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Патент USA US2066165

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Dec. 29, 1936..
G. J. sTREzYNsKl
PRocEss .oF PURIFYING AND DEWAXING MINERAL oILs
V’
Filed June 27, 1935
Apo/r/a/VAL Pl/MPJ
26,066,165
2,066,165
Patented Dec. 29, 1936
UNITED STATES
PATENT OFFICE
2,066,165
PROCESS OF PURIFYING AND DEWAXING
MINERAL OILS
George J. Strezynski, Poughkeepsie, N. Y., as
signor to The De Laval Separator Company,
New York, N. Y., a corporation of New Jersey
Application June 27, 1935, Serial No. 28,656
i)
2 Claims. (Cl. 196-21)
In an application ñled by me June 27, 1935, step of the process and particularly to the tem
Serial No. 28,655, I describe a process for purify
perature of the acid added in its relation to the
ing and dewaxing mineral oil containing both temperature to which the oil ischilled. The tem
amorphous and crystalline waxes and producing perature of chilling, dependent Aon the desired ,
therefrom a dewaxed lubricating oil having a pour point of the finished oil, may vary from
high pour test. In this process, which is prefer
about 0° F. to _50° F. Since the freezing point
ably applied to crude oil from which no or feW of sulfuric acid of the high concentrations that
light fractions have been distilled, but which is give the best results may vary from about _8° F.
also applicable to any heavy fraction of the to not much above 30° F. (usually in the upper .
crude, such as the long residuum containing all part of such range), it is `obvious that, if there
or most of the lubricating fractions, the crude is
blended with any suitable light diluent, such as
naphtha or other light hydrocarbon, and the
blend is subjected to chilling, preferably shock
chilling with pronounced agitation, to reduce its
temperature to approximately 35° F. below the
desired pour point of the finished oil. The dil
uent is added in such proportion that the treated
blend, after addition of acid, will, when centri
20 fuged with a force 6000 times gravity, gives a
heavy layer of waxy acid sludge not less than
15% or more than 30% of the mass of the chilled
and treated blend. After the chilling step,
wherein all the wax, amorphous and crystalline,
is precipitated (that is, all the wax is precipi
tated down to the temperature of the pour point
desired), a continuous stream of acid is added
to the continuous stream of the mixture of oil
and wax ñowing from the chiller and the two
streams are subjected to a mixing action, the
acid combining with undesirable compounds (im
purities) in the oil and wax to form a waxy acid
sludge. The treated mixture then flows contin
uously to a centrifuge wherein a purified com
pletely dewaxed oil is separated from the sludge.
In the process set forth in said application, the
oil is chilled, for example, to a temperature of
approximately _16° F. if it is desired to produce
a finished lubricating oil having a pour point of
40 20° F., or to approximately _35° F. if the ñn
ished lubricating oil is desired to have a pour
point of 0° F. In the specific example of the
process therein given, there is treated a typical
east Texas paraffin base (more accurately mixed
45
base) crude containing gasoline about 29%, kero
sene about 14%, gas oil about 21%, wax and
asphaltic material about 12% (wax about 8%)
and lubricating oil constituents 1'7-18%, which,
when separated, give a lubricating oil having a
50 pour point of 20° F., viscosity index 86 and
viscosity 67.
The present process is not concerned with the
centrifugal separating step of the process where
by there is secured a maximum yield of the qual
55
ity of oil desired, but relates to the acid. addition
were no chemical reaction, the acid would freeze
almost immediately upon >coming into contact
with the cold oil. The chemical reaction, how
ever, produces a certain amount of heat and this
prevents the immediate freezing of the acid. It
has heretofore been deemed necessary to add
the acid at a reasonably low temperature in order
to avoid too great a rise in the temperature of the
mixture of cold oil and wax.
'I‘he reaction con-
Y
sequently proceeds so slowly that eventually a 20
certain amount of acid freezes into hard crystals
and causes clogging and overflow.
The use of
fuming acid has been suggested, but the freezing
point of fuming acid is higher than that of 98%
acid.
~
I have found, however, that if the oil is chilled
to a temperature more than 30% below that of
the desired pour point of the finished oil, that> is,
below what has been deemed necessary, and if
the added acid is at a substantially higher tem 30
perature than that hitherto employed, the
chemical reaction is so far expedited and the
heat generation so far accelerated that the re
action will be completed before the acid is suf
ñciently reduced in temperature to freeze, there 35
by eliminating the clogging elfect of acid crys
tals. While the temperature of the oil and Wax
mixture is thereby raised more than it otherwise
would be, it Will not be raised above the permis
sible maximum if, in the initial chilling, it is 40
chilled to only a very few degrees below the
temperature required if the acid were added
while comparatively cold. To prevent freezing,
the temperature of the acid sho-uld be above
110° F. More desirably it should be added at a 45
temperature within about 10° F. of 150° F. It
will be understood that the hotter the acid, the
greater must be the degree of refrigeration. It
is permissive to add the acid at a temperature
substantially higher than 150° F., but it is un 50
economical to do do so, since it involves the ex
pense of refrigeration to a lower temperature
with no corresponding gain.
