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Патент USA US3096280

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July 2, 1963
3,096,273
J. HANISIAN ET AL
RECOVERY OF HYDROCARBONS
Filed Aug. 5. 1960
1m:<0
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INVENTORS
JOHN HANISIAN
EDWARD H. LIGHTCAP
J.H.Gllwm,
2am n. W
ATTORNEYS
Unitedw States Patent 0 Nice
3,096,273
Patented July 2, 1963
2
1
3,096,273
_,
containing the minor portion of C14 and heavier hydro
.
RECOVERY OF HYDROCARBONS
John Hanisian, Garden City, N.Y., and Edward H.
Lightcap, Stratford, N.J., assignors to The» M. W. Kel
logg Company, Jersey City, NJ., a corporation of Del
aware
Filed Aug. 5, 1960, Ser. No. 47,728
12 Claims. (Cl. 208—101)
This invention relates to the separation and recovery
of hydrocarbons. In a particular aspect, it relates to the
recovery of relatively low boiling hydrocarbons from ad
carbons present in the scrubbed-gas fraction and some
C13 and lighter hydrocarbons, separating C13 and lighter
hydrocarbons from at least a portion of the hydrocarbon
condensate separated after the cooling and partial con
densing step, and recovering C13 and lighter hydrocarbons
uncondensed from the cooling and partial condensing step
and as separated from the liquid fraction and the hydro
carbon condensate.
For a better understanding of the invention, reference
is had to the following detailed discussion and description
read in conjunction with the accompanying drawing which
is a diagrammatic illustration in elevation of equipment
suitable for practicing a preferred embodiment of the in
ous unsaturated hydrocarbons for use as starting materials 15 vention.
!In the drawing a vaporized light naphtha feed is intro
in the manufacture of plastics and the like, various hydro
duced to the process at 300° F. and at 79 p.s.i.g. through
carbon feed stocks, such as ethane, propane and naphtha,
conduit 11. An equal weight proportion of steam is intro
are pyrolyzed, i.e., subjected brie?y to high temperatures
duced through'conduit 12 and admixed with the naphtha
in the presence of steam, to produce an e?iuent of pyrolysis
containing a spectrum of components ranging from hydro 20 feed in conduit 11. vThe steam-hydrocarbon admixture
is introduced to pyrolysis furnace 13 wherein the admix
gen, methane, ethylene, etc., to high boiling hydrocarbons,
‘ture is indirectly heated to about 145 0° F. so as to pyrolyze
tarry substances and solids. Thus, in addition to ethylene,
mixture with relatively high boiling hydrocarbons.
"In the production of ethylene and other normally gase
propylene and butadiene, the pyrolysis ef?uent contains
a gasoline fraction, i.e., a fraction boiling generally in
‘the hydrocarbon and produce ethylene, propylene, butadi
ene, gasoline-boiling range materials, C14, and heavier hy
the C5—C13 range, which is useful as a motor fuel. Re 25 drocarbons including tarry substances and solids. Heat
for pyrolysis is generated by the combustion of fuel in
gardless of the method used to separately recover indi
furnace 13. The steam which is introduced to furnace 13
vidual constituents and groups of constituents of relatively
,with the hydrocarbon feed reduces carbon deposition
narrow boiling range from a pyrolysis e?iuent of wide
attendant to pyrolytic cracking. The hot pyrolysis ef?uent
boiling range, it is advantageous to ?rst remove substan
tially all of the solids and the C14 and heavier hydro 30 is withdrawn from furnace 13 through conduit 14 and
carbons which include tarry substances from the e?iuent
passes immediately to a quench boiler 16 wherein the
than about C13, which under the in?uence of heat or pres
sure or both readily tend to polymerize or otherwise de
, substantial proportions of the heat in the pyrolysis efiiuent
,by generation of. steam. In this regard, water is intro~
duced through a conduit 17 into a steam drum 18 from
ef?uent is cooled to about 750° F. by indirect heat ex
in order to avoid such accumulation of solid deposits in
change with boiling water. The partial cooling of the
subsequent equipment as would force periodic interruption
pyrolysis e?iuent in boiler 16 provides both for quenching
of the process for cleaning. As used herein, tarry sub
stances include high molecular weight polymeric materials 35 the e?iuent to below reaction temperature, thereby
,“freezing” the e?luent composition, and for recovery of
and other hydrocarbons in the pyrolysis effluent, heavier
teriorate forming fouling deposits.
