• Research progress on the resource utilization of multi-source biomass thermo-chemical conversion for carbon peaking and carbon neutrality

    LU Qiang;XIE Wenluan;HU Bin;LIU Ji;ZHANG Zhenxi;LI Kai;National Engineering Research Center of New Energy Power Generation,North China Electric Power University;

    Biomass is the only renewable carbon resource on earth with significant advantages of wide sources and abundant reserves. Diverse high-value fuels, chemicals, and carbon-based materials can be obtained through advanced biomass thermo-chemical conversion methods, thereby partially replacing fossil resources, which has an important strategic position and development prospects in the field of new energy. Currently, the energy utilization technologies of biomass have made significant progress in China. However, with the rapid advancements of society and technology, the scope of biomass is no longer limited to traditional agricultural and forestry waste, but covers multiple organic wastes from agricultural and forestry sources, industrial sources, and domestic sources. The high selectivity and large-scale conversion of biomass is seriously hindered due to the complex component structure and differentiated thermal decomposition characteristics, and there are still many challenges to achieving its high-value resource utilization. The development of biomass thermo-chemical conversion was discussed. Based on the fundamental structures and thermal decomposition characteristics of multi-source biomass components, the latest research achievements and development trends of various cutting-edge resource utilization technologies, including selective pyrolysis for producing high-value products, pyrolysis reforming for hydrogen production, and novel gasification, etc., were compared and analyzed, in response to the problems of low quality and poor selectivity of thermal conversion products. To promote the further development of multi-source biomass thermo-chemical conversion technology in the carbon peaking and carbon neutrality era, the following aspects still need to be focused on. Firstly, large-scale utilization is an inevitable trend for future development, propelled by the significant promotion of efficient catalytic techniques and reaction equipment. The directional enrichment of target products can be achieved by breaking through the efficiency and recycling constraints of catalysts, reducing catalytic operating costs, strengthening reactor innovation, and optimizing heat transfer and anti-coking performance. Coupled with efficient strategies for raw material collection, storage, and transportation, the economic feasibility of industrial large-scale biomass thermo-chemical conversion will be enhanced. Secondly, the full-component conversion is the key to achieving high-value utilization of biomass. Through in-depth investigation on the decomposition and synergistic conversion mechanisms of various biomass characteristic components, it is necessary to develop efficient poly-generation technologies that combine multiple pretreatments, directional thermo-chemical conversion, and precise separation and condensation of three-phase products. Biomass raw materials are transformed into bio-oil rich in high-value chemicals, high-quality combustible gas, and high-performance carbon materials, thereby achieving comprehensive poly-generation of different products and effectively improving the output ratio of resources. Finally, multi-energy complementarity represents a significant development direction for the future. By efficiently integrating biomass with other clean energy sources and electricity, and fully utilizing the long-term chemical energy storage characteristics of biomass thermal decomposition products, a flexible multi-energy complementary supply system will be established, thereby achieving the multi-dimensional development and the overall economic efficiency of the new energy industry.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 697K]

  • Hydro-upgrading of crude algal bio-oil: Influence of external hydrogen sources

    WANG Zhicong;XIE Longfei;DUAN Peigao;School of Chemical Engineering and Technology,Xi′an Jiaotong University;Ecostar (Qingdao) Renewable Resources Co.,Ltd.;

