A modified furnace, which burns diesel oil is adopted to study the combustion characteristics and the pollution of the exhausting products under certain designing and operating conditions. The different equivalence ratios and swirl numbers can be obtained by adjusting the flow rate of both axial air and tangential air. The controlling ranges of the various experimental parameters include the equivalence ratios from 0.8 to 1.1, the jet oil pressures from 7 kg/cm² to 9 kg/cm², the open angles of the plate 0¢X and 45¢X, the swirl numbers from 0 to 1.0, the flow rates of the recirculated flue gas from 0% to 12%. The effects of the controlling variables on the combustion characteristics and the formations of pollutants within combustion chamber are studied in this reseach. A photographic technology is used to study the flame structures for helping us to understand the behaviors of the flame under various operating conditions. Under the equivalence ratios from 0.8 to1.1, the concentrations of the average NO and CO decrease, at the lower equivalence ratio. However, the concentrations of the average NO and temperature increases monotonously when jet oil pressure increases. The plate open angle 45¢X is useful for the mixing of both fuel and air, so that the open angle of the plate have important effects on both the temperature of combusion gas and the formation of pollutant NO. When the plate open angle 45¢X and the swirl number is 0.6, the flow rate of NO in the exhaust duct is the lowest. At equivalence ratio 0.8, the average NO concentration in exhaust duct decrease, when the flow rate of the recirculated flue gas increase. Our experiments display that the optimized operating condition is at the plate open angle 45¢X, the swirl number 1.0 and the recirculation rate of the flue gas 12%. NO can be reduced to 32% in this condition, and heat efficiency is reduced only about 3.7%, so we can achieve the request of reducing efficiency to much, the formation of pollutant without influencing the combustion. Under the condition of swirl number 0 and the open angle of the plate at 0¢X and 45¢X the color of the flame in the primary combustion region are white-yellow. In the other hand, at the swirl number 1.0, the color of the flame out of the primary combustion region at the swirl number 1.0 exhibits the red color due to the formation of CO2 and water vapor. The red color region at the swirl number 1.0 is much larger than that at the swirl number 0.

Made available in DSpace on 2014-06-11T19:30:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-18Bitstream added on 2014-06-13T19:25:46Z : No. of bitstreams: 1 caputo_pd_me_guara.pdf: 1452016 bytes, checksum: bd796f6ea43f3ec75f5c6bf6d5e2078a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esta dissertação analisa a possibilidade de utilizar combustíveis gasosos alternativos para reduzir o consumo de gás de coqueria em usinas siderúrgicas integradas. Foram consideradas misturas a) de gás de coqueria com gases de gaseificação e b) de gás natural com gases de gaseificação, para substituir o gás de coqueria puro e misturas do gás de coqueria com gás de alto forno. Os dois parâmetros principais que definem a intercambiabilidade entre os gases foram o Índice de Wobbe e o Índice de Weaver relativo a descolamento de chama. O percentual de economia de gás de coqueria foi calculado para as diversas misturas consideradas. / This dissertation analyzes the possibility of using alternate fuel gases to reduce the consumption of coke oven gas in integrated steel making plants. The following gas mixtures were considered: a) coke oven gas with different gasification gases and b) natural gas with different gasification gases to substitute either pure coke oven gas or mixtures of coke oven gas with blast furnace gas. Eight gasification gases from biomass and coal were selected from the literature as prospective substitutes. The two main parameters that defined the interchangeability were the Wobbe Index and the Weaver Index related to flame blow out. The economy of coke oven gas was calculated for all considered alternate gases.

The aluminosilicate materials kaolinite, calcium montmorillonite and emathlite have been tested as solid sorbents for alkali vapour in controlled gaseous environments, in order to study their sorption characteristics. The study used pan pelletised and extruded pellets in single pellet and fixed bed reactor systems under gaseous environmental conditions containing water vapour, hydrogen chloride and nitrogen at a temperature of 850°C. The means of producing the pellets and the composition of the gaseous environment were shown to determine the sorption performance of the sorbent pellets. The physical properties of the pellet (particle size, total pore volume, surface area, crush strength) significantly affect the sorption effectiveness, while the formation of reaction products is dependent upon the sorbents' chemical composition and on the sorption conditions. Reaction products identified under the various sorption conditions indicated possible pathways for alkali capture. Hydrogen chloride mixtures were shown to cause a reverse of the sorption process for some sorbents. A leaching method for extracting sodium from treated pellets enabled the type of bonding to be determined but not necessarily the prime sorption mechanism. With the introduction of water vapour, some evidence was presented that the alkali sorption rate can change significantly. The previously reported effect of hydrogen chloride upon alkali capture by the sorbent material, calcium montmorillonite; shown by McLaughlin (1990) was confirmed and the effect was also investigated for emathlite and kaolinite. Reversibility depended upon the presence or absence of hydrogen chloride. Both water vapour and hydrogen chloride determine sorption activity and capacity. Likewise the structural characteristics of the pellet influences the sorption activity and capacity. The sorption process is not due to aluminosilicate reaction alone but also due to replacement mechanisms. Conclusions are drawn regarding mechanism and theoretical model proposed.

