Note: Descriptions are shown in the official language in which they were submitted.
~6~
~ he present i~ention is directed to the pyrolysis
oî organic solid wastes ~rom indu~trial and municipal
sourceæ.
~ h~ di~po~al o:E wa~tes b`oth ~rom municipal and
industrial souroes, 3uch as trash, rubbish, garba~e,
animal wastes, agricultural wastcs, and waste of
plastic processing op~ration~ is rapidly be¢omlng o~
imme~ national conc~rn. lh¢ cost of disposal rank~
third behind public schooling and highways as municipal
10 expense in the IJnited Stato~.
It is estimated that each individual i~ th¢ U.S~A.
generates ~etween 4 and 6 pound~ (2 t~ 3 kg) of wa~t~
per day and that th~ industrial output 19 ~qulvalent to
approximatoly 5 pou~d~ (205 kg) o~ solid wast~ per
per~on per day4 Previou~ methodsl o~ maes wa~t~ diepo~al 9
euch ae landfill~ ar~ becoming impossible, while oth~rs
such as incineration are costly and result in air
` pollution ~roblem~
,
A va~t majority o~ the ~aste ~hich is pre~ntly
' 20 dispo~ed of co~tain~ products which are immediately
: recyalabla back into the eco~omy or product~ in~o
whi¢h the wa~te ca~ bc converted ~or reGycle ba~k to
the e~onomy. Directly recyclable constituents ~re the
' various metal~ preeent, ~uch as aluminium, steel and
:;. gla~s. For the most part 9 the org~nic solid w~st~
; ~raction may be ~ub~ect to a fla3h prolysis a~ an
: operation i~dependent o~ recovery o~ the directly
recyclable inorganic fraction and any organic portion
recovered a~ pulp~ ~la~h pyrolysis yield~, inter alia~
char, pyrolytic oil and gase~ as products~
.
~'~
-
~7~
It has now been found that selected size fractions of the
substantially carbDn-free particulate Lnorgania ~esidua formed from de-
carbonization of the carbon-contai m ng solid res~due from the pvrolysis
of organic waste which Lncludes f m e ino~ganics, particularly glass and
metals which elude gross recovery of ino~ganic values, have advantages over
the carbon-containing solid residue of pyrolysis as the source of heat for
flash pyrolysis. Relatively attr~tion-free, such material has excellent
fluidization charaateristics fo~ transpDrt to a pyrolysis ~eactor and is of
high bulk density. This latter property reduces signiflcantly the required
height for fluidized legs, improving mate~ially the feasibilit~ of flash
pyrolysis operatians which depend on their use.
The invention accordingl~ provides a process for the treabment
of soLid waste containing organic matte~ by separat m g said waste into an
inorganic fraction anl an organic fractio~ cantaLnLng entrainRd particulate
in~rga m c constituents, CCmmLnUting said organic fraction to particles having
a largest dimensian less than 25 mm and subjeating sald particles to ~lash
pyrolysis i~ a tuLbulent stre~m conta m m g ~ald particles, a paLticulate
solid heat sou~ce and a carrier gas that is non-deleteriously reactive with
the pyrol~sls products, the pyrolysis being c~nducted at a temperatu~e not
1 ss than 600F and suoh as to p~oduce a carbon-contaLning solid residue,
condensable p~rol~tic oil and gas, characterised in ~hat the said heat source
is solid pa~t~culate high density inorganic material resulting from
decarbonising at least pa~t of the carbon-containing residue o~ the pyrolysis
and having a sinterLng temperature higher than said pyrolysis tenpe~ature.
;; ' :' '
. . .
_ 3 _
7651~
In the pyrolysis~process of this invention, the solid organic
waste, includ~ng entra med inc~ganics, exists as discrete particles having a
maximum par~icle dimension less than one inch ~25 mm) and are preferably
of a size less than about 5 mesh ~U.S. standa~d). For ease of mass transpDrt
and t~ansfer of heat to the organic solid waste ~ndergoing pyrolysis, the
inorga m c solad heat source is of a sui~ably small particle size, preferably
ranging from 10 to 2,000 microns~ and most desiLably ranging from 20 to
1,000 micLons and hav m g, for instance, a bulk density ranging from 35
to 70 lbs~/cu~to ~560 to 1120 kg~m3). Preferably~ at least 50% of the
10 particles are grea~e~ than 37 microns.
Alth~ugh any gas ~hich is nondeleteriousl~ reactive, i.e. does
;~ not react deleteriously with the produats of
. ~
.
.
. , .
'
,''
''
` ~765~
pyrolysis, may ~e uæed a~ the carrier gas for tran~
porting both the organic solid waste and the hot
inorganic solid heat souree, it is preferred ~or
exp~ien¢y in the process to use a~ carrier gas the
ga~es which are the by-produots of the pyroly~i~
operation it3elf. ~he pri~oipal co~stituents o~ the
by-product ga~ are the oxide~ o carbon.
Residence time during flash pyroly~is i~ generally
~ le~ than 10 ~econds, preferably being from 0.1 to 2 .~:
`: 10 ~econd~, and most de~irably ranging from about 0~1 to
1 se¢o~d.
The weigh~ ratio of inorganlc solid heat source to
organic ~olid waste fed to the pyroly~is zo~e will vary
depending upon temperature o~ the heat source a~d the
temperature desired in the p~roly~is zone. Generally, ~:
about 2 ~o about 20 part3 bg weigh.~, preferably from :
4 to 6 part~ by weight, of inorganic ~olid heat ~ouree
per weight par~ of the commi~uted organic ~olld wa~te 1
fed to the pyroly~i~ 20ne.
