combustion of pellets from wheat straw · (rcg) from finland, pellets made of apple juice...
TRANSCRIPT
Acta Montanistica Slovaca Ročník 17 (2012), číslo 4, 283-289
283
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
Introduction
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 MJ.kg-1 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, [email protected] , [email protected] , [email protected] , [email protected]
Jozef Jand
284
as an addconditioncondition(91.3 %).Straw pelsignificanof boilersash conteefficienciin real lifreported iand RL-2particle h
Schmburned 8beech, oagrass) pecontinuouManuallymeasuredmanually13 % O2,with aut12–21 mgfired systfraction cof levoglof automathe same by the mowere obs(under fuof the fue
Comheat sourburning o
Boilform of wless than grid withthat showset up andis 25 kW
ačka, Michal Ho
ditive). Pelletsns and in twons, wood pell. The CO andllets emitted tnt. High ash cs. Reed canaryents and lessies. Comparisfe condition tin real life con2 boilers, resphad a tendencymidl et al. (20 different typ
ak and spruce ellets and trusly while PMy fired stovesd compounds,y fired applian dry gas), equ
tomatically fig m−3 (STP, 1tems account
content of aroulucosan whileatically fired fuel type pr
ode of operaterved for triti
ull load operael.
mbustion of wrces was adapof wood pelletler “1” (fig. 1 wood pellets r20 mm. The
h movable comws the basic opd individual fu.
Fig
olubčík, Štefan P
s were burnedo boilers (35lets yielded td dust emissiothe highest Ncontents and loy grass, citruss emissions. on with the stthan standard nditions. In thpectively. They to form smal011) tested propes of fuel in
logs, wood priticale (“enerM10 was sams exhibited hi, determined
nces were arouuivalent to 90ired applianc3 % O2, dry g
t for elementund 90 %. One this anhydrsystems. Gen
redominantly tion, start-up, cale pellets: 1
ation, STP, 13
ood pellets anpted to burn pts (boiler “2”)left) is low-te
respectively stboiler has wa
mponents (figperating param
functions of th
g. 1. Left: Boiler
Papučík and Rad
d in multi-fue5 kW) were the highest cons were the Ox and SOx. Fow ash meltin
s pectin and apIn the real l
tandard laboralaboratory co
he real life cone FE–SEM ell clusters of soduction of ga2 automatica
ellets as well rgy crop”) pmpled with aighly variablein a series o
und 130 mg m0 mg MJ−1. Wces emit almgas), or 8–14 mal carbon and
n average arourous sugar wnerally, emissconsisting offull load or p
184 mg m−3 (13 % O2, dry g
Expe
nd straw pellepellets made f.
emperature hetraw pellets frater body mad
g. 1 right). Onmeters of the he boiler can b
“1” for combusti
dovan Nosek: Co
l domestic petested in rea
combustion efhighest with
For agro-pelleng temperaturpple pellets halife conditionatory performaonditions; howndition, dust examination osub-micron sizaseous emissially and 2 maas further bio
pellets were a dilution syse emissions rof replicate e
m−3 (standard cWood pellets anmost one ordmg MJ−1. Arod 30–40 % fo
und 5 % of PMas below detsions from auf inorganic copart load for a125 mg MJ−1gas), originati
rimental dev
ets was realizefrom wood or
eat source desifrom agricultude from weld
n the top side boiler and key
be effectively
ion of various pel
ombustion of pelle
ellet boiler (40al life conditifficiency (92.peat and sun
ets, statistical re made strawave advantagens, the boilerance showed twever, lowed emissions werf the particleze ranging betions and particanually fired ogenic fuels: w
tested. Gasetem and aver
resulting in aexperiments. conditions fornd chips combder of magnound 30 % of tor organic ca
M10 emitted btection limit iutomated systeonstituents. Ea given fuel t,) PM10 and ing from high
vice
ed in two autor straw (boile
igned for autoural biomass aed steel plateof boiler is pyboard througcontrolled. No
llets, Right: Burn
ets from wheat st
0 kW) under ions. Under .4 %) followenflower husk
differences inw pellets less se over others wrs had aroundthat the NOx eCO and parti
e 5.0 and 5.8 s revealed thtween 300 µmculate mattersappliances. S
wood chips, meous emissionraged over st
an uncertaintyAverage PM
r temperature bustion under
nitude less Ptotal particle marbon, resultiny manually fiin full- and pems were rel
Emissions aretype. Surprisin466 mg m−3 (h chlorine an
omatic heat soer “1”) and an
omatic biomasand wood chip. Combustion
placed controlgh which thesominal perfor
ner of boiler “1”.
