Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 50 of 504 results
  • The significance of domino effect in chemical accidents

     Hemmatian, Behrouz; Abdolhamidzadeh, B; Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim
    Journal of loss prevention in the process industries
    Date of publication: 2014
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Predicting the flammable region reach of propane vapor clouds

     Vílchez, Juan; Villafañe, Diana; Casal Fabrega, Joaquim
    Journal of loss prevention in the process industries
    Date of publication: 2014
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Liquified gas fuels are widely used around the world, and the growth of LNG and LPG consumption continues to increase. However, using these fuels can lead to accidents if they are released to the environment. Consequently, the challenge to control and predict such hazards has become an objective in emergency planning and risk analysis. In a previous article the ¿Dispersion Safety Factor¿ (DSF) was proposed, defined as the ratio between the distance at which the lower flammability limit concentration occurs and that corresponding to the visible contour of a vapor cloud. Its interest was demonstrated by applying it to the specific case of an LNG spill. With the appropriate modifications, this factor may be applied to the dispersion of other substances; in this communication it is applied to the atmospheric dispersion of propane, and two expressions are proposed to estimate it. Due to the similarity between the properties of both gases, these expressions could probably be applied as well to the dispersion of propylene

  • Analysis of past accidents and relevant case-histories

     Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria
    Date of publication: 2013
    Book chapter

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The diverse historical surveys on accidents involving domino effect have been analyzed to identify their significance and their most important features. From these data, the importance of domino effect among all accidents in the process industry and in the transportation of hazardous materials has been highlighted. The characteristics of this type of accidents have been studied with a statistical approach: origin and causes of domino effect, materials most frequently involved and effects and consequences of accidents. The significance of the diverse domino sequences have been assessed by using the relative probability event tree. Finally, four relevant cases have been discussed, corresponding to the following initiating events: two vapor cloud explosions (Buncefield, 2005 and Naples, 1985), one jet fire (Valero, 2007) and one accident associated with dust explosion.

  • Tracking global flows of e-waste additives by using substance flow analysis, with a case study in China

     Tien, Henning; Heise, Susanne; Segui Julia, Xavier; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria; Suciu, Nicoleta; Capri, Ettore; Trevisan, Marco; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim
    Date of publication: 2013
    Book chapter

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Human and environmental impact produced by e-waste releases at Guiyu region (China)

     Suciu, Nicoleta; Capri, Ettore; Trevisan, Marco; Tanaka, Taku; Tien, Henning; Heise, Susanne; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim; Segui Julia, Xavier; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria
    Date of publication: 2013
    Book chapter

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Environmental fate models

     Suciu, Nicoleta; Tanaka, Taku; Trevisan, Marco; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim; Segui Julia, Xavier; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria; Capri, Ettore
    Date of publication: 2013
    Book chapter

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Environmental reporting and communication ¿ ¿Show me the evidence¿!

     Puig, Martí; Wooldridge, Chris; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria
    GreenPort Congress
    Presentation's date: 2013-10-10
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Fuzzy model for risk assessment of persistent organic pollutants in aquatic ecosystems

     Segui Julia, Xavier; Pujolasus, Edgar; Betró, S.; AGUEDA COSTAFREDA, ALBA; Casal Fabrega, Joaquim; Ocampo Duque, W.; Rudolph, Ignacio; Barra, Ricardo; Páez, Martha; Baron, E.; Eljarrat, Ethel; Barceló Culleres, Damià; Darbra Roman, Rosa Maria
    Environmental pollution
    Date of publication: 2013
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    We developed a model for evaluating the environmental risk of persistent organic pollutants (POPs) to aquatic organisms. The model is based on fuzzy theory and uses information provided by international experts through a questionnaire. It has been tested in two case studies for a particular type of POPs: brominated flame retardants (BFRs). The first case study is related to the EU-funded AQUATERRA project, with sampling campaigns carried out in two Ebro tributaries in Spain (the Cinca and Vero Rivers). The second one, named the BROMACUA project, assessed different aquatic ecosystems in Chile (San Vicente Bay) and Colombia (Santa Marta Marsh). In both projects, the BFRs under study were polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). However, the model can be extrapolated to other POPs and to different aquatic ecosystems to provide useful results for decision-makers.

