Abstract
This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW) flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ.
Highlights
The rapid development of modern society has resulted in the production of an increasing volume of municipal solid waste (MSW)
For the flame of the MSW incinerator, strong characteristic emission lines of Na and K are observed in the visible spectra in the experiments, and more studies are needed to know if this type spectrum could be used for measurement temperature, while related works are relatively few in number
As the absolute spectral intensity distribution of the MSW flames depicted in Figure 3b shows, it can be seen that the peak intensities of the Rb emission lines are too weak to be identified
Summary
The rapid development of modern society has resulted in the production of an increasing volume of MSW. The disposal, treatment and management of MSW are common problems in the world. Incineration has been widely used for the disposal of MSW in order to conserve fuel and protect the environment by lessening the amount of MSW in landfills [1,2]. Emissions of trace organic compounds— polychlorinated dioxins and furans, and heavy metals such as mercury, lead and cadmium—are major environmental hazards caused by MSW incineration. Alkali and alkaline earth metals are typically found in high concentrations in MSW. These alkali metal compounds often contribute to the fouling and corrosion of the heating surfaces of fluidized bed and
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