不同升温速率下模块装药的烤燃特性分析

目的 研究不同升温速率下模块装药烤燃特性的变化.方法 基于模块装药结构及其烤燃化学反应机理,提出基本假设,建立二维非稳态烤燃计算模型,通过数值模拟计算分析研究模块装药在不同工况下的烤燃特性.结果 在3.30、5.25、7.20 K/h的加热条件下,模块装药发生烤燃响应的着火温度分别为476.6、473.1、477.1 ...     

Accumulation and phytoavailability of benzo[a]pyrene in an acid sandy soil

Effects of benzo[a]pyrene (B[a]P) on ryegrass (Lolium perenne L.) growth, plant accumulation and dissipiation of B[a]P in a red sandy soil (Hapli-Udic Argosol) were studied in a pot experiment. The plants were grown for 61 days in soil spiked with B[a]P at 0, 12.5, 25 and 50 mg kg⁻¹. Control pots without plants were also set up. Soil extractable B[a]P, plant shoot and root biomass, and concentrations of B[a]P in plant shoots and roots were determined. Ryegrass biomass was increased by addition of B[a]P and root B[a]P concentrations were significantly correlated with B[a]P application rate, but no such correlation was found for shoot B[a]P concentrations. This indicates that B[a]P enhanced the growth of the ryegrass. The extractable B[a]P concentration in the planted soil was significantly lower than that in the unplanted control soil at the rate of 50 mg B[a]P kg⁻¹. This indicates that ryegrass may help to dissipate B[a]P in soil at concentrations over 50 mg kg⁻¹ soil although the mechanism for this is not understood.     

Methylmercury, total mercury and total selenium in four common freshwater fish species from Ya-Er Lake, China

Snakehead fish (Ophiocephalus argus cantor), silver carp (Hypophthalmichthys molitrtix), crucian carp (Carassius carassius), and common carp (Cyprinus carpio) are four common freshwater fish species in China. In this study, the level of methylmercury (MeHg), total mercury (T-Hg), and total selenium (T-Se) in muscle samples of these four fish species from Ya-Er Lake, China, were analyzed using atomic fluorescence spectrometry coupled with high-performance liquid chromatography, and inductively coupled plasma mass spectrometry. The concentrations of MeHg in all the fish species were significantly correlated with those of T-Hg. Higher T-Hg and MeHg concentrations had accumulated in the snakehead fish, which is a strongly predatory fish, than in the other three species. The concentration ratios of MeHg and T-Hg in the muscles of these four fish species were almost equal. Conversely, there was negative correlation between the concentrations of T-Hg and T-Se, which implies that there is a competition between these two elements with respect to bioaccumulation. It is noteworthy that of all the muscle samples tested, the level of T-Hg exceeded the maximum allowable limit in fish [0.4 mg kg⁻¹ (w/w) recommended by the World Health Organization] in 38.46% of those of the silver carp, 18.18% of those of the crucian carp, and 100% of those of snakehead fish. These results show that the consumption of contaminated fish is a potential threat to human health and that necessary preventive measures to safeguard public health should be emphasized.     

电解浮选用于活性污泥固液分离的研究

在装有Ti/RuO₂-IrO₂-TiO₂阳极、Ti阴极的电解浮选槽中进行了活性污泥固液分离的研究.考察了影响电解浮选性能的操作参数,这些参数包括水力停留时间、电流密度、进水SS浓度和进水pH值.研究表明,电解浮选是高效的固液分离单元,水力停留时间和电流密度是主要的影响因素.SS的去除率随着水力停留时间和电流密度的增加而增大;污泥负荷增加,SS的去除率下降;pH值影响电解产生微气泡的尺寸和污泥性质,但对SS的去除影响不大,实际应用中可以不调节pH值.进水SS约1 000mg/L时,当水力停留时间为20min,接触室电流密度为5 mA/cm²,分离区电流密度为2.5 mA/cm²,SS的去除率可达97%以上,此时的能耗为0.4～0.5(kW.h)/m³废水.电解浮选产生的浮渣含水率为95.9%,低于溶气气浮和二沉池的污泥含水率,对污泥减量化及其最终处置有较大的意义.     

