This paper reports the experimental investigation of fine particle agglomeration through an in-situ trial on aerodynamic agglomerators installed in front of the electrostatic precipitator (ESP) of a 330 MW PC-fired (i.e. pulverized-coal-fired) boiler. It is demonstrated that the agglomerators greatly reduce the fine particles entering the ESP. In particular, for the present case, the fine particles of the aerodynamic diameter <= 2.5 mu m (PM2.5) and those <= 10 mu m (PM10) are found to decrease 56.2% and 50.6%, hence reducing the overall particle concentration by 26.3 mg/Nm(3) at the outlet of the ESP. Also, the mercury concentration of 891.08 ng/g obtained in the ash from hoppers of the ESP with the agglomerators is 26.4% higher than that of the ESP without agglomerator. Therefore, the application of aerodynamic agglomerators is believed to reduce both emissions of fine particles and mercury from the flue gas of PC-fired boilers. In addition, the reason for the above observations is also explored in the paper. (C) 2015 Elsevier Ltd. All rights reserved.