Rastko Mladenovic - Academia.edu (original) (raw)
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Papers by Rastko Mladenovic
Energy and Buildings, Apr 1, 2005
This paper presents selected results obtained by experimental investigation and modeling of flow ... more This paper presents selected results obtained by experimental investigation and modeling of flow and heat transfer processes, considering heat exchanger built within an originally developed concept of a household furnace, with convective canals. High efficiency, low emission, firing of both low- and high-rank solid fuels, considerable energy savings, as well as a pleasant heated ambient could be considered as advantages
Fuel, 2007
Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio us... more Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio using high-temperature steam, mean mass diameter of pulverized coal and coal size fraction on basic characteristics of coal gasification were performed. Experiments were carried out on a laboratory scale (0.09m i.d.×1.5m high) coal gasification apparatus with lignite type of coal. Influence of steam was realized through comparison of
18th International Conference on Fluidized Bed Combustion, 2005
The results of the detailed investigations of behavior of lignites Kolubara and Kovin, in fluidiz... more The results of the detailed investigations of behavior of lignites Kolubara and Kovin, in fluidized bed combustion are presented in the paper. Investigation was carried out due to the interest of the Serbian Electric Power Production Company to use CFBC boilers in the process of refurbishment of old pulverized coal combustion boilers. As a part of a feasibility study for CFBC use in power plants in Serbia, investigation of combustion characteristics of lignites was performed using original methodology introduced many years ago by Laboratory for Thermal Engineering and Energy. Methodology was approved by numerous investigations of more than 20 Yugoslav coals for FBC combustion, with the aim to determine design data for bubbling FBC boilers. The main attention in present investigation was paid to the problem of using methodology developed for bubbling FBC in the conditions present in CFBC boilers. Four samples of Kolubara lignite, with heat capacity from 2.5 to 8.5 MJ/kg, and different ash contents were investigated, and also lignite Kovin in the same range of heat capacity. Investigations were performed in three phases: (1) ultimate and proximate analysis, determination of ash sintering temperature by standard method and in fluidized bed laboratory oven, (2) investigations in laboratory fluidized bed furnace and determination of coal particle fragmentation, burning rate, start-up temperature and self-sulfure-capture and (3) investigation of combustion in pilot-plant in stationary combustion conditions. In conclusion, suitability of results obtained in BFBC conditions is approved, and earlier statement that lignites are suitable for BFBC is confirmed by the statement that lignites are even more suitable for burning in CFBC boilers. Considering differences between combustion and flow conditions in bubbling and circulating FBC boilers, behavior of the lignites in CFBC is discussed in details and optimal regime parameters of the CFBC boilers are determined. The results obtained will be used by Serbian Electric Power Production Company for evaluation of bid for CFBC boiler implementation in refurbishment of old thermal power plants.© 2005 ASME
Thermal Science, 2009
Based on investigations of ash deposit formation, semi-empirical indicators for slagging and foul... more Based on investigations of ash deposit formation, semi-empirical indicators for slagging and fouling, based on ash chemical composition and its fusion temperature, have been determined. These criteria-indicators, in suggested limits, describe the coals on which they are based (North-American and British) well. However, the experience in the thermal power production sector of Serbia shows that their literal application to domestic coals does not produce satisfactory results. This contribution provides an analysis of applicability and the choice of criteria that are suitable for Serbian coals. The focus of the contribution is on coal slagging indicators, since slagging has much heavier consequences on heat transfer inside the steam boiler, and on boiler operation as a whole. The basis for the analysis of chosen criteria comprises of the results of investigations of four coal fields - Kostolac, Kolubara, Kosovo (Serbia), and Ugljevik (Bosnia and Herzegovina).
Thermal Science, 2006
Many households in Serbia, using electric thermo-accumulation furnaces for heating, have been for... more Many households in Serbia, using electric thermo-accumulation furnaces for heating, have been forced to find an alternative solution, due to a significant increase in electricity prices during the last decade. A possible solution is replacing electric heating appliances with the solid fuel-fired ones. A prototype of a new concept of thermo-accumulation solid fuel-fired furnace has been developed to meet these growing needs, providing electricity saving together with considerable environmental benefits. Two strategies for reduction of carbon monoxide emission are examined in the paper: application of Pt/Al2O3 catalyst, in the form of 3 ? 0.3 mm spheres, providing further combustion of flue gases within the furnace, as well as an additional emission reduction by means of the air excess control. Experimental investigations of the catalyst influence on the conversion of carbon monoxide have been done for different operation regimes and positions of the catalyst. The paper presents selec...
Thermal Science, 2012
In this paper a method of examination of fuel suitability for fluidized bed combustion is present... more In this paper a method of examination of fuel suitability for fluidized bed combustion is presented. The research of combustion characteristics of low grade fractions of Lubnica brown coal in the fluidized bed by the aforementioned methodology has been carried out on a laboratory semi-industrial apparatus of 200 kWt. Description of the experimental fluidized bed combustion facility is given, as well as experimental results, with the focus on furnace temperature distribution, in order to determine the location of the zone of intensive combustion. Based on investigation results, which are focused on combustion quality (combustion completion) as well as on satisfying the environmental protection criteria, it can be stated that the investigated coal is suitable for burning in bubbling, as well as in circulating fluidized bed.
