METHOD AND APPARATUS FOR REGENERATING COLD TRAPS WITHIN LIQUID-METAL CIRCULATORY SYSTEMS

摘要

1489329 Recovery of sodium hydroxide values from liquid sodium UNITED STATES ENERGY RESEARCH & DEVELOPMENT ADMINISTRATION 12 April 1976 [29 May 1975] 14805/76 Heading ClA [Also in Division C7] Liquid sodium or sodium alloys circulating in a system have the impurities Na 2 O and Na hydride removed by depositing the impurities in a cold trap and by heating the trap to react the oxide and hydride to form NaOH, monitoring the hydrogen partial pressure to determine the efficiency of the reaction, and by draining the molten NaOH from the system. Liquid metal is drawn from a circulatory system via pipe 11, through pump 13 to an econimizer 15 wherein the heat of the metal is recovered. The cooled metal feeds through pipe 17 to a cold trap pressure vessel 27, filled with metallic packing material 37 on which the impurities crystallize when the vessel 27 is cooled by blower 39 to say 100-200‹ C. A pressure gauge 30 monitors the hydrogen partial pressure within the tank 27, which may be adjusted as required by either venting or adding hydrogen from supply 65. Tank 27 is also fitted with a drain outlet 31, connected by valve 32 to a second tank 45, which again may be heated or cooled by resistance 53 and blower 55. A level indicator 57 is installed in each 45. In operation, liquid metal withdrawn from the system enters tank 27, passing through economizer 15, to fill the tank, passing outside baffle 35 through packing 37 to the upper tank outlet 19, thence back to the circulatory system, having been cooled to 100-200‹C. in its passage through tank 27, so that the oxide and hydride impurities precipitate out on packing 37. When tank 27 is filled with impurities, it is isolated from the circulatory system by valve 23, and any liquid metal drained via outlet 31 to reservoir 67. The tank 27 is then heated to cause the reaction to occur (temperature of 412-550‹ C.), and the molten NaOH is drained into tank 45. indicator 57 showing when reaction is complete. The partial pressure of hydrogen in tank 27 is then measured to see if excess NaH or NaO is present in tank 27 which may be corrected by altering the H 2 pressure until the level in tank 45 is constant indicating that all the impurities have been removed. The cold trap is then reconnected to the circulatory system for further use.