CA1113414A - Pyrolysis processes utilizing a particulate heat source - Google Patents
Pyrolysis processes utilizing a particulate heat sourceInfo
- Publication number
- CA1113414A CA1113414A CA280,355A CA280355A CA1113414A CA 1113414 A CA1113414 A CA 1113414A CA 280355 A CA280355 A CA 280355A CA 1113414 A CA1113414 A CA 1113414A
- Authority
- CA
- Canada
- Prior art keywords
- particulate
- pyrolysis
- heat
- source
- zone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B49/00—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated
- C10B49/16—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated with moving solid heat-carriers in divided form
Abstract
ABSTRACT
A solid carbonaceous material is pyrolyzed in a descending flow pyrolysis reactor in the presence of a particulate source of heat to yield a particulate carbon-containing solid residue. The particulate source of heat is obtained by educting with a gaseous source of oxygen the particulate carbon-containing solid residue from a fluidized bed into a first combustion zone coupled to a second combustion zone. A source of oxygen is introduced into the second combustion zone to oxidize carbon monoxide formed in the first combustion zone to heat the solid residue to the temperature of the particulate source of heat.
A solid carbonaceous material is pyrolyzed in a descending flow pyrolysis reactor in the presence of a particulate source of heat to yield a particulate carbon-containing solid residue. The particulate source of heat is obtained by educting with a gaseous source of oxygen the particulate carbon-containing solid residue from a fluidized bed into a first combustion zone coupled to a second combustion zone. A source of oxygen is introduced into the second combustion zone to oxidize carbon monoxide formed in the first combustion zone to heat the solid residue to the temperature of the particulate source of heat.
Description
~13414 The increasing scarcity of ~luid fossil fuels such as oil and natural gas is causing much attention to be directed towards converting solid carbonaceous materi,als such as coal, oil shale, tar sands, uintaite and solid waste to liquid and gaseous hydrocarbons by pyrolysis. Pyrolysis can occur under nonoxidizing conditions in a pyrolysis reactor in the presence of a particul~te source of heat to yield as products pyrolytic vapors containing hydrocarbons and a particul'~te carbon-containing solid residue. The particulate source of heat for eff`ecting the pyrolys,is of the carbonaceous material can be obtaincd by oxidizing carbon in the particulate carbon-containing solid residue in a combustion cllamber.
There are many problems associated with this use of a pyrolysis reactor and a combustion chamber in co~nl~ination for obtaining hydrocarbons from soli,d carbonaceous materials. One of these problems i,s caking of coal along the walls of the pyro],ysis reactor when the carbonaceous material is an aggrlomerative coal, parti,cularly an Eastern Un;ted States coal, which expe-rience shows to have a tendency to ag~omerate in a reactor, especial]y along the walls oI' the reactor.
Anotller probleln concerns trar-sfe~cring the particulate carbon-containing solid product from the pyrolysis reactor to the combus-tion chamber while at the same time preveilting oxygen that is present i,n the combustion cllalnber from enterillg the r~yrolysis reactor. If oxy~elllnanages to leak i,ntc~ the pyrolysis reacl,or, the value of tl3e hydrocarl~oll procluct is reduced anc,ll;~ol-(?over, a ~iolent e~l)losion may occ,uv~.
A, th-ird prol>lem concc-~rns the rleed to 113'-~ ni~e product,i,on ~ ca-~boll dil-xic~ln and min:i,ln:ize prcd-~ct,i,on o,f o<irbon ~031C-~'i c,~e - 30 i,n -tlle com'bus1;io~1 ~03ie i~ order -to nn'l~:i.mi7,(' l'C.`COVC`ry of l:]le ,~ _ ~k~
1113~14 heating value of the carbon-containing solid residue during oxidation. The kinetics and thermodynamic equilibria of the oxidation of carbon favour increased production of carbon monoxide relative to carbon dioxide at temperatures greater than about 1200F. (650C.) at long residence times when there is a stoichiometric deficiency of oxygen. Because pyrolysis of carbonaceous materials often is conducted at temperatures greater than 1200F. (650C.) and can approach temperatures higher than 2000F. (1100C.), it is necessary to form a particulate source of heat having temperatures greater and often considerably greater than 12000F. (650C.). Moreover, the particulate carbon-containing solid residue is only partly oxidized in a stoichio-metric deficiency of oxygen to form the particulate source of heat. Thus production of carbon monoxide inevitably occurs during the oxidation of the particulate carbon-containing solid residue. The carbon monoxide formed represents a loss of thermal efficiency of the process.
Therefore, there is a need for a process and an apparatus for obtaining values from a solid carbonaceous material by pyrolysis which are sueful for agglomerative coals; which, when a particulate carbon-containing solid residue of pyrolysis of the carbonaceous material is oxidized to form a particulate source of heat to pyrolyze the carbonaceous material, prevent oxygen from entering into the pyrolysis reaction; and which maximize pro-duction of carbon dioxide while minimizing production of carbon monoxide.
The present invention therefore provides a method in which the fluidized bed is fluidized by a fluidizing gas contain-ng oxygen.
Preferably there is provided a continuous process for pyrolysis of particulate solid carbonaceous materials which ?
4~
comprises, in combination, the steps of:
a) subjecting a particulate solid carbonaceous material to flash pyrolysis by continuously:
(i) transporting the particulate solid carbonaceous material contained in a carrier gas which is substantially nondeleteriously reactive with respect to products of pyrolysis of the particulate solid carbonaceous material to a substantially vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature below about 2000F;
(ii) feeding a particulate source of heat at a te~perature above the pyrolysis temperature and comprising heated particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iii) forming a turbulent mixture of the particulate source of heat, particulate solid carbonaceous material and carrier gas to pyrolyze the particulate solid carbonaceous material and yield a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
b) passing the pyrolysis product stream from the pyrolysis reactor to a first separation zone and separating at least the bulk of the solids from the vapor mixture; and c) forming the par~iculate source of heat by:
(i) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material and separated from the vapour mixture to a fluidized be~ around a substantially vertically oriented - 3a -~3~
open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combust-ion zone;
(ii) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by inject-ing a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the particulate carbon containing solid residue thereby heating the particulate carbon containing solid residue and to transport particulate carbon containing solid residue and gaSeQus combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone;
(iii) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones in combination being sufficient to generate the particulate source of heat; and (iv) passing the formed particulate source of heat and the gaseous combuation products from the second combustion zone to a second separation zone and separating the particulate source of heat from the gaseous combuation products of the particulate carbon containing solid residue and feeding the thusly separated particulate source of heat to the pyrolysis reactor.
Preferably the invention provides a process for pyrolysis of solid carbonaceous materials by heat transferred thereto by a particulate source of heat to yield a particulate - 3b -~13~
carbon~colltaining solid residue as a product of pyrolysis, t;he particulate source of heat being formed by oxidizing at least a portion of the particulate carbon-containing solid residue, characterised by transporting at least a portion of the particulate carbon-containing solid residue formed by pyrolysis of the solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zons;
educting sol.id residue from the fluidized bed into the first combustion zone by illjecting a gaseous source of oxygen upwardly i.nto the conduit to oxidize carbon in the solid residue for partly lleating the solid re-idue and to transport solid residue and gaseous com~ustion products of the solid residue, including carbon monoxide, to a second combustion zone; and introdllcing a source of oxygen into the second combustion zone in an amount at least equal to 50% of tho molar feed of carbon monoxide to the second combustion zone, t.he total oxygen ~eed to the :first and second combustion zones being sufficient to generate the particulate source of heat.
Prefera.bly the said conduit is spaced ~part from said riser al~d the particulate carbon~conta.ining solid res.idue is ~luidized : in the l`luidized bed by an upward flcw of a fluidlzing gas that passes into the riser through the space between t;he riser and tile COlldlli t . The ilui.dizing gas desirably contains oxy~en.
In prel`er3ed embodiments of the inventi.oll the pyrolysis process is a so~c~li.ed flasll pyrolysi.s st;ep, performed by cont;inuously tra]~sporti.ng pa:rt:iculate solid carbo1laceouc mater~
fee~ contaill.ed in a c.lrrieJ ~ras whi.ch ;s subst;al-l-li.ally 1~13414 nondeleteriously reactive with respect to products of pyrolysis to a vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at ; a temperature below about 2000 F. ( 1100 C. ); feeding the particulate source of heat at a temperature above the pyrolysis temperature to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature; forming a turbulent mixture of the particulate `
source of heat, particulate solid carbonaceous material feed and the carrier gas to pyrolyze the solid carbonaceous material feed and yield a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon-containing solid residue of pyrolysis, and a vapor mixture of carrier gas .
; and pyrolytic vapors comprising hydrocarbons; and passing the ;; pyrolysis product stream from the pyrolysis reactor to a first separation zone to separate at least the bulk of the solids from -the vapor mixture.
The first separation zone may be a cyclone separation zone.
; The formed particulate source of heat may be separated from the gaseous combustion products of the second combustion zone in a(secon~ cyclone separation zone. Alternatively, the second combustion zone may comprise a cyclone oxidation-separation zone.
The process is preferably performed with the use of a pyrolysis reactor ha~ing a solids feed inlet for the solid carbonaceous material feed and a vertically oriented chamber surrounding the upper portion of the pyrolysis reactor, the inner peripheral wall of said chamber forming ar overflow weir to a vertically oriented mixing zone of the reactor, the particulate solid carbonaceous material being transported ~134~4 in a carrier gas to the solids feed inlet and thence being injected into the mixing zone, the particulate source of heat being fed to the said vertically oriented chamber and being fluidized in such chamber by a flow of a fluidizing gas substantially nondeleteriously reactive with respect to the products of pyrolysis, the fluidized particulate source of heat discharging over said weir and downwardly into said mixing zone to form a turbulent mixture with the particulate solid carbon-aceous material, said mixture passing downwardly from the mixing zone to the pyrolysis zone of the pyrolysis reactor to pyrolyze the solid carbonaceous material.
The invention also provides an apparatus in which the combustion chamber is a cyclone for separating formed particulate source of heat from such formed combustion gas.
Such apparatus is particularly useful for combination with a pyrolysis reactor utilising a particulate solid source of heat. Accordingly, in another aspect the invention provides an apparatus for pyrolysis of solid carbonaceous ,~
~f j 1~13~4 materials~ comprising a descending flow pyrolysis reactor;
means for forming a turbulent mixture of a particulate source of heat and a solid carbonaceous material contained in a carrier gas for introduction into the pyrolysis reactor to pyroiyze the solid carbonaceous feed to form a pyrolysis product stream containing a vapor mixture and, as solids, the particulate source of heat and a particulate carbon-containin~ solid residue of pyrolysis; a first separator for separating at least th~ bulk of the solids from the vapor mixture in the pyrolysis product stream; means for transferring the pyrolysis product stream to the first separator fro~ the pyrolysis reactor; means . .
for f~ming the particulate source of heat, comprising a vessel containing a fluidized bed of the separated solids around an open, substantially vertically oriented conduit, a substantially vertically oriented riser in open communication . with the conduit, a combustion chamber in communication with the riser, means for introducing a gaseous source of oxygen upwardly into the conduit to educt solids from the fluidized bed into the conduit, and means for introducing oxygen into the combustion chamber to heat the solids to form the particulate source of heat, means for passing the separated solids from the first separator to the fluidized bed; means for transferring the particulate source of heat from the second combustion chamber to the second separator; a second separator for separating the particulate source of heat from the gaseous combustion ~: product; and means for transferring the separated particulate source of heat from the second separator to the pyrolysis reactor, ' ~referably the said conduit is spaced apart from said riscr The first and second separators may con~eniently both be 1~ r;~L~1!4 cyclone separators although in a modified arrangement the second combustion cha3nber and the second separator are integrated and constituted by a cyclone oxidation-separation device.
In a preferred embodi~ent of the apparatus, the pyrolysis reactor contains a substantially vertically oriented mixing section and a su~stal3tially ~ertically oriented pyrolysis section, and has a solids feed inlet, a substanti.ally vertically or;ented ch~nber surrounding the upper portion of the reactor and ha~ing an inner peripheral wall that forms an overflow weir to the vertically ori.ented mixing section, - and the means for forming a turbu.lent mixture comprises means for feeding par':iculate source o~ heat to t;he vertically oriented chamber; means for introducing a fluidizing gas into the cha1nber to maintain the particul.ate source of heat therein in a fluidized state; and means for injectil~g the solid carbonaceous feed contained in the ca.rrier gas from tthe solids feed inlet into the mixi.ng section to form tlle resultant turbulellt mixture.
Irl anotller aspect the invention provides an apparatus for pyrol.ysis of agglomerati~re coals, comprising a descelldillg flow pyrolysis reactor con1aining a substan~:ially vertically orienled n~i~cingr section, a su1~stanttially vertically or.iented pyrolysi.s section, a solids feed :in1.et, a1-lcl a su1~t;a1lt:ially erticall.~ oriented cham1~er surrounding t}~c~ up~er por1;;on of the reac-tor, t;he im-er pe1-i.pheral ~Tall of t1~e cl1an31~er formi1~r an o~er~lo~r1~re:i.r to the mi.~i.ng section, ~lle:ce-in an ag~lo1~3erati~-r coal feed containecl in. a ca-rri.er gas is combillec~ a partici~l.c~..t;e SOUl~C.? of heat IllldCr l-Urb~lCllt f1O~r condii;ic-ns :in tlle pyrolysis sect:i.on Or t:he p!T olysis ro<lc-t~ co yiel.d a pyrolysis product stream containing as solids the particulate source of heat and a particulate carbon containing solid residue of pyrolysis, and a ~apor mixture; means for feeding the particulate source of heat to the vertically oriented chamber; means for introducing a fluidizing gas into the chamber to maintain the particulate source of heat therein in a fluidized state; means for passing a coal feed from the solids feed inlet into the mixing section; a first cyclone separator in con~nunication with the pyrolysis reactor for separating at least the bulk of the solids in the pyrolysis product stream from the vapor mixture in the pyrolysis product stream; means for forming the particulate source of heat, comprising a vessel containing a fluidized bed of the separat~l solids arour~d an open, substantially vertically oriented conduit, a substantially vertically oriented riser in open communication with the vertically oriented conduit and separated therefrom, a second combustion chamber in communication with the riser, means for introducing a gaseous source of oxygen upwardly into the conduit to educt solids from the fluidized bed into the conduit and to partially oxidize carbon in the solids to heat the solids with attendant formation of combustion products, means for introducing o~gen into the second combustion ch~nber to further heat the solids to form the particulatc source of heat; a dipleg I`rom the first cyclorle separator to the fluidized bed for transferring the scparated soli~s from the first cyclone separator to the fluidized bed, a second cyclone separator in communica-tlon with the coml~usiion cham~Gr for separatirlg tl~e particulate source of heat from tl~e ~cr~seous com~ustion products, and a d:;ple~r from t~le second cyclone separator to the cllamber surrounding l}le uI)per po:rt;oll of the pyrol-ysis reaG-toJ J`or transferring t}le p.lrt3.cuL~te source of ~ g _ 4~
heat to the pyrolyæis reactor. ~:
Further preferable features of the process of the invention and of the apparatus thereof will be discussed and described in the following, with reference to the accompanying drawings in which:
~ IGURE 1 illustrates . diagrammatically a process and an apparatus embodying features of this invention; and .-FIGURE 2 is an enlarged and more detailed view of the region marked 2 in ~igure 1.
The drawings illustrate a pyrolysis unit 8 comprising a descending flow pyrolysis reactor 10 which has a substantially vertically oriented mixing sectiosl or zone 12 and a substantially vertically oriented pyrolysis section or zone 14 below the mixing section. Arrow 1~ shows the approximate extent of the pyrolysis section. The reactor has an elbow ~, 18 towards the end of the pyroly~is section, by which it can be supported. The lower end 20 of the reactor termînates in . a separation zonè such as first cyclone separator 22.
A generally upright annular solids feed inlet 24 `t 20 terminating within the mixing section 12 and constricted at its end to form a nozzle 26 is provided for introducing a so1id carbonaceous materi.al into the mixing region.
-The upper end 28 of the reactor is open and of larger diameter than the nozzle 26, thereby leaving an annular gap 30 between the upper end 28 of the reactor and the nozzle 26.
