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Патент USA US3066097

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Nov. 27, 17962
R. J. PHILLIPS
3,066,087
PROCESS 0E REDUCING SULFATE CONTENT IN STOCK FEED
Filed oct. 12, 1959
2 Shee‘bs--Sheei'I l
Nov. 27, 1962
3,066,087
R. J. PHILLIPS
PROCESS OF REDUCING SULFATE CONTENT IN STOCK FEED
Filed Oct. 12, 1959
2 Sheets-Sheet 2
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BY
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United States
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3,055,057
Patented Nov. 27, V1962
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2
3,065,037
tween 6 and l2 inches from each other, with electrode
potentials of 1900 to 2500 volts per inch of electrode
Robert J. Phillips, Tyler, Tex., assigner to Howe-Baker
Engineers, Inc., Tyler, Tex., a corporation of Texas
Filed Oct. 12, 1959, Ser. No. 845,758
2 Claims. (Cl. 204-190)
tem whereby the deviation of the maximum voltage from
the average voltage, normally referred to as the “ripple
factor” is reduced to a low substantially steady state. It
has been found through actual practice that when the
above arrangement is employed, an efficient separation of
PROCESS GF REDUCING SULFATE CONTENT
1N STOCK FEED
spacing; the current being supplied by a three-phase sys
This invention relates to new and useful improvements
in methods of and apparatus for treating hydrocarbon 10
streams to reduce the sulfur content, and relates particu
larly to the treatment of the products of distillation which
comprise petroleum fractions.
This application is filed as a continuation-in-part of
the sulfur content is effected.
Y
Still another object is to provide an improved method,
of the character described, which includes not only the
initial sulfur-removing step, but which also may include
a subsequent caustic-neutralizing step followed by a water
wash to provide a complete process for producing a de
my co-pending application Serial No. 601,919, filed 15 sulfurized product.
Y
August 3, 1956, and now abandoned.
The construction designed to carry out the invention
In refining operations, certain products of distillation
will be hereinafter described, together with other features
contain undesirable or deleterious components as, for ex
thereof.
ample, in the case of catalytic reformer feed stock, which
The invention will be more readily understood from a
stock is high in sulfur content. The presence of sulfur 20 reading of the following speciñcation and by reference to
in the feed stock, unless removed, causes corrosion in
the accompanying drawings forming a part thereof, where
the reformer units due to the formation of hydrogen
in an example of the invention is shown, and wherein:
sulfide, a reaction product of hydrogen and sulfur.
FIGURE l is a diagrammatic View or flow diagram of
Industry has recognized the problem of sulfur content
the apparatus for carrying out the improved method or
and various methods and treatments directed toward re 25 process; and,
duction and removal of sulfur content have been em
FIGURE 2 is a horizontal, cross-sectional view of the
ployed, but such prior treatments have involved specially
designed and economically expensive apparatus without
providing a completely satisfactory solution to the prob
lem.
'
electrical treating apparatus which is employed in the
process; and,
'
FIGURE 3 is a transverse, vertical sectional view,
30 taken on the line 3_3 of FIGURE 2.
Prior to the present invention it has not been believed
possible to accomplish the result with a relatively simple
In the drawings (FIGURE l) the numeral 10 indi
cates an inlet conductor through which the hydrocarbon
type electrical treater, but I have found that by proper
stream which is to be treated is directed. The invention
control of the electrical treating zone as to voltage and
has been found particularly applicable to the treatment
electrode spacing, and also by accurately controlling the 35 of catalytic reformer feed stocks or streams for the pur
contact time of the material both Within an initial mixing
pose of reducing the sulfur content of such streams. As
zone and within the electrical treater, an efficient process
is well known, a catalytic reformer feed stream contains
for effectively reducing the sulfur content of the hydro
a relatively high sulfur content which creates deleterious
carbon feed may be carried out.
