Tag Archives: calorific value

656-668 A. Brunerová, H. Roubík, M. Brožek and J. Velebil
Agricultural residues in Indonesia and Vietnam and their potential for direct combustion: with a focus on fruit processing and plantation crops
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Agricultural residues in Indonesia and Vietnam and their potential for direct combustion: with a focus on fruit processing and plantation crops

A. Brunerová¹*, H. Roubík², M. Brožek¹ and J. Velebil³

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Kamýcká 129, CZ165 00 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences, Department of Sustainable Technologies, Kamýcká 129, CZ165 00 Prague, Czech Republic
³Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 00 Prague, Czech Republic
*Correspondence: brunerova@tf.czu.cz

Abstract:

Energy consumption in Indonesia and Vietnam has grown rapidly in recent decades. To meet the energy needs of both countries, a higher utilisation of waste biomass sources may represent an adequate solution. Investigated samples represent major crop residues (waste biomass) originating mainly from the agriculture sector of the selected countries. Herbaceous waste biomass from Indonesia is, namely, cassava stems and root peelings (Manihot esculenta), coffee leaves (Coffea arabica), cacao leaves (Theobroma cacao), banana leaves (Musa acuminata), bamboo leaves (Bambusoideae spp.) and aloe vera leaves (Aloe vera). Furthermore, fruit and aquatic waste biomass originating from Vietnam is, specifically, sugarcane bagasse (Saccharum officinarum), durian peelings (Durio zibethinus), rambutan peelings (Nephelium lappaceum), banana peelings (Musa acuminata), water milfoil (Myriophyllum spicatum) and water hyacinth (Eichhornia crassipes). All mentioned types of waste biomass were subjected to proximate and calorimetric analysis: moisture, ash and volatile matter contents (%) and higher and lower heating values (MJ kg–1). Obtained values indicated the highest level of ash content in fruit biomass samples in the case of sugarcane bagasse (0.84%), in herbaceous biomass in the case of cassava stems (3.14%) and in aquatic biomass in the case of water hyacinth (14.16%). The highest levels of lower heating values were achieved by following samples (best samples from each biomass type): cassava stems (17.5 MJ kg–1); banana peelings (17.3 MJ kg–1) and water hyacinth (12.8 MJ kg–1). The overall evaluation of all observed samples indicated that the best suitability for energy utilisation by direct combustion of investigated representatives is fruit waste biomass, followed by herbaceous waste biomass and then aquatic waste biomass.

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474-482 M. Križan, K. Krištof, M. Angelovič, J. Jobbágy and O. Urbanovičová
Energy potential of densified biomass from maize straw in form of pellets and briquettes
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Energy potential of densified biomass from maize straw in form of pellets and briquettes

M. Križan, K. Krištof*, M. Angelovič, J. Jobbágy and O. Urbanovičová

University of Agriculture in Nitra, Faculty of Engineering, Department of Machines and Production Biosystems, Tr. A. Hlinku 2, SK94976 Nitra, Slovakia
*Correspondence: koloman.kristof@uniag.sk

Abstract:

The aim of the study was the evaluation and comparison of energy potential of briquettes and pellets produced from the maize straw and woody biomass based on various diameters of pellets. By experimental measurements a calorific value and ash content was observed. Calorific value was measured by laboratory calorimeter IKA C 6000 (IKA® Works, Inc., USA) and laboratory combustion chamber Lindberg/Blue M (Thermo Fisher Scientific, Inc., USA). Individual calorific values and ash content was observed and subsequently confronted to obtain differences with replication. The analysis showed that calorific value of pellets with diameter 6 mm ranged from 16.99 MJ kg-1 to 17.80 MJ kg-1. Calorific value of pellets with 8 mm diameter ranged from 16.63 MJ kg-1 to 17.20 MJ kg-1. However, compared calorific value of briquettes ranged from 14.99 MJ kg-1 to 15.66 MJ kg-1. Further analysis showed that ash content of samples varied as well and it’s even affected by diameter of pellets. While ash content of pellets with diameter 6 mm was observed as 4.9% of total volume in case of pellets with 8 mm it was observed at value 5.5%. Briquettes produced from maize straw have ash content at value 5.4%. In contrary, ash content of woody biomass was significantly higher, 11% of volume, specifically. At the basis of observed parameters it can be concluded that maize straw densified in form of briquettes and pellets have a great energy potential which is comparable and competitive with currently used materials for production of briquettes and pellets.

