159
1 INTRODUCTION
1.1 Hazardintransportofagricultureproducts
The marine transport industry tonnage accounts for
90%ofworldtrade.Whetheritinvolvesthedelivery
of raw product to a manufacturer, or final goods,
marinetransportisacriticalpartofthesupplychain
[Kelman2008].
The agriculture sector has been growing rapidly
overtheyears.Agricultureproductsshipmentsareto
a large extent determined by weather condit
ions in
producing and exporting countries. However, other
factors are increasingly influencing the volume and
structure of these cargoes. They include: the shift in
demand and usage for industrial purposes,
environmental and energy policies tha
t promote the
useofalternativeenergysourcesuchasbiofuelsand
evaluationinconsumptionanddemandpatterns.
Apart from grains, oilseeds, and pulses, and
besides timber and paper products and refrigerated
products,thereremainsawholerangeofagricultural
productswhichtogethercompriselargeandvaluable
sectors of seaborne tra
de. Most agriculture products
are transported with minimal loss of quality.
However, a part of raw vegetable and grain
productsthataretransportedinbulk,whensubjected
to high humidity levels and mild heat tend to self‐
heat,whichcontributestoareductionoftheirquality.
Cargoes with a high tendency to self‐heating are
list
ed as Class 4.2 Substance Liable to Spontaneous
Combustion.
Self‐heatingisacatalyticprocessthatoccurswhen
theheatgeneratedbytheoxidationofcargoandother
mechanisms is not effectively dissipated to the
surroundingenvironment,causing localtemperature
to rise. The increase in temperature occurs in two
Sea Transportation of Some Agriculture Products Liable
to Self-heating
M.Popek
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT:Propensityofcargoestosel
f
‐heatingisdeterminedbymanyfactorswhichcanbedividedintotwo
maintypes‐propertiesofthecargoandenvironment/storageconditions.
Some agricultural products are susceptible to self‐heating which can cause many serious problems during
handling,storageandseatransportationofsuchcommodities.
Palmkernelshells(PKS)havebeenshippedinbulksince2007buttheyarenotacurrentlylist
edcargointhe
IMSBC. PKS are a natural by‐product of pa lm oil processing and differ materially from the palm kernel
expellerscurrentlyregulatedbytheIMSBCCode.However,their specificcharacteristicsandnegativeexternal
influences may cause them to beha
ve like a substance from Class 4.2 (Substances liable to spontaneous
combustion)orMHBcargo.
Due to the importance of spontaneous combustion, particularly with respect to the storage and sea
transportationofPKS,aninvestigationhasbeenconducted.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 11
Number 1
March 2017
DOI:10.12716/1001.11.01.19
160
phases. Phase one is a biological heating, which
normally occurs up to 55
o
C and exceptionally up to
75
o
C.Biologicalheatingiscausedbyactivityofplant
cells, bacteria and insects. Phase two is a chemical
heating caused by exothermic chemical reaction
betweengoodsandoxygenupatleast150
o
C[Ramirez
et al. 2010].If the heat is removed or absorbed by
the surrounding environment, then only low
temperatureoxidationmayoccur.
Self‐heating of agriculture cargoes depends on
numerous controllable and uncontrollable factors
such as: chemical composition, porosity, exposed
surfacearea.
The original condition of these products is the
most important factor affecting its transport. The
product moisture content and temperature influence
andevendirecteventsthatoccurduringstorageand
transportationmayleadtoself‐heating.
Also, handling conditions such as changes in
moisture content of surrounding environment, large
variation in the temperature and movement of air
through
the cargo may contribute to self‐heating of
thecargo.
Moisture within the product reaches an
equilibrium with the air within and between the
product particles and produces a relative humidity
level that may be suitable for the growth of
deteriorativeorganisms.
Biological organisms that cause transported
products to deteriorate require
different levels of
relativehumidityfornormaldevelopment.
Both relative humidity and moisture content
depend on temperature. The excess moisture in the
productcoupledwithelevatedtemperaturepromotes
microbialactivitythatexudesheatandmoisture.
Insomecases,self‐heatingmaynotonlyleadtoa
decomposition of the material,
with a release of
flammable gases, but also major fires and risk of
explosion. This phenomenon is known as
spontaneouscombustionorself –ignition[Sturaro et
al. 2003]. Situations involving fire are very serious
andmay causemajor lossesof productsand human
injury.
Inordertosecurestorage andtransport,
theself‐
heating and self‐ignition in different types of coal
woodproductsandbiomasshavebeenstudied[Jones
2001,Krause&Schmidt2001].However,thereisstilla
lack of research that would characterize the risk of
self‐heating of agriculture products. Therefore, not
enough data regarding the properties of
the goods
storedandtransportedbysea.