effects in the equipment, such as the reformer units,
It is therefore one object of this invention to provide a 40 through which the stream is subsequently directed. Al
very simple and improved practical method or process
though the invention is particularly adapted for the treat
for effectively reducing the sulfur content of hydrocarbon
ment of this type of hydrocarbon stream and will be de
streams such as reformer feed stocks, whereby -the damag
scribed herein as applied thereto, the invention has ap
ing effects of corrosion to the equipment through which
plication in the treatment of other hydrocarbon streams.
the stream or feed stock is subsequently directed are 45
The inlet conductor 10 conducts the >hydrocarbon
eliminated.
stream containing sulfur components into a mixer 11
An important object is to provide an improved treat
which is illustrated as a vessel having rotatable mixer
ingmethod, of the character described, wherein sulfuric
blades 12 therein. For controlling the flow or volume
acid is intimately admixed with the feed stream for a
of the hydrocarbon stream a suitable flow controller 13
controlled period of time and the mixture is thereafter
is connected in the inlet conductor 10 in advance of the
directed through an electrical precipitator and is subject
mixer 11. Sulfuric acid is introduced into the mixer il
ed to the action of a single electrical treating zone with
through a line 14 and within the mixer the acid-hydro
the contact or residence time of the stream within the
carbon solution is vigorously and intimately mixed to
precipitator being accurately controlled so that the sulfur
reduce the acid particle size to an optimum diameter and
content of the stream is reduced and other deleterious 55 to cause the acid to begin reaction with the sulfur com
components such as nitrogencompounds are removed or
ponents in the stream. As is well known, an oxidation
reduced.
reaction of said sulfur components occurs which converts
` A particular object is to provide an improved treating '
the components to the disulfide form, in which form the
method wherein the electrical treatment of the hydro
re-action products are preferentially soluble in the acid.
carbon-acid dispersion performs adual function in that 60 The residence time of the hydrocarbonand acid in the
it subjects said mixture to “electrostatic mixing” to assure
mixer is important since it is desirable to reduce the size
of each acid particle suiiiciently to obtain maximum con
ponents in the hydrocarbon to the disulfide form whereby
tact area and also to assure mobility of the particle within
said components in disulfide form may enter into solu
an electrical field when said particle is subsequently sub
tion with the acid, and at the same time subjects the 65 jected to electrical treatment; however, if the acid par
hydrocarbon-acid mixture to the electrical field to effect
ticles are too small, efficient subsequent separation of the
coalescence of the acid products to promote separation
acid from the hydrocarbon >cannot be etiiciently carried
thereof from the hydrocarbon stream.
out. Thus, to obtain “optimum” particle size the energy
Another object is to provide an improved method and
imparted to the mixer and the residence time of the hy
apparatus, of the character described, wherein the acid 70 drocarbon-acid in the mixture is controlled and is related
treated stream is subjected to a direct current electrical
i to the through-put through the system so that the particle
field which is created by spaced electrodes located be- . size of the acid is reduced to assure maximum contact
completion of the oxidation reaction of the sulfur com- f
3,066,087'
„ja
4
area without such a great reduction in size as to cause
wardly into the vessel and has connection with a distribu
diñîculty in subsequent separation. Actual tests have
shown that with a through-put of approximately 10,000
longitudinal pipe having outlet openings 28 spaced along
bbls. per day, a residence time in the mixer of from 3 to
6 minutes is satisfactory. With such assumed through
put sulfuric acid having a strength lying between the
tion header 27 which is shown as constructed of a
its length. Thus, the acid-hydrocarbon stream is evenly
distributed by the header 2'7 throughout the length of
the vessel 16 and an upward flow of the mixture within
the vessel occurs.
limits o-f 85 to 98% titratable acidity is introduced to the
The hydrocarbon outlet conductor 17 extends from
mixture in a volume which depends upon the concentra
the upper end of the vessel andV between this outlet and
tion of contaminants in the hydrocarbon. Such volume
may v_ary from 2 pounds of acid per barrel of hydrocar 10 the inlet the electrode system, which forms the electrical
treating Zone, is mounted. As will be explained, the
bon stream to 25 pounds of acid per barrel.
