COMPUTER SUPPORTED ENGINEERING PROCESSES -
AN APPLICATION FIELD FOR COOPERATION FOR COMPUTER SCIENTISTS AND ENGINEERS
G. Paul1, N. Fröhlich1, U. Scholz 2
SPOUTED BED – CONSTRUCTIONS OF APPARATUS, HYDRODYNAMICS
AND APPLICATION
E. Piskova1, K. Kojouharov1, D. Mitev2, G. Krüger1, L. Mörl1
PARTIAL OXIDATION OF ETHANE – THE POTENTIAL
OF MEMBRANE REACTORS
F. Klose1, T. Wolff1, Chr. Hamel1, M. Alandjiyska 2, H. Weiss2,
M. Joshi3, A. Tota3, A. Seidel-Morgenstern1, 3
DEPOSITION OF PARTICLES IN LAMINAR TUBE FLOW UNDER THE INFLUENCE
OF THERMOPHORETICAL AND ELECTRICAL FORCES
L. Reime, D. Mewes
INVESTIGATION OF THE HYDRODYNAMIC PROPERTIES OF THE NEW HEAT
EXCHANGER-REACTOR APPARATUS
E. Kraychev, G. Krüger, L. Mörl
A NEW FLUIDISED BED FREEZE DRYING PROCESS
P. Tomova, M. Ihlow, W. Behns, H. Haida, L. Mörl
SPRAY COOLING HEAT TRANSFER - EXPERIMENT AND MICRO MODEL
M. Nacheva, T. Todorov, J. Schmidt
EXPERIMENTAL DETERMINATION AND THERMODYNAMIC INTERPRETATION
OF CALORIC DATA OF SEMICRYSTALLINE POLYMERS
P. Dobreva, J. J. Schröder
A NEW PACKING FOR OPERATION AT EXTREMELY LOW LIQUID SUPERFICIAL
VELOCITY
N. Kolev, B. Kralev
PLANT RISK AND SAFETY ANALYSES USING QUANTITATIVE AND SEMI-QUANTITATIVE
METHODS – A COMPARISON
U. Hauptmanns
POTENTIAL LIGHTNING IMPACT ON SAFETY SYSTEMS
V. Varbanov, U. Hauptmanns, G. Wollenberg, T. Steinmetz
ALOHA AS A USEFUL TOOL FOR SIMULATION DISPERSION OF TOXIC GASES
IN THE ATMOSPHERE
S. Tchaoushev, M. Karsheva
SYNTHESIS AND CHARACTERISATION OF TITANIUM DIOXIDE NANOPARTICLES
T. Nikolov, W. Hintz, V. Jordanova, J. Tomas
BIOSORPTION OF ACID DYE ON KUDZU (Pueraria lobata ohwi) FROM
AQUEOUS SOLUTIONS
B. Koumanova1, B. Achova1, S. Allen2
EXTRACTION OF LACTIC ACID WITH NEW SOLVENTS
M. Marinova1, G. Kyuchoukov1, J. Albet2, J. Molinier2
REMOVAL OF IRON AND ZINC BY MEANS OF DIFFERENT EXTRACTANTS
S. Zhivkova, G. Kyuchoukov
MODELLING OF SORPTION KINETICS BY BATCH EXPERIMENTS UPTAKE
CURVES FOR HEAVY METAL IONS SORPTION ON NATURAL ZEOLITE
II. COMPARISON WITH OTHER DIFFUSION MODELS
M. Kostova, I. Tsibranska, S. Nenov
MULTI-COMPONENT ADSORPTION OF METAL IONS FROM AQUEOUS SOLUTIONS
ONTO CLINOPTILOLITE, MONTMORILONITE AND THEIR MIXTURES
B. Vassileva, B. Koumanova
SHORT-TERM SCHEDULING OF CURDS PROCESSING FOR ENVIRONMENTAL
IMPACT MINIMIZATION
E. Shopova, N. Vaklieva-Bancheva
COMPARATIVE STUDY OF FLOW PROPERTIES OF COSMETIC PRODUCTS
S. Handjieva, M. Karsheva
DISINFECTION OF BIOLOGICALLY CONTAMINATED WATER SOURCES BY
IMMOBILIZED PHOTOSENSITIZERS
M. Krysteva, S. Artarsky, S. Kozhukharov
MATHEMATICAL MODELING AND OPTIMIZATION OF THE ENZYME TREATMENT
PROCESS USED IN COTTON DYEING
V. Tzotchev, K. Atanasovski
ROBUST TUNING APPROACH FOR CONVENTIONAL SMITH PREDICTOR
M. Hadjiski, E. Ivanova
ECONOMICAL RESULTS FROM THE PRIVATIZATION OF THE SHOE MANUFACTURE
N. Karev, P.Guetchev
TECHNICAL - ECONOMIC ESTIMATION FOR B?CO3 PRODUCTION
P. Guetchev, D. Nikolova, M. Georgiev
COMPUTER SUPPORTED ENGINEERING PROCESSES - AN APPLICATION
FIELD FOR COOPERATION FOR COMPUTER SCIENTISTS AND ENGINEERS
G. Paul1, N. Fröhlich1, U. Scholz 2
1Institute of Technical and Business Information Systems
Otto-von-Guericke-University Magdeburg,
P.O. Box 4120, 39016 Magdeburg, Germany
E-mail: paul@iti.cs.uni-magdeburg.de
2Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
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Received 30 September 2003
Accepted 15 October 2003
|
Computers support the work of the engineers
in many appli-cation fields. But the engineering processes are mostly very
complex. This means that before you can use computers for solving a techni-cal
problem you have to analyze these processes. That is a task for engineers
and computer scientists. We will show via two examples our approach in this
cooperation.
