Патент USA US2397868

April 2, 1946”
v. N. JENKINS
, 2,397,868
TWO-STAGE DEOILING AND DEWAXING
Filed May 25, 1944
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INVENTOR.
WNCEMDZWK/NS,
BY
'
TTORNEY.
2,397,808
Patented Apr. ‘2, 1946
UNITED 'sTATEs PATENT/canoe
'rwo-s'mcn DEOILING AND nEwAxmG
Vance N. Jenkins, Palos VerdesHEstates, CaliL,
assignor to Union Oil Company of California,
Los Angeles, Calif., a corporation of California
Application May 23, 1944, Serial No. 536,975
riolaims. (Cl. 1963-18)
The present invention relates to the separation
of oil and wax from wax-oil mixtures such as
waxy oils or oily waxes.
The invention*rrelates
v particularly to a process for separating wax and
oil from wax-oil mixtures to produce low pour
test lubricating oils and oil free high melting
point waxes. The- invention also relates to a
process for treating slack wax to produce high
melting point waxes, and is an improvement ‘in
the process described in my Patent No. 2,229,658, ,10
dated January 28, 1941.
,
I
The above patent describes a method of opera
tion for the separation of wax and oil from ‘wax
oil mixtures, such as a ra?lnate derived from‘ the
steam coil and the vapors are then passed through
a mist extractor for the separation of, entrained
oil andlnto a condenser, wherein the solvent
vapors arefcondensed before'being returned to
solvent storage‘.
I
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,_
“The wax cake containing a minor portion of
solvent, and a small amount or‘ oil, which was
blended with additional solventso as to placé said
wax cake in a ?uid state in order to facilitate
pumping, is then passed through a heat ex
changer where it is heated to a suf?ciently ele
vated temperature to effect vaporization of the
solvent. The heated wax-solvent mixture is then
selective solvent extraction of distillate produced 15 passed into an evaporator._ The solvent vapors
arerecovered from; the evaporator, passed to a
by the vacuum distillation of a waxy crude oil,
condenserand the condensed liquid returned to
or the raw distillate itself or other fractions ob
solvent
storage. The high melting point solvent
tained from waxy crude oils or the slack‘ waxes
freewax
is withdrawn from said evaporator and
obtained from such oils, or a crude 611 residue
containing wax.
‘
..
20
' In the performance of the above disclosed in
vention (Patent No. 2,229,658), I heat the selected I
wax stock su?iciently high to eifect solution of
pumped to storage.
The oil recovered from the oil-solvent ?ltrate
may be passed to storage, or if the oil contains
low melting. point wax, ‘which it;does if the wax
The molten waxsoil
crystallization in the chilling and mixing column
dles and scrapers. The molten wax-oil mixture
is gradually cooled in said column to the desired
temperature, i. e., to a point su?iciently low to
temperature. .In the .further dewaxing of the
above mentioned oil, the said oil is mixed with a
wax contained in the oil.
mixture is introduced into a chilling and mixing 25 is carried out at a temperature vsufficiently high
to crystallize only'the high melting point wax, it
column provided with agitating or stirring. pad
is subjected to a second dewaxing stage at a. lower
crystallize the high melting point wax, vwhile
30 solvent such as one consisting of 50% methyl
agitating the mixture to prevent the wax-oil mix
ture from setting up into a solid non-?uid mass.
When the desired temperature on the wax-oil
mixture has been reached, a deoiling. solvent
such as one consisting of 90% methyl ethyl ke
tone (MEK) and 10% benzene is mixed with the
wax-oil mixture in order to produce a slurry
which ?lters readily. The solvent is preferably
ciently low temperature to. precipitate‘ substan
tially all of the low melting point wax contained
ethyl ketone (MEK) and 50% benzene. The solu
tion of MEX-benzene and oil is then passed into
a chiller where the solution is chilled to_ a suf?
in the solution.
_
When a temperature su?iciently low for de
‘waxing is attained in the chiller, the resulting
slurry is withdrawn and'pumped into a'?lter
cooled to the temperature prevailing in thejchill
ing and mixing column or to a lowervtemperature 4.0 where the wax suspended in the slurry is sepa
rated from the oil and solvent. The ?ltrate con
so as to prevent resolution of crystallized wax.
sisting of oil and solvent is-{ passed through a
‘heat exchanger and then into an evaporator
where the solvent is vaporized'from the dewaxed
After the solvent has been mixed with the
cooled wax-oil mixture containing the desired
crystallized wax, the resulting slurryis withdrawn
from said column and introduced into a ?lter 45
where the wax suspended in the slurry by chilling
is separated from the oil and the bulk'of the sol- '
vent. 'The separated wax in this operation will
oil and then condensed and “pumped to storage.
