燃煤电厂电除尘出口颗粒物采样方法初步分析

Preliminary Comparison of Sampling Methods for Paticles of Electrostatic Precipitator Outlet in Coal-fired Power Plant

燃煤电厂排放烟气中颗粒物浓度的降低和颗粒粒径的减小,为颗粒物采用简便的单点恒速采样提供了可能。参考烟气(废气)中气态污染物可单点恒速采样的原理,探究燃煤电厂颗粒物单点采样的理论条件,得到燃煤电厂电除尘(ESP)、湿法脱硫(WFGD)后烟气单点采样的条件为:颗粒流态为层流、颗粒粒径≤4μm。实际烟气中颗粒物符合采样条件,认为燃煤电厂ESP,WFGD后颗粒物可单点采样。在3家燃煤电厂ESP出口同步开展颗粒物多点等速、单点恒速采样的对比测定,并对采样结果进行相对标准偏差(RSD)及统计学分析。结果显示,平行样的RSD在2.1%~24.1%之间,符合国家相关标准要求,测定结果一致度较好;2种采样方法测定结果总体方差相等,且无显著性差异。现场试验结果与理论分析一致,证实燃煤电厂ESP出口颗粒物可以采用简便的单点恒速采样。

The reduction of particle concentration and the decrease of particle size in the flue gas of coal-fired power plants to provide the possibility of using single-point and constant-speed sampling for particles. Referring to the principle of single point constant speed sampling for gaseous pollutants in flue gas（exhaust gas）,the theoretical analysis of single point sampling of particulate matter in coalfired power plants has been carried out during the same period. The conditions for single-point sampling of smoke gas after ESP or WFGD are as follows：the smoke particles are in a laminar flow state and particle size less than 4 μm. The particles in the actual flue gas are in accordance with the sampling conditions, and it is considered that the particles of ESP and WFGD in coal-fired power plants can be sampled by a single-point.In this paper, the comparative determination of multi point constant velocity and single point constant velocity sampling was carried out at the ESP exit of 3 coal-fired power plants, and the RSD（relative standard deviation） and statistical analysis were carried out on the sampling results.The following results were obtained： the parallel RSD is between 2.1% and 24.1%, which accords with the national standard requirement, and it is proved that the measurement results are consistent. The results showed that the total variance of the two samples was equal, and there was no significant difference between results of the test. The results from the field test are in agreement with the theoretical analysis. It is proved that the ESP outlet particles in the coal-fired power plant can be sampled at single-point and constant-speed.