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Патент USA US2105122

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Jan- 1 1, 1938.
‘
T. B. KlMBALL ET AL
2,105,122
ART OF CRACKING HYDROCARBON§
Filed June 20, 1953
Tar
‘g
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INVENIOR
Mamas B, lnmbal/
0n}? GJfaasa
ATTORNEYS
'
Patented Jan. 11, 1938
UNITED STATES PATENT, QFFCE
2,105,122
ART OF CRACKING HYDROCARBONS
Thomas 13.. Kimball, Hammond, and Orin G.
Kaasa, Munster, Ind, assignors to Sinclair Re
_,
?ning Company, New York, N. Y., a corporation
of Maine
Application June 20, 1933, Serial No. 676,616
10 Claims.
This invention relates to improvements in op
(Cl. 196—58)
fraction cyclically circulating from the separat
erations combining the cracking and coking of ing receptacle to the coking receptacle and back
petroleum oils, the cracking of gas oil and kero
sene character stocks for example and the cok
ing of crude oils or reduced crude oils, fuel oils,
tars and the like. The invention consists es
sentially in the combination of two features of
operation in operations of this general type.
In that form of such combined operations to
10 ‘which this invention more particularly relates, a.
stream of oil to be cracked is forced through a
heater and heated to a high temperature therein,
oil to bercoked is reduced to coke in a coking
receptacle by direct heat exchange with the
-15 stream of heated oil discharged from the heater,
and the vapors from the coking receptacle are
cooled to separate, in a separating receptacle, a
residual tar which is usually introduced into the
coking receptacle.
The separation of entrained
20 liquid particles from the vapors from the coking
receptacle, an unusually persistent form of en
trainment, has required special operations, par
ticularly in combined operations involving re
turn to the heater of fractions condensed from
25 vapor mixtures including vapors from the cok
ing receptacle. Scrubbing oi the vapors from the
coking receptacle in a liquid oil body including
the separated tar is one of the best means of
eliminating such entrainment. The maintenance
30 of the substantial liquid bodies necessary to ei
iect such scrubbing, however, involves a loss
with respect to recovery of liquid distillates be
cause of so-—called “polymerization reactions”
which proceed in such oil bodies at the elevated
35 temperatures necessarily involved. Such pol
ymerization reactions are reduced to a minimum
by reducing to a minimum thermean time for
to the separating receptacle, and so on. This ef
fect is avoided, in the combined operation, by
introducing into the coking receptacle part, but 1'
only part, of the residual tar separated in the
separating receptacle, the balance being dis
charged from the system in which the operation
is carried out. The ratio between the part intro
‘duced into the coking receptacle and the part 10
discharged from the ‘system is with advantage
kept at a maximum short of that value at which
such progressive accumulation of a cyclically cir
culating refractory tar fraction begins. The
invention consists essentially in combination, in .15
operations of this general type, of the mainte
nance of a minimum of liquid tar volume‘in the
separating receptacle with the introduction of
part, but only part, of this separated tar into the
coking receptacle, the maximum advantage of
the invention being. derived when maximum
temperatures short of those at which coking
begins are maintained in the separating re
ceptacle.
In putting this invention into prac
tice, the entrainment dii?culties to which. refer- ' '
ence has been made are eliminated by improved
fractionation of the vapors escaping ‘from the
separating receptacle;
Thus, according to this invention, a stream of
oil to be cracked is forced vthrough a heater 30
and heated therein'to a temperature approxi
mating 1000P-l150° F. and an oil to be coked is
reduced to coke, in a coking receptacle, by direct
heat exchange with the stream of heated oil
discharged from the. heater. The vapors from the
coking, receptacle are cooled, advantageously to
a temperature upwards of 750° F., to separate a
which the average. molecular group is maintained
residual tar , in a separating receptacle, that
at these elevated temperatures.