    We developed a model for evaluating the environmental risk of persistent organic pollutants (POPs) to aquatic organisms. The model is based on fuzzy theory and uses information provided by international experts through a questionnaire. It has been tested in two case studies for a particular type of POPs: brominated flame retardants (BFRs). The first case study is related to the EU-funded AQUATERRA project, with sampling campaigns carried out in two Ebro tributaries in Spain (the Cinca and Vero Rivers). The second one, named the BROMACUA project, assessed different aquatic ecosystems in Chile (San Vicente Bay) and Colombia (Santa Marta Marsh). In both projects, the BFRs under study were polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). However, the model can be extrapolated to other POPs and to different aquatic ecosystems to provide useful results for decision-makers.

  • A dispersion safety factor for LNG vapor clouds

     Vílchez Sanchez, Juan Antonio; Villafañe, Diana; Casal Fabrega, Joaquim
    Journal of hazardous materials
    Date of publication: 2013-02-15
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The growing importance of liquefied natural gas (LNG) to global energy demand has increased interest in the possible hazards associated with its storage and transportation. Concerning the event of an LNG spill, a study was performed on the relationship between the distance at which the lower flammability limit (LFL) concentration occurs and that corresponding to the visible contour of LNG vapor clouds. A parameter called the dispersion safety factor (DSF) has been defined as the ratio between these two lengths, and two expressions are proposed to estimate it. During an emergency, the DSF can be a helpful parameter to indicate the danger of cloud ignition and flash fire.

    The growing importance of liquefied natural gas (LNG) to global energy demand has increased interest in the possible hazards associated with its storage and transportation. Concerning the event of an LNG spill, a study was performed on the relationship between the distance at which the lower flammability limit (LFL) concentration occurs and that corresponding to the visible contour of LNG vapor clouds. A parameter called the dispersion safety factor (DSF) has been defined as the ratio between these two lengths, and two expressions are proposed to estimate it. During an emergency, the DSF can be a helpful parameter to indicate the danger of cloud ignition and flash fire

  • Estudio de la dispersión e incendio de nubes inflamables de gas (GNL y GLP)  Open access

     Villafañe Santander, Diana
    Defense's date: 2013-06-20
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    This thesis is focuses on the study of the dispersion and combustion of a vapor cloud resulting from the escape of LNG and LPG. The consumption of natural gas and LPG is clearly growing, and is based on multiple storage facilities and different types of transport. The possibility of a release and the subsequent vapor cloud formation is significant. The application of appropriate measures to ensure safety in terminals and facilities related to these products is essential to the community safety. An important aspect is the management of the emergency once the cloud has reached the stationary state (the time to reach this state depends on wind velocity, but is usually very short). In this situation, any information about the position of the flammable region of the cloud can be very helpful. A historical analysis of accidents involving vapor cloud fires has been carried out. 176 accidents have been analyzed, which have yielded information on the causes, origins and consequences of such events. A dispersion safety factor (DSF) has been proposed as a tool to help in the decision process under these circumstances. The parameter DSF is the ratio between the distance reached by the lower flammability limit and that of the visible cloud. The results obtained for the dispersion safety factor with the DEGADIS code agree fairly well with the evidence from experimental data obtained at large scale. This factor is strongly dependent on the atmospheric relative humidity. Thus, when high relative humidity prevails, the cloud will be visible for some distance beyond the flammable region (DSF < 1). When the relative humidity in the air is low, the flammable region extends beyond the visible cloud contour (DSF > 1). In this case, the flammable vapor cloud will not be visible at the location of any potential ignition source. Two expressions have been proposed to estimate the parameter DSF for a release of LNG according to the range of HR. The same treatment has also been applied to the case of a spill of liquefied propane gas cooled at atmospheric pressure. With respect to the combustion of the flammable vapor cloud, a new expression has been obtained, which determines the flame speed as a function of the wind speed, based on various large scale tests conducted with LNG between 1968 and 1982; this expression gives a better fit for high wind speeds. A relatively simple model of the flash fire has been developed based on the dispersion of the cloud as a function of fuel properties and atmospheric conditions (stability and wind velocity). The size of the flames will depend on the size of the cloud, being higher that the latter. It has been observed from the available data experiments, that the flame height increases proportionally to the visible cloud.

