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11.
Environmental Geochemistry and Health - Based on 1625 data collected from the published literature, the geochemistry of tin (Sn) in Chinese coals, including the abundance, distribution, modes of... 相似文献
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《International Journal of Greenhouse Gas Control》2007,1(1):31-36
The dry sorbent CO2 capture process is an advanced concept to efficiently remove CO2 from flue gas with two fluidized-bed reactors. This paper summarizes the results of performance of the two fluidized-bed reactors in the continuous solid circulation mode to investigate the feasibility of using potassium carbonate-based solid sorbent (Sorb KX35). The parameters such as gas velocity, solid circulation, carbonation temperature, and water vapor content were investigated during several continuous operations of two fluidized-bed reactors. The CO2 removal increased as gas velocity was decreased and as solid circulation rate was increased. The CO2 removal ranged from 26% to 73% was rather sensitive to the water vapor content among other parameters. A 20 h continuous operation conducted in a bench scale fast fluidized-bed reactor system indicated that the spray-dried potassium-based sorbent, Sorb KX35 having superior attrition resistance and high bulk density, had a promising CO2 removal capacity of 50–73% at steady state and was able to regenerate and reuse. The results from this work are good enough to prove the concept of the dry sorbent CO2 capture process to be one of viable methods for capturing CO2 from dilute flue gas of fossil fuel-fired power plants. 相似文献
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《Atmospheric environment (Oxford, England : 1994)》2007,41(24):5020-5030
The activity of the natural radionuclide tracers 7Be and 210Pb has been determined in bulk aerosol samples collected over 2-day intervals for nearly five full years at Summit, Greenland. Year-round sampling was conducted in three campaigns; summer 1997 to summer 1998, summer 2000 to summer 2002, and summer 2003 to present. As in previous summer campaigns at Summit, and a year-round investigation at Dye 3, variations in the activities of the tracers on short time scales were strongly correlated despite the upper troposphere/lower stratosphere source of 7Be and the continental surface source of 222Rn (precursor of 210Pb). This behavior is attributed to boundary layer dynamics exerting the dominant control on activities in air just above the ice sheet. Aerosols and associated species are depleted from the boundary layer above the snow when a strong inversion limits exchange with the free troposphere. Episodic weakening of the inversion allows ventilation of the boundary layer. This cycle drives simultaneous decreases and increases in the radionuclide tracers. The correlation between 7Be and 210Pb on seasonal and annual bases was found to be stronger than at Dye 3, and the average activity of 7Be was lower at Summit despite the higher elevation (3.0 versus 2.5 km). These observations indicate that the boundary layer at Summit is more effectively isolated than at Dye 3. The activity of 7Be at Summit peaked in June or July all 5 years, closely following the seasonality of stratospheric injection of 7Be into the Arctic troposphere (based on seasonality of the 10Be/7Be ratio previously measured at Alert, NWT). This suggests that when the boundary layer at Summit is replenished by ventilation, it receives air reflecting the composition of the mid and upper troposphere. 相似文献
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In China, the rapid development of the polyvinylchloride (PVC) industry will inevitably lead to various environmental problems. This paper studies the PVC metabolism further by (1) constructing dynamic models based on material flow analysis (MFA), (2) introducing calculation on detailed lifetime distribution of different types of products and recycling, and (3) obtaining the performances of waste emissions and accumulation as a function of raw material input and time. Based on system evolution theory and population development models, the developing trend of the PVC industry is studied, and annual consumptions in future years are predicted. The annual emission and accumulation after metabolism can be calculated by tracking the amount of raw material input, existing form and process flow for a single year (2003), as well as over a longer period (from 1958 to 2048) in China. Analysis indicates that over 0.6 billion tons of PVC waste will have accumulated in the environment by the end of 2050. In this scenario analysis, the effects of product structure, lifetime distribution, mechanical recycling, chemical recycling and incineration on waste output are all taken into consideration. The product metabolism process can be decelerated by changing these factors appropriately. However, mechanical recycling and chemical recycling are the most effective solutions. 相似文献
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《环境科学学报(英文版)》2023,35(4):483-493
