Removal of Fine Particles from Coal Combustion by Heterogeneous Condensational Enlargement in Wet Flue Gas Desulfurization

According to the enlargement of fine particles by heterogeneous condensation and typical technology of wet flue gas desulphurization (WFGD) system, a novel process is proposed in this paper to remove fine particles from coal-fired flue gas in WFGD system which use limestone as desulfurizer. Supersaturated vapor environment, necessary for the condensational growth of fine particles, can be achieved by means of spray water evaporation at inlet of electrostatic precipitator (ESP) and then cooling by low–low-temperature heat exchanger at WFGD inlet. The preliminary tests show that fine particles can be generated during desulphurization process under many operation conditions. Under the action of heterogeneous condensation, generated fine particles and initial ones can be removed effectively. Different relative humidities and temperatures of flue gas at inlet, liquid-to-gas ratios of WFGD system, and the desulfurization solution temperatures were tested in the experiments. The results show that the remove efficiency of WFGD system is related to its operation conditions. Flue gas with lower temperatures and higher relative humidities has a positive effect on remove efficiency of fine particles. It can be also seen from this paper that in common operation conditions, the remove efficiency for fine particles of WFGD system is ranged from 40 to 50 % by heterogeneous condensation.