  • Design Optimization of Storage Terminals through the Application of QRA.  Open access

     Bernechea Rojas, Esteban José
    Defense's date: 2013-09-19
    Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The storage of hazardous materials is a necessary part of the life cycle and operation of any process plant, which intrinsically entails certain hazards and dangers. The results of historical analysis reveal that 17% of major accidents in the process industry occur in storage terminals, and the NFPA of the USA reported that in 2009, 13% percent of the major fire accidents that occurred in that country took place in storage installations, causing $69,980,000 in losses. Therefore, it is clear that a methodology for the optimization of the design of storage terminals from a safety point of view could be very useful. A method that allows doing this, through the combination of Quantitative Risk Assessment, Inherently Safer Design and mathematical optimization, has been developed in this thesis. This methodology has been applied to a real life case study, obtaining results that validate it as a useful tool in the design of storage terminals.

  • Global E-waste trade impact on China

     Tien, Henning; Heise, Susanne; Segui Julia, Xavier; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria; Suciu, Nicoleta; Capri, Ettore; Trevisan, Marco; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim
    Risk-based Management of Chemicals and Products in a Circular Economy at a Global Scale
    Presentation's date: 2012-05
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Environmental and human risk assessment of e-waste releases in China through USEtoxTM

     Segui Julia, Xavier; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim; Tien, Henning; Heise, Susanne; Suciu, Nicoleta; Capri, Ettore; Trevisan, Marco
    Risk-based Management of Chemicals and Products in a Circular Economy at a Global Scale
    Presentation's date: 2012-05
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Jet fires: a "minor" fire hazard?

     Casal Fabrega, Joaquim; Gómez-Mares, Mercedes; Muñoz, Miguel; Palacios, Adriana
    International Conference on Safety & Environment in Process & Power Industry
    Presentation's date: 2012-06
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Use of a multimedia exposure model for health risk assessment of lead released during e-waste recycling processes in South of China

     Suciu, Nicoleta; Trevisan, Marco; Capri, Ettore; Tanaka, Taku; Darbra Roman, Rosa Maria; Segui Julia, Xavier; Casal Fabrega, Joaquim; Tien, Henning; Heise, Susanne; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim
    Risk-based Management of Chemicals and Products in a Circular Economy at a Global Scale
    Presentation's date: 2012-05
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Application of the multimedia environmental model QWASI for asessing the aquatic risk in an area of informal e-waste recycling

     Heise, Susanne; Tien, Henning; Darbra Roman, Rosa Maria; Segui Julia, Xavier; Casal Fabrega, Joaquim; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim; Suciu, Nicoleta; Trevisan, Marco; Capri, Ettore
    Risk-based Management of Chemicals and Products in a Circular Economy at a Global Scale
    Presentation's date: 2012-05
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Human and environmental impact produced by the e-waste releases at Guiyu Region (China)

     Suciu, Nicoleta; Capri, Ettore; Trevisan, Marco; Tien, Henning; Heise, Susanne; Schuhmacher, Marta; Nadal, Martí; Rovira Solano, Joaquim; Segui Julia, Xavier; Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria
    Risk-based Management of Chemicals and Products in a Circular Economy at a Global Scale
    Presentation's date: 2012-05
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Jet fires: a "minor" major accident?  Open access

     Casal Fabrega, Joaquim; Gómez-Mares, Mercedes; Muñoz, Miguel Angel; Palacios, Adriana
    Chemical engineering transactions
    Date of publication: 2012
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Jet fires have received only a rather reduced attention as compared to other types of fires; this is probably due to the fact that they are usually much smaller that fireballs, pool fires or tank fires. However, jet fires often occur in areas where there is other equipment and the probability of flames impinging on a pipe or a vessel can be high. Furthermore, due to the turbulence of the phenomenon, the combustion in such fires is very good and high heat fluxes can seriously affect this equipment, thus originating a domino effect which will enlarge the scale of the accident. A historical survey has shown that, of the jet fires reported in accident data bases, 50 % caused another event with severe effects. In 90 % of the domino effect cases there was an explosion, usually of a vessel; this was especially frequent in transportation accidents. In this communication the main features of jet fires are commented: most frequent domino effect sequences, shape and size, thermal behaviour, mathematical modelling.

  • Risk analysis active learning through the investigation of real cases

     Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim; Pastor Ferrer, Elsa; Vílchez, Juan Antoni; Arnaldos Viger, Josep; Planas Cuchi, Eulalia
    Process safety and environmental protection
    Date of publication: 2012
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Risk analysis is a topic of high relevance in chemical engineering. Courses on this topic are being introduced increasingly into the university curricula. The investigation of real cases is an interesting opportunity to consolidate the concepts taught in such courses and to get a better engagement of students through a creative work. The exercise proposed in this paper has to be performed by a group of students to whom a set of information has been provided. In the exercise, the students play the role of an expert team: they have to deliver a final report including diverse sections such as the description of the accident, the explanation of why and how it occurred, different calculations and finally, some conclusions. From the pedagogical point of view, the results obtained from this type of exercise are very positive and promote the students active and cooperative learning.