    Catalytic hydrogenation is an effective way to improve the quality of crude algal bio-oil, in which hydrogen source is the key factor. The hydrogen production of five kinds of conventional metals(iron, aluminum, tin, zinc, magnesium) under supercritical water was investigated, and the hydrogen production of aluminum was the largest under the same mass. Then, using Ru/C as catalyst, the upgrading effect of four different hydrogen sources(hydrogen produced from hydrothermal gasification of microalgae hydrothermal liquefaction aqueous phase-M-HTL-H_2, hydrogen produced from hydrothermal gasification of Chlorella M-SCW-H_2, hydrogen produced from the reaction of Al and high temperature water-Al-H_2, and laboratory elemental hydrogen-L-H_2) on microalgae crude bio-oil in tetrahydronaphthalene medium was studied at 400 ℃ and 2 h. The results show that, regardless of the hydrogen source, the upgraded bio-oil yield of the refined products is the highest, and the upgraded oil yield from L-H_2 is the highest(87.6%), while the upgraded bio-oil yield from M-SCW-H_2 is the lowest(70.4%). The four hydrogen sources also show different hydrogenation improvement effects on crude bio-oil, among which the deoxidation effect of Al-H_2 on bio-oil is the highest(93.03%), and the calorific value of upgraded bio-oil is also the highest(43.05 MJ/kg). The nitrogen removal effect of M-SCW-H_2 is the best(86.11%). The desulfuration effect of the four hydrogen sources on bio-oil is more than 90%. The hydrogen source also has a great influence on the composition of the upgraded bio-oil. The content of aromatic hydrocarbon and unsaturated hydrocarbon in the upgraded bio-oil obtained from L-H_2 is the highest. The content of saturated hydrocarbon is the highest and the content of aromatic hydrocarbon is the lowest in the upgraded bio-oil obtained from M-HTL-H_2. The results show that hydrorefining of crude bio-oil with different external hydrogenation sources can obtain different bio-oil quality improvement effects, and if these different hydrogen sources are combined, a better improvement in bio-oil quality can be obtained.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 529K]

  • Research status and prospects of thermal conversion clean utilization technology for organic solid waste under the carbon-neutral vision

    YANG Tianhua;TONG Yao;ZHAI Yingmei;CUI Shuang;MA Ying;School of Energy and Environment,Shenyang Aerospace University;

    With the escalation of worldwide climate change and the pressing issues surrounding energy and the environment, achieving carbon neutrality has emerged as a crucial objective for nations striving for sustainable development. Intensifying research efforts have centered on the resource-based clean utilization technology of organic solid waste, recognized as a current focal point in research. Through the application of heat treatment conversion technology, it is possible to achieve efficient conversion and comprehensive utilization of organic solid waste, making significant contributions to the establishment of a carbon-neutral society. In this context, this article reviews the research progress of thermochemical conversion of organic solid waste, including the utilization of agricultural and forestry biomass for energy, municipal sludge treatment and disposal, as well as the clean utilization technology for municipal solid waste and summarized the domestic and foreign research progress and application status of combustion, pyrolysis, gasification, and hydrothermal thermochemical conversion technology. The technologies of biomass and municipal solid waste incineration for power generation, integrated pyrolysis gasification for multiple products, co-incineration, and pyrolysis carbonization of sludge were mainly discussed. Through the in-depth analysis of the current research and application status of organic solid waste treatment and disposal, feasible high-value resource utilization technologies were discussed, and the development direction of organic solid waste heat conversion was proposed. Furthermore, relevant policy documents on the treatment and disposal of organic solid waste in China were outlined, and the environmental emission reduction benefits of organic solid waste heat conversion utilization were summarized. Suggestions for commercial models of organic solid waste heat conversion in China were proposed, aiming to provide a reference for promoting the harmless, high-value, resourceful clean utilization and industrial application of organic solid waste in urban and rural areas in China.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 2066K]

  • Chemical extraction and precipitation recovery performance of phosphorus from four kinds of sludge heat treatment products

    ZHANG Zhihan;LUO Xinyi;ZHANG Aijia;YANG Yingju;LIU Jing;QIAO Yu;State Key Laboratory of Coal Combustion,School of Energy and Power Engineering,Huazhong University of Science and Technology;