A vertically oriented fluidising chamber or well 32 surrounds the upper portion of the reactor and is formed by a preferably annular section 3~ which connects the wall 36 of the solids feed : inlet above wllere the wall constricts to for.m the nozzle 26 and the upper portion 2~ of the reactor, The chamber 32 ~3~13~4 surrounds the nozzle 26 and a portion of the upper wall 28 of the reactor. The inner peripheral wall of the chamber 32 is formed by thè upper wall 28 of the reactor and serves as an over~low weir to the mixing section 12 of the reactor 10.
A second vertically oriented solids inlet 38 terminates in the annulàr fluidizing chamber 32, prefe~ably at a level below the top edge 40 of the pyrolysis reactor 10, There is a gas inlet 42 to the bottom of the fluidizing chamber for a fluidizing gas. Means are provided such as a cylindrical, horizontally oriented, perforated plate 44 positioned towards the oottom of the fluidizing chamber below the end of the second inlet for distributing the fluidizing gas so that the fluidizing gas flows u]~wardly through the fluidizing chamber.
The first cyclone separator 22 serves to separate a particulate carbon-containing solid residue of pyrolysis from the gaseous products of pyrolysis.
The particulate source of heat for the pyrolysis reactor is forméd by oxidizing at least a portion of the particulate carbon-containi.ng solid re~idue in a combustion unit 50.
The combustion unit includes a vessel 52 containing a fluidized bed 60 of a particulate carbon-conta.ining solid residue around an open, substantially vertica]ly oriented conduit or tube 54. There i.s a gas inlet 56 for a transport gas at the base of the vessei 52 w13ich narrows down to form a vertical]y oriented nozz.le 5~ for inJection of the tran~port gas directly upwardly into the open conduit 5~1. The ~luidized bed 60 of carbon-containing solid residue is fluidized by a fluidi7ing gas entering the cbalnber througll a gas i.nlet 62 at ~ ~3~
the base of the vessel. The fluiclizing gas is distributed throughout the fluidized bed by means of a second, horizontally oriented perforated distributor plate 64.
The top 66 of the vessel 52 tapers upwardly and i-.-wardly to connect to a vertically oriented riser 68. The riser and conduit comprise a first combustion zone or chamber. The riser couples the vessel 52 to a second combustion zone or chamber 70.
The conduit 54 is below the riser 68 and tlle top edge 72 of the conduit is spaced apart from the riser so that an annular gap of space 74 is formed between the inlet 76 to the riser and the top edge 72 of the conduit. The top portion 71 of the conduit can be tapered inwardly so that the diameter of the conduit at its top edge is smaller than the diameter of the riser.
A vertically oriented standpipe or dipleg 78 having stripping gas inlets 122 extends from the bottom of the first cyclone separator 22 into the ves.sel 52 below the top 80 of the flu;dized bed of carbon-containillg solid residue. Solids separated by the first cyclone separator are transferred througll this dipleg into the vessel.
There is an inlet 82 at the upper portion of the riser 68 for introduction of a source of oxygell into the second comb-lstion chamber 70. The second combustion chamber is in open comm~lication with a second separa1;or such as cyclone separator 84. This separator serves to separate a particulate source of heat generated in the combus-tion unit 50 from any combustion gases present in the com~ustion unit. The particulate source o~ heat is transferred from the second cyclone separa-tor 8ll to 1;1~e second inlet 38 of the pyrolysi,s reactor throu~ll a vertica,,ly or:ienl;ed d;pleg or stancdp;pe 86 1~i3L?~'~4 originating at the bottom o~ the second cyclone separator 84 and terminating in the second inlet 38. The length of the -standpipe 86 is chosen to balance the accumulation of differential pressures throughout the remainder of -the system. Inlets 88 for a stripping gas are provided along the length of the standpipe 86.
In summary, what has' been described is an apparatus for pyrolysis of a ~solid carbonaceous material comprising two ntain units, a pyrolysis unit 8 and a combustion unit 50.
These t~o units are coupled by two cyclone separators 22, 84 and two vertically oriented stanclpipes or risers 78, 86 which allow car~on-containing solid residue to be transferred from the pyrolysis unit to the combustion unit and particulate source of heat to be transferred from the combustion unit to the pyrolysis unit, respectively.
In the proc~ss of this invention, a particulate solid carbonaceous ~1aterial is subjected to flasll pyrolysis by transporting the particulate solid carbonaceous material feed containcd in a carrier gas through. the first feed i.nlet 24- to the feed no~le 26 and thus to the pyrolysi.s reactor 10.
The carri.er ~as is substantially nonde]eteriously reacti~e Wit~l respect to the products of pyr.olysis and may sc~rve as a diluen-t to pre~ent se].f-agg]o~neration of the carbonaceous ma-tericLl.
.As used hAl~ein, by a "nondeleteriously reacti.ve" gas there is l~eallt a ~IS StreaT,Il WhiCh iS SUbStant~ 11Y free 0f free OXYgel1. A1 l;hOUgh the gas ~nay con.-tain con.stituc~llts 1,llLt reac-t uncler nonox.idizing conditions w-itll pyrolysis ~)rod~cts to upgrade -thei.r ~T.-Llue, the gas sl-ould no'c conta;n cons-tit,uents that dcgrade pyroly.5:i.s proc]ucts. T]le carri.or 3o gas may, ~or ~ st,al~ccT be -t.]le O:)~ -L.S prCldliCt O:l~ pyrolys ~3414 ste~2 which will react under suitable conditions with char or coke formed from pyrolysis to yield, by water-gas shift reactions, hydrogen that serves to react with and stabilize unsaturates in the products of pyrolysis; any desired inert gas;
or mixtures thereof. The carrier gas can, for instance, be synthesis gas, especially a hyTdrogen-enriched synthesis gas.
The carbollaceous material may be treated before it is fed to the first fluidized bed by processes such as removal of inorganic fractions by magnetic sepàration and classification, particularly in the case of municipal solid waste. The carbonaceous material also can be dried to reduce its moisture content. The solid carbonaceous material is usually comminuted to increase th<: surface area avai]able for pyrolysis.
Preferably a substantial portion of the carbonaceous material is o~ a particule size of less than about 1000 microns to pre~sent a large surface-to-volume ratio to obtain rapid heating of the coal in the pyrolysis zone. Rapid heating results in improved yields of hydrocarbons. For an agglomerative coal, the partlcle size is preferably mainly less than a~out 250 microns because aggLomerative coals are well -known to plasticize and agglutinate at relatively low temperatures i.e., 400 to 850 F. (200 - 450 C.). An agglomerative coal should -therefore be rapidly hcated through the plastic state be~ore it strikes the wall of a pyrolysis reactor to prevent caking on the reactor waLl.s. Because thc rate at ~Thich a coal particle can be lleated increases as particle size decreases, it is important that an agglomerative coal bc comminuted to 250 ~licrons or less, depending 031 the si~e and conriguration of the pyrolys;s re~cl->r, so that substantia31y all the coal particle3 have l~assccl thro~g}l t~le ~i3'~:~4 plastic state and have become non-tacky by the time the coal particles stri~e a reactor wall, ~or example, when a bituminous high-~ol.atile C coal which agglomerates at temper~tures above 500 F. (260 C.) is pyrolyzed at a temperature of 1075 F. (580 C.) in a 10 inch (250 mm) diameter pyrolysis reactor of the design shown in Figure 1 and described below, the coal should be comminuted to a size less than 250 mi.crons in diameter to prevent caking on the reactor walls, Coal parti.cles larger than 250 microns in diameter could strike the reactor walls before passing through the plastic state.
The carbonaceous material introduced into the pyrolysis ,' reactor is preferably substantially free of fines less tllan about, 10 microns in di.ameter, because carbon-containing solid residue fincs 3~esu~.-ting from pyrolysis of the carbonaceous material have a tendency to be carried into and contaminate the liquid hydrocarbon. products.
Simu].taneously with the introduction of the carbonaceous materi.al ~eed, there is introduced. a particulate source of`
heat i,nto the fluid;zing cha1nber 32 through the second vertically oriented inlet 38. Because in tll-_ preferred embodiment the second inlet 38 terminates bel-)w the top edge 40 of the pyrolys:is reactor 10, incom;l-lg "art:ic~llatc? source of heat bui.lds up in the fluidizing chaniber be3o~J the weir 28 to form a solids seal. The particula.te source of lleat in chamber 32 is mainta.ined in a fluidized st~te in the chamber ~y introduction O:r a flu,idiz:ing gas st:ream -tllrc)~ l? tlle gas .inlet;
42~ The f`lu:i,di~ing gas is distributed b~r the d--stributor plate 411 tC? maintai.n the particulat-e SOUl'Ce Or )leat in a -fluidiz(?cl st~l1;e throughout l;h-' cl?amber. ~s addi t.. ,?nal I?arl~i CUlat;r? source of heat is ini;~oAllced :illt~? tlle cl~ambe:r t~ .ll`tiCUlatC SOllrCC
of heat passes over the upper end 40 of the weir and through the opening 30 between the weir and the nozzle 26, into the mixing section 12 of the pyrolysis reactor 10 with aid of fluidizing gas. An advantage of this weir-like configuration is that substantially steady flow of fluidi~ed particulate source of heat enters the mixing section because the mass of the particulate source of heat backed up behind the weir of the reactor damps minor fluctuations in the flow of the particulate source of heat.
In the mixing zone of the pyrolysis reactor, the carbonaceous material conta.ined in th~ carrier gas-is discharged from the nozz]~ as a fluid jet 112 expanding towards the reactor wall at an angle of about 20 or less as shown by dotted lines 88 ~hich represent ths periphery of the fluid jet. Once the particulate source of heat is inside the mixing section, it falls into the path of the fluid jet 112 of the carbonaceous material feed stream and carrier gas coming from the nozzle and is entrained thereby, yiel.ding a resultant turbulent mixture of the particulate source of heat, particulate solid carbonaceous materia] feed, and the carrier gas, The jet has a frce core region 113 of carbonaceous material, as delineated by the V~sha.ped dotted line 114s extending considerably into the reactor, but as tlle jet expands, the particula.te source of lleat present is entrained 1~ith mixing of the carbonaceous material in -th.e pOl-tiOn of thc flui~ jet 112 arou.nd the free core re~i.on 113, The par-ticulate source of heat along the ~eri.p~-Zery 88 of the f1a~:id 3et prefera~ly he&ts the carbonaceous materi.al in the ca.se of an ag~lomeralive coal to a temperature al~ove~ tho temperat;ure at whic}- t]!e coal J S tacky. In tlle re~ion 116 ~et~een t~l react.o3 walls and 3~4 the fluid jet 112, there is unentrained particulate source of heat.
This mixing of the particulate source of heat with the solid carbonaceous material in the mixing zone 12 initiates heat transfer from the particulate solid source of heat to the carbonaceous material, causing pyrolysis in the pyrolysis sect;ion 14 of the pyrolysis reactor 10. Pyrolysis is a combination of vaporization and cracking reactions. As the vaporlzation and cracking ractions occur, condensible and noncondensible hydrocarbons are generated from the carbonaceolls material with an attenc~ant production of a carbon-containing solid residue such as coke or char. An effective pyrolysis time i 9 le.ss tllan about 5 seconds, and -treferably from about 0.1 to about 3 seconds, to maximize yield of middle distillates, Middle distillates are the middle boiling hydrocarbons, i.e., C5 hydrocarbons to hydrocarbons having a boiling end point of about 950 ~. (510 C-)- These hydrocarbons are useful for the production of gasoline, diese]. fuel, heating fuel., and the li~e.
As used herei.n, "pyrolysis timc" mealls the time from when th.e carbonaceous material con-tacts the ~arti.cu]ate source of` heat until the pyrolytic vapors produced by pyrolysi.s are separated from the particulate source of lleat in the first sepa.ration zone 22, as described below.
A convellient measure of pyrolysis ti.me ;s the average residence tir~e of the carrier ~a3 in the p~rolysis section 14 of tlle pyrolysis reactor ancl. the first scp<trator 2~.
Snflicient pyrolysis time must ~e pro~ri~ed to heat tlle carbon~cec-us rrlater;.al to the pyrolysis tcl.;peratll:re.
All advanta~;c-~ of t;he pyro:lysis react~ S~10~!11. -in the clrawinp~s is tlla-t thc turbul.ent flow c<-uses -tll( s~.l.id - ~-7 -1~3'};~4 carbonaceous material feed to be heated rapidly, which improves yields, In the case of agglomerative coals, buildups of coal particles on the reactor walls are prevented by the rapid heating and turbulent flow. Preferably the particulate source of heat enters the mixing section 12 at a rate of flow less than turbulent and the solid carbonaceous material enters the mixing section through the nozzle under the turbulent flow conditions at a rate sufficiently high for the resultant mixed stream from these two inlet streams to be turbulent.
Turbulent flow results in intimate contact be-tweerl the solid carbonaceous material and the particulate source of heat particles, thereby yieldin~ rapid heating of the carbonaceous material. In the case of an agglomerative coal, the turbulence results in mixing o~ the particulate source of heat with the coal particles in the inner portion of the fluid jet, thereby quickl3r heating these coal particles through the tacky/plastic state. As used herein, "turbulent" means that the stream ~7s a Reynolds flow index Number greater than 2000 as calculated by the velocity of the carrier gas at operating conditions. Laminar flow in the pyrolysis reactor tends to severely limit the rate of heat transrer within the pyrolysis zone. Process parameters such as the noz~le diameter ancl mass flow ratc o~ the carbonaceous material and its carrier gas are varied to maintain the flow rate of the particulate stream entering the ~irst inlet in tlie turbulent region.
The end o~ the sc,lids feecl inle-t is pref`era7,1y cooled, e.g. I~y water when pyrolyzing an agglomerati~re c~al because othel^wise ths lnlet might be heated abo~c tlle point at which the coRl becomcs tacliy, by hea-t transfer f`lom t]le ~articulate source o~ heat s~urroundirlg the end of t}l~ solid~, feed inlet.
l8 -9.3~i~i4:~
Although the drawings show a solids feed inlet 24 having a nozzle 26 at its end to achieve high inlet velocities into the mixing region, a nozzle type inlet is not required. Alternatively, the carbonaceous material and its carrier gas can be supplied at a sufficient velocity to the inlet 24 so that the resultant mixture is under turbulent flow wit,hout need for a nozzle.
The hot particulate solid source of heat is supplied at a rate and a temperature consonant with maintaining a temperature in the pyrolysis zone suitable for pyrolysis.
Pyrolysis initiates at about 600 F, (315 C.) and may be carried out at temperatures above 2000 F. (1100 C.).
Preferably, however, pyrolys;s is conducted at a temperature ranging from about 900 F. (480 C.) to about 1400 F. (760 C.) to maximize the yield of middle boiling point hydrocarbons.
Higher temperatures, by contrast, enhance gasification reactions.
The maximum temperature in the pyrolysis reactor is limited by tl~e temperature at which the inorganic portion of the particulate source of heat or carbonaceous material soft,ens wi.th resultan-t fusi.. on or slag formation.
Dependlng upon pyrolysis temperature, tl~e we:igrht rat:io of - particulate solid source of heat to carbGnaceous rnaterial ;.s preferably in the range 2 to 20 at the entry to the reactor.
At these ratios w;thin this range, the particu3ate source of heat is introducecl to the reactor at a tenlperal,ure from about 100 to about ~00 F. (~5 - 2~0 f',) above tl2e d^s:;red pyrolys:is tel~perat,ure .
For economy the amount of fluidizing ~ras injecl;ed tJll`Oll~
inlet li2 into the flll;.di.zi.n~ chaml)er i.s mail~ta:i~ic?d at as 3.o~
a 3evel as poss~ Le sul)ject to t,he co~isl.:ra:iJ-It, i;]l~lt, l;he _ ~9 _ ~ ~ ~ 3L~ ~
particulate source of lleat be maintained in a fluidized state.- Preferably at least a portion of the fluidizing gas is ad,mitted into the mixing section of the reactor to prevent eddy formations with r~sultant back-mixing of partly spent particulate source of heat. The quantity of carrier gas injected with the sol,id carbonaceous material is that which maintains turbulent flow during the progress of the solid carbonaceous material througll the plastic state in the case of an agglomerative coal. Sufficient carrier gas must be injected to preven-t undesirable pressure fluctuations due to flow instabilities. The amount of gas employed to transport the solid car~onaceous material is sufficient to avoid plugging in the reactor, and normally in excess of that amount to dilute the ~solid materials anl prevent self-agglomeration in the case o~ an agg],omerative coal.