  • Risk-based optimization of the design of on-shore pipeline shutdown systems

     Medina, Héctor; Arnaldos Viger, Josep; Casal Fabrega, Joaquim; Bonvicini, Sarah; Cozzani, Valerio
    Journal of loss prevention in the process industries
    Date of publication: 2012-05
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Crude oil and other liquid materials are transported in large quantities through pipelines. Pipelines are an efficient and safe transport way as compared to both rail and road transportation, both from the economical and environmental points of view. Nevertheless, loss of containment accidents can occur due to external action ea mechanical impact, for examplee or to corrosion, aging, etc. Even though the frequency of such events is certainly very low, the effects and consequences on environment can be very important. The consequences of accidents in pipelines can be efficiently reduced through a suitable design of the whole system. One of the points which must be decided in the design is the installation of blocking valves at appropriate distances, so that emergency shutdowns can interrupt the flow of substance and isolate the section where the loss of containment has taken place. In the case of pipe rupture the amount released is therefore limited to the content between two consecutive valves, usually placed according to heuristic criteria. However, if too many valves are used, the capital cost of equipment increases excessively, and if too few are used, the risk of serious accidents increases. In this paper we consider the possibility of improving the design of such systems by applying riskbased optimization criteria. We propose an optimization methodology to solve this conflict by means of an objective function that analyzes the variations in overall costs, including the cost of the investment (with specific reference to blocking valves) and the cost of accidents. The result is an optimum situation in which costs are kept to a minimum. As an example, we apply the methodology to the transportation of gasoline by pipeline.

  • Application of life cycle from functional security to the maintenance of security valves

     Basco, J.; Vílchez, Juan Antoni; Blanco, E.; Casal Fabrega, Joaquim
    Ingeniería química
    Date of publication: 2012-09
    Journal article

     Share Reference managers Reference managers Open in new window

  • Additives in the textile industry

     Darbra Roman, Rosa Maria; González Dan, Jose Roberto; Casal Fabrega, Joaquim; Àgueda, Alba; Capri, Ettore; Fait, G; Schumacher, Marta; Nadal, Martí; Rovira Solano, Joaquim; Grundmann, Veit; Barceló, D; Ginebreda Marti, Antoni; Guillén, Daniel
    Date of publication: 2012-01-31
    Book chapter

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Medalla Narcís Monturiol al mèrit científic i tecnològic

     Casal Fabrega, Joaquim
    Award or recognition

    View View Open in new window  Share

  • Thermal radiation from vertical jet fires

     Palacios, Adriana; Muñoz, Miguel; Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim
    Fire safety journal
    Date of publication: 2012
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Geometric and thermal data, obtained from a series of large outdoor jet fire experiments, were used to estimate the thermal radiation intensity from the flames towards targets located at diverse distances. Vertical turbulent sonic and subsonic exit velocity propane jet fires, up to 10.3 m in length released in still air, were studied. The temperatures of the flame surface and the surface emissive power of the flame were also analysed by processing infrared images. Thermal radiation intensity was estimated by applying the solid flame model in both one-zone and multiple-zone configurations (taking into account the variation of surface emissive power), considering the flame as a cylinder defined by the 800 K isotherm. Experimental and predicted thermal radiation intensity values were compared.

  • Main features and mathematical modelling of flash fires

     Villafañe, Diana; Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim
    International Congress of Chemical and Process Engineering
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Fuzzy approach for risk assessment of brominated flame retardants in aquatic ecosystems of Latin America

     Àgueda, A.; Betrò, S.; Pujolasus, E.; Casal Fabrega, Joaquim; Ocampo-Duque, William; Eljarrat, Ethel; Barceló, D.; Darbra Roman, Rosa Maria
    SETAC Europe Annual Meeting
    Presentation's date: 2011-05
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Environmental risk assessment of brominated flame retardants through fuzzy logic

     Betrò, S.; Pujolasus, A.; Àgueda, E.; Casal Fabrega, Joaquim; Ocampo-Duque, William; Eljarrat, Ethel; Barceló, D.; Darbra Roman, Rosa Maria
    RISKCYCLE Workshop
    Presentation's date: 2011-05-02
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Environmental risk assessment of brominated flame