It is therefore an object of the invention to provide a 40 which a portion passes through conduit 19 to the quench
process for recovering C13 and lighter hydrocarbons from
boiler 16 wherein steam is generated and returned through
conduit 21 to drum 18. Additional steam is produced by
passing water from drum 18 through a conduit 22 to
hydrocarbons.
It is another object of the invention to provide a process 45 indirect heat exchange coils located in the ?ue gas exhaust
section of furnace 13. Steam thus generated is returned
for the removal of entrained solids from the e?luent of a
from furnace 13 to drum 18 via conduit 23. The total
pyrolysis process.
steam make of drum 18 which is at 400 p.s.i.g. is with
Still another object of the invention is to provide a
drawn through a conduit 24.
process for quenching the effluent of a pyrolysis process.
Pyrolyses, such as the one described, are preferably
A further object of the invention is to provide a process
conducted
at maximum temperatures between about 11000
for separating C13 and lighter hydrocarbons from the
F. and about 1600° F. and at relatively low superatmos
effluent of a pyrolysis process.
'
pheric pressures, normally between about 5 andlOO p.s.i.g.
A still further object of the invention is to provide a‘
These
conditions are normally used where the pyrolysis is
process for quenching and cleaning the effluent of a py
a vaporous mixture containing the same, C14 and heavier
rolysis process and for recovery of enhanced yields of C13 55 ~conducted for the production of ethylene and other nor
‘mally gaseous unsaturated hydrocarbons including ole?ns
and lighter hydrocarbons therefrom.
and vdiole?ns, although some variation can of course be
Various other objects and advantages of the invention
made.
will appear from the following detailed discussion and
The intermediate temperature to which the pyrolysis
description.
effluent is cooled in quench boiler 16 is preferably between
The above objects are accomplished in accordance with
about 500° F. and about 900° F. While it is desirable to
the invention by the process which comprises contacting a
C14 and heavier hydrocarbons in a scrubbing zone with a
recover as much heat as possible in the quench boiler so
as to generate steam, the lower temperature limit of about
scrubbing liquid predominantly containing hydrocarbons
500° F. should be carefully observed, because below
vaporous mixture containing C13 and lighter hydro-carbons,
heavier than C13, separating a scrubbed-gas fraction con 65 about this temperature the tarry substances which are
taining a major portion of the C13 and lighter hydrocar
present in the pyrolysis effluent tend to condense'on equip
bons and a minor portion of the C14 and heavier hydro
carbons and a liquid fraction containing a major portion
ment surfaces, gradually build up, and eventually render
of the ‘C14 and heavier hydrocarbons and a minor portion
the equipment inoperative, necessitating costly shutdowns
for cleaning.
.
of the C13 and lighter hydrocarbons, separating C13 and 70 The partially cooled pyrolysis effluent from quench
lighter hydrocarbons from at least a portion of the liquid
boiler 16 is passed through conduit 26 at a rate of 169,907
fraction, cooling and partially condensing the scrubbed
lbs. hydrocarbon/hr. to a gas scrubber 27 operated at
gas fraction so as to produce a hydrocarbon condensate
3,096,273
'
4
3
about 13 p.s.i.g. The feed to scrubber 27 in conduit 26
has the composition shown in Table I below:
TABLE I
carbons, tarry substances and solids and a minor portion
of the C13 and lighter hydrocarbons absorbed from the
pyrolysis effluent. The Warm liquid fraction is withdrawn
Pyrolysis Effluent in Conduit 26
through conduit 28 at a rate of 73,280 barrels per stream
day and ?ltered in ?lters 31 and 32 so as to separate the
larger particles of entrained solids. Filter 29‘ is cleaned
Component
Mol percent
Hydrogen .._
_
Acetylene
Ethylene
while ?lters 31 and 312 are in operation, enabling continu
16.4
Methane ______________________________ .._
____ __
__
Ethane ______________________________ __
Methyl acetylene _____________________ __
Propadiene ___________________________ .._
Propylene _..
ous ?ltration. The appropriate isolating valves are not
0.5
shown. The warm liquid now free of at least the larger
2.8.9 10 entrained solids is passed from ?lters 31 and 32 through
conduit 33 by pump 34. A major portion of the warm
7.8
liquid fraction is passed through a conduit 43 to an indi~
0.3
22.6
rect heat exchanger 44. In exchanger 44 the liquid frac
tion which is at about 350° F. is substantially cooled by in
0.1
10.6
15
direct heat exchange with liquid introduced into exchanger
Propane _____________________________ __
0.3
Butadiene ____________________________ __
1.9
44 through conduit 46 .and withdrawn through conduit 47.
