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Патент USA US2119733

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June 7, 1938.
Au. B. BRAY
PROCESS FOR DEWAXING OILS> _
Filed July 2, 1934
2,119,733
Patented June 7, 1938
ÚNETE
¿ears
STE"
ortica
2,119,733
PROCESS F01?, DEWAXING OILS
`
UlricB. Bray, Palos Verdes Estates, Calif., as
signer to Union (lil Company of California,
Los Angeles, Calif., a corporation of California
Application July 2, 1934, Serial No. 733,422
17 Claims.
rl‘he present invention relates to a process for
the same. More specifically, it relates to a process
for separting asphalt and wax from oils by means
which have been mixed with a liqueiied normally
gaseous hydrocarbon. While mixture of oil and
diluent is chilled t0 precipitate the Wax in the
presence of the asphalt and the precipitated as
of solvent.
phalt and wax separated as a mixture from the
separating asphalt and wax from oils containing
-
(Cl. 196-18)
>
In my co-pending application Ser. No. 466,189,
ñled July 7th, 1930, I disclosed a process for sep
arating asphalt and Wax from oils containing
the same. In this process, crude oil, after topping
the light oils such as gasoline and kerosene, Was
commingled with a liquefied normally gaseous hy
drocarbon such as propane, under a superatmos
pheric pressure suñicient to maintain the propane
in the liquid state. The mixture was then al
solution of oil and diluent.It has also been found that When a considerable
amount of high molecular Weight propane in
soluble tars or asphalt is carried into the pro
pane solution at, say 90 to 120° F. by virtue of
the presence of 20 to 40% of oil in the propane
solution, a large portion of the dissolved tars or
asphalt precipitates in the devvaxing `stage by
cooling to low temperatures so that the wax cake
lowed to settle under pressure to permit settling ' or slurry is badly contaminated with a heavy`
of asphalt precipitated from solution. The oil
solvent solution free from asphalt but contain
ing the Wax Was decanted from the settled asphalt
and passed into a chiller Where a portion of the
propane was vaporized under reduced pressure
which accomplished a reirigerative effect on the
remaining oil, Wax and propane and caused the
precipitation of the wax. By reducing the pres~
sure to approximately atmospheric, the oil Was
25' chilled to about _40° F. The precipitated Wax
was separated from the oil and residual propane
by centrifuging and then the Wax-freesolution
was heated to vaporize the propane leaving be
hind a lubricating oil substantially free from
30 both asphalt and wax.
In my co-pending application Ser. No. 659,855,
filed March 6th, 1933 which has been issued as
Patent No. 2,010,008, I disclosed that the eiliciency
of asphalt separation with propane increased as
35 the propane to oil ratio was increased. The high
er the propane to oil ratio the more e?icient is
the separation between the oil and the asphalt.
This was evidenced by the fact that greater quan
tities of asphaltic and semi-asphaltic materials
40 were recovered at the higher propane to oil ratios.
In my application, Serial No. 611,933, now U. S.
Patent Number 2,031,095, I have disclosed the use
of an asphalt material to promote the crystalli
Zation of the Wax contained in an oil containing
45 the same. The material is added to the Wax bear
ing oil which does not contain a sufficient amount
resinous impurity which seriously interferes With
the handling of the Wax upon the filter or in
other operations. The precipitation or“ a small
amount of these propane insoluble materials
along With the wax is beneficial as regards filtra
tion and settling characteristics of the wax but
an excessive amount is deñnitely detrimental. On
account of the equilibrium involved there appears
to be little likelihood, however, of so completely
deasphaltizing or de-tarring a stock with propane
that the benefit of having some asphaltic mate
5.
rial present in dewaxing is completely lost by
simple propane extraction with a high ratio of
propane.
It is, therefore, apparent that it is desirable to 30
deasphaltize or Ole-tar heavy oil stocks as com
pletely as possible with a relatively high propane
to oil ratio before proceeding with the devvaxing
of theoil solution.V However, economical con
siderations have restricted conditions to relative
ly loW propane ratios in the initial propane solu
tion or extraction of the stock for the purpose of
separating the asphaltic material.