     Betrò, S.; Pujolasus, E; Àgueda, A; Casal Fabrega, Joaquim; Ocampo-Duque, William; Eljarrat, Ethel; Barceló, D; Darbra Roman, Rosa Maria
    RISKCYCLE workshop
    Presentation's date: 2011-05
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Flash fire: historical analysis and modeling

     Villafañe, Diana; Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim
    International Congress of Chemical and Process Engineering
    Presentation's date: 2011-05-10
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Risk-Based inspection and its application to the optimization of chemical plants

     Medina, Héctor; Arnaldos Viger, Josep; Casal Fabrega, Joaquim
    International Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction
    Presentation's date: 2011-05-09
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Convective heat transfer around vertical jet fires: an experimental study

     Kozanoglu, Bulent Kozanoglu; Zárate, Luis Zárate; Gómez-Mares, Mercedes; Casal Fabrega, Joaquim
    Journal of hazardous materials
    Date of publication: 2011-12
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Flash fire: historical analysis and modeling

     Villafañe, D; Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim
    Chemical engineering transactions
    Date of publication: 2011
    Journal article

     Share Reference managers Reference managers Open in new window

  • Risk-based inspection and its applications to the optimization of chemical plants

     Medina, H; Arnaldos Viger, Josep; Casal Fabrega, Joaquim
    Chemical engineering transactions
    Date of publication: 2011
    Journal article

     Share Reference managers Reference managers Open in new window

  • Main Features and mathematical modelling of flash fires

     Villafañe, D; Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim
    Chemical engineering transactions
    Date of publication: 2011
    Journal article

     Share Reference managers Reference managers Open in new window

  • Producción de hidrógeno a partir del reformado con vapor de dimetil éter utilizando monolitos catalíticos  Open access

     Ledesma Rodriguez, Cristian
    Defense's date: 2011-11-25
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    El modelo actual del consumo energético basado en la utilización de combustibles fósiles requiere un replanteamiento debido al agotamiento de éstos y a las emisiones de gases contaminantes que generan. La obtención de energía mediante la utilización de pilas de combustible se presenta como una alternativa prometedora dado su elevado rendimiento energético y que únicamente genera agua como subproducto. El tipo más sencillo de pila de combustible requiere de una fuente de oxígeno e hidrógeno. El primero puede extraerse del aire de forma sencilla, pero el hidrógeno debe generarse ya que no existe de forma aislada en la Tierra. Uno de los métodos con los que se obtiene una mayor cantidad de hidrógeno es mediante el reformado catalítico con vapor de un combustible derivado de la biomasa, el cual además es un método sostenible dado que no se generan nuevas emisiones a la atmósfera. En este trabajo se ha estudiado la producción de hidrógeno a través de la reacción catalítica y endotérmica del reformado con vapor del dimetil éter, producto que puede obtenerse a partir de la biomasa. Para ello se ha preparado y caracterizado mediante diferentes técnicas propias del estado sólido una serie de catalizadores soportados en estructuras monolíticas de cordierita que contienen diferentes óxidos inorgánicos como soporte y cobre, zinc, paladio o mezclas de éstos como fase activa. Se ha estudiado el comportamiento de los catalizadores monolíticos en la reacción de reformado con vapor del dimetil éter para evaluar su actividad, selectividad y estabilidad tanto en condiciones diluidas como en condiciones próximas a las de la industria. Asimismo se ha estudiado el mecanismo de la reacción mediante espectroscopía IR y la naturaleza de los centros activos de los catalizadores mediante espectroscopía fotoelectrónica de rayos X (XPS). El catalizador monolítico que ha mostrado un mejor comportamiento en términos de actividad, selectividad y estabilidad es el que contiene Cu y Zn como fase activa y óxido de zirconio. La presencia de especies reducidas de cobre favorece la formación de especies intermedias tipo formiato, que son las que evolucionan a dióxido de carbono. La presencia del zinc favorece la dispersión de las partículas de cobre, además de mejorar la selectividad hacia los productos de la reacción de reformado, hidrógeno y dióxido de carbono

