| Nowadays exhaust gas pollution from the combustion of fossil fuels has been one of global environmental problems, thus to find an advanced and economical technology to removal of acid gases from flues gas becomes universally focused on. Considering the higher efficiency and the less energy wasted, pulsed corona discharge plasma is regarded as the new and promising technology to resolve the problem recently. The radicals and active species (OH, O, H, N, O3 HO2, H2O2 etc.) produced by the pulsed corona discharge play important role in the removal of acid gases from flues gas. Especially, OH radical play the central role for its strong oxidation in many physicochemical processes. In this work we pay more attention to the research about characters of various radicals and their trend under the external conditions.In this article, combining with relative experimental conditions, a mathematical model is proposed subsequently to describe the behavior of OH and O radicals in positive pulsed corona discharge of N2 and H2O mixture gas in a wire-plate reactor at one atmosphere, and to compute the generation of radicals by considering a serious of many mixed reactions in the corona discharge into stiff ordinary differential equations. The equations could be solved numerically with the FORTRAN subroutine Treanor.Two aspects will be studied in this article:(1) A mathematical model was proposed to describe the behavior of OH and O radicals by a singe pulse in the positive pulsed corona discharge of N2 and H2O mixture gas with a wire-plate reactor at one atmosphere. The evolution of the radicals produced in the N2 and H2O mixture gas as a function of time has been studied. The generation and the process of various radicals as well as theirs evolution under the influences of various gas components in the reactor such as reduced water vapor or added O2 in the N2 and H2O mixture gas for the relative OH and 0 radicals are described. Both the concentration of OH, O radicals increase when vapor increase, but the concentration of OH radical decreases while the concentration of O increases when the concentration of O2 increases. And it is also found that the concentration of OH radical is larger in the N2 and H2O mixture gas while the concentration of O radical is larger in the atmosphere by comparing the evolution of OH, O radicals in the both above systems. Moreover, the reaction mechanisms and the main physicochemical processes involved have also been discussed consequently.(2) A mathematical model was also proposed to describe the behavior of OH radical by continual pulses in the positive pulsed corona discharge within either N2 and H2O mixture gas or the atmosphere with a wire-plate reactor at one atmospheric pressure. The evolutions of the OH radical in N2-H2O with various operating parameters such as discharge frequency, the added O2 in the N2 and H2O mixture gas have been studied. The simulation results indicate: the concentration of OH radical increases with increasing the frequency, and decreases with increasing the flow rate of added oxygen. The calculated results are compared with the experimental data, and they match well qualitatively with each other.The characters of radicals and the trends with several parameters are studied by numerical simulation, and these results could provide experiments with theoretic references as well as proofs of validity. |
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