Research on efficiency deep improvement technologies of vertical airflow electrostatic precipitator
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摘要:
常规电除尘存在细颗粒粉尘难荷电、反电晕、二次扬尘等技术难题，限制了除尘效率的进一步提升。针对电除尘深度提效技术进行了研究，提出进口烟箱预收尘—电场尾部二维收尘—出口烟箱防逃逸电除尘深度提效工艺，研制了垂直气流方向的“W”形和梯形网状收尘装置，显著增大了电除尘收尘面积，解决了二次扬尘问题。垂直气流电除尘深度提效技术在630 MW燃煤机组工程应用结果表明：在保持电除尘外形尺寸、电场数量不变的情况下，出口烟尘浓度可控制在10 mg/m3以下；电除尘出口烟尘浓度由改造前的14.4 mg/m3降至6.5 mg/m3，提效幅度高达54.9%，与低低温电除尘技术提效幅度相当，可实现烟尘超低排放。
Abstract:There are some technology problems of routine electrostatic precipitator, such as difficult charging of fine-particle dust, anti-corona, and dust re-entrainment. These technology problems limit the further improvement of dust removal efficiency. The efficiency deep improvement technologies of electrostatic precipitator were studied in detail. Firstly, the dust-removal efficiency deep improvement process was put forward, which included dust pre-collection in inlet smoke box, two-dimensional dust collection at the tail of electric fields, and dust anti escape technology in outlet smoke box. Secondly, the "W" shaped and trapezoid net-like dust collection devices perpendicular to the air flow direction were developed, which significantly increased the dust collecting area of electrostatic precipitator and solved the problem of dust re-entrainment. At last, the efficiency deep improvement technologies of vertical airflow electrostatic precipitator were applied on 630 MW coal-fired unit project. The application results showed that the dust concentration could be controlled to be lower than 10 mg/m3 at the outlet of electrostatic precipitator without changing the shape and size of the electrostatic precipitator and the number of electric fields. The dust concentration at the outlet of electrostatic precipitator was reduced from 14.4 mg/m3 before transformation to 6.5 mg/m3 by applying the technology. And the efficiency improvement range was as high as 54.9%, which was equivalent to that of the low-temperature electrostatic precipitation technology. Apparently, the dust concentration could achieve ultra-low emissions by applying the technology.
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图 1 电除尘深度提效技术原理示意
Figure 1. Schematic diagram of principle of the efficiency deep improvement technology of electrostatic precipitator
图 9 电除尘提效技术工艺布置方案
Figure 9. Process layout of electrostatic precipitator efficiency improvement technology
图 12 电除尘器能效等级对比
Figure 12. Comparison of energy efficiency grades of electrostatic precipitators
表 1 技术方案对比
Table 1. Comparison of technical schemes
项目 电除尘深度
提效技术电袋复合除尘技术 进气烟箱 预收尘改造 不变 一电场 检修 进行规范性大修，主要包括阴极
系统、阳极系统、阴阳极振打系统二电场 检修 进行规范性大修，主要包括阴极
系统、阳极系统、阴阳极振打系统三电场 检修，尾端增加垂
直气流除尘装置拆除极板、极线、振打系统，
布置滤袋、清灰系统等四电场 检修，尾端增加
垂直气流除尘装置拆除极板、极线、振打系统，
布置滤袋、清灰系统等五电场 检修 拆除极板、极线、振打系统，
布置滤袋、清灰系统等出气烟箱 梯形多通道三维
除尘装置改造改造 灰斗 规范性大修 不变 气力输送系统 不变 四、五电场改造 引风机 不变 扩容改造 
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表 2 技术经济性比较
Table 2. Contrast of technical economy
项目 电除尘深度提效技术 电袋复合除尘技术 烟尘排放浓度/(mg/m3) ≤10 ≤10 改造工作量 较小 大 运行维护工作量 小 换袋工作量大 机组改造停炉时间/d 50 60 新增阻力/Pa 50 1 000 一次投资/万元 1 000 3 000 年运行维护费用/万元 150 450
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表 3 改造前后试验数据
Table 3. Test data before and after transformation
项目 改造前 改造后 工况1 工况2 机组负荷率/% 95.2 98.7 98.7 机组功率/MW 600 622 622 烟气流量/(m3/h) 2 863 329 2 923 187 2 923 187 烟温/℃ 135.0 134.5 134.5 系统阻力/Pa 197.9 242.5 242.5 除尘段电能消耗/(kW·h) 703.7 942.4 1382.0
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