DE1243155B - Device for cleaning gases by diffusion - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

BOId

German class: 12e-3/04

Number; 1 243 155

File number: E 21217IV c / 12 e

Filing date: June 9, 1961

Docking date: June 29, 1967

In order to obtain hydrogen of a high degree of purity, commercially available hydrogen can be diffused can be purified by palladium. A suitable device for this purpose, the palladium tubes, which are arranged in a helical shape is described in U.S. Pat. No. 2,911,057. A highly selective separation by diffusion is also obtained when using helium and allows oxygen to diffuse through glass (containing silicon oxide) or silver.

When hydrogen diffuses through palladium, it is desirable at an elevated temperature level of a few hundred degrees Celsius to work. Therefore, the helical shape of the tubes serves according to the patent cited above, the thermal Allow expansion and contraction of the palladium tubes without breaking the pressure seal of the enveloping container breaks.

The diffusion devices that have been used heretofore have an inlet chamber through which circulates the raw gas, and a recovery chamber. The inlet chamber and the recovery chamber are diaphragm apart separated, which consists of a material that has selective permeability for the gas that is extracted should be owns.

Normally the recovery chamber of a diffusion device has only a single connection pipe, that is the outlet for the purified gas. But it has also been suggested to provide the recovery chamber with an inlet and an outlet.

With this kind of arrangement, an advantageous gas flow can be obtained in the recovery space will. It is desirable to allow a part of the gas flow to diffuse back into the recovery space avoid. The gas flows in the recovery space in countercurrent to the gas in the palladium pipes, and thereby there is a gradual increase in the hydrogen content in the recovery chamber and a gradual decrease in the hydrogen content inside the palladium tubes. When the palladium tubes However, if they are helical, an effective countercurrent can be achieved without backmixing not easily obtained.

It has been found that in a device for purifying gases by diffusion, consisting of an inlet and an outlet chamber near the inlet chamber, an outlet for the purified gas and an inlet for generating a countercurrent near the outlet chamber, optionally heatable cylinder, wherein Device for purifying gases
by diffusion "

Applicant:

Engelhard Industries, Inc.,

Newark, N.J. (V. St. A.)

Representative:

Dr.-Ing. W. Abitz, patent attorney,

Munich 27, Pienzenauer Str. 28

Named as inventor:
William C. Pfefferte, Middletown, NJ;

Martin F. Collins, Jersey City, N.J. (V. St. A.)

Claimed priority:
V. St. v. America June 10, 1960 (35 299) - -

the inlet chamber with the outlet chamber over many.

The pipes that allow diffusion are connected,

the back diffusion is reduced, while at the same time on a different thermal expansion or - contraction of the diffusion tubes and the surrounding chamber must be taken into account when according to the invention in the cylinder, a plate forming a U-shaped space protrudes into the cylinder opening, on one End of the cylinder perpendicular to this plate a cross-section filling the inlet chamber and Outlet chamber forming plate is arranged and that the two chambers by U-shaped bent Diffusion tubes are connected to each other.

The device is to be explained in more detail, for example, with reference to the drawings.

F i g. 1 shows a device with a U-shaped Diffusion space;

F i g. Figure 2 shows another embodiment in which a preheater is used and in which the palladium tubes are grouped in suspended bundles;

FIG. 3 shows a view of part of the FIG. 2 shown device;

F i g. 4 and 5 show two views of an upper part of the pipe, which is shown in FIG. 2 and 3 shown Device is used.

In Fig. 1, a recovery chamber 12 is shown which has a cylindrical FoaBv and from corrosion-resistant steel is made. These

'. : 709 608/379

Chamber is divided into two semi-cylindrical parts by means of a corrosion-resistant steel plate 14, which extends across the chamber 12 for almost its entire length. Due to the arrangement of the partition plate 14, the extraction space 12 is given a U-shaped configuration, with one leg of the U is above the partition plate 14 and the other leg of the U is below the partition plate 14.