traw
standard labostandard laboed by apple pellet, respecn ash content
suitable for thiwith reasonabd 90% combemission was icle emissionmg Nm-3 withat most of th
m and 1.2 µm. s (PM10) wheSoftwood briqmiscanthus (elns were metandard test c
y of 30 % forM10 emissions
and pressure r full load ope
PM10, respecmass from mang in carbonared stoves conpart load opeatively consta
e mainly influngly high emi(395 mg MJ−1
nd nitrogen co
ources. One onother allowe
ss combustionps with tiny frn is realized atl unit with a de parameters
rmance of boil
oratory oratory pellets
ctively. s were is type
ble less bustion higher s were h RL-1 he dust
en they quettes, ephant asured cycles. r most s from (STP), eration ctively: anually aceous nsisted eration ant for uenced issions ) NOx,
ontents
f these d only
n in the raction t fixed display can be ler “1”
BpossibIn thefeederair to the bu
M
boilerTo decharacaccordboilerinlet perfor
wheretransf
wheremediu
Boiler “2” (figble to burn blae boiler is usedr. From there,burner. Subs
urning layer by
Measurementsrs for solid fetermine thermcteristics boilding to configr performancetemperature trmance is dete
e cw is specififer medium is
e V& is voluum [kg.m-3].
g. 2 left) is loack coal with d retort burne, screw feederequently pelley new supplie
Fig. 2. Left: B
s of performanfuels supplied
mal performaner must be op
guration, whice measuremento the boiler ermined by th
vmP = &
ic heat capacicalculated by
=Vm && v
ume flow ra
Fig. 3. Sc
ow-temperaturmaximum grar (fig. 2 right)rs transported ets are burneded pellets whil
Boiler “2” for com
nce and emissd manually a
nce, boiler effiperated in nomch is shown innts are recorde
(TR) and thhe following ca
.(. RVw ttc −
ity of the heaty the following
ρ⋅V [k
ate of heat t
cheme of test equip
Acta
re heat sourceanularity 25 m). Pellets fromit to the retor
d in the burnile fall into the
mbustion of wood
sion parameterand automati
ficiency, burniminal thermaln fig. 3. For noed the followihe mass flowalorimetric eq
)R [W],
t transfer medg relationship
kg.s-1],
transfer medi
ipment for measu
Montanistica S
e designed formm. Nominal m the hopper art space. Fan ing layer. Bure ash box.
d pellets, Right: B
rs were perforically, with ning time, templ performanceominal boiler ing parameter
w of heat tranquation
dium [J.kg-1.K
ium [m3s-1]
ring parameters
lovaca Ročník
r fully wood pperformance
are moved by with variable
rned pieces an
Burner of boiler “
rmed by standnominal perfoperature of exe. Testing dev
performance,rs: temperaturnsfer medium
K-1], while the
and ρ is de
of heat sources.
k 17 (2012), čísl
pellets combuof this boiler gravity into tspeed spur co
nd ash are pu
“2”.
dard EN 303-5formance to 3xiting flue gasvices may be , respectively re of boiler oum (ṁv). Boile
(
e mass flow o
(
ensity of hea
o 4, 283-289
285
stion. It is is 18 kW. he hole of ombustion shed from
5 "Heating 300 kW". , emission connected minimum
utput (TV), er thermal
(1)
of the heat
(2)
at transfer
Jozef Jand
286
On fCO and concentra
On f
CO and N
ačka, Michal Ho
fig. 4 and 5 arNOx accordi
ation of emiss
fig. 6 and 7 arNOx according
olubčík, Štefan P
re shown profiing to the tiions were rec
Fig. 4. Pr
Fig. 5. Profiles o
re shown profig to the time, w
Fig. 6. Pr
Papučík and Rad
Mea
files of measurime, where walculated to th
rofile of thermal p
of measured emis
files of measurwhere wood p
rofile of thermal p
dovan Nosek: Co
asured result
red thermal pewood pellets he reference o
performance – bo
ssions CO and NO
red thermal pepellets were bu
performance – bo
ombustion of pelle
ts
erformance anwere burned
oxygen (O2ref
oiler “1”, wood p
Ox – boiler “1”,
erformance anurned in boile
oiler “1”, straw p
ets from wheat st
nd profiles of md in boiler “= 10 %).