First example: The computer aided support during the whole product life cycle
is currently one of the most important tasks in the industry. Especially the
casting design and the work scheduling in foundries are very complicated and
their efficient solution is respon-sible for the economical survival on the
world market. This paper contains proposals for a better support of the phases
of the work scheduling and the casting design. This field of our work is embed-ded
in the topic "Information Fusion", which comprehends re-searchers
of different fields of computer science. Therefore we give a review about
the efforts of the research group. Also several aspects of the work scheduling
are explained, which contains the state of the art and proposals for software
solutions. Our results are methods for the computer aided workout of offers
associated with the elaboration of the work documents.
Second example: Subject of the second example is the devel-opment of a framework,
that allows the generation of a system for a flexible, platform-independent,
user-specific and integrated access to heterogeneous, worldwide distributed
molecular biological data sources. Furthermore the generated system must offer
some stan-dardized interfaces to support the coupling of different molecular
biological analysis tools.
Both topics should clearly indicate the efforts for developing an integrated
software solution. The partners came to the conclusion that a cooperation
is basis of the success.
Keywords: computer aided engineering, information fusion,
product life cycle, software engineering, integration framework.
SPOUTED
BED – CONSTRUCTIONS OF APPARATUS, HYDRODYNAMICS AND APPLICATION
E. Piskova1, K. Kojouharov1, D. Mitev2, G. Krüger1, L. Mörl1
1Otto-von-Guericke-University Magdeburg, Institute of Process Equipment
and Environment Technology, Chair of Chemical Apparatus Design,
Universitätsplatz 2,39106 Magdeburg, Germany
E-mail: Elka.Piskova@VST.Uni-Magdeburg.DE
2Assen Zlatarov University – Burgas, Institute of Chemical Engineering,
Prof. Jakimov Street 1, 8010 Burgas, Bulgaria
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Received 30 September 2003
Accepted 15 October 2003
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Experimental studies of the pneumatics in
different spouted bed apparatuses have been studied. The operation spouting
regimes have been determined in different spouted bed constructions and have
been compared with the conventional fluidized bed. The spouted bed techniques
are used when in the fluidised bed a homogeneous and stable flow regime is
not observed as, for example, in the cases of non-spherical particles and
in polydisperse and finedisperse systems. Consequently, original hydrodynamics
correlations to calculate the Reynolds number, corresponding to the stable
fluidization, and for the calculation of the simplex G have been proposed.
The pneumatic regimes of different constructions spouted beds are demonstrated
through ?P-u- and Re-G-Ar-diagramms.
Keywords: spouted bed, hydrodynamic, fluid flow regimes,
minimum spouting velocity.
