Showing papers on "Carbochemistry published in 2004"

Water in Brown Coal and Its Removal

Abstract: Publisher Summary The brown coals of Victoria represent an important state and national resource. This chapter deals with the physics, chemistry and analytical aspects of water in brown coal. Victorian brown coals show sigmoid isotherms, typical for physical adsorption of condensable vapors on porous substances. The chapter describes drying and dewatering technologies and emphasizes the binderless briquetting technology for brown coal, where water in the coal plays a critical role. In considering the drying requirements of low rank coals, it is informative to express the moisture content on a dry coal basis to indicate the quantity of water to be removed per unit mass of dried coal and hence the energy which has to be provided. The high moisture content of low rank coals has led to the development of a plethora of drying processes, but a major breakthrough on drying cost is still awaited. Water removal processes for low rank coals can generally be divided into evaporative drying or non-evaporative dewatering, where the water is removed from the coal in liquid form.

Coal and coal-related compounds : structures, reactivity and catalytic reactions

Abstract: Methods of Classification and Characterization of Coal. Chemical and Macromolecular Structure of Coal. Pyrolysis. Liquefaction of Coal. Gasification of Coal. Microbial Depolymerization of Coal.

Gasification and Combustion of Brown Coal

Abstract: Publisher Summary This chapter deals with coal gasification, which refers to the reactions of coal with air, oxygen, steam, carbon dioxide, hydrogen or a mixture of these gases to yield a gaseous product These products can be used either as a source of energy or as a raw material for the synthesis of chemicals, liquid fuels or other gaseous fuels The gasification converts solid coal into gaseous products Since coal combustion is defined as the reactions of coal with air or oxygen, it can be regarded as a special case of coal gasification When as-received Victorian brown coal is heated up under gasification conditions, it first undergoes dewatering and pyrolysis Unlike bituminous coals and many other low rank coals, Victorian brown coals have large contents of moisture (60 - 65 %) The dewatering process is therefore particularly important from a practical point of view In the pyrolysis step (sometimes referred to as devolatilisation), inorganic and hydrocarbon gases as well as tarry vapors evolve as volatile matters to leave a solid residue as char Subsequently, a relatively slow reaction of the devolatilised char with a gasifying agent takes place predominantly