Butylenes ____________________________ .._
3 .0
The material in conduits '46 and 47 which is a propane
_
0.1
C5’s _________________________________ .._
Butanes
2.5
Cs’S
C-fs ___
___
_-_
-.--
_-__
____ __
3.5
_
0.6
C9’s—C13"s ____________________________ __
C878
0.4
C14’s and heavier _________ __-_ _________ __
0.1
fraction from the lower portion of a propane-propylene
fractionator (not shown) in the recovery process subse
20 quent to the instant process is partially vaporized in ex
changer 44. Warm scrubbing liquid, as a circulating heat
carrier medium, can be used of course in indirect heat ex
change to supply heat at any convenient point to the pro-d
uct gas, obtained from the instant process, for and in the
25
100.0
In gas scrubber 27 feed gas from conduit 26 is directly
contacted countercurrently with a relatively cold scrub
bing liquid predominantly containing hydrocarbons heav
ier than C13. The scrubbing liquid is obtained and intro
duced as hereinafter described. Scrubber 27 contains suit
course of its subsequent fractionation. By virtue of the
heat exchanges done in quench boiler 16 and exchanger
44, substantially all of the useful heat originally in the
pyrolysis e?luent in conduit 14 is recovered. The now
cooled major portion of the warm liquid fraction is passed
30 from exchanger 44 through conduit 48 at a rate of 72,500
barrels per stream day, further cooled to about 175° F.
by indirect heat exchange with cooling water in exchanger
able baf?es, etc., by means of which efficient vapor-liquid
49
and split into three streams in conduits 5’1, 52, and 53,
contact is achieved. The cold scrubbing liquid substan
tially cools the effluent introduced through conduit 26 to 35 having valves 54, 56 and 57, respectively, and returned to
the scrubber 27 as a major portion or‘ the aforesaid rela
about 225° F., scrubs out substantial amounts of the C14
tively cold scrubbing liquid. Conduits 511, 52 and 53 are
and heavier hydrocarbons including substantially all of
provided to permit control of the point or points in the
the tarry substances and solids in the e?luent. The tem
scrubber 27 to which the scrubbing liquid is introduced.
perature to which the pyrolysis e?luent is cooled in scrub
This control assures e?icient gas-liquid contacting.
ber 27 is important. The effluent should be cooled ‘as ex 40
Control of the composition of the circulating scrubbing
tensively as possible from the standpoint of reducing ex
liquid is obtained vby supplying a make-up gas oil stream,
traneous cooling requirements and of transferring pyroly
free of tarry substances, through conduit 58 to the cycled
sis heat to the scrubbing liquid which, ‘as a circulating me
scrubbing
liquid in conduit 53, and by withdrawing from
dium, is subsequently and e?iciently used to supply heat
to the e?luent in the course of its fractionation. At the 45 the system a minor portion of the warm liquid fraction
through conduit 35. Such make-up and purge results in
same time it is necessary to avoid condensing any of the
low
concentrations of tarry substances in the scrubbing
steam present in the e?luent during its passage through
liquid and reduces the total time that such heat-sensitive
scrubber 27 because steam condensate, if present, and the
materials present in the scrubbing liquid are subjected to
tarry substances in the scrubbing liquid would tend to
high temperature. In this way, interruption of operation
emulsify and thereby present a difficult separation prob 50 for
the purpose of removing fouling deposits formed by
lem. Accordingly, the scrubbed-gas effluent from scrub
deterioration of heat-sensitive materials is avoided.
ber 27 should be at a temperature no lower than its water
The extraneous scrubbing liquid supplied in accordance
dew point which, at the steam to hydrocarbon ratios and
with the invention can be any hydrocarbon or mixture of
pressures normally used in pyrolysis, is between about
hydrocarbon which is a free-?owing liquid at the condi
170° F. and about 260° F.
55 tions of operation; which is free of tarry substances so
The scrubbing method described is quite e?icient, par
that the ‘high temperatures encountered will not cause sub
ticularly from the standpoint of tar and solids removal,
stantial cracking, polymerization or other deterioration;
and of cooling the pyrolysis e?iuent while avoiding an oil
and which is preferably relatively high boiling so ‘as to
water emulsion problem. However, the scrubbing proc
permit continuous circulation without loss through vapor
ess described tends to produce equilibrium concentrations
ization. Such hydrocarbon liquids are those boiling gen
of all the components in the system in both the liquid
erally in the gas oil range. In the example here given, the
and vapor phases. Thus, a certain portion ‘of the C13 and
gas oil used is introduced at a rate of 1000 barrels per
lighter hydrocarbons in the effluent will be lost from the
stream day and contains principally C14 and heavier hy
vaporous fraction by absorption into the liquid fraction.