Pyroly~i~ result8 from heating of the solid wa~te
primarily by solids-to-~olid~ heat transfer wlth ~ome ~olids-
to-ga~ to-~olide heat tran~fer occurring. To aohieve
thi~ end, tur~ulent flow ~ondition~ are required in the
pyrolyai~ zo~e. ~eynold~ w index numbers will,
there~ore, generally exceed 2,000 in the pyroly~is
zone, with Reynold~ number~ i~ exoea~ of 50,000
frequently bein~ employe~.
Following pyrolysi~, the particulate haaviar
inorganic ~olid heat source and carbon-oontaini~g solid
~ 30 residue o~ pyrolysie are ~eparated from the re~ultant
,. 5
~7~
:
high temperature ~tream, leaving ~ine carbon-containing
~ particle~, the co~densable pyrolytio oils, and the
- pyroly~i~ ga~es as a separate stream~ After separation
o~ the ~ine carbon-containing particles, the pyrolytic
~ oil~ are conden~ed, preferably using an oil quench,
and the gas to the extent requlred, recycled a~ carrier
ga~ for uRe in the proce~ The excess ga8 may be u~ed
;~ a~ drying gas ~ w811 ae a fuel source~
~he mixture of inorgani~ ~olid h~at source and
carbon-contai~i~g ~olid re~idue of pyrolys1~ which i3
~ reco~er~d from the pyroly~i~ zon~ i8 subject to decarb-
- onization, preferably by controlled combustio~ in the
pre~ence of a ~ource of gxyge~, ~ormally air, and water.
~ater aide i~ decarbonization and moderate~ thc
combustio~ temperature to mainta:L~ the temperature
below the temperature ab which fll~ion of the inorganic
particle3 will occur. For the particulate~inorganic~
e~trained in a typical org~nic ~olid waste, fusion
: temperature will generally ra~ge ~rom about 1425 to
2G 1700~o (775 to 925C.)o It i~ pre~erred to Gonduct
decarbonization at a c~ntrolled temperature belo~ th~
t~ring tamperature to avoid agglomeration o~ the
particl~. After deearbonization, the formed i~organic
~olid heat ~ource is proces~ed to ~electively reco~er
particles o~ larger size, e.~. 10 micron~ or more for
recycle, as required, to the pyrolysis zone. The
fin~ are recovered as a product. Because o~ its
glas~-like nature, the excess inorganic ~olid heat
.~ source may be u~ed as an asph~lt filler for road pa~i~g
opera~ion~, and therefore ha~ an immediate value i~ the
. - 6 -
.:.
.~
municipality proce~ing of the solid wa~te1 a~ part o~
an o~going operation.
Particular benefits of converti~g the carbon-containing
~olid residue of pyrolysis to the inorganic solld heat
~ource 3 however, are found i~ the ~avin~3 in equipment : :
~ize u~ed to tran~port the inorganic 801i~ heat sourc~
during the flash pyrolysis operation. ~he carbon-containing
~olid re~idue formed from organic wa~te re~ults ~ a
consequen~e o~ approximately a 50% reduction in the
particle ~iz~ of the wa~teO I~ forming the inorganic
solid heat souree9 however, there i~ a slgnificant inerea~e
i~ ~'ulk density, ranging ~rom 400 to 900~. ~he inorganic
eolia heat ~ource having, QS ind icated 9 a settled bulk
den~ity of betwee~ about 55 and about 70 pounds per cubi~
foot (880 to 1120 ~g/m3) ie of a particl~ e which
enables fluidization without cha~neli~g or ~lugging with
a material reduction of sta~dpipe or ~luidiz~d leg height
: required to meet the pres~ure differentials within the
.~ .
proce~. In addltio~, it i9 relatively stable a~d
i~se~iti~e to at~tio~, ha~ing in thi~ regard a
behaviour superior to catalysts normally employed i~
catalytic cracki~g O
; In addi~D~, by ~o~erti~ the carbon-containi~g
solid re~idue o~ pyroly~i~ to the inorganic ~olid heat
; source, a better o~erall heat balanoe i8 realized ~r
the ~yatem. When the oarbon oo~taini~g solid resi~ue
:, ia ueed aa a heat source, and the heat ia generated by
- limited oombuetio~ in air, the feed to a bur~er employe~ -
mu~t be oxygen-lean9 ~hia generates conaid~rable
quantitie3 of carbon mo~oxide with a generally low heat
. . , ~ '
;. . .
S~
release. By total decarbonization, ¢ombustion may occur
in a stoichiometric exce~s of air, maximizing -the amou~t
o~ heat generated for return in the inorganic solid heat
~ource to the pyroly~i~ reactorO These several advanta~e~
are not pre~ent in the us~ of the carbon-containing ~olid
residue of pyrolysis as the heat souree fQr pyroly~
.: ~he i~vention i~ ~urther de~cribed with refere~ce to
the accompa~ying drawi~g~, in which:
~IGURE 1 i3 a graphioal compa~ison o~ the ~luidized
bed density of the c~rbon-containing solid re~idue
- pyrolysi~,o~ the one hand, with the for~ed inorg~n1c
~olid heat ~ourc~ used i~ the pxoc~ss of the i~e~tio~,
~ on the othe~ hand;
: FIG~RE 2 illu~trat~ ap~aratus which may be used to
~: carry out th~ prooes~ of the ~nve~tion;
FIGURE 3 illu~trata~ anoth~r apparatu~ whi¢h may
be u~ed to carry QUt the proo0es of the invention;
~ IG~R~ ~ is a 60~ mi¢rophotogr~ph o~ particles
re~ulti~g ~rom pyrolysi~-of ~olid organlc wa~te and
whioh are gr~ater than 150 mesh but les~ than 100 me~h
9 ~ho~ing t~ combu~tible particles ~nd the
inorganic particles;
~ IGURE 5 i~ a 60~ microphotograph of p~rticle~
resulting from pyrolysis o~ solid organie waste and
whioh are finer than 150 me~h but lar~er than 200 me~h
in ~iz~, ~howing com~u~tible particle~ and i~organic
~ particle~ and
: ~IGURE 6 is a 60~ microphoto~raph o~ partiolee
re~ulting from pyroly~i~ of ~olid organic wa~te and
which are ~iner tha~ 400 me~h i~ ~ize, ~howi~g
7~
combustible particles and fly ash.
