the devolatilization index were improved, which means adding FeCl3/CaO was helpful for the initial combustion. However, the burnout index and the general combustion parameter went through a slight rise before they got to downward trend, which implies the appropriate dosage was good to the combustion. With increased heating rate, the characteristic curves of sewage sludge move to the higher temperature zone, general combustion performance of the sewage sludge can also be improved. which was good for combusting sludge. Different atmospheres conditions, the sludge samples showed different characteristics. Compared to air, under the nitrogen and oxygen, the sludge would reaction more thoroughly. The sludge sample reaction rate from fast to slow was oxygen>air> nitrogen.Then the dynamics of sludge combustion was calculated. According to it, the reaction order of pre-peak was 0.5 and post-peak was 2.The apparent activation energy of the first devolatilisation peak before would increase with the addition of FeCl3/CaO, the increasing of heating rate or the content of oxygen increasing.After that, using a laboratory tube furnace and IC to study HCl and SO2 emission characteristics of the deeply dewater sludge in incineration. It showed that as the temperature from 600℃ to 900℃, the average SO2 and HCl concentration presented a gradually increasing trend. The SO2 emissions would reduce after conditioning with FeCl3/CaO. The HCl emissions would increase after conditioning with FeCl3/CaO. FeCl3/CaO as conditioner could reduce SO2 emissions, but HCl emissions would increase. But from the conversion rate of Clâ†'HCl, the conditioner could fix the Cl. When the temperature over 800℃, S and Cl fixation were weakened with FeCl3/CaO.At last, on the basis of analysis on heavy metal content in incineration the distribution of heavy metals in incineration residue was discussed in the dissertation. The experiments was conducted at temperature of 600℃,700℃,800℃,900℃ in order to investigate the temperature on the distribution of heavy metals (Pb, Zn, Cu, Ni> Cr, Cd, Fe) in incineration residue. It found that the distribution of heavy metals in combustion residue was affected by the characteristics of heavy metals and incinerating temperature. Cd had the best volatile and it had the lowest residual rate in combustion residue. And Ni, Cu, Cr had higher residual rate. The conditioning with FeCl3/CaO would change the volatile of Cu and Cr in the sludge. |
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