燃煤烟气半干法脱氯实现脱硫废水零排放基础研究

发布时间：2018-05-13 07:29

  本文选题：脱硫废水 + 零排放　； 参考：《浙江大学》2017年硕士论文

【摘要】：近年来,我国燃煤电厂脱硫废水零排放已得到广泛重视。其中烟道喷雾蒸发技术因具有占地面积小、工艺简单、改造费用低等优点而受到广泛关注,但目前此技术尚未成熟,废水量过大可能导致废水回喷烟道后的积灰及腐蚀等问题。当烟气中的HCl被大量脱除后,脱硫废水排放率将大幅度减少。为解决废水烟道喷雾蒸发技术中因废水量过大导致的问题,本文创新性地提出了一种半干法脱氯技术,即首先脱除烟气中的HCl,大幅度减少脱硫废水量,再将脱硫废水作为碱基溶剂回喷到烟气中,实现脱硫废水零排放。利用CHEMKIN软件对半干法脱氯过程进行了化学动力学模拟,研究了在燃煤电厂烟气气氛中,NaOH与HCl、SO2、SO3的反应过程与程度;搭建实验台模拟空预器至除尘器间烟道,研究了 Na/Cl、HF、碱基种类、S02浓度、烟温及停留时间对HCl反应效率的影响。并得出以下结论:HCl的反应效率与Na/Cl呈正相关,随着Na/Cl的增大,HCl的反应效率逐渐升高,但Na/Cl5后增长趋势逐渐变缓;S02的反应效率随Na/Cl的增大近线性上升;烟气中HF的存在对半干法脱氯过程的影响较小;烟气中SO2对HCl的脱除过程有一定干扰作用,但HCl的反应效率依然处于较高水平,Na/Cl 一定时,SO2的浓度每变化1000mg/Nm3,HCl的反应效率变化约13%,对某台特定锅炉而言,SO2浓度一般仅在小范围内变化,不会对HCl的反应效率的稳定性造成太大影响;碱基物质对HCl的脱除效果与其碱性强弱有关,碱基物质按脱除效果强弱排列依次为NaOH,Na2CO3,NaHCO3;烟温的变化将显著影响半干法脱氯的反应效率,随着温度由100℃C上升到140℃,HCl的反应效率逐渐下降,由78.67%下降到59.23%;随着停留时间由0.5s延长至2.5s,HCl的反应效率有轻微幅度的上升,由68.13%上升至73.01%。通过对一台660WM机组进行分析计算,研究了半干法脱氯后脱硫废水量、废水回喷后的烟气温降、运行经济性及对粉煤灰利用的影响。通过计算可知半干法脱氯后,脱硫废水量显著降低71.16%。此时将废水回喷烟道,烟气温降较小,仅为2.49℃。半干法脱氯系统简单,成本较低,不会对粉煤灰的综合利用造成显著的不利影响。
[Abstract]:In recent years, zero discharge of desulfurization wastewater from coal-fired power plants has been paid more and more attention. The flue spray evaporation technology is widely concerned because of its advantages of small area, simple process and low cost of renovation. However, at present, the technology is not yet mature, and too much waste water may lead to ash deposition and corrosion after the waste water is returned to the flue. After the removal of HCl from flue gas, the discharge rate of desulfurization wastewater will be greatly reduced. In order to solve the problem caused by excessive amount of waste water in flue spray evaporation of waste water, a semi-dry dechlorination technology is proposed in this paper, that is, the HCl in flue gas is removed first, and the amount of waste water in desulfurization is greatly reduced. The desulphurization wastewater was injected back into the flue gas as base solvent to realize zero discharge of desulfurization wastewater. The chemical kinetics simulation of semi-dry dechlorination process was carried out by using CHEMKIN software, the reaction process and degree of NaOH and HClNSO _ 2so _ 3 in the flue gas atmosphere of coal-fired power plant were studied, and the flue gas between the air preheater and the dust collector was simulated by an experimental bench. The effects of the concentration of Na / Cl-HF, base species S02, smoke temperature and residence time on the HCl reaction efficiency were studied. The following conclusions are drawn: the reaction efficiency of Na/Cl is positively correlated with the reaction efficiency of Na/Cl, and increases gradually with the increase of Na/Cl, but the reaction efficiency of S02 increases linearly with the increase of Na/Cl after Na/Cl5. The presence of HF in flue gas has little effect on the process of semi-dry dechlorination, and SO2 in flue gas has a certain interference effect on the process of HCl removal. However, the reaction efficiency of HCl is still at a high level. When the concentration of so _ 2 varies by 1000mg / Nm _ 3H _ 2HCl, the reaction efficiency of so _ 2 is about 13%. For a particular boiler, the concentration of so _ 2 generally changes only in a small range. The stability of the reaction efficiency of HCl will not be greatly affected, and the removal effect of base material on HCl is related to its alkalinity. In order of removal effect, NaOHN Na2CO3 + NaHCO3, the change of smoke temperature will significantly affect the dechlorination efficiency of semi-dry process, and the reaction efficiency will decrease with the increase of temperature from 100 鈩，

本文编号：1882244