As above explainedJ in the process of the present invention, a par-
ticulate solid heat source or "ash~' formed by decarbonization of the carbon-
containing solid residue of pyrolysis of organic solid waste is employed as a
prime source of heat in the pyrolysis of the comminuted organic solid waste.
As used herein, the term "organic solid wastes" is meunt the pre-
dominantly organic portion derived from a waste source, domestic and/or
industrial in origin~ after gross separation of inorganic constituents such as
iron, aluminium, glass and other values including paper pulp from the waste.
Because of the several comminuting operations attendant to the gross separa-
tion, there appear in the organic solid waste fraction fine particles of glass
and other inorganic constituents that make up at least one percentJ and usual-
ly at least three percent, by weight ~dry basis) of the organic solid waste.
Organic solid wastes containing much larger amounts of glass and other in-
organics may however be treated by the process of the invention, the maximum
content of such materials being dependent upon the maximum heat capacity and
den~ity o the solid waste acceptable to the pyrolysis system. Because these
inorganics, except for some of the fine natural ash content of organic matter,
following decarbonization of the solid effluent of the pyrolysis zone, become
the solid particulate heat source used for p~rolysis, the amount of such in-
organics in tha solid waste may be adjusted to cause the production of a
desired amount of the solid particulate heat source. For instance, the in-
organic content of the sol;d waste may be adjusted upwardly by addition of
materials such as glass, ceramics, refractories, natural or artificial
siliceous or aluminiferrous materials and metals to the solid waste. Con-
versely, organic matter can be added to reduce the percentage inorganic content
; of the waste.
The organic constituents of the organic solid wastes include
cellulosic materials, plastics, rubber stock, and animal waste. Included in
the meaning of "cellulosic materials" are paper, tree trimming and bark, saw-
dust, crop waste, vegetable and fruit processing waste, and the like.
_ g
. ~.
. .
51~
"Plastics" include discarded household plastics, as well as the waste of in-
dustrial polymer-forming and processing operations. "Rubber stock" includes
waste ~yresO "Animal wastes" include household discards, slaughter house
wastes, poultry processing wastes, manure, and the like.
Resulting from a generally sundry mixture of waste materials after
gross separation of inorganic values, the organic solid waste may have, after
drying to the extent required for transport to a pyrolysis reactor, the
following typical analysis:
Table l
Constituent ~ by ~eight
Organîcs 92029
Metals 003~
Glass 1.69
Other Inorganics 2002
~ater 3.62
~ hen the organic solid waste is pyrolyzed there is formed a mixture
of solid carbon-containing residue of pyrolysis which includes the entrained
inorganics, pyrolytic oils and gas. The gas includes carrier gas and gases
r~sulting from pyrolysisO The gas on a dry basis consists primarily of the
oxides of carbon, and hydrogenO
- The carbon~containing solid residue of pyrolysis, which may be
termed ~'char~', typically contains from about lO to about 60 inorganics, but
usually not more than afiout 50% inorganics, the balance being carbonaceous in
nature, the major constituent of which is carbonO If the carbon-containing
solid residue contains less than lO percent inorganics, its inorganic content
may be increased by adding inorganic materials, for instance ceramics, refrac-
tories or metals, to the said solid residue before its decarbonization ~o
produce the solid particulate heat source.
Figures 4, 5 and 6 illustrate the nature of the carbon-contain-
ing solid residue of pyrolysis. It contains combustibles which are
carbonaceous in nature, i.e. contain carbon, hydrogen and oxygen, and it
is of low bulk densîtyO Low bulk density is especially
- 10 -
attributed to the fiberous particle~ shown in ~igure 5
which re~i~t compre~ionO There i~ al~o present
inorganics~ mainly glas~ and metal particle~, which
exi~t predomin~ly a~ separate dis~rete particles and
which may contai~ some entrai~ed carbonO ~he ~i~e~
400 mesh or le~ ee Figure 6), include fine organics
(combustiblea), the fine inorganic~ pre~ent in the ~eea
plu8 the naturally occurring ash of the organie matter
subject to pyroly~i~O ~he inorganic ~ine~ are termed
herein "~ly ash". Despite high inorganics content, bulk
den~ity is only about 3.5 to about 12.5 lbsO/cu.~t.
(56 to 200 kg/m3)~
; When the carbon-containing solid re~idu~ of pyrolysis
i~ decarbonized, the combu~tiblee are eliminated~ ex~ept
~or fly a~h, ~nd bulk density indrea~e~ markedly to
betw~en about 35 and 70 lb~.!cu.ft~ (560 to 1120 kg/m3).
~he re~idue is hard and glas~-li.ke in ~ature and an ideal
lnorganic heat trane~er solid whic~h i~ readily generat0d
:.. ; . . .
fro~ withi~ the prooe~e itself. ~!he inor~ani¢ heat
tranafer solid has a ~int2rlng temperaturs ranging ~ro~
about 1425 to abou~ 17~0F~ (775 to 9250.)9 a ~u~ion
temperatuxe ranging from about 2000 to about 2300~.
(1090 to 1260a.), and a particle and ~keletal de~sity
o~ about 15~ lb~/cuo~t~ (2400 kg/m3) and may be terme~
. "a~h".
