Download ΤHE SCIENTIFIC ENERGY SAVING PROJECT OF SEMAN IN

ΤHE SCIENTIFIC ENERGY SAVING PROJECT OF SEMAN
IN HALYPS CEMENT PLANT
MEMBER OF ITALCEMENTI GROUP
Α. HALYPS CEMENT PLANT OF ITALCEMENTI GROUP.
Italcementi Group, having an annual production capacity of more than 60 million
tons and 46 cement plants, is the world’s fifth largest cement producer. Along with
the cement plants, Italcementi Group’s industrial network includes 12 grinding
centers, 6 terminals, 417 concrete batching units combining the expertise, knowhow and cultures of 22 countries across four continents.
Italcementi Group is operating in Greece through Halyps Building Materials S.A.
company. Halyps Building Materials S.A. is operating in cement activity under the
brand name “Halyps Cement”, in aggregates activity under the brand name "Halyps
Quarries” and in the concrete activity under the brand name "Et Beton", having
three production plants servicing the Attica region.
Picture 1: General Plant View
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Picture 2: General Plant View
Picture 3: Production Line
The total installed electric power of Halyps Cement Plant comes up to 30,5 MW. The
grid is in 50Hz and there are 13 Transformers supplying loads to various voltage
levels (e.g. 6300V, 550V and 400V). The average annual electricity cost is
approximately 7.143.672,79 € in current prices.
Β. The scientific project of SEMAN
The scientific project for electric energy saving and current - voltage quality
improvement has been concluded by SEMAN in March 2010.
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In order to elaborate the scientific study for Halyps Cement Electric Power Grid, the
engineers’ staff of SEMAN performed measurements and recordings of all the
required electrical values at each individual load of the installation (AC & DC motors,
motors operating with Inverters, DC Converters, Star- Delta starters, etc., both in
Low and Medium Voltage).
Picture 4: Laptops used for measurements and recordings
Measurements and recordings concerned the basic electric values (power, reactive
power, voltage, current, frequency), as well as current & voltage harmonics (up to
the 35th class) and transient phenomena.
Inside the Electric Power Grid of Halyps Cement plant, transient phenomena occur
not only from the disturbances catering from the Public Power Distribution Network,
but also from its own big electric loads that start and stop sharply during production
days.
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Picture 5: Measurements have been performed also in the core of the electrical installation next to the loads
Moreover, the engineers’ staff of SEMAN proceeded to the collection of all the
essential data regarding the lengths and cross-sections of cables, the number of
cables headed together in canals, the nominal values of motors, the power
transformers and many other data also necessary for the elaboration of the scientific
study for the electric energy saving project.
Picture 6: Measurements with special power quality analyzers
The analysis of measurements and recordings showed that considerable harmonic
sources existed inside the Electric Network of Halyps Cement, producing not only
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harmonic currents (for example, at the ID FAN drive, THD-I% reached 45% of the
fundamental - see Pic. 7), but also considerable voltage harmonics.
Picture 7: Harmonic currents recordings in the electric network
Picture 8: Voltage harmonics distortion % recordings in the electric network
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Picture 9: Portable measurement devices
Running a number of simulations according to SEMAN’s know-how for the Electrical
installation of Halyps Cement plant, the electric energy saving scientific study
concluded that 34 customized interventions should be installed at all voltage levels
(please refer to pictures 10, 11 for low voltage loads and to pictures 12, 13 for
medium voltage loads).
The total installed power of SEMAN’s customized interventions for the voltagecurrent quality improvement and electric energy saving project was 10,5MVA.
It should be mentioned that most of the above specialized interventions are
Thyristors switched (please refer to pictures 14 and 15). These Thyristor Switched
interventions have been designed from SEMAN’s engineers especially for the power
system of Halyps Cement plant, which requires instantaneous harmonics absorption
and VAr support to mitigate voltage sags, voltage flicker and high inrush currents
associated with large dynamic loads and motor starting. The answering time could
be as less as 20 milliseconds. Moreover, the inrush currents are the minimum, as the
filter steps of SEMAN’s customized interventions are switched at "zero current cross
over threshold”.
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Picture 10: Low Voltage (LV) SEMAN’s customized interventions
Picture 11: Low Voltage (LV) SEMAN’s customized interventions connected to the motor’s terminal
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Picture 12: Medium Voltage (MV) SEMAN’s customized intervention
Picture 23: Detail of a MV customized intervention of SEMAN
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Picture 34: Thyristor Switched customized intervention of SEMAN
Picture 15: Details of a Thyristor Switch
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The target of the installed customized interventions was to:
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maximize the total efficiency of the electrical installation,
improve motors’ efficiencies, through:
 the minimization of the counterclockwise electromagnetic torques
caused by harmonics and,
 the reduction of voltage drops and the higher constant voltage to
the motors.
improve power transformers’ efficiencies by the reduction of their copper
and iron losses,
reduce the following thermal losses:
 Thermal losses of supply.
