No description available.

No description available.

No description available.

No description available.

No description available.

Volatile sulfur compounds are cause of concern because, when present in high concentrations, they constitute a danger for health because of their strong toxicity. Furthermore, for low concentrations, they are often a cause of complaint, because of their low odor threshold. In this context, the purpose of this Thesis is to evaluate a new technology for the abatement of sulfur-based malodorous compounds. The investigated technology consists in the use of ozone generating low-pressure UV mercury lamps, operating at room temperature. Hydrogen sulfide is often found in industrial processes, (e.g. WWTPs (Wastewater Treatment Plants), leather production, sewage treatment, garbage disposal, etc). Moreover, it presents both a very high toxicity a low odor threshold. Thus, due to its high representativeness of the case, hydrogen sulfide was chosen as reference compound for the purposes of this project. In order to evaluate a wide range of cases, several experiments using different residence times, humidity contents and inlet concentrations of the pollutant were conducted. The obtained results show that this technology generally presents discrete conversion efficiencies, although not suffcient to be used as freestanding process. For this reason, a pretreatment is revealed to be necessary. The best conversion efficiency was obtained for low flow rates and high moisture content. At the end of the project, as side-study, a possible pretreatment using an adsorbent bed constituted by granular ferric oxide was evaluated.

Exposure to diesel engine exhaust is linked to chronic and acute illness. In underground mines, workers can be exposed to high concentrations for extended periods of time. Therefore, Mine Safety and Health Administration (MSHA) enforces personal exposure and engine emission limits. These regulations target just the solid portion of diesel exhaust, known as diesel particulate matter (DPM). The majority of DPM mass is attributed to particulate organic carbon (POC) and elemental carbon (EC). Total carbon (TC) is the sum of POC and EC and currently used as the surrogate to represent DPM as a whole. The NIOSH Method 5040 is the standard sample collection and analysis procedure. It outlines collection of submicron particulate matter samples on a quartz filter then measurement of POC and EC using a thermal-optical analysis. Error in DPM measurement occurs when volatile organic carbon (VOC) sorbs onto the particulate matter deposit and filter resulting in a positive sampling artifact. To correct for this, a dynamic blank method with two quartz filters (i.e., primary and secondary) in tandem is used. However, the accuracy of the dynamic blank correction method is dependent on equal sorption of VOC onto each filter. Observed instances of higher VOC on the secondary filter result in underestimated POC measurements and in some cases negative POC. The work presented in this thesis investigates the sources of VOC interference in particulate matter sampling and possible solutions. Three existing datasets containing information from blank samples and laboratory and field DPM samples were analyzed to look into instances of higher VOC sorption onto the secondary filter. Negative total POC results were limited to blank samples, but negative results for the POC of individual isotherms were observed in blank and DPM samples. A follow-up study looked into the possibility of sampling materials as a source of VOC that preferentially sorbs onto the secondary filter. Blank samples were assembled to test five sampling materials (i.e., two types of sample cassette, cellulose support pads, impactor cassettes, and impactors). In addition, sample storage conditions (i.e., temperature and duration) were tested for their impact on VOC sorption. It was discovered that all of the sample materials tested contributed VOC and, as expected, higher storage temperatures and longer storage durations increase the amount of VOC. Preferential sorption onto the secondary filter was observed in most conditions as well. A field study explored thermal separation of VOC and POC as a possible alternative to the dynamic blank correction method. Two sets of DPM samples were collected from two locations in an underground stone mine and one set of ambient particulate matter samples was collected from a highly trafficked truck stop. The temperature of 175°C was used for this preliminary investigation. The effectiveness of a temperature separation may depend on sample location. To better understand VOC and POC evolution characteristic, further testing with a wide range of sample mass and composition as well as different temperatures is suggested. It seems unlikely that a correction method using a separation temperature would be more effective than the standard dynamic blank in occupational DPM monitoring. The work presented in this thesis highlights the difficulty in accurately measuring POC. / Master of Science / Diesel Particulate matter (DPM) is the solid portion of diesel exhaust and can cause chronic and acute illness. Underground miners can regularly be exposed to high concentrations of DPM over long periods of time, therefore DPM must be monitored. Total Carbon (TC) is the sum of particulate organic and elemental carbon (POC and EC) and is used as the surrogate measurement to represent DPM. The standard method of DPM sample analysis is subject to volatile organic carbon (VOC) interference, therefore a dynamic blank correction is used. However, in some cases, the dynamic blank over- or under-corrects. This thesis presents studies to better understand the source(s) of VOC interference and possible solutions. Three existing datasets containing information from blank samples and laboratory and field DPM samples were investigated for instances of VOC interference resulting in an overcorrection. Such instances were limited to blank and low mass samples. A field study looked into the possibility of sampling materials as a source of VOC that may cause overcorrection when using the dynamic blank method. Blank samples were assembled to test five sampling materials as well as various sample storage conditions. It was discovered that all of the sample materials tested contributed VOC and, as expected, higher storage temperatures and longer storage durations increase the amount of VOC. A second field study explored thermal separation of VOC and POC as a possible alternative to the dynamic blank correction method. Two sets of DPM samples were collected from two locations in an underground stone mine and one set of ambient particulate matter samples was collected from a highly trafficked truck stop. The temperature of 175°C was used for this preliminary investigation. Results indicate that the effectiveness of temperature separation may depend on sample concentration and composition. To better understand VOC and POC evolution characteristic, further testing with a wide range of sample mass and composition, as well as, different temperatures is suggested. The work presented in this thesis highlights the difficulty in accurately measuring POC.

