The present paper renders a modeling and a 2D numerical simulation for the removal of CO_2from CO_2/CH_4gaseous stream utilizing sodium hydroxide(NaOH),monoethanolamine(MEA)and triethanolamine(TEA)liquid absorbents in...The present paper renders a modeling and a 2D numerical simulation for the removal of CO_2from CO_2/CH_4gaseous stream utilizing sodium hydroxide(NaOH),monoethanolamine(MEA)and triethanolamine(TEA)liquid absorbents inside the hollow fiber membrane contactor.Counter-current arrangement of absorbing agents and CO_2/CH_4gaseous mixture flows are implemented in the modeling and numerical simulation.Non-wetting and partial wetting modes of operation are considered where in the partial wetting mode,CO_2/CH_4gaseous mixture and liquid absorbents fill the membrane pores.The deteriorated removal of CO_2in the partial wetting mode of operation is mainly due to the mass transfer resistance imposed by the liquid in the pores of membrane.The validation of numerical simulation is done based on the comparison of simulation results of CO_2removal using Na OH and experimental data under non-wetting mode of operation.The comparison illustrates a desirable agreement with an average deviation of less than 5%.According to the results,MEA provides higher efficiency for CO_2removal in comparison with the other liquid absorbents.The order for CO_2removal performance is MEAN Na OHN TEA.The influence of non-wetting and partial wetting modes of operation on CO_2removal are evaluated in this article as one of the novelties.Besides,the percentage of CO_2sequestration as a function of gas velocity for various percentages of membrane pores wetting ranging from 0(non-wetting mode of operation)to 100%(complete wetting mode of operation)is studied in this research paper,which can be proposed as the other novelty.The results indicate that increase in some operational parameters such as module length,membrane porosity and absorbents concentration encourage the removal percentage of CO_2from CO_2/CH_4gaseous mixture while increasing in membrane tortuosity,gas velocity and initial CO_2concentration has unfavorable influence on the separation efficiency of CO_2.展开更多
Application of methanol solvent for physical absorption of CO2 and H2S from CO2/H2S/CH4 mixture in gas–liquid hollow fiber membrane gas absorber (HFMGA) was investigated. A computational mass transfer (CMT) model for...Application of methanol solvent for physical absorption of CO2 and H2S from CO2/H2S/CH4 mixture in gas–liquid hollow fiber membrane gas absorber (HFMGA) was investigated. A computational mass transfer (CMT) model for simulation of HFMGA in the case of simultaneous separation of CO2 and H2S was developed. The membrane gas absorber model explicitly calculates for the rates of mass transfer through the membrane and components concentration profiles. Due to the lack of experimental data in the literature, the model was validated using available individual components’ water absorption data. The numerical predictions were in good agreement with the experimental data. The effects of operating conditions such as liquid velocity, gas velocity, temperature and pressure were analyzed. It is shown that methanol solvent can successfully be used for CO2 and H2S removal in membrane gas absorber. Also it is found that the concentration distribution of CO2 and H2S in the gas phase along the fiber length obeys plug flow model whereas in the methanol absorbent deeply affected by the interface concentration, absorbent velocity and diffusivity. In addition, it is shown that application of membrane gas absorber using methanol absorbents for H2S removal and at higher flow rate is more efficient. Moreover, at operating pressures above 10 atm even at low absorbent rate, H2S concentration depletion is relatively complete while at 1 atm this value is about 30%. This means that removal efficiency decreases with an increase in temperature and it is more important especially for H2S.展开更多
Herein, excellent UV-absorbing poly(vinylidene fluoride)(PVDF) membranes were fabricated through the pre-irradiation induced graft polymerization method. The PVDF chains irradiated with ^(60)Co γ-ray were modified wi...Herein, excellent UV-absorbing poly(vinylidene fluoride)(PVDF) membranes were fabricated through the pre-irradiation induced graft polymerization method. The PVDF chains irradiated with ^(60)Co γ-ray were modified with the polymerizable UV absorber 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2 H-benzotriazole(RUVA-93). The influences of irradiation dose and monomer concentration on the prepared PVDF-g-PRUVA-93 membranes were investigated, and the optimal condition was eventually obtained. The chemical structures of the films were studied by ~1H-NMR, FTIR, and XRD. UV light transmittance and DSC tests were used to characterize the UV-absorbing performance and thermal property of the PVDF films before and after modification. The results proved that the PRUVA-93 side chains were successfully incorporated into the PVDF main chains and the obtained PVDF-g-PRUVA-93 films possessed remarkable UV-absorbing property. The modified membrane made under the optimized experiment condition could completely block the UV light in the range of 200-387 nm. Additionally, the transmittance of the PVDF-g-PRUVA-93 film could be reduced to0.04% in 280-320 nm, where the light irradiation could damage polymer materials most seriously.展开更多
