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Патент USA US2113816

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April 12, 1938-
c. w. SAACKE
Filed Oct. 18, 1934
CHARLES n4 s/mcnz
Patented Apr. 12, 1938
, 2,113,816
Charles W. Saacke, New York, N. Y., assignor to
Gasoline Products Company, Inc., Newark,
N. J., a corporation of Delaware
Application October 18, 1934, Serial No. 748,823
2 Claims.
This invention relates to processes and appa
ratus for the production of gasoline or other
relatively light distillate from raw crude oil, or
other similar relatively heavy stock containing
5 lighter and heavier constituents.
ing a heavy gas oil distillate derived from the
other cracking steps, under the condition best
suited for the conversion of this heavy gas oil
In the treatment of raw crude oil or the like
The above mentioned and further objects and
to produce gasoline, it has been the general prac—
tice heretofore to form from the crude oil, either
by distillation alone or distillation coupled with
advantages of my invention and the manner of
obtaining them will be made clear in the follow
'10 mild cracking, a distillate stock suitable for
charging to a cracking operation, this stock
(Cl. 196-48)
value to the desired point, and separately crack
usually being a gas oil. Simultaneously, a plu
rality of other cuts have customarily been re
moved from the crude charging stock, being, for
example, a light naphtha cut or virgin gasoline,
heavy naphtha which it is desired to reform,
kerosene and in some cases furnace oil, for sale
as products without further conversion. After
these several cuts have been obtained, it has
20 been customary to subject the gas oil to cracking
in a separate unit, wherein it is converted to
gasoline or other desired light distillates, and to
reform the heavy naphtha separately in still an
other operation. In certain instances the re
25 duced crude freed of the distillate stock men
tioned, has been cracked under low crack per
pass conditions to reduce its viscosity by the
formation of additional quantities of gas oil suit
able for cracking in a separate gas oil cracking
- 30 step.
It is an object of my invention to provide a
unitary process for the treatment of raw crude
ing description taken in conjunction with the
accompanying drawing.
The single ?gure of the drawing represents
diagrammatically in side elevation and partly in
section a combination cracking unit constructed
in accordance with my invention.
Referring more particularly to the drawing, 15
reference numeral I indicates a crude flash tower,
2 an evaporator, 3 a viscosity breaking furnace,
4 a vapor phase furnace, 5 a soaking drum and B,
a fractionator.
Fresh heavy charging stock, such as crude oil, 20
after preliminary heating to a distilling tempera
ture, for example, by indirect heat exchange with
hot products resulting from subsequent cracking
steps, or after having been heated in a directly
?red coil, or both, is forced through charging 25
line ‘i by pump 8 into the ?rst stripping section
9 of the crude ?ash tower or stripping tower I,
wherein lighter constituents thereof are sepa
rated as vapors and passed off through vapor line
it and condenser II into receiving drum I2, the 30
condensate collected in the receiving drum be
ing, for example, light naphtha or low end point
virgin gasoline. The unvaporized liquid collect
oil or the like whereby all the operations neces
sary to produce a maximum amount of gasoline ' ing in the base of the section 9 travels down
35 of ?nal desired end point and characteristics wardly through pipe I3, into the intermediate 35
portion of the second section I4 of the crude
may be carried out at the same time in a series
of interlocking steps so related, one to another, flash tower, wherein a further separation into
that a minimum amount of heat and attention vapors and liquids takes place, by the contacting
are necessary, and high ef?ciency results. By of the introduced liquid with a stream of highly
heated vapors passing upwardly through the 40
section M, as will be explained more fully here
inafter. This separation may be further aided,
if desired, by a reduction in pressure obtained by
adjustment of valve I5. The vapors generated
travel upwardly through the section I4, and those 45
remaining uncondensed at the top of this section
pass oif through vapor line I6 and condenser I'I
the process.
into receiver I8, the distillate so collected being,
More speci?cally, it is an object of my inven
tion to combine in a single unitary process for the > for example, heavy naphtha which it is desired
50 treatment of raw crude oil, the steps of topping to reform. An intermediate condensate collects 50
the raw crude, viscosity breaking the topped on trap-out tray I9, and is forced by pump 20
through line 2i into the top of the evaporator
crude, cracking a clean condensate stock, includ
40 combining all of the various steps which have
-heretofore been performed individually or in
some incomplete combination, it is possible to
utilize more advantageously heat which might
votherwise be wasted, and also keep at a low ?g
‘.15 ure the amount of'labor and supervision neces
sary in the operation of a system to carry out
ing cracked and virgin components, derived from
2 or into the bubble tower or fractionator 6
the process, reforming any necessary portion of,
through line 22, or both. The intermediate dis
tillate so introduced into the evaporator and/or 55
65 the gasoline produced to raise its anti-knock
fractionator serve as a re?uxing medium, and
is at the same time placed in a position for cir
culation through the vapor phase cracking fur
nace 5%, as will be explained more fully herein
after. The unvaporized liquid collects on trap
out tray 23, from which it may be withdrawn
through pipe 24.