    Sewage sludge contains a large amount of phosphorus, and the recovery of phosphorus can realize the secondary utilization of phosphorus resources. The phosphorus recovery experiments in the acid leaching solution of four kinds of sludge thermal treatment products, including smoldering ash, mixed ash, incineration ash and pyrolysis coke were conducted by the magnesium ammonium phosphate(MAP) recovery method. The phosphorus recovery performance of each thermal treatment product under the acid leaching-MAP recovery process route was analyzed. The phosphorus precipitation rate, the phosphorus and impurities contents in the products were explored. The environmental safety of the precipitated products was further investigated. The results show that the phosphorus content of the precipitate product can reach 19.82-31.71 mg/g, and the phosphorus recovery rate in the original sludge reaches 49.25%-65.81% by the acid leaching-MAP recovery method. The order of the phosphorus recovery performance is incineration ash > pyrolysis coke > smoldering ash > mixed ash. There are a large number of Ca, Fe, Al and Si impurities in the acid leaching MAP recovery product, and a certain amount of Zn, Pb, Cr, Cu, Cd, As and Ni, with Zn content much higher than other heavy metals. The purity and environmental safety of the products follows the order of incineration ash > mixed ash > pyrolysis coke > smoldering ash. In the terms of the environmental safety of the precipitated products, the heavy metal content of the acid leaching-MAP recovered products of smoldering ash, incineration ash and pyrolysis coke all meet the "Ecological Index of Arsenic, cadmium, lead and mercury in Fertilizers" written in GB/T 23349—2009 and the "Control Standard of Pollutants in Agricultural Sludge" written in GB 4284—2018. The content of Cd in the recovered product from the mixed ash using acid leaching-MAP is 3.20 mg/kg, which exceeds the limited value of 3.00 mg/kg for pollutant control of agricultural sludge.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 629K]

  • Preparation of various crystal forms of calcium carbonate from industrial solid waste by CO_2 indirect mineralization

    MEI Jieqiong;LU Shijian;REN Xuefeng;KANG Guojun;LIU Ling;Jinagsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization,China University of Mining and Technology;Institute of Carbon Neutralization,China University of Mining and Technology;School of Chemical Engineering,China University of Mining and Technology;

    The emissions of CO_2 and industrial solid waste are increasing year by year, posing a threat to human survival and development. Countries around the world are urgently seeking solutions to reduce carbon emissions. Researchers have developed a series of CO_2 mineralization processes by reacting calcium and magnesium elements with CO_2 to generate stable carbonates, achieving permanent CO_2 storage. In order to achieve large-scale CO_2 storage, high-value utilization of calcium containing solid waste, and reduce mineralization costs, inexpensive and easily available calcium containing industrial solid waste was selected as mineralization raw materials. Started from the preparation of polycrystalline micro nano calcium carbonate, the latest research progress on the leaching of calcium containing industrial solid waste and CO_2 interstitial mineralization was summarized. The commonly used leaching agents for indirect mineralization of calcium containing industrial solid waste were introduced, and the impact of reaction conditions and crystal form control agents on the crystal form and morphology of micro nano calcium carbonate during indirect mineralization preparation was analyzed. The control principle was understood and explained. Finally, the current technical difficulties and future research focus of indirect mineralization technology were summarized and discussed. The results indicate that adjusting the mineralization reaction conditions such as temperature, pH, stirring rate, and CO_2 aeration rate, or adding crystal form control agents, can effectively control the crystal form, morphology, and size of calcium carbonate. The indirect mineralization of CO_2 from industrial solid waste containing calcium to prepare micro nano calcium carbonate can meet the requirements of different fields for the use of calcium carbonate, and can generate economic and environmental benefits, with broad development prospects.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 399K]

  • Research progress on the hydrothermal carbonization characteristics of low rank coal and biomass and the functionalization modification of hydrochar

    SONG Ruizhen;YANG Xiaoyang;ZHANG Peng;WANG Baofeng;Engineering Research Center of CO2 Emission Reduction and Resource Utilization-Ministry of Education of the People′s Republic of China,Institute of Resources and Environment Engineering,Shanxi University;

