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March 22, 1938.,
_
D. B. _BANKS ET AL
2,111,957
METHOD FOR DEPROPANVIZING -wAX PROPANE MIXTURES v
-Filed Aug. 1s. 1955~
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METHOD FOR DEPROPANIZING WAXl PROPANE MIXTURES
Filed Aug.' 13; -1935
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March 22, 1938.,
Q_ E‘ BANKS ET AL
2,111,957
METHOD FOR DEPROPANIZING WAX PROPANE MIXTURES
» Filed Aug. 13. 1955
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2,111,957
Patented Mar. 22, 1938
UNITED Sixers
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OFFiCE
2,111,957
lvlETl-IOD FOR DEPROPANIZING WAX
PROP‘ANE MIXTURES
Daniel B. Banks, Drexel Hill, and Paul D. Barton,
Narberth, Pa., assignors to Sun Oil Company,
ì Philadelphia, Pa., a corporation of New .iersey
Application August 13, 1935, Serial No. 35,980
7 Claims. (Gl. 196-75)
The present invention relates to a process for
depropanizing wax-propane or Wax-asphalt-pro
pane mixtures formed in the propane dewaxing
of hydrocarbon oils.
insures an intimate Contact between such wax
propane mixtures and a heating medium at a tern.
>
In dewaxing hydrocarbon oils b-y methods in
volving the use of propane (with which a minor
proportion of propylene is usually dissolved) or
other liqueñed normally gaseous hydrocarbons,
such as butane, iso-butane, propylene and the
like and mixtures of the same, which will herein
after be referred to only as propane, the wax
bearing oil is lirst dissolved in propane, and the
solution thus obtained is then chilled to the prop
er Wax crystallizing temperature by evaporation
of a portion of the propane, or by indirect refrig
eration or a combination of the two chilling meth
ods. After the solution has been sufficiently
lowered in temperature, the wax separates from
the solution of oil and propane in the form of
crystals. The solution of oil and propane with
solidiñed wax suspended-therein is then filtered
or centrifuged to separate the crystallized wax
from the `solution of Wax free oil and propane,
the wax being recovered in the form of a wax
filter cake, or in the form of a wax 'slurry if the
2 Ul centrifuge method is used.
The wax iilter cake
or slurry, thus obtained, will contain, in addition
to the wax, considerable quantities of propane
and oil. If the Wax-bearing oil being dewaxed
is a mazoot or bottoms derived from a mixed
30 base crude, the wax and asphalt may be sepa
rated from the solution of asphalt and wax bear
ing oil and 'propane together, the wax usually
agglomerating around particles of asphalt. The
35
Wax-asphalt filter cake or slurry obtained from
this type of crude will contain, in addition to the
wax and asphalt, considerable quantities of pro
pane and oil.
_
In order toV prevent repetition hereinafter, it is
-40 to be understood that Where the word “wax” is
used, it is meant to include wax containing small
proportions of unseparated oil and also wax and
asphalt with or without small proportions of oil
not removed by the filtration or centrifugation.
45
Such wax-ñlter cakes or slurries or other wax
perature high enough to insure substantially
complete vaporization of the propane.
It is a further object of the invention to prc- : CIK
vide a process and apparatus whereby the depre
panized Wax mixture may be heated and re-cir
culated to vaporize the propaneV from further
quantities of Wax-propane mixtures.
In carrying out the present invention, the cold»
wax-propane mixture from the filter or other`
separating means is conducted to a chamber from
which it is fed by a multiplicity of jets, a pump
being provided for each jet. To the jets there
is also fed hot depropanized Wax. The jets are.V
so constructed as to provide a very intimate ad
mixture and Contact between the cold Wax pro
pane and hot depropanized Wax. The outlets of
these jets open into a vapor disengaging cham
ber and heater. The mixture is so broken up by u
the action of the jets as to be in a very ñnely di
vided condition, thus insuring a quick separation
or disengagement of Vthe >propane vapor. The
wax, which has been reduced to a liquid condition
by the heat so far added to it, falls to the bottom 25
oi the chamber, in which are placed steam coils
to add additional heat to the depropanized Wax,
so that a portion of it may be readily pumped
from the chamber to storage or purification
means and other portions pumped back to jets 30
for heating further ‘quantities of cold wax-pro
pane mixture.
There is provided, at one end of the chamber
into which the jets open, a bubble tower through
which the disengaged propane vapor is passed in i 35
contact with reflux comprising hot depropanized
Wax in order to remove any entrained particles
of wax. The disengaging chamber is maintained
under such pressure as will insure the condensa
tion of the propane or other solvent, when re--` 40
moved from ‘the chamber and cooled.