pellets.
wood pellets.
nd profiles of mer “1”.
pellets.
traw
measured emi“1”. The me
measured emi
issions asured
issions
O
CO an
Oemissadaptesuddepelletfive t
On fig. 8 and 9nd NOx accord
On fig. 10 anions CO and Ned for burning
enly began to s this performtimes and pro
Fig. 7. Prof
9 are shown pding to the tim
Fig. 8
Fig. 9. Prof
nd 11 are shNOx according straw pelletfall heat perf
mance has decloduction of em
files of measured
profiles of meame, where woo
8. Profile of therm
files of measured
own profiles ng to the time, ts. When passformance of blined steadily,mission NOx
Acta
emissions CO an
asured thermaod pellets wer
mal performance
emissions CO an
of measuredwhere wood p
sing from the boiler from 17, this is visiblincreased alm
Montanistica S
nd NOx – boiler “
al performancre burned in b
e – boiler “2”, wo
nd NOx – boiler “
d thermal perpellets were bcombustion o
7 kW to 10 ke on fig. 10. Pmost four tim
lovaca Ročník
“1”, straw pellets
e and profilesoiler “2”.
ood pellets.
“2”, wood pellets
formance andburned in boileof wood pellekW. During thProduction of
mes. The bigg
k 17 (2012), čísl
s.
s of measured
s.
d profiles of er “2”. Boiler
ets to burn strahe combustionemission CO
gest issue was
o 4, 283-289
287
emissions
measured “2” is not
aw pellets n of straw increased s in using
Jozef Jand
288
of burnerclusters oprocess.
Ave1214 mgof straw pand emiss
AveAverage of combupellets inand emisscontinuedand unbuand therm
It is or burnerwas morperformadesigned of pellets
ačka, Michal Ho
r, which is notof ash, which
F
rage thermal .m-3 and NOpellets in boilsions of NOx rage measuremeasured pro
ustion of woodn boiler “2” sions of NOx d thermal peurned pellets mal power dec
obvious that r with movablre effective tance significa
to burn only s, this differen
olubčík, Štefan P
t adapted for bcaused low f
Fig. 10. Pr
Fig. 11. Profiles
performance Ox 186 mg.m-
ler “1” was 13676 mg.m-3 of
ed thermal peoduction of ed pellets in bowas 8,9 kW644,3 mg.m-
erformance dedropped to a
creased sharplycombustion o
le grid. It has than combustantly lower tha
wood pelletsnce was 33.7 %
Papučík and Rad
burning of agflow temperatu
rofiles of thermal
of measured emi
C
of boiler “1” -3 in boiler “13,2 kW. Averf combustion
erformance ofemission CO oiler “2”. Ave
W. Average m-3 of combustecreased, becash box. Latey.
of straw biomabeen shown o
tion in boileran in the case s, namely 43.3%.
dovan Nosek: Co
gricultural pellure of ash. Th
l performance – b
issions CO and N
Conclusion
was 19,9 kW1”. Average mage measuredof straw pelle
f combustion was 1034,4
rage measuremeasured prodtion of straw cause clusterser, after mea
ass is complicon measuremer “2”. Duringof wood pell
3 %. The boil
ombustion of pelle
lets. On the suhese ash clust
boiler “2”, straw
NOx – boiler “2”,
W. Average memeasured therd production oets in boiler “1
of wood pellmg.m-3 and ed thermal per
duction of empellets in boi
s of ash limsuring, cluste
cated and neeents. Combustg combustionets. This diffe
ler “2” is desi
ets from wheat st
urface of the bters prevented
pellets.
straw pellets.
