Tesis
Separação adsortiva de misturas etanol-água por processo PSA.
Fecha
2005-03-02Registro en:
MOREIRA, Alexandre Marques. Separação adsortiva de misturas etanol-água por
processo PSA.. 2005. 121 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2005.
Autor
Moreira, Alexandre Marques
Institución
Resumen
The ethanol is one of the most well-known and diffused fuels sources in
nowadays, therefore the domain of its technology has a great importance to the producer
countries. Beyond it is in general, lesser expensive than the major part of the
petrochemical fuels, the ethanol has its origin in the renewable sources that becomes
Brazil in a world power on its production.
From these facts the present work consists on the application of the PSA
(Pressuring Swing Adsorption) process on the ethanol purification, from ethanol-water
mixtures with compositions that simulate ethanol concentrations of the final steps of
distillation process. To get this ethanol purification it was used the zeolite 3A as
adsorbent, which adsorbed the water of the mixtures in a pressured bed.
The PSA process were composed by four steps: The first was the
adsorption bed pressurization, at high temperature, with a given ethanol-water mixture;
the second was the residence of the fed mixture for a given time in the bed to recover
the ethanol; the third was the depressurisation of the bed to the ambient pressure, and
the fourth was the regeneration of the adsorbent by vacuum, to recover the water
adsorbed.
The process variables studied in this work were adsorption pressure,
adsorption time and initial concentration, being evaluated their influences on the
response variables fluid phase enrichment, ethanol recover and process productivity,
were studied, through a factorial planning. These influences were described by
polynomial models, in which were applied the statistical tests F and R2, to analyse the
quality of the obtained adjustments. The obtained models were validated by extra
experiments done out of the factorial planning.
The influences of the process variables over the response variables were
analysed through response surfaces generated by the obtained polynomial models.
The response variables were individually optimized with the using of
search programs, which sought the best results over the polynomial models and the
process variable ranges. The individual optimum results of the response variables were
found, at the same way, the values of the process variables that produced these results.
The response variables were also optimized together simultaneously. To
obtain these optimizations search programs, with the same logic of the used in the
individual optimization, were used with the multiresponse method, which made possible
the obtainment of the optimum values of response variable arrangements in pairs and all
of these together simultaneously. These optimum values to these arrangements were
obtained, at the same way that the process variable values, which correspond to these
optimizations.
The enrichment obtained results showed high values and low variations
with the increase of the adsorption time. At the same way, the adsorption pressure
influences the enrichment significantly only with low values of the initial concentration
and adsorption time. The enrichment had also an increase of its value and a decrease of
its variation, with the increase of the initial ethanol concentration.
The ethanol recover showed without significantly influence with the
variations of the adsorption time and the adsorption pressure, however had an increase
with the increase of the initial concentration.
The productivity profiles showed that they were influenced by the three
process variables. The increase of the productivity was detected with the increase of the
initial concentration and the increase of the adsorption pressure. The productivity
decreased with the increase of the adsorption pressure.
The obtained results to the simultaneous optimizations showed that the
productivity had a predominant influence over the other response variables optimized
with these. At the same way, the recover values were not influenced by the optimization
of the others response variables. Also it was seen that the enrichment optimization
impaired the productivity results, in spite of the reverse fact had not been verified.
To illustrate the generated results of the optimizations, the next values
were obtained to the optimization of the three response variables simultaneously: 94.7%
to the fluid phase enrichment, 82.5% to the ethanol recover and 5.14g.g-1.h-1 to the
process productivity, with the values of the process variables of 10 bar to the adsorption
pressure, 90% to the initial ethanol concentration and 2.0 minutes to the adsorption
time.