Download Buletin Stiintific - UPB - Seria C - numar 1 - 2010

U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
Contents
Sary Awad, I-A. Basa, M. Paraschiv, S. Kumar, M. Tazerout
Characterisation and optimisation of biodiesel’s production from waste cooking
oil
3
Andrei Damian, Andrei-Mugur Georgescu
Modelling of the wind effect on a double-tracking PV platform
13
Cosmin Mărculescu, Adrian Badea, Tiberiu Apostol
Two-stage gasification process of solid organic compounds
21
Cora Bulmău (Gheorghe), Cosmin Mărculescu, Adrian Badea, Tiberiu Apostol
Pyrolysis parameters influencing the bio-char generation from wooden biomass
29
Michel Feidt
Energy efficiency and environment
39
Petre Blaga, Horia Necula, Constantin Ionescu
The increase of energy efficiency through the conversion of a thermal power plant
into a cogeneration plant
53
André Lallemand, Lingai Luo, Renaud Gicquel
Comparative study of heat production by cogeneration or heat pump
65
Roxana Patraşcu, George Darie, Eduard Minciuc, Cristian Răducanu, Adina Stanculea
Comparative analysis of production and processing of glassware and technical
glass
73
Gheorghe Cârţină, Gheorghe Grigoraş, Elena-Crenguţa Bobric
Opportunities to conserve energy right from distribution installations
81
Florin Ionescu, Constantin Bulac, Ioana Pisică, Ion Tristiu, Lucian Toma
An evolutionary programming application to optimal reactive power dispatch
91
Alberto Borghetti, Mauro Bosetti, Carlo Alberto Nucci, Mario Paolone
Parameters identification of a power plant model for the simulation of islanding
transients
101
Cristian Dincă, Adrian Badea, Tiberiu Apostol
Life cycle impact assessment of fossil fuels
115
Ion Melinte, Mihaela Bălănescu, George Darie, Carmencita Constantin
New methods for the assessment and the reduction of the co2 emissions in iron and
steel processes and thermo-electric power stations, based on an integrated
approach
127
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
Elena David, I. Ştefanescu, A. Armeanu
Economical CO2 capture from fossil flue utilization
135
Iosif Prodea, Cristina Alice Mărgeanu, Andrei Rizoiu, Ilie Prisecaru, Nicolae Dănilă
Void reactivity reduction in CANDU reactors using burnable absorbers and
advanced fuel designs
145
Ilie Prisecaru, Iulian Pavel Niţă, Daniel Dupleac
Influence of preheater loss in regeneration efficiency on the secondary circuit
153
Viorel Şerban, Ilie Prisecaru
Analysis of some critical points that may influence Cernavoda NPP nuclear safety
during an earthquake and solutions to increase the safety margin
163
Florin Munteanu, Ciprian Nemeş
Real efficiency of intelligent switching of high voltage circuit-breakers
173
Marian Costea, Bogdan Nicoară
Influence factors on the transmitted overvoltages from high voltage to low voltage
networks
183
Cristian Lăzăroiu, Dario Zaninelli
DC arc furnace modelling for power quality analysis
191
Florin Ciauşiu, Mircea Eremia
Steady-state stability limit identification for large power systems
201
Ioana Pisică, Petru Postolache
Rough set theory and its applications in electrical power engineering. A survey
211
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
CHARACTERISATION AND OPTIMISATION OF
BIODIESEL’S PRODUCTION FROM WASTE COOKING OIL
Sary AWAD, I-A. BASA, M. PARASCHIV, S. KUMAR, M. TAZEROUT
We studied the transesterification of two types of waste cooking oil (WCO),
with methanol and ethanol using NaOH. Also the physical characteristics of
produced biodiesel were studied and compared to the European standard EN 14214.
The WCO used in this study was collected from the École des Mines de Nantes
university’s restaurant. We used to search the optimum conversion ratio, combining
four variables: temperature of reaction, catalyst amount, time of reaction and
alcohol to oil molar ratio, the effect of free fatty acid content in the oil and the type
of alcohol used in the reaction were also studied.