Similarly, a certain portion of the C14 and heavier hydro 65 drocarbons, having an average boiling point of 544° F.
The initial temperature of the circulated scrubbing liquid
carbons including tarry substances will appear in the
should be below the temperature to which the scrubbed
scrubbed-gas fraction. As will "appear hereinafter, these
gas fraction is to be cooled, preferably between about
disadvantages are also overcome by the process of this
10° F. and 50° F. below the temperature of the scrubbed
invention.
A gas-liquid separation occurs in scrubber 27. The 70 gas fraction for e?icient heat transfer. The temperature
of the warm liquid fraction is in?uenced by the rate of
cooled scrubbed-gas fraction contains steam, a major por
circulation of scrubbing liquid, which rate should ‘be main
tion of the C13 and lighter hydrocarbons originally pres
tained high enough to keep the temperature of the warm
ent in the pyrolysis e?luent and a minor portion of the
liquid fraction below those at which appreciable vapor
C14 and heavier hydrocarbons. The warm liquid fraction
ization or deterioration of the scrubbing liquid would
contains a major portion of the C14 and heavier hydro 75 result.
3,096,273
6
pyrolysis e?iuent.
A minor portion of the warm liquid fraction withdrawn
through conduit 33 and pump 34 is passed, as purge,
through conduit 35 to ?lters 36 and 37, arranged for alter
It hasbeen cooled and cleaned of
entrained solids and heavy hydrocarbons which might
prevent fouling problems in the subsequent recovery
nating operation, wherein substantially all of the entrained
solids are removed. Complete separation of entrained
solids is not practiced in ?lters 29, 31 and 32 because the
passages in the circulating scrubbing system are large and
no problems arise from the presence therein of relatively
small particles of entrained solids. It is, however, neces
sary for the minor portion passing in conduit 35 to be
substantially freed of entrained solids in view of the sub
sequent treatment of this minor portion. Use of ?lters
36 and 37 avoids, therefore, the need for ?ne ?ltration
of the whole circulating scrubbing liquid in ?lters 29, 31
and 32. The ?ltered minor portion is passed in conduit 15
process, and therefore, is in a suitable condition to be
treated under high pressures and low temperatures for
the recovery of ethylene, propylene, butadiene, gasoline,
etc. The product in conduit 76 has the composition
shown in Table 11 below.
I
TABLE II
Product in Conduit 76
Component:
Hydrogen
Mol percent
16.5
Methane ___
22.7
Acetylene
0.5
38 to the upper portion of a stripping tower 39 operated
at about 14 p.s.i.g. Steam is introduced into the lower
portion of stripping tower 39 which contains a number of
Ethylene
suitable liquid-vapor contact trays. The steam strips C13
and lighter hydrocarbons from the purge stream intro '20
Propadiene ____________________________ __
duced in conduit 38 so that the vaporous over-head from
tower 39 withdrawn through conduit 42 constitutes re
Propane ___
But-adiene
1.9
covered C13 and lighter hydrocarbons originally in the
pyrolysis e?iuent and lost therefrom incident to scrubbing
Butylene
3.2
Ethane
__
7.8
Methyl acetylene _______________________ __
Propylene
C5’s '
0.1
0.3
0.1
.._
____
2.5
C5’S ___
3.4
C-fs
0.6
_________________________________ _..
C878 ___
Cg’S-C13’S
30~
0.3
10.7
Butanes
in scrubber 27. A gas oil purge stream containing tarry 25
substances is withdrawn from tower 39 through conduit
77 at 348° F., cooled by indirect heat exchange in ex’
changer 68 to 226° F., and discarded from the process
through conduit 78. Operation in the foregoing manner
‘permits a continuous purge of undesirable tarry substances
from the process without the loss of C13 and lighter hydro
carbons.
__ 29.0
___
___.
._
C14’s—and heavier _____________________ __
0. 1
0.0
100.0
The cooled and cleaned pyrolysis eflluent is withdrawn ‘ By virtue of stripping the purge stream from conduit 35
in tower 39 and the condensate from the scrubbed-gas
as a scrubbed-gas fraction from scrubber 27 through a
conduit 59 at a rate of 172,035 lbs. hydrocarbon/hr., 35 fraction in tower 71, all of the advantages of hydrocarbon
combined with the vaporous overhead recovered from
stripping tower 39 in conduit 42 and cooled and partially
condensed by indirect heat exchange with cooling water
in exchanger 61. The cooling and partial condensing in
liquid scrubbing are obtained without the usual attendant
disadvantages previously mentioned as resulting from the
tendency to reach equilibrium between liquid and vapor
phases in scrubber 27.
