Consequence modelling of a hydrogen explosion in a compressor shelter

Abstract. The aim of this study was to model the overpressure effects of a vapour cloud explosion from a significant hydrogen leakage in a compressor shelter. Modelling was performed with the FLACS software for three different cases: Model1, Model2 and Model3. Model1 covered only the compressor shelter, and its surroundings without process equipment and buildings. Model2 included the compressor shelter, surrounding diesel producing unit and a control building. Model3 included the process area with a radius of 100 metres from the compressor shelter. Each model had the same modelling area, computational mesh (grid), and scenario settings in FLACS. The hydrogen leakage was modelled (dispersion simulation) to examine the effects of two Pasquill weather conditions (2F and 5D) and three different wind directions on the formation and dispersion of a vapour cloud. Based on the results, the worst case dispersion scenario was chosen for each model. The dispersion scenario with the largest flammable vapour cloud (volume and mass) was chosen. Explosion simulations were performed with an equivalent stoichiometric gas cloud based on the volume of the conservative Q8 cloud. Explosion simulations were also run with Q9 clouds which are less conservative than Q8 clouds. The worst case scenario was selected for each case based on the highest overpressure and pressure impulse. Build up overpressures and pressure impulses were measured with monitor points located at several places throughout the model (e.g. nearby process area and control building). The locations of the monitor points remained the same in each model. The FLACS software used in this study showed that not only the location of the ignition points and volume of the blockage ratio but also the mass of a flammable vapour cloud have a significant effect on the magnitude of the explosion overpressures and pressure impulses. The maximum overpressures were measured in the compressor shelter in Model2 (4.4 bar(g)) and Model3 (3.7 bar(g)) with pressure impulses of 4770 Pas (Model2) and 4400 Pas (Model3). The masses of the flammable vapour clouds were 140 kg in Model2 (cloud volume 7500 m³) and 138 kg in Model3 (cloud volume 7400 m³). The maximum values measured at the control building were in Model1 (0.5 bar(g) and 1650 Pas) where the mass and volume of the flammable vapour cloud were 160 kg and 8200 m³. This work also showed that the choice of an equivalent stoichiometric gas cloud has a very significant influence on worst case scenario selection since overpressures and pressure impulses varied according to the cloud volume (significantly higher overpressure effects in Q8 cloud than in Q9 cloud). A hydrogen vapour cloud explosion in a compressor shelter can cause a major accident with severe personal injuries, major equipment and structural damage, production interruption and significant financial damage.Tiivistelmä. Tämän työn tarkoituksena oli mallintaa FLACS-ohjelmistolla kompressorihallissa tapahtuva merkittävä vetyvuoto ja sen jälkisyttymisestä aiheutuvat ylipainevaikutukset. Mallintaminen suoritettiin yhteensä kolmelle eri tapaukselle: Model1 mallinnusalue kattoi kompressorihallin ja ympäröivän ympäristön ilman prosessilaitteita ja rakennuksia, Model2 mallinnusalue kattoi kompressorihallin lisäksi dieseltuotetta tuottavan yksikön sekä keskusvalvomorakennuksen ja Model3 alue kattoi kompressorihallista 100 metrin säteen sisällä olevan prosessialueen. Jokaisessa tapauksessa oli sama mallinnuspinta-ala, laskentaverkko sekä lähtötiedot/parametrit. Ensiksi mallinnettiin vetyvuoto (dispersiosimulointi), jossa tarkasteltiin kahden eri Pasquill sääolosuhteen (2F ja 5D) ja kolmen eri tuulensuunnan vaikutusta kaasupilven muodostukseen ja leviämiseen kompressorihallissa ja sen ympäristössä. Saatujen tulosten perusteella valittiin jokaisen mallin kohdalla se dispersioskenaario, jossa muodostui suurin (syttymiskelpoisen pilven massa ja tilavuus) syttymiskelpoinen kaasupilvi. Seuraavaksi tälle kaasupilvelle simuloitiin vetykaasun räjähdysskenaario. Räjähdyssimuloinnissa selvitettiin merkittävimmät ylipainevaikutukset sekä paineimpulssit ja syttymispisteiden vaikutusta muodostuviin ylipaineisiin. Räjähdyksen ylipainevaikutuksia ja impulssia monitoroitiin mallinnusalueen eri kohdissa (mm. läheinen prosessialue ja keskusvalvomorakennus). Näissä määritettiin maksimiylipaineet ja paineimpulssit, joita mitattiin eri kohdin mallinnusaluetta. Räjähdyssimuloinnissa käytettiin stoikiometrista kaasupilveä, joka perustui konservatiiviseen Q8 pilven tilavuuteen. Räjähdyssimulointeja tehtiin myös Q9-pilvillä, joka on vähemmän konservatiivinen pilvityyppi FLACS työkalussa. Räjähdyssimuloinneista kunkin tapauksen kohdalla ääritapausskenaarioksi valittiin se tapaus, jossa muodostui suurimmat ylipainevaikutukset sekä paineimpulssit. Työssä käytetyn FLACS-ohjelman avulla osoitettiin, että syttymispisteiden sijainnin ja estetiheyden lisäksi myös syttymiskelpoisen pilven massalla on merkittävä vaikutus kaasupilviräjähdyksen ylipainevaikutuksen suuruuteen. Maksimiylipaineet mitattiin kompressorihallissa mallinnusskenaarioissa Model2 (4.4 bar(g)) ja Model3 (3.7 bar(g)). Paineimpulssit olivat näissä tapauksissa 4770 Pas (Model2) ja 4400 Pas (Model3). Syttymiskelpoisen pilven massa ja tilavuus olivat 140 kg ja 7500 m³ (Model2) sekä 138 kg ja 7400 m³ (Model3). Valvomorakennukseen kohdistuvat maksimiarvot mitattiin mallinnusskenaariossa Model1 (0.5 bar(g) ja 1650 Pas), jossa syttymiskelpoisen pilven massa ja tilavuus olivat 160 kg ja 8200 m³. Tämä työ osoitti, että ekvivalenttisen stoikiometrisen pilven valinnalla (Q8 ja Q9) on erittäin merkittävä vaikutus ääritapausskenaarion valinnassa, sillä ääritapausskenaario vaihteli pilvestä riippuen. Vetykaasupilviräjähdys kompressorihallissa voi aiheuttaa suuronnettomuuden, joka aiheuttaa vakavia henkilövahinkoja, merkittäviä laite- ja rakennevaurioita, tuotannon keskeytymisen sekä huomattavia taloudellisia tappioita