Keywords: biodiesel, waste cooking oil, transesterification, biodiesel
characterization
MODELLING OF THE WIND EFFECT ON A DOUBLETRACKING PV PLATFORM
Andrei DAMIAN, Andrei-Mugur GEORGESCU
The objective of the paper is the assessment of the wind load applied to a real
photovoltaic (PV) platform installed on a site situated in Brasov, Romania. The
platform has a double-tracking axis mechanism, which allows the rotation of the
platform depending on the sun position, in order to gather the maximum solar yield
to produce electricity.
The 3D numerical investigations were performed by using the COMSOL
Multiphysics software. The results were represented graphically, in terms of
pressure fields along the PV platform disk, depending on the seasonal and daily
angle of inclination relatively to the two rotation axes of the platform.
Keywords: photovoltaic platform, PV, wind load, COMSOL Multiphysics
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
TWO-STAGE GASIFICATION PROCESS OF SOLID
ORGANIC COMPOUNDS
Cosmin MĂRCULESCU, Adrian BADEA, Tiberiu APOSTOL
The research focused on two-stage high temperature gasification under
steam atmosphere, at atmospheric pressure conducted organic solid compounds for
maximum energy potential recovery with respect to product transformation during
the process and its influence on final results. The work aimed to establish the
dependence of second gasification stage on the first devolatilization one together
with the connection: process parameters – reactions kinetics. The approach was
justified by the products different physical-chemical structures and carbonization
parameters: pressure, temperature and residence time influence on the char
formation and its physical characteristics. Furthermore the second reason for this
approach was the advantages of two-stage pyro-gasification process, compared to
direct gasification one.
Keywords: pyrolysis, gasification, kinetics, solid fuel
PYROLYSIS PARAMETERS INFLUENCING THE BIO-CHAR
GENERATION FROM WOODEN BIOMASS
Cora Bulmău (GHEORGHE), Cosmin MĂRCULESCU, Adrian BADEA, Tiberiu
APOSTOL
Recently much research has been investigated on identifying suitable
biomass species, which can provide high-energy outputs, to replace conventional
fossil fuels. This paper reports an approach for increasing the yield of bio-char
production from pyrolysis with respect to process conditions. The analyzed material
was cherry sawdust. The experiments were conducted for pyrolysis temperature
between 450ºC and 800ºC. The experimental study focused on the influence of
pyrolysis temperature, residence time or heating rate on the bio-char yield and on
determination of the HHV of the pyrolysis char.
Keywords: biomass, bio-char, pyrolysis, temperature, heating rate
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
ENERGY EFFICIENCY AND ENVIRONMENT
Michel FEIDT
In this paper, we intent to review and reconsider the concept of efficiency
applied to energy systems and processes. It is shown that due to increasing use of
energy, we must refine the criterions that serve as objective functions to
characterize and optimize systems and processes. Moreover coupling between
energy uses and environment appears more and more important. This question
starts to be explored : present state of the art is summarized ; some suggestions and
perspectives are evoked, particularly the relation to economy, even if the main
aspects developed remain centered on the scientific part and technical
consequences.
Keywords: energy, environment, economy, efficiency
THE INCREASE OF ENERGY EFFICIENCY THROUGH THE
CONVERSION OF A THERMAL POWER PLANT INTO A
COGENERATION PLANT
Petre BLAGA, Horia NECULA, Constantin IONESCU
Re-engineering obsolete industrial plants is an increasingly important issue
for small and medium enterprises. This paper describes the transformation of a
thermal power plant with simultaneous production of low-temperature saturated
steam and hot water into a central cogeneration plant, at a company from the drug
industry field.
Taking into account the economic advantage, reduced operating problems,
environmental protection etc., the cogeneration solution with heat engines was
appealed. By using this solution for cogeneration, the company recorded a 5-12%
reduction in the monthly bills, lower than buying all electricity from the system.
Keywords: energy efficiency, cogeneration, heat engine, technical analysis
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
COMPARATIVE STUDY OF HEAT PRODUCTION BY
COGENERATION OR HEAT PUMP
André LALLEMAND, Lingai LUO, Renaud GICQUEL
Considering Carnot cycles, it is shown that reducing the power of a thermal
power plant to produce cogeneration or using this difference in power to run heat
pumps is equivalent in terms of overall performance. Practically, this is however not
the same. This conclusion is put in evidence when considering an actual 280 MW
power cycle and R134a, R600 and R717 heat pumps. It is shown that depending on
the operating temperatures of the heat pumps and the heating network transmission
losses, the overall cogeneration performance can be higher than the use of heat
pumps in many configurations.