    The current model of energy consumption based on the use of fossil fuels needs a change due to their exhaustion and their hazardous emissions to the atmosphere. Fuel cells are considered a promising alternative due to their high energy yield and only water is produced as a side product. The easiest type of fuel cell needs a source of oxygen and hydrogen. The first one can be extracted from air but the hydrogen must be produced since it does not exist as an isolated compound in Earth. One of the methods which a high amount of hydrogen is produced is by the steam reforming reaction of a biomass derived fuel, a sustainable method since no new emissions are generated. In this work, the production of hydrogen by the catalytic steam reforming of dimethyl ether (DME), a fuel that can be obtained from biomass, has been studied. Different catalysts supported on cordierite monolithic structures have been prepared and characterized by different techniques. These catalysts contain different inorganic oxides as a support and copper, zinc, palladium or mixtures of them as active phase. The performance of these catalysts in terms of activity, selectivity and stability in the DME steam reforming reaction has been studied under diluted conditions or using pure mixtures, simulating industrial conditions. Moreover, the reaction mechanism has been studied by IR spectroscopy and the nature of the active sites of the catalysts has been studied by X-ray photoelectron spectroscopy (XPS). The catalytic monolith that showed the best performance in terms of activity, selectivity and stability was the one that contains copper and zinc as active phase and zirconia oxide as a support. The presence of copper-reduced species favours the formation of formate intermediates, which evolves to carbon dioxide. The presence of zinc favours the dispersion of copper particles and improves the selectivity towards the reforming products, hydrogen and carbon dioxide.

  • Efectivitat dels tractaments d'aclarida en la reducció del risc de propagació d'incendis en regenerats de pi blanc  Open access

     Domènech Jardí, Ruth
    Defense's date: 2011-11-18
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Increased wildfire activity over the last years has made fire managers to become more concerned about the effectiveness of current fuel treatment practices to reduce fire risk and severity. Fuel treatments lead to changes in the forest structure and therefore modify certain basic parameters that may influence the fire behaviour. The goal of this work is to quantitatively assess the effectiveness of fuel treatments in reducing risk of wildfires spread in some typically Mediterranean forest. Specifically, it envisages to know the characteristics of the fire that can occur in the slash originated from regenerated aleppo pine stands that were thinned after a wildfire and also to know the evolution of slash combustibility after the treatment. First, an extensive literature review has been done, focused mainly on those works that assessed the effectiveness of fuel treatments in reducing the risk of wildfire. Several studies demonstrated the effectiveness of treatments such as prescribed burning or thinning. However, these studies are not consistent about what treatment and slash management technique are the most effective. A study area has been selected and located within the perimeter of a large forest fire occurred in Bages (Central Catalonia, Spain) in 1994 to study the effectiveness of a type of fuel treatment usually performed in the Mediterranean Basin. The site was previously thinned during different periods and the slash was left in, not managed. In this area, the fuel, environment and topographic characteristics have been determined. With the fuel sampling methods used at the site, a protocol has been produced in order to characterize the regenerated aleppo pine stands, useful to obtain the parameters needed to evaluate fire behaviour. Results have led to a new fuel model for regenerated aleppo pine stands and also fuel models for regenerated aleppo pine stands that have been thinned at different times with the slash remaining unmanaged at the site. An experimental burning program has been implemented reproducing two different regenerated structures (6 and 40 months after treatment). With these experiments it has been proved that ex-situ experimentation is not useful to reproduce actual fire situations because it is impossible to repeat faithfully the overall structure of the ecosystem that affect fire behavior. A series of simulations of potential fires that could occur in the study area have been performed, incorporating the determined inputs (environmental conditions and fuel type) and evaluating different simulation tools (NEXUS i WFDS). Results obtained with the two simulations tools used confirm that both tools are reliable. In general values obtained in fireline intensity and rate of spread with WFDS are larger than with NEXUS. Results from simulations of Bages plots carried with both simulation tools generally show that fire behavior is more severe 1 month and 6 months after the treatment. That is, the wildfire effects after the treatment would be worse than in the untreated control plot and that time does not improve this situation, at least six months after treatment. According to the results and given the characteristics of our country where the risk of fires is very high, the effect of thinning treatments performed in central Catalonia after the 1994 fire brings a great fire vulnerability in treated stands, at least during the first months of treatment.