重型柴油车车载排放实测与加载影响研究

采用车载排放测试仪,对2辆重型柴油卡车在空载和加载条件下进行实际道路车载排放测试.通过分析获得了油耗与排放速率的速度-加速度及其工况点的分布,发现高油耗与高排放工况点主要集中在高速加速区域,加载时油耗与排放高值随工况点分布更广;车辆在(30±2.5)km·h^-1等速及加速行驶时受加载影响最大,此时加载油耗与排放约是空载的1.6～3.2倍左右;由实测结果发现,卡车Ⅰ和卡车Ⅱ加载时油耗及CO、HC、NO_x排放因子分别是空载的1.6倍、3.5倍、1.1倍、1.5倍以及1.2倍、1.0倍、0.9倍和1.5倍,加载对油耗与NO_x排放影响最为明显,对HC影响最小,CO影响取决于车辆保养水平;卡车Ⅱ较卡车Ⅰ车型更大,发动机功率更高,相同荷载时受加载影响较小,说明重型车在发动机负荷可承受的范围内合理装载,有助于避免油耗与排放恶化,提高燃油经济性和排放水平.     

Reductive dechlorination of 1,2,4-trichlorobenzene with palladized nanoscale Fe(zero-valent) particles supported on chitosan and silica

In this study, nanoscale Pd-Fe particles, with diameters less than 100 nm, were synthesized and dispersed over the chitosan and silica supports. Three different Pd-Fe particles were synthesized, namely 0.1% Pd-Fe, 0.5% Pd-Fe and 1.0% Pd-Fe. SEM images confirmed that the Pd-Fe particles were dispersed over the surface of the supports while SEM-EDX confirmed evenly distribution of Pd over Fe(zero-valent). alpha-Fe(zero-valent) crystallites were identified by means of XRD and observed in TEM. Reductive dechlorinations of 1,2,4-trichlorobenzene (1,2,4-TCB) with the nanoscale Pd-Fe/chitosan and Pd-Fe/silica were carried out in the batch experiment system. Disappearance of the parent species and formation of the reaction intermediates and end product were monitored at discrete times. The results show that the nano-scale Pd-Fe particles were able to completely dechlorinate the chlorinated benzenes within a very short timescale. Complete dechlorinations of 1,2,4-TCB to benzene were achieved within 60 min with the 1.0% Pd-Fe/chitosan and within 100 min with the 1.0% Pd-Fe/silica. Reaction rates were observed to increase with increasing Pd content of the Pd-Fe/support. The reactions apparently followed pseudo-first-order kinetics with respect to the 1,2,4-TCB transformation. A kinetic model is constructed to fit the experimental results for the reactions, enabling identification of the major and minor dechlorination pathways of 1,2,4-TCB. The model suggests that the 1,2,4-TCB transformation mainly followed the primary pathway of direct reductive dechlorination to benzene and secondary pathway of sequential hydrogenolysis to 1,2-dichlorobenzene (1,2-DCB) and then chlorobenzene (CB) or benzene.     

煤燃烧过程中有机钙固氟效果研究

选择醋酸钙镁、醋酸钙2种有机钙为固氟剂,在固定床管式炉上对它们的固氟效果进行了初步研究,并分析了粒径、温度、钙硫比等对试验结果的影响.通过与传统固氟剂碳酸钙的固氟效果进行比较发现:在相同实验条件下,这2种有机钙具有良好的固氟效果,高温阶段效果更加明显,温度为1 000～1 100℃时,醋酸钙镁的固氟率是碳酸钙的1.68～1.74倍,醋酸钙的固氟率为碳酸钙的1.28～1.37倍.     

生物滴滤塔脱除污泥干化尾气中的SO2

以市政污泥干化尾气中的主要含硫物质二氧化硫(SO2)为处理对象,从市政污泥中筛选出高效脱硫菌——嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,A.f),搭建了实验室规模的生物滴滤塔,考察了进气质量浓度、气体停留时间、营养液喷淋密度和营养液中Fe2+浓度对生物滴滤塔脱除SO2的影响....     

山西省循环流化床粉煤灰环境风险评估及管控建议

为服务山西省循环流化床粉煤灰环境管理,本文在对全省循环流化床锅炉粉煤灰调查的基础上,选取典型粉煤灰开展了物理化学性质及污染物赋存及浸出特征研究,开展了不同暴露途径的环境风险评估,提出了环境风险管控建议.结果表明,循环流化床粉煤灰堆存对土壤和地下水无致癌风险,但具有一定的危害性,需强化堆存规范性、着力源头减量、拓宽综合利...     

连续起伏管道投产过程中的气相运移研究*

为应对山区液体管道在投产过程中可能出现的气阻、超压问题,从气相运移角度出发,建立液顶气模型,研究在1个U型单元内积气形成、压缩和破碎的全过程,在此基础上,提出连接各个U型单元的气相的传递函数,探讨背压累积因素下,连续起伏管道投产过程中各个U型管段的积气情况和压力的变化,进行动态的建模和计算。以国内某原油管道的现场投产数据与模型结果进行比对。结果表明:可以更加准确地预测山区液体管道投产过程中的气相传递和压力变化过程,能为未来连续起伏大落差液体管道投产的安全稳定运行提供理论指导和技术支持。