8,855 research outputs found

    Characterization of Catalytic Porous Medium Using Platinum for Micro-combustion Application

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    In this study, catalytic alumina porous medium has been fabricated by using platinum as an active material for micro-combustion application. Platinum has been deposited onto porous medium surface via wet impregnation method. The porous medium undergoes surface modification process via wash coating method using gamma alumina (γ-Al2O3) solution, before being impregnated with platinum in order to increase the surface area. The surface morphology of porous medium entirely changes from smooth “solid-rock” into rough “sand-like” after the wash coating process. The amount of platinum deposited onto the treated porous medium is 1.66 wt.%. LPG combustion analysis shows that the combustion is successfully occur inside the catalytic porous media with overall efficiency of 71%

    Ultra-lean methane combustion in porous burners

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    Ultra-lean methane combustion in porous burners is investigated by means of a pilot-scale demonstration of the technology supported by a computational fluid dynamics (CFD) modelling study. The suitability of porous burners as a lean-burn technology for the mitigation of methane emissions is also evaluated. Methane constitutes 14.3% of total global anthropogenic greenhouse gas emissions. The mitigation of these emissions could have a significant near-term effect on slowing global warming, and recovering and burning the methane would allow a wasted energy resource to be exploited. The typically low and fluctuating energy content of the emission streams makes combustion difficult; however porous burners—an advanced combustion technology capable of burning low-calorific value fuels below the conventional flammability limit—are a possible mitigation solution. A pilot-scale porous burner is designed expressly for the purpose of ultra-lean methane combustion. The burner comprises a cylindrical combustion chamber filled with a porous bed of alumina saddles, combined with an arrangement of heat exchanger tubes for preheating the incoming methane/air mixture. A CFD model is developed to aid in the design process. Results illustrating the operating range and behaviour of the burner are presented. Running on natural gas, the stable lean flammability limit of the system is 2.3 vol%, a considerable extension of the conventional lean limit of 4.3 vol%; operating in the transient combustion regime allows the lean limit to be reduced further still, to 1.1 vol%. The heat exchanger arrangement is found to be effective; preheat temperatures of up to 800K are recorded. Emissions of carbon monoxide and unburned hydrocarbons are negligible. The process appears stable to fluctuations in fuel concentration and flow rate, typically taking several hours to react to any changes. A CFD model of the porous burner is developed based on the commercial CFD code ANSYS CFX 12.0. The burner is modelled as a single 1-dimensional porous domain. Pressure loss due to the presence of the porous solid is accounted for using an isotropic loss model. Separate energy equations for the gas and solid phases are applied. Models for conductive heat transfer within the solid phase, and for convective heat transport between the gas and solid phases, are added. Combustion is modelled using a finite rate chemistry model; a skeletal mechanism for ultra-lean methane combustion is developed and incorporated into the model to describe the combustion reaction. Results from the model are presented and validated against experimental data; the model correctly predicts the main features of burner behaviour. Porous burners are found to show potential as a methane mitigation technology

    Ultra-lean methane combustion in porous burners

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    Ultra-lean methane combustion in porous burners is investigated by means of a pilot-scale demonstration of the technology supported by a computational fluid dynamics (CFD) modelling study. The suitability of porous burners as a lean-burn technology for the mitigation of methane emissions is also evaluated. Methane constitutes 14.3% of total global anthropogenic greenhouse gas emissions. The mitigation of these emissions could have a significant near-term effect on slowing global warming, and recovering and burning the methane would allow a wasted energy resource to be exploited. The typically low and fluctuating energy content of the emission streams makes combustion difficult; however porous burners—an advanced combustion technology capable of burning low-calorific value fuels below the conventional flammability limit—are a possible mitigation solution. A pilot-scale porous burner is designed expressly for the purpose of ultra-lean methane combustion. The burner comprises a cylindrical combustion chamber filled with a porous bed of alumina saddles, combined with an arrangement of heat exchanger tubes for preheating the incoming methane/air mixture. A CFD model is developed to aid in the design process. Results illustrating the operating range and behaviour of the burner are presented. Running on natural gas, the stable lean flammability limit of the system is 2.3 vol%, a considerable extension of the conventional lean limit of 4.3 vol%; operating in the transient combustion regime allows the lean limit to be reduced further still, to 1.1 vol%. The heat exchanger arrangement is found to be effective; preheat temperatures of up to 800K are recorded. Emissions of carbon monoxide and unburned hydrocarbons are negligible. The process appears stable to fluctuations in fuel concentration and flow rate, typically taking several hours to react to any changes. A CFD model of the porous burner is developed based on the commercial CFD code ANSYS CFX 12.0. The burner is modelled as a single 1-dimensional porous domain. Pressure loss due to the presence of the porous solid is accounted for using an isotropic loss model. Separate energy equations for the gas and solid phases are applied. Models for conductive heat transfer within the solid phase, and for convective heat transport between the gas and solid phases, are added. Combustion is modelled using a finite rate chemistry model; a skeletal mechanism for ultra-lean methane combustion is developed and incorporated into the model to describe the combustion reaction. Results from the model are presented and validated against experimental data; the model correctly predicts the main features of burner behaviour. Porous burners are found to show potential as a methane mitigation technology

