Optimisation-based approaches for multi-floor process plant layout

The layout configuration of a chemical process plant has an immense impact on its efficiency of operation, energy consumption, environmental impact and safety levels. This design decision usually lasts throughout the life span of a plant but with the advent of smart manufacturing systems, changes can be made as often as required. At present, there is also a growing need for new chemical plants to meet the increasing demand for chemical products. Hence, automating the layout design process using highly efficient and realistic mathematical models is vital. To aid this, mixed integer linear programming (MILP) models are proposed in this thesis for the efficient determination of multi-floor chemical process plant layout designs. These MILP models proposed obtain the layout configurations factoring in equipment inter-connectivity by pipes, pumping, construction, land purchase and a more realistic description for tall equipment that span through floors, with/without the availability of pre-defined production sections. Using novel integer cuts, each model obtains globally optimal solutions for larger problem instances in short computational times. Safety factors are also introduced with risk being quantified using the Dow's fire and explosion index and the Domino Hazard Index. Hazardous events including jet fires, pool fires, fireballs, flash fires, explosions and/or the resulting blast wave effects are quantified as a function of inter-equipment distances. The associated financial risks in the event of an accident are also determined using a more accurate evaluation of the separation distance between equipment. The resulting MILP model estimates the optimal layout configuration and protection device choices for a chemical process plant. In each of these cases, the unique characteristics and limitations of the proposed models are shown using industry-relevant case studies having a varying number of equipment and requirements, with the models handling all features described with improved computational performance

QRA with respect to domino effects and property damage

In 1996 the European Union adopted the Seveso II Directive. The Directive stated actions to be taken in the process industry in order to prevent and limit the impact of serious chemical accidents. In the Directive it is clearly stated that domino effects shall be considered, but the level of detail required is not specified. Due to that fact and the high degree of complexity linked to domino effects, these aspects are mostly dealt with in a qualitative manner. Such approach leads to subjective assessments and is highly dependent on simplified assumptions, leading to results that may be questionable. Thus, it would be beneficial to develop a method that incorporates the risk of domino effects in a quantitative risk analysis (QRA), which has been the aim of this thesis. The method was developed based on a literature review of existing research. Focus was on integrating domino effects as a natural part of a QRA without compromising the timeframe associated to a QRA. The developed method has been applied in a case study of an oil refinery in order to evaluate how well it is applicable in practise. During the case study, the method has proven to enable the risk of property damage with regard to domino effects to be quantitatively analysed. The results from the case study, evidence the importance of taking domino effects into consideration in QRAs, as the risk may be underestimated if not

Risk Analysis of Domino Effect Due to Fire in Petroleum Plants

Fire accidents in petroleum plants are one of the common issues that happen in the industry nowadays. The facilities and equipment in petroleum plants have the risks to involve in accidents specifically fire accidents. These accidents first started as single event then they can spread leading to a domino accident. Fire domino accident have a great impact on a petroleum plant causing the loss of properties and fatalities. The common type of fire accidents that occur in the industry is pool fire. Fire domino can be categorized into three parts: primary event, escalation and secondary scenarios