Generally high solids content in the pyrolysis feed strearn is desired to minimize equipment size and cost.
However, preferably the resultant turbu],ellt mi~ture contains su~ficient carrier gas for the mixture to have a solids content
There are many problems associated with this use of a pyrolysis reactor and a combustion chamber in co~nl~ination for obtaining hydrocarbons from soli,d carbonaceous materials. One of these problems i,s caking of coal along the walls of the pyro],ysis reactor when the carbonaceous material is an aggrlomerative coal, parti,cularly an Eastern Un;ted States coal, which expe-rience shows to have a tendency to ag~omerate in a reactor, especial]y along the walls oI' the reactor.
Anotller probleln concerns trar-sfe~cring the particulate carbon-containing solid product from the pyrolysis reactor to the combus-tion chamber while at the same time preveilting oxygen that is present i,n the combustion cllalnber from enterillg the r~yrolysis reactor. If oxy~elllnanages to leak i,ntc~ the pyrolysis reacl,or, the value of tl3e hydrocarl~oll procluct is reduced anc,ll;~ol-(?over, a ~iolent e~l)losion may occ,uv~.
A, th-ird prol>lem concc-~rns the rleed to 113'-~ ni~e product,i,on ~ ca-~boll dil-xic~ln and min:i,ln:ize prcd-~ct,i,on o,f o<irbon ~031C-~'i c,~e - 30 i,n -tlle com'bus1;io~1 ~03ie i~ order -to nn'l~:i.mi7,(' l'C.`COVC`ry of l:]le ,~ _ ~k~
1113~14 heating value of the carbon-containing solid residue during oxidation. The kinetics and thermodynamic equilibria of the oxidation of carbon favour increased production of carbon monoxide relative to carbon dioxide at temperatures greater than about 1200F. (650C.) at long residence times when there is a stoichiometric deficiency of oxygen. Because pyrolysis of carbonaceous materials often is conducted at temperatures greater than 1200F. (650C.) and can approach temperatures higher than 2000F. (1100C.), it is necessary to form a particulate source of heat having temperatures greater and often considerably greater than 12000F. (650C.). Moreover, the particulate carbon-containing solid residue is only partly oxidized in a stoichio-metric deficiency of oxygen to form the particulate source of heat. Thus production of carbon monoxide inevitably occurs during the oxidation of the particulate carbon-containing solid residue. The carbon monoxide formed represents a loss of thermal efficiency of the process.
Therefore, there is a need for a process and an apparatus for obtaining values from a solid carbonaceous material by pyrolysis which are sueful for agglomerative coals; which, when a particulate carbon-containing solid residue of pyrolysis of the carbonaceous material is oxidized to form a particulate source of heat to pyrolyze the carbonaceous material, prevent oxygen from entering into the pyrolysis reaction; and which maximize pro-duction of carbon dioxide while minimizing production of carbon monoxide.
The present invention therefore provides a method in which the fluidized bed is fluidized by a fluidizing gas contain-ng oxygen.
Preferably there is provided a continuous process for pyrolysis of particulate solid carbonaceous materials which ?
4~
comprises, in combination, the steps of:
a) subjecting a particulate solid carbonaceous material to flash pyrolysis by continuously:
(i) transporting the particulate solid carbonaceous material contained in a carrier gas which is substantially nondeleteriously reactive with respect to products of pyrolysis of the particulate solid carbonaceous material to a substantially vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature below about 2000F;
(ii) feeding a particulate source of heat at a te~perature above the pyrolysis temperature and comprising heated particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iii) forming a turbulent mixture of the particulate source of heat, particulate solid carbonaceous material and carrier gas to pyrolyze the particulate solid carbonaceous material and yield a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
b) passing the pyrolysis product stream from the pyrolysis reactor to a first separation zone and separating at least the bulk of the solids from the vapor mixture; and c) forming the par~iculate source of heat by:
(i) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material and separated from the vapour mixture to a fluidized be~ around a substantially vertically oriented - 3a -~3~
open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combust-ion zone;
(ii) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by inject-ing a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the particulate carbon containing solid residue thereby heating the particulate carbon containing solid residue and to transport particulate carbon containing solid residue and gaSeQus combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone;
(iii) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones in combination being sufficient to generate the particulate source of heat; and (iv) passing the formed particulate source of heat and the gaseous combuation products from the second combustion zone to a second separation zone and separating the particulate source of heat from the gaseous combuation products of the particulate carbon containing solid residue and feeding the thusly separated particulate source of heat to the pyrolysis reactor.
Preferably the invention provides a process for pyrolysis of solid carbonaceous materials by heat transferred thereto by a particulate source of heat to yield a particulate - 3b -~13~
carbon~colltaining solid residue as a product of pyrolysis, t;he particulate source of heat being formed by oxidizing at least a portion of the particulate carbon-containing solid residue, characterised by transporting at least a portion of the particulate carbon-containing solid residue formed by pyrolysis of the solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zons;
educting sol.id residue from the fluidized bed into the first combustion zone by illjecting a gaseous source of oxygen upwardly i.nto the conduit to oxidize carbon in the solid residue for partly lleating the solid re-idue and to transport solid residue and gaseous com~ustion products of the solid residue, including carbon monoxide, to a second combustion zone; and introdllcing a source of oxygen into the second combustion zone in an amount at least equal to 50% of tho molar feed of carbon monoxide to the second combustion zone, t.he total oxygen ~eed to the :first and second combustion zones being sufficient to generate the particulate source of heat.
Prefera.bly the said conduit is spaced ~part from said riser al~d the particulate carbon~conta.ining solid res.idue is ~luidized : in the l`luidized bed by an upward flcw of a fluidlzing gas that passes into the riser through the space between t;he riser and tile COlldlli t . The ilui.dizing gas desirably contains oxy~en.
In prel`er3ed embodiments of the inventi.oll the pyrolysis process is a so~c~li.ed flasll pyrolysi.s st;ep, performed by cont;inuously tra]~sporti.ng pa:rt:iculate solid carbo1laceouc mater~
fee~ contaill.ed in a c.lrrieJ ~ras whi.ch ;s subst;al-l-li.ally 1~13414 nondeleteriously reactive with respect to products of pyrolysis to a vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at ; a temperature below about 2000 F. ( 1100 C. ); feeding the particulate source of heat at a temperature above the pyrolysis temperature to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature; forming a turbulent mixture of the particulate `
source of heat, particulate solid carbonaceous material feed and the carrier gas to pyrolyze the solid carbonaceous material feed and yield a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon-containing solid residue of pyrolysis, and a vapor mixture of carrier gas .
; and pyrolytic vapors comprising hydrocarbons; and passing the ;; pyrolysis product stream from the pyrolysis reactor to a first separation zone to separate at least the bulk of the solids from -the vapor mixture.
The first separation zone may be a cyclone separation zone.
; The formed particulate source of heat may be separated from the gaseous combustion products of the second combustion zone in a(secon~ cyclone separation zone. Alternatively, the second combustion zone may comprise a cyclone oxidation-separation zone.
The process is preferably performed with the use of a pyrolysis reactor ha~ing a solids feed inlet for the solid carbonaceous material feed and a vertically oriented chamber surrounding the upper portion of the pyrolysis reactor, the inner peripheral wall of said chamber forming ar overflow weir to a vertically oriented mixing zone of the reactor, the particulate solid carbonaceous material being transported ~134~4 in a carrier gas to the solids feed inlet and thence being injected into the mixing zone, the particulate source of heat being fed to the said vertically oriented chamber and being fluidized in such chamber by a flow of a fluidizing gas substantially nondeleteriously reactive with respect to the products of pyrolysis, the fluidized particulate source of heat discharging over said weir and downwardly into said mixing zone to form a turbulent mixture with the particulate solid carbon-aceous material, said mixture passing downwardly from the mixing zone to the pyrolysis zone of the pyrolysis reactor to pyrolyze the solid carbonaceous material.
The invention also provides an apparatus in which the combustion chamber is a cyclone for separating formed particulate source of heat from such formed combustion gas.
Such apparatus is particularly useful for combination with a pyrolysis reactor utilising a particulate solid source of heat. Accordingly, in another aspect the invention provides an apparatus for pyrolysis of solid carbonaceous ,~
~f j 1~13~4 materials~ comprising a descending flow pyrolysis reactor;
means for forming a turbulent mixture of a particulate source of heat and a solid carbonaceous material contained in a carrier gas for introduction into the pyrolysis reactor to pyroiyze the solid carbonaceous feed to form a pyrolysis product stream containing a vapor mixture and, as solids, the particulate source of heat and a particulate carbon-containin~ solid residue of pyrolysis; a first separator for separating at least th~ bulk of the solids from the vapor mixture in the pyrolysis product stream; means for transferring the pyrolysis product stream to the first separator fro~ the pyrolysis reactor; means . .
for f~ming the particulate source of heat, comprising a vessel containing a fluidized bed of the separated solids around an open, substantially vertically oriented conduit, a substantially vertically oriented riser in open communication . with the conduit, a combustion chamber in communication with the riser, means for introducing a gaseous source of oxygen upwardly into the conduit to educt solids from the fluidized bed into the conduit, and means for introducing oxygen into the combustion chamber to heat the solids to form the particulate source of heat, means for passing the separated solids from the first separator to the fluidized bed; means for transferring the particulate source of heat from the second combustion chamber to the second separator; a second separator for separating the particulate source of heat from the gaseous combustion ~: product; and means for transferring the separated particulate source of heat from the second separator to the pyrolysis reactor, ' ~referably the said conduit is spaced apart from said riscr The first and second separators may con~eniently both be 1~ r;~L~1!4 cyclone separators although in a modified arrangement the second combustion cha3nber and the second separator are integrated and constituted by a cyclone oxidation-separation device.
In a preferred embodi~ent of the apparatus, the pyrolysis reactor contains a substantially vertically oriented mixing section and a su~stal3tially ~ertically oriented pyrolysis section, and has a solids feed inlet, a substanti.ally vertically or;ented ch~nber surrounding the upper portion of the reactor and ha~ing an inner peripheral wall that forms an overflow weir to the vertically ori.ented mixing section, - and the means for forming a turbu.lent mixture comprises means for feeding par':iculate source o~ heat to t;he vertically oriented chamber; means for introducing a fluidizing gas into the cha1nber to maintain the particul.ate source of heat therein in a fluidized state; and means for injectil~g the solid carbonaceous feed contained in the ca.rrier gas from tthe solids feed inlet into the mixi.ng section to form tlle resultant turbulellt mixture.
Irl anotller aspect the invention provides an apparatus for pyrol.ysis of agglomerati~re coals, comprising a descelldillg flow pyrolysis reactor con1aining a substan~:ially vertically orienled n~i~cingr section, a su1~stanttially vertically or.iented pyrolysi.s section, a solids feed :in1.et, a1-lcl a su1~t;a1lt:ially erticall.~ oriented cham1~er surrounding t}~c~ up~er por1;;on of the reac-tor, t;he im-er pe1-i.pheral ~Tall of t1~e cl1an31~er formi1~r an o~er~lo~r1~re:i.r to the mi.~i.ng section, ~lle:ce-in an ag~lo1~3erati~-r coal feed containecl in. a ca-rri.er gas is combillec~ a partici~l.c~..t;e SOUl~C.? of heat IllldCr l-Urb~lCllt f1O~r condii;ic-ns :in tlle pyrolysis sect:i.on Or t:he p!T olysis ro<lc-t~ co yiel.d a pyrolysis product stream containing as solids the particulate source of heat and a particulate carbon containing solid residue of pyrolysis, and a ~apor mixture; means for feeding the particulate source of heat to the vertically oriented chamber; means for introducing a fluidizing gas into the chamber to maintain the particulate source of heat therein in a fluidized state; means for passing a coal feed from the solids feed inlet into the mixing section; a first cyclone separator in con~nunication with the pyrolysis reactor for separating at least the bulk of the solids in the pyrolysis product stream from the vapor mixture in the pyrolysis product stream; means for forming the particulate source of heat, comprising a vessel containing a fluidized bed of the separat~l solids arour~d an open, substantially vertically oriented conduit, a substantially vertically oriented riser in open communication with the vertically oriented conduit and separated therefrom, a second combustion chamber in communication with the riser, means for introducing a gaseous source of oxygen upwardly into the conduit to educt solids from the fluidized bed into the conduit and to partially oxidize carbon in the solids to heat the solids with attendant formation of combustion products, means for introducing o~gen into the second combustion ch~nber to further heat the solids to form the particulatc source of heat; a dipleg I`rom the first cyclorle separator to the fluidized bed for transferring the scparated soli~s from the first cyclone separator to the fluidized bed, a second cyclone separator in communica-tlon with the coml~usiion cham~Gr for separatirlg tl~e particulate source of heat from tl~e ~cr~seous com~ustion products, and a d:;ple~r from t~le second cyclone separator to the cllamber surrounding l}le uI)per po:rt;oll of the pyrol-ysis reaG-toJ J`or transferring t}le p.lrt3.cuL~te source of ~ g _ 4~
heat to the pyrolyæis reactor. ~:
Further preferable features of the process of the invention and of the apparatus thereof will be discussed and described in the following, with reference to the accompanying drawings in which:
~ IGURE 1 illustrates . diagrammatically a process and an apparatus embodying features of this invention; and .-FIGURE 2 is an enlarged and more detailed view of the region marked 2 in ~igure 1.
The drawings illustrate a pyrolysis unit 8 comprising a descending flow pyrolysis reactor 10 which has a substantially vertically oriented mixing sectiosl or zone 12 and a substantially vertically oriented pyrolysis section or zone 14 below the mixing section. Arrow 1~ shows the approximate extent of the pyrolysis section. The reactor has an elbow ~, 18 towards the end of the pyroly~is section, by which it can be supported. The lower end 20 of the reactor termînates in . a separation zonè such as first cyclone separator 22.
A generally upright annular solids feed inlet 24 `t 20 terminating within the mixing section 12 and constricted at its end to form a nozzle 26 is provided for introducing a so1id carbonaceous materi.al into the mixing region.
-The upper end 28 of the reactor is open and of larger diameter than the nozzle 26, thereby leaving an annular gap 30 between the upper end 28 of the reactor and the nozzle 26.
A vertically oriented fluidising chamber or well 32 surrounds the upper portion of the reactor and is formed by a preferably annular section 3~ which connects the wall 36 of the solids feed : inlet above wllere the wall constricts to for.m the nozzle 26 and the upper portion 2~ of the reactor, The chamber 32 ~3~13~4 surrounds the nozzle 26 and a portion of the upper wall 28 of the reactor. The inner peripheral wall of the chamber 32 is formed by thè upper wall 28 of the reactor and serves as an over~low weir to the mixing section 12 of the reactor 10.
A second vertically oriented solids inlet 38 terminates in the annulàr fluidizing chamber 32, prefe~ably at a level below the top edge 40 of the pyrolysis reactor 10, There is a gas inlet 42 to the bottom of the fluidizing chamber for a fluidizing gas. Means are provided such as a cylindrical, horizontally oriented, perforated plate 44 positioned towards the oottom of the fluidizing chamber below the end of the second inlet for distributing the fluidizing gas so that the fluidizing gas flows u]~wardly through the fluidizing chamber.
The first cyclone separator 22 serves to separate a particulate carbon-containing solid residue of pyrolysis from the gaseous products of pyrolysis.
The particulate source of heat for the pyrolysis reactor is forméd by oxidizing at least a portion of the particulate carbon-containi.ng solid re~idue in a combustion unit 50.
The combustion unit includes a vessel 52 containing a fluidized bed 60 of a particulate carbon-conta.ining solid residue around an open, substantially vertica]ly oriented conduit or tube 54. There i.s a gas inlet 56 for a transport gas at the base of the vessei 52 w13ich narrows down to form a vertical]y oriented nozz.le 5~ for inJection of the tran~port gas directly upwardly into the open conduit 5~1. The ~luidized bed 60 of carbon-containing solid residue is fluidized by a fluidi7ing gas entering the cbalnber througll a gas i.nlet 62 at ~ ~3~
the base of the vessel. The fluiclizing gas is distributed throughout the fluidized bed by means of a second, horizontally oriented perforated distributor plate 64.