It should be understood that many variations can be
made in the foregoing process without departing from the
vscope of the invention. For example, instead of intro
of the C13 and lighter hydrocarbons. A sharp liquid
ducing steam into stripping towers 39 and 71, convention
vapor separation between about Q14 and C13 hydrocarbons
-a1_ reboilers could be used to produce stripping vapors.
is again precluded by the equilibrium character of the
liquid-vapor separation. Separation of this mixture is 45 Also, instead of cooling the ef?uent to an intermediate
temperature in quench boiler 16, this step could be omitted
effected in drum 62, operated at about 105° F. and 9
‘and all the requisite cooling could be done in scrubber 27.
p.s.i.g., wherein a water layer and a hydrocarbon layer
‘Likewise, the vaporous overhead fraction of tower 39
develop as well as an uncondensed fraction. Water is
could, alternately, pass directly to product in conduit 76.
withdrawn from drum 62 through conduit 63 and discard
ed from the process. Hydrocarbon condensate is with 50 Instead of passing the vaporous overhead fraction of tower
71 directly to product, it could be combined with the
drawn from‘ drum 62 through conduit 64 and is passed
scrubbed-gas fraction in conduit 59 ‘and thereby be sub
by pump 66 in conduit 67 to heat exchanger 38 wherein
jected to an additional cooling and separation. The point
it is indirectly heated to about 250° F, The heated con
exchanger 61 is such as to condense substantially all of the
C14 and heavier hydrocarbons, steam and a minor portion
at which each of the vaporous overhead fractions of towers
densate from exchanger 68 passes in conduit 69 to the
upper portion of a stripping tower 71 to which steam is 55 39 and 71 is recombined with the scrubbed-gas fraction is
principally a matter of engineering expedience, i.e., in
introduced through a conduit 72. Stripping tower 71
accordance with relative pressures. Generally the ar
which also contains a number of suitable liquid-vapor
rangement illustrated by tower 39 and conduit 42 is
contacting trays is operated at about 9' p.s.i.g. The con
densate delivered in conduit 69 is stripped by steam to
recover C13 and lighter hydrocarbons as a vaporous over
vpreferred because sharper separations result from repeat
ed partial condensing and separation.
60
The foregoing example presents an embodiment of the
head fr-action withdrawn from tower 71 through conduit
invention in which several objectives are achieved: separa
73. The bottoms fraction comprising C14 and heavier
tion of higher boiling hydrocarbons, tarry substances and
hydrocarbons is withdrawn from tower 71 and discarded
solids from the vaporous feed and cooling of the vaporous
from the process through conduit 79. This operation of
tower 71 permits a continuous rejection of the C14 and 65 feed. It should be understood that the invention is of
equal applicability embodied in any process in which a
heavier hydrocarbons contained in the scrubbed-gas frac
hydrocarbon vapor is directly contacted with a hydro
tion incident to the scrubbing in scrubber 27, without the
carbon liquid so as to accomplish only one or a few of
loss of C13 and lighter hydrocarbons. The uncondensed
the above objectives.
portion of the scrubbed-gas fraction in drum 62 is with
Various alterations in and modi?cations to the process
drawn through conduit 74, combined with the vaporous 70
of the invention may be made as will be evident to one
overhead fraction from tower 71 in conduit 73, and
- skilled in the art without departure from its scope.