    Syngas Fuel Production from Carbonaceous Feedstocks Using Hybrid Porous Media

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    During the last years, hybrid porous media reactors have been developed aiming to partially oxidize solid and gaseous fuels to produce reducing gases. The gases produced are mainly composed of hydrogen (H2) and carbon monoxide, among other products of gasification. This hybrid process combines inert porous media (IPM) combustion and gasification of solid fuels by replacing a fraction of the inert solid volume with a solid fuel. The gaseous mixture is produced from carbon-rich reactants exposed to the high temperatures of filtration combustion. Experimental results from different solid fuels (coal, biomass, and others) and gaseous fuels (natural gas (NG), propane, and others) are presented, with detailed analysis of high temperatures (between 900 and 1800 K), velocities, and product gas composition of the combustion waves, which is able to produce [H2]/[CO] ratios from 0.2 to 10

    Biomassapohjaisen kaasutuskaasun suodatus korkeissa lämpötiloissa

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    Literature part of the thesis concerns the combination of biomass gasification process and Fischer-Tropsch synthesis, which can be used to produce liquid biofuels. Cleaning of the gasification gas by filtration and tar reforming is the focus of the work. It is essential to develop an effective and profitable process concept for hot gas cleaning to achieve competitive biofuel production route. The main challenge is to develop stable filtration process that is resistant towards tar components and carbon formation at high temperatures. Heavy tar compounds are decomposed either in the filtration unit or in the following reformer unit. At high temperatures, formed filter cakes are sticky and cleaning of filter medium is challenging. Additionally, the contaminants in the gasification gas complicate the usage of some catalysts. Different catalysts have been studied for gasification gas cleaning applications and catalyst modifications have been tested including different support and promoter additives. The aim of the experimental part of the thesis was to study the suitability of novel metal filters for hot gasification gas cleaning purpose. Furthermore, the Atomic Layer Deposition (ALD) coating technique was tested in the experiments with nickel catalyst and alumina support. Different process conditions and gas face velocities were studied. It was also tested how sulfur in the gas affects the process. The best result was 55 % conversion for naphthalene and it was achieved with the combination of nickel catalyst and alumina support at 5 bar and at 900 ˚C. The applied gas face velocity was 15 cm/s. However, at these conditions, there occurred carbon formation on the surfaces and finally the reactor was blocked. Without a nickel catalyst, the best conversion achieved for naphthalene was 29 % at same process conditions with the gas face velocity of 12 cm/s. Without a catalyst, less carbon was accumulated on the filter surface and there were no problems related to the reactor clogging.Diplomityön kirjallisuusosio käsittelee nestemäisten polttoaineiden valmistusta biomassan kaasutuksen ja Fischer-Tropsch-synteesin avulla. Työ keskittyy tutkimaan kaasutuskaasun puhdistuslinjan suodatus- ja reformointiprosesseja. Merkittävä haaste biomassan valmistusprosessin tehokkuuden parantamisessa on saavuttaa stabiili suodatusprosessi. Suodatusprosessin tulisi kestää vaativat prosessiolosuhteet sekä kaasun sisältämien epäpuhtauksien vaikutukset. Raskaat tervayhdisteet hajotetaan joko suodatusvaiheessa tai sitä seuraavassa reformointiyksikössä. Korkeissa lämpötiloissa muodostuvat suodatuskakut ovat tyypillisesti tahmeita ja suodatin on hankala puhdistaa. Korkeissa lämpötiloissa hiiltä kertyy prosessilaitteen pinnoille, mikä voi lopulta johtaa reaktorin tukkeutumiseen. Monia erilaisia katalyyttejä on tutkittu kuuman kaasutuskaasun puhdistamista varten ja katalyyttejä on muokattu esimerkiksi erilaisten tuki- ja lisämateriaalien avulla. Kokeellisen osion tarkoituksena oli testata uusien metallifilttereiden soveltuvuutta kaasutuskaasun kuumasuodatusta varten. Lisäksi koeajoissa testattiin atomikerroskasvatuksella valmistettuja nikkeliä sekä alumiinioksidia sisältäviä katalyyttipinnoituksia. Myös erilaisia prosessiolosuhteita sekä kaasun pintanopeuksia tutkittiin. Koeajojen avulla saatiin myös lisätietoa rikkiyhdisteiden vaikutuksesta nikkelikatalyytin toimintaan. Paras naftaleenin hajoamiselle saavutettu konversio oli 55 % ja se saavutettiin paksuimmalla nikkelipinnoituksella alumiinioksidin päällä 5 bar paineessa sekä 900 ˚C lämpötilassa. Kaasun pintanopeus oli 15 cm/s. Näissä olosuhteissa reaktorin hiiltyminen aiheutti kuitenkin ongelmia ja neljän tunnin ajon jälkeen reaktori tukkeutui. Ilman katalyyttiä korkein saavutettu naftaleenin konversio oli 29 % samoissa olosuhteissa, mutta 12 cm/s pintanopeudella. Ilman katalyyttiä, hiiltä kertyi reaktoriin huomattavasti vähemmän eikä reaktorin tukkeutumista tapahtunut