This is be
cause the initial amount of propane requiredV to
chill the oil to precipitate Wax by evaporative
refrigeration and to leave an adequate amount
of propane at the completion of the chilling op-v
eration to provide good settling or filtration char
acteristics to separate the precipitated wax is
rarely over 6 or 'l volumes of propane to one of 45
the oil. For example, if a mixture of 6 volumes of
of the asphalt to promote crystallization of the propane to one of oil and Wax ata temperature
wax and the mixture is blended with a liquefied ~ of 90° F. was chilled adiabatically by vaporization
normally gaseous hydrocarbon such as propane. of propane under gradually reducing pressure
50 The mixture is then chilled to precipitate the conditions and at a rate, for example, of 3° F. per
Wax and the asphalt and Wax is separated from minute, the amount of propane vaporized to chill
the solution to _40° F. Would comprise about 3
the diluted oil.
In my application, Serial No. 610,130, now U. S. »volumes leaving about 3 volumes of propane in
the chilled mixture. The latter amount is more
Patent No. 2,049,046, I disclosed the co-precipita
55 tion of asphaltic material and Wax from oils than suûicient to provide good settling or'ñltra
2
2,119,733
tion of the chilled mixture. However, if a topped
crude containing approximately 25% asphaltic
materials precipitable at 90° F. with a propane to
oil ratio of about 12 to 1, the propane to oil ratio
of the mixture upon completion of the' deasphalt
izing operation and as the solution enters the
chiller would be in the neighborhood of about l5
or 16 to 1. This amount of propane is far in ex
cess of that required to chill the oil down to _40°
F.
Furthermore, aside from the fact that the
cost of handling such a large amount of propane
based upon the amount of oil treated is prohibi
stream of asphalt precipitating solvent, prefer
ably a liquefied normally gaseous hydrocarbon
which is taken from storage tank 5 via line 6
controlled by valve 1 by means of pump 8 which
forces the solution through line 9 into line 2. It
will be observed that bythe term “asphalt”, I
intend to inclule such substantially wax-free 10
fractions which will precipitate or separate from
oils when such oils are commingled with liquid
tive for commercial operations, the ñltrate would
propane or other solvents.
contain an excessive amount of propane» which
dissolves an appreciable amount of the wax even
clude asphalty or bitumen and/or heavy viscous
oil fractions, malthas, pseudo asphaltic mate 15
rials, tars and dark coloring bodies.
The oil solvent solution is passed through tur
at _40° F. so that the pour point of the oil is high
upon separation of the propane.
It is an object of the present invention to pre
sent a process for separating asphalt and Wax in
20 which all of the benefits of a very high propane
ratio on heavy oil stocks is obtained without the
necessity of standing the cost of such high pro
pane to oil ratios.
It is another object of my invention to separate
Such fractions in
bulence coil or mixing coil l0 and then into de
canter ll where asphalt precipitated from solu
tion by means of the liquefied hydrocarbon is 20
allowed to separate and settle to the bottom of
the decanter H.
For the purpose of precipitating the asphalt
from solution, I may employ any of the liquefied
high propane to oil ratio and then separate the
normally gaseous hydrocarbons comprising 25
methane, ethane, propane, butane, iso-butane or
wax from the solution at a low propane to oil
mixtures thereof. Such hydrocarbons are vola
ratio.
Another object of the invention resides in dis
solving the heavy asphalt and wax containing
stock at a high propane to oil ratio sufficient to
remove substantially all of the asphaltic and
tile at atmospheric temperatures and pressures.
If desired, I may employ the normally gaseous
hydrocarbons obtained by rectification of casing 30
head gasoline by the so-called stabilizing method
ì the asphalt from oils containing the same at a
30.
distillate cylinder stock or a residual stock is
drawn from tank I by pump 4 and is passed into
line 2 controlled by valve 3 where it meets a
dark coloring bodies from the oil, separating the
asphaltic material precipitated from solution and
then adding a quantity of waxy oil which is sub
stantially free from asphaltic material so as to
lower the propane to oil ratio on the resulting
mixture and subsequently dewaxing the mixture.