The increased sea transportation of agriculture
raw materials for the biofuels industries and the
distribution of alternative energy products present
newchallengesforthemaritimeindustry.
Some agriculture goods are more susceptible to
self‐heating than others, and this can lead to severe
problems
duringstorage,handlingandtransportation
ofsuchcommodities.
Themechanismbehindthereactionwhichleadsto
self‐heating is not completely understood but is
probablyconnectedtothebiomassextractives.
1.2 Seedcakes
Seedcakeistheresidueremainingafterremovalofoil
fromanyoil‐bearingseeds, grains,cereals and
other
cereals products. It is a by‐product and principally
usedasananimalfeedandfertilizer.
Cereals and cereal products defined as seedcake
are those derived from several products such as:
coconut, maize, sunflower seed, copra, corn gluten,
linseedpalmkernelandsoyabean.
Seedcakeis transported asdry bulk
cargo, in the
formofpulp,meal,cake,pelletsandexpellers.There
are four types of seedcakes listed in IMSBC Code
definedbytheoil,moisturecontent andthemethod
of production. Three of them are classified as
hazardousmaterialsclass 4.2andrepresentscargoes
liabletospontaneouscombustion.
Seed
cake is regarded as hazardous good and
liabletoself‐heatingduetohighpresenceofmoisture,
residualoil.Althoughtheprocessisslow,itcancause
the temperature of the cargo to rise to the point at
whichitmayspontaneouslyignite.Furthermore,high
moisture content of seedcake promotes
microbiological
activity,whichmayberesponsiblefor
theinitialriseintemperatureuptoabout70
o
C.Itmay
accelerate oxidation of the residual oil, which can
causethetemperaturetorisetothevalueatwhichthe
seedcakewillspontaneouslyignite.
Oxidation of the oil in seedcake causes a
subsequentreductionofthe concentrationof oxygen
intheairinsidethecargospace.Additionally,carbon
dioxide
andcarbonmonoxidemaybeproduced.
Palm Kernel Shells (PKS) have been shipped in
bulk since 2007, but they are not a currently listed
cargointheIMSBC.PKSareanaturalby‐productof
palmoilprocessinganddiffermaterialfromthePalm
Kernel Expellers currently regulated by the
IMSBC
Code. However, their specific characteristics and
negative external influences may cause them to
behave like a substance from Class 4.2 (Substances
liabletospontaneouscombustion)orMHBcargo.
The purpose of the research was to examine
factors, which contribute to the self‐heating of Palm
KernelShells.
2 PALMKERNEL
SHELLS
2.1 CharacteristicsofPalmKernelShells
Therearetwokindsofoilinpalmnut:oneispalmoil,
whichremainsinoutercoreofthenutandtheotheris
palmkerneloilwhichisextractedfromtheinnercore,
knownaspalmkernel.PalmKernelShells(PKS)
are
the hard endocarps, which cover palm kernel
[Olanipekunetal.2006].
The palm oil industry produces wastes after oil
extractionprocess.Thetypeofwasteproducedfrom
oilpalmindustryincludes:emptyfruitbunches,fiber,
shell,wetshell,palmkernelfrondsandtrunks.They
consistmainlyofhemicellulose,celluloseand
lignin,
with some biopolymer extractives being minor
components[Ninduangdeeetal.2015].
161
PKSasacargoaretheshellfractionleftafterthe
nuthasbeenremovedaftercrushinginthePalmOil
mill. This cargo should not be confused with PK
Expellers, which can contain more residual oil and
thereforeregulatedinIMSBCCodeasSeedCake.
Kernelshellsarefibrous
materialandcanbeeasily
handledinbulk.Theaverageoilcontentisbelow1%,
butindividualcargoesmayvary.
MoisturecontentinPKSislowcomparedtoother
biomass residues with different sources and is
between 11% and 13%. Due to the fact that the
exporting countries are located
in the tropical zone,
the cargo can take up a large quantities of moisture
contentafterheavyprecipitation.
ThestudieshaveshownthatPKSischaracterized
bythatthe relativehighabsorbencyof water,asthe
material is an organic aggregate and contains many
pores.The24–hwaterabsorptionvaries
intherange
21%‐25% with varying PKS sizes. [Alengaram et al.
2010].
SpecificgravityofPKSdependsontheoriginbut
hasnevercrossedthevalue2,0andtherangeofitis
around1,17‐1,60[Mannan&Ganapathy2002].
PKShaswiderangeofparticlesfrom3to
14mm.
