Note: Descriptions are shown in the official language in which they were submitted.
1 32~468
C-10065
HYPOCHL~R~US AC~ REAC~OR
This invention relates generally to a reactor
vessel and more specifically to a reactor vessel for
the production of hypohalogenated acid by the mixing
and reaction therein of an alkali metal hydro~ide and a
gaseous halogen. ~ preferred product acid is
i hypochlorous acid.
HypoGhlorous acid is used extensively in the
preparation of chlorohydrin and chloramines.
Chloroisocyanurates ar~ typical examples. Hypochlorous
acid has been produced by several processes or
techniques. The use of dilute hypochlorous acid and
large quantities of halogen to produce hypohalites,
' 15 such as sodium hypochlorite, is recent.
One technique employs the process in which
chlorine, steam and air are bubbled through an aqueous
solution of an alkali earth metal hypochlorite, such as
calcium hypochlorite, to remove the resulting
hypochlorous acid in vapor form. The hypochlorous acid
is then co~densed and stored for use. This process,
however, produces a large volume of undesirable
, by-product, calcium chloride.
Another process uses a low concentration of
aqueous caustic solution to scrub chlorine gas.
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However, the solution has an available chlorine content
of about only 5% and, because of the chloride ion
content, the hypochlorous acid that is formed quickly
decomposes, most preferably to chloric acid.
Another related process prepares a solid
mi~ture of alkali metal hypochlorite and alkali metal
chloride by reacting chlorine gas with a spray of
alkali metal hydro~ide, while drying with a g~s the
reactants and product. Some cooling of the reacting
chemicals and the drying gas may be done. The primary
products of this process have very limited utility.
A more recent process, which produces
~ypochlorous acid vapor, sprays aqueous alkali metal
hydroxide in droplet form or solid alkali metal -
lS hydro~ide particles into gaseous chlorine. This
approach attempts to utilize droplet sizes to attain
the maximum surface to volume ratio possible. Droplets
having an average diameter of less than about 1000
microns are employed.
These previous processes, and the apparatus
employed to produce these processes, have suffered from
not achieving substantially complete reactions between
the chlorine and the alkali metal hydroxide. A
critical factor in determining the complete r~action is
the droplet size of the alkali metal hydro~ide. It is
also desirable that any hypochlorous acid produced and
any water present be readily vaporizable. The salt
particles produced as by-products in any process should
be dry to facilitate handling. The salt particles
should be sized so that they readily separate from the
gaseous product mi~ture of hypochlorous acid. Prior
3 1 32q46~
processes have produced oversized alkali metal
hydro~ide droplets that result in the undesired
reaction of hypochlorous acid and the oversized
particles to produce significant alkali metal
chlorates. These oversized particles then retain
excessîve moisture so that caking results and the caked
mass adheres to the reactor surfaces. The presence of
such alkali metal chlorates reflect reduced yields of
the desired hypochlorous acid, while increasing the raw
material and op~rating costs.
These problems are solved in the design of the
present invention wherein a reactor vessel for the
production of hy~ohalogenated acid is provided ~n.~ich
the mi~ing and reaction of alkali metal hydro~ide and a
gaseous halogen occurs.
It is an object of the present invention to
provide a reactor vessel within which a gas phase
controlled reaction can occur to produce a
hypohalogenated acid.
It is another object of the present invention
to provide a reactor vessel in which both a liquid-gas
reaction and drying occur to produce a gaseous product
and a .solid by-product.
It is a feature of the present in~ention that
an atomizer is employed to produce small droplets of an
alkali metal hydro~ide to ensure that the undesirable
secondary reactions are minimized and that proper
drying of the desired particles occurs.
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It is another feature of the present invention
that the reactor vessel permits the rapidly sequential
events of absorption of gaseous halogen into the
atomized particles of alkali metal hydroxide and water
` 5 evaporation to occur.
It is still another feature of the present
invention that the atomizer is located near the top of
the reactor vessel.
It is yet another feature of the present
~', 10 invention that heated halogen gas mi~ture is fed into
the top of the reactor vessel.
It is an advantage of the present invention
that the production of oversized alkali metal hydroxide
droplets are avoided and that undesirable sscondary
reactions are minimized.
It is another advantage of the present
invention that manufacturing costs are substantially
reduced.
These and other objects, features and
advantages are provided in a reactor vessel for the
production of hypohalogenated acid from the mixing and
`~ reaction of an alkali metal hydroxide and a gaseous
halogen in the reactor vessel, which is elongate and
generally vertically positioned and the atomizer for
atomizing the alkali metal hydro~ide is mounted within
the reactor vessel above the spraying and reaction zone
and the drying zone.
