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  • Acta Montanistica Slovaca Ročník 17 (2012), číslo 4, 283-289


    Combustion of pellets from wheat straw

    Jozef Jandačka, Michal Holubčík, Štefan Papučík and Radovan Nosek1

    The alternative energy sources are more and more used for production of heat. Several new combustion devices allow co-firing of different fuels, like dendromass and phytomass. The article analyses combustion of wood and straw pellets in the same boiler. Measurements were realized in two automatic heat sources – one is adapted to burn pellets made from wood or straw and another allows only burning of wood pellets. There are analysed performance and emission parameters of boiler. Key words: wood pellets, straw pellets, energy crops, performance, emission


    At present there is high interest in using of agricultural waste from plant production and energy using of energy crops that are deliberately planted on a big fields. Energy crops are plants with non-wood stems grown specifically for energy production. Their energy content is about 15 - 20 in the dry state. Growing of energy crops has an indisputable advantage for farmers because they do not compete with food, so this "green energy" can then ensure smooth sales.

    In terms of Europe can plant create 1.2 to 1.4 g of dry phytomass from 1 MJ of solar power, plant with C4 type of photosynthesis are more efficient. Creation of 1.4 g dry weight from 1 MJ of solar energy is considered one of the criteria for selection of plants for use in phytoenergetics. (Jandačka et al., 2007)

    These energy crops can be directly used for production of heat in combustion devices or they can be improved to pellets or briquettes.

    In practice, there are used only a few kinds of plants. In terms of energy is particularly important yield, production costs, product modification for the purpose of heating engineering, logistics, transport of finished biofuel to consumers, etc. Grown plants, bio-treatment, distribution and marketing of agricultural biofuels are aspects for the use of plants. Energy content of agricultural biofuels for energy using is necessary to utilize in combustion devices, and this is the second page of the problem.

    Most agricultural biofuels have low temperature point of softening, melting and flow of ash (cereal straw) or a large production of CO (carbon monoxide) (feeding juices and most types of grass) and almost all contain a high content of ash (more than 5 %). These are negative qualities that wood biomass pellets and briquettes from waste wood do not have. One of the ways to eliminate negative properties is making from energy crops and other possible components a mixture of certain proportions. Another option to eliminate negative properties of agricultural biofuel combustion is adjusting of combustion device such another type of burner, shape and size of combustion chamber, rapping and blowing of burner to remove the excessive proportion of ash, or modification of regulatory and management system. (Jandačka et al., 2007).

    In many cases, manufacturers of automatic boilers for wood pellets report that in these boilers can be burnt pellets made from energy crops (straw pellets) as well. These small heat sources are produced in most cases, with automatic control using regulation of feeding and standing time. In feeding time is fuel transported by screw conveyor to burner in combustion chamber. However, for each fuel type is this setting various and the biggest problem for manufacturers of boilers is finding usable interval of fuel feeding. It is given by different properties of used fuel. It is also important to note that change of settings which control to lower operating performance (lower time intervals) may not be automatically provided setting to optimum combustion of fuel. It is necessary to do a lot of experiments in order to find usable time intervals for combustion of various types of fuel in one heat source.

    Related work

    Verma et al. (2011) tested wood pellets from the Belgium, peat pellets and reed canary grass pellets

    (RCG) from Finland, pellets made of apple juice industrial waste from Poland, pectin pellets made of citrus shell (CPW) from Denmark, sunflower husk pellets (SFH) from Ukraine and two kinds of wheat straw pellets from Belgium (straw-1 with 100% pure straw and straw-2 with 2wt% of hydrated lime [Ca(OH)2] 1 prof. Ing. Jozef Jandačka, PhD., Ing. Michal Holubčík, Ing. Štefan Papučík, PhD., Ing. Radovan Nosek, PhD., Department of power

    engineering, Faculty of Mechanical Engineering, University of Zilina, Univerzitná 8215/1, 010 26 Žilina, tel. +421 (0)41 513 2851, , , ,