Η παρούσα διπλωματική εργασία πραγματεύεται την ανάλυση και σχεδίαση απευθείας ελέγχου πραγματικής και άεργου ισχύος σε αιολικό σύστημα με επαγωγική γεννήτρια διπλής τροφοδοσίας (Doubly-Fed Induction Generator, DFIG). Κύριος σκοπός της εργασίας είναι η εξαγωγή ενός κατάλληλου δυναμικού μοντέλου του συστήματος, το οποίο περιέχει ως καταστάσεις τις ισχείς. Επιπλέον, μέσω του διανυσματικού ελέγχου με προσανατολισμό στην τάση του δικτύου (Voltage-Oriented Control, VOC) επιτυγχάνεται ο απευθείας έλεγχος των ισχύων χρησιμοποιώντας αναλογικό-ολοκληρωτικούς (Proportional-Integral, PI) ελεγκτές, επιβάλλοντας με αυτόν τον τρόπο την επιθυμητή μεταβατική συμπεριφορά. Τελικά, η ανάλυση και η συμπεριφορά του αιολικού συστήματος επιβεβαιώνεται με τα αποτελέσματα της εξομοίωσης σε περιβάλλον MATLAB/Simulink. Ειδικότερα, στο κεφάλαιο 1 παρουσιάζονται το ενεργειακό πρόβλημα και τα διάφορα είδη ανανεώσιμων πηγών ενέργειας. Στο κεφάλαιο 2 αναφέρονται τα συστήματα αιολικής ενέργειας. Πιο συγκεκριμένα, περιγράφονται οι κυριότεροι τύποι ανεμογεννητριών και η δομή της, οι γεννήτριες και οι συσκευές ηλεκτρονικών ισχύος που χρησιμοποιούνται σε ένα αιολικό σύστημα, καθώς και ο μηχανικός έλεγχος ισχύος που μπορεί να εφαρμοστεί. Στη συνέχεια, στο κεφάλαιο 3 πραγματοποιείται η ανάλυση του αιολικού συστήματος με την DFIG όπου εξάγεται με την βοήθεια του μετασχηματισμού Park, το ζητούμενο μαθηματικό μοντέλο. Έπειτα, στο κεφάλαιο 4 αναφέρονται οι μέθοδοι ελέγχου που χρησιμοποιούνται στις ανεμογεννήτριες, εφαρμόζεται ο VOC στο αιολικό σύστημα που μελετάται και σχεδιάζονται οι απαιτούμενοι ελεγκτές PI ώστε να ελεγχθεί η ισχύς μέσω των δύο μετατροπέων ισχύος. Τέλος, στο κεφάλαιο 5 παρουσιάζεται η εξομοίωση του συστήματος και τα αποτελέσματα που προέκυψαν. / This diploma thesis deals with the analysis and design of a direct active and reactive power control system for a Doubly-Fed Induction Generator (DFIG) wind power system. The main purpose of this thesis is to extract a suitable dynamic model of the system that contains as states the active and reactive power. In addition, the direct control of the active and reactive power is achieved through voltage-oriented control (VOC) and the use of PI controllers, imposing the desirable transient behavior. Finally, the analysis and the performance of the wind system are verified through simulation results in MATLAB/Simulink. Specifically, in chapter 1 the energy problem and the different types of renewable energy sources are presented. The second chapter deals with the wind energy systems. In particular, the main types and the structure of wind turbines, the generators, the power electronic devices and the mechanic power control used in a wind power system are presented. Then, in chapter 3 the DFIG wind system is analysed and the required mathematical model is extracted using Park’s transformation. Next, in the fourth chapter the control methods for a wind turbine are presented and, using the VOC in the wind power system studied, the required PI controllers for the two power converters are designed. Finally, in chapter 5 the simulation results are presented and conclusions are drawn.

