DE1129135B - Process for the production of hydrogen or ammonia enriched in deuterium - Google Patents

Description

The deuterium exchange between hydrogen and liquid ammonia is one of the cheapest A method of concentrating deuterium, and one of the main approaches to performing one such a process is the two-tower, double-temperature process, as described in Proceedings of the International Conference on the Peaceful Uses of Atomic Energy, Geneva, 1955 ", Vol. 8, pp. 399-403, and in U.S. Patent 2,690,379. A complication with a continuous Process arises from the fact that it is necessary to remove the deuterium-depleted ammonia to be brought into contact with water in a separate exchange tower. The deuterium exchange constant between water and ammonia is close to one, so that the deuterium content of the ammonia is up to its natural concentration is restored. Such a procedure is described in the first full section on p. 403, vol. 8, of the "Proceedings ..." mentioned above. The ammonia-water exchange reaction can take place in a tower, which is essentially a distillation column, with one zone near the feeder in which the exchange takes place. Such a tower has one rather large steam consumption, and the waste heat must somehow be used in the best possible way the power contained therein. It is also necessary to remove the potassium amide catalyst from the depleted ammonia recover by evaporating the ammonia and remixing the Catalyst with the regenerated ammonia, otherwise with the deuterium exchange between Ammonia and water hydrolysis of the catalyst occurs.

In "Angewandte Chemie", Vol. 68 (1956), p. 13, Fig. 9, a method is described in which that of a double temperature water-hydrogen exchange process coming from deuterium-depleted hydrogen with deuterium layered by bringing it into contact with water at high temperature (250 ° C) will.

The purpose of the method according to the invention is to avoid the ammonia coming into contact with water and also to bypass the separation of the catalyst from the ammonia by re-enrichment of the deuterium in the hydrogen stream instead of the liquid ammonia stream becomes an essential one Reduction in the strength of these currents is achieved as the capacity of the plant is increased by the hydrogen

of enriched in deuterium

Hydrogen or ammonia

Applicant:

United Kingdom Atomic Energy Authority, London

Representative: Dipl.-Ing. E. Schubert, patent attorney,
Siegen, Oranienstr. 14th

Claimed priority;
Great Britain August 2, 1956 (No. 23 936)

Peter Thomas Walker, London,
has been named as the inventor

current is determined. In an ammonia re-enrichment process the capacity is determined by the ammonia flow, and the hydrogen flow must be several times greater than that Ammonia flow (e.g. five times as large). This means a substantial reduction in both capital and operating costs.

The separation of the liquid ammonia and the catalyst is another costly process, and further savings can be made by avoiding or bypassing it.

The method according to the invention is a method for the production of deuterium enriched Hydrogen or ammonia through deuterium exchange between a homogeneous exchange catalyst containing liquid ammonia and hydrogen in a hot-cold column pair with re-enrichment one of the reactants leaving the hot-cold system in a depleted state before its reintroduction into the hot-cold system by exchanging deuterium with water from natural Deuterium content, which is characterized in that that which flows out of the cold column is depleted Hydrogen with the water at a higher temperature in the presence of an exchange catalyst brought into contact and then returned to the hot column.

The deuterium can by distillation of the hydrogen enriched in deuterium between the hot and cold tower.

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Alternatively, the ammonia enriched in deuterium can be obtained by distilling the enriched ammonia liquid ammonia can be obtained between the hot and cold towers.

The invention will now be explained in more detail with reference to the drawing showing it for example The figure shows a flow diagram for the production of deuterium enriched hydrogen.

The production of hydrogen enriched in deuterium consists of three separate processes together; an ammonia-hydrogen two tower double temperature exchange process, a hydrogen distillation process and a high temperature hydrogen-water exchange process.

In a two-tower process, the liquid ammonia, which contains potassium sulphide as a catalyst, runs continuously between two towers arranged in series, with one of the towers at a higher temperature than the other is held. The water ao Substance comes into contact with the ammonia by flowing countercurrently through the towers. He enters the hotter tower first, where it competes according to the physical properties of the system Deuterium is enriched; enriched hydrogen is at points. The main crowd the hydrogen then flows through the colder tower, where it is depleted in deuterium.

This depleted hydrogen then goes into the high temperature hydrogen-water exchange process, where the hydrogen is brought into contact with steam via a catalyst in a reactor to replenish the deuterium content of the hydrogen. The one leaving the reactor Hydrogen must be freed from water vapor before it enters the hot tower of the two-tower process occurs, but this is technically a far simpler process than removing water from liquid Ammonia.

Part of the enriched hydrogen is withdrawn at point B and fed to a hydrogen distillation process. This process results in a final product of highly enriched hydrogen and rejects depleted hydrogen which meets the depleted hydrogen from the cold tower at point C prior to re-enrichment.

The temperature must be controlled at all stages of the process and the various streams treated as indicated in the drawing; X indicates heat supply and O heat removal. These treatments can be chained together as appropriate.

Local economic conditions and conditions can of course vary the process conditions chosen. The example described was in the UK at a pressure of 50 atmospheres in the entire system, and at working temperatures of 30 ° C for the hot tower, -60 ° C for the cold tower, 550 ⁰ C for the hydrogen-water reactor, and - 225 ° C for hydrogen distillation.

Under these conditions, the depleted hydrogen leaving the reactor has a deuterium concentration of 0.7 of the natural concentration and, using ten theoretical trays in each of the hot and cold towers, it is the deuterium concentration of the one at point B. Hydrogen distillation of withdrawn enriched hydrogen twice the natural concentration. The product is 99.8% deuterium, and the still reject and hydrogen exiting the cold tower both have a deuterium concentration of one-seventh the natural concentration before re-enrichment.

In the alternative method for obtaining ammonia enriched in deuterium, the hydrogen distillation is replaced by a similar ammonia distillation, the enriched ammonia is withdrawn from point .4 of the ammonia cycle and the depleted ammonia is returned to point D of the cycle. The enrichment of ammonia at A is slightly higher than that of hydrogen at B.

Claims (1)

PATENT CLAIM: Process for the production of hydrogen or ammonia enriched in deuterium by means of deuterium exchange between liquid ammonia containing a homogeneous exchange catalyst and hydrogen in a hot-cold column pair with re-enrichment of one of the reactants leaving the hot-cold system in a depleted state before it is reintroduced into the hot-cold -System by deuterium exchange with water of natural deuterium content, characterized in that the depleted hydrogen flowing out of the cold column is brought into contact with the water at a higher temperature in the presence of an exchange catalyst and then returned to the hot column. Considered publications:
U.S. Patent No. 2,690,379;
Angew. Chem., 68 (1956), pp. 10 and 12;
Proc. of the International Conference on the Peaceful Uses of Atomic Energy, 1955, Vol. 8, p. 403. 1 sheet of drawings @ 209 579/245 5.62