PARTIAL
OXIDATION OF ETHANE – THE POTENTIAL OF MEMBRANE REACTORS
F. Klose1, T. Wolff1, Chr. Hamel1, M. Alandjiyska 2, H. Weiss2,
M. Joshi3, A. Tota3, A. Seidel-Morgenstern1, 3
1Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstraße
1, D-39106 Magdeburg, Germany
2Otto-von-Guericke-Universität Magdeburg, Institut für Chemie,
Postfach 4120, D-39016 Magdeburg, Germany
3Otto-von-Guericke-Universität Magdeburg, Lehrstuhl für Chemische
Verfahrenstechnik, Postfach 4120,
D-39016 Magdeburg, Germany
E-mail: klose@mpi-magdeburg.mpg.de
|
Received 30 September 2003
Accepted 15 October 2003
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The operation
of packed bed membrane reactors (PBMR) was compared to the classical fixed
bed reactor (FBR) using the catalytic oxidation of ethane over a ?-Al2O3 supported
VOx catalyst (1.4 % V) as a model reaction. Ethylene, CO and CO2 were observed
as products in both reactors. Several attractive operation modes for the PBMR
were identified, a selective oxidation mode with low oxygen-to-hydrocarbon
ratios for olefin production, a mode favoring CO production and a deep oxidation
mode for catalytic combustion. In all modes conversion in the PBMR is increased
relative to the FBR, and the selectivity is enhanced into the desired direction.
The better performance of the PBMR in all modes is caused by the interaction
of changed concentration and contact time profiles inside the reactor due
to the oxidant dosing over the membrane.
Keywords: selective oxidation of hydrocarbons, membrane reactors.
DEPOSITION
OF PARTICLES IN LAMINAR TUBE FLOW UNDER THE INFLUENCE OF THERMOPHORETICAL
AND ELECTRICAL FORCES
L. Reime, D. Mewes
Institute of Process Engineering, University of Hanover, Callinstr. 36,
30167 Hannover, Germany
E-mail: reime@ifv.uni-hannover.de
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Received 30 September 2003
Accepted 15 October 2003
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The precipitation of heated ultrafine particles
which are dispersed within hot air is investigated. The relative motion of
the particles in laminar tube flow is caused by thermophoretical, electrical
and diffusion forces. When the temperature of dispersed aerosols has to be
reduced, the movement of the particles is subject to forces from inertia,
gravitation, diffusion and friction as well as forces, which are due to strong
temperature gradients in the zone of heat transfer. Particles are accelerated
due to the thermophoretic force caused by the temperature gradients toward
the wall of the tube and deposit there. In order to prevent the deposition
of the particles they are unipolar charged. With the help of an electrical
field overlying the temperature field the particles are affected by the electrical
force which is directed toward the centre of the tube. By unipolar charging
of the particles the uniformity of their electric polarisation is understood.
Keywords: thermophoresis, electrophoresis, deposition.
INVESTIGATION
OF THE HYDRODYNAMIC PROPERTIES OF THE NEW HEAT EXCHANGER-REACTOR APPARATUS
E. Kraychev, G. Krüger, L. Mörl
Otto-von-Guericke University of Magdeburg,
Department of Chemical Apparatus Design
E-mail: e_kraichev@yahoo.com
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Received 30 September 2003
Accepted 15 October 2003
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The pressure of work fluid-air is researched
in work of one new type device heatexchanger reactor. It shows less hydraulic
resistance and less energy consumption in comparison with similar devices
that work in principle of fountain layer.
Keywords : heatexchanger, reacto-r, hydraulic resistance.
A
NEW FLUIDISED BED FREEZE DRYING PROCESS
P. Tomova, M. Ihlow, W. Behns, H. Haida, L. Mörl
Otto-von-Guericke-University of Magdeburg
Institute of Process Equipment and Environmental Technology, Post office
box 4120, D – 39016 Magdeburg, Deutschland
E-mail: plamena.tomova@student.uni-magdeburg.de
|
Received 30 September 2003
Accepted 15 October 2003
|
The presented study describes an alternative
atmospheric freeze drying process which can be used to achieve high quality
dried biological products. This is a fluidized bed freeze drying process which
combines the advantages of the fluidized bed (good heat and mass transfer)
with the possibility of adsorption drying.
The experimental investigations are realized in a fluidized bed plant with
a nominal diameter of 100 mm. The plant is built in an industrial freezer
container providing the opportunity of drying at low temperatures.
The feasibility of atmospheric freeze drying process was demonstrated with
the model material ?-Al2O3 and a specific biological product. The water vapour
adsorption isotherms of the product serve as the basis of theoretical considerations.
The needed adsorption isotherm of the model material was measured by desiccator
method at –1°C and described by means of Brunauer-Emmet-Teller (BET)
and Guggenheim-Anderson-de Boer (GAB) models. The GAB model showed better
conformity with the experimental results.
Keywords: atmospheric freeze drying, fluidized bed, adsorption
isotherm.
