Improvements in the Manufacture of Bleaching Powder and in Apparatus to be employed therein.
Year: 1892

page_text: Date of Application, 19th Apr., 1892
Complete Specification Left, 19th Jan., 1893-Accepted, 4th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Bleaching Powder and in
Apparatus to be employed therein.
I, FERDINAND HURTER, Ph. D. of Holly Lodge, Cressington Park Liverpool
in the County of Lancaster, Analytical Chemist, do hereby declare the nature of
my invention to be as follows:-
This invention relates to the manufacture of bleaching powder and consists in
regulating the temperature of the gas employed in the said manufacture as herein-
after described.
Considerable difficulty is experienced in the manufacture of strong bleaching
powder by the Deacon process owing to the temperature in the apparatus being
liable to rise too high in summer and to fall too low in winter.
According to my invention this difficulty is removed by artificially raising or
lowering the temperature of the chlorine gas used in the apparatus so as to cause
it to act at an approximately uniform temperature at all seasons of the year.
With this object the gas is cooled for example by artificially lowering the
temperature of the sulphuric acid used for drying the gas. This cooling of the
sulphuric acid may be effected by means of any suitable refrigerating apparatus or
process. The cold sulphuric acid is brought into intimate contact with the gas by
means of any suitable apparatus or preferably in an apparatus in the form of a
tower, consisting of a lead lined chamber containing fragments of coke or equivalent
material presenting an extended surface. The cold sulphuric acid is allowed to
flow downwards through this chamber whilst the chlorine gas flows through it in
the opposite direction. By these means the gas is dried and at the same time its
temperature is lowered to the required extent.
If the dry gas be not sufficiently cool it may afterwards be passed through a
number of pipes, which are surrounded with refrigerated brine, but these pipes will
become choked with chlorine hydrate if moist chlorine gas be allowed to enter.
In like manner the temperature of the gas is raised when necessary by suitably
regulating the temperature of the sulphuric acid employed in the drying process.
Dated this 19th day of April 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Bleaching Powder and in
Apparatus to be employed therein.
I, FERDINAND HURTER of Widnes in the County of Lancaster, Analytical
Chemist, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement :-
My invention relates to the manufacture of bleaching powder and consists in
regulating the temperature of the gas employed in the said manufacture as herein-
after described.
Considerable difficulty is experienced in the manufacture of strong bleaching
powder by processes such as the Deacon process owing to the temperature in the
apparatus employed in the said manufacture being liable to rise too high in summer
or-bot weather and to fall too low in winter or cold weather.
The chlorine gas produced by what is known as the Deacon process or by other

page_text: similar processes, such as Reychler & De Wilde's, Weldon-Pechiney's, Mond's
and the like, always contains a very large amount of inert gases (but I will refer
to it as the gas), and coming from the wash towers, is fully saturated with moisture.
The absorption of this moisture during the process of drying the gas by means of
a hydroscopic substance, such as sulphuric acid, evolves a large amount of heat and
in consequence of this the gas arrives at the bleaching powder chambers frequently
at a temperature considerably higher than that of the surrounding atmosphere
more particularly during hot weather. During the cold weather on the other
hand.owing to-the-great dilution of the chlorine by inert gases the absorption of
the gas by the lime in the bleaching powder chambers becomes sluggish..
According to my invention these difficulties are removed either by artificially
lowering or by artificially raising the temperature of the chlorine gas used in the
apparatus so as to cause it to act at an approximately uniform temperature at all
seasons of the year or irrespective of the temperature of the surrounding
atmosphere.
With this object when the gas is to be cooled for example in hot weather this
can be effected by artificially lowering the temperature of the sulphuric acid
used for drying the gas before the said gas is allowed to pass into the bleaching
powder chambers. This cooling of the sulphuric acid may be effected by any
suitable refrigerating apparatus or process. The cold sulphuric acid is brought
into intimate contact with the gas by means of any suitable apparatus, or
preferably in an apparatus such as is hereinafter more particularly described
and consisting of a tower forming or containing a lead lined chamber in which
are.fragments of coke or equivalent acid resisting material presenting an extensive
surface, or there may be a number of perforated shelves to retard the flow of
the acid. The cold sulphuric acid is allowed to flow downwards through this
chamber, whilst the gas flows through it in an opposite direction. By these
means the gas is dried and at the same time its temperature is lowered to the
.required extent.
As it is necessary to employ a strong sulphuric acid (usually of a specific
gravity of 140 to 150 degrees on Twaddles hydrometer) its temperature cannot
safely be reduced below 40° F., or the acid may solidify and choke the pipes or
passages through which it should flow. If therefore the gas arrive in the said
chamber at an elevated temperature and saturated with moisture, the con-
densation of the aqueous vapour and its combination with the sulphuric acid-
will produce so much heat, that the gas though it arrives at the top of the said
chamber cooler than it would have been, if the sulphuric acid had not been
refrigerated, yet is too warm to be successfully employed in the manufacture
of strong bleaching powder as the practical limits of cooling of the acid as afore-
said have not allowed its temperature to be lowered to a sufficient degree to cool
the gas to the desirable extent.
.
If therefore the dry gas be not sufficiently cooled by the acid it may afterwards
be passed through a number of pipes or passages which are surrounded with
refrigerated brine or like cooling medium. This passing of the gas through the
said pipes or passages could not be effected until after the gas has been dried
because the said pipes or passages would become choked with chlorine hydrate if
the moist gas were allowed to pass into them.
In like manner the temperature of the gas can be raised when necessary by
causing the sulphuric acid employed to impart heat to the gas in the drying
_process, when, of course the second operation of refrigerating the gas in pipes is
omitted.
The apparatus by which my invention may be carried into practice may be
varied without departing from the nature of my invention but I have illustrated
in the accompanying drawings in, sectional elevation an apparatus well adapted
for the purpose of carrying my invention into effect. I will presume that the gas
is to be cooled. A is a chamber or tower which may be square or of other shape
in plan. It is shewn as being constructed of thick planks or board and lined with

