ELABORATION OF TECHNICAL PROJECT CONCEPT OF THE FUEL SWITCH TO BIOMASS IN PROKUPLJE INCLUDING ECONOMICAL EVALUATION AND RECOMMENDATIONS FOR IMPLEMENTATION STRUCTURE OF DISTRICT HEATING GRID Prepared for: Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH Dag Hammarskjöld Weg 1-5 Postfach/ P.O.Box 5180 65760 Eschborn Prepared by: K.R.B. Consulting & agency Starovlaška 89 32250 Ivanjica September 2017
78
Embed
ELABORATION OF TECHNICAL PROJECT CONCEPT OF THE FUEL ... · elaboration of technical project concept of the fuel switch to biomass in prokuplje including economical evaluation and
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
ELABORATION OF TECHNICAL PROJECT CONCEPT OF THE
FUEL SWITCH TO BIOMASS IN PROKUPLJE
INCLUDING ECONOMICAL EVALUATION AND
RECOMMENDATIONS FOR IMPLEMENTATION STRUCTURE OF
DISTRICT HEATING GRID
Prepared for:
Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Table 4 - Data on population of the town of Prokuplje from 1961 to 20115
The most significant energy potential, which would ensure sustainable development, is the use of
biomass as a fuel. Wood potential of forests and orchards, as well as developed agriculture;
represent a good basis for collecting biomass with the purpose of solving the energy needs of public
and residential buildings in the city. Solution for energy requirements of the buildings is based on
the development of district heating network and installation of biomass boiler.
Positive planning documents, i.e. Detailed regulation plan of the city heating plant from 2011,
consider the central heating source only, and omit the heating network. Therefore, the first step in
establishment of the heating system and a fuel switch to biomass would be to revise the planning
documents, to create a development strategy, and General regulation plan of Prokuplje.
4 The Census of Population, Households and Dwellings in the Republic of Serbia, 2011 http://popis2011.stat.rs/?page_id=2134 5 Ibid
16
4. EXISTING HEATING SYSTEMS
Public institutions in Prokuplje are located in separate buildings with individual radiator systems and
individual boilers using light fuel oil and coil. Qualified personnel manage the boiler rooms. In several
buildings, electric heaters are used.
Particular problem is the use of the fuel oil, which combustion produces negative environmental
effects. Under certain microclimate conditions, the allowed emission limits are exceeded, which
could lead to a closure of the heat source.
In all of the buildings, radiator-heating systems are designed for temperature regime of 80/60°C and
the outdoor design temperature for the region of Prokuplje is -14.5°C.
Microclimate data
Air temperature
Relative humidity
Daily insolation
Atmospheric pressure
Wind speed
Soil temperature
(°C) (%) (kWh/m2) (kPa) (m/s) (°C)
January 0.3 80.5 1.59 95.5 1.9 -1.6
February 2.0 74.2 2.42 95.3 2.0 0.1
March 6.6 66.0 3.41 95.2 2.5 5.3
April 11.8 64.4 4.13 94.9 2.2 10.8
May 16.9 66.0 5.08 95 2.0 16.7
June 19.9 66.9 5.75 95.1 1.8 20.6
July 22.2 63.1 6.00 95.1 1.9 23.2
August 22.1 62.1 5.42 95.1 1.8 23.3
September 17.5 68.7 3.95 95.3 1.7 18.2
October 12.4 73.3 2.67 95.5 1.8 12.0
November 6.1 78.2 1.62 95.4 1.9 4.8
December 1.7 81.4 1.28 95.5 2.0 -0.5
Year 11.7 70.4 3.62 95.2 2.0 11.1
Table 5 - Microclimate data for the City of Prokuplje6
6 RET Screen International & NASA Software, updated 2014
17
Analysis of heating systems connected to the boiler room in the building of Gymnasium
Several buildings are connected to distributive system of the boiler room located in the building of
Gymnasium. There are three light oil fuel boilers of 3x550kW.
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Gymnasium 3,710 779 756,172
2 The gym ‘Sokolski Dom’ 574 145 66,531
3 National Museum Toplice 513 115 92,739
4 Movie Theatre 423 148 44,204
5 Primary school ‘Nikodije Stojanović Tatko’ 1,360 272 264,029
Total 6,580 1,459 1,223,675
Table 6 - Data on buildings connected to the boiler room of Gymnasium
Operations of the boilers are controlled by flow temperature
thermostats installed on the boilers. There are closed
expansion tank with compressor, water circulation pumps,
and collector for distribution of heating energy. Equipment
in the boiler room is outdated, but well preserved and
functional. There is two-pipe radiator heating system with
no thermostatic valves on radiators.