<p>In this study potential health risks for employees in connection with handling of bottom ash and bottom ash water at a Municipal Waste Incineration (MWI) plant have been investigated. Air surrounding the bottom ash and the bottom ash water has been examined. MWI is one of the primary ways to manage solid household waste, and bottom ash is the main solid residue produced by the incineration process. Bottom ash constitutes about 15-20% of the original waste. The bottom ash is extinguished in a water bath (bottom ash water).</p><p>The study was carried out in a MWI plant in Karlstad, Sweden. The plant is equipped with a grate furnace with a capacity of 7 tonnes per hour. Annually about 50 000 tonnes are incinerated at the plant.</p><p>Levels of airborne particles, metals present in the airborne particles, volatile organic compounds (VOC), and phosphine were measured in the air. Analysis of the bottom ash water including: pH, total phosphorus, ammonium, chemical oxygen demand (COD), suspended solids, and bacteria were also carried out. Further, a questionnaire was distributed to investigate how the workers at the MWI plant re°ected on health when working.</p><p>The results showed that the levels of airborne particles, metals and VOC did not pose any major health risks. The bacterial analysis demonstrated very low concentrations of bacteria in the water and thus that the bacteria posed no risk for the workers. The phosphine measurements did not result in levels exceeding the Swedish threshold limit value. However, the method used in this study was not well-tested in these sorts of environments and the results implied that higher levels of phosphine might be present. The conclusion from the questionnaire was that there is a concern about health risks in connection with certain tasks at the plant.</p> / <p>På Hedenverket, Karlstads Energi AB, förbränner man årligen cirka 50 000 ton hushålls- och verksamhetsavfall. En av restprodukterna av förbränningen kallas slagg (bottenaska) och utgör ca 15-20% av det inmatade avfallet. Slaggen släcks i ett vattenbad under själva pannan (slaggsläckningsbad) och matas sedan ut, via ett skakbord för reduktion av vatten, till containrar innan det slutligen körs på deponi.</p><p>Syftet med det här projekt var att utreda om det föreligger några hälsorisker vid arbete kring slaggen och slaggsläckningsvattnet. För att skapa en bild av möjliga hälsorisker gjordes en inledande studie av tidigare utredningar, mätningar gjorda på avfallsförbränningsanläggningar runt om i Svergie och vad kemiska och biologiska hälsorisker innebär. Även lagstiftning på området har berörts.</p><p>Med tidigare utredningar och mätningar samt diskussioner som grund utfördes mätningar av damm, metallhalter i damm, VOC och fosfin i luften samt en analys av slaggvattnet och bakterier i slaggvattnet. För att skapa en uppfattning av hur personalen, som arbetar med driften, upplever sin arbetssituation ur hälsorisksynpunkt genomfördes även en enkätundersökning.</p><p>Resultaten av undersökningarna på Karlstads Energi AB visade att varken damm, metaller eller VOC utgör någon hälsorisk. Bakterieprovtagningen av slaggsläckningsvattnet visade på mycket låga halter av bakterier och bakterier kan därför inte sägas utgöra någon hälsorisk.</p><p>Undersökningar av slaggvatten på andra anläggningar i Sverige visar däremot på höga metallhalter i slaggvattnet och det vore således inte särskilt hälsosamt att få i sig större mängder av detta. Resultaten av fosfinmätningen visar inte heller på några alarmerande nivåer, men metoden som användes är inte väl beprövad i den här typen av miljö. Resultaten kan tyda på att högre halter av fosfin förekommer, men hur höga de är inte möjligt att svara på. Fosfin är ett ämne som i små mängder kan ge upphov till bland annat illamående. I enkätundersökningen påtalades att obehag och illamående uppstºar vid längre arbeten över skakbordet och det är möjligt att fosfin kan vara en orsak till detta. Enkätundersökningen visade även att det finns en oro för hälsan vid vissa typer av arbeten på anläggningen och oro för att hälsan ska påverkas negativt på längre sikt.</p>