minimum volume of liquid tar necessary to
maintain liquid discharge from the lowermost
This is accom
40 plished by maintaining, in the separating re
ceptacle in which residual tar is separated from
the cooled vapors .from the coking receptacle,
that minimum volume of liquid tar necessary to
maintain liquid discharge from the lowermost
45 part of the separating receptacle. Then, by
maintaining a relatively high temperature in the
separating receptacle, an improved recovery of
liquid distillates is to be had. ‘However, under
these conditions, the tar separated in the sepa
50 rating receptacle tends to become progressively
more refractory with respect to the coking con
ditions maintained in the coking receptacle with a
consequent tendency to choke the system in
which the operation is carried out through the
56 gradual increase in volume of a refractory tar
part of the separating receptacle is maintained
therein, liquid tar is discharged from the lower
most part of the separating receptacle and part,
but only part, of this ‘discharged tar is intro
duced into the coking receptacle. The oil to be 45
coked may be introduced into the separating re
ceptacle, that part of such oil remaining un
vaporized therein combining with the residual
tar separated therein, or it may be introduced
directly into the coking receptacle, or it maybe
introduced into a iractionating operation to
which the Vapors escaping from the separating
receptacle are subjected, in direct heat exchange
with the vapors, for example. The cooling of the
vapors from the coking receptacle may be effected 55
2,105,122’
2
by direct heat exchange with oil to be cracked,
troduction into the separating tower 4 through
in operations in which a fraction condense-d from
any of connections 26, 21, 28 and 29 or by in
.troduction into the transfer connection 25
through connection 30 or by combined introduc
tion of cooling oil through two or more of these
connections. A residual tar is separated in
separating tower 4 and is discharged, as a liquid,
through connection 3|, that minimum volume of
liquid tar necessary to maintain liquid discharge
being maintained in the tar leg 2|. Part of the 10
residual tar discharged through connection 3I is
the vapors escaping from the separating. recep
tacle is returned to the heater, or with oil to be
coked or with a fraction condensed from the
vapors escaping from the separating receptacle,
and stock so utilized as a cooling medium may be
introduced either directly into the separating
receptacle or into the vapors passing from the
10 coking receptacle and thus into the separating
receptacle.
The invention will be further described in
connection with the accompanying drawing
which illustrats, diagrammatically and conven
15 tionally, in elevation and partly in section and
with parts broken away, one form of apparatus
adapted for practice of the invention.
The apparatus illustrated comprises the heat
ing furnace I in which a heating coil 2 is ar
20 ranged, a coking chamber 3, a separating tower
>4, fractionating towers 5 and 6, a condenser ‘I,
and a receiver 8. Re?ux condensers 9 and II) on
tower 4, II and I2 on tower 5, and I3 and I4 on
tower 6 are provided for control or supplementary
25 control of the operation of these several towers.
Re?ux condensers 9, H and I3 are arranged as
heat exchangers to permit the recovery of heat
30
35
40
45
50
abstracted from the vapors passing therethrough
in stock to be'supplied to the operation; Coolers
I5, I9 and I‘! are provided for cooling residual or
liquid fractions discharged from towers 4, 5 and
5 respectively and coolers I5 and I6 are arranged
to permit the cooling or partial cooling of residual
or liquid fractions discharged from towers 4 and
5 and returned to the operation. Only one cok
ing chamber is illustrated; usually a group of
two, three or more coking chambers is connected
between the manifold headers I8, I9, 20 and 53
to avoid interruption of the combined operation
while permittingdischarge of accumulated coke
from and cleaning of individual coking chambers.
In order to facilitate the maintenance of liquid
discharge from the lowermost part of the tower
4 while maintaining the minimum volume of
liquid tar therein, this tower is provided with
a tar leg 2I, the liquid level of separated tar
remaining within the tower normally being main
tained within this tar leg. By this expedient it
is possible to maintain without unusual dif?
culty a volume of liquid tar as low as one-half
a barrel or even less in the separating tower of
the combined apparatus in which the normal
charging rate to the heater approximates 200-300
barrels per hour.
55
In carrying out the invention in the apparatus
illustrated: Oil to be cracked, a gas oil or kerosene
character stock for example, is forced by means
of pump 22 through the heating coil 2 and is
heated therein to a temperature, for example,
60 of 1120°—1130° F., and the hot oil products dis
charged from the heating coil are introduced,
through connection 23, into the coking chamber
3. Oil to be coked is introduced into the coking
chamber 3 through connection 24, and is reduced
to coke therein by direct heat exchange with the
introduced into the coking receptacle 3 through
connection 24, either by means of pump 32
through connection 33 or by means of pump 34,
after passing through the cooler I5, through con 15
nections 35, 36 and 31, and another part of this
residual tar is discharged through connection 38.
The vapors escaping from the separating tower
4 are subjected to fractionation in the fraction
ating tower 5, the vapors escaping from the frac 20
tionating tower are subjected to fractionation in
the fractionating tower 6, and the vapors escap
ing from this fractionating tower, constituting
a gasoline fraction for example, are condensed
in the condenser ‘I, the condensed distillate being 25
separated from uncondensed vapors and gases
and collected in receiver 8.
