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Nov. 19, 1946.
B. F. wlNGRovE
2,41 1,492
METHOD FOR TREATING WAXY STOCKS
Filed March 9, 1945
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INVENTOR
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Patented Nov. 19, 1946
2,411,492
UNITED STATES PATENT OFFICE
2,411,492
METHOD FOR TREATING WAXY STOCKS
Byron F. Wingrove, Beaumont, Tex., assignor to
Socony-Vacuum Oil Company, Incorporated,
New York, N. Y., a corporation of New York
Application March 9, 1945, Serial No. 581,923
11 Claims.
(C1. 196-17)
1
2
This invention is directed to certain improve
ments to solvent dewaxing processes for the
preparation of substantially pure wax or petrola
tum and of low pour point lubricating oils. It is
specifically directed to a novel and economical
method Within such solvent dewaxing processes
for the removal of ash-forming constituents from
the wax or petrolatum product. Such ash-form
ing constituents are those non_-carbonaceous
constituents found in the residue from a batch
distillation to dryness of a petroleum oil, The
ash generally consists of metal salts and oxides
such as those of sodium, calcium and magnesium
and may also contain certain other inorganic
constituents. It is in this sense that the terms
ash-forming constituents will be used herein
both in describing and in claiming this invention.
The solvent dewaxing processes may involve the
-use of a single solvent such as petroleum naph
It is a further object of this invention to pro
vide removal of ash-bearing constituents from
separated wax in solvent dewaxing processes be
fore the subjection of the solvent containing sep
arated wax to distillation conditions.
tha or more generally the use of a mixture of f
. These and other objects of this invention will
become apparent from the following description
thereof, The separated wax after washing in
solvent dewaxing processes contains small quan
tities of solvent and possibly some ice. It has
now been found that by proper dilution of this
wax cake with additional quantities of the same
solvent or with at least one of the constituents
of that solvent, followed by heating to controlled
temperatures,` the ash-forming constituents may
then be removed from the mixture by mixing
therewith a relatively small proportion of wa
ter, which dissolves the ash-forming constitu
ents, and by a subsequent separation of the wa
ter by settling.
’
solvents such as benzol ketones, benzol-acetone
and toluol ketone mixtures. It is well known, for
example, that if a waxy petroleum stock be dis
solved in a mixture of benzol and methyl-ethyl
by reference to the single drawing, Figure 1 at-_
tached hereto, wherein is shown in highly dia
ketone and then chilled to suitably low temper-`
atures, waxy constituents will crystallize in such
ing process modified according to this invention.
substantial equipment corrosion.
the desired temperature, for example 0 degrees
This invention may be more readily understood
grammatic form a flow plan of a solvent dewax
Turning now to Figure l, a waxy charge stock
which may contain wax or petrolatum and which
form as to permit their removal from the mixture
by filtering in a suitable filter. The separated
contains ash~forming constituents is pumped by
wax is then washed with additional solvent and
charge pump I0 through pipe Il wherein it is
then introduced into suitable distillation equip 30 mixed with a suitable solvent which passes from
ment for the removal of contained solvent.
solvent tank i2 through pipe I3, pump I4 and
Ii the waxy stocks so processed bear high ash
pipe l5 into pipe il. The solvent may consist
contents, the resulting wax will contain a large
of a single solvent capable of dissolving t-he waxyV
proportion of said ash and as a result will be un
stock or it may consist of a mixture of solvents,
ñt for most oi the commercial wax products. 35 for example, benzol and methyl-ethyl ketone.
