Effect Analysis of the Venting Direction on Explosion Pressure in LPG Pipelines.

In order to study the effect of the venting direction on explosion pressure in liquefied petroleum gas pipelines, explosion accident scenarios are experimentally tested and numerically simulated in a pipeline model with different explosion venting directions. In addition, the effect characteristic is analyzed through the pressure field varying with time and peak pressure varying with the distance. Results show that the pressure in the vertical branch decreases sharply, while the pressure in the horizontal branch does not show an obvious decrease with explosion venting of the vertical branch. However, the pressure decreases obviously in both branches with explosion venting of the horizontal branch, and the biggest reduction of peak pressure of monitoring points is 73.55% compared with that without venting. In addition, large areas of negative pressure appear in both branches with explosion venting of the vertical branch; however, a large area of negative pressure area appears in the horizontal branch with explosion venting of the horizontal branch. What is more, the arrival time of peak pressure in the main pipe of the explosion pipeline is significantly reduced with explosion venting, which is caused by the different generation ways of peak pressure. The effect analysis result of the venting direction on explosion pressure could aid the optimal layout design of LPG pipelines with the location of venting and important facilities as well as with the selection of negative-pressure-resistant material and higher-accuracy sensors.

Recovery of a freshwater wetland from chemical contamination after an oil spill.

In March 2009, a cargo ship spilled 250 tons of heavy fuel oil off the Queensland coast of Australia. The pristine National Park Moreton Island, seven nautical miles to the east of the spill site, was most affected by the oil slick. Contamination of the island's shoreline was widespread, with freshwater wetlands particularly slow to recover as clean-up needed to be carefully managed to avoid damage to this sensitive ecosystem. During the clean-up process on Moreton Island a monitoring program was initiated using traditional chemical analysis in combination with bioanalytical techniques to assess the extent and variability in contamination at sites on the shoreline and freshwater wetlands. Water accommodated fractions (WAF) of oil residues from samples taken directly after the spill on the shoreline showed the same level of toxic potency as samples from the wetland while baseline-toxicity equivalent concentrations (baseline-TEQ) and 2,3,7,8-tetrachlorodibenzodioxin equivalent concentrations (TCDDEQ) were much lower in oil collected from the sandy beach. The umuC assay for genotoxicity and the E-SCREEN assay for estrogenic effects indicated the extracts were not genotoxic or estrogenic. PAH concentrations and toxicity in grab water samples were below detectable levels, however, extracts from time integrated silicone passive samplers deployed for several weeks at the contaminated sites gave measurable responses in the bioassays with TCDDEQ levels increased relative to the control site. The low levels of baseline-TEQ and TCDDEQ present after 8 months had further decreased 6 months later indicating satisfactory recovery of this pristine ecosystem after an oil spill.

[Numerical analysis on pollutant decline in the emergency of water pollution in Three Gorges].

The water self-clarification ability in the reservoir area is much lower and the risk of the emergency of water pollution is more serious after the accomplishment of water storage in Three Gorges. This paper presented a hydrodynamic model for emergency of water pollution by the investigating the water states in Three Gorges, validated the veracity of the model by comparing flow velocity on the selected cross sections between the computed and measured data, and introduced numerical method to give visual show of the pollutant' s diffusion and to study the movement roles of pollutant after an accident. Further, analyzing the actual instance and characteristic, the decay process of pollutant was numerically simulated after controlling polluting source and taking decontaminating measure in river, and the effect of emergency measure was analyzed and discussed. It is more helpful for emergency to make a scientific decision in the respect of selecting control areas and methods after a pollution accident, putting forward a new way to effectively prevent and control water pollution.