CA2005833A1 - Fuel briquettes with combustion inhibitor and method of making same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Fuel briquettes comprising a fine-grain carbon carrier consisting of petroleum coke or a mixture of mainly petroleum coke and coal (preferably non-caking coal) with a binder and with a fine-grain combustion inhibitor mixed therein in the form of calcium carbonate and/or dolomite, which has been added to the initial fuel briquette mixture in a quantity in excess of 2%
by weight, volatile constituents being eliminated from the fuel briquette.

Description

29~S833 BRIQ~ 'ES WIq~I COMBt~STION I~HIBI~irOR AND ~OD OF M~XING SAl~E

CIF~AT:lON

The lrlv~ntion ~late~ to fuel bxiqu~3tte~ c~omprl~lng a, ~ine,--graln c~rbon earrier ~onsi6ting oC petroll2um coke or a ~ixt;u:re o~ mainly petr~le~ cok~ and oc,al, prefera~ly non-ca~ing co~,l., with a b~nder. ~h~ term "fuel briquet~es" denote~ brir~ette~ of the kind used for heat generati.on in domes.tia fires, central heating boi1er6 r thermal power 6tations an~ the like.

E~R~R~ 5~T~ 3~LON
Fuel briquette~ in whioh the fi.ne-grain carbon ca~rier i~
petrole~m co~e or mainly petroleu~ coke generate excessive temperatures on ao~nbustion whi~h clamage the combu~tion equipment.
They have inadequate ~tr~ength and readily d~lntec3rate ~ur~nc~
handling and combu~tion~
FU~ iqut~tte~ o~ this kin~ generelte ~xt,~6siv~ ~emperatures on combu~tion and ~e~t~oy the combustion eg~ipment from the simple ~urnat,e to the heating boiler. Petrolt~um coke frequently oontains a conslderable amount of sul~ur, e~g~ in quantities o~
0.8 to 5% or more. The same applaes to the binde:r, parti~larly in the ~ase of pitch.

[ 1 ;~OOS~333 Fuel ~rique~tes conta~ning petroleu~.n ~oke or main}y petroleum coke as t:he ~ine-grain c~rbon carrier ther1~0re ~ene~ate exeessiv~ amount~ of ~ulfur dioxid,3 i~na, for other reasons, nitric oxides a~. well.
The l~ttex also appl ~ es to briquette~ o:E ~he above-d~cr~.~)ed ¢omp~ition (U.~:. Patent 2,036,642) whl~h, in order to i.ncrease the ~trength, ~re manu~actured by mean~3 of a special binder mixtu~e whiah also contaLns caloiu~ hyl1roz:lde ~s a binder in ~
quantlty o~ a~o~ 2~ by weight. ~n thi~s ca!;e the in$~ial. mixt:ure i~ heat-trealted at a~ou~ 250-C in ~he unmo:lded ~tate and is molded i~to the ~inal ~uel briquettes nf~er ~ooling.
In pr2,ctice, ~uel bri~uettes col1talning ~ine-grain hi.gh-a.sh ~on~ont c:oal a~ caxbon carr~er hav,~3 ~e-~n disclosed experimental-ly wlth addition~ of ~ine-graln calcium carbona~e a~ desul~urlz-ation agent, due conside~ation be$ng g:Lven to sto$chiometrlcaspects. TherQ 3~e no pxoblem~ as~cciated with th~ ¢om~ustion temperat~res oacUrring with such fuel briqllettes, ~u~h temperat~res be~ng aete~tnined by the coal ash ~ontent. The regulred de5ulfurization ~5 unsat~ ac1:ory ~nd ~orreYponding ~0 2uel bri~uettes hav~ ound little use :in practice.

5~JE.~'S OF ~H~ YX~TIO~
An o~eot of tha invention ~8 to provide ~uel bri~uetteq ¢ontainlng petroleum co~e or mainly petroleum coXe whlch wlll burn in z. co~txo1led fashion involving no pro~le~s for the combus~ion appllance.
~ nother ob~e~t o~ the inven~ion is 1;o pr.ov~de an improved metho~ of` maXlng fuel ~riguettes.