Photo 1 - Building of Gymnasium
Photo 2 - Light fuel oil boilers, 3x550kW Photo 3 - Insulated hot water collector
Photo 4 - Gymnasium underground fuel tank
18
Underground pipeline connects the boiler room in the building of Gymnasium to several other
buildings. First building on the route of underground pipeline is Gym hall ‘Sokolski dom’. It is used
for activities of Gymnasium and sports clubs. There is two-pipe radiator heating system without
thermostatic valves and ventilation system with air heated from the boiler room in the building of
Gymnasium. Ventilation system is used occasionally.
After the building of ‘Sokolski dom’, National Museum Toplice is connected to the pipeline. There
is two-pipe radiator heating system with panel radiators without thermostatic valves on radiators in
the Museum.
Photo 5 - Gym hall ‘Sokolski dom’ Photo 6 - Building of ‘Sokolski dom’
Photo 7 - Building of National Museum Toplice Photo 8 - Panel radiator in the Museum
19
Building of primary school ‘Nikodije Stojanović Tatko’,
also connected to the boiler room in Gymnasium, has
two-pipe radiator heating system without thermostatic
valves. Schoolwork is conducted in two shifts. School
building is modernized by reparation of the facade and
installation of PVC windows, which increased energy
efficiency of the building.
Photo 9 – Primary school ‘Nikodije Stojanović Tatko’
Movie Theatre is located in the building of Gymnasium. There is two-pipe radiator heating system
without thermostatic valves in Movie Theatre.
Photo 11 – Movie Theater and Gymnasium schoolyard view
Photo 10 - Movie Theatre, street view
20
Analysis of heating system in the primary school ‘Ratko Pavlović Ćićko’
Primary school ‘Ratko Pavlović Ćićko’ is heated from the boiler room located within the school
building. There are two wood pellet heated new boilers with power of 2x250kW, produced by
‘Šukom’, Knjaževac.
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Primary school ‘Ratko Pavlović Ćićko’ 2,870 502 487,289
Total 2,870 502 487,289
Table 7 - Data on the building of primary school ‘Ratko Pavlović Ćićko’
Until the end of heating season 2016-17, the School was heated by solid fuel. In summer of 2017,
the heating system was modernized. Former boilers were dismantled, and there were installed two
modern biomass (wood pellets) boilers, produced by ‘Šukom’, model Šukoplam PR 250. These
boilers have additional ventilator for airflow through the boiler. There is ongoing installation of rail
transporters for delivery of wood pellets to the boilers. There are also installed new circulation pumps
and new hot water distributors.
Photo 13 – Wood pellet boilers, 2x250kW
Photo 12 - Primary school ‘Ratko Pavlović Ćićko’
21
There is two-pipe radiator heating system without thermostatic valves in the School building.
Schoolwork will continue in two shifts. Operations of the boilers, ventilator, and rail transporter are
automatized in accordance with output water temperature from the boilers.
Analysis of heating systems connected to the boiler room in Kindergarten ‘Biseri’
Kindergartens ‘Biseri’ and ‘Bambi’ are both heated from the boiler room located in the Kindergarten
‘Biseri’. Underground pipeline connects Kindergarten ‘Bambi’ to the boiler room. ,
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Kindergarten ‘Biseri’ 458 59 48,460
2 Kindergarten ‘Bambi’ 529 79 64,887
Total 987 138 113,347
Table 8 - Data on the buildings of Kindergartens ‘Biseri’ and ‘Bambi’
There is two-pipe heating system without thermostatic valves in both kindergartens. Recently, there was
implemented energy rehabilitation of Kindergarten ‘Biseri’ by installation of thermal insulation and PVC
windows.
Photo 15 – Radiator without thermostatic valve
Photo 14 - Insulated hot water collector
22
Photo 16 – Kindergarten ‘Biseri’
Light oil fuel heated boiler is produced by ‘Sime’, model 2R 10, with
capacity of 200kW. There are circulation pumps and hot water
collector with damaged insulation. Equipment in the boiler room is
outdated and in a poor condition. There is underground fuel tank in
the yard of Kindergarten ‘Biseri’.
Photo 18 – Boiler in Kindergarten ‘Biseri’
Photo 20 – Damaged insulation of hot water collector
Photo 17 - Kindergarten ‘Bambi’
Photo 19 – Underground fuel oil
tank in the yard of Kindergarten
23
Analysis of heating systems connected to the boiler room in the building of Municipality
Building of the Municipality and Police station are heated from the boiler room located in the building
of the Municipality. Underground pipeline connects the Police station to the boiler room.
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Building of the Municipality 2,518 466 313,161
2 Police station 954 143 244,646
Total 3,471 609 557,808
Table 9 - Data on buildings of the Municipality and Police station
There is two-pipe radiator heating system without thermostatic valves on radiators in these two
buildings.