    The abundant oxygen-containing functional groups in low rank coal endow it with strong hydrophilicity, and cause the pore surface to absorb a large amount of water, which makes the transportation costs increasing and energy conversion efficiency reducing. Therefore, the clean, low-carbon and efficient conversion of low rank coal has attracted more and more attentions. Hydrothermal carbonization is a green, low-carbon, efficient, and economical low-rank coal upgrading technology. It consumes low energy and can treat organic solid substances with high moisture content directly. As a renewable energy source, biomass can replace fossil fuels. Through hydrothermal carbonization, the quality of biomass can be improved significantly. During co-hydrothermal carbonization of low rank coal and biomass, there will be a certain synergistic effect between them, and compared to hydrothermal carbonization of low rank coal or biomass alone, co-hydrothermal carbonization can result in higher yield and carbon retention ratio. Furthermore, functionalization modification of hydrochar can further enrich its pore structure, increase the functional groups on the material surface, and obtain high-performance functional carbon materials for gas adsorption such as CO_2 and SO_2. In this paper, the hydrothermal carbonization characteristics of low rank coal, biomass and their mixture were reviewed, and the main influencing factors of biomass hydrothermal carbonization were analyzed. The activation and doping modification methods of hydrochar were also summarized, and the doping methods, mechanisms and application scope of nitrogen, sulfur doping, and co-doping hydrochar were compared. Moreover, the adsorption performance of modified hydrochar for CO_2 and SO_2 was also introduced, and the mechanism of CO_2 and SO_2 adsorption on the surface of porous carbon were described. At the end, the future development directions of co-hydrothermal carbonization of low rank coal and biomass were suggested, as well as for the low-cost preparation of gas adsorbents using hydrochar.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 559K]

  • Perovsokite-anchored ceria for chemical looping dry reforming

    ZHANG Juping;SONG Fuping;LIU Tianzhu;ZHU Tao;LI Dongfang;ZHU Xing;Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology;

    Chemical looping dry reforming of methane(CL-DRM) is a process simultaneously utilizing two greenhouse gases, carbon dioxide, and methane, and converting them into syngas that can be used for Fischer-Tropsch synthesis. A series of(Ni/CeO_2)/ABO_3(Perovskite-type) composite oxygen carriers were prepared by sol-gel and impregnation methods and the effects of Ni/CeO_2 loading on the oxygen storage performance of perovsokite were investigated. The effects of different Ni/CeO_2 loadings on the activity of La_(0.8)Sr_(0.2)FeO_3 perovskites were explored and the cycling stability of the oxygen carriers was analyzed. It was found that the interaction of CeO_2 with the carrier La_(0.8)Sr_(0.2)FeO_3 favors the formation of oxygen vacancies in perovsokite, which enhances their oxygen mobility. The loading of Ni/CeO_2 improved the oxygen storage performance of the oxygen carrier, lowering the initial reaction temperature and enhancing the reaction activity, however, a high loading would lead to methane cracking to form carbon deposits. The(Ni/CeO_2)/La_(0.8)Sr_(0.2)FeO_3 composite oxygen carrier reached 82% methane conversion with a 2.1 H_2/CO molar ratio when the Ni/CeO_2 loading was 20%. Furthermore, the catalyst remained stable after 30 cycles and showed excellent cycling stability performance. In addition, CeO_2 particle size can significantly affect the dispersion of the Ni phase. The reduction of CeO_2 particle size enhances interfacial interaction with metal Ni, improves oxygen carrier reactivity, and reduces methane cracking. Modulating CeO_2 particle size enabled the oxygen carrier to achieve over 87% CH_4 conversion, over 90% CO selectivity, and a H_2/CO ratio of 2.18, close to the ideal value of 2.0. The strategy of preparing composite oxygen carriers with perovsokite-anchored active species offers an effective approach for high performance in chemical looping dry reforming. Additionally, the preparation of highly active and stable composite metal oxide oxygen carriers serves as a reference for oxygen storage catalytic materials in related fields.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 898K]

  • Analysis of the carbon emission reduction potential of straw hydrothermal liquefaction technology in 30 provinces of China

    LIU Zuoxi;WEI Yingying;WANG Jian;YANG Tianhua;WANG Shanshan;LI Bingshuo;LI Yanlong;LIU Shan;School of Energy and Environment,Shenyang University of Aeronautics and Astronautics;Department of Quality Control,Liaoning Center for Disease Control and Prevention;

