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Effect of CaO on retention of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn,W and Pb in bottom ashes from fluidized-bed coal combustion power station

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Journal of Environmental Sciences 2014年第7期26卷 1429-1436页

作者： Lucie Bartonova Zdenek Klika Energy Units for Utilization of Non-Traditional Energy Sources Centre V?B-Technical University of Ostrava 708 33 Ostrava-Poruba Czech Republic Regional Material and Technology Research Centre VSB-Technical University of Ostrava 708 33 Ostrava-Poruba Czech Republic

This work was conducted to evaluate whether Ca-bearing additives used during coal combustion can also help with the retention of some other elements. This work was focused on the evaluation of bottom ashes collected during four full-scale combustion tests at an operating thermal fluidized-bed power station. Bottom ashes were preferred to fly ashes for the study to avoid interference from condensation processes usually occurring in the post-combustion zone. This work focused on the behaviors of S, Cl, Br, As, Mn, V, Cr, Ni, Cu,Zn, W, and Pb. Strong positive correlations with CaO content in bottom ashes were observed（for all four combustion tests） for S, As, Cl and Br（R = 0.917-0.999）. Strong inverse proportionality was calculated between the contents of Pb, Zn, Ni, Cr and Mn and CaO, so these elements showed association to materials other than Ca-bearing compounds（e.g., to aluminosilicates, organic matter, etc.）. Somewhat unclear behaviors were observed for W, Cu, and V. Their correlation coefficients were evaluated as statistically ＂not significant＂, i.e., these elements were not thought to be significantly associated with CaO. It was also discovered that major enrichment of CaO in the finest bottom ash fractions could be advantageously used for simple separation of elements strongly associated with these fractions, mainly S and As, but also Cl or Br. Removal of5% of the finest ash particles brings about a decrease in As concentration down to 77%-80% of its original bulk ash content, which can be conveniently used e.g., when high As content complicates further ash utilization.

关键词： coal combustion Arsenic Chlorine Bromine CaO Retention Fluidized-bed Trace elements

Role of iron-based catalysts in reducing NO_(x) emissions from coal combustion

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Chinese Journal of Chemical Engineering 2023年第7期59卷 1-8页

作者： Yuehua Liu Lili Chen Shoujun Liu Song Yang Ju Shangguan State Key Laboratory of Clean and Efficient coal Utilization Taiyuan University of TechnologyTaiyuan 030024China Shanxi Engineering Center of Civil Clean Fuel Taiyuan University of TechnologyTaiyuan 030024China College of Chemical Engineering and Technology Taiyuan University of TechnologyTaiyuan 030024China

Nitrogen oxide(NO_(x))pollutants emitted from coal combustion are attracting growing public *** the traditional technologies of reducing NO_(x) were mainly focused on terminal treatment,and the research on source treatment is *** paper proposes a new coal combustion strategy that significantly reduces NO_(x) emissions during coal *** strategy has two important advantages in reducing NO_(x) ***,by introducing iron-based catalyst at the source,which will catalyze the conversion of coke nitrogen to volatile nitrogen during the pyrolysis process,thereby greatly reducing the coke nitrogen *** second is de-NO_(x) process by a redox reaction between NO_(x) and reducing agents(coke,HCN,NH_(3),etc.)that occurred during coke *** to direct combustion of coal,coke prepared by adding iron-based catalyst has 46.1% reduction in NO_(x) *** determine the effect of iron-based additives on de-NO_(x) performance,demineralized coal(de-coal)was prepared to eliminate the effect of iron-based minerals in coal *** effects of iron compounds,additive dosages,and combustion temperatures on de-NO_(x) efficiency are systematically *** results revealed that the NO_(x) emission of the coke generated by pyrolysis of de-coal loaded with 3%(mass)Fe_(2)O_(3) decreases to 27.3% at combustion temperature of 900℃.Two main reasons for lower NO_(x) emissions were deduced:(1)During the catalytic coal pyrolysis stage,the nitrogen content in the coke decreases with the release of volatile nitrogen.(2)Part of the NO_(x) emitted during the coke combustion was converted into N_(2) for the catalytic effect of the Fe-based *** is of great practical value and scientific significance to the comprehensive treatment and the clean utilization process of coal.

