Search

Gas explosions in obstructed vessels have been investigated for many years. However, the flame acceleration mechanism of enriched-hydrogen fuels with diluents in the piping system has received little systematic study in the literature. This particular study aimed to analyse the flame front mechanism of hydrogen-diluents/air explosion inside the pipe by considering the influence of tee junction distance from the ignition points. The tests were performed using H 2 /diluents-air at different concentrations and ignition positions, in two different tee junction pipe configurations. From the results, the worst case of explosion severity was found in 95% H 2 –2.5% Ar–2.5% N 2 /air for all ignition positions. In general, if ignition happened at the tee junction, the overpressure and rate of pressure rise profiles showed almost a similar trend on both configurations. Similar trend was also observed for the flame flow characteristic analysis. Overall, it was clearly demonstrated that a shorter distance between ignition point and obstacles resulted in higher explosion severity. [ABSTRACT FROM AUTHOR]

Based on recent developments, hydrogen-based combustion systems have received wide attention, mainly due to increasing awareness of enduring environmental pollutants and restricted access to fossil fuel usage. In the relevant literature, there are evidences of the possibilities on the partial or total replacement of hydrocarbon fuels with hydrogen in power plants and vehicle engines. However, some challenging issues particularly on hydrogen storage are remained to be resolved. This paper reviews and comments on addressing the effectiveness of hydrogen-enrichment on the engines and burners׳ performance includes the chemical kinetic analysis, the flame propagation structures and the effects of inhibitors on global burning velocity of hydrogen–hydrocarbon mixtures in different combustion bombs, chambers and vessels. It is recommended that future researches should aim towards the different application of hydrogen–hydrocarbon i.e. transportation and clean energy carrier. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising fuel for the future. In recent years it has been successfully utilised in industries, particularly in refineries and petrochemicals. In previous studies, the effect of inhibitors on hydrogen explosion behaviour has been investigated in different systems, yet only scarce data are available. Therefore, experimental study is carried out to investigate the effects of argon, nitrogen and carbon dioxide on hydrogen/air explosion in a branched pipe configuration. The fuel/air mixtures were ignited at three different ignition positions, A, B and D. The results show that, when ignited at the furthest distance (position A), the tee junction area is most vulnerable to the critical pressure impact of gas explosion. However, no similar trend was observed at the other ignition positions. In addition, mixtures with the compositions 95% H 2 –2.5% Ar–2.5% N 2 /air, 95% H 2 –5% N 2 /air, H 2 /air and 95% H 2 –5% Ar/air showed higher risks due to the higher diffusivity ratio and the associated rate of pressure rise. This phenomenon is highlighted in the discussion part of this paper. The results show that mixtures with CO 2 lead to lower severity than other compositions (∼50% reduction), as the average recorded maximum flame speed for this particular mixture was lower at all of the ignition points. This suggests that the effectiveness of the inhibitors should be in the order of Ar < N 2 < CO 2 . [ABSTRACT FROM AUTHOR]

One of the main cultural heritages associated with South-East Asian people’s way of life and economy is batik. Not only batik is a part of textile industries, playing an important role in industrial development, it also, like other wet textile processes, generates huge amounts of hazardous wastewater. Due to the presence of wax in the batik production process an efficient wastewater pre-treatment is necessary to appropriately prepare related effluent conditions for further conventional wastewater treatment. Accordingly, in this study, the application of a baffle separation tank to treat simulated batik effluent as an innovative wastewater pre-treatment method was investigated. Therefore, two sets of simulated batik wastewaters containing constant amounts of chemical components (wax, dye, and sodium silicate with different reactive dyes) were tested. In the next step, the removal efficiency of the discussed samples’ chemical components was calculated based on pre- and post-process analytical experiments during an hour-long pre-treatment run. Wax, sodium silicate, and reactive dye removal through the runs were in the ranges of 92–95, 32–42, and 2–5%, respectively. The results showed slight decreases in pH, COD, and conductivity values in the post-treated samples, the differences of which were within the ranges of 0.2–0.6, 52–107 mg/L and 9–27 μS/cm, respectively. Moreover, this technique presented an effective rate of reduction for effluent samples’ existing heavy metal concentration. [ABSTRACT FROM PUBLISHER]

