Toshikatsu Hakuta

Calculation Methods for Multicomponent Gas Separation by Permeation

Abstract Calculation methods for the single-stage permeation of a multicomponent gas mixture are presented for five flow patterns: cocurrent flow, countercurrent flow, cross flow, perfect mixing, and one-side mixing. The derivations are cast in a form suitable for computer calculation. The calculation methods presented are appropriate for systems with any number of components. Calculation results are shown for the separations of a NH3, H2, and N2 gaseous mixture by means of a polyethylene membrane, and for a H2, CH4, CO, N2, and CO2 mixture through a microporous glass membrane.

A Study of Concentration Polarization Phenomenon on the Surface of a Gas Separation Membrane

Abstract Mass transfer coefficients on the surface of porous glass membrane were obtained from separation tests of H2-CO mixtures. These data agree with the correlation presented by Ghosh and Upadhyay for mass transfer on an impermeable wall. In addition, effects of the selectivity of membrane and bulk composition on the concentration polarization phenomenon are discussed and the limiting permeability which is affected by the polarization is represented as a function of mass transfer coefficient.

Performance of Gas Separator with High-Flux Polyimide Hollow Fiber Membrane

Abstract The permeation properties of H2-CO mixtures through a high-flux asymmetric polyimide membrane are studied experimentally and theoretically. Experimental results measured with miniature module-equipped hollow fibers indicate the advantage of countercurrent flow pattern. The calculation model used for the analysis of the conventional symmetric membrane can predict the gas separation performance. However, the model is necessary to take the longitudinal mixing into account for analyzing the experimental results measured with a pilot scale module.

Vapor-liquid equilibria of strong electrolyte aqueous solutions

Abstract A new method is proposed for calculation of vapor-liquid equilibrium (VLE) and vapor pressure of concentrated aqueous solution containing one or more strong electrolytes. Activities of electrolyte and water in the high concentration region are calculated by an expression extending the Meissner equation. The applicability of this method is examined for 20 binary and ternary electrolytic systems. As a result, it is confirmed that the method can represent the experimental data with good accuracy up to about 433.2 K and 30 mol kg−1 of ionic strength.

The Calculation of a Serial Fed Gas Permeator System

The calculation methods for the serial fed multistage system were developed for the four flow pattern, i.e., perfect mixing, concurrent flow, cross flow, and countercurrent flow, under the condition of constant membrane area or constant cut. The calculations were performed for two examples using permeabilities of polyimide. One is the case in which concentrate H2 is up to 95% in the total permeate stream from a 75% H2-25% CO mixture. Another is the case in which concentrate CH4 is up to 98% in the high-pressure stream from a 60% CH4-40% CO2 mixture. A brief parametric study shows that the system consisting of countercurrent flow modules under the condition of constant cut is most efficient among the cases studied and should minimize the number of stages using big modules. On the other hand, the system composed of perfect mixing or concurrent flow modules under the condition of constant membrane area is more efficient than constant cut, and it is advantageous to assemble a system using a large number of small modules. The performance of the system comprised of cross flow modules is identical with that of a single module. 14 references, 6 figures, 5 tables.

Thermal Resistance of Asymmetric Polyimide Membrane for Gas Separation

る分離. 精製技 術の開発研究を行 って来て いる。膜素材 としては, 無 機系 (多孔質ガ ラス), 有機系 (ポ リイ ミド, ポ リスル ホン, テフ ロン) があ り, ポ リイ ミド膜につい ては実用化 ・商品化 の段階1)と なっている。 有機系膜 の 場合, 目標値 として最 高使 用温度100°Cを 設定 して おり, 耐熱性 に優れた素材の開発 を 目指 している。したが って, こうした有機膜のガス分離膜 としての耐熱性の評価, さ らには高温下での性能 変化 を試験す る必要が生ず ること にな る。 そ こで本報で は, ガ ス透 過性能 の温度特性を明 らか に す るために昇温型 ガス透過試験装置 を試作 し, サ ンプル として取 り上 げた非対称 ポ リイ ミド膜 の性能評価を行 っ た。 さらに, 高温下で観察 されたガス透過性能 の劣化機 構を, TGお よびTMAの 熱分析手法 を利用 して明 らか にす ることを試 みた。 2. 昇 温型 ガ ス透 過試 験 装 置

Tortuosity of Microporous Glass for Gas Diffusion

Abstract A random network model of microporous glass with uniform pores was constructed. On the basis of this model, an equation for gas diffusion through microporous glass in the Knudsen regime was derived. The tortuosity of microporous glass was expressed in terms of the ratio of half-length of pore to diameter, Π. The model was applied to previous data of helium diffusion through microporous glass, thus a value of Π = 2.6 ± 0.7 was obtained.

Prediction of Vapor-Liquid Equilibrium of Binary Systems

ある二成分系の液相全維成範囲にわたる活最係数データと。他の温度あるいは圧力下の活敏係数の一点の値とを用いて, 任意の条件下の気液平衡関係を簡単に推算する方法を提出する。多くの二成分系に対して推算値は, 実験値と良い一致を示し, 父この方法が共沸系の気液平衡関係を推算するのにも用いられることを示した。本法を例題で詳述しその結果を図表で示した。