A better understanding of the invention will be
had by reference to the following drawings, of
which:
Fig. 1 is` a side elevation of the complete appa
l
propane mixtures present a very difficult depro
panizing problem since they are at extremely
low temperatures and do not readily conduct
heat. For instance, if a bucket is filled with the
material and placed over a steam bath, it will
ratus;
take two hoursV or more for sufficient heat to
Fig. 5 is a detail of that portion of the jet in
Fig. 4 designated by a dotted circle and marked
56X”.
Turning now to Figs. l and‘Z ofthe drawings, 55
penetrate through the wax-propane mixture to
distill off the major portion of the propane.
It is, therefore, an object of the present in
vention to provide a process and apparatus which
Fig. 2 is an end elevation of the complete ap
paratus;
. Fig. 3 is a section taken on line 3--3 of Fig. l;
Fig. 4 is a cross section taken through one of 50
the jets; and
Y
2
2,111,957
A represents a feeding chamber to which the cold
wax propane mixture is fed from the iîlters or
centrifuges. B represents the disengaging cham
CTI
ber and the heater. C represents a bubble tower
at one end of the disengaging heating chamber
for removing entrained liquid from the gaseous
propane. D represents a pressure equalizing line
between the top of chamber B and feed chamber
A. In operation, the cold wax propane mixture
10 is admitted to the feed chamber A through line
I. After suiiîcient head is built up in the feed
chamber, the material will, by its own weight,
be forced into the gear pumps 2 which rest upon
15
plate 3, forming the bottom of the chamber, a
head 4 being added below plate 3 merely to pro
vide strength.
The gear, or booster, pumps 2 are in parallel
rows, each row having a number of pumps
therein as shown in Fig. 3. Each pump feeds a
single valve controlled line 5 leading to a jet or
nozzle 6. Within the jet or nozzle 6 the cold
wax propane mixture is intimately admixed with
hot depropanized wax which is admitted to each
nozzle through lines l, fed by a manifold con
25 nection 8. Manifold connection 8 is in turn sup
plied with hot depropanized wax from the bot
tom of the chamber B, by means of line 9, pump
IQ, valved line II and line I2. When the hot de
propanized wax is brought into direct and com,
30 plete ccntact with the cold propane wax mixture,
, it heats such mixture suñiciently to render the
wax fluid, and to vaporize the propane. The
then heated mixture leaves the jets and passes
into the disengaging chamber and heater B.
35 The chamber B is surmounted by a dome I3 hav
ing a cover plate I4, to which the nozzles 6 are
aliixed. Within the dome I3 there is supported
on angle irons I5 an inclined plate I 6. Above
the plate I6 there are arranged steam coils Il.
40 On entering the dome the heated wax and pro
pane separate from each other, the wax in a
molten condition falling to the inclined plate I6
and the propane vapors passing off to the side
and down into the chamber proper between the
wall of the dome I3 and the cylindrical baffle I8
supported within and spaced from the walls of
the dome I3. The liquid wax in falling to the
plate IS passes over the steam coils I1, which
serve to heat it sufliciently to vaporize some of
the propane not vaporized in the jets or nozzles
6. The liquid wax then overflows the edge of
plate I5 into the bottom of the chamber B.
Within the chamber B proper there are placed a
series of hairpin heating coils I9, which are fixed
to a tube sheet 20, held in place by head 2I.
There is provided within the head a partition 22.
Steam is fed to one side of partition 22, passes
through the coils I 9, and is removed from the
other side of partition 22. At the opposite side
60 of chamber B there is provided a weir or parti
tion 23 which serves to maintain a predetermined
liquid level within the chamber B. When this
predetermined liquid level is reached the liquid
wax overflows weir 23 into the end chamber which
65 contains
a ñoat mechanism 24, operating
through head 25 to control valve 26 in line II.
By means of this provision, there is maintained
a constant liquid level in the major portion of
chamber B and the excess melted wax is with
drawn as it overiiows the weir 23, thereby at all
times assuring a constant level within the major
portion of chamber B. Chamber B is further
provided with a valved outlet 21 which is used
only on draining the chamber after a run or for
inspection and repair.
Such of the hot depro
panized wax overflowing Weir 23 and passing
out through line 9 as is not recirculated through
line I 2 to the jets E or tower C, is withdrawn
through iloat controlled valve to storage or wax
puriñcation apparatus.
The propane vapors, after being disengaged
from the melted wax, pass up through bubble
CI
tower C positioned at one end of the chamber B.
To the topmost trays in the tower there is sup
plied molten wax drawn from line I2, by means
of valved line 2B.
