posted on 2017-01-11, 00:00authored byGangqiang Yu, Chengna Dai, Liang Wu, Zhigang Lei
The
technology of natural gas dehydration with ionic liquids (ILs)
as a promising method was proposed and systematically investigated
in this work. The IL [EMIM][Tf2N] was screened out as an
appropriate absorbent from 252 IL candidates for the natural gas dehydration
process by means of the COSMO-RS model. The σ-profiles and σ-potentials
of the CH4-H2O-IL system were analyzed at the
molecular level to explain the possibility of CH4 dehydration
using [EMIM][Tf2N] as absorbent. The experiment data of
CH4 solubility in pure IL and in the mixture of IL + H2O were measured and compared with the predicted results by
the UNIFAC–Lei model. Moreover, the CH4 dehydration
experiment was carried out, and the gas product with a low water content
(down to 350 ppm in mole fraction) can be obtained. Finally, the conceptual
dehydration process was simulated and optimized using the rigorous
equilibrium (EQ) stage model, into which the UNIFAC–Lei model
parameters were input. It was found that the CH4 dehydration
process with [EMIM][Tf2N] demonstrates the better separation
performance, i.e., no solvent loss, plant miniaturization, and saving
energy consumption, when compared to the benchmark triethylene glycol
(TEG) process. Thus, ILs can be taken on as a type of promising alternative
absorbents to conventional solvents in the field of gas dehydration.