Batch processes play a key role in producing low-volume and high-value-added products. In order to produce consistent, high-standard products and ensure process safety, real-time monitoring of batch processes is critical. To this end, the present work proposed a batch processes monitoring method based on the multiway principal polynomial component analysis (MPPCA). The MPPCA-based monitoring method is a nonlinear technique used to tackle the problem of process nonlinearity inherent in most batch processes. Thus, the MPPCA-based monitoring method is more suitable for nonlinear process applications than traditional linear methods such as principal component analysis (PCA)-based monitoring methods. Moreover, as compared to other nonlinear monitoring methods such as kernel-based methods, the MPPCA-based monitoring method has attractive features of invertibility, volume-preservation, and straightforward out-of-sample extension. The effectiveness of the proposed MPPCA-based monitoring method was validated through its application to a fed-batch penicillin fermentation process. The application results have demonstrated that the proposed MPPCA-based monitoring method is superior to the conventional multiway PCA (MPCA)-based monitoring method and the multiway kernel PCA (MKPCA)-based monitoring method in fault detection and diagnosis performance.
Many accidents have occurred in universities and the accident reports are accumulated in most universities. The information described in the accident reports must be used effectively to prevent a recurrence of the accidents. In this study, we applied text analytics to the description written in 373 accident reports in a university as a case study. Information mining method was adopted for the contents analysis, and 9 factors based on human error and m-SHEL, that is “slip”, “lapse”, “mistake”, “violation”, “software”, “hardware”, “environment”, “liveware”, and “management” were used for morphological analysis for description in report. The factors in each category (e.g. accident situation, generation) were extracted, and it is suggested that text analytics is one of the most effective methods to analyze the accident reports in universities.
Storage tank fires (such as pool fires) often occur in petrochemical tank farms. Flame pulsation is an important characteristic of turbulent flames observed in pool fires. Current solid flame models inadequately predict the thermal radiation of pool fires, particularly the effects of flame pulsation. The thermal buckling behavior and fire resistance of a fixed-roof Q345 steel tank with a stepped thickness under a neighboring ethanol pool fire based on a flame pulsation model was numerically investigated. The influence of smoke generated by the combustion process which can reduce thermal radiation fluxes was taken into account. Geometric and material nonlinear analysis was used on finite element analysis. Nonlinear analyses were solved using an explicit dynamic algorithm. Results showed that losing the load-carrying capacity in a circumferential direction at the most heated area triggers thermal buckling of the target tank and that the observed buckling behavior is non-linear, and the deformation shapes are diagonally symmetric. Fire resistance (in terms of critical time (tcr)) of the target tank depends on the vertical location of the fire (Hf). When Hf increases from 3.56 to 17.82 m, tcr rises from 900 to 2710 s. Fire resistance decreases exponentially as burning tank diameter (Df) increases. When Df increases from 10 to 30 m, tcr reduces by about half. The fire resistance for the cylinder-cone combined flame is larger than that for the cylindrical flame. The cylindrical flame underestimates fire resistance of the target tank when flame pulsation is accounted for.
Reaction calorimetry has been widespread applied for thermokinetic analysis of chemical reactions in the context of thermal process safety and process development. Mixing heat of reactants may lead to deviation of reaction heat measured by reaction calorimetry as it can't be separated from the reaction heat, especially for a solvent-free reaction mixture. This work is devoted to evaluating the influence of mixing heat on determination of thermokinetic parameters for the esterification of propionic anhydride with 2-butanol in the presence of sulfuric acid. To this aim, excess molar enthalpies of reactant solution were measured using a Mettler-Toledo EasyMax102 calorimetric reactor at 298 K and 0.1 MPa for the quaternary system which may occur during the esterification of propionic anhydride with 2-butanol (production of propanoic acid and 2-butyl propionate). A model for the excess molar enthalpies of the reaction mixtures as a function of the molar composition has been developed, which mainly based on Redlich–Kister equations and NRTL model. The model, which shows a good agreement with experimental data, then has been adopted for the evaluation of the mixing heat, which may lead to accurate kinetic parameters, through the correction of reaction enthalpy for esterification of propionic anhydride with 2-butanol in a batch reactor. Furthermore, corrected results of maximum temperature of the synthesis reaction (MTSR) were able to be acquired and be applied in safety assessment.
Some fire and explosion incidents in the workplace including large chemical plants have occurred intermittently since 2011 in Japan. It is pointed out that insufficient risk assessment has been implemented in using hazardous materials and chemical reaction of treating chemical substances understanding insufficiently them. Especially small and medium enterprises (SMEs) cannot often devote adequate resources toward implementing risk assessment. Thus, it is expected that the scenarios related to unintended reactions and the examples of risk reduction measures for these scenarios are provided for SMEs. One of solutions is considered to show some typical scenarios related to some critical events (runaway reactions, fire and explosion due to chemical incompatibility, explosion of self-reactive materials etc.) as support measures for implementing risk assessment considering unintended reactions. To investigate the typical scenarios and the risk reduction measures to prevent the progression of these scenarios, the scenarios related to unintended reactions were analyzed by developing bow tie diagrams because bow tie diagrams can be easily visible on the relationship between the causes of the events and the consequences of concern, and the measures preventing the progress of the scenarios.
