KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44/h ps://doi.o g/10.14356/kona.2022008 Re iew Pape
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Copy igh © 2022 The Au ho s. Published by Hosokawa Powde Technology Founda ion. This is an open access
a icle unde he CC BY license (h ps://c ea i ecommons.o g/licenses/by/4.0/).
The Se illa Powde Tes e : A Tool o Measu ing he Flow
P ope ies o Cohesi e Powde s a High Tempe a u es †
Rahma Gannoun, José Manuel Pé ez Eb í, Albe o T. Pé ez and José Manuel Val e de *
Facul ad de Física, Uni e sidad de Se illa, Spain
Abs ac
Unde s anding he lowabili y o cohesi e powde s a high empe a u e is o g ea impo ance o many indus ial
applica ions whe e hese ma e ials a e handled a ha sh he mal condi ions. Fo ins ance, he Calcium-Looping
(CaL) p ocess, in ol ing he anspo , s o age and luidiza ion o limes one powde s a high empe a u e, is being
conside ed nowadays as a p omising echnology o he mochemical ene gy s o age (TCES) in concen a ed
sola powe plan s (CSP). In his con ex , he High Tempe a u e Se ille Powde Tes e (HTSPT) is p esen ed in
his wo k as a use ul ool o analyze how he low beha io o cohesi e powde s changes wi h empe a u e. The
manusc ip e iews he main esul s ob ained so a using his no el appa a us. The change o powde cohesi eness
and he e o e o powde lowabili y as depending on empe a u e, pa icle size, ma e ial p ope ies and nanosilica
su ace coa ing is illus a ed.
Keywo ds: calcium looping (CaL), HTSPT, lowabili y, he mochemical ene gy s o age (TCES), luidiza ion
1. In oduc ion
The calcium looping (CaL) p ocess has been widely
in es iga ed as a 2nd gene a ion echnology o cap u e CO2
om ossil uel powe plan s wi h al eady p o en high e i-
ciency in la ge scale pilo plan s (1–2 MWh) (Ba ke , 1974;
Blamey e al., 2010; Chaca egui e al., 2016; Kie zkowska
e al., 2013; P ie o e al., 2016; Val e de, 2013). The CaL
echnology bene i s om he abundance, low p ice and lack
o oxici y o na u al CaO p ecu so s such as limes one
and dolomi e ha can be used as aw ma e ial. Basically,
he CaL p ocess elies on he e e sible calcina ion/
ca bona ion eac ion
CaCO3 (s) CaO (s) + CO2 (g) (1)
0178kJ/mol
H
(1)
Du ing he exo he mic ca bona ion eac ion, solid CaO
pa icles eac in a luidized bed eac o a app oxima ely
650 °C wi h he lue gas con aining a small concen a ion
o CO2 (a ound 15 % ol). The ca bona ed pa icles a e
hen aken o a luidized bed calcine whe e he endo he -
mic decomposi ion o CaCO3 akes place o egene a e he
CaO a empe a u es abo e 900 °C in a high CO2 concen-
a ion en i onmen (Val e de, 2013; 2015). Mo e ecen ly,
he CaL p ocess has been he subjec o se e al s udies
o s o e ene gy in concen a ed sola powe (CSP) plan s
(Chaca egui e al., 2016; Paksoy, 2007; Pa do e al., 2014).
Cu en ly, small scale pilo plan s a e unde de elopmen
showing p omising esul s (Co dis, 2020).
Due o he g owing need o employ g een enewable
ene gy, he massi e deploymen o CSP plan s has come
up as an a o dable and highly e icien solu ion o elec-
ici y gene a ion a la ge scale. Howe e , he e iciency o
CSP plan s is hinde ed by he in e mi ence o sola di ec
adia ion which leads o an unbalance be ween elec ici y
p oduc ion and demand. The mal ene gy s o age (TES)
echnologies allow eleasing he mal ene gy o gene a e
elec ici y when is equi ed by means o hea s o age
ma e ials, hus sol ing sho comings and discon inui y
issues. A majo challenge o minimize he cos o CSP wi h
s o age and enhance i s e iciency is o selec adequa e
he mal ene gy s o age sys em. Based on di e en ac o s,
ene gy s o age echnologies a e classi ied as sensible hea
s o age (SHS), la en hea s o age (LHS), and he mo-
chemical ene gy s o age (TCES) (Hall and Hausz, 1979).
Sensible hea s o age s o es and eleases sensible hea by
means o a change in he empe a u e o he ma e ial used.
Syn he ic oils, mol en sal s, liquid me als and conc e es
a e he main sensible hea s o age ma e ials employable
in CSP. Cha ac e ized by hei high speci ic hea capaci y,
ela i ely low cos and accep able sa e y, mol en sal s
a e being cu en ly employed in comme cial CSP plan s
(Fe nández e al., 2014; Sang e al., 2015; Wu e al., 2017;
† Recei ed 10 Ma ch 2021; Accep ed 11 May 2021
J-STAGE Ad ance published online 26 June 2021
* Co esponding au ho : José Manuel Val e de;
Add: A enida Reina Me cedes s/n, 41012 Se illa, Spain
E-mail: [email protected]
TEL: +34-954550960
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Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
Zhang e al., 2013). Howe e , below empe a u es a ound
200 °C, mol en sal s solidi y, which equi es keeping he
whole ci cui abo e his mel ing empe a u e e en du ing
p olonged pe iods o absence o sola di ec sola adia ion.
In addi ion, abo e empe a u es ~560 °C, mol en sal s
deg ade whe eas he empe a u es achie able a CSP plan s
wi h owe echnology a e a ound 1000 °C. Thus, he use
o mol en sal s o powe gene a ion bu dens he po en ial
e iciency o CSP plan s o powe p oduc ion. Mo eo e ,
mol en sal s a e co osi e pa icula ly a high empe a u e
which equi es he use o special equipmen and he e o e
leads o high main enance cos s (Dunn e al., 2012; O ega
e al., 2008).