Deactivation of catalysts were investigated focusing on three industrial processes: 1) Selective Catalytic Reduction (SCR) for abatement of NOx from biomass combustion using V2O5-WO3 /TiO2 catalysts; 2) Catalytic oxidation of volatile organic compounds (VOC) from printing industries using a Pt/γ-Al2O3 catalyst; and 3) Ni and Pt/Rh catalysts used in steam reforming reaction of bio-syngas obtained from biomass gasification. The aim has been to simulate industrial conditions in laboratory experiments in order to comprehend influence of compounds affecting catalysts performance. Typical catalyst lifetimes in industrial processes are several years, which are a challenge when accelerating deactivation in laboratory scale experiments where possible exposure times are few hours or days. Catalysts can be introduced to deactivating compounds through different routes. The first method examined was gaseous exposure, which was applied to deactivate VOC oxidation catalyst through exposure of gaseous hexamethyldisiloxane. The second method involved wet impregnation and was used for impregnation of SCR catalyst with salt solutions. The third method was based on exposure and deposition of size selected particles of deactivating substances on the catalyst. The latter device was developed during this work. It was applied to monolithic SCR catalysts as well as to pellet catalysts intended for steam reforming of biomass gasification syngas. Deactivated SCR catalyst samples by size selected exposure method were verified and compared with SCR catalysts used in a commercial biomass boiler for 6 500 h. Evaluations of fresh and deactivated samples were investigated using BET surface area; chemisorption and temperature programmed desorption (TPD); surface morphology using Scanning Electron Microscopy (SEM) and poison penetration profile through SEM with an Electron Micro Probe Analyser (EMPA) also equipped with a energy dispersive spectrometer (EDS); chemical analysis of accumulation of exposed compounds by Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES); and influence on catalyst performance. The size selected generated particles of deactivating substances were characterized with respect to mean diameter and number size distribution through Scanning Mobility Particle Sizer (SMPS) and mass size distribution applying an Electric Low Pressure Impactor (ELPI). Results from catalyst characterization methods were useful tools in evaluation of catalyst deactivation routes. Understanding deactivation processes and impact on catalyst performance is vital for further optimization of catalysts with respect to performance and lifetime. Further research in this field can provide more resistant catalysts for application in industry leading to higher commercial benefits and further application of environmental catalysts in thermo-chemical conversion of biomass.