Removal effect of the low-low temperature electrostatic precipitator on polycyclic aromatic hydrocarbons

Abstract

The low-low temperature electrostatic precipitator (LLT-ESP) is one of the most used devices for pollutant control in ultra-low emission coal-fired power plants. This study investigated the influence of the LLT-ESP on polycyclic aromatic hydrocarbons (PAHs) distributions in flue gas from an ultra-low emission coal-fired power plant. The total gas-phase PAH concentration was reduced from 27.52 μg/m to 3.38 μg/m. The total particulate-phase PAH concentration decreased from 14.36 μg/m to 0.34 μg/m. The removal efficiency of the LLT-ESP for gas-phase and particulate phase carcinogenic higher molecular weight (HMW) PAHs was 85% and 99%, respectively. The total concentration of 16 selected PAHs in feed coal was 98.16 μg/g. The fly ash particle size successively decreased from Electric Field 1 (F1) to Electric Field 4 (F4). The total PAH concentration decreased from F1 to F2 but increased again from F3 to F4. The flue gas cooling process significantly contributed to the elimination of both gas- and particulate-phase PAHs in the flue gas. Presumably, most of the condensed PAHs were adhered to or absorbed in the fly ash and were scavenged in Field 1. Both gas- and particulate-phase 5- and 6-ring PAHs in the flue gas were completely removed in Field 1. The discharge process in the electric fields may promote the formation of several 4- or 5-ring PAHs. In this study, benzo[k]fluoranthene (BKF) and benzo[a]pyrene (BaP) were regenerated in the particles rather than in the flue gas during the discharge process in the electric fields.

Distribution of Organic Compounds in Coal-Fired Power Plant Emissions

“…For this reason, another numerical comparison was established, based on the following equation where C om is the portion of organic compounds that undergoes combustion and C coal , C gas , C ash , and C slag represent the concentrations (in μg·kg –1 or mg·m –3 ) of organic compounds in coal, flue gas, fly ash, and slag, respectively. Considering the high boiling points of PAHs and the results of prior research, ,, it was assumed that PAHs were not contained in the flue gas below 100 °C, such that the C gas value for PAHs was zero. M coal , M gas , M ash , and M slag represent the mass or volume (in kg or m 3 ) of coal, flue gas, fly ash, and slag, respectively, consumed or generated at a fixed full boiler load over the span of 1 h. The equation was also employed, where C coarse‑ash and C fine‑ash represent the concentrations (in μg·kg –1 ) of organic compounds in the coarse and fine ash, respectively, and M coarse‑ash and M fine‑ash represent the masses of coarse and fine ash generated at a 100% boiler load over 1 h (in kg).…”

“…where C om is the portion of organic compounds that undergoes combustion and C coal , C gas , C ash , and C slag represent the concentrations (in μg•kg −1 or mg•m −3 ) of organic compounds in coal, flue gas, fly ash, and slag, respectively. Considering the high boiling points of PAHs and the results of prior research, 17,21,22 it was assumed that PAHs were not contained in the flue gas below 100 °C, such that the C gas value for PAHs was zero. M coal , M gas , M ash , and M slag represent the mass or volume (in kg or m 3 ) of coal, flue gas, fly ash, and slag, respectively, consumed or generated at a fixed full boiler load over the span of 1 h. The equation…”

The Assessment of Indoor Formaldehyde and Bioaerosol Removal by Using Negative Discharge Electrostatic Air Cleaners

“…The collection rate increases as the discharge voltage increases [ 8 , 9 , 10 ]. During the ESP discharge process, the air surrounding the discharge electrode can form a plasma, which destroys gaseous air pollutants [ 11 , 12 , 13 ]. Han et al (2017) [ 14 ] studied bioaerosol removal efficiency at ESP and discovered that, during the charging process, the removal amount of charged bioaerosols was proportional to the square of particle diameter.…”

Adsorption of Volatile Organic Compounds at Medium-High Temperature Conditions by Activated Carbons

“…In addition to the conventional pollutants such as particulate matter, NO x , and SO 2 , some organic pollutants are generated as well . As opposed to industrial sources (e.g., paint production and petrochemical industries), the compositions of organic pollutants produced by coal-fired power plants, as determined by combustion conditions (e.g., boiler temperature and amount of excess air) and air pollution control devices (APCDs), are complex. , Among all of the organic pollutants, volatile organic compounds (VOCs), and semivolatile organic compounds (SVOCs), such as benzene, propane, chlorobenzene, toluene, naphthalene, and acenaphthene, are the primary components in flue gas . Their concentrations are much lower than those of other polluting gases discharged from industrial sources; however, coal-fired power plants are still a major anthropogenic source of organic pollutants because a large amount of flue gas is emitted into the atmosphere .…”