 Contiguity Effect Losses.
 Skin Effect Losses.
 Eddy Current Losses.
According to SEMAN’s scientific tools for the simulation of electrical installations,
such as the finite elements method along with load flow analysis, all interferences
between the electrical loads of the plant and all possible resonance frequencies of
current harmonics at cables, subpanels and power transformers were calculated. The
results of the above simulations led to the final design of the customized
interventions, which can operate in any operation scenario of the installation.
Furthermore, an extensive spread Power Quality Measuring System has been
developed at the Electrical Installation of Halyps Cement Plant. 37 Power Quality
analyzers (please refer to pictures 16 and 17) have been installed at different places
of the plant, measuring all the electrical values of certain electric loads. All the 37
devices are interconnected using fiber optics, profibus and network cables. The
purpose of the established network is to transfer the measured values to a central
SCADA system (please refer to pictures 18 and 19). The operation and control with
this center’s interface is being made via Programmable Logic Controller (PLC). PLC is
running the well-known WinCC Premium software by SIEMENS. The SIMATIC WinCC
Powerrate add-on provides transparency for energy consumption from the power
supply to the user. Energy data is continuously collected, archived and further
processed. Exact knowledge of the consumption profile and detailed information
about the costs involved allow the user to identify savings potential, optimize the
energy import, and thus, lower the energy costs. This transparency enables energy
consumption to be optimized while being fully integrated into the WinCC
environment.
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Picture 15: Power Quality Measuring Systems
Picture 16: Power Quality Analyzer
Picture 17: General View of SCADA system visualization
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Picture 48: Detail of SCADA system visualization
C. Results – Benefits – Conclusions
After the completion of the project, measurements and recordings were performed
that demonstrated significant reductions in rms consumption currents, improvement
of voltage levels, reduction up to eradication of the requested reactive power. The
evaluation of SEMAN’s energy saving project result was realized according to the
methodology described in the relative International Bibliography:
[1] Council Regulation (EEC) No 1836/93 of 29 June 1993 allowing voluntary
participation by companies in the industrial sector in a Community eco-management
and audit scheme.
[2] International Performance Measurement & Verification Protocol. Concepts and
Options for Determining Energy and Water Savings, Volume 1, Revised March 2002.
[3] North American energy M&V protocol, version 1March 1996.
Specifically, by using historical data of the electric energy consumption and
operation of the several sections of the plant before the electric energy saving
project, a mathematical model was developed, based on regression analysis,
correlating the monthly electric energy consumption with the monthly operational
data of the plant (such as production data of the various plant departments,
operational hours, etc). The correlation accuracy of the mathematical model was
very good, as the average prediction error for the historical data was only 0,73%.
By applying this accurate mathematical model to the months followed project
implementation, it was calculated with great accuracy the energy consumption of
each month if SEMAN’s saving project had not been carried out. By comparing each
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month these calculations with the real energy consumption (extracted by the
monthly electricity bills of the plant) in the presence of SEMAN’s customized
interventions, the final electric energy saving and also the cost saving result in the
electricity bills was calculated. The aggregated results are analytically presented in
the following Table 1.
Table 1. Synoptic Results of SEMAN’s Electric Energy Saving Project accomplished for Halyps Cement Plant
Value
Results
Guaranteed Electric Energy Saving according to the contract (%)
-5,32%
Real Electric Energy Saving finally achieved (%)
(according also to the Reference Letter by Halyps Cement Company
Management)
-9,00%
Guaranteed Pay Back Period of the project (years)
3
Real Pay Back Period of the project (years)
1,8
Annual Money Saving (€)
642.930,00 €
Picture 19: Harmonic currents recordings in the electric network after SEMAN’s project
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Picture 20: Voltage harmonics distortion % recordings in the electric network after SEMAN’s project
In conclusion, SEMAN’s scientific project in the electrical installation of Halyps
Cement plant had some extra benefits, as confirmed also by Halyps Cement staff.
Some of these extra benefits are the following:
1. Reduction of current & voltage harmonics up to 40%. Before (See Pic 8 & 9)
and After (See Pic 19 & 20) SEMAN’s interventions.
2. Optimization of the voltage & current quality in the electric installation of
the plant.
3. Increase of the efficiency of the electric power grid, motors and power
transformers.
4. Reduction of production lines’ undesirable halts, due to the decrease of load
supply voltage sensitivity, caused by voltage dips and the instability of the
electricity provider’s Power Distribution Network in general.
5. Increase of electrical installation’s reserve.
6. Reduction of the maintenance cost concerning all components of the
electrical installation.
Taking everything into account, SEMAN’s project was considered totally successful y
Halyps Cement staff, which, also, sent a congratulatory reference letter.
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