ABSTRACT
Salt separation at super-critical condition is a promising technology to separate dissolved salts from water by utilizing sharp changes in thermal and physical properties of water close to its critical point in a tube in tube separator. To capture flow complexity and geometric asymmetry, a three-dimensional CFD model of salt separator is developed in Fluent ver 16. Simulation results are compared and validated with experimental work by Schubert et al. [19]. The axial temperature profiles predicted by model at different wall temperature are well in agreement with the reported data [19]. The model provides insight to axial and radial flow field, temperature gradients, and so on within the salt separator. The blurred boundary between super-critical and sub-critical regions is captured by accounting sharp changes in physical properties of water close to critical temperature and pressure. Sensitivity of key process parameters (e.g., vessel wall temperature, feed pre-heat temperature, flow rates and forced cooling in cold region) was carried out to check effect of operating parameters on deviation in performance of salt separator. No pre-heat feed condition (25°C) is best since it ensures no salt deposition in dip tube without affecting the salt separator performance. Optimum wall temperature lies between 390°C to 470°C to avoid salt deposition and maintain desired temperature gradient between hot and cold section. The modelling framework will aid in efficient design and scale up of salt separator.
Acknowledgments
The authors are grateful for the support provided by Reliance Industries Limited, India.
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