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Патент USA US2117464

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‘May 17, 1938.
J. w. THROCKM'ORTON
2,117,464
THERMOLYTIC CONVERSION OF HYDROCARBON GASES TO LIQUID
Filed July 23, 1937
‘
INVENTOR
_
“John WBYThrac/rmorton
2
F ATTORNEY
2,117,464
Patented May 17, 1938
‘v , UNITED STATES
PATENT OFFICE
2,117,484
THERMOLYTIC CONVERSION OF HYDRO
CARBON GASES
LIQUID
John W. Throckmorton, New York, N. Y., as
si‘gnor to The Pure 01! Company, Chicago, 111.,‘
a corporation of Ohio
Application July 23, 1937, Serial No. 155,152
12 Claims. (Cl. 196-10)
In order to more fully comprehend the nature
Y ‘This‘invention‘relates to method and apparatus
and scope of the invention, reference, should be
for‘ converting hydrocarbon gas to liquid hydro
carbons and is‘ more particularly concerned with had to the following description together with
method and ‘apparatus for efficiently converting
5
hydrocarbongas mixtures into gasoline type hy
drocarbons.‘
f“
i
'
'
“ In the‘operation of thermolytic gas polymeriza
tionprocesses it is difficult to obtain complete
conversion of the‘reactable constituents in a one
10 stepsystem without the necessity of high recycle
ratios. ‘ But‘ v‘high recycle
ratios
mean
low
throughput lwithv‘vresultan't low output and high
operating cost. “
‘In accordance with this invention the charging
gas is fractionated so as to separate the C2 hydro
carbons and vlighter gas from a fraction contain
mg C: and heavier hydrocarbons. The latter
fraction is charged through suitable heating and
reaction zones‘iseparate from the light fraction,
wherein it is subjected to suitable conditions of
time,‘ temperature ‘and pressure to convert a sub
stantial portion togasoline boiling hydrocarbons.
W'I‘he‘light fractionjmay or may not be further
fractionated to remove the lightest constituents
25 suchas hydrogen and methane, and then charged
‘toaseparatecracking coil preferably operated
at higher temperatures and lower pressures than
we coil to whichjtheh'eavy fraction is charged.
the accompanying drawing of which -
The single ?gure is a diagrammatic elevational 5
view of apparatus suitable for carrying out the in
vention.
_
Referring to the drawing, the numeral l indi
cates a line through which fresh gas is charged
to the system by means of pump or compressor 10
3. The charging gas may be natural or cracked
gas, gas from a liquid or vapor phase 011 crack
ing operation, or other gas containing a. substan
tial amountlof Cs and. C4 hydrocarbons. The
charging gas is ‘then pumped through line 5 and 15
cooler ‘l to gas and liquid separator 9. If the
charge is gaseous it may be compressed in com
pressor 3 to a’ pressure of approximately 150-350
pounds per square inch and cooled to a tem
perature of 80°-100° F. before entering the gas
separator. ‘If the charge is liquid, the samecon
dltions of temperature and pressure should be
maintained.
The liquid fraction consisting chie?y of C: and
C4 hydrocarbons is withdrawn from the lower
part of the gas separator through line I I by means
of pump l3, and may be charged through line
I 5 controlled by valve II, to the inlet of coil l9
In ‘t e'cracking'co conversion of gas to liquids' located in furnace 2| at a pressure ranging from
and, to‘ olefins‘vtakesffplace. The desirable por
tion’s ,ofjthereajcte gas are absorbed in a liquid
‘oil mén‘scmumfap "the rich oil used to chill the
reaction‘produets‘f-froin the high pressure coil.
Thefcombined, prtxluct'sv are then fractionated
mixed with the fresh
35 and“ the resultinglgas
30
charge.‘ ‘In this‘lma‘nnerg the desirable portions
of‘the gases‘from‘th‘ereaction zone are recovered
and mixed ‘withfthe fresh gas after elimination
40
46
The pressure, under which the charge to the.