easured concermal performaof emission C1”. lets in boiler emissions of formance of c
mission CO wiler “2”. Whe
mited the comers of ash ex
d special burntion of straw n of straw perence was grigned to burn
traw
burner were fd proper comb
entration of Cance of combO was 1850 m
“2” was 15,NOx 174,8 m
combustion ofwas 5245,3 men the measurmbustion of xtinguished th
ner with coolepellets in boil
pellets was theater in a boiltwo different
formed bustion
CO was bustion mg.m-3
7 kW. mg.m-3 f straw mg.m-3 rement pellets he fire
ed grid ler “1” hermal ler “1” t types
Acta Montanistica Slovaca Ročník 17 (2012), číslo 4, 283-289
289
The thermal performance of the boiler “2” had a downward trend. The concentration of CO has increased by 52.4 % when burning straw pellets in boiler “2” and NOx increased 3.6 times more in comparision with the combustion of wood pellets. In the case of boiler "1" it was worse. The formation of CO increased more than 5 times in the case of straw pellets and the concentration of NOx was 3.7 times more in comparision with the combustion of wood pellets. Larger amount of NOx in the both boilers is very similar, which is caused by a higher content of nitrogen in the phytomass as in dendromass. The concentration of CO is much higher in the second boiler “2”. This is because the burner of the boiler “2” is designed to burn agri-pellets and during combustion occurs the melting of ash and of clusters of ash. This resulted in imperfect combustion process, lower performance and higher production of CO emissions.
The above measurements have pointed to the fact that the combustion of agro - pellets is quite difficult and requires use of special burners. Measurements also showed that the purchase and burning of cheaper phytomass pellets in boilers designed to burn only wood pellets is inappropriate.
Acknowledgement: This work is supported by the financial assistance of the project VEGA No. 1/1353/12. I acknowledge the financing with thanks.
References
Hužvár, J., Kapjor:, A.: Project Micro-cogeneration Incl. The Conversion of Chemical Energy of Biomass to Electric Energy and low Potential Heat, Fourth Global Conference on Power Control and Optimalization, roč. 4, č. 1, 2010.
Hužvár, J., Nosek, R.: Impact of fuel supply to concentrations of emissions in domestic boiler. Power control and optimization, Malaysia, 2010, ISBN 978-983-44483-32.
Chabinski, M., Kubica, K., Szlęk, A.: Influence of control algorithm on efficiency and pollutant emission in small capacity stoker boiler, The 1st International Congress on Thermodynamics, 2011.
Chabiński, M., Szlęk, A.: Propozycja wyznaczania sprawności kotłów małej mocy, Archiwum Spalania Vol.11 Nr1-2, 2011.
Chudikova, P., Tausova, M., Erdelyiova, K., Taus, P.: Potential of dendromass in Slovak Republic and its actual exploitationin thermic economy. In: Acta Montanistica Slovaca, 15 (spec issue 2), pp. 139-145, 2011.
Jandačka, J., Holubčík, M., Papučík, Š, Jurkechová, J.: Spaľovacie a splyňovacie kotly na pevné palivá pre domácnosti. Žilina, Slovakia: Juraj Stefúň GEORG, 2011, ISBN 978-80-89401-38-3.
Jandačka, J., Papučík, Š., Nosek, R., Holubčík, M., Kapjor, A.: Environmentálne a energetické aspekty spaľovania biomasy, Žilina, Slovakia: Juraj Stefúň GEORG, 2011, ISBN 978-80-89401-40-6.
Nemec, P., Hužvár, J.: Proposal of heat exchanger in micro cogeneration unit, configuration with biomass combustion, Materials science and technology, 2011, ISSN 1335-9053.
Rybár, R., Tauš, P., Horbaj, P.: Technológie alternatívnych zdrojov vodná energia a biomasa, 1. vyd - Košice: ES F BERG TU - 2011. - 93 s.. - ISBN 978-80-553-0693-3.
Schmidl, C., Luisser, M., Padouvas, E., Lasselsberger, L., Rzaca, M., Ramirez-Santa Cruz, C., Handler, M., Peng, G., Bauer, H., Puxbaum, H.: Particulate and gaseous emissions from manually and automatically fired small scale combustion systems, Atmospheric Environment, Volume 45, Issue 39, December 2011, Pages 7443–7454, 2011, ISSN: 1352-2310.
Verma, V. K., Bram, S., Delattin, F., Laha, P., Vandendael, I., Hubin, A., De Ruyck, J.: Agro-pellets for domestic heating boilers: Standard laboratory and real life performance, Applied Energy, Volume 90, Issue 1, February 2012, Pages 17–23, ISSN: 0306-2619.