Theshape ofthe material depends onthe extraction
methodandbreakingofthenut.ThethicknessofPKS
varies between 0,15 and 8 mm. Bulk densities are
affectedbythesizeof PKSandvary intherange of
500‐600 kg/m
3
and 600‐740 kg/m
3
for loose and
compacted material respectively [Alengaram et al.
2010].
Furthermore, PKS contain residues of Palm Oil,
which accounts for its slightly higher heating value
thanaveragelignocellulosicbiomass.
2.2 MajorapplicationofPKS
In view of increasing population, the energy
consumption derived from fossil fuel resources
increasestoo.Nowadays
oneoftheseriousproblems
relatedtotheenvironmentistheincreasing pollution,
causedbytheuseoffossilfuels(Olivieretal.2012).
Globalwarminghasemergedasamajorproblemdue
to increasing rate of greenhouse gases emissions
generatedfromfossilfuelcombustion[Hosseinietal
2013].
Furthermore, facing
the challenge of depletion of
fossil fuels reserves, there are a lot initiatives to
promote the development and dissemination of
renewableenergy[Dhillon&vonWuehlisch2013].
In order to promote greater energy efficiency,
renewable energy should be part of the climate
change solution as long as the renewable energy
is
developedinasustainableway.
Use of biomass fuels in stationary combustion
chambersisrecognizedasanenvironmentalfriendly
productionofenergy[Laseket.al2017].
This has led to significant number of different
sourceofbiomasstobeappliedasanenergyresource.
The two countries: Indonesia and Malaysia
produce 85% of world’s oil palm total production.
Indonesiaistheworld’slargestproducersofpalmoil
and the industry has been the economy’s most
valuableagriculturalexportsectorforthepastdecade
[WorldGrowth,2011].
PKSisoneof theproductsof wasteduring palm
oil production. The huge
quantities of waste
generated from oil palm industry resulted in
investigationthepossibility ofconverting that waste
into biofuel. PKS have a high dry matter content,
thereforearegenerallyconsideredasagoodfuelfor
theboilersbecauseoflowashamountsandminimum
emissionincombustionprocess.
Theestimationof
biomass‐basedrenewableenergy
potential generated from solid waste od palm oil
(PKS) are approximately 54.8 GJ/year which could
replacetheuseoffossilfuels[Prastowo2012].
Currently compacted briquettes obtained from
palmkernelshellsareformed.Becauseoftheuniform
shape and size this product, it can be more
easily
transportedandusedasafuel.
In the opinion of scientist hydrogen may be
considered as the most important bio‐fuel that is
expected to be a major source of energy and play
significant role in the economic development [He et
al.2009,Pintoetal.2009].
One of the
serious problems, related to the
environment, is the increasing amount of plastic
waste. Currently the possibility of hydrogen
productionby blending Palm Kernel Shellswith the
polyethylene waste is studied. The production of
hydrogen‐rich gas from mixed feedstock may
mitigate the carbon emissions to the environment,
preventing further global
warning and reducing the
dependenceonfossilfuel.[Moghadametal.2013].
Theinvestigationindicatesthatpalmkernelshells
would make good alternative pore agents in
insulating refractory bricks. Very low water
absorption rate and hardness have the potentialities
of producing controlled size and independent pores
[Ekong2013].
The high demand for
concrete in construction
usingnormal weight aggregates, such as gravel and
granite, has reduced natural stone deposits and
causeddamagetotheenvironment[Alengarametal.
2013]. During the past years researches has been
focused on investigation on the use of palm kernel
shells as lightweight aggregates, to replace
conventional
normal weight aggregates in structural
elementsand roadconstruction[Mannan et.al2006].
It served the purpose of both the structural stability
andeconomicviability.
PalmKernelShellsarecurrentlythemostcommon
biomass energy good transported by sea. PKS are
generallyshippedinbulkvessels.
Recentincidentsduringseatransportationof
PKS
inlastyearshavedemonstratedthatthiscargoemits
veryhighlevelofmethane,whenissubjectedtothe
fermentation process and oxidation. This situation
occurs,whenthemoisturecontentexceeds11%.The
experienceinshipment ofthese goodsindicatesthat
the cargoes are subjected to oxidation leading to
depletionofoxygenandincreaseofcarbonmonoxide
andcarbondioxide.
162
Duetotheimportanceofself‐heating,particularly
withrespecttothestorage andseatransportationof
the PKS, an investigation has been conducted. The
IMOstandardhasbeenusedinthisinvestigation.
3 EXPERIMENTAL
3.1 Materialsandmethods
For the research, Palm Kernel Shells coming from
Indonesiawereused.
