Avaliação experimental dos coeficientes de transferencia de massa e calor em uma coluna com pratos perfurados

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Due to the relation with the mass, heat and momentum transfer phenomena, capacity and operational characteristics, thermodynamic properties and the wide relationship with other industrial equipment, the study of the separation processes by distillation becomes very complex, in spite of its extensive use in the chemical and petrochemical industries. For this reason, researches of great scientific relevance are still being developed for better understanding the related phenomena and for allowing the improvement of the operation. Thus, this work presents as objective the experimental study of a distillation column with sieve plates to evaluate the behaviour of the Murphree efficiency, Q Connell and Barros &Wolf correlations and the mass and heat transfer coefficients along the equipment. The experimental data were obtained used for the validation of the equilibrium and nonequilibrium stage models and of the new efficiency correlation developed by Barros &Wolf. For these purposes, a stainless steel distillation column with eight sieve plates with down comer and a system for the power measuring were designed and built. The column contains eight spaced temperature/sample points. For each experiment, the ethanol feed composition and the heat duty were changed to evaluate the influence of the heat duty on the behaviour of the mole fractions and on the temperature profiles in the column operating at total reflux. After established the steady state, the liquid samples and the temperature were taken in each stage of the column, and the samples were analyzed using the gas chromatography technique. Using the temperature and ethanol and water compositions in each stage and the heat duty supplied to the reboiler, Murphree and Q Connell efficiency were calculated. The programs involving the equilibrium stage model (with Barros &Wolf correlation) and the nonequilibrium stage model developed in the Laboratory of Separation Process Development (UNICAMP) were used in the simulations at the same conditions of the experiments. The data obtained with simulations were compared with experimental data to corroborate such models. The obtained results showed that the equilibrium stage model and the nonequilibrium stage model reproduce, with great fidelity, the real conditions of the process and they can be used to represent the real behaviour of the mass and heat transfer coefficients along the distillation column

ASSUNTO(S)

massa - transferencia mass and heat transfers efficiency equilibrio liquido-vapor azeotropo calor - transmissão nonequilibrium stage model distillation destilação termodinamica de sistemas em não-equilibrio

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