This liquid wax overñows
from tray to tray, and provides a washing medi
um through which the propane vapors must bub
ble on their way from the apparatus, thus in~
suring that all entrained wax particles are re
moved, the propane vapors passing to a con
denser (not shown) wherein they are cooled sutil,
ciently to condense them at their existing pres~
sure.
This pressure will, of course, vary with
the solvent used in the dewaxing process,
whether it be propane or, for example, butane,
or a mixture of ethane, propane and butane.
The higher boiling the solvent, the lower, of
course, the pressure required for condensation
at a given temperature.
Of the heated and depropanized wax that is
continuously
withdrawn
from
chamber
B,
through line 9 by means of pump IB, and passed
through lines II and I2, a portion is used for
reflux in the tower C, and the balance is fed- 30
through manifold 8 to line 7 and the jets 6, for
admixture with incoming cold wax-propane mix
ture. As already stated, the pressure between
the chamber B and feed chamber A is equalized
by means of valved line D.
Since the propane- .
wax mixture entering chamber A through line
I may be from _45° F. to _60° F., and since the
pressure within the tower C and chambers B and
A is su?licient to condense the vaporized pro
pane on cooling, it is evident that the propane 40
which is contained above the cold wax propane
mixture in chamber A will be in part chilled
and condensed within the chamber A above the
propane wax mixture therein. This condensed
propane may be withdrawn from time to time
through valved lines 29 set at the various levels
in chamber A and line 3U, and passed to the
lower part of chamber B wherein it comes into
contact with heated depropanized wax and is
vaporized, thereafter passing off with the balance
of vaporized propane.
50
When first starting up the apparatus, the valve
in line D is closed and cold propane wax mixture
is admitted to the chamber A, through line II.
When suiñcient head has built up in the chambery
A, an inert gas is admitted to the valved line 3I,
55
thereby creating additional pressure at the bot
tom of chamber A. The pump 9 is started, then
pump 2, it being assumed that there is already a
charge of heated and depropanized wax in cham-. 60
ber B.
As soon as the ñrst wax passes into dome
I3 of the chamber B, an atmosphere of propane
will be formed, the pressure of which will be grad
ually increased as cold wax propane mixture is
pumped from chamber A. As soon as the requi-= 65
site pressure has built up in chamber B and tower
C, the valve at the exit of the tower C is opened
and hot reñux is admitted to the trays in tower
C. The valve in line D is then opened, and the
valve in line 3l closed. The apparatus will then 70
function automatically, so long as cold wax
propane mixture is fed to the chamber A. If the
feed of the cold wax-propane mixture to chamber
A is cut down, the head in chamber A will de
crease, thereby decreasing the amount which is 75
3
2,111,957
picked up by the pumps 2 and fed to the' jets or
depropanizing nozzles S. The cold wax~propane
mixture does not function as a liquid, since it is
a more >or less gummy mass, depending on the
Cil
temperature of admission, and the proportion of
oil propane and asphalt contained therein. It
is, therefore, necessary that a considerable head
be maintained in -the chamber A, from which it
follows that the greater the head the greater the
feed to the pump 2, and the lower the head the
less the feed to pump 2, the head, of course, being
controlled automatically by the rate of admission
of cold propane wax mixture.
Referring now to Figs. 4 and 5 which illustrate
the depropanizing nozzle 6, the cold wax-propane
mixture enters the nozzle 3 through line 5 which is
tapped into bell shaped chamber 35 in top section
34 of the nozzle.
The top section all is bolted to
central section 36 by tap bolts 3l, suitable packing
38 being provided between the top and central
sections of the nozzle.
The top section 34 and
central section 36 are cut away to form an an
nular chamber 39 in the nozzle 5. Hot depre
panized wax enters 'the nozzle ß through line ‘E
which is tapped into opening 4i) leading to chame
ber 39. A cup shaped member 42 is held in a
bell shaped opening Ill, in central section 35, by
ribs 43, attached to central section 36 and cup
d2. The cup 42 has a threaded opening 55, in. the
bottom thereof, through which a shaft Ml, having
a pear shaped head 45, is screwed. By turning
shaft 44, the pear shaped head 45 may be raised
or lowered to adjust the size of the annular open
ing 46 between chambers 35 and M. Shaft lid
may be locked against rotation by lock nut 48.
An annular insert 48 is screwed into the central>
section 3B of the nozzle 5 so as to form a part of
the walls of' annular chamber 39. This insert 49
temperature of the cold wax component and the
temperature ofthe hot depropanized liquid. .
While the present invention has so far been
described only in respect to its application to de
propaniz'ing cold wax-propane and cold wax
asphalt-propane mixtures, it is apparent that it
is readily adaptable to other analogous uses.