It is important to characterize the risk of self‐
heating and self‐ignition of these cargoes before
loading them on ship.Dry and oily (contaminated
withoils)samples ofPKS wereused instudies. The
possibility of self‐heating of Palm Kernel Shells was
estimated by using The Test Method
for self‐heating
substances of the Model Regulations [UN 2009]. The
test procedure outlined adequately assesses the
relative hazard of goods liable to spontaneous
combustion so that an appropriate classification for
transportcan be made. The abilityof a substance to
undergo oxidative self‐heating is determined by
exposureofit
toairattemperatureof140
o
Cin25mm
wiremeshcube.
The sample of PKS in its commercial form was
filled to the brim of the sample container and the
container tapped several times. The container was
housed in the cover and hung at the center of the
oven.Theoventemperaturewasraisedto
140
o
Cand
keptforseveralhours.Thetemperatureofthesample
andoftheovenwasrecordedcontinuously.Positive
resultsareobtainedifspontaneousignitionoccursor
if the temperature of the sample exceeds the oven
temperatureby60
o
C.
3.2 Resultsanddiscussion
The result of investigation on the ability of self‐
heatingarepresentedonfigures13.
Dry sample of PKS (sample A) , wet (10 % of
moisturecontent–sampleB),wet(15%ofmoisture
content – sample C)and oily contaminated (
oils
content:10%–sample D; 15% sample – E) samples
ofPKSwereusedinstudies.
Figure1.Self‐heatingcurveoftestedsampleAataconstant
temperature140
o
C.
Figure2.Self‐heatingcurvesoftestedsamplesBandCata
constanttemperature140
o
C.
Figure3.Self‐heatingcurvesoftestedsamplesDandEata
constanttemperature140
o
C.
The primary component of tested material is
cellulosethatisakindofapolymermainlycomposed
of C, H, and O. Despite such chemical composition,
the result indicates that the dry PKS are not self‐
heatingmaterials.Afterthetestperiod,therewasno
visiblechangeinthesample.
Based
onthecriteriadefinedinTheTestMethodfor
self‐heating substances, PKS is not a self‐heating
substance (in the conditions of the experiment, the
sampletemperaturehasnotincreasedto200
o
C).Self–
heating of biomass can occur either by chemical
oxidationreactionormicrobiologicaldecay.
Self‐heatingprocessesofPKSwhichwererecorded
during sea transportation were probably caused by
microbiologicalprocesses.
According to the test, wetted PKS cannot be
classifiedasasubstancecapableof self‐ignition.The
experimental
data may suggest that moisture
enhancesoxidationofmaterialsbyoxygen.
15%moisturecontentcausedthatthetemperature
of PKS approached the limit values of 200
o
C. The
conditionsofshipping: largemassoftheloadandthe
long transportation time can cause self‐heating of
moistcargo.
Nevertheless, for PKS the content of fatty acid is
predominant from the point of view of safe storage
andtransportation.Oncecontaminatedwithdryoils,
its thermal stability was
decreased with larger heat
generation which could result in spontaneous
combustion.
163
Theresultsofexperimentsconfirmedthatthelevel
ofpropensityPKStoself‐heatingstronglydependson
the degree of purity of tested materials. The high
content of oil as a contaminant (10 %) accelerates
exothermicreactionwhich may causeself‐heating of
material.WhenoilcontentinPKSwas
approximately
15%,thetemperaturegrewrapidly andhasinitiated
theself‐heatingprocess.
4 CONCLUSION
The maritime transport continues to evolve, new
products and new methods introduce new and less
wellunderstoodhazards.Itisrecognizedthatrisks
associatedwiththisgrowthinthe transportofthese
raw materials depend
on two major parameters:
temperatureandtheirmoisturesensitivity.
Self‐heating of biomass is a serious problem and
hasbeenacauseofseveralincidents.
OilpalmbiomasssuchasPalmKernelShellcanbe
used to produce steam for processing activities and
for generating electricity. It is important to
characterize
the risk of self‐heating and self‐ignition
ofthesecargoesbeforeloadingthemonship.
The results of investigation provide information
importantforpreventingtheself‐heatinginthePKS.
The data presented in the paper could be useful in
estimationofthethermalstabilityduringstorageand
transportation
of these cargoes. It should be
recommendedtoavoidstorageandseatransportation
of large volumes of PKS if its tendency for self –
heatingisunknown.
TheIMSBCodeneedcontinual upgradingbecause
crewsandshippingagency needmoreinformationon
thebehaviorofthenewproductsandtheir carriage
in
newways.
Factors, such as cargo volume, the level of
compactionofthetransportedcargoandexternalheat
source should be taken into account when
determiningtheriskofself‐heating.
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