The fine particles in desulfurized flue gas comprise coal-fired fine particles from combustion and generated fine particles from desulfurization. The abatement of fine particle emission by heterogeneous vapor condensation during wet flue gas desulfurization (WFGD) is experimentally investigated in this paper. A supersaturation atmosphere, which is necessary for heterogeneous vapor condensation, is established by increasing the humidity and reducing the temperature of the flue gas before WFGD. The improvement of the removal of coal-fired fine particles and the inhibition of generated fine particles formation in desulfurization process by heterogeneous vapor condensation were studied, and the influences of inlet flue gas parameters on the emission of total fine particles, including coal-fired fine particles and generated fine particles during desulfurization, are examined. The results indicate that the total emission of fine particles in desulfurized flue gas can be significantly decreased via heterogeneous vapor condensation. This decrease in the emission of coal-fired fine particles is mainly related to the removal of fine particles via heterogeneous vapor condensation, and the generation of fine particles from desulfurization is abated because of both the decrease in the inlet flue gas temperature and heterogeneous vapor condensation. Higher inlet flue gas humidity can adequately reduce the emission of generated fine particles from desulfurization. The reduction in the flue gas temperature before WFGD is the main factor that inhibits the formation of fine particles and removes coal-fired fine particles during desulfurization.
The surface microstructure of the current collectors significantly affects the electrochemical performance of lithium-ion batteries (LIBs). This study shows that an effective method of orthogonal ploughing/extrusion is to fabricate three-dimensional (3D) microstructures directly on a copper plate used as the current collector for LIBs. Such an on-chip-structured current collector avoids introducing additional layers or components, dispenses with complex fabrication and integration, as well as provides abundant surface structures and morphologies. It is simply combined with mesocarbon microbeads graphite powders to form the anode electrode of CR2032 coin half-cells. Results indicate that the prepared current collector facilitates a high reversible discharge specific capacity of 341.8 mAh g–1 after 200 cycles at a current rate of 0.2 C with a capacity retention rate as high as 98.6%. This performance is significantly higher than the traditional bare copper current collector which maintains only 262.2 mAh g–1 with a capacity retention rate of 79.6% at 0.2 C after 100 cycles. It is proven that the combined microstructures of grooves, burrs, and reentrant cavities formed on the surface of the 3D on-chip-structured current collector effectively improve the electrochemical performance of LIBs in terms of reversible specific capacity, cycling stability, electrical conductivity, and Coulombic efficiency.
A new process was proposed to reduce fine particle emissions in coal-fired flue gases via the condensation of SO3 and water vapor. In this new process, hot atomized water was sprayed before the electrostatic precipitator (ESP) system to decrease the flue gas temperature and increase the flue gas humidity, causing the flue gas temperature to drop below the acid dew point; thus, SO3 would condense on the particle surfaces ahead of the ESP, which would enhance the fine particle removal efficiency of the ESP. Then, a fluoroplastic heat exchanger was located between the ESP and the wet flue gas desulfurization (WFGD) system to make the WFGD inlet flue gas temperature decrease further at a high humidity, leading to the condensation of water vapor on the particle surfaces in the desulfurization scrubber, which would improve the removal efficiency of the WFGD. The feasibility of this new process was analyzed by numerical calculation, and the results showed that the new process was feasible for the original flue gas with high SO3 concentrations, high temperature, and high humidity. The effectiveness of this new process under typical operating conditions was also presented. Furthermore, the influence of several main parameters, such as the SO3 concentration of original flue gas, the temperature drop of flue gas before the ESP, and the temperature of flue gas at the WFGD inlet, were also investigated. The results indicated that the fine particle emissions in the final exhausted flue gas would be reduced by 50–70% with this new process.
BACKGROUND: The reduction of sulfuric acid aerosol emissions in coal fired power plant is of great importance. Based on the classical theory of heterogeneous vapor condensation, a novel engineering process was proposed to increase the efficiency of removal of sulfuric acid aerosols by adding moist air in the condensational growth chamber (CGC), following the desulfurization scrubber. RESULTS:The theoretical analysis showed that this novel process was feasible. The experimental results indicated that the efficiency of removal of sulfuric acid aerosols was mainly influenced by the amount of moist air added and the humiture of desulfurized flue gas and moist air. Higher humiture of desulfurized flue gas could promote removal efficiency, whereas higher temperature of moist air was unfavorable. However, the influence of the relative humidity of moist air was not obvious. Moreover, increasing the mixture ratio was also beneficial for the improvement of removal performance in the range below 10:20. CONCLUSION: The process proposed was feasible for industrial application. The efficiency of removal of sulfuric acid aerosols was enhanced to 30-50% by this novel process.
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