|关键词||热等离子体 厨余垃圾 气化 化学平衡|
通过自行设计和搭建的1 kW、35 kW热等离子体气化实验系统完成空气、水蒸气气化剂和物料自身属性对热等离子体气化效果影响的实验。在1 kW的实验系统上，研究结果表明，过量空气系数（ER）对于合成气和低位热值的影响有两种效应：当 ER小于0.095时，化学反应热在气化室中占据主导；而当ER大于0.095，合成气由于空气含量的增加而导致其被消耗，一氧化碳和氢气的产量有所下降，二氧化碳含量升高。水蒸汽作为气化剂的气化过程，水煤气反应会增强，进而促进合成气的产量和气化效率提升。整个热等离子体气化实验过程中的热效率和㶲效率最大值均出在水蒸汽物料比（SFR）等于0.084时，分别为28.2%和 23.0%。
With the rapid development of the city's scale and population, the amount of municipal solid waste (MSW) and kitchen waste has also increased gradually. However, the standards for waste disposal and pollution emission are more stricter rather than reduced. Ships also have a large amount of domestic garbage that needs to be disposed of, due to their small space and mobility. Therefore, this study mainly focuses on designing and setting up an experimental system for plasma gasification treatment of ship kitchen waste, according to the small bulk, high efficiency and strong operability of ship equipment. Considering the ship kitchen waste is classified into staple food, celluloses, and oil and fats, this study is carried out by a thermal plasma generator to gasify the staple food wastes, involving a small amount of gasification experiments related to cellulosic biomass.
The gasification experiments of air, water gasification agents and raw materials properties were carried out through the self-designed and constructed 1 kW, 35 kW thermal plasma gasification experimental systems. The results under 1 kW generator indicate that two effects induced by the equivalence ratio (ER) appear on the syngas and low heating value: When the ER is less than 0.095, the chemical reaction heat dominates in the gasification chamber; When the ER is greater than 0.095, the syngas is consumed by the rise of air, resulting in a decrease in the production of carbon monoxide and hydrogen and an increase in the carbon dioxide concentration. As for the process of steam gasification, the water gas reaction enhanced in turn promotes the production and gasification efficiency of syngas. During the entire thermal plasma gasification, the maximum thermal and exergy efficiencies were obtained at the steam-to-material ratio (SFR) of 0.084, corresponding to 28.2% and 23.0%, respectively.
The experimental results under the 35 kW plasma generator demonstrate that the material with different particle sizes plays an important role for the gasification: the materials, 40 and 10 mesh, cause a decline in the yield of carbon monoxide and hydrogen. A plasma energy ratio (PER) less than 0.26 is more favorable for plasma gasification in order to obtain the higher efficiency. Since excessively high plasma energy is likely detrimental to the gasification chamber and actual safe operation of the equipment, which results from the high temperature caused by long time work. As to different materials, the gasification production of flour and rice mainly consist of carbon monoxide and hydrogen. However carbon monoxide concentration in the bagasse gasification products is the lowest among three materials, while the carbon dioxide concentration is the highest, due to the water vapor reaction. The Potash carbonate loading in rice has limited promotion effects on the plasma gasification process and is not as good as the catalytic effect of the traditional gasification process. The residue can reflect the process of gasification in extent. Thus, X-ray diffraction (XRD) and Raman spectroscopy were employed in the residues after plasma gasification, with results demonstrating that the residues have slightly microcrystalline graphite, among which the residue of bagasse has the highest process of graphite, while potassium carbonate can inhibit the process of graphite of material residue.
In addition, through the Gibbs free energy minimum principle, the Aspen Plus software is employed to model and simulate the thermal plasma gasification process. The simulation and energy demand analysis indicate that the moisture content of raw material should be controlled below 36% before the material enter. The classical empirical formula of fluid mechanics is used to analysis the force of particles during the plasma gasification. And the force in the gasification chamber was broke into the hydrodynamic force along the axial direction and the thermophoresis force along the radial direction, which are conducive to realizing the reason that the residue is accumulate in the chamber and the small particle size feed are apt to be blocked in the inlet. From the calculation results, the equivalent model employed in the study is relatively reasonable.
|李慧鑫. 船舶厨余垃圾的热等离子体气化研究[D]. 北京. 中国科学院大学,2015.|