Study On Crystallization Kinetics Of Sodium Chloride In Ethylene Glycol Solution

At present, more and more of the glycol regeneration desalination system has been applied in deep water gas field development relying on the platform, which is particularly critical desalination unit is mainly from the rich glycol solution solid salt particles and liquid to remove salt from ethylene glycol regeneration desalination system, in order to reduce equipment, pipeline corrosion. Salt in ethylene glycol solution crystallization rate will directly influence the desalting efficiency of desalination system, at the same time, the granularity of the salt crystallization of particles size will also affect the choice of the separation equipment and parameter setting, in order to improve the desalting efficiency of desalination system, and provide theory basis for equipment type selection, it is necessary to carry out the crystallization behavior of salt in ethylene glycol system research. This paper takes the perspective of sodium salt in ethylene glycol solution crystallization research thermodynamic properties, dynamic properties of sodium salt in ethylene glycol and the different factors on sodium salt crystallization kinetics and the influence of particle size distribution rules, provide data support and theoretical basis for the selection and parameter optimization of desalination technology and equipment, has the vital significance to the realization of glycol regeneration desalination system design localization. Of the crystallization process of sodium salt in ethylene glycol, this paper has carried out the following several aspects of research:(1) The solubility of sodium chloride at different temperatures in ethylene glycol is obtained by static method, and the appropriate use of solid-liquid equilibrium model is fitted to the experimental results, and at last obtained the equation.(2) The supersolubility of sodium chloride in ethylene glycol is measured by laser method, and combined with solubility curve obtained the metastable zone, and discussed the influence of temperature on the metastable zone width. The results show that the limit supersaturation of sodium chloride in the ethylene glycol solution is small under the experimental conditions; lower than the metastable zone width of393.15K is wide and stable, higher than the metastable zone width of393.15K will gradually narrow with the increase of temperature.(3) The induction period of sodium chloride in ethylene glycol solution is measured, in order to investigate the influence of different degree of supersaturation on the induction period. The results show that the higher the degree of supersaturation, the smaller the induction period.(4) Intermittent dynamic method is used to study the crystallization kinetics of sodium chloride in ethylene glycol solution, the sodium chloride in the nucleation rate equation and the growth rate equation of ethylene glycol, and on this basis, discuss the degree of supersaturation and temperature on the influence of sodium chloride crystallization kinetics. Results show that:increasing the temperature, growth rate and nucleation rate will increase, and the nucleation occurs more easily; increasing the degree of supersaturation and nucleation rate, growth rate will be larger; increasing the suspension density, the nucleation rate will increase.(5) Factors such as temperature, vacuum degree is studied through laboratory experiments on the effect of sodium chloride crystal size distribution are studied. The results show that under the same conditions, the higher temperature, the crystal size distribution more dispersed, the smaller average particle size; the higher vacuum degree, the crystal size distribution more dispersed, the smaller average particle size; solid-liquid ratio is too high or too low will lead to the mean particle size of crystal smaller; residence time is too long or too short will lead to the average crystal size smaller.