Experimental Study On Simultaneous Desulphurization And Denitrification By Ammoniacal Cobalt(Ⅱ) Solutions

The treatment of sulfur dioxide and nitric oxide in the combustion of coal fired boiler is a severe problem around the world.Cobalt ammonia complex method is an effective simultaneous desulfurization and denitrification technology.Basing on the theoretical analysis of cobalt ammonia solution component,systematic experiments for simultaneous desulfurization and denitrification by cobalt ammonia solution were conducted,and following main achievements were obtained.The experiments of denitration by cobalt ammonia solution were carried out in self-designed bubble column reaction device.From above experiments we could conclude that effective constituents for denitration were only [(7)(8)]2(10)35NHCo and [(7)(8)]2(10)36NHCo.Denitration production analysis was conducted with ion chromatography and spectrophotometry.Mechanisms of NO oxidation and oxidized NO reacting with ammonia were verified.Overall reaction equation of NO was obtained and reaction mechanism of cobalt ammonia solution denitration was improved.Sole and simultaneous desulfurization and denitrification experiments were carried out and optimal conditions for sole denitration efficiency,optimal conditions for sole desulphurization efficiency,optimal conditions for simultaneous desulfurization and denitrification efficiency were obtained.Practical conditions for simultaneous desulfurization and denitrification efficiency with consideration of ammonia escape was also obtained,which provides the basis of industrial production of simultaneous desulfurization and denitrification by cobalt ammonia solution.The equilibrium constants of [Co(NH3)5]2+ and [Co(NH3)6]2+ absorbing NO were obtained in self-designed bubble column reactors.The magnitude of the equilibrium constant 5NOK was 1012,and the magnitude of 6NOK was 1013,which indicates that above reactions were completely.The fitting formula of equilibrium constant and temperature was obtained,which can be used to compute equilibrium constant when the temperature is in the range of 295.2 to 303.2 K.The reaction rate constants of [Co(NH3)5]2+ and [Co(NH3)6]2+ absorbing NO can be obtained in wetted-wall reactor,and through experimental and regression analysis we could conclude that these two absorbing reactions were first order processes for NO.A multiple linear regression method to solve non-linear equation system was proposed,and the reaction rate constant of [Co(NH3)5]2+ and [Co(NH3)6]2+ absorbing NO were obtained at 295.2 K、298.2 K and 301.2 K.A regeneration method of cobalt ammonia waste by activated carbon and graphene treated with modified HCl and H2O2 was propeosed.Physical and chemical performance of modified activated carbon and graphene were studied by characterization.Influence of modification temperature,concentration and time on regeneration were studied.Effect of modification temperature,concentration and time on denitration efficiency was also studied to get optimal modification conditions.The experiments of simultaneous desulfurization and denitrification were carried out in 10 Nm3/h spray tower reactor,simulating the fact stack gases circs(CO2).Take denitrification/desulphurization efficiency and ammonia escape as evaluation standards to provide evidence for treatment of simulated actual flue gas by cobalt ammonia solution.The working of this paper can provide basis for the further understanding of denitrification mechanism by cobalt ammonia solution,and also provide theoretical evidence for simultaneous desulfurization and denitrification by cobalt ammonia solution.