With the rapid development of adsorbents for removal of elemental mercury (Hg0) from coal combustion flue gas,the preparation of adsorbents with superior performance,lower cost and environmental friendliness remains a...With the rapid development of adsorbents for removal of elemental mercury (Hg0) from coal combustion flue gas,the preparation of adsorbents with superior performance,lower cost and environmental friendliness remains an important challenge.An incipient wetness impregnation method followed by in-situ selenization was used to load copper selenide(CuSe) onto the surface of optimal magnetic biochar (OMBC).The results showed that CuSe significantly enhanced the Hg0removal performance of the OMBC,and CuSe loading ratio of 10%(10CuSe/OMBC) had the best Hg0removal performance.10CuSe/OMBC maintained its Hg0removal efficiency above 95% for 150 min at 30-150℃,and it had a good resistance to SO2.The equilibrium adsorption capacity of 10CuSe/OMBC could reach up to 8.73 mg/g,which was close to the theoretical value 12.99 mg/g,and the adsorption rate was up to 20.33μg/(g·min) Meanwhile,10CuSe/OMBC had strong magnetism that is not permanently magnetized,which could be separated from desulfurization gypsum and recycled many times.Characterization results demonstrated that Se22-,Cu2+and Oβplayed essential roles in the oxidation of Hg0,and Se22-and Se2-can immobilize Hg2+to HgSe.10CuSe/OMBC has important guiding significance for practical application because of its low cost,high performance and low mercury leaching characteristic to form HgSe.展开更多
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 c...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.展开更多
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 d...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.展开更多
Objective To explore the relationship between different components of fine particulate matter（PM2.5） emitted from coal combustion and their cytotoxic effect in the vascular endothelial cells. Methods Coal-fired PM2....Objective To explore the relationship between different components of fine particulate matter（PM2.5） emitted from coal combustion and their cytotoxic effect in the vascular endothelial cells. Methods Coal-fired PM2.5 was sampled using a fixed-source dilution channel and flow sampler. The sample components were analyzed by ion chromatography and inductively coupled plasma atomic emission spectroscopy（ICP-AES）. The PM2.5 suspension was extracted using an ultrasonic water-bath method and then human umbilical vein endothelial cells（EA.hy926） were treated with various concentrations of the PM2.5 suspension. Cell proliferation, oxidative DNA damage, and global DNA methylation levels were used to measure the cellular toxicity of PM2.5 emitted from coal combustion. Results Compared to other types of coal-fired PM2.5 preparations, the PM2.5 suspension from Yinchuan coal had the highest cytotoxicity. PM2.5 suspension from Datong coal had the highest toxic effect while that from Yinchuan coal had the lowest. Exposure to coal-fired PM2.5 from Jingxi coal resulted in lower 8-hydroxy-2’-deoxyguanosine（8-OHd G） levels. At the same dose, PM2.5 emitted from coal combustion could produce more severe DNA impairment compared to that produced by carbon black. Cell survival rate was negatively correlated with chloride and potassium ions content. The 5-methylcytosine（5-m C） level was positively correlated with Mn and negatively correlated with Zn levels. The 8-OHd G% level was positively correlated with both Mn and Fe. Conclusion PM2.5 emitted from coal combustion can decrease cell viability, increase global DNA methylation, and cause oxidative DNA damage in EA.hy926 cells. Metal components may be important factors that influence cellular toxicity.展开更多
Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result...Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result in deteriorating local air quality.In this study,a dynamic smog chamber was used to investigate the real-time emissions of gaseous and particulate pollutants during the combustion process and a static smog chamber was used to investigate the fume evolution under simulate light irradiation.The real-time emissions revealed that the total hydrocarbon （THC） and CO increased sharply after ignition,and then quickly decreased,indicating volatilization of hydrocarbons with low molecular weight and incomplete combustion at the beginning stage of combustion made great contribution to these pollutants.There was evident shoulder peak around 10min combustion for both THC and CO,revealing the emissions from vitrinite combustion.Additionally,another broad emission peak of CO after 30min was also observed,which was ascribed to the incomplete combustion of the inertinite.Compared with THC and CO,there was only one emission peak for NOx,SO 2 and particular matters at the beginning stage of combustion.The fume evolution with static chamber simulation indicated that evident consumption of SO 2 and NOx as well as new particle formation were observed.The consumption rates for SO 2 and NOx were about 3.44% hr-1 and 3.68% hr-1,the new particle formation of nuclei particles grew at a rate of 16.03 nm/hr during the first reaction hour,and the increase of the diameter of accumulation mode particles was evident.The addition of isoprene to the diluted mixture of the fume could promote O 3 and secondary particle formation.展开更多
