Experimental study on removals of SO2 and NO(x) using adsorption of activated carbon/microwave desorption.

UNLABELLED: Experimental studies on desulfurization and denitrification were carried out using activated carbon irradiated by microwave. The influences of the concentrations of nitric oxide (NO) and sulfur dioxide (SO2), the flue gas coexisting compositions, on adsorption properties of activated carbon and efficiencies of desulfurization and denitrification were investigated. The results show that adsorption capacity and removal efficiency of NO decrease with the increasing of SO2 concentrations in flue gas; adsorption capacity of NO increases slightly first and drops to 12.79 mg/g, and desulfurization efficiency descends with the increasing SO2 concentrations. Adsorption capacity of SO2 declines with the increasing of O2 content in flue gas, but adsorption capacity of NO increases, and removal efficiencies of NO and SO2 could be larger than 99%. Adsorption capacity of NO declines with the increase of moisture in the flue gas, but adsorption capacity of SO2 increases and removal efficiencies of NO and SO2 would be relatively stable. Adsorption capacities of both NO and SO2 decrease with the increasing of CO2 content; efficiencies of desulfurization and denitrification augment at the beginning stage, then start to fall when CO2 content exceeds 12.4%. The mechanisms of this process are also discussed. IMPLICATIONS: The prominent SO2 and NOx treatment techniques in power plants are wet flue gas desulfurization (FGD) and the catalytic decomposition method like selective catalytic reduction (SCR) or nonselective catalytic reduction (NSCR). However, these processes would have some difficulties in commercial application due to their high investment, requirement of expensive catalysts and large-scale equipment, and so on. A simple SO2 and NOx reduction utilizing decomposition by microwave energy method can be used. The pollutants control of flue gas in the power plants by the method of microwave-induced decomposition using adsorption of activated carbon/microwave desorption can meet the requirements of environmental protection, which will be stricter in the future.

Advances on simultaneous desulfurization and denitrification using activated carbon irradiated by microwaves.

This paper describes the research background and chemistry of desulfurization and denitrification technology using microwave irradiation. Microwave-induced catalysis combined with activated carbon adsorption and reduction can reduce nitric oxide to nitrogen and sulfur dioxide to sulfur from flue gas effectively. This paper also highlights the main drawbacks of this technology and discusses future development trends. It is reported that the removal of sulfur dioxide and nitric oxide using microwave irradiation has broad prospects for development in the field of air pollution control.

ORP as slurry oxidation index and model modification in wet desulfurization system.

Due to wet desulfurization system lacks effective control indicators for the oxidation process, so the sulfite oxidation in the slurry and the quality of gypsum become unstable. In this paper actual desulfurization system operation data are used to improve the ORP semi-empirical formula obtained in the laboratory. It was concluded that the ORP was mainly affected by the concentration of sulfite and pH during the operation of the actual desulfurization system, the dissolved oxygen was less affected by the small concentration change during operation. It is verified that the model can correct the ORP measurement value by using other conventional measurement data from the power plant. The results can provide theoretical support for adding ORP as a control index to optimize the oxidation process. IMPLICATIONS: At present, the main control parameter of wet FGD is pH control, but wet FGD has two main reactions at the same time, one is acid-base reaction, the other is redox, single pH control can not reflect the degree of redox, so it is necessary to introduce another control index to evaluate redox, which is the ORP control proposed in this paper, ORP can reflect the degree of slurry oxidation, avoid the occurrence of excessive oxidation and inadequate oxidation, so that the operation of desulfurization system can be more healthy and stable.

[Experiment study on the aqueous removal of SO2 by Mn2+ catalytic ozonation].

The removal of SO2 by Mn2+ catalytic aqueous ozonation was investigated by experiment, so as to find the effects of Mn2+ for aqueous removal of SO2 by ozonation. The concentration curve of ozone was drawn by standard iodine method. The operating factors included mole ratio of ozone to sulfur dioxide and concentration of Mn2+. When absorption solution has no Mn2+, the removal efficiency of SO2 was 35% at [O3 ]/[SO2 ] = 0.5,but the efficiency was 70% when Mn2+ was put into absorption solution at the same value of [O3 ]/[SO2].With the increasing of [3O]/[SO2], the removal efficiency of SO2 increases. And as concentration of Mn2+ increases, the efficiency also increases. There is an appropriate concentration range which is 1.2 x 10(-2)-1.2 x 10(-1) mol/L for Mn2+.

[Experimental research for simultaneous removal of SO2 and NOx by aqueous oxidation of O3].

The removal of SO2 and NOx by aqueous oxidation of O3 was studied by self-designed bubbling reactor. The results show that NO can be oxidized efficiently by O3 in liquid phase, while the existence of SO2 has a negative impact on the removal of NO and pH value has a little impact. The NO removal efficiency is 89.6% at [O3]/[NO] = 1.1. When the rang of pH value is in 3-11, NO removal efficiency can be achieved over 80%. At 20-65 degrees C, NO removal efficiency has no change. Combining with wet scrubbing tower, SO2 removal efficiency is nearly 100% and NO2 removal efficiency is 84.2% at [O3]/[NO] = 1.1. SO2 and NOx can be removed effectively by aqueous oxidation of O3 simultaneously.