| Global warming, which is accompanied by the unpredictable climate changes, has been generally considered to be correlated with the global CO2 emissions arising from the combustion of fossil fuels. Therefore, the development of cost-effective technologies to control CO2 emissions is always a hot topic in the world. In China, coal-fired power plants are the main CO2 emission sources and have attracted particular attention from both the Chinese government and the relevant scientists. Many CO2 capture technologies have been developed, among which, the membrane separation is one of the most effective ones. Comparing to the conventional solvent absorption methods, the membrane separation technology has the advantages of low investment costs, compact configuration and no secondary pollution.In this paper, PDMS-PEI flat sheet membrane and PI hollow fiber membrane are studied as subjects. First of all, effects of operation conditions on CO2 separation performances of the PDMS-PEI plate membrane and PI hollow fiber membrane are studied in the simulation test bench. Secondly, a series of long time tests are being done, to research the effect of SO2, water vapor, SO2 and water vapor, on CO2 separation performances of PI hollow fiber membranes under the best operation conditions based on the first step. And then, the long term influences of particle types and membrane types on CO2 separation performances of membranes are researched by choosing fly ash, ammonium sulfate and calcium sulfate as typical experience particles. Finally, the co-exist influence of fine particulate and gaseous component on CO2 separation performances of membrane are studied under the flue gas in the pilot experimental hot bench. In addition, many analysis instruments, such as FESEM, FTIR, EDS and AFM, are used to analysis physical and chemical properties of membrane samples, before and after test, providing data for CO2 separation performances analysis.It is found that increasing gas flow rate is beneficial to CO2 separation performances both of the PDMS-PEI composite plate membrane and PI hollow fiber membrane. And increasing operating pressure is good for PI hollow fiber membrane. For PDMS-PEI composite plate membrane, increasing operating pressure can not only improving CO2/N2 separation factor, but also reducing CO2 permeation rate. Operating temperature is good for PI hollow fiber membrane, but bad for PDMS-PEI flat sheet membrane. The best operation conditions are 400L/h,0.3MPa and 25℃. For the concentration of SO2 was significantly lower than that of CO2, SO2 will not results obvious impacts on CO2 separation performances of membrane in a long time. Due to competitive adsorption, capillary condensation, cluster migration and plasricizing swelling and these comprehensive effect of water vapor, water vapor is a disadvantage for CO2 separation performances of PI hollow fiber membrane. And the impact of water vapor on PI hollow fiber membrane is reversible. Under SO2 and water vapor co-exist condition, SO2 deteriorates CO2 separation performance of PI hollow fiber membrane, but the impact of water vapor and SO2 co-exist on PI hollow fiber membrane is reversible. For covering surface of membrane, absorbing gases, increasing the mass transfer resistance and these comprehensive effect of fine particles, such as fly ash, ammonium sulfate and calcium sulfate, these three kinds of fine particles all decrease CO2 separation performances of membrane. For each of them, the effect is basically the same, when present alone. In the condition of water vapor, the influence of water vapor and the coexist influence of water vapor and fine particle make CO2 separation performances of membrane worse than that of the condition without water vapor. And, the decrease impact of ammonium sulfate and calcium sulfate under water vapor condition is worse than that of fly ash. Under the flue gas after WFGD, CO2 separation performance of PI hollow fiber membrane is tested lasting 10 days. From the experimental results, it is clear that the co-exist impact of SO2, water vapor and fine particle, make CO2/N2 separation factor decreasing 64.08%, CO2 permeation rate decreasing 32.51% compared with the initial state, and CO2/N2 separation factor decreasing 89.22%, CO2 permeation rate decreasing 43.59%compared with simple atmosphere. Among them, water vapor and fine particles play a major role for the inhibition phenomenon. |
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