Design and implementation of a database for QRA management

En aquest treball s’ha dut a terme una recerca bibliogràfica sobre la legislació a nivell europeu, espanyol i català aplicat als establiments afectats per la directiva SEVESO. S’ha realitzat una investigació sobre l’evolució d’aquestes normatives i els canvis que presenten entre elles, documentant quina és a informació requerida que cada establiment ha de presentar segons la seva categoria. La literatura fa referència a l’anàlisi quantitatiu de risc i l’informe de seguretat. S’ha dissenyat una base de dades per la recollida d’informació a partir d’informes de seguretat, basant la seva estructura en la taula de codificació de possibles accidents de la Generalitat de Catalunya. En aquesta base de dades s’ha introduït informació sobre la localització, l’activitat industrial, les condiciones meteorològiques, la substància involucrada, l’iniciador del possible accident greu i l’efecte final associat a aquest. S’ha realitzat un anàlisi exploratori de la base de dades en funció de la seva localització, condiciones meteorològiques, destacant la temperatura, humitat relativa, estabilitat atmosfèrica, direcció i velocitat del vent. També s’ha tingut en compte la substància present, el possible accident bàsic juntament amb les distàncies de seguretat (zona d’intervenció, zona d’alerta i zona d’efecte dominó). Addicionalment, s’ha estudiat l’impacte de cada un d’aquests factors en les distancies de seguretat. Finalment, s’ha realitzat una exploració pel reconeixement de patrons utilitzant la anàlisis de components principals i l’ajustament de la regressió per veure la relació que hi ha entre aquests factors, en funció de l’accident final, i les diferents distàncies de seguretat.En este trabajo se ha realizado una investigación bibliográfica sobre la legislación a nivel europeo, español y catalán aplicado a los establecimientos afectados por la directiva SEVESO. Se ha realizado una investigación sobre cuál es la evolución de esta normativa y los cambios que presentan entre ellas, documentando cuál es la información requerida que debe presentar cada establecimiento según su categoría. La literatura hace referencia al análisis cuantitativo de riesgo y al informe de seguridad. Se ha diseñado una base de datos para la recogida de información a partir de informes de seguridad, basando su estructura en la tabla de codificación de posibles accidentes de la Generalitat de Catalunya. En esta base de datos se ha introducido información sobre la localización, la actividad industrial, las condiciones meteorológicas, la sustancia involucrada, el iniciador del posible accidente grave y el efecto final asociado al mismo. Se ha realizado un análisis exploratorio de la base de datos en función de su localización, condiciones meteorológicas, destacando la temperatura, humedad relativa, estabilidad atmosférica, dirección y velocidad del viento. También se ha tenido en cuenta la sustancia presente, el posible accidente básico especificado junto con las distancias de seguridad (zona de intervención, zona de alerta y zona de efecto dominó). Adicionalmente, se ha estudiado el impacto de cada uno de estos factores en las distancias de seguridad. Por último, se ha realizado una exploración para el reconocimiento de patrones utilizando el análisis de componentes principales y el ajuste de regresión para ver la relación existente entre estos factores, en función del accidente final, y las diferentes distancias de seguridad.In this project, bibliographic research is carried out on the European, Spanish, and Catalan legislation applied to establishments affected by the SEVESO directive. Research on the evolution of these regulations and the modifications between them is conducted, documenting the required information that each establishment must present according to its category. The literature refers to quantitative risk analysis and safety reports. A database is designed for the collection of information from safety reports, basing its structure on the coding table of possible accidents of the Generalitat de Catalunya. Information on the location, industrial activity, meteorological conditions, substance involved, initiator of the possible major accident and the final event, are the fields introduced in the database. An exploratory analysis of the database is carried out according to its location, meteorological conditions, including temperature, relative humidity, atmospheric stability, wind direction and velocity. The substance present, the possible basic accident and final event, specified together with the safety distances (intervention zone, alert zone, and domino effect zone) are also considered. In addition, the impact of each of these factors on the safety distances is studied. Finally, an exploration via pattern recognition using principal component analysis and regression adjustment is done to investigate the existing relation between these factors, as a function of the final event, and the different safety distances

Risk analysis of LPG tanks at the wildland-urban interface

In areas of wildland-urban interface (WUI), especially residential developments, it is very common to see liquefied petroleum gas (LPG) tanks, particularly with a higher ratio of propane, in surface installations serving homes. The most common tanks are between 1 and 5 m3 of capacity, but smaller ones of less than 1 m3 are more frequent. In case of accident, installations may be subject to fires and explosions, especially in those circumstances where legal and normative requirements allow very close exposure to flames from vegetable fuel near LPG tanks. In this project, it is intended to do a comprehensive diagnosis of the problem, addressing the compilation of information on real risk scenarios in historical fires. First, a preliminary presentation of the properties and characteristics of liquefied petroleum gas will be exposed. Its physical and chemical properties, production methodology, pressure and temperature diagrams and important considerations will be defined when using this type of substances in a storage tank of a certain volume. Next, a review of the situation of the existence of LPG tanks in the urban forest interfaces will be exposed. In this case, the main accidents caused by problems with the storage of LPG will be analyzed taking into account the relevance of BLEVE events in this type of incidents. To do this, the main scenarios that could take place in the event of a fire will be presented. Next, the existing legislation on the storage of LPG in these environments in some Mediterranean countries will be studied. In order to develop a comprehensive analysis, the main safety measures and distances will be considered, as well as the awareness of the possibility of vegetation material in the vicinity of LPG storage tanks, which is the main problem that will arise in a possible BLEVE scenario in case of fire. To finalize and facilitate understanding, a comparative table will be included with the aim of visualizing the main advantages and legislative deficiencies between the different countries. Following, the state of the art in terms of modelling LPG accidents at the WUI will be reviewed. Trying to simulate and predict this type of scenarios, it will see the models normally chosen to obtain the tolerable values selected and the answers obtained in each case. Finally, several fire scenarios will be simulated by means of a CFD tool (FDS, Fire Dynamics Simulator). In these simulations, the wind velocity and the distance of the combustible vegetal mass to the tank will be controlled in a WUI fire in which there is a tank of fixed dimensions. The temperature and the heat flow in each of the scenarios will be obtained, and the differences among the location of the sensors and the characteristics of the scenario will be analyzed. As a conclusion, it has been observed that there is a great amount of variables that are not contemplated by the regulatory organisms and that the existing legislation does not guarantee the safety of the population in this type of environment. From the simulations results, variables as temperature should be studied for further characterizations

