汽车涂料生产环节VOCs的排放特征及安全评价

选择某汽车涂料的生产车间为研究对象,根据汽车涂料生产工艺的不同环节,在3个生产车间选定了8个采样点,用气质联用仪分析了汽车涂料车间内不同生产环节的挥发性有机物(volatile organic compounds,VOCs)的种类及浓度水平,并通过比较各种VOC的浓度与国家卫生部规定的工作场所有毒物质职业接触限值中短时接触容许浓度,对车间工人健康的影响进行了评价.结果表明,汽车涂料生产车间内共检测出15种主要的VOCs,包括苯、甲苯、乙苯、二甲苯、乙酸乙酯、乙酸丁酯、甲基异丁基酮、丙二醇甲醚醋酸酯、三甲苯、乙二醇丁醚等,其浓度检出范围为0.51~593.14 mg·m-3.生产车间各生产环节处TVOCs浓度显著不同,同一生产环节不同批次的气体样品中VOCs浓度也存在较大差异.二甲苯和乙酸丁酯是生产车间室内空气的主要VOCs.在生产高峰期部分VOCs浓度超过了工作场所有毒物质职业接触限值,需采取相应控制措施以保障工人健康.     

水中几种有机污染物的SPE-HPLC联用测定技术

酚类及硝基苯是水中一类重要的优先控制污染物。通过对固相萃取 (SPE)技术与高效液相色谱 (HPLC)联用技术的研究 ,得出对于含酚类及硝基苯的水样采用 2 0 0mg的键合硅胶C1 8柱在水样pH值为 3 .0和过柱水样为 40mL时可得到较好的萃取及测定结果 ,从而提出一种对水中酚类物质及硝基苯测定具有灵敏度高、准确性好的分析方法。     

乙醇汽油自燃温度及爆炸极限测试

为评估不同标号乙醇汽油(E10)的燃爆危险特性,补充完善乙醇汽油的技术指标,首次采用AIT551自燃温度测试仪和FRTA爆炸极限测试仪测试了E10的自燃温度和爆炸极限,并分析了温度对乙醇汽油爆炸极限的影响规律。结果表明:90号、93号、97号E10自燃温度分别为373℃、339℃、373℃,对应着火延迟时间为8 s、9 s、8s;90号、93号、97号E10的爆炸范围分别为1.223%~8.292%、1.343%~8.893%、1.294%~8.546%;温度从20℃升高至120℃,93号E10的爆炸范围从1.491%~8.765%变宽至1.318%~9.103%,即E10蒸气爆炸极限范围随温度升高而变宽;推导了测量E10蒸气爆炸极限时待测样品量预估计的公式。     

Relationship of traffic fatality rates to maximum state speed limits

Objectives: The objective of this study was to examine the safety effects of increases in U.S. state maximum speed limits during the period 1993–2013.

Methods: Poisson regression was used to model state-by-state annual traffic fatality rates per mile of travel as a function of time, the unemployment rate, the percentage of the driving age population that was younger than 25, per capita alcohol consumption, and the maximum posted speed limit on any road in the state. Separate analyses were conducted for all roads, interstates and freeways, and all other roads.

Results: A 5 mph increase in the maximum state speed limit was associated with an 8% increase in fatality rates on interstates and freeways and a 4% increase on other roads. In total, there were an estimated 33,000 more traffic fatalities during the years 1995–2013 than would have been expected if maximum speed limits had not increased. In 2013 alone, there were approximately 1,900 additional deaths—500 on interstates/freeways and 1,400 on other roads.

Conclusions: There is a definite trend of increased fatality risk when speed limits are raised. As roadway sections with higher speed limits have become more ubiquitous, the increase in fatality risk has extended beyond these roadways. The increase in risk has been so great that it has now largely offset the beneficial effects of some other traffic safety strategies. State policy makers should keep this trade-off in mind when considering proposals to raise speed limits.     

