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March 11, 1947.
J, D. CovlNGTQN
2,417,351
HYDROFLUORIG ACID RESISTANT PACKING MATERIAL
Filed July 7, 1944
[email protected]
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l2,417,351
Patented Mar. 11, 1947
UNITED STATES PATENT OFFICE
2,417,351
HYDROFLUORIC ACID RESISTANT
PACKING MATERIAL
James D. Covington, Dallas, Tex., assignor, by
mesne assignments, to Socony-Vacuum Oil
Company, Incorporated, New York, N. Y.,> a
corporation of New York
Application July 7, 1944, Serial No. 543,855
2 Claims. (Cl. 252-29)
l
This invention relates to packing materials, and
particularly to packing materials employed in
the control units of systems or processes utilizing
hydroñuoric acid, particularly to processes for the
condensation of hydrocarbons, such as the alkyla
tion 0f isoparaffins with oleñns, the polymeriza
tion of oleñns, the alkylation of aromatic hydro
carbons with olefins and the like.
~A typical application of my invention is its use
2
are packed with a packing material comprising
talc instead of the conventional packing materials
the operating period during which no leakage
will occur in such units is greatly increased.
In order that a full understanding of the in
vention and the advantages to be derived from
its use may be had, reference is made to the ac
_ companying drawing which is a iiow diagram of
a conventional process for producing alkylated
in a commercial alkylation process, 'such as the 10 hydrocarbons from isobutanes and butenes utiliz
'ing hydrogen fluoride as a catalyst.
alkylation of isoparaflins such as isobutane with
In the drawing there is shown a reaction cir
oleiins such as the butenes. The invention will be
cuit I into which butene feed stock is admitted
illustrated as applied to an alkylation process of
through line 2 ñ-tted with valve 3. isobutane
this type. It is to be understood, however, that
the principles of my invention are applicable to 15 feed stock is fed to the reaction circuit through
line 4 fitted with valve 5. Essentially anhydrous
any process or system wherein essentially an
hydroñuoric acid catalyst is delivered to the re
hydrous hydrogen iiuoride is utilized as a catalyst
action circuit through line 6 provided with valve
or other treating agent and/or wherein control of
‘I by way of line 8. A circulating pump II) cir-`
the flow of this acid or its agitation are required.
culates the reactants and the hydrofluoric acid
Hydroñuoric acid exerts a strong corrosive ac
continuously around the reaction circuit. A
tion on many 0f the materials normally used in
cooler II is provided in order to maintain the
the construction of reiinery equipment. Also, the
reactants at the desired reaction temperature.
acid is highly toxic and is therefore a potentially
The reactants may be by-passed through the
hazardous chemical. For these reasons the use
of hydroñuoric acid asl an alkylation catalyst has 25 cooler II in any desired proportion by means of
ñow regulation valve I2. Material is continuously
introduced new problems in design, construction
withdrawn from the circulating mixture through
and operation of refinery equipment.
line I3 provided with valve I4 to separator I5
A particularly troublesome problem en
where gravity separation of hydrofluoric acid
countered in HF alkylation plants has been the
frequent occurrence of leaks in circulating pumps 30 from reacted and unreacted hydrocarbons occurs,
forming an acid phase and a hydrocarbon phase.
and control valves and the like through which
The heavier acid phase settles to the bottom of
hydrofluoric acid, or mixtures of >hydrofluoric acid
the separator I5 and is withdrawn through line 8
and hydrocarbonsare conducted in the process.
provided with valve I6 and recycled to reaction
These leaks are caused mainly by deterioration
of the packing used in these units due to the 35 circuit I by means of a pump 20. The hydrocar
action of the hydroiiuoric acid, although infre
quently, corrosion of the metal parts of such units,
bon phase is withdrawn from the top of separator
I5 through line 2|' provided with valve 22 and
passed to fractionating column 23 provided with
reboiler 2li.v Small amounts of hydroñuoric acid
after prolonged exposure to the acid, is a con
tributing factor. These leaks are not only
troublesome from an operational standpoint but 40 carried over in the eiliuent stream from the sep
arator I5 may be removed from the process at
they constitute a serious hazard to personnel be
this point by treatment in a suitable alkaline
cause of the high toxicity of the acid.
absorber or by means of a hydroiiuoric acid
It is an object of my invention to provide a
stripper (not shown). Liquid alkylate product is
novel compacted packing and lubricating ma
withdrawn from the bottom of fractionator 23
terial for use in flow control units, such as pumps,
through line 25 fitted with valve 26 while the
valves and the like which are employed in systems
lighter components of the reacted mixture, com
carrying hydrofluoric acid, said packing material
prising unreacted isobutane with small amounts
being highly resistant to the action of hydro
of n-butane and lighter gases such as propane,
ñuoric acid. whereby the occurrence of costly and
hazardous leaks, due to packing failure in such 50 ethane, etc., formed in the reaction circuit are
taken oñî overhead in line 21. In line 21 the
control units is substantially minimized.