delivered through conduit 76 as the principal product of
the process. This product stream delivered at a rate of
We claim:
1. A process ‘for recovering C13 and lighter hydro
164,891 lbs. hydrocarbon/hr. contains substantially all of
.the C13 and lighter hydrocarbons originally present in the 75 carbons from a vaporous mixture containing the same
3,096,273
l
7
8
and tarry substances which comprises contacting said
hydrocarbons heavier than C13, separating a scrubbed
vaporous mixture in a scrubbing zone with a hydrocarbon
heavier than C13, separating a scrubbed-gas traction con
gas fraction containing a major portion of said C13 and
lighter hydrocarbons and a minor portion of said C14l
and heavier hydrocarbons and a liquid fraction contain~
taining a major portion of said C13 and lighter hydro- ,
carbons and a minor portion of said C14 and heavier
ing a major portion of said C14 and heavier hydrocarbons
and a minor portion of said C13 and lighter hydrocarbons,
scrubbing liquid predominantly comprising hydrocarbons
hydrocarbons and a liquid fraction containing a major
portion of said C14 and heavier hydrocarbons, tarry sub
passing at least a portion of said liquid fraction ‘from
said scrubbing zone to a ?rst stripping zone, separating
stances and a minor portion of said C13 and lighter hydro
carbons, separating C13 and lighter hydrocarbons from
at least a portion of said liquid fraction, cooling and par
tially condensing said scrubbed-gas fraction, separating
10
a vaporous fraction containing C13 and lighter hydro
carbons in said ?rst stripping zone, cooling and partially
condensing said scrubbed-gas ‘fraction, separating hydro
carbon condensate containing said minor portion of C14
hydrocarbon condensate containing said minor portion of
and heavier hydrocarbons present in said scrubbed-gas
C14 and heavier hydrocarbons present in said scrubbed
fraction and C13 ‘and lighter hydrocarbons from said
gas fraction and C13 and lighter hydrocarbons from said 15 cooled and partially condensed scrubbed-gas fraction,
cooled and partially condensed scrubbed-gas fraction,
passing at least a portion of said hydrocarbon condensate
separating C13 and lighter hydrocarbons from at least a
to a second stripping zone, separating a vaporous frac
portion of said hydrocarbon condensate, and recovering
tion containing C13 and lighter hydrocarbons in said
C13 and lighter hydrocarbons uncondensed from said
second stripping zone, and recovering C13 and lighter
cooling and partial condensing step and as separated ‘from 20 hydrocarbons uncondensed from said cooling and par~
said liquid fraction and said hydrocarbon condensate.
tial condensing step and as the vaporous fractions of each
‘2. In a process 'for the production of ethylene by the
pyrolysis of a hydrocarbon feed in which the pyrolysis
of said stripping zones.
5. A process as de?ned in claim 4 where that portion
effluent contains ethylene, gasoline, tarry substances and
of said liquid fraction ‘which is passed ‘from said scrub
solids, the process for recovering the gasoline and lighter 25 bing zone to said ?rst stripping zone is a minor portion
materials which comprises contacting said pyrolysis
and where a major portion of said liquid fraction is re
e?iuent in a scrubbing zone with a hydrocarbon scrub
turned to said scrubbing zone as at least a major portion
bing liquid predominantly comprising hydrocarbons
of said scrubbing liquid.
heavier than C13, separating a scrubbed-‘gas fraction con
6‘. A process for recovering C13 and lighter hydrocar
taining a major portion of said gasoline and lighter mate 30 bons from a vaporous mixture containing the same, C14
'rials and a minor portion of said C14 and heavier hydro
and heavier hydrocarbons and entrained solids which
carbons and a liquid fraction containing a major portion
comprises contacting said vaporous mixture in a scrub~
of said C14 and reavier hydrocarbons, said tarry sub
bing zone with a hydrocarbon scrubbing liquid predom
stances .and said solids and a minor portion of said gas
inantly comprising hydrocarbons heavier than C13, sepa
oline and light materials, separating gasoline and lighter
rating a scrubbed-gas fraction containing a major por
materials from at least a portion of said liquid fraction,
tion of said C13 and lighter hydrocarbons and a minor
cooling and partially condensing said scrubbed-gas frac
portion of said C14 and heavier hydrocarbons and a
tion, separating hydrocarbon condensate containing said
liquid fraction containing a major portion of said C14
rninor portion of C14 and heavier hydrocarbons present
and heavier hydrocarbons, a minor portion of said C13
in said scrubbed-ga-swfraction and gasoline and lighter 40 and lighter hydrocarbons and said entrained solids,
materials from said cooled and partially condensed
scrubbed-gas fraction, separating gasoline and lighter
?ltering said liquid fraction to remove solids, returning
a major portion of said ?ltered liquid ‘fraction to said
materials from at least a portion of said hydrocarbon
scrubbing zone as at least a major portion of said scrub
condensate and recovering gasoline and lighter materials
uncondensed from said cooling and partial condensing
bing liquid, passing a minor portion of said ‘?ltered liquid
hydrocarbon condensate.