The top 66 of the vessel 52 tapers upwardly and i-.-wardly to connect to a vertically oriented riser 68. The riser and conduit comprise a first combustion zone or chamber. The riser couples the vessel 52 to a second combustion zone or chamber 70.
The conduit 54 is below the riser 68 and tlle top edge 72 of the conduit is spaced apart from the riser so that an annular gap of space 74 is formed between the inlet 76 to the riser and the top edge 72 of the conduit. The top portion 71 of the conduit can be tapered inwardly so that the diameter of the conduit at its top edge is smaller than the diameter of the riser.
A vertically oriented standpipe or dipleg 78 having stripping gas inlets 122 extends from the bottom of the first cyclone separator 22 into the ves.sel 52 below the top 80 of the flu;dized bed of carbon-containillg solid residue. Solids separated by the first cyclone separator are transferred througll this dipleg into the vessel.
There is an inlet 82 at the upper portion of the riser 68 for introduction of a source of oxygell into the second comb-lstion chamber 70. The second combustion chamber is in open comm~lication with a second separa1;or such as cyclone separator 84. This separator serves to separate a particulate source of heat generated in the combus-tion unit 50 from any combustion gases present in the com~ustion unit. The particulate source o~ heat is transferred from the second cyclone separa-tor 8ll to 1;1~e second inlet 38 of the pyrolysi,s reactor throu~ll a vertica,,ly or:ienl;ed d;pleg or stancdp;pe 86 1~i3L?~'~4 originating at the bottom o~ the second cyclone separator 84 and terminating in the second inlet 38. The length of the -standpipe 86 is chosen to balance the accumulation of differential pressures throughout the remainder of -the system. Inlets 88 for a stripping gas are provided along the length of the standpipe 86.
In summary, what has' been described is an apparatus for pyrolysis of a ~solid carbonaceous material comprising two ntain units, a pyrolysis unit 8 and a combustion unit 50.
These t~o units are coupled by two cyclone separators 22, 84 and two vertically oriented stanclpipes or risers 78, 86 which allow car~on-containing solid residue to be transferred from the pyrolysis unit to the combustion unit and particulate source of heat to be transferred from the combustion unit to the pyrolysis unit, respectively.
In the proc~ss of this invention, a particulate solid carbonaceous ~1aterial is subjected to flasll pyrolysis by transporting the particulate solid carbonaceous material feed containcd in a carrier gas through. the first feed i.nlet 24- to the feed no~le 26 and thus to the pyrolysi.s reactor 10.
The carri.er ~as is substantially nonde]eteriously reacti~e Wit~l respect to the products of pyr.olysis and may sc~rve as a diluen-t to pre~ent se].f-agg]o~neration of the carbonaceous ma-tericLl.
.As used hAl~ein, by a "nondeleteriously reacti.ve" gas there is l~eallt a ~IS StreaT,Il WhiCh iS SUbStant~ 11Y free 0f free OXYgel1. A1 l;hOUgh the gas ~nay con.-tain con.stituc~llts 1,llLt reac-t uncler nonox.idizing conditions w-itll pyrolysis ~)rod~cts to upgrade -thei.r ~T.-Llue, the gas sl-ould no'c conta;n cons-tit,uents that dcgrade pyroly.5:i.s proc]ucts. T]le carri.or 3o gas may, ~or ~ st,al~ccT be -t.]le O:)~ -L.S prCldliCt O:l~ pyrolys ~3414 ste~2 which will react under suitable conditions with char or coke formed from pyrolysis to yield, by water-gas shift reactions, hydrogen that serves to react with and stabilize unsaturates in the products of pyrolysis; any desired inert gas;
or mixtures thereof. The carrier gas can, for instance, be synthesis gas, especially a hyTdrogen-enriched synthesis gas.
The carbollaceous material may be treated before it is fed to the first fluidized bed by processes such as removal of inorganic fractions by magnetic sepàration and classification, particularly in the case of municipal solid waste. The carbonaceous material also can be dried to reduce its moisture content. The solid carbonaceous material is usually comminuted to increase th<: surface area avai]able for pyrolysis.
Preferably a substantial portion of the carbonaceous material is o~ a particule size of less than about 1000 microns to pre~sent a large surface-to-volume ratio to obtain rapid heating of the coal in the pyrolysis zone. Rapid heating results in improved yields of hydrocarbons. For an agglomerative coal, the partlcle size is preferably mainly less than a~out 250 microns because aggLomerative coals are well -known to plasticize and agglutinate at relatively low temperatures i.e., 400 to 850 F. (200 - 450 C.). An agglomerative coal should -therefore be rapidly hcated through the plastic state be~ore it strikes the wall of a pyrolysis reactor to prevent caking on the reactor waLl.s. Because thc rate at ~Thich a coal particle can be lleated increases as particle size decreases, it is important that an agglomerative coal bc comminuted to 250 ~licrons or less, depending 031 the si~e and conriguration of the pyrolys;s re~cl->r, so that substantia31y all the coal particle3 have l~assccl thro~g}l t~le ~i3'~:~4 plastic state and have become non-tacky by the time the coal particles stri~e a reactor wall, ~or example, when a bituminous high-~ol.atile C coal which agglomerates at temper~tures above 500 F. (260 C.) is pyrolyzed at a temperature of 1075 F. (580 C.) in a 10 inch (250 mm) diameter pyrolysis reactor of the design shown in Figure 1 and described below, the coal should be comminuted to a size less than 250 mi.crons in diameter to prevent caking on the reactor walls, Coal parti.cles larger than 250 microns in diameter could strike the reactor walls before passing through the plastic state.
The carbonaceous material introduced into the pyrolysis ,' reactor is preferably substantially free of fines less tllan about, 10 microns in di.ameter, because carbon-containing solid residue fincs 3~esu~.-ting from pyrolysis of the carbonaceous material have a tendency to be carried into and contaminate the liquid hydrocarbon. products.
Simu].taneously with the introduction of the carbonaceous materi.al ~eed, there is introduced. a particulate source of`
heat i,nto the fluid;zing cha1nber 32 through the second vertically oriented inlet 38. Because in tll-_ preferred embodiment the second inlet 38 terminates bel-)w the top edge 40 of the pyrolys:is reactor 10, incom;l-lg "art:ic~llatc? source of heat bui.lds up in the fluidizing chaniber be3o~J the weir 28 to form a solids seal. The particula.te source of lleat in chamber 32 is mainta.ined in a fluidized st~te in the chamber ~y introduction O:r a flu,idiz:ing gas st:ream -tllrc)~ l? tlle gas .inlet;
42~ The f`lu:i,di~ing gas is distributed b~r the d--stributor plate 411 tC? maintai.n the particulat-e SOUl'Ce Or )leat in a -fluidiz(?cl st~l1;e throughout l;h-' cl?amber. ~s addi t.. ,?nal I?arl~i CUlat;r? source of heat is ini;~oAllced :illt~? tlle cl~ambe:r t~ .ll`tiCUlatC SOllrCC
of heat passes over the upper end 40 of the weir and through the opening 30 between the weir and the nozzle 26, into the mixing section 12 of the pyrolysis reactor 10 with aid of fluidizing gas. An advantage of this weir-like configuration is that substantially steady flow of fluidi~ed particulate source of heat enters the mixing section because the mass of the particulate source of heat backed up behind the weir of the reactor damps minor fluctuations in the flow of the particulate source of heat.
In the mixing zone of the pyrolysis reactor, the carbonaceous material conta.ined in th~ carrier gas-is discharged from the nozz]~ as a fluid jet 112 expanding towards the reactor wall at an angle of about 20 or less as shown by dotted lines 88 ~hich represent ths periphery of the fluid jet. Once the particulate source of heat is inside the mixing section, it falls into the path of the fluid jet 112 of the carbonaceous material feed stream and carrier gas coming from the nozzle and is entrained thereby, yiel.ding a resultant turbulent mixture of the particulate source of heat, particulate solid carbonaceous materia] feed, and the carrier gas, The jet has a frce core region 113 of carbonaceous material, as delineated by the V~sha.ped dotted line 114s extending considerably into the reactor, but as tlle jet expands, the particula.te source of lleat present is entrained 1~ith mixing of the carbonaceous material in -th.e pOl-tiOn of thc flui~ jet 112 arou.nd the free core re~i.on 113, The par-ticulate source of heat along the ~eri.p~-Zery 88 of the f1a~:id 3et prefera~ly he&ts the carbonaceous materi.al in the ca.se of an ag~lomeralive coal to a temperature al~ove~ tho temperat;ure at whic}- t]!e coal J S tacky. In tlle re~ion 116 ~et~een t~l react.o3 walls and 3~4 the fluid jet 112, there is unentrained particulate source of heat.
This mixing of the particulate source of heat with the solid carbonaceous material in the mixing zone 12 initiates heat transfer from the particulate solid source of heat to the carbonaceous material, causing pyrolysis in the pyrolysis sect;ion 14 of the pyrolysis reactor 10. Pyrolysis is a combination of vaporization and cracking reactions. As the vaporlzation and cracking ractions occur, condensible and noncondensible hydrocarbons are generated from the carbonaceolls material with an attenc~ant production of a carbon-containing solid residue such as coke or char. An effective pyrolysis time i 9 le.ss tllan about 5 seconds, and -treferably from about 0.1 to about 3 seconds, to maximize yield of middle distillates, Middle distillates are the middle boiling hydrocarbons, i.e., C5 hydrocarbons to hydrocarbons having a boiling end point of about 950 ~. (510 C-)- These hydrocarbons are useful for the production of gasoline, diese]. fuel, heating fuel., and the li~e.
As used herei.n, "pyrolysis timc" mealls the time from when th.e carbonaceous material con-tacts the ~arti.cu]ate source of` heat until the pyrolytic vapors produced by pyrolysi.s are separated from the particulate source of lleat in the first sepa.ration zone 22, as described below.
A convellient measure of pyrolysis ti.me ;s the average residence tir~e of the carrier ~a3 in the p~rolysis section 14 of tlle pyrolysis reactor ancl. the first scp<trator 2~.
Snflicient pyrolysis time must ~e pro~ri~ed to heat tlle carbon~cec-us rrlater;.al to the pyrolysis tcl.;peratll:re.
All advanta~;c-~ of t;he pyro:lysis react~ S~10~!11. -in the clrawinp~s is tlla-t thc turbul.ent flow c<-uses -tll( s~.l.id - ~-7 -1~3'};~4 carbonaceous material feed to be heated rapidly, which improves yields, In the case of agglomerative coals, buildups of coal particles on the reactor walls are prevented by the rapid heating and turbulent flow. Preferably the particulate source of heat enters the mixing section 12 at a rate of flow less than turbulent and the solid carbonaceous material enters the mixing section through the nozzle under the turbulent flow conditions at a rate sufficiently high for the resultant mixed stream from these two inlet streams to be turbulent.
Turbulent flow results in intimate contact be-tweerl the solid carbonaceous material and the particulate source of heat particles, thereby yieldin~ rapid heating of the carbonaceous material. In the case of an agglomerative coal, the turbulence results in mixing o~ the particulate source of heat with the coal particles in the inner portion of the fluid jet, thereby quickl3r heating these coal particles through the tacky/plastic state. As used herein, "turbulent" means that the stream ~7s a Reynolds flow index Number greater than 2000 as calculated by the velocity of the carrier gas at operating conditions. Laminar flow in the pyrolysis reactor tends to severely limit the rate of heat transrer within the pyrolysis zone. Process parameters such as the noz~le diameter ancl mass flow ratc o~ the carbonaceous material and its carrier gas are varied to maintain the flow rate of the particulate stream entering the ~irst inlet in tlie turbulent region.
The end o~ the sc,lids feecl inle-t is pref`era7,1y cooled, e.g. I~y water when pyrolyzing an agglomerati~re c~al because othel^wise ths lnlet might be heated abo~c tlle point at which the coRl becomcs tacliy, by hea-t transfer f`lom t]le ~articulate source o~ heat s~urroundirlg the end of t}l~ solid~, feed inlet.
l8 -9.3~i~i4:~
Although the drawings show a solids feed inlet 24 having a nozzle 26 at its end to achieve high inlet velocities into the mixing region, a nozzle type inlet is not required. Alternatively, the carbonaceous material and its carrier gas can be supplied at a sufficient velocity to the inlet 24 so that the resultant mixture is under turbulent flow wit,hout need for a nozzle.
The hot particulate solid source of heat is supplied at a rate and a temperature consonant with maintaining a temperature in the pyrolysis zone suitable for pyrolysis.
Pyrolysis initiates at about 600 F, (315 C.) and may be carried out at temperatures above 2000 F. (1100 C.).
Preferably, however, pyrolys;s is conducted at a temperature ranging from about 900 F. (480 C.) to about 1400 F. (760 C.) to maximize the yield of middle boiling point hydrocarbons.
Higher temperatures, by contrast, enhance gasification reactions.
The maximum temperature in the pyrolysis reactor is limited by tl~e temperature at which the inorganic portion of the particulate source of heat or carbonaceous material soft,ens wi.th resultan-t fusi.. on or slag formation.
Dependlng upon pyrolysis temperature, tl~e we:igrht rat:io of - particulate solid source of heat to carbGnaceous rnaterial ;.s preferably in the range 2 to 20 at the entry to the reactor.
At these ratios w;thin this range, the particu3ate source of heat is introducecl to the reactor at a tenlperal,ure from about 100 to about ~00 F. (~5 - 2~0 f',) above tl2e d^s:;red pyrolys:is tel~perat,ure .
For economy the amount of fluidizing ~ras injecl;ed tJll`Oll~
inlet li2 into the flll;.di.zi.n~ chaml)er i.s mail~ta:i~ic?d at as 3.o~
a 3evel as poss~ Le sul)ject to t,he co~isl.:ra:iJ-It, i;]l~lt, l;he _ ~9 _ ~ ~ ~ 3L~ ~
particulate source of lleat be maintained in a fluidized state.- Preferably at least a portion of the fluidizing gas is ad,mitted into the mixing section of the reactor to prevent eddy formations with r~sultant back-mixing of partly spent particulate source of heat. The quantity of carrier gas injected with the sol,id carbonaceous material is that which maintains turbulent flow during the progress of the solid carbonaceous material througll the plastic state in the case of an agglomerative coal. Sufficient carrier gas must be injected to preven-t undesirable pressure fluctuations due to flow instabilities. The amount of gas employed to transport the solid car~onaceous material is sufficient to avoid plugging in the reactor, and normally in excess of that amount to dilute the ~solid materials anl prevent self-agglomeration in the case o~ an agg],omerative coal.
Generally high solids content in the pyrolysis feed strearn is desired to minimize equipment size and cost.
However, preferably the resultant turbu],ellt mi~ture contains su~ficient carrier gas for the mixture to have a solids content
2~ ranging from about; 0.1 to about 10~ by volume based on the total vo]ume of t;he stream, to provide turbulence for rapid heating of the carbvnaceous material and to ditute the carbonaceous material and help prevent self-agglomeration, particularly ~hen processing an agglomerat;~e coal. napid heating res-ults in high yields and pre~eIlts agglutinat,ion o~ agglomerative coals.
~lle si~e ~r.vt con~igurativn of tl~e pyrolysis reactor is chosen to main~ain the desired residellce t;in}lc ror the pyrolysis reaction. Generally, as the pyrol~sis t,e~ erclt;ure is reduccd, longc-~r residence t;imes are used -to ma:i}lt-c~in -tll-- desirecl y-ie]d L~
of volatilized hydrocarbons.
~or economy, the pressure in the pyrolysis reactor is typically greater than atmospheric to compress the vapors formed during pyrolysis so that low volume separation equipment downstream of the reactor can be used.
