Dusting is one of the major problems in the operation of lime kilns because dust particles interfere with kiln operation and reduce its efficiency. A numerical model is developed to predict the rate of dust formation in rotary lime kilns. The model consists of four major components: 1) a 3D model for the kiln gas, solving fluid flow, heat transfer, and combustion in the gas region; 2) a 1D model for the kiln bed, solving for variation of the solids composition, including moisture content, along the kiln; 3) a 3D model to predict the motion of the solids in the bed, and to estimate the reaction rates; 4) a mathematical model to predict the rate of particle pickup from the bed. Additionally, motion of dust particles was modeled, for the first time, using Stochastic Separated Flow model (a Lagrangian approach). The developed model of particle tracking enables the user to predict distribution of dust particles in the gas section of the kiln. Different components of the model were validated using experimental data published in the literature. The developed model was used to simulate operation of a full-scale lime kiln at typical operating conditions, i.e. at different fuel and air flow-rates. Dusting signatures were also estimated for each setting to determine the effect each operating condition has on dusting. The results presented in this thesis indicate that dust formation is mainly affected by the kiln gas velocity. Effect of other operating conditions was found to be negligible within the ranges studied. The results presented here suggest that dust formation can be controlled by minimizing the input gas flow rate.

Dusting is one of the major problems in the operation of lime kilns because dust particles interfere with kiln operation and reduce its efficiency. A numerical model is developed to predict the rate of dust formation in rotary lime kilns. The model consists of four major components: 1) a 3D model for the kiln gas, solving fluid flow, heat transfer, and combustion in the gas region; 2) a 1D model for the kiln bed, solving for variation of the solids composition, including moisture content, along the kiln; 3) a 3D model to predict the motion of the solids in the bed, and to estimate the reaction rates; 4) a mathematical model to predict the rate of particle pickup from the bed. Additionally, motion of dust particles was modeled, for the first time, using Stochastic Separated Flow model (a Lagrangian approach). The developed model of particle tracking enables the user to predict distribution of dust particles in the gas section of the kiln. Different components of the model were validated using experimental data published in the literature. The developed model was used to simulate operation of a full-scale lime kiln at typical operating conditions, i.e. at different fuel and air flow-rates. Dusting signatures were also estimated for each setting to determine the effect each operating condition has on dusting. The results presented in this thesis indicate that dust formation is mainly affected by the kiln gas velocity. Effect of other operating conditions was found to be negligible within the ranges studied. The results presented here suggest that dust formation can be controlled by minimizing the input gas flow rate.

<p>The subject of this M.Sc. thesis is to find out whether the lime industry is a possible business area for Kanthal AB. The lime industry is one of the biggest chemical industries in the world and it is very energy demanding. In the process of making quicklime, calcium oxide, a lot of energy is needed as the dissociation of limestone, which consists mainly of calcium carbonate, takes place in the temperature span between 900°C and 1300°C. The total production of quicklime was in 2009 about 280 million tonnes, and the selling price was about $100 per ton. Today, all limekilns are driven by fossil fuels, i.e. oil, coal and gas. The increasing demand on lowering the emissions of carbon dioxide strongly affects the industry, as it is responsible for about 2 % of the total emissions of carbon dioxide. The industry itself claims that the emissions may only be reduced about 10 %, although at very high costs. Kanthal AB produces electric heating solutions that may be suitable for lime production. However, the lime industry is conservative and the use of electricity for lime production is not economically feasible today. Most of the electricity comes from coal power plants and therefore the use of electricity would not be more environmentally friendly in most countries. New limekilns, which are more environmentally friendly, are on the way. These kilns do not necessarily have to use fossil fuels, provides a purer end product and the emission of carbon dioxide is minimized. The size of the production is also much lower, but the end products might be used in more demanding areas, e.g. the pharmaceutical industry, and be sold at a higher price. It is this area Kanthal has to focus on if going to enter the lime industry at this point.</p>

