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Role of Air Staging in a Batch-Type Fixed Bed biomass Combustor under Constant Primary Air

Journal of Thermal Science 2024年第1期33卷 284-299页

作者： Awais JUNEJO Yasir M.AL-ABDELI Jacobo PORTEIRO School of Engineering Edith Cowan UniversityJoondalupWA 6027Australia CINTECX Universidade de Vigo Grupo de Tecnoloxia Enerxetica(GTE)36310 VigoEspana

Staged combustion of biomass is the most suitable thermo-chemical conversion for achieving lower gaseous emissions and higher fuel conversion rates.In a staged fixed bed combustion of biomass,combustion air is supplied in two stages.In the first stage,primary air is provided below the fuel,whereas in the later stage,secondary air is supplied in the freeboard region.The available literature on the effects of air staging(secondary air location) at a constant primary air flow rate on combustion characteristics in a batch-type fixed bed combustor is limited and hence warrants further investigations.This study resolves the effect of air staging,by varying the location of secondary air in the freeboard at five secondary to total air ratios in a batch-type fixed bed combustor.Results are reported for the effects of these controlled parameters on fuel conversion rate,overall gaseous emissions(CO_(2),CO and NO_x) and temperature distributions.The fuel used throughout was densified hardwood pellets.Results show that a primary freeboard length(distance between fuel bed top and secondary air injection) of200 mm has higher fuel conversion rates and temperatures as well as lower CO emissions,at a secondary to total air ratio of 0.75 as compared to primary freeboard length of 300 mm.However,NO_x emissions were found to be lower for a primary freeboard length of 300 mm as compared to 200 mm.An increase in secondary to total air ratio from 0.33 to 0.75 resulted in higher freeboard temperatures and lower CO as well as NO_x emissions.The outcomes of this study will be helpful in the effective design of commercial scale biomass combustors for more efficient and environmentally friendly combustion.

关键词： fixed bed combustor biomass combustion air staging freeboard temperature burning rate gaseous emissions

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Reactivity improvement of ilmenite by calcium nitrate melt infiltration for Chemical Looping combustion of biomass

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Carbon Resources Conversion 2019年第1期2卷 51-58页

作者： Martin Keller Hikaru Oka Junichiro Otomo Graduate School of Frontier Sciences The University of Tokyo5-1-5 KashiwanohaKashiwa-shiChiba 277-8563Japan

Chemical Looping combustion is a novel process that generates sequestration-ready CO_(2) from the combustion of woody biomass without requiring a gas separation step and without diluting the CO_(2) with N_(2) from air.This is achieved by oxidizing the fuel with lattice oxygen of a metal oxide oxygen carrier.When using cheap and abundant ilmenite ore(FeTiO3)as the oxygen carrier,the rather low reactivity towards volatiles released from the biomass upon devolatilization,as well as detrimental structural changes due to a segregation of Fe and Ti in the material,are of concern.These issues can be addressed by modifying ilmenite with Ca via melt infiltration.In this work,we demonstrate that this modification results in a good distribution of Ca throughout the ilmenite particles that a)prevents detrimental Fe/Ti segregation,b)improves the mechanical stability of the particle compared to materials prepared by solution impregnation and c)improves the reactivity of this material towards hydrogen and wet methane.Moreover,fixed bed experiments showed that the Ca modification not only resulted in increased methane conversion,but also in an increased degree of oxidation of gaseous intermediates CO and H2.We thus conclude that the performance of ilmenite in Chemical Looping processes can be significantly enhanced by Ca modification of ilmenite either prior to use or in-situ during operation of this bed material with Ca-rich fuels such as woody biomass.

关键词： Carbon dioxide removal Chemical Looping combustion Ilmenite Melt infiltration BECCS biomass combustion

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biomass briquette fuel,boiler types and pollutant emissions of industrial biomass boiler:A review

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颗粒学报:英文版 2023年第6期77卷 79-90页

作者： Hong Huang Yan Gao Hunan Chen Yiying Wu Jiayi Wang Chenglong Yu Jianlong Li Changwei Zou School of Resources and Environment Nanchang UniversityNanchang330031China Key Laboratory of Poyang Lake Environment and Resource Utilization Ministry of EducationNanchang330031China School of Land Resources and Environment Jiangxi Agricultural UniversityNanchang330045China