The several sections of the crude ?ash tower
or stripper l are provided with bubble trays,
10 baifles or other contacting means, as shown in
the drawing, in accordance with the usual prac
tice. The lower portion of the section i4 serves
as a tar ?ashing chamber, as will be explained
Reference numerals 25, 26'and 21 indicate re
?uxing lines through which cool oil from an ex
pressure control valve 42, into the lower portion
of the evaporator 2, wherein these products un
dergo separation into vapors and liquid residue,
just as described in connection with the cracked
oil from the viscosity breaking furnace 3, The
soaker 5 may be by-passed, if desired, in which
case the cracked oil from the heating coil 39
would pass directly into the evaporator 2.
The heavy naphtha collected in the receiver I8
is directed through the conduit 43, under pressure 10
generated by pump 44, through the naphtha re
forming coil 45 located in the vapor phase fur
nace 4, wherein the naphtha is raised to a high
cracking temperature sui?cient to cause the con
version thereof into higher anti-knock gasoline 15
The resulting reformed products
ternal source may be introduced for cooling and
are transferred from the coil 45 through the line
re?uxing purposes in the well known manner.
45, having pressure control valve 41, into the
lower portion of the evaporator 2.
Alternatively, indirect cooling coils may be
placed in the tower l, to accomplish the same
purpose, or cooling may be supplied in any well
known manner.
The unvaporized liquid reduced crude is with
drawn from the trap-out tray 23 through con
25 duit Eli, and forced by pump 28 through the heat
ing coil located in the viscosity breaking furnace
3, from which the oil emerges, after having been
raised to cracking temperature and cracked sui?
ciently to produce additional quantities of light
clean gas oil stock, suitable for cracking in the
vapor phase, and is forwarded through transfer
line 29 into the lower portion of evaporator 2,
wherein separation of vapors from liquid residue
takes place. Valve 39 is inserted in the transfer
35 line 29 to control the relative pressures in the
viscosity breaking furnace and evaporator. The
vapors pass upwardly through the evaporator,
undergoing ‘partial condensation therein, this
condensation being only sufficient to condense the
40 heavier gas oil components thereof, the vapors
remaining uncondensed passing oif through con
duit 3i and partial condenser 32, into the lower
portion of the bubble tower 6. Condensate formed
in the’ partial condenser 32 may be returned
through conduit 33 to the top of the evaporator
Z’asa re?uxing medium. The partial condenser
may be omitted if desired.
vapors and liquids, similarly to the cracked prod- __ __
ucts already discussed.
A re?uxing line 55 is shown for supplying cool
ing ?uid from an external source to the evapo
rator 2 and another line 55 is shown for provid
ing cooling ?uid to the top ofthe fractionator 6,
in well known manner. Indirect cooling coils
might be used for accomplishing the same pur
pose, in which event the cooling ?uid might be
the fresh charging stock, whereby the charging
stock would be raised in temperature to aid in the
distillation thereof. The evaporator 2 is provided
with ba?ie plates, bubble trays, or other suit
able contacting means in a well known manner.
'In the fractionator or bubble tower, 6, the va
pors pass upwardly and are subjected to frac
tionation in the well known manner.
A heavy gas oil condensate is collected on the 20
trap-out tray 48 located in an intermediate level
in the evaporator 2, is withdrawn through pipe
49, into accumulator 5t, from which it is with
drawn by pump 5i and forced through cracking
coil 52 located in the vapor phase furnace 4. In 25
this coil the oil is raised to cracking temperature
and subjected to conversion into lighter products,
including lighter gas oil suitable for cracking at
higher temperatures in the vapor phase cracking
coil 39. The resulting cracked products pass "30
through the transfer line 53,. having pressure
control valve 54, into the lower portion of the
evaporator 2, and therein undergo separation into
vapors remaining uncondensed at the top of the
fractionator are withdrawn through pipe 34 and
condenser 35, the condensate formed being col
lected in receiver 35. This condensate will be
gasoline of the desired end point. vIt may be used
by itself, or it may be combined with the light
naphtha derived from the crude ?ashing oper
ation and collected in the receiver !2. Either or
both of these distillates may be stabilized, if de
sired, or be subjected to any other suitable treat
ment to give them the selected characteristics.