isobutane and normal butane-containing frac
I have discovered that when units such as
tion is conducted to fractionator 28 in which the
pumps and valves, which handle hydroiiuoric acid
isobutane is separated and recycled to reaction
or mixtures containing hydroñuoric acid such
as in the alkylation of isobutane with butenes, 55 circuit I by way of line 29 provided with com
2,417,851
presser 30, cooler 3| and valve 32. Normal butane
is withdrawn from fractionator 28 in line 33
fitted with valve 34, while the gases lighter than
isobutane are vented through line 35.
By the terms "hydroñuo‘ric acid” and “essen-.
tially anhydrous hydrogen ñuoride" as used
throughout this speciñcation and in the appended
claims I refer to hydrogen ñuoride diluted with
.
In the operation of the hydrofluoric acid'alky
or containing not more than 10% of water.
Having now fully described my invention what
I claim as new and wish to be secured- by Letters
lation process just described trouble has been en
countered due to the frequent occurrence of `leaks
in the hydrofluoric acid recycle stream pump 20
Patent is:
-
and in the circulating pump i0. Leaks were also
1. As a new article of manufacture, a com
encountered, though they were less frequent, in 10 pacted packing and lubricating mass consisting
control valves 1, I4' and I6. All of these leaks
of an intimate mixture of talc and ilake graphite,
were the result of deterioration of the conven-`
said mass characterized by being highly resistant
tional packing used in these units. The life of
the packing material in the circulating pumps
to the action of hydrogen ñuoride and the talc
being present in an amount from about "I5k to
under conditions of continuous operation was 15 about 90 per cent of the total weight of the
only a few hours on the average and rarely ex
mixture.
ceeded a day after which time leakage occurred
2. As a new article of manufacture a com
and repacking was necessary. However, when in
pacted packing and lubricating mass character
accordance with my invention a packing compo
ized by being highly resistant to the action of
_ sition comprising talcumpowder was employed 20 hydrogen fluoride consisting of an intimate mix
in these umts leakage was prevented for periods'
ture of talc and flake graphite in which the talc
as long as from 3 to 5 weeks. under conditions of
comprises from 50 to about,90% by weight of the
continuous operation. This represents about a
mixture.
.
thirtyfold increase in the length of the packing
JAMES D.- COVINGTON.
life. The fact that talc is so eiïective for this 25
purpose is surprising since it is essentially a
REFERENCESy CITED
silicious material (MgO.4SiO2.H2O) and there-`
The following references are of record in the
fore would be expected to be attacked readily by
ñle of this patent:
hydrofluoric acid. Whether a reaction does oc
UNITED' sTATEs PATENTS
cur between the talc and the hydrogen ñuoride to
produce a substance which affords the talc its
Number
eñ’ectiveness as a packing in the presence of
hydrogen fluoride is not known to me, the evident
fact being. that'it is so eiïective.
_
In order to reduce friction and añ'ord a lubri
cating quality to the talc, I generally mix the
talc with ilake graphite. I have found that best
results are obtained by using a mi-xture of talc and
Number
percent by weight of graphite although mixtures '
containing as high as 50 percent may be em
invention is equally applicable to other hydro
fluoric acid processes or to systems carrying
hydroñuoric acid or mixtures thereof in which
circulating pumps, agitators and stirrers having
packed shafts, bearings, etc., are exposed to
hydrogen fluoride.
'
Country~
325,566
ployed.
Though I have described and illustrated my in-`
vention in connection‘with an alkylation process,
it should be understood that the principle of the
Date
Benjamin ________ .__ Mar.- 14,
Calts _____________ __ Dec. 28,
Frey _____________ __ June 29,
Jones ____________ „_ Nov. »28,
Matuszak _________ __ Sept. 5,
1922
1920
1943
1944
1944
FOREIGN PATENTS
graphite containing from about 10 to about 25l
_
Name
1,409,276
1,363,563
2,322,800
2,363,597
2,357,753
_
Date
British ___________ __ Feb. 14, 1930
OTHER REFERENCES
National Pet. News, Tech. Soc., June 2, 1943,
pp. 11243-244. (Patent Office Library.)
National Pet. News, Tech. Soc., Mar. 1, 1944,
Vpp. R-146, R-148, R-150, R-151, Elf-1.54, R455.
Chem. Abs., v01. 26, page 446.1, Aug. 2o, 1932,
252-29.
(Copy in Div. 64.)
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