Gas products from the process of coal oxidization and spontaneous combustion have been studied at different temperatures with FTI spectroscopic tests. With temperatures rising to about 30~100 ℃, water and carbon diox...Gas products from the process of coal oxidization and spontaneous combustion have been studied at different temperatures with FTI spectroscopic tests. With temperatures rising to about 30~100 ℃, water and carbon dioxide gas were formed and from about 105~150 ℃, carbon monoxide was produced. Using the DFT B3LYP method with a 6-311G basis set, the reaction system, where spontaneous combustion between coal and oxygen occurs and produces water and monoxide, has been studied, with the geometric configuration for all stagnation points on the potential reaction energy surface optimized. With a frequency analysis and an IRC method, transient formations were tested. Our results indicate that in the reaction of coal oxidization and spontaneous com-bustion producing carbon dioxide and water, oxygen molecules attack carbon atoms of the terminal of the propyl alcohol group on the lateral chain of benzene rings, which causes this propyl alcohol group to produce the acid (-CH2-CH2-COOH) group and water. This acid group continues its break up into carbon dioxide and the (-CH2-CH3) ethyl group. We have come to the conclusion that this water-and-carbon dioxide-production reaction is spontaneous, based on the observation of the energy released by the reaction.展开更多
The destruction of the ozone layer in the atmosphere caused by industriallysynthesized CFCs has aroused greatest concerns from the international society, but the CFCs formedfrom burning of coal containing fluorine hav...The destruction of the ozone layer in the atmosphere caused by industriallysynthesized CFCs has aroused greatest concerns from the international society, but the CFCs formedfrom burning of coal containing fluorine have not been recognized by the world yet. In the presentstudy, we condensed the gas through cold traps and used the GC-MS to measure the gas composition,and found that the content of CFC-12 in the smog from coal combustion was significantly higher thanthe background value of the local atmosphere. This proves that CFC- 12 is formed in the process ofcoal combustion. This paper discusses a new source of non-synthesized CFCs.展开更多
Volatile organic compounds （VOCs） play ,an important role in ozone and secondary organic aerosol （SOA） formation, but VOCs sources during winter are not fully understood. To investigate VOCs sources during winter,...Volatile organic compounds （VOCs） play ,an important role in ozone and secondary organic aerosol （SOA） formation, but VOCs sources during winter are not fully understood. To investigate VOCs sources during winter, mixing ratios of C2-C12 VOCs were measured at an urban site in Beijing from December 29, 2011 to January 17, 2012. Correlation analysis of toluene to benzene and i-pentane to n-pentane suggest that coal combustion could also be an important source for VOCs besides vehicular emissions. Source apportionment results show that coal combustion and vehicular emissions contributed 28%-39% and 31%-45% to ambient VOCs during winter, respectively. Backward trajectory analyses demonstrated that contributions from the burning of coal were higher when air masses came from southern regions outside Beijing. Close attention should be paid to VOCs emissions from coal combustion in Beijing city and the vicinity to the South.展开更多
In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China, we have analyzed the characteristics of spontaneous coal combustion and explain ...In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China, we have analyzed the characteristics of spontaneous coal combustion and explain theoretically the factors affecting spontaneous coal combustion, such as rock bursts, high temperatures, high ventilation resistance, slow advancing speed and large obliquity mining. Key technologies to prevent spontaneous combustion occurring in sharply inclined seams in deep mines are pro- posed; these include pouring water, stopping leakage in upper and lower comers of the working face, choking off the goaf and cov- eting the coal. CO concentrations were controlled within two years to less than 15×10^-6 at the upper comer by applying these tech- nologies at the 1410 working face of the Huafeng coal mine. Our method has significant theoretical value and is of practical impor- tance in controlling spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines.展开更多