The oil to be cracked, supplied to the heating
coil 2, may consist, for example, of a distillate
fraction separated in the fractionating tower 6, 30
supplied hot to the pump 22 through connection
39, or. of an appropriate fraction supplied to
the pump 22 from an extraneous source through
connection 40, or a mixture of the two. All or
part of the distillate fraction separated in frac
tionating tower 5 may be discharged through
connection 4| after passing through cooler H.
The oil to be coked, at least the higher boiling
constituents of which are ultimately introduced
.into the coking chamber 3, may, in the ?rst in
stance, be introduced either into the coking
chamber 3 through connection 24, or into the
separating tower 4 through connections 25, 27,
28 and 29 or one or more of them, or into the
transfer connection 25 through connection 39, or
‘
into the fractionating tower 5 through connec
tions 42 and 43 or one of them, or simultaneously
through anytwo or more of these connections.
Oil to be coked containing constitutents suitable
as components of the distillate collected in re- ’
ceiver B or of the distillate separated in frac
tionating tower 5, for example, is with advan
tage introduced either into the fractionating
tower 5, through connections 42 and 43 for ex
ample, or into the upper part of separating tower 155
4, through connections 28 and 29 for example.
Such oil may be supplied, for example, through
connection 44. Oil to be coked which is rela
tively free from constituents of intermediate
boiling range is with advantage introduced (60
either directly into the coking chamber 3 through
connection 52 or into the separating tower 4
through connections 26 and 21 or one of them.
Such oil may be supplied, for example, through
connection 45. For example, crude oil may be 765
hot oil products entering the coking chamber I introduced through any of connections 29, 28,
43 and 42, reduced crude oil containing a substan—
through connection 23. The coke product ac
cumulates in the coking chamber. The vapors tial proportion of constituents of intermediate
from the coking chamber pass to separating tower boiling range may be introduced through any of
these connections or through connection 30, 70
4 through connection 25. A temperature ap
proximating 775° F. is with advantage main
reduced crude oil relatively free from constituents
tained in the lower part of the separating tower of intermediate boiling range or fuel oil of this
4. To maintain this temperature, a cooler oil
character may be introduced through any of
is brought into direct heat exchange with the connections 29, 28, 21, 26, 30 and Z4, and cracked
tars and the like may be introduced through 75
75 vvapors from the coking chamber, either by in;
2,105,122
any‘of the connections 26, 30 and 24; The in
vention is not limited to the foregoing distribu~
tion of stocks, but this distribution is given merely
to illustrate.
'
10
‘
> i
The fraction separated in the fractionating
tower 5‘ may be a distillate fraction if, any oils
introduced through either connection 42 or con
nection 43 are distillate fractions or it may in
clude‘ residual constituents'if such oils include
residual fractions. This fraction separated in
tower 5 maybe either discharged through con
nection 46 where oil to be coked is not introduced
into the fractionating tower 5, or it may be in
whole or in part ‘introduced into the separating
tower 4 through connection 26 or connection 2'!
or into the transfer connection 25 through con
nections 4'! and “by means-of pump 48 as a
cooling medium Whether or not oil to be coked is
introduced into tower 5, and this either with or
20 without having passed through cooler IE, or it
may be introduced in whole. or in part into the
coking chamber 3 through connection 24 or into
the transfer connection 25 through connection 30
or into the separating tower 4 through connection
26 or connection’ 2'! where oil to be coked is intro
duced into tower 5. The use of the fraction or
part of the fraction separated in ‘the fraction
ating tower has a cooling ‘medium in the oper
130
ation of separating tower 4 is particularly advan
tageous where thisjfraction-is condensed, at least
in part, by direct, heat exchange with oil to be
coked introduced into tower 5.
,
I
The several towers 4, 5 and 6 are controlled
either by regulated circulation of a stock to be
supplied to, the operation through re?ux con
densers 9, II and i3, appropriate by-pass connec
tions being provided for control ‘of this circu
lation, or by regulated circulation of a cooling
medium through re?ux condensers l0, I2 and
40 I4 or by regulated introduction of a vaporizable
re?uxing medium through the connections .49, 5G
and 5!,‘or by any of these means conjointly.
Oil to ‘be coked containing foreign solids, such
as crude oil or reduced crude oil containing sub
3
This invention makes possible the separation of
a residual tar in the separating receptacle so
concentrated as to have a gravity, corrected to
atmospheric temperature, as low as —5 A. P. I.