coil I9 is maintained, will depend largely upon
the composition of the charge and upon the
product desired. If the charge contains sub
39
stantially only saturated hydrocarbons, pressures 35
of approximately atmospheric to 250 pounds per
square inch and temperatures of approximately
l200°-1300° F. will be preferably maintained with
?nished gasoline'is “obt "tied all in a single op
a short reaction period in order to convert the
saturated hydrocarbons to unsaturates. In such 4.0
case the products, after leaving the heating coil,
el‘iti?n‘By
.,
. ajjtw‘o
._ "step‘op'eration of the type
fresh charge which is by-passed through line 26
above ’described'the‘recycle “in the high pressure
coil ‘may be“ maintained ‘between the limits of !/2
controlled by valve 21 to a temperature of ap
proximately 10'75°—1200° F. and then passed to
a reaction coil or chamber 29 maintained under
substantially the same pressure as‘ the cracking
of the ‘iixed gas‘, ,lowin polymerizable constitu
ents,‘,_ifrom‘ the ,syste‘nigiandf a] uniform blend of
‘ '
"
_
50
200-3000 or more pounds per square inch.
‘
H
'
i
‘
lefg‘astolf part of fresh gas,
recycle ratio in the low pres
surefc‘oil: 1‘ Moreovergthejyse of the two step sys
tem‘enable‘s" the‘maintenance of optimum condi
tions’forlthe productscharged to each coil, re
may be chilled at 23 by means of a portion of the
coil, wherein the products are given su?icient
time to polymerize to hydrocarbons boiling within
the gasoline range. ~ The reaction coil 29 is pref
greatlylau‘gmentemand ‘operating costs are cor
erably provided. with means for controlling tem
perature. For this purpose the coil’ or chamber
may be enclosed in a suitable vessel through
respondingly‘lideci'eased ‘beleause of lower over
which a draft of air, combustion gases, or other
sulting‘in‘ longe'frim'sTwitheutexcessive coke for
mation.“ The‘ throughputiandjgasoline yield are
head“-
i
-
50
heat exchange or cooling means ‘may be passed. 55
2
2,117,464
If the charge to the coil I9 contains approxi
mately 20% or more of oleflnic hydrocarbons, it
may be heated in the coil I9 to a temperature
between approximately 800°-l050° F. under pres
sure of 500-3000 or more pounds per square inch,
and these temperature and pressure conditions
maintained in the reaction coil; or if it is de
sired to produce primarily aromatic hydrocar
bons, the charge may be maintained under a
10 pressure of approximately atmospheric to 250
pounds per square inch and at temperatures of
1075°-12oo° F.
The products issuing from the reaction coil
29 may be suddenly chilled to a temperature of
15 approximately 600° F. or lower by direct contact
with an intermediate oil fraction formed in the
system and which is injected into the issuing
products at the point 3I. Depending upon the
pressure maintained in the reaction coil, the
20 pressure on the reaction products may or may
not be reduced at the valve 33 and the products
then passed into the lower portion of fractionat
ing tower 35., The temperature of the reaction
products, after chilling, should be high enough
25 to permit fractionation thereof without addition
al heating.
The reaction products are separated in the
fractionating tower 35 into residual oil, an inter
mediate fraction boiling above the gasoline range,
which is collected on the plate 31, gasoline boil
ing hydrocarbons which are collected on the
plates 39 and ‘I, and residual gas which comes
over the top of the tower through line 43. The
residuum is withdrawn from the bottom of the
35 fractionating tower through line 45 controlled by
valve 41, at which the pressure is reduced to ap
rator 93 is recycled through line 95 by means of
pump 91, as re?ux, to the upper portion of the
fractionating tower 35. The gases which remain
uncondensed are withdrawn from the upper por
tion of the separator 93, through line 99, and
join the fresh gas in the line 5, to be reprocessed.
The gases which are not lique?ed in the sepa
rator 9 are withdrawn from the top thereof
through line IOI controlled by valve I03 and
charged to the inlet of the cracking coil I05 lo
cated in the furnace I0‘I. If desired, the gases
withdrawn through the line I0l may be further
fractionated by being by-passed through line I09,
compressed by compressor III, and charged to
separator I I3. In this manner the hydrogen and
methane may be eliminated from the gas prior
to charging to the cracking coil. The gases will
be compressed in compressor III su?iciently to
liquefy the C2 fractions in order to separate them
from the hydrogen and methane which are elimi
nated from the system through line II5 con
trolled by valve II'I. The lique?ed C2 fractions
may be withdrawn from the separator II3,
through line II9 controlled by valve I2I, and
charged to the inlet of the cracking coil I05.
