Tag Archives: wheat straw

1257-1265 J. Bradna, J. Malaťák and D. Hájek
The properties of wheat straw combustion and use of fly ash as a soil amendment
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The properties of wheat straw combustion and use of fly ash as a soil amendment

J. Bradna, J. Malaťák* and D. Hájek

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:

Agriculture is one of possible producers of by-products suitable for energy purposes,

such as rapeseed and wheat straw. But on the other hand, not only thanks to the support of energy
from biomass grown specifically for this purpose, arable land is exposed to intense cultivation of
wide-row crops indirectly supporting soil erosion and nutrient elution. The issue of recycling ash
from biomass combustion on agricultural and forest land is very important to resolve. Experience
with this problem is found in countries in Northern Europe such as Finland or Sweden, as well as
in North America. Due to ash characteristics, it is considered a valuable soil component and a
potential replacement for conventional fertilizers.
Elemental analyses of samples from wheat straw pellets were followed by combustion and
emission measurements. The effects of temperature and volume of air in the combustion of wheat
straw was analysed, focusing on emission concentrations and the ash content. Effect of excess air
coefficient on the composition of end products after combustion was assessed in three modes
(small, optimum and high coefficient of excess air). During the measurements, the excess air
coefficient ranged between the values from 3.95 to 14.89. The average net calorific value of the
wheat straw samples was 15.55 MJ kg-1 in the original state. Mineral composition analysis of
solid combustion products, necessary for using these residues as a fertilizer or soil component,
was performed as well.

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303-310 T. Ivanova, M. Kaválek,, B. Havrland, M. Kolaříková and P. Skopec
Comparison of technologic parameters of pellets and other solid fuels produced from various raw materials
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Comparison of technologic parameters of pellets and other solid fuels produced from various raw materials

T. Ivanova¹, M. Kaválek¹,*, B. Havrland¹, M. Kolaříková¹ and P. Skopec²

¹Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences, Kamycka 129, CZ16521 Prague 6 – Suchdol, Czech Republic
²Czech Technical University in Prague, Faculty of Mechanical Engineering, Zikova 1903/4, CZ16636 Prague 6, Czech Republic *Correspondence: michal.kavalek@seznam.cz

Abstract:

The article relates results of experiments and problem studies, the main goal of which was comparing four alternatives of solid biofuels suitable for heating private houses by low-power boilers. The results were obtained by burning of selected biofuels in an automatic pellet boiler specifically designed for combustion of pelletized fuels with high ash content. The emissions were set up related to the mass of burnt fuels and to the fuels’ net calorific value (specific emissions), they were measured and analysed. Based on the emission concentration measurements and stoichiometric calculations, the fuel gas emissions’ properties and boiler efficiency were compared at a range of power outputs of 7.5 kW, 12.5 kW and 18.5 kW. With regard to fuel properties and boiler outputs, the emissions of carbon monoxide (CO) were determined as well as emissions of nitrogen oxides (NOx) and sulfur dioxide (SO2) were measured and compared too. The results permitted to formulate conclusions that the wood pellets were having the lowest values of measured emissions, whereby Jatropha seed cakes showed several times higher emissions in comparison with emissions from wood pellets, oil palm shells and wheat straw pellets, where the last one is a typical representative of the agricultural biomass with relatively high nitrogen content and as was shown higher emissions of NOX as compared to wood pellets. Oil palm shells measured emissions were relatively similar to wood pellets emissions, especially concerning emissions of SO2 and CO. All tested materials were having very low combustible sulphur contents and therefore the specific SO2 emissions were negligible at all these fuels. A very important finding was that the amount of emissions was dependent on boiler output, where with the output decreasing the amount of emissions was growing. The other linkage – dependence of the boiler efficiency on power output was also proved in the present paper.

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269-276 M. Tutt, T. Kikas and J. Olt
Influence of different pretreatment methods on bioethanol production from wheat straw
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Influence of different pretreatment methods on bioethanol production from wheat straw

M. Tutt, T. Kikas and J. Olt

Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56,
EE51014, Tartu, Estonia; e-mail: marti.tutt@emu.ee

Abstract:

Article investigates the influence of different pretreatment methods on sugar
conversion and bioethanol production. Different dilute acid and alkaline pretreatment methods
are compared to determine the best pretreatment method to give the highest glucose and ethanol
yields under the mild operating conditions. Wheat straw is used as a raw material as it is the
most widely grown cereal in Europe. Dilute sulfuric acid, hydrochloric acid, nitric acid and
potassium hydroxide solutions are used for pretreatment in combination with enzymatic
hydrolysis. Results indicate that the highest cellulose-to-glucose conversion rate of 316.7 g kg-1
of biomass is achieved by the pretreatment with nitric acid. The lowest glucose concentration of
221.3 g kg-1 is achieved by hydrochloric acid. In the wheat straw samples pretreated with
sulfuric acid and KOH, two different approaches are used. Solid phase of half the samples is
rinsed with water before adding enzymes, and the rest of the samples are not. The rinsed
samples pretreated with KOH solution give the highest ethanol yield of 104.3 g kg-1, while the
lowest ethanol yield is 67.7 g kg-1 from samples pretreated with HCl solution. Unrinsed samples
and rinsed samples pretreated with sulfuric acid give an ethanol yield of 78.7 g kg-1 and
92.0 g kg-1, respectively. These results indicate that rinsing the solid phase of the samples with
distilled water before hydrolysis removes most of the inhibitory compounds formed during the
pretreatment with dilute acid and increases fermentation efficiency by approximately 12%. 

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