‘The dewaxed oil isiwithdrawn from the .evapo
rator and pumpedinto dewaxed oil storage.
' The solvent wet wax remaining in the above
mentioned ?lter is 'withdrawn‘and blended with a
contain a small amount of solvent as well as a
small amount of oil. The oil-solvent ?ltrate from , 50 'su?icient amount of solvent so as to put said wax
the ?lter is then passed through a heat exchanger
where the temperature is raised so as to permit
vaporization of the solvent. The preheated solu
tion is then passed into an evaporator. The sol
’vent is vaporized in the .evaporator'aided' bye.
in a pumpable state; The?uid wax is then
passed through a heat exchanger and intoan
evaporator where the solvent‘ is separated from
, the wax.
55
The low melting point solvent-free wax
is withdrawn from the evaporator and pumped to
2;
'
7
2,897,868
oil, respectively, are stripped. This benzene
methyl ethyl ketone solution is converted into
90% methyl ethyl ketone and 10% benzene by
subjecting it to distillation after adding enough
storage. The‘ solvent vaporized in the evaporator
is removed, condensed and returned to storage.
When carried out as above, it is apparent that
four stripping operations‘ are necessary to sepa
I rate the solvent from the high melting wax, the
water to said solution to- form a ternary azeo
trope, with all of the benzene present. This‘
azeotrope consists of about 7.7% water, 19.0%
low melting wax, the partly dewaxed oil, and the
fully dewaxed oil, respectively. These operations
‘ involvin‘gi'the'; separation :of tli'e'i'solvent fromtth‘e' ‘
methyl‘v ethyl“ 'ketone, and 373.3% "benzene, and
when it is‘ distilled overhead it leaves a bottoms
oil involve distillation of a very large amount of
‘ solvent, and it would be very desirable from an,
economic standpoint to eliminate one of them.'
consisting of 100% methyl ethyl ketone. The
_' distillate is then cooled and allowed to separate
3 highly desirable, without introducing‘: additional
ventconsisting of: about 20% MEK and 80% ben
It is also apparent that steam. cannotbeused in ‘ . into twophases, anv aqueous phase‘ and a'solvent
‘ these stripping operations, even; though it is ‘l ' phase which is then dehydrated to yield a dry sol
, complicated solvent recoveryappara-tus; because 7' "zone. "This i'svth'enmixed with the 100% methyl
ethyl ketone in- the proper proportions to form
the 9.0%; MEK 10% benzene solvent for use in the
?rst stage of the two-stage process. The aque
MEK is so soluble in water; ‘
It was also shown in the earlier patentthat
one of the above stripping operations could'be
omitted if the 50% benzene 50% MEK' solvent
' one phase from the settling step is recycled to the
for the second stage dewaxing. cQuldbe. pnefpared "‘
azeotropic. distillationstep. .
in the oil-solution, merely by addingbenzene. .(and
MEK; if necessary.) tothe filtrate from the ?rst
., _
wax-oil mixtures into their constituent compo
dewaxing step, without distilling. the ?ltrate. to
separate the 90% MEK"10% benzene solvent from
the partly dewaxecl oil in this ?ltrate. Operat
.pliiying the procedure required for’ the recovery
Thus, itis an object of myv invention to separate
nents. in a very'simpl'e. and economical manner. .
’ Aiurther object oifmyinvention resides in sim
of used. deoiling and. dewaxing solvents.
ing in this manner, the solvent recovered by
.
Another object is theseparation of MEK-ben
evaporation of solvent from the high melting
zene-water mixtures into components which may
point wax obtained from‘ the ?rst d'ewaxing stage
will have a composition of 90% MEK and 10%
be reblended ' to obtain dryrMEK-benzene de
benzene, i. _e., the‘same'composition as the sol- ’
oiling and dewaxing solvents having any, desired
ventoriginally introduced into said ?rst stage of
dewaxin‘g,‘ the solvent ‘recovered from evaporaw
tion of solvent from the low melting point wax‘
obtained from the second d'ewaxing- stage‘ 'will
have a composition of 50% MEK and 50% ben
composition between 320%, MEK, and 100% MEK.
zene, i. e'., the same composition as the‘ solvent
be apparent from‘thefollowing description of the
originally introduced into- said second stage ‘of
dewaxingy' and the solvent recovered‘ from the
Another object of my. invention is the conver
sion of used‘ deoiling, and dewaxing solvents into
the proper compositionsfor deoiling, and dewax
ing
purposes-I
invention.
evaporation of solvent from dewaxed’ oilv from the '
.
