Abstract
Analysis of crude oil distillation unit stability and operation optimization were performed to maximize light fraction yields and to reduce adverse event risks using a superheated water steam of different flow rates and technological parameters in processes of oil distillation. Mathematical models of crude oil distillation units with and without partially heat integration have been developed using Aspen Hysys. An algorithm of stability analysis using steady state mathematical models is proposed. The conditions of water-hydrocarbon azeotropes formation and possible water condensation on the trays have been theoretically investigated in the distillation columns to eliminate the operation instability of distillation units. Parametrical sensitivities of light fraction yields, of heat loads and steam loads on the trays to perturbations of the superheated steam flow rate are estimated. The extreme behavior of parametrical sensitivity coefficients to small perturbation of steam flow rates is observed for both distillation units. Small absolute values of these coefficients ensure stable unit operation throughout the range of superheated water steam flow rates fed to the cube of the main column. An optimization criterion based on the product yield and energy consumption for steam production and condensation is formed. Objective function extremes depending on physical parameters and steam flow rates are numerically determined. Optimal temperatures and water steam flow rates corresponding to the maxima of the objective function for both distillation units are defined. The results obtained have been put into practice.
Keywords: crude oil distillation unit, multicomponent system, superheated water steam, stability, parametrical sensitivity, optimization, objective function, stream integration, azeotrope
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