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Overall heat transfer coefficients, pressure drop and power demand in plate heat exchangers during the ammonia liquor cooling process

Abstract:

In the Ammonia Recovery process of the nickel company the pressure drop of the Ammonia liquor cooling process, by means of the plate heat exchangers, is associated to the incorrect estimate of the overall heat transfer coefficients and fluid parameters: Water and ammonia liquor outlet temperature, Water and ammonia liquor mass flow. The above increases the consumption of water, the available energy in the system and the maintenance costs. The investigation was carried out in plate heat exchangers, with the objective of determining the overall heat transfer coefficients and the behavior of pressure drop and power required for the ammonia liquor cooling process. By means of an iterative procedure was determined the equation and behavior of the overall heat transfer coefficients and their dependence with the Reynolds and Prandtl, for it was used a multifactor experimental design and measurements of the installation work parameters in function of the time. The results pbkp_redict the knowledge of the overall heat transfer coefficients for the calculation of the Nusselt number with the Reynolds and Prandtl values for both fluids (water and ammonia liquor). The comparison with other investigators shows correspondence with Thonon results. To the overall heat transfer coefficient values less than 2500 W/m2K, the outlet temperature of the ammonia liquor exceeds 40 OC so the maintenance of the installation is recommended in less than 27 days period. The behavior of pressure drop and power demand as a function of the Reynolds number was obtained. Values for cooling the liquor are diminished compared to the water, it is because more water is used.