Re?ux condensate collects in the base of the
bubble tower 6, is removed through conduit 31,
and passed by pump 38 through the cracking coil
39. of the vapor phase furnace 4!, wherein it is
raised to a cracking temperature and subjected
to conversion, preferably in the vapor phase. The
resultingcracked products emerge from the heat
ing coil and travel through transfer line 40 into
70 the soaker or reaction chamber 5, wherein they
I have indicated all of the cracked products from
the several cracking and reforming coils 39, 45
and 53, as entering the evaporator 2 through a
common connection. Instead all of the pipes 4|,
I16 and '53 might connect separately with the evap
orator. Cooling oil can be introduced into the
soaker adjacent the outlet thereof and likewise
into the various transfer lines, for ?uxing pur
poses, in a well known manner, if desired, so as to
inhibit the deposition of coke. Likewise any suit
able cooling arrangement may be provided for
maintaining the temperature of the liquid coi
lecting in the base of the evaporator 2 at a suit 60
ably low value to prevent deleterious coke deposi
tion therein.
The liquid residue collecting in the base of
evaporator 2 is withdrawn through conduit 51, ‘
having pressure reducing valve 58, and is. intro
duced into the base of the lower section M of
the crude ?ash tower i, which base serves as a
tar ?asher drum. Therein the introduced resi
due undergoes separation into vapors and un
vaporized residual stock or tar, by virtue of its 70
heating coil. The digested products emerge from
contained heat, and the reduction in pressure ef
fected by aid of valve 58. The vapors pass up
wardly through the tower l, constituting a source
of the hot vapors already mentioned, which con
75 the soaker and travel through conduit El having
tact with the partially reduced crude charging
undergo further conversion as a result of their
contained heat, preferably under substantially
the same pressure as held on the outlet of the
stock moving downwardly through the lower
portion I4 of the tower, after introduction there
into through the aid of conduit I3.
Reference numeral 60 indicates a valved line
interconnecting the transfer line 29 with the base
of the tower I whereby any desired portion of the
densate, these condensates corresponding respec
tively to the condensates collected in the base of
the fractionator 6 and the gasoline distillate so
segregated can then be combined, either with or
without previous reformation, with the cracked
hot products from the viscosity breaking furnace
gasoline collected in receiver 36 and/or the virgin
coil may be introduced directly into the crude
light naphtha collected in receiver I2, to form a
desired blended product. The heavier condensate
obtained can be introduced into the top of the 10
evaporator 2 above the tray 48, and the lighter
clean condensate can be introduced into the base
of the fractionator 6, or, if desired, both stocks
might be introduced into the evaporator above
the tray 48, or part or all ‘below the tray 48 if 15
desired, for cooling purposes. In any event the
effect would be to cause the heavy condensate to
pass through the heating coil 52 and the lighter
condensate to pass through the heating coil 39.
‘The same effect might be obtained by passing 20
both the light and heavy condensates directly
into the charging lines 49 and 31, respectively, of
the two cracking coils mentioned. In case the
vapors from the separate viscosity breaker evapo
stripping system along with the liquid residue
able for vapor phase cracking, and heavier con
10 from the evaporator 2, in order to supplyv any
additional heat necessary for the ?nal stripping
of the crude charging stock.
All desirably light cracking stock contained in
the residue introduced into the base of section 14,
15 including any naphtha components, is volatilized,
while the undesirably heavy constituents remain
in unvaporized form and are withdrawn from the
process through valved draw-off line 59. The
heaviest fractions of the generated vapors are
20 ‘condensed and collected on trap-out tray 23 for
recycling through the viscosity breaking furnace
3, while somewhat lighter constituents collect on
trap-out tray l9, and are returned to either the
evaporator or the fractionator or both, in which
25 event they are recycled through the vapor phase
cracking coil 39, in the furnace 4, along with the
other re?ux condensate collected in the base of
the fractionator 6. Any naphtha components
contained in the rising vapors ‘are withdrawn
30 through connection 16 and condenser I‘! for col
lection in the receiver l8, and for ‘recycling
through the reforming coil 45, in the vapor phase
furnace 4.
rator are fractionated, the pressure in the evap 25
orator last mentioned can be considerably lower
than that in the evaporator 2, since the con
densate stocks obtained can be pumped to their
destinations at increased pressure. On the other
hand if the pressure in the viscosity breaker 30
evaporator is maintained su?iciently high the
vapors therefrom can be introduced directly into
the evaporator 2 under their own pressure.
