2 - Hydrogen isotope separation by rectification

Abstract

This chapter describes the hydrogen isotope separation by rectification. Water rectification is the simplest method of heavy water production. This method offers a variety of apparent advantages such as limitless raw material resources and the possibility to carry out the process on the simplest non-depletion principle, absence of corrosion, toxicity, inflammability, and explosion hazards. The rectification optimum conditions should be selected with regard to their influence both on the separation factor, and on the reaction kinetics and hydrodynamics, which requires taking into account the adopted type of column contactors. Heavy water can be obtained not only by water rectification, but also by rectification of other hydrogen compounds such as ammonia. Considering that ammonia rectification requires lower grade heat than water vacuum rectification, these two rectification processes can be combined into a multiple-unit rectification scheme where water vacuum rectification exhaust gas is utilized for heating the ammonia column evaporator. The circulation scheme of ammonia rectification together with ammonia-water isotope exchange has the advantage of independence from the ammonia source. The heavy water production by cryogenic rectification of hydrogen is also elaborated.