Effects of the Changes of Load and Flue Gas Temperature on the Emission of Particulate Matter from the Coal-fired Unit

Yujia Wu,Zhenyao Xu,Shengyong Lu,Minghui Tang,Siqi Liu

doi:10.4209/aaqr.210268

Abstract

Due to the rapid development of new energy power generation, most coal-fired power plants cannot always operate at full capacity. The changes in flue gas temperature at the inlet of low-low temperature electrostatic precipitator and unit load are the important factors affecting the emission of condensable and filterable particulate matter (CPM and FPM). CPM and FPM were sampled from a typical ultra-low emission coal-fired power unit with different operating loads (650, 850, and 1000 MW) and flue gas temperature (90 and 100°C). The emission concentration of FPM, organic and inorganic components of CPM were obtained. The representative organic matter n-alkanes and phthalates in CPM (C-N and C-P) were quantified. The concentrations of CPM emitted from the coal-fired unit ranged from 6.66–8.93 mg Nm–3, which was 2.4–6.2 times higher than FPM. The emission concentration of CPM was the lowest from the unit under high load and low flue gas temperature. The decrease of flue gas temperature increased of SO42– emission concentration, which was the soluble ion with the highest concentration in CPM. The effect of unit load and flue gas temperature changes on monocomponent C-N and C-P was limited; however, the effect on its total emission concentration was consistent with that on CPM. The concentrations of n-alkanes and phthalates in CPM accounted for more than 20% at all four stages.

Highlights

It is observed that the emission concentrations of filterable particulate matter (FPM) with different particle sizes from different loads of the unit are close, all below 3 mg Nm–3
It is worth noting that the concentration of CPMo in flue gas emitted from units increased with the decrease of the load
This conclusion suggests that in the process of removing condensable particulate matter (CPM) from low-low temperature electrostatic precipitator (LLT-ESP), the main way of removal may be the change of phase state of CPMo which is adsorbed on FPM and collected by dust collector plate due to the decrease of temperature

Summary

Introduction

According to statistics (BP, 2020), coal is primarily used as fuel in China, which still accounted for nearly 60% of China's primary energy consumption in recent years. What is not allowed to ignore is multiple pollutants such as particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx), and organic pollutants are emitted from coal combustion, which causes unfavorable effects on the environment and human health (Wang et al, 2016; Tong et al, 2018; Lu et al, 2020; Zhang et al, 2020; Zhou et al, 2020; Sun et al, 2021; Wu et al, 2021a). Ultralow-emission retrofits for coal-fired power plants (CFPPs) have been implemented in China for years (Ruan et al, 2019). Desulfurization, and denitrification technologies have been formed and applied in the field of coal combustion (Xu et al, 2000; Zhang et al, 2006; You and Xu, 2010; Zheng et al, 2018b)

Methods

Results

Conclusion