Computer Aided HAZOP Study Implementation Bottlenecks in Chemical Industry

With modularization of modern process plants, an acceleration in design and engineering is achieved. This development also affects the safety assessment and changes the workflow. Compared to conventional process plants this is expressed especially in regards to store and exchange safety related information between manufacturer and owner/operator. Current risk-assessment techniques fall short to support the advantages of modular process design and production due to the lack of flexibility, as well as missing methods for transformation and transportation of information. To compensate this, current models of safety analysis methods, especially HAZOP (Hazard and Operability) studies, are analyzed and extended. Focus of the analysis is the reuse and integration of previous knowledge similar to the method of the modularization. This research presents a workflow to close the gaps of current risk analysis to meet the changing requirements of modularization. This is done by creating an interface for connecting different HAZOP studies. The specifications are represented in an information model. The concepts of the workflow have been shown on exemplary HAZOP studies.

HAZOP (HAZard and OPerability) studies are carried out to analyse complex automated systems, especially large and distributed automated systems. The aim is to systematically assess the automated system regarding possibly negative effects of deviations from standard operation on safety and performance. Today, HAZOP studies require significant manual effort and tedious work of several costly experts. The authors of this paper propose a knowledge-based approach to support the HAZOP analysis and to reduce the required manual effort. The main ideas are (1) to incorporate knowledge about typical problems in automation systems, in combination with their causes and their effects, in a rule base, and (2) to apply this rule base by means of a rule engine on the description of the automated system under consideration. This yields a list of possible dangers regarding safety risks and performance reductions. These results can be used by the automation experts to improve the system's design. Within this paper, the general approach is presented, and an example application is dealt with where the system design is given in the form of a UML class diagram, and the HAZOP study is focused on hazards caused by faulty communication within the distributed system.

Hazard and Operability (HAZOP) techniques the best step for identification and analyzing the hazard and operational issues of the system. It is very organized, methodical and structured process to identify hazards of any system or process from the initiating stage till decommissioning of the project. Technology and system possess exposure to undesired events because system can fail or improper work resulting in injury, damage and deaths. Our lives are dealing with a web of different systems, each of which can affect our safety. Each of these systems contains inherent hazard that present unique risk. The major concerned is about eliminating and reducing risk which leads to undesired events. The overall methodology like Failure Mode Effective Analysis, Fault Tree Analysis, Event Tree Analysis, HAZOP, Checklist, inspection, Audit, and What if Analysis presented in this dissertation allows systematic identification of hazards as well as quantification of the risks associated with the operation of chemical process plants. This aids the selection and prioritization of necessary strategies for accident prevention, reduction and limiting their consequences. This dissertation can be used for improving plant safety performance as well as to reduce human and property losses. The result of Hazard identification helps to suggest the control measures in order to prevent deviation and to avoid the consequences. HAZOP technique provides clear and detailed analysis of hazard associated with the process and results are easy to understand.

Beyond-compliance uses of HAZOP/LOPA studies

Problem statement: Ensuring safe operability and minimizing risk is the key component to prevent negative impact in all industries dealing with toxic, reactive, flammable and explosive. Hazard and Operability (HAZOP), a preliminary and systematic approach for identifying hazards has been unquestionably successful in reducing incidents by mitigating the consequence of major accident in the industries process facility. However, laborious work, time and cost are the shortcoming in performing and maintaining HAZOP analysis. Many research works over HAZOP automation available yet the traditional approach is still widely used by plant operators as it covers all part and aspect of a specific plant rather than generalizing to fit many plant types. Approach: In this study, we presented web based HAZOP analysis management system to help HAZOP team and related individual to perform revision, tracking and even complete HAZOP analysis without management bureaucracy. Besides depend solely to expert imaginative thinking of scenario using P&ID, We added dynamic visual model to bring the system user a different view of consequent and subsequent to an accident and can be analyzed in three dimensional effects. This prevented miss looks due to 'paper based' view. Similarity matrix is responsible ensuring accuracy in analysis tracking. Reactor section in a hydrodesulphurization process was used as the case study to illustrate proposed system performance. Results: Developed system in average manages to reduce more than half the time required in performing HAZOP analysis compares to traditional method. Conclusion: This system expected to be the base engine for Virtual Reality simulator in analyzing accident caused by human factor

The safe operation of Chinese Train Control System Level 3 (CTCS-3) is of great significance, particularly with respect to the increasing operational speed and expanding railway networks of the Chinese high-speed railway system, which has drawn deep concern from both customers and strategic makers. A hazard and operability (HAZOP) study has been recognized as an effective systematic examination to identify any potential problems existing in various industrial processes or operations. This paper presents a process of applying a HAZOP study to identify the hazards of a CTCS-3 onboard system for the first time, which is composed of two major parts: system models and hazard identification on the examination session. To better reflect the structure and functions of a CTCS-3 onboard system, the following models are developed, i.e., a reference model, a function hierarchical model, a state diagram, and a sequence diagram. To demonstrate the effectiveness of the HAZOP study, hazard identification on the basis of the functions of the CTCS-3 onboard system and a scenario of temporary speed restriction is considered and employed. The results indicate that existing hazards can be dug out at express speed, which allows the relevant actions to be proposed and implemented to prevent the hazards from spreading to a wide range in the whole CTCS-3 onboard system.