Keywords: rational use of energy, waste heat, power plants, heat pumps,
cogeneration
COMPARATIVE ANALYSIS OF PRODUCTION AND
PROCESSING OF GLASSWARE AND TECHNICAL GLASS
Roxana PATRAŞCU, George DARIE, Eduard MINCIUC, Cristian
RĂDUCANU, Adina STANCULEA
The article is an integrated approach of energetic efficiency and
environmental impact in the field of glass industry. The article is also targeting at
improving of energetic and economic efficiency, a reduction of the environment
impact and new equipment implementation in the field of glass manufacturing
industry in Romania. The model aims at increasing energy and economic
efficiencies and decreasing environmental impact, as well as finding new clean
technologies for the Romanian glass manufacturing industry. New methodologies
techniques and technologies and also the new developed evaluation models might
have a replication potential for other industrial sectors.
Keywords: glass, analysis, energy, economic, environment
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
OPPORTUNITIES TO CONSERVE ENERGY RIGHT FROM
DISTRIBUTION INSTALLATIONS
Gheorghe CÂRŢINĂ, Gheorghe GRIGORAŞ, Elena-Crenguţa BOBRIC
The paper presents a methodology of the evaluation of the energy saving
potential in distribution network, by replacement of the old transformers with
efficient transformers. The modeling of the transformers load was performed by
fuzzy techniques. Finally, a study case for a urban distribution network is presented.
Keywords: smart grids, energy saving, efficient transformers, fuzzy techniques
AN EVOLUTIONARY PROGRAMMING APPLICATION TO
OPTIMAL REACTIVE POWER DISPATCH
Florin IONESCU, Constantin BULAC, Ioana PISICĂ, Ion TRISTIU, Lucian
TOMA
This paper presents an application of evolutionary programming (EP) to
optimal reactive power dispatch (ORDP). The objective of ORDP is to minimize the
real power losses and keep the voltages and reactive power generations in their
operating limits. In this matter the control variables are generator bus voltages and
transformer taps.
The proposed EP approach was evaluated on the modified IEEE-30 bus
system.
Keywords: Evolutionary Programming, Optimal Reactive Power Dispatch,
Minimizing the Real Power Losses
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
PARAMETERS IDENTIFICATION OF A POWER PLANT
MODEL FOR THE SIMULATION OF ISLANDING
TRANSIENTS
Alberto BORGHETTI, Mauro BOSETTI, Carlo ALBERTO NUCCI, Mario
PAOLONE
The paper presents a procedure for parameter identification along with its
application to the model of a combined cycle power plant that includes the
surrounding electrical network, built for the analysis of islanding maneuvers
transients. The paper illustrates both the power system computer model,
implemented within the EMTP-RV simulation environment, and the developed
identification procedure based on the interface between the developed model and
Matlab. The parameter identification procedure is applied to experimental transient
recordings that make reference to a similar power plant.
Keywords: power plant, parameter identification, islanding, electromechanical
transients
LIFE CYCLE IMPACT ASSESSMENT OF FOSSIL FUELS
Cristian DINCĂ, Adrian BADEA, Tiberiu APOSTOL
The main objective of this study is to compare the life cycle of fossil fuel
(coal, natural gas and oil) in order to assess the overall environmental impact. In
this respect it was analyzed the fossil fuels energy production based on the best
available energy technologies for each fuel. The methodology used in order to
evaluate the total environmental impact was Life Cycle Analysis.
The method allowed on one side the identification of the pollutants generated
in each stage: extraction, treatment, transportation and combustion, and on the
other side identification of the main classes of impact according the pollutants
inventory.