  • Study of jet fires geometry and radiative features  Open access

     Palacios Rosa, Adriana
    Defense's date: 2011-01-11
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Entre els accidents greus que poden ocórrer a les instal·lacions industrials o durant el transport de substàncies perilloses, els dolls de foc presenten un especial interès. Tot i que tenen una distància relativament més curta d'afectació que altres accidents greus, es caracteritzen per originar grans fluxos de calor i, en cas de contacte de la flama amb un equip, originen sovint un efecte domino, desencadenant una subseqüent explosió, incendi o altres esdeveniments amb greus conseqüències.Diversos estudis experimentals i teòrics han estat efectuats; no obstant això, la majoria d'aquests han estat enfocats a dolls de foc a escala de laboratori, flames subsòniques o torxes, les condicions de les quals difereixen significativament d'aquelles trobades en dolls de foc accidentals reals, que normalment assoleixen majors longituds de flama i velocitats de sortida sònica. Aquesta manca d'investigació és la raó per explicar perquè els dolls de foc eren encara molt mal coneguts i la predicció dels seus efectes i conseqüències era encara un problema. Aquesta tesi ha estat elaborada per a obtenir informació nova i útil sobre els dolls de foc, millorant la comprensió de la seva geometría i de les característiques tèrmiques, mitjançant l'anàlisi, l'experimentació i el modelatge matemàtic.Aquest estudi s'ha centrat alhora en dades existents i en noves dades experimentals, implicant Aixa dolls de foc verticals i horitzontals alliberats en absència de vent, implicant diversos combustibles (hidrogen, metà i propà). L'estudi comprèn una àmplia gamma de variables d'operació (velocitats de sortida del combustible, pressions en la canonada i diàmetres d'orifici de sortida). L'estudi experimental ha implicat dolls de foc amb flames de fins a 10.3 m de longitud i 1.5 m d'amplada. El combustible utilitzat ha estat propà, amb velocitats de sortida sònica i subsònica, utilitzant diversos diàmetres d'orifici de sortida. Els dolls de foc han estat filmats amb dues càmeres de vídeo (VHS) i una càmera termográfica d'alta velocitat (IR). Les principals característiques geomètriques de les flames (dimensions i forma) han estat analitzades en funció de la velocitat de sortida del combustible,del flux màssic i del diàmetre d'orifici de sortida. L'anàlisi i tractament d'imatges infraroges i de les mesures obtingudes amb tres sensors de flux de calor situats a diferents distàncies de la sortida del doll de foc han permès l'obtenció de les seves principals característiques de radiació: flux de calor irradiat als voltants (persones i instal·lacions) en funció de la distancia, poder emissiu i emisivitat de les flames. Diverses expressions han estat proposades per estimar les dimensions de la flama en funció de diverses variables (flux màssic, diàmetre d'orifici de sortida i nombres de Froude i Reynolds). Els resultats i expressions obtinguts en aquest estudi contribueixen a una millor comprensió dels dolls de foc, representant un avanç en les metodologies i l'establiment de noves mesures, normes i polítiques de planificació per a la prevenció i/o el control d'aquest tipus d'accident greu amb foc, tant en establiments industrials com en el transport de materials perillosos.

    Among the major accidents that can occur in processing plants or in the transportation of hazardous materials, jet fires are of particular interest. Although they have a relatively shorter distance of influence than other major accidents, they are characterized by high heat fluxes and if there is flame impingement they can originate a domino effect, leading to a subsequent explosion, large fire, or other events with severe effects. Several experimental and theoretical studies have been carried out; however, most of those works have been focused on small-scale jet fires, subsonic flames or flares, the conditions of which significantly differ from those found in real accidental jet fires, usually reaching larger flame lengths and sonic exit velocities. This lack of research is the reason to explain why the current knowledge of jet fires was still rather poor and the accurate prediction of their effects and consequences was still a problem. The present thesis has been addressed to produce a significant amount of novel and useful information on jet fires, by improving understanding of jet fire structure, reach and radiative features, through analyses, experiment and mathematical modelling. This study has been focused on both existing and also new experimental jet flame data, comprising all together, turbulent non-premixed jet flames vertically and horizontally released into still air, involving several fuels (hydrogen, methane and propane), over a wide range of operational conditions (jet exit velocities, release pressures and pipe diameters). The experimental study developed in this thesis has concerned relatively large jet fires with flames of up to 10.3 m in length and 1.5 m in width. The fuel was propane, and both sonic and subsonic jet exit velocities were obtained from different outlet diameters. The jet fires were filmed with two videocameras registering visible light (VHS) and a thermographic camera (IR). The main geometrical features of the flames were analyzed as a function of the fuel velocity, mass flow rate and jet outlet diameter: jet flame size and flame shape. The treatment of infrared images and measurements obtained from three heat flow sensors located at different distances from the jet fire outlet also led the main radiative features of jet fires to be obtained: incident thermal radiation heat over a target, surface emissive power and emissivity of the flames.Expressions for estimating jet flame reach as a function of several variables (mass flow rate, orifice exit diameter, Froude and Reynolds numbers) have also been proposed. The results and the expressions obtained in this study contribute to a better understanding of jet fires for accurate risk assessment, allowing the obtention of important advances in risk assessment methodologies and the establishment of new measures, regulations, and risk planning policies for the prevention and/or control of this type of major fire, occurred world-wide in industrial establishments and in the transportation of hazardous materials.

