Research On Flue Gas Desulfurization By Ammonia-ammonium Sulfate Method

The FGD of ammonia-ammonium sulfate is a recycling technology of sulfur,accord with China's sustainable development of economic policy,and it can achieve cyclic development of the economy.But at present this technology is at the developing stage,which is a research focus of FGD.Through self-designed ammonia-ammonium sulfate FGD experimental system and the establishment of simulated wet flue gas desulfurization devices,including packed absorption column,simulated flue gas,preparation and circulation of the absorption,compulsory oxidation air,experimental instrument control and experimental testing,the absorption technology of SO₂ were studied.With industrial ammonia as absorbent,the desulfurization experiment based on the ammonia-ammonium sulfate FGD experimental system.Through the reaserch on liquid gas ratio(L/G),initial pH of absorption,composition of absorption,the concentration of absorption,flue gas velocity and the SO₂ concentration,the results demonstrated that the best technical parameters were 2 to 3 L/m³ for the liquid-gas ratio,5.4 to 6 for the initial pH of absorption,1.5 to 2.0 m/s for the flue gas velocity.When the inlet concentration of SO₂ changed,the system could adjust spray amount or the initial pH value of the absorption. Under the best technical parameters the desul furization rate could reach more than 96 percent.Through studying the experiment factors,such as(NH₄)₂SO₃ concentration,compulsory oxidation air flow,(NH₄)₂SO₄ concentration,temperature,solution pH value and so on,which impacted the oxidation of(NH₄)₂SO₃.,the oxidation dynamic equati on of low concentration (NH₄)₂SO₃ was established.And the oxidation activation energy of(NH₄)₂SO₃ was proved to be 31.32 kJ/mol.In this experiment,the products(NH₄)₂SO₄ solution was evaporated and crystal llized, and crystal form,purity and particle size of the product was also analyzed.Through the observation of the phenomenon and characterization of the related equi pments,the results confirmed the impact of metal irons in the solution,and made reasonable proposals to eliminate the impact.At the same time through the study on the particle size distribution of the product,the conclusion that particle size mainly concentrated in 185μm around was found.The experiment established a model of SO₂ absorption in the packed column.Through programming and solving the equation by Visual Basic 6.0,the relevant parameters of the model were obtained.Then the chemical process simulation software ChemCAD was used to simulate the whole process.Through calculating the liquid gas ratio,the flue gas flow rate,pH value,mole fractions of SO₂ in gas phases,and comparing the results of simulation, experiment and programming,this paper could provide a basis for the industrialization of ammonia-ammonium sulfate FGD technology to some extent.