The amount of acid added may be varied With
in limits at the discretion of the operator. The 55
2
2,066,165
desirable amount will vary with the desired pour
test of the finished oil. Thus, in producing 20°
F. pour test oil, a preferable addition of acid is
patents granted to me December 3, 1935, No.
2,022,814, No. 2,022,815, No. 2,022,816, and No.
about 12 to 14 pounds per barrel of oil, or about
21/2%; While in producing 0° F. pour test oil,
It will be understood that I do not herein claim,
separate and apart from the above described
a preferable addition of acid is about 24 to 28
pounds, or about 5%. The amount of acid in
these examples is about 20% moreL than is used
in conventional methods and is distinctly above
10 the amount required to produce the necessary
reaction.
The addition of acid in such substan- 5
tial excess is of advantage invse’veral respects.
It insures a sufficient gravity> differential be
tween the oil and sludge. It speeds the reac
15 tion. It results in the production of a lubricat-`
ing oil having a higher viscosity index number
than is obtainable by the addition of a smaller
quantity. It decreases the temperature spread
between the operation temperature and the pour
I
20 point of the finished oil.
, Referringto the drawing, which is a diagram
or flow sheet of an apparatus for practicing the
above described process: Separate streams of the
oil tor be dewaxed and purifiedV (which may be
2,022,817.
'
process, certain novel features thereof, such as
the regulation of the percentage of the diluent,
which form the subject matter of an application
filed by Strezynski and Pfau >July 25,1935, Serial
No. 33,073.
n
n
mineral oil to obtain therefrom high test pour
oil, which comprises chilling the oil to a tem 15
perature below 0° F. to precipitate the wax, mix
ing concentrated sulfuric acid with the mixture
of oil and precipitated wax and centrifuging the
resultant mixture of waxy acid sludge and puri
fied dewaxed oil and thereby effecting their sepa
ration; the improvement which comprises,ìin the
chilling operation, sub-cooling the oil below the
temperature that would be required, if cold acid
Yand a diluent, such as naphtha, are delivered'to a
were added, to subsequently produce purified de
waxed oil of the desired pour point, and, in the
acid treating operation, adding the acid While at
blending tank I0, whence the oil is pumped
a temperature above 110° F. to thereby, by ac
through a chiller II and therein sub-cooled to a
temperature. of . about l35° `F. below the desired
pour test of the finished oil. The chilling opera
celerating the generation of heat by the reaction,
prevent freezing of the acid before completion of
tion will precipitate all the wax which precipi
pitates at the temperature of chilling. By means
2. In the process of purifying and dewaxing
mineral oil to obtain therefrom high testV pour
oil, whichfcomprises chilling the oil to a tem
perature below 0° F. to precipitate the wax, mix
crude oilV of the character hereinbefore described)
of a pump I2 the mixture of oil and wax is con
veyed to a mixer I4, which may be a centrifugal
35 pump. YInto the oil line leading to the mixer I4
is conveyed, through a pump I3, a stream of con
centrated sulfuric acid (preferably about 98%
H2804) at a temperature of about 150° F. The
mixing may be completed in the pump I4, or it
40 may berun through an additional mixer I5, which
maybe a series of centrifugal pumps. The acid
reacts with the oil and forms a mixture of waxy
acid sludge and oil, the latter usually contain
ing'wax in ñne suspension but otherwise purified.
45 The mixture is then conveyed to a centrifuge I6,
which is specially designed to act upon the mix
ture so as to enable the recovery of completely
dewaxed oil. Suitable centrifuges are shown in
10
What I claim and desire to protect by Letters
Patent is:
1. In the process of purifying and dewaxing
the raction.
,
ing concentrated sulfuric acid with the mixture
of oil and precipitated wax and centrifuging the
resultant mixture of waxy acid sludge and puri
fied dewaxed oil and thereby effecting their sepa
ration; the 'improvement which comprises, in the
chilling operation, sub-cooling the oil below the 40
temperature that would be required, if cold acid
were added, to subsequently produce purified de
waxed oil of the desired pour point, and, in the
acid treating operation, adding the acid while at
a temperature Within 10° F. of 150° F. to thereby 45
speed the reaction and prevent freezing of the
acid before the completion of the reaction.
'
GEORGE J. STREZYNSKI.
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