~ ulk den~ity will vary with carbo~ conte~-t a~
~hown 1~ ~able 20
.- :
~ '~
.,;'
,, .
' ' , : ' ' .
~076~
~able 2
% Carbon in ~luidized ~ean Particle
'a~ re,
~oll~ ~eat ~'c ~~ ~~
36 3 48 40
51 7 112 50
5.7 35 5~0 100
2.9 38.5 61~ 120
0.6 38 608 1~
A ~imil~r compari~on is shown in Figure 1 which
~ompares t~o inorgan~c fraction~ of dif~erent carbon
~ontent for fluid bed bulk density as a ~unction o~
particle size. ~luid bed den~ity i~ given i~ pound~
mae~ per cubio ~oGt ~bM/~3), u~it~ equivalent to
~ kg/m30 ~rom these considerations7 it is 0vident tbat
bulk density is ma~imized at minimum carbon con~ent. An
inorganic solid heat 30urce havi~g les~ than about 1~%
by wei~ht Garbon i~ particulaxly pre~erred as exhiblting
ma~imum bulk den~ity and ~luldized densityO
~he pyrolytlc oils ~ormed, while varying i~ ~ature
~epenai~ upon the compo8ition of the wa~te material
proc~s~ed and pyroly~i~ conditions employed, are at the
: 3ame tim~ uni~e. ~hey may be characterized a~ o~y~enated,
eomplex organic fluids, typioally, up to 40% and in ~ome
¢asee up to 85% soluble in water9 aoids or ba~e~.
Solubility in polar organic 901vent8 su¢h as glyeerol
i8 limited and the pyrolytic oll~ are relatively in~oluble
in non ~olar organio ~ol~ents, ~uch as ~ie~el oil, oarbon
tetrachloride, pentane~ decane~ ben0ene~ toluene and
he~ane, ~he pyrol~si~ oil, however, can be blended and
76~
mixed with various ~oO6 ~uel oil~ Combu~-tion ~tability
of th~ mixture i~ about the same a~ No.6 ~uel oil alone~
A typical example of an elemental analy~i~ of the
~rolyt~c oil i~ that obtained from the pyrolysi~ of a
waste material ¢ontaining about 70~ cellulo~io~0 ~he
oll thus obtai~ed will contain from about 52 to about 60
carbo~g ~rom about 6 to about 8% hydrogen, from about 1
to about 2~ nitro~en and from about 29 to about 33%
oxygen. ~he empirical formula which best fit~ th~
pyrolytic oil a~alysie i~ C5 ~2~ Spsoifi~ gravitie~
are ~nu~ually high, ra~gin~ from about 1.1 to about 104.
~ he proce~ of thi~ inve~tio~ may be be~t u~d~rstood
with reference to attachad ~igure~ 2 and 3.
With reference to ~igure 2~ the ~rganic ~ol$d wa~te
after gro~ ~eparation of inorganic~, is comminuted to a
si~e i~ which the maximum parti~le dime~io~ i~ le~
than 1 inch (25 mm)~ pre~erably to a ~i~e les~ tha~
aboub 5 me~h, more preferably les~ than about 8 me~h~
~nd dried to make it tran~portable a~ a ~luidized ma~.
~he dried organlo ~olid wa~te i~ transported, u3ing a
oarriar ga~, typically product ga~ from the pro¢e~, to
~yroly~is reactor 10, whcre it iB combine~ with
fluidiæod ~olid ixlor~ani¢ heat source re~ulting from
decarboni~atio~ oî char, fed in ~rertical ri~er 12.
Pyroly~i~ ocour~ i~ flash tran~port pyrolysie reactor lû
w~thin a tempsrature ra~ge from about 600F. (315C. )
to ~omo temperature below the ~i~tering temperatur~ o~
the solid in~rganic heat ~our~e, preferably at a
temperature ranging from 600 to about 1700~. ( 315 to
925~a . ), more preferably fro~ about 800 to about 1400~.
-- 13 --
7~
( ~25 to 760Co ) ~ Flow condition~ are turbulent with
Reynolds number~ bei~g ill excess of 2000, and more
typically in the order of 50,000 or moreO
~ ypical feed to the pyrolysi~ reactor 10 ¢on3i~t~
o:f about 2 to about 20 par-ts by weight of the solid
inorgarL:i c heat ~ource per weight part OI the or~anic
solid wa~te, dependl~g o~ pyroly~i~ temperatureO ~he
preferred range ig îrom about 4 to about 6 part~ by
weig~t of ~olid inorganio heat ~our~e per weight part
of organic ~olid ~a~teO
The carrier ga~ employed to tran~por~ the ~olî~
inorganic heat sourc~ and the commiIluted organic ~olid
- wa~te l;o the pyrol~sis r~actor 10 1~ one v~hioh will not
deleteriou~ly react wlth the products of pyroly~is~ ~he
gas ~tream may9 ho~ever, oontain con~titub~t~ such a~
carbo~ monoxide that will react with the hyarocarb~s
to form other uReful producte. O~ygen i8 to be avoided.
While a to~ally inert carrier ~;a~ uch as nitro~ e:ll, ca2l
`; be u~ed, the pre~erred ~a~ i~ thel ga~ atream formed ~rom
pyrolysis.
