No description available.

This work investigates the influence of one or more OH groups present on the fuel molecule and the resultant formation of NOX emissions. Combustion of oxygenated fuels has been increasing globally and such fuels offer significant potential in the reduction of pollutant emissions. One such emission class is the oxides of nitrogen, which typically form through a combination of two regimes: the thermal and non-thermal mechanisms. While thermal NO formation can be reduced by lowering the combustion temperature, non-thermal NO formation is coupled to the fuel chemistry. An experimental and computational investigation of NOX formation in three different burner configurations and under a range of equivalence ratios and temperature regimes explored the differences in NO formation. Measurements of temperature profiles and in-flame species concentrations, utilizing both probed and non-intrusive laser based techniques, allowed for the investigation of NO formation through non-thermal pathways and the differences that exist between fuels with varying numbers of OH groups. The first burner configuration was composed of a high swirl liquid spray burner with insulted combustion chamber walls designed specifically for the combustion of low energy density fuels. In this system the combustion of alcohols and glycerol (the largest by-product of biodiesel production), along with other fuels with multiple hydroxyl groups, was studied. Measurements of the mean flame temperature and exhaust gas measurements of NOX showed significant reductions in non-thermal NO concentrations with increasing numbers of OH groups. An accompanying modeling study and detailed reaction path analysis showed that fuel decomposition pathways through formaldehyde were shown a preference due to the presence of the OH groups which resulted in reduced contributions to the hydrocarbon radical pools subsequent reductions to the Prompt NO mechanism. Two burner configurations with reduced dimensionality facilitated measurements in premixed flames for temperature and species in high and low temperature flames. These measurements included probed thermocouple temperature measurements, extractive gas sampling for NO and intermediate hydrocarbon species, and planar Laser Induced Fluorescence (LIF) measurements for 2OH-LIF thermometry, semiquantitative CH2O LIF, and quantitative NO LIF. Additionally, the simplified nature of the burner geometries allowed for the modeling of the flames incorporating detailed reaction kinetics for fuel decomposition and NOX formation. Significant reductions in NO formation were observed in comparisons of alcohol and alkane flames, resulting in up to 50% reductions in the pollutant. Computational analyses and nitrogen flux accounting allowed for the identification of the reduction in NO formation through all the known NOX formation pathways. It was observed that all of the known pathways exhibited reductions in contributions to NO formation in the presence of OH functional groups, indicating a complex coupling of fuel and NOX chemistry.

Since nitrogen oxides, NOx are harmful to human health and the environment, the International Maritime Organization, IMO has proposed reductions of the allowed amount of NOx-emissions from vessels in certain areas. The Swedish Shipowners Association together with others are critical to the suggestion. They are afraid that the cost for the installation of the reduction technique will be so expensive that the shipping business would lose competitiveness and that the goods will find other ways. In this paper different alternatives, such as NOx-reduction techniques, economical instruments of control, alternative fuels etc. to reduce NOx- emissions are described and analysed. Some alternatives are relativley new and unrealible, while others not have the potential to meet the future demands. The alternatives which are tested and proven are quite expensive and space demanding, but all alternatives can contribute.

Estágio realizado na empresa BA Vidro, S.A. - Unidade de Avintes e orientado por Sérgio Sousa / Documento confidencial. Não pode ser disponibilizado para consulta / Tese de mestrado integrado. Engenharia do Ambiente. Faculdade de Engenharia. Universidade do Porto. 2010

In this study, a regenerative thermal oxidizer (RTO) was used to test the relationship between VOC concentration and nitrogen oxides(NOx) formed, and to estimate its performance. The RTO is electrically heated and contains two 0.152 m ¡Ñ 0.14 m ¡Ñ 1.0 m (L ¡Ñ W ¡Ñ H) beds both packed with gravel particles of around 1.11 cm in average diameter to a height of 1.0 m. The bed has a void fraction of 0.416. Experiments include two phases: (1) tests to find the VOC destruction and NOx formed with DMF only in the influent air stream in the following condition: setting temperature Tset=700-900oC, flowrate Q=0.5-1.0 Am3/min, influent concentration Co=0-500ppm, shift time ts=1.5 min. and before that, to test the effect to thermal recovery efficiency and pressure drop. (2) tests to find the VOC destruction and NOx formed for the air stream with MEK/DMF mixed in the influent air stream in the following condition: setting temperature Tset=600-900oC ,flowrate Q=0.5 Am3/min, influent MEK/DMF ratio =100/100,200/100,500/100(ppm/ppm), shift time ts=1.5 min. and before that, to test the effect to thermal recovery efficiency and pressure drop. Result show : (1)there have no NOx formed in cool-bed with DMF only in the influent air stream. DMF destruction is proportional to influent concentration(low Co > high Co ) and setting temperature(900 > 800 > 700oC).NOx formed is inversely proportional to Co.(2)in the phase two Experiment, DMF destruction is proportional to add MEK in. NOx formed is inversely proportional to Co. MEK/DMF ratio is proportional to (NOx formed/DMF removed) at Tset=600oC,but not closely related during Tset=700-800oC.NO2 formation is significant at Tset=800 oC. (3)Ergun equation is suitable to estimate pressure drop of RTO.

