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Experimental studies of ash film fractions based on measurement of cenospheres geometry in pulverized coal combustion

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Frontiers in Energy 2021年第1期15卷 91-98页

作者： Siqi LIU Yanqing NIU Liping WEN Yang LIANG Bokang YAN Denghui WANG Shi'en HUI State Key Laboratory of Multiphase Flow in Power Engineering Department of Thermal EngineeringSchool of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

In pulverized coal particle combustion, part of the ash forms the ash film and exerts an inhibitory influence on combustion by impeding the diffusion of oxygen to the encapsulated char core, while part of the ash diffuses toward the char core. Despite the considerable ash effects on combustion, the fraction of ash film still remains unclear. However, the research of the properties of cenospheres can be an appropriate choice for the fraction determination, being aware that the formation of cenospheres is based on the model of coal particles with the visco-plastic ash film and a solid core. The fraction of ash film X is the ratio of the measuring mass of ash film and the total ash in coal particle. In this paper, the Huangling bituminous coal with different sizes was burnt in a drop-tube furnace at 1273, 1473, and 1673 K with air as oxidizer. A scanning electron microscope (SEM) and cross-section analysis have been used to study the geometry of the collected cenospheres and the effects of combustion parameters on the fraction of ash film. The results show that the ash film fraction increases with increasing temperature and carbon conversion ratio but decreases with larger sizes of coal particles. The high fraction of ash film provides a reasonable explanation for the extinction event at the late burnout stage. The varied values of ash film fractions under different conditions during the dynamic combustion process are necessary for further development of kinetic models.

关键词： ash film fraction cenospheres coal combustion fly ash

Numerical Simulation of NO_x Formation in coal combustion with Inlet Natural Gas Burning

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Chinese Journal of Chemical Engineering 2005年第3期13卷 318-323页

作者：张宇周力行魏小林盛宏至 Institute of MechanicsChinese Academy of Sciences Beijing 100080China The State Key Laboratory of Clean coal combustionTsinghua University Beijing 100084China

A full two-fluid model of reacting gas-particle flows and coal combustion is used to simulate coal combustion with and without inlet natural gas added in the inlet. The simulation results for the case without natural gas burning is in fair agreement with the experimental results reported in references. The simulation results of different natural gas adding positions indicate that the natural gas burning can form lean oxygen combustion enviroment at the combustor inlet region and the NOx concentration is reduced. The same result can be obtained from chemical equilibrium analysis.

关键词： coal combustion natural gas burning NOx formation numerical simulation

Advances in LES of Two-phase combustion(Ⅱ) LES of Complex Gas-Particle Flows and coal combustion

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Chinese Journal of Chemical Engineering 2012年第4期20卷 609-616页

作者：周力行胡瓅元 Department of Engineering Mechanics Tsinghua University School of Mechanical Engineering Shanghai Jiao Tong University

Large-eddy simulation(LES) is under its rapid development and is recognized as a possible second generation of CFD methods used in ***-eddy simulation of two-phase flows and combustion is particularly important for engineering *** investigators,including the present authors,give their review on LES of spray combustion in gas-turbine combustors and internal combustion ***,up to now only a few papers are related to the state-of-the-art on LES of gas-particle flows and *** this paper a review of the advances in LES of complex gas-particle flows and coal combustion is *** sub-grid scale(SGS) stress models and combustion models are described,some of the main results are summarized,and some research needs are discussed.

关键词： large-eddy simulation complex gas-particle flows coal combustion

Mercury in coal and its emission by coal combustion in the Northeast China

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Journal of Environmental Sciences 2000年第S1期12卷 22-23页

作者： WANG Qi\|chao, HU Xing\|da, MA Ru\|long (Changchun Institute of Geography, Chinese Academy of Sciences,Changchun 130021, China)

This paper reports on the mercury content distribution in coals produced in the Northeast of China, and the east of Inner Mongolia, and transmission of mercury from coals into the burned products. The arithmetic average value of mercury content in coals is 0.158 mg/kg, and the mercury content shows considerable positive correlation with ashes in coals. The mercury content in fly ash is increased as the particle diameter of fly ash decrease. After combustion, 23.1—26.9 percent of mercury in coals enters fly ash,and 56.3—69.7 percent of mercury escapes into atmosphere. We estimated that the amount of mercury in raw coals produced in the Northeast of China and the east Inner Mongolia was 30.9 tons in the whole year and the amount emitted into atmosphere was 20 30 tons in 1990.

关键词： mercury emission coal combustion Northeast of China

A review on nitrogen transformation and conversion during coal pyrolysis and combustion based on quantum chemical calculation and experimental study

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Chinese Journal of Chemical Engineering 2021年第7期34卷 107-123页

作者： Tingting Jiao Huiling Fan Shoujun Liu Song Yang Wenguang Du Pengzheng Shi Chao Yang Yeshuang Wang Ju Shangguan State Key Laboratory of Clean and Efficient coal Utilization Taiyuan University of TechnologyTaiyuan 030024China Shanxi Engineering Central of Civil Clean Fuel Taiyuan University of TechnologyTaiyuan 030024China College of Chemistry and Chemical Engineering Taiyuan University of TechnologyTaiyuan 030000China Taiyuan Green Coke Energy Co. Ltd.Taiyuan 030006China