Suitable means for providing thorough mixing
Moreover, serious ash deposition results in the
distillation equipment used for separation of sol
of the solvent and waxy stock may be provided
vent from the pressed wax. Such ash deposition
in pipe Il, such as a series of venturis. The sol
vent-waxy stock mixture then passes through
causes severe loss in the heat transfer rates in
the distillation and cooling systems as well as 40 cooler I ß and chiller Vl, wherein it is chilled to
Attempts to
wash the pressed wax as normally charged to dis
Fahrenheit. The chilled mixture then passes
tillation equipment or attempts to wash the wax
through pipe i8 to surge tank I9 from which it
is withdrawn through pipe 20, and pump 2| and
product Jfrom such distillation with water result
in serious emulsion dilìculties and resultant neg 45 charged through pipe 22 into the ñlter 23. The
ligible ash removal. As a consequence, at the
ñlter may be any of a number of types either of
present state of the art, high ash bearing waxy
the plate and frame variety or of the continuous
stocks are generally avoided in dewaxing opera
rotary vacuum type variety such as an Oliver ‘lil
tions; and, if used,l the wax product is generally
ter. The crystallized waxy material is pressed on
useful for nothing more than a low grade crack 50 the filter 23 and washed by means of additional
ing stock.
i
solvent introduced through pipe 24. The wax
It is an object of this invention to provide an `
cake containing some solvent and ash-forming
economical and practical method for removal
constituents is withdrawn from filter 23 through
of ash forming constituents from separated waxy
screw conveyor 25 which pumps it into a pump
55 ablemixture which passes through pipe 2.6, pump
materials.
Y
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,
.
.
2,411,492
3
.
2'! and pipe 28 to heat exchanger 25. Additional
vent passes from the bottom of tower 'i0 through
pipe 71, pump 'i8 and pipe 'i9 to the steam strip
before the exchanger 29, such as within pipe 25,
ping tower Bü. Solvent and steam pass overhead
into which it is introduced through pipe 30. The
from this tower through pipe 8| into the Water
volume of solvent sc added should be substantial 5 solvent fractionator 59, from which dewaxed lu
ly in excess of the volume of the wax cake. The
bricating oil is withdrawn from the bottom of
solvent wax cake mixture is heated in exchanger
tower Bil through pipe 82.
Z5 to a suitable temperature, for example, 120 to
It should be understood that no novelty is
150 degrees Fahrenheit and is then passed
claimed herein in the solvent dewaxing process
through pipe 52 into mixing tank 33. Water
as such, but novelty is claimed in the practical
amounting to a small proportion of the wax-sol
incorporation into such'solvent dewaxing proc
vent mixture is added to the mixer 33 through
esses of the hereinabove described practical and
pipe 3l and thoroughly mixed with said mixture;
economical method for removing ash-forming
solvent is added to the wax cake at some location
whereby the ash-forming constituents therein
constituents from the wax cake. The ñltered
wax cake obtained from filter 23 in conventional
are dissolved in the added Water. It will be un
derstood that the mixing tank 33 may be of any
solvent dewaxing processes will contain certain
amounts of solvent and frozen water as well as
the ash-forming constituents. The method of
this invention employing additional quantities
conventional construction suited for its purpose
and may consist only of a series of venturis or
oriiices within a section of conduit. The mixture
then passes from the mixer 33 through pipe 34, 20 0f the same solvent and of water to effect the re
pump 35, and pipe 35 into a settling tank 31
moval of ash-forming constituents, requires the
wherein the mixture stratii'les into an upper lay
addition of no constituents to the dewaxing proc
ess other than those that were already present.
This is of substantial practical importance as it
er containing solvent and waxy material and a
lower layer containing Water, ash-forming con
stituents and a small quantity of solvent. The
settling tank 3l may be of any conventional con
struction well known to the art, and while only
one is shown in the drawing, several may be
. means no particular increase or change in the
fractionation equipment already existing in the
used alternately to provide continuity to the
solvent dewaxing plant, and makes highly prac
tical the solvent dewaxing of ash bearing waxy
stocks for the production of substantially ash
process. The material in the wax-solvent layer
free wax products as well as low pour point lu
is then passed through pipe 38, pump 39, and
bricants. It will be readily recognized by those
pipe 40 to heater lil wherein it is heated to a
skilled in the art that various modifications in
suitable temperature and then charged ,through
the equipment, equipment arrangement and flow
streams are employed in various solvent dewax
pipe 42 into fractionator 43 wherein the wax and
solvent are separated by fractionation.A The 35 ing processes which modifications will differ
waxy material is discharged from the lower sec
somewhat from the highly diagrammatic flow
plan shown in Figure 1. It will be understood
that the specific arrangement shown in Figure
1 is intended merely as exemplary and it is not
intended that the scope of this invention be lim
ited thereto.