..
.,
'
Other objects and features of my invention will
_
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'
According to my invention for the treatment
second dewaxing stage will also ‘have a composi in of wax-oil mixtures containinghigh percentages .
,of high 'meltingjpoint waxes, suchfas solvent
tion of‘ 50%: MEK and. 505% benzene, :i. e., the
extracted 'raf?nate offhig'h wax _c.ontent,_,I' oper- '
same composition as the solventor-iginally intro
.ate the process in two stages,’ the'g?rst of which
duced into-said second? dewaxingv stage:
' r The .aboveprocessalsoidiscloses' the .use.of.‘12001% :45 maybe regarded as a deoiling stage and the sec
and ‘as a dewaxing stage; In the ?rst ‘stage the,
MEK and. another solvent vvconsisting of 20%
ra?inate, for example, ‘is ‘heated to a'temperature
and. 80% benzene‘ a‘s'the original ‘solvent
'sui?cient to dissolve completely the‘ wax in the
contained oil, after which theheated r'a?nate is
cooled with constant agitation toatmospheric
of dewaxing. ' The total recovered solvent there
fore consists of a minor‘ proportion of 9.0% MEK" 50 temperature or lower, so that the greater per
centage of high "melting ‘point wax is crystal
and 10% benzene and a major-proportion of 50%
stocks which ‘may’ be blended to produce 90%; '
MEK and- 10% benzene :for use imthe-‘?rstr stage
lized in the form of large, well-de?ned, oil-free
crystals. ‘It is preferable to add a srriall amount
of a deoiling solvent to the wax-oil mixture be
MEK and 50% benzene.
aresu-ltof the above
v.process agproblem arises which: consists of con
verting a portion of the recovered 50 % MEK ‘and
50%v benzene back to the 90% MEK 110% benzene
.solvent required for the ?rst stage treatment.
‘ . Fractional distillation cannot be employedto-sep- ‘
arate MEK from benzene since they boil within
approximately .0.5° C. of eachother. _A.fur-ther
problemv arises when/steam ‘is employed, as is
highly desirable, inthe stripping of. the solvent
from the wax‘and from they oil, as mentioned
above.
.
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'
fore it is cooled to ?nal de°waxing temperatures
when the slurry becomes sothick that it is dii~
?cult to stir and subsequent to theicrystallization
of substantially all of the desired vhigh melting
point wax‘. ‘When the raf?nate ‘has been cooled
to the desired “deoiling temperature, a small.
amount of the deoiling'solvent" is mixed'with ;
the cooled raf?nate to form a slurry which ?lters
rapidly. "As a solvent fora'dmixture with the
I'havediscovered. process-whereinl can ac- . cooled ‘raf?nate, I ‘use a v‘mixture consisting of
and 10% benzene. The
complish. the simpli?ed two-stage dewaxing oper 65 approximately 90%
amount of solventused will depend upon the de
ation just described and- at the-same ‘time convert
?ired viscosity of the resulting slurry.‘ 'lv '
the recovered 50%IMEK 50% benzene solventin
The slurry produced "in'the above method is
to._9.0:% ‘MEKand 10% benzene andla‘lso usepsteam
then filtered in the usual manner and the wax
in ‘all stripping operations, In order to accom
cake "washed on the ?lter with a small amount
plish’ this; blend the,,90% MEK and 10% ‘ben
of the solvent to remove entrained oil. The high
- zene containing condensed‘ steam recoveredfrom
‘melting point waxcontaining entrained solvent
the. steam strippingvogf 'the'rhigh melting point
is introduced into a stripping column where by
wax. with the 50% MEK, and ‘50% ‘benzene con
means of steam the solvent in said wax is vapor
taining condensed steam recovered from ‘the steps
wherein the low‘ melting point waxv and dewaxed 75 ized and removed irom'the "top of the column,
_
accuses
this distillate consists" of 90%
3
and 10%
minor proportion of water, therefore. it is ?rst
benzene and condensed'steam. The high melt
ing point wax is withdrawn from said stripping
said water before passing the MEK to storage.
necessary to pass it through a drier to remove
column and pumped toistorage.