    Hydrothermal liquefaction technology, as a biomass thermo-chemical method with broad prospects for development and utilization, is still in a blank state of research on the carbon emission reduction potential of hydrothermal liquefaction technology in China. In order to reduce greenhouse gas emissions and energy consumption, conventional hydrothermal liquefaction technology is combined with photovoltaic technology to use renewable energy electricity to replace the electricity consumption during the operation of the hydrothermal liquefaction system, and utilize the biochar produced to return to the soil by using soil carbon sequestration technology, achieving negative carbon emissions. The greenhouse gas(GHG) emissions, energy consumption and carbon reduction potential of deploying photovoltaic(PV) hydrothermal liquefaction(HRL) plants in 30 provinces in China were studied, and a multi-region hybrid life cycle assessment model in China was established. The input-output life cycle was combined with the IPCC factorization approach to calculate GHG emissions and energy consumption. Firstly, the life cycle GHG emissions and energy consumption of the PV hydrothermal liquefaction plant in Henan Province as a demonstration province were assessed. The carbon dioxide emissions of the PV hydrothermal liquefaction plant are 128.76 t(CO_2-eq) and the total energy consumption was 48 371.01 kg(standard coal)during its construction. The energy consumption and GHG emission impacts of each province and its economic sector can be obtained in an input-output economic context by using the established hybrid LCA. Henan Province has the most significant impact from a spatial perspective. Furthermore, the chemical products sector is the largest sector for implied GHG emitting and energy consuming. The carbon reduction efficacy of different proportions of biochar returned to the soil were analyzed base on scenarios. The results show that the carbon dioxide emissions will be reduced by 1 686.53 t by returning all the biochar produced by a photovoltaic hydrothermal liquefaction plant in Henan Province to the soil. Combining biochar carbon sequestration technology, the impact of GHG emissions from transportation distances of 41-200 km in conjunction was analyzed. The results show that even if sufficient straw yield is collected by expanding the collection radius in straw-poor areas, the construction of a photovoltaic hydro-thermal liquefaction plant will reduce carbon dioxide emissions by 1 603.91 t when all the biochar produced is returned to the field. Photovoltaic hydrothermal liquefaction(PVHL) technology has the potential for large-scale deployment. So assuming that straw from all provinces is maximized for use in PVHL, the carbon dioxide emissions will be reduced by 213.2 Mt/a by the production of bio-oil and bio-gas to replace the use of fossil fuels, and the production of bio-char will all be immobilized in the soil, which will result in a cumulative reduction of 114.14 Mt/a. Therefore, the deployment of PV hydrothermal liquefaction technology in 30 provinces in China could have a significant impact on achieving national GHG reduction targets.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 1126K]

  • Research progress on the reactivity of biomass char and its correlation with Raman spectroscopy characterization

    BAO Zhengyan;LU Zhimin;CHEN Jinzheng;CAI Jianfeng;YAO Shunchun;School of Electric Power,South China University of Technology;

