Optimization of a Crude Atmospheric Distillation Unit
PROCESS constructed a simulation model of an existing crude distillation unit and tuned the model to actual plant data to allow PROCESS to evaluate existing unit performance, conduct a parametric study of the heat exchanger network simultaneously with distillation optimization, and determine the ultimate capacity of the major unit equipment. The crude unit consisted of the preheat train (11 exchangers and a crude desalter), a pre-fractionation tower, two fired heaters, an atmospheric crude distillation tower, and a vacuum distillation tower. The heat exchanger network was modeled using CCTherm, and a pinch analysis was performed using composite curves generated by ChemCAD. The composite curves were evaluated simultaneously with the optimization of the distillation objectives in order to maximize modeled unit capacity and energy recovery at minimum unit revamp cost. Information from the simulation effort included: overall unit mass and energy balances; tower operating profiles; tower tray, packing, and grid loadings; tower ultimate distillation capacity per section; heat exchanger pinch analysis and composite curves; hydraulic piping losses and heat exchanger pressure drops; and product distillation curves and properties.
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