*b) Projected solution*

The project consists of the substitution of existing boilers fed by fossil fuel by a CHP bio‐ mass facility, to heat public buildings and greenhouses as well as generate electricity. This will contribute to the reduction of CO2 emissions and to the improvement of the general liv‐ ing conditions of the local inhabitants. As a pilot project, it has the potential to serve as an example for profitable green energy production facilities with replication potential.

The project covers a new boiler house with cogeneration facility. The boiler house comprise following main elements, included in the business plan (Table 9.). In addition to the men‐ tioned units of the CHP facility, there are other infrastructural elements of the described technology, which have not been included in the business-plan, listed in Table 10.

**Boiler house element Preliminary data and description**

functional unit

**Infrastructural element Preliminary data and description**

Heating installations in the new greenhouse Same heating system as in the existing greenhouse Connecting the facility to the electric grid Installation of necessary electric poles and equipment

Machinery for gathering and transport of the biomass Machinery for provisioning the biomass reserves in

Construction project subjected to the CHP plant, in the suburb of Padinska Skela, near Bel‐ grade, presents the continuing efforts from Laboratory for thermal engineering and energy of Vinca Institute and Central European Initiative (CEI) to build such a plant in Serbia. CEI associates through implementation of projects BIOMADRIA and BIOMADRIA 2 recognized the importance of the construction of such a facility, as similar projects can be transferred to many places in Serbia, as well as in the surrounding countries, which also has an intensive

optimal conditions

Building for the accommodation of the equipment

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81

Development of the Technology for Combustion of Large Bales Using Local Biomass

Connecting the existing and new boiler house into a

Next to the boiler house, week bale storage is planned

The existing storage does not meet present requirements

CHP biomass facility with the auxiliary equipment 3000-4000 kW thermal + 400-600 kW electric (net)

Heat accumulator Matching the peaks in energy consumption

whole auxiliary equipment 3000-4000 kW (as a reserve)

Hot water heavy fuel oil (or light fuel oil) boiler with the

The boiler house building (the new boiler house is going

Reconstruction of the existing boiler house and

Automated bale storage and equipment for the bale

Pipeline for connecting the consumers with the new

Building of a central roofed storage of biomass for annual

**Table 10.** Infrastructural elements, not comprised by the business-plan

boiler house ≈1000 m pipeline

Communicational roads Hard material roads

to be connected to the existing one)

connection it with the new one

**Table 9.** The main project elements

manipulation

needs

c) *Project Implementation*

agricultural production.

The planned CHP facility is based on the two proven technologies:


Functional scheme of the CHP facility with the proposed combustion technology and the heat into electricity energy conversion technology is shown in Figure 27. The combustion technology (based on the cigarette type burning) has been described in detail in numerous papers [9, 10, 20], and has been developed up to industrial application, largely with help of Ministry of Education and Sciences of Republic of Serbia. Beside the cigarette combustion, this technology comprises some original technical solutions, considering the organization of biomass combustion completion in fluidized bed. This technology enables using balled agri‐ cultural residues (in form it has been collected on fields), with no additional transformation (chopping, grounding), which decreases fuel cost and pollution, and contributes to energy efficiency. This type of combustion has been marked as the most suitable way of combustion of agricultural biomass in EU [13]. This technology, proven in operation in PKB, is going to be applied for CHP facility and the supplemental (reserve) biomass boiler.

The cogeneration technology is ORC - Organic Rankin Cycle based. There are a number of well known producers of the equipment. The technology is used exclusively for power gen‐ eration in CHP facilities, with electric efficiency is up to 20% and overall efficiency of over 80%. More than 100 of facilities like that have been installed in EU, thus the technology could be considered proven.

Combining these two technologies would give the first experimental, demonstrational and industrial facility of the kind. It is going to be a good reference for all companies involved in the project. The facility is going to be built in PKB Company, and the company is going to supply it with the fuel (soy straw, rapeseed straw and cornstalk), which is a very convenient because they have an experience in operation with a similar boiler. Public Company "Bel‐ grade Plants" also owned by the city of Belgrade, should take part in design and construc‐ tion of the necessary infrastructure (connecting the existing system with the new one). It is necessary to note that a heat accumulator (hot water reservoir) is going to be built in scope of the boiler house in order to cover the peaks in energy consumption. It has been proven in operation with the existing cigarette type boiler in the PKB.


**Table 9.** The main project elements

The project covers a new boiler house with cogeneration facility. The boiler house comprise following main elements, included in the business plan (Table 9.). In addition to the men‐ tioned units of the CHP facility, there are other infrastructural elements of the described

**a.** The balled straw combustion technology (developed in Laboratory for Thermal Engi‐ neering and Energy of Vinca Institute of Nuclear Sciences, in cooperation with Compa‐ ny Tipo-Kotlogradnja, Belgrade), which has been applied in existing 1.5 MW facility

**b.** Organic Rankin Cycle (ORC) for electricity generation. ORC technology is based on tur‐ bines driven by silicone oil steam (although, steam of other liquids can be used).

