ALMEIDA FILHO, E. M.; http://lattes.cnpq.br/3494025186437682; ALMEIDA FILHO, Edvaldo Monte de.
Abstract:
In the chlor-alkali industry, the diaphragm technology is still known for being
the one that most contributes in industrial production. With asbestos diaphragms,
asbestos with polymer diaphragms, or non-asbestos diaphragm, the diaphragm is the
major component of the electrolytic cell, being responsible for the operational security
and for the process and energetic efficiency. Nevertheless, the way in which the
diaphragm is manufactured did not suffer any significant change since the first
diaphragm deposited on cathode of the electrolytic cell, around 1920. The most
significant aspect of this work is the quantitative understanding of the influence of the
effects that the variables involved in the process of deposition have over the
performance of the diaphragm in operation. The major variables involved in this process
that were considered in this work are: the specific weight of the diaphragm, the relation
between the length of the asbestos fibers and the concentrations of NaCl, NaOH and the
polymer.
With the use of well known statistics techniques, through which we obtained a
statistic mathematical model, it was possible to established quantitative relations
between these variables and the parameters that characterize the diaphragm, such as the
MacMullin number and permeability. The statistic model presented a correlation
coefficient of approximately 100% of certainty.
Following this, the parameters calculated with the help of the statistic model were
applied to an existing mathematical model which was developed specifically for the
electrolytic diaphragm cell. The mathematical model calculates the current efficiency
and the concentration of NaOH produced in the catholyte of the cell. Therefore, it was
possible to compare the calculated values of the current efficiency and the concentration
of NaOH with the values measured in a group of 34 cells in operation in an industrial
scale. The results show that, for the current efficiency, 75% of the measured data are in
accordance to the data calculated in a range of ± 5% of certainty. For the concentration
of NaOH, 74% of the measured data are in accordance to the data calculated in a range
of ± 10% of certainty. Therefore, it was possible to establish relations between the
variables involved in the process of deposition with the performance of the diaphragm
in operation in an electrolytic cell an industrial scale.