The amount of solvent mixed with the waxy
charge stock will vary depending upon the par
tion of iractionator ¿i3 through pipe 44 and
passes as a substantially ash free wax either to
storage or to further refining equipment. The
recovered solvent passes overhead through pipe
45 and condenser ¿i6 to pump 41 from which it is
forced in part through pipes 48 and 49 to the
upper section of tower ¿i3 as reflux and in part
through pipes 48 and 50 and 5l to the solvent
ticular stock and process involved. As an ex
tank l2. Alternately this latter fraction of sol 45 ample, in the solvent dewaxing of an acid treat
vent instead of passing through pipe 5| into tank
ed and caustic neutralized mixed base residuum
l2 may pass through pipes 52 and 30 into pipe
of approximately 160 S. U. V. at 210° F., the
25 as dilution solvent for the wax cake as herein
solvent to waxy stock ratio is of the order of 5.0
above described or it may pass through pipes 52
to 1. The amount of solvent required to ade
and 53 to the nlter 23 as wash solvent. On the 50 quately dilute the filtered wax-solvent mixture
other hand, if desired, solvent may be drawn
discharged from ñlter 23 will also vary with the
from tank i2, through pipe i3, pump M, pipe I5
solvent used, and the stock involved. Inany
and pipe 55 into pipe 52 for use for washing or
case the volume of the solvent should greatly ex
dilution purposesl
ceed the volume of the wax cake. In general the
The water containing ash-forming constitu 55 volumetric ratio of solvent to wax cake in the
ents and small amounts of solvent passes from
mixture should be at least 8 to 1. As an example,
settling tank 37 through pipe 55, pump 55, heat
in the processing of the wax cake from the above
er 5l' and pipe 58 to the water-solvent fraction
mentioned mixed base residuum, suilicient sol
ator 59. Water is drained from the bottom of
vent should be added to provide a mixture con
tower 5S through pipe 50 to the sewer and the 50 taining approximately `8 to 10 volumes of solvent
solvent overhead passes through pipe Si, con
per volume of pressed wax cake. The solvent
denser 52, to pump 63 from which it passes
used in that example consisted of a mixture con
through pipe 54 partly through pipe 55 to tower
taining about 60% benzol and 40% methyl-ethyl
59 as reiiux and partly through pipes 55, 50 and
ketone. When the solvent dewaxing process in
5! to solvent'tank I2.
65 volves the use of mixed solvents, it is not entire
_Returning to ñlter 23, the dewaxed oil pro
duced therein dissolved in solvent passes therefrom through pipe 5l to pump 58 from which it
passes through pipe 59 to the flash tower 10.
Most ofthe solvent passes overhead from tower 70
'I0 through pipe il, and condenser T2 to pump 13
from which it passes in part through pipes 'M
and 'i5 to the upper section of tower ï@ as reflux
and in part through pipes i4, 'i6 and 5| to sol
vent tank l2. The oil stillcontaining some sol
ly necessary that the solvent constituents be of
the same ratio in the solvent mixture used for
dissolving the waxy oil charge stockv and in the
solvent mixture used for diluting the wax-cake
solvent mixture. In the latter case, it may often
be desirable to use either one or the other of the
solvents involved in substantially pure form de
pending upon the process. It will be understood
that in the claiming of this invention the word
'15. solvent is used in a sense suiliciently broad to.
2,411,492
5
6
of heating, thoroughly mixing atleast 5 per cent
by volume water to said heated mixture, thereby
cover a `single solvent material or a mixture
thereof.