It is a particular object of my invention to sep
40 arate tarry matter from heavy lubricating oil
now conventional in the natural gasoline in
dustry. Such fractions may comprise the over
head fractions of the stabilizing process. 'I'he
gaseous fractions may be liquefied by compres 35
sion and cooling and are drawn oif into pressure
chambers where they are maintained in the liq
uid state until they are used. A fraction of this
character may comprise essentially propane
which, however, may contain other gaseous hy 40
stocks such as from overhead heavy or viscous
distillates containing wax or substantially free
drocarbons as ethane, iso-butane and butane.
Instead of employing a liquefied normally gaseous
from wax with a sufficient amount of a liquefied
hydrocarbon for the purpose of precipitating the
normally gaseous hydrocarbon diluent as pro
pane and then add a clean waxy stock to the de
tarred heavy stock and propane, preferably a
light or less viscous waxy overhead lubricating oil
asphalt, I may also use other solvents which are
capable of dissolving the oil and wax from the 45
raw stock but which will precipitate the asphalt.
Such solvents may comprise alcohol, mixtures
of alcohol and ether, acetone or volatile hydro
carbon solvents such as casinghead gasoline and
light naphthas. I find, however, that the process 50
is best carried out by the use of liquefied nor
distillate substantially free from asphaltic, tarry
or coloring bodies in an amount sufficient to lower
50 the amount of propane in the resulting mixture
to within a range which is merely sufficient to
chill the mixture of oils to a dewaxing tempera
ture by vaporization of a portion of the propane
and yet to leave a sufûcient amount of propane
DI C): in the chilled mixture to provide good filtration or
separation of precipitated wax from solution,
then chilling the mixture to a devvaxing tem
perature and separating precipitated wax from
the remaining propane and oils and finally sep
60 arating the propane from the oils and then, if
desired, separating the oils into heavy and light
fractions such as by distillation. A particular
advantage of treating oils in the above manner
resides in the fact that the heavy distillates act
in such a manner to alter the character of the
Wax in the light distillate so that when precipi
tated at low temperatures, the wax may be rap
idly filtered.
Other objects and advantages of my invention
p will be apparent from the following description
of the drawing which represents a schematic ar
rangement of apparatus for carrying out my
invention:
.
Referring to the drawing, an oil containing as
phalt and also wax, such as a heavy overhead
mally gaseous hydrocarbons, preferably liquid
propane, in the ratio of approximately 10 to
20 volumes of propane to one of the oil and in
the present discussion of my invention, I shall
describe the process employing propane although
I do not wish to be specifically limited thereto.
A superatmospheric pressure is maintained in
decanter Il sufficient to maintain the propane
and oil in the liquid state at the temperature in 60
decanter H. Decanter Il and solvent storage
tank 5 are maintained at substantially the same
pressure by means of equilibrium line l2 con
trolled by valve I4. For the solvent given above,
i. e. propane, this pressure should be about 125 65
lbs. per square inch when a temperature of about
75° F. is maintained in decanter Il. At higher
temperatures, the pressures Will be correspond
ingly higher.
The asphalt precipitated from solution by 70.
means of propane and settling to the bottom of
d-ecanter Il is removed as a slurry of asphalt
containing oil and propane. This asphalt slurry
is removed via line l5 controlled by' valve I6
by means of pump I1 which forces the slurry via 75
3
2,119,733
line i8 through heater I9 Where the mixture is
heated to a sufficiently high temperature to melt
the asphalt and vaporize the residual propane.
This mixture is then l'lashed via valve 2l on line
2U into vaporizer 22 which is operated at a lower
pressure. Superheated steam is introduced into
vaporizer 22 via line 23 to supply additional heat
and to reduce the asphalt to proper speciñcation
generally only as regards flash and lire points.
10 The overhead from vaporizer 22 is sent through
line 24 to cooler 25 where the water and oil va
pors are condensed which then pass via line 25
into separator 21.
