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591.
池火灾热辐射计算及模拟 总被引:2,自引:0,他引:2
在油罐火灾中,着火罐所释放的热辐射对附近的人员以及设备造成一定的危害,分别采用经验公式以及FDS模拟来计算热辐射强度,并对计算结果进行比较及分析,结果表明两种方法可互相补充完善。 相似文献
592.
孙集平 《辽宁城乡环境科技》2009,(4):38-40
对沈阳市目前运行的7座污水处理厂及污水特征参数进行了论述和推算,以北部污水处理厂为例,结合沈阳城市污水源热泵系统规划,通过调查分析供暖企业的燃煤现状及供暖情况,推算出了采用污水供暖取代燃煤供暖后的环境效益和经济效益,并对沈阳建立污水源热泵系统面临的问题提出了对策和建议。 相似文献
593.
浸入式超滤膜工艺稳定运行影响因素研究 总被引:5,自引:1,他引:4
以确定浸入式超滤膜工艺稳定运行工况为目标,进行了混凝.浸入式超滤膜工艺处理滦河原水的中试研究.采用横跨膜压差(TMP)做为表征膜稳定运行的工艺参数,考察了膜通量、制水周期、原水水质条件的改变对膜工艺的影响.结果表明,采用浸入式膜处理滦河水时,膜通量为53.3 L/(m2·h)且制水周期为30 min时膜工艺运行稳定,能较好控制膜污染;水温变化对膜工艺运行影响较大,低温期单个过滤周期TMP比高藻期增加了76%;EFM和化学清洗结合是一种有效地控制膜污染、强化稳定运行的措施. 相似文献
594.
A.M.G. de Bruijn K. Butterbach-Bahl S. Blagodatsky R. Grote 《Agriculture, ecosystems & environment》2009,133(3-4):196
N2O emissions from soil contribute significantly to global warming. Pulse emissions of N2O from soils during freeze-thawing were recently recognized as important atmospheric sources. In this modelling study we explore three different hypotheses for explaining freeze–thaw related N2O emissions: (1) soil frost or snow cover may reduce gas diffusion and create anaerobic conditions that stimulate N2O production via denitrification, (2) microbes that die of frost deliver easy decomposable organic carbon and nitrogen to the soil, which stimulates microbial growth and vigorous N2O production during freeze–thaw, and (3) the enzyme nitrous oxide reductase, which is responsible for the reduction of N2O to N2 during denitrification, is more sensitive to low temperatures than other enzymes, so that N2O becomes the dominating end-product of denitrification at low temperatures. These hypotheses were tested with a biogeochemical model that combines hydrology and physics calculations with a newly developed, parameter-poor biochemistry module. The model was first calibrated with field datasets on soil–atmosphere fluxes of N2O, NO and CO2 and soil NO3 and NH4 concentrations that were measured in a spruce forest in Southeast Germany in the years 1994–1997. Subsequently, additional model mechanisms were implemented that allow the model to describe the outlined mechanisms potentially driving freeze–thaw N2O fluxes. After each implementation the model was recalibrated. We were able to mimic dimension and timing of high N2O emissions when either one of the first two hypotheses were assumed, but found no confirmation for the third. The best model fit was achieved by combining hypothesis one and two, indicating that freeze–thaw N2O emissions are not mono-causal. 相似文献
595.
The UF membrane with molecular weight cuto (MWCO) ranging from 2 to 100 kDa and XAD-8 resin were employed to identify
the characteristic of molecular weight (MW) distribution of wastewater e uent organic matter (EfOM) in terms of TOC and UV254,
as well as the amounts of the hydrophilic/hydrophobic organic fractions in di erent MW ranges. Then, the nanofiltration (NF)
membrane fouling experiments were carried out using the above fractionated water to investigate the e ect of MW distribution and
hydrophilic/hydrophobic characteristics of EfOM on the membrane flux decline using the fractionated water samples. The experimental
results have shown that 45.61% of the total organics belongs to the low MW one, among which the percentage of the hydrophilic
organics with low MW (less than 2 kDa) was up to 28.07%, while that of the hydrophobic organics was 17.54%. In particular,
the hydrophilic fraction was found to be the most abundant fraction in the e uents. MW distribution has a significant e ect on the
membrane fouling. When the MWwas less than 30 kDa, the lower the MW, the larger was the specific flux decline, while in the case of
MW higher than 30 kDa, the higher the MW, the larger was the specific flux decline, and the decline degree of low MW organics was
larger than the high MW one. With the same MW distribution range, specific flux decline of the hydrophilic organic was considerably
slower than that of the hydrophobic organic, which indicated that the hydrophobic organic fractions dominantly contribute to the flux
decline. 相似文献
596.
597.
598.
Although the effects of jet fires are often limited to rather short distances, if their flames impinge on a pipe or a vessel collapse can occur in very short times. In such cases, the heat flux on the affected equipment is very high and wall temperature can increase very rapidly. This can happen in parallel pipelines, if a release occurs and impinges on another one. Nevertheless, jet fire impingement has been scarcely studied. In this communication the results obtained from an experimental set-up are presented. Sonic jet fires impinged on a pipe containing stagnant air or water. The temperatures of the flames impinging on it were measured for the worst case (flame front-bright zone), as well as the evolution with time of the pipe wall temperature at different locations. Initial temperature increases up to around twenty °C/s were registered for the air inside, with maximum values of up to 600 °C reached in 2.5 min, and 800 °C in approximately 9 min. In the case of pipe containing water, in the zone of the wall in contact with the liquid the heating rates were much lower, the maximum temperature reached being up to approximately 150 °C. From the temperatures of the jet flames and of the pipe, the heat fluxes reaching the pipe and the corresponding heat transfer coefficients were obtained. The results obtained emphasized that safe distances are essential in pipelines, together with fire proofing and other safety measures. 相似文献
599.
为提高煤田火区温室气体通量测量的准确性,科学制定温室气区减排措施,笔者对国内外煤田火区温室气体测量方法进行梳理,对比分析各种测量方法的原理、优缺点和适用范围等,提出测量方法存在的问题及以后的研究方向。研究表明:目前所用的测量方法存在测量精度低、连续性差、假设理想化等缺陷,检测设备的改进应朝着能适应当地地表高温环境并能实现连续监测的方向发展,测量方法应更注重和新技术的结合。 相似文献
600.
为研究不同添加剂对聚氨酯泡沫材料阻燃性能的影响,对磷酸、硼酸、杨梅单宁阻燃剂3种添加剂处理后的聚氨酯泡沫材料与标准样分别测定氧指数、热值、烟密度等级和热稳定性,并以层次分析法评价阻燃性能优劣。结果表明:4种材料PUF STD、PUF PA、PUF BA、PUF FR的OI、CV依次分别为34.71%、38.59%、35.88%、37.86%,17.4023、16.7037、15.3197、15.0397kJ/g,燃烧时均少烟,热稳定性排序为:TS PA>TS STD>TS FR>TS BA;采用层次分析法分析3种添加剂对聚氨酯泡沫材料阻燃性能的影响顺序由优到劣为:PUF PA>PUF FR>PUF BA>PUF STD。该结论可为聚氨酯材料阻燃添加剂的选择提供参考方向。 相似文献