    Biomass energy, as the most extensively utilized source of renewable energy, has advantages such as substantial reserves, the absence of carbon emissions, renewability, and consistent supply. The usage of biomass char is a significant aspect of biomass energy utilization, and its reactivity varies greatly due to different types of raw materials, which seriously hinders the advancement of research and the utilization of biomass energy. The reactivity of biomass char is primarily influenced by inorganic components, texture properties, and carbon structure. Raman spectroscopy, as a fast-advancing technique for characterizing carbon structures, has has been widely used in the study of the physical and chemical properties of biomass char. In this paper, starting from the spectral parameters such as band position, band width, band intensity ratio, and band area of biomass coke Raman spectroscopy, the carbon structure of biomass char at home and abroad was summarized. The changes in carbon structure during the thermochemical transformation of biomass char were thoroughly analyzed. Raman spectroscopy is a reliable method for analyzing the carbon skeleton structure of biomass char. The presence of a well-organized aromatic or graphitized structure in the char will decrease its reactivity. Currently, there is a limited amount of research on the relationships between the reactivity of biomass char and the carbon skeleton structure characterized by Raman spectroscopy. These studies mostly concentrate on a specific type of biomass, and the generalizability of its findings still needs to be verified. There are also a few studies on the char reactivity and Raman spectrum of various biomass raw materials. However, no quantitative conclusions have been given. The research findings on the relationships between the char reactivity of different biomass feedstock and the Raman parameters of char were introduced, in order to offer a reference for future studies on the reactivity of biomass fuel. The future holds enormous potential for the development of Raman spectroscopy in analyzing biomass char. Currently, the primary focus of study is on analyzing the spectral region of the first-order Raman spectrum. The second-order Raman spectrum has not received much attention. In addition, advanced Raman spectroscopy techniques, including surface-enhanced Raman spectroscopy, tip-enhanced Raman spectroscopy, and coherent anti-Stokes Raman scattering, have not yet been utilized in the analysis of carbon structure and reactivity in biomass char, and should be given priority consideration in the future.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 1025K]

  • Research progress in directional construction of biomass carbon-based electrolysis water catalysts

    LIU Faming;LI Guoning;MA Weiyang;GUO Min;LI Shijie;XIAO Qiangqiang;LU Wanpeng;LI Hui;School of Thermal Engineering, Shandong Jianzhu University;

    Biomass carbon has the advantages of affordability, environmental friendliness, and adjustable pore structure. It is a good matrix for loading transition metals and has broad application prospects in water electrolysis. The specific surface area, pore size distribution, and other physical and chemical structures of carbon carriers directly affect the utilization of transition metal active sites and electrolyte ion diffusion, which is the key to unleashing the potential of transition metal electrolysis for water catalysis and determining catalyst performance. This article introduced the pyrolysis mechanisms of different biomass, summarized common biomass carbon preparation methods such as high-temperature pyrolysis, hydrothermal carbonization, and microwave pyrolysis, and compared the advantages and disadvantages of different preparation methods. A summary of targeted control strategies for biomass carbon physicochemical structure, including physical, chemical, and template methods, was conducted, and the effects of different control strategies on biomass carbon specific surface area, pore volume, average pore size, and other physicochemical properties were explored. The construction strategies of common biomass carbon-based electrolysis water catalysts, such as doping with heteroatoms and loading with metal active components were summarized. The research status of these catalysts in oxygen evolution reaction, hydrogen evolution reaction, bifunctional catalysis, and hybrid electrolysis of water was also summarized, and the progress made in electrolysis of water was elaborated in detail. And the challenges faced by biomass carbon-based electrolysis water catalysts in controlling micro to mesoporous ratio, improving conductivity, hydrophilicity, and catalyst forming treatment were discussed in the future.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 628K]

  • Effects of co-combustion of semi-coke and biomass on emissions and combustion characteristics of NO_x and SO_2

    WANG Xuewen;CHEN Long;ZHANG Chao;ZHANG Xin;LIU Pengzhong;YANG Shi;Beijing Tiandi Rongchuang Technology Co., Ltd.;