SPRAY
COOLING HEAT TRANSFER - EXPERIMENT AND MICRO MODEL
M. Nacheva, T. Todorov, J. Schmidt
University of Magdeburg, Institute of Fluid Dynamics and Thermodynamics,
P. O. Box 4120, Universitätsplatz 2,
D – 39016 Magdeburg, Germany
E-Mail: mariya.nacheva@student.uni-magdeburg.de
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Received 30 September 2003
Accepted 15 October 2003
|
A quasi-stationary method is presented for
the estimation of the heat transfer coefficient (HTC) for film boiling on
a hot metal plate at temperatures above the Leidenfrost temperature. Different
kinds of water nozzles were used for the experiments. Parameters measured
include: the mass flux, the spray parameter - volume mean diameter and mean
velocity of the droplets. The influence of the mass flux and the spray characteristics
on HTC was investigated.
The heat transfer experiments were realized with a thin, electrically heated
Inconel metal sheet. The HTC was calculated from the temperature fields of
the dry metal sheet side measured by means of IR-Thermography. The mass flux
of the water was measured by means of patternator and a Phase-Doppler-Analyser
(PDA) has been used to determine the spray characteristics.
First ideas of a micro-model for the theoretical description of the measured
results are presented.
Keywords: spray cooling, film boiling, Leidenfrosttempera-ture,
heat transfer.
EXPERIMENTAL
DETERMINATION AND THERMODYNAMIC INTERPRETATION OF CALORIC DATA OF SEMICRYSTALLINE
POLYMERS
P. Dobreva, J. J. Schröder
University of Hannover, Institute for Thermodynamics,
Callinstr. 36, 30167 Hannover, Germany
E-mail: dobreva@ift.uni-hannover.de
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Received 18 September 2002
Accepted 22 October 2002
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Differential scanning calorimetry (DSC)
is a commonly used method to determine thermal properties of polymers. On
this basis, the caloric behaviour of such polymers as polyethylene terephthalate
(PET), polybuthylene terephthalate (PBT) and polyoxymethylene (POM) is examined
experimentally as a function of the previous heat treatment. Measurements
by temperature modulated DSC (TMDSC) show the frequency dependent heat capacity
of these polymers in the glass transition region after isothermal crystallization.
The baseline heat capacity values are obtained with a two-phase model (crystalline-amorphous
combination). The significance of a rigid amorphous fraction which is noncrystalline
but does not participate in the glass transition is shown.
Two main topics in the study of isothermal crystallization kinetics are highlighted:
the effects of the crystallization temperature and the crystallization time.
The interdependence of the melting behaviour of the semicrystalline polymers
and the extent of secondary crystallization is described. Models found in
the literature for the interpretation of thermal properties of semicrystalline
polymers are presented in order to find a lead towards a more fundamental
modelling. Results of own and published experiments are discussed on this
basis.
Keywords: calorimetry, semicrystalline polymers, crystallization,
glass transition.
A
NEW PACKING FOR OPERATION AT EXTREMELY LOW LIQUID SUPERFICIAL VELOCITY
N. Kolev, B. Kralev
Institute of Chemical Engeering, BAS
Str.”Acad. G. Bonchev”, block 1031, Sofia 1113
E-mail: kolev@bas.bg
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Received 30 September 2003
Accepted 15 October 2003
|
Former investigations have shown that a
packing made of separate low horizontal lamellas is especially effective for
mass transfer at extremely low liquid superficial velocity. The construction
of the packing from single lamellas is a difficult and expensive task. That
is why the aim of the present work is to investigate a new type of easy to
make lamella packing constructed of single lamellas stamped in sheets of sintered
PVC. The results about the effective surface area of the packing covered with
a moving liquid at different flow-rates of the irrigating liquid and two constructive
types of the packing are presented.
Keywords: packed-bed column, new packing, effective surface,
low liquid superficial velocity.
PLANT
RISK AND SAFETY ANALYSES USING QUANTITATIVE AND SEMI-QUANTITATIVE METHODS
– A COMPARISON
U. Hauptmanns
Otto-von-Guericke-Universität Magdeburg
Fakultät für Verfahrens- und Systemtechnik
Institut für Apparate- und Umwelttechnik
Abteilung Anlagentechnik und Anlagensicherheit
E-mail: ulrich.hauptmanns@vst.uni-magdeburg.de
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Received 30 September 2003
Accepted 15 October 2003
|
Motivated by the new Seveso directive and
the Safety Integrity Level Classes there is an increased interest in risk
analyses for process plants. The procedure for performing complete risk assessments
is outlined. The steps to be performed and the input information requirements
are given. It becomes clear that the performance of in-depth analyses may
be too onerous in many cases. Therefore two simplified approaches for assessing
risk, namely LOPA and SQUAFTA, are presented. Their respective differences
and points in common are explained. Their advantages as well as their drawbacks
are discussed.
