High-pressure gas permeation tests

FIGURE 23.11 Schematic of high-pressure gas permeation testing system. 

Table 8 illustrates the effect of solvent on permeabilities and permeability ratios of dense films prepared from HMW HSPPO-18.5 [23]. All films were prepared from polymer solutions of identical concentration (4g in 100 ml of solvent) and at identical drying conditions. To avoid inconsistencies due to the presence of water in films, all gas permeation tests were performed in the CV system following film drying at an ultra-high vacuum of 0.003 mmHg absolute pressure for an extended period of time. 

The question of relative rates of seal leakage and permeation (cf. points 1 and 3) has been considered by MERE. For the sealing of HPHT (5000 psi, ca. 345 bar, or 34.5 MPa 100°C) fluids with chevron seal-stack systems used at the bottom of oil wells in intermittently dynamic conditions, high-pressure permeation and seal-leakage tests using the equipment outlined in Section 23.3.1.2 have been conducted it has been shown that methane gas permeation rate was only ca. 1 % of the rate... 

For gases, both permeation and diffusion data are best measured by permeation tests, many different types been described elsewhere. The same sheet membrane permeation test can quantify permeation coefficient Q, diffusion coefficient D, solubility coefficient s, and concentration c. The membrane, of known area and thickness, must be completely sealed to separate the high-pressure (initial) region from that containing the permeated gas it may need an open-grid support to withstand the pressure. The permeant must be suitably detected and quantified (e.g., by pressure or volume buildup, infrared (IR) spectroscopy, ultraviolet (UV), gas chromatography, etc.). 

Values from high-pressure permeation tests can give useful information regarding the selecting of elastomer types to withstand potential explosive (rapid gas) decompression damage (Sections... 

More recently, Teramoto et al. [24-25] referred to the use of a novel facihtated transport membrane for gas separation in which a carrier was supphed to the feed side (high-pressure side) and it was forced to permeate through a membrane to the permeate side (low-pressure side), and then the permeated carrier solution was recirculated to the feed side. Since the membrane was always wet with the carrier solution, the membrane became very stable with no open or unfilled pores present which usually caused membrane unselectively in traditional SLM. This new type of membrane has been named a bulk flow liquid membrane (BFLM). The membrane resulted to be stable over a discontinuous one-month testing period. 

The static cell used for reverse osmosis and ultrafiliration experiments can be used to test the separation of gas mixtures Air in the feed chamber of the test cell and the feed gas line is removed by flushing them with the feed gas stream. The feed gas is then supplied to the feed gas chamber under pressure. The gas permeation velocity is measured by a bubble flow meter connected to the permeate side of the test cell. The permeate sample is also subjected to analysis by gas chromatography. This simple device is useful when an asymmetric membrane is tested and when the permeation rate is high. 

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