    Emission Control Technology

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    Non-Catalytic Reforming of Biogas in Porous Media Combustion

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    Rich combustion of biogas inside an inert porous media reactor was investigated to evaluate hydrogen and syngas production. Temperature, velocities, and product gas composition of the combustion waves were analysed, while varying its filtration velocity, for a range of equivalence ratios (φ) from φ = 1.0 to φ = 3.5. A numerical model based on comprehensive heat transfer and chemical mechanisms was found to be in a good qualitative agreement with experimental data. Partial oxidation products of biogas (H2 and CO) were dominant on rich combustion. Different gas mixtures of methane and carbon dioxide, which simulated synthetic biogas, and the addition of a varying fraction of water steam were experimentally analysed. It was observed that an increasing steam to carbon ratio (S/C) improved hydrogen and syngas production. The non-catalytic process investigated results in an effective biogas upgrading, and to be essentially higher than under natural gas filtration combustion

    Multilayer Porous Composite From Waste Glass for Water Filtration

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    Multilayer porous composite have been produced through the heating process at temperature T=700oC for 2.5 h. Single layered porous composite was made with a varied mass percentage of from PEG polymer 1% to 10%. Double-layered porous composite were made by the arrangement of porosity (4:3)%, (4:2)% and (3:2)%, while the three-layers porous composite have an arrangement (4:3:2)%. Performance of multilayer porous composite for water filtration with pollutants of methylene blue 100 ppm was estimated from the absorbance spectrum. Rejection of methylene blue pollutants from single layered porous composite increases when the fraction of PEG polymer tend to be smaller in the matrix. Meanwhile, the double layered porous composite has a degradation of methylene blue pollutants are better than one layer. Triple layered porous composite have good performance for the water filtration where all the pollutants of methylene blue be able to be filtered. Komposit pori berlapis telah dihasilkan dengan proses pemanasan pada temperatur T=700oC selama 2.5 jam. Komposit pori satu lapis dibuat dengan variasi persen massa polimer PEG 1% hingga 10%. Komposit pori dua lapis dibuat dengan susunan porositas (4:3)%, (4:2)% dan (3:2)%, sedangkan komposit pori tiga lapis memiliki susunan porositas (4:3:2)%. Kinerja komposit pori berlapis untuk filter air dengan polutan methylene blue 100 ppm diestimasi dari spektrum absorbansi. Rejeksi polutan methylene blue dari komposit pori satu lapis meningkat saat fraksi polimer PEG cenderung lebih kecil dalam matrik komposit. Sedangkan, komposit pori dua lapis memiliki kemampuan untuk degradasi polutan methylene blue yang lebih baik dari satu lapis. Komposit pori tiga lapis memiliki kinerja yang baik untuk filter air dimana seluruh polutan methylene blue mampu disaring

    Reduction of Particulate Matter Emissions in EU Inland Waterway Transport

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    In September 2014, the European Commission adopted a proposal on new requirements relating to emission limits and type-approval for non-road engines. The introduction of a new emission stage (Stage V) establishes extremely tight limits for particulate matter emissions for mobile non-road applications, including inland waterway vessels. These new emission limits will eventually require many ships to apply efficient exhaust gas after-treatment technology. The aim of this study was to find out which kinds of exhaust gas after-treatment solutions could fulfil these tightening particulate emission standards in EU inland navigation. A marine dual fuel engine was used as an example. The engine can be run both with gas and diesel fuel. The first part of the study consists of a literature review of various exhaust gas after-treatment technologies. This part serves as a general technology guide for particulate emission abatement from diesel engines. In the second part of the study, different supplier technologies and solutions were evaluated. The targets for particulate filtering system were defined and a specific inquiry was sent to potential suppliers. Based on the replies, passive diesel particulate filter systems with catalytic coating or/and an upstream diesel oxidation catalyst can be regarded as the primary choice for particulate emission control in inland navigation. This study was conducted as part of the EU Hercules-2 research and development programme, aimed at fostering environmentally sustainable and more efficient shipping.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format
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