Integrated Experimental Study On Flue Gas Desulfurization And Denitrification Of NaClO/NaClO 2 Composite Solution

Today,the ultro-low emission of sulfur dioxide and nitrogen oxide in flue gas produced by coal firing is one of the main targets of atmospheric pollution control.Most technologies about the desulfurization and denitration separately have been mature or widely application,both in domestic and abroad.However,the one to one way of desulfurization or denitration could not fit for the development of emission requirements.There are many problems to be solved,such as the high initial investment and running cost;the more occupied area of too parallel equipment and so forth.As the requirements to the air quality increase gradually with the corresponding emissions standards,the new technology and equipment used to desulfurization and denitration at the same time or in a device has become a research direction of the current air pollution control.The study of desulfurization and denitration equipments industrial is imminent.In this paper,a new type of NaClO/NaClO₂ solution method is adopted.It is an oxidation and absorbing liquid,the cheap NaClO solution is the main composition in the solution,and the expensive NaClO₂ is added as the additive to strengthen the oxidation.A plexiglass spraying tower was built which is scaling down design and to be the integrative and used for the flue gas desulfurization and denitration by oxidization and absorbing solution spraying.According to the gaseous compositions in a practice coal firing boiler flue gas,and to the visual spraying conditions,the gas-solution ratio is to be controlled and to obtain the optimum one.By studying the influence of relevant process parameters on the desulfurization and denitration's efficiency,the optimal conditions of NaClO/NaClO₂ solution spraying and running was determined.The gaseous pollutants are set as the conventional boiler flue gas,for example,the SO₂ concentration is 500 mg/m3,and the NO concentration is about 300mg/m3.When the initial concentration of NaClO in spraying solution is 4mmol/L,the initial concentration of NaClO₂ is 2mmol/L,the initial solution pH value is 6,the liquid gas ratio of 25L/m3,and the temperature of solution is 55?,the highest desulfurization and denitration removal efficiency both could reach to 100%.In this paper,reunion agent was added into the composite solution to cooperate the ultra-fine particle removal by agglomeration method.And then,the efficiency of desulfurization and denitration used one concentration of reunion agent in the compound solution is tested to see the influence of solution viscosity on the de_SOx and De-NO_x efficiency.The increased viscosity of the solution affected the atomization quality,but the concentration of reunion agent is very small,and it couldbe used in the integrative desulfurization and denitration solution,so the ultrafine particle removal also could be integrated in the spraying method and in the same tower.The XTG0.1% agglomeration concentration is fit for the application in this paper.In order to study the chemical reaction rate between the compound liquid and the NO_x/SO₂ in flue gas,each reactants and products in the reaction solution was analyzed by chemical titration of the sampling periodically during the reaction process.It is shown that chlorine dioxide and chlorine gas are the intermediate products to be the oxidizing agents to react with NO and not the hypochlorite/chlorite directly as oxidation agents.Then the mechanism of gas liquid two phase reaction between NaClO/NaClO₂ composite solution with NO/SO₂ is deduced at the same time,and the total chemical desulfurization denitration reaction equations are concluded.The industrial boiler emissions of lower SO₂ concentration firing low-sulfur coal,or the low temperature flue gas all are difficult to realize its ultra-low emissions.For example,the NO concentration is below 200 mg/m3 and the temperature is only100?.A series of the compound solution tests,including the NaClO/Na ClO2 solution,oxidizing-reducing combined solution,are carried out in this paper.Under the condition of the added catalyst copper oxide,low temperature and concentration of denitration efficiency reached 56%,make it meet the industrial boiler in ultra-low NO_x emissions.The novel complex NaClO/NaClO₂ solution in this study is suitable used in coal-fired flue gas for desulfurization and denitration,even tiny particles integration removal technology.The efficiency of simultaneous desulfurization and denitration is high for the common coal-firing flue gas.And its system is simple,initial investment and operation cost is not high,so it's good prospect for application and promotion.