By utilizing two separate evaporators it is pos
By providing the several cracking coils shown, '
35 it is possible to effect the desired conversion of sible separately to extract from the process tar 35
the several oil components under the optimum
conditions. The inclusion of the trap-out tray 48
and the associated heating coil 52 assures that
the heavy gas oil, which is not suitable for crack
ing in the vapor phase furnace on account of
coke forming tendencies, can be separately con
verted under the conditions best adapted to cause
a maximum conversion thereof, without being
returned to the viscosity breaking furnace 3, for
45 conversion with the reduced crude at correspond
ingly lower conversions per pass. The provision
of the cracking coil 52 also lightens the load on
the viscosity breaking furnace 3 and .not only
permits greater through-put or reduced crude in
that furnace, but also limits the stock going
through that furnace to a greater proportion of
virgin components and to components which are
more nearly of like characteristics. The viscosity
breaking furnace 3 can, therefore, be operated
55 under the best conditions for cracking the heavy
reduced crude, while the heavy cracked con
densate collected on trap-out tray 48 may be
separately converted under conditions best suited
to its characteristics, the clean gas oil cracking
60 stock from the base of the fractionator and the
heavy naphtha from the crude ?ash tower being
separately treated in individual furnace coils, to
cause the desired conversion thereof, under con
ditions properly selected for the stocks in ques
65 tion, without consideration for other of the frac
If desired the cracked products from the vis
cosity breaking furnace may be introduced into a
separate evaporator, and only the Vapors be
70 passed to the evaporator 2, part of these being
diverted to the base of the tower l to supply
additional heat, if desired. Or alternatively the
vapors from the added evaporator may be sepa
rately fractionated in order to form gasoline
75 distillate and light clean gas oil condensate suit
from the viscosity breaking operation, and from
the cracking and reforming operations, these two
tars having di?’erent characteristics, several
different types of marketable fuel oil can be
formed by properly blending them, or the two 40
tars’ may be sold separately if desired. The sug
gested additional evaporator, fractionator, and
associated pipe lines have been omitted from the
Referring speci?cally to the furnaces 3 and 4, 45
it will be noted that the stock to be subjected to
viscosity breaking cracking is ?rst passed through
tubes in a convection section of the furnace, then
through tubes located in the radiant portion of
the furnace, and finally through soaking tubes 50
located in the cooler convection section of the fur
nace. The relatively light clean gas oil removed
from the base of the fractionator is preferably
cracked by passage entirely through radiantly
heated tubes located in one of the two radiant 55
or combustion sections of the twin ?re box type
furnace 4. The heavy gas oil withdrawn from
trap-out tray 48 is preferably passed through
a similarly located coil 52 in the other radiant
section of the furnace 4, while the naphtha from 60
the receiver IB ?rst is conducted through the
convection section of the furnace, and then
through roof tubes in the radiant section of the
furnace, 4. Obviously other flow arrangements
might be used, and other types of furnaces, like 65
wise. The heating tubes could, if desired, be lo
cated each in a separate furnace, although the
arrangement shown is preferred.
From a relative point of ‘view, the cracking
conditions on the stock charged to the viscosity 70
breaking furnace 3, the cracking coil 52, the
cracking coil 39, and the reforming coil 45, will
be increasingly more drastic in the order men
tioned. Merely by way of example, the outlet
temperature of the heating furnace 3 may be 75
890° F., more or less, the outlettemperature of
the coil 52, 940° F., more or less, the outlet tem
perature of the coil 39, 975° F., more or less, and
the. outlet temperature on the reforming coil 45
may be 1050° F., more or less.
I prefer to use the temperatures and pressures
and temperature controllers, and other auxiliary
apparatus have been omitted from the drawing
in the interest of clarity, but could be provided
in accordance with the teachings of the prior art.
While I have described a particular embodi- ~
ment of my invention, for the purposes of illus
already mentioned, for the viscosity breaking,
cracking and reforming operations, particularly
tration, it should be understood that various
modi?cations and adaptations thereof, occurring
for producing gasoline'of approximately 70 oo
10 tane number from a charging stock such as 37°
A. P. I. Mid-Continent crude, but somewhat
to one skilled in the art, may be made within the
spirit of the invention, as set forth in the ap
higher or lower temperatures and pressures may
be used, the exact conditions being determined
in each case by the character of the charging
stock and the speci?cations of the ?nal desired
products. The octane number and other charac
teristics of the ?nal desired product may be reg
pended claims.
