Stude On Cross-flow Membrane Aeration-membrane Absorption Integrated Seawater Flue Gas Desulfurization Process

With the global industrialization process,fossil fuels have become the most important part of the current global energy structure.The sulfur dioxide gas produced in its combustion and accompanying acid rain pose great harm to the ecological environment and human health.Therefore,the desulfurization of industrial source flue gas is essential and important.Membrane absorption seawater flue gas desulfurization ttechnology,intergrating both characteristics of seawater flue gas desulfurization and membrane absorption,separate control of gas-liquid two phases,large gas-liquid contact area,compact equipment structure and easy industrial integration.And so on.Membrane flue gas desulfurization uses a membrane absorber as an absorption unit.Therefore,the development of a membrane contactor with high mass transfer and high absorption is of great significance for improving the desulfurization efficiency of seawater.In this paper,a polypropylene hollow fiber aeration double-layer membrane contactor was developed.The contact aerator was used to study the membrane aeration-membrane absorption coupled seawater flue gas desulfurization process.The effects of gas-liquid flow rate,flue gas concentration,aeration amount,seawater p H and seawater concentration on flue gas desulfurization performance were investigated.Simultaneously,the strengthening effect of membrane aeration on SO₂ absorption process was explored,and the performance of hollow fiber membrane after use was characterized.The results show that the aerated membrane absorption process has higher desulfurization efficiency and mass transfer performance;the increase of flue gas flow and flue gas concentration has a negative impact on the SO₂ absorption process;The increase of aeration,seawater flow,seawater p H and seawater concentration promote SO₂ absorption;The SEM and contact angle characterization of the membrane showed that although the film surface had impurities attached,the membrane contact angle decreased slightly,but the polypropylene hollow fiber membrane still had good hydrophobic properties and performance after one month of use.Through the investigation of different factors under the four aeration types of non-aeration and aeration sources,such as nitrogen,air and oxygen;the effects of disturbance and oxidation under aeration on the absorption process of SO₂ were preliminarily investigated.The results show that SO₂ absorption rate,absorption flux,total mass transfer coefficient,seawater p H and carbonate concentration in seawater all decrease with time;The concentration of SO₃^2-and SO₄^2-increases with time.The change of seawater p H is related to the concentration of carbonate in seawater.The change of seawater p H is divided into four stages（decline period,buffer period,sudden drop period and stable period）.The effect of aeration type on SO₂ absorption rate,total mass transfer coefficient and dissolved oxygen content in seawater is that oxygen>air>nitrogen>no aeration.Under long-term operation,the degree of change of SO₂ absorption rate and total mass transfer coefficient under four types is obtained:not only the aeration effect of aeration improves the absorption performance of SO₂,but also the oxidation effect plays a significant role,and the aeration effect is greater than the oxidation effect.