Typlcally, the ~mount of the ~as employed i~ o~ly
~u~fici~nt to tran~port the solid inor~ani~ heat ~ource
and the orga~ic ~olid wasta a~ a fluidized mass to the
pyrol~si0 reactor 10. Ge~rally, a solids-to-ga~ wei~ht
ratio of about 1 to about 4 i~ employed. All that io
: critical i~ the mai~t~nance of turbulent ~lo~ condition~
a~d free solid~ trangport. Residence time in the p~roly~is
%one i~ ~hort and le~ than 1 minute, preferably frQm
about Ool to about 2 ~eoond3 and more typically from
about 0.2 to about 005 ~e~ondO
- 14 -
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,, :
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7~5~
E~sentially all of the heat re~uired Por p~roly~i~
i~ provided by the ~olid inorga~Lic heat source a~Ld
trans~erred to the organic ~olid waste by ~olid~ to-
~olids contact a~ well a3 solid~-to-gas-to-solid~ heat
transferO Velocitie~ range from about 10 to about
200 ft./~ec (0.3 to 61m/~eo)0
~ he effluent from the pyrolysi~ reactor 10 i9
compo~ed of the solid i~orga~Lic heat source, the ~olid
carbon-containing product of pyrolysl~, a corLden~able
pyrolyti~ oil, water a~ ste~, a~Ld the normally gaseous
con~tituent~. The effluent passes from the pyroly~is
re~¢tor 10 to high efii~iency product cycloxL~8 14 a~Ld
16. C~clone 14 serve~ primarily to ~sparate the solid
i~organlo heat 30urce and larger particles o~ the
carbon-containixLg ~olid residue o~' pyrolysi~ from the
pyroly~i~ reacto~ e~fluent wh~rea~ cyclone 16 ~eparate~
ixtermediate to ~irLe partioles of the earbon~contalning
~olid residue of pyroly3is and finer solid inorg~.Lic
h~at ~our~ particles. ~he balano~ of th~ ~i~e carborL-
20 CQYLtaini~Lg ~olid resldue o~ pyroly~i~g a~ product, i~~eparated i~ fin~ CyClOXLe 18 ~or collectioxL i~ hopper
~0~ ~he ~a~ and condensa~ls pyroly-tic oils ar~ pa~ed
to ~e¢overy zo~eæ, not showrL. ~he in~rga~io heat ~ource
~nd carbon-¢sntai~in~ solid residue ~ pyroly~is oolle~t
in stripper 22 which is mai~tained ln a ~luidized 3tate
by the upward ~low of produ¢t ga~ a~ an aeratio~ ga~0
Stxipper 22 contains a scree~ 24 to re~ect ¢li~ker~
which gra~itate to~aras the base of the stripper a~d by
mechanical action are ev~ntually reco~ered from th~
~y~temO
- 15 -
. .
765~
More importantly, the fluidization gas remo~es
pyrolytlc oil~ from the par~icle~ a~d by it~ central
po~ition in con~t~cted zon~ 25 tends ~Q sample particles
of a~erage nompositio~ i~ stripper 220 Other locations
would tend to ~ample predomi~a~tly the inorga~ic heat
~ource or carbon-containing solid residue o~ pyrolysi~
~owever, for the conti~gency thQt the caxbon-containing
eolid residue of pyroly3is ~ormed is fine and will not
blend well with the inorgani~ heat source ~o a3 to make
it ~uel lea~, there is provided a ~econdary withdrawal
tubc 27 cooperati~g with feed line 29 and val~e 31 to
remove ~ine parti¢le~ of -the carbon-containing eolid
re~idue o~ pyrolysi~ along with inorganio heat ~ource
~rom stripper 22 for feed to burner 24.
~he expanded seotion ~3 of the stripp~r enable~ the
majority of particles exitsd by the aeratlon gas to
retuxn to the ma~. Bypa~8 26 re;Lea~es the fluidi~ation
ga~ ~rom ~trip~er 22 carrying with it any fines
entrained in the ga~ ~pace above the colleoted particle~.
The eold solid inorganl¢ heat ~ouree and carbo~-
oontaining solid re~idue o~ pyrol~sis maintained in a
semi-fl~idized ~tate by the use o~ product gae ~ an
aeration gas enter fl~ldized lag ox ~andp~pe 28, p~5~
: through ~lide ~alve 30, and are transported along ri3er
32 to burner 34. ~he gas employed for tra~port i~
preferably air~
Air is fed to bux~er 34 in proportio~ to combu~t
at least 80~o~ preferably lOO~o~ of the oarbon contain2d
in the carbon-contai~ing solid residue of pyrolysis.
He~t of combu~tion ~erve~ ta preh2at the cold ~olid
- 16 ;
~07G5~
inorganic heat source to a sultable temperature ~or
retur~ to p~roly~i~ reactor 10 and ge~erates from the
carbon-containing ~olid residue of pyroly~is additlonal
~olid inorganic heat source~ ~o control the temperatuxe
and pre~e~t agglomeration or ~intering of ~olid inorganlc
heat ~ource, water is introdu¢ed with the air a~ a
uniform ~og. ~hs u~e of a ~og as oppo~ed to a spray
prevent3 localized quenohing and makes water more
available for reaction with carbo~. Residence time ln
burner 30 i~ suf~icient for the desired degree of
combu3tlo~ to QCCUr and typically ~rom 0.4 to 3 ~econd~,
preferably 0.5 to 1 ~econd. Typi~al tsmperatures ranga
from about 1250 to ab~ut 1650F. (675 to 900~C.)
