Perfectionnements aux procédés de préparation d'eau lourde par échange isotopique monotherme NH3-H2

摘要

Deuterium-enriched ammonia is obtained by isothermal isotopic deuterium exchange in one or more reactors between liquid ammonia and ammonia synthesis gas containing deuterium, in the presence of a catalyst in solution in the liquid ammonia, circulating continuously in the reactor or reactors, at least one catalyst reinjection loop being connected to at least one of the reactors; in each loop the catalyst leaving the reactors is recovered in a dry condition, and is redissolved in a part of the liquid ammonia supplied to the top of the reactor or reactors to form a concentrated solution which is passed in counter-current to the ammonia synthesis gas withdrawn from the top of the reactor or reactors; this concentrated solution is subsequently injected into the remainder of the ammonia supply to the reactor or reactors, and the gaseous mixture is reinjected at a point of iso-concentration of deuterium. In Fig. 3 a catalyst injection loop comprises an evaporator 8 and an auxiliary reactor assembly 10, and is coupled to two reactor assemblies 1 and 2. Ammonia synthesis gas enters at 5, the deuterium-enriched fraction of ammonia is drawn off at 6, and the deterium-impoverished fraction of ammonia is drawn off at 7. Catalyst delivered from the bottom of reactor 2 is dried in evaporator 8, and the resulting catalyst-free ammonia is delivered to unit 3, which decomposes the ammonia to form ammonia synthesis gas which enters reaction assembly 2 at the bottom. Synthesis unit 4 supplies deuterium-poor liquid ammonia to the top of reactor assembly 1. The catalyst from 8 is redissolved in a fraction of the liquid ammonia tapped from synthesis unit 4 and the solution is delivered to a third, auxiliary, reactor assembly 10 where it is impoverished in deuterium by exchange with gas withdrawn from the top of 1. The catalyst solution is then injected at 9 into the remainder of the ammonia supply which enters 1. The ammonia synthesis gas leaving 10 is reinjected e.g. into 2 at point 11. In Fig. 4 (not shown) two catalyst reinjection loops as described above are employed. The catalyst and liquid ammonia from each reactor assembly (1 and 2) are separated and these two products are treated as described above. Specification 952,335 is referred to.