The bow tie diagrams related to runaway reactions were developed by reference to the literature about the causes and consequences of runaway reactions. Moreover, the risk reduction measures to prevent the progression of these developed scenarios were investigate using the developed bow tie diagrams. Furthermore, the incident cases known about the detail of these incidents were traced using the developed bow tie diagrams to investigate the adequacy of these diagrams. The results from these investigations will be presented at the congress. It is expected that the developed bow tie diagrams are helpful for SMEs with limited resources to study the appropriate risk reduction measures to prevent the progression of these scenarios.
Fugitive emissions are unavoidable releases that occur continuously throughout a refinery or chemical plant wherever there are connections or seals between the process fluids and the external environment. Daily exposure to such emissions may pose a serious threat to the health of the workers. Previous work has been carried out focusing on assessing the occupational health risk in chemical plants by means of indexes such as the inherent occupational health index and the integrated inherent safety index. However, the indexes are only a good proxy indicator of the source of potential occupational hazards (i.e. chemicals, process conditions and process equipment). Based on the Source-Path-Receptor (SPR) model, the exposure and thus the eventual health risk also depend on the path and receptor. Also, in actual chemical plants, there are usually controls and mitigation measures put in place to control hazards and these can be referred to as protection layers (PL). Hence, in order to assess and evaluate the occupational health risk in chemical plants due to fugitive emissions, a more holistic methodology is required. Therefore, a hybrid framework for assessing this occupational health risk was developed by integrating the concepts of Layers of Protection, Hierarchy of Control and Source-Path-Receptor model. The generic protection layers identified were classified according to traditional hierarchy of controls. At the source, the protection layer identified were hazard elimination/substitution, inherently safer design and engineering controls. Next, along the exposure path, maintenance and equipment reliability were the identified protection layers. Finally, at the receptor, worker exposure is linked with management systems, procedures, safety behaviour and culture. Therefore, the proposed methodology can be also used for benchmarking and performance tracking of occupational health risk in a chemical plant over time, as the methodology includes the time-varying parameters of plant maintenance, management system compliance, safety behaviour and culture.
Household products such as dishwasher products and multipurpose cleaners may contain specific chemical ingredients to meet the consumer needs. However, some of the ingredients may result in skin and respiratory irritation. Thus, a systematic methodology to estimate the extent of hazard and risk for consumers' exposure to the products is needed. In this work, an index-based methodology is presented to estimate the severity of the hazards and risks of the ingredients during the early stage of product design. Besides, such methodology can be used as initial screening tool to reduce the hazards and risk of household products. Higher score was assigned to the higher potential of hazard and risk, and vice versa. The allocation of score can reveal the different level of severity of hazard and risk. With the score, the hazardous ingredient in the product formulation can be identified. The hazard potential was determined based on hazard classification by the Global Harmonised System (GHS), commonly found in material safety data sheet (MSDS). Risk assessment was performed by considering the Margin of Exposure (MOE) and Risk Characterization Ratio (RCR). The no-observed-adverse-effect level (NOAEL) of chemical ingredients is used to derive the MOE. Meanwhile, RCR is calculated by comparing the value of derived no effect level (DNELs) to the estimated exposure concentration. To demonstrate the proposed methodology, the dermal and inhalation hazards as well as risks from ingredients used in formulation of liquid detergent were evaluated.
Process accidents are also partly caused by technical skill based on insufficient process safety information (PSI) and inappropriate non-technical skill. The causes were for example, “I didn't know it was used differently than when it was designed”, “The heat of reaction formation of the dimer was too large.” There were troubles that could be prevented at the design stage and gradually shifted from the original idea in daily operation. Engineers should make appropriate decisions by utilizing the PSI that has been accumulated by understanding everything from design to operation. Five abilities to operate PSI are defined; information collection ability, information creation ability, information sharing ability, information utilization ability and information update ability. For next use we need to update the information if it is necessary to correct the information after use. It is necessary to store information that has been updated. Wire Mesh Protection Model is modeled to explain the mechanism to prevent accidents by using PSI.The protection layers consists of two layers, technical skill (TS) and non-technical skill (NTS). If insufficient management of TS and NTS, two layers allows hazards to occur accident. Well-operated NTS leads the inner layer to prevent any accident. It is important to consider utilizing PSI to make workplace safe. Accidents can be suppressed by strengthening both layers. An operational support system based on NTS is proposed and conceptual diagram that NTS work at each event. The formal knowledge that is the subject of PSI will be complemented by unconsciousness gained from experience and the five senses and implicit knowledge that is difficult to verbalize. It will find new added value in forming PSI in Japan.