Resumo: Esta dissertação analisa a possibilidade de utilizar combustíveis gasosos alternativos para reduzir o consumo de gás de coqueria em usinas siderúrgicas integradas. Foram consideradas misturas a) de gás de coqueria com gases de gaseificação e b) de gás natural com gases de gaseificação, para substituir o gás de coqueria puro e misturas do gás de coqueria com gás de alto forno. Os dois parâmetros principais que definem a intercambiabilidade entre os gases foram o Índice de Wobbe e o Índice de Weaver relativo a descolamento de chama. O percentual de economia de gás de coqueria foi calculado para as diversas misturas consideradas. / Abstract: This dissertation analyzes the possibility of using alternate fuel gases to reduce the consumption of coke oven gas in integrated steel making plants. The following gas mixtures were considered: a) coke oven gas with different gasification gases and b) natural gas with different gasification gases to substitute either pure coke oven gas or mixtures of coke oven gas with blast furnace gas. Eight gasification gases from biomass and coal were selected from the literature as prospective substitutes. The two main parameters that defined the interchangeability were the Wobbe Index and the Weaver Index related to flame blow out. The economy of coke oven gas was calculated for all considered alternate gases. / Orientador: João Andrade de Carvalho Junior / Coorientador: Sergio Leite Lopes / Banca: Mauricio Araujo Zanardi / Banca: Marco Aurelio Ferreira / Mestre

[pt] No presente trabalho calcula-se a eficiência de um aquecedor de água, sem evaporação, queimando gás combustível com composição química desconhecida. Faz-se a comparação dos resultados obtidos com duas normas que apresentam formas diferentes de cálculo, ASME (1) e NBS (2). Com os resultados finais, sugere-se um procedimento a ser seguido no cálculo de eficiência de aquecedores. / [en] In this research, the thermal efficiency of a sensible water heater is measured and calculated, burning fuel gas with unknown chemical composition. The experimental results are then compared with the calculated values, when using ASME(1) and NBS(2) standard procedures. Finally and procedure is suggested to calculate the thermal efficiency of such heaters.

Atomization of fuel is an important pre-requisite for efficient combustion in devices such as gas turbines, liquid propellant rocket engines, internal combustion engines and incinerators. The overall objective of the present work is to explore air-assisted atomization strategies for high viscosity fuels and liquids. Air-assisted atomization is a twin-fluid atomization method in which energy of the gas is used to assist the atomization of liquids. Broadly, three categories of air-assisted injection, i.e., effervescent, impinging jet and pre-filming air-blast are studied. Laser-based diagnostics are used to characterize the spray structure in terms of cone angle, penetration and drop size distribution. A backlit direct imaging method is used to study the macroscopic spray characteristics such as spray structure and spray cone angle while the microscopic characteristics are measured using the Particle/droplet imaging analysis (PDIA) technique. Effervescent atomization is a technique in which a small amount of gas is injected into the liquid at high pressure in the form of bubbles. Upon injection, the two-phase mixture expands rapidly and shatters the liquid into droplets and ligaments. Effervescent spray characteristics of viscous fuels such as Jatropha and Pongamia pure plant oils and diesel are studied. Measurements are made at various gas-to-liquid ratios (GLRs) and injection pressures. A Sauter Mean Diameter (SMD) of the order of 20 µm is achieved at an injection pressure of 10 bar and GLR of 0.2 with viscous fuels. An image-based method is proposed and applied to evaluate the unsteadiness in the spray. A map indicating steady/unsteady regime of operation has been generated. An optically accessible injector tip is developed which has enabled visualization of the two-phase flow structure inside the exit orifice of the atomizer. An important contribution of the present work is the correlation of the two-phase flow regime in the orifice with the external spray structure. For viscous fuels, the spray is observed to be steady only in the annular two-phase flow regime. Unexpanded gas bubbles observed in the liquid core even at an injection pressure of 10 bar indicate that the bubbly flow regime may not be beneficial for high viscosity oils. A novel method of external mixing twin-fluid atomization is developed. In this method, two identical liquid jets impinging at an angle are atomized using a gas jet. The effect of liquid viscosity (1 cP to 39 cP) and surface tension (22 mN/m to 72 mN/m) on this mode of atomization is studied by using water-glycerol and water-ethanol mixtures, respectively. An SMD of the order of 40 µm is achieved for a viscosity of 39 cP at a GLR of 0.13 at a liquid pressure of 8 bar and gas pressure of 5 bar. It is observed that the effect of liquid properties is minimal at high GLRs where the liquid jets are broken before the impingement as in the prompt atomization mode. Finally, a pre-filming air-blast technique is explored for transient spray applications. An SMD of 22 µm is obtained with diesel at liquid and gas pressures as low as 10 bar and 8.5 bar, respectively. With this technique, an SMD of 44 µm is achieved for Jatropha oil having a viscosity 10 times higher than that of diesel.