Study of the Control Systems of a Distillation Process Equipped with Heat Pump

Abstract

The paper presents the results of the researches on the modelling and simulation of the propylene-propane mixture distillation process equipped with heat pump. Industrial data regarding the process structure, operating data and control structure are presented. Modelling and simulation of the process was accomplished using the resources of the Unisim Design simulator. Because the simulator does not include a mathematical model associated with the distillation process equipped with heat pump, the distillation column model was replaced with the Reboiled Absorber model from the simulation environment library. An analysis of the multivariable character of the distillation process revealed discrepancies between the structure determined by the Relative Gain Array analysis and the industrial control structure. The design of the control systems requires dynamic simulation of the process, so the authors� research was focused on the dynamic simulation of the absorption process. The obtained dynamic model was the starting point for testing the propylene quality control system. Finally, the optimal operating conditions for this process were analyzed.

Modelling the Atmospheric Distillation Using the Unisim Design Simulator

“…The calculation elements of the mathematical model are as follows: a) Calculation of product specifications on the TBP curve; b) Calculation of white products potential; c) Calculation of physical properties curves for crude oil (average percentage curvedensity and efficiency curve -density); d) Calculation of average properties of distilled fractions (density, molecular weight, characterization factor); e) Calculation of the fractions distillation curves (TBP, ASTM, FVE). More details on the calculation algorithm are presented in paper [11]. The running of the calculation program has generated results, the most important in the context of the present study being the volumetric and molar distribution of the four products separated in the atmospheric distillation column, table 2.…”

“…Based on these experimental data, the author has approached two methods for calculating liquid-vapor balance for crude oil and petroleum products derived from it as well as for other physical properties. The two methods are: the method based on the Edmister-Okamoto correlations [11] and the method based on the transformation of the petroleum product into a mixture of pseudo-constituents [12].…”

Advanced Control Solution for a Refinery Gas Sweetening Process

“…This control structure was implemented with good results for propylene/propane distillation column [8,9]. Because there are some similitudes between the two processes (propylene/propane column and gas sweetening process) regarding the dynamic behavior, the authors concern was to see if this control structure offers also good results for gas sweetening process.…”