The apertured end plate 16 made of corrosion-resistant steel has an upper one a lower semi-cylindrical plate. which closes one end of the extraction chamber 12. One Row of U-shaped diffusion tubes is in the Extraction chamber arranged with one leg of each of the tubes in the end plate 16 above the divider plate 14 and the other is attached under the same. Two of these U-shaped diffusion tubes 18 and 20 are in Fig. 1 shown. It will be noted that the tubes 18 and 20 are both the same shape and shape have the same curvature.

The other tubes 22, which are shown broken, have a corresponding configuration. When the diffusion tubes are generally of the same shape and many or all of one another are identical, manufacture is simplified and the same diffusion effect becomes obtained from each tube extending through the recovery space.

The extraction chamber 12 is surrounded by a heating coil 24. The resistance wire can, for example be a chrome-nickel wire, and the turns are in a layer of cement 26, for example enclosed in an asbestos cement layer. The whole facility is in an aluminum container 28, which has end plates 30 and 32 made of asbestos cement or the like Material are made. The rest of the space within the chamber 28 is covered with a heat insulating material Material 34, such as B. Magnesium oxide filled.

The incoming low purity gas is supplied to the inlet space 36 through the inlet pipe 38 introduced. The output flow of the gas recovered from the diffusion tubes is in the chamber 40 and is connected to the inlet to the recovery chamber 12 through tubes 42 and 44 and the pressure reducer 46 is connected. The exhaust gas is blown out of the pressure reducer 46 through the pipe 48.

The countercurrent arrangement illustrated in the drawings of this invention is used to reduce the total pressure drop required across the parallel tubes. This will obtain a system in which the flow velocity is relatively high. With the countercurrent, like As shown in the drawings, there are high partial pressure differentials in the U-shaped recovery chamber maintained without the absolute pressure difference on both sides of the tubes is undesirably high. In this way, high diffusion rates are obtained without Pressures must be achieved at which the tubes break easily.

For example, the raw gas contains 10 Vo hydrogen and 90% nitrogen at a pressure of 24.608 kg / cm ² . The raw gas was introduced into the diffusion device containing the palladium tubes at a rate of 1.91 per minute. A pressure reducer 46 reduced the pressure in the extraction chamber to 3.164 kg / cm ^like. The gas that passed through the pressure reducer had a composition of about 0.26% hydrogen and 99.74% nitrogen. The partial pressure of hydrogen at the exit of the palladium tube was about 0.07 kg / cm ^s . Similarly, the partial pressure of the hydrogen in the gas supplied to the inlet of the recovery chamber was

ίο was about 0.00844 kg / cm ² . At the exit of the recovery chamber, the concentration of hydrogen was 47% compared to 53% nitrogen. The flow rate was about 0.41 per minute. It was also found that the partial pressure of the hydrogen in the palladium tubes and in the recovery chamber near the outlet of the recovery device was 2.531 and 1.476 kg / cm ² , respectively.
In the arrangement shown in FIG. 1, a distance is provided between the dashed line 50 and the right-hand end of the chamber 12 in order to allow the thermal expansion of the tubes and the chambers when the resistance winding 24 is traversed by the current. This expansion path is indicated by a double arrow 52 in the drawing. There will also be a slight expansion between the outer ends of the tubes. Accordingly, a small clearance is provided between the walls of the chambers 12 and the tubes.

The in F i g. 2 is the embodiment shown in FIG. 1 shown similarly. However, it is with the in Fig. 2, a preheater 56 is provided in place of the resistance turn 24.

In addition, the palladium diffusion tubes are arranged in bundles and in groups of seven each connected to a distributor 58. The manifolds 58 are in turn secured in the end plate 60, and in this way the inlet chamber 62 and the Outlet chamber 64 connected to one another via the diffusion tubes. The manifold 58 extends a significant distance beyond the surface of the end plate 60 so that the palladium tubes with these manifolds can be easily soldered without excessive heat flowing to the plate 60. On the other hand, the distributors can also turn to the left, as in FIG. 2 and 3 is shown over extend the plate out. In this case, the palladium tubes extend the entire length of the Manifold or header pipes and are soldered to the left end of the same.

