基于全年在线监测数据的燃煤电厂超低排放特征分析

Emission characteristics of ultra-low emission coal-fired power plants by analyzing data from CEMS

通过收集位于中部地区某省已实现超低排放的139台燃煤机组2017年全年在线监测数据,对烟尘、SO2、NOx小时浓度符合超低限值的时间比率(符合率)、月均浓度值、单位电量排放绩效情况进行了统计对比分析,研究超低排放燃煤电厂大气污染物在线数据排放特征,并在此基础上提出符合我国煤电大气污染物排放实际的在线监测数据达标评判方法。统计结果显示,下半年三种污染物同时符合超低限值的时间比率达到或超过99%的机组占比情况(达到80%以上)明显高于上半年,可见,超低排放机组环保设施的运行和管理的水平在逐渐提高;随着统计时间段加长(从按月度、季度),小时平均浓度100%符合超低限值的概率有所降低,但符合率达到95%及以上的机组占比情况相对稳定(均在90%以上),可见,在火电厂大气污染物排放标准中引入小时均值浓度符合率的评判条件具有科学性和实际意义;139台机组12个月的烟尘、SO2、NOx月均排放浓度均符合超低排放限值,其中90%的月平均浓度分别不超过3.7、24、40mg/m^(3),仅分别占欧盟最严标准限值的37%、16%、27%;90%的月平均绩效分别不超过0.014、0.09、0.16g/(kW·h),仅分别占美国最严标准的35%、20%、50%,可见,我国燃煤电厂大气污染物排放水平均已处于世界领先水平。

In order to study the characteristics and regularity of continuous on-line monitoring data of air pollutants from ultra-low emission coal-fired power plants in China,on-line monitoring data from continuous emission monitoring system(CEMS)of 139 coal-fired units from a province in center China for one year were collected and the hourly concentration compliance rate,monthly averaged concentration and monthly averaged emission performance value distribution of those units were statistically analyzed.The results show that the proportion of units whose time ratio of three pollutants to meet the ultra-low limit at the same time reached or exceeded 99%in the second half of the year was significantly higher than that in the first half of the year;the probability of absolute compliance to ultra-low limits of hourly averaged concentrations declines with the increasing of statistical time period,but the proportion of units with a compliance rate of 95%or more is relatively stable(above 90%);90%of the monthly average concentration of PM,SO2 and NOx emissions from 139 units in 12 months did not exceed 3.7,24 and 40 mg/m^(3),accounting for only 37%,16%and 27%of the EU's most strictest standard limits;90%of the monthly average emission performance value did not exceed 0.014,0.09 and 0.16g/(kW·h),accounting for only 35%,20%and 50%of the US's strictest standards limits.