Patent GB-818421-A (GB)
Title: Method of manufacturing water or hydrogen sulfide rich in deuterium
IPC: C01B4/00
Filed: 1956-06-18
Abstract: <PICT:0818421/III/1> <PICT:0818421/III/2> <PICT:0818421/III/3> In the manufacture of water or hydrogen sulphide rich in deuterium by effecting transfer of deuterium between liquid hydrogen sulphide and water in a cyclic system connecting two zones at different temperatures in both of which the water and liquid hydrogen sulphide streams flow in countercurrent and intermingle as in Specification 818,777, a substance miscible with H2S, but substantially immiscible with water, and having a vapour pressure substantially less than that of the H2S to reduce the pressure necessary to maintain the H2S liquid is added to the H2S.  The substance should have a vapour pressure 1/4 of that of H2S at 80 DEG  C., a low molecular volume, i.e. less than 125 ml./grm. mol. and a density less than H2O or much greater, and may be ethylene dichloride, carbon disulphide, ethyl chloride, butane, pentane, methanethio, or ethanethiol.  It is stated CCl3F, CCl2F2, CClF3, CHCl2F, or C2Cl3F3 could be used, but are not so suitable.  The amount of substance should be not more than 2-3 times the volume of the original H2S.  In Fig. 1, the water is circulated by pumps 3, 4 through heat exchanger 11, heater 15, hot tower 1, say at 90 DEG  C., where D2 is transferred from H2O to H2S, heat exchanger 11, refrigerator 13, and cold tower 2, say at 10 DEG C., where D2 is transferred from H2S to H2O, by pipes 5, 6, while liquid H2S is circulated by pumps 7, 8 and pipes 9, 10 through heat exchanger 12, refrigerator 14, cold tower 2, heat exchanger 12, heater 16, and hot tower 1.  The pressure in the system is sufficient to maintain the H2S liquid.  A substance to lower the freezing point of water, as used in Specification 818,777, is not necessary in the present process, but the water may contain an inert water-miscible organic liquid, e.g. alcohol, to make the heat capacities of the H2O and H2S streams approximately equal.  The rate of flow of H2S may be 1000 gals./min. and of water 200 gals./min.  A small stream of product is withdrawn at 17, and deuterium is replaced by withdrawing a small stream of H2S at 24 and passing it through an exchange unit 25, at the same temperature as tower 1, in contact with a counterflow of deaerated water from 26, before return at 28.  The water passes to separating unit 30 where H2S and the substance are recovered, by steam stripping, compressed, and returned to the cycle at 32.  Where no alcohol is added to the water, it is withdrawn at 60 and passed to H2S recovery in the separating unit 30, and fresh, deaerated water, heated in 62, is passed to tower 1 at 63.  The stream of enriched H2O 17 may be passed to an electrolytic enrichment unit 19, from which depleted H2O is returned through 20, or to further dual temperature enrichment units.  In Fig. 2 the stream 17 is led into hot column 11 of a system having cold column 21 in which liquid H2S and H2O are circulated in countercurrent, as in Fig. 1, but the capacity of which is much smaller.  The enriched H2O is withdrawn to distillation desorption apparatus 40, in which H2S is removed as a gas, compressed, and returned to the circuit at 42 and a depleted H2O stream is recovered at 43 and returned to the cycle at 44.  The enriched water flows through pipe 49 to electrolytic enrichment unit 45 containing several cells 46, 47, 48 (Fig. 3), from which deuterium oxide is recovered at 50, while the H2 and D2 evolved are converted to oxide by air or O2-enriched air in reactors 51, 52, 53 from which the condensates are returned to the preceding cell or, in the case 51, to tower 11 at 55.  In an alternative arrangement (Figs. 4 and 5, not shown) heavy water is produced in a similar system, but enriched H2S is transferred from stage to stage.