    The co-combustion of biomass and semi-coke is considered to be a potential way to solve a large number of air pollution-related problems such as carbon emissions, NO_x and SO_2. The air-staged combustion characteristics of semi-coke, mixture of semi-coke and biomass were studied by thermogravimetric experiment and drop tube furnace experiment respectively. The effects of blending ratio on ignition temperature, burnout temperature, slagging characteristics, fouling characteristics and combustion characteristic index of mixed fuel were analyzed, and the suitable air-staged combustion ratio, optimal combustion temperature and optimal blending ratio were determined. The results show that the ignition point of the mixed fuel is effectively reduced after co-firing biomass, and the ignition point is reduced from 474 ℃ to 300 ℃. The burnout temperature is slightly reduced after co-firing biomass. The combustion characteristic index is not significantly improved by the combustion of carbon mixed biomass. The combustion of biomass mixed with carbon powder has a tendency of high ash deposition and a small tendency of slagging. The outlet NO_x mass concentration and outlet SO_2 mass concentration after co-firing biomass at different temperatures are lower than those before co-firing. Compared with those before co-firing, the mass concentration of outlet NO_x and SO_(2 )at 1 200 ℃ decreases significantly, reaching by 87.27 % and 80.2 % respectively. Based on comprehensive export parameters such as NO_x, the optimal biomass mass fraction is 30%~40%, and the optimal combustion temperature range is 1 200~1 300 ℃ under the condition of no air classification. The initial NO_x emission of biomass with a mass fraction of 30% changes gently with temperature during staged combustion, showing good stability. The outlet NO_x mass concentration is the lowest, all below 125 mg/m~3. The research conclusions can provide some technical support for the equipment operation of organic solid waste incineration disposal and the organizational regulation of related combustion conditions.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 840K]

  • Mineralogical elemental and geochemistry characteristics of fly ash from coal-fired power plants in Ningdong Energy Chemical Industry Base

    HUANG Pengcheng;CAI Feifei;WU Tiancai;ZHAO Hui;GUO Weiyong;LIANG Yongping;QI Fenghua;Coal Geology Bureau of Ningxia Hui Autonomous Region;China University of Geosciences;Ningxia Yinxing Power Generation Co.LTD;

    The physicochemical properties of fly ash, such as type, element and mineral composition, are the foundation determining the multiple utilization of fly ash. To achieve the potential high-value utilization of fly ash from coal-fired power plants around the Ningdong Energy Base, the raw coal, slag, coarse ash, and fine ash from the Maliantai and Yinxing power plants were studied. The chemical composition and microelement concentration of the fly ash were analyzed by X-ray fluorescence broad spectrum(XRF) and inductively coupled plasma mass spectrometry(ICP-MS). The mineral composition and morphological characteristics of fly ash were analyzed by X-ray diffractometer(XRD) and scanning electron microscope. The results show that the chemical composition of the coarse and fine fly ash from Maliantai and Yinxing power plants are mainly composed of SiO_2, Al_2O_3, Fe_2O_3 and CaO, with a minor amount of TiO_2, MnO, MgO, Na_2O, K_2O and P_2O_5. The mass fractions of CaO in the fly ash of the two power plants are less than 10%, and w(SiO_2)+w(Al_2O_3)+w(Fe_2O_3)>75.39%, classifying them as F-type low-Ca fly ash. The crystalline mineral phases mainly comprise of quartz, mullite, hematite, lime, anorthite, anhydrite, dolomite, and calcite; glassy is mainly composed of SiO_2 and Al_2O_3, and is characterized by a high SiO_2/Al_2O_3 mass ratio(2.18~2.36). The contents of most microelements in coarse ash and fine ash are lower than the maximum of corresponding elements in European fly ash. B, V, Co, Cu, Ga, Sn, Cs, Ti, Pb, Zn, Sn and other volatile and relatively high condensing elements are easy to be enriched in fly ash. Mg, Ca, Sr, Fe, Mn, Cr, Ni and other volatile elements are easy to be enriched in slag. The low microelement content, low leaching capacity, high glassy content and high SiO_2/Al_2O_3 mass ratio in the fly ash of the two power plants indicate its high utilization value and low environmental risk in the process of resource utilization.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 418K]

  • Effect of synergistically constructed pore configuration and nitrogen-containing functional groups on low-temperature NO reduction performance of activated coke

    YANG Jiacheng;HE Minqiang;QU Zhibin;CHEN Lanxin;YANG Chenglong;LI Yang;SUN Fei;School of Energy Science and Engineering, Harbin Institute of Technology;Xi'an Thermal Power Research Institute Co., Ltd;

