Le précalcinateur de cimenterie est un réacteur dans lequel une grande quantité d'énergie thermique est produite par la combustion de solides pulvérisés à des températures modérées : 800 à 1100°C. Les cokes de pétrole sont la principale source d'énergie. Nous nous intéressons dans ce travail aux mécanismes thermochimiques qui sont à l'origine de la formation de polluants de type NO et SO2 lors de leur combustion dans ce réacteur. La première approche est expérimentale : la combustion de 22 cokes a été réalisée en laboratoire au moyen d'un Réacteur à Flux Entraîné à 900°C, dans des conditions thermochimiques proches de celles d'un précalcinateur. Une recherche de corrélations entre les caractéristiques des cokes et les quantités de polluants formées lors de leur combustion a montré qu'aucune relation simple ne prédit les quantités de NO formées. Nous avons donc, dans une deuxième approche, décrit au moyen d'un modèle numérique l'ensemble des phénomènes thermiques et chimiques mis en jeu dans la combustion et la formation des NOX. Des expériences spécifiques ont permis de caractériser les espèce produites par chacune des réactions principales, et de déterminer leurs paramètres cinétiques. Le modèle permet de dégager les mécanismes prépondérants, et de hiérarchiser leur participation à la formation de polluants. Les quantités de NO thermique formées sont négligeables. Le NO du combustible se forme majoritairement au cours de l'oxydation du résidu carboné. Les réactions chimiques en phase gaz contribuent largement à la formation du NO dans la zone de flamme, mais n'ont au final qu'un faible impact sur les quantités de NO présentes. En revanche, une quantité significative de NO est réduite par réaction hétérogène avec le résidu carboné. L'espèce SO2 est formée au prorata de la perte de masse du combustible, au cours de la dévolatilisation et au cours de l'oxydation du résidu carboné. Son interaction avec la chimie des oxydes d'azote a un impact peu significatif.

Agglomerate formation is a common phenomenon that can cause operating problems in the fluid coking reactor. When agglomerates form they provide longer diffusion paths of the reaction products through the liquid layers and liquid bridges within the agglomerate, which leads to higher mass transfer resistance, trapping of the reaction products and increasing the undesired coke formation reactions. Surviving agglomerates in the reactor can also cause fouling of the reactor interior and defluidization of the bed. The ultimate coke yield was determined for agglomerates of Athabasca vacuum residue and solid particles by heating on Curie-point alloy strips in an induction furnace at 503 oC and 530 oC and in a fluidized bed reactor at 500 oC until all toluene-soluble material was converted. Coke yields from agglomerates were compared to the results from reacting thin films of vacuum residue. The average coke yield from the agglomerates was 23%, while the coke yield from thin films of 20 m thickness was 11%, which supports the role of mass transfer in coke formation reactions. The ultimate coke yield was insensitive to vacuum residue concentration, agglomerate size, reaction temperature and agglomerate disintegration. The temperature profile within agglomerates was measured by implanting a thermocouple at the agglomerate center, and a heat transfer model was used to describe the temperature variation with time. The effective thermal diffusivity of the agglomerates was 0.20 x 10-6 m2/s. Control experiments on reactions in thin liquid films confirmed that heating rates in the range of 14.8 to 148 K/s had no effect on the ultimate yield of coke

An electrochemical double-layer capacitor (EDLC) is a potential buffer for current power and energy supply. In this work, activated carbon derived from fluid coke as a brand new electrode material was studied due to its high specific surface area (SSA) and large portion of mesopores. A suitable electrode material formula, current collector, and cell configuration were investigated to fabricate a testable system and ensure the reproducibility of measurements. Cyclic voltammetry (CV) and constant current charge/discharge (CD) techniques were used to characterize the performance of the electrode material, as well as to study its fundamental behaviour. A new procedure was established for quantifying the capacitance (Cc) of EDLC from CV which isolates the effect of internal resistance on the measured capacitance (CM). The specific capacitance of single electrode made of activated carbon (~1900 m2/g) with approximately 80% mesopores and macropores was able to reach 180 F/g at scan rate of 0.5mV/s.

An electrochemical double-layer capacitor (EDLC) is a potential buffer for current power and energy supply. In this work, activated carbon derived from fluid coke as a brand new electrode material was studied due to its high specific surface area (SSA) and large portion of mesopores. A suitable electrode material formula, current collector, and cell configuration were investigated to fabricate a testable system and ensure the reproducibility of measurements. Cyclic voltammetry (CV) and constant current charge/discharge (CD) techniques were used to characterize the performance of the electrode material, as well as to study its fundamental behaviour. A new procedure was established for quantifying the capacitance (Cc) of EDLC from CV which isolates the effect of internal resistance on the measured capacitance (CM). The specific capacitance of single electrode made of activated carbon (~1900 m2/g) with approximately 80% mesopores and macropores was able to reach 180 F/g at scan rate of 0.5mV/s.

none

Coke is an indispensable material in Ironmaking process by blast furnace. To provide good and constant quality coke for stable and efficient blast furance operation is very important. Furthermore, a challenging issue in the cokemaking process is the prediction of coke quality. An accurate prediction can support production planning decision and reduce business operation costs. The objective of this thesis is to apply the backpropagation neural network and the model tree techniques for predicting the strength and meansize of coke. Specifically, we developed the coke- physical&chemical-property model, coal-usage model, coal-group-usage model, and extended model for the target prediction task. Experimentally, we found that the coal-usage model achieves the highest Correlation Coefficient and the lowest Mean Absolute Error. Moreover, the model trees technique reaches higher accuracy and better efficiency than does the backpropagation neural network technique.

No description available.

No description available.

No description available.

ABSTRACT MOTIVATION FOR COSTLY MISSIONS: A COMPARISON OF THE JOURNALS OF THOMAS COKE AND WILLIAM CAREY Barry Mark Morris, Ph.D. The Southern Baptist Theological Seminary, 2014 Chairperson: Dr. George Martin Contemporary missions senders can employ expediently lessons regarding risk and self-sacrifice learned through the journals of Thomas Coke and William Carey. This dissertation explores these lessons, applies them to the contemporary context, and considers the consequences of applying said lessons. Fundamental to this discussion is the question - Are the motivations, attitudes and practices of Carey and Coke representative of historical and contemporary pioneer missions? Chapter 2 builds the case by turning to the biblical precedent of men and women who sacrifice much on God's mission. Old and New Testament and historical examples are tendered, demonstrating risky obedience in fulfillment of God's mission. Chapters 3 and 4 form the heart of the dissertation, contributing journal entries from Thomas Coke and William Carey. Chapter 3 highlights and describes Thomas Coke's journal, while Chapter 4 addresses William Carey and his journal. Journal entries are gathered and analyzed according to three themes: risk and sacrifice, evangelism and the gospel, and resolute motivation for risky missions. Chapter 5 compares and contrasts observations from the two journals. Coke's and Carey's motivation for missions is examined in light of the resultant risks and sacrifices experienced in the advance of Christ's kingdom. In this chapter the author highlights recent examples of risky missions found in the correspondence and journals of contemporary missionaries and indigenous workers. The final chapter presents lessons learned from the journals as relates to contemporary missionaries and senders. Specific proposals are proffered to strengthen the decision-making processes for risk-management in mission settings. The investigation calls for the examination of other missionary journals and correspondence from various traditions and regions.