biomass is considered a renewable and cleaner energy source alternative to fossil fuels.In recent years,industrial biomass boilers have been rapidly developed and widely used in the industrial field.This work makes a review on the fuel types used in industrial biomass boilers,the fuel characteristics and the characteristics of air pollutants emitted from the combustion of industrial biomass boilers and other contents in different studies.However,the existing research still has many deficiencies.In the future,further research on biomass fuel,industrial biomass boiler combustion process and the pollutants emitted by industrial biomass boiler combustion,especially the carbonaceous aerosol emitted by in-dustrial biomass boiler and carbonaceous aerosol optical properties still need to be made.At the same time,the potential harm of carbonaceous aerosols emitted from industrial biomass boiler sources to human health and climate change needs to be studied in depth.This review provides a scientific basis for the accurate evaluation of industrial biomass boilers and the effective prevention and control of various pollutants of industrial biomass boilers.

关键词： Industrial biomass boilers biomass briquette fuel Emissions of air pollutants biomass combustion

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Physicochemical characterization of forest and sugarcane leaf combustion’s particulate matters using electron microscopy,EDS,XRD and TGA

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Journal of Environmental Sciences 2021年第1期33卷 296-310页

作者： Hay Mon Oo Preechar Karin Nuwong Chollacoop Katsunori Hanamura Faculty of Engineering King Mongkut's Institute of Technology LadkrabangBangkok 10520Thailand National Metal and Materials Technology Center National Science and Technology Development AgencyPathum Thani 12120Thailand School of Engineering Tokyo Institute of TechnologyTokyo 152-8552Japan

Physical characteristics and quantitative elemental composition of PM and residual ash produced from sugarcane leaves(SCL)combustion were investigated using TEM-EDS compared with forest leaves(FRL).SEM-EDS was used to analyze the microstructure and chemical composition of biomass raw leaves and PM.XRD analysis was also performed to investigate the characterization of the crystalline nanostructure,structure of PM,and residual ash compared to the TEM image processing method.The oxidation kinetics of biomass raw materials,PM,and residual ash were investigated by TGA.The morphology of fine and ultrafine agglomerate structure of SCL soot and residual ash are not significantly different from the FRL soot and residual ash.The average diameter sizes of single primary nanoparticles of SCL and FRL soot are approximately 37 nm and 35 nm,while the sizes of residual ash are about 18 nm and 22 nm,respectively.The single primary nanoparticles of soot are mainly composed of curve line crystallites of carbon fringes,while residual ash is composed of straightline lattice fringes.The average fringe lengths of SCL and FRL soot are about 1.25 nm and 1.04 nm from the outer shell and 0.89 nm and 0.74 nm from the inner core.The interlayer spacing of curve line carbon fringes of SCL and FRL soot is approximately 0.359 nm and 0.362 nm by the TEM image analysis and it was matched with XRD analysis.The biomass PMs are mainly composed of soot,Si,Ca,and K compounds:SiO_(2),CaCO3,and KCl.

关键词： biomass combustion Particulate matter Soot Ashes TEM XRD TGA

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Physicochemical and toxicological characteristics of nanoparticles in aerosols in southern Thailand during recent haze episodes in lower southeast Asia

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Journal of Environmental Sciences 2020年第8期32卷 72-80页

作者： Jiraporn Chomanee Kunchira Thongboon Surajit Tekasakul Masami Furuuchi Racha Dejchanchaiwong Perapong Tekasakul Department of Basic Science and Mathematics Faculty of ScienceThaksin UniversitySongkhla90000Thailand Department of Environmental Engineering Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90112Thailand Department of Chemistry Faculty of SciencePrince of Songkla UniversityHat YaiSongkhla 90112Thailand Graduate School of Natural Science and Technology Kanazawa UniversityKanazawaIshikawa920-1192Japan Department of Chemical Engineering Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90112Thailand Department of Mechanical Engineering Faculty of EngineeringPrince of Songkla UniversityHat YaiSongkhla 90112Thailand Air Pollution and Health Effect Research Center Prince of Songkla UniversityHat YaiSongkhla 90112Thailand