This paper shares information on developing process safety management (PSM) system for refineries and activities toward the implementation of the system for process safety enhancement.
In chemical process industry, a lot of serious accidents have been experienced like vapor cloud explosion (VCE), boiling liquid expanding vapor explosion (BLEVE), boil over, poisonous gas expansion and so forth. Once it occurs, workforces in the plant will be seriously injured. Furthermore, neighbors and local community will be suffered blast wave, radiant heat etc. Company revenue and reputations will be also impacted.
In our refineries, HAZOP, LOPA and management of change (MOC) have been widely applied to identify and manage process safety risks, however, it is also of great importance to identify some other risks which cannot be captured through the methods above. PSM is widely credited in the industry for reductions in major accident risk in a comprehensive and systematic way. This presentation shares our journey toward the development of PSM system and some examples of the key activities to implement the core elements of the PSM system: hazard identification and risk analysis etc.
Process safety of a chemical plant should be managed consistently throughout the plant life cycle. In order to consistently manage process safety, it is necessary to explicitly express the whole business process framework of process safety management. Therefore, we have developed a business process model as a framework. Based on the developed model, the constraints of each activity, the position of the activity can be found. Activities to assess the impact of change are heavily burdened, especially if the rationale of previous decisions is not available, particularly for change management. To reduce the burden, the rationale for any decision-making should be preserved for use in future activities. The saved rationale should be formatted for easy use in future activities. Therefore, we proposed a support system framework for smart management of change based on business process model. The system automatically generates a checklist when the rationale for decision making is proposed.
The U.S. Chemical Safety Board (CSB), an independent, non–regulatory federal agency that investigates the root causes of major chemical incidents, has firstly analyzed safety culture as an important element to maintain process safety in the investigation report of “BP America Refinery Explosion” in 2007. On the same year, the Center for Chemical Process Safety (CCPS) published Risk Based Process Safety (RBPS) in which process safety culture was newly added as an element.
The author found following six CSB reports which analyzed and found weaknesses of safety culture, and discussed their relations with essential features of process safety culture in RBPS.
1. BP America Refinery Explosion 2007
–Lack of reporting and learning culture
–Focus on personal safety rather than process safety
–Organizational changes and budget cuts
2. Tesoro Refinery Fatal Explosion and Fire 2014
–Management had normalized hazardous conditions
–Safety culture required proof of danger
3. Chevron Refinery Fire 2015
–Decision to operate despite hazardous leaks several times
–Reluctance to use Stop Work Authority
–Increased problems in equipment maintenance
4. Macondo Blowout and Explosion 2016
(No new findings)
5. Tesoro Martinez Sulfuric Acid Spill 2016
–Failure to learn from past incidents
–Weak management commitment to worker safety
6. Williams Olefins Plant Explosion and Fire 2016
–Deficiencies in and poor implementation of the process safety management system
Weaknesses underlined correspond to the essential features in the principle “maintain a dependable practice” in RBPS. Five reports contain weaknesses of this type, which suggests that these sites need to acquire dependable practices to develop and implement a sound culture. Repeated past incidents clearly show the normalization of deviance. Though the reports including analysis of safety culture are still limited, approaches to analyze safety culture are being accumulated.
Most of PETRONAS Operating Plant Units (OPU) are classified as a Hazardous Installation due to handling of the large inventories of flammable, explosive and toxic substances at site. The quantities of hazardous materials are estimated to be above the specified threshold values, taken from the Occupational Safety and Health Act 1994, Control of Industrial Major Accident Hazards (CIMAH) Regulations, 1996.
The Safety Report demonstrate to the Department of Occupational Safety and Health (DOSH) that OPU has applied strict measures to manage Major Accident Hazards as an operator of all hazardous facilities.
The Major Accident Hazard (MAH) and its mitigation through Safety Critical Element (SCE) Management Process forms a major part of the PETRONAS Risk Management Process.
This is implemented to provide a safer operating environment for people, maximizing the understanding of the risks inherently involved in the extraction of hydrocarbons, and minimizing the exposure of personnel to these risks.
Major Accident Hazards are established from a Hazard Identification Study (HAZID) as well as Hazard and Operability Study (HAZOP). SCEs are identified from analysing those Hazards, and constitute the means required to manage the associated risks.
The SCE Management process has four main stages:
• Identification of Major Accident Hazards;
• Identification of Safety Critical Elements, involved in managing Major Accident Hazards
• Identification of Performance Standards, and Assurance processes that ensure the continued suitability of the Safety Critical Elements
• Verification that all stages have been undertaken; that non-conformances are being identified, controlled and closed-out; and thus that Major Accident Hazards are being controlled.
Through the diligent application of these stages, it is possible to meet the requirements for MAH and SCE Management Process giving a better way of controlling risk by PETRONAS.