Keywords: Seveso directive, SIL classes, risk assessment,
LOPA, SQUAFTA.
POTENTIAL
LIGHTNING IMPACT ON SAFETY SYSTEMS
V. Varbanov, U. Hauptmanns, G. Wollenberg, T. Steinmetz
Interference voltages, caused by external
electromagnetic fields, for instance those from lightning strike, or caused
by crosstalk in wires in low-voltage power installations are of particular
concern especially when safety systems are involved.
In the paper voltages caused by a nearby lightning strike in a buried low-voltage
power installation are investigated. Two possible cases are studied, namely
when lightning strikes close to the line and when it strikes directly over
the line. In the first case interference voltages are caused by radiated electromagnetic
field and for this case Agrawal’s approach [6] is used to find these
voltages. In the second case interference voltages are caused mainly from
crosstalk between the conductors in the cable bundle.
For detecting the fields under the ground, caused by a lightning strike, a
computer code was written based on equations proposed by Cooray [5]. This
code determines fields in the frequency domain as well as in the time domain,
however for our purposes only fields in the time domain are used. These are
then used as an input for the computer program “CableMod” for
simulating the excited line. “CableMod” is a simulation program
that analyses complex cable structures. For the second case current, which
flows at the base of a lightning channel is used as input parameter for the
“CableMod” program.
As results, voltages at the end of the line are presented. These would then
impact the electronic part of a safety system.
Keywords: electromagnetic compatibility, lightning stroke,
complex underground cable systems.
ALOHA
AS A USEFUL TOOL FOR SIMULATION DISPERSION OF TOXIC GASES IN THE ATMOSPHERE
S. Tchaoushev, M. Karsheva
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: tchaoushev@uctm.edu,
mik@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
Major reasons for accidents in the chemical
industry are different “bottle-necks” of technological processes
as well as potential hazards in the transportation of raw materials and chemical
products to intermediate and end users.
Last decades of XX century were marked by intensive development of computerized
technologies in the human development. In the chemical industry this can be
summarized as use of specialized software products (simulators) for evaluation
of consequences from release of toxic fluids in the atmosphere and its impact
on the environment and human beings.
The aim of this work was the numerical simulation of harmful gases release
at real conditions in the region of Sofia. The programme ALOHA (Aerial Location
Of Hazardous Materials) was applied as a simulation tool. Two examples for
the purposes of education were developed.
Keywords: dispertion, release of toxic substances, simulation.
SYNTHESIS
AND CHARACTERISATION OF TITANIUM DIOXIDE NANOPARTICLES
T. Nikolov, W. Hintz, V. Jordanova, J. Tomas
Otto-von-Guericke University of Magdeburg, Me-chanical Process Engineering,
P.O. Box 4120,
D-39106 Magdeburg, Germany
E-mail: Tsvetan.Nikolov@student.uni-magdeburg.de
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Received 30 September 2003
Accepted 15 October 2003
|
Nanosized titanium dioxide was prepared
on a laboratory scale by precipitation of titanium tetra isopropoxide (TTIP)
in dilute nitric acid, followed by a re-dispersion reaction of the spontane-ously
formed titanium dioxide suspension. Nanosized particles of a mean size from
10 to 30 nm were obtained within 24 hours. The par-ticle sizes of titanium
dioxide (from 1000 microns after precipitation down to 10 nm) were measured
by dynamic light scattering and la-ser diffraction spectroscopy to get kinetic
information of the re-dispersion process.
Dry porous titanium dioxide aggregates were obtained by freeze drying and
calcination. Then the powder was subsequently physically characterized by
particle density, size distribution, spe-cific surface area, pore size distribution
and inner aggregate poros-ity. The BET specific surface areas were determined
from nitrogen adsorption data ranging from 85 to 185 m2/g for the untreated
pow-der. The Barrett - Joyner - Halenda (BJH) method was used to de-termine
the pore size distribution. The isolated titanium dioxide ag-gregates were
mesoporous with pore sizes from 2 to 4 nm. The inner aggregate porosity of
0.3 was obtained.
The reversible re-dispersion (deagglomeration, peptization) and the agglomeration
(coagulation) process of sol-gel-synthesis of titanium dioxide nanoparticles
were modelled and simulated by population balance equations with a special
approach for the kinet-ics. The equilibrium reaction constant, average agglomeration
and dispersion rate constant were calculated for a real polydisperse sys-tem
on the basis of the particle and aggregate size distribution ob-tained by
laser diffraction and dynamic light scattering.