The hydrocarbon stream containing -the acid dispersion
position of the electrode system is predetermined with
respect to the inlet header 27 so as to control the size
is conducted from the mixer through a line 15 into the
of the settling zone therebelow; by controlling the size
lower end of the vessel 16 of an electrical precipitator A.
During its passage from thepmixe'r some re-action of the 15 or area of the settling zone the residence time of the
mixture within the zone and within the electrical treatsulfur components and the acid will occur, and such re
ing zone is controlled. The electrode system comprises
action products will enter into solution with the acid.
a plurality of live electrodes 29 which are grid-like in
Continued rek-action takes place within the lower portion,
structure and which are suspended through electrical
which may be termed a settling zone, of the vessel 16.
As will be explained, the dispersion is conducted upward 20 conducting rods 30 from an electrode bar 31 located in
the upper portion of the vessel. The electrodes are sup
ly through the vessel and passes through an electrical
plied with direct current by means of electrical power
treating zone, wherein it isV subjected to suiiîcient elec
unit P which receives its supply from `a three-phase A.C.
trostatic mixing to enhance contact between the acid and
power source. Between the live grid-like electrodes 29
sulfur components and thereby insure completion of the
oxidation reaction of the sulfur components in the hy 25 are longitudinally extending ground electrodes 32 which
are `also grid-like in structure; below the lowermost live
drocarbon to the disulfide form, whereby the reaction
electrode 29 is a grid-like ground electrode 33. Thus, a
products may move into the acid phase. Not only does
D.C. lelectrical field zone is created within the vessel and
the electrical treating zone kfunction to insure comple
such zone extends substantially throughout the upper
tion of the oxidation reaction, but it also accomplishes a
rapid coalescence of the acid droplets to effect a rapid 30 portion of the vessel. Suitable baffles 34 (FIG. 2) and
3S (FIG. 3) are mounted within the vessel adjacent the
separation of the acid from the hydrocarbon. The pre
sides and ends of the lowermost electrode 33 and func
cipitator A may be referred to -as the “reaction stage”
and within this stage the sulfur is substantially removed
«from the stream. The stream is vdischarged from the
upper'end of the vessel 16 through an outlet conductor 17.
The acid having the reacted disulfides in solution there
tion to direct the ilow of liquid upwardly through the
electrical iield zone formed between the electrodes.
The particular spacing of the electrodes has been found
of importance in carrying out the present method and
actual practice has shown that the spacing between the
with is coalesced within the vessel V16 and precipitates
electrodes may vary between 6 and l2 inches; a normal
downwardly to be collected in the bottom of the vessel,
spacing of approximately 8 inches between electrodes has
being discharged therefrom through a conductor 1‘3. lf
a recirculation of the acid, which may be said to be only 40 been found satisfactory. Satisfactory results are obtain
able with electrode potentials of between 1900 and 2500
partially spent, is desired, the ilow is through line 18 and
volts per inch of electrode spacing and actual tests have
then through `a recycling line 18a which extends to an
indicated that potentials outside of these limits are un
acid supply vessel 19, such vessel also having connection
with a fresh `acid supply line 20. From vessel 19 the
acid is circulated by means of a pump 21 to the line 14
which extends to the mixer and which has a suitable flow
controller 22 connected therein whereby the volume of
acid which is conducted to the mixer is controlled.
satisfactory for the purpose.
The use of a three-phase
system is of importance to the invention because >with the
three-phase system the deviation of the maximum voltage
from >the average voltage, generally known as the ripple
factor, ris reduced so as to effect a reduction in pulsation.
A predetermined liquid level is maintained, in the vessel
For example, a single-phase system pulses constantly with
tially spent and containing the re-_acted disulfides is re
_coalescence of the acid droplets. Electrostatic mixing
the ripple factor being approximately 52%; with the
16 of the precipitator by means of a float 23, controller
three-phase system the ripple factor is reduced to 4%.