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17~44 S~MMA~ OF TH~ INVE~IO~~
To this end, the invention relates to i.uel bric~ettes com3-,ri~-ing a ~ine-gxaill c~lrbon aar~ie~ ca,nsistLn5~ of petroleum coke o~
~ mixtur~3 o~ ma~nly petroleu~ c:oke and coal (preferably non-c~ak-5 lng coal~ wi~h ~ ~i.nder and wlt;h a ~ine-gxain COmbUStiOll inhlbitor m~xed therein in the fo~ of calc~um carbonate an~for dolomite~ whi~h has~ beer~ ~dded to the init:ial fuel briquette mix~ure in a quan~i.ty in ex~e~ of 2~ ~y weight, volati:Le ~on&tl~u-~nts ~elnq elimi.nated Pro~ the fruel briquette.
Th~ term volatile ~ons~t~ents denote~ ~ate~ vApor, ~snd ~l~o hydroc~rbon~. Test~ hâve Bhowrl that vol3t:ile con~tituento are libe~ated at ev~n ~ery 3.ow temperatures. ~he volatlle const;Ltu-e~t~ ori~3inate ~om the inltial mi~ture, ~.g., from the binder.
The heat treatment i5 eP~ected neverthele~;s even i~ there are no volat~le constituents present.
A 6at:l6faatory heat treatmerlt is obtained even at te~npera~
tures of littlo ovor 100-C. The temperatures o~ t,he ~eat tr~at-ment 6hould not ~xc~eed 500'~.
In th~æ ~uel bric~ettes aa¢ordlng t~ the t nvention, the ~alaium aar~onat:e 2Ind~0r the dolo~ite ~ulI111 a new fun~tio~, i.e. thal; o~ a ao~ ustic~n inhi~itGr. The addition of calciu~
carbonatl3 and~or dolomi~e has ~een mixed lnto the initial mixture Ln a quan~ity suffi~ient ~or this puxpose and w:ith ~
flneness sufflc:ient; ~or this purpose. ~uring the heat-~rea~ment the fue~ briquett~si unde~go hardening. They do not dis~ntegrate on handl lng .
In ad~ition, ~hey ret:ain th~ir shape ~ufflcient:ly du~ing combus~$on, even when bllrning ~way.

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20058~3 Conse~uently, durlng combust:ioni of the fuel bri.quettes aocording to th~ inventi>on a calcium-contcl~n~ng a~;h laye~ o~
adequa~e th~eknessi continually forms around the lr,,dividual brlquett~es and enclo~es tho un~urn.ed cor~ like a closed she:ll as it were, ~o~m~ ~ dlffuGi.on bar~ler to the oxygen requir~3d ~or combustion o~ the car~on ca~ri~r and allows oxygen to pZ16S only ln a quanti~y 6uch that the~e are no distur~ingly high tempexatt~xes. The ~uantity of co~bustion ~nhibitor ~ixed into the product is adjusted in thiC way.
3ur~nc3 bu~ning, ao ths d~amet~r of th~ unburned core decrea~es the ash layer .become~ thicker an~ mor~ ota~l~ as ~l ~hell, BO that no ~sturbingly high te~per,~tures occur duxirlcJ
the entire combu~t1on of the fuel ~risuet~.~s accordin~ to the invention~ On the othe~ hand, the tem~er~tures are adequate for desul~uri.zatlon, calc1um ~ulfite o:r c~lcium ~ulfate, or magnesium ~ulf~te or m~g~eslum ~ul~ate ~or~ing and going int:o the ash. A~ording~ to the ~nvention, ther~efore, it ~8 ~lso possible to use petroleu~ cok- having a hil~h 6ulfur content.
Thei degree of desul~uri~tlon tS a's much a.s 80~ and moxe.
There are nu~erous possibil~ties of development withln the inventlon. A prefe~rred embodi~ent of the invention whic:h i~;
particularly lmport;ant econom$~ally, s~nce ~arge quantit:ies of petroleuT~ coke and pitch, are forme~ in pet;roleum di~tillation, is chara~terized in that. the carbon carrier consists of petroleur~ aoXe and the combustton inhibito~ has been added to the initial mixkure~ ln a quantity in exce~ of 3% by welght.
Fuel briquett;es aocord~ng to the invention have prov~d ~atis~actory ~n wh~.ch the bi~der i~ a bitLlminous bri~ue~.tin~

