Gas separation: processes – Selective diffusion of gases – Selective diffusion of gases through substantially solid...
Patent
1997-09-11
1999-08-03
Spitzer, Robert
Gas separation: processes
Selective diffusion of gases
Selective diffusion of gases through substantially solid...
95 53, 95 56, 96 11, 55524, B01D 5322, B01D 7102
Patent
active
059319879
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to separation and purification of a gas from a fluid mixture. More particularly, the present invention relates to a membrane gas extraction module for removing preferably hydrogen from a fluid mixture.
BACKGROUND OF THE INVENTION
A common technology for extracting pure hydrogen from industrial streams, such as for hydrogenation for changing the balance of hydrogen in those streams or to increase reaction selectivity, is to use membranes of palladium or palladium alloys alone or supported structurally by a matrix. Membranes which contain thick enough palladium layers to be made without holes and not break during service tend to be expensive and have relatively high resistance to hydrogen permeation.
Several membrane variations and module designs have been proposed to minimize this effect. Membranes can include porous ceramics either by themselves or coated with palladium alloys or with silica and palladium coated refractory metals and alloys, especially those based on Nb, V, Ta, Ti, Zr. These have greater strength than palladium and palladium-based alloys, are cheaper per unit volume, and most have greater intrinsic permeabilities to hydrogen. Although the alternatives are less expensive than Pd, they are not less expensive compared to polymers. Thus, with all of these membranes more attention must be directed to module designs that make efficient use of the membrane surface and provide a high recovery percentage without undue gas-phase mass transfer resistance. To date, no commercial module has been described that is particularly efficient for large scale hydrogen extraction using any of these membranes.
An example of an apparatus for hydrogen separation is disclosed in U.S. Pat. No. 4,468,235 to Hill (Hill '235). The Hill '235 patent discloses an apparatus for separating hydrogen from fluids and includes, mounted axially in a cylindrical pressure vessel, a plurality of membranes in the form of tubes coated on either the inside or the outside or both sides with coatings having a high permeability to hydrogen. There is also a fluid flow inlet and a raffinate flow outlet and a header to collect hydrogen. No sizes or criticalities are disclosed for the extraction membrane. Additionally, since this design provides no mechanism for flow distribution or turbulence generation, the separation efficiency of this apparatus is not maximized.
Another example of a similar apparatus for hydrogen extraction is disclosed in U.S. Pat. No. 5,205,841 to Vaiman (Vaiman '841) issued Apr. 27, 1993. The Vaiman '841 patent discloses an apparatus for separating hydrogen from gas and gas liquid mixtures at low temperature. The Vaiman '841 apparatus includes a plurality of axially mounted tubes coated on both their inside and outside surfaces with palladium/platinum black. There is also a fluid flow inlet and a raffinate flow outlet and a header to collect hydrogen. Vailman '841 does not teach any sizes or criticalities for the extraction membrane or its arrangement within the structure. Additionally, as similarly stated above regarding the Hill patent, the Vaiman '841 design provides no mechanism for flow distribution or turbulence generation. Separation efficiency of this apparatus is not maximized.
Another typical design for large hydrogen extractors uses tubular membranes of palladium-silver alloy in spiral form. This tubing generally has an outer diameter of 0.0625 to 0.125 inches and wall thickness of approximately 0.003 inches. For the smaller diameter tubes, the source hydrogen flows over the outside of several wound helixs made from 10 to 15 feet of tubing. These, hydrogen extractors typically require complex expensive construction that limits heat and mass transport. Also, since pressure drops become excessive when the tube length exceeds about twenty-five feet large modules end up with 40 or more nested and stacked helixes that must be hand assembled in a large tubular bundle without damaging any single one of the delicate tubes. This is a delicate construction process by
REFERENCES:
patent: 2958391 (1960-11-01), deRosset
patent: 3241293 (1966-03-01), Pfefferle
patent: 3241298 (1966-03-01), Pierce
patent: 3344582 (1967-10-01), Merrill et al.
patent: 3350846 (1967-11-01), Makrides et al.
patent: 3368329 (1968-02-01), Eguchi et al.
patent: 3410058 (1968-11-01), Oswin
patent: 4313013 (1982-01-01), Harris
patent: 4427424 (1984-01-01), Charpin et al.
patent: 4468235 (1994-08-01), Hill
patent: 4496373 (1985-01-01), Behr et al.
patent: 4536196 (1985-08-01), Harris
patent: 4810485 (1989-03-01), Marianowski et al.
patent: 4986837 (1991-01-01), Shibata
patent: 5181941 (1993-01-01), Najjar et al.
patent: 5205841 (1993-04-01), Vaiman
patent: 5215729 (1993-06-01), Buxbaum
patent: 5358553 (1994-10-01), Najjar et al.
patent: 5498278 (1996-03-01), Edlund
patent: 5518530 (1996-05-01), Sakai et al.
Booth, J.C.S., Doyle, M.L., Gee, S.M., Miller, J., Scholtz, L-A., and Walker, P.A., "Advanced Hydrogen Separation Via Thin Supported Pd Membranes", Hydrogen Energy Progress XI, vol. 1, pp. 867-878 (No Date).
LandOfFree
Apparatus and methods for gas extraction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and methods for gas extraction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and methods for gas extraction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-845779