1050MW超超临界燃煤发电机组主蒸汽氢电导偏高运行分析及处置

Analysis and Treatment of High Main Steam Hydrogen Conductivity of 1050MW Ultra-supercritical Coal-fired Power Generation Unit

福建省某百万千瓦4号燃煤发电机组在运行过程中发现机组主蒸汽氢电导有轻微上升趋势,峰值到0.14μs/cm但未超过规定限值0.15μs/cm。火力发电厂热力系统水汽中所含有的物质比较简单并相对稳定,在其他化学仪表使用可靠性低的情况下要重视氢导电率表的作用,当水汽中阴离子(如氯离子、硫酸根、乙酸根等)的含量发生变化时,氢电导率能迅速直接地反映出来,而这些阴离子也正是水汽监督的对象。主蒸汽氢电导偏高说明蒸汽内携带了一定量的对水汽系统有害的阴离子,长期偏高会造成炉水pH降低、汽轮机低压缸部件腐蚀等一系列问题。本文通过问题导向分析、主蒸汽阴离子普查及除盐水分段排除法最终解决了导致主蒸汽氢电导有上升的根本原因,对电力行业超超临界机组水汽质量监督管理具有一定的借鉴意义。

During the operation of a certain million-kilowatt No.4 coal-fired generating unit in Fujian Province,it was found that the hydrogen conductivity of the unit's main steam had a slight upward trend,reaching a peak value of 0.14μs/cm but not exceeding the specified limit of 0.15μs/cm.The substances contained in the water vapor in the thermal system of thermal power plants are relatively simple and relatively stable.When other chemical instruments have low reliability,the role of the hydrogen conductivity meter must be paid attention to.When the content of anions such as chloride ions,sulfate,and acetate in the water vapor changes,the hydrogen conductivity can be quickly and directly reflected,and these anions are also the objects of water vapor monitoring.The high hydrogen conductivity of the main steam indicates that the steam carries a certain amount of anions that are harmful to the water-vapor system.Long-term high hydrogen conductivity will cause a series of problems such as a decrease in the pH of the boiler water and corrosion of the low-pressure cylinder parts of the steam turbine.This paper finally solves the root cause of the increase in hydrogen conductivity of main steam through problem-oriented analysis,main steam anion survey and desalted water segmentation elimination method,which has certain reference significance for the supervision and management of water vapor quality of ultra-supercritical units in the power industry.