La en hea s o age o phase-change ene gy s o age is
based on he hea s o ed and eleased when he ma e ial ex-
pe iences a phase change (e apo a ion, mel ing, c ys alli-
za ion e c.). The choice o phase change ma e ials (PCMs)
in ended o TES applica ions needs o mee some sui able
ea u es: kine ic, physical, chemical, he modynamic and,
o cou se, economic a o dabili y. Solid-liquid PCMs a e
he mos used ones in esea ch p ojec s unde de elopmen .
Ye , hese ma e ials elease low la en hea and only in he
limi ed ange o empe a u es whe ein phase ansi ion
occu s. In addi ion some signi ican d awbacks a e hei
gene ally low he mal conduc i i y, phase sepa a ion,
expensi e main enance cos s, and also low ope a ing em-
pe a u e anges (up o ~90 °C) (He mann and Kea ney,
2002; Pin aldi e al., 2015; Sha ma e al., 2009).
In his con ex , he mochemical ene gy s o age (TCES)
is conside ed as a p omising echnology o ene gy s o age
in CSP sys ems (Abedin, 2011; Cabeza e al., 2012; Paksoy,
2007; Ta sidjodoung e al., 2013), as demons a ed by he
g owing numbe o e iews published in he las yea s
on his echnology which is cu en ly unde de elopmen
(And é e al., 2016; Ba ke , 1974; Ca illo e al., 2019; Gil
e al., 2010; Mahlia e al., 2014; Pa do e al., 2014). TCES
elies on he s o age/ elease o hea ia e e sible chemical
eac ions (Ca illo e al., 2019; Dinçe and Rosen, 2010).
The mos ele an ad an ages o TCES include he possi-
bili y o long e m hea s o age, high s o ed ene gy densi y,
small ene gy loss and he sui abili y o ope a e a e y
high empe a u es (up o 1000 °C o abo e (Abedin, 2011;
Cabeza e al., 2012; Ta sidjodoung e al., 2013). Among he
di e se op ions in es iga ed o TCES a majo candida e
is he CaL p ocess. Besides o he low cos , abundance
and lack o oxici y o limes one used as aw ma e ial, a
pa icula ly ele an ad an age o he in eg a ion o he
CaL p ocess in CSP plan s is ha he CaCO3 calcina ion
empe a u e i s in he ange o empe a u es a ainable a
he ecei e o CSP plan s wi h owe echnology (Pinel e
al., 2011).
A possible echnique o ope a ing he CaL p ocess in
CSP plan s is o use luidized bed eac o s albei o he
ype o eac o s such as alling pa icle, en ained low and
cen i ugal pa icle eac o s ha migh be be e in eg a ed
in sola ecei e s a e being in es iga ed (Co dis, 2020;
Esence e al., 2020; Ka asa as e al., 2020; Lisbona e
al., 2020; Sa ion e al., 2016; Tesio e al., 2019; 2020),
CaCO3/CaO solids o be employed in he CaL-CSP in e-
g a ion would p e e ably be in he o m o ine powde s
o mi iga e eac ion a e limi ing mechanisms such as po e
plugging (Beni ez-Gue e o e al., 2017) ha migh hinde
he p ocess a he mos a o able ope a ing condi ions o
he CaL-CSP in eg a ion (Hanak e al., 2015). As i is well-
known om expe ience, he lack o ma e ial lowabili y
may be a se ious issue in indus ial applica ions whe e
ine powde s a e employed due o hei high cohesi eness,
which can be enhanced e en u he a high empe a u es
(Chi one e al., 2020; Le ie i e al., 2000; Mac ì e al.,
2017; Tomase a e al., 2011). The Se illa Powde Tes e
(SPT) has p o en i sel as a eliable and accu a e de ice o
he cha ac e iza ion o cohesi e powde s (Ba le a e al.,
2019; Cas ellanos, 2005; Cas ellanos e al., 2004; Chen e
al., 2009; Val e de e al., 2000; Za a e al., 2015). Recen ly,
i has been upg aded o be used a high empe a u es. The
p esen manusc ip aims o p esen a de ailed desc ip ion
o he so-called High Tempe a u e Se illa Powde Tes e
(HTSPT). We e iew he main esul s ecen ly ob ained by
means o his no el se up, wi h a special ocus on he e ec
o empe a u e on he ensile yield s eng h o ine powde s
as depending on pa icle size, su ace coa ing and ma e ial
p ope ies.
2. A b ie c i ical e iew on powde
lowabili y es e s
Exhaus i e esea ch has been conduc ed wi h he aim
o explo ing ele an echniques o assess he abili y o
powde s o low (Schwedes, 2003). He e we summa ize
he main me hods en isaged om a c i ical compa a i e
analysis.
One o hese me hods, as desc ibed in he book o he
Ame ican Socie y o Tes ing and Ma e ials S anda ds
(ASTM, 1978), is based on measu ing he ime equi ed by
a ce ain amoun o powde o discha ge h ough a hoppe .
Hall and Cu ess (1960) showed ha his echnique can
be use ul o me allic powde s. An ex e nal ene gy sou ce
should be p o ided o enhance he low o e y cohesi e
powde s, which in oduces unce ain y o he esul s. A
heome e composed o shea heads, blades and pis ons is
ano he ool o e alua e powde lowabili y. To measu e
he o a ional and axial o ces, he componen s o he se up
a e o a ed and s i ed in he axial di ec ion. A de ailed
desc ip ion o he se up can be ound in (F eeman, 2004).
The eliabili y o hese es e s is somewha comp omised
due o he lack o ep oducibili y. Fo ins ance, he his o y
o he powde is dependen on he illing p ocedu e, he
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applied load, he de ice used and he wo king condi ions
(Cas ellanos e al., 2004).