‘
The temperature to which the solvent-wax
cake mixture should be heated before addition of
accomplishing the solution of said ash-forming
material in said water, and substantially separat
ing the water containing said ash-forming mate
water is torsome extent dependent upon the ma
terials involved. In general, it should be above
about 12o degrees Fahrenheit and below the boil
ing points of the solvent and of water at the
existing pressure conditions of the heating.
rial from said mixture of solvent and waxy ma
terial by settling.
4. In a solvent dewaxing process wherein waxy
material is separated at suitably low temperatures
10 from a waxy petroleum stock, mixed with liquid
solvent having a substantially greater solubility
The .
preferable temperature range is from about 120°
to about 150° F.
The amount of water required to remove the
ash-forming constituents will depend in part on
the amount of such constituents present. In gen
eral the quantity of water required is a small pro
portion of the total mixture and preferably should
be of the order of 5 to 10 percent by volume of
said mixture.
for the non-waxy material than for the waxy
material contained in said stock at saidlow tem
peratures, the method for removing ash-forming
constituents from the separated waxy material
which comprises: adding to said separated waxy
material, before removal of any contained sol
vent therefrom, an additional amount of said
I claim:
>
solvent sufûcient to provide a waxy material
l. In a solvent-dewaxing process wherein waxy 20 solvent mixture containing at least 8 volumes of
material is separated at suitably low temperatures
said solvent per volume of waxy material, heat
from a waxy petroleum stock, mixed with a suit
ing said mixture to a temperature at least above .
able composite solvent, the method for removing
l2() degrees Fahrenheit and below the boiling
ash-forming constituents from the separated wax
point ofwater and of said solvent at the condi
cake> which comprises: adding at least one con- 25 tions of heating, thoroughly mixing at least 5
stituent of the solvent involved in said dewaxing
per cent by volume water to said heated mixture,
thereby accomplishing the solution of said ash
process to said wax cake in an amount substan
forming material in said water, maintaining the
tially in excess of the volume of said Vwax cake,
heating the mixture to a temperature above about
resulting mixture in a settling chamber wherein
120 degrees Fahrenheit but below a temperature
the water containing said ash-forming constitu
sufficient to substantially boil said solvent and
ents substantiaily separates from said mixture
water, mixing with said mixture a relatively small
’of waxy-material and solvent by stratification,
proportion by volume of water, whereby the ash
forming constituents contained in said `wax cake
will be dissolved in said added water, and sub
stantially separating the water containing said
ash-forming constituents from said solvent-wax
mixture.
`
2. In a solvent dewaxing process wherein waxy
separately removing the stratiñed materials from
said chamber and effecting the separation 0f said
. purified waxy materials from said solvent.
5. The method for producing a substantially
ash-free wax from a wax-containing petroleum
stock which method comprises: dissolving said
wax-containing stock in a `solvent having a low
material is `separated `at suitably low tempera 40 `viscosity relative to said stock and a substantially
tures from a waxy petroleum stock, mixed with a
greater solubility for the non-waxy constituents
suitable solvent, the method for removing ash
of said stock than for said waxy constituents at
forming constituents from the separated wax cake
reduced temperatures, chilling the mixture to a
which comprises: adding at least one constituent
suitable temperature substantially below the freez
of the solvent involved in said dewaxing process iff ing point of water, whereby the waxy constitu
to said> wax `cake in an amount sufficient to pro-,
ents crystallize, ñltering the wax from the oil
vide a mixture containing about 8 to l0 volumes
solvent solution, to effect separation therefrom,
of solventper volume of wax cake, heating the
adding sufficient solvent to said separated wax
mixture to a temperature above about 120 de
to provide a mixture` containingat least 8 vol
grees Fahrenheit but >below a temperature suiñ- 5U` umes of solvent per volume of wax, heating said
cient to substantially boil said solvent and wa
wax-solvent mixture to a temperature above
ter, mixing with said mixture about 5 to l0 per
about 120 degrees Fahrenheitand below the boil
cent by volume of water, whereby theash--form
ing point of water and of said solvent, thorough
ing constituents contained in said wax cake will
ly mixing at least ölper cent by volume of wa
be dissolved in said added water, and substan- 55 ter with said mixture to effect solution of said
tially separating the water containing said ash
forming constituents from said solvent-wax mix
ture.