The emission of NOx during coal combustion contributes to the formation of acid rain and photochemical smog,which would seriously affect the quality of atmospheric ***,the decrease of NOx is of great importance for improving the efficient utilization of *** present review comprehensively summarized the influence factors and mechanisms of migration and transformation of nitrogen during the coal pyrolysis and combustion based on experimental study and quantum chemical ***,in the process of pyrolysis:the occurrence state and transformation of nitrogen were *** influence of temperature,atmosphere,heating rate and catalyst on formation of NOx precursor and nitrogen migration path at the molecular level were summarized;Secondly,during the process of combustion:the influence of temperature,ambient oxygen concentration,physical structure of coal char,catalyst on heterogeneous oxidation of char(N)were summarized;The effects of char surface properties,catalyst and ambient atmosphere on heterogeneous reduction of NOx were also *** on the quantum chemical calculation,the reaction path of heterogeneous oxidation of char-N and heterogeneous reduction of NOx were described in *** studies focus more on the generation of HCN and NH3,but in order to reduce the pollution of NOx from the source,it is necessary to further improve the process conditions and the optimal formula of producing more N2 during pyrolysis,as well as clarify the path of the generation of *** study and quantum chemistry calculation should be combined to complete the research of directional nitrogen reduction during pyrolysis and denitration during combustion.

关键词： coal combustion Pyrolysis Environment Nitrogen oxides Quantum chemical calculation

Accounting Research about Soot Emission Caused by coal combustion in Chongqing

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Meteorological and Environmental Research 2014年第7期5卷 34-36,40页

作者： Mao Huiqian Cheng Yan Li Hancheng Huang Jiang Mou Xinli School of Finance and Economics Chongqing Three Gorges University Lianhe Chemical Technology Co. Ltd. Key Laboratory of Water Environment Evolution and Pollution Control in Three Gorges Reservoir( Chongqing Three Gorges University)

As rapid development of economy and acceleration of urbanization process, air pollution problem in Chongqing was more and more prominent. By referring to statistical yearbook and investigating energy usage and economy activity levels of various industrial sectors of Chongqing, basic data （activity level, energy production and consumption situation） of various economic sectors of Chongqing during 2007 -2012 were ob- tained. Using emission coefficient method, soot emission inventory in Chongqing during 2007 -2012 was established. Meanwhile, input-output model containing environmental factor was established to study relationship between economy development and environmental protection and number relationship between economy development and pollutant emission. According to the results, countermeasures of emission reduction in Chongqing were put forward.

关键词： coal combustion Soot pollution Input-output model Chongqing China

Effect of unburned carbon content in fly ash on the retention of 12 elements out of coal-combustion flue gas

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Journal of Environmental Sciences 2012年第9期24卷 1624-1629页

作者： Lucie Bartonov Bohumír ech Lucie Ruppenthalov Vendula Majvelderov Dagmar Juchelkov Zdeněk Klika Faculty of Metallurgy and Material Engineering VSB-Technical University of OstravaTr.17.listopadu 15708 33 Ostrava-PorubaCzech Republic

The aim of this study was to evaluate whether unburned carbon particles present in fly ash can help in the retention of S, Cl, Br, As, Se, Cu, Ni, Zn, Ga, Ge, Rb, and Pb out of flue gas during the coal combustion at fluidised-bed power station where the coal was combusted along with limestone. The competitive influence of 10%-25% CaO in fly ashes on the distribution of studied elements was studied as well to be clear which factor governs behaviour of studied elements. Except of S （with significant association with CaO） and Rb and Pb （with major affinity to A1203） the statistically significant and positive correlation coefficients were calculated for the relations between unburned carbon content and Br （0.959）, Cl （0.957）, Cu （0.916）, Se （0.898）, Ni （0.866）, As （0.861）, Zn （0.742）, Ge （0.717）, and Ga （0.588） content. The results suggest that the unburned carbon is promising material in terms of flue gas cleaning even if contained in highly calcareous fly ashes.

关键词： unburned carbon coal combustion fluidised bed trace elements emissions retention

Effects of CeO_2 on the XPS valence band spectra of coal under the combustion initialization stage at 400℃

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International Journal of Minerals,Metallurgy and Materials 2013年第4期20卷 338-344页

作者： Cheng-lin Qi Jian-liang Zhang Chao Ma Gen-sheng Feng Zhong-ping Song State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Shougang Research Institute of Technology

In order to get the catalytic mechanism of CeO2 on graphite and coal at 400℃, the morphologies of coal, graphite, and CeO2 before and after combustion were analyzed through X-ray photoelectron spectroscopy （XPS）. It is found that the particle size of coal is mostly between 11.727 and 64.79 μm, while the particle size of CeO2 is between 1.937 and 11.79 μm. The agglomeration of coal and CeO2 can be seen by scanning electron microscopy （SEM） after reaction. XPS results show that with the addition of CeO2, the intensity of binding energy gets stronger, but there is no energy peak transition. Comparing the character of coal with and without the addition of CeO2, it can be seen that the C C bond fractures first at 400℃, while the C-H energy-band takes electrons at the same time to be far away from the Fermi level, and the O 2s, O 2p, and C sp hybrid orbitals are all excited. Adding CeO2 can enhance the activity of the whole coal. In addition, through XPS analysis, combined with the oxygen transfer theory and the electron transfer theory, the catalytic mechanism of CeO2 for pulverized coal combustion could be obtained.

关键词： coal combustion cerium oxide valence bands catalysis binding energy X-ray photoelectron spectroscopy pulverized fuel

Comparative cytotoxicity of fine particles from different coal combustion on cultured vascular endothelia cells

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Comparative cytotoxicity of fine particles from different co...