A pyrolysis product stream is passed f'rom the end 20 of` the pyrolysis reactor 10 to the first cyclone separator 22. The pyrolysis product stream contains as solids, the particulate source o~ heat and the particulate carbon-containing solid residue of pyrolysis, and a vapor mixture of carrier gas and pyrolytic vapors comprising noncondensible hydrocarbons and eondensible hydrocarbons. Preferably the first cyclone separator is in open communication with vhe lower end 20 of the pyrolysis reactor so that a quick separation of the vapors from the solids can be ef`fected to mini.~ize pyrolysis time and so that the vapors can be quenched to prevent cracking reactions f`rom occuring which tend to decrease the recovery of middle distillates from the pyrolytic vapor. In tlle cyclone separator 22 at least the bulk of the solids are separated from the vapor mixture. The va.por mixture contains pyrolytic vapors containing volati.lized hyclroca.rbons~ inert carrier gases, and nonhydrocarborl components such as hydrogen sulf`i,de which ]rlay be generated in the pyrolysis reaction.
r~he vol~tiL;.zed h~idrocarbons prod~ced by pyrolysi.s consist Or condensible hydrocarbon~s wh:ich Illcly ~e recoveled l~y contacting the vol~t;,lized llydrocarbons sucll as met~lanc and other hydrocarboJl gases which are not reco-c,eral:)ly by or~ ~ r co~ldens~tjG~l meansO Conc~ c;ib~e l~y-<~ o(~al~bons C~til ~e separat,ecl and reco~rered by COllV-?~lt:i Ol1al Ill<`~llS SUC11 aS ~c`lit~lr:i scrubbers, indirect heat exchangers, wash towers, and the like.
~he undesirable gaseous products can be removed from the uncondensible hydrocarbons by means such as chemical scrub~ing. Remaining uncondensed hydrocarbons can be sold as a product gas stream and can be utilized as the carrier gas for carrying the carbonaceous material to the pyrolysis reaction zone.
The particulate source of heat is formed in the combustion unit 50. The solids separated in the first cyclone separator 22 are passed down through the dipleg 78 into the fluidized bed 60 contai}ling spent particula1;e source of heat and the carbon-containing solid residue of pyro3ysis. As the solids drop down through the dipleg, hydrocarbons on the surface of the solids are stripped by an upward ~low of stripping gas, nondclcteriously reacti~e with respect to pyrolysis products, such as steam. The stripping gas is introduced through gas inlets 120 on the side of the dipleg. The bed 60 is maintained in a fluidized state by an upward flow of fluidizing gas stream 91 into the Yessel 52 through the gas inlet 62 and distributed by the distributor plate 64. The fluidizing gas can be nonreactive with respect to the solids in the fluidized bed, being for instance the off gas product of pyrolysis, or the gas may contain a portion of the oxygen required for oxidizing the solids to form the particulate source of ~eat.
A transport gas is introduced upwardly through the gas inlet 56 and nozzle 58 into the riser 54. The transport gas preferably conta;lls free oxygen. Other reactan1,s which lea~
to the formation of carboll monoxide may be ~-resent~ These include ste.~ and carbon dioxide, When steam is present,
~lle si~e ~r.vt con~igurativn of tl~e pyrolysis reactor is chosen to main~ain the desired residellce t;in}lc ror the pyrolysis reaction. Generally, as the pyrol~sis t,e~ erclt;ure is reduccd, longc-~r residence t;imes are used -to ma:i}lt-c~in -tll-- desirecl y-ie]d L~
of volatilized hydrocarbons.
~or economy, the pressure in the pyrolysis reactor is typically greater than atmospheric to compress the vapors formed during pyrolysis so that low volume separation equipment downstream of the reactor can be used.
A pyrolysis product stream is passed f'rom the end 20 of` the pyrolysis reactor 10 to the first cyclone separator 22. The pyrolysis product stream contains as solids, the particulate source o~ heat and the particulate carbon-containing solid residue of pyrolysis, and a vapor mixture of carrier gas and pyrolytic vapors comprising noncondensible hydrocarbons and eondensible hydrocarbons. Preferably the first cyclone separator is in open communication with vhe lower end 20 of the pyrolysis reactor so that a quick separation of the vapors from the solids can be ef`fected to mini.~ize pyrolysis time and so that the vapors can be quenched to prevent cracking reactions f`rom occuring which tend to decrease the recovery of middle distillates from the pyrolytic vapor. In tlle cyclone separator 22 at least the bulk of the solids are separated from the vapor mixture. The va.por mixture contains pyrolytic vapors containing volati.lized hyclroca.rbons~ inert carrier gases, and nonhydrocarborl components such as hydrogen sulf`i,de which ]rlay be generated in the pyrolysis reaction.
r~he vol~tiL;.zed h~idrocarbons prod~ced by pyrolysi.s consist Or condensible hydrocarbon~s wh:ich Illcly ~e recoveled l~y contacting the vol~t;,lized llydrocarbons sucll as met~lanc and other hydrocarboJl gases which are not reco-c,eral:)ly by or~ ~ r co~ldens~tjG~l meansO Conc~ c;ib~e l~y-<~ o(~al~bons C~til ~e separat,ecl and reco~rered by COllV-?~lt:i Ol1al Ill<`~llS SUC11 aS ~c`lit~lr:i scrubbers, indirect heat exchangers, wash towers, and the like.
~he undesirable gaseous products can be removed from the uncondensible hydrocarbons by means such as chemical scrub~ing. Remaining uncondensed hydrocarbons can be sold as a product gas stream and can be utilized as the carrier gas for carrying the carbonaceous material to the pyrolysis reaction zone.
The particulate source of heat is formed in the combustion unit 50. The solids separated in the first cyclone separator 22 are passed down through the dipleg 78 into the fluidized bed 60 contai}ling spent particula1;e source of heat and the carbon-containing solid residue of pyro3ysis. As the solids drop down through the dipleg, hydrocarbons on the surface of the solids are stripped by an upward ~low of stripping gas, nondclcteriously reacti~e with respect to pyrolysis products, such as steam. The stripping gas is introduced through gas inlets 120 on the side of the dipleg. The bed 60 is maintained in a fluidized state by an upward flow of fluidizing gas stream 91 into the Yessel 52 through the gas inlet 62 and distributed by the distributor plate 64. The fluidizing gas can be nonreactive with respect to the solids in the fluidized bed, being for instance the off gas product of pyrolysis, or the gas may contain a portion of the oxygen required for oxidizing the solids to form the particulate source of ~eat.
A transport gas is introduced upwardly through the gas inlet 56 and nozzle 58 into the riser 54. The transport gas preferably conta;lls free oxygen. Other reactan1,s which lea~
to the formation of carboll monoxide may be ~-resent~ These include ste.~ and carbon dioxide, When steam is present,
3~ hydrogen also is formed.
~? -In the preferred process, the transport gas contains,as indicated, some oxygen to generate a portion of the heat necessary to raise the char to the temperature required for feed to the pyrolysis reactor in the first combustion zone.
However, the amount of oxy~en is limited for if there is too much oxygen in the transport gas, the carbon monoxide generated in the transport line cannot be converted to carbon dioxide in the second combustion zone without introducing so much additional oxygen to the second combustion zone that the char would be raised to a temperature above the te~perature required for feed to the pyrolysis reactor.
As indicat~d i.n ~igure 1, the transport gas can be an air stream 90 introduced upwardly through the gas inlet 56 and nozzle 58 into the conduit 54. A sufficient supply of this air stream at a.n appropriate oxygen content is maintained to: 1) educt solids ~rom the fluidized bed into the conduit;
2) to oxidize a portion of the carbon in the solids to heat the solids in tho conduit and riser; and 3) to transport the solids and combustion products, including carbon monoxide, of the solids upwardly through the verti.cal riser 68 into the second combustion zone chamber 70. The fluidizing gas stream 91 passes through the annular or space gap 74 between the upper edge 72 of the conduit and the vertical r;ser 68 to help carry the solids vpwardly into the second combustion chamber 70 If the top portion 71 of tlle conduit is smaller in dia~neter than the riser, the flow of gas and solids upwardly in-to t}le riser from the conduit can serve to eduet t~e f]uidizing gas into the riser t1lrough the annular gap 74, The ve:locity of the transport gas is main1;ained s~^ficielltly .3~1~
high to educt solids into the conduit and convey them into the second combustion zone. For~example, when the transport gas contains air as a source of oxygen, a diluent gas subst~ntially free of free oxygen, e.g. nitrogen or flue gas, can be combined with the air to provide an oxygen-lean carrier gas having sufficient velocity to educt and transport the solids without introducing too much oxygen to generate too much carbon monoxide. By diluting the heated air stream, a carrier gas stream containing less than about 20% oxygen by volume is formed.
The amount of oxygen in the transport gas is controlled to maintain the desired temperature in the riser. This is always less tha-l the stoichiometric amount required to completely oxi~lize the char. Because of this deficiency of oxygen and the relatively high temperature in the riser, which can range up to about 1100 F. (595 C) in the case of a pyrolysis reaction zone maintained at a te]nperature ranging up to over 2000 F. ( 1100 C. ) for a pyrolysis reaction designed to enhance gasif;cation, appreciable amounts of carbon Tnonoxide are formed.
Also, as the solids and combustion gases pass upwardly through the riser 68, carbon dioxide introduced in the ~transport gas and carbon dioxide formed by oxidation of char tends to react with additional carbon in the char to rorm carbon monoxide according to the reaction:
C ~ C02 ~ 2CO
Thus generally,less than about halr, and usuall~- from about 20 to about 50C~ 0~ the oxygen required to form the particulate 3o source O:r heat 3 g in the transport gas. The remainder o~` the - 2~ _ 3~
oxygen required is introduced into the second combustion zone to oxidize the carbon monoxide from the first combustion zone to carbon dioxide.
Excess solids in the fluidized bed beyond what is required for oxidation to form the particulate source of heat represent the net solid product of the pyrolysis reaction, and are withdrawn from the first chamber through line 94.
The configuration of the combustion unit shown in the drawings and described above has many advantages. Among these is instant ignltion of the solids entering the flui.dized bed 60. When exposed to a source of oxygen the carbon in the carbon-containing solid residue is readily oxidized. If the carbon~containing solid residue has poor ignition properties oxygen can be introduced with the fluidizing gas to oxidize carbon in the solids in the fluldized bed to raise the temperature of the fluidized bed.
Duri.ng startup, a f.uel gas followed by air can be utilized as a fluidizing ga.s to elevate the temperature of the solids in the fluidized bed above the solids igniti.on temperature . .
Another advantage of the scheme shown in the draw:ings an.d described above is that the temperature in the first combustion chamber is easily controlled by controlling the amount of o~ygen fed to the fluidized bed in the fluidizing gas stream 90, Another advantage results from the large 1nass of soli.ds in the fluidized ~ed. Because of this large mass, Jninor system upsets are damped by changcs in t}le le~el of t11e fluidized bed. As ~the le~rel i21 the flu:i~.izecl bed increases~
adclition~l solids are remo~ed through the ~ithdrawal line 94 and ~ddi.tional solids are educted by the tra~ls~c)rt g 3S becauso 1~.3L~14 of the higher differential pressure of the solids due to the increase in height of the bed. Conversely, as the level in the bed decreases fewer solids are withdrawrL as product arLd less solids arc ed~1cted by the transport gas because the differential pressure of the bed decreases.
If any additional controls on the level of the fluidized bed are required, the jet flow of the source of oxygen can be varied. Thus the fluidized bed is a self-compensating system.
Another advantage of the configuration of the first combustion ch~nber and vessel is that because the solids are fluidized in the fluidized bed, withdrawl of solid product is facilitated. As the level of the solids in the fluidized bed rises, more solids are au1omatically withdrawn through the solids outlet line 40. ~his line extends upwardly into the vessel 52 and its height determines the average top 80 of the fluidized bed in the vessel.
A major advantage of the scheme shown in the drawings is that it provides a comparatively "fail-safe" method of preventing oxygen in the combustion unit 50 from entering the pyrolysis scction 8. The hei~ht of the fluidized 1>ed acts as a barrier against the backflow of oxyge~l through the dipleg 78 inlo the pyrolysis reactor. In addition, au-tomatic control means can be provided to scnse the level of the fluidi~.ed bed, and ir t~-Le level drops too low, automatically to cut off the fLow of the source of oxyge into the firs-l combllstion cl1amber.
A source of oxy~erl is int:roduced throu~]l il1e ~s inlet 8~ into t;lle seeolLd co~nbustio-n ZOl.e. Tlle amc,~ Li; of free oxygen introd~Lcec1 illtO tl]e SeCOrlCI Colnl);lStioll ~O~.C c~uals ca-t _ ~6 -l~i3'~4 least 50~ of the molar amount of carbon monoxide entering the stage to completely oxidize carbon monoxide generated in the first combustion zone so the total potential heating value of the char oxidized in the first combustion zone is obtained. In addition, oxygen above the stoichiometric amount can be added to react with the carbon in the char to heat the char to the temperature required to form the particulate source of heat for introduction into the pyrolysis zone. The total oxygen feed to the two oxidation stages is at all times sufficient to raise the solids to the temperature required for feed to the pyrolysis zone.
Typically the particulate source of heat has a temperature from about 100 to 500 F, (55 - 280 C.) highcr than the pyrolysis zone temperature.
Introducing oxygcn to oxidize carbon in the solid residue in two combustion zones serves to obtain maximum heating value from solid residue by oxidation. When the~
solid residue is oxidized where there is less than stoichiometric amounts of oxygen and/or the residence time is long, t;hen some of the carbon dioxide in the reaction product gases tends to react with carbon in the solid residue to produce carbon monoxide. This is undesirable because more valuable carbon-cont;aining solids residue has to be burned to achieve desired temperatures than if carbon dioxide were the only product;. Net carbor mono~ide formed is minimiæed and the carborl dioxide to carbon monoxide ratio maximized to maximize tl-~e alllount of heat generated per Ullit ~ree carbon combusted by using two ca~bust;ion zones.
The formecl particulate source of hea-t and the gaseous l~i34~4 ;~ . , combustion products of the solids, as well as nonreactive components of the source of oxygen such as nitrogen, pass from the second combustion chamber to a second cyclone separator 84. In the separat3r the particulate so~rce of heat is separated from the combustion gases for feed to the pyrolysis reaction zone. The gases 100 are discharged through the top o~ the cyclone 84. Because most of the c carbon monoxide formed in the riser and conduit is oxidized to carbon dioxide in the oxidation zone, the combustion gases ~0 can be directly released to the atmosphere. How-~ver, if ... . .
there are appreciable amounts of carbon monoxide or other `-pollutants in the combustion gas stream 100 from the second cyclone separator 84, these gases can be treated as by chemical scrubbing before release to tha atmosphere.
,~
ÇJ ~ ~lthough the drawings show the second combustion zone and the second cyclone separation zone oonstituted by oeparate apparatus, it is possible to form the particulate source of heat from the preheated solids and separate the particulate source of heat from the gaseous combustion products ~` -20 simultaneously in a single cyclone oxidation-separation zone.
This modification has significant advantages. ~nong these advantages are reduced capital and operating costs for the process because a separator and a combustion zone are replaced with a single cyclone separator. In addition, production of car~on monoxide is minimized because short reac~ion times, which favour production of carbon dioxide, . , .
are obtained ~y using a cyclone vessel ~or oxidizing the carbon-containing solid residue~ lt is preferred that the residence times of solids in a cyclone oxidation-separatioll zone be less than about 5 seconds, and more pre-r`erably~ from
~? -In the preferred process, the transport gas contains,as indicated, some oxygen to generate a portion of the heat necessary to raise the char to the temperature required for feed to the pyrolysis reactor in the first combustion zone.
However, the amount of oxy~en is limited for if there is too much oxygen in the transport gas, the carbon monoxide generated in the transport line cannot be converted to carbon dioxide in the second combustion zone without introducing so much additional oxygen to the second combustion zone that the char would be raised to a temperature above the te~perature required for feed to the pyrolysis reactor.