Photo 21- Building of the Municipality
There are two light oil fuel boilers produced by ‘Toplota’, Zagreb, with capacity of 2x290kW. There are circulation pumps and hot water collector without insulation. Equipment in the boiler room is outdated and in a poor condition. There is underground fuel tank in the yard of the Police station. Photo 23 – Fuel oil boilers in municipal boiler room
Photo 22 - Police station
24
Analysis of heating systems connected to the boiler room of Technical school ’15. Maj’
Building of Technical school ’15. Maj’, the School gym, and primary school ‘Milić Rakić Mirko’ are
heated from the boiler room located in the building of the Technical school ’15. Maj’. Underground
pipeline connects these buildings to the boiler room.
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Technical school ’15. Maj’ 2,790 446 432,930
2 School gym 780 196 89,932
3 Primary school ‘Milić Rakić Mirko’ 1,524 244 236,850
Total 5,094 886 759,711
Table 10 - Data on the buildings connected to the boiler room in Technical school
In all of above listed buildings, there are two-pipe radiator heating systems. In the School gym and
in primary school ‘Milić Rakić Mirko’, there are no thermostatic valves on radiators, while in Technical
school, thermostatic valves are installed. The building of Technical school was reconstructed and
energy rehabilitated by installation of thermal insulation and PVC windows. Schoolwork in both
schools is conducted in two shifts.
Photo 25 - Underground oil tank
in the yard of the Police station
Photo 24 - Uninsulated hot water collectors in municipal boiler room
25
There are two light oil fuel boilers with capacity of 2x750kW in the boiler room. There are circulation pumps and hot water collector without insulation. There is expansion tank with compressor. Installations in the boiler room are new, dated on recent reconstruction of the School building. Level of automatization of the boilers’ operations is low. Functioning of the boilers is regulated in accordance with temperature of water in the boiler. Underground fuel tank is located in the schoolyard.
Photo 30 - Underground fuel
oil tank in the Schoolyard
Photo 27 - Primary school
‘Milić Rakić Mirko’
Photo 26 - Technical school
’15. maj’ and School gym
Photo 29 - Uninsulated hot water collectors Photo 28 - Fuel oil boilers in Technical school
26
Analysis of heating system in the primary school ‘9. Oktobar’
Primary school ‘9. oktobar’ is heated from the boiler room located within the school building. There
are two oil fuel heated boilers with power of 2x400kW, produced by ‘Kran Inženjering’, Knjaževac.
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Primary school ‘9. oktobar’ 2,080 364 353,333
Total 2,080 364 353,333
Table 11 - Data on the building of primary school ‘9. Oktobar’
Premises of primary school ‘9. oktobar’ are located in two buildings. Boiler room is located in main
building, and secondary building is connected to the boiler room by underground pipeline. In both
buildings, there is two-pipe radiator heating system without thermostatic valves on radiators.
Schoolwork is conducted in two shifts.
There are water circulation pumps and thermally insulated hot water collectors. Equipment is outdated, but functional. Underground fuel tank is located in the Schoolyard.
Photo 32 – Secondary building of the School
Photo 33 - Fuel oil boilers in primary school
‘9. oktobar’
Photo 31 - Primary school ‘9. Oktobar’, main building
27
Photo 34 - Hot water collectors in the School ‘9. Oktobar’
Analysis of heating system in Sports hall ‘Dr. Zoran Đinđić’
Sports hall ‘Dr. Zoran Đinđić’ has no heating system. In the building consisting of the sports hall,
utility rooms, and offices, there is two-pipe panel radiator heating system, and heating system of the
sports hall by air conditioning chamber.
No Institution Heated
area Heating capacity
Calculated consumption
(m2) (kW) (kWh/a)
1 Sports hall 2,070 767 325,180
Total 2,070 767 325,180
Table 12 - Data on the Sports hall
Photo 35 - Underground fuel oil tank in the Schoolyard
Photo 37 - Sport court inside the Sports hall
Photo 36 - Sports hall ‘Dr. Zoran Đinđić’
28
Electric boilers are heating 230 m² of business premises in the building, while the sports hall is not
heated. Annual consumption of electricity for heating business premises is 200 kWh/m2, i.e. 46,000
kWh. As temporary solution, there are three LPG (liquefied petroleum gas) boilers with capacity of
2x48kW and 1x36kW, and the system of pipeline, circulation pumps, and collectors. As part of this
temporary solution, there are infrared heaters installed in the Sports hall immediately by the roof
structure. There is underground tank of LPG at fenced location behind the Sports hall.
LPG switch between the tank and equipment in the hall (boilers and infrared heaters) is installed on
the facade of the building. Bulkhead valve of the LPG switch is locked and secured by the Fire
department. This temporary LPG heating system is not operational due to failure in meeting
requirements of fire protection.
Planned solution for the heating of the Sports hall was construction of the boiler room that would be
connected to the Sports hall by underground pipeline. Behind the Sports hall, auxiliary facility of the
boiler room was constructed, but the boiler room has never been constructed.