Abstract The combustion characteristics and the pollution of the exhausting products under various designing and operating conditions are studied in this research. In our experiments, the furnace fuel is diesel oil. By adjusting the flow rate of both axial air and tangential air the different equivalence ratios and swirl numbers can be obtained. The controlling ranges of the various experimental parameters include equivalence ratio from 0.8 to 1.1, swirl number from 0 to 1.0, recirculated flue gas from 0% to 12%, and jet spray angle 45?and 80? The effect of the controlling variables on the combustion characteristics and pollutant formations within combustion chamber are studied in this reseacher. A photographic technology is used to study the flame structures to help us understanding the behaviors of the flame under various operating condition. Form the experimental results, we find that the recirculation generated by swirl influence the produce temperature and its distribution with combustion chamber. The swirl is useful for flame expanding, and increases the mixing of fuel and air, so that the complete reaction can achieve near the burner. When the jet spray angle is 80? and swirl number is 0.6, the exhaust rate of NOx in the exhaust duct is the lowest, and the combustion in combustion chamber is the best. At equivalence ratio 0.9, the effects of the flow rate of the recirculating flue gason the flame structure and the exhaust emission is not too much. Our experiments display that the optimized operating condition is jet spray angle 80? swirl number 0.6 and flue gas recirculation 8%. NO can be reduced about 15~20% in this condition. When no swirl occurs, the color of flame displays white-yellow due to the burning of soot in this region. For the condition with swirl, the color of the outside flame displays orange-yellow. In primary combustion zone, the flame exhibits the red color which is due to the radiation of CO2 and water vapor.

In this research a modified commercial boiler,which burns diesel oil,is used to study the combustion characterisics and the pollution of the exhausting products under various operating conditions.The controlling ranges of the various experimental parameters include equivalence ratio from 0.8to1.1,swirl number 0 and 0.6, the flue rate of the recirculated flue gas from 0% to 12%, and jet spray angle 80. The effect of the above various operating conditions on the combustion characteristics and the formation of pollutants are studied in this research. A photographic technology is used to study the combustion behaviors of the flame under various operating condition. Flame structures display that when the flow rate of the recirculated flue gas increase, the flame color in primary combustion zone will change gradually from high temperature white-yellow flame to low temperature orange-red flame. At plate angle 0 and 45, the primary combustion zone with plate angle 45 occurs near burner so that we cannot see too much white-yellow zone from quartz window. The flame outside of the primary combustion region exhibits the red color which is due to the radition of CO2 and water vapor. In addition, when the strength of the swirl increases the contour of the flame will change gradually from smooth shape to strongly distortion.

No description available.

Denna studie har sammanställt kunskap och erfarenhet från drift av SCR-anläggningar påfartyg med syftet att fastställa de huvudsakliga orsakerna bakom problem som uppstår ikatalysatoranläggningar inom Nord- och Östersjöfarten. Undersökningen utfördes meden kvalitativ intervjumetod. För att få en bra täckning riktade sig undersökningen motbåde rederier och fartyg med erfarenhet av SCR, samt tillverkare av systemen.Intervjuerna utfördes per telefon och analyserades sedan mot frågeställningarna. Iresultatet framkom att ett stort antal anläggningar genomgått modifieringar eftersomproblem uppstått. Ett antal vanligt förekommande problem identifierades. Någrakomponenter är särskilt kritiska att designa och dimensionera, såsom utrusning förureainjicering och magnetventiler för sotblåsning. Vidare framkom att avgastemperatursåväl som bränslet och ureans kvalité var viktiga faktorer för att uppnå god prestandaoch livslängd. Studien visar även att ökad kompetens krävs både hos befintlig ochblivande maskinpersonal för att underhållsåtgärder ska ske på rätt sätt och i rätt tid. Föratt möta eventuella framtida behov av SCR kombinerat med scrubberteknik krävs fortsattteknikutveckling. / The objective of the project was to compile knowledge and experience from the operationof SCR-installations on vessels in order to determine the main causes behind theproblems that arise in the catalyst systems within North- and Baltic Sea shipping. Thestudy was performed as a qualitative interview method. In order to get a good coverage,the study was directed against both companies and ships with experience of SCR andmanufacturers of systems. The interviews were conducted by telephone, and thenanalyzed against the objective. The result showed that a large number of plants haveundergone modifications since problems has occurred. A number of common problemswere identified. The study identified some components that are particularly critical todesign and dimension, such as equipment for urea injection and solenoid valves for sootblowing. It was also found that the exhaust temperature as well as fuel and urea qualitywere important factors in achieving good performance and lifetime. Increasedcompetence is required from both existing and future engine personnel so thatmaintenance can be done the right way and at the right time. To meet future demands ofSCR combined with scrubber technique further technical development is required.

Zugl.: Karlsruhe, Univ., Diss., 2008 / Hergestellt on demand