In another aspect, the concentration of the re
sidual tar so separated is a measure of the im
provement in capacity of the apparatus in which
the operation is carried out. As the concentra
tion of this residual tar is increased, the burden
imposed upon the coking operation proper is re 10
‘duced and the ratio of vapors to liquids dis
charged from the separating receptacle is in
creased. In the combined operation of the in
vention, full realization of this improvement with
respect to the coking operation proper is had 15
because of limitation, by means of the invention,
of accumulation of any cyclically circulating re
fractory tar fraction. Further, by the provision
of adequate fractionation of the vapors escaping
from the separating receptacle, a distillate frac-’ 20
tion substantially free from tar constituents and
appropriate to be supplied to the heating opera
ation is recovered.
We claim:
1. In cracking and coking petroleum oils, the 25
improvement which comprises forcing a stream
of oil to be cracked through a heater and heating
it therein to a temperature approximating 1000°~
1150° F. and reducing. another oil to coke by di
rect heat exchange with this stream of heated
oil in a coking receptacle, cooling the vapors from
the coking receptacle to separate a residual tar
in a separating receptacle, maintaining that
minimum volume of liquid tar in the separating
receptacle necessary to maintain liquid discharge 35
from the lowermost part thereof, discharging liq
uid tar from the lowermost part of the separat
ing receptacle and introducing part but only part
of this discharged tar into the coking receptacle.
2. In cracking and coking petroleum oils, the.v
improvement which comprises forcing a stream
of oil to be cracked through a heater and heat
ing it therein to a temperature "approximating
1000°-1150° F. and reducing another oil to coke
stantial proportions of salt, cracked tar contain
by direct heat exchange with this stream of
ing high proportions of solid vor semi-solid ma
terials, and residual stocks including solid or
semi-solid reactants or reaction products such as
those resulting from the treatment of lubricat
ing oils with caustic alkali, ‘for example, is with
heated oil in a coking receptacle, cooling the va
pors from the coking receptacle to a temperature
approximating 775° F. to separate a residual tar
advantage introduced directly" into the coking
chamber 3 through connection 52.‘ The bulk of
such foreign solids is thus precipitated as part
of the coke accumulating in the coking chamber
and that part of the residual tar discharged
through connection ‘38 is, in this manner, freed
from that proportion of the thus precipitated
solids which it would otherwise contain if this
stock were introduced, for example, into the sepa
rating tower 4. The value as a liquid fuel of the
residual tar discharged through connection 38, in
operations in which such residual oil containing
foreign soiids is to be handled, can thus be sub
stantially increased. In one aspect, the inven
" tion thus makes possible the recovery of substan
tial values from residual oils containing foreign
solids otherwise useless even as fuel.
The features of operation combined in the
process of the invention cooperate to improve the
recovery of liquid distillates and to improve the
capacity of any particular apparatus in.which
the operation is carried out. In one aspect, the
concentration of the residual tar separated in
the separating receptacle is a measure of the im
provement in recovery of liquid distillates.
316
in a separating receptacle, maintaining that
minimum volume of liquid tar in the separating
receptacle necessary to maintain liquid discharge to
from the lowermost part thereof, discharging liq
uid tar from the lowermost part of the separat
ing receptacle and introducing part but only part
of this discharged tar into the coking receptacle. 1"
3. In cracking and coking petroleum oi1s,'the
improvement which comprises forcing a stream
of oil to be cracked through a heater and heating
it therein to a temperature approximating 1000°
1150° F. and reducing another oil to coke’ by to
direct heat exchange with this stream of heated
oil in a coking receptacle, cooling the vapors
from the coking receptacle to separate a residual
tar in a separating receptacle, introducing oil to
be coked into the separating receptacle, main 65
taining that minimum volume of liquid tar in the
separating receptacle necessary to maintain liq
uid discharge from the lowermost part thereof,
discharging liquid tar from the lowermost part
of the separating receptacle and introducing part 70
but only part of this discharged tar into the cok
ing receptacle.
4. In cracking and cokingpetroleum oils, the
improvement which comprises forcing a stream
of oil to be cracked through a heater and heating 75
2,106,122
it therein to a temperature approximating 1000"
-1150° F. and reducing another oil to coke by
direct heat exchange with this stream of heated
part thereof, discharging liquid tar from the low
ermost part of the separating receptacle and in
troducing part but only part of this discharged
oil in a coking receptacle, cooling the vapors
tar into the coking receptacle.