As indicat~d i.n ~igure 1, the transport gas can be an air stream 90 introduced upwardly through the gas inlet 56 and nozzle 58 into the conduit 54. A sufficient supply of this air stream at a.n appropriate oxygen content is maintained to: 1) educt solids ~rom the fluidized bed into the conduit;
2) to oxidize a portion of the carbon in the solids to heat the solids in tho conduit and riser; and 3) to transport the solids and combustion products, including carbon monoxide, of the solids upwardly through the verti.cal riser 68 into the second combustion zone chamber 70. The fluidizing gas stream 91 passes through the annular or space gap 74 between the upper edge 72 of the conduit and the vertical r;ser 68 to help carry the solids vpwardly into the second combustion chamber 70 If the top portion 71 of tlle conduit is smaller in dia~neter than the riser, the flow of gas and solids upwardly in-to t}le riser from the conduit can serve to eduet t~e f]uidizing gas into the riser t1lrough the annular gap 74, The ve:locity of the transport gas is main1;ained s~^ficielltly .3~1~
high to educt solids into the conduit and convey them into the second combustion zone. For~example, when the transport gas contains air as a source of oxygen, a diluent gas subst~ntially free of free oxygen, e.g. nitrogen or flue gas, can be combined with the air to provide an oxygen-lean carrier gas having sufficient velocity to educt and transport the solids without introducing too much oxygen to generate too much carbon monoxide. By diluting the heated air stream, a carrier gas stream containing less than about 20% oxygen by volume is formed.
The amount of oxygen in the transport gas is controlled to maintain the desired temperature in the riser. This is always less tha-l the stoichiometric amount required to completely oxi~lize the char. Because of this deficiency of oxygen and the relatively high temperature in the riser, which can range up to about 1100 F. (595 C) in the case of a pyrolysis reaction zone maintained at a te]nperature ranging up to over 2000 F. ( 1100 C. ) for a pyrolysis reaction designed to enhance gasif;cation, appreciable amounts of carbon Tnonoxide are formed.
Also, as the solids and combustion gases pass upwardly through the riser 68, carbon dioxide introduced in the ~transport gas and carbon dioxide formed by oxidation of char tends to react with additional carbon in the char to rorm carbon monoxide according to the reaction:
C ~ C02 ~ 2CO
Thus generally,less than about halr, and usuall~- from about 20 to about 50C~ 0~ the oxygen required to form the particulate 3o source O:r heat 3 g in the transport gas. The remainder o~` the - 2~ _ 3~
oxygen required is introduced into the second combustion zone to oxidize the carbon monoxide from the first combustion zone to carbon dioxide.
Excess solids in the fluidized bed beyond what is required for oxidation to form the particulate source of heat represent the net solid product of the pyrolysis reaction, and are withdrawn from the first chamber through line 94.
The configuration of the combustion unit shown in the drawings and described above has many advantages. Among these is instant ignltion of the solids entering the flui.dized bed 60. When exposed to a source of oxygen the carbon in the carbon-containing solid residue is readily oxidized. If the carbon~containing solid residue has poor ignition properties oxygen can be introduced with the fluidizing gas to oxidize carbon in the solids in the fluldized bed to raise the temperature of the fluidized bed.
Duri.ng startup, a f.uel gas followed by air can be utilized as a fluidizing ga.s to elevate the temperature of the solids in the fluidized bed above the solids igniti.on temperature . .
Another advantage of the scheme shown in the draw:ings an.d described above is that the temperature in the first combustion chamber is easily controlled by controlling the amount of o~ygen fed to the fluidized bed in the fluidizing gas stream 90, Another advantage results from the large 1nass of soli.ds in the fluidized ~ed. Because of this large mass, Jninor system upsets are damped by changcs in t}le le~el of t11e fluidized bed. As ~the le~rel i21 the flu:i~.izecl bed increases~
adclition~l solids are remo~ed through the ~ithdrawal line 94 and ~ddi.tional solids are educted by the tra~ls~c)rt g 3S becauso 1~.3L~14 of the higher differential pressure of the solids due to the increase in height of the bed. Conversely, as the level in the bed decreases fewer solids are withdrawrL as product arLd less solids arc ed~1cted by the transport gas because the differential pressure of the bed decreases.
If any additional controls on the level of the fluidized bed are required, the jet flow of the source of oxygen can be varied. Thus the fluidized bed is a self-compensating system.
Another advantage of the configuration of the first combustion ch~nber and vessel is that because the solids are fluidized in the fluidized bed, withdrawl of solid product is facilitated. As the level of the solids in the fluidized bed rises, more solids are au1omatically withdrawn through the solids outlet line 40. ~his line extends upwardly into the vessel 52 and its height determines the average top 80 of the fluidized bed in the vessel.
A major advantage of the scheme shown in the drawings is that it provides a comparatively "fail-safe" method of preventing oxygen in the combustion unit 50 from entering the pyrolysis scction 8. The hei~ht of the fluidized 1>ed acts as a barrier against the backflow of oxyge~l through the dipleg 78 inlo the pyrolysis reactor. In addition, au-tomatic control means can be provided to scnse the level of the fluidi~.ed bed, and ir t~-Le level drops too low, automatically to cut off the fLow of the source of oxyge into the firs-l combllstion cl1amber.
A source of oxy~erl is int:roduced throu~]l il1e ~s inlet 8~ into t;lle seeolLd co~nbustio-n ZOl.e. Tlle amc,~ Li; of free oxygen introd~Lcec1 illtO tl]e SeCOrlCI Colnl);lStioll ~O~.C c~uals ca-t _ ~6 -l~i3'~4 least 50~ of the molar amount of carbon monoxide entering the stage to completely oxidize carbon monoxide generated in the first combustion zone so the total potential heating value of the char oxidized in the first combustion zone is obtained. In addition, oxygen above the stoichiometric amount can be added to react with the carbon in the char to heat the char to the temperature required to form the particulate source of heat for introduction into the pyrolysis zone. The total oxygen feed to the two oxidation stages is at all times sufficient to raise the solids to the temperature required for feed to the pyrolysis zone.
Typically the particulate source of heat has a temperature from about 100 to 500 F, (55 - 280 C.) highcr than the pyrolysis zone temperature.
Introducing oxygcn to oxidize carbon in the solid residue in two combustion zones serves to obtain maximum heating value from solid residue by oxidation. When the~
solid residue is oxidized where there is less than stoichiometric amounts of oxygen and/or the residence time is long, t;hen some of the carbon dioxide in the reaction product gases tends to react with carbon in the solid residue to produce carbon monoxide. This is undesirable because more valuable carbon-cont;aining solids residue has to be burned to achieve desired temperatures than if carbon dioxide were the only product;. Net carbor mono~ide formed is minimiæed and the carborl dioxide to carbon monoxide ratio maximized to maximize tl-~e alllount of heat generated per Ullit ~ree carbon combusted by using two ca~bust;ion zones.
The formecl particulate source of hea-t and the gaseous l~i34~4 ;~ . , combustion products of the solids, as well as nonreactive components of the source of oxygen such as nitrogen, pass from the second combustion chamber to a second cyclone separator 84. In the separat3r the particulate so~rce of heat is separated from the combustion gases for feed to the pyrolysis reaction zone. The gases 100 are discharged through the top o~ the cyclone 84. Because most of the c carbon monoxide formed in the riser and conduit is oxidized to carbon dioxide in the oxidation zone, the combustion gases ~0 can be directly released to the atmosphere. How-~ver, if ... . .
there are appreciable amounts of carbon monoxide or other `-pollutants in the combustion gas stream 100 from the second cyclone separator 84, these gases can be treated as by chemical scrubbing before release to tha atmosphere.
,~
ÇJ ~ ~lthough the drawings show the second combustion zone and the second cyclone separation zone oonstituted by oeparate apparatus, it is possible to form the particulate source of heat from the preheated solids and separate the particulate source of heat from the gaseous combustion products ~` -20 simultaneously in a single cyclone oxidation-separation zone.
This modification has significant advantages. ~nong these advantages are reduced capital and operating costs for the process because a separator and a combustion zone are replaced with a single cyclone separator. In addition, production of car~on monoxide is minimized because short reac~ion times, which favour production of carbon dioxide, . , .
are obtained ~y using a cyclone vessel ~or oxidizing the carbon-containing solid residue~ lt is preferred that the residence times of solids in a cyclone oxidation-separatioll zone be less than about 5 seconds, and more pre-r`erably~ from
4~ -about 0.1 to about 3 seconds. This short residence time favours production of carbon dioxide compared to carbon monoxide. -Another advantage of using a cyclone oxidation-separation zone is that carbon-containing solid residue fines, which are less valuable than larger particles are burned preferentially because of the more efficient separation of the larger particles from the fines in the cyclone.
The formed particulate source of heat separated from the gases in the second cyclone separation zone is passed through the standpipe 86 to the fluidized chamber 32 surrounding the inlet to the pyrolysis reactor. The standpipe is fluidized by an aeration gas nondeleteriously reactive with respect to pyrolysis products. The aeration gas .
is introduced through the inlets 88 along the length of the standpipe.
Although the invention has- been described in terms of certain preferred embodiments other embodiments will be apparent to those skilled in the art. For example, steam can be injected along with the carbon-containing solid residue to the fluidizing chamber 32 to react with the hot particulate source of heat to form hydrogen gas by water-gas shift reactions. The hydrogen so produced can hydrogenate the volatilized hydrocarbons resulting from the pyrolysis of the carbonaceous material to upgrade their value. In addition, one or more cyclones in series or parallel as required can be used to replace the cyclone separators 22, 84. The advanta~e of using more than one cyclone in series is that a fines frac*ion of the carbon containing solid residue and a fine~
fraction of the particulate source of heat can be removed ~ 29 . . , from the bulk of the particles so that the amount of solids carried over with the vapor mixture to a product recovery operation is minimized.
The formed particulate source of heat separated from the gases in the second cyclone separation zone is passed through the standpipe 86 to the fluidized chamber 32 surrounding the inlet to the pyrolysis reactor. The standpipe is fluidized by an aeration gas nondeleteriously reactive with respect to pyrolysis products. The aeration gas .
is introduced through the inlets 88 along the length of the standpipe.
Although the invention has- been described in terms of certain preferred embodiments other embodiments will be apparent to those skilled in the art. For example, steam can be injected along with the carbon-containing solid residue to the fluidizing chamber 32 to react with the hot particulate source of heat to form hydrogen gas by water-gas shift reactions. The hydrogen so produced can hydrogenate the volatilized hydrocarbons resulting from the pyrolysis of the carbonaceous material to upgrade their value. In addition, one or more cyclones in series or parallel as required can be used to replace the cyclone separators 22, 84. The advanta~e of using more than one cyclone in series is that a fines frac*ion of the carbon containing solid residue and a fine~
fraction of the particulate source of heat can be removed ~ 29 . . , from the bulk of the particles so that the amount of solids carried over with the vapor mixture to a product recovery operation is minimized.
Claims (61)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED IN WHICH:
1. In a process for pyrolysis of particulate solid carbon-aceous materials in which a particulate solid carbonaceous material is pyrolyzed by heat transferred thereto by a particulate source of heat to yield a particulate carbon containing solid residue as a product of pyrolysis and in which the particulate source of heat is formed by oxidizing at least a portion of the particulate carbon containing solid residue, the improvement which comprises forming the particulate source of heat by the steps of:
a) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
b) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the particulate carbon containing solid residue thereby partially heating the particulate carbon containing solid residue and to transport particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone; and c) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones being sufficient to generate the particulate source of heat.
a) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
b) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the particulate carbon containing solid residue thereby partially heating the particulate carbon containing solid residue and to transport particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone; and c) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones being sufficient to generate the particulate source of heat.
2. The method of claim 1 in which the conduit is spaced apart from the riser, and the particulate carbon containing solid residue is fluidized in the fluidized bed by an upward flow of a fluidizing gas, and wherein fluidizing gas passes into the riser through the space between the riser and the conduit.
3. The method of claim 1 in which the fluidized bed is fluidized by a fluidizing gas containing oxygen.
4. A continuous process for pyrolysis of particulate solid carbonaceous materials which comprises, in combination, the steps of:
a) subjecting a particulate solid carbonaceous material to flash pyrolysis by continuously:
(i) transporting the particulate solid carbonaceous material contained in a carrier gas which is substantially nondeleteriously reactive with respect to products of pyrolysis of the particulate solid carbonaceous material to a substantially vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature below about 2000 F;
(ii) feeding a particulate source of heat at a temperature above the pyrolysis temperature and comprising heated particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iii) forming a turbulent mixture of the particulate source of heat, particulate solid carbonaceous material and carrier gas to pyrolyze the particulate solid carbonaceous material and yield a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
b) passing the pyrolysis product stream from the pyrolysis reactor to a first separation zone and separating at least the bulk of the solids from the vapor mixture; and c) forming the particulate source of heat by:
(i) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material and separated from the vapour mixture to a fluidized bed around a substantially vertically oriented open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combus-tion zone;
(ii) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the particulate carbon containing solid residue thereby heating the particulate carbon containing solid residue and to transport particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone;
(iii) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones in combination being sufficient to generate the particulate source of heat; and (iv) passing the formed particulate source of heat and the gaseous combustion products from the second combustion zone to a second separation zone and separating the particulate source of heat from the gaseous combustion products of the particulate carbon containing solid residue and feeding the thusly separated particulate source of heat to the pyrolysis reactor.
a) subjecting a particulate solid carbonaceous material to flash pyrolysis by continuously:
(i) transporting the particulate solid carbonaceous material contained in a carrier gas which is substantially nondeleteriously reactive with respect to products of pyrolysis of the particulate solid carbonaceous material to a substantially vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature below about 2000 F;
(ii) feeding a particulate source of heat at a temperature above the pyrolysis temperature and comprising heated particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iii) forming a turbulent mixture of the particulate source of heat, particulate solid carbonaceous material and carrier gas to pyrolyze the particulate solid carbonaceous material and yield a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
b) passing the pyrolysis product stream from the pyrolysis reactor to a first separation zone and separating at least the bulk of the solids from the vapor mixture; and c) forming the particulate source of heat by:
(i) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material and separated from the vapour mixture to a fluidized bed around a substantially vertically oriented open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combus-tion zone;
(ii) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the particulate carbon containing solid residue thereby heating the particulate carbon containing solid residue and to transport particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone;
(iii) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones in combination being sufficient to generate the particulate source of heat; and (iv) passing the formed particulate source of heat and the gaseous combustion products from the second combustion zone to a second separation zone and separating the particulate source of heat from the gaseous combustion products of the particulate carbon containing solid residue and feeding the thusly separated particulate source of heat to the pyrolysis reactor.
5. A process as claimed in claim 4 in which the first separation zone is a cyclone separation zone.
6. A process as claimed in claim 4 in which the second separation zone is a cyclone separation zone.
7. A process as claimed in claim 4 in which the turbulent mixture in the pyrolysis reactor has a solids content ranging from about 0.1 to about 10% by volume based on the total volume of the pyrolysis product stream, and a weight ratio of the particulate source of heat to the particulate solid carbonaceous material of from about 2:1 to about 20:1.
8. A process as claimed in claim 4 in which the pyrolysis temperature is from about 900 to about 1400°F.
9. A process as claimed in claim 4 wherein the pyrolysis reactor has a solids feed inlet for the particulate solid carbonaceous material and a vertically oriented chamber surround-ing the upper portion of the pyrolysis reactor, the chamber having an inner peripheral wall forming an overflow weir to a vertically oriented mixing zone of the pyrolysis reactor, wherein the step of transporting particulate solid carbonaceous material to the reactor comprises transporting the particulate solid carbonaceous material contained in a carrier gas to the solids feed inlet, wherein the step of feeding a particulate source of heat to the pyrolysis reactor comprises feeding the particulate source of heat to the vertically oriented chamber surrounding the inlet to the pyrolysis reactor, maintaining the particulate source of heat in the vertically oriented chamber in a fluidized state by a flow of a fluidizing gas substantially nondeleteriously reactive with respect to the products of pyrolysis of the particulate solid carbonaceous material, and discharging the fluidized particulate source of heat over said weir and downwardly into said mixing zone, wherein the step of forming the turbulent mixture comprises injecting the particulate solid carbonaceous material contained in a carrier gas from the solids feed inlet into the mixing zone, and wherein the process comprises the additional step of passing the turbulent mixture downward from the mixing zone to the pyrolysis zone of the pyrolysis reactor to pyrolyze the particulate solid carbonaceous material.
10. The process of claim 9 in which residence time of the carrier gas in the pyrolysis zone of the pyrolysis reactor and the first separation zone in combination is less than about 5 seconds.
