2006 Fiscal Year Final Research Report Summary
Investigation of measurement method of heavy metal compounds in fine particles from waste combustion flue gas using supersonic flow
| Project/Area Number |
17510064
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental technology/Environmental materials
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| Research Institution | Kanazawa University |
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Principal Investigator |
HATA Mitsuhiko Graduate School of Natural Science and Technology, Research Associate, 自然科学研究科, 助手 (00334756)
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| Co-Investigator(Kenkyū-buntansha) |
FURUUCHI Masami Graduate School of Natural Science and Technology, Associate Professor, 自然科学研究科, 助教授 (70165463)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Supersonic flow / Waste combustion / Impactor / Flue gas / Heavy metals |
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| Research Abstract |
For the first step, two approaches are used to investigate the transformation of heavy and alkali metals during waste incineration: a thermodynamic equilibrium calculation and experiments using a bench-scale combustor. The distribution of heavy and alkali metals at different temperatures (800, 700, 600, 400, and 200℃) is studied in these experiments. The chemical equilibrium calculation shows that vaporized metallic compounds form a condensed phase at different temperatures.The calculation results show that vaporized lead compounds begin to transfer to the solid phase at 500℃. The main species of solid lead in the flue gas is PbC12(s) below 500℃. Zn and K have the same temperature range (300-500℃), while the conversion temperature for As is 600℃ and that for Na and Cu is above 800℃. The experimental results also prove the feasibility of separating heavy and alkali metals according to their gas-solid transformation temperature zones. On the basis of the experimental results, the optimum
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separation temperature is <400℃ for Pb and K, 600℃ for As, and 800℃ for Cu, Zn, and Na. It was found that generation rate of the metal compounds could be described by exponential function of temperature.
A super-sonic impactor using a Laval nozzle, which has been developed for size control of ultra-fine aerosol particles down to nano-size range, was basically tested for the sampling of ultra-fine ambient aerosol. Ambient aerosol was classified into two different size classes, or<ca.200nm and above, by the super-sonic impactor and PAHs were analyzed as a typical index of anthropogenic air pollutants. When the humid air was sampled, concentration of PAHs larger than four benzene rings of particles collected on the backup filter downstream the supersonic impactor decreased probably because of the influence of condensation of water vapor, which leads to the increase in particle size. There may be a possibility of an increase in collected amount of semi-volatile compounds to the backup filter due to the influence of super-saturation. However, flue gas has much higher moisture content, which will cause problem at high temperature flue gas sampling.
In order to suppress the effect of super saturation by adiabatic expansion, subsonic aerosol sampler was tested. For the ambient temperature sampling of flue gas from waste combustion, adiabatic expansion has suppressed and nanoparticles could be classified. For the original objective, the sampling method should be tested at high temperatures for heavy metal compounds base on the basic test results. Less
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