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Патент USA US2404061

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Patented July 16, 1946
Julian P. Hamilton, Pelly, and Charles F. Jones,
Goose Creek, Tex., assignors to Standard Oil
Development Company, a corporation of Dela
No Drawing. Application October 19,1943,
Serial No. 506,898
5 Claims. (01. aloe-201)
"The present‘ invention is directed to a method
for ?ltering in which a sheet ?ltering surface is
be’ absolutely inert but may contain ‘a’ minor
precoated with a ?ltering aid before the ?ltering
operation is begun.
supplementing the preceding postulate, is that
amount of oxygen ‘which oxidizes these'mate
The present'invention is particularly applica
ble to the ?ltration of asphaltic or gummy ma
5 the tarry, or resinous materials are relatively ?uid
at the temperatures of the order of ‘600° 'F. em
terials by-means of rotary ?lters.- An example
of such an operation, is the ?ltration of' cracked
tars- in petroleum re?neries through a rotating
?ltering element with the ?ltering element pro
vided with a'precoatingo'f ?ltering aid, such as
ployedfor the ?ltering step but are substantially
solid at the temperatures ‘of‘the order of‘_250° F.
commonlyused for washing and discharging the
9 ?lter; iltwillibe understood that-these postulates
explaining the formation of the (residual heel in
the ?lterduring conventional ?ltering operations
diatomaceous earth, before the tar is passed
through the ?lter. '
'Anothelr'explanation, Or an explanation
are suggested only byway “of explanation and are
in, no wise intended to‘ limit the, present, inven
It has been known to the art to ?lter tarry
or resinous material, such ‘as. hot. cracking coal 15
tars, througharotary' ?lter. _ In this operation
. We have .now discovered that a greatly in.
it has been ‘customary 'to deposit preliminarily
upon the ?lter screen adiatomaceaus'earth pre
creased ?ltering capacity may be obtained when
?ltering cracked tars and other tarry or resinous
.coat with a thickness of the order of three inches.
material. ’ In accordance with our discovery,
As the ?lter, surface revolved the precoat was
the ?ltering operation is terminated before the
resinous or tarry materials being separated from
the filtrate penetrate through the precoat torthe
?lter screen. The charge remaining within the
?lter shell ‘is discharged therefrom, being @re
placed, for example, with gas oil and the portion
of the precoat into which the resinous ‘and tarry
-materials have penetrated is trimmed __0f_fiby. the
trimmed o? at a rate of from,0.001 to 0.003 inch
per revolution of the ?lter drum until the pre
coat remaining was no more, than one-quarter
of an inch thick. It has then been customary
to displace the hot cracking tar with a cooler ,25
liquid to coolthe‘?lter shell, as m‘uchyof this
cooler liquid being drawn through the ?lter as
possible and the remainder pumpedout. The
?lter screen and remaining precoat was then
sprayed vwith gas oll?to remove asmuch of the
precoat and depositedgsolids as possible. In such
?lter knife or‘ doctor. ~ After the removal-'of'the
plugged portion of the precoat-the.remaindercf
30 .the‘precoat, free from binding and plugging ma
terials, is either. removed entirely by washing or,
a procedure, however, substantial amounts of re
alternatively, it is left on‘the ?lter ‘screen as a
sidual materials from the tar penetratethrough
base and anew layer of precoat deposited on the
-‘ the precoat to the screen and theresidual heel 35 ?lter and the ?ltering cycle repeated.
is plugged and bound to the ?lter screen by these
tarry or resinous materials. This contaminated
‘I The improvement in the capacity of the ?lter
by the employment of the present invention is
indicated in the following table, in which the
heel cannot be removed from‘ the ?lter by wash
ing with‘ gas oil or a similar solvent and,‘ ac
conventional procedure is shown under the head
ing “Old operation” with runs 1, 2 and ‘3' and
the employment of the present invention shown
under the'heading “Newv operation” with runs
use of steel brushes. In such operations the time
4, 5 and 6. Whereas, the ?ltering time per, cycle
required to openlthe ?lter and clean the screen
under the old operation is somewhat longer than
was large withrespe‘ct to the total ?ltering cycle.‘
The exact nature of the tarry or resinous ‘ma 45 under the new operation, the turnaround time has
terials which penetrate below the surface of the ..been so reduced under the new operation that
cordingly, it’has been necessary to open the ?lter
and remove the remainder of the precoat and 40
the tarry materials plugging the" screen, by the
nrecoat and ‘act to plug and bind the residual
heel to the ?lter screen is not known. As a pos
the total time per cycle is much less under the
new operation and gives a greatly increased ca
tulate, it is suggested ‘that the hot cracking coal
“pacity factor. The three runs carried out un—
'_ ?ltered include viscousor resinous liquids which
' penetrate into the precoat and forma coating on.
the surfaces of the particlescomprising the pre
the new operation had an-average‘cycle time of‘
der the old operating conditions had an aver
tens or viscosity breaker bottoms conventionally 50
age oycle time of 85 hours, while the runs under
r 53.7 hours and the capacity factor of the ?lter
was increased from 62.1 per cent under the old
.rcome coked atthe vhigh temperature of ?ltraa 55.
_ operation to 81.7 per cent under the new opera
_ coat.‘ These tarry or resinous materials may be
_ tion, orthe gas employed-"in the ?lter-may-not
. tion.
Old operation, average
New operation, average
Run No.
Turnaroundtime ______________________ __d0____ 15.0
Cycletime ______________________ _-do_.__ 74,8
49.7 65.7
72.9 -79.8
Cycle time """""""""" "
75.8 ‘83.4
Capacity factor:
41.5 48.5
While we have disclosed speci?c examples of
the application of the present invention to the
?ltration of viscosity breaker bottoms and other
A slurry of diatomaceous earth in gas 011 was
viscous cracked tars consisting of asphaltic ma
forced into the ?lter shell and gas oil passed
through the ?lter medium until a diatomaceous
terial, it is to be understood that the invention is
earth precoating three inches thick formed on
not limited to the ?ltration of this speci?c ma
the ?lter screen. The slurry was then displaced
terial but may be applied generally to the treat
from the ?lter shell and viscosity breaker bot
ment of materials, having incorporated therein
toms at 600° F. passed through the ?lter while
tarry or resinous matter capable of penetrat
the screen was rotated at a uniform rate and the
ing a precoat to aconsiderable depth and which
precoat trimmed off at the rate of 0.001 to 01103 25 may combine with the solid particles of the pre
inch per revolution of the ?lter until a layer of
coat during the ?ltering operations and act to
precoat one-quarter inch thick remained. The
plug the precoat and bind it to the ?lter screen.
?lter shell was then cooled by replacing the vis
It will also be understood that the method of the
cosity breaker bottoms with cracked tar at 250°
present invention is by no means limited to the
F. This tar was drawn through the ?lter in a 30 speci?c temperatures given in the examples ‘but
normal manner and the residual tar in the ?lter
thatv it may be practiced over a wide range of
shell then pumped out. The ?lter screen was
then sprayed with gas oil to remove as much of
Having fully described the present invention,
the precoat as possible and the ?lter then opened
and the ?lter screen scrubbed by hand with steel 35 what we desire to claim is:
1. A method for?ltering wherein a viscous liq,
brushes. After this operation the screen was
uicl containing solids and substantial amounts of
closed and the cycle was repeated.
Runs 1, 2 and 3 in the above table were conducted
as follows:
tarry materials capable of penetrating through
Example 2.-New operations
a substantial thickness of precoat is passed
The precoat was formed on the ?lter screen in 40 through a moving ?lter screen provided with a
the same manner as in Example 1. The viscosity
breaker bottoms at 600° F. were then passed
through the ?lter medium while the precoat was
progressively removed by the ?lter knife until
about three-quarters of an inch of the precoat 45
substantial thickness of precoat, comprising the
steps of continuously removing a thin layer of
precoat and deposited solids from the ?ltering
element while the w‘scous liquid is being passed
through the element, terminating the ?ltration
remained on the ?lter.
Cracked tar at 250° F.
of viscous liquid while a substantial thickness of
was then charged to the ?lter to cool it down
the precoat adjacent the screen is uncontami
with the tar being drawn through the ?lter but
nated with the tarry materials, removing alayer
no precoat being removed during the cooling op
of the remaining precoat, having a thickness of
eration. The residual tar was then pumped out 50 the order of 1/2 inch and including at least that
from the bottom of the ?lter shell and the knife
portion of the remaining precoat contaminated
blades advanced to remove approximately one
by the tarry materials, subsequently providing the
half inch thickness of the precoat, leaving a layer
?lter screen with the precoat layer of substantial
only about one-fourth inch thickness ofthe pre
thickness and repeating the cycle.
coat on the ?lter shell. A slurry of diatomaceous 55
2. A method for ?ltering comprising the steps
earth in gas oil was then pumped into the ?lter
of depositing a relatively thick layer of ?lter aid
shell and new precoat deposited directly upon
on a rotating ?ltering element, passing a viscous
the one-fourth inch layer of precoat to build up
tar containing solids and substantial amounts of
another precoat three inches in thickness and
the ?ltering cycle was then repeated. The char 60 tarry materials capable of penetrating through
a substantial depth of precoat therethrough and
acteristics of the viscosity breaker bottoms,
continuously removing a thin layer of precoat
cracking coal tar and gas oil passed to the ?lter
and deposited solids from the moving ?ltering
in the above examples are as follows:
element to provide a freshly exposed layer of pre
Table II
coat with every revolution of the ?lter, termi
Gravity, "APL _ 7. _____ ___ _______ ._
coal tar
11. 0
Gas oil
SSF at 122° F_
SU at 100° F“
By extraction, wt. percent_.__.
By hot ?ltration, wt. percent.
0. 25
0. 05 ________ __
0.06 ________ __
nating ?ltration of the tar while the remaining
precoat layer is of substantial thickness and be—
fore the tarry materials deposited thereon have
penetrated that portion of the precoat adjacent
the ?lter screen, removing the tar from contact
70 with the ?ltering element, removing a layer of
the remaining precoat having a. thickness of the
order of 11; inch and including at least the con
taminated portions of the precoat remaining on
the screen, providing a new precoat layer of ap
75 proximately the same thickness of the layer‘at
the beginning of the cycle and repeating the
penetrating cycle.
3. A process in accordance with claim 2 in
which a thin layer of uncontaminated precoat
of 600° F. in contact with said ?ltering element '
and ?ltering tar from said pool through said ?l
tering element and continuously removing a thin
layer of the precoat and deposited solids from
said ?tlering element while the viscous tar is
being ?ltered, terminating the ?ltration of said
precoat layer.
tar when the precoat layer has been reduced to
4. A method in accordance with claim 2 in
a thickness of the order of 3/; inch, replacing
which all of the precoat layer is removed from
the tar in the pool with low viscosity tar at about
the ?lter screen, and the new precoat layer is 10 250° F. to cool the ?lter, removing the low vis
built up directly on the ?lter screen.
cosity tar from said pool, removing a layer of
5. A method for ?ltering comprising the steps
said precoat having a thickness of the order of
of depositing a layer of ?lter aid on a rotating
1/2 inch and including a contaminated portion,
?ltering element to a thickness of approximately
subsequently depositing a new layer of precoat
3 inches, forming a pool of highly viscous tar 15 on said ?ltering element to a depth of approxi
is retained on the ?lter screen and additional
precoat is deposited thereon to build up the new
containing solids and asphaltic material capable
of penetrating a substantial depth into a, layer
of precoat and at a temperature of the order
mately 3 inches and repeating the cycle.
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