As in an embodiment according to FIG. 1, the cylindrical chamber 66 can be made of corrosion-resistant Made of steel. The partition plate 68 can also be made of the same material. That The aluminum outer housing 70 is separated from the inner chamber 68 by means of a suitable insulating material, as described above in connection with FIG. 1 has been described, isolated. Moreover, the whole nature of the gas flow is in that shown in FIG The embodiment shown is essentially the same as in the embodiment shown in FIG. 1 shown.

The incoming gas of low purity is directed to the preheater 56 before it flows into the inlet chamber 62. Preheating is particularly important for the large-scale industrial process more economical than using resistance heating around the chamber walls. The one for one

System of the type described in question are the following dimensions: The cylinder 66 can have a diameter of about 12.7 cm and a length of up to 7.52 m. Each of the 49 palladium or Palladium-silver tubes can have a diameter of 3.175 and a wall thickness of about 0.2 mm own.

In Fig. 3, the headers 58 are enlarged Scale shown. Three of the 14 headers used for a typical installation are shown in FIG. 3 shown. Seven of the manifold tubes are above the septum 68 and seven arranged below this.

As shown in Figs. 4 and 5, the headers are cylindrical in shape, each having seven holes 72 running the full length of these tubes. As in Fig. 3 shown is, the palladium tubes are fixed in the protruding end portion of the collecting tube 58. Five of the seven tubes 74 are shown in FIG. 3 shown. The tube group of each collecting tube forms a small one Bundle and is held at various points along the length of the chamber 66. In Fig. 2 there are three Tube bundles 74, 76 and 78 can be seen.

As stated above, it is desirable that the gas be uninterrupted and free of backflow flows within the chamber 66. Accordingly, some of the tube bundles are simultaneously by means of Support members 80, 82, 84, 86 and 88 in Fig. 2 are supported. These supports can extend below and above the partition plate 68. Only some of the seven bundles are supported at some point. Each bundle, on the other hand, is periodic along it Length to avoid unwanted sagging and uneven distribution of the tubes in the chamber 66 to avoid. The places where the three bundles 74, 76 and 78 are supported in the chamber 66 are indicated by black circles at the points of intersection with the support members 80, 82, 84, 86, 88 and 90 are displayed. The support members can be made of sheet metal or other suitable construction material be made.

In addition to the use of pure palladium diffusion tubes Alloys of palladium with up to 50% silver can be used.

The effect of diffusion in all of the selective diffusion processes discussed above is enhanced by the application of heat. Temperatures above room temperature up to about 600 ° C have been used with palladium or palladium alloy pipes. The preferred temperature range is from 200 to 45O ⁰ C. The heat is limited by the thickness of the palladium tube and the pressure applied to them. It must be so dimensioned that there is no risk of the pipes breaking. With thinner pipe walls, the applied temperatures or pressures or both must therefore be lower.

Claims (3)

Patent claims: 1. Device for cleaning gases by diffusion, consisting of an inlet and an outlet chamber near the inlet chamber, an outlet for the purified gas and for generation a countercurrent near the outlet chamber having an inlet, optionally heatable cylinder, the inlet chamber being connected to the outlet chamber via many tubes that allow diffusion, characterized in that in the cylinder a plate (14) forming a U-shaped space projects into the cylinder opening, on one End of the cylinder perpendicular to the plate (14) has a cross-section filling the inlet chamber (36) and outlet chamber (40) forming plate (16) is arranged and that the two chambers through U-shaped bent diffusion tubes (18.20, 22) are connected to each other. 2. Device according to claim 1, characterized in that that in the plate (16) pipe pieces (58) which receive a plurality of diffusion pipes (72, 74), are provided. 3. Apparatus according to claim 1 or 2, characterized in that supports (80, 82, 84, 86, 88) for the diffusion tubes are arranged periodically. Considered publications:
French Patent No. 1178 480;
U.S. Patent No. 2,911,057. 1 sheet of drawings