The ~lue ga~ and particulate ~olid inorganic heat
~ource lsave burner 34 and pa~ through low efficien~y
heater eyclone~ 35 and 38 which recover particle~ in
the paxticle ~ize range from 10 t~ 2000 micron~,
pxeferably from ~0 to about 600 micrvns. Some fly a~h
and fine~ are collected downstrea~ to yield high
tamperature ~lue gae which i~ ve~ted a~ter use o~ ito
sen~ible heat in the overall procees. ~he reoovered
~olid inorgani~ heat ~ouroe colle¢t~ in a ~urg~ hopper
40 maintai~ed, b~ ulation, at a temperature abo~t
equal to the temperature in burner 34. Bypa~ 42 i~ ~
provlded to return ~ine~ entrained in ths fluldi~i~g ga~
e~tcring surge hoppar 40 back to cyclone 36. If
combu~tion in ¢har burner 34 i8 incomplete, the
decarboni~atio~ i~ completed9 i~e. to redu~e carbon
content to lQ% or lees, in ~urge hopper 40 by i~tro-
ductio~ o~ air a~ the aeration or ~luidizing ga~ and
-- 17 --
. :
:
7 6 ~
water to control temperature.
~ he particles of the solid inorganic heat source
which collect i~ surga hopper 40 may vary ln particle
size from about 2000 microns or more~ to leæs than 10
micron~ ~o ensure return of particles of a de~ired
~i~e ra~ge to reactor 10 requires continuouE3 or
intermitte~t ad~uetments in particle ~izeO
~ o enable adju~tment of partiele size in hopper 40,
there ls employed an auxiliary operation keyed to excees
solid inorganic heat sour¢e re¢overyO
The eolid inorganic heat ~our¢e ia generated i~ a
quantity in ex~eE3E~ o~ that required for recy~le and i~
withdrawn through ~iphon tube 44, pa~sed to qu~nch
hopper 46 and finally to produot h~pper 480
If the circulating particleE~ tend to become ~oo
fine~ the bed level in surge hopper 40 iE3 allowed to
ri~e to increa~e antrainment of t]~ ~ine~ by cyclone~
36 and 38 to conce~trate the larger particleE~ in E~urge
hopper 40. ~e an alternati~e, a e3mall amou~t o~ gas
2~ ca~ be i~eeted into the bottom o$ cyclone 38 t~ di~turb
itB operatio~ to mi~imize reoovery o~ e particleeO
Co~versely, i~ the particle~ b~come too eoar~e,
tho produot inorganics contained in ~urge hopper 4Q ie
with~rawn ~y ~cr~e~ed $iphon tube 44 at a larg~ rate
and elutriated to return fi~e~ t~ ~urge hopper 40. ~hle
concentrates the fine particle~ in ~urge hopper 40 and
reduce~ average particle size to about 50 mierons.
Exca~s inorganice are co~tinuou~ly withdrawn a~ product.
~hi~ control lead~ to the preferred operatio~ wh0rein
the inor~anic heat source contain~ les~ than 50~ fly
~ 18 -
-
~7 ~
a~h, the retained ~ly ash having a particle size greater
than about 10 microns. As a whole, the inorganio ~olid
source of heat ha~ a particle ~ize distribution in which
at lea~t 50~ of the solld h~ve a particle size greater
than about 37 microns (400 mesh)~
The ~luidiæed ~olid inorganic heat source required
or pyrolysis i~ pas~ed by aerated leg or standpipe 50
through slide valve 52 and e~trai~ed by transport gas,
preferably the product ga~, ~nd pas~ed through riser 12
to pyrolysis rea~tor 10 to complete the loop cycleO
In the ~peration of the apparatu~ depicted in
~igure 1, the standpipes 28 a~d 50 form ~luidized legs
where the parti¢les are retained at a reduced bulk
de~eity, generally 70% o~ settled bulk density. ~o
; achieve the proper ba~e leg pressure in exce~ o~
operating pre~sures in pyrolysis reactor 10 and char
.~ bur~er ~4 and to pre~ent back~low of materials,
re~uires a leg o~ a height determined by the preæsure~
rsquirea and the density of it~ fluidized ~olids~
20 ~his i~ most critical i~ leg 500 As a con~equenco o~ :
uaing the decarbonized 301id residue o~ pyr~ly~i~ ae
¢ompared to the carbon-containing ~olid re~idue itæelf
:~ . a~ the heat souree, leg height can effec~vely be
~; redueedO ~he reduction in h~i~ht ia critical ~or some
i~stallations to meet design code re~trictia~ for
chemical comple~es0 There i~ also a si~nific~nt
reduction i~ plan~ coct because of the ~aving~ i~
~upport~ ~or the leg and the vessels above lt.
~ominally, le~ pressures at the val~es are abQut 1.5
~0 to 205 times the operat1~g pre~sure o~ the reactor or
", -- 19 --
. .
' ' . ................................................................ .
,. . . .
~7 ~ 5
burner served by the leg.
The use of the solid inorganic heat ~ource i~ more
reliable i~ the cont~ol of particle siæe tha~ carbon-
containing solid residue of pyrolysis. ~he latter i8
readily ~ubject to attrition, breaking dow~ into
particle~ of ~ine ~ize, contami~ating the pyrolytic oil
and ga~ ~tre~m~. ~he ~olid inorganiG source a~
obtained by ~u~stantial de~arbonization 3~ the carbon-
containing solid product o~ pyrolysis by ~ontrast, iæ
relatively attritlo~ free, subject to preci~e control
over the rangs o~ particle ~ize employed i~ the
pyrolysi~ reactor, ~impli~yi~g greatly the ~verall
operationO
In addition, since e~sentiall,y complete combu~tion
of char may occur in char burner 34~ the carbo~ mono~ide
content of the gas stream can be ~3ffectively co~trolled~
~ igure 3 represent~ a~ alter~natiYe to the process
depicted in ~igure 20
~ ith refere~ce to ~igure 3, again the organic solid
wa~te i~ transported and combined with the inorgani~
solid heat sourc~ a~d the carrier gaæ i~ transp~rt
pyroly~ls re~c~or 10. After pyrolysi~ the pro~uct~
are pa~3ed through high e~iciency product cyclonee 14
and 16 for recovery of ~pent ~olid inorganic heat source
and the carbon-containi~g ~olid product of pyroly~
~he fine~ are ~ep~rated in cyclo~e 18 ~or ~torage in
hopper 2Q. Bypa 8 269 as i~ pre~iou~ly described, permit~
the ~ine~ entrained in ~tripper 22 to be retur~ed to the
product line.