,
`
,
ash-forming constituents therein, maintaining
the resulting mixture in a settling chamber where
in said water containing said ash-forming con
3.` In a solvent dewaxing processwherein waxy
stituents is separated from said wax-solvent mix
material is separated at suitably low .temperatures 5o ture by stratification, separately withdrawing the
from a waxy petroleumstock, mixed with a sol
wax-solvent layer from said chamber, effecting
vent having a substantially greater solubility for
the non-waxymaterial .than for the waxy ma
terial contained _in saidstock `at said low tern
the separation of said puriñed wax from said sol
vent, and recovering dissolved solvent from said
separated water.
peratures, the method for removing ashfforming 65 6. The method for producing a substantially
constituents from the separated waxy material
ash-free wax `from a wax-containing petroleum
which comprises: adding to said separated waxy
stock which ‘method comprises: dissolving said"
material, before removal of any contained sol
wax-containing stock in a composite solvent hav
vent therefrom, an additional amount of said
ing a low viscosity relative to said stock and a
,- solvent sufficient to provide a waxy material- 70 substantially greater solubility for the non-waxy
`solvent mixture containing at least 8 volumes of
said Solvent per volume of waxy material, heating
said mixture to a temperature at least above 120
degrees Fahrenheit and below the boiling point
of water and of said solvent atV the conditions 75
constituents of said stock than for said waxy con
stituents at reduced temperatures, chilling the
mixture to a suitable temperature substantially
below the freezing point of water, whereby the
waxy constituents crystallize, filtering the wax
8
7
ture to a suitable temperature substantially be
from theI oil-solvent solution to obtain a substan
tiallywax-free oil stock and a wax cake contain
ing some residual solvent, substantially diluting
the wax-solvent mixture `with an additional
quantity of at least one constituent of said solvent
tweend 32 degrees Fahrenheit, filtering theÁ wax
from the oil-solvent solution, to eiiect separation
therefrom, adding suñicient solvent to said ñl
tered wax to provide a mixture containing at
least 8 volumes of solvent per volume of wax, `
heating said wax-solvent mixture to a temper-_
to raise its solvent content, heating the mixture
to a temperature above about 120 degrees Fahren
heit and below the boiling point of said solvent
ature above about 120 degrees Fahrenheit an‘d
below the boiling poi-nt of water and of said sol
vent, thoroughly mixing at least 5 perv cent by
~ volume of water with said mixture to effect solu
and of water under the: pressure conditions of
heating, thoroughly mixing arelatively small pro
portion of water with said heated mixture toefiect
solution' of said ash-forming censtituents therein,
maintaining the resulting‘mixture in a settling
chamber wherein said water containing said ash
forming constituents is s_eparted from said wax
tion oi?v said ash-forming constituents therein,
maintaining the resulting mixture in a settling
chamber wherein said water containing said ash
l5 forming constituents is separated from said wax
solvent mixture by stratiñcation, separately with
solvent mixture by stratification, separately with
drawing the wax-solvent layer from said cham
ber, effecting the separation of said puriñed wax
drawing the Wax-solvent layer from said cham
ber, elTecting the separation of said purified wax
from said solvent.
from said solvent, and recovering dissolved sol
l
`
'
7. lIn a solvent dewaxing process wherein waxy 20 vent from said separated` water.