Calculation of the potential of forest waste in the municipality of Prokuplje is based on the study
‘Potentials and Possibilities of Commercial Use of Wood Biomass for Energy Production and
Economic Development of the Municipalities Nova Varoš, Priboj and Prijepolje’. This Study was
carried out as the analysis of the availability of wood waste from the sawmill industry and forestry in
the municipalities of Nova Varoš, Priboj and Prijepolje. The results showed that following amounts
are available to meet energy needs:
8 ‘Potentials and Possibilities of Commercial Use of Wood Biomass for Energy Production and Economic Development of the Municipalities Nova Varoš, Priboj and Prijepolje’, 2009, author: Branko Glavonjić, PhD 9 ibid
Figure 8 - Share of forest’s area in the total area of the Serbian municipalities
Figure 7 – State and private forestsper Municipalities and Districts
38
Nova Varoš Priboj Prijepolje Total
Forest (ha) 22,400 30,400 44,000 96,800
Wood waste volume (m3)
Chips from forestry 3,100 4,300 5,400 12,800
Wood industry 9,364 1,194 11,739 22,297
Total 12,464 5,494 17,139 35,097
Wood waste mass (t)
Chips from forestry 1,813.5 2,515.5 3,159.0 7,488
Wood industry 5,477.9 1,137.2 6,867.3 13,482
Total 7,291 3,653 10,026 20,970
Annually available energy value (MWh/a)
Chips from forestry 4,003.2 5,532.2 6,950.0 16,485
Wood industry 15,901.6 3,308.2 19,932.6 39,142
Total 19,905 8,840 26,883 55,628
Table 20 - The energy potential of green chips from forestry, with wood waste from sawmill industry, in the municipalities of Nova Varos, Priboj and Prijepolje10
Calculated energy value of forest waste, without the waste of the sawmill industry of SE ‘Srbijašume'
and FE ‘Kuršumlija’ is shown in the table below:
Territory
Forest area
Volume of wood waste
Mass of wood waste
Annually available energy
ha m3 t MWh/a
Prijepolje, Priboj, Nova Varoš 96,800 35,097 20,970 55,628
Table 21 - The energy potential of biomass from FE ‘Kuršumlija’11
Biomass of wood origin in the form of pellets available on the market is not suitable for analysis due
to the high purchase price. Some of the benefits of wood chips compared to wood pellets are lower
prices and lower level of wood processing. Domestic market transactions are performed on a small
scale between manufacturers and wholesalers, where price reaches 180 €/t of wood pellets.
Depending on the time of purchase, end customers pay between 200 and 220 €/t. The advantage
of pellets is higher bulk density, which means lower transportation costs and smaller storage for the
same amount of fuel in terms of energy produced. Due to lower processing level, wood chips has
lower price, but higher moisture content, which affects its energy value, bulk density, and price.
Wood chips Moisture Energy value Bulk density Cost
(%) (kWh/m3) (bulk-kg/m3) (€/t)
30-40 940-1,200 300-350 45-60
Table 22 - Characteristics of wood chips depending on the percentage of moisture
10 ‘Potentials and Possibilities of Commercial Use of Wood Biomass for Energy Production and Economic Development of the Municipalities Nova Varoš, Priboj and Prijepolje’, 2009, author: Branko Glavonjić, PhD 11 Own calculation
39
6. TECHNICAL DESIGN CONCEPT
6.1 TECHNICAL SOLUTIONS AND SIZING THE BOILER
Aimed to decreasing fuel costs for heating public buildings in the Prokuplje municipality, it is
designed the concept of the construction of central boiler room with biomass- wood chips heated
boiler, remote district heating pipe system, and substations. Comparative analysis of annual fuel
costs in existing systems, and in case of using wood chips is shown in Table 24. The analysis does
not consider area of sports hall within the building of Sports hall ‘Dr. Zoran Đinđić’. In calculations
of total heating energy produced by future biomass heating system, the heating of this whole
building is included, which provides actual parameters of comparative analysis. Following Table
shows variation of energy value and unit price of energy, depending on percentage of moisture. Due
to large contact surface, wood chips easily exchanges moisture with environment, which affects its
energy value and unit price of energy.
Moisture
Caloric value
Unit price
(%) (kWh/t) (€/t) (€/kWh)
Biomass, wood chips
30 3,400 53
0.016
40 2,800 0.019
Table 23 - Unit price of wood chips depending on the percentage of moisture
Unit Fuel type
Biomass Light fuel oil Pellet Electricity Total
Energy consumption (kWh) 3,007,874 482,436 46,000 3,536,310 3,815,490
Emission of CO2 (kg) 842,205 0 15,180 857,385 0
Efficiency of system (%) 90% 90% 99% 0 83%
Increase for heating up the system
(%) 0% 0% 0% 5%
Consumption of fuel (t), (m3) 291 108 0 1,578
Heated area (m2) 18,213 2,839 230 21,282 21,282
Unit fuel price (€/t), (€/kWh),
(€/m3) 1,020 180 0.09 53
Annual energy cost (€) 296,428 19,492 4,140 320,060 83,631
Unit price of energy (€/m2) 16.28 6.87 18.00 15.04 3.93
Unit price of energy (€/MWh) 98.55 40.40 90.00 90.51 21.92
Table 24 - Comparative analysis of the costs of currently used fuels in Prokuplje and costs of biomass
Based on collected data, calculated annual fuel costs in buildings used by public institutions in
Prokuplje are estimated to be around 320,000 €. If the analysed facilities used biomass-wood chips
for heating, annual fuel costs would come to amount of approximate 85,000 €. The use of biomass
for the heating of analysed facilities can reduce annual fuel costs by the amount of 220,000-
250,000 €.
