Current Air Quality Issues

Air pollution is thus far one of the key environmental issues in urban areas. Comprehensive air quality plans are required to manage air pollution for a particular area. Consequently, air should be continuously sampled, monitored, and modeled to examine different action plans. Reviews and research papers describe air pollution in five main contexts: Monitoring, Modeling, Risk Assessment, Health, and Indoor Air Pollution. The book is recommended to experts interested in health and air pollution issues

Laser-based diagnostics for investigating soot formation in combustion processes

In this work, laser-based diagnostic techniques were developed and applied to investigate soot formation in small-scale laboratory burners as well as in practical combustion devices. Quantitative 2D laser-induced incandescence (LII) measurements often use a cylindrical lens to shape the beam and illuminate the planar region of interest. The varying laser fluence and sheet width in the imaged flame region created due to this focusing was found to introduce significant bias in the 2D LII signal distributions, especially for short focal length lenses combined with long imaged regions. Experimental data were recorded with variations in laser fluence and detector gate, which were reproduced through numerical simulations using a heat-and-mass-transfer-based LII model. It was shown that adequate choices of experimental parameters could minimize bias in the 2D LII signal distribution. Combined measurements using LII and extinction as well as laser-induced fluorescence of polycylic aromatic hydrocarbons (PAH-LIF) were applied to characterize soot formation in methane-air diffusion flames at elevated pressures. A special focus was on the evaluation of optical properties of soot at various spatial locations in the flames through the analysis of LII fluence curves. The absorption function E(m) was found to increase strongly with increase in pressure at the position of maximum soot volume fraction (fv), and also along the centreline of the flame until the position of maximum fv. It was demonstrated that an assumption of constant E(m) in 2D LII measurements in sooting diffusion flames leads to large uncertainties in evaluated soot volume fractions.Previous studies have shown that addition of potassium chloride (KCl) reduces soot concentration and primary particle size. As PAHs are precursors of soot, this work focused on the influence of potassium and sodium salt additives on PAH formation, and measurements were primarily made using PAH-LIF and elastic light scattering (ELS). Using different combinations of excitation and fluorescence wavelengths, the detected fluorescence could be classified to originate from two groups: small PAHs (~ 2-3 rings) and large PAHs (≳ 4 rings). Addition of potassium and sodium salts were found to have no observable influence on the formation of smaller PAHs. However, the concentration of larger PAHs decreased in the sooting flame region with the addition of these salts, where the largest effect was seen for potassium salts. Additionally, different salts of potassium (or sodium) showed similar fluorescence and scattering response, thus showing that it is the metal ion which is primarily responsible for the influence on PAH concentrations observed in this study. Laser diagnostic techniques have also been applied in an optical diesel engine to study the effects of injector aging and oxygenated fuel additive tripropylene glycol monomethyl ether (TPGME) on spray and soot formation as well as soot oxidation. Studies in the literature have shown that aging of injectors adversely affects diesel engine combustion. TPGME has also been found to lower soot emissions. The spray and soot formation were investigated using high-speed imaging measurements of Mie scattering and natural luminosity, whereas late cycle soot oxidation was studied using semi-quantitative 2D LII and extinction measurements. Aged injector showed higher fuel injection rates resulting in higher soot formation and faster soot oxidation, predominantly at low load conditions. The fuel with added TPGME produced lesser soot in the cycle and showed faster soot oxidation rates

Development and application of a comprehensive methodology for the analysis of global and local emissions of energy systems

