Monday, September 1, 2014

Combination of membrane separation and gas condensation for advanced natural gas conditioning

CATEGORY: NATURAL GAS 
Combination of membrane separation
 and gas condensation for advanced natural gas conditioning

Type
Journal Article
Author
Katja Neubauer
Author
Radostina Dragomirova
Author
Marion Stöhr
Author
Raymond Mothes
Author
Udo Lubenau
Author
Dietmar Paschek
Author
Sebastian Wohlrab
URL
Volume
453
Pages
100-107
Publication
Journal of Membrane Science
Date
March 1, 2014
Abstract
 Combining membrane separation and gas condensation reveal an advanced method for the separation of alkanes. First, the applicability of MFI membranes for alkane separation is demonstrated using realistic adsorption isotherms computed by configurational biased Monte Carlo (CBM) simulations. Dew point curves of mixtures comprising different ratios of n-butane (C4) and methane (C1) were then calculated according to the thermodynamic methods of Soave–Redlich–Kwong (SRK) and Peng Robinson (PR).
Isothermal phase boundaries in dependence on the composition of the gas mixture were derived and process parameters under which condensation of the alkane mixture occurs were predetermined. Experimentally, the separation performance of MFI membranes was recorded during separation of n-butane from methane. It was found that liquefied n-butane in the feed and a further liquefaction in the permeate enhance the separation selectivity of MFI zeolite membranes under sweeping conditions tremendously. At the dew point of the feed mixture a sudden rise of the separation factor α was observed. At a temperature of 258 K a mixture with χ C 4 =0.5 can be separated with a separation factor α C 4 / C 1 =174 due to liquefaction. Experiments without sweeping show a similar behaviour. When forming a two phase mixture in the feed an increase in overall condensation efficiency η C 4 is detected in the permeate. At 258 K and pfeed=2 bar and ppermeate=1 bar 29.6% liquefied n-butane was isolated in the permeate from a mixture comprising χ C 4 =0.5.

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