40
Figure 9 - Annual energy costs per fuel types - comparison with biomass
Figure 10 - Unit price of energy per fuel type - comparison with biomass
The program of switching existing fuels with biomass in buildings used by public institutions of
Prokuplje requires a complex analysis in order to select the best technical and economic solutions.
Facilities of public institutions are dispersed all around the town, so replacement of individual boilers
requires the construction of two new central biomass boiler rooms with pipe system for district
heating.
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
Light Fuel oil Pellet Electricity Total
296,428
19,4924,140
320,060
65,933
10,575 1,008
83,636
Annual energy cost (€)
Existing fuel (€) Biomass, ships (€)
0.00
20.00
40.00
60.00
80.00
100.00
Light Fuel oil Pellet Electricity Biomass
16.286.87
18.00
3.93
98.55
40.4
90.00
21.92
Unit price of energy (€/m2), (€/MWh)
(€/m2) (€/MWh)
41
Heating plant marked ‘A’ would be connected to public buildings in immediate city core. Heating
plant marked ‘B’ would be connected to the buildings of primary school ‘9. oktobar’, and Sports hall
‘Dr. Zoran Đinđić’, which are distant from the future heating plant ‘A’ app. 1 km. If these building
would be connected to the heating plant ‘A’, route of the pipeline would run through hardly
approachable streets on very unevened terrain. Furthermore, there are no other public buildings-
bigger consumers of heat energy on that route. In respect to these facts, connection of primary
school ‘9. oktobar’ and Sports hall ‘Dr. Zoran Đinđić’ to the heating plant ‘A’ would result in delay of
delivery of heating energy compared to consumers in the city centre, and in lower quality of the
system. Considering aforementioned, there will be constructed heating plant ‘B’ to satisfy
consumption of primary school ‘9. oktobar’ and Sports hall ‘Dr. Zoran Đinđić’.
Local boiler rooms Heating
area capacity
m2 kW
BOILER ROOM – HETAING PLANT - SYSTEM ‘A’
Gymnasium 6,580 1,459
Primary school ‘Ratko Pavlović Ćićko’ 2,839 497
Kindergarten ‘Biseri’ 987 138
Building of the Municipality 3,471 609
Technical School ’15. maj’ 5,094 886
TOTAL ‘A’ 18,972 3,589
BOILER ROOM – HETAING PLANT - SYSTEM ‘B’
Primary school ‘9. oktobar’ 2,080 364
Sports hall 2,070 767
TOTAL ‘B’ 4,150 1,131
Table 25 - Overview of the areas and capacity of central biomass heating systems ‘A’ and ‘B’
For each system (‘A’ and ‘B’) will be Construction district heating network which should enable the
connection of the considered public facilities, with the possibility of connecting others buildings in
the future. This district heating system represents an investment in infrastructure.
The required installed capacity of the boiler and level of efficiency of the heating system is calculated
using the formula:
C
B
QQ
QB (kW) Installed boiler capacity
QC (kW) Net consume (capacity)
η System efficiency
η = ηB · ηC
ηB Boiler efficiency
ηC Efficiency of district heating system
τ Simultaneity factor
42
The calculated heat demand would be covered by installing heating plant of nominal heat output
presented in the next table:
Table 26 - Calculated capacity of future heating plant
Figure 11 - Diagram of the annual distribution of the heat capacity of the heating plants
The number of hours of boiler operations can be determined using Sochinsky formula:
max
1
0
0
0
11 QQ
m
b
max
min0
Q
Q
maxQ
Qmm
Q - heating capacity at the time,
- time,
minQ - minimum heating capacity of boiler
maxQ - maximum heating capacity of boiler
mQ - required capacity
0
1000
2000
3000
4000
5000
0 500 1000 1500 2000 2500 3000 3500
kW
Working hours
Heating Capacity (kW) - Heat Load Curve
System "A" System "B"
System Capacity
Qc ηB ηC Τ
Calculate QB
Sizing of the boiler
(kW) (kW) (kW)
‘A’ 3,589 0.9 0.92 0.9 3,901 4,500
‘B’ 1,131 0.9 0.92 0.9 1,229 1,500
43
During winter, every heating system is a subject to great fluctuations that depend on the weather
and user’s habits. The maximum output power is utilized very shortly during periods of very cold
weather. Regularly, the boiler is operating for long intervals of time at low load. Therefore, it is
important for the boiler to be operated efficiently during off-peak periods. This can be achieved in
one of the following ways:
1. The biomass boiler can provide the maximum capacity, while a buffer (a hot water tank) covers
short-term load fluctuations and ensures that the boiler can be operated efficiently during off-peak
periods.