When the gases charged to the cracking coil
I05 are not further fractionated they are pref
erably charged thereto in the gaseousstate under
pressure of from 50-100 pounds per square inch.
The gases may be heated in the cracking coil to 30
temperatures of l200°-1600° F. The temperature
and pressure conditions maintained in this coil
I05 will be those most suitable for obtaining
maximum yield of gasoline boiling hydrocarbons.
If the fraction removed from separator 9 through 35
line IN is low in ole?nic hydrocarbons, high
proximately atmospheric pressure, and the oil is
temperatures and low pressures, such as those
?ashed in flash tower 49 into vapors and tar.
The residual tar is withdrawn from the ?ash
40 tower through line 5|, by means of pump 53,
the coil I05. If the ole?nic content of these gases
through cooling coil 55, to-any suitable place of
storage. The vapors are withdrawn from the
?ash tower through line 51 and condenser 59
into separator 6|. Any uncondensed material is
45
withdrawn from the separator 5|‘, through line
53, and eliminated from the system. The con
densate is recycled through line 55, by means of
pump 51, to an intermediate portion of the frac
tionating tower 35, as reflux. This re?ux pref
60 erably enters the tower at a point intermediate
the trays 31 and 39.
v
The gasoline boiling constituents are with
drawn from the fractionating tower through line
59 controlled by valve ‘II and line ‘I3 controlled
a GI by valve ‘I5 and pass through a common line 11
into a stripper ‘I9. In the stripper light hydro
carbons, such as C: and a portion of the C4
hydrocarbons, are vaporized and taken overhead
through the line 8|. The stripper ‘I9 is prefer
ably provided with suitable fractionating plates
and heating means in order to stabilize the gaso
line. The stabilized gasoline may be withdrawn
from the stripper through lines 53 and 85 and
passed to storage through line 91 controlled by
valve 99.
The pressure in the fractionating tower 35 is
preferably maintained at approximately 175-250
pounds per square inch and the temperature at
the top of the tower is‘ maintained su?iclently
70 low to condense the major portion of the gasoline
fraction. vThe incondensible gases together with
a small amount of uncondensed gasoline va'pors
leave the fractionating tower 35 through line 53,
then pass through condenser 9|, into gas and
75 liquid separator 93. 'The condensate from sepa
above mentioned, are preferably maintained in
is suillciently high, that is, above approximately 40
20%, it may bev advantageous to further frac
tionate them to remove the hydrogen and meth
ane, and charge the remaining gas in the liquid
or gaseous phase to the coil I05. If liquid phase
charging is employed, the pressures maintained 45
in the coil I05 may be 500-3000 or more pounds
per square inch and the temperatures preferably
between 700° and 1000° F. If the ole?n content
is su?lciently high to avoid necessitating further
fractionation, the gases charged to the coil I05 60
may be maintained at low pressures of approxi
mately atmospheric to 250 pounds per square
inch and at temperatures of approximately
l100°-1200° F. It will be understood, however.v
that these conditions of temperature and pres
sure may be varied in accordance with the com
position of the charge to the coil. The reaction
time will vary with the pressure and temperature
conditions maintained. Generally the reaction
time will vary directly with the pressure and in 66
versely with the temperature.
In the coil I05 cracking and/or polymerization
of the gases take place in the formation chie?y
of liquid hydrocarbons and ole?nic gases. The
reaction products issue from the cracking coil
through the line I23 and are suddenly chilled by
direct contact with an intermediate condensate
formed in the process, which is introduced into
the line I23 at the point I25.-_ The partially
chilled reaction products are further cooled by
passing through the cooling or condensing coil
I21, and then pass through line I29 controlled by
valve I3I, into gas and liquid separator I33.
From the separator I33 any liquid products are
withdrawn through the line‘ I35 by means of 75
“
2,117,464
pump I 31. The gases are withdrawn by means
of the compressor I39 through line Ill and cool
ing coil I43 and charged to the lower portion of
the absorber I45.
