| The clean utility of coal for electricity generation has gradually become a research hotspot in energy industry.Seeking an efficient and environmentally friendly coal-fired power generation technology has become a primary task of energy industry.Supercritical water has strong oxidizing property and special solubility,and is an ideal reaction solvent for the oxidation of organics.Supercritical water oxidation technology is gradually applied in energy field.According to the application and development of the current supercritical water oxidation technology,a new type of power generation system using composite working produce by supercritical water coal direct oxidation was proposed in this paper,which is a promising clean and efficient coal-fired power generation method.The calculation results show that the new power generation system of supercritical water oxidation has a power generation efficiency of 39.5%after carbon collection,and the product is very clean and can achieve near zero emissions.The key problem in this new power generation system is the supercritical water coal oxidation reaction.Therefore,it is of great significance to study the mechanism of water coal oxidation reaction.In this paper,the simulation and experimental study on the oxidation reaction of coal powder were carried out,and the influence of environmental factors such as temperature,reaction time,oxygen ratio and particle size on the oxidation process of water coal was discussed in detail.Firstly,combined with elemental analysis and infrared spectroscopy,the selected coal samples were used as simulation objects to construct the basic model of coal molecules.Then,using the constructed coal molecules as the research object,the simulation calculation of water-oil oxidation reaction under different phase compositions and different temperature conditions was carried out.At the same time,a set of visualized supercritical water-coal oxidation experiment platform was designed and built independently.The high-temperature steam oxidation test at 500?,800? and 1100? and the supercritical water-coal oxidation test at 23MPa and 500? were carried out.After data collation and analysis,the oxidation reaction rate and degree of decomposition of water coal are affected by the content of H2O and O2 in the reaction system.Lowering the water vapor content or oxygen content will result in a decrease in the oxidative decomposition rate of coal powder,and the oxygen content has a greater influence on the oxidation process of water coal.The oxidation reaction rate of water coal increases with the increase of temperature,and decreases with the increase of particle size of coal powder.The oxidative decomposition rate of coal powder in supercritical water environment is higher than that in high temperature water vapor environment.The microscopic morphology analysis of solid residue after oxidation of coal powder found that the higher the oxidative decomposition rate of coal powder,the higher the surface floc fine wrinkles.The grain structure of the solid residue is oxide of elements such as silicon,aluminum and iron. |
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