The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary ...The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary for numerical simulation of combustion process, the uneven radiation parameter can be calculated. A method to examine three-dimensional temperature distribution in blast furnace raceway was put forward by radiant image processing. The numeral temperature field matching the real combustion can be obtained by proposed numeric image processing technique.展开更多
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 pro...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 compositions.The 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 heating.The 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 city.Positive 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 total.Our 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.展开更多
In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional r...In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional radiant energy in a blast furnace raceway, focusing on the correlativity of the numerical simulation of combustion processes with the connection of radiant images information and space temperature distribution. We calculated the uneven radiate characteristic parameterby taking radiant images as a kind of radiative boundary for numerical simulation of combustion processes, and put fonward a method to examine three-dimensional temperatures distribution in blast furnace raceway by radiant image processing. The numeral temperature fields matching the real combustion can be got by the numeric image processing technique.展开更多
Emissions of volatile organic compounds （VOCs） and carbonyls from residential coal combustion of five coals with different maturities were studied in a simulated room.The coals were burned in form of honeycomb briqu...Emissions of volatile organic compounds （VOCs） and carbonyls from residential coal combustion of five coals with different maturities were studied in a simulated room.The coals were burned in form of honeycomb briquettes in a domestic coal stove,one of the most common fuel/stove combinations in China.Through a dilution system,VOCs and carbonyls samples were collected by canisters and silica-gel cartridges and analyzed by gas chromatography and mass spectrum （GC/MS） and high performance liquid chromatography/ultraviolet （HPLC/UV）,respectively.The results show that the bituminous coals with medium volatile matter content produce the highest emissions while the anthracite yields the lowest.Among the identified carbonyls from the coal smoke,the aromatic compounds （benzaldehyde,2,5-dimethylbenzaldehyde and p-tolualdehyde,m/o-tolualdehyde,benzene,m,p-xylene and trimethyl-benzene） were relatively abundant,which might be due to the molecular structure of the coal.For formaldehyde,aromatic carbonyls and aliphatic alkanes,their concentrations increase up to the maximum values and then decrease with increasing coal maturity.The total carbonyls and VOCs have the same tendency,which was observed for the emission factors of organic carbon （OC）,elemental carbon （EC）,particulate matter （PM） and polycyclic aromatic hydrocarbons （PAHs） detected in the series study.展开更多
NO emissions from coal combustion are receiving significant attention in recent years. As a solid waste generated from metallurgical industry, metallurgical dust （MD） contains a large amount of metal oxides, such as...NO emissions from coal combustion are receiving significant attention in recent years. As a solid waste generated from metallurgical industry, metallurgical dust （MD） contains a large amount of metal oxides, such as Fe2O3, CaO, SiO2 and Al2O3, as well as other rare metal oxides. The influence of MD on the NO emissions and the mechanism of the coal com- bustion systems were analyzed. The results show that the peak values of NO emission decrease with the increase in MD mass percent, and the curve of NO emission can be divided into two stages including rapid generation （400-600 ℃） and slow release （800-900 ℃）. The reduction of NO is significantly affected by temperature, volatile components, 02 and CO. CO has a significant catalytic action which can deoxidize NO to N2. The results obtained by X-ray diffraction and scanning electron microscopy indicate that multiple components in MD, such as FegTiO15, Fe2O3 and TiO2, can react with NO to produce TiN. Besides, the alkali metals in MD, such as Na, K and Ca, may catalyze NO precursor to inhibit NO emission. These results indicate that MD is cheap and highly efficient in controlling NO emissions during coal combustion processes.展开更多
Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons （PAHs） are important in flue gas of the stove. By using dilution tunnel s...Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons （PAHs） are important in flue gas of the stove. By using dilution tunnel system, samples of both gaseous and particulate phases from domestic coal combustion were collected and 18 PAH species were analyzed by GC-MS. The average emission factors of total 18 PAH species was 171.73 mg/kg, ranging from 140.75 to 229.11 mg/kg for bituminous coals, while was 93.98 mg/kg, ranging from 58.48 to 129.47 mg/kg for anthracite coals. PAHs in gaseous phases occupied 95% of the total of PAHs emission of coal combustion. In particulate phase, 3-ring and 4- ring PAHs were the main components, accounting for 80% of the total particulate PAHs. The total toxicity potency evaluated by benzo[a]pyrene-equivalent carcinogenic power, sum of 7 carcinogenic PAH components and 2,3,7,8-tetrachlorodibenzodioxin had a similar tendency. And as a result, the toxic potential of bituminous coal was higher than that of anthracite coal. Efficient emission control should be conducted to reduce PAH emissions in order to protect ecosystem and human health.展开更多
The efficiency of coal combustion is an important factor for the blast furnace process.The influence of low xO/xC on coal combustion performance under nitrogen free blast furnace condition was researched through the s...The efficiency of coal combustion is an important factor for the blast furnace process.The influence of low xO/xC on coal combustion performance under nitrogen free blast furnace condition was researched through the self-developed pulverized coal burning device.The results show that the coal combustion rate reduces with xO/xC decreasing,and the combustion rate of bituminous coal is higher than that of anthracite.The coal combustion rate ascends with the rise of volatile matter,but when volatile matter of pulverized coal is more than 18%,the combustion rates will not increase correspondingly.Small amount of CaCO3 and CO2 additions can promote coal combustion,and the effect of CaCO3 is more apparent,which can increase the pulverized coal combustion rate by 15%-18% or so.展开更多
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 ...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.展开更多
The change of bubbles and the position of the tuyere in an oxygen coal combustion melting and separating furnace affect the flow and splash behavior of the molten pool.To analyze this problem further,a three-dimension...The change of bubbles and the position of the tuyere in an oxygen coal combustion melting and separating furnace affect the flow and splash behavior of the molten pool.To analyze this problem further,a three-dimensional numerical simulation method was used to explore the behavior and change of the flow field inside the molten pool during double-row tuyere injection.In addition,the arrangement of the tuyere was changed for a more detailed understanding of the internal phase distribution and splashing in a molten pool.The results indicated that under three-dimensional numerical simulation conditions,bubbles rise after leaving the tuyere and break on the surface of the molten pool,which results in certain fluctuations in the nearby melt.During the injection process of the tuyere,the meteorological accumulation in the middle part of the molten pool formed part of the foam slag because of the influence of surface tension.When the layout of the upper and lower exhaust tuyeres was changed from staggered to symmetrical,or when the spacing of the upper and lower exhaust tuyeres changed,it had an effect on the phase distribution and splash behavior.展开更多
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 aver...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.展开更多
Large-eddy simulation(LES) is under its rapid development and is recognized as a possible second generation of CFD methods used in engineering.Large-eddy simulation of two-phase flows and combustion is particularly im...Large-eddy simulation(LES) is under its rapid development and is recognized as a possible second generation of CFD methods used in engineering.Large-eddy simulation of two-phase flows and combustion is particularly important for engineering applications.Some investigators,including the present authors,give their review on LES of spray combustion in gas-turbine combustors and internal combustion engines.However,up to now only a few papers are related to the state-of-the-art on LES of gas-particle flows and combustion.In this paper a review of the advances in LES of complex gas-particle flows and coal combustion is presented.Different sub-grid scale(SGS) stress models and combustion models are described,some of the main results are summarized,and some research needs are discussed.展开更多
基金supported by the Basic Research Business Fund Grant Program for University of Science and Technology Beijing(No.06500227)the Fundamental Research Funds for the Central Universities(No.FRF-TP-22-091A1)+1 种基金National Natural Science Foundation of China(No.52200121),Chinese Universities Scientific Fund(No.00007713)the Guide special project(No.40103322).