Keywords: LCA, fossil fuels, multi-criteria analysis
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
NEW METHODS FOR THE ASSESSMENT AND THE
REDUCTION OF THE CO2 EMISSIONS IN IRON AND STEEL
PROCESSES AND THERMO-ELECTRIC POWER STATIONS,
BASED ON AN INTEGRATED APPROACH
Ion MELINTE, Mihaela BĂLĂNESCU, George DARIE, Carmencita
CONSTANTIN
This paper presents new methods for the assessment and the reduction of the
CO2 emissions in iron and steel processes and in thermo-electric power stations,
based on a conceptual model for an integrated, technological and energetic system,
using the calculus programs and patterns and simulations of the process input
parameters (quantities of raw materials, fuel feeds, carbon content in the raw
materials and in the fuels).
There are approached primary methods for reducing the CO2 emissions,
namely the modification of the process input parameters or the modification of the
actual process (technological or combustion), for improving its technologic or
energetic efficiency.
Keywords: new methods, CO2 emissions reduction, integrated approach, iron and
steel
ECONOMICAL CO2 CAPTURE FROM FOSSIL FLUE
UTILIZATION
Elena DAVID, I. ŞTEFANESCU, A. ARMEANU
This paper presented an experimental study for CO2 capture from flue gas by
pressure swing adsorption process (PSA). Capture of carbon dioxide from a binary
mixture (N2/CO2) simulating flue gas was performed by PSA, using selective
adsorbents (zeolite-X, carbon molecular sieve, activated carbons). One PSA process
consists of three adsorption beds. The process was tested by varying the operation
parameters: pressures of adsorption and vacuum evacuation steps. As a typical
result, a high purity CO2 (≈99%) can be produced with recoveries of 50% and 65%
from feed gases containing 15-25 vol. % CO2 respectively. By the other process of
two stage PSA, CO2 can be concentrated from feed gas to product of 99% with much
higher capture (>80%).The obtained results prove that the capture of CO2 from the
fossil fuel industry by PSA process is to find cost-effective solutions that will reduce
the release of CO2 into the atmosphere and can contribute to cleaning of
environment.
Keywords: CO2, PSA, Adsorption, Pollution, Environment
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
VOID REACTIVITY REDUCTION IN CANDU REACTORS
USING BURNABLE ABSORBERS AND ADVANCED FUEL
DESIGNS
Iosif PRODEA, Cristina Alice MĂRGEANU, Andrei RIZOIU, Ilie PRISECARU,
Nicolae DĂNILĂ
It is very well known that the CANDU® reactor has positive Coolant Void
Reactivity (CVR), which is an important criticisms about CANDU. Recent
innovations based on using of a thin absorbent Hafnium shell in the central bundle
element were successfully been applied to the Advanced CANDU Reactor (ACR™)
project. The paper's objective is to analyze elementary lattice cell effects in applying
of such methods to reduce CVR. Three basic fuel designs in their corresponding
geometries were chosen to be compared: the ACR-1000TM, the RU-43 (developed in
INR Pitesti) and the standard CANDU fuel. The Graphite absorber influence on
void effect was also evaluated. The WIMS calculations proved the Hafnium absorber
suitability (in the latest "shell design") to achieve the negative CVR target with a
great accuracy for the ACR-1000 fuel bundle design than the other two projects.
Keywords: ACR, CANDU, CVR, burnable absorber
INFLUENCE OF PREHEATER LOSS IN REGENERATION
EFFICIENCY ON THE SECONDARY CIRCUIT
Ilie PRISECARU, Iulian Pavel NIŢĂ, Daniel DUPLEAC
This paper presents the results of operating analyses in secondary circuit of
Cernavoda NPP - Unit 2, in abnormal regimes, due to the failure of a feedwater
preheater from the regenerative chain. Based on these analyses, operating solutions
are proposed in order to minimize power losses from the normal regime. In this
paper we developed a simplified method for calculating the operating parameters of
the heat exchangers in abnormal regimes. Also this method allows quick detection of
the abnormally operating heat exchanger.
Keywords: NPP operation, abnormal regimes, minimized losses, heat exchangers,
plant efficiency
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
ANALYSIS OF SOME CRITICAL POINTS THAT MAY
INFLUENCE CERNAVODA NPP NUCLEAR SAFETY
DURING AN EARTHQUAKE AND SOLUTIONS TO
INCREASE THE SAFETY MARGIN
Viorel ŞERBAN, Ilie PRISECARU
The paper is a general presentation of the main critical points in
CERNAVODA NPP- Unit 1 and 2 in respect of seismic behavior, which from the
authors’ viewpoint are:
- Fuelling Machine coupled to a fuel channel; - The pipe leg of the Emergency Core Cooling System (ECCS) having
supports on the inner structure, the containment and the staircase structure in B
area;
- Live Steam pipe legs installed on the reactor containment and service
building.