Keywords: titanium dioxide nanoparticles agglomeration kinetics,
population balance model, nanopowder characterisation.
BIOSORPTION
OF ACID DYE ON KUDZU (Pueraria lobata ohwi) FROM AQUEOUS SOLUTIONS
B. Koumanova1, B. Achova1, S. Allen2
1University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: bogdana@uctm.edu
2The Queen’s University of Belfast,
School of Chemical Engineering,
David Keir Building, Stranmillis Road, Belfast, UK
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Received 30 September 2003
Accepted 15 October 2003
|
Dyestuff production units and dyeing units
have a pressing need for economical pretreatment for colour in the effluents.
The effectiveness of adsorption for dye removal from wastewaters had made
it an ideal alternative to other expensive treatment options. Kudzu (Pueraria
lobata ohwi), a vine native to Eastern Asia, was determined to be an effective
adsorbent for the removal of heavy metals ions from aqueous solutions. In
this study the use of kudzu as a low-cost adsorbent for the removal of acid
dye Erionil Marine Blau from aqueous solutions has been investigated. The
experiments were held at various initial dye concentrations, quantity of adsorbent
and agitation using batch adsorber. High extent of dye’s uptake was
obtained (93 %). The adsorption followed Freunlich isotherm better than the
Langmuir and the isotherms parameters have been calculated as well. A comparison
of the rate constants and equilibrium capacity calculated by the pseudo-first
and pseudo-second order kinetic models proves the applicability of the pseudo-second
order equation. Intraparticle diffusion in the pore structure is proposed
as a mass transfer mechanism. A diffusion rate parameter, k, is proposed and
is correlated with possible system variables.
Keywords: acid dye, low-cost adsorbent, adsorption isotherms,
intraparticle diffusion, sorption dynamics.
EXTRACTION
OF LACTIC ACID WITH NEW SOLVENTS
M. Marinova1, G. Kyuchoukov1, J. Albet2, J. Molinier2
1Institute of Chemical Engineering, BAS,
Acad. G. Bonchev Str., Bl.103, 1113 Sofia, Bulgaria,
E-mail: pertrex@bas.bg
2Equipe Génie Chimique, LCA UMR 1010 INRA, INP - ENSIACET,
118, Route de Narbonne, 31077 Toulouse, France
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Received 30 September 2003
Accepted 15 October 2003
|
A study on the extraction of lactic acid
by means of a mixed and a modified extractants was carried out. The mixture
of a tertiary amine and a quaternary ammonium salt is more efficient than
the individual constituents and the carbonate form of Aliquat 336 is more
suitable for lactic acid extraction than the classical chloride one.
Keywords: mixed extractant, modified extractant, lactic acid,
tri-n-octylamine, Aliquat 336.
REMOVAL
OF IRON AND ZINC BY MEANS OF DIFFERENT EXTRACTANTS
S. Zhivkova, G. Kyuchoukov
Institute of Chemical Engineering, BAS,
Acad. G. Bonchev Str., bl.103, 1113 Sofia, Bulgaria,
E-mail: pertrex@bas.bg
|
Received 30 September 2003
Accepted 15 October 2003
|
The removal and separation of iron and zinc
from waste industrial hydrochloric acid solutions was studied. The experiments
were carried out using various solvents, involving different extraction mechanisms
- solvating, anion-exchange, kation-exchange, bifunctional. Mixtures of these
extractants have been also used. The extraction properties of these extractant
mixtures toward iron and zinc, the effect of used modifiers and diluents have
been also investigated.
Keywords: zinc, iron, extraction, modifier, mixed extractant.
MODELLING
OF SORPTION KINETICS BY BATCH EXPERIMENTS UPTAKE CURVES FOR HEAVY METAL IONS
SORPTION ON NATURAL ZEOLITE
II. COMPARISON WITH OTHER DIFFUSION MODELS
M. Kostova, I. Tsibranska, S. Nenov
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: miki@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
In Part I an analytical solution based on
the Linear Driving Force Model for a rectangular equilibrium was derived.
In the following Part II an experimental verification of the model equation
is presented. Sorption of Pb2+ ions with Na+ modified form of natural clinoptilolite
from the Eastern Rhodopes in Bulgaria was performed. Simulation of the experimental
uptake curves with other diffusion models is also presented – the biporous
and the monoporous diffusion models, as well as the solid phase diffusion
models were used in the calculations. The results with the monoporous diffusion
model agree with the experimentally observed kinetics and are closely related
to those of the analytical solution from Part I. The biporous diffusion models
does not describe the observed effect of the particle size on the kinetic
curves. A possible cause of this disagreement is probably due to the strong
influence of the “place” of the equilibrium condition on the modelled
sorption kinetics.