page_text: lead. The planks serve as a support for the lead but they should be sufficiently
thick to prevent as far as possible the convection of heat from the outside atino-
sphere through the lead to the interior of the chamber. The chamber is filled
with coke or broken acid proof earthenware or other equivalent material which
rests on a grating B which may be made of iron bars covered with lead to protect
them against the corrosive action of the sulphuric acid, or it may be constructed
of earthenware tiles or in other suitable way. In the interior of this chamber
above the coke or the like is placed the distributing arrangement for the
refrigerated sulphuric acid. This distributing arrangement may be constructed
in various ways, but as here shewn it consists of a number of troughs C made of
lead or earthenware and provided on both sides with spouts, from which the
refrigerated sulphuric acid flows in small streams on to the coke or the like.
These troughs rest upon supports D which may be iron bars covered with lead
similarly to the bars B.
The sulphuric acid after flowing downwards through the coke or the like leaves
the tower by the syphon pipe E and is then conveyed to a concentrating pan, and
after having been concentrated may be used again. The sulphuric acid is supplied
to the troughs C from the supply cistern H through pipes G provided with valves
or cocks to regulate the flow of the acid. These pipes may pass directly through
the top of the tower as shewn at but in order that the flow of the acid may be
observed it is more convenient to place hydraulic lutes on the tower as shewn
at F..
The sulphuric acid may be refrigerated before arriving at the supply cistern H,
but it is more economical to refrigerate it in the said supply cistern by placing
therein a coil or coils of lead or equivalent pipes through which refrigerated brine
or other cooling medium is caused to flow.
The gas enters the tower A through the inlet pipe K. and is dried and cooled
whilst passing upward through the coke or the like by the downward stream of
cold sulphuric acid. The gas leaves the tower through the pipe L. In case the
gas is not sufficiently cooled by the means described I pass it through a second
refrigerator consisting of a number of pipes through which the gas is passed and
which are surrounded with refrigerated brine, or the gas may surround the pipes
and the refrigerated brine be passed through the pipes which latter is the plan
shewn in the drawing. This apparatus consists of a vessel N which may be a
cylindrical wrought iron vessel lined with lead but this is not absolutely necessary
since dry cold chlorine does not materially act upon the iron. The vessel N is
divided into three compartments by partition plates which may be of iron covered
with lead if desired. The upper compartment M³ communicates with the lower
compartment M₁ by a number of lead or equivalent pipes traversing the middle
compartment M². The pipes are shewn straight but they may be otherwise
arranged for instance as coils (suitably supported) to give increased surface. In
order to secure perfectly tight joints between the pipes and partition plates, the
lead covering of the plates and the ends of the lead pipes are "burnt or soldered
together. If the lower side of the lower partition plate and the upper side of the
upper partition plate be covered with lead the pressure of the liquid will force the
lead lining against and not away from the said plates. Through the pipe P
refrigerated brine or other cooling medium is conveyed or pumped into the com-
partment M, and passes through the pipes in the compartment M' upward into
compartment M³, from whence it may return to the refrigerating machine, or it
may (as is shewn in the drawing) be caused to pass through a coil of pipes m in
the sulphuric acid cistern H and thence to the refrigerating machine.
,,
The dry chlorine gas leaves the vessel A by the pipe L and enters the
compartment M2 of the vessel N and descending among the cold pipes therein is
cooled to the requisite temperature and then passes through the pipe Q to the
bleaching powder chambers.
To prevent the interior of the vessel N being heated by the surrounding
atmosphere it can be covered outside with wood or other non-conducting material.

page_text: All pipes conveying the cooled gas, or refrigerated liquors should also be covered
with non-conducting materials.
Several refrigerators in succession may of course be used if found necessary.
Except in very hot climates or during the hottest weather the refrigerated brine
or artificially cooled medium may be replaced by cold water if a sufficient supply
at a suitable temperature be at disposal. In very cold weather tepid water and
tepid sulphuric acid may be used, the heating being effected by an exchange of
temperature substantially as hereinbefore described with regard to cooling-and-the-
same-apparatus-may-be-used.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In the manufacture of bleaching powder by processes such as are hereinbefore
mentioned, the regulation of the temperature of the chlorine gas, by causing it to
come into contact with sulphuric acid which has been brought to the requisite
temperature substantially as hereinbefore described.
}
2. In the manufacture of bleaching powder by processes such as are hereinbefore
mentioned first drying the chlorine gas and then effecting the regulation of its
temperature substantially as hereinbefore described with reference to the vessel N.
3. In the manufacture of bleaching powder by processes such as are hereinbefore
mentioned the regulation of the temperature of the chlorine gas by the combined
use of sulphuric acid artificially brought to the requisite temperature and of an
auxiliary temperature regulating appliance substantially as herein before described.
4. The arrangement and combination of parts substantially as herein before
described and shewn on the annexed drawing for regulating the temperature of
the chlorine gas in the manufacture of bleaching powder by processes such as are
hereinbefore mentioned.
Dated this 19th day of January 1893.
J. H. JOHNSON & Co.,
Agents.