Simulation Analysis Of SO₂ Dissolution Process In Bunsen Reaction And Experimental Study Based On Microchannel Reactor

The emissions of the sulfur-containing pollutants in the utilization of traditional fossil fuels such as coal,oil and natural gas cause serious harm to human living environment.Great advances have been made on the desulfurization and the purification of sulfur-containing gas,but the effective control and reutilization of H₂S still faces challenges.H₂S splitting cycle for hydrogen production?H₂S+H₂SO₄?2H₂O+SO₂+S;S+O₂?SO₂;SO₂+I₂+2H₂O?2HI+H₂SO₄;2HI?H₂+I₂?provides a technical route to produce high-quality and high-value prodcuts,hydrogen and sulfuric acid,from hydrogen sulfide and sulfur dioxide.It also provides a potential method to reutilize the sulfur-containing pollutants in the utilization of coal.The realization of H₂S splitting cycle for hydrogen production focuses on thethree-phase Bunsen reaction by using sulfur dioxide?gas phase?,water?aqueous phase?and iodine-toluene solution?organic phase?as reactants.The previous studies showed the SO₂ absorption process is the rate-controlling step of the Bunsen reaction.This paper focuses on the interaction between SO₂ and water or toluene.Firstly,SO₂ absorption has been simulated by using Aspen Plus which is a large chemical process simulation software.Secondly,characteristics of SO₂ absorption have been experimental studied by using Corning G1 microchannel reactor which can solve the difficulties of the mass transfer of multiphases and the severe corrosion of products..The main discoveries and conclusions are described as follows:1)The dissolution process of SO₂ in water or toluene,the rate control step of the Bunsen reaction was simulated by using Aspen plus software.The RK-SOAVE equation of state model and the ELECNRTL activity coefficient model were used to simulate the SO₂-H₂O and SO₂-toluene binary systems in the FLASH2 flash module.The solubility of the binary system was predicted by sensitivity analysis.The SO₂solubility varing by temperature and pressure was optimized.For the SO₂-toluene binary system,the solubility of SO₂ increased as increase in the pressure.The higher the pressure,the more pronounced the decrease in temperature rise solubility.When the operating pressure reaches 8atm,the solubility exceeds 100g/100g toluene in the temperature range from 20to 70^oC.For SO₂-H₂O binary system,the solubility of SO₂ in water gradually decreases with the increase in the temperature,and exponentially increases with the increase in the pressure.When the pressure continuously increased to 8 atm,the SO₂ solubility reached 97.4 g/100 g H₂O.2)On the basis of determining the choice of physical methods,the Henry binary interaction parameters in the Aspen plus software database were not fully applicable to high temperatures and high pressures during the thermodynamic test of SO₂-H₂O binary system.The physical regression system was used to recombine the existing experimental data with the Aspen plus database.The Henry's constants of the SO₂-H₂O system were modified and fitted in the temperature range of 20-50^oC and 50-70^oC,respectively.Regression analysis was performed according to the calculated values fitted by the experimental data.The results showed that the RMSR=5.9207 obtained by the first regression and the RMSR=8.67883 of the second regression?<10 for the gas-liquid system?were used for the subsequent experimental conditions.The results provide theoretical basis and data support to complement the Aspen system's binary interaction parameter database.3)The dissolution behavior of SO₂ in Bunsen reaction,under different operating conditions,including temperatures,pressures and reactants feed rates was investigated and optimized by using Corning G1 microchannel reactor.To obtain the high reaction yield and minimize the use of toluene,the two-phase dissolution behavior of gas flow rate and gas phase composition concentration were optimized by calculating the total mass transfer coefficient and absorption rate.The results showed that the increase in the reaction temperature increased the total mass transfer coefficient and the absorption rate of SO₂.Increasing the reaction pressure increased the total mass transfer coefficient.The total mass transfer coefficient was constant in the SO₂-H₂O system but increased in the SO₂-toluene system.I increasing the SO₂ feed concentration and the flow rate of liquid phase decreased the total mass transfer coefficients and increased the absorption rate of SO₂.For the SO₂-H₂O-toluene ternary system at a constant liquid phase flow rate,the absorption rate increased as an increase in the volume fraction of toluene.