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Modeling of Esterification of Acetic Acid with Ethanol Coupled with Pervaporation Using Cross Linked Pva Membranes
--
N Sirisha, S V Naidu, S Subba Rao and
P Mohan Kumar Yadav
The pervaporation catalytic membrane reactor is one in which the membrane Poly Vinyl Alcohol (PVA)
is cross-linked with catalyst Maleic acid (PVAMA) and Citric acid (PVACA), which is used for the
separation of one or more of the products formed, thereby increasing the conversion. In this study, theoretical models
for both esterification and pervaporation aided esterification are developed. The model equations are
validated with the available experimental data. The performance of pervaporation reactor for the esterification
reaction of acetic acid with ethanol is studied. The study includes the optimization of several process variables
such as temperature (T), initial mole ratio of ethanol to acetic acid
(Ro) and the ratio of effective membrane area
to volume of the reacting mixture (S/V) on water concentration.
© 2011 IUP. All Rights Reserved.
Mass Transfer at the Confining Wall
of an Electrochemical Cell in the Presence
of Twisted Tapes
-- B S Subramanyam, M S N Murty,
B Surendra Babu and K V Ramesh
Mass transfer coefficients between a liquid and column wall of an electrochemical cell were computed
from the limiting current measurements made at the point electrodes fixed flush with the inner surface of
the column wall. Twisted tapes of varying width and pitch served as insert promoter elements. The
employed test section, which acted as electrochemical cell, consisted of a perspex tube of 6.73 cm inner diameter.
34 point electrodes were fixed to the test section. The liquid used was an electrolyte belonging to the
Ferri-Ferrocyanide redox system. Addition of Carboxy Methyl Cellulose (CMC) sodium sulphate increased
the viscosity of the solution. Analysis of the data obtained revealed that an increase in tape width increased
the mass transfer coefficient. A decrease in mass transfer coefficient was observed with increase in tape
pitch and CMC concentration. The data were correlated using regression analysis.
© 2011 IUP. All Rights Reserved.
Momentum Transfer in Circular Conduit with Coaxially Placed Entry Region
Twisted Tape as Swirl Promoter
--
V Nageswara Rao, P Rajendra Prasad and N Chitti Babu
The effect of coaxially placed entry region twisted tape as turbulence promoter on momentum transfer rates
in forced convection flow of electrolyte were studied in an circular conduit. The friction
correlation was based on the law of wall similarity. The study covered a wide range of variables such as the flow rate of
electrolyte, geometric parameters such as pitch of the tape
(TP) which varied from 0.02 m to 0.12 m,
length of the tape (TL) which varied from 0.14 m to 0.22 m and width of the tape
(TW) which varied from 0.01 m to 0.03 m. The
results revealed that the friction factor increased with increase
in TL and TW and decreased with increase in TP. Momentum transfer rates were analyzed with momentum transfer roughness function in place of
friction factor (f) and roughness Reynolds number + ( Re+) in place of Reynolds number
(Re). The following correlation was reported out of the study: R(h+) =
18.581(Re+)_0.109 (f1)0.374 (f2)0.001 (f3)0.019. The
correlation which was developed can be extended to a wider range of variables by virtue of law of wall similarity.
© 2011 IUP. All Rights Reserved.
Comparative Study on the Adsorption Kinetics of Cd
(II) and Cu (II) Metal Ions
Onto Eggshell Powder
-- P Kalpana, K China Malakondaiah,
D A Naidu, P King and V S R K Prasad
The removal of Copper (Cu) (II) and Cadmium (Cd) (II) ions from aqueous solutions by adsorption on
hen eggshells was investigated depending on the pH, sorbent dosage, contact time, initial metal
concentration and sorbent size. The optimum values of pH were found to be 6 for both the metal ions. The
equilibrium contact time was determined to be 60 m for the adsorption of Cu (II) ions and 90 m for the adsorption of
Cd (II) ions. From the initial concentrations, the constant for the Freundlich, Langmuir and Redlich
Peterson isotherms was calculated at room temperature. It was found that biosorption of Cd (II) and Cu (II) ions
onto the eggshell were better suitable to Langmuir, than Freundlich or Redlich Peterson model. The
maximum biosorption capacity of hen eggshell for Cd was 34.39 mg/g and 32.02 mg/g for Cu. The kinetic
experimental data were properly correlated with the second order kinetic model for both metal ions. The present
data confirms that hen eggshells may be used as efficient biosorbent for the removal of Cd (II) and Cu (II) ions
from aqueous solution.
© 2011 IUP. All Rights Reserved.
Liquefied Petroleum Gas: Fire and Explosion
Hazards, Mathematical Models
and Safe Storage
-- Kailas L Wasewar and M Siva Kumar
There are numerous hazards associated with chemical processing, especially with highly
inflammable substances like Liquefied Petroleum Gas (LPG). The process safety engineer plays a pivotal role in
identifying the associated hazards, areas of influence and their mathematical representation to ensure that the
risks involved in these hazards can be reduced to acceptable levels through the application of
engineering principles and proven engineering practice. In modern hydrocarbon plants, LPG is widely stored in
various vessels. The fire and explosion hazards of these objects are extremely high. This has been confirmed by
a series of accidents involving fires and explosions that have taken place around the world. In the
present paper, the fire and explosion hazards associated with the LPG are described with the most
appropriate mathematical models. Safe storage options which avoid the chances of these explosion hazards are
also reviewed.
© 2011 IUP. All Rights Reserved.
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