8. In cracking and coking petroleum oils, the
fit from the coking receptacle to separate a residual
tar in a separating receptacle, maintaining that
minimum volume of liquid tar in the separating
receptacle necessary to maintain liquid dis
charge from the lowermost part thereof, dis
10 charging liquid tar from the lowermost part of
the separating receptacle and introducing part
but only part of this discharged tar into the cok
ing receptacle, and introducing oil to be coked
into the coking receptacle.
5. In cracking and coking petroleum oils, the
15
improvement which comprises forcing a stream
improvement which comprises forcing a stream
of oil to be cracked through a heater and heat
ing it therein to a temperature approximating
1000°-l150° F. and reducing another oil to coke
by direct heat exchange with this stream of 10
heated oil in a coking receptacle, cooling the va
pors from the coking receptacle to separate a
residual tar in a separating receptacle by direct
heat exchange with a fraction condensed from
the vapors escaping from the separating recep 15
pors from the coking receptacle by direct heat
exchange with oil to be coked to separate a
tacle, maintaining that minimum volume of liq
uid tar in the separating receptacle necessary
to maintain liquid discharge from the lowermost
part thereof, discharging liquid tar from the low
ermost part of the separating receptacle and 20
introducing part but only part of this discharged
tar into the coking receptacle, and condensing
said fraction by direct heat exchange with oil
residual tar in a separating receptacle, main
to be coked.
of oil to be cracked through a heater and heat
ing it therein to a temperature approximating
l000°-1l50° F. and reducing another oil to coke
by direct heat exchange with this stream of
heated oil in a coking receptacle, cooling the va
v25 taining that minimum volume of liquid tar in the
separating receptacle necessary to maintain liq
uid discharge from the lowermost part thereof,
discharging liquid tar from the lowermost part
of the separating receptacle and introducing part
'30 but only part of this discharged tar into the cok
ing receptacle.
6. In cracking and coking petroleum oils, the
improvement which comprises forcing a stream
of oil to be cracked through a heater and heating
it therein to a temperature approximating 1000"
1150° F. and reducing another oil to coke by di
rect heat exchange with this stream of heated
oil in a coking receptacle, cooling the vapors
from the coking receptacle by direct heat ex
change with another oil to separate a residual
tar in a separating receptacle, maintaining that
minimum volume of liquid tar in the separating
receptacle necessary to maintain liquid discharge
'from the lowermost part thereof, discharging
45 liquid tar from the lowermost part of the sepa
rating receptacle and introducing part but only
part of this discharged tar into the coking recep
tacle.
7. In cracking and coking petroleum oils, the
improvement which comprises forcing a stream
so of oil to be cracked through a heater and heat
ing it therein to a temperature approximating
1000°-1150° F. and reducing another oil to coke
by direct heat exchange with this stream of
heated oil in a coking receptacle, cooling the va
pors from the coking receptacle to separate a
residual tar in a separating receptacle by direct
heat exchange with a fraction condensed from
the vapors escaping from the separating recep~
60 tacle, maintaining that minimum volume of liq
uid tar in the separating receptacle necessary
to maintain liquid discharge from the lowermost
9. In cracking and coking petroleum oils, the 25
improvement which comprises forcing a stream
of oil to be cracked through a heater and heat
ing it therein to a temperature approximating
l000°-1l50° F. and reducing another oil to coke
by direct heat exchange with this stream of 30
heated oil in a coking receptacle, cooling the
vapors from the coking receptacle to a tempera
ture upwards of 750° F. to separate a residual tar
in a separating receptacle, maintaining that min
imum volume of liquid tar in the separating re
ceptacle necessary to maintain liquid discharge
from the lowermost part thereof, discharging
liquid tar from the lowermost part of the sep
arating receptacle and introducing part but only
part of this discharged tar into the coking recep~
tacle.
10. In cracking and coking petroleum oils, the
improvement which comprises forcing a stream
of oil to be cracked through a heater and heat
ing it therein to a temperature approximating
l000°—'1150° F. and reducing another oil to coke
by direct heat exchange with this stream of
heated oil in a coking receptacle, cooling the
vapors from the coking receptacle to separate a
residual tar in a separating receptacle, main
taining that minimum volume of liquid tar in
the separating receptacle necessary to maintain
liquid discharge from the lowermost part there
of, discharging liquid tar from the lowermost
part of the separating receptacle and introduc
ing part but only part of this discharged tar into
the coking receptacle, and introducing oil to be
coked containing foreign solids directly into the
coking chamber._
THOMAS B. KIMBALL.
ORIN G. KAASA.
35
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