Gas freeing process in crude oil tanker ships is widely recognized one of the most hazardous aspects of shipboard operations. Although the process provides practical benefits to ship by removing the explosive or poisonous gases from the cargo tanks and raising the oxygen level up to 21 percent, the consequences of failure may cause serious damage to human health, marine environment and cargo. Therefore, the crew exercise utmost care and become aware of the potential hazards in gas freeing process. In this context, this paper provides a fuzzy DEMATEL (Decision Making Trial and Evaluation Laboratory) method to evaluate critical operational hazards in gas freeing process. While the DEMATEL method enables to identify and analyse the potential hazards of gas freeing process with respect to causal–effect relation diagram, fuzzy sets deal with the uncertainty in decision-making and human judgements through the DEMATEL. Thus, the hybrid approach provides smart solution for safety practitioners to prevent critical hazards in gas freeing process. The results of the research will contribute to maritime safety at sea and prevention of environment pollution as well as loss of life on-board crude oil tankers ships. 相似文献
Trace amounts of organophosphorus pesticides (OPs) were determined in various fruits by headspace solid phase microextraction (HS-SPME) and gas chromatography–nitrogen phosphorous detection (GC-NPD). Sampling from the headspace enhanced method selectivity, whereas at the same time improved fiber life time and method sensitivity. Diazinon, parathion, methyl parathion, malathion and fenithrothion were determined in various fruits: more than 150 samples of 21 types of fruits were studied. SPME-GC-NPD provided a useful and very efficient analytical tool: method linearity ranged from 1.2 to 700 ng/ml. Limits of detection (LODs) and quantitation (LOQs) ranged from 0.03 to 3 ng/ml and 0.12 to 10 ng/ml respectively, values well below the residue limits set by the EU. Less than 2% of the samples were found positive containing amounts higher than the EU limits. The effect of fruit peeling and washing was also investigated. 相似文献
While coal seam is being mined, an annular fissure circle with gas accumulation will be formed in the fissure zone as a result of desorption, dissipation and permeation of gas in the goaf area and overlying strata due to fissures from rock caving and mitigation in the roof. The methods for computation of spatial locations of the fissure circle are researched in this paper. Based on these methods, gas drainage technique for the fissure zone is optimized. By applying drill hole returning water method of variables, the height of caving zone that most affects the drainage effects of inclined high dip drill hole was measured on the site. Due to the consistency of the expected height with the computed height of caving lines at different positions, the correctness of the theoretical computation method is further validated. Meanwhile, the parameters of the inclined high dip drill hole at #3311 working face of Hexi Coal Mine are determined by a case study. 相似文献
Gas emission rate from borehole is one of the most important indexes for the coal and gas outburst prediction. The mathematical model of gas flow in the coal seam, gas flow into the measuring chamber, gas pressure change in the measuring chamber, and gas flow out of the chamber through the pipe is established. Gas migration in the coal seam, gas pressure in borehole chamber and gas flow in pipe is simulated using the finite difference method. Gas emission rate is obtained under dynamic boundary conditions. The influence of gas storage parameters on gas emission rate from borehole is analyzed. Results show that: the gas pressure and the permeability coefficient have great impacts on the value of gas flow quantity in borehole. The larger the original gas pressure of coal seam and the permeability coefficient of coal seam are, the greater the maximum value of gas emission rate form borehole and the later the maximum appears. 相似文献
Human urge of exploiting earth resources has resulted into unprecedented industrial development in the last century resulting into production of large quantities of hazardous chemicals. Chemical, petrochemical, nuclear, biomedical and pharmaceutical industrial accidents release large quantities of hazardous chemicals into the atmosphere. The accidental discharge during production or storage or transportation have subjected the population to be exposed to exceptionally high concentration levels of hazardous chemicals, taking them by surprise, unprepared with fatal consequences. An emergency planning organization has to be trained to combat this situation in the shortest possible time to minimize the number of causalities. The present paper focuses on computation of dispersion model, using emission source, accident location and online metrological data near to the sources, to provide necessary and accurate results swiftly. The predicted ground level concentrations with the hazardous nature of the chemical, speed and direction of plume, the emergency team will be supplied with all the information in graphical easy to grasp form, superimposed over a GIS map or the latest satellite image of the area.
The emergency team has to be trained for all past scenarios and their preparedness, response and actions must be practiced regularly to be able to abate chemical releases accidentally or intentionally.
Accidental releases of chlorine and ammonia gases in residential and industrial areas are simulated. The predicted ground level concentrations in the effected areas are shown after different time intervals. For low vapor pressure chemical, the dispersion time is large and concentration levels are low but persist for prolonged time while for volatile chemical, the concentrations are high in short time and recovering to safe environment is quick. 相似文献
The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving
the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate in a brackish marsh at Rockefeller
Wildlife Refuge in southwestern Louisiana was remediated through the use of in situ burning. An assessment of vegetation recovery
was initiated in three treatment marshes: (1) oil-impacted and burned, (2) oil impacted and unburned, and (3) a nonoiled unburned
reference. We compared percent cover, stem density, and biomass in the treatment marshes to define ecological recovery of
the marsh vegetation and soil hydrocarbon content to determine the efficacy of in situ burning as a cleanup technique. Burning
led to a rapid decrease in soil hydrocarbon concentrations in the impacted-and-burned marsh to background levels by the end
of the first growing season. Although a management fire accidentally burned the oil-impacted-and-unburned and reference marshes
in December 1995, stem density, live biomass, and total percent cover values in the oil-impacted-and-burned marsh were equivalent
to those in the other treatment marshes after three years. In addition, plant community composition within the oil-impacted-and-burned
marsh was similar to the codominant mix of the grasses Distichlis spicata (salt grass) and Spartina patens (wire grass) characteristic of the surrounding marsh after the same time period. Rapid recovery of the oil-impacted-and-unburned
marsh was likely due to lower initial hydrocarbon exposure. Water levels inundating the soil surface of this grass-dominated
marsh and the timing of the in situ burn early in the growing season were important factors contributing to the rapid recovery
of this wetland. The results of this in situ burn evaluation support the conclusion that burning, under the proper conditions,
can be relied upon as an effective cleanup response to hydrocarbon spills in herbaceous wetlands. 相似文献