1. COM8USTION/PVROPI(OCESSING
...
When to enrich the kiln1
by Larr y Farme r & Sincc 1!J97, cC'ment plants h.1VC rootinely appliC'd oxygen f"nrichmClJt to
Frank Romano, enhance kiln performalJce and ((t.'alc economic bt.'lIclil. The technical
Air Prod ucts and Chemicals advantages of oxygen-enhanced com bustion have been well documented.
Inc, USA but there arc ..ttll .mme quest,om a .. to its pr,1CljCiJ/ily, especiafly in U,t.'
cement industry. The common perception i<; that ox ygen worh but ,t is
expensive. Wllile oxygen represents an added ('Os/. it can be ecollomica l
depending on operating conc1ilioH,~ and specdic c.o~/s .11 the plant. Other
T
hi~ ,Irticl" ;I rlnro>sso>s the f'{OI1Cll'!lic~
tor three con UlIon cement pl,lo'It industries. sl.lt.h as steel. glass. and non · ferrous metals. routinely emplo y
opera ting (onn lhcns that w ould o xygen in lheir high·tcmpcralurc processes.
warrdnt COtlSldtoldbo< of oxygen·
enh;Jncoo tombu~ l ion_ the volu~ p<'I'",l ty of air (<;ef' panel). ao OIlygen systrnl ,~ typically very low
III Jdditlon t o Ihe ,mmcd ..!le 1:...0 1
0 camp.lIed to othl'r eqUipmenl Of ~y'lem
Fan limited inc.emental dinke., oxygen promotes Llr,~.ade~ .lnd IS not.1 'ignific.lnt l,leto.
Wh.lt l i.st (jrov!' th e USI' 01 oKy g~n IfI a mo.1' st;'!bl~ oper;'!!lon by rre .ltlng a Ul co nsidering ol{ygen. In mo~t in~t,lnCeS,
the 1"lc ·l990s wa, the ~ ud dcn Up~Uf'gl' hot:<'r, ~hoft~r /la"l(' and im p.uving ,!In pie payba(k on luta l capital i~ in the
on the USA demand fa. cenwnt following burn'ng lone control. Ove r trme. the order of two or thr"'f' month s_
yN' S of lottie or 110 growth if' capacIty. ddd(,(! ~!<lblhly contr btrt:~ 10 a(k"llonal The variableS that play the grl'a l('l. roll'
As (ement planh uiecl to squeeze exlr.1 p.oduction In the economiC f'volluillion arf' d inkl"
cI:nket out 01 theu kl)n~, I N.-y Dilen ~lrKe th iS CMf' ~ pu.ely pfOduchon va lue. unil oxyge n cost, and oxygrn
Wl'fe hmited b V their inritl(f' d d.aft (ID) c1.jven, the tnO'c men ta l chn ker va lue efficiency (onflf'S of Incremental clin kerl
f,l!l~. Incremental plO(lucho fl ,C1:!ulfcd must b{' grealer Ih,1n Ih .. added CO$ of lonne~ 01 oXYI,Wn) Opcration~ th ~ t hd!{,
.lddit,on.,1 fuel ;IId tombu~ti on air At the m'ygen ,1011 inClenwntll fue l .1nd employec1 o.Y!iell for n 5l1st,lined period
most plant;, the It) f.m reached its hmi t In'd costs The ,Idd' lonal dlnker ,~ be.ng enjoy,..! continued m.l, ket demantl for
before other N ltHpmenl or ~y5tems p.oduced VI,th no change to the plolnf djn~er with (l,nl(er values .11 or ~hght ly
lK'd 10 Ihe kiln. In thelot· CJ5e'i, oxygen I 'l{{'d cO'>ts. Thl'fefo.e. only Ii'll' added below the c~1 o f oxygen (Oil a U~S/t
f'nr;chment prOVIded thl' ne.::es!o.1ry vanable « x ts .lre reqLl,red to d{'te'minr bais) an d oxygen efficlellcies gredle-r
additlOn.ll o~ygen fa. tcmbu~1on WI thout tI'H' net benefl!. The (api t.l l cost 10 Inst.lll th.Jnthr~
O!<ygen,~ either produc('(l atl-arge
cryogen-= IW' 5oep.lrallOl'l plants and
then tr.rnportl'd by tank ItKk 0 the
arn;~r'~ $Ill' (lr In ~ cases It ca~ be
AIR..!.: !ent'f.aed dtfect/y .1 tile eustomer's SIll"
"ooucrs .....:
JANUil!:! 10(}') 1(. ~9

2. COM BUSTiON/F'YROPROC FSSING
A fiem ative fuel challenges o xygen 10 re,1(1 '111h thl'; co ,1nd at.jln o:tygt'n en richment. Employ,"g mrygl'n
MQ.(' Jnd 11'10 ' (' (cmcnl plJl1h .lIe " OW some e x!r.1 bent'!it from thc l C ~l.Ill,n,; hea t IfIll'c tiOf) 10 1 pr ove con,busl",n In (ement
00
turning to .iltern.1twt' fuels to lowl" theIr tell'<lSe kilns I~ technl(ally ilnd I'(onom kaily v~lble
ope rating (O~t~. Today's alternatlvc f u('~ Thl' key tactol In dctelmlnmg the Wllh nlininM! c"pltal investment, wment