I claim:
1. The process of treating hydrocarbon oil
which comprises separating from raw crude oil
light and heavy virgin naphtha and topped crude,
cracking said topped crude, reforming said heavy
The outlet pressures on all of the heating coils
naphtha, contacting vapors from a portion of the
cracked topped crude with said raw crude oil to
aid in the said separating step, combining another
portion of the cracked topped crude with the re
formed products and separating from the com
may be substantially the same, this being su?i
cient to maintain. a pressure in the evaporator of
bined products a gasoline distillate, a gas oil con
densate suitable for use as vapor phase cracking
ulated by varying the cracking temperature, the
cracking per pass of the individual stocks, or the
"20 total amount of cracking of these stocks;
about 200 pounds per square inch, the pressure in a
stock andaheavier condensate, cracking said con
the soaker 5 being slightly higher, and that in the
bubble tower or fractionator 6 being slightly
densates last-mentioned in separate
cracking "’
zones and'combining the resulting products with
said cracked and reformed products ?rst-men
lower. These pressures may, if desired, be dif
ferent, the necessary differential being main-, tioned prior to the separation thereof into said
tained by adjustment of the pressure control gasoline distillate and said condensates.
2. The process of treating hydrocarbon oil
valves in the transfer lines. .
It is sometimes advantageous to increase the
pressure on the reforming coil 45, for example
by several hundred pounds, to a value in the
neighborhood of from 500 to 700 pounds per
square'inch more or less.
The pressures on the
outlets of the other coils may similarly vary from
a few pounds to several hundred pounds per
square inch, but in general the pressure condi
tions speci?cally mentioned are desirable.
Similarly the temperatures may vary quite
widely, depending upon factors such as thechar
acter of the stock and the character of the ?nal
desired product. As a rule it is not possible to
state exact ‘temperatures, but as a general prop
osition the outlet temperature of the viscosity
breaking furnace coil may fall in the range of
840° to 900° F., the outlet temperature of the
vapor phase coil 39 mayfall in the range of 850°
to 1000° F. and the outlet of the reformer coil
50 may fall in the range of 1000° to 1100° F. The
outlet temperature of the heavy gas oil crack
ing coil 45 would desirably fall in between that
of the viscosity breaking heating coil, and the
vapor phase cracking coil, being, for example, in
55 the range of 850° to 925° F. The amount of con
version to products in the gasoline boiling range
per pass may be from 6% to 15%, in the viscosity
breaking coil desirably about 10%; 10% to 20% in
the heavy gas oil cracking coil 52, preferably
60 about 15%; and 15% to 25% in the vapor phase
cracking coil and soaking drum, preferably about
20%. These conversions per pass are merely in
tended for general guidance, and are not inserted
in a limiting sense.
Various valves shown on the drawing, but not
referred to de?nitely by reference numerals, are
intended for. obvious control purposes. Aux
iliary heat exchanges, cooling coils, pressure, flow
which, comprises introducing relatively heavy
charging stock comprising crude oil components
into a primary fractionating zone of a stripping
zone in countercurrent contact with a rising
stream of highly heated vapors, removing from
the primary fractionating zone unvaporized por
tions of the said charging stock and condensed
fractions of the rising vapors, passing oil so re
moved in a stream of restricted cross sectional
area through a heating zone wherein it is raised
to a cracking temperature by passing successively
through convectively and radiantly heated zones
and subjected to'conversion, introducing a portion
of the resulting cracked products into an evapo
rating zone wherein vapors separate from liquid '
residue, fractionally condensing resulting vapors
to form 'a desired gasoline distillate, a relatively
light gas oil condensate and a relatively heavy
gas oil condensate, passing said gas oil con
densates through separate heating zones in v50
streams of restricted cross sectional area and
therein raising said oils to cracking temperature
substantially only by the application of radiant
heat and causing conversion thereof, introducing
the resulting cracked products into said evaporat
ing ‘ zone, removing liquid residue from said
evaporating zone and introducing it into said
stripping zone, with an accompanying reduction
in pressure to cause the ?ashing of lighter con
stituents therefrom asgvapors, the resulting vapors
passing to said primary fractionating zone to con
stitute a source of said highly heated vapors ?rst
mentioned and introducing another portion of the
hot cracked products from said heating ?rst
mentioned into said stripping zone to serve as an '
additional source, of said highly heated vapors
first mentioned. ,
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