The water left as bottoms in the distillation col
umn is removed and returned to the azeotropic
distillation column to act as an azetrope former.
The ?ltrate from the above ?lter, which con
sists of oil, low melting point wax and solvent
(90% MEK and 10% benzene) is blended with
a su?icient. amount of 20% MEK and 80% ben
zene to convert the composition of said solvent
_
The methyl ethyl ketone from 100% methyl '
ethyl ketone storage is then blended in the proper
proportions with the MEK-benzene mixture from
to approximately 50% MEK and 50% benzene. 10 the 20% methyl ethyl ketone, 80% benzene storThe ?ltrate consisting of oil, low melting point
age to produce a mixture of 90% methyl ethyl
wax ‘and 50% MEK and 50% benzene solvent
ketone and 10% benzene which is then recycled
is introduced into a second chilling and mixing
to the ?rst stage dewaxing to act as a dewaxing
column provided with agitating or stirring pad
solvent.
_
dles and scrapers. The resulting slurry produced
' The method of operation of my invention may
in the above cooling stage is withdrawn from
be better understood by reference to the descrip
said column and introduced into another ?lter
tion of the drawing. Referring to a speci?c ex_
where the low melting point wax suspended in
ample carried out in a unit substantially as shown
the slurry is separated from the oil and solvent.
in the drawing wherein a waxy ra?inate stock was
The oil solvent ?ltrate is then passed through
used which was produced by solvent extracting
a heat exchanger where the temperature is raised
a waxy distillate having such gravity and viscosity
so as to permit vaporization of the solvent. The
characteristics as ‘to produce a ?nished S. A.‘ E.
preheated solution is ‘then passed into a stripping ' 50 lubricating oil. The waxy distillate was ex
column where the‘ solvent is vaporized with the
tracted with about 3 volumes of phenol at a tem
aid of stripping‘ steam. The recovered vapors are
perature of 180° F. The ra?inate resulting from
then condensed. The condensed product con
such extraction had an A. ‘P. I. gravity of 31.5",
sists of 50% MEK and 50% benzene and con~
a viscosity of 65 seconds Saybolt Universal at
densed steam.
‘
j
210° F., a pour point of 110° F., and a wax con
The wax separated in the above described'?lter
tent of approximately 23%. A 1000 volume por
is passed through a heat exchanger where it is 30 tion of the above described waxy raf?nate was in
heated to a suiiiciently elevated temperature to
troduced into tank! and subsequently heated to
effect vaporization of the solvent.‘ The heated
a temperature of‘ 150° F. soas to effect solution
wax-solvent mixture is then passed into a strip
of wax contained in the oil. The waxy ra?inate
ping column where the solvent is vaporized with
was then withdrawn from tank i through line 2,
the aid of stripping steam. The solvent vapors
controlled by valve 3, and pumped by pump 4
and steam are recovered from the stripping col
through line 5 and into chilling and mixing col
umn and passed to a'condenser. The condensed
umn 6. Column 6 was provided with Jacket ‘I
product consists of 50% MEK 50% benzene sol
which encircled said column, into which a cooling
vent and ‘condensed steam. The low melting
liquid to cool the wax-oil mixture was introduced
point solvent-g-free wax is withdrawn from said 40 via line 8 and withdrawn via line 8a. Column 0
stripping column and pumped to a storage. _>
was provided with agitating paddles and scrapers
The 90% MEK and 10% benzene solvent and
50% MEK 50% benzenesolvent, and condensed
steam recovered from the above steps,-respec- '
tively, are blended together.- The resulting prod
uct will consist substantially ‘of a 50% MEK and
50% benzene mixture with a minor portion of
condensed steam. This mixture isthen subjected
to azeotropic distillation in the presence of wa
ter to produce an azeotropicdistillate compris- .
ing about 19.0% MEK, 73.3% benzene, and ‘7.7%
,9 on shaft M which was rotated by pulley I I con
nected to, a source of power not shown. “The
molten wax-oil mixture was'gradually cooled in
column 6 to about 60° F. at a rate of about60° F.
per hour., During the cooling to 60° F. the con“.
tents of column 6 were constantly stirred by the
agitating paddles and scrapers by the rotation of
sameat a moderate rate su?icient to prevent the
wax mass from setting up into a solid mass.
