Tag Archives: calorific value

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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115-122 S. Kalinauskaite, A. Sakalauskas, E. Šarauskis, A. Jasinskas, M. Ahlhaus and H. Gerath
Biomass preparation for conversion humidity and value assessment
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Biomass preparation for conversion humidity and value assessment

S. Kalinauskaite, A. Sakalauskas, E. Šarauskis, A. Jasinskas¹, M. Ahlhaus² and H. Gerath³

¹Aleksandras Stulginskis University, Studentų g. 11, Akademija, Kauno r. LT-53361,
Lithuania; e-mail: solveiga.kalinauskaite@gmail.com
²Fachhochschule Stralsund, Institut für Regenerative EnergieSysteme (IRES), Zur
Schwedenschanze 15, 18435 Stralsund, Germany;
e-mail: Matthias.Ahlhaus@fh-stralsund.de
³Hochschule Wismar, Philipp-Müller-Straße PF 1210 Wismar 23952, Germany;
e-mail: horst.gerath@hs-wismar.de

Abstract:

Biomass usage for heat and energy purposes is one of the questions which still required more detailed analysis and scientific research. In this research we have focused on an analysis of humidity correlation on biomass preparation to conversion steps and calorific value assessment. The concept of biomass is widely understood, and in this research the chosen research object is agricultural, biomass with a main focus on straw, and additionally for results comparison are analyzed samples, composition are a mixture of straw and hay, with an additional 2% lime additive. For this research analyzed samples and their humidity for production steps is: one chop size reduction (20 mm) straw briquettes, two chops size reduction (30 mm and 10 mm) straw briquettes, pallets composition of 100% straw, 98% straw incl. 2% lime additive, 50% straw and 50% hay, 49% straw and 49% hay incl. 2% lime additive, 100% hay, 98% hay incl. 2% lime additive. Samples of straw and hay mixture, also with a lime additive is choosen because it is discussed widely that not only is it possible to use surplus straw from agricultural biomass as renewable energy and heat source, as a lime additive helps to keep a higher temperature on the combustion process and to generate more energy, but it is not healthy for the plant and not recommended under environmental aspects. The results received will help to estimate and determine the material humidity impact on biomass preparation for conversion steps, following an energy requirement for the production of briquettes and pallets, combustion factor and efficiency. It is defined as material calorific, HHV (higher heating value) and ash content which is one of the main factors and the criteria for fuel valuation will allow to determine tested samples further usage for heat and energy purposes. The research results will help further research tasks on bio energy as an agricultural biomass usage.

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