Transboundary haze from biomass burning is one of the most important air pollutions in Southeast Asia.The most recent serious haze episode occurred in 2015.Southern Thailand was affected by the haze during September to October when the particulate matter concentration hit a record high.We investigated physical and chemical characteristics of aerosols,including concentration and aerosol size distribution down to sub-micron sizes during haze episodes in 2013 and 2015 and,for reference,an insignificant haze period in 2017.The highest total suspended particulates and PM 10 levels in Hat Yai city were 340.1 and 322.5μg/m^3.The mass fractions were nanoparticles(<100 nm)3.1%-14.8%and fine particles(<1μm)54.6%-59.1%.Polycyclic aromatic hydrocarbon size distributions in haze periods peaked at 0.75μm and the concentrations are 2-30 times higher than the normal period.High molecular weight(4-6 ring)PAHs during the haze episode contribute to about 56.7%-88.0%for nanoparticles.The average values of benzo(a)pyrene toxic equivalency quotient were 3.34±2.54ng/m^3 in the 2015 haze period but only 0.89±0.17 ng/m^3 in 2017.It is clear that particles smaller than 1μm,were highly toxic.Nanoparticles contributed 19.4%-26.0%of total BaP-TEQ,whereas the mass fraction is 13.1%-14.8%.Thus the nanoparticles were more carcinogenic and can cause greater health effect than larger particles.The fraction of BaP-TEQ for nanoparticles during 2017 non-haze period was nearly the same,while the mass fraction was lower.This indicates that nanoparticles are the significant source of carcinogenic aerosols both during haze and non-haze periods.

关键词： Polycyclic aromatic hydrocarbons biomass combustion Air pollution Carcinogenicity Aerosol size distribution

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Compositional and structural study of ash deposits spatially distributed in superheaters of a large biomass-fired CFB boiler

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Frontiers in Energy 2021年第2期15卷 449-459页

作者： Yishu XU Xiaowei LIU Jiuxin QI Tianpeng ZHANG Minghou XU Fangfang FEI Dingqing LI State Key Laboratory of Coal combustion Huazhong University of Science and TechnologyWuhan 430074China School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan 430074China Guangdong Yudean Zhanjiang biomass Power Plant Zhanjiang 524300China

Recognizing the nature and formation progress of the ash deposits is essential to resolve the deposition problem hindering the wide application of large-scale biomass-fired boilers.Therefore,the ash deposits in the superheaters of a 220 t/h biomass-fired CFB boiler were studied,including the platen(PS),the high-temperature(HTS),the upper and the lower low-temperature superheaters(LTS).The results showed that the deposits in the PSs and HTSs were thin(several millimeters)and compact,consisting of a yellow outer layer and snow-white inner layer near the tube surface.The deposits in the upper LTS appeared to be toughly sintered ceramic,while those in the lower LTS were composed of dispersive coarse ash particles with an unsintered surface.Detailed characterization of the cross-section and the initial layers in the deposits revealed that the dominating compositions in both the PSs and the HTSs were Cl and K(approximately 70%)in the form of KCl.Interestingly,the cross-section of the deposition in the upper LTS exhibited a unique lamellar structure with a major composition of Ca and S.The contents of Ca and Si increased from approximately 10%to approximately 60%in the deposits from the high temperature surfaces to the low temperature ones.It was concluded that the vaporized mineral matter such as KCl played the most important role in the deposition progress in the PS and the HTS.In addition,although the condensation of KCl in the LTSs also happened,the deposition of ash particles played a more important role.

关键词： ash deposition biomass combustion circulating fluidized bed initial layer structure analysis

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Characteristics and source regions of the biomass burning tracer levoglucosan in spring at four background sites in South China

Characteristics and source regions of the biomass burning tr...

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第七届亚洲气溶胶会议

作者： Chuen-Yu Chan Guenter Engling School of Environmental Science and Engineering Sun Yat-sen University National Tsing Hua University Department of Biomedical Engineering and Environmental Science

An intensive field study was carried out to identify the influence of biomass burning and the associated source regions during spring in South China. Ambient concentrations of the biomass burning tracer levoglucosan were determined at four background stations: Jianfengling （JFL） on Hainan Island, Hok Tsui （HT） in Hong Kong, Lin’an （LA） in Zhejiang province and Tengchong （TC） in Yunnan province. Exceptionally high levels of levoglucosan were found in TC, with an average concentration of 1070 ng m-3, while those at the other sites were lower by two orders of magnitude. Elevated levoglucosan levels were further investigated with the help of fire hot spot counts and aerosol index derived from satellite data, as well as backward trajectories. Southwest Asia, the Philippines and the Southeast China coast area were identified as source regions of biomass burning aerosol transported to South China. Using a simplified receptor-based model, the contribution of biomass burning to OC was estimated to be as high as 73% at the TC site due to strong influence by biomass burning activities in Southwest Asia. Moreover, the widespread biomass burning smoke plumes derived from the Philippines were reported for the first time in this study, accounting for 21% and 4.5% of OC in PM2.5 at JFL and HT, respectively.

关键词： biomass combustion Levoglucosan Source apportionment Long-range transport

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