con~i~t of .1 wid!> raor,e of matenill~ '111 111 benefIt 01 l.IInr, o~y.r,cn to comb ust plants can im plemen t o xygen rOfi(hn)Cnt
Sit,:l1iiic,!1 va riJllons in cnl'm i(al ,10 (1 e:o:{t'ss CO i~ si mil", to Ihe first .'xample to g'l, n ,1n Incre me nta l i ncr ('~s c in
phyS<Cill COtl1pO~It ion. Petcoke. Iyrf'~, of Increased Pt orllJctl(ln. Th e ~ aJl.I e (>f production o~ lower o pWill ing C:O~ t
waste oil. Mld chemicals Wf'r r the ongonal th e additional p.odl.ldiOIl (o r ,"" , IUl' through glcd!e. substitution o f a lte rna tive
alle. na llY(" fuels but arc now bCln l! IOlflc<l of the high ty'C ~ub~ti tuJon) n lu~ be: fuels. Each plant mus t wClgh all 0ptions
by ,1 Wide ' ,lOge of material~ mC!uoing compared to the r.O.~t of the oxyg!'''. fOl and dete.mim" the most econom,e,l l
wood wa!;!r. pl.1~tic5. Wil sIe paper. JJllnlill CO (emetJldlon, thl' volume of oxygen approach 10 IIn pmve theIr O~I ~tinn~. In
me,ll. etc. tends to bl! low!'. Ih,1n for thl! prl!vicu e,lc!' c~~e. the oxygen efficiency VI'II pl" y
DCPffiding on th~ nature of the fucl l' KJmpll's. The flow rate reqUirement ;I~ O a key to le III the bendi ts analy~i~ The
,lnd its dispo5a l CO lt. the ~C() nomi( t!'nd, to be 5t~'l dy nlllking on-site oxygpn de~i gn ,1nli InC,ll ion of t he o ~yger. Injectm
bClIehts carl lx- ~ub~tantial. O n the 01111: ' gC<le ralion mor c amenable, w hich fwl ile r a'e also cr itiC,'! to IllaXl nll$mg cfh( lency.
h.md, ,1ItfornatlVf' fupls p'P5ent a majer Improves the ov!',,)11 pconom>(5.. Smce each pI,l ot has Uniq Ue oper,ll in);
challenge 10 the kIt" oper.ltor. Thel' charade. ist~. it I~ Important to con~tdcf
heilbng valUf' r.Jrl,~e between 2000 Summary Ihe expe n("lce of the technology p'OIIIffi;f
and 36,OOOld/kt: ,nd they Un contolln Th~e siluatio n~ ,11 I('Plesenl ope' a t'"g to make ~u".' that o pt.unJ.l ' ewlh a.r
lip to 50 per cen t w. Ir •. Due to thi!.
1 w<ld itions thai ......l" ,nl investiga tiOn 01 "I t,lined. I
widt' ',m ge ,n propt. rtie<,. th pre IS ofte n
d p,actical I:mi t to wb~t ltu l lo" levcls
In the k~n an d p ,ec,lklne •. m,lln taimng
sulf>(K-lIt tcmpe' ,ltu'e I~ pa'dlllount to
thl! efficient prGducticn of clinker. If thl!sl!
tem pe rature-. tanr1Ct be- mamtalned d ue
In thl' low he ati ng v"lue~ of altematove
lu d ~ . prGductlon I cvt'l~ mu ~t be curtailed
A~ a re~u l t, oVl' r.111 fu el ~ub~ti tu ti o n and
tht~ economIC benchts .~ re ~ mi:l'd
By U1Uea$Ing the fl,lme If' mperature,
oxygen·e nhanced combu~tion enables
Inc(f'a,;cd subsbtutlon of "lll'rn,l tive fuels
"",theut .loy decline il"! prcducbon. The
ccon(>nH lot o. ygen ,~ d roV by the
CS l'"
co~ t (MferenD"i belw el' n thl' primary .1nO
a.it('(fIat,vr tueb. To be tC() rI(>ITlI (,ll. the
OIIer,11! fu el .~avlng~ nll",t oH'of' t the o xygen
cost This I~ .oulillely achoevcd al pl<lnls
tha t are p,l.d to burn wute furk When
th .. c051 d,fferenti,11 betWttn he pflmary
fucl an d " I'I'.n~' ,ve fuel i low. Ihe "oded
co, t of o xyg en is m DI'e ("h fflwlt to lu~tify
un!..-ss the re a ll' othc ' bc 'I(· llt~
Emission constraints
In <;orne Coll"o J Cl'menl p~lnl ope •.J.boo
I~ CO<1traJnt'd by t-ml~~lon pem li l Irvd~
Whl'fl thl' emissions ~re directly .elil te d tn
co 'l1 b u ~lion e(('CIency. oxygen ennchmelll
mi gh l be fea~i b l e. For f' ~" m p l e . cement
planb hJl alc lImi ted by lo la l ca rbo n
mono xid e (CO) tml~~'nn~ may benefil
f.om o xygen ennch mcnl. This situatJoo
Iyp,cally occurs w llh prehl'iltc. k'ins
burning tyr!'s 01 precak,nt r ~ ilns th ,l t ale
limi ted by tl lell terti ary (lir.
To .wo id fXpensivp, po~t - I reatm" nl
o f CO, ccmcnt pla nh CoIl1 d ln ,cll), Ifllt'Ct