文摘With the rapid development of adsorbents for removal of elemental mercury (Hg0) from coal combustion flue gas,the preparation of adsorbents with superior performance,lower cost and environmental friendliness remains an important challenge.An incipient wetness impregnation method followed by in-situ selenization was used to load copper selenide(CuSe) onto the surface of optimal magnetic biochar (OMBC).The results showed that CuSe significantly enhanced the Hg0removal performance of the OMBC,and CuSe loading ratio of 10%(10CuSe/OMBC) had the best Hg0removal performance.10CuSe/OMBC maintained its Hg0removal efficiency above 95% for 150 min at 30-150℃,and it had a good resistance to SO2.The equilibrium adsorption capacity of 10CuSe/OMBC could reach up to 8.73 mg/g,which was close to the theoretical value 12.99 mg/g,and the adsorption rate was up to 20.33μg/(g·min) Meanwhile,10CuSe/OMBC had strong magnetism that is not permanently magnetized,which could be separated from desulfurization gypsum and recycled many times.Characterization results demonstrated that Se22-,Cu2+and Oβplayed essential roles in the oxidation of Hg0,and Se22-and Se2-can immobilize Hg2+to HgSe.10CuSe/OMBC has important guiding significance for practical application because of its low cost,high performance and low mercury leaching characteristic to form HgSe.
基金Item Sponsored by National Key Technology Research and Development Programin 11th Five-Year Plan of China(2008BAB32B05)
文摘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.
基金supported by project no. CZ.1.05/2.1.00/03.0069 (ENET-Energy Units for Utilization of Non Traditional Energy Sources)supported by LO 1203 (Regional Material and Technology Research Centre)
文摘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.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.21507122)
文摘Objective To explore the relationship between different components of fine particulate matter（PM2.5） emitted from coal combustion and their cytotoxic effect in the vascular endothelial cells. Methods Coal-fired PM2.5 was sampled using a fixed-source dilution channel and flow sampler. The sample components were analyzed by ion chromatography and inductively coupled plasma atomic emission spectroscopy（ICP-AES）. The PM2.5 suspension was extracted using an ultrasonic water-bath method and then human umbilical vein endothelial cells（EA.hy926） were treated with various concentrations of the PM2.5 suspension. Cell proliferation, oxidative DNA damage, and global DNA methylation levels were used to measure the cellular toxicity of PM2.5 emitted from coal combustion. Results Compared to other types of coal-fired PM2.5 preparations, the PM2.5 suspension from Yinchuan coal had the highest cytotoxicity. PM2.5 suspension from Datong coal had the highest toxic effect while that from Yinchuan coal had the lowest. Exposure to coal-fired PM2.5 from Jingxi coal resulted in lower 8-hydroxy-2’-deoxyguanosine（8-OHd G） levels. At the same dose, PM2.5 emitted from coal combustion could produce more severe DNA impairment compared to that produced by carbon black. Cell survival rate was negatively correlated with chloride and potassium ions content. The 5-methylcytosine（5-m C） level was positively correlated with Mn and negatively correlated with Zn levels. The 8-OHd G% level was positively correlated with both Mn and Fe. Conclusion PM2.5 emitted from coal combustion can decrease cell viability, increase global DNA methylation, and cause oxidative DNA damage in EA.hy926 cells. Metal components may be important factors that influence cellular toxicity.
基金supported by the Central Public-Interest Scientific Institution Basal Research Fund (No. 2009KYYW01)the National Natural Science Foundation of China (No. 40705043)the Open Foundation of Environmental Simulation and Pollution Control State Key Laboratories (Peking University)
文摘Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result in deteriorating local air quality.In this study,a dynamic smog chamber was used to investigate the real-time emissions of gaseous and particulate pollutants during the combustion process and a static smog chamber was used to investigate the fume evolution under simulate light irradiation.The real-time emissions revealed that the total hydrocarbon （THC） and CO increased sharply after ignition,and then quickly decreased,indicating volatilization of hydrocarbons with low molecular weight and incomplete combustion at the beginning stage of combustion made great contribution to these pollutants.There was evident shoulder peak around 10min combustion for both THC and CO,revealing the emissions from vitrinite combustion.Additionally,another broad emission peak of CO after 30min was also observed,which was ascribed to the incomplete combustion of the inertinite.Compared with THC and CO,there was only one emission peak for NOx,SO 2 and particular matters at the beginning stage of combustion.The fume evolution with static chamber simulation indicated that evident consumption of SO 2 and NOx as well as new particle formation were observed.The consumption rates for SO 2 and NOx were about 3.44% hr-1 and 3.68% hr-1,the new particle formation of nuclei particles grew at a rate of 16.03 nm/hr during the first reaction hour,and the increase of the diameter of accumulation mode particles was evident.The addition of isoprene to the diluted mixture of the fume could promote O 3 and secondary particle formation.