XC~OS83;~

~lhder, e.g. pitch, W~iCh has ~een added to the ini.tial l~ixture in a quantlty of 5 l:o 10~ by weight;, pre~era~ly ln a guantity o~
abou~ 8% by ~eight.
Also satisfa~ory are ~uel brl~uettes in wh$ch t.he binder :Ls ~u~ltQ w.~ste li~uor, which ha~ beeln ad~ed to the lnitla:l mlxture in a quantity o~ ~ to 10~ by weight., prefera~ly in a quant~ty of a~out 6~ by we~ght. Ot~er bind~r~ c~n b~3 used according to 1;he inventlon. The c:o~ustion inhibitor i~ preferably solely ca~cium carbonate. The grai.n ~iz:e of th~
carbon carrler in the fuel ~riq~lettes according to ~h~ invent;lon 3hould not be exc~sC~ive but ~s usually belc~w 3 mm. Some larg~3r q~n-slze component:s do not ha~e an adver~:e ef~ect. Th~. graln ~iz~ of th~ oombusti.on inh$b~to~ should ~e 60 ad~u~ted aR to give the ef~ects desc~ d. A graln ~ize o~ le~s than 1 mm i~
there~ore advantage,ously used.
~ he fuel bri~let~es aooxding to the invent~on can be manu~actured in vari,ous ways us~.ng convQntional br~quettlng technology ald~. More particul~rly, brlqu~tting presse~ can ~)e used. ~h13 subject o~ the~ ~nvent,ion i8 alsc~ a process for productlon of ~uel briguettes of' the compo~;ltion indicated, wherein the ~ne~grzlin c~,r~oh cz,rrier, the binder and the ine-grain CombUE;t~ on ~nhib~tor a~e mixed and pre~orms a~e mo].ded ~rom the mixture an~l wherein by a heat trez\tment of a tempere~ure below the ~eaction t:emper2ture o~ the combustion 25 inh~ bitor the pr~3for~s are hardened and any volatile con~tltuents present are ~uff~Lciently comp~et.ely eliminated. Hydrocarbons ~re also liberated even ~t 300'C. W~ter vapor is el~minated too at tempe~a~ul-es a~ove l.Q0-C i~ thQ pre~orm~ co~tain water.