A he mic oscopic le el, in e pa icle con ac o ces
a e ul ima ely he main d i e o powde lowabili y
(Quin anilla e al., 2001a). Thus, he di ec measu emen o
hese o ces is he bes me hod o unde s and he physical
mechanism ha go e ns powde low beha io . Shimada
e al. (2002) concei ed an ins umen o di ec ly measu e
adhesi e con ac o ces be ween pa icles o be ween a
plane su ace and a powde sample. This s udy conce ned
o ganic powde s (po a o s a ch, lac ose and co ns a ch). An
ad an age o he de ice is ha i can handle ine and e y
cohesi e pa icles (e en below 10 μm in size). The ea e ,
by means o a came a o mic oscope, i analyses he adhe-
sion o ce o a selec ed indi idual pa icle. They compa ed
he ob ained esul s wi h hose ound by ano he di ec
me hod ( he cen i ugal me hod) based also on a pos -
p ocess image analysis o powde a alanches in a o a ing
d um (Lüddecke e al., 2021; Quin anilla e al., 2001b). The
au ho s con i med ha bo h me hods ag ee quali a i ely.
Un o una ely, hese echniques do no allow o con ol
he s ess s a e o he powde ha g ea ly impac s he
con ac o ces (Quin anilla e al., 2001a). In his con ex ,
Quin anilla e al. (2001a) employed an a omic o ce mi-
c oscope (AFM) o de e mine he adhesion o ce be ween
i egula ly shaped pa icles o xe og aphic one s. The load
o ce p e iously applied on he indi idual pa icles can be
accu a ely con olled h ough his echnique. Compa ing
hei indings wi h he in e pa icle o ces es ima ed om
measu emen s o he bulk s esses in he Se ille Powde
Tes e (SPT) (Cas ellanos e al., 2004), hey epo ed an ac-
cep able ag eemen . Howe e , i should be highligh ed ha
he esul s on he o ces di ec ly measu ed using he AFM
echnique showed a la ge deg ee o dispe sion, which was
a ibu ed o he c i ical dependence o he adhesion con-
ac o ces o he highly a iable local su ace p ope ies
(Cas ellanos, 2005; Cas ellanos e al., 2004).
Recen ly, Ma che i and Hulme-Smi h (2021) in es i-
ga ed he lowabili y o 11 me al powde s wi h di e en
p ope ies and pa icle size dis ibu ions employing six
di e en es e s. The abili y o he powde s o low was
de e mined by means o di e se indica o s such as he
low a e, Hausne a io, basic lowabili y ene gy (BFE),
comp essibili y (CPS), majo p incipal s ess (MPS),
angle o in e nal ic ion (AIF), low ac o (FF), angle
o epose, speci ic ene gy (SE), and he uncon ined yield
s ess (UYS). The in e es ed eade could ind u he de-
ails abou he powde es e s and he di e en pa ame e s
in (Ma che i and Hulme-Smi h, 2021; Schwedes, 2003;
Cas ellanos e al., 2004; Le ie i and Mac ì, 2016).
Ma che i and Hulme-Smi h (2021) demons a ed he
exis ence o co ela ions be ween hese di e en pa am-
e e s o cha ac e ize powde low. They epo ed ha ,
o cohesi e powde s, he Hall and Ca ney unnels a e
blocked, while he lowabili y indica o o hese de ices is
he low a e. Consequen ly, hey a e no app op ia e in his
case. Indeed, hanks o hei simplici y, he es s based on
undamen al p ope ies (all he men ioned es s excep o
he heome e wi h shea cell de ice) a e widely employed
in indus ial and academic ields. Howe e , he insu icien
ep oducibili y ep esen s a se ious d awback (Ghadi i e
al., 2020; San omaso e al., 2003).
The Jenike shea cell is one o he mos commonly used
es e s. Fi s ly de eloped by Jenike in 1953 (Schwedes,
1976), he powde sample in his es is p e iously sub-
jec ed o a con olled consolida ion s ess. The sample is
con ained in a cylind ical cell o med by wo supe posed
s eel ings. Once he no mal load is wi hd awn, he es e
de e mines he minimum s eady s a e shea s ess ha mus
be applied o ini ia e powde low. Howe e , he Jenike
es e is no sui able o e alua e powde lowabili y a e y
small consolida ions ( ypically below 1 kPa). Besides, his
echnique assumes ha he powde shea s in a ho izon al
slip plane homogeneously ac oss he sample, which is
unce ain (S a o sky, 1987).
The Peschl shea cell (Ba le a e al., 2005; 2007; B uni
e al., 2007a; 2007b) was p esen ed as an al e na i e o ci -
cum en some o he abo e men ioned p oblems. The es e
is essen ially based on he same echnic as he p e iously
ci ed cells albei he shea s ess is exe ed by he o a ion
o he uppe pa o he annula shea cell con aining he
powde sample (S a o sky, 1987). This es e allows
o de e mine he powde low o an un es ained shea
dis ance and o a cons an shea su ace. Ne e heless,
non-negligible wall e ec s and non-uni o mi y o s ess
dis ibu ion may gi e ise o s ong unce ain ies
(Cas ellanos e al., 2004).
The abo e e iewed shea es e s a e designed o be used
only a ambien empe a u e. Ea ly wo ks o assess powde
lowabili y a high empe a u e we e ca ied ou by Smi h
e al. (1997). These au ho s employed he Jenike shea
cell o es CaSO4 and MgSO4 powde samples ha we e
p e iously hea ed (up o 750 °C) al hough he sample em-
pe a u e was no con olled du ing he es s. The au ho s
demons a ed ha he powde yield s eng h inc eased wi h
empe a u e p esumably due o he o ma ion o agglom-
e a es du ing hea ing. Kanaoka e al. (2001), Kamiya e
al. (2002) and Tsukada e al. (2008) succeeded o con ol
he empe a u e du ing he measu emen by placing he
shea cell inside a u nace. These au ho s mainly s udied
he adhesion beha io as ep esen ed by he a ia ion o he
shea yield s ess o ly ash pa icles. Kanaoka e al. (2001)
assumed ha he samples beha io ollowed he Coulomb’s
law o es ima e powde cohesion and he angle o in e nal
ic ion. In gene al, hey obse ed an inc ease in he shea
yield s ess wi h empe a u e, and he e o e o cohesion,
which was a ibu ed o he o ma ion o solid b idges
du ing hea ing. Simila obse a ions a e epo ed by
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Tsukada e al. (2008), who showed ha his phenomenon
can be a enua ed by adding coa se silica pa icles.