基金Financial support for this work, provided by the National Natural Science Foundation of China (No.50834002)the National Eleventh Five-year Plan Science and Technology Key Project (No. 2006BAK03B05), is gratefully acknowledged
文摘Gas products from the process of coal oxidization and spontaneous combustion have been studied at different temperatures with FTI spectroscopic tests. With temperatures rising to about 30~100 ℃, water and carbon dioxide gas were formed and from about 105~150 ℃, carbon monoxide was produced. Using the DFT B3LYP method with a 6-311G basis set, the reaction system, where spontaneous combustion between coal and oxygen occurs and produces water and monoxide, has been studied, with the geometric configuration for all stagnation points on the potential reaction energy surface optimized. With a frequency analysis and an IRC method, transient formations were tested. Our results indicate that in the reaction of coal oxidization and spontaneous com-bustion producing carbon dioxide and water, oxygen molecules attack carbon atoms of the terminal of the propyl alcohol group on the lateral chain of benzene rings, which causes this propyl alcohol group to produce the acid (-CH2-CH2-COOH) group and water. This acid group continues its break up into carbon dioxide and the (-CH2-CH3) ethyl group. We have come to the conclusion that this water-and-carbon dioxide-production reaction is spontaneous, based on the observation of the energy released by the reaction.
文摘The destruction of the ozone layer in the atmosphere caused by industriallysynthesized CFCs has aroused greatest concerns from the international society, but the CFCs formedfrom burning of coal containing fluorine have not been recognized by the world yet. In the presentstudy, we condensed the gas through cold traps and used the GC-MS to measure the gas composition,and found that the content of CFC-12 in the smog from coal combustion was significantly higher thanthe background value of the local atmosphere. This proves that CFC- 12 is formed in the process ofcoal combustion. This paper discusses a new source of non-synthesized CFCs.
基金funded by the Natural Science Foundation for Outstanding Young Scholars(No.41125018)
文摘Volatile organic compounds （VOCs） play ,an important role in ozone and secondary organic aerosol （SOA） formation, but VOCs sources during winter are not fully understood. To investigate VOCs sources during winter, mixing ratios of C2-C12 VOCs were measured at an urban site in Beijing from December 29, 2011 to January 17, 2012. Correlation analysis of toluene to benzene and i-pentane to n-pentane suggest that coal combustion could also be an important source for VOCs besides vehicular emissions. Source apportionment results show that coal combustion and vehicular emissions contributed 28%-39% and 31%-45% to ambient VOCs during winter, respectively. Backward trajectory analyses demonstrated that contributions from the burning of coal were higher when air masses came from southern regions outside Beijing. Close attention should be paid to VOCs emissions from coal combustion in Beijing city and the vicinity to the South.
基金Projects 2007B53 supported by the Foundation for National Excellent Doctoral Dissertation of ChinaBK2008123 by the Natural Science Foundation of Jiangsu Province
文摘In order to prevent spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines in China, we have analyzed the characteristics of spontaneous coal combustion and explain theoretically the factors affecting spontaneous coal combustion, such as rock bursts, high temperatures, high ventilation resistance, slow advancing speed and large obliquity mining. Key technologies to prevent spontaneous combustion occurring in sharply inclined seams in deep mines are pro- posed; these include pouring water, stopping leakage in upper and lower comers of the working face, choking off the goaf and cov- eting the coal. CO concentrations were controlled within two years to less than 15×10^-6 at the upper comer by applying these tech- nologies at the 1410 working face of the Huafeng coal mine. Our method has significant theoretical value and is of practical impor- tance in controlling spontaneous coal combustion occurring at a fully mechanized caving face with large obliquity in deep mines.
