Study On The SO₂ Gas-liquid Absorption Process In The Microscale Channel

With the rapid development of industry,environmental pollution is also increasingly serious,and the treatment of tail gas SO₂ is essential,and micro-chemical technology for the development of SO₂ gas absorption is of great significance.In this paper,the gas-liquid twophase flow characteristics are studied by high-speed camera in the circular microchannel reactor and gas-liquid flow pattern is studied by gas-phase CO₂ and liquid-phase water.Then,under the condition of the absorption concentration,the apparent flow velocity,the apparent flow velocity,the reaction temperature and the microchannel size,the mass transfer characteristics of SO₂ gas and NaOH absorbent are revealed.Finally,the absorption of SO₂ gas is studied by using NaOH absorber and Na2SO3 absorber in the micro-scale channel.The following conclusions are drawn:（1）There are various flow patterns with different apparent gas flow rates and apparent liquid flow rates between the CO₂ and water phases.There are bubble flow,shell flow,shelllike flow,annular flow and stirred flow.And according to the two-phase apparent speed the flow chart is drawed.The flow pattern is shown in the figure.In addition,the mass transfer between CO₂ and water is enhanced in the microchannel,and the pressure drop increases with the apparent velocity of the two phases.（2）With the increase of NaOH concentration,the absorption and mass transfer of SO₂ gas is increasing.With the increase of apparent gas velocity and apparent liquid velocity,the total mass transfer coefficient of liquid phase gradually increases.With the increase of the reaction temperature,the mass transfer coefficient of the liquid is weakened,and the total mass transfer coefficient of the liquid phase decreases,and the effect is the most significant at high temperature.The microchannel inner diameter becomes larger and the liquid flow rate is constant.The mass transfer coefficient increases first and then decreases with the gas flow rate.When the gas flow rate dominates,the microchannel size effect is weakened.（3）With the increase of the concentration of NaOH solution and Na2SO3 solution,the absorption rate of SO₂ is increasing gradually,and the absorption of NaOH solution is better than that of Na2SO3 solution.The absorption rate of SO₂ gas decreases with the increase of the apparent flow rate of the two gases,and increases with the apparent flow of the liquid and the trend is slowed down.The gas absorption rate is 92%,but the gas flow continues to increase,absorption effect gradually is decreasing.With the increase of the operating temperature,the absorption rate of SO₂ gas is decreasing with the increase of the operating temperature.When the microchannel diameter increased to 900μm,the absorption effect gradually is increasing with the increase of the apparent liquid flow rate.When the liquid flow is very large,the two absorbers in the different micro-channel diameter of the SO₂ gas absorption rate is 99%,almost completely.