关键词： NO_(x) coal combustion coal pyrolysis Fe2O3 catalyst

Restraining NO_x Formation during coal combustion in Packed Bed

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International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 70-74页

作者： Shengli Wu Chunbao Xu Qiushuang Shou Daqiang Cang Metallurgy School, UST Beijing, Beijing 100083, China Metallurgy School UST Beijing Beijing 100083 China

The effects of various combustion conditions (i. e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NO_x during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NO_x, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O_2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NO_x. In order to investigate the effect of metallic oxide layers on restraining NO_x formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe_2O_3, Ni_2O_3 and mixed oxides Fe-Ni-O_x were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NO_x emission during coal combustion.

关键词： coal combustion NO_x formation restraining metallic oxide

Significant coal combustion contribution to water-soluble brown carbon during winter in Xingtai, China: Optical properties and sources

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Journal of Environmental Sciences 2023年第2期124卷 892-900页

作者： Dapeng Li Can Wu Si Zhang Yali Lei Shaojun Lv Wei Du Shijie Liu Fan Zhang Xiaodi Liu Lang Liu Jingjing Meng Yuesi Wang Jian Gao Gehui Wang Key Lab of Geographic Information Science of the Ministry of Education School of Geographic SciencesEast China Normal UniversityShanghai 200241China School of Public Policy and Administration Northwestern Polytechnical UniversityXi’an 710061China School of Environment and Planning Liaocheng UniversityLiaocheng 252000China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100080China Chinese Research Academy of Environmental Sciences Beijing 100012China Institute of Eco-Chongming Chenjia ZhenChongmingShanghai 202162China

To understand the characteristics of atmospheric brown carbon(BrC),daily PM2.5 samples in Xingtai,a small city in North China Plain(NCP),during the four seasons of 2018-2019,were collected and analyzed for optical properties and chemical *** light absorption at 365 nm(abs λ=365 nm)displayed a strong seasonal variation with the highest value in winter(29.0±14.3 M/m),which was 3.2∼5.4-fold of that in other seasons.A strong correlation of abs λ=365 nm with benzo(b)fluoranthene(BbF)was only observed in winter,indicating that coal combustion was the major source for BrC in the season due to the enhanced domestic *** mass absorbing efficiency of BrC also exhibited a similar seasonal pattern,and was found to correlate linearly with the aerosol pH,suggesting a positive effect of aerosol acidity on the optical properties and formation of BrC in the *** matrix factorization(PMF)analysis further showed that on a yearly basis the major source for BrC was biomass burning,which accounted for 34% of the total BrC,followed by secondary formation(26.7%),coal combustion(21.3%)and fugitive dust(18%).However,the contribution from coal combustionwas remarkably enhanced in winter,accounting for∼40%of the *** work revealed that more efforts of“shifting coal to clean energy”are necessary in rural areas and small cities in NCP in order to further mitigate PM2.5 pollution in China.

关键词： Brown carbon coal combustion Haze Organic tracers,PMF

Possibility of Reducing Formations of NO_x and SO_2 Simultaneously during coal combustion

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International Journal of Minerals,Metallurgy and Materials 2000年第3期14卷 165-169页

作者： Chunbao Xu, Shengli Wu, Daqiang Cang ( Metallurgy School, University of Science and Technology Beijing, Beijing 100083, China Institute for Chemical Reaction Science, Tohoku University, Japan) Metallurgy School University of Science and Technology Beijing Beijing 100083 China Institute for Chemical Reaction Science Tohoku University Japan