文摘The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary for numerical simulation of combustion process, the uneven radiation parameter can be calculated. A method to examine three-dimensional temperature distribution in blast furnace raceway was put forward by radiant image processing. The numeral temperature field matching the real combustion can be obtained by proposed numeric image processing technique.
基金financially supported by the National Natural Science Foundation of China (No. 41773117, 42007202)the National Key R&D Plan, Ministry of Science and Technology of China (Mechanism and chemical process characterization of atmospheric particulate matter multi-isotope fractionation) (No. 2017YFC0212703)+1 种基金the Shanghai Science and Technology Innovation Action Plan (No. 20dz1204011)the program of Institute of Eco-Chongming and ECNU Happiness Flower
文摘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 compositions.The 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 heating.The 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 city.Positive 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 total.Our 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.
基金Funded by the National Natural Science Foundation of China and Iron & Steel Unite Research Funds (50374085).
文摘In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional radiant energy in a blast furnace raceway, focusing on the correlativity of the numerical simulation of combustion processes with the connection of radiant images information and space temperature distribution. We calculated the uneven radiate characteristic parameterby taking radiant images as a kind of radiative boundary for numerical simulation of combustion processes, and put fonward a method to examine three-dimensional temperatures distribution in blast furnace raceway by radiant image processing. The numeral temperature fields matching the real combustion can be got by the numeric image processing technique.
基金supported by the National Natural Science Foundation of China (Grant Nos.40773047,40605033 and 40973071)the Shanghai Leading Academic Discipline Project (Grant No.S30109)the Earmarked Foundation of the State Key Laboratory of Organic Geochemistry (Grant No.OGL-200705)
文摘Emissions of volatile organic compounds （VOCs） and carbonyls from residential coal combustion of five coals with different maturities were studied in a simulated room.The coals were burned in form of honeycomb briquettes in a domestic coal stove,one of the most common fuel/stove combinations in China.Through a dilution system,VOCs and carbonyls samples were collected by canisters and silica-gel cartridges and analyzed by gas chromatography and mass spectrum （GC/MS） and high performance liquid chromatography/ultraviolet （HPLC/UV）,respectively.The results show that the bituminous coals with medium volatile matter content produce the highest emissions while the anthracite yields the lowest.Among the identified carbonyls from the coal smoke,the aromatic compounds （benzaldehyde,2,5-dimethylbenzaldehyde and p-tolualdehyde,m/o-tolualdehyde,benzene,m,p-xylene and trimethyl-benzene） were relatively abundant,which might be due to the molecular structure of the coal.For formaldehyde,aromatic carbonyls and aliphatic alkanes,their concentrations increase up to the maximum values and then decrease with increasing coal maturity.The total carbonyls and VOCs have the same tendency,which was observed for the emission factors of organic carbon （OC）,elemental carbon （EC）,particulate matter （PM） and polycyclic aromatic hydrocarbons （PAHs） detected in the series study.
基金This work was financially supported by the Joint Fund of the National Natural Science Foundation of China and the Baosteel Group Corporation （No. U 1660106）.
文摘NO emissions from coal combustion are receiving significant attention in recent years. As a solid waste generated from metallurgical industry, metallurgical dust （MD） contains a large amount of metal oxides, such as Fe2O3, CaO, SiO2 and Al2O3, as well as other rare metal oxides. The influence of MD on the NO emissions and the mechanism of the coal com- bustion systems were analyzed. The results show that the peak values of NO emission decrease with the increase in MD mass percent, and the curve of NO emission can be divided into two stages including rapid generation （400-600 ℃） and slow release （800-900 ℃）. The reduction of NO is significantly affected by temperature, volatile components, 02 and CO. CO has a significant catalytic action which can deoxidize NO to N2. The results obtained by X-ray diffraction and scanning electron microscopy indicate that multiple components in MD, such as FegTiO15, Fe2O3 and TiO2, can react with NO to produce TiN. Besides, the alkali metals in MD, such as Na, K and Ca, may catalyze NO precursor to inhibit NO emission. These results indicate that MD is cheap and highly efficient in controlling NO emissions during coal combustion processes.