Mo e ecen ly some wo ks ha e modi ied he s anda d
Schulze cell in o de o s udy he e ec o empe a u e
(Chi one e al., 2015; 2020) (Mac ì e al., 2017; Tomase a
e al., 2011). Fu he de ails abou hese s udies will be
discussed in sec ion 5.
Al hough hese es s ha e shown sa is ac o y esul s, as-
sessing powde lowabili y a high empe a u e in luidized
beds would be desi able as his sys em s ands as he mos
commonly used o an adequa e empe a u e con ol, be e
e iciency o hea ans e and gas-solid con ac (Ding e al.,
2019). All in all, since in e pa icle o ces a e e y sensi i e
o nume ous pa ame e s (humidi y, empe a u e, pa icles’
size and shape, solid mechanical p ope ies, e c.) he e
is s ill a long way o go o ully unde s and powde low
beha io . Ou HTSPT based on he luidized bed echnique
is p esen ed in de ail in he nex sec ion as a u he con i-
bu ion o u he explo ing his c i ical issue.
3. Expe imen al se up
Fig. 1 shows a schema ic iew o he HTSPT used in
he wo ks e iewed in his manusc ip . This se up is aimed
o measu e he ensile yield s eng h and po osi y o ine
powde s as depending on empe a u e and consolida ion
s ess. I is based on he o iginal SPT o iginally concei ed
by Val e de e al. (2000). Essen ially, he equipmen is
based on measu ing he p essu e d op o a con olled gas
low ac oss he bed. The powde bed is held in a cylind ical
qua z essel o 4.5 cm diame e . A qua z po ous pla e is
placed a he bo om o he e ical cylinde ha se es as
gas dis ibu o . Be o e en e ing he bed eac o , he gas
c osses a il e and d ye (model SMC IDFA3E) in o de
o ge id o pollu an pa icles o humidi y ha can modi y
pa icle su ace p ope ies and he e o e powde cohesion
(Schube , 1984). Then a con olled gas low is pumped
h ough he bed by means o a digi al mass low con olle
(omega model FMA-2606A, 2000 sccm). The gas p essu e
d op ac oss he powde is measu ed by a MKS di e en ial
p essu e ansduce ha gene a es an analogue signal ead-
able by he compu e . The measu ed p essu e d op has wo
con ibu ions, he p essu e d op ac oss he powde bed and
he p essu e d op ac oss he po ous pla e. Ob aining he
p essu e d op ac oss he po ous pla e equi es a calib a ion
p ocedu e which consis s o measu ing he p essu e d op
o he pla e alone. This p essu e is sub ac ed om he
o al p essu e d op o ob ain Δp, he ac ual p essu e d op
ac oss he powde bed. The egis e ed p essu e d op has
an accu acy o ±5 Pa. A loudspeake is placed a he op o
he essel ha yields an acous ical exci a ion o 150 dB a
a equency o 130 Hz. This high in ensi y sound ield is
held o 5 s du ing he ini ializa ion p ocedu e as explained
below o dis up any plugs o channels ha may o m
and hinde luidiza ion, pa icula ly in he case o highly
cohesi e powde s (Val e de, 2013) yields an acous ical
exci a ion o 150 dB a a equency o 130 Hz. This high
in ensi y sound ield is held o 5 s du ing he ini ializa ion
p ocedu e as explained below o dis up any plugs o chan-
nels ha may o m and hinde luidiza ion, pa icula ly in
he case o highly cohesi e powde s (Val e de, 2013). A
se o al es is used o con ol he gas low di ec ion, when
al es 1 and 3 a e open while 2 and 4 a e closed he gas
lows upwa d ac oss he powde bed. This is he ope a ing
mode o b eaking and luidize he bed. On he o he hand,
in he in e se si ua ion ( al es 1 and 3 closed while 2 and
4 open) he low is di ec ed downwa d, which is used o
bed consolida ion. The bed is placed inside a u nace which
se es o pu he bed a high empe a u e.
The ully au oma ed se up s a s by a s anda d ini ializa-
ion p ocedu e du ing which a su icien ly high gas low
a e d i es he bed in o he bubbling luidiza ion egime o
30 s. Fluidiza ion is assis ed o he i s 5 s by he sound
Fig. 1 HTSPT: schema ic o he expe imen al se -up. Rep in ed wi h pe mission om Re . (Espin e al., 2020). Copy igh : (2020) Else ie .
33
Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
exci a ion. Then he gas low is u ned o and he bed is
le o se le o 30 s. This i s s ep is impo an in o de o
ensu e ep oducibili y o he ini ial s a e o he sample. In
he second s ep he bed is hea ed by using a PID con olle
(Eu o he m 3216). When he a ge empe a u e is eached,
a one-hou he mal s abiliza ion pe iod is se , aiming o
gua an ee a homogenous empe a u e dis ibu ion wi hin
he sample. The ea e , he bed is subjec ed o a g adually
inc easing downwa d gas low a e (by inc emen s o
5 cm3/min each 3 s) up o each a a ge consolida ion
s ess ( anging om he weigh pe uni a ea o he bed
up o σc~2 kPa). When he a ge consolida ion s ess is
me , he downwa d di ec ed gas low a e is main ained o
10 s. Then i is dec eased p og essi ely un il i is s opped.