The
thus cooled waxy ra?inate containing part of the
water and a residual fraction comprising 100%
MEK. The 100% MEK recovered as bottoms
from the azeotropic distillationv is removed from
wax content in crystalline form was then mixed '
the azeotropic column and passed to storage. .
The azeotropic distillate consisting‘ of MEK, ben
with 1700 volumes of approximately 90% methyl
ethyl ketone and 10%, benzene solvent. The-sol
vent was mixed ‘with the cooled wax-oil mixture
in column 6 and was withdrawn from storage tank
zene, and water, is removed from the azeotropic
I2 which'lcontained ‘100% MEK, and tank I3
column overhead and then condensed. The con
which contained ‘20% MEK and 80% benzene
densed distillate is cooled and then passed to a
solvent and introduced, into column 6 via lines It
settler wherein a separation occurs to form a ii) and I5, respectively, controlled by valves I6 and
lower layer of water containing a minor por
I1. and pumped by pumps l8 and I9 via lines 20
and 2|, respectively,- into line 22 and through
tion, such as about 2% MEK, and an upper layer
consisting of about 20% MEK and 80% ben
zene and a minor proportion of dissolved and
suspended water. The upper layer is removed
from the settler and passed through a salt drier
where the water and salt solution is removed,
leaving a non-[aqueous mixture of 20% MEK and
80% benzene which is returned to storage. The
lower layer-consisting vof waterand a minor pro
portion of MEK is removed from the bottom of
the settler and pumped either directly back to
65
cooler 23, and line ‘24 controlled by valve 25. The
MEK-benzene solvent pumped from tanks I2 and
I3, werevblended in the necessary proportions so
that~ the solvent entering column ii consisted of
approximately 90% MEK and 10% benzene. The
solvent ‘was cooled before introduction into ‘col
umn '6 to the temperatures prevailing in said col
umn by means of cooler 23.
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>
After the solvent ‘had been mixed with the
cooled wax-‘oil mixture containing the desired
the azeotropic distillation‘ column, or to a distil
crystallized'wax, the resulting slurry was with
lation tower wherein the MEK is distilled over.
drawn from the bottom or the column via line
‘In the latter case the distillate will contain a 75 26 controlled by valve 21 and pumped by pump
4
drawn via line 1!, vpetl‘olled by valve. 1-2. and
pumped by pump '13; through line 11!, heat ex:
changer ‘I5 and line 16, into 'strippingcolllmn 11
provided with means for lntrodlllgiiig. stripping
steam 18, where, thefsel'ventwas vaporizedironi
2.3_through,.1i_¥}§: 28st? fill-er.-v
was then
?ltered under, about
eignvhescf vacuum with
ten inches of, vacuum
thewashine section of
the ?lter. The calge on the ?lter» was then washed
with about 500 volumes oi-thell/IEK-benzene sole
the Wax, to produce. a distillate-consisting of 778
volumes of benzeneand 522 volumes of
and
61 volumes of water. The, molten crude slack.
removed with’ the aid of- 4,00 volumes of solvent
wax was withdrawn from the stripping column 11
introduced into said ?lter by'means of, lines 24
and 41 and controlled byval-vell?, via line .3 t, con 10 via line 19 controlled by valve 80 and pumped by
pump 8| through one 812 into» storage tank‘ 83. ,
trolled by valve 32 and pumped by pump 33
ventwhich was applied as a sprav. The wax cake
and occluded solvent, separated in ?lterv 30 were
The vaporized solvent and steam was removed
from the. stripping column by means of‘line 8A
controlled by valve .85. and pumped into line ‘4 I.
The condensed distillate. recovered from strip
ping columns 31, .171
‘62: and introduced into
line 4!‘ and admixed therein. consisted‘ of 3270
volumes of
and 3860 volumes. oi benzene
through heat exchanger“.- where.‘ it was heated I
to a suf?ciently elevated’ temperature to e?fejct
vaporization of the solvent. The heated wax was
then passed via line 35‘ controlled by valve 36
into stripping column .31 which was provided with
' stripping steam introdllqed therein through line
15
38, The solvent vapors'and steam were recovered '
from the stripping column via line. 39 controlled
by valve 40' and passed into line 4| ‘for passage
sol-vent and tzl'volumesoi vats?’ whichwas in:
troduced into alzeotropic distillation'coluinn 42), by
20
to azeotropic distillation column“. One hun
means of line. .85.