For instance, when an asphalt bearing oil is
deasphaltized by mixing the asphalt bearing oil
with propane, or other similar normally gaseous 10
hydrocarbons having selective solvent properties
between oil and asphalt, under pressure and at
ordinary atmospheric temperatures, and the mix
ture is allowed to settle, the asphalt will precipi
tate. The solution of the lubricating oil and wax, 15
if wax was present in the original stock, in liquid
solvent is withdrawn from the pressure precipi
tator, leaving a residue of asphalt. This asphal
tic residue will contain a small amount of propane
which must be recovered in order to render the 20
operation an economic one and the asphalt ñt
for use. The method and apparatus of the pres
ent invention are very valuable for depropanizing
the asphalt-propane mixture thus obtained.
The operation of depropanizing such an 25
asphalt-propane mixture is similar to that de
scribed above in connection with depropanizing
wax-propane mixtures. The asphalt-propane
mixture is admitted to tank A through line I and
is forced by pumps 2 through lines 5 to jets or 30
nozzles B where it is mixed with hot depropanized
asphalt which is withdrawn from the bath of hot
depropanized asphalt in chamber B.
The depropanized wax-asphalt mixture or as
phalt obtained as described above. is frequently
made into a fuel oil by mixing it with gas oil to
obtain a fuel oil of the'desired characteristics as
to viscosity, flash point, fire point, etc. However,
is spaced uniformly from top section 3d by set it Vis possible to utilize the method of the present
screws 50 in insert 49 pressing against top sec - invention for'blending the gas oil with the as 40
phalt-propane mixture or wax-asphalt-propane
tion 35 so as to form a uniform annular opening
41 between chambers 39 and 4|. There are pref»
erably at least three such set screws 5i! placed
equidistantly around insert ¿i9 and held in place
by set screws 5l, used as jam screws. Insert 43
may be held against rotation by set screws 52.
An annular flange 53 is screwed onto central sec
mixture, so as to vaporize the propane and give
a fuel oil of the desired characteristics.
In case it is desired to blend the asphalt or
wax-asphalt mixture with gas oil to obtain fuel 11.5
oil, the asphalt~`propane mixture or wax-asphalt
pi‘opane mixture is admitted to tank A through
line l, and Ywithdrawn therefrom by pumps 2
tion 36 and welded thereto as at 5t. ' ‘Nozzle 6 is
forced through lines 5 to jets or nozzles 6.
connected to chamber B by bolting ñange 53 to and
Hot gas oil is admitted through valved line 32
cover plate Hl.
.
Y
The operation of the nozzle is as follows: Cold to manifold 8 and thence through lines 'l to jets
or nozzles E where it is intimately mixed with
wax-propane mixture from line 5 enters cham
the propane bearing mixtures introduced to the
ber 35 and passes through annular opening d6, in jets or nozzles 6 from lines 5, and heats the
the form of an annular stream, to chamber lil. same to vaporize a large part of the propane. 55
Hot depropanized wax from line 1 enters chamber The propane vapors separate from the fuel >oil
39 and passes through annular opening d1, also in blend of gas o-il and asphalt, or asphalt and wax,
the form of an annular stream, to chamber 4l. in the dome I3 and pass off to the side and into
The annular stream of hot depropanized wax, the chamber B and thence into the tower C‘. The
issuing from annular opening ¿il hits the annular fuel oil blend falls to the plate l5 and flows over 60
stream of cold wax-«propane mixture, issuing from the heating coils l'l which heat it and vaporize
annular opening 4B, the two streams meeting at additional quantities of propane. The liquid
high velocity at an angle of about 30°, as will be from plate i6 falls into the body of hot fuel oil
clear by reference to Fig. 4. The cold wax-pro
blend maintained in chamber B and flows over
pane mixture is thus thoroughly mixed with hot the Weir 23 and is withdrawn through line 9 by 65
65 » depropanized wax in chamber lll. Since the Vol
pump lil, a portion iiows through line VIl past
float controlled valve 25 to` storage and the re
ume of hot depropanized wax issuing from open
ing 41 is preferably'about l0 times the volume of mainder is circulated through line l2 and valved
line 2S to'tower C. The amountof gas oil ad
the cold wax-propane mixture issuing from open
ing 46, the cold. wax-propane mixture willV be mitted through line 32 will of course depend on 70
heated, by its intimate admixture with thehot the specifications for the fuel oil which it is de
depropanized wax, sufficiently to vaporize the sired to obtain and the characteristics of the ma
propane contained therein. The ration of 10 : l *ferial being blended. In case the gas oil alone
above expressed is by no means fixed. The proper does not supply su?icient heat to vaporize the
proportion is established by the composition and pro-pane, the valve 33 may be opened and part of 75
2,111,957
the hot fuel oil blend, from chamber B, which
is being circulated in line I2 may pass to mani
fold 8 with the hot gas oil and thence through
lines l to jets or nozzles 6, and thus supply part
of the heat necessary to vaporize the propane.