In he las s age, a g adually inc easing upwa d gas low
is imposed o pu he bed unde ension which allows o
de i e he ensile yield s eng h o he powde as a unc ion
o empe a u e and he p e iously imposed consolida ion
s ess as explained below.
Impo an ly, in all he es s he heigh o he bed is kep
below he bed diame e which allows us o dismiss wall
e en ion e ec s o calcula e he ensile yield s ess. This
c i ical issue is discussed in u he de ail in Cas ellanos e
al. (2004).
4. B eaking and luidiza ion cu es
The gas p essu e d op ac oss he powde bed Δp is made
non-dimensional by he weigh pe uni a ea (W) in o de o
be e assess when luidiza ion is eached (
1
P
W
(11)
) which
in u n helps o de e mine he ensile s eng h. By plo ing
he gas p essu e d op h ough he bed as a unc ion o
he upwa d di ec ed gas low a e we ob ain he so-called
luidiza ion cu e (Fig. 2). A small gas low a es, he bed
emains in a solid-like s a e and Δp inc eases linea ly unde
he e ec o ic ional esis ance h ough he bed. This
linea beha io con o ms o he Ca man-Kozeny law a low
Reynolds numbe s (Ca man, 1997)
m
2
22
pp 1
E ηh φ
pq
ψd ρS φ
(2)
(2)
whe e E is he empi ical E gun’s cons an ( aking a ypical
alue be ween 150 and 180 (Nedde man, 1992), dp s ands
o he a e age pa icle diame e , ψp is he sphe ici y o
he pa icle ( a io o he su ace a ea o a sphe e wi h same
olume as he pa icle o he su ace a ea o he pa icle), ƞ
is he dynamic iscosi y o he gas, ρ alludes o he gas den-
si y, h and S a e, espec i ely, he heigh and c oss-sec ional
a ea o he powde bed, φ is he pa icle olume ac ion
and qm is he gas low a e.
The p essu e d op balances he powde weigh pe uni
a ea a he so-called minimum luidiza ion gas low a e qm .
A his poin , a non-cohesi e powde would be luidized.
Howe e , when in e pa icle adhesi e o ces a e signi ican
(compa ed o pa icle weigh ), he powde emains in a
solid-like s a e as he gas low is u he inc eased o e qm .
Then, he gas low pu s he bed unde ension while he
p essu e d op con inues o inc ease linea ly. A a c i ical
gas low, in e pa icle adhesi e o ces a e o e come and
a sudden b eak o he powde occu s a he bo om o he
bed while he p essu e d op alls ab up ly o a le el a ound
he powde weigh pe uni a ea. The ensile yield s eng h
o he powde a he bo om o he bed is ob ained om
he o e shoo o he gas p essu e d op o e he weigh pe
uni a ea σ = Δpmax – W. As he gas low a e is u he
inc eased o e he b eaking poin , he p essu e d op os-
cilla es a ound he weigh pe uni a ea while he powde
en e s a he e ogeneous luidiza ion s a e (see Fig. 2).
5. E ec o empe a u e
S udying he powde beha io a high empe a u es is
e y impo an no only o he CaL p ocess bu also o
many o he indus ial applica ions (hyd oca bons c acking,
nuclea and me allu gical indus ies e c.) (Le ie i P. and
Mac ì D., 2016) whe e ope a ing condi ions in ol e he
handling o powde s a empe a u es much highe han
oom empe a u e (Kunii D. e al., 1991). Se e al wo ks
ha e add essed he e ec o empe a u e on he luidiza ion
o powde s. Howe e , he epo ed obse a ions on he
minimum luidiza ion eloci y a e somewha con o e sial.
Di e en co ela ions ha e been p oposed o p edic he
e ec o empe a u e on he minimum luidiza ion eloci y
(Le ie i P. and Mac ì D., 2016). Howe e , hese co ela-
ions a e no eliable a high empe a u e. Fu he mo e,
an ex apola ion o he esul s o he es ed condi ions is
equi ed (Val e de e al., 2000; Yang e al., 1985). Some
al e na i es ying o sol e his p oblem ha e been
Fig. 2 Dimensionless p essu e d op Δp/W s he gas low a e qm
o CaCO3 powde samples (a e age pa icle size dp = 88.02 ± 0.7 μm,
T = 500 °C) p e iously subjec ed o di e en consolida ion s esses σc
as indica ed. Rep in ed wi h pe mission om Re . (Espin e al., 2020).
Copy igh : (2020) Else ie .
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Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
sugges ed (Wen and Yu, 1966), ye he e olu ion o he
minimum luidiza ion eloci y and bed oidage εm wi h
empe a u e is s ill conside ed as unce ain despi e he
se e al co ela ions epo ed in he li e a u e (Bo e ill e
al., 1982).
In o de o check he e iciency and ag eemen be ween
he di e en powde shea es e s, Salehi e al. (2017)
compa ed he esul s ob ained wi h he Schulze ing shea
es e , he Jenike shea es e and he B ook ield powde
es e (PFT) using h ee di e en ma e ials ha belong o
di e en Jenike powde classes (calcium lac a e, calcium
ca bona e and dolomi ic lime). Thei esul s had shown
ha he deg ee o ag eemen be ween he di e en se ups
depends on he na u e o powde es ed. Fo ins ance, o
dolomi ic lime, he PFT and Schulze es e show a good
ag eemen while he Jenike es e yielded highe cohesion
alues. Fo calcium lac a e ma e ial, he Jenike and Schulze
es e s yield a conside able inc ease o he powde cohe-
sion wi h consolida ion s ess, howe e he PFT measu es
do no uphold his obse a ion. In all he cases, he Jenike
es e gi e he highe cohesion alues. In wha conce ns
pa icula ly CaCO3 powde s, he cohesion de e mined by
he Schulze es e is ypically highe han he es ima ed by
he o he es ing de ices. I is no ewo hy ha all he men-
ioned es s ha e been pe o med a ambien empe a u e
due o echnical limi a ions.
