Techniques to Achieve Energy Efficient Heating Substation

Abstract

The paper presents what are the techniques for energyefficient
heating substations in relation to the use of
devices that are integral parts of one heating substation.
An analysis of thermal substation before and after the
implementation of energy efficiency measures is
presented. Techno-economic analysis of implementation
of energy efficient heating substation was performed in
terms of electric energy consumption, the costs of the
old versions and new ones, and obtained data shows
estimated savings at the example of a heating
substation.

Full text

ERK'2014, Portorož, A:205-208 205
Techniques to Achieve Energy Efficient Heating Substation
Jasenko Sarajlic1, Nedzmija Demirovic2, Enes Demirovic3
1Energonivest Sarajevo, BiH
2 Faculty of Electrical Engineering Tuzla
3 Centrano grijanje dd Tuzla
E-mail: nedzmija.demirovic@untz.ba
Abstract
Efficient use of energy raises the quality of our own
environment and contributing to the global fight to
combat climate change. Simply put, energy efficiency
means a smaller amount of energy used for the same
work - function (heating or cooling, lighting, producing
variety of products, drive vehicles, etc.). It should be
noted that energy efficiency can not be seen as energy
savings, because savings are always entails certain
sacrifices, while the efficient use of energy never distort
the conditions of work and life. Furthermore, improving
the efficiency of energy consumption not only involve
the application of technical solutions, but also the
existence of educated people who will know how to use
it in the most efficient manner possible.
The paper presents what are the techniques for energy-
efficient heating substations in relation to the use of
devices that are integral parts of one heating substation.
An analysis of thermal substation before and after the
implementation of energy efficiency measures is
presented. Techno-economic analysis of implementation
of energy efficient heating substation was performed in
terms of electric energy consumption, the costs of the
old versions and new ones, and obtained data shows
estimated savings at the example of a heating
substation.
1 Introduction
Energy efficiency is the top priority for most people.
However, what energy efficiency really involves and
what the ways of saving energy can be applied is still
quite unclear. For this reason, some companies are
dealing with the energy savings, determined two
approaches to energy efficiency including: passive
energy efficiency, and greater extent active energy
efficiency. From the point of view of active energy
management it is not enough just to install energy-
saving equipment, but they can be controlled and to use
only as much energy as they need. This aspect of
control is actually crucial to achieving maximum energy
efficiency [1]-[3].
The term energy efficiency is used in various ways
depending on the contest, and also depends on the
person using the term. From the standpoint of the
profession, energy efficiency is in relation to the energy
input and the output of a process. This is a typical
engineering approach when analyzing machines,
motors, etc.
The energy efficiency of the electric motor is the ratio
of mechanical input (work) and output electrical power.
The values must be expressed in the same units such as
kWh / day as a result, often dimensionless number,
conventionally expressed as a percentage.
This approach is represented in industrial plants and
buildings for a wide range of equipment including
motors, pumps, compressors, electric stoves and water
heaters. In many real situations, energy efficiency often
has its alternate name. On a national or a higher level is
often mentioned term energy intensity. The difference
between energy efficiency and energy intensity is that
changes in the sector, such as the transition from the
production of one product to another, affect the energy
intensity regardless of the change in the energy
efficiency of the plant, machinery or processes that are
involved in the production. There are many of the
benefits of increased energy efficiency. They can
generally be categorized as financial (economic),
environmental and social. For private companies, the
most significant benefits of implementing energy
efficiency measures are directly related to the financial
indicators in the form of lower operating costs. This
refers to the typical manufacturing companies as well as
suppliers of energy.
2 The concept and role of heat
substations in heating system
According to the holder of the heat, district heating
systems can be divided into hot water and steam
systems. According to the type of consumer and their
location they are divided into block heating systems
with heat source in a separate facility or heating plant
and the industrial and urban systems. Industrial remote
systems satisfy needs of the technological processes in
production. In addition to commonly used to supply
heat to the settlement of prefabricated housing that is
being built near industrial facilities. Supplying heat to
entire cities, or at least large parts of them, called the
system of the city or district heating.
Pipeline, which carries the fluid to the property, which
is connected to the remote system, is a primary network.
Piping from the substation to the end users and the
radiator is a secondary network. Limit location of
primary and secondary pipe networks are heat
substations, where the primary carrier of heat has to be
transformed according to needed of individual