Accident prevention programming for the chemical industry.

Thesis (M.B.A.)--Boston Universit

Extension of Quantitative Risk Assessment to the Analysis of External Hazard Factors in the Chemical and Process Industry

The PhD research project is aimed at developing and applying an innovative framework toward Risk Assessment of cascading events within the chemical and process industry, addressing both domino and security-based events. Cascading events are catastrophic accidents, triggered by external hazard factors, including safety-based (i.e., domino) and security-based events. In the chemical industry domain, barriers provide a crucial role for the prevention, control and mitigation of cascading events. Therefore, it is necessary to apply innovative techniques, aimed at the evaluation of barriers technical performance and at their optimal economic allocation, to be inserted within Quantitative Risk Assessment (i.e., QRA). Concerning barriers technical performance, the research activity is aimed at applying Bayesian Networks to safety barriers performance assessment, regarding domino events. Starting from a conventional approach, preliminary applications have been aimed at implementing a Bayesian approach to barriers performance assessment concerning major accidents. Therefore, the approach has been extended to domino accident analysis, in purpose to evaluate the effect of barriers introduction within modelling. The case studies demonstrated that the application of a Bayesian approach provides a very accurate barriers performance assessment within QRA, with reference to external hazard factors driven accidents (i.e., domino events), offering a realistic risk picture. Concerning barriers optimal economic allocation, the research activity is aimed at developing and applying an original economic model for the prevention of security-based cascading events. The model includes security upgrades performance and costs assessment, evaluation of benefits and definition of threat and vulnerability probabilities. The application of economic techniques, by means of cost-benefit and cost-effectiveness analyses, enables barriers optimal allocation within budgets constraints. Validation of the model is provided by application to relevant case studies. Therefore, the model enables defining rational criteria for barriers optimal selection and allocation and its outputs support the inclusion of security hazards within QRA, and related decision-making

Robust multi-objective optimization of safety barriers performance parameters for NaTech scenarios risk assessment and management

Safety barriers are to be designed to bring the largest benefit in terms of accidental scenarios consequences mitigation at the most reasonable cost. In this paper, we formulate the problem of the identification of the optimal performance parameters of the barriers that can at the same time allow for the consequences mitigation of Natural Technological (NaTech) accidental scenarios at reasonable cost as a Multi-Objective Optimization (MOO) problem. The MOO is solved for a case study of literature, consisting in a chemical facility composed by three tanks filled with flammable substances and equipped with six safety barriers (active, passive and procedural), exposed to NaTech scenarios triggered by either severe floods or earthquakes. The performance of the barriers is evaluated by a phenomenological dynamic model that mimics the realistic response of the system. The uncertainty of the relevant parameters of the model (i.e., the response time of active and procedural barriers and the effectiveness of the barriers) is accounted for in the optimization, to provide robust solutions. Results for this case study suggest that the NaTech risk is optimally managed by improving the performances of four-out-of-six barriers (three active and one passive). Practical guidelines are provided to retrofit the safety barriers design

Safety management of a complex R and D ground operating system

A perspective on safety program management was developed for a complex R&D operating system, such as the NASA-Lewis Research Center. Using a systems approach, hazardous operations are subjected to third-party reviews by designated-area safety committees and are maintained under safety permit controls. To insure personnel alertness, emergency containment forces and employees are trained in dry-run emergency simulation exercises. The keys to real safety effectiveness are top management support and visibility of residual risks