In ega ds o he assessmen o powde low p ope ies
as a ec ed by empe a u e, Tomase a e al. (2011) made
some modi ica ions o he s anda d annula Schulze shea
cell. Howe e , o small consolida ions ( ypically below
~1 kPa), he esul s a e no ully eliable. They a ibu ed
his issue o design p oblems. Fo his eason, only es s
a highe consolida ion s esses we e ealized. A high
consolida ions hey con i med ha empe a u e (in he
ange up o 500 °C) does no ha e a signi ican impac on
he powde lowabili y o all he ma e ials es ed (FCC
powde , Co undum and ly ashes). Using he same se up,
Chi one e al. (2015) in es iga ed he low cha ac e is ics
a oom empe a u e and a 500 °C o i e di e en ce amic
powde s. Thei indings show ha he powde cohesi eness
conside ably inc eased wi h empe a u e and consolida ion
s ess. Howe e , o he samples wi h he smalles size,
he powde s we e al eady e y cohesi e, and he e ec o
empe a u e was no signi ican . Fo powde s o 20–38 μm
pa icle size, he e is an inc ease o cohesion o abou 35 %.
Fo samples o 63–88 μm pa icle size and o e 88 μm
pa icle size, a cohesion inc ease o 35 and 45 % a 500 °C
was no iced.
The esul s demons a ed also ha ee lowing powde s
(63–88 μm and mo e han 88 μm) u ned in o easy lowing
a 500 °C as a consequence o he inc ease in cohesion by
35 and 45 % espec i ely. In his con ex , o he same em-
pe a u e ange and using he same se up, Mac ì e al. (2017)
con i med hese obse a ions bu o wo di e en ypes o
TiO2 powde s (na u al and syn he ic).
Chi one e al. (2020) s udied he low beha io o
powde samples sie ed o ob ain a ange o pa icle sizes
co e ing G oup B, A and C o Gelda ’s classi ica ion a
empe a u es in he ange be ween 25 °C and 500 °C in a
hea ed luidized bed. They ound ha he ensile s eng h
o he powde s was inc eased wi h empe a u e. They
claimed ha his beha io was no a ibu able only o he
a ia ion o in e pa icle o ces wi h empe a u e bu also
o o he ac o s such as he di e ence in pa icle size and
bed expansion.
Du án-Oli encia e al. (2020) s udied he e ec o
empe a u e on he ensile s eng h measu ed o limes one
samples ha ing an a e age pa icle size o abou 50 μm
(de ails on he powde used a e illus a ed in Table A1) by
means o he HTSPT. Thei esul s indica ed a conside able
inc ease o powde cohesi eness as he empe a u e was
inc eased (Figs. 3 and 4). Mo eo e , he e ec o empe a-
u e was u he enhanced as he consolida ion s ess o
which he sample was p e iously subjec ed was inc eased.
The ob ained esul s i ed well o he empi ical co ela ion
(Fig. 5).
3/2 1/3 3/2 1/3
cc
σ a bT cσ bT σ
(3)
(3)
indica ing he exis ence o a c oss e ec be ween empe a-
u e and consolida ion. Thus, he consolida ion s ess can
be conside ed as a p omo e o he empe a u e e ec on he
ensile s eng h. The o egoing is o g ea impo ance. Fo
ins ance, du ing hei s o age in CaL-CSP plan s, he solids
Fig. 3 Tensile s eng h measu ed o a limes one powde as a unc ion
o he empe a u e o di e en alues o he p e iously applied con-
solida ion s ess σc: he g ay highligh ed a ea s ands o σc < 1000 Pa,
he ed colo ed cu e a ea ep esen s he ensile s eng h alues o
σc ≥ 1000 Pa. Rep in ed wi h pe mission om Re . (Du án-Oli encia e
al., 2020). Copy igh : (2020) Else ie .
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Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
could unde go a ious wo king condi ions in ol ing high
consolida ion s esses (abo e 1 kPa) and high empe a u es
(mo e han 300 °C).
6. E ec o pa icle size on he powde ensile
s eng h
Pa icle size is a majo physical p ope y ha impac s he
cohesi e beha io o powde s (Mac ì e al., 2017; Chi one
e al., 2020; Espin e al., 2019; 2020). As pa icle size is e-
duced, he gas-solid con ac e iciency is enhanced, which
p omo es mass and hea ans e in solid-gas eac o s.
Howe e , powde cohesi eness is also p omo ed, which
hinde s powde lowabili y and luidizabili y (Cas ellanos,
2005). Using he SPT, Espin e al. (2019) showed ha he
ensile s eng h o limes one powde s is no ably enhanced
as he a e age pa icle size is dec eased. Impo an ly, he
limes one powde samples used in hese es s we e ob ained
by ae odynamic classi ica ion yielding a na ow pa icle
size dis ibu ion, which made possible o be e analyze he
ele an e ec o empe a u e on powde cohesi eness as
depending on pa icle size. The expe imen s e ealed ha
he e is a syne ge ic e ec be ween he consolida ion s ess
o which he powde was p e iously subjec ed and pa icle
size on he inc ease o he ensile s eng h. The impac
o he consolida ion s ess on he powde ensile s eng h
becomes mo e ma ked o smalle pa icle sizes (Fig. 6).
As seen in a p e ious wo k, he inc ease o empe a u e
p omo es u he powde cohesi eness. This phenomenon
may u n ee lowing powde s a ambien condi ions in o
cohesi e as empe a u e is inc eased whe eas low cohesi e
powde s may show a e y cohesi e beha io a high em-
pe a u es (Chi one e al., 2020). The e ec o empe a u e
and consolida ion s ess could be well i ed by a powe
law b
c
a
σσ
(12)
whe e he alue o b p og essi ely inc eased
om 0.3 o 0.9 as he empe a u e o he powde bed was
inc eased in he ange om ambien o 500 °C (Fig. 7).