-
Intermediate condensate substantially boiling
within the range of gas oil is withdrawn from
3
lighter gases and eliminating them from the sys
tem, ‘charging. the remainder of the reaction
products resulting from said conversion of the
lighter gases to a common fractionating zone
together with the reaction products of the C1. C4 '
hydrocarbons‘. separating the incondensible gases
the fractionating tower 35 through line I" by from the normally liquid hydrocarbons, and unit
means of pump I49 and passes through cooling ing the incondensible gases with the fresh gas
.
coil Iii. From the cooling coil Iii a portion of . ‘ prior to separation thereof into fractions.
the condensate passes through line I53 and valve -
iii to the line I23 where it is injected into the
reaction products from the coil I05 in order to
cool these products below reaction temperature.
The remaining portion of the condensate passes
through line I51 controlled by valve I59 into the
15
upper portion of absorber I45 wherein it passes
counter-currently to the gases entering the bot
tom of the absorber. The pressure in the ab
sorber may be preferably between 175—225 pounds
per square inch and the temperature approxi
20 mately 75°-100° F. Under these conditions of
temperature and pressure substantially all the
Ca and heavier hydrocarbons will be absorbed as
well as a substantial portion of the C: hydro
2.__.The process of converting gas mixtures, con
taining chie?y C2, C: and C4 hydrocarbons, to liq
uid hydrocarbons which comprises separating- the
10
mixture into a fraction containing chie?y C: and
C4 hydrocarbons and a fraction containing C2
and lighter gases. subjecting each fraction in a 15
separate zone to suitable conditions of time. tem
perature and pressure to convert a substantial
portion of the gaseous constituents to liquid hy
drocarbons boiling within the gasoline range, sepé
arating the resulting. products from the lighter 20
‘ fraction conversion into liquids and gases, con-.- ‘
taoting the gases imder pressure with absorber
oil in order to absorb the major portion of the
C3 and C4 hydrocarbons, charging rich‘absorber
carbons, mainly ethylene. The hydrogen, meth-h oil into a common fractionating zone with the
25 ane and the main portion of vthe C2 hydrocar
reaction products of the C3, C4 fraction, separat
bons are eliminated from the absorber and from \ ing normally gaseous hydrocarbons from the
the system through line IGI controlled by, valve
I63.
Rich oil leaves the bottom of the absorber
30 through line I65 and is charged by pump I61
through line I69 into line. I'll. The liquid hydro
carbons from the separator I33 join the rich
oil in the line I60. rI'he stream of rich absorber
oil together with the liquids from separator I 33
35 may be split in the line ill, a portion passing
through valve I13 and entering the line 30 at the
point iii in order to chill the reaction products
below reaction temperature, and another portion
passing through the valve I15 into the interme
40 diate portion of the fractionating tower above the
normally liquid hydrocarbons in said fraction
,ating zone, and mixing the normally gaseous hy
drocarbons with fresh gas prior to separation 30
thereof. into fractions.
3. Process in accordance with claim
in which
the rich absorber oil is used to chill‘the reaction
products of the C3, C4 fraction ‘below conversion
temperature, and the chilled mixture charged to 35
the common .fraotionating zone.
4. Process in accordance with claim 2 in which
the liquid reaction products from the conversion
of the C2 and‘lighter gases are charged to the
common fractionating zone.
40
5. Process in accordance with claim 2 in which
a‘condensate heavier than gasoline is withdrawn
plate 31 to act as re?ux.
‘
i
In the fractionating tower the absorber oil is from the fractionating zone and cooled, and a
stripped of its gases which pass over from the - portion of the cooled condensate used to chill the
reaction products of the C2 and lighter gases be 45
tower through line 43 and are processed as here
45
tofore described.
‘
low reaction temperature and another portion
By virtue of the fact that substantially all the used as the absorption menstruum.
6. Process in accordance with claim 2 in which
C2 and lighter gases. are eliminated from the
charge to the‘ coil I9, the recycle ratio to this the gas mixture charged to the process contains
a substantial proportion of C3 and C4 olefins, and 50
coil is kept low allowing for a greater through
'50 put of fresh charging stock. Moreover, the elim
in which the C3, C4 fraction is subjected to con
version at temperatures of 800°-1050° F. and at
ination of these light gases permits the main
tenance of those conditions in the coil I9 and pressures above 500 pounds per square inch while
reaction coil'29 which will produce the maximum the C2 and lighter gas fraction is subjected to
amount of desired product. The C2 and lighter conversion at temperatures between 1200" and 55
55 fractions, after having been subjected to a com
1600” F. and under pressures below 100 pounds
bined cracking-polymerization operation, or to per square inch.