  • Generic event trees and probabilities for the release of different types of hazardous materials

     Vilchez Sanchez, Juan Antonio; Espejo, Vicenç; Casal Fabrega, Joaquim
    Journal of loss prevention in the process industries
    Date of publication: 2011
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Assessment of the shape of vertical jet fires

     Palacios Rosa, Adriana; Casal Fabrega, Joaquim
    Fuel (Guildford)
    Date of publication: 2011-02
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Experiments were carried out on relatively large vertical propane sonic and subsonic exit velocity jet fires (up to approximately 10 m in length and 1.5 m in width). The main geometrical features of jet fires (flame shape, length and width) were determined by analyzing infrared images. From the observations of visible and infrared images, the flame boundary was defined as that corresponding to a temperature of 800 K. Results were compared with the shapes proposed in previous research projects. In the present study, data for sonic and subsonic exit velocity flames indicated that a cylindrical shape could accurately describe the shape of a vertical propane jet fire in still air. The length of such a cylindrical jet fire was the radiant flame length and the equivalent diameter was that corresponding to a volume equal to that surrounded by the aforementioned boundary. The ratio of flame length to diameter was found to be 7. Expressions are proposed to predict the values of jet flame length and width as a function of orifice exit diameter and Reynolds number.

  • The behaviour of vertical jet fires

     Palacios, Adriana; Gómez-Mares, Mercedes; Casal Fabrega, Joaquim
    13th International Symposium on Loss Prevention and Safety Promotion in the Process Industries
    Presentation's date: 2010-06-06
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Assessment of thermal effects from hydrocarbon fires

     Palacios Rosa, Adriana; Gómez Mares, Mercedes; Villafañe Santander, Diana; Darbra Roman, Rosa Maria; Muñoz, Miguel; Casal Fabrega, Joaquim
    European Meeting on Chemical Industry and Environment
    Presentation's date: 2010-05-19
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • RISKCYCLE Work package 5: Aims achieved and future goals

     Darbra Roman, Rosa Maria; Àgueda, A.; Casal Fabrega, Joaquim
    RISKCYCLE Workshop
    Presentation's date: 2010-11-15
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Correlation of the height of turbulent choked jet flames

     Bradley, D.; Casal Fabrega, Joaquim; Palacios, A.
    International Seminar on Fire and Explosions Hazards
    Presentation's date: 2010-04-11
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Modelling of pool fires

     Casal Fabrega, Joaquim; Demichela, Micaela; Pirani, Roberta
    European Meeting on Chemical Industry and Environment
    Presentation's date: 2010-05-18
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Risk-based optimization of the design of on-shore pipelines shutdown systems

     Medina, Héctor; Arnaldos Viger, Josep; Casal Fabrega, Joaquim; Bonvicini, Sarah; Cozzani, Valerio
    European Meeting on Chemical Industry and Environment
    Presentation's date: 2010-05-18
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Environmental risk associated to textile materials: preliminary considerations

     Darbra Roman, Rosa Maria; AGUEDA COSTAFREDA, ALBA; Casal Fabrega, Joaquim
    Risk-based Management of Chemicals and Products in a Circular Economy at a Global Scale: International Workshop
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Risk-based optimization of the design of onshore pipelines shutdown systems

     Medina, H.; Arnaldos Viger, Josep; Casal Fabrega, Joaquim; Bonvicini, S.; Cozzani, V.
    European Meeting on Chemical Industry and Environment
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • The behaviour of vertical jet fires under sonic and subsonic regimes

     Palacios, Adiana; Casal Fabrega, Joaquim
    Chemical engineering transactions
    Date of publication: 2010
    Journal article

     Share Reference managers Reference managers Open in new window