In thi~ in~tance~ to avoid the leg 28, the
- 20 -
6 5~
particulate mixture i~ fed by low tsmperature rotary
valve 52 to burner 34 where the carbo~ containing ~olid
re~idue of pyrolysis i~ decarbonized ~or pa~sage to low
ef~iciency cyclone 54 where the solid inorganic heat
source in the particle 3i~e oY ~rom about lO to about
2000microns, preferably from 20 to about 100 micxo~ i~
reGovered for return to the pyroly~is reaotor usi~g leg ~,
50 and riser or feed li~e 12. ~he fi~e inorganic
partiole~ or ~ly a~h are recovered in cyclone 56, ~nd
l~ the flue gas after recovery of sensible heat vented to
the atmo~phere.
I~ carrying out the proc~e~ ~f this inYe~tion, it
will be appreciated that since the solid inorga~ic heat
~ource i9 not available for start-up conditions,
another ~ource of heat i~ required. ~hi3 may conveniently
take the form o~ fine gla3~ commi~uted within the process 7
or sand. Suoh a starting mate:rial 9 how~ver, onoe the
proc~s i~ in o~ratio~, will eve~tually be ~upplanted
in t,he line3 by the solid inorganic h~at sourGe for~ed
by decarbonizatio~ o~ the oarbon-containing solid
residue ~f pyroly~ie~
It will also be apprsciated that where it i~
de~lred t~ upgrads the quality of the pyrolytic oil
or heat ~lue of the product gas from the pyroly~is
oparation, there ma~ be includ~d in the tran~p~rt gas
reactive con3tltuent~ or heat supplsment constituents
which react with the pyrolytic oil in the product oil
and~or gaeO
As indicated7 however, the constituent~ mu~t not
deleteriou~ly react with the products o~ pyroly~i~ 7
- 21 -
. ., ' '
65~L~
but are added to upgrade their value.
With reference again to Figure~ 4~ 57 and 6, the
~ature of the carbon-containing solid re~idue of
pyrolysis is a ~eterogenous mixture o~ particulate
inorganlc~ from an origi~ different from the organic3
which underwent pyroly~i~ and carbonaGeous particle~
re~ulting from pyroly~is. ~o at least a su~stantial
degree the inorganics are unchangsd by pyrolysi~. ~he
organi~ i~ addition to formation of the pyrolytic products
may relea~e otherwise nonseparable, homogenou~l~ contained
inorganic filter~ such as clay~ and the like. These ~i~e
particle~ appear as fly ash (~ee Figure 6) and to a ~ajor
e~tent are removed from the system following combustio~
or decarbonization. Duri~g decarboniæatio~, the
combustibles are sub~tantially eliminated es~entiall~
leaving only the inorganics which were ~ontained in tha
organlc waste portion or released as a con3eque~ce o~
pyrolysis or combu~tion. It is the inorganics which
~remain which serve a~ the inorganic 3~1id heat ~ource
; 20 o~ thls invention. It is becaus~ ~ the required preeence
o~ the i~o:rganic3, that the carbon-Gontaining solid
re~idue of pyroly3i~ differs from ch~r as it i~ u~derst~od
:~ in the normal sense~ It i~ through the pre~enee of
i~organlcs that a heat source superior to oh~r can be
generated îrom the organio wa~te~ proce~edO
Once prepared fo~ recycle aB the heat source, a
preferred ~peci~i~atlo~, the fly ash aonte~t be les~ th~n
about 50% by weight, and then the retained fly a~h have
a particle ~ize greater than 10 micron~. Moreover, the
inorgani~ solid ~ourc~ of heat should have a particle
_ 22 -
, . :
~ 6Si~L
size distribution in whlch at least 50~ of the
paIticles are of a ~ize greater than 37 mi¢ron30
~ he following egample is illustrative of the
process of this invention.
~XAMP~E
Organic solid waste resulting from the treatment
o~ mu~ipal ~olid waste to remove the inorganic
constltuents is dried and comminuted to a particle
size less than 8 me~h. ~he vrga~ic solid waste having
the compositio~ show~ i~ ~able 3 1~ ~ed at a rate of
9491.4 pOUlla9 ~!~505-3 kg) per hour to a pyrolysie
reaetor using as the ~arrier gas a product gas ~ the
compositio~ shown i~ Table 4.
Component Wt ~0
Organic~ 92.29
Metal~ 0.38
Gl~s~ 1.69
Inorgani¢~ 1.40
Other Soli~0~62
~ater 3.62
~L
~g~
~2S 0031
.
~2 0.86
~2 32.42
CO 31.1
~2 10.~
~i 5.13
C2H4 2.56 ..
- 23 -
.
~7~5~
C2~6 008
0.88
~0 15.28
~tal 100.00
Average ~olecular Weight 28.43
~ he carrier gas has a temperature of 500F~ (260Co)
and the organie solids waste to carrier ga~ weight rat1o
is 2Ø ~h~ nominal ~olid~ temp2rature is 100~. (37C.)
Simultaneously, 49~831 pounde (22603 k~) per hour
of a particulate solid inorga~ic heat æouroe foxmed ~rom
decarbo~izatio~ of the carbon-containing ~olid re~idue
of pyroly~ tran~ported along by about 480 pOWld9
(218 kg) per hour of the carrier ga~ to the pyroly~i~
reactor. Heat ~ource temperature i5 about 1~50F. (730C.)o
~he average exit tempera~ure i~ t'he pyrolysi~ reactor i~
950~. (510a~)o O~erati~g pressure is 1005 p~ig
(543 mm~g). Averaee residence time i3 0.6 ~e¢ond.