What we claim and desire to protect by Let
ters Patent is as follows:
1. The method of depropanizing a cold mix
ture of propane and a high boiling point hydro
carbon, which comprises continuously flowing
separate streams of said mixture and of a heat
ed high boiling point hydrocarbon toward a com
mon locus of mixing and evaporation while im
parting to both streams a substantially increased
velocity and at such velocity intimately mixing
them, thereby promoting evaporation of pro
pane by mechanically breaking up the newly
formed mixture as Well as by elevating the tem
perature of the constituents of said propane mix
20 ture and removing separated propane vapors
from said locus.
2. The method of depropanizing a cold mix
ture of propane and a high boiling point hydro
carbon, which comprises continuously flowing
separate streams of said mixture and of a heat
ed high boiling point hydrocarbon to a common
locus and thereat substantially increasing the
velocity of both streams to thus ñnely divide
and mix them and thereby, as well as by elevating
the temperature of the said propane-containing
mixture, promoting the evaporation of propane,
and conducting away the separated propane
vapors.
3. The method of depropanizing a cold mix
35 ture of propane and a high boiling point hydro
carbon, which comprises continuously flowing
separate streams of said mixture and of a heat
ed high boiling point hydrocarbon to a common
locus of mixing and evaporation while imparting
40 to both streams a substantially increased velocity
and at such velocity impinging said streams one
upon the other to thereby intimately mix and
mechanically break up as well as elevate the
temperature of said propane-containing mixture
45 and thereby promote the vaporization of pro
pane, removing evaporated propane from such
locus and immediately conveying the high boil
ing hydrocarbon together with any unevaporated
p-ropane to a pool of the high boiling hydrocar
50 bon and heating the pool and thereby effecting
evaporation of substantially all the remaining
propane.
4. The method of depropanizing a cold mix
ture of propane and a high boiling point hydro
~55
carbon, which comprises continuously ilowing
separate streams of said mixture and of a heat
ed high boiling point hydrocarbon to a common
locus of mixing and evaporation while imparting
to both streams a substantially increased velocity
and at such velocity impinging said streams one
upon the other to thereby intimately mix and
mechanically break up as well as elevate the
temperature of said propane-containing mixture
and thereby promote the vaporization of pro
pane, still further raising the temperature of
the finely divided new mixture and conducting
away evaporated propane, and conveying the
high boiling hydrocarbon together with any un 10
evaporated propane to a pool thereof and heating
the pool to thereby eiîect evaporation of substan
tially all the remaining propane,
5. The method of depropanizing a cold mix
ture of propane and a high boiling point hydro 15
carbon, which comprises continuously flowing
separate streams of said mixture and of a heated
high boiling point hydrocarbon toward a locus
of mixing and evaporation and thereat imping
ing them one upon the other by discharging them 20
through two concentric annular adjacent open
ings of restricted width to thereby impart to both
streams a` high velocity and mechanically break
up the said propane mixture and promote evapo
ration of propane.
6. The method of depropanizing a cold mix
ture of propane and a high boiling point hydro
carbon, which comprises continuously flowing
separate streams of said mixture and of a heated
high boiling point hydrocarbon toward a locus
of mixing and evaporation in the form of two
concentric annular adjacent streams of progres
30
sively decreasing width to thereby impart to both
streams a high velocity and effect the intimate
mixture of said adjacent concentric annular high
velocity streams to thereby mechanically break
up the said propane mixture and promote evapo
ration of propane.
7. The method of depropanizing a cold mix
ture of propane and a high boiling hydrocarbon 40
which consists in ñowing separate streams of said
mixture and of a heated high boiling hydro
carbon to an expanded space constituting a com
mon locus of evaporation and thereat simul
taneously mixing the streams and elevating the
temperature of the constituents of the cold mix
ture, with consequent evaporation and separa
tion of propane, ñowing the mixture of hydro
carbons through said locus to» a pool of such
hydrocarbons and in the course of its ñow
through said locus and in said pool successively 50
heating the hydrocarbons, with consequent fur
ther evapioration and separation of propane,
thereby separating substantially all of the pro
pane, and immediately conducting away the pro
pane vapors from said locus and pool.
DANIEL B. BANKS.
PAUL D. BARTON.
55
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