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276-285 B. Tamelová, J. Malaťák and J. Velebil
Energy valorisation of citrus peel waste by torrefaction treatment
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Energy valorisation of citrus peel waste by torrefaction treatment

B. Tamelová*, J. Malaťák and J. Velebil

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamycka 129, CZ165 21 Prague, Czech Republic
*Correspondence: tamelova@tf.czu.cz

Abstract:

The article deals with the issue of processing and utilization of citrus peel, which often ends unused with other biodegradable waste. The research is concerned with the energy potential of this raw material and its torrefaction conversion. The tested materials were orange peel (Citrus sinensis Osbeck cv ‘Valencia’, Citrus sinensis Osbeck cv ‘Murcia’) and grapefruit peel (Citrus paradise ‘Ruby red’). Samples of dried materials underwent torrefaction treatment at 225 °C, 250 °C and 275 °C for 30 minutes. Samples before and after torrefaction were analysed for proximate and elemental composition and for calorific value. Consequently, stoichiometric combustion analyses were done. The torrefaction was performed in a LECO TGA 701 thermogravimetric analyzer under nitrogen atmosphere. The results of proximate and elemental analysis showed positive influence of torrefaction on the samples. The highest net calorific value for orange peel is 24.97 MJ kg-1 at the temperature of 275 °C. The greatest differences in net calorific values are between 225 °C and 250 °C where the increase is almost 3 MJ kg-1. Subsequently, the increase between the 250 °C and 275 °C torrefaction temperatures is 1 MJ kg-1. Weight loss at respective torrefaction temperatures showed similar time-dependent curves for all samples. Stoichiometric combustion analysis shows slight differences between original samples, but great differences after torrefaction processing. Stoichiometric combustion parameters also change proportionately with increasing temperature of torrefication. The resulting comnbustion balance figures show significantly lower need for mass of fuel in the case of the torrefied material for a given heat output thanks to the net calorific value being nearly doubled.

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1084–1093 J. Malaťák, J. Bradna and J. Velebil
The dependence of COx and NOx emission concentrations on the excess air coefficient during combustion of selected agricultural briquetted by-products
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The dependence of COx and NOx emission concentrations on the excess air coefficient during combustion of selected agricultural briquetted by-products

J. Malaťák*, J. Bradna and J. Velebil

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: malatak@tf.czu.cz

Abstract:

The issue of CO, CO2 and NOx emissions is very extensive and important. The aim of the paper is the experimental determination of the CO, CO2 and NOx emission dependencies on the amount of excess air. Materials used for the experiments were several types of briquetted biomass. Crops used were Czech knotweed (Reynoutria × bohemica), Rumex hybrid OK 2 (Rumex patientia × Rumex tianschanicus), meadow hay and timothy grass (Phleum pratense). For all samples proximate and elemental analyses were performed (semiautomatic calorimeter LECO AC-600 elemental analyser CHN628 + S and analyser LECO TGA-701) and stoichiometric calculations of combustion were made. Combustion device used in combustion tests was a hot air stove with a grate fireplace and with manual fuel supply. The combustion process was monitored by analyser Madur GA-60. Parameters monitored during the combustion tests were primarily the flue gas temperature and the emission levels of carbon monoxide, carbon dioxide and nitrogen oxides.
Analyses and calculations of plant biomass samples indicate their good properties for energy use. The gross calorific value was as high as 19.55 MJ.kg-1 in the sample of Rumex OK 2. Limiting factor is the high quantity of ash in plant material. The briquettes from timothy grass achieved 5.77% wt. ash in the dry matter. The excess combustion air had positive influence during combustion test. On the other hand, this caused heat loss by departing flue gases, wherein the flue gas temperature reached high values. The excess air coefficient also significantly affected the emission levels of carbon dioxide and monoxide and nitrogen oxides in the flue gases. Results were statistically analysed and complemented by regression equations, which in practice can be used to optimize the combustion process in boilers with manual fuel supply.

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344–358 A. Brunerová, M. Brožek and M. Müller
Utilization of waste biomass from post–harvest lines in the form of briquettes for energy production
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Utilization of waste biomass from post–harvest lines in the form of briquettes for energy production

A. Brunerová*, M. Brožek and M. Müller

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Material Science and anufacturing Technology, Kamýcká 129, CZ165 00 Prague, Czech Republic *Correspondence:brunerova@tf.czu.cz

Abstract:

A great amount of herbal waste biomass is produced nowadays during agriculture crop processing; also during ‘post–harvest lines’ operations. Such waste biomass occurs in the bulk form, thus, is not suitable for direct combustion; it can be improved by using of briquetting technology. Therefore, present paper provides chemical, mechanical and microscopic analyses of waste biomass originating from post–harvest lines and briquettes produced from it. Namely, waste biomass originated from production of oat (Avena sativa) – husks, wheat (Triticum spp.) – husks and poppy (Papaver somniferum) – straw and seed pods and mixture of all mentioned were investigated. Unprocessed materials were subjected to microscopic and chemical analysis and subsequently produced briquette samples were subjected to determination of its mechanical quality. A satisfactory level of moisture and ash content was observed, as well as, materials energy potential; oat – 17.39 MJ kg-1, wheat – 17.04 MJ kg-1, poppy – 14.48 MJ kg-1. Also microscopic analysis proved suitability of all feedstock materials within evaluation of geometrical shapes of their particles. However, evaluation of briquette mechanical quality unsatisfactory results. Process of briquetting revealed unsuitability of oat feedstock for briquette production; other materials proved following values of volume density and mechanical durability (in sequence): wheat – 1,023.19 kg m-3, 89.1%; poppy – 1,141.43 kg m-3, 94.7%; mixture – 972.49 kg m-3, 62.7%. In general, only poppy briquettes achieved requested mechanical quality level for commercial briquette production. However, undeniable advantage of investigated materials is the form they occurred in; no further feedstock preparation (drying, crushing) was needed.

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359–368 A. Brunerová, J. Malaťák, M. Müller, P. Valášek and H. Roubík
Tropical waste biomass potential for solid biofuels production
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Tropical waste biomass potential for solid biofuels production

A. Brunerová¹*, J. Malaťák², M. Müller¹, P. Valášek¹ and H. Roubík³

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Kamýcká 129, CZ165 00 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 00 Prague, Czech Republic
³Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences, Department of Sustainable Technologies, Kamýcká 129, CZ165 00 Prague, Czech Republic
*Correspondence: brunerova@tf.czu.cz

Abstract:

Subsequent utilization of waste biomass in developing countries occurs at poor level, despite the  act, that it has great potential in solid biofuel production. Densified waste biomass is utilized for  direct combustion, therefore, its suitability (energy potential, chemical composition) must be determined in attempt to protect environment and reduce air pollution. Main aim of present research was to determine suitability of waste biomass originating from production of rice (Oryza sativa), Date fruit (Phoenix dactylifera L.) and Jatropha fruit (Jatropha curcas) for solid biofuel production. Within a moisture, ash and volatile matter contents, major chemical elements (C, H, N, O) and net calorific value (NCV) were determined. Rice waste analysis proved low NCV (14.33 MJ kg–1) and high ash content (20.74%), which presented problems during combustion. Jatropha fruit waste (cake) analyses exhibited outstanding NCV (24.44 MJ kg–1) caused by residual oil content. Within major elements analysis a low content of oxygen (26.61%) was proved (recommended). Date fruit waste exhibited average NCV (16.40 MJ kg–1). However, high oxygen content (44.01%) was defined as limiting factor. Overall evaluation proved greatest suitability for Jatropha fruit waste (cake), followed by Date fruit waste and lowest potential was determined for Rice waste. However, investigated plants are not cultivated for energy production purposes, thus, observed results achieved satisfactory level of their suitability for solid biofuel production.

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614–623 J. Velebil, J. Malalák and J. Bradna
Mass and energetic yields of hydrochar from brewer’s spent grain
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Mass and energetic yields of hydrochar from brewer’s spent grain

J. Velebil*, J. Malalák and J. Bradna

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ 165 21 Prague, Czech Republic
*Correspondence: velebil@tf.czu.cz

Abstract:

 Brewer’s spent grain (BSG) was hydrothermally carbonized at combinations of three temperatures (180 °C, 215 °C, 250 °C) and three reaction times (2 h, 5 h, 12 h). For comparison, the corresponding barley malt was also tested at the same conditions. Elemental composition, volatile matter, ash and heating values were determined for original biomasses as well as resulting hydrochars. The mass yield of dry BSG hydrochar ranged from 45 to 73%. The energetic yield defined as retention of total lower heating value in the hydrochar on dry basis ranged from 66 to 85%. Specific lower heating value of dry material rose from 20.6 MJ kg-1 to 30.3 MJ kg-1 at the most severe conditions. Nitrogen and sulphur content in hydrochar were not strongly dependent on reaction conditions.

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525–532, J. Malaták, J. Bradna and J. Velebil
Combustion of briquettes from oversize fraction of compost from wood waste and other biomass residues
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Combustion of briquettes from oversize fraction of compost from wood waste and other biomass residues

J. Malaták*, J. Bradna and J. Velebil

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ 165 21 Prague, Czech Republic
*Correspondence: malatak@tf.czu.cz

Abstract:

This article aims to determine experimentally the energy potential of samples from oversize compost fraction formed into briquettes. Theoretical combustion characteristics of the briquettes are determined and are compared with a reference fuel. Elemental analysis and stoichiometric calculations were performed for the samples. Classical grate combustion device with manual fuel supply was chosen for combustion tests. Flue gas temperature and emission parameters, such as the emission levels of carbon monoxide, carbon dioxide and nitrogen oxides, were monitored by a multi-purpose flue gas analyzer Madur GA-60. Dependence of these parameters on air input was followed.
Elemental analyses and stoichiometric calculations of individual samples indicate favourable properties of the energy compost for further energy utilisation, namely the gross calorific value of 16.42 MJ kg-1. Excess air was causing high losses through heat of the flue gas during the experiments on combustion device. This fact occurred in a situation when the temperature of flue gas leaving the chimney reached high levels. The excess air coefficient also significantly influenced emissions of carbon dioxide and monoxide and nitrogen oxides in the flue gas. The trends are analysed statistically and are expressed by regression equations. The results can serve in practice for optimization of combustion processes in grate boilers with manual feed of the fuel.

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259–268 D. Streikus, A. Jasinskas, M. Arak, E. Jotautienė1, R. Mieldažys, S. Čekanauskas and Z. Jankauskienė
Investigations of fibre plants preparation and utilization of solid biofuels
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Investigations of fibre plants preparation and utilization of solid biofuels

D. Streikus¹, A. Jasinskas¹*, M. Arak², E. Jotautienė1, R. Mieldažys¹, S. Čekanauskas³ and Z. Jankauskienė⁴

¹Aleksandras Stulginskis University, Faculty of Agricultural Engineering, Institute of
Agricultural Engineering and Safety, Kaunas-Akademija, Studentu str. 15A, LT-53361
Kaunas r., Lithuania
²Estonian University of Life Sciences, Institute of Technology, Fr.R. Kreutzwaldi 56,
EE51014 Tartu, Estonia
³Aleksandras Stulginskis University, Experimental Station, Kaunas-Akademija,
LT-53361 Kaunas r., Lithuania
⁴Lithuanian Research Centre for Agriculture and Forestry, Upyte Experimental Station,
Linininku str. 3, Upyte, LT-38294 Panevezys r., Lithuania
*Correspondence: algirdas.jasinskas@asu.lt

Abstract:

Presented research results of technological-technical means and operations for solid biofuel preparation: chopping, milling, pelleting and burning of fibre plants – 3 sorts of fibre hemp (Beniko, Bialobrzeskie and Epsilon 68) and fibre nettle (sown in 60 x 60 cm). These fibre plants were grown in the experimental fields of Lithuanian Research Centre for Agriculture and Forestry, Upytė Experimental Station, and in Aleksandras Stulginskis University were investigated the technical means of these plants preparation and usage for energy purposes. It was used the standard methodology for solid biofuel preparation of fibre plants, and was investigated the technique for plant chopping, milling and pelleting. There were determined fibre plant mill fractional composition while usage the hummer miller prepared mill. There were determined the fibre plant pellet quality indicators – moisture content and bulk density. The fibre plant pellet moisture content ranged from 6.4% to 8.8%, and pellet density reached 1,082.7–1,186.2 kg m-3 DM (dry matter). Pellet elemental composition, ash content and calorific value were determined at the Lithuanian Energy Institute. The ash content after the burning of fibre plant pellet was not high and varied from 3.6 to 5.9%. Determined net calorific value of fibre hemp and fibre nettle dry mass was relatively high 17.2–17.5 MJ kg-1, it was close to calorific value of some wood species.

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17-24 A. Beloborodko, L. Timma, A. Žandeckis and F. Romagnoli
The regression model for the evaluation of the quality parameters for pellets
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The regression model for the evaluation of the quality parameters for pellets

A. Beloborodko, L. Timma, A. Žandeckis and F. Romagnoli

Institute of Environment and Energy Systems, Riga Technical University,
Kronvaldablvd. 1, Riga, LV-1010, Latvia; e-mail: anna.beloborodko@rtu.lv

Abstract:

In Latvia no European legislation concerning the quality of the production of pellets is adopted. Since the market is not regulated by any governmental regulations, biofuel testing is not compulsory. This aspect leads to a situation where pellets of various qualities are available on the market. The main objective of this paper is to compare the characteristics of the pellets which are produced in various regions of Latvia. The second goal is to develop a regression model which describes the influence of the independent aspects (physical parameters, price, trading form, transportation distance etc.) on the pellet quality. The quality parameters for the solid biofuels were determined according to the methods described in the Technical Specifications of the European Commission for Standardization. The regression model for the pellet quality has been implemented using the software STATGRAPHICS Centurion 16.1.15. The results of the research emphasize that the physical parameters of the pellets vary widely. Three regression models were built in order to describe the influence of the various parameters on the indicator (price per net calorific value) and on the mechanical quality of the pellets. The fitted Models were described by the regression equation given in the paper.

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