湿法脱硫协同去除细颗粒物的研究进展

doi:10.16085/j.issn.1000-6613.2018-1961

摘要/Abstract

摘要：

石灰石-石膏湿法烟气脱硫（wet flue gas desulfurization，WFGD）工艺具有吸收剂来源广、成本低、脱硫效率高等优点，成为应用最广泛的烟气脱硫工艺。湿法脱硫过程中，燃煤烟气在喷淋浆液的洗涤作用下不仅能高效脱除SO₂而且可以协同去除细颗粒物,但同时存在石灰浆液夹带导致出口颗粒物浓度增加的问题。本文首先综述了湿法脱硫的应用现状，对比了湿法脱硫系统前后细颗粒物物性变化，然后概述了应用于湿法脱硫协同去除细颗粒物的新方法，包括脱硫塔内部结构调整以及促进细颗粒物凝聚长大，同时分析了湿法脱硫工艺中采用荷电细水雾吸附细颗粒物并增益脱除SO₂的可行性，以期为燃煤电厂细颗粒物排放控制提供借鉴。最后指出未来湿法脱硫技术不仅要实现高脱硫效率，而且能有效脱除未被静电除尘器脱除的细颗粒物，湿法脱硫技术的发展趋势是多种技术耦合实现多污染物的协同脱除。

关键词: 湿法脱硫, 除尘, 结构调整, 蒸发相变, 荷电水雾

Abstract:

Limestone-gypsum wet flue gas desulfurization (WFGD) process has become the most widely used FGD process due to its wide source of absorbent, low cost and high desulfurization efficiency. In the wet desulfurization process, the coal-fired flue gas is washed by the spray slurry. Not only SO₂ can be removed efficiently, but also fine particles can be synergistically removed. However, there is also a problem that the concentration of the particulate matter in the outlet increases due to the entrainment of the lime slurry. In this paper, the application status of wet desulfurization have been reviewed firstly, the physical properties of fine particles before and after wet desulfurization system have been compared. Then the new methods for synergistic removal of fine particles by wet desulfurization have been outlined. The methods comprise the internal structure adjustment of the desulfurization tower and promoting the agglomeration of fine particles. And then the feasibilities of using charged water mist to adsorb fine particles and facilitating SO₂ removal in WFGD process have been analyzed. These methods may provide reference for the control of fine particulate matter emission in coal-fired power plants. Finally, It is pointed out that the future wet desulfurization technology not only achieve high desulfurization efficiency, but also can effectively remove fine particles that are not removed by electrostatic precipitator. The development trend of wet desulfurization technology is to achieve synergistic removal of multiple pollutants by multi-technology coupling.

Key words: wet flue gas desulfurization (WFGD), dust removal, structural adjustment, evaporation phase transition, charged water mist

中图分类号:

TK175

王军锋, 李金, 徐惠斌, 刘璐, 郑高杰. 湿法脱硫协同去除细颗粒物的研究进展[J]. 化工进展, 2019, 38(07): 3402-3411.

Junfeng WANG, Jin LI, Huibin XU, Lu LIU, Gaojie ZHENG. Advances in research on wet desulfurization andsynergistic removal of fine particles[J]. Chemical Industry and Engineering Progress, 2019, 38(07): 3402-3411.

图/表 10

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烟气脱硫种类	特点	优点	缺点
干法	无液相参与，脱硫过程及脱硫产物均处于干状态	设备腐蚀小，无废水排出，脱硫后无明显温降，有利于烟囱排气扩散	设备庞大，反应速率慢，脱除效率较低，飞灰与脱硫产物混合，脱硫副产物较难利用
湿法	吸收剂为液体或浆液，脱硫过程及脱硫产物均处于湿状态	气液反应，脱硫反应速率快，脱硫效率高达90%以上	脱硫设备初投资大，运行费用高，系统易结垢腐蚀，脱硫废水较难处理
半干法	吸收剂浆液雾化喷入吸收塔，经吸收烟气热量后脱硫产物以干态排出	系统相对简单，投资低，运行费用不高，无废水排出，脱硫产物易处理	脱硫剂在吸收塔内停留时间短，脱硫效率和脱硫剂利用率较低

烟气脱硫种类	特点	优点	缺点
干法	无液相参与，脱硫过程及脱硫产物均处于干状态	设备腐蚀小，无废水排出，脱硫后无明显温降，有利于烟囱排气扩散	设备庞大，反应速率慢，脱除效率较低，飞灰与脱硫产物混合，脱硫副产物较难利用
湿法	吸收剂为液体或浆液，脱硫过程及脱硫产物均处于湿状态	气液反应，脱硫反应速率快，脱硫效率高达90%以上	脱硫设备初投资大，运行费用高，系统易结垢腐蚀，脱硫废水较难处理
半干法	吸收剂浆液雾化喷入吸收塔，经吸收烟气热量后脱硫产物以干态排出	系统相对简单，投资低，运行费用不高，无废水排出，脱硫产物易处理	脱硫剂在吸收塔内停留时间短，脱硫效率和脱硫剂利用率较低