Any condensed light oil in
separator 21 is withdrawn through line 28 con
15 trolled by valve 29 and condensed water is with
drawn via line 30 controlled by valve 3 l. The un
condensed propane fro-m separator 21 is sent
through line 32 controlled by valve 33 to the suc
tion of compressor 34. Also, the propane vapor
20 ized in other apparatus in the process, as will be
described, will be sent to compressor 34. The
propane is compressed in compressor 34 Where the
pressure is raised so that in the high pressure sys
tem and the compressed propane is passed via
25 line 35 to condenser 36 Where the propane lique
ñes and thence passes via line 31 to propane stor
age tank 5.
The asphalt is withdrawn from the bottom of
vaporizer 22 Via line 38 controlled by valve 39 by
30 means of pump 40 which forces the asphalt
through line 4l into asphalt storage tank 42.
The overflow from decanter Il consisting oi
substantially asphalt-free oil, wax and propane in
a ratio in excess of that introduced into decanter
35 Il due to the separation of a part of theoil as
asphalt is Withdrawn via line 43 where it is com
mingled with l to 3 volumes of waxy oil sub
stantially free from asphalt such as lo-w viscosity
distillate or a well chemically treated oil coming
40 from tank 44 via line 45 controlled by valve 46
and pump 41 which forces the oil via line 48 into
line 43. This mixture then passes through heater
49 and line 50 controlled by valve 5I into Chiller
52 where the mixture is chilled to a sumciently
45 low temperature to precipitate wax from solution.
In heater 49, the mixture is heated to sufficiently
high temperature to cause the wax to dissolve in
the oil and propane preparatory to dewaxing.
The amount of waxy oil commingled with the
decantate from the asphalt separator Il will de
pend largely upon the propane to oil ratio pass
ing into line 43 and also upon the desired proi
pane to oil ratio passing into Chiller 52. Ii the
original . oil in tank l contains approximately
11% of asphalt and is commingled with, say 12
volumes of propane at 90 to 120° F. and approxi
mately 10% of asphalt is removed in decanter
H, the propane to oil ratio in line 43 will coni
prise about 13 to l. Adding, say 2 volumes oi
60 distillate from tank 44 to the propane and oil in
line 43, the propane to waxy oil ratio will be in
the neighborhood of 4.3 to l which is in the region
commonly accepted as being economical. Adding 3 volumes of the waxy distillate would give
a still lower propane ratio in the neighborhood
of 3.3.to l, While the addition of only one vol
ume of waxy distillate would give a higher ratio
of about 6.5 to 1.
The chilling for dewaxing in chiller 52 is ac
70 complished by vaporizing a portion of the propane
under reduced pressure which exerts a refrigera
tive >eiïect upon the remaining oil, wax and pro
pane. By gradually reducing the pressure at a
rate of, say 2 to 5° per minutedown to substan
75 tially atmospheric pressure, a temperature of ap
proximately _40° F. isobtained in chiller 52
which is su?licient to precipitate substantially all
of the -wax from solution. When other solvents
are used, the refrigeration temperature at atmos
pheric pressure Will vary from _40° F. and in
some cases, it may be necessary to operate vthe
chiller at sub-atmospheric pressures or to chill
the solution by indirect heat exchange with a cold
medium such as brine. The propane vaporized
in 52 passes via line 53 controlled by pressure re 10
duction valve 54 and passes into line 32 to the
suction of compressor 34. The chilling in 52 may
be accomplished with or Without make-up pro
pane dependingfupon the propane to waxy oil
ratio entering the chiller and the ratio of pro 15
pane to oil desired at the completion of the chill
ing operation. . If the propane to oil ratio enter
ing the Chiller is insuiiicient so that upon evapo
ration of pro-pane to vatmospheric pressure, an in
sufficient amount of propane remains in the
chiller to provide for adequate separation of the
precipitated wax from the remaining voil and-pro
pane, a further quantity oi propane may bevadded
via line 55 controlled by valve 56. >This liquid
propane may be either precooled or not, depend 25
ing upon Whether it is desired to obtain further
chilling in 52 with the make-up propane. Ii it
has been found that the propane to oil> ratio was
sumcient to obtain the desired low temperature
but insufficient to provide for adequate wax sepa 30
ration, it is preferable to add propane cooled to
about _40° F. into chiller 52 through line 55,
whereas, if the propane was insufficient to pro
duce the desired refrigeration, the propane may
be added at a somewhat higher temperature. 85
The chilling may then be continued to _40° F.
