High-Pressure Aging of Asymmetric Torlon® Hollow Fibers for Helium Separation from Natural Gas

Abstract

Membrane separation for helium extraction from natural gas gained increased interest recently. Several vendors offer membrane elements for helium extraction, although data on their performance and operating experience are unpublished. The aim of this work was to obtain and study the separation performance of asymmetric hollow-fiber membrane element from commercial polyamide-imide Torlon®, in conditions close to the industrial process of helium extraction from natural gas. A membrane element with an active area of 0.177 m2, a helium permeance of 100 l(STP)/(m2·h·bar), and a selectivity α(He/CH4) = 340 was produced. This corresponds to a selective layer thickness of 82.3 nm, which was confirmed by SEM and resistance model calculations. The obtained membrane element was employed to decrease the concentration of helium in its binary mixture with methane from 0.4% to 0.05%. A relationship of separation characteristics from transmembrane pressure is also presented. At 70 bar and a stage cut of 2.7%, the feed flow rate was 0.16 m3(STP)/h, which yielded a helium permeate concentration of 14.7%. At 80 bar, a decrease in permeance to 60 l(STP)/(m2·h·bar) and in selectivity to 240 was observed. It was shown that the main reason for aging was the increased support resistance, due to a partial compaction of pores with a radius of less than 15 nm.

Elaboration of High Permeable Macrovoid Free Polysulfone Hollow Fiber Membranes for Air Separation

“…The schematic of the setup is described in detail in [2,[22][23][24]. The dope was placed in a sealed tank, equipped with a water jacket, and either cooled down to 25 • C or warmed up till 62 • C. Spinneret with the dope orifice outer diameter (OD) of 0.5 mm and the inner diameter (ID) of 0.23 mm was used ( Figure 1).…”

“…Permeance (P/l) defines the required membrane area, that is, the size and the number of membrane elements and hence, a substantial portion of the capital cost [2]. This parameter is calculated using a formula:…”

“…where P-permeability, l-selective layer thickness, V/τ-volumetric flow rate, S-membrane area, ∆p-transmembrane pressure. Units for permeance are: L (STP)/(m 2 •h•bar) = 0.3703 GPU = 1.239•10 −10 mol/(m 2 •s•Pa). Dimensionless membrane selectivity is calculated as a ratio of permeances of fast permeating species (A) relative to slow permeating species (B):…”

Simulation of Convection–Diffusion Transport in a Laminar Flow Past a Row of Parallel Absorbing Fibers

“…Studies of convection-diffusion transfer in fibrous media are essential for the development of various technological processes. The results obtained are employed in solutions to the problems concerning the filtration of suspended particles [1,2], sorption, catalysis, electrochemistry, and especially, in membrane separation technology [3,4], where membranes in the form of hollow fibers are used for membrane gas absorption/desorption [5,6], ultra- [7] and nanofiltration [8], and gas separation [9,10]. Within the field of membrane technology, a great number of studies is devoted to the modelling of different mass-transfer processes in hollow-fiber membrane contactors [11][12][13][14][15][16].…”

The Effect of the Type and Concentration of the Crosslinking Diene on the Gas Transport Properties of Membranes Based on Polyoctylmethylsiloxane

“…Despite the variety of silicone rubbers, only two representatives are used for the preparation of industrial membranes, namely, polydimethylsiloxane (PDMS) and polyoctylmethylsiloxane (POMS) [13,25]. PDMS possesses the highest permeability among silicone rubbers and good coating properties and is applied not only for the application of the selective layer of composite membranes [2,13] but also for the removal of the defects of asymmetric gas separation membranes [26]. POMS is inferior to PDMS with respect to permeability but possesses an increased selectivity that manifests itself in both gas separation [13,17] and pervaporation [27,28].…”