2. Combination of more biomass boilers. More boilers increase the reliability of supply and ensure
that the heating operates efficiently, even in off-peak periods.
Optimal model for biomass plant ‘A’ would be the solution with two wood chips heated boilers,
2,500kW + 2,000kW, and hot water tanks with 45m3 volume . One boiler would be used at higher
outside temperatures. In this way, the system would be efficient even in lower operating modes. For
biomass plant ‘B’, optimal model would be the solution with one wood chip heated boiler, 1500kW
and hot water tank with 15m3 volume. Existing boilers in aforementioned facilities would serve as a
backup solution.
Comparison of biomass and existing fuels is based on the full load hours of 808 kWh/kW. This
consumption value implies that the heating systems are in a maintenance mode after working hours
and in schools during winter holidays. According to this data, it is necessary to produce yearly
consumption of 3,815 MWh. The unit production cost of the heating energy, according to the solution
with wood chips as a fuel, is about 21.92 €/MWh. Current unit cost for buildings described in this
study, with existing heating systems, is up to 90.51 €/MWh.
44
6.2 HEATING PLANT, LOCATION AND FACILITIES
6.2.1 HEATING PLANT ‘А’
The plot intended for the construction of a new power plant is located on a part of cadastral plot
2308/1 CM Prokuplje with surface of 4,200m2. This location is on the site of the former landfill, on
the left bank of the Toplica River.
Figure 12 - Situation plan of heating plant ‘A’
Photo 45 - Location of the heating plant ‘A’
45
The heat source consists of two boilers capacity 2,000kW and 2,500kW, for combustion of biomass
with total nominal thermal capacity of 4,000 kW. In the plant with two boilers, stable operations are
ensured with low outdoor temperatures, as well as with higher outdoor temperatures. In cases of
higher outdoor temperatures, one boiler can provide sufficient heating, without the risk of cooling
entire system. The regime of the boiler temperature is 100/70°C. Maximum operating pressure is
6 bars. The minimum temperature return to boiler is 60°C. It is planned to install a buffer tank with
volume of 45 m3 in order to optimize the operation of the heat source. Circulator pumps are located
between the boiler and buffer tank, as well as three-way mixing valve in order to provide protection
for the cold parts of boilers.
For the purposes of technical calculation, the documentation was used made by ‘Topling-heating
Beograd’, including additional mechanisms for feeding fuel, extracting exhaust gases and ash. For
the purposes of circulation in the distribution system, circulation pump with inconstant flow and
pressure sensors are planned.
Construction of following facilities is envisaged at the site of future heating plant ‘A’:
Building A:
- Space to install biomass boilers with area of 250 m2 is needed for installation of following
boilers:
a) one boiler with capacity of 2,000 kW. Space necessary for operations of such boiler has
following dimensions: width x length x height = 6.8 x 9.2 x 5.8m
b) one boiler with capacity of 2,500kW. Space necessary for operations of such boiler has
following dimensions: width x length x height = 8.0 x 10.2 x 6.3m
The rest of a space is manipulative space for access to maintaining and safe passage.
- Space to install daily tank of woodchips with surface of 250 m2 and capacity of 100 m3,
i.e. 30 t, and space for daily fuel storage sufficient for 4 days of operations.
- The area of processing equipment (buffers, pumps, collectors) of 130 m2
- Office space of 50 m²
Building B:
- Wood chips storage for whole heating season and for both heating plants (‘A’+’B’), with
area of 2,640 m2 and minimum useful height of 7 m. Capacity of this storage is 5,270 m3 or
1,580 t of wood chips, which is sufficient for the needs of both heating plants to provide
energy for the heating of all public buildings.
Total area of buildings of the heating plant ‘A’ is 3,320 m2 (250+250+130+50+2,640 m2) and the
degree of availability of cadastral parcel is 80%.
46
6.2.2 HEATING PLANT ‘B’
The plot intended for the construction of a new power plant ‘B’ is located on a part of cadastral plot
1704/1 CM Prokuplje with surface of 1,500m2. The location is behind primary school ‘9. oktobar’ and
Sports hall ‘Dr. Zoran Đinđić’.
