烟气深度冷凝余热利用协同污染物脱除技术研究

发布时间：2018-04-09 16:00

  本文选题：饱和湿烟气　切入点：冷凝换热　出处：《山东大学》2017年硕士论文

【摘要】：燃煤锅炉尾部烟气中含有大量余热及SO_2、SO_3、微细颗粒等污染物,湿法烟气脱硫的大规模应用,虽然有效的控制了 Sb排放,但脱硫后饱和湿烟气仍然含有大量潜热,同时携带有少量的微细颗粒、SO_2等污染物,现有的湿式静电等末端控制技术难以兼顾余热回收与污染物的协同脱除。本文针对上述问题,提出了烟气深度降温余热回收协同污染物脱除技术,在理论分析基础上,针对不同位置烟气的特点,分别设计并搭建了湿烟气冷凝换热协同污染物脱除中试试验系统以及SO_3冷凝机理实验系统,研究了烟气深度降温余热回收效率以及冷凝换热过程中微细颗粒物、SO_2、SO_3的脱除规律,为促进烟气余热回收与污染物协同脱除技术提供基础数据。首先,本文在理论分析的基础上,建立了脱硫后饱和湿烟气冷凝换热协同污染物脱除试验系统,通过冷凝实现烟气深度温降,来研究冷凝器对湿法脱硫后湿烟气的换热性能,以及不同运行参数下微细颗粒物、SO_2脱除效率,研究发现:冷凝器对脱硫后饱和湿烟气的换热性能良好,凝结水回收率在90%以上。湿烟气降温冷凝对微细颗粒的分级脱除效率整体呈"U"型分布,脱除效率随冷却水流量与湿烟气温降的增加而增加,随湿烟气中微细颗粒物浓度、烟气流量的增加而降低。实验中在最佳工况下,湿烟气温度从50℃降到20℃,微细颗粒物脱除效率可达40%左右;烟气深度冷凝对SO_2也有一定脱除效果,烟气流量不变,其脱除效率随冷却水流量与入口 SO_2浓度的增加均先增加后减少,其脱除量随入口 SO_2浓度的增加而增加,在入口浓度200mg/Nm3左右时迅速上升,此后增长趋于稳定。试验中在最佳工况下SO_2脱除效率在15%～20%之间,通过增加钙基吸收剂可有效提高脱硫效率。其次,建立了SO_3冷凝机理实验系统,研究了不同条件下SO_3冷凝析出规律,研究发现:烟温低于10C℃时,SO_3凝结收集效率随着冷凝温度的增加而增加;烟温到100～～20℃左右时,可收集几乎全部的SO_3;随着冷凝温度继续增加到烟气酸露点以上时,SO_3收集率迅速降低。SO_3及水蒸气浓度的增加都会导致SO_3冷凝收集效率降低,且SO_3浓度对收集效率产生的影响较大。相同条件下,SO_3收集率:直型冷凝管蛇型冷凝管带过滤棉的蛇型冷凝管,而单纯增加冷凝管的长度,对收集效率的增加影响不大。
[Abstract]:The flue gas of coal-fired boiler tail contains a large amount of waste heat and pollutants such as so _ 2 / so _ 3 and so _ 2 / so _ 3, etc. Although the large-scale application of wet flue gas desulfurization (WFGD) can effectively control the discharge of SB, the saturated wet flue gas still contains a large amount of latent heat after desulphurization.At the same time, a small amount of fine particles such as so _ 2 are carried. The existing wet electrostatic equal-end control technology is difficult to take into account the waste heat recovery and the coordinated removal of pollutants.In order to solve the above problems, this paper puts forward the technology of removing pollutants from waste heat recovery by deep cooling of flue gas. On the basis of theoretical analysis, according to the characteristics of flue gas in different locations,A pilot test system for the co-removal of pollutants from wet flue gas condensation heat transfer and an experimental system for the mechanism of SO_3 condensation were designed and built, respectively. The recovery efficiency of waste heat from deep cooling of flue gas and the removal law of fine particulate matter so _ 2SO _ 3 in the process of condensation and heat transfer were studied.It provides the basic data for promoting the technology of flue gas waste heat recovery and pollutant removal.Firstly, on the basis of theoretical analysis, this paper establishes the experimental system of condensing heat transfer of saturated wet flue gas after desulphurization, and realizes the deep temperature drop of flue gas through condensation to study the heat transfer performance of the condenser for wet flue gas after wet desulphurization.The results show that the condenser has good heat transfer performance for saturated wet flue gas after desulphurization, and the condensate recovery rate is over 90%.The fractionation efficiency of wet flue gas cooling and condensing is "U". The removal efficiency increases with the increase of cooling water flow and the temperature drop of wet smoke, and decreases with the increase of the concentration of fine particles in the wet flue gas and the increase of flue gas flow rate.Under the optimum conditions, the removal efficiency of fine particles can reach about 40% when the wet flue gas temperature is reduced from 50 鈩，

本文编号：1727128