It is generally desirable to complete the chilling
operation with propane to oil ratio of about 2`
to 21/2 to 1. This is sufficient to accomplish good
separation of the precipitated Wax from the 4.0
chilled mixture.
'
The chilled mixture is Withdrawn from the bot-v
tom of Chiller 52 via line 51 controlled by valve
58 and pump 59 which forces the mixture under
pressure via line 50 through ñlter 6l Where the 45
precipitated Wax deposits upon the filter leaves
and is withdrawn via line 52 controlled by valve
33 from which it may be passed to suitable heat
ers and separators for removing propane and oil
contained in the Wax cake. Instead of separat 50
ing the precipitated wax by filtration, I may em
ploy other means, such as cold settling or cen
trifuging. The'ñltrate substantially free from
wax and asphalt is passed through line B4 through ,
heat exchanger 55 where the low temperature of 55
the solution may be recovered such as by heat ex
change as, for example, with solution entering the
Chiller' after passing through heater 49. The
mixture is then introduced into vaporizer 66
Where the propane is vaporized, aided lby steam
circulated through closed coil '61. The vapor
ized propane passes out of vaporizer 6E via
line 33 controlled by valve (i9 and thence passes
into line 32 to the suction of compressor 34. The
dewaxed oil passes from the bottom of. vaporizer 65
66 via line 10 controlled by Valve 1| and pump
12 which forces the oil through line 13 into storage
tank 14.
‘
'
'
After dewaxing and depropanizing,v the mix
ture' of heavy and light oil stocks may be redis 70.
tilled and fractionated to give appropriate cuts
for further treatment such as Withacid and alkali
and clay or by extraction with suitable solvents
such as liquid sulphur dioxide, or for use as dif
ferent viscosity grades of> lubricating oils, if 7,5
4
2,119,733
desired.
This may be effected in a fractional dis
tillation column 15 supplied from the tank 14 by
means of line 16, and having take off lines 11
for the recovery of various fractions as desired.
The following represents an example for carry
ing out my process on certain stocks. However,
this example is not intended to be limiting:
An S. A. E. 70 overhead vacuum distilled stock
containing wax was mixed under pressure with
about 20 volumes of propane at 90° F. which
caused separation of about 12% of heavy green
mixture to precipitate wax, separating precipi
tated wax from said mixture, and subjecting the
dewaxed oil to distillation to separate the same
into oils of varying viscosities.
2. A process for separating asphalt and wax
from oils which comprises commingling an oll
containing asphaltic material and wax with a
liqueñed normally gaseous hydrocarbon diluent »
in an amount suflicient to separate substantially
all of the asphalt and coloring matter from said 10
oil, said hydrocarbon diluent to oil ratio being
After decantation, the propane
considerably in excess of a diluent to oil ratio
oil solution was commingled with twice as much
of S. A. E. 40 distillate stock based on the original
oil giving a propane to oil ratio of about 6.8 to 1.
This solution was heated to above the cloud point
(about 125° F.) and then chilled adiabatically at
a rate of about 21/2° F. per minute to about _40° F.
and then was filtered at --40° F. under a pressure
20 of about 10 lbs. per square inch. The volumetric
ratio of propane to oil passing to the filter was
about 3.3 to 1. The filter rate on a viscous oil
basis was 3.9 gallons per square foot per hour.
After treating the oil with a selective solvent in
the presence of the remaining propane, a raflinate
was obtained having a gravity of 60° F. of 27.3°
A. P. I., a color of 7 N. P. A., a pour point of 5° F.,
Saybolt Universal viscosities of 1185 at 100° F.,
474 at 130° F., 182 at 170° F. and 92.5 at 210° F., a
30 viscosity index of 88 and a viscosity gravity con
stant of 0.811.
