Deuterium for heavy water is produced from hydrogen - depleted hydrogen being used for power generation

摘要

Prodn. of heavy water is from hydrogen which is obtd. by cracking of hydrocarbons in the presence of steam. The mixture leaving the cracking plant is cooled (to cryogenic temps) to separate the constituents which have a higher b. pt. than hydrogen. The hydrogen flow is then cooled by thermal exchange and expansion to do work. Deuterium is sepd. by rectification and then oxidised to produce heavy water. The remaining hydrogen and pref. also the remaining hydrocarbons from the mixture, after evaporation and reheating, are passed to a power generation plant, and used as fuel or removed. Since the hydrogen used as the deuterium source is produced at 25-30 bars pressure, some of the resultant energy of compression can be recovered to provide power for the cryogenic cooling plant, as the temp. redn. required to liquefy the hydrogen is largely provided by the expansion and throttling of the hydrogen. By using substantially pure hydrogen as a fuel, the quantity of gas discharged from the combustion chamber of the power plant is considerably reduced and heat rejection to atmosphere is less.