11. The process of claim 4 in which residence time of the carrier gas in the pyrolysis zone of the pyrolysis reactor and the first separation zone in combination is less than about 5 seconds.
12. The process of claim 4 in which residence time of the carrier gas in the pyrolysis zone of the pyrolysis reactor and the first separation zone in combination is less than about 3 seconds.
13. A process as claimed in claim 4 in which the particulate solid carbonaceous material is an agglomerative coal substantially of a particle size up to about 250 microns.
14. A process as claimed in claim 4 in which the pyrolysis temperature is from about 600 to about 2000°F.
15. A process as claimed in claim 4 in which the pyrolysis temperature is from about 600 to about 1400°F.
16. A process as claimed in claim 4 in which residence time of the carrier gas in the pyrolysis zone and first separation zone in combination is from about 0.1 to about 3 seconds.
17. A process as claimed in claim 4 in which the second combustion zone comprises a cyclone oxidation-separation zone.
18. A process as claimed in claim 17 in which residence time of the particulate carbon containing solid residue in the cyclone oxidation-separation zone is less than about 5 seconds.
19. A process as claimed in claim 17 in which residence time of the particulate carbon containing solid residue in the cyclone oxidation-separation zone is less than about 3 seconds.
20. A process as claimed in claim 4 in which a substantial portion of the particulate solid carbonaceous material is particles of a size up to about 1000 microns in diameter.
21. A process as claimed in claim 4 in which the particulate solid carbonaceous material is an agglomerative coal and sub-stantially composed of particles of a size less than about 250 microns in diameter.
22. A continuous process for pyrolysis of agglomerative coals which comprises the steps of:
a) providing a particulate agglomerative coal feed containing agglomerative coal particles of a size less than about 250 microns in diameter;
b) subjecting the particulate coal feed to flash pyrolysis by continuously:
(i) transporting the particulate agglomerative coal feed contained in a carrier gas which is nondeleteriously reactive with respect to products of pyrolysis of the particulate agglomerative coal feed to a solids feed inlet of a vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature above about 600°F;
(ii) feeding a particulate source of heat at a temperature above the pyrolysis temperature and comprising heated char resulting from pyrolysis of the particulate agglomerative coal feed to a vertically oriented chamber surrounding the upper portion of the pyrolysis reactor, the chamber having an inner peripheral wall forming an overflow weir to a vertically oriented mixing zone of the pyrolysis reactor, the particulate heat source in said chamber being maintained in a fluidized state by the flow therethrough of a fluidizing gas substantially nondeleteriously reactive with respect to the products of pyrolysis of the particulate agglomerative coal feed;
(iii) discharging the particulate source of heat over said overflow weir and downwardly into said mixing zone at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iv) injecting the particulate agglomerative coal feed and carrier gas from the solids feed inlet into the mixing zone to form a turbulent mixture of the particulate source of heat, the particulate agglomerative coal feed and carrier gas, (v) passing the resultant turbulent mixture downwardly from said mixing zone to the pyrolysis zone of said pyrolysis reactor to pyrolyze the particulate agglomerative coal feed and yield a pyrolysis product stream containing as solids, the particulate source of heat and char, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
c) passing the pyrolysis product stream from said pyrolysis reactor to a first cyclone separation zone and separat-ing at least the bulk of the solids from the vapor mixture;
d) forming the particulate source of heat by:
(i) transporting at least a portion of the separated solids from the first cyclone separation zone to a fluidized bed around a substantially vertically oriented open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
(ii) educting solids from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the solids thereby partially heating the solids and transporting partially heated solids and gaseous combustion products of the solids, including carbon monoxide, to a second combustion zone;
(iii) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed to carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones being sufficient to generate the particulate source of heat; and (iv) passing the formed particulate source of heat and the gaseous combustion products from the second combustion zone to a second separation zone and separating the formed particulate source of heat from the gaseous combustion products of the solids for feed of the formed particulate source of heat to the verti-cally oriented chamber of the pyrolysis reactor;
e) passing the formed particulate source of heat thusly separated to the vertically oriented chamber surrounding the upper portion of the pyrolysis reactor.
a) providing a particulate agglomerative coal feed containing agglomerative coal particles of a size less than about 250 microns in diameter;
b) subjecting the particulate coal feed to flash pyrolysis by continuously:
(i) transporting the particulate agglomerative coal feed contained in a carrier gas which is nondeleteriously reactive with respect to products of pyrolysis of the particulate agglomerative coal feed to a solids feed inlet of a vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature above about 600°F;
(ii) feeding a particulate source of heat at a temperature above the pyrolysis temperature and comprising heated char resulting from pyrolysis of the particulate agglomerative coal feed to a vertically oriented chamber surrounding the upper portion of the pyrolysis reactor, the chamber having an inner peripheral wall forming an overflow weir to a vertically oriented mixing zone of the pyrolysis reactor, the particulate heat source in said chamber being maintained in a fluidized state by the flow therethrough of a fluidizing gas substantially nondeleteriously reactive with respect to the products of pyrolysis of the particulate agglomerative coal feed;
(iii) discharging the particulate source of heat over said overflow weir and downwardly into said mixing zone at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iv) injecting the particulate agglomerative coal feed and carrier gas from the solids feed inlet into the mixing zone to form a turbulent mixture of the particulate source of heat, the particulate agglomerative coal feed and carrier gas, (v) passing the resultant turbulent mixture downwardly from said mixing zone to the pyrolysis zone of said pyrolysis reactor to pyrolyze the particulate agglomerative coal feed and yield a pyrolysis product stream containing as solids, the particulate source of heat and char, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
c) passing the pyrolysis product stream from said pyrolysis reactor to a first cyclone separation zone and separat-ing at least the bulk of the solids from the vapor mixture;
d) forming the particulate source of heat by:
(i) transporting at least a portion of the separated solids from the first cyclone separation zone to a fluidized bed around a substantially vertically oriented open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
(ii) educting solids from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit to oxidize carbon in the solids thereby partially heating the solids and transporting partially heated solids and gaseous combustion products of the solids, including carbon monoxide, to a second combustion zone;
(iii) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed to carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones being sufficient to generate the particulate source of heat; and (iv) passing the formed particulate source of heat and the gaseous combustion products from the second combustion zone to a second separation zone and separating the formed particulate source of heat from the gaseous combustion products of the solids for feed of the formed particulate source of heat to the verti-cally oriented chamber of the pyrolysis reactor;
e) passing the formed particulate source of heat thusly separated to the vertically oriented chamber surrounding the upper portion of the pyrolysis reactor.
23. The process of claim 22 in which the particulate source of heat is passed from the second separation zone to the verti-cally oriented chamber surrounding the upper portion of the pyrolysis reactor through a vertically oriented standpipe fluidized with a gas which is nondeleteriously reactive with respect to products of pyrolysis of the particulate agglomerative coal feed.
24. The process of claim 22 in which carrier gas residence time in the pyrolysis zone of the pyrolysis reactor and the first cyclone separation zone in combustion is less than about 5 seconds.
25. A process as claimed in claim 22 in which the turbulent mixture in the pyrolysis reactor has a solids content ranging from about 0.1 to about 10% by volume based on the total volume of the turbulent mixture, and a weight ratio of the particulate source of heat to particulate agglomerative coal feed from about 2:1 to about 20:1.
26. A process as claimed in claim 22 in which the pyrolysis temperature is from about 900 to about 1400°F.
27. A process as claimed in claim 22 in which the pyrolysis temperature is from about 600 to about 2000°F.
28. A process as claimed in claim 22 in which the pyrolysis temperature is from about 600 to about 1400°F.
29. A continuous process for pyrolysis of solid carbonaceous materials comprising the steps of:
a) subjecting a particulate solid carbonaceous material to flash pyrolysis by continuously:
(i) transporting particulate solid carbonaceous material contained in a carrier gas which is substantially nondeleteriously reactive with respect to products of pyrolysis of the particulate solid carbonaceous material to a vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature from about 600 to about 2000°F;
(ii) feeding a particulate source of heat at a temperature above the pyrolysis temperature and comprising heated particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iii) forming a turbulent mixture of the particulate source of heat, particulate solid carbonaceous material and carrier gas and pyrolyzing the particulate solid carbonaceous material feed to form a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
b) passing the pyrolysis product stream from the pyrolysis reactor to a first separation zone and separating at least the bulk of the solids from the vapor mixture;
c) forming the particulate source of heat by:
(i) transporting at least a portion of the separated solids from the first separation zone to a fluidized bed around a sub-stantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the riser and conduit comprising a first combustion zone;
(ii) fluidizing the solids in the fluidizing bed with an upward flow of a fluidizing gas which then passes into the riser through the space between the conduit and the riser;
(iii) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit and oxidizing carbon in the particulate carbon containing solid residue thereby partially heating the particulate carbon contain-ing solid residue and transporting particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone; and (iv) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones in combination being sufficient to generate the particulate source of heat;
d) passing the formed particulate source of heat and combustion gases from the second combustion zone to a second separation zone and separating the particulate source of heat from the gaseous combustion product and feeding the separated particulate source of heat to the pyrolysis reactor.
a) subjecting a particulate solid carbonaceous material to flash pyrolysis by continuously:
(i) transporting particulate solid carbonaceous material contained in a carrier gas which is substantially nondeleteriously reactive with respect to products of pyrolysis of the particulate solid carbonaceous material to a vertically oriented, descending flow pyrolysis reactor containing a pyrolysis zone operated at a pyrolysis temperature from about 600 to about 2000°F;
(ii) feeding a particulate source of heat at a temperature above the pyrolysis temperature and comprising heated particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material to the pyrolysis reactor at a rate sufficient to maintain said pyrolysis zone at the pyrolysis temperature;
(iii) forming a turbulent mixture of the particulate source of heat, particulate solid carbonaceous material and carrier gas and pyrolyzing the particulate solid carbonaceous material feed to form a pyrolysis product stream containing as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material, and a vapor mixture of carrier gas and pyrolytic vapors comprising hydrocarbons;
b) passing the pyrolysis product stream from the pyrolysis reactor to a first separation zone and separating at least the bulk of the solids from the vapor mixture;
c) forming the particulate source of heat by:
(i) transporting at least a portion of the separated solids from the first separation zone to a fluidized bed around a sub-stantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the riser and conduit comprising a first combustion zone;
(ii) fluidizing the solids in the fluidizing bed with an upward flow of a fluidizing gas which then passes into the riser through the space between the conduit and the riser;
(iii) educting particulate carbon containing solid residue from the fluidized bed upwards into the first combustion zone by injecting a gaseous source of oxygen upwardly into the conduit and oxidizing carbon in the particulate carbon containing solid residue thereby partially heating the particulate carbon contain-ing solid residue and transporting particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone; and (iv) introducing a source of oxygen into the second combustion zone in an amount at least equal to 50% of the molar feed of carbon monoxide to the second combustion zone for oxidation of such carbon monoxide in the second combustion zone, the total oxygen fed to the first and second combustion zones in combination being sufficient to generate the particulate source of heat;
d) passing the formed particulate source of heat and combustion gases from the second combustion zone to a second separation zone and separating the particulate source of heat from the gaseous combustion product and feeding the separated particulate source of heat to the pyrolysis reactor.
30. The process of claim 29 in which the fluidizing gas contains oxygen to partially oxidize carbon in the separated solids to heat the solids separated in the fluidized bed.
31. A process as claimed in claim 29 in which the pyrolysis temperature is from about 900 to about 1400°F.
32. A process as claimed in claim 29 in which the pyrolysis temperature is from about 600 to about 1400°F.
33. A process as claimed in claim 29 in which the particulate solid carbonaceous material is a particulate agglomerative coal substantially of a particle size up to about 250 microns.
34. A process as claimed in claim 29 in which a substantial portion of the particulate solid carbonaceous material is particles in the range up to about 1000 microns in diameter.
35. A process as claimed in claim 29 in which the particulate solid carbonaceous material is a particulate agglomerative coal and substantially composed of particles of a size less than about 250 microns in diameter.
36. An apparatus for forming a particulate solid source of heat from a particulate carbon containing solid residue of pyrolysis of a particulate solid carbonaceous material for pyrolysis of the solid carbonaceous material comprising:
a) a vessel for containing a fluidized bed of a particulate carbon containing solid residue of pyrolysis of a particulate solid carbonaceous material around an open, sub-stantially vertically oriented conduit, said vessel being coupled to one end of a substantially vertically oriented riser in open communication with the conduit, the riser and conduit serving as a first combustion chamber;
b) a second combustion chamber in communication with the opposed end of the riser;
c) means for introducing particulate carbon containing solid residue of pyrolysis into the vessel to from the fluidized bed;
d) means for injecting a gaseous source of oxygen upwardly into the conduit to educt particulate carbon containing solid residue from a fluidized bed of particulate carbon contain-ing solid residue of pyrolysis contained in the vessel first into the conduit and then into the riser to oxidize carbon in the particulate carbon containing solid residue of pyrolysis for heating the particulate carbon containing solid residue in the first combustion chamber with attendant formation of carbon monoxide;
e) means for introducing oxygen into the second combustion chamber to form the particulate source of heat and to oxidize carbon monoxide; and f) means for fluidizing a fluidized bed of the particulate carbon containing solid residue of pyrolysis contained by the vessel.
a) a vessel for containing a fluidized bed of a particulate carbon containing solid residue of pyrolysis of a particulate solid carbonaceous material around an open, sub-stantially vertically oriented conduit, said vessel being coupled to one end of a substantially vertically oriented riser in open communication with the conduit, the riser and conduit serving as a first combustion chamber;
b) a second combustion chamber in communication with the opposed end of the riser;
c) means for introducing particulate carbon containing solid residue of pyrolysis into the vessel to from the fluidized bed;
d) means for injecting a gaseous source of oxygen upwardly into the conduit to educt particulate carbon containing solid residue from a fluidized bed of particulate carbon contain-ing solid residue of pyrolysis contained in the vessel first into the conduit and then into the riser to oxidize carbon in the particulate carbon containing solid residue of pyrolysis for heating the particulate carbon containing solid residue in the first combustion chamber with attendant formation of carbon monoxide;
e) means for introducing oxygen into the second combustion chamber to form the particulate source of heat and to oxidize carbon monoxide; and f) means for fluidizing a fluidized bed of the particulate carbon containing solid residue of pyrolysis contained by the vessel.
37. An apparatus as claimed in claim 36 in which the conduit is separated from the vertical riser.
38. An apparatus for pyrolysis of solid carbonaceous material comprising:
a) a descending flow pyrolysis reactor;
b) means for forming a turbulent mixture of a particulate source of heat and a particulate solid carbonaceous material contained in a carrier gas for introduction into the pyrolysis reactor to pyrolyze the particulate solid carbonaceous material to form a pyrolysis product stream containing a vapor mixture and, as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material;
c) a first separator for separating at least the bulk of the solids from the vapor mixture in the pyrolysis product stream;
d) means for transferring the pyrolysis product stream from the pyrolysis reactor to the first separator;
e) means for forming the particulate source of heat comprising:
(i) a vessel for containing a fluidized bed of the separated solids around an open, substantially vertically oriented conduit, said vessel coupled to one end of a substantially vertically oriented riser in open communication with the conduit, the riser and conduit serving as a first combustion chamber;
(ii) a second combustion chamber in communication with the opposed end of the riser;
(iii) means for introducing a gaseous source of oxygen up-wardly into the conduit to educt separated solids contained in the vessel upward into the first combustion chamber and from the first combustion chamber to the second combustion chamber to partially oxidize carbon in the solids to heat the solids in the first combustion chamber with attendant formation of gaseous combustion products including carbon monoxide;
(iv) means for introducing oxygen into the second combustion chamber to further heat the solids to form the particulate source of heat and to oxidize such carbon monoxide;
(v) means for fluidizing separated solids contained by the vessel;
f) means for passing the separated solids from the first separator to the fluidized bed of the separated solids;
g) means for transferring the particulate source of heat and gaseous combustion products from the second combustion chamber to a second separator;
h) a second separator for separating the particulate source of heat from the gaseous combustion products; and i) means for transferring the separated particulate source of heat from the second separator to the pyrolysis reactor.
a) a descending flow pyrolysis reactor;
b) means for forming a turbulent mixture of a particulate source of heat and a particulate solid carbonaceous material contained in a carrier gas for introduction into the pyrolysis reactor to pyrolyze the particulate solid carbonaceous material to form a pyrolysis product stream containing a vapor mixture and, as solids, the particulate source of heat and a particulate carbon containing solid residue of pyrolysis of the particulate solid carbonaceous material;
c) a first separator for separating at least the bulk of the solids from the vapor mixture in the pyrolysis product stream;
d) means for transferring the pyrolysis product stream from the pyrolysis reactor to the first separator;
e) means for forming the particulate source of heat comprising:
(i) a vessel for containing a fluidized bed of the separated solids around an open, substantially vertically oriented conduit, said vessel coupled to one end of a substantially vertically oriented riser in open communication with the conduit, the riser and conduit serving as a first combustion chamber;
(ii) a second combustion chamber in communication with the opposed end of the riser;
(iii) means for introducing a gaseous source of oxygen up-wardly into the conduit to educt separated solids contained in the vessel upward into the first combustion chamber and from the first combustion chamber to the second combustion chamber to partially oxidize carbon in the solids to heat the solids in the first combustion chamber with attendant formation of gaseous combustion products including carbon monoxide;
(iv) means for introducing oxygen into the second combustion chamber to further heat the solids to form the particulate source of heat and to oxidize such carbon monoxide;
(v) means for fluidizing separated solids contained by the vessel;
f) means for passing the separated solids from the first separator to the fluidized bed of the separated solids;
g) means for transferring the particulate source of heat and gaseous combustion products from the second combustion chamber to a second separator;
h) a second separator for separating the particulate source of heat from the gaseous combustion products; and i) means for transferring the separated particulate source of heat from the second separator to the pyrolysis reactor.
