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151.
Zihong Xia Jian Li Tingting Wu Caixia Chen Xiaoke Zhang 《Waste management (New York, N.Y.)》2014,34(9):1609-1618
A CFD scheme was presented for modeling municipal solid waste (MSW) combustion in a moving-grate incinerator, including the in-bed burning of solid wastes, the out-of-bed burnout of gaseous volatiles, and the selective non-catalytic reduction (SNCR) process between urea (CO(NH2)2) and NOx. The in-bed calculations provided 2-D profiles of the gas–solid temperatures and the gas species concentrations along the bed length, which were then used as inlet conditions for the out-of-bed computations. The over-bed simulations provided the profiles of incident radiation heat flux on the top of bed. A 3-dimensional benchmark simulation was conducted with a 750 t/day commercial incinerator using the present coupling scheme incorporating with a reduced SNCR reduction mechanism. Numerical tests were performed to investigate the effects of operating parameters such as injection position, injection speed and the normalized stoichiometric ratio (NSR) on the SNCR performance. The simulation results showed that the distributions of gas velocity, temperature and NOx concentration were highly non-uniform, which made the injection position one of the most sensitive operating parameters influencing the SNCR performance of moving grate incinerators. The simulation results also showed that multi-layer injections were needed to meet the EU2000 standard, and a NSR 1.5 was suggested as a compromise of a satisfactory NOx reduction and reasonable NH3 slip rates. This work provided useful guides to the design and operation of SNCR process in moving-grate incinerators. 相似文献
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154.
有机污染物土地生物处理过程动态规律模拟研究 总被引:2,自引:0,他引:2
应用土壤颗粒内部有机污染物屏蔽理论,说明土地生物处理过程中残余有机污染物在土壤中的滞留现象,提出描述有机污染物在土壤及相连的水环境中生物降解过程的数学模型.其中,污染物的扩散过程用Fick第二扩散定律表示,可逆的吸附和解吸过程用线性吸附等温线表示,不可逆的土壤颗粒内部屏蔽过程用假一级反应动力学方程表示,生物降解过程用Monod动力学方程表示.模型计算结果与实验结果基本拟合,表示模型基本可靠.利用该数学模型,可以定量预测有机污染物进行土地生物处理所需的时间、处理的程度及动态规律. 相似文献
155.
环境中萘和甲基萘的气相色谱测定 总被引:3,自引:0,他引:3
针对发生的甲基萘油车泄漏事故进行了水样和空气样品中萘和甲基萘的测定,水样中直接进样,对空气样品则以甲醇为吸收液吸收,富集,氢火焰毛细管色谱法测定。 相似文献
156.
Industrial complexes may release dust emissions through several to up to tens of stacks, as well as via fugitive area sources. Several diffusion models for small-scale fugitive dust sources have been developed and combined with a point source model to form a series of models for industrial complexes. The applicable area of these models and the methods for obtaining the main parameters in the models have been tested and verified using measurement data gained from several field experiments. The models developed in this paper can give quite satisfactory results when compared to other current models. 相似文献
157.
物种敏感度分布法(SSD)在农药水质基准推导中的应用 总被引:2,自引:0,他引:2
水质基准推导方法在水质基准制定中起着至关重要的作用,物种敏感度分布法是目前国际上常用的基准推导方法,但利用此方法推导水质基准时,可选用的模型很多,但并不是所有的模型都能很好地拟合农药毒性数据集。为了筛选得到拟合优度较好的模型,选取4种典型农药,对采用不同模型拟合物种敏感度分布曲线的结果进行比较研究。结果显示,sigmoid、Gaussian、Gompertz和exponential growth 4种模型对于农药数据集,无论是在曲线走势、HC5值的合理性还是拟合优度方面的拟合效果都优于其他几种模型。因此,在应用物种敏感度分布法推导农药水质基准时,可以首选上述4种模型进行拟合,然后再从中选出最优模型来确定基准值,从而保证基准值推导的科学性。研究结果可为农药水质基准制定时推导方法的选择提供科学参考。 相似文献
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159.
研究了城市污水厂污泥好氧堆肥过程中的重金属钝化规律.由蘑菇渣、磷矿粉、鸡粪、高温菌种与城市污泥组成的试验堆体在微生物作用下快速干化.经过30天的好氧堆肥,试验堆体稳定态铬的比例达到了67~80%,稳定态铜的比例达到了31~41%,稳定态镍的比例达到了49~57%,稳定态锌的比例达到了46~55%,稳定态锰的比例达到了56~64%,污泥重金属的生物活性和毒性减少.生成的复合有机肥施用于园林绿化.图5,表2,参5. 相似文献
160.
Research on community characteristics of riparian herbs is an important scientific basis of riparian vegetation rehabilitation. This study aimed to investigate the species diversity and quantitative characteristics of riparian herbs in Liaohe River Conservation Area and its tributaries. Herbaceous communities were investigated by sample line method. Group average clustering analysis and detrended correspondence analysis (DCA) were used to find the major environmental factors affecting the distribution pattern of riparian herbaceous communities. The result showed altogether 154 herbaceous species, belonging to 40 families and 96 genera. The riparian herbaceous species diversity was found to be correlated to river slope, sinuosity and stream order, being lower in rivers of mountain area than in rivers of plain area, and higher in tributaries than in Liaohe River Conservation Area. Clustering analysis classified the herbaceous communities into 23 types, being dominated by hygrophytes including communities of Echinochloa crusgalli, Oenanthe javanica, Polygonum hydropiper, Murdannia keisak, Artemisia selengensis, Scirpus triqueter, Heleocharis soloniensis, Pycreus sanguinolentus, Cyperus fuscus, Phragmites australis, Polygonum amphibium, Carex diandra + Artemisia selengensis and Carex diandra + Rorippa islandica. Correlation analysis between DCA ordination axes and environmental factors showed that the altitude, river slope, sinuosity and stream level were the major environmental factors affecting the distribution pattern of herbaceous communities in the riparian zone of Liaohe River Conservation Area and its tributaries. The results of CCA showed that the contribution ratio of stream level was the highest, followed by altitude and slope, with sinuosity the last. The results suggested that riparian herbaceous characteristics are affected by the comprehensive force of altitude, river slope, sinuosity and stream order, and that Calamagrostis epigeios, Triarrhena sacchariflora and Phragmites australis are suitable species for riparian vegetation rehabilitation. 相似文献