Nanocrystals of Ni doped ZnO semiconductor by Sol-Gel combustion method

Nanoparticles of the system Zn0.95Ni0.05O were prepared by sol gel self- combustion method and a study of their structural, optical andmagnetic properties were conducted. X-ray diffraction study shows a hexagonal wurtzite structure for the nanocompound. The formation ofthe wurtzite structure in Ni doped ZnO was further confirmed by Fourier transform infra-red spectrometry. Transmission electron microscopyrevealed an average size of 31 nm for the particles. Optical absorption spectra shows that the band energy of Zn0.95Ni0.05O powders is about2.54 eV at room temperature. A study of the magnetic properties of the nanopowders of ZnO: Ni, reveals paramagnetic behavior, withinteraction ferromagnetic between particles.Fil: Carrero Lobo, Aneely Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Los Andes; VenezuelaFil: Sagredo, V.. Universidad de Los Andes; VenezuelaFil: Larionova, J.. Université Montpellier II; Franci

Simultaneous spectrophotometric determination of chromium(VI) and iron (III) by H-point standard addition method

In this work the possibility of simultaneous spectrophotometric determination of chromium (VI) and iron (III) in alloys with help of the mixed organic reagent (diphenylcarbazide and 1,10-phenanthroline) is studied. We have applied Н-point standard addition method to determine concentrations of chromium (VI) and iron (III) from the mixture. The pure signals of complexes of chromium (VI) with diphenylcarbazide and iron (III) with the 1,10-phenanthroline and their calibration plots are previously carried out. We established the possibility of simultaneous determination of chromium (VI) and iron (III) in the different concentration ranges by Н-point standard addition method. Correctness of determination of concentration by means of the offered technique is proved by "added-found" method for a series of mixtures with different ratios of concentration of chromium (VI) and iron (III). It is founded that the error of determination of concentration doesn't exceed 33 %.

