Minimização de emissão de poluentes na sintese de resinas fenolicas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

This work describes the optirnization of a novolac resm synthesis catried out m a batch reactor. Basically, the main purpose of this work is to reduce the concentration of phenol in the efluent, because this is the largest problem in the process, since in the industry the concentration of phenol in the efluent is between 20.000 and 50.000 ppm, wich is a high value if the toxity of phenol is to be considered. The maximum value of phenol according to the legislation of a lot of countries is between 1 and 0.01 pprn, depending on the classification of the emissary. The optimization will be then, considered in the separation stage. The efluent is basically compound by phenol and water, wich is resulting of the condensation reaction between phenol, phormol and the water of dilution of phormol, and it leaves the reactor by distillation adding a solvent. In the industry (Resana S. A. Ind. Químicas) was noted that in the column, wich is acoplated to the reactor, this reflux return to the reactor. If the reflux return to the top of the column, the concentration of phenol wil reduce, once the mass transfer will be increased. Therefore it is a point that will be, also, explorated in the modelling. It is important to say that this modelling is very complex because it involves batch complex distillation with chemical reaction. This distillation has characteristics of azeotropic distillation, then there is necessity to choose the best solvent for the system. Some solvents were studied by thermodynamic, economy and toxity analysis in water-so1vent-phenol systems. Nowadays, the industry applies the toluene as the solvent. To characterize the process, two kinds of modelling were made. In the first chemical reaction was not taken-into account and in the second it was considered. To solve the system of equations, was used the Euler method for the first modelling and Runge-Kutta fourth order in the second. The Unifàc method was used for the prediction of activity coeficient in the liquid phase in liquid-vapor and liquid-liquid equilibria calculations and the Virial equation was used for the prediction of vapor phase in the liquid-vapor equilibria. In the simulations were analysed the behaviour of distillate (efluent) in relation to changes in variables of this process, verifying that the behaviour was very good, mainly when compared to the one normally found in the industry. Furthermore, ciclohexane was considered as the best solvent for the separation of the water-phenol mixtures

ASSUNTO(S)

destilação resinas fenolicas

ACESSO AO ARTIGO

Documentos Relacionados