206
consumers through a secondary network. Equipment
compact heat substation consists of mechanical (thermal
engineering) part and the power part [3] - [5].
Thermo-technical installation contains all the necessary
elements required to operate the substation:
- heat exchanger (indirect connection with
consumers),
- pressure regulator and relief valve (with direct
connection of customers)
- electric control valve or combined valve,
- ultrasonic flow sensor (part of heat meters),
- catcher dirt and sump.
- circulation pump,
- court or expansion device to maintain pressure
- safety valve,
- sensor for measuring the pressure and
temperature of the water
3 Measures to achieve energy efficient
heating substation
With increasing awareness of the need for improving
energy efficiency in the market have begun to appear
different solutions that have found their use in district
heating sector and thus also in heating substations.
Some of these solutions are comprised in this paper,
such as frequency converters, high efficiency electronic
pumps, electronic controls, thermostatic valves,
balancing valves, etc [6] - [8].
3.1 Frequency converter ACS-800
The frequency converter is used to change the speed of
an induction motor according to the technological
process [6] - [8]..
It consists of:
- power supply (contactors, fuses)
- AC adapter - DC link
- modulator drive voltage and frequency –
output
- controls
- regulator
- protection and limits.
Figure 1 The block diagram of frequency converter
ACS 800 drives that are built on the heating system
have the ability to choose the motor control mode as
follows: DTC (Direct Torque Control) is suitable for the
largest number of examples and SCALAR control mode
should be selected in special cases where the DTC mode
can not be applied.
3.2 Wilo - Stratos PICO highly-efficient pump
With energy savings of up to 90% compared with the
old unregulated pump Wilo-Stratos PICO is more frugal
than any other pump of the A-Class, according to
standard European Committee. This is possible by using
an unique 3-watt technology. Practically pump will
repay itself in the first year of operation.
3.3 Electronic controller Eltec TP-05
Electronic controller TP-05 is very important to achieve
energy efficient heating substation. The regulator, as the
name implies, regulates the operation of the substation
according to predefined settings [6] - [8].
Electronic controller consists of:
- five analog inputs (pressure sensors, valves
openness ...)
- ten digital inputs (alarm pumps, pulse inputs etc.)
- eight temperature inputs (PT1000)
- digital outputs
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3.4 Pumps with variable flow
Pumps with variable flow like Wilo Stratos and
Grundfos Alpha have incorporated a variable speed
drive (VFD - Variable Frequency Drive), which changes
the speed of rotation of the engine, and thus changing
the flow of the pump. The pumps are equipped with
electronic that on the basis of the measured number of
revolutions of the motor pumps and electricity that
drives the motor and given parameters of pipeline pump
regulates the rpm and maintains the working point of
the pump. Some of the advantages of variable flow
pumps:
- reducing electricity consumption 70% to 90%
- optimized flow through heating body
- replacement of circulating pumps by one pump
when there are more thermostatically
controlled heating circuits
- greater efficiency condensing boilers
- longer service life of pumps and zonal
regulated valves
- less noisy pump operation
- easier selection and dimensioning pumps
4 Comparison of the results in relation to
the different techniques to achieve
energy effiviency
A complete analysis of the application frequency
regulated drive effects are done for pump water network
in Tuzla power plant based on the assumption that
regulation is made for two new operating points, so that
after the control engine is running with 75% and 60%
power.

207
Figure 2 Pump characteristic curve with the new operating
points
Operating parameters of pump aggregates, assumed
arbitrarily due to the impossibility of performing
experimental measurements, and corresponds to the
computational values from the equations regarding to
the theory of similarity work of turbo-machines:
00 n
n
Q
Q= ;
2
00
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
=
n
n
H
H (1)
3
00
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
=
n
n
P
P (2)
P
Pη
gHQρ
P⋅⋅⋅
= (3)
m
P
mη
P
P= (4)
where are:
g – the acceleration of gravitation,
ηp, ηm – level of efficiency pump and motor,
Pp, Pm – power of the pump and motor,
H – Effort of the pump
Q- Volumetric flow pumps
n- speed pumps
The difference or savings in the power demand of
electric drives and savings in the consumption of raw
water gives input to the economic analysis of the effects
of reconstruction. Saving electricity due to the
reduction of engine power pumping units is:

kWW 997,2299671724812719ΔP==+= (5)
,kWh 104884,5
Wh048845001350029967TIΔPΔE
=
=
⋅=⋅=
Average annual energy savings is ΔE≈ 104 884,5 kWh.
Table 1 The parameters of the pump before regulation
No
frekvency
regulation
Number of
rpm
Effort of
the pump Flow
Power
of the
motor
n [rpm/min] H [m] Q [m3/h] P [kW]
2945 70 64 22
Table 2 The parameters of the pump after frequency regulation
and achieved energy savings
Number
of rpm
Effort
of the
pump
Flow
Power
of the
motor
Power
saving
Water
saving
n
[rpm/min] H [m]
Q
[m3/h] P [W]
P
Δ[W]
Q
Δ
[m3/h]
2250 39,38 48 9281 12719 16
1800 25,20 38,4 4752 17248 25,6
5 Analysis of own electricity consumption
of heating substations and economic
indicators justification of investments
5.1 Application of frequency converter
By applying the frequency converter on the drive pumps
substation “Korzo'' 1'' some positive results are
achieved. By monitoring electricity consumption, which
is carried out in the specified substation, corresponding
results obtained are presented in the Table 3 –Table 6.
It is considered the heat exchange substation of nominal
power of 2800 kW engaged in heat and power is 1908
kW.
Table 3 Consumption in the typical months in a higher and a
lower daily rate and total consumption after installation of
frequency converter 31.05.2007.
PERIOD
HIGH
TARIFF
LOWER
TARIFF
SUM
kWh
31-Aug-07 13 19 32
31-Dec-07 4153 4317 8470
31-Jan-08 4488 5633 10121
29-Feb-08 4211 4523 8734
Table 4 Consumption in the typical months in a higher and a
lower daily rate and total consumption after suffering
frequency converter 22.11.2008.
PERIOD
HIGH
TARIFF
LOWER
TARIFF
SUM
kWh
31-Dec-08 6106 7841 13947
31-Jan-09 5822 8018 13840
28-Feb-09 5203 6954 12157

208
Table 5 Consumption in the typical months in a higher and a
lower daily rate and total consumption with the new built-in
frequency converter 28.05.2009
PERIOD
HIGH
TARIFF
LOWER
TARIFF
SUM
kWh
31-Dec-09 3911 4339 8250
31-Jan-10 4522 6172 10694
28-Feb-10 3943 5310 9253
Table 6 Consumption in the typical months in a higher and a
lower daily rate and total consumption after re-suffering
converter 10.10.2011
PERIOD
HIGH
TARIFF
LOWER
TARIFF
SUM
kWh
31-Aug-11 15 21 36
31-Dec-11 5994 8070 14064
31-Jan-12 5188 6868 12056
29-Feb-12 5135 6788 11923
From the presented tables it is evident that the energy
consumption in the summer negligible compared to the
periods of the winter months, which is logical because
the pump as the largest consumers of electricity in the
substation, work during winter months [9].
Heating season in Tuzla lasts from the beginning of
October until the end of the fourth month next year.
Therefore, the following analysis and spent observing
eight complete heating seasons and this season of
2006/2007 do 2013/2014. Temperature characteristics
of selected heating season were approximately equal
with characteristic of average high temperatures of
winter period.
From the previous table it can be seen that the
consumption of electricity is reduced in the season
which the pump plant was built with frequency
regulator (converter).
Realized savings at the level of the season amounted to
11165 (kWh) or consumption was reduced by 16.41%
compared to the season without frequency regulator.
Using an automatic speed control speed according to set
parameters of pressure and temperature it is possible to
avoid unnecessary energy consumption caused by
increased improper handling of individuals.
6 Conclusion
Using modern smart technology to optimize the
efficiency of the system for energy management
currently offers the greatest opportunities for improving
energy efficiency and reducing operating costs, while
ensuring significant reduction in CO2 emissions.
Through detailed energy audit and analysis of specific
indicators of technologies used for industrial systems it
is possible identify the causes of irrational energy
consumption, in order to find the best balance between
system management, and user devices. Setting energy-
efficient motor and frequency inverter is one of the
easiest measures to achieve energy efficiency.
Responsible and rational approach of using modern
devices can contribute to reducing their energy
consumption which directly reflects on the necessary
financial resources of the company.
Literature
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perspective Technological Studies:“Best available
Techniques in the Energy Efficiency“, July, 2007.
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