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Purification of heavy water used as the moderator and coolant of pressurized heavy water nuclear reactors (PHWRs) is a vital step in ensuring its adequate isotopic content that maintains neutron economy in the reactor core. This process is carried out in a packed vacuum distillation column which requires condensers and reboilers as essential heat transfer components. A vertical thermosiphon reboiler is used to minimize operating costs of the distillation system by eliminating the fluid recirculation pump and improving system reliability and safety by minimizing leakages and heavy water losses. This work presents a simple, direct methodology for optimizing the design and operation of such a reboiler using codes developed in-house and based on heuristics and two-phase heat and momentum transfer correlations from literature. The methodology is general and can be applied to any application requiring a thermosiphon reboiler. Parametric analysis and cost calculations have also been performed along with exergy analysis of reboiler performance. [ABSTRACT FROM AUTHOR]

Simulation studies of batch distillation of some non-ideal binary systems have been carried out and reported in this work. Differential distillation as well as batch distillation at total reflux has been simulated through a semirigorous unsteady state mathematical model, implemented via codes developed in-house. The Wilson model has been used to represent non-ideality in the liquid phase and predict-vapour-liquid equilibrium (VLE) data. Parametric studies of the composition and temperature profiles have been carried out. Heating and cooling requirements for batch distillation operation have also been estimated. The model presented here can be used for simulating the start-up of any distillation column for even multi-component non-ideal systems, as long as the VLE data are available for them, without requiring any commercial simulation software. The model can also be extended to simulation of batch distillation columns with a finite value of reflux ratio after suitable modification of the governing equations. Thus it can be used for preliminary design work as well. [ABSTRACT FROM AUTHOR]

Cryogenic distillation is a very widely applied technique for separating the components of a mixture of hydrogen isotopes, which may contain up to six isotopic species. This work presents a simple dynamic model for evaluating the major performance characteristics of a cryogenic distillation column for hydrogen isotope separation. Liquid hold up, pressure drop and flooding point have been predicted for the tower using known packing characteristics and fluid properties. The column has been modelled as an equivalent tray tower using a known value of the height equivalent to theoretical plate (HETP) and its dynamic behaviour and separation performance under various conditions have been predicted. The effect of parameters like temperature, reflux ratio, feed point location and feed composition on the final isotopic contents of top and bottom products at steady state has also been studied. Consequences of neglecting the decay heat of tritium in distillation calculations have also been evaluated. This model is intended for preliminary column design work using data from literature, without the need for prior experimental activity. [ABSTRACT FROM AUTHOR]