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2~0S83~

In a preferred embodiment of the im ent.~.on the heat treatment i~ carried out in a rotary tubul~r furn~lc~ c~ntaining an immex~ion bed 20r t~e preform~, ~uch bed consisting O:e ~ine-grain pe~roleum coke (G~man Paten'c l~ocument 37 2~ 4,64) . Tl~o hardening S desc~ri~ed 16 obta.ined witll a ~ery non-in~ur:Lous e~fect in the ~mmer6~0n bed.
The ~u21 br1quet:1:e~ o~' the inven,tion thus adva~nt;ageou~y c~mprise a~ body heat-~treat:ed to clrive off volat~les and predomlnan~ly con~lt:uted of a fi.ne-gr~$n c~rbon carrier ~;elec:t:ed Srom ~he group wh~ch con~ t~ Or pQt~o~um c:o~e, coal and ~ixt,ure~
thereoS, a blnder ret:ainirJg th~ body in a co:herent form, and zl ~ne-grain combu~iorl ~nhibitor pre~nt in a.n amount in exces~; of 2% ~y we~ght oS a oompos~tion oo~tai:n~ng thel carrier, bincler substanc~ alnd combus~ion ~nhi~tor~ f:rom which the b~dy 1~
~ormed, the combu~tion inhi~itor be~ng sale~ted from ~he yroup wh1ch cons1st~ of ~alcium car~bonate, dolomite and mixture~
thereo2.
The me~hod compr1ses the steps oe:
(a) so2~ng A ~omposltion consist~ng e~sent~ally o2 a flne-grain cnrbon carri-r ~lected from the l3roup wh~c~ c~nsist~
of petroleum co~e, coal an~ mixtures thereof~ a binder capa~le oi' retalnlng ~l body o~ ~he carbon car~or ln a cohe~en~ i~orm, and fine-graln com~ust,lon.~nhi~itor selected from ~he group wh~ch cons~sts oP caloium carbonate, dolo~:ite ~nd m~xtures thexeo~
present ln an amo~nt ~n ex~es~ of 2% by weigh~ of the compo~ition;
(~ molding preforms having conf:Lguratlons o~ ~riquettes from the compos~,t~on; and ~ 6 ]

2(~C)5833 ~ c~ heating the p~eforms to ~ temperatule ~ufficient t:o na~den th~ preform~ ~nto fuel briqu~sttes and to drive Of~
vol~tllo aono~ucn~ ro~ thc ~ s~ tne temperac~re ~ei.ng below a ~e~ction te~perat.u~ o~ the car~bon ,~arrler with t:he combustion inh~bitor.

~U~7 DEs~xIprIoN ~ EY~9'I~
Th~ above and other ob~ects, featurel~ and advantages of my i~vention ~111 be~o~e more readily app~rent from ~h~e ~ollowing description, reference be~ng made to the acaompanying h~ghly diagrammatic drawln(~ 1n whlch th~e ~c~le l?IGUI~E of wnich i~
b~ocX diagram illu~trating the me~hc)d o~ tho invent.ion.

~e~ EI~8~1P~
As can be seen ~rom the drawin~, petroleLIm coke or a m~xture o~ petroleum coke and non-ca~lng coal f~,om E~ource 10, a binder ~5 which can be pitch o:r wa~te ~ul~ite liquor ~'~om a ~ou~ce 11 and the combustion inhibitor in the ~or~l of c~ ium carbonate, dolomite or ~ixturol~ th~r~!of Pro~ a ~our~e 12 are blonded in mixture 13 and the mixtur~ i~ mo:Ldec~ to ~on~l briquettes o ~
~iz~ and s:hape corr~3ponding to the charcoa:L briquet:tes utilized ~or domestic pu~pose~i. The preform~, are then ~ub~ected to hea~
trea~ent at 15 in a rotary tube ~o~mation with a p~troleum cok:e in a immer~ion ~ed t;he~eo~ in t~e rotary tube formation to ~rive of~ volat~Les as represented at 16. The prc~duo~ ic the fuel br~uettes shown ~t 17.

t 7 ) 1744~

~ IFIC ~XA~5~LE~, A compo~1tion con~1st:lng essenti.a11y o~ 8% ~y WC!lght ~itch, 5 by weight o~ calcium carbonate o~ a grcund l:o a part:icle l3~ze rango o~ 0.1 to 0.5 ~m ancl the ba1arl~e ~Qt~o1eum co~e with a paxtlcle BiZe rang~ of 0,S to 2.5 mm ~ b1ende~ ~n ~ con~çntiona1 mixer and ~he resu1ting mixture i~ then molded to ~orm br:lq~ett.es.
The resultlng pre~orms are then heat treated in a rotary ~ube ~ormat1On by 1mmersion in ~ petro1eum coXe bed at a ~empe~ature o~
300'C to driv~ of~ vo~ati1e8 and harden the preform~ into t~e briquettes.
Th- br1quette~ ar~ ~ound to burn ~n a h1qh1y uni~orm ~anner wlthout the formation o~ hot ~pots with little emi~sion o~ ~ul~ur compounds. The a~h is ~ound to cont~in su1f'ur compounds wh~ch drive from the su1fur content of the petro1eum coke.
Similar result~ are o~tained when 6% wa~te 8u1fite 1iguor i~
subst~tute~ ~or the pitch binder.