The energy sector is a source of economic and social progress, but it is also the main responsible of air pollution resulting from human activity, mainly from the combustion of fossil fuels and bioenergy. The impacts on atmosphere may be divided into global effects, due to change in concentration of greenhouse gases, and regional/local effects, due to the dispersion of SO2, NOx, particulates and other gases. The aim of this thesis is the development and application of a methodology for calculating the emissions in atmosphere associated with energy management interventions. The methodology aims to characterize and quantify the environmental impacts affecting both the local and global scale. The pollutants involving local effects considered in this study are nitrogen oxides and particulate matter. Globally, the emission of greenhouse gases is considered, by quantifying the equivalent CO2 (CO2eq) emitted. The environmental impact of an energy option is quantified in terms of its emission balance, i.e. by comparing the present situation with one (or more) future scenarios. The study at the local scale also considers the dispersion of pollutants using modelling tools. The methodology is applied to two case studies located in the Italian Metropolitan City of Turin, characterized by different application contexts and different scales of operation. The first case study is represented by a system for the production and conversion of biogas and biomethane. The analysis of global emissions considers four different operating scenarios. The results show a CO2 reduction of 1426 t/y for biogas combustion in full cogeneration mode (generation of both heat and electricity). Biomethane for transports scenario provides a similar result (1379 t/y). If biogas combustion with partial cogeneration is considered (generation of electricity only), the CO2 balance approaches to zero. The evaluation of local impacts is made with two different dispersion models. The application of an Octave-based Gaussian model provides an average increase of concentration both for NOx and TSP, in the order of units of g/m3. The results of CALPUFF model simulations show a slight decrease of concentration in the order of 10-2 g/m3. The second case study consists of a potential extension of the district heating network in the urban area of Turin. The production of local emissions is calculated considering the operation of the main power plants in response to the estimated heat demand. Avoided emissions are calculated simulating the heat production of centralized residential heaters. The results of CALPUFF model simulations show a potential reduction of NOx average concentration between 1 and 6 g/m3. The results of global emissions show an unfavorable balance in the order of 104 t/y of CO2, that varies depending on the assumptions on the emission factors of the power units. A comprehensive final discussion is reported after the analysis of the two case studies. The calculation of two indicators (the “thermal benefit vs. local emission indicator” and the “local to global emission ratio”) is also included to discuss a possible standardization of the proposed methodology. This study provides important information on the effects on air quality resulting from the modification of the energetic management of an area or settlement. The employed methodology is consistent and comprehensive in identifying the potential optimal solutions for energy production and management, as well as identifying the consequences to a given scenario under an environmental point of view

Emission inventories from Kuwait petroleum refineries and respective ground level concentration of pollutants in the neighboring residential area

The State of Kuwait has three large refineries, namely, Mina Al Ahmadi Refinery, Mina Abdullah Refinery and Shuaiba Refinery. These refineries process and refine Kuwait Crude Oil through different process units. There are many heaters, boilers and flares that form a part of the complicated equipment which enhance the different petroleum processes. Fuel gas is used as a firing fuel for those heaters and boilers. As a result, stack emissions like SO2, NOx, CO are predominantly present in the flue gases and this study focuses on those emissions and their impact on the surrounding residential area. The area of interest will be Umm Al-Hyman residential area. This study accumulates emission inventories from the three refineries and the respective ground level concentration of the pollutants in the neighboring residential area. It also focuses on the impact of emissions from the refinery operations on the ground level concentrations in the surrounding areas by using the inventory model and latest emission factors to provide accurate emission estimates. The models were developed and the results were verified with the actual data from the area of impact. As a result of the findings of the major pollutants, namely SO2, NOx & CO, it is found that SO2 and CO are not exceeding Kuwait EPA Ambient Air Quality Standards for Residential Areas normally. However, NOx is observed to exceed occasionally. Even though, NOx emissions from refineries sources represented by plume models were much less, there is a consistent increase in the measured NOx. Furthermore, in 2007, the measured hourly, daily and annual NOx concentration exceeded the international standard many times. The increasing trend in NOx is attributed to continuous increase in population and the number of motor vehicles. The study will go further step in recommending engineering solutions and best practices to reduce the pollutants concentrations which will help in the reduction of human health risks and protect the environment

Integrated Waste Management

This book reports research on policy and legal issues, anaerobic digestion of solid waste under processing aspects, industrial waste, application of GIS and LCA in waste management, and a couple of research papers relating to leachate and odour management

