IMPROVEMENTS IN CALCINING BICARBONATE OF SODA PRODUCED BY THE AMMONIA PROCESS, AND IN APPARATUS FOR THAT PURPOSE
Year: 1880

page_text: LETTERS PATENT to Walter Weldon, of Rede Hall, Burstow, in the County of
Surrey, for an Invention of "IMPROVEMENTS IN CALCINING BICARBONATE OF
SODA PRODUCED BY THE AMMONIA PROCESS, AND IN APPARATUS FOR THAT
PURPOSE." A communication from abroad by Alfred Rangod. Pechiney,
Chemical Manufacturer, of Salindres, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the Office
of the Commissioners of Patents on the 24th May 1880.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey. "IMPROVE-
MENTS IN CALCINING BICARBONATE OF SODA PRODUCED BY THE AMMONIA
PROCESS, AND IN APPARATUS FOR THAT PURPOSE." A communication from
abroad by Alfred Rangod Pechiney, Chemical Manufacturer, of Salindres, in the
Republic of France.
This Invention consists partly in driving off from bicarbonate of soda produced
by the ammonia process its second equivalent of carbonic acid and the ammoniacal
compounds associated with it, by treating the bicarbonate with carbonic acid gas
proceeding from the calcination of a previous quantity of bicarbonate, this carbonic
acid gas being heated in a special apparatus before being so employed, and partly in
a particular form of apparatus for carrying this method of calcination into effect.
The apparatus in question consists essentially of four chambers of brickwork; A,
B, C, and D, the whole of the four chambers being enclosed in one and the same
iron case, and this case being so supported upon a central pivot as to be susceptible
of a movement of rotation. This pivot rests on the piston of a hydraulic press, so
that the whole case containing the four chambers can be first raised and then
lowered a few inches at will. In the bottom of each of the four chambers is an
aperture, and when the case containing the four chambers is in any one of its four
normal positions, three of these four apertures are immediately above the upper
extremities of certain channels for gas, with which they are then in communication
by means of hydraulic lutes. Besides the four chambers in the brickwork in the
iron case, there are also in that brickwork four tubes or channels E, F, G, and H,

page_text: each of which similarly corresponds to, and is capable of being connected by means
of a hydraulic lute with, a channel below it, in such wise that when the apparatus
is at work heated carbonic acid gas can enter at the bottom of the chamber A, pass
upwards through that chamber, pass out of it into the upper extremity of the
channel E, pass downwards through that channel into the channel communicating
with the aperture in the bottom of the chamber B, pass upwards through chamber B,
pass out of chamber B into the channel F, and then downwards into the channel
communicating with the bottom of chamber C, then pass upward through
chamber C, and then pass out of chamber C into the channel G, and pass down
channel G into an exit-pipe communicating with a refrigerator and other apparatus,
as will be hereafter mentioned. The heated gas thus passes through only three
of the four chambers, one of the four chambers being always isolated from the
current of gas for the purpose of being discharged and recharged. When the
charge in chamber A has been sufficiently calcined the pivot on which the case
containing the four chambers rests is raised by means of the hydraulic press, upon
whose piston that pivot is supported sufficiently to permit the upper and lower lips
of the various hydraulic lutes clearing each other, and a quarter of a revolution is
then given to the whole case. This isolates chamber A, which is then discharged
and recharged, while the current of heated carbonic acid gas now passes, firstly
into chamber B, then downwards by the channel F into the channel communicating
with the bottom of chamber C, then upwards through the chamber C, then downwards
by the channel G into the channel communicating with the bottom of the
chamber D, and finally upwards through chamber D, and then downward by tho
channel H into the exit-pipe, as before. When the charge in chamber B is
sufficiently calcined, another quarter turn is given to the case, whereby chamber B
is isolated for discharging and re-charging, the hot gas now passing first into C,
then into D, then into A, and from A. into the exit-pipe. When the charge in Bis
finished another quarter revolution is made, and so on continually.
The bicarbonate is charged through a door in the top of each chamber on to a
grating near the bottom of the chamber. For discharging each chamber should
have a door in one of its sides. The temperature being too high to permit of the
use of water for the hydraulic lutes, it is preferred to use in them a readily fusible
metallic alloy. Paraffin or other such body may also be used in them.
The
The heated gas which is passed over and through the bicarbonate in the
aforesaid chambers drives off therefrom, not only carbonic acid, but also water and
ammonia, or compounds thereof. The mixture of gas and vapours passing off from
the chambers must therefore go first to a suitable refrigerator or condenser, in
which the vapours in it shall be condensed, as will be well understood.
carbonic acid gas must then pass on to a suitable reservoir, from which a portion
of it shall be pumped into the apparatus in which it is to be applied to the
production of more bicarbonate, and the remainder pumped, forced, or aspirated
into the stove or other apparatus in which it is to be heated in order to be applied
to the calcination of more bicarbonate. The stove or other apparatus used for
heating the carbonic acid gas may be any of those used for heating the air supplied
to blast furnaces.
Instead of heated carbonic acid gas, heated air may be employed as above
described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Walter Weldon in the Great Seal Patent Office on the 22nd
November 1880.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey. "IMPROVE-
MENTS IN CALCINING BICARBONATE OF SODA PRODUCED BY THE AMMONIA
PROCESS, AND IN APPARATUS FOR THAT PURPOSE."
This Invention consists, firstly, in reducing bicarbonate of soda, as manufactured
by what is known as the ammonia process, to the state of monocarbonate of soda,
by the method which will hereinafter be described; and, secondly, in a furnace or
apparatus for carrying the said method into effect.
The said method of performing what it will be convenient to call the calcination
of the bicarbonate of soda consists in sending over and through the mass of the
bicarbonate of soda, charged in lumps or cakes into a suitable apparatus, carbonic
acid gas, which