24 and outlet valve 2S, the latter being mounted in an
Although the exact action which takes place in the
acid outlet line 26 extending from the discharge 18. When
electrical precipitator is not fully understood, it is be
valve 25 is opened by reason of the float rising above the
lieved that the electrical treating zone performs a dual
pre-set level, the acid is removed from vessel 16 through
outlet line 26; the reaction products are, of course, re 55 function; first, it subjects the mixture to “electrostatic
mixing” which insures completion of the oxidation reac
moved along with the acid. So long as the level is below
tion of the sulfur components, and second, it effects rapid
that for which the controller is set, the acid which is par
may be defined as the employment of the electrical energy
circulated by means of conductor 18 and re-cycling line
60 to accelerate the motion of an electrically conductive par
18a.
ticle or ion within the body of a non-conductive medium.
Although the re-circulation of acid has been found sat
The conductive particle which is the sulfuric acid is re
isfactory, it is not essential since good results can be
_duced by this mechanical mixing to a very small particle
obtained with a once-through circulation of the acid
size’with a correspondingly large increase in surface area
through the system. In such case, the re-cycling line 18a
between the discharge conductor 18 and vessel 19 would 65 which greatly enhances the contact between the sulfuric
acid and the lsulfur components. 'Ihe predetermined
be eliminated and fresh acid would be furnished to the
electrical potential is applied to the properly spaced elec
mixer at all times. The spent acid having the reaction
trodes and the electrical energy thus transmitted imparts
products therein would, of course, be removed through
a violent and rapid motion to the dispersed particles. It
outlet 26.
k
.p
Y
The electrical precipitator A which has been found to 70 is believed that within said precipitator the mixture is
subjected to a combination of two forces: First, it is
perform the dual function of electrostatic mixing and
subjected to the dispersive action of the electrical field
coalescence and which effectively carries out the present
'which greatly enhances and encourages the probability of
_process is illustrated in FIGURES 2 and 3. Such precipi
contact between any rgiven molecule of sulfur and any
tator includes the vessel 16 having the line 15 and con
ductor 18 connected in its bottom. Line 15 projects up 75 given molecule of sulfuric acid; second, Yelectrolysis of
3,666,087
5
6
the sulfuric acid molecule increases the speed and ef
ficiency of the reaction. Actual experience with the proc
to sutîicient electrostatic mixing to insure completion of
the oxidation reaction of the sulfur components in the
ess indicates that substantially complete oxidation reac«
`tion of the sulfur components to the disulfide form is
hydrocarbon to the disulfide form, and to subsequently
move such reaction products into the acid phase. At
the same time, the action of the electrical iield continu
accomplished, thereby assuring conversion of the com
ponents into the acid phase.
The electrical field also hastens »and rapidly eñects the
coalescence of the droplets of sulfuric acid containing
reaction products to accomplish rapid settling and ef
ously and rapidly coalesces the acid containing the reac
tion products and said acid is collected in the bottom of
the vessel 16 from which it is discharged through the
conductor 18. If the partially spent acid containing the
ficient separation of the hydrocarbon on the one hand 10 reaction products is to be recirculated, it is conducted
and the acid-reaction product on the other.
through re-cycling line 18a to the vessel 19. If, however,
In addition to the proper spacing of the electrodes and
a once-through passage of acid through the vessel is
the electrode potentials in the electrode system, the total
being carried out, the spent acid containing the reacted
residence or contact time of the mixture being treated is
disultides is withdrawn through outlet 26. The hydro
carefully controlled throughout the entire process to pre 15 carbon stream leaving the vessel 16 which forms Ythe reac
Ivent the formation of undesirable reaction products, such
tion stage is conducted therefrom Vthrough the outlet
as esters and sulfones. As has been noted, the contact
conductor 17.