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In accordance with the present invention, there
is thus provided a reactor for the production of hypo-
halogenated acid from the mixing and reaction of an alkali
metal hydroxide and a gaseous halogen, comprising in com
bination:
a. an elongated, generally vertically
extending reactor vessel having a top and an opposing
bottom, and a central axis therebetweeni
b. gas inlet means in the top of the reactor
vessel;
c. flow directing means beneath the gas inlet
connected to and inside the vessel effective to direct
the gaseous halogen from the top to the opposing bottom;
d. infeed means mounted to the reactor vessel
for feeding alkali metal hydroxide droplets in a spray
into the vessel;
e. an alkali metal hydroxide feed line
, connected to the infeed means in the reactor vessel
i from a supply of alkali metal hydroxide;
f. a spraying and reaction zone beneath the
3 infeed means into which the alkali metal hydroxide is
sprayed and reacts with the gaseous halogen to form
reaction products including hypohalogenated acid;
g. a drying zone beneath the spraying and
reaction 20ne to dry the reaction products; and
h. outlet means below the drying zone and
above the bottom for outletting gaseous halogen and
product from the reactor vessel.
The present invention also provides, in
another aspect thereof, a reactor for the production of a
solid by-product and a gaseous product from the reaction
of a gas and a liquid, comprising in combination:
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a. an elongated, generally vertically
extending reactor vessel having a top and an opposing
bottom, and a central axis therebetween;
b. gas inlet means in the top of the reactor
vessel to feed in a reactant gas;
c. flow directing means beneath the gas inlet
connected to and inside the reactor vessel e fective to
direct the reactant gas from the top to the opposing
bottom;
d. a liquid feed line connected to the
reactor vessel beneath the flow directing means;
e. infeed means mounted to the reactor vessel
and connected to the liquid feed line for spraying the
liquid;
-~ 15 f. a spraying and reaction zone beneath the
infeed means into which the liquid is sprayed and in
~ which the liquid reacts with the reactant gas to form
j the gaseous product and the solid by-product;
g. a drying zone beneath the spraying and
reaction zone to dry the solid by-product;
h. outlet means below the drying zone for
outletting the dried solid by-product from the reactor
vessel; and
i. a generally horizontally extending gaseous
product outlet in the drying zone and above ~he
opposing bottom to outlet product gas from the reactor
and recycle any unreacted reactan~ gas.
~ eatures and advantages of this invention will
become apparent upon consideration of the following detailed
disclosure of the invention, especially when it is
taken in conjunction with the drawings wherein:
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FIGURE 1 is a side elevational view of the
reactor vessel; and
FIGURE 2 is a bottom perspective view of the
ellipsoid inlet for the e~haust duct.
FIGURE l shows the reactor, indicated
generally by the numeral 10, which reacts the liquid
alkali metal hydro~ide, such as caustic, supplied by
feed line 11 with the gaseous halogen, such as
chlorine, to produce the solid salt crystals and the
gaseous product, such as HOCl. Although the reactor
will be discussed in terms of producing hypochlorous
acid, it is to be understood that any halogen could be
employed to produce hypohalogenated acid, for example,
hypobromous or hypofluorous acid. The HOCl is
condensed to produce liquid hypochlorous acid which,
~' for e~ample, can be mixed with a lime slurry to produce
calcium hypochlorite. Gaseous chlorine, along with
some chlorine mono~ide in the recycle system, is fed
into reactor 10 via gas infeed 12 in the top 14. Top
14 is in the shape of an inverted funnel, that can be
constructed of a suitable corrosion resistant material,
such as titanium: coated titanium; an alloy of nickel,
chrome, molybdenum, iron and other materials; tantalum;
and lined carbon steel or lined fiberglass reinforced
plastic. The lining can be a suitable polyfluoro-
' polymer.
Reactor vessel 15 has a perforated plate 16 atthe top between the reactor top 14 and the vessel 15.
The plate 16 is also made of a suitable corrosion
resistant material, such as polytetrafluoroethylene or
one oL the above mentioned materials with respect to
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; top 14, and serves to create a straight cocurrent flow
path for the chlorine gas flowing down from the top
14. Ethylene chlorotrifluoroethylene has also been
used as a construction material for reactor vessel 15.
Vessel lS, similarly can be made from any suitable
corrosion resistant material, such as carbon steel with
a liner or coating of a suitable perfluoropolymer, such
as that sold under the tradename TEPLON(R) PFA.
