查看更多>>摘要：Refineries are highly complex installations and a potential source of major hazards. Due to the large volumes of flammable and toxic substances present, an accident in a refinery may have multidimensional consequences. This includes severe property damages, injuries to personnel, toxic releases of chemicals causing adverse health effects on nearby residents and the environment, and large business interruption losses that may lead to company bankruptcy. This paper looks at the risk profile of refineries from an insurers’ perspective. A top down approach is employed to derive key performance indicators (KPIs) for two types of events historically known as main causes of major accidents in refineries, i.e. fire and vapor cloud explosion. Bayesian Belief Networks (BBNs) are used to develop a probabilistic model for quantifying risk indication of refineries for fire and explosion events via a structured approach to elicit and synthesize available knowledge from domain experts. Three types of KPIs are modelled as BBN nodes: quantitative, qualitative and directional indicators linked to technical, human and change trend factors, respectively. The approach proposed has a twofold practical use: i) to support insurers to assess which plants have low potential risk exposures; and ii) to inform the refineries about their own risk profile, thus supporting them with the assessment and the implementation of risk reduction measures. To ensure applicability across the industry, the systematic development of the BBN is detailed and extension via the inclusion of modules accounting for further KPIs is discussed.
查看更多>>摘要：Multivariable process monitoring (MPM) algorithms are very popular for early detection of abnormalities and diagnosis of process conditions to ensure plant safety, reliability, and production quality during operation. Hazard and operability (HAZOP) study is a systematic brainstorming session to identify the credible causes and consequences of the process upsets. Then the process safeguards in place are reviewed to evaluate risk of HAZOP scenarios. According to IEC61882 HAZOP studies have proved to be very useful in a variety of different process industries. However, the method has some limitations to be considered in potential applications and particularly for complex processes. This paper aims at improving the HAZOP study by applying MPM algorithms to perform a holistic and more accurate consequence analysis and effective evaluation of the process safeguarding strategy. The proposed monitoring algorithm consists of two layers of decision boundaries. The 1st layer is based on normal operating condition and the 2nd layer (i.e. suggested in this paper) is based on safe operating condition of plant. The effectiveness of the proposed method is verified by investigations on an operating complex polymerization plant.
查看更多>>摘要：This work is aimed at investigating the lower flammability limits (LFLs) of ethanol, acetone, and ethyl acetate vapor mixtures in air with various mole fractions. The LFLs were measured by a self-made experimental apparatus. Besides, a theoretical calculation model of LFL based on adiabatic constant pressure was established. The heat release, adiabatic flame temperature and the sensitivity of mass burning rate on LFL are analyzed. The results indicated that as the mole fraction of a single substance in a binary mixture or a ternary mixture increases, the LFL changes monotonically. The calculated LFLs are in good agreement with the experiment. The maximum absolute deviation and relative deviation are 0.2% and 6.47% respectively. The trends of heat release and adiabatic flame temperature (AFT) are consistent, meanwhile, the trends of LFL are opposite to them. Besides, the trend of the total peak of heat release rate at LFL is consistent with the heat release. H + O2 < = > O + OH mainly reduces the heat release rate, and CH3 + O < = > CH2O + H mainly increases the heat release rate. The sensitivity coefficients of the maximum main chain branching reaction H + O2 < = > O + OH and the main termination reaction H + O2 (+M) < = > HO2 (+M) of the mass burning rate at the LFL are almost the same.
NSTL
Elsevier