The subject of this M.Sc. thesis is to find out whether the lime industry is a possible business area for Kanthal AB. The lime industry is one of the biggest chemical industries in the world and it is very energy demanding. In the process of making quicklime, calcium oxide, a lot of energy is needed as the dissociation of limestone, which consists mainly of calcium carbonate, takes place in the temperature span between 900°C and 1300°C. The total production of quicklime was in 2009 about 280 million tonnes, and the selling price was about $100 per ton. Today, all limekilns are driven by fossil fuels, i.e. oil, coal and gas. The increasing demand on lowering the emissions of carbon dioxide strongly affects the industry, as it is responsible for about 2 % of the total emissions of carbon dioxide. The industry itself claims that the emissions may only be reduced about 10 %, although at very high costs. Kanthal AB produces electric heating solutions that may be suitable for lime production. However, the lime industry is conservative and the use of electricity for lime production is not economically feasible today. Most of the electricity comes from coal power plants and therefore the use of electricity would not be more environmentally friendly in most countries. New limekilns, which are more environmentally friendly, are on the way. These kilns do not necessarily have to use fossil fuels, provides a purer end product and the emission of carbon dioxide is minimized. The size of the production is also much lower, but the end products might be used in more demanding areas, e.g. the pharmaceutical industry, and be sold at a higher price. It is this area Kanthal has to focus on if going to enter the lime industry at this point.

Low cement castable (LCC) refractory linings, over recent years, have superseded refractory bricks in many high temperature applications. There are concerns however, pertaining to their dry-out. In particular the catastrophic destruction of LCC shapes or linings as a result of phenomenate rmede xplosives palling. This thesis describes the study of both the on-site treatments of LCCs and the physicochemical changes that occur during heating. Two types of explosive spalling event are classified,b asedo n on-siteo bservationsa ndp ost-mortems tudy. A model is presented that describes the physicochemical changes in a LCC system as it is heated from ambient to 450°C. From this model a zone of high vulnerability to explosion has been identified between 230-280°C. The dehydration of the hydrated alumina phase gibbsite (AH3), within this zone, is identified as a possible cause of explosive spalling. An investigation of polypropylene fibres, which are added to LCCs as anti-explosion additives, found that the fibres block porosity between1 60-240°CI.t is suggested that this additive system is not optimised and that polymer fibre blends may be more advantageous. The diffusion characteristics of a LCC system cured at 5 and 20°C is presented. It was found that at the lower curing temperature the diffusion rate was lower. This supports the recommendation for the use of high curing temperature to facilitate the drying of LCCs and reduce the risk of explosive spalling. A list of guidelines that could be used to establish benchmark standards for the development of best practice in industry has been compiled from the results of these studies.

The problem with which this investigation is concerned is the discovery of suitable uses for the enameling kiln in the arts and crafts program at the junior college level in the production of kiln-formed glass and the testing of methods and materials that will permit work of aesthetic merit at a nominal cost to the students and the school.

No description available.