'7. Process in accordance with claim 2 in which
polymerization alone, in the coil I05, are sub
stantially eliminated from the system through the gas mixture charged to the process is rich
the line I6I, only a relatively small portion there ‘ in ole?ns and in which the fraction containing 60
60 of being absorbed in the absorber and recycled
the lighter gases is further fractionated to re
move methane and hydrogen, and the remainder
to the system.
of the fraction is subjected to temperatures be
What is claimed is:
1. The process of converting gas mixtures, . tween 700° and 1000“ F. under pressures above 500
containing chie?y C2, C3 and C4 hydrocarbons, to pounds per square inch while the C3, C4 fraction 05
65 liquid hydrocarbons which comprises separating
is subjected to temperatures of approximately
1075°-1200° F. under pressures up to approxir
the mixture into a fraction containing chie?y Ca
mately 250 pounds per square inch.
and C4 hydrocarbons and another fraction con
8. Process in accordance with claim 2 in which
taining C2 hydrocarbons and lighter gases, sub
the gas mixture charged to the process is rich 70
jecting each fraction in a separate zone to suit
70 able conditions of time, temperature and pres
in ole?ns and in which the fraction containing
sure for converting the gaseous constituents to
liquid hydrocarbons boiling within the gasoline
boiling range, separating the bulk of the C2 and
75
lighter gases from the reaction products of the
the lighter gases is further fractionated to re
move methane and hydrogen, and the remainder
of the fraction is subjected to temperatures be
tween 700° and 1000° F. under pressures above 75
4
2, 1 17,484
500 pounds per square inch while the C3, C4 frac
tion is subjected to temperatures of approxi
mately 800°-l050° F. under pressures above 500
- pounds per square inch.
9. Apparatus for converting hydrocarbon gases
absorber oil directly to said fractionating means.
11. Apparatus in accordance with claim 9 in
cluding means for collecting heavy condensate
in said fractionating means, means for with
to liquid hydrocarbons comprising means for sep
drawing said heavy condensate and contacting a
portion thereof with hot reaction products from
arating gases into a light fractionv and a heavy
fraction, means 'for charging mixed gases to said
separating means, a heating and reaction means.
means for charging said light fraction to said
heating and reaction means, a second heating
said heating‘and reaction means, and means for
charging another portion of said condensate to
said absorption means.
12. The process of converting gas mixtures, 10
means and ‘a second reaction means connected
containing chie?y C2, C3 and C4 hydrocarbons, to
liquid hydrocarbons, which comprises separating
thereto, means for charging said heavy fraction
to said second heating'means, means for cooling
the reaction products from said ?rst heating and
the mixture into a fraction containing chie?y Ca
and C4 hydrocarbons and another fraction con
taining C2 hydrocarbons and lighter gases, sub 15
.reaction means, means for separating normally
jecting each fraction in a separate zone to suit
liquid from normally gaseous constituents in said able conditions of time, temperature and pressure
cooled products, means for contacting said gas
for converting the‘gaseous constituents to liquid
eous constituents with absorber oil under such hydrocarbons boiling within the gasoline boiling
conditions as to absorb substantially only the range, separating the bulk of the C: and lighter
heavier portions of said gaseous constituents, gases from the reaction products of the lighter 20
means for eliminating the unabsorbed constit-' gases and eliminating them from the system,
uents from the system, means for contacting the charging separated normally gaseous andnor
rich absorber oil with the hot reaction products mally liquid reaction products resulting from said
from said second reaction means in order to par
‘ conversion oi’ the lighter gases to a common frac
tially cool said products, means for fractionating tionating zone together with the reaction prod
the partially cooled products in order to separate ucts of the C3, C4 hydrocarbons, separating the
the normally gaseous from the normally liquid
constituents, and means for uniting the last men
tioned normally gaseous constituents with the
fresh gases charged to the system.
10. Apparatus in accordance with claim 9 in
cluding means for charging a portion of said rich
incondensible gases from the normally liquid
hydrocarbons, and uniting the incondensible
gases with the fresh gas prior to separation there
of into fractions.
,
‘
JOHN W. THROCKMORTON.
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