Keywords: critical points, safety margin, SERB device, hysteresis diagram
REAL EFFICIENCY OF INTELLIGENT SWITCHING OF
HIGH VOLTAGE CIRCUIT-BREAKERS
Florin MUNTEANU, Ciprian NEMEŞ
The concept of intelligent switching means extending the existing controlled
switching characteristics to new situations from which the case of faults is the most
important. One of the main aspect is related to modern high speed circuit-breakers
which are opening before the d.c. component of the short-circuit current is closed to
zero. Based on authors’ main research results in implementation of intelligent
switching of high voltage circuit-breakers in case of faults, the paper deals with the
real advantages and efficiency of this relative new technology in power systems.
Between main positive results of this new technology there is a major power quality
improvement as much as the overvoltages and overloads are strongly diminished.
Keywords: intelligent switching, stress mitigation, circuit-breakers
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
INFLUENCE FACTORS ON THE TRANSMITTED
OVERVOLTAGES FROM HIGH VOLTAGE TO LOW
VOLTAGE NETWORKS
Marian COSTEA, Bogdan NICOARĂ
In the high and medium voltage networks a large variety of overvoltages can
occur. These are produced by lightnings, switching operations or insulation faults.
Normally, the protection against overvoltages, based of surge arresters and relay
protection of the equipment, act to eliminate or reduce the insulation stress. The
transients occurred in the high or medium voltage networks are then transmitted by
different mechanisms to the low voltage networks. The paper analyse the influence
factors and their weights to the transmitted overvoltages from a superior voltage
networks to the low voltage one considering a proper action of the protection
against overvoltages in the first network. The study was performed on a real
configuration of network subjected of different shape and amplitude of lightning
overvoltages.
Keywords: electric power installation, full lightning impulse, chopped lightning
impulse, lightning induced overvoltage
DC ARC FURNACE MODELLING FOR POWER QUALITY
ANALYSIS
Cristian LĂZĂROIU, Dario ZANINELLI
The dc arc furnaces are highly disturbing loads for transmission and
distribution networks. The present paper deals with the study of the dc arc furnace
modeling and analysis of the controller structure for the ac-dc converter,
highlighting the advantages obtained regarding power quality improvement. In this
study both deterministic and random models of the electric arc are considered
together with different structures of the ac-dc converter unit.
Keywords: voltage flicker, dc arc furnace, power quality
U. P. B. Sci. Bull., Series C, Vol. 72, Iss. 1, 2010
ISSN 1454-234x
STEADY-STATE STABILITY LIMIT IDENTIFICATION FOR
LARGE POWER SYSTEMS
Florin CIAUŞIU, Mircea EREMIA
This paper is treating the problem of steady-state stability reserve
identification in a power system when realizing off-line simulations. Even in off-line
simulations the stability reserve of a power system is not a straight forward analysis.
The difficulties appear when trying to solve the stability reserve aspect for a large
power system. Present paper is illustrating the steady-state stability limit
identification by using eigenvalues and eigenvectors computation. In this respect, a
software application created by the authors under Matlab software tool is used in
combination with PSA/Eurostag in order to compute the eigenvalues of the steadystate matrix.
Keywords: steady-state stability, eigenvalues, steady-state matrix analysis.
ROUGH SET THEORY AND ITS APPLICATIONS IN
ELECTRICAL POWER ENGINEERING. A SURVEY
Ioana PISICĂ, Petru POSTOLACHE
Rough Set theory represents a promising technique in imperfect data
analysis, which has found interesting extensions and various applications. It can be
regarded as complementary to other theories that handle imperfect knowledge, such
as Bayesian inference or fuzzy sets. The paper presents some Rough Set Theory
concepts and applications in several fields, with emphasis on a series of
applications in electrical engineering.
Kewords: rough set, attribute selection, information system