液态锑阳极直接碳燃料电池阳极机理与反应特性研究

发布时间：2018-02-23 02:40

本文关键词： 直接碳燃料电池液态锑阳极反应机理性能特性流化床电极　出处：《清华大学》2014年博士论文　论文类型：学位论文

【摘要】：液态锑(Sb)阳极直接碳燃料电池(DCFC)是一种新型发电技术，开展相关机理与反应特性研究对该技术发展具有重要意义。本文系统地研究了液态Sb阳极反应特性，Sb阳极浸润性和电解质表面形貌对电池性能的影响机制，碳燃料在Sb阳极中的反应机理，脱灰煤在Sb阳极中的反应和输运特性，在此基础之上构建了流化床管式液态Sb阳极DCFC原型样机。采用表面粗糙度为纳米级的光滑YSZ单晶电解质(Ra=0.69nm)，能够剥离电解质表面形貌的影响，获得液态Sb阳极的本征反应特性。在800oC下，Sb阳极的本征阳极阻抗为0.143cm2，本征交换电流密度为141.4mA/cm2。800oC下液态Sb和Sb2O3与YSZ单晶表面的接触角分别为45o、0o，Sb2O3的生成有利于提高液态Sb阳极与电解质表面的接触面积。采用Ra=540nm的粗糙电解质表面时，液态Sb阳极与YSZ单晶电解质的有效接触面积提高了38%，表面粗糙度的适度增大有利于提高液态Sb阳极的交换电流密度。在液态Sb阳极中碳还原Sb2O3反应的主要路径是3C+2Sb2O3=4Sb+3CO2，尾气中CO2的比例可达90%。由于CO在液态Sb中的输运速率慢，使得中间产物CO难以还原液态Sb阳极中的Sb2O3。在阳极-电解质界面处的碳燃料能够发生电化学反应，但是由于缺少良好的催化剂，使得碳燃料的电化学反应对电池性能的影响甚微。太西脱灰煤能使液态Sb阳极性能恢复至电池模式初始性能，脱灰煤中的杂质能够被液态Sb层隔离，避免在阳极-电解质界面积累。脱灰煤在液态Sb中的输运方式有扩散和自然对流两种，但是由于粘性力的影响，，使得自然对流对脱灰煤在液态Sb中的输运作用并不显著。采用管式固体氧化物燃料电池，构建了流化床管式液态Sb阳极DCFC原型样机，实现了液态Sb阳极DCFC的连续给料和稳定运行，验证了流化床电极应用于液态Sb阳极DCFC中的可行性。流化床管式液态Sb阳极DCFC中碳燃料转化率可达90%，电池的实际效率可达41%。
[Abstract]:Liquid antimony (SB) anode direct carbon fuel cell (DCFC) is a new generation technology. It is of great significance to study the mechanism and reaction characteristics for the development of this technology. In this paper, the effects of liquid SB anodic reaction characteristics and electrolyte surface morphology on the performance of the battery are systematically studied. On the basis of the reaction mechanism of carbon fuel in SB anode and the reaction and transport characteristics of demineralized coal in SB anode, a prototype of fluidized bed tubular SB anode DCFC was constructed. A smooth YSZ single crystal electrolyte with surface roughness of nanometer size of 0.69 nm can be used to peel off the influence of the surface morphology of the electrolyte. The intrinsic reaction characteristics of liquid SB anode were obtained. At 800oC, the intrinsic anode impedance of Sb anode was 0.143 cm 2, and the exchange current density was 141.4 Ma / cm 2.800oC. the contact angle between liquid SB and Sb2O3 on the surface of YSZ single crystal was 45oTO 0oSb 2O 3 at 800oC. Contact area between SB anode and electrolyte surface. When using Ra=540nm rough electrolyte surface, The effective contact area between liquid SB anode and YSZ single crystal electrolyte is increased by 38%, and the exchange current density of liquid SB anode is increased with the increase of surface roughness. The main route of carbon reduction Sb2O3 reaction in liquid SB anode is 3C _ 2SB _ 2O _ 3N _ 4SB _ 3CO _ 2, and the proportion of CO2 in tail gas can reach 90%. Due to the slow CO transport rate in liquid SB, It is difficult for the intermediate product CO to reduce SB _ 2O _ 3 in liquid SB anode. The carbon fuel at the anodic electrolyte interface can react electrochemical, but due to the lack of good catalyst, The electrochemical reaction of carbon fuel has little effect on the performance of the battery. Tacey deashing coal can restore the performance of liquid SB anode to the initial performance of battery mode, and the impurities in the ash removal coal can be isolated by liquid SB layer. The transport modes of deashing coal in liquid SB are diffusion and natural convection, but due to the influence of viscosity, natural convection has little effect on the transport of deashing coal in liquid SB. The prototype of fluidized bed tubular SB anode DCFC was constructed by using tubular solid oxide fuel cell. The continuous feeding and stable operation of liquid SB anode DCFC were realized. The feasibility of using fluidized bed electrode in liquid SB anode DCFC is verified. The conversion rate of carbon fuel in liquid SB anode DCFC of fluidized bed tube can reach 90% and the actual efficiency of battery can reach 41%.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM911.4

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