Modelling and Simulation ofCO emission using Point Source Model

The framework for developing computerized software for air dispersion is presented in this project. The software is called Plume Dispersion Modelling Software (PluDMS) which focuses on carbon monoxide dispersion from a point source. PluDMS is developed using Visual Basic (VB) programming language to specifically predict carbon monoxide coiicentrations over distance. Atmospheric conditions and emission parameters are the required inputs for the software. The output is the concentration of gas over the distance and die fatahty predicted for that concentration dispersed. The software is vahdated using other established air dispersion software; SCREEN3. Existing models are utilized to predict the dispersion scenarios and their impact to the environment and humans. The model used in the softwareis a Pasquill-GiffordGaussian point source model

NOx ADSORPTION AND NTP DESORPTION-REDUCTION

NOx emissions have multi-fold hazards for both environment and human health, due to their role in the formation of fine particles, ozone smog, acid rain and eutrophication. The increasing level of emissions and the improved comprehension of NOx toxicity have led to a progressive reduction of allowed emissions from stationary and mobile anthropic sources. NOx emissions can be controlled by altering the combustion process (e.g. Selective Non-Catalytic Reduction) or by post-combustion treatment of the flue gases (e.g. Selective Catalytic Reduction). These two technologies are the most commonly used for industrial processes in a wide range of applications. SCR has a higher capital cost than SNCR but allows a superior reduction of NOx concentration and it is the preferred technique in many industrial applications when high-quality standards are required. Due to the recent stricter European regulations for NOx emissions, SNCR is almost inadequate for the new standards, and cost-effective and alternative methods to SCR are under investigation. The NOx adsorption and non-thermal plasma desorption/reduction strategy was proposed and it is investigated in this thesis. The process consists of the adsorption of NOx on a sorbent material followed by the sorbent regeneration using non-thermal plasma in N2 flushing. The presence of the plasma has the double effect of promoting the NOx desorption from the sorbent surface and reducing the NOx desorbed to N2 and O2. A further reduction of NOx can be performed in a DBD plasma reactor. The desorption and reduction are promoted by the high reactive nitrogen gas discharge particles that react with NOx. A granular activated carbon (GAC) was investigated for NOx adsorption from simulated flue gases. The adsorption capacity for NOx was negligible (less than 4mg/g) if a mixture of NO diluted in N2 was considered; however, it was possible to calculate the adsorption isotherms at 30 and 120°C. A great improvement in the adsorption capacity was calculated as oxygen was fed (up to 66mg/g). The tests demonstrated that part of the NO was catalytically oxidized to NO2 in the presence of oxygen, with a consequent improvement in NOx adsorption. Even the adsorbent impregnation with copper (GAC-Cu) played a positive role in the NO oxidation, hence improving the capacity to remove NOx from the gas stream. Dielectric Barrier Discharge reactors demonstrated a high efficiency (up to 100%) in NOx reduction. The configurations with one and two dielectrics were investigated, highlighting the high performance of the one dielectric barrier discharge reactor and the high flexibility of the two dielectric barriers discharge. A numerical analysis was performed to model the plasma condition promoted in the realistic reactors. The results in terms of electric parameters were consistent with those estimated in the gas discharge, e.g. electric field, electron density and electron temperature. Cyclic tests of adsorption and sorbent regeneration plasma-assisted demonstrated the effectiveness of the process by using GAC-Cu for NOx removal. The amount of NOx adsorbed during the adsorption stage was desorbed and converted during the desorption plasma-assisted process. Higher effectiveness (≈100%) was estimated in the case of GAC-Cu of commercial size (1.5-3mm), while the effectiveness decreased in the case of lower granular size (0.3-0.6mm). The possibility to perform the process at low temperature makes this technology suitable for those gas treatment plants that require a retrofit to accomplish the new regulations. The gas would be treated with the designed reactor to obtain further NOx reduction, without risks of ammonia slip that represents the main problem of high-efficiency conventional technologies

Energy: A continuing bibliography with indexes, issue 17

This bibliography lists 1292 reports, articles, and other documents introduced into the NASA scientific and technical information system from January 1, 1978 through March 31, 1978