| During coal combustion at high temperature in furnaces, the desulfurization rate is difficult to promote, which is well-known. In allusion to this problem, the reaction mechanisms of desulfurization was analyzed and studied thoroughly and systematically. In this paper, analyses of theories, mechanism research and industrial tests were reported.Firstly, the emission law of sulfur contamination of the combustion of coal powder, mixed coal and coal water slurry was analyzed. And the microcosmic reaction mechanism of self sulfur-fixation characteristic of coal-fired boilers(1000t/h) in power plants was studied by the X-ray diffraction for dolycrystalline Rietveld Quantitative Analysis, N2 automatic adsorption instrument and SEM visualization. The composition of crystal and non-crystal phases of CaCO3, CaO, Ca(OH)2, and CaS04 in coal ash and dregs was measured quantificationally for the first time. As a result, the distribution characteristic of different phases hi the coal ash and dregs was found, and the variation law with the change of the boiler load was summarized.Secondly, based on the analysis of weight loss, the characteristic of calcinations and sintering of sulfur-retention additive and sorts of coals was studied hi the view of analytical chemistry. That includes the analysis of crystal contents by XRD, pore structure by mercury porosimetry and surface forms by SEM. The influence of the change of the temperature, time and atmosphere on the characteristic of calcinations and sintering was discussed thoroughly.Afterwards, the characteristic of high temperature desulfurizing reaction and catalyst combustion of lots of minerals and industrial wastes was studied thoroughly for the first time, in the view of chemical kinetics and thermodynamics and catalyst chemistry. Especially, SrSO4, BaSO4, silicon aluminate and sulfur aluminate was researched as stable sulfur-fixation products at high temperature. The catalyst calcium-based desulfurizing characteristic of minerals and waste residues, which are rich of alkali metals and transition metals, was studied systematically. The new additives were developed and the sulfur-fixation reaction mechanism of them was illuminated by XRD and SEM visualization. The kinetic characteristic of coal combustion catalyzed by sorts of minerals and waste residues was studied in the condition of constant temperature and gradually rising temperature by a single particle furnace and thermogravimetric method. Furthermore, the catalyst combustion efficiency of minerals and waste residues, which is rich hi different metal oxides, was studied by the perpendicular experiments. As a result, a new combution-supporting agent was developed and the reaction mechanism of it was demonstrated by SEM visualization.Through lots of industrial tests and applications of demonstration projects, the tw o-stage desulfurization technology was put forward originally. The first step of it is blending in coal bed, and the second step is injection in furnace space. This new technology greatly prompted the sulfur removal efficiency of calcium-based sorbents during coal combustion hi furnaces, from 40% to 75%. In addition, the whole desulfurization rate can reach about 85% through flue gas humidification in the water-fiim separator. This technology was considered as an international advanced one by national appraisal. Because of its high efficiency, low cost, environment-protecting and energy-saving, the technology has obvious benefits in economy and society and has wide foreground for application and extension. In the field of numerical simulation, a two-stage particle-expansion model was put forward. It has been used in the study of the influence of S0: initial concentration, ratio of calcium to sulfur, particle diameter of limestone and other parameters on the desulfurization efficiency in limestone injection process.At last, considering the characteristic oxidizing and reducing conditions in pulverized coal fired boilers, a so called air and calcium staged technology was put forward to achieve...
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