Consumption of import: Evidence from industrialized countries

Consumption of imported goods by households has an influence of external and domestic demand value and is one of the components of gross domestic product. Differentiation of demand for imported goods is due to a number of internal and external environment factors. There can be identified such external determinants as inflation rate, exchange rate, social guarantees, credit availability. Internal factors influencing consumer behavior of households are socio-economic and demographic characteristics of a household such as the number of household members, their socio-economic status, employment, income, place of residence. The main factors of the increase in imports commonly believed to be the growth of real money incomes and strengthening of the national currency. The increase in the welfare of the population leads to creation of effective demand, and strengthening of the national currency results in that the imported goods initially valued in foreign currencies become cheaper what in turn increases the propensity to purchase imported goods. The purpose of the study is to analyze the characteristics of household demand for imported goods in the industrialized countries. In the course of analysis of data on industrialized countries in the period from 2000 to 2014 it is proposed to use econometric and statistical methods

Analysis of human capital level and inequality interrelation

© 2015, Mediterranean Center of Social and Educational Research. All rights reserved. This article presents the results of the relationship between human capital and inequality in income distribution in European countries analysis. To test the hypothesis of research the cluster approach was applied, that allowed to divide investigated countries into 9 clusters. The study has concluded that countries with high level of human capital are characterized by a lower degree of inequality in income distribution. Correlation and regression analysis confirm the presence of feedback between the HDI and Gini index

Economic behavior of households: Cross-country comparison

The basic hypothesis of the research is that social capital has an effect on saving behavior and quality of life of households in different countries. We have used correlation and hierarchical cluster analysis as the methods of research and analyzed the indicators for the 29 countries with different levels of economic development. The cluster analysis has allowed to distribute the countries to the groups with similar meanings of household saving rate and social capital index, life expectancy or Gross national income (GNI)

Household characteristics as the determinants of their consumption expenditure

© 2016 Taylor & Francis Group, London.The main aim of this study is to analyze the impact of household characteristics such as income, urbanization degree, types of households, and work status of reference person on the differentiation of household consumption expenditure based on European countries as an example. The study has identified the essential characteristics of households, the general trends and patterns in the dynamics of household consumption expenditure

Qualitative assessment of banking system institutional environment

The research indicates that the institutional environment is a key feature of the banking system in different countries. The aim of the research is to examine banking system institutional environment from 18 countries of Eurozone. We have used index and grouping tests as the methods of research and analyzed the indicators for the countries with different state of financial system. Due the investigation countries were divided into three groups with particular features which characterizing internal institutional environment of banking system and allowing making international comparison

Evaluation of regional infrastructure

Aninfrastructure development level has a significant impact on the economy of a region as a whole, especially in the territorial and sectoral organization of production. The purpose of the study is to identify problems in the infrastructure of regions, and todevelopthe ranking of regions. The object of the study were 85 administrative regions of the Russian Federation. To assess the infrastructure of the regions there has been developed a technique that includes 8 blocks uniting 37 socio-economic indicators characterizing the level of logistics, transport, social, financial, investment, innovation, energy and telecommunications infrastructure availability. Application of linear scaling method has allowed comparison of data by regions and calculate the integral index of infrastructure availability on the basis of which we can determine the extent of disadvantages of one region from another. The ranking of the entities of the Russian Federation under the calculated integral index of infrastructure availabilitywill allow identifying regions with high, medium and low value of the indicator. The testing of the developed methodology for comparison regions in terms of infrastructure development level has revealed problem areas in subjects in the sphere of creation and development of infrastructure in terms of attracting manufacturing companies to their territory. Results of the study showed that there is considerable differentiation of entities of the Russian Federation by the level of infrastructure availability what must be considered when developing a territorial development programs.The proposed method of estimation of infrastructure availability can be the basis for drawing up a regional ranking by the level of infrastructure availability and investment attractiveness