    Low-temperature NH_3-SCR is an important technology choice for flue gas denitrification in non-electricity industries with low exhaust temperature, and low-cost carbon materials with good structural tunability are one of the most promising low-temperature NH_3-SCR catalysts, but face the bottleneck of low denitrification efficiency. In this paper, based on a one-step catalytic activation process, activated coke catalysts with typical pore configurations and nitrogen-containing functional groups were prepared from low-cost and large-volume Jundong coal as raw materials, and the effects of activated coke pore configurations and surface functional groups on the low-temperature NH_3-SCR under different flue gas conditions were investigated. The results showed that both graded pores and nitrogen-containing functional groups have significant effects on NH_3-SCR, and the nitrogen-doped graded-porous activated coke with both graded pores and nitrogen-containing functional groups has the optimal performance of NH_3-SCR due to the simultaneous improvement of the mass transfer channels and reaction kinetics, and its denitrification efficiency reaches as high as 83.5% under the condition of 160 ℃. The enhancement effects of graded pores and nitrogen-containing functional groups on the NH_3-SCR performance are more obvious in the presence of SO_2 or H_2O, and the denitrification efficiency of microporous activated coke decays from 39.6% to 13.8% and 34.9%, whereas the denitrification efficiency of nitrogen-doped graded-porous coke improves to 86.4% and 86.7%, respectively. This may be related to the synergistic effect between different flue gas components enhanced by the functionalized graded pore environment. In this study, the dependence between the performance of carbon-based low-temperature NH_3-SCR and the physicochemical structure of the carbon materials was investigated, which provides a new idea for the development of high-performance carbon-based low-temperature NH_3-SCR technology.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 813K]

  • VOCs emission characteristics of coal-fired units

    CHEN Chao;LIU Weiping;TANG Guofeng;DING Yi;ZHANG Jianwei;ZHU Xifeng;WANG Jiawei;WANG Tao;ZHANG Yongsheng;SDIC Genting Meizhou Wan Electric Power Co., Ltd.;SDIC Power Holding Co., Ltd.;School of Energy, Power and Mechanical Engineering, North China Electric Power University;

    In order to understand the emission characteristics of volatile organic compounds(VOCs) in the flue gas of coal-fired units with different capacities and the control effect of air pollutant control equipment(APCDs) in different tails on VOCs, online and offline sampling tests were carried out at the 400 MW subcritical offset combustion unit and 1 000 MW ultra-supercritical tangential combustion unit of Yunding Meizhou Bay Electric Power Company in Fujian Province. Theses tests aimed to obtain the whole-process concentrations of methane, non-methane total hydrocarbons and other VOCs in flue gas. The results show that the total non-methane hydrocarbon concentration before SCR of 1 000 MW unit(24.66 mg/m~3) is lower than that of 400 MW unit(33.36 mg/m~3). This disparity can be attributed to the higher load and furnace temperature of the 1 000 MW unit, along with the prolonged residence time of coal in the tangential combustion furnace, resulting in more thorough coal combustion. The SCR system of the two units can remove more than 70% of the total non-methane hydrocarbon, with removal rates of 88.43% for 400 MW unit and 74.32% for 1 000 MW unit, respectively. In the electrostatic dust removal(ESP) process, the high voltage electrostatic field may cause the fly ash to release some VOCs, thus increasing the VOCs concentration in the flue gas. Following the implementation of all APCDs, the VOCs emission concentration of 400 MW unit and 1 000 MW unit is 8.40 mg/m~3 and 8.47 mg/m~3, respectively, with the overall removal rate of 73.98% and 63.02%. Notably, almost no methane is detected. The offline test results show that the main components of VOCs after coal combustion in Indonesia are n-hexane, benzene series and benzaldehyde. The organic content analysis of various solid samples(such as coal, ash, gypsum) shows no obvious correlation between VOCs type and unit size. These findings have important significance for further understanding the impact of coal-fired power plants on air quality and optimizing the design of pollution control equipment. In actual operation of coal-fired power plants, pollution control equipment should be optimized according to specific conditions to achieve the maximum removal effect. It is also necessary to consider the unit size and operating efficiency to effectively control VOCs emissions.

    2024 03 v.30;No.163 [Abstract][OnlineView][Download 587K]