time in the mechanical mixer is in the range of 3 to 6
Actual experience with the process has indicated that
minutes whereby a reduction of acid particle size to a
the sulfur content of catalytic reformer feed stock has
previously determined optimum diameter is accomplished. 20 been reduced to the point of eliminating corrosion or
The residence time of the acid-hydrocarbon mixture with
other difliculties in the reformer units through which the
in the vessel 16 may vary between the limits of 20 to 40
stream is subsequently conducted. As an example, actual
minutes in accordance with the particular size and me
tests were made on a Mid-Continent naphtha under exact
`chanical design of said Vessel. The effective residence
ly identical conditions, except that in one case the acid
time of the mixture within the settling zone which iS 25 naphtha mixture was passed through the reaction stage
formed below the bottom live electrode 29 is preferably
vessel 16, and in the other case it was not. Without the
about 40% of the total residence time of the mixture
electrical treatment as above described, the sulfur was
within the vessel. The contact time is controlled by
»reduced from about 400 parts per million in the feed to
controlling the flow rate of the main hydrocarbon stream
about 150 parts per million in the product. With the
which is introduced through the inlet conductor and also 30 application of electrical treatment as above described, the
by properly locating the electrode System within said
vessel in relationship to the settling zone. In this man
ner the mixture is retained in the settling zone and in the
electrical treating zone for the predetermined time which
has been found most satisfactory to accomplish the im 35
proved results.
The operating temperature of- the vessel 16 may vary
from 40° F. to approximately 150° F. Below 40° F. the
reaction does not proceed with the desirable speed, and
above 150° F. the sulfuric acid will begin to react with 40
other compounds in the stream to produce undesirable
reaction products. As to operating pressure, the mini«
mum operating pressure is that which would be required
to maintain the hydrocarbon phase as a liquid; there is
sulfur in this same feed stock was reduced in the product
to approximately 25 parts per million. It is believed that
the improved results may be best explained by j the
phenomena of electrolysis. However, electrolysis is con
ventionally employed with very high current and` low volt
age, but the present apparatus has reversed this and
employs very high voltage and very low current. The
reduction of ripple factor by reason of the three-phase
system is believed to be important because the reduction
in pulsation provides for a steady state for the electrolysis
to occur.
It has also been found that the total residence, or con
tact time, of the mixture in its passage through the
vessel is of importance. By properly controlling the rate
no upper limit on the operating pressure except that 45 of flow the mixture may be retained within a vessel a
which might be imposed by economical design of the
vessel and associated equipment.
The process has been found extremely satisfactory
when applied to a feed stock stream which is generally
predetermined length of time to permit the efficient separa
tion of the sulfur components from the hydrocarbon
stream.
It is ordinarily desirable to treat the product from the
characterized as napthas, having ASTM boiling ranges
50 reaction stage with a caustic to neutralize the carry-over
of approximately 150° F. to 450° F. The sulfur content
may vary from 25 to 1500 ppm. As heretofore men
products and naturally occurring acids which may be
of sulfuric acid, and also to neutralize the acidic reaction
tioned, a treating agent which has been found satisfactory
present in the feed stock. For this purpose, the hydro
is sulfuric acid having an optimum strength lying be
carbon product from the reaction stage is conducted
tween the limits of 85 to 98% titratable acidity, and the 55 through the outlet conductor 17 and to the lower end of
rate of acid addition varies with the nature and concen
an electrical precipitator B. A suitable caustic, such as
tration of contaminants in the hydrocarbon. The par
mild sodium hydroxide, is introduced through an inlet
ticular process and its manner of functioning is believed
line 36a to a supply vessel 37. From this vessel a pump
evident from the foregoing. The sulfuric acid is intimate
36 directs the caustic through line 38 into the outlet con
ly and vigorously mixed with the hydrocarbon stream in 60 ductor 17, the connection being made in advance of a
the mixer 12, and mixing is controlled to reduce the par
mixer 39. A suitable ñow controller 40a controls the
ticle size of the acid to the point Where maximum surface
volume of caustic being introduced through line 38.
area is presented for contact with the sulfur components.
