A computational study of soot formation in ethylene/air coflow jet diffusion flame at atmospheric pres-sure was conducted using a reduced mechanism and soot formation model. A 20-step mechanism was derived from the fu...A computational study of soot formation in ethylene/air coflow jet diffusion flame at atmospheric pres-sure was conducted using a reduced mechanism and soot formation model. A 20-step mechanism was derived from the full mechanism using sensitivity analysis,reaction path analysis and quasi steady state(QSS) approximation. The model in premixed flame was validated and with computing savings in diffusion flame was applied by incor-porating into a CFD code. Simulations were performed to explore the effect of coflow air on flame structure and soot formation. Thermal radiation was calculated by a discrete-ordinates method,and soot formation was predicted by a simple two-equation soot model. Model results are in good agreement with those from experiment data and detailed mechanism at atmospheric conditions. The soot nucleation,growth,and oxidation by OH are all enhanced by decrease in coflow air velocity. The peak soot volume fraction region appears in the lower annular region be-tween the peak flame temperature and peak acetylene concentration locations,and the high soot oxidation rate due to the OH attack occurs in the middle annular region because of high temperature.展开更多
The district heating company ＂Rigas siltums＂ operates biomass fuelled boiler in Riga city. Three systems consisting ofbiomass boilers having a comparatively similar heat capacity and particle abatement units like mu...The district heating company ＂Rigas siltums＂ operates biomass fuelled boiler in Riga city. Three systems consisting ofbiomass boilers having a comparatively similar heat capacity and particle abatement units like multicyclons, electrostatic precipitators and flue gas condensers are compared. The main goal of the study is to evaluate the boiler plant as a system where solid particles are both emitted and caught. The results show that, the particulate matter can be efficiently trapped from flue gases by the particle abatement technologies, and the electrostatic precipitator with sufficiently large collection surfaces is able to provide appropriate flue gas treatment of the particulate matter in the biomass boilers also without pre-cleaning of the flue gas in multieyelons.展开更多
The objectives of this work are to study the primary chemical structure of soot aerosol derived from lump-coal combustion in different experimental conditions in fixed bed. A laboratory-scale movable fixed bed, water-...The objectives of this work are to study the primary chemical structure of soot aerosol derived from lump-coal combustion in different experimental conditions in fixed bed. A laboratory-scale movable fixed bed, water-cooled soot aerosol collection system, and electric reactor have been designed and used in the process. Three kinds of coals, sized at 3-5 ram, have been heated in the experiments. Fourier Transform Infrared Spectroscopy （FTlR） has been employed to test functional groups of soot aerosol samples. Infrared spectra from 400 to 4000 cm^ -1 and semiquantitative analysis have been employed. The results of experiments show that contents of hydrogen-bonded are increased, contents of unsaturated hydrocarbons are increased, and contents of aromatic hydrocarbons are decreased with temperature increase; contents of hydrogen-bonded and unsaturated hydrocarbons are increased first and decreased late, and contents of aromatic hydrocarbons are decreased with gases residence time extension; the contents of hydrogen bonded and unsaturated hydrocarbons derived from soot aerosol samples are higher than those from original coal samples in lower-volatile coals, and the contents of aromatic hydrocarbons derived from soot aerosol samples are lower than those from original coals; and contents of hydrogen-bonded are decreased, contents of unsaturated hydrocarbons are increased, and contents of aromatic hydrocarbons are decreased with a increase.展开更多
基金Supported by the National Natural Science Foundation of China（50806023 50721005 50806024） Program of Introducing Talents of Discipline to Universities of China（“111” Project B06019）
文摘A computational study of soot formation in ethylene/air coflow jet diffusion flame at atmospheric pres-sure was conducted using a reduced mechanism and soot formation model. A 20-step mechanism was derived from the full mechanism using sensitivity analysis,reaction path analysis and quasi steady state(QSS) approximation. The model in premixed flame was validated and with computing savings in diffusion flame was applied by incor-porating into a CFD code. Simulations were performed to explore the effect of coflow air on flame structure and soot formation. Thermal radiation was calculated by a discrete-ordinates method,and soot formation was predicted by a simple two-equation soot model. Model results are in good agreement with those from experiment data and detailed mechanism at atmospheric conditions. The soot nucleation,growth,and oxidation by OH are all enhanced by decrease in coflow air velocity. The peak soot volume fraction region appears in the lower annular region be-tween the peak flame temperature and peak acetylene concentration locations,and the high soot oxidation rate due to the OH attack occurs in the middle annular region because of high temperature.
文摘The district heating company ＂Rigas siltums＂ operates biomass fuelled boiler in Riga city. Three systems consisting ofbiomass boilers having a comparatively similar heat capacity and particle abatement units like multicyclons, electrostatic precipitators and flue gas condensers are compared. The main goal of the study is to evaluate the boiler plant as a system where solid particles are both emitted and caught. The results show that, the particulate matter can be efficiently trapped from flue gases by the particle abatement technologies, and the electrostatic precipitator with sufficiently large collection surfaces is able to provide appropriate flue gas treatment of the particulate matter in the biomass boilers also without pre-cleaning of the flue gas in multieyelons.
文摘The objectives of this work are to study the primary chemical structure of soot aerosol derived from lump-coal combustion in different experimental conditions in fixed bed. A laboratory-scale movable fixed bed, water-cooled soot aerosol collection system, and electric reactor have been designed and used in the process. Three kinds of coals, sized at 3-5 ram, have been heated in the experiments. Fourier Transform Infrared Spectroscopy （FTlR） has been employed to test functional groups of soot aerosol samples. Infrared spectra from 400 to 4000 cm^ -1 and semiquantitative analysis have been employed. The results of experiments show that contents of hydrogen-bonded are increased, contents of unsaturated hydrocarbons are increased, and contents of aromatic hydrocarbons are decreased with temperature increase; contents of hydrogen-bonded and unsaturated hydrocarbons are increased first and decreased late, and contents of aromatic hydrocarbons are decreased with gases residence time extension; the contents of hydrogen bonded and unsaturated hydrocarbons derived from soot aerosol samples are higher than those from original coal samples in lower-volatile coals, and the contents of aromatic hydrocarbons derived from soot aerosol samples are lower than those from original coals; and contents of hydrogen-bonded are decreased, contents of unsaturated hydrocarbons are increased, and contents of aromatic hydrocarbons are decreased with a increase.