El concreto Autocompactante está dirigido principalmente para el empleo del concreto en elementos que poseen difícil acceso, alta congestión de acero o por el proceso necesita ser vertido en el menor tiempo posible. Es posible desarrollar un concreto autocompactante para resistencias convencionales como f´c 210, 245 y 280 kg/cm2 con adiciones de microfiller calizo. El trabajo fue desarrollado considerando como base comparativa los diseños de resistencia a la compresión f´c 210, 245 y 280 kg/cm2 cuyos contenidos referenciales de cemento son equivalentes a 9, 11 y 12 bolsas de cemento, respectivamente. Se estableció un espectro de análisis para la adición del microfiller calizo considerando porcentualmente dosis de 30%, 40%, 50% y 60% de adición respecto al contenido total del cemento más microfiller calizo. Los componentes de las mezclas son de procedencia local como el cemento tipo I de marca Sol, la adición mineral de microfiller calizo, ambos de Cementos Lima, los agregados fino y grueso de huso #89 procedentes de cantera Jicamarca, el agua de la red pública y los aditivos retardante reductor de agua de rango medio y superplastificante de alto rango a base de policarboxilatos de BASF Perú. Se elaboraron mezclas de concreto bajo similares condiciones ambientales y controladas a escala de laboratorio. El estudio ha permitido el uso de los mismos contenidos de cemento empelados en concretos convencionales como base para mezclas autocompactantes y el empleo de un material de reemplazo como el microfiller calizo que es el residuo captado de los filtros en la elaboración del cemento, Los diseños con sólo cemento que logran un mejor comportamiento son aquellos que tienen contenidos de cemento entre 460 y 500 kg/m3, debido a que el empleo de contenidos menores nos obligarían a empelar aditivos modificadores de viscosidad para evitar una posible segregación de la mezcla, en la búsqueda de mayores extensibilidades iniciales y la limitación del contenido de agua y aditivos. A las mezclas que se incluyeron microfiller calizo también se consideraron dosis de reemplazo a su contenido de cemento logrando mezclas de hasta 260 kg/m3 de cemento para adiciones de 30%, 40%, 50% y 60% del cementante total; bajo consideraciones de mezclas autocompactantes mientras se incrementaba el porcentaje de adición las mezclas lograban mejores desempeños en la fluidez de la mezcla. Las mezclas con adición de microfiller calizo tienen un mejor comportamiento en la capacidad de relleno respecto a las mezclas con sólo cemento, debido a que las últimas presentan mayor cohesión en la mezcla. Respecto a la medición de la permeabilidad del concreto, las mezclas convencionales no cumplirían requisitos para ser evaluados debido a que el ensayo está considerado para relaciones a/cm menores a 0.50, las muestras en estudio con sólo cemento y adiciones de microfiller calizo alcanzan una clasificación de permeabilidad alta. La durabilidad del concreto evaluada por el ensayo de abrasión demuestra que los concretos con sólo cemento tienen un mejor comportamiento frente al desgaste superficial y los concretos con adiciones al 30% y 40% de microfiller calizo obtienen pérdidas de material superficial similares, siendo las muestras con adiciones de 50% y 60% las que tienen a incrementar el desgaste superficial. Las resistencias a la compresión en mezclas con adición de microfiller calizo se mantienen en el rango promedio de 360 kg/cm2 con una variación promedio de 60 kg/Cm2 entre las adiciones extremas de microfiller calizo (30% y 60%), esto supera definitivamente el f´c convencional y ofrece un valor agregado respecto las características de una mezcla autocompactante.

Increasing population equals increase in agricultural product consumption for which continuous food production is not a viable option. Solar drying, on the other hand is a promising method to preserve agricultural products for longer durations. This thesis focuses on calculating the predictability of the independent factors and a comprehensive risk assessment to improve the performance of Solar Hybrid Kiln. Biochar samples with different moisture content were selected for 3 tests. Principal component analysis and multiple linear regression analysis were conducted on the gathered data using Minitab 18R platform. Risk response plans associated with the kiln were provided through failure mode effects analysis. Results exhibited 3 significant principal components and reliable prediction model limits were obtained for both training and testing datasets. A total of 41 risks were identified and risk response plans were proposed for them. These results can be further used to increase the efficiency of biochar drying processes.

The objective of the research is to reduce the volatile organic compounds (VOCs) emitted during kiln drying of southern yellow pine (SYP) lumber. Three treatment methods were explored to determine their effect on VOC emissions. The three methods were configured at the air exhaust of a pilot-scale dry kiln. 1) A steel reactor containing copper tubing heated to 100°, 200°, and 240° Celsius was evaluated. Temperature did not statistically affect VOC emissions (p-value = 0.1674). The average reduction of VOCs at 240° C was seven percent. 2) The use of hydrogen peroxide and ultra-violet (UV) light did not reduce VOCs emitted during kiln drying. 3) The use of Fenton?s reagent, with hydrogen peroxide and ferrous sulfate, also did not reduce VOCs emitted during kiln drying. 4) It is recommended that future studies with copper heated to temperatures above 240° C be performed.