Comparing with other NO_x and SO_2 control technologies, in-bed reducing NO_x and SO_2 simultaneously during coal combustion may lower the investment and operation cost. However, there are several possible contradictions between the reduction of NO_x and the capture of SO2 during combustion: 1) CO rich atmosphere is favorable for the reduction of NO_x, whereas O_2 rich favorable for the capture of SO_2; 2) higher preheating temperature of coal is favorable for reducing NO_x, but unfavorable for reducing SO_2; 3) sulphation of some minerals may deactivate their catalytic effect on the reduction of NO_x. The attempts to eliminate such contradictions by coating coal granules with thin layer of monometallic oxides and mixed oxides were proposed. Ni_2O_3 and Fe_2O_3 showed high activity on NOx reduction and CaO and Cr_2O_3 showed good effect on sulfur capture. The mixed metallic oxides, e.g., Fe_2O_3NiO, etc., showed effective for both NO_x reduction and SO_2 retention. It is possible to in-bed reduce NO_x and SO_2 simultaneously if the adhering materials are properly chosen to be difunctional materials of both active catalysts for NO_x reduction reactions and better sorbents for SO_2 retention.

关键词： coal combustion purification of NO and SO catalyst sorbent

Investigation on Pulverized coal combustion Behavior by Non-Isothermic Integral Thermogravimetry Method

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Journal of Iron and Steel Research International 2011年第8期18卷 1-8页

作者： QI Cheng-lin ZHANG Jian-liang LIN Xiang-hai LIU Qin-yuan WANG Xiao-liu School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

The combustion process of pulverized coal was investigated by non-isothermic integral thermogravimetry. The thermogravimetry curves were fitted by the Coats-Redferm approximation function, and kinetic parameters and characteristic temperatures were obtained. The optimal mixing ratio and particle size can be ascertained. The characteristic temperature of pulverized coal can be obtained from the thermogravimetry curve, and the combustion of coal can be divided into homogeneous and heterogeneous combustion according to the differential thermal analysis curve. The activation energy of a single type of coal ranking from low to high is as follows： bituminous coal, meager-lean coal, and anthracite. In the first mixing method, with more low-price meager-lean coal B replacing high price anthracite A, the activation energy slightly decreases; with more bituminous coal replacing meager-lean coal, total tendency makes a declining of activation. In the later mixing method, with an increase in particle size, a declining activation energy can be seen in total tendency.

关键词： pulverized coal combustion themogravimetry kinetics mixed-coal granularity coal combustion

The transformation and concentration of environmental hazardous trace elements during coal combustion

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Journal of coal Science & Engineering(China) 2010年第1期16卷 74-77页

作者： YAO Duo-xi ZHI Xia-chen Department of Natural Resourcers and Environmental Engineering Anhui University of Science and Technology Huainan 232001 China School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China

Studied the content and distribution of 18 environmental hazardous trace elementsin the lignite, fatty coal, anthracite and its burnt products by combustion simulatingexpriment in the one-dismensinal *** transformations and concentration of 18 traceelements during different coal combustion were *** results show that there aresome content distribution of 18 hazardous trace elements in every burnt product, but thelaw of concentration and dispersion of every trace element during different coal combustionis very *** results indicate that the transformation and concentrationof trace elements during coal combustion are related to the element contents and occur-rencesof trace elements in raw coal, but are also affected by some man-made factorssuch as the combustion method of boiler, combustion temperature and atmosphere, thetype of precipitators and so on.

关键词： environmental hazardous trace elements transformation and concentration coal combustion

Experimental research on combustion fluorine retention using calcium-based sorbets during coal combustion(Ⅱ)

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Journal of coal Science & Engineering(China) 2008年第2期14卷 667-671页

作者：齐庆杰马喜焱刘建忠吴宪周俊虎岑可法 College of Resource and Environment Engineering Liaoning Technical UniversityFuxin 123000China College of Mechanical and Energy Engineering Zhejiang UniversityHangzhou 310027China

During the fixed bed tube furnace combustion experimental study,stimulated the calcium-based sorbent grain size and microstructured influencing factors to explain the fluorine retention effect influence law,and expounded the combustion fluorine retention agent developing principle,and probed into the high-temperature fluorine retention agent technical *** results show that the calcium-based sorbent particle grain size and pore structure also have the bigger influence on the combustion fluorine retention ef- fect,and reducing the calcium-based sorbent particle grain size and improving the calcium sorbent structure characteristics at very high temperature to enhance the fluorine retention effect is the important approach to the fluorine retention agent development.

关键词： coal combustion calcium-based fluorine retention agent pore structure grain size

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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