Abstract: Nowadays, hydrogen is being utilized massively in industries as a clean fuel. Displacing of hydrogen due to unique chemical and physical properties has adversely affect on pipeline network, hence increases the potential risk of explosion. This study was carried out to determine the flame propagation of hydrogen/air and hydrogen–methane/air mixtures in pipeline. A 90° pipeline with L/D ratio of 40 was used. Pure hydrogen/air mixture with equivalence ratio, φ = 0.13, 0.17, 0.2, 0.24, 0.27 and 0.30 were used in this work. Different composition of hydrogen–methane–air mixtures were tested in this study i.e. 3%H2 + 97CH4, 4%H2 + 96CH4, 6%H2 + 94CH4 and 8%H2 + 92CH4. All mixtures were operated at ambient condition. The results show that bending is the critical part of pipeline and higher concentration of hydrogen can affect on maximum overpressure, flame speed and temperature rise of both pure hydrogen/air and methane-hydrogen/air mixtures. [Copyright &y& Elsevier]

Highlights • Structural equation modelling was engaged to test the reliability and validity of the relationship. • There are significant direct path of safety climate factors and risk estimate. • Priority to safety was the most important factor that affects the relationship. • There is no significant direct path of risk control measures and risk estimate. • There is no significant direct path of decision making attitude and risk estimate. Abstract Safety culture practices tend to strongly influence workers to control possible risk, make decision, and have a true perception on the risk despite the aim of encouraging safe work environment and reducing the numbers of human errors. The present study assessed the perceptions of the workers on nine safety culture practices as well as the individual risk estimate on the chemical and radiation hazard. In this study, a questionnaire survey was conducted among the workers of nuclear and radiation facilities in Malaysia. In this study, structural equation modelling (SEM) was utilised to analyse the relationship between the variables. The reliability and validity of the measured item was found to be acceptable. Meanwhile, the significant direct path of safety climate factors managed to be shown together with risk control measures, decision making attitude, and individual risk estimate. However, risk control measure and decision-making attitude did not mediate the relationship between safety climate factors and the risk estimate. On the other hand, priority to safety was identified as the most important factor that affects risk estimate, risk control measure, and decision-making attitude. This study also emphasized the requirement of communicative information which can be performed through information sharing, dissemination, and questioning mechanism. Overall, these findings manage to facilitate radiation stakeholders in developing the framework of safety culture practices as well as strengthening the safety management system. [ABSTRACT FROM AUTHOR]

A substantial amount of research has delved into the nature of safety climate, and subsequently its importance as a leading indicator of safety performance. However, they have mostly been conducted in Western countries via high risk operations. Therefore, this study is focused on the exploratory factors of safety culture practice in the industrial context of Malaysian radiation facilities, specifically by determining the influencing factors, their dependency and significant difference in mean level. This is attempted by adopting and adapting the six-factor Malaysian Safety Tool Kit (MSTK) and the components of safety culture practice as suggested by International Atomic Energy Agency (IAEA) safety series as the Malaysian nuclear and radiation safety tool kit (MRSTK). The exploratory factor analysis representing the MSTK model is therefore partially replicated and applied in the Malaysian nuclear and radiation sector. An alternative nine-factor model has been developed, which consisted of 32 items encompassing these elements accordingly: questioning attitude, communicative information, work environment, management commitment, communication, safety priority, personal view, involvement and prudent approach. The resulting outcomes have displayed statistically significant mean difference among these factors and consequently remained consistent with common safety climate themes. Nevertheless, they have also demonstrated the need to factor in individual response and organization cultural factors in the development of safety climate models intended for usage in Malaysian radiation sector. Furthermore, these findings have also revealed implications regarding the transferability of safety climate models and the type of safety interventions in implementing Occupational Health and Safety (OHS) management strategies more efficiently. [ABSTRACT FROM AUTHOR]