Fundamental Study On Carbon Dioxide Absorption Into Amines

Absorption of CO2 with amines has been extensively studied in last two decades because of the environmental concern of CO2 mitigation and for CO2 enhanced oil recovery (EOR) applications0 Features of mixed amine systems and the mass transfer rate model of CO2 absorption into N-methyldiethanolamine(MDEA) solutions were studied in the paper, which may serve future study as groundwork.Absorption rates of gaseous CO2 into aqueous mixtures of MDEA with monoethanolamine (MEA) or diethanolamine(DEA) were measured, as well as the solution of 10 mass% MEA+20 mass% MDEA at the different temperatures. The absorption rates were found to increase with the increase of MEA or DEA concentration in the mixed amines.It was found that the enhancement factor of the solution: 2.OmollL MDEA O.3molIL MEA+1.7molfL MDEA. 0.5molIL MEA+l.Smol/L MDEA was 2.3.. 13.4.. 20.6 respectively (p=O.15 atm; T=298K; kL0=2.2X l0^m/s). And the mutual coefficient P for the mixed MDEA and MEA was obtained as a function of CO2 loading L^{total concentration: 2.Omol/L, MDEA concentration: 0.3----0.5molIL}:/3(L) 0.12 + 0.35o eL/O026The shooting method and the difference method were described for numerical simulation of film theory (named as "rigorous model") for CO2 absorption with aqueous solution of MDEA. The numerical implementation of the film model confirmed the argument that it was reasonable to neglect the contribution of 0H when L<0.05 mol/mol amine and p<0.Olatm. The prediction of CO-N absorption rate by simplified film model and the rigorous model were compared with the experimental results.It has been demonstrated that the rigorous model provides an excellent approximation to the absorption rate of CO2 into MDEA solutions, which may overestimated by the simplified model at most cases, for the equilibrium constant of reaction between CO2 and MDEA is not extremely high. The results show that percent deviation of the simplified model was over 15% when MDEA concentration was greater than 1.5 molIL, while the maximum percent deviation of the rigorous model below 10% at the rage of 0.5'-2.5 sno!IL(other condition: T303K; L⁰.l; pl atm; kL0=2.8x105m!s). And it was discovered that average percent deviation of the simplified model and the rigorous one was 36.0%, 9.0 1% respectively under the experimental condition of Th303K; L0.005; MDEAtotaj2.0 mollL; kL0=2.8x 105m/s.