Keywords: ion exchange, sorption, zeolite, heavy metal ions,
mathematical modelling.
MULTI-COMPONENT
ADSORPTION OF METAL IONS FROM AQUEOUS SOLUTIONS ONTO CLINOPTILOLITE, MONTMORILONITE
AND THEIR MIXTURES
B. Vassileva, B. Koumanova
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: bogdana@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
The adsorption of NH4+, Ca2+, Zn2+, Cu2+
and Pb2+ from model aqueous solutions onto clinoptilolite, montmorilonite
and their mixtures has been investigated. The experiments were carried out
in a glass column and constant rate 5 ml s-1. Samples were taken regularly
and were analyzed potentiometrically. Four mixtures of clinoptilolite and
montmorilonite in ratio 1:1; 3:1; 4:1 and 5:1 have been studied. Comparing
the results for ions uptake it was established that the mixed sorbents are
very effective in case of NH4+, Zn2+ and Pb2+ and their removal was not influenced
by the other ions in the solution. Higher extent of Ca2+and Cu2+ removal from
the solution was obtained in the presence of NH4+.
Keywords: multi-component adsorption, metal ions, clinoptilolite,
montmorilonite.
SHORT-TERM
SCHEDULING OF CURDS PROCESSING FOR ENVIRONMENTAL IMPACT MINIMIZATION
E. Shopova, N. Vaklieva-Bancheva
Institute of Chemical Engineering – BAS
“Acad. G. Bontchev” Str., Bl.103, 1113 Sofia, Bulgaria,
E-mail: eshopova@mail.bg
|
Received 30 September 2003
Accepted 15 October 2003
|
This study considers a short-term scheduling
in curds processing for environmental impact minimization. The aim is to find
the best tradeoff between production requirements and the environmental impact
assessed by BOD “generated” in the whole batch plant. The problem
is formulated as MINLP. The contribution of the inherent losses in the GBOD
is taken into account.
Keywords: short term schedules, MINLP, dairy industry, global
BOD minimization.
COMPARATIVE
STUDY OF FLOW PROPERTIES OF COSMETIC PRODUCTS
S. Handjieva, M. Karsheva
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: sneja@uctm.edu; mik@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
A comparative study of rheological behaviour
of cosmetic products: shampoos and douche gels was done. It was found that
all the products are non-Newtonian fluids and their flow behaviour could be
described by power-law rheological model. It was found that all products with
basic compound hydroxyethylcellulose exhibited a shear-thinning properties,
and those with basic compound polyvinyl alcohol depending on the type and
the quantity of surfactant could be also dilatant. The dependence of flow
properties of the cosmetic gels on the electrolyte contents as well as on
the contents of aesthetic compounds was also investigated. It was found that
the presence of boric acid in the compositions with polyvinyl alcohol leads
to complex compounds which followed by neutralization in the case of the douche-gels
results in change of the flow behaviour from the dilatant to pseudoplastic.
The influence of the temperature on the rheological parameters of the cosmetic
gels was also studied. The Arrhenius law describes quite satisfactory the
temperature dependence of the consistency index K. The influence of the temperature
on the flow index n was found to be negligible. The data obtained could be
used in calculation of power requirements for transport and mixing of such
compositions.
Keywords: rheology, shampoos, douche gels, dependence on
composition and temperature.
DISINFECTION
OF BIOLOGICALLY CONTAMINATED WATER SOURCES BY IMMOBILIZED PHOTOSENSITIZERS
M. Krysteva, S. Artarsky, S. Kozhukharov
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: krysteva@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
It is well known, that water is a favorable
medium for the development of microorganisms abundance. This could be the
reason for propagation of different infections. From this point of view water-reservoirs
undergo disinfection. Discovering the photomicrobicidal activity of some compounds,
is an evidence for the variety of singlet oxygen applications, which is generated
by dye substances, known as “photosensitizers”. A typical example
is the photochemical therapy of cancer, etc.