Journal of the Serbian Chemical Society, 2007
A prototype of a solid fuel thermo-accumulating furnace has been developed. In order to achieve a... more A prototype of a solid fuel thermo-accumulating furnace has been developed. In order to achieve a higher combustion efficiency, a Pt/Al2O3 catalyst in the form of 3 ? 0.3 mm spheres was applied, which enabled further combustion of flue gases within the furnace. Experimental investigation of the influence of the catalyst on the conversion of CO has been done for different operation regimes and positions of the catalyst. Paper presents selected results regarding CO emission during wood and coal combustion. Investigations suggest a considerable effect of the catalyst and a strong influence of the catalyst position to CO emission reduction. The microstructure of the catalyst beads, characterized by selective chemisorption of CO, has shown the decrease of the number of Pt sites as a consequence of blockage by coke deposits formed during the combustion of solid fuel. .
International Journal of Heat and Mass Transfer, 2009
Fuel, 2007
Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio us... more Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio using high-temperature steam, mean mass diameter of pulverized coal and coal size fraction on basic characteristics of coal gasification were performed. Experiments were carried out on a laboratory scale (0.09m i.d.×1.5m high) coal gasification apparatus with lignite type of coal. Influence of steam was realized through comparison of
Applied Thermal Engineering, 2007
Due to a significant increase in electricity prices during the last decade and insufficient produ... more Due to a significant increase in electricity prices during the last decade and insufficient production capacity of the electric power industry in Serbia, many households that are currently using electric heat storage furnaces for heating have been forced to find an alternative solution for heating. A possible solution is replacing electric heating appliances with similar solid fuel-fired ones. Existing solid
Thermal Science, 2008
There is a growing need for the use of alternative and renewable energy sources, in terms of sust... more There is a growing need for the use of alternative and renewable energy sources, in terms of sustainable energy development. One of the potentially biggest renewable energy sources in Serbia is agricultural biomass, quite available and cheap at the moment. For many years, the Vinca Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, has been working on the development of clean technologies for efficient utilization of biomass, and as a result utilities and equipment (boilers and furnaces) with wide range of use have been developed. These devices have complete combustion control and primarily burn baled biomass with no adequate utilization. The results of the development and of the tests of an experimental demonstrativel boiler burning small bales of soya straw have been presented in this paper. In the boiler, the combustion has been organized on the 'cigarette burning' principle, and fuel feeding has been done by gravity. The technical scheme of the...
Energy and Buildings, Apr 1, 2005
This paper presents selected results obtained by experimental investigation and modeling of flow ... more This paper presents selected results obtained by experimental investigation and modeling of flow and heat transfer processes, considering heat exchanger built within an originally developed concept of a household furnace, with convective canals. High efficiency, low emission, firing of both low- and high-rank solid fuels, considerable energy savings, as well as a pleasant heated ambient could be considered as advantages
Fuel, 2007
Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio us... more Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio using high-temperature steam, mean mass diameter of pulverized coal and coal size fraction on basic characteristics of coal gasification were performed. Experiments were carried out on a laboratory scale (0.09m i.d.×1.5m high) coal gasification apparatus with lignite type of coal. Influence of steam was realized through comparison of
18th International Conference on Fluidized Bed Combustion, 2005
The results of the detailed investigations of behavior of lignites Kolubara and Kovin, in fluidiz... more The results of the detailed investigations of behavior of lignites Kolubara and Kovin, in fluidized bed combustion are presented in the paper. Investigation was carried out due to the interest of the Serbian Electric Power Production Company to use CFBC boilers in the process of refurbishment of old pulverized coal combustion boilers. As a part of a feasibility study for CFBC use in power plants in Serbia, investigation of combustion characteristics of lignites was performed using original methodology introduced many years ago by Laboratory for Thermal Engineering and Energy. Methodology was approved by numerous investigations of more than 20 Yugoslav coals for FBC combustion, with the aim to determine design data for bubbling FBC boilers. The main attention in present investigation was paid to the problem of using methodology developed for bubbling FBC in the conditions present in CFBC boilers. Four samples of Kolubara lignite, with heat capacity from 2.5 to 8.5 MJ/kg, and different ash contents were investigated, and also lignite Kovin in the same range of heat capacity. Investigations were performed in three phases: (1) ultimate and proximate analysis, determination of ash sintering temperature by standard method and in fluidized bed laboratory oven, (2) investigations in laboratory fluidized bed furnace and determination of coal particle fragmentation, burning rate, start-up temperature and self-sulfure-capture and (3) investigation of combustion in pilot-plant in stationary combustion conditions. In conclusion, suitability of results obtained in BFBC conditions is approved, and earlier statement that lignites are suitable for BFBC is confirmed by the statement that lignites are even more suitable for burning in CFBC boilers. Considering differences between combustion and flow conditions in bubbling and circulating FBC boilers, behavior of the lignites in CFBC is discussed in details and optimal regime parameters of the CFBC boilers are determined. The results obtained will be used by Serbian Electric Power Production Company for evaluation of bid for CFBC boiler implementation in refurbishment of old thermal power plants.© 2005 ASME
Thermal Science, 2009
Based on investigations of ash deposit formation, semi-empirical indicators for slagging and foul... more Based on investigations of ash deposit formation, semi-empirical indicators for slagging and fouling, based on ash chemical composition and its fusion temperature, have been determined. These criteria-indicators, in suggested limits, describe the coals on which they are based (North-American and British) well. However, the experience in the thermal power production sector of Serbia shows that their literal application to domestic coals does not produce satisfactory results. This contribution provides an analysis of applicability and the choice of criteria that are suitable for Serbian coals. The focus of the contribution is on coal slagging indicators, since slagging has much heavier consequences on heat transfer inside the steam boiler, and on boiler operation as a whole. The basis for the analysis of chosen criteria comprises of the results of investigations of four coal fields - Kostolac, Kolubara, Kosovo (Serbia), and Ugljevik (Bosnia and Herzegovina).