Unified Modelling Language (UML) has a graphical notation for 13 different types of diagrams and can be used as a general modelling tool. Well-known examples of diagram types are class diagrams for modelling classes that can be instanced into objects, state machine diagrams for modelling states in systems and activity diagrams for modelling process flows. A literature survey shows that UML has been used to model concepts and methodologies of risk assessment and risk management. One example is the Coras Framework. The international standard CEI IEC 61882 Hazard and operability (HAZOP) studies describes concepts for investigating and detecting possible hazards in systems. In CEI IEC 6882, guide words like ‘More’ and ‘Less’ are applied to system parameters to invoke deviations in the system and assess possible hazards due to the deviation from the design intent. In this paper, we have used UML to model concepts of CEI IEC 61882 Hazards and operability studies. Diagrams of UML were used to show dependencies and relations between parts of the target system and concepts of CEI IEC 61882. Extensions of UML are suggested to better capture and display the concepts of CEI IEC 61882, the results of a HAZOP study and emerging risk. These extensions are referred to as UML for emerging risks (UML-ER).

The present paper is an extension of the work presented by authors at SDEWES2015 conference, where changes in the dynamic behaviour of shell-and-tube heat exchangers induced by fouling build-up were studied. A mathematical model was proposed of transient heat exchange with the influence of thermal resistance of fouling taken into account. Next a mathematical model of the entire heat exchanger was implemented and simulations were carried out using Simulink in MATLAB environment. The model was validated using data records acquired during 3 years of operation of a heat exchanger network coupled with a Crude Distillation Unit (CDU). Using the validated dynamic model, one can simulate the behaviour of a heat exchanger together with its PID control loop and investigate the influence of fouling build-up on specific indexes of quality of operation. A simulation study was carried out on selected PID-controlled exchangers operated in a heat exchanger network coupled with a CDU rated 220 kg/s crude oil. For different periods of uninterrupted exchanger operation, that is, at different values of the thermal resistance of fouling, tuning parameters were determined using the Ziegler-Nichols method. It was found that the optimal values of tuning parameters changed when the thermal resistance of fouling was changed. However, oscillations remained in the characteristics of some controlled exchangers indicating that the new values of tuning parameters determined by the simple Ziegler–Nichols method were ineffective. In the present work, to improve the quality indices of the exchangers control under fouling conditions, a more advanced method of the optimization of controller tuning is presented using Signal Constraint block in MATLAB/SIMULINK.

Analysis of the HAZOP study and comparison with similar safety analysis systems

In 2020, a fire and explosion accident occurred in Taiwan because of the reverse flow of high‐pressure recycle gas. This accident resulted in three minor injuries and caused the Taiwanese government to instruct the top three chemical groups in Taiwan to conduct procedural hazard and operability (HAZOP) studies in addition to normal HAZOP studies. The cause analysis based on the accident timeline and cause factor chart indicated that improper control of the protection logic bypass and the lack of four process safety management (PSM) elements, namely mechanical integrity, process safety information (PSI), operating procedures, and process hazard analysis (PHA), were the root causes of the aforementioned accident. The deficiencies leading to accidents are related to planning problems in PSM promotion but unrelated to the implementation of PSM programs. Maintenance processes should be evaluated and developed according to PHA results or equipment structure to guarantee equipment integrity. The incompatibility of process chemicals with pipeline materials should be considered; then, the construction materials mentioned in PSI should be extended to those of pipelines, not just equipment. In addition to the hazards of normal operations, those of non‐routine operations should be identified to ensure the completeness of the PSM program. Protection logic bypass should be appropriately controlled, and a complete safety evaluation must be conducted before resetting the initiated protection logic. A majority of the deficiencies identified in this study exist in most Taiwanese chemical companies, including the leading ones performing PSM. The lessons learned from the aforementioned accident provide advance information that can be used to develop an improved PSM system.

This paper was aimed to illustrate the use of process simulation tools to find bottlenecks in a chemical plant. In practice, finding the first bottleneck of a plant is simply by increasing the capacity. However, two questions remain, e.g. what would the next bottleneck be and how big the first bottleneck needs to be expanded until the next bottleneck is reached. These questions can be repeated until eventually the whole equipment in the plant needs to be debottlenecked. Since it is impossible to answer the above questions in practice, a process simulation approach is utilized. Relevant equipment data and a validated thermodynamic model are used to build such a model. Plant performance trials are taken into account to estimate practical parameters such as fouling coefficients and plate tightness. This work requires strong interactions between operational people, consistent data gathering, and process simulation skill. The approach used in this work has shown that a reasonably accurate model can be built. The result has shown that the model can identify the first bottleneck as confirmed on the field. Sequence of bottlenecks and their corresponding increment of capacity increase have also been identified. The simulation results also illustrate the use of process simulation for plant debottlenecking.