After pyrolysisg the di~charge compositio~ ~rom
reactor 1~ is 129883.6 po~nd~ (5844 kg) per hour o~
gas i~cluding 39659 pou~ds (1660 kg) per hour of
.; py~dytic oil, 1,760.5 pou~ds ~798.56 k~) per hour
- water, 17829.5 po~d~ (829.86 kg) o~ the carbon-
oontai~lng ~olid re~idue o~ pyrolysis, and the total
i~organic ~olid heat ~ource ~ed to the pyroly~ie r~actorO
`~ lhe efflue~t is pas~ed to a first product cyclone ~hich
~eparates 51,120 pound~ (23188 kg) per hour of ~olid~
from the gas stream a~d a 3econd cyclo~e which s~parate~
269 pound~ (122 kg) per hour of ~olid~ from the gas
. .
~0 streamc lhe balancc of the gas ~tream adva~ces to fine
~ ~4 ~
cyclone which separate~ 207 pounde (94 kg) per hour o~
e~entially fine carbon-containing solid residue of
pyroly~i~, a~ product from the gas stream. After
quench qeparation of pyrolytic oil, residual ga~ stream
at a rate o~ 13,419 pound~ (6086.9 kg~ per hour i~
made available as a heating gas and ga3 for the process~
~he exce~s i9 flared to the atmo3phere. lhe composition
of the pyrolytic oil and carbon ~ontaining solid reeidue
of pyrolysi~ i~ shown in Table 5.
D
:j Carbon ~onb~ni~
~~~ Oi
Carbon 48.8 57.0
~ydrogen 3.~ 7.7
~itrogen lol 1.1
Sulphur 0.2 002
Chlori~ O.3 0o2
A~h 33~0 0,2
.. 20 Oxygen 13.3 3306
~he physical pr~pertles and pa~ticle ~i~e
dietr~butio~ of the inorganic ~ource and carbon
cotaini~g solid ra~idue o~ pyroly~i~ fed to the product
cyclone~ i~ show~ in ~able 6.
Of the mixture of solid inorganic heat ~our¢e a~d
carbon-containing solid reoidue of pyroly~is ~olle~ted ..
in the stripper, particulat~ solid~ are remo~ed at a
rate of 51,388 pou~d~ (233~0 kg) p~r hour, using a~ the
prime tran~port ga~ air~ and fe~ to the burner 30~ Air
at the rate of 2~328 ~tandard cubic feet (65.~3m3~ per
- 25 -
3L~7~
minute J and water at the rate of 100 standard Gubic feet(2.83m3) per minute, as a ~uenchg are combined with the
solids in burner 30O ~ecarbonizatio~ of the carbon
containi~g solid residue of pyrolysis by oxidation occurs
at an average burner temperature of 1350Ft (730C.)~
~he re~ultant solid inorganic heat source and gases are
pa~sed to a fir~t burner cyclone which separate~ ~olid~ at
the rate o~ 49,914 pound~ (22641 kg) per hour and then to
a second bur~er cy~lone whi¢h re¢eiveB solids at the rate
of 306 pound~ (139 kg) per houxO Re~idual ga~ stream
containing 120 pound~ ~54.4 kg~ per hour of fines i8
pas~ed to a fineB accumulator. ~he solld inGrganic heat
source colleoted in the ~torage hopper is withdrawn ~g
product at a net recovery rate of 84 pound~ (38.1 kg) per
hour4 In this operation, the flue ga~ from burner 30 is
employed to preheat the air required for combustion. In
thi~ in~ta~ce, the air is heated to a temperature of 650~.
(345C~) by indirect heat exchange with flue ga~ following
in which the flue gas iB vented to the atmo~phere. In the
operation, nomi~al re~ide~ee time i~ the pyrolysis reactor
i~ 0.3 ~e~ond, and in char burner 0.~ ~eoo~d O Average
re~idence time of ~olid~ in stripper 22 iæ 3 minutes and
the sur~e hopper 40, 5.5. mi~ute~
~he physical properties and parti~le ~ize of the
solids lea~ing the pyrolysis reactor are shown i~ ~able :~:
6. About gg"96% of the particles are removed. The
inor~anic heat ~our¢e compo~itio~ i~ that fed to the
pyrolysi~ reactor.
'
:
-- 2
',
~able 6
Inorganic Carbon Containin~
--t 8~13lr--D---
Source
Compo~ition, wt. % g6.5 3.5
Particle den3it~,~ 3 150.0 (2400) 112.0 (1792
lbs/ft (kg/m )
Skeletal density9
lbs/~t3 (kg/m~ 150.0 (2400) 150.0 (2400)
Settled bulk den~it~ .
lb~/ft3 (kg/m~ 58 (928) 12.5 (200)
'' ' . Size Distribution, wt %
, 19 010 mieron~ 1.2 34.0
: 1020 mierons 7.8 24~0
2040 micro~s 13.0 1970
4080 micro~ 16.0 10.0
80120 miero~ 18.0 4.0
~, 12016~ micro~s 13.0 2.0
.~ 160200 mieron~ 10.0 1.5
290400 micron~ 15~0 2.5
~,. 400600 mieron~ 2,5 1~2
: 6001000 mieron~ 2.0 1.1
2010002000 mierons 1.5. 0.7
. . .
2000 + - '
"''
, .
. '
....
, . . .
.
,
: 30
, .
. . .
.: :
', ' ,: . . . .~ .
i' . ', : ~ , . ..