文摘The present paper renders a modeling and a 2D numerical simulation for the removal of CO_2from CO_2/CH_4gaseous stream utilizing sodium hydroxide(NaOH),monoethanolamine(MEA)and triethanolamine(TEA)liquid absorbents inside the hollow fiber membrane contactor.Counter-current arrangement of absorbing agents and CO_2/CH_4gaseous mixture flows are implemented in the modeling and numerical simulation.Non-wetting and partial wetting modes of operation are considered where in the partial wetting mode,CO_2/CH_4gaseous mixture and liquid absorbents fill the membrane pores.The deteriorated removal of CO_2in the partial wetting mode of operation is mainly due to the mass transfer resistance imposed by the liquid in the pores of membrane.The validation of numerical simulation is done based on the comparison of simulation results of CO_2removal using Na OH and experimental data under non-wetting mode of operation.The comparison illustrates a desirable agreement with an average deviation of less than 5%.According to the results,MEA provides higher efficiency for CO_2removal in comparison with the other liquid absorbents.The order for CO_2removal performance is MEAN Na OHN TEA.The influence of non-wetting and partial wetting modes of operation on CO_2removal are evaluated in this article as one of the novelties.Besides,the percentage of CO_2sequestration as a function of gas velocity for various percentages of membrane pores wetting ranging from 0(non-wetting mode of operation)to 100%(complete wetting mode of operation)is studied in this research paper,which can be proposed as the other novelty.The results indicate that increase in some operational parameters such as module length,membrane porosity and absorbents concentration encourage the removal percentage of CO_2from CO_2/CH_4gaseous mixture while increasing in membrane tortuosity,gas velocity and initial CO_2concentration has unfavorable influence on the separation efficiency of CO_2.
文摘Application of methanol solvent for physical absorption of CO2 and H2S from CO2/H2S/CH4 mixture in gas–liquid hollow fiber membrane gas absorber (HFMGA) was investigated. A computational mass transfer (CMT) model for simulation of HFMGA in the case of simultaneous separation of CO2 and H2S was developed. The membrane gas absorber model explicitly calculates for the rates of mass transfer through the membrane and components concentration profiles. Due to the lack of experimental data in the literature, the model was validated using available individual components’ water absorption data. The numerical predictions were in good agreement with the experimental data. The effects of operating conditions such as liquid velocity, gas velocity, temperature and pressure were analyzed. It is shown that methanol solvent can successfully be used for CO2 and H2S removal in membrane gas absorber. Also it is found that the concentration distribution of CO2 and H2S in the gas phase along the fiber length obeys plug flow model whereas in the methanol absorbent deeply affected by the interface concentration, absorbent velocity and diffusivity. In addition, it is shown that application of membrane gas absorber using methanol absorbents for H2S removal and at higher flow rate is more efficient. Moreover, at operating pressures above 10 atm even at low absorbent rate, H2S concentration depletion is relatively complete while at 1 atm this value is about 30%. This means that removal efficiency decreases with an increase in temperature and it is more important especially for H2S.
文摘Herein, excellent UV-absorbing poly(vinylidene fluoride)(PVDF) membranes were fabricated through the pre-irradiation induced graft polymerization method. The PVDF chains irradiated with ^(60)Co γ-ray were modified with the polymerizable UV absorber 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2 H-benzotriazole(RUVA-93). The influences of irradiation dose and monomer concentration on the prepared PVDF-g-PRUVA-93 membranes were investigated, and the optimal condition was eventually obtained. The chemical structures of the films were studied by ~1H-NMR, FTIR, and XRD. UV light transmittance and DSC tests were used to characterize the UV-absorbing performance and thermal property of the PVDF films before and after modification. The results proved that the PRUVA-93 side chains were successfully incorporated into the PVDF main chains and the obtained PVDF-g-PRUVA-93 films possessed remarkable UV-absorbing property. The modified membrane made under the optimized experiment condition could completely block the UV light in the range of 200-387 nm. Additionally, the transmittance of the PVDF-g-PRUVA-93 film could be reduced to0.04% in 280-320 nm, where the light irradiation could damage polymer materials most seriously.