Functional scheme of the CHP facility with the proposed combustion technology and the heat into electricity energy conversion technology is shown in Figure 27. The combustion technology (based on the cigarette type burning) has been described in detail in numerous papers [9, 10, 20], and has been developed up to industrial application, largely with help of Ministry of Education and Sciences of Republic of Serbia. Beside the cigarette combustion, this technology comprises some original technical solutions, considering the organization of biomass combustion completion in fluidized bed. This technology enables using balled agri‐ cultural residues (in form it has been collected on fields), with no additional transformation (chopping, grounding), which decreases fuel cost and pollution, and contributes to energy efficiency. This type of combustion has been marked as the most suitable way of combustion of agricultural biomass in EU [13]. This technology, proven in operation in PKB, is going to

The cogeneration technology is ORC - Organic Rankin Cycle based. There are a number of well known producers of the equipment. The technology is used exclusively for power gen‐ eration in CHP facilities, with electric efficiency is up to 20% and overall efficiency of over 80%. More than 100 of facilities like that have been installed in EU, thus the technology

Combining these two technologies would give the first experimental, demonstrational and industrial facility of the kind. It is going to be a good reference for all companies involved in the project. The facility is going to be built in PKB Company, and the company is going to supply it with the fuel (soy straw, rapeseed straw and cornstalk), which is a very convenient because they have an experience in operation with a similar boiler. Public Company "Bel‐ grade Plants" also owned by the city of Belgrade, should take part in design and construc‐ tion of the necessary infrastructure (connecting the existing system with the new one). It is necessary to note that a heat accumulator (hot water reservoir) is going to be built in scope of the boiler house in order to cover the peaks in energy consumption. It has been proven in

be applied for CHP facility and the supplemental (reserve) biomass boiler.

operation with the existing cigarette type boiler in the PKB.

technology, which have not been included in the business-plan, listed in Table 10.

The planned CHP facility is based on the two proven technologies:

used for heating greenhouses in PKB.

80 Sustainable Energy - Recent Studies

could be considered proven.


**Table 10.** Infrastructural elements, not comprised by the business-plan

### c) *Project Implementation*

Construction project subjected to the CHP plant, in the suburb of Padinska Skela, near Bel‐ grade, presents the continuing efforts from Laboratory for thermal engineering and energy of Vinca Institute and Central European Initiative (CEI) to build such a plant in Serbia. CEI associates through implementation of projects BIOMADRIA and BIOMADRIA 2 recognized the importance of the construction of such a facility, as similar projects can be transferred to many places in Serbia, as well as in the surrounding countries, which also has an intensive agricultural production.

installed power for the hospital, 38% for the school, 35% for the office building and 55%

Development of the Technology for Combustion of Large Bales Using Local Biomass

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83

Energy potential of renewable energy sources in the Republic of Serbia equals approximately 4.3 Mtoe/year. Biomass is deemed to be the main source of renewable energy, with estimated 2.7 Mtoe/year of energy potential, with 60% being the potential of agricultural biomass and the re‐ maining 40% being attributed to the forest biomass. Combustion of agricultural biomass was an‐ alyzed with respect to the cigar burner combustion technology, suitable for the whole-bale combustion. Technology developed was tested in the 75 kWth hot water boiler, 1 MWth demon‐ stration furnace and 1.5 MW industrial hot water boiler, where combustion of soybean and ra‐ peseed straw samples was investigated. Results obtained indicated that combustion technology developed was very convenient for combustion of biomass varieties characterized by high ash melting temperatures. A cigar firing combustion system is expected to exhibit the following ad‐ vantageous features: a) combustion of whole bales and whole energy crops; b) compact combus‐ tor design; c) short start up period, good load-following performance; d) profitable operation of smaller facilities (down to 1 MWth); e) division of combustion from the heat recovery system, usable not only for the provision of steam (for heat generation or CHP), but also as a hot gas gen‐

Cigar burner combustion system promises a more competitive use of renewable for "green" heat and power generation as well as their use in various industrial applications. In the same time, biomass combustion in cigar burners was modeled by appropriately developed numerical model. The model developed enabled the effect of fuel moisture content on the temperature distribution in the furnace to be analyzed, as well as related emissions of harm‐ ful combustion products into the environment. Research investigation conducted has dem‐ onstrated that high combustion temperatures can be achieved in furnaces used for the combustion of agricultural biomass and that achieved CO and NOx emission levels are low‐

The paper has been realized in scope of Ministry of Education and Science of Republic of Serbia's project "Development and improvement of technologies for energy efficient and en‐ vironmentally sound use of several types of agricultural and forest biomass and possible uti‐

er than the regulatory emission limit values defined by Serbian legislation.

for the greenhouses.

erator in industrial drying applications.

**Acknowledgements**

lization for cogeneration", Record number III42011.

**5. Conclusions**

**Figure 27.** Functional scheme of the combined heat and power facility

The time needed for the full implementation of the project is 1.5 years starting from the date of loan approval and the first disbursement (6 months for preparations, obtaining all neces‐ sary permissions and licenses, and designing; 8 months for the building the facility, and 4 months for its commissioning). The service lifetime of the CHP plant would be 25 years, which is a commonly accepted lifetime with proper maintenance.

d) CHP facility parameters

Plant parameters are determined on basis of heat demand. In this case, the analysis is com‐ plicated by different heating dynamics of the consumers (greenhouses, office building, school, hospital). The school has a different heating dynamic compared to the hospital, and all this is completely different from the dynamics of greenhouse heating system, e.g. the greenhouse needs heating at night while hospitals and schools are heated during the day. The consumers' heat demand has been carried out in the three steps:


installed power for the hospital, 38% for the school, 35% for the office building and 55% for the greenhouses.