Figure 13 - Situation plan of heating plant ‘B’
The heat source consists of one boiler capacity 1,500kW, for combustion of biomass, and hot water
buffer tank with volume of 15 m3 in order to optimize the operation of the heat source. In the plant
with boiler and hot water buffer tank, stable operations are ensured with low outdoor temperatures,
as well as with higher outdoor temperatures. In cases of higher outdoor temperatures, one boiler
can provide sufficient heating, without the risk of cooling entire system. The regime of the boiler
temperature is 100/70°C. Maximum operating pressure is 6 bars. The minimum temperature return
to boiler is 60°C. Circulator pumps are located between the boiler and buffer tank, as well as three-
way mixing valve in order to provide protection for the cold parts of boilers.
For the purposes of technical calculation, the documentation was used made by ‘Topling-heating
Beograd’, including additional mechanisms for feeding fuel, extracting exhaust gases and ash. For
the purposes of circulation in the distribution system, circulation pump with inconstant flow and
pressure sensors is planned.
Construction of following facilities is envisaged at the site of future heating plant ‘B’:
47
Building A:
- Space to install biomass boilers with area of 150 m2 is needed for installation of a boiler
with capacity of 1,500 kW. Space necessary for operations of such boiler has following
dimensions: width x length x height = 6.8 x 9.2 x 5.8m
The rest of a space is manipulative space for access to maintaining and safe passage.
- Space to install daily tank of wood chips with area of 55 m2 and capacity of 22 m3 or 6.5 t
that is sufficient for 4 days of operations
- The area of processing equipment (buffers, pumps, collectors) with area of 50 m2
- Office space of 50 m²
Building B:
- Wood chips storage with area of 100 m2 and minimum useful height of 7 m. Capacity of
this storage is 190 m3 or 55 t of wood chips, which is average 4 weeks consumption in the
coldest period of a year. This storage would be supplied by wood chips from central storage
located in the complex of heating plant ‘A’
Total area of buildings of heating plant ‘B’ is 405 m2 (150+55+50+50+100 m2) and the degree of
availability of cadastral parcel is 27%.
48
6.3 CONCEPT OF DISTRICT HEATING NETWORK
6.3.1 CONCEPT OF DISTRICT HEATING NETWORK
Heating network is designed to connect aforementioned public buildings. The pipe network consists
of pre-insulated steel pipes that are installed directly in the prepared soil. Distribution network will
contain chambers with bulkhead valves.
Photo 46 - Pre-insulated pipes for the district heating network12
The quality of the pipes corresponds to 1.0254 i.e. P235
TR1 according to EN10217 T1 (or St.37.0 of the technical
requirements and delivery conditions according to
DIN1626). The operating temperatures at the threshold of
the heat source are:
- The flow temperature is 100℃,
- The return temperature is 70℃
The difference in altitude between the highest point of the
town (on the outskirts) and the lowest point is less than
30 m, so the lowest required operating pressure in the
pipeline is 6 bar.
Route of the pipeline runs through main streets, or through land plots owned by the City or by other
state body/ company. An example is cadastral plot No 5686, owned by Public Water Management
Company ‘Srbijavode’, necessary for connection of Technical school ’15. maj’ to the heating
network.
Before designing the heating network, it is necessary preparation of a document at the municipal
level, which will define the Prokuplje construction strategy and direction of the future development
of the city centre.
Concept plan of the heating network is preliminary, and designed for the planning of the budget
expenditures.
12 Source: Website of the company Konvar d.o.o., Belgrade
49
6.3.2 SCHEME OF DISTRICT HEATING NETWORK
Based on the position of public institution buildings, as well as on the position of the main town
streets, residential buildings and individual houses, heating network plan would be as follows:
Figure 14 - Disposition of drawings of the heating network per numbers
50
Figure 15 - Drawing No 1 of the heating network
51
Figure 16 - Drawing No 2 of the heating network
52
Figure 17 - Drawing No 3 of the heating network
53
Figure 18 - Drawing No 4 of the heating network
54
Figure 19 - Drawing No 5 of the heating network
55
Figure 20 - Drawing No 6 of the heating network
56
Figure 21 - Drawing No 7 of the heating network
57
Figure 22 - Drawing No 8 of the heating network
58
Dimensions of heating pipes for the network calculated with the planned reserve for future additions to the network:
Within the analysis, heating network is divided by the routes and transparent points, as shown on the drawings:
Type Route Distance Capacity of Unit price of network
of from to heat substations Dimension Total
route (m) (kW)
main A B 90 2200 DN150 310 27,900
main B C 95 2700 DN200 465 44,175
main C D 285 2900 DN200 465 132,525
main E E1 350 900 DN100 220 77,000
main F F1 100 500 DN80 175 17,500
main G G1 100 1000 DN125 265 26,500
connection A1 100 700 DN100 220 22,000
connection A2 160 1500 DN125 265 42,400
connection B1 110 500 DN80 175 19,250
connection C1 60 200 DN50 130 7,800
connection E1 10 900 DN100 220 2,200
connection F1 10 500 DN80 175 1,750
connection G1 10 1000 DN125 265 2,650
TOTAL 1,480 423,650
Table 27 - Sizing the pipe network by routes
According to the prices of units needed to construct a network of pre-insulated pipes, the costs of
the construction of heating network are estimated to 424,000 €. The additional costs of the
construction of the chamber with necessary fittings and installation of the fittings increase estimation
for 10%, leading to total costs of the heating network of 470,000 €.