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Claims (19)

1. A fuel briquette for combustion to produce heat, comprising a body heat-treated to drive off volatiles and predominantly constituted of a fine-grain carbon carrier selected from the group which consists of petroleum coke, coal and mixtures thereof, a binder retaining said body in a coherent form, and a fine-grain combustion inhibitor present in an amount in excess of 2% by weight of, a composition. containing said carrier, binder substance and combustion inhibitor from which said body is formed, said combustion inhibitor being selected from the group which consists of calcium carbonate, dolomite and mixtures thereof.

2. The fuel briquette defined in claim 1 wherein said coal is a noncaking coal.

3. The fuel briquette defined in claim 1 wherein said carbon carrier consists of petroleum coke and said combustion inhibitor is present in an amount corresponding to in excess of 3% by weight of said composition.

4. The fuel briquette defined in claim 1 wherein said binder is a bituminous briquetting binder present in an amount corresponding to 5 to 10% by weight of said composition.

5. The fuel briquette defined in claim 4 wherein said binder is pitch and is present in an amount corresponding to about 8%
by weight of said composition.

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6. The fuel briquette defined in claim 1 wherein said binder is a sulfite waste liquor present in an amount corresponding to 5 to 10% by weight of said composition.

7. The fuel briquette defined in claim 6 wherein said binder is present in an amount corresponding to about 6% by weight of said composition.

8. The fuel briquette defined in claim 1 wherein said combustion inhibitor is solely calcium carbonate.

9. The fuel briquette defined in claim 1 wherein said combustion inhibitor has a grain size of less than 1 mm.

10. The fuel briquette defined in claim 1 wherein said carbon carrier has a grain size of less than 3 mm.

11. A method of making fuel briquettes for combustion to produce heat, comprising the steps of:

(a) forming a composition consisting essentially of a fine-grain carbon carrier selected from the group which consists of petroleum coke, coal and mixtures thereof, a binder capable of retaining a body of said carbon carrier in a coherent form, and a fine-grain combustion inhibitor selected from the group which consists of calcium carbonate, dolomite and mixtures thereof present in an amount in excess of 2% by weight of said composition;
(b) molding preforms having configurations of briguettes [ 10 ]

from said composition; and (c) heating said preforms to a temperature sufficient to harden said performs into fuel briquettes and to drive off volatile constituents from said briquettes, said temperature being below a reaction temperature of said carbon carrier with said combustion inhibitor.

12. The method defined in claim 11 wherein said healing in step (c) is carried out at a temperature of less than 500°C.

13. The method defined in claim 12 wherein the heating in step (c) is carried out in a rotary tubular furnace containing an immersion bed for said preforms, said bed consisting of fine-grain petroleum coke.

14. The method defined in claimed 13 wherein said coal is a noncaking coal.

15. The method defined in claimed 13 wherein said carbon carrier consists of petroleum coke and said combustion inhibitor is present in an amount corresponding to in excess of 3% by weight of said composition.

16. The method defined in claim 15 wherein said binder is a bituminous briquetting binder present in an amount of 5 to 10%
by weight of said composition.

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17. The method defined in claim 15 wherein said binder is a sulfite waste liquor present in an amount of 5 to 10% by weight of said composition.

18. The method defined in claim 15 wherein said combustion inhibitor is solely calcium carbonate.

19. The method defined in claim 15 wherein said combustion inhibitor has a grain size of less than 1 mm and said carbon carrier has a grain size of less than 3 mm.

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