39. The apparatus of claim 38 in which the conduit is spaced apart from the riser.
40. The apparatus of claim 38 in which the first separator is a cyclone separator.
41. The apparatus of claim 38 in which the second separator is a cyclone separator.
42. An apparatus as claimed in claim 38 in which the pyrolysis reactor contains a substantially vertically oriented mixing section and a substantially vertically oriented pyrolysis section, and the reactor has a solids feed inlet and a substant-ially vertically oriented chamber surrounding the upper portion of the reactor, wherein the inner peripheral wall of the chamber forms an overflow weir to the vertically oriented mixing section, and the means for forming a turbulent mixture comprises:
a) means for feeding particulate source of heat to the vertically oriented chamber;
b) means for introducing a fluidizing gas into the vertically oriented chamber to maintain the particulate source of heat therein in a fluidized state; and c) means for injecting the particulate solid carbonaceous material contained in the carrier gas from the solids feed inlet into the mixing section to form the turbulent mixture.
a) means for feeding particulate source of heat to the vertically oriented chamber;
b) means for introducing a fluidizing gas into the vertically oriented chamber to maintain the particulate source of heat therein in a fluidized state; and c) means for injecting the particulate solid carbonaceous material contained in the carrier gas from the solids feed inlet into the mixing section to form the turbulent mixture.
43. An apparatus for pyrolysis of agglomerative coals comprising:
a) a descending flow pyrolysis reactor containing a substantially vertically oriented mixing section, a substantially vertically oriented pyrolysis section, a solids feed inlet, and 2 substantially vertically oriented chamber surrounding the upper portion of the reactor, the substantially vertically oriented chamber having an inner peripheral wall forming an overflow weir to the mixing section, wherein a particulate agglomerative coal feed contained in a carrier gas is combined with a particulate source of heat under turbulent flow conditions in the pyrolysis section of the pyrolysis reactor to yield a pyrolysis product stream containing as solids the particulate source of heat and a particulate carbon containing solid residue of pyrolysis of the particulate agglomerative coal feed, and a vapor mixture;
b) means for feeding the particulate source of heat to the vertically oriented chamber;
c) means for introducing a fluidizing gas into the substantially vertically oriented chamber to maintain the particulate source of heat therein in a fluidized state;
d) means for passing the particulate agglomerative coal feed from the solids feed inlet into the mixing section;
e) a first cyclone separator in communication with the pyrolysis reactor for separating at least the bulk of the solids in the pyrolysis product stream from the vapor mixture in the pyrolysis product stream;
f) means for forming the particulate source of heat comprising:
(i) a vessel for containing a fluidized bed of the separated solids around an open, substantially vertically oriented conduit, said vessel coupled to one end of a substantially vertically oriented riser in open communication with the vertically oriented conduit and separated therefrom, the riser and conduit serving as a first combustion chamber;
(ii) a second combustion chamber in communication with the opposed end of the riser;
(iii) means for introducing a gaseous source of oxygen up-wardly into the conduit to educt separated solids contained in the vessel upward into the conduit and the riser and from the riser to the second combustion chamber to partially oxidize carbon in the solids in the first combustion chamber to heat the solids with attendant formation of gaseous combustion products including carbon monoxide;
(iv) means for introducing oxygen into the second combustion chamber to further heat the solids to form the particulate source of heat and to oxidize such carbon monoxide;
(v) means to fluidize separated solids contained by the vessel;
g) a dipleg from the first cyclone separator to the fluidized bed for transferring the separated solids from the first cyclone separator to the fluidized bed;
h) a second cyclone separator in communication with the second combustion chamber for separating the particulate source of heat from the gaseous combustion products; and i) a dipleg from the second cyclone separator to the chamber surrounding the upper portion of the pyrolysis reactor for transferring the particulate source of heat to the pyrolysis reactor.
a) a descending flow pyrolysis reactor containing a substantially vertically oriented mixing section, a substantially vertically oriented pyrolysis section, a solids feed inlet, and 2 substantially vertically oriented chamber surrounding the upper portion of the reactor, the substantially vertically oriented chamber having an inner peripheral wall forming an overflow weir to the mixing section, wherein a particulate agglomerative coal feed contained in a carrier gas is combined with a particulate source of heat under turbulent flow conditions in the pyrolysis section of the pyrolysis reactor to yield a pyrolysis product stream containing as solids the particulate source of heat and a particulate carbon containing solid residue of pyrolysis of the particulate agglomerative coal feed, and a vapor mixture;
b) means for feeding the particulate source of heat to the vertically oriented chamber;
c) means for introducing a fluidizing gas into the substantially vertically oriented chamber to maintain the particulate source of heat therein in a fluidized state;
d) means for passing the particulate agglomerative coal feed from the solids feed inlet into the mixing section;
e) a first cyclone separator in communication with the pyrolysis reactor for separating at least the bulk of the solids in the pyrolysis product stream from the vapor mixture in the pyrolysis product stream;
f) means for forming the particulate source of heat comprising:
(i) a vessel for containing a fluidized bed of the separated solids around an open, substantially vertically oriented conduit, said vessel coupled to one end of a substantially vertically oriented riser in open communication with the vertically oriented conduit and separated therefrom, the riser and conduit serving as a first combustion chamber;
(ii) a second combustion chamber in communication with the opposed end of the riser;
(iii) means for introducing a gaseous source of oxygen up-wardly into the conduit to educt separated solids contained in the vessel upward into the conduit and the riser and from the riser to the second combustion chamber to partially oxidize carbon in the solids in the first combustion chamber to heat the solids with attendant formation of gaseous combustion products including carbon monoxide;
(iv) means for introducing oxygen into the second combustion chamber to further heat the solids to form the particulate source of heat and to oxidize such carbon monoxide;
(v) means to fluidize separated solids contained by the vessel;
g) a dipleg from the first cyclone separator to the fluidized bed for transferring the separated solids from the first cyclone separator to the fluidized bed;
h) a second cyclone separator in communication with the second combustion chamber for separating the particulate source of heat from the gaseous combustion products; and i) a dipleg from the second cyclone separator to the chamber surrounding the upper portion of the pyrolysis reactor for transferring the particulate source of heat to the pyrolysis reactor.
44. In a process for pyrolysis of particulate solid carbonaceous materials in which a particulate solid carbonaceous material is pyrolyzed by heat transferred thereto by a particulate source of heat to yield a particulate carbon containing solid residue as a product of pyrolysis and in which the particulate source of heat is formed by oxidizing at least a portion of the particulate carbon containing solid residue, the improvement which comprises forming the particulate source of heat by the steps of:
a) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
b) educting particulate carbon containing solid residue upward from the fluidized bed directly into the first combustion zone by injecting a transport gas upwardly into the conduit to transport particulate carbon containing solid residue to a second combustion zone; and c) generating the particulate source of heat by combustion of the particulate carbon containing solid residue in a combustion zone in the presence of oxygen.
a) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
b) educting particulate carbon containing solid residue upward from the fluidized bed directly into the first combustion zone by injecting a transport gas upwardly into the conduit to transport particulate carbon containing solid residue to a second combustion zone; and c) generating the particulate source of heat by combustion of the particulate carbon containing solid residue in a combustion zone in the presence of oxygen.
45. The method of claim 44 in which the conduit is spaced apart from the riser, and the particulate carbon containing solid residue is fluidized in the fluidized bed by an upward flow of a fluidizing gas, and wherein fluidizing gas passes into the riser through the space between the riser and the conduit.
46. The method of claim 44 in which the fluidized bed is fluidized by a fluidizing gas containing oxygen.
47. The method of claim 44 wherein the second combustion zone comprises a cyclone oxidation-separation zone in which carbon in the particulate carbon containing solid residue is oxidized to generate the particulate source of heat and gaseous combustion products of the particulate carbon containing solid residue and simultaneously therewith generated particulate source of heat is separated from such gaseous combustion products.
48. The method of claim 47 in which the source of oxygen is introduced directly into the cyclone oxidation-separation zone.
49. A process as claimed in claim 47 in which residence time of the carbon containing solid residue in the cyclone oxidation-separation zone is less than about 5 seconds.
50. A process as claimed in claim 47 in which residence time of the carbon containing solid residue in the cyclone oxidation-separation zone is less than about 3 seconds.
51. In a process for pyrolysis of particulate solid carbonaceous materials in which a particulate solid carbonaceous material is pyrolyzed by heat transferred thereto by a particulate source of heat to yield a particulate carbon containing solid residue as a product of pyrolysis and in which the particulate source of heat is formed by oxidizing at least a portion of the particulate carbon containing solid residue, the improvement which comprises forming the particulate source of heat by the steps of:
a) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
b) educting particulate carbon containing solid residue upward from the fluidized bed directly into the first combustion zone by injecting a transport gas comprising oxygen upwardly into the conduit to oxidize carbon in the particulate carbon contain-ing solid residue and partially heating the particulate carbon containing solid residue and transporting the particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone; and c) introducing a source of oxygen into the second combustion zone for oxidation of such carbon monoxide in the second combuation zone to form carbon dioxide, the total oxygen fed to the first and second combustion zones being sufficient to generate the particulate source of heat.
a) transporting at least a portion of the particulate carbon containing solid residue formed by pyrolysis of the particulate solid carbonaceous material to a fluidized bed around a substantially vertically oriented, open conduit in open communication with a substantially vertically oriented riser, the conduit and riser comprising a first combustion zone;
b) educting particulate carbon containing solid residue upward from the fluidized bed directly into the first combustion zone by injecting a transport gas comprising oxygen upwardly into the conduit to oxidize carbon in the particulate carbon contain-ing solid residue and partially heating the particulate carbon containing solid residue and transporting the particulate carbon containing solid residue and gaseous combustion products of the particulate carbon containing solid residue, including carbon monoxide, to a second combustion zone; and c) introducing a source of oxygen into the second combustion zone for oxidation of such carbon monoxide in the second combuation zone to form carbon dioxide, the total oxygen fed to the first and second combustion zones being sufficient to generate the particulate source of heat.
52. The method of claim 51 in which the conduit is spaced apart from the riser, and the particulate carbon containing solid residue is fluidized in the fluidized bed by an upward flow of a fluidizing gas, and wherein fluidizing gas passes into the riser through the space between the riser and the conduit.
53. The method of claim 51 in which the fluidized bed is fluidized by a fluidizing gas containing oxygen.
54. The method of claim 51 wherein the second combustion zone comprises a cyclone oxidation-separation zone in which carbon monoxide is oxidized to carbon dioxide and simultaneously there-with generated particulate source of heat is separated from such formed carbon dioxide.
55. The method of claim 54 in which the source of oxygen is introduced directly into the cyclone oxidation separation zone.
56. A process as claimed in claim 54 in which residence time of the particulate carbon containing solid residue in the cyclone oxidation-separation zone is less than about 5 seconds.
57. A process as claimed in claim 54 in which residence time of the particulate carbon containing solid residue in the cyclone oxidation-separation zone is less than about 3 seconds.
58. An apparatus for forming a particulate solid source of heat from a particulate carbon containing solid residue of pyrolysis of a particulate solid carbonaceous material for pyrolysis of the solid carbonaceous material comprising:
a) a vessel for containing a fluidized bed of a particulate carbon containing solid residue of pyrolysis of a particulate solid carbonaceous material around an open, substan-tially vertically oriented conduit, said vessel being coupled to one end of a substantially vertically oriented riser in open communication with the conduit;
b) a combustion chamber in communication with the riser;
c) means for introducing particulate carbon containing solid residue of pyrolysis into the vessel;
d) means for injecting a transport gas upwardly into the conduit to educt carbon containing solid residue of pyrolysis contained in the vessel upward first into the conduit and then into the riser and to transport the particulate carbon containing solid residue of pyrolysis to the combustion chamber;
e) means for introducing oxygen to the combustion chamber to oxidize carbon in the particulate carbon containing solid residue to form the particulate source of heat with attendant formation of combustion gas; and f) means for fluidizing particulate carbon containing solid residue of pyrolysis contained in the vessel.
a) a vessel for containing a fluidized bed of a particulate carbon containing solid residue of pyrolysis of a particulate solid carbonaceous material around an open, substan-tially vertically oriented conduit, said vessel being coupled to one end of a substantially vertically oriented riser in open communication with the conduit;
b) a combustion chamber in communication with the riser;
c) means for introducing particulate carbon containing solid residue of pyrolysis into the vessel;
d) means for injecting a transport gas upwardly into the conduit to educt carbon containing solid residue of pyrolysis contained in the vessel upward first into the conduit and then into the riser and to transport the particulate carbon containing solid residue of pyrolysis to the combustion chamber;
e) means for introducing oxygen to the combustion chamber to oxidize carbon in the particulate carbon containing solid residue to form the particulate source of heat with attendant formation of combustion gas; and f) means for fluidizing particulate carbon containing solid residue of pyrolysis contained in the vessel.
59. An apparatus as claimed in claim 58 in which the conduit is separated from the vertical riser.
60. The apparatus of claim 58 in which the combustion chamber is a cyclone for separating formed particulate source of heat from such formed combustion gas
61. The apparatus of claim 58 in which the means for introducing oxygen comprises means for introducing oxygen directly into the combustion chamber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US69999976A | 1976-06-25 | 1976-06-25 | |
| US699,999 | 1976-06-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113414A true CA1113414A (en) | 1981-12-01 |
Family
ID=24811803
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,355A Expired CA1113414A (en) | 1976-06-25 | 1977-06-13 | Pyrolysis processes utilizing a particulate heat source |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS532502A (en) |
| CA (1) | CA1113414A (en) |
| DE (1) | DE2728437A1 (en) |
| GB (1) | GB1583890A (en) |
| ZA (1) | ZA773556B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62282651A (en) * | 1986-05-31 | 1987-12-08 | 株式会社イセキ開発工機 | Crusher |
| JPS62282652A (en) * | 1986-06-02 | 1987-12-08 | 株式会社 イセキ開発工機 | Crusher |
-
1977
- 1977-06-10 GB GB24436/77A patent/GB1583890A/en not_active Expired
- 1977-06-13 CA CA280,355A patent/CA1113414A/en not_active Expired
- 1977-06-14 ZA ZA00773556A patent/ZA773556B/en unknown
- 1977-06-24 DE DE19772728437 patent/DE2728437A1/en not_active Withdrawn
- 1977-06-25 JP JP7604277A patent/JPS532502A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB1583890A (en) | 1981-02-04 |
| DE2728437A1 (en) | 1978-01-05 |
| ZA773556B (en) | 1978-05-30 |
| JPS532502A (en) | 1978-01-11 |
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