湿法脱硫技术	脱硫吸收剂	优点	缺点	脱硫副产物	技术适用性
石灰石-	石灰石	脱硫效率高达95%以上，吸收剂来源丰富且廉价，技术成熟	工艺流程复杂，投资运行费用高，脱硫废水较难处理，设备结垢腐蚀较严重	石膏，回收利用	适用于大容量机组，煤种适用性强，高硫煤低硫煤都能适用
石膏法	石灰石	脱硫效率高达95%以上，吸收剂来源丰富且廉价，技术成熟	工艺流程复杂，投资运行费用高，脱硫废水较难处理，设备结垢腐蚀较严重	石膏，回收利用	适用于大容量机组，煤种适用性强，高硫煤低硫煤都能适用
氧化镁法	氧化镁	脱硫效率高达95%以上，甚至高于石灰石-石膏法，氧化镁可循环利用，无废渣产生	工艺流程复杂，氧化镁循环利用过程中存在煅烧过程，工艺能耗较高	亚硫酸镁，分解煅烧后得到氧化镁循环利用	适用于中小机组，煤种适用性强
氨法	氨水	脱硫效率达90%以上，系统简单，投资费用较低，无废水废渣排放	吸收剂氨水价格较高，工艺成本较高，设备腐蚀严重	硫酸氨，回收可作硫铵化肥	现用于中小型机组，适用于中高硫煤的脱硫
海水法	海水	脱硫效率达90%以上，无需制备脱硫剂，无腐蚀、结垢、堵塞问题，投资运行费用低	只适用于海滨电厂，占地面积大，脱硫后产生的重金属沉积可能对海洋环境产生危害	硫酸盐，脱硫海水处理后排入海洋	适用于大中型机组，中低硫煤脱除效果较好，高硫煤烟气脱硫难以达到排放要求

湿法脱硫技术	脱硫吸收剂	优点	缺点	脱硫副产物	技术适用性
石灰石-	石灰石	脱硫效率高达95%以上，吸收剂来源丰富且廉价，技术成熟	工艺流程复杂，投资运行费用高，脱硫废水较难处理，设备结垢腐蚀较严重	石膏，回收利用	适用于大容量机组，煤种适用性强，高硫煤低硫煤都能适用
石膏法	石灰石	脱硫效率高达95%以上，吸收剂来源丰富且廉价，技术成熟	工艺流程复杂，投资运行费用高，脱硫废水较难处理，设备结垢腐蚀较严重	石膏，回收利用	适用于大容量机组，煤种适用性强，高硫煤低硫煤都能适用
氧化镁法	氧化镁	脱硫效率高达95%以上，甚至高于石灰石-石膏法，氧化镁可循环利用，无废渣产生	工艺流程复杂，氧化镁循环利用过程中存在煅烧过程，工艺能耗较高	亚硫酸镁，分解煅烧后得到氧化镁循环利用	适用于中小机组，煤种适用性强
氨法	氨水	脱硫效率达90%以上，系统简单，投资费用较低，无废水废渣排放	吸收剂氨水价格较高，工艺成本较高，设备腐蚀严重	硫酸氨，回收可作硫铵化肥	现用于中小型机组，适用于中高硫煤的脱硫
海水法	海水	脱硫效率达90%以上，无需制备脱硫剂，无腐蚀、结垢、堵塞问题，投资运行费用低	只适用于海滨电厂，占地面积大，脱硫后产生的重金属沉积可能对海洋环境产生危害	硫酸盐，脱硫海水处理后排入海洋	适用于大中型机组，中低硫煤脱除效果较好，高硫煤烟气脱硫难以达到排放要求

作者	测试范围	脱除效果	粒度分布	形态特性	元素组分
周科等^[16]	PM₁₀分级脱除	0.3μm以下颗粒物浓度增加，总量增加160%左右；0.3μm以上颗粒物浓度总量减少40%左右	脱硫前后都呈单峰分布，峰值粒径在2μm左右	由脱硫前单颗粒或多颗粒团聚形态转变为不规则的熔融态	脱硫后0.3μm以下颗粒物中Ca和S含量明显增加；0.3μm以上颗粒物元素浓度无明显变化
徐鹏等^[17]	PM_2.5 PM₁ PM_0.5 PM_0.2	脱硫后PM_2.5、PM₁、PM_0.5、PM_0.2质量分数呈现不同程度的增长，且随着粒径的减小增长比例增加	脱硫前后颗粒物粒径均呈单峰分布，脱硫前峰值粒径在0.2~0.4μm，脱硫后峰值在0.2~0.3μm	—	脱硫后Ca元素浓度增加，Al和Si元素浓度略微降低
陈浩等^[18]	总悬浮颗粒物 PM₁₀₊ PM_2.5~10 PM_1~2.5	总颗粒脱除效率为46.8%，脱除效率随粒径的减少而降低，PM_1~2.5脱除效率为15%	—	脱硫后PM₁₀₊、PM_2.5~10颗粒物为不规则块状或链状，PM_1~2.5主要呈圆形，几乎没有团聚现象	对比除雾器冲洗和不冲洗两种状态，冲洗作用下Ca、S、C、O元素含量显著降低
Du等^[19]	PM_2.5	脱硫过程对PM_0.38~2.5的细颗粒物有较好的脱除效果，PM_0.38的细颗粒物捕集效果较差，甚至出口PM_0.38数量浓度增加	PM_2.5的数量浓度主要取决于PM_0.38，脱硫后粒径分布由双峰变为单峰，峰值粒径由0.12μm和0.76μm变为0.07μm	燃烧产生的PM_2.5主要为球形，还包括熔融黏结形成的不规则形	脱硫后Al、Si和Ca的元素含量降低，S元素含量增加