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Study on the Incineration of Tannery Sludge and 20t/d Hazardous Waste Incineration System

Author: FeiZhenWei
Tutor: NiMingJiang；JiangXuGuang
School: Zhejiang University
Course: Engineering Thermophysics
Keywords: Hazardous Waste TG FTIR Incineration Heavy Metal Infiltration
CLC: X794
Type: Master's thesis
Year: 2010
Downloads: 156
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Abstract

With rapid economic growth and living standards in China, many cities face the problem of hazardous wastes. So it is important that the basic researchments of hazardous wastes disposing are developed. The thermochemistrial method of incineration has a lot of merits such as the volume reduction, resouce utilization, innocuity and so on, so that it is abroad applied. However incineration of hazardous wastes can lead to the problem of environment pollution, especially the problem of abio-contaminates such as heavy metals because of a lot of hazardous wastes possessing of the element of heavy metals.Therefore it is extremely concerned to protect our living conditions that the researchments of contamination control of heavy metals are implemented.Basic reasearch on the incineration of tannery sludge and 20t/d hazardous waste incineration system has been carried out in this thesis. The main content of the researches involved are as follows:1) Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) tests were performed to characterize the thermal behavior and the emission characteristics of the sludge. It was shown that the thermaldecomposition of tannery sludge mainly occurs in a temperature frame between 150℃and 780℃. The main compounds of gas were CO2 and H2O.Hexene was determined as the most important gaseous pollutant in tannery sludge combustion at low temperature.2) Tannery sludge is considered a hazardous material because of its high content of heavy metals. The behaveors of different heavy metal elements (Pb,Cd,Cu,Zn,Cr and Mn) when tannery sludge was incinerated were investigated. The quantity of Pb, Zn, Cu, Cr, Mn and Cd decreased in the incineration while the furnace temperature raised. The release rate of eavy metals is 56.9%,96.0%,63.2%,25.7%,41.7%a nd 73.2% respectively while temperature reached 900℃. The evaporation effect of Pb、Zn and Cd is significantl and Zn is the easiest metal of evaporation while temperature reached 900℃.On the other hand, the enrichment effect of Mn is not significant and it belongs to relative stable metal, and the volatilization and enrichment effect of Cu are both not significant. Furthermore the quantity of Cr changes little during incinerateon, and the enrichment effect of Cr is significant relatively.3) Through the experiments of fly ash of Tannery Sludge leaching an stabilizing, we make clear of leaching characteristics on the every kind of conditions, and take the method of melting fly ash and bottom ash which can large descend the concentration of leaehing solution and make it get to the standards of lixiviating toxicity in Chnia.4) A multi-incineration system of rotary fluidizing and ash-cooling for hazardous waste was developed by the combination of rotary kiln and fluidized bed. The incineration system included primary chamber (rotary kiln), fluidized bed and secondary chamber. The problem of slagging in rotary kiln inside wall could be solved by the controlling of temperature at the rotary kiln inlet, the residence time of the incombustible slag could be prolonged by using the fluidizing and the ash-cooling device, so the problem of high value of the loss-on-ignition could be solved. The flue gas temperature could be lowered directly from 1100℃to 200℃by the flue gas quenching facility, thus the low-temperature regeneration of dioxin are prevented. Medical waste and majority of solid and liquid hazardous waste could be disposed by the stable system. The levels of flue gas pollutants emitted from the stack especially dioxin met national emission limits set by the Chinese EPA. The operation data of temperature distribution at the rotary kiln inlet, oxygen content at the outlet of secondary chamber with time, temperature changing with time of rotary kiln and furnace temperature distribution at the outlet of chamber had been described, valuable experience data for the operation of hazardous waste incinerator could be referred for commercial incineration plants.

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