"
"
l0,A The> method of obtaining a substantially
material is ñltered at suitably low temperatures
vfrom a waxy stock mixed with a suitable solvent ~
ash-free wax from a waxy petroleum stock which
containing at yleast one aromatic and at least one
method comprises: dissolving said waxy -stock in a>
ketone, the method for removing ash-forming
solvent ‘consisting of benzol. methyl-ethvl ketone
constituents from the iiltered waxy material
which comprises: adding to saids?lltered waxy
material after the washing thereof with solvent
an additional amount of at least oneconstituent
mixture, chilling said solution to a temperature
below zero degrees Fahrenheit. whereby the wax
constituents are crystallized, filtering said chilled
of said solvent mixture sufficient to provide a
mixture to effect separation of waxy Vmaterial
from non-waxy petroleum oil, adding a quantity
waxy material-solvent mixture containing at
30 of at least kone constituent _of said solvent mixture
least 8 volumesl ofvsai'd solvent per volume of
waxy material, heating said mixture to a tem
perature at least above 120 degrees'Fahrenheit
and below the boiling point of water and of said
tosaid iiltered waxy _material to form a mixture
containing, about 8 to 10 volumes of solvent per
volume of waxy material, heating said'mixture to
a temperature within the range 120 to 150 degrees
solvent at the> conditions of heating, thoroughly 35 Fahrenheit, thoroughly mixing about 5 to 1'0 per
cent by volume of water with said heated mixture
Vmixing at least V5 per cent by volume water to
said heated mixture,- thereby accomplishing the
whereby the ash-forming constituent in said waxy
solution of said ash-forming material in said
water. and substantially separating the water
material are> dissolved in said added water, sep
arating said water from said mixture by settling
containing said ash-forming material from said, 40 and eiîecting a lseparation of said waxy mate
rial from said solvent by distillation.
'
mixture of solvent and waxy material by settling.
11. In a solvent dewaxing process wherein waxy
8.’ In a solvent dewaxing process wherein waxy
material is ñltered at suitably low temperatures
material is filtered from a benzol, methyl-ethyl
from 'a waxy petroleum stock mixed withV a sol
ketone solvent mixture with a vwaxy petroleum
stock at suitably reduced temperatures the method 45 vent mixture having a substantially greater solu
- for removing ash-forming constituents Afrom the
bility `for >the non-waxy material lthan for4 ’the
ñltered waxy material which comprises: adding
waxy material 'contained in said V'stock at said
low temperatures, the method for removing ash
a suñicient -quantity of at least one constituent
forming constituents from the filtered waxy ma
of said solvent mixture to said filtered waxy mate
rial to provide a mixture containing about 8 to 50 terial which comprises: adding to said ñltered
waxy material, before removal of any contained
10 volumes of said solvent to one volume of waxy
solvent therefrom, an additional amount of at
material, heating the resultant Vmixture to a
temperature within the range about 120 to 150
least one constituent of said solvent mixture suf
degrees Fahrenheit, thoroughly mixing about 5
ñcientïto provide a waxy material-solvent mix
55 ture containing at least 8 volumes of said solvent
per .volume of waxy material, heating said mixture ‘
ture whereby said ash-forming constituents ‘are
to a temperature at least above Y120 degrees
- dissolved in said water and eñecting the separa
to 10 per cent by volume of water with said mix
Fahrenheit and below the boiling point of water
and of said solvent at the -conditions of heating,
9. The method of obtaining a substantially ash 60 thoroughly mixing at least 5 per cent by "volume
free wax from a wax-containing petroleum stock
water to said heated mixture, thereby accom
plishing the solution of said ash-forming mate
which method comprises: ldissolving said wax
rial in said water, and substantially separating
containing stock in a solvent containing a mix
the water containing >said ash-forming material
tureV of a fatty ketone having aliphatic groups
containing within. therange l to 4 carbon atoms 65 from said mixture of solvent and waxy material r
tion‘of said water from said solvent-wax mixture
byV
settling.v
,
'
y
A
I
_
‘
ì
‘ and of material selected from the group consist
ing of benzol, toluol and -xylene and aliphatic>
substituted derivatives thereof, chilling the mix
by
settling.
_
Y
_
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BYRON F. WINGROVE.
v
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