1'
"
'
'
‘
,
The mixture in the electrons column- weevils
dred‘and sixty (16,0)v volumes of_ high melting
' _
_ ‘
'
98131" re' of
vapor.
point waxremained aiter said stripping ‘opera, ' tilled with’ an ‘overhead
about 156° 1?. at which pointan azeotrope consist
tion, which was withdrawniromr stripping column
an. 3186c v.6. nines of
31'via line 43, controlled byjvvalve 4A, and pumped 2,5 ing of .993 volumes of
benzene solvent and lie-volumes 'oiwater was. dis!
by pump 65- into storage tank 46. The wax cake
tilled over, leaving as bottoms in the az'eotrope
recovered tested 158‘? F. melting point (Galiciahl,
column 2230 volumes of methyl ethyl ketone. The
.912, speci?c gravity at 60°F! and appeared to
above described oilel‘h?ad formed in, column ‘42
be oil-free. After- being treated with‘ only 8%
was withdrawn vialine 8:1‘ controlled. by valve. 88
of ?lter clay; it was a marketable water-white
and condensed and cooled to 809,‘ _. in condenser
wax.’ The total distillate recovered in the above
stripping operations consisted of 819, volumes of
90% methyl ethyl ketone 10% benzene solvent
and 40 volumes of water.
89 "and the condensate withd
thereirom by
wherein 2a separation'occurred to forman upper
layer consisting of 17 volumes voi: water and 4853
volumes of 20%
80%henzeneso1vent, and
means of line 91) and introducedinto settler 9i,
_ i
The oil solvent ?ltrate consisting of about ‘615
volumes of oil stock, v1781 volumes of 90% methyl
ethyl ketone,‘ 10% benzene solvent and 225 vol:
35
a lower aqueous layer consisting of 395 volumes
of water and 17 volumes of methyl $121131 k?tone
The lower layer was withdpawn i
settler 9!
umes of low melting point wax was then passed
into line 49 controlled by valveblland then mixed
with approximately 2420 vvolumes ofv 20%
via line 92 controlled. bvvalve 9312 i.
it)
'
"
_
' into distillation
column
.94
and..
a and 80% benzene solvent, from tank l3 via line 5,!
tillation at an overhead temperature of about
1.64? F. which produced, as an overhead wetmethyl
ethyl ketone consisting ‘of, .17.’! volumes of Water
and 17 volumes of methyl ethyl ketoneé The wet
and valve 52, thereby creating; arnixture consist~
ing of 615 volumes'of- oil stock,'4201.volumes of
‘50%‘MEK, ‘50% benzene solvent and 225 volumes
of low melting point wax The resulting mixture
was then passed into chiller 53 where the solu
tion was chilled to about 15° F. in order to pre
cipitate the low melting point wax from, these
lution.
The resulting slurry was withdrawn via line .54
controlled by valve 575. and pumped by pump 56 in
to ?lter 51 and ?ltered under a vacuum of, about
3 inches to separate the. precipitated .Wax from
the chilled slurry. The ?ltration rate was ill
gallons per square foot of ?lter area'per hour.
Four hundred ‘($00) volumes of solvent was then
._§
lubieote. v to dis;
50
MEK distilled over was in drawn via line 95
controlled by valve ??vand copied in a cooler, not
shown, and then introduced into. salt‘drier 91
where the water and salt solution was removed
by means of line 9,3; The dry MEK was with
drawn via line 98a, controlled by valve 99 and
introduced into line. “in, and then to 100% MEK
storage l2, The upper layer in settler 91 was
withdrawn therefrom via line, “H controlled by
P valve I02 and introduced into salt drier L03
wherein the water and salt solution was removed
and disposed of_ through line 1 I14 to yie1'd'fi852
volumes of 20% MEK ‘and 30% benzene solvent.
added to the wax calge having occluded solvent,
so as to facilitate the removal of the'said cake
from the ?lter. The filtrate consisting of 6:15
The dry solvent ‘was withdrawn via linev l 05‘ con
volumes of oil plus4981 volumes of solvent was 60
trolled
39% benzene
by valve
solvent
L06 and
‘storage,
introduced
13 ‘for‘into’
blending
2.0%. with
dry
from tank 12 hetero recycling to the
?rst deoiling stage, The water-remaining in dis
--tillation,_column at was; withdrawn via line I01
then passed via line 58 controlled by valve 59
through heat exchanger 60 and line 6.! into strip.
ping column 62 provided with a means for intro
ducing stripping steam 63 where the solvent was
vaporized from the’dewaxed 0.1-1 which yi?lded as
controlled by valve -_l>ll8"and intijodnoed into azeo
,azeotrope. former.