The esul s epo ed by Espin e al. (2020) e ealed ha
powde lowabili y is c i ically in luenced by pa icle size
as depending on empe a u e. As i is clea om Fig. 7
he impac o empe a u e on he powde ensile s eng h
is s ongly in luenced by pa icle size. An app eciable
inc ease o powde cohesi eness was obse ed when he
empe a u e exceeded a ce ain h eshold which depends
on pa icle size a he ela i ely small consolida ions
Fig. 4 Tensile s eng h o a limes one powde measu ed as a unc ion
o he p e iously applied consolida ion s ess o empe a u es anging
be ween 25 °C and 500 °C. The solid lines ep esen he bes i o a
powe law σ ~ σc 1/3. Rep in ed wi h pe mission om Re . (Du án-
Oli encia e al., 2020). Copy igh : (2020) Else ie .
Fig. 5 3D ep esen a ion o he ensile s eng h measu ed o a lime-
s one powde as a unc ion o consolida ion s ess and empe a u e. The
plo ed su ace shows he c oss e ec exis ing be ween hese pa ame e s
go e ned by he exp ession 3/ 2 1/ 3 3/ 2 1/ 3
cc
σ a bT cσ bT σ
[21]
. The
poin s a e he expe imen al measu es. Rep in ed wi h pe mission om
Re . (Du án-Oli encia F.J. e al., 2020). Copy igh : (2020) Else ie .
Fig. 6 Powde ensile s eng h σ as a unc ion o he consolida ion
s ess σc p e iously applied o he powde bed o CaCO3 powde
samples o pa icle size be ween 4 μm and 30 μm a oom empe a u e.
Rep in ed wi h pe mission om Re . (Espin e al., 2019). Copy igh :
(2019) Else ie .
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Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
es ed. Fo ela i ely small pa icles (a e age pa icle size
dp = 30 μm) he inc ease o he ensile s eng h is app ecia-
ble al eady a empe a u es below 100 °C. As pa icle size
is inc eased, highe empe a u es a e equi ed o p omo e
no ably he ensile s eng h. Fo ins ance, he empe a u e
h eshold ha causes a signi ican e ec on he ensile
s eng h is abou 300 °C o he powde s wi h 60 μm and
80 μm pa icle size. This empe a u e is educed o 200 °C
when pa icle size is dec eased o 45 μm. These esul s
show he impo ance o p ac ical applica ions o assessing
he impai men o powde lowabili y wi h empe a u e as
depending on pa icle size and he ypical consolida ion
s esses o which he powde s will be subjec ed du ing s o -
age and anspo . Fo he mal s o age o CaCO3 powde s a
indus ial scale, consolida ion s esses may be well abo e
1 kPa a empe a u es clea ly exceeding 300 °C (Val e de,
2013; 2015), which implies ha powde lowabili y could
be se iously hinde ed a he ypical empe a u es o he CaL
p ocess i ine pa icles (below ~60 um) a e employed.
Fig. 7 Tensile s eng h σ e sus he consolida ion s ess σc o CaCO3 powde s o di e en empe a u es and pa icle size: (a) dp = 88.2 ± 0.7 μm; (b)
dp = 59.3 ± 0.8 μm; (c) dp = 42.5 ± 0.8 μm; and (d) dp = 32 ± 1 μm. The solid lines a e he bes i s o he equa ion
b
c
a
σσ
[22]
o he expe imen al da a.
Rep in ed wi h pe mission om Re . (Espin e al., 2020). Copy igh : (2020) Else ie .
Fig. 8 Tensile yield s eng h σ o di e se powde s measu ed as a unc ion o he p e iously applied consolida ion s ess σc and empe a u e T. (a)
CaCO3, (b) soda-lime glass beads and (c) SiC powde samples. The solid lines ep esen he bes i o a powe law o he da a σ = aσcb, wi h b close o
uni y. Rep in ed wi h pe mission om Re . (Du án-Oli encia e al., 2021).
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Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
7. E ec o ma e ial p ope ies
Du án-Oli encia e al. (2021) es ed he e ec o he in-
c ease o empe a u e on he ensile yield s eng h o pow-
de s o simila pa icle size (be ween ~42 μm and ~72 μm)
bu o di e en ma e ials (limes one, soda lime and SiC).