Thermal Science, 2006
Many households in Serbia, using electric thermo-accumulation furnaces for heating, have been for... more Many households in Serbia, using electric thermo-accumulation furnaces for heating, have been forced to find an alternative solution, due to a significant increase in electricity prices during the last decade. A possible solution is replacing electric heating appliances with the solid fuel-fired ones. A prototype of a new concept of thermo-accumulation solid fuel-fired furnace has been developed to meet these growing needs, providing electricity saving together with considerable environmental benefits. Two strategies for reduction of carbon monoxide emission are examined in the paper: application of Pt/Al2O3 catalyst, in the form of 3 ? 0.3 mm spheres, providing further combustion of flue gases within the furnace, as well as an additional emission reduction by means of the air excess control. Experimental investigations of the catalyst influence on the conversion of carbon monoxide have been done for different operation regimes and positions of the catalyst. The paper presents selec...
Thermal Science, 2012
In this paper a method of examination of fuel suitability for fluidized bed combustion is present... more In this paper a method of examination of fuel suitability for fluidized bed combustion is presented. The research of combustion characteristics of low grade fractions of Lubnica brown coal in the fluidized bed by the aforementioned methodology has been carried out on a laboratory semi-industrial apparatus of 200 kWt. Description of the experimental fluidized bed combustion facility is given, as well as experimental results, with the focus on furnace temperature distribution, in order to determine the location of the zone of intensive combustion. Based on investigation results, which are focused on combustion quality (combustion completion) as well as on satisfying the environmental protection criteria, it can be stated that the investigated coal is suitable for burning in bubbling, as well as in circulating fluidized bed.
Journal of the Serbian Chemical Society, 2007
A prototype of a solid fuel thermo-accumulating furnace has been developed. In order to achieve a... more A prototype of a solid fuel thermo-accumulating furnace has been developed. In order to achieve a higher combustion efficiency, a Pt/Al2O3 catalyst in the form of 3 ? 0.3 mm spheres was applied, which enabled further combustion of flue gases within the furnace. Experimental investigation of the influence of the catalyst on the conversion of CO has been done for different operation regimes and positions of the catalyst. Paper presents selected results regarding CO emission during wood and coal combustion. Investigations suggest a considerable effect of the catalyst and a strong influence of the catalyst position to CO emission reduction. The microstructure of the catalyst beads, characterized by selective chemisorption of CO, has shown the decrease of the number of Pt sites as a consequence of blockage by coke deposits formed during the combustion of solid fuel. .
International Journal of Heat and Mass Transfer, 2009
Fuel, 2007
Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio us... more Experimental investigations of the influence of excess oxygen coefficient, H2O/coal mass ratio using high-temperature steam, mean mass diameter of pulverized coal and coal size fraction on basic characteristics of coal gasification were performed. Experiments were carried out on a laboratory scale (0.09m i.d.×1.5m high) coal gasification apparatus with lignite type of coal. Influence of steam was realized through comparison of
Applied Thermal Engineering, 2007
Due to a significant increase in electricity prices during the last decade and insufficient produ... more Due to a significant increase in electricity prices during the last decade and insufficient production capacity of the electric power industry in Serbia, many households that are currently using electric heat storage furnaces for heating have been forced to find an alternative solution for heating. A possible solution is replacing electric heating appliances with similar solid fuel-fired ones. Existing solid
Thermal Science, 2008
There is a growing need for the use of alternative and renewable energy sources, in terms of sust... more There is a growing need for the use of alternative and renewable energy sources, in terms of sustainable energy development. One of the potentially biggest renewable energy sources in Serbia is agricultural biomass, quite available and cheap at the moment. For many years, the Vinca Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, has been working on the development of clean technologies for efficient utilization of biomass, and as a result utilities and equipment (boilers and furnaces) with wide range of use have been developed. These devices have complete combustion control and primarily burn baled biomass with no adequate utilization. The results of the development and of the tests of an experimental demonstrativel boiler burning small bales of soya straw have been presented in this paper. In the boiler, the combustion has been organized on the 'cigarette burning' principle, and fuel feeding has been done by gravity. The technical scheme of the...