Q - The amount of heat transported by the pipeline
w - Velocity of flow of the working fluid
ρ - Density of the working fluid
cp - Specific heat capacity
Δθ - Temperature difference
p
incw
QD
4
59
Calculation of operating point of the network pump is shown in the following Tables:
Table 28 - Calculation of operation point of network pump, heating plant ‘A’
Table 29 - Calculation of operation point of network pump, heating plant ‘B’
The operating point of the network pump (or a pair of network pumps, depending on the solution
adopted in the preliminary design) is as follows:
Heating plant ‘A’ Heating plant ‘B’
Flow l/h 95,000 50,000
Pressure drop kPa 87 55
Table 30 - Working points of circulation pumps for heating plant ‘A’ and ‘B’
The operating point is selected on a basis of the pressure drop in the hydraulically least favorable
heating substation.
Aimed to saving electricity for pumping the working fluid, it is necessary to incorporate the engine
frequency controls in order to optimize the operation of network pumps and synchronize it with the
actual required thermal energy to be delivered to the consumer.
Flow Lenght Speed
from to diemeter wall unit total friction local TOTAL
kW l/h m mm mm m/s Pa/m kPa kPa kPa
D C 2.900 85.508 90 219,1 5,9 0,704 22,08 1,987 3,603 5,590
C B 2.700 79.611 120 219,1 5,9 0,656 19,20 2,3 1,5 3,761
B A 2.380 70.175 150 168,3 4,5 0,979 58,36 8,8 3,2 12,001
6.3.3 CONCEPT OF HEATING SUBSTATIONS District heating transfer stations provide the link between district heating suppliers and the customers’ systems. They incorporate the necessary equipment to tailor the supplied heat to the needs of the user. Indirect connections (in which district heating and in-house systems are hydraulically isolated) incorporate components to separate the systems (heat exchanger), to limit the flow volume, regulate the secondary supply temperature and measure the energy consumption. Substations are designed for installation in already existing boiler rooms. The existing boilers will be reviewed in terms of functionality. Those that do not meet the minimum requirements for safe operations will be removed from the substations (i.e. from the existing boiler rooms). Those that meet the minimum technical requirements will remain as a backup heat source in case when, for any reason, the heating system goes into breakdown of operational mode; or to serve as back up heating source if there is an increase of heat consumption that cannot be foreseen at this moment. The operating pressure in the primary part of the substation will be up to 6 bars max., and will correspond to the parameters of the heating network, while the temperature range will be 100/70℃ in the primary part and 80/60℃ in the secondary part. The further development of the heating system, with a focus on the connection of residential buildings, would involve the installation of heating substations of the packet type in each building, with identical operating parameters as for heating substations in public institutions or business facilities.
Substations models DSP-MAXI are designed for power stronger than 100 kW. Substations DSA1-Mini are designed to power up to 100 kW and can be mounted on the wall. Heat substation should be dimensioned according to the size of the heat loss of the building. The reconstruction of the existing boiler rooms should be executed in a way that does not change the working fluid distribution system and the heating substation is connected to the existing supply and return collectors. The existing circulation pumps should be replaced by more energy-efficient units with motors of variable frequency, in order to achieve savings in power consumption and reduce heat dissipation in the buildings.
Estimation of operational costs (OPEX) predicts that after first 10 years, prices will stabilize and achieve small growth of 1% annually. In following 10 years, it is expected wood chips price increase up to 65€/t, and pellet price increase up to 220€/t. After this period, the price would continue growing per 1% annually. For the price of electricity, it is foreseen annual growth at a rate of 2.5%. Insurance costs are estimated for all of facilities, equipment, and installations built by the investment. Considering workforce, it is planned engagement of two highly technically educated employees and
one manager. Workers with lower qualifications would be replaced from existing assignments in the
facilities that are the subject of this study. Salaries costs would increase per annual rate of 1.5%.
Costs of cleaning exhaust systems and ash disposal are proportional to quantity of ash (2%) in
burned wood chips. Unit price of these costs would increase per annual rate of 1.5%.
18 Own calculations
65
8. PRELIMINARY FINANCIAL ANALYSIS
Sustainability of the plant will be analysed for a period of 20 years. Variations of operational costs
according to the structure for a period of 20 years are shown in tabular form. Analysis of operational
costs considers forecasts of price variations for each item.
Preliminary financial analysis consists of the table of costs of energy production, and following
figures, (enclosed in the Annex): comparative analysis of costs of heating energy and savings;
savings resulted by a fuel switch; operational costs and depreciation; comparison of total costs of
the existing and a new heating system; and cash flow.