According to published statistics regarding pharmaceutical industries, there has been a significant increase in the demand for cosmetics and skincare products. As a result, there has also been an increase in interest by researchers to conduct experimental and theoretical studies on these industries. The outermost layer of the skin, which is the stratum corneum, plays a key role in determining the skin permeability. This layer represents the first and main barrier against dehydration and screening from external elements and pathogens. Research efforts have been made to better understand skin permeability. Experimental methodologies play a key role in pharmaceutical and dermatology studies. However, ethical standards of using animal and human models in in-vitro permeability studies are very strict in their admission process and approval time. Furthermore, the lack of available material and financial resources for setting up, operating and repeating experiments has also limited the required progress. These problems can be addressed by developing better mathematical models on skin permeability. Progress, regarding the mathematical modelling of solute transport in skin, has been achieved in the last decades. The mathematical modelling strategy is used as a skin permeability predictor tool based on common physicochemical properties of the skin and penetrated solute molecules. Many factors play an important role in the formulation of a mathematical model and in determining how reliable the predicted results are. Therefore, the more skin physiological details are included in the model, the more computational efforts are required to interpret the solute permeation mechanisms in the dermal region and simulate a drug transport in the transdermal administration. The mathematical complexities associated with formulating a mathematical model of drug transport in skin significantly limit the utilities of such models in practice. Thus, a balance between the model’s complexity and how realistic it is in describing the solute transport processes in skin has to be achieved. Therefore, a mathematical model formulated on principles familiar to the pharmaceutical scientific community could be of value. In this thesis, we have developed a novel mathematical model using a compartmental approach. The proposed model enables for simulating solute transport across the stratum corneum (SC) in a variety of exposure scenarios in percutaneous drug delivery systems. The obtained results were compared with the diffusion model outcomes – which can be considered the current ‘golden standard’ for modelling skin transport – and showed a good agreement. The mathematical foundations of the model are relatively simple and better aligned with the physiology of the stratum corneum. In addition, this work shows that performing a numerical simulation using the compartmental model is less demanding than using the diffusing model, especially for complex exposure scenarios, and can be performed using free software, such as Python. The research findings of this thesis contribute towards a better understanding of transport phenomena across the skin. Also, the compartmental model proposed in this work can be used to describe transport phenomena in the membrane. Due to the similarity between the governing equations of diffusion and heat transfer, the proposed approach also offers a mathematical framework for studying heat transfer problems in biomaterials with minimum model development or computational efforts.

Composite materials are increasingly being relied upon for their light weight and high strength to weight ratios and form the backbone of the aerospace industry, which follows a Systems Engineering approach. This paper is an attempt to manifest such an approach at a relatively smaller scale for a composite UAV landing gear. The landing gear acts as a support structure for the fuselage during take-offs and landings and hence needs to be carefully designed, analyzed and manufactured. The strength and weight of a landing gear has to be optimized so as to adhere to the overall aerodynamics and structural integrity of the aerial system. This study is initiated with the design concept of the landing gear and the state of load being acted upon followed by appropriate composite material selection. An approximate number of layers are decided for the composite vacuum layup of the landing gear through iterative experimentation. The fibre orientation of the composite layers is instrumental in gauging the macro-mechanical performance of the composite, thus being the focal point of this study. To execute this, the extensional, coupling and bending stiffness matrices are computed in a mathematical model in MATLAB for different fibre orientations in response to the elastic constants of the fibre and matrix. The global and local strains and curvatures are calculated for a load case and the final combination is down-selected. Corresponding to the down-selected combination, the landing gear is finally fabricated, using Vacuum bag moulding.

Metal expansion bellows is an important flexible element used to absorb extension or shrinkage and vibrations of the piping system used in various process applications. Failure of the bellows occurs due to the unpredictable behavior in its convolutions due to severe working conditions. Hence, determination of its dynamic characteristics is of prime importance. To find and analyse dynamic characteristics like axial natural frequencies, modal frequency responses and mode shapes of U-shaped convolution bellows as well as the effect of increase in number of convolutions on the dynamic characteristics. In this paper, analytical, numerical simulation and experimental investigations are performed to find the axial natural frequencies of bellows. Numerical simulation is performed using the mathematical model in MATLAB and modal analysis is performed using ANSYS 15. The deformation and axial natural frequency response of bellows with eight, nine and ten convolutions are obtained by FE analysis for various modes when bellows are subjected to different end conditions. As per the simulation and experimental modal analysis, it is seen that the range of axial natural frequencies with less number of convolutions shows maximum deformation and larger number of convolutions shows minimum deformation. To decrease the axial natural frequency for the given flow rate and to avoid resonance, the number of convolutions of the bellows should be increased for designing the new configuration.

The spring‐assisted gantry robots, described in this paper, were designed primarily for the rapid transfer of lightweight objects from one point to another, e.g. to pick objects from a conveyor belt and to place them in a box. The average amount of work required for pick‐and‐place operations carried out by a conventional gantry robot was decided. Springs were added to conserve the kinetic energy of the main bar, which slides in theX‐direction and the work of the same pick‐and‐place operation was decided. A theoretical study showed that when the spring constant was optimized the required motor work of the spring‐assisted robots were 42–95 percent less than the required work of the conventional robot. The conceptual robot exists in mathematical models in Matlab and SIMULINK.