3. A process for recovering C13 and lighter hydro
lighter hydrocarbons in said ?rst stripping zone, cooling
‘and partially condensing said scrubbed-gas fraction,
separating hydrocarbon condensate containing said minor
fraction from said scrubbing zone to a ?rst stripping
step and as separated from said liquid fraction and said 45 zone, separating -a vaporous fraction containing C13 and
carbons »from a vaporous mixture containing the same,
C14 and heavier hydrocarbons which comprises contact~ 50 portion of C14 and heavier hydrocarbons present in said
ing said vaporous mixture in a scrubbing zone with a
scrubbed-gas fraction and C13 and lighter hydrocarbons
hydrocarbon. scrubbing liquid predominantly comprising
‘from said cooled and partially condensed scrubbed-gas
hydrocarbons heavier than C13, separating a scrubbed
fraction, passing at least a portion of said hydrocarbon
gas fraction containing a major portion of ‘said C13 and
condensate to a second stripping zone, separating a
lighter hydrocarbons and a minor portion of said C14 55 vaporous fraction containing ‘C13 and lighter hydro
and heavier hydrocarbons and a liquid fraction contain
carbons in said second stripping zone, and recovering C13
ing a major portion of said C14 and heavier hydrocarbons
and lighter hydrocarbons uncondensed from said cooling
‘and a minor portion of said C13 and lighter hydrocarbons,
and partial condensing step and as the vaporous \fractions
separating C13 and lighter hydrocarbons from at least a
of each of said stripping zones.
portion of said liquid fraction, cooling and partially
7. A process for cooling and recovering C13 and lighter
condensing said scrubbed-gas ‘fraction, separating hydro
hydrocarbons from 1a relatively war-n1 vaporous pyrolysis
carbon condensate containing said minor portion of C14
effluent containing the same, ‘C14 and heavier hydrocar
and heavier hydrocarbons present in said scrubbed-gas
bons which comprises contacting said relatively warm
fraction and C13 and lighter hydrocarbons from said
vaporous e?luent in a scrubbing zone with a relatively
cooled and partially condensed scrubbed-gas fraction,
cold
hydrocarbon scrubbing liquid predominantly con
separating C13 and lighter hydrocarbons from at least a 65 taining hydrocarbons heavier than lC13, separating a cool
portion of said hydrocarbon condensate, and recovering
scrubbed-gas fraction comprising a major portion of said
C13 and lighter hydrocarbons uncondensed from said
C13 and lighter hydrocarbons and a minor portion of said
cooling and partial condensing step and as separated from
C14 and heavier hydrocarbons and a warm liquid fraction
said liquid fraction and said hydrocarbon condensate.
70 containing a major portion of said C14 and heavier hydro
4. A process for recovering C13 and lighter hydro
carbons and a minor portion of said C13 and lighter hy
carbons from a vaporous mixture containing the same,
drocarbons, cooling a major portion of said Warm liquid
C14 and heavier hydrocarbons which comprises contact
fraction, returning the thus cooled portion of said warm
ing said vaporous mixture in a scrubbing zone with a
liquid fraction to said scrubbing zone as at least a major
hydrocarbon scrubbing liquid predominantly comprising 75 portion of said relatively cold scrubbing liquid, passing a
3,096,273
10
11. A process for cooling and recovering C13 and
minor portion of said warm liquid fraction from said
lighter hydrocarbons from a hightemperature vaporous
scrubbing zone to a ?rst stripping zone, separating a
pyrolysis e?luent containing the same, C14 and heavier
hydrocarbons and entrained solids which comprises cool
ing said high temperature vaporous pyrolysis e?luent by
vaporous fraction containing C13 ‘and lighter hydrocar
bons in said ?rst stripping zone, further cooling and par
tial condensing said cool scrnb'bedrgas fraction, separat
indirect heat exchange to an intermediate temperature,
ing hydrocarbon condensate containing said minor portion
directly contacting the partially cooled e?luent in a scrub
of C14 and heavier hydrocarbons present in said cool
bing zone with a relatively cold ‘hydrocarbon scrubbing
scrubbed-gas fraction ‘and C13 and lighter hydrocarbons
liquid predominantly comprising hydrocarbons heavier
from said further cooled and partially condensed
than C13 and obtained ‘as described below, separating a
10
scrubbed-gas fraction, passing at least 1a portion of said
cooled scrubbed-gas fraction containing a major portion
hydrocarbon condensate to a second stripping zone, sep
of said C13 and lighter hydrocarbons and a minor portion
arating a vaporous fraction container C13 and lighter hy
of said C14 and heavier hydrocarbons and a warm liquid
drocarbons in said second stripping zone, and recovering
fraction containing a major portion of said C14 and heav
‘C13 and lighter hydrocarbons uncondensed from said fur
ther cooling and partial condensing step and as the vapor 15 ier hydrocarbons, a minor portion of said C13 and lighter
hydrocarbons and said entrained solids, ?ltering said
ous fractions of each of said stripping zones.
