Constant Concentration Method of Measuring Hydrogen Permeation from a Hydrogen Mixture with Pd Membrane

以定濃度法量測氫氣混合氣體滲透鈀金屬薄膜的現象

洪嘉業(Caryat C. Y. Hung) ； 雷敏宏(M. H. Rei)

《Journal of the Chinese Institute of Chemical Engineers》 38卷3&4期 (2007/07) Pp. 341-348

摘要

利用鈀膜管測試混合氫氣的滲透量時，氫氣的濃度順著膜管而遞減，因此所測到的氫氣滲透量與進料濃度無法對比。為解決這困難，本文提供一種簡易的方法使氫氣在膜管的滲透過程保持固定的濃度，以求得正確的氫濃度與其相對的滲透量。這方法使我們發現，雖然使用氫氣的分壓，Sieverts公式仍不適用於測試混合氫氣的滲透值(permeance)，滲透值除了與平方根的壓力差有關之外，也受進料中氫氣濃度所影響。

並列摘要

The conventional flow method of measuring hydrogen permeation flux was found to be inaccurate and inadequate to obtain a consistent value of hydrogen flux and permeance because of changing hydrogen concentration along the palladium membrane tube in a hydrogen mixture. We designed a new method in which the hydrogen concentration was kept constant in the retentate. This constant concentration method was a more accurate measurement of hydrogen permeation flux in all of the possible hydrogen mixtures: H2+Y with Y=Ar, N2 and CH4 and various hydrogen concentrations under different pressure. Permselectivity of the hydrogen mixture was measured under this constant concentration method and was compared with both the conventional flow-through method and separate flow measurement of pure component gases. All three methods gave a different value of permselectivity for the same composite mixture.
This method enables us to measure hydrogen flux and permeance accurately in the corresponding composition of the mixture. We found that even with the same partial hydrogen pressure differential for Sieverts' equation, the hydrogen flux and permeance decreased dramatically with the lowering of hydrogen concentration in the feed.

並列關鍵字

New method of measuring hydrogen permeation ； Permeance of hydrogen mixture ； H2+Ar ； H2+N2 ； H2+CH4