The aim of the present work is to investigate immobilized photosensitizes
as a potential tool for photomicrobicidal disinfection. The Zn(II)-phthalocyanine
was immobilized on a previously prepared membrane from chitosan by means of
chemical bonds. The Rose bengale was immobilized by entrapment in the structure
of a triacetylcellulose membrane. The contact between water containing microorganisms
and immobilized photosensitizers, was ensured by a special equipment with
light – source. This phenomenon was studied in model solutions, containing
certain quantities of Esherichia coli and Pseudomonas aeroginosa. Usually
these microorganisms occur in the water reservoirs. They may cause a large
number of diseases when their concentration increases. It was established
that the Zn(II)-phthalocyanine membranes have a complete bactericidal effect
against Esherichia coli for 140 minutes, while for Pseudomonas aeroginosa
it was found that liquidation was obtained even for 180 minutes. The same
effect was obtained in the case with Rose bengale.
Keywords: photo-disinfection, water, photo-sensitizers, phthalocyanine,
Rose bengale.
MATHEMATICAL
MODELING AND OPTIMIZATION OF THE ENZYME TREATMENT PROCESS USED IN COTTON DYEING
V. Tzotchev, K. Atanasovski
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: tzochev@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
In this article results of the investigation
of the enzyme treatment process used in cotton dyeing are presented. The main
purpose of this investigation is to optimize the process. A useful tool for
this is the Design of Experiments and particularly the Response Surface Methodology.
The performance characteristics that are investigated are the strength of
the cotton fiber and its mass. The most important factors for the process
are 1) temperature ; 2) pH; 3) enzyme concentration and 4) time of treatment
. A two factors face-centered central composite design is used. All experiments
are performed at constant temperature and pH – 5. The regions of experimentation
for the two other factors are time , and concentration . Adequate second-order
regression models are obtained. Generating contour plots and then overlaying
them optimal conditions are found. Joint optimization using overall desirability
is used as well.
Keywords: cotton dyeing, design of experiments, regression
models, response surface methodology, optimization, contour plot, desirability.
ROBUST
TUNING APPROACH FOR CONVENTIONAL SMITH PREDICTOR
M. Hadjiski, E. Ivanova
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: hadjiski@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
Intelligent control systems schemes take
wider place in contemporary technological applications. The tendency is that
they will gradually replace the conventional controllers. Still, the control
algorithms like PID will always be the heart of process control. Their smartness,
simplicity and effectiveness assign them a position in a variety of practical
applications.
The conventional Smith control algorithm is one of the approaches that aim
to supply a decision for the many complicated problems of control of plants
with a large time delay. The considerable deterioration of the system quality
by vagueness and parametrical uncertainty is the main reason why the conventional
Smith control algorithm will be displaced from many practical applications
by more effective control approaches. Often in their essence is the idea of
control in open loop schemes. In such cases the accumulated error in the control
signal that is determined by the delayed system performance is avoided.
In the present paper one approach for robust tuning of a conventional Smith
predictor that will guarantee quality in system performance is considered.
The main attention is given to the performance of the tuning procedure in
cases with different levels of noise in the system.
Keywords: time delay, conventional Smith predictor, robust
tuning approach.
ECONOMICAL
RESULTS FROM THE PRIVATIZATION OF THE SHOE MANUFACTURE
N. Karev, P.Guetchev
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: pgechev@uctm.edu
|
Received 30 September 2003
Accepted 15 October 2003
|
Cardinal changes in the bulgarian economy
connected with the transition from a control planning to market economy have
been appeared after 1989. As a result of this, the shoe enterprises have to
work under quite different conditions. Nowadays almost 100 % of the shoe branch
firms and 92 % of their capital are private. The analysis of the basic economic
indices has shown that the shoe production, efficiency of labour as well as
the number of employee are fallen drastically. These changes have led to the
decrease of the relative part of the branch in the bulgarian industry and
will have negative sequences for its development.
Keywords: shoe manufacture, privatization, economic indices,
economic consequences.
TECHNICAL
- ECONOMIC ESTIMATION FOR B?CO3 PRODUCTION
P. Guetchev, D. Nikolova, M. Georgiev
University of Chemical Technology and Metallurgy,
8 Kl. Ohridski, 1756 Sofia, Bulgaria
E-mail: Pgechev@hotmail.com
|
Received 30 September 2003
Accepted 15 October 2003
|
The business activity of the chemical companies
requires constant innovation of their products and capital investment.
The technology for BaCO3 production suggests the use as a raw material of
barite concentrate, a product from the metallurgical company “Kremikovtsi”.
In this way not only economical but also ecological problems may be solved.
In the work are given basic parameters of the technology, but special attention
is paid to economical issues – total product cost, profit, capital investment.
Because of the high level of technical completeness and economical efficiency,
the technology is orientated to potential investors.
Keywords: BaCO3 production, economic efficiency, total product
cost, profit.