The main esul s ob ained a e summa ized in Fig. 8. These
measu emen s e ealed ha , ega dless o he powde
na u e, cohesi eness is augmen ed wi h empe a u e. This
e ec is especially app eciable when he empe a u e is
T ≥ 200 °C o limes one and soda-lime powde s, wi h a
negligible di e ence in he measu ed σ up o 300 °C o
bo h ma e ials as i can be clea ly obse ed in Fig. 9. On
he o he hand, cohesi eness was p omo ed u he o he
soda-lime powde a highe empe a u es. Powde beds
could no be b oken when he empe a u e was abo e
300 °C, e en by he highes gas low a es achie able in he
es (qmmax = 0.8 g/min), which indica es a g ea inc ease o
he powde ensile s eng h nea his empe a u e. Indeed,
a empe a u es abo e 300 °C, soda lime is close o i s
glass- ansi ion empe a u e Tg (Tg ~520 °C) (Ge ha d,
2017; Va shneya and Mau o, 2019). A his empe a u e,
he powde ansi s om pu e-solid o ubbe y-like. This
change is accompanied by an app eciable dec ease o he
ma e ial ha dness and, he e o e, a ma ked inc ease o he
ensile s eng h acco ding o con ac mechanics p edic-
ions (Cas ellanos, 2005). In addi ion, high consolida ion
s esses p omo e u he ma e ial so ening as T app oaches
Tg. Fig. 10 shows SEM pic u e o soda-lime powde sam-
ples a e being hea ed up o 500 °C and subjec ed o a con-
solida ion s ess σc = 2 kPa. As may be seen, he pa icles
ha e expe ienced a isible local de o ma ion p esumably
due o ma e ial so ening. Dimples a e clea ly seen a he
su ace o he glass beads which we e a guably c ea ed a
in e pa icle con ac poin s du ing consolida ion a high
empe a u e. In con as , powde samples o a much ha de
ma e ial (SiC) show alues o he ensile s eng h up o ou
imes smalle han hose measu ed o he CaCO3 powde
o simila pa icle size o gi en alues o he consolida ion
s ess and empe a u e (Fig. 8). In he case o limes one, no
de o ma ions o he su ace o he pa icles we e app ecia-
ble a e he samples (ei he silica coa ed o uncoa ed) we e
subjec ed o he high empe a u e luidiza ion cycles (Espin
e al., 2020). These indings can be quali a i ely explained
by he change in he mechanical p ope ies o he ma e ial
as a ec ed by empe a u e, pa icula ly i s ha dness, which
dec eases signi ican ly wi h empe a u e (Michel e al.,
2004; Wheele and Michle , 2013; Zhang e al., 2017)
yielding an inc ease o he ensile s eng h as p edic ed by
con ac mechanics (Cas ellanos, 2005) when he pa icles
de o m plas ically a con ac poin s. Ano he impo an
pa ame e o conside in he case o non-glass solids is he
Tamman empe a u e TTam which is es ima ed as hal o he
mel ing poin and indica es he empe a u e a which ma e-
ial de o ma ion s a s o be app eciable (Tammann, 1932).
Fo limes one, his empe a u e is app oxima ely in he
same o de o he highes empe a u e es ed in he wo ks
e iewed in his manusc ip (TTam (CaCO3) = 565 °C (Xu e
al., 2016)), which would explain he app eciable inc ease
in he ensile s eng h seen in his case as he ma e ial
would so en conside ably a empe a u es close o TTam
(Fig. 8 (soda-lime pa icles)). Howe e , in he case o SiC,
he Tamman empe a u e is e y high (TTam ~1238 °C (Xu
e al., 2016) ). Thus, he ensile s eng h measu ed o his
powde in he ange o es ed empe a u es (below 500 °C)
is inc eased only sligh ly and powde lowabili y is no
se iously comp omised as is he case o he soda-lime and
limes one powde s.
Fig. 9 Compa ison o Tensile yield s eng h σ as a unc ion o he p e-
iously applied consolida ion s ess σc o he di e en powde s es ed
a T = 300 °C. Rep in ed wi h pe mission om Re . (Du án-Oli encia e
al., 2021). Copy igh : (2021) Else ie .
Fig. 10 SEM pic u es o soda-lime glass beads a e unde going
a consolida ion s ess o σc ≈ 2000 Pa a a empe a u e o 500 °C
(magni ica ions: 2500×). The a ow indica es pe manen de o ma ions
on he beads su ace su e ed du ing consolida ion a high T (no
obse ed in he esh sample). Rep in ed wi h pe mission om Re .
(Du án-Oli encia e al., 2021).
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Rahma Gannoun e al. / KONA Powde and Pa icle Jou nal No. 39 (2022) 29–44
Au ho s’ Sho Biog aphies
Rahma Gannoun
Holds a PhD (2019) in p ocess-chemical enginee ing om he na ional school o enginee s o
Gabes in collabo a ion wi h labo a o y o me ology and he mal measu emen o he na ional school
o enginee s o Monas i . She was unde g adua ed as a chemical-p ocess enginee in 2014 om
he same school. Ac ually she has a pos -doc ellowship wi h he acul y o physics (uni e si y o
Se ille). He a eas o in e es include elec ohyd odynamics, Compu a ional luid dynamics (CFD),
hea ans e , enewable ene gy, ine powde low.
José Manuel Pé ez Eb í
A membe o he Elec ohyd odynamics and Cohesi e G anula Ma e ials (EHD-CGM) esea ch
g oup a he Uni e sidad de Se illa (Se ille, Spain). PhD in Science and Technology o New
Ma e ials (2016). He began his ca ee as an indus ial echnical enginee in EHD-CGM g oup in
2005, whe e he ook pa in de eloping se e al expe imen al se ups, one o his a eas o in e es . He
wo ked ou yea s in ae onau ical indus y as a ma e ials enginee . He is de eloping his esea ch
ac i i y in Ca-Looping p ocess o CO2 cap u e and mechanical p ope ies o g anula ma e ials.
Albe o T. Pé ez
Was bo n in El Pue o de San a Ma ía (Spain) in 1962. He ecei ed his PhD deg ee om he
Uni e sidad de Se illa in 1989, whe e he has de eloped his academic ca ee . Since 2009 he is Full
P o esso o Elec omagne ism in his uni e si y. His in e es s a e p ima ily in elec ohyd odynam-
ics, powde low, and elec ic beha io o colloids. He has au ho ed mo e han 90 pape s in indexed
jou nals on hese subjec s. He is also a popula science w i e . P o esso Pé ez is cu en ly he head o
he g oup o Elec ohyd odynamics and Cohesi e G anula Ma e ials o he Uni e sidad de Se illa
José Manuel Val e de
P o esso o elec omagne ism and ma e ials enginee ing. PhD in physics (1997). His esea ch
ac i i y has been ocused on he s udy o luidiza ion and he mechanical p ope ies o g anula ma e-
ials. A main subjec o cu en in e es is de elopmen o no el echniques o enhance he CO2 cap-
u e e iciency o CaO-based ma e ials by means o he Ca-looping echnology based on ca bona ion/
calcina ion o na u al limes one in luidized beds. He has published o e 100 pape s mos ly in Q1
jou nals wi h o e 1000 ci a ions.