It will be observed that in addition to obtaining
a very thorough de-tarring of the heavy stock
Without the expense of propane to oil ratio being
desired during dewaxing of an oil by vaporization
of diluent under reduced pressure, separating pre
cipitated asphaltic material from the oil and dil
ish-brown tar.
SÉ charged against the heavy stock by the method
shown above, another important advantage is
40
obtained in that the dewaxing characteristics of
the added lower viscosity stock are greatly im
proved by the admixture with the heavy stock.
It will be observed that while I have described
the foregoing example in connection with treat
ing an S. A. E. 70 overhead vacuum distilled stock
and commingled an S. A. E. 40 distillate with the
deasphaltized heavy stock and then dewaxed the
45 mixture, the invention may be applied to the
treatment of other oils. Thus, instead of adding
an S. A. E. 40 distillate to the heavy stock, I may
add a treated waxy distillate such as one which
had been reñned with acid and alkali or with a
50 selective solvent such as liquid sulphur dioxide or
both. Instead of treating a heavy overhead dis
tillate, I may treat a raiiinate produced by selec
tive solvent extraction with liquid sulphur dioxide
and obtain an improved color and carbon residue
on the rafïinate. The treatment with large
amounts of propane appears to precipitate color
bodies from the raffinate which even selective
solvent extraction will not remove.
Thus, there are many variations of the process
which may be made within the scope of the fol
lowing claims by those skilled in the art Without
departing from the spirit of the invention; con
sequently, the foregoing exemplary description is
65
not to be taken as limiting.
I claim:
from oils which comprises mixing a heavy oil con
taining asphalt and wax with a sufficient quantity
liquefied
normally
gaseous
desirable for dewaxing by vaporization of diluent 20
under reduced pressure, chilling said mixture to
precipitate wax and separating precipitated wax
from said mixture.
3. A process as in claim 2 in which said heavy
oil containing asphalt comprises about an S. A. E. 25
70 oil and said waxy lighter oil comprises one hav
ing about an S. A. E. 40.
4. A process for separating Wax from relatively
light waxy oils which comprises commingling said
relatively light waxy oil with a light hydrocarbon 30
diluent and a raffinate produced by extracting an
oil with a selective solvent, said rañinate contain
ing color bodies which are not removed by the
extraction with the selective solvent but which
precipitate when admixed with said light hydro 35
carbon diluent, chilling said mixture toI precipi
tate wax and separating the precipitated wax
from the mixture.
5. A process for separating wax from waxy oils
which comprises commingling a relatively light 40
waxy oil with a light hydrocarbon diluent and
a relatively heavier rañinate produced by extract
ing an oil with a selective solvent, said rafñnate
containing color bodies which are not removed
by the extraction with the selective solvent but 45
which precipitate when admixed with said light
hydrocarbon diluent, chilling the mixture to pre
cipitate wax and separating precipitated wax
from the mixture.
6. A process for separating asphalt and wax
from oils which comprises commingling an
asphalt and wax containing oil with allarge vol
ume of solvent capable of dissolving the'oil but
not the asphalt, separating undissolved asphalt
from the oil and solvent, commingling said de 55
asphalted oil and solvent with a second oil con
taining wax but substantially free from asphalt
in amount sufficient to reduce the diluent oil
ratio to a large extent, chilling said mixture to
precipitate wax and separating precipitated wax
from said mixture.
7. A process for separating asphalt and wax
from oils which comprises mixing a heavy oil
cointaining asphalt and wax with a suñicient
quantity of liqueñed normally gaseous hydrocar 65
Y 1; A process for separating asphalt and wax
of
uent, commingling said oil and diluent with a
suiiicient amount of an asphalt-free waxy oil of
lower Viscosity than said first mentioned oil to
reduce the diluent to oil ratio within an amount
hydrocarbon
70 diluent to elîect precipitation of substantially all
of the asphalt from said oil, separating precipi
tated material from the oil and hydrocarbon
diluent, commingling said oil and diluent with a
Wax containing oil in amount suflicient to reduce
the diluent oil ratio to a large extent, chilling said
bon diluent to effect precipitation of substan
tially all of the asphalt from said oil, separating
said precipitated asphalt from the oil and hydro
carbon diluent, commingling said oil and diluent
with a Wax containing oil substantially free from 70
asphalt in amount suiiicient to reduce the diluent
oil ratio to a large extent, chilling said mixture
to precipitate Wax and separating precipitated
wax from said mixture.