warm liquid fraction to separate solids, cooling a major
8. A process as de?ned in claim 7 in which said rela
portion of said ?ltered liquid fraction, combining said
tively warm vaporous pyrolysis ef?uent further contains
cooled major portion of said ?ltered liquid ‘fraction with
steam and in which the temperature of said cool scrubbed
a hydrocarbon liquid stream predominantly comprising
gas fraction is maintained above the dew point of steam 20
hydrocarbons heavier than C13 and free of tarry sub
whereby said warm liquid fraction separated in said
stances, passing said combined stream to said scrubbing
scrubbing zone is substantially water-free.
zone as the above-mentioned relatively cold scrubbing
9. A process as de?ned in claim 7 in which the tem
liquid,
passing a minor portion of said ?ltered liquid frac
perature of the cool scrubbed-gas ‘fraction is above about
tion to a ?rst stripping zone, separating a vaporous frac
170° F. and the temperature of said relatively cold scrub 25 tion
containing ‘C13 and lighter hydrocarbons in said ?rst
bing liquid contacting said pyrolysis ef?uent in said scrub
stripping zone, further cooling and partially condensing
bing zone is initially between about 10° F. and 50° F.
said cooled scrubbed-gas fraction, separating hydrocarbon
cooler than the temperature of said cool scrubbed~gas
fraction.
_
10. A process for recovering C13 and lighter hydro
30
carbons from a vaporous pyrolysis e?luent containing the
same, C14 and heavier hydrocarbons and entrained solids
which comprises contacting said vaporous effluent in a
scrubbing zone with a hydrocarbon scrubbing liquid pre
dominantly comprising hydrocarbons heavier than C13
condensate containing said minor portion of C14 and
heavier hydrocarbons present in said cooled scrubbed
gas fraction and C13 and lighter hydrocarbons from said
further cooled and partially condensed scrubbed-gas frac
tion, passing at least a portion of said hydrocarbon con
densate to a second stripping zone, separating a vaporous
35
and obtained as described below, separating a scrubbed
tgas fraction containing a major portion of said C13 and
fraction containing C13 and lighter hydrocarbons in said
second stripping zone, and recovering C13 and lighter
hydrocarbons uncondensed from said further cooling and
partial condensing step and as the vaporous fractions of
lighter hydrocarbons and a minor portion of said C14 and
of said stripping zones.
heavier hydrocarbons and a liquid fraction containing a 40 each
12. A process as de?ned in claim 11 wherein said high
major portion of said ‘C14 and heavier hydrocarbons, a
temperature vaporous pyrolysis effluent is at a tempera
minor portion of said ‘C13 and lighter hydrocarbons and
ture between about 1100° F. and about 1600° B, said
said entrained solids, ?ltering said liquid fraction to re
intermediate temperature to which said vaporous pyroly
move solids, combining a major portion of said ?ltered
sis e?luent is partially cooled is between about 500° F.
liquid fraction with a hydrocarbon liquid stream pre 45 and about 900° F., said cooled scrubbed-gas fraction is
dominantly comprising hydrocarbons heavier than C13
at a temperature above about 170° F. and said relatively
and free of tarry substances, passing said combined stream
cold scrubbing liquid contacting said partially cooled ef
to said scrubbing zone as the above-mentioned scrubbing
fluent in said scrubbing zone is initially ‘at a temperature
liquid, passing a minor portion of said ?ltered liquid frac
between about 10° F. and 50° F. vbelow the temperature
tion to a ?rst stripping zone, separating -a vaporous frac
tion containing C13 and lighter hydrocarbons in said ?rst
stripping zone, cooling and partially condensing said
scrubbed-gas fraction, separating hydrocarbon condensate
containing said minor portion of C14 and ‘heavier hydro
carbons present in said scrubbed-gas fraction and C13 and 65
lighter hydrocarbons vfrom said cooled and partially con
densed scrubbed-gas fraction, passing at least a portion
of said hydrocarbon condensate to a second stripping
zone, separating =a vaporous ‘fraction containing C13 and
lighter hydrocarbons in said second stripping zone, and 60
recovering C13 and lighter hydrocarbons uncondensed
from said cooling and partial condensing step and as the
vaporous fractions of each of said stripping zones.
of said cooled scrubbed-gas fraction.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,824,947
Davis et al. __________ __ Sept. 29, 1931
2,313,940
2,619,450
2,768,124
2,777,802
2,780,580
2,804,488
2,989,459
Hirsch ______________ __ Mar. 16,
Fleming _____________ __ Nov. 25,
Berg ‘et a1 _____________ __ Oct. 23,
Peet _________________ __ Jan. 15,
Kniel ________________ __ Feb. 5,
Cobb ________________ __ Aug. 27,
Eastman et a1. ________ __ June 20,
1943
1952
1956
1957
1957
1957
1961
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