The-bottoms" in the azeotropic distillation c.01
urnn 42 consisting p: 109%.
was Withdrawn
via line I09 controlled by'valv'efl lllfand pumped
bypump in through line‘ we andinto 10.0%
storage I2,’ where ‘it
ithdrawn v.for recycling
tropic column 42 via lines VIII and 785 to act as an
an overhead fractiona solventconsisting of 1981
volumes of ME}; and 3000'volumes of benzene
and 220 volumes of water. The dewaxed oil was
withdrawn from the stripping column ‘62 via line
54 controlled by valve 65 and pumped by pump
.65 through line 5] into storage tank-68. The
vaporized solvent and steam was removed from
the stripping column by means .ot line 59 con
trolled by. valve‘lq andintrodueed into line 4 l, I
The wax cake andsolvent in'?lter 51 was with
to the ?rst deoiline stage A
76
hematite in
case were is inset, ‘.ent ‘400M911 d at am in the
feed to azeotropic celumn ?gtlie lower layer of
, 2,897,868
_ water from settler 9! may be introduced into col
umn 42, by means ‘o'fline; 92;‘oontrolled by valve
proximately 90% methyl, ethyl ketone and 10%
benzene, and the low melting wax is separated
at lower‘temperatures'in the second stage by a
dewaxing solvent containing approximately 50%
methyl ethyl ketone‘a‘nd 50% benzene,‘ the step
which comprises steam stripping the high melting
wax containing occluded’ solvent, low melting
93, and ‘lines 4| and 86 in'steadof ‘routing same
into column 94, as described above. '
e 5
y
The foregoing two-stage dewaxing ‘and solvent
recovery process hasbeen described with refer
ence to the treatment'of ra?inates. Itvwill be
, understood that I maytreat any wax-oil mixture
wax containing occludedv solvent and lubricating
in two stages, as above, whether it be an oily wax,
oil containing solvent, separating the solvent and
such as a slack wax which has been‘separated 10 steam from the waxland-oil and azeotropically
from oil by conventional dewaxing processes, or
distilling the solvent which is poor Tinniethyl ethyl
a waxy oil such as raw waxy distillate.
ketone, in the presence of a sufficient additional
It will beobserved that in the foregoing de
amount of water, whereby'two fractions are ob
scription ‘of the invention I have shown'that a
tained one of which consists of- methyl ethyl ke
mixture consisting of approximately 90% MEK 15' tone free from benzeneand the other of'which
and 10% benzene is used asa solvent in the ?rst
consists of water and benzene containing about
stage (deoiling stage) and a mixture consisting
20% of methyl ethyl ketone, removing the water
of approximately 50% MEK and 50% benzene
from the second fraction, leaving "a s'olvent'con
in the second stage (dewaxing stage). However,
sisting of approximately 80% benzene and ‘20%
it is to be understood that the invention is'in no 20
' way limited to the use of'these speci?c mixtures.
In fact, the invention includes any solvent treat
ment in the two stages described above by means
of a MEK-benzene solvent mixture wherein the
MEK concentrate is greater than 20%. » The sol
vent mixture of MEK and benzene is governed
and controlled by the amount of 100% MEK
solvent from solvent storage l2 and 20% MEK,
80% benzene solvent mixture from storage l3 in
troduced into the system.
The solvent employed a
in the ?rst dewaxing stage is preferably richer in
methyl ethyl ketone than the solvent employed
in the second stage.
The preferable solvent for
use in the ?rst stage should have a MEK concen
tration ranging between about 80% to 100%.
The MEK concentration in the second stage sol
vent is preferably between about 40% to 60%,
although the invention is not limited to these
concentrations.
The foregoing exemplary description of my in
vention is not to be considered as limiting since
many variations may bemade by those skilled in
the art within the scope of the following claims
methyl ethyl ketone.
.
‘
"
v
»
-
. 3. A process for‘the separation of wax-oilmix
tures which are solid at‘ the herein described
temperature of wax ‘separation which comprises
bringing said oil to‘ a state whereinthe wax pres
ent is substantially completely dissolved in the
oil present in said mixture, slowly cooling said
Wax-oil solution to crystallize the high melting
wax with slow agitation in the presence of a
quantity of methyl ethyl ketone-benzene solvent
suii‘icient to reduce the viscosity of the wax-oil
but insu?icient in amount to maintain the waxy
oil fluid at the dewaxing temperature in the ab
sence of said agitation, commingling said cooled
mixture containing high melting crystallized wax
with a cooled dewaxing solvent containing methyl
ethyl ketone and benzene wherein said solvent
is rich in methyl ethyl ketone, separating the
solvent solution of oil and non-crystallized low
melting wax from the crystallized wax, slowly
cooling said solvent solution of oil and non
crystallized low melting wax with a dewaxing
solvent containing methyl ethyl ketone and ben
zene wherein said solvent is poor in methyl ethyl
without departing from the spirit thereof. It
ketone, separating the solvent solution of oil from
will be observed that in the foregoing description 45 the low melting crystallized wax, separating the
of the drawing, I have shown only single pieces
solvent from the oil and azeotropically distilling
of apparatus for carrying out the process. It is
to be understood that duplicate equipment may
be provided where necessary, which may be op
erated alternately so that the process may be 50
carried out more or less continuously.
I claim:
1. In a process for the separation of a mixture
the solvent in the presence of Water.
4. A process for the separation of wax-oil mix
tures which are solid at the herein described tem
perature of wax separation. which comprises
bringing said oil to a state wherein the wax
present is substantially completely dissolved in
the oil present in said mixture, slowly cooling
comprising lubricating oil, low melting wax and
said wax-oil solution to crystallize the high melt
high melting wax, wherein the separation is ef
ing wax with slow agitation in the presence of a
55
fected in two stages in which the high melting
quantity of methyl ethyl ketone-benzene solvent
wax is separated in the ?rst stage by a dewaxing
sui?cient to reduce the viscosity of the wax-oil
solvent containing approximately 90% methyl
but insu?icient in amount to maintain the waxy
ethyl ketone and 10% benzene, and the low melt
oil ?uid at the dewaxing temperature in the ab
ing wax is separated in the second stage by a 60 sence of said agitation, commingling said cooled
dewaxing solvent containing approximately 50%
mixture containing high melting crystallized wax
methyl ethyl ketone and 50% benzene, the step
with a cooled dewaxing solvent containing ap
which comprises fractionally distilling the sol
proximately 90% methyl ethyl ketone and ap
vent which is poor in methy ethyl ketone, in the
proximately
10% benzene, separating the solvent
presence of a su?icient amount of water, whereby 65 solution of oil and non-crystallized low melting
two fractions are obtained one of which consists
wax from the crystallized wax, slowly cooling said
of methyl ethyl ketone free from benzene and
solvent solution of oil and non-crystallized low
the other of which consists of water and benzene
melting wax with a dewaxing solvent containing
containing about 20% of methyl ‘ethyl ketone.
approximately 50% methyl ethyl ketone and ap
2. In a process for the separation of a mixture 70
proximately
50% benzene, steam stripping the
comprising lubricating oil, low melting wax and
high melting wax containing occluded solvent,
high melting wax wherein the separation is ef
low melting wax containing occluded solvent and
fected in two stages in which the high melting
lubricating
oil containing solvent, separating the
wax is separated at higher temperatures in the
solvent and steam from the wax and oil and azeo
first stage by a dewaxing solvent containing ap
tropically distilling the solvent which is poor in
31
H
benzemi‘and 20%metm1-éthx1 ketbne-;.. ;
‘contains “approximately-v 90% methyl, ethyLke
.mne and-approximately .10 %i;benzene ‘ ma quan
~ tityj-sut?vcientgnpmdpceja solvent therein pon~
tailing. apnm?mate1y‘5o%vmebhy1 ethyl ketone ~
and approximately 50% benzene]. ;
'..;;6. ‘A pmcessiad?prdmg V’gbjciaim A v{wlrxgareinl the
.‘ia‘st namm. soivent. 'c'onsisting 10f approximately
:_80.!Z/7,a,.~;:henzianev , ‘and 1 20 %w ‘methyl ' ethyl ketone. ‘ is
blended; with methyl ethyl ketone fr'ee, from hen
zene, v which is; pmduced (as fine. fraction ‘in ‘the
‘ a'zéotro‘pic distillation to prdduce a solvent con- ~
benzene.