8. A process as in claim 7 in which the liquefied 75
5
2,119,733
normally gaseous hydrocarbon diluent comprises
13. A process as in claim 11 in which the light
liquid propane.
Vhydrocarbon diluent comprises liquid propane.
9. A process for separating wax from waxy
lubricating stocks which comprises commingling
a relatively heavy rafñnate with large quantities
of a liqueñed normally gaseous hydrocarbon dil
uent, said rañinate being produced by extracting
an oil with a selective solvent but containing
color bodies which are not removed by the extrac~
tion with the selective solvent, adding a quantity
of a relativelylighter waxy oil to reduce the oil-dil
uent ratio, chilling the mixture to precipitate wax
and separating the precipitated wax.
10. A process for separating wax from oils
which comprises mixing a waxy heavy oil which
naturally contains a wax separation aid with a
suñicient quantity of a diluent which is capable of
precipitating said wax separation aid from said
oil, and thereby precipitating wax separation aid,
separating substantially all of the wax separation
aid from the diluted oil, mixing said diluted oil
with an oil containing wax in an amount sufûcient
to reduce the diluent to oil ratio, chilling said
mixture to precipitate wax and separating the
wax from said mixture.
11. A process for separating wax from a rela
tively light waxy oil which is substantially free
from asphalt which comprises mixing a relatively
heavy waxy oil containing asphaltic materials
with a light hydrocarbon diluent in an amount
sufficient to precipitate a substantial quantity of
said asphaltic materials but to leave a small
quantity of the asphaltic materials in the oil to
serve as a wax-separation aid for the subsequent
dewaxing of relatively light waxy oil, mixing
said diluted oil with al relatively light waxy oil
in an amount suñ'icient to reduce the diluent to
oil ratio to a large extent, chilling the mixture
in the presence of the wax separation aid to pre
lll. A process for separating wax from a rela
tively light waxy oil which is substantially free
from asphalt which comprises ñxing a relatively
heavy waxy oil containing asphaltic materials
with a light hydrocarbon diluent in an amount
suflicient to precipitate a substantial quantity of
said asphaltic materials but to -leave a small
quantity of said asphaltic materials in the oil 10
to serve as a wax Yseparation aid for the subse
quent dewaxing of the relatively light waxy oil,
removing the precipitated asphaltic material
from the oil, rdiluent and remaining asphaltic
materials, mixing said last mentioned mixture
with the relatively light waxy oil in an amount
suflicient to reduce materially the diluent to oil
ratio, chilling said mixture to precipitate wax
and separating the precipitated wax from the
mixture.
l
20
15. A process for separating wax from waxy
lubricating stocks which comprises commingling
a relatively heavy wax bearing raiilnate with large
quantities of a light hydrocarbon diluent, said `
' raflinite being produced by extracting an oil with 25
a selective solvent and containing color bodies
which are not removed by the extraction with the
selective solvent but which precipitate when ad
mixed with said light hydrocarbon diluent, pre
cipitating and separating said color bodies from
said rañinate and diluent, adding a quantity of
a relatively lighter asphalt free waxy oil to reduce
the oilediluent ratio, chilling the mixture to pre
cipitate wax and separating the precipitated wax
from the solution of diluent and oil.
16. A process as in claim 15 in which the light
hydrocarbon diluent comprises a liquefied nor
mally gaseous hydrocarbon.
3,5
_
17. A process as in claim 15 in which the light
40 cipitate the wax and separating the precipitated
hydrocarbon diluent comprises liquid propane.
wax from the mixture.
12. A process as in claim 11 inwhich the light
hydrocarbon diluent comprises a liquefied nor
ULRIC B. BRAY.
mally gaseous hydrocarbon.
so
40
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