The Research Of Seawater Refreshment Process In Seawater Flue Gas Desulfurization Technology

Using seawater as an absorbent of sulfur dioxide in stock gas,the seawater flue gas desulfurization was developed rapidly among coastal power plants.It has many advantages,such as no secondary pollution and byproducts,no comsumtion of fresh water and mineral resource,simple operation,stable system,while there are still some shortages,namely,low oxidation efficiency and big oxidation basin.To study the seawater-refreshment system,two techniques between conventional method and high-voltage pulsed plasma oxidation technology were carried out for basic research in this paper.Firstly,a packed tower reactor was used in order to get the simulated effluent of the scrubbing process.After the scrubbing process,we carried out the conventional air-oxidation experiments.The result shows that,in the condition of pH=3,initial S_(â…£) concentration of 2 mM,temperature of 25℃,air flow rate of 400 L/L,after reacting 90 min,the oxidation efficiency was just up to 20%.Secondly,high-voltage pulsed plasma oxidation technology was firstly induced in the seawater-refreshment system.A novel wetted-wall reactor was designed,and a series of experiments was conducted about the match of the reactor,the characteristic of the effluent and electrical parameters.The results indicted that,in the condition of pH=3,U=20 kV,Cs_(â…£)=2 mM,R=8 mm,L=125 mm and the solution flow rate of 40 m³/m²h,after discharging 15 min,the oxidation efficiency was up to 95%.Compared with the conditional method,the high-voltage pulsed plasma oxidation technology has greatly improved the oxidation efficiency,and no need of adding fresh water to raise the pH value.Preliminary research has shown that high voltage plasma corona discharge produced large amour of active species,such as hydroxyl radical and ozone.In our experiments,it is found that the ozone concentration can stably reach 3000 ppm in gas phase and 1 mg/L in liquid phase.Ozone played an important role in oxidation with S_(â…£).Meanwhile,the peroxide couldn't be detected in our system.Through the comparison between only zone oxidation and plasma oxidation process,we can find that the oxidation efficiency of plasma process was larger than only ozone process, which means the radical species still played a role in oxidating S_(â…£).In spite of hydroxyl radical scavenger in the liquid phase,ozone and radical specis co-oxidated the S_(â…£).