When exposed to different relative humidities (RHs), the optical properties of atmospheric aerosols will change because of changes in the aerosol particle size and complex refractive index (RI), which will affect haze formation and global climate change. The potential contributions of ultrafine particles to the atmospheric optical characteristics and to haze spreading cannot be ignored because of their high particle number concentrations and strong diffusibility; measurement of the optical properties of wet ultrafine particles is thus highly important for environmental assessment. Therefore, a surface plasmon resonance microscopy with azimuthal rotation illumination (SPRM-ARI) system is designed to determine the RIs of single particle aerosols with diameters of less than 100 nm in the hygroscopic growth process. Measurements are taken using mixed single particles with different mass ratios. The RIs of mixed single aerosols at different RHs are retrieved by measuring the scattering light intensity using the SPRM-ARI system and almost all the RIs of the bicomponent particles with different mass ratios decrease with increasing water content under high RH conditions. Finally, for each of the bicomponent particles, the maximum standard deviations for the retrieved RI values are only , and , corresponding to the NaCl and NaNO3 bicomponent particles with a 3:1 mass ratio at 76.0% RH, the NaCl and glucose particles with a 1:3 mass ratio at 89.0% RH, and the NaCl and OA particles with a 1:1 mass ratio at 78.0% RH, respectively; these results indicate that the high-sensitivity SPRM-ARI system can measure the RI effectively and accurately. 相似文献
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Flame regime of gasoline-air mixture explosion is related to chemical reaction, turbulent flow and heat and mass transfer. Experimental data of gas velocity, pressure and flame temperature of gasoline-air mixture explosion in a tube at the equivalence ratio of 0.72, 1.00 and 1.28 were preliminarily acquired. Then, fluctuating velocities, overpressures, and burned and unburned gas temperatures at early stage (50 ms), intermediate stage (150 ms) and last stage (250 ms) in three explosions were determined through the analysis of the experimental data. Finally, the Damköhler number and Reynolds number of the early, intermediate and late stage were calculated respectively, and the flame regimes for each stage were estimated through the Damköhler number vs. Reynolds number diagram. Results show that all the flames at early, intermediate and late stage of the three explosions have the same regime of flamelets-in-eddies. The conclusions can provide some useful references for further study of the flame regime and the numerical analysis model selection of gasoline-air mixture explosion. 相似文献
19.
There is a clear difference between exiting data on the measured flammability limits of hydrogen-air mixture. The non-uniformity of concentration distribution of hydrogen in air is a contributor to deviations of the upper flammability limit (UFL) and the lower flammability limit (LFL) measured in different experiments. This paper presents a numerical model to simulate the gas mixing process from start to stability, to predict the concentration distribution, and to research the influence of concentration distribution of hydrogen in air on measured UFLs and LFLs. The commercial software package Fluent was used to carry out the numerical simulation for the concentration distribution of hydrogen in air in the vessels with length-to-diameter ratios (L: D) of 1:1, 3:1, 5:1 and 7:1 respectively. Based on the numerical simulation and analysis, the influence of concentration distribution on measured flammability limits was demonstrated for hydrogen in air in the vessel. It is found that the deviations of measured flammability limits of hydrogen in air are the minimum in the vessel with length-to-diameter ratio of 1:1, and augment with the augmentation of vessel length-to-diameter ratio. Moreover, it is presented that the deviations of measured flammability limits of hydrogen in the center of the vessel are lower than that in the top and the bottom. 相似文献
20.
The disaster scene in three-dimensional (3D) plays a crucial role in disaster emergency management and risk communication of oil transmission stations. However, existing research for the disaster scene mainly focuses on reproducing the disaster environment and rarely predicts the damage state of the disaster-affected object. This paper proposes an object-oriented modeling method that utilizes a multilevel decomposition pattern for disaster scenes. This method combines earthquake vulnerability assessment with 3D visualization technology to predict and characterize the damage state of critical infrastructure in oil transmission stations. To enhance earthquake risk perception, a simulation system is designed and developed, which allows for the construction of virtual scenes and quick simulation of disaster scenes in 3D. The case application shows that the system improves the 3D modeling efficiency of disaster scenes and enhances public awareness of earthquake risks. The simulation system can provide technical support for seismic mitigation planning and emergency management decision-making at oil transmission stations and has good application prospects. 相似文献