| 摘要 |
1300496 Refining alkali and alkaline-earth metals INTERATOM INTERNATIONALE ATOMREAKTORBAY GmbH 28 May 1971 [23 July 1970] 18182/71 Heading C7D [Also in Division G6] Carbon impurity is removed from alkali or alkaline-earth metals by passing hydrogen or a hydrogen-containing gas through the metal in molten state, and separating the resulting methane from the metal. The melt is preferably maintained at temperatures between 200 and 600‹ C while the partial pressure of the hydrogen should not exceed 1 atmosphere. An additional small quantity of oxygen speeds the removal of carbon. Apart from its use in refining the metal, and the incidental preparation of pure methane, the invention is particularly applicable to the monitoring and detecting of the carbon content of sodium in the coding systems of nuclear reactors, where a gas chromatograph or flame ionization detector can accurately measure the methane concentration. Apparatus A vessel 1, having a lid 5 and heater at 4 contains molten sodium, the level 3 being maintained by filling gauge 2. A stream of sodium, e.g. withdrawn from the cooling system of a nuclear installation, enters the vessel at 6 and leaves at 7 to flow back into the installation. Hydrogencontaining gas flows through pipe 9 into the sodium by means of openings 10; the methane formed is entrained with the hydrogen-containing gas as it is conveyed through pipe 11 to separator 12, where any sodium is removed, and measuring arrangement 13, where the methane content is evaluated. Hydrogen disolved in the exit sodium stream is removed at 8 by, e.g. a hydrogen-pervious membrane under vacuum. If the hydrogen is recycled from measuring arrangement 13 to pipe 9, while keeping the temperature of the melt constant, an equilibrium can be set up to provide a steady methane content reading. |
