生物质与煤混燃灰荷电特性及电场特性研究

发布时间：2018-11-17 13:42

【摘要】：飞灰颗粒荷电是其被电除尘器捕集的前提和基本过程,伏安特性和板电流密度分布特性是衡量电除尘器电场特性及极配型式的关键参数。生物质与煤混燃,由于生物质与煤物化特性以及燃烧特性上的差异,可能会使得混燃灰在电除尘器内部的荷电特性及电场特性发生一定的变化,从而影响电除尘器对其捕集效率。因此对混燃灰荷电特性、伏安特性以及板电流密度分布特性展开研究具有十分重要的意义。本文将常见的生物质燃料玉米秸、花生壳、木头屑按照占总热量0、5%、10%、15%、20%、100%的比例分别与无烟煤和烟煤混燃,制成一系列混燃灰。通过采用自行设计的粉尘总体荷电量测量系统及分级荷质比测量系统,在5kV直流正高压条件下电晕荷电,进行混燃灰总体及分级荷质比测量。实验结果表明:混燃灰荷质比随着生物质混燃比增加出现逐渐增大的趋势,混燃比例越高,混燃灰的荷电特性越强。另外,掺混生物质种类对混燃灰的荷电特性有一定影响,玉米秸、花生壳及木头屑三种生物质来看,玉米秸混燃灰荷电特性最强,花生壳次之,木头屑荷电特性最弱。与此同时,被掺煤种对混燃灰的荷电特性也存在一定的影响。分析认为混燃灰荷电特性规律与其化学成分、微观形貌、比电阻等因素有关。电场特性层面,通过在自行设计的水平电场伏安特性测定装置上模拟电除尘器电晕放电,对混燃灰伏安特性进行测定,结果表明:生物质混燃比例对混燃灰样的伏安特性有着显著影响。随着生物质的混燃比提高,混燃灰的伏安特性更优。玉米秸、花生壳、木头屑三种生物质与煤混燃灰的伏安特性优劣程度:玉米秸花生壳木头屑与煤的混燃灰,而且随着生物质混燃比例的增加,掺混生物质种类差别对混燃灰伏安特性的影响程度愈加凸显。另外结果还发现生物质与无烟煤混燃灰伏安特性明显优于与烟煤混燃灰,但不同品类的无烟煤之间伏安特性虽存在差异,但差异较小。采用网格型微元电流信号法在自行设计的板电流密度分布测定装置上对混燃灰板电流密度分布特性进行研究,结果表明:生物质混燃比以及掺混生物质种类仅对混燃灰电流密度大小产生影响,对其电流密度分布均匀性没有影响。另外电晕线型是影响混燃灰板电流密度分布特性的重要因素。因此对于混燃灰的高效捕集,选择最佳的极配形式也尤为重要。
[Abstract]:Charge of fly ash particles is the premise and basic process of its capture by electrostatic precipitator. The characteristics of volt-ampere and plate current density distribution are the key parameters to measure the electric field characteristics and pole-matching type of electrostatic precipitator. Because of the difference in the physical and chemical characteristics and combustion characteristics of biomass and coal, the charge and electric field characteristics of the mixed combustion ash in the electrostatic precipitator may be changed to a certain extent. Thus, the capture efficiency of the electrostatic precipitator is affected. Therefore, it is of great significance to study the charge-charging characteristics, volt-ampere characteristics and current density distribution characteristics of mixed combustion ash. In this paper, the common biomass fuel corn straw, peanut hulls and wood dandruff were mixed with anthracite and bituminous coal to form a series of combustible ash according to the proportion of 10% of total heat of corn straw, peanut shell and wood dandruff. By using the self-designed system for measuring the total charge of dust and the measuring system of the graded charging mass ratio, the total and graded charge / mass ratio of the mixed combustion ash was measured under the condition of 5kV DC positive high voltage and corona charge. The experimental results show that the charge / mass ratio of mixed combustion ash increases gradually with the increase of biomass blending ratio, and the higher the blending ratio is, the stronger the charge characteristic of the mixed combustion ash is. In addition, the type of mixed biomass has a certain effect on the charge characteristics of mixed burning ash. Among the three kinds of biomass, corn straw, peanut shell and wood dandruff have the strongest charge-charging characteristics, followed by peanut shell and wood dandruff. At the same time, mixed coal has a certain influence on the charge characteristics of mixed combustion ash. It is concluded that the charge-charging characteristics of mixed combustion ash are related to its chemical composition, microscopic morphology, specific resistance and so on. In the electric field characteristic level, by simulating the corona discharge of the electrostatic precipitator on the self-designed measuring device of the horizontal electric field volt-ampere characteristic, the volt-ampere characteristic of the mixed combustion ash is measured. The results show that the ratio of biomass mixture has a significant effect on the voltammetric characteristics of mixed combustion ash samples. With the increase of the ratio of biomass to fuel, the voltammetric characteristics of mixed combustion ash are better. The voltammetric characteristics of corn straw, peanut shell, wood dandruff and coal mixed combustion ash were good and bad: corn straw peanut shell wood dandruff and coal mixed burning ash, and with the increase of biomass mixed combustion ratio, The influence of different kinds of mixed biomass on the voltammetric characteristics of blended ash is becoming more and more prominent. The results also showed that the voltammetric characteristics of biomass and anthracite blended ash were obviously superior to those of bituminous coal, but the voltammetric characteristics of anthracite of different categories were different, but the difference was small. The characteristics of the current density distribution of the mixed ash plate were studied by using the grid microelement current signal method on the plate current density measurement device designed by ourselves. The results showed that the mixed combustion ratio and the type of mixed biomass had only influence on the current density of the ash, but had no effect on the uniformity of the current density distribution. In addition, the corona pattern is an important factor affecting the current density distribution of the ash plate. Therefore, it is very important to select the best matching form for the high efficiency capture of mixed combustion ash.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X701.2

【参考文献】