某型航空发动机振动环境统计

目的研究某型航空发动机振动应力测量数据PSD在整个频率带宽内不完全服从对数正态分布情况下的振动环境统计方法。方法在对数据进行对数正态分布检验的基础上,采用一种将正态容差限和非参数上限统计方法相结合的方法。结果该方法的振动环境统计结果介于传统单独采用正态容差限或非参数上限之间。结论对比结果表明,该方法用于确定航空发动机的振动环境条件合理可行。     

美国工业点源排放控制经验对中国的借鉴研究

文章分析了以排放限值为主要手段的美国工业水污染控制体系.美国工业水污染控制体系包括基于水质的排放限值和基于技术的排放限值,两者相辅相成,互为补充,不仅促使工业点源排放量不断降低,而且按照水质标准维护自然水体健康.在此基础上,文章提出了美国经验对中国水污染控制政策的三点启示:一是基于水质的排放限值与基于技术的排放限值分开设置,二是基于技术的排放限值始终保持先进性,三是重视统计学方法在排放限值制定中的应用.     

如何降低水中VOC分析的检测限

环境中挥发性有机污染物（ＶＯＣ）的存在很复杂,随着ＶＯＣ治理的进步,环境水中ＶＯＣ浓度有不断降低的趋势,要求ＶＯＣ分析具有更低的检测限。通过对环境水前处理过程采用优化吹扫捕集条件来扩大试样量,选择高灵敏度的检测器以及降低前处理过程的空白值,提纯分析用水;优化ＶＯＣ色谱分离条件,确保色谱峰良好分离来降低试样和空白值的标准偏差的研究,表明可以有效降低水中ＶＯＣ分析方法的检测限。     

生活生产类产品VOCs含量限值法规与标准研究

本文对国内生活生产类产品VOCs含量限值的国家标准、地方标准、行业标准以及中国香港、欧美等发达地区精细化的生活生产类产品VOCs含量限值法规和标准做了比较全面的综述,并从产品限值种类以及限值要求两个方面进行了对比研究和分析,提出了我国生产生活类产品VOCs 含量限值法规标准制定建议。笔者认为,应借鉴发达国家成功的生活生产类产品VOCs含量限值法规及标准制定经验,从做好标准和产品技术要求衔接、建立区域协同制定标准模式、结合经济因素或环境空气质量,分步推进相关标准制定和发布等方面入手,建立符合实际国情的产品种类较为全面、标准要求较高的生产生活类产品VOCs含量限值法规与标准体系,尤其是生活消费品方面,减少直接与人体接触的生活消费品VOCs排放。     

Effect of initial temperature on explosion characteristics of 2, 3, 3, 3–Tetrafluoropropene

The flammability of refrigerants is a major cause of refrigerant explosion incidents. Studying the explosion characteristics of refrigerants at different initial temperatures can provide significant benefits for solving the safety problems of refrigerants under actual working conditions. This paper studied the effects of the initial temperature and refrigerant concentration on the explosion characteristics of refrigerant 2, 3, 3, 3-tetrafluoropropene (R1234yf) at 0.1 MPa. The curves of explosion characteristics with different initial temperature revealed the same variation trend ranged from 25 °C to 115 °C. Specifically, as the refrigerant concentration was raised, the peak overpressure, the maximum rate of pressure rise, and laminar burning velocity increased initially and decreased afterwards, along with maximum values at the refrigerant concentration of 7.6%. When the refrigerant concentration was 7.6%, the peak overpressure declined exponentially with the initial temperature rise, while the maximum rate of pressure rise increased linearly. The laminar burning velocity calculated from the spherical expansion method indicated that the flame propagation was gradually accelerated by the increase of initial temperature, which coincided with the change of the maximum rate of pressure rise. Meanwhile, experiments and CHEMKIN simulation results demonstrated the effects of elevated temperature from 20 °C to 50 °C on the explosion limits of R1234yf. The lower explosion limit reduced and the upper explosion limit increased with rising initial temperature. In general, R1234yf exhibited moderate combustion and lower explosion risk, compared with traditional refrigerants.