基金supported by the Natural Science Foundation of China(No.41275135,41105090)the National High Technology Research and Development Program(863)of China(No.2012AA063506)the Open Foundation of Environmental Simulation and Pollution Control State Key Laboratories(Peking University)
文摘Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons （PAHs） are important in flue gas of the stove. By using dilution tunnel system, samples of both gaseous and particulate phases from domestic coal combustion were collected and 18 PAH species were analyzed by GC-MS. The average emission factors of total 18 PAH species was 171.73 mg/kg, ranging from 140.75 to 229.11 mg/kg for bituminous coals, while was 93.98 mg/kg, ranging from 58.48 to 129.47 mg/kg for anthracite coals. PAHs in gaseous phases occupied 95% of the total of PAHs emission of coal combustion. In particulate phase, 3-ring and 4- ring PAHs were the main components, accounting for 80% of the total particulate PAHs. The total toxicity potency evaluated by benzo[a]pyrene-equivalent carcinogenic power, sum of 7 carcinogenic PAH components and 2,3,7,8-tetrachlorodibenzodioxin had a similar tendency. And as a result, the toxic potential of bituminous coal was higher than that of anthracite coal. Efficient emission control should be conducted to reduce PAH emissions in order to protect ecosystem and human health.
基金Item Sponsored by National Basic Research Program of China(2012CB720401)National Key Technology Research and Development Program in 12th Five-Year Plan of China(2011BAC01B02)National Natural Science Foundation of China(51134008)
文摘The efficiency of coal combustion is an important factor for the blast furnace process.The influence of low xO/xC on coal combustion performance under nitrogen free blast furnace condition was researched through the self-developed pulverized coal burning device.The results show that the coal combustion rate reduces with xO/xC decreasing,and the combustion rate of bituminous coal is higher than that of anthracite.The coal combustion rate ascends with the rise of volatile matter,but when volatile matter of pulverized coal is more than 18%,the combustion rates will not increase correspondingly.Small amount of CaCO3 and CO2 additions can promote coal combustion,and the effect of CaCO3 is more apparent,which can increase the pulverized coal combustion rate by 15%-18% or so.
基金Supported by the National Natural Science Foundation of China (No. 50376068).
文摘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.
基金supported by the National Key R&D Program of China(2017YFB0603800 and 2017YFB0603802).
文摘The change of bubbles and the position of the tuyere in an oxygen coal combustion melting and separating furnace affect the flow and splash behavior of the molten pool.To analyze this problem further,a three-dimensional numerical simulation method was used to explore the behavior and change of the flow field inside the molten pool during double-row tuyere injection.In addition,the arrangement of the tuyere was changed for a more detailed understanding of the internal phase distribution and splashing in a molten pool.The results indicated that under three-dimensional numerical simulation conditions,bubbles rise after leaving the tuyere and break on the surface of the molten pool,which results in certain fluctuations in the nearby melt.During the injection process of the tuyere,the meteorological accumulation in the middle part of the molten pool formed part of the foam slag because of the influence of surface tension.When the layout of the upper and lower exhaust tuyeres was changed from staggered to symmetrical,or when the spacing of the upper and lower exhaust tuyeres changed,it had an effect on the phase distribution and splash behavior.
文摘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.
基金Supported by the National Natural Science Foundation of China (50606026,50736006)the Foundation of State Key Laboratory of Engines,Tianjin University (K-2010-07)
文摘Large-eddy simulation(LES) is under its rapid development and is recognized as a possible second generation of CFD methods used in engineering.Large-eddy simulation of two-phase flows and combustion is particularly important for engineering applications.Some investigators,including the present authors,give their review on LES of spray combustion in gas-turbine combustors and internal combustion engines.However,up to now only a few papers are related to the state-of-the-art on LES of gas-particle flows and combustion.In this paper a review of the advances in LES of complex gas-particle flows and coal combustion is presented.Different sub-grid scale(SGS) stress models and combustion models are described,some of the main results are summarized,and some research needs are discussed.