1 Reactor vessel 15 has a generally elongate
3 10 cylindrical central section 18 which tapers to a
3 conically shaped funnel bottom 19 to permit solid
alkali metal halide salt, such as NaCl, product to
''f discharge out through a standpipe, not shown, for
further processing. ~essel 15 has a caustic feed line
15 11 that enters through its side and provides the
¦ caustic to an atomizer nozzle 21. Nozzle 21 is mounted
along the center line 22 of the vessel lS about six
(06) inches below the top of vessel lS. Nozzle 21
creates caustic droplets of a desired size between
about 50 to 200 microns which are of sufficient size to
absorb virtually all of the gaseous chlorine feed while
the chlorine and caustic react fast to produce the
gaseous and solid products as shown in the equation: -
NaOH t C12 ~ HOCl I NaCl
i~ 25 The reac~ion occurs at a pH of about 4 to
about 6 with a stochiometric ratio of about 30 to 1
chlorine to caustic. The gaseous HOCl is condensed
between about 0 to about 10C after exiting the
¦ reactor to recover a concentrated HOCl solution.
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Recycled gases, such as chlorine and chlorine
monoxide, are exhausted from the vessel 15 through
exhaust duct 24 and are fed back into reactor 10 via a
recirculation loop, after passing through a heat
e~changer (not shown) to achieve the necessary heat,
when combined with the heat of reaction to evaporate
the hypohalogenated acid, such as hypochlorous acid,
and water phase to leave a dry sodium chloride or salt
solid by-product. The desired reaction temperature
10 ranges from about 30 to about 100 centigrade.
The recycled gases are also used i~s reactant gases in
the production of the hypohalogenated acid.
The recycled gases, for example chlorine and
; chlorine monoxide, enter the reactor vessel top 15 and
disperse outwardly in the inverted funnel top 14 and
pass through the flow directing means or perforated
plate 16 to enter the reactor vessel 15 in a generally
vertical flow orientation. Fresh halogen gas, for
example chlorine, is fed in through chlorine feed line
20 through the reactor top 14 and is directed down over
j the nozzle or atomizer 21.
~ ~ozzle 21 may be a single fluid atomizer, a
;~ two fluid nozzle or a wheel atomizer dependent upon the
viscosity and density of the alkali metal hydro~ide
being atomized and the amount of pressure to which the
liquid is subjected. The materials of construction of
the nozzle must be capable of withstanding the
~ harshness of the environment within the reactor.
j The vessel 15 has an outlet or e~haust duct 24
at the bottom of the drying zone 26 just above the
funnel or conica1ly ~haped bottom 19 to remove the
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product gas, the unreacted halogen gas and some
by-product into the recirculation loop as previously
described. Outlet or e~haust duct 24 exits through the
side of vessel 15 generally horizontally and has an
inlet 28 that is undercut such that the top overhangs
or overlies and covers the bottom to preclude solid
alkali metal chloride by-product, for e~ample sodium
chloride, from falling directly into it. The preferred
`r' shape of the inlet 28 is an undercut ellipsoid, as seen
s 10 in FIGURE 2.
The vessel 15 has its central section 18
`' preferably cylindrically shaped, but it could also be
~ polygonal, as appropriate. The cylindrical design has
dl a desired diameter and length. The length e~tends from
15 the top at the perforated plate 16 to the bottom of the
drying zone 26, just above the funnel bottom 19. The
dimensions of the len~th and the diameter can be
selected so that the length to diameter ratio, l/d, can
range from about 1 to 1 to about 1 to 5.
In operation the halogen gas, for e~ample
chlorine, is fed into the reactor 10 through feed line
20 and is directed generally vertically downward over
nozzle 21. Recycled gases are fed in from the
recirculation system via gas infeed 12 into the reactor
top 14 and are directionalized by perforated plate 16
down into reactor vessel 15. Vessel 15 has an elongate
cylindrical section 18 which has a spraying and drying
zone 25 adjacent the top surrounding nozzle 21 and a
drying zone 26 therebelow.
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The reacted gases e~it the reactor 10 through
outlet or e~haust duct 29 for processing and
recirculation, as appropriate. The solid by-product
alkali metal halide, such as sodium chloride, exits the
vessel 15 through the conically shaped funnel bottom 19
for processing. Bottom 19 is connected by conventional
flanging to connecting pipes ~not shown).
The solid by-product alkali metal halogen is
dried as it passes down through the drying zone 26.
The overhanging top portion of e~haust duct 24 prevents
substantial quantities of the solid by-product from
being drawn out through the undercut ellip60id inlet 28
with the product HOCl gas and the recycle gases.
While the preferred structure in which the
principles of the pre~ent invention have been
incorporated is shown and described above, it is to be
I understood that the invention is not to be limited to
; the particular details thus presented, but, in fact,
widely different means may be employed in the practice
of the broader aspects of this invention. The scope of
the appended claims is intended to encompass all
I obviouæ changes in the details, materials, and
; arrangement of parts which will occur to one of skill
in the art upon a reading of the disclosure.
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