  • Jozef Jand


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    Schm burned 8 beech, oa grass) pe continuou Manually measured manually 13 % O2, with aut 12–21 mg fired syst fraction c of levogl of automa the same by the mo were obs (under fu of the fue

    Com heat sour burning o

    Boil form of w less than grid with that show set up and is 25 kW

    ačka, Michal Ho

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    ak and spruce ellets and tr usly while PM y fired stoves d compounds, y fired applian dry gas), equ

    tomatically fi g m−3 (STP, 1 tems account

    content of arou lucosan while atically fired fuel type pr

    ode of operat erved for triti

    ull load opera el.

    mbustion of w rces was adap of wood pellet ler “1” (fig. 1 wood pellets r 20 mm. The

    h movable com ws the basic op d individual fu .


    olubčík, Štefan P

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    logs, wood p riticale (“ener M10 was sam s exhibited hi , determined

    nces were arou uivalent to 90 ired applianc 3 % O2, dry g

    t for element und 90 %. On e this anhydr systems. Gen

    redominantly tion, start-up, cale pellets: 1

    ation, STP, 13

    ood pellets an pted to burn p ts (boiler “2”) left) is low-te

    respectively st boiler has wa

    mponents (fig perating param

    functions of th

    g. 1. Left: Boiler

    Papučík and Rad

    d in multi-fue 5 kW) were the highest c ons were the Ox and SOx. F ow ash meltin

    s pectin and ap In the real l

    tandard labora laboratory co

    he real life con e FE–SEM e ll clusters of s oduction of ga 2 automatica

    ellets as well rgy crop”) p mpled with a ighly variable in a series o

    und 130 mg m 0 mg MJ−1. W ces emit alm gas), or 8–14 m al carbon and

    n average arou rous sugar w nerally, emiss consisting of full load or p

    184 mg m−3 (1 3 % O2, dry g


    nd straw pelle pellets made f .

    emperature he traw pellets fr ater body mad

    g. 1 right). On meters of the he boiler can b

    “1” for combusti

    dovan Nosek: Co

    l domestic pe tested in rea

    combustion ef highest with

    For agro-pelle ng temperatur pple pellets ha life condition atory performa onditions; how ndition, dust e xamination o sub-micron siz aseous emissi ally and 2 ma as further bio

    pellets were a dilution sys e emissions r of replicate e

    m−3 (standard c Wood pellets an most one ord mg MJ−1. Aro d 30–40 % fo

    und 5 % of PM as below det sions from au f inorganic co part load for a 125 mg MJ−1 gas), originati

    rimental dev

    ets was realize from wood or

    eat source desi from agricultu de from weld

    n the top side boiler and key

    be effectively

    ion of various pel

    ombustion of pelle

    ellet boiler (40 al life conditi fficiency (92. peat and sun

    ets, statistical re made straw ave advantage ns, the boiler ance showed t wever, lowed emissions wer f the particle ze ranging bet ions and partic anually fired ogenic fuels: w

    tested. Gase tem and aver

    resulting in a experiments. conditions for nd chips comb der of magn ound 30 % of t or organic ca

    M10 emitted b tection limit i utomated syste onstituents. E a given fuel t ,) PM10 and ing from high


    ed in two auto r straw (boile

    igned for auto ural biomass a ed steel plate of boiler is p yboard throug controlled. No

    llets, Right: Burn

    ets from wheat st

    0 kW) under ions. Under .4 %) followe nflower husk

    differences in w pellets less s e over others w rs had around that the NOx e CO and parti

    e 5.0 and 5.8 s revealed th tween 300 µm culate matters appliances. S

    wood chips, m eous emission raged over st

    an uncertainty Average PM

    r temperature bustion under

    nitude less P total particle m arbon, resultin y manually fi in full- and p ems were rel

    Emissions are type. Surprisin 466 mg m−3 ( h chlorine an

    omatic heat so er “1”) and an

    omatic biomas and wood chip . Combustion

    placed control gh which thes ominal perfor

    ner of boiler “1”.


    standard labo stan