Mixer 39 thoroughly admixes the caustic with the stream
Oxidation reaction of the sulfur componentsto the di
under treatment and the mixture is conducted into the
sulfide form begins in the mixer and continues as the 65 precipitator B.
stream is distributed longitudinally within the Vlower por
Within the precipitator the admixed stream and caustic
tion of the vessel 16 by the header 27. The mixture is
are subjected to a direct current electrical field whereby a
retained in the settling zone formed by the area between
neutralizing action is carried out. The precipitate from
the headers and the lowermost live electrode 29 to per
the precipitator B may be re-circulated through line 40,
mit the oxidation to proceed and to convert the reaction 70 or may be discharged through line 41. It is pointed out
product to the acid phase; also some precipitation of
that the electrical precipitator B may be of any standard
the acid-reaction product occurs in the settling zone.
construction, and this step of the process may be referred
The mixture then flows upwardly and is subjected to
to as the “neutralization stage.”
the action of the direct current electrical field in the elec
The neutralized hydrocarbon may thereafter be “Water
trical treatment zone wherein the dispersion is subjected 75 washed” to remove any carry over of caustic and in such
3,066,087
8
instance is conducted from the neutralization stage
precipitator B through line 42 which has connection with
the lower end of a third electrical precipitator C. Water
is introduced through inlet line 43 and is pumped by
means of pump 44 through a line 45 which connects with
the outlet conductor 42 extending from the neutralization
stage. Flow controller 46 controls the volume of water
so introduced and the water is mixed by means of a suit
able mixer 47 with the neutralized hydrocarbon stream.
Within the precipitator C the water is electrically
I claim:
1. A process of treating a hydrocarbon stream con
taining sulfur components which comprises intimately and
vigorously admixing with such hydrocarbon stream sul
furic acid having a strength of between 85 and 98% ti
tratable acidity in proportions of 2 to 25 pounds of said
acid per barrel of hydrocarbon for a period of 3 to 6
minutes, conducting the acid-hydrocarbon mixture into a
settling zone, allowing said mixture to remain in said
settling zone for a period of time sufficient to bring about
the formation of sulfur-containing reaction products which
dissolve in the acid, passing the mixture through an elec
trical field zone wherein the electrical field is generated
water is removed through outlet line 49.
by la direct current of approximately 1900 to 2500 volts
In some instances it may not be necessary to include
the neutralization stage and water wash, although in most 15 per inch of electrode spacing with the electrode spacing
being between 6 and 12 inches, while maintaining a tem
instances it is desirable to neutralize the product from the
perature in the settling and electrical ñeld zones within the
reaction stage. Actual experience with the process has
range of 40 and 150° F. and a combined residence time
indicated that the sulfur content of the catalytic reformer
of the acid-hydrocarbon mixture within the settling and
feed stock can be readily reduced to the point of eliminat
ing corrosion or other difficulties in the reformer units 20 electrical field zones between 20 and 40 minutes, remov
ing acid from the settling zone, and removing a desul
through which the stream is subsequently conducted. As
coalesced and the ñnal de-sulfurized product is conducted
from precipitator C through outlet line 48. The separated
mentioned above, although the 'invention is particularly
adapted to products of distillation, it is suitable for the
furized hydrocarbon stream from the electrical iield zone.
2. A process as claimed in claim 1 in which the resi
dence time of the mixture in the settling zone is approxi
treatment of any hydrocarbon stream in which the reduc
tion of sulfur content is desirable. By means of the 25 mately 40% of the combined residence time of the acid
hydrocarbon mixture in the settling and electrical field
present process, a "simple type electrical treater in which
zones.
the electrodes are properly spaced and the electrode po
tentials controlled may be employed. As noted, the inti
mate mixing of the acid with the hydrocarbon, together
with the reaction time or residence time of the mixture 30
within the reaction stage,lis of importance.
The foregoing disclosure and description of the inven
tion is illustrative and explanatory thereof and various
changes in the size, shape and materials, as well as in the
details of the illustrated construction, may be made within '
the scope of the appended claims without departing from
the spirit of the invention.
References Cited in the file of this patent
UNITED STATES PATENTS
2,101,168
2,382,697
2,412,791
2,721,833
2,855,357
2,974,095
Deutsch ______________ __ Dec. 7,
Deutsch _____________ __ Aug. 14,
Waterman ____________ __ Dec. 17,
Defoe et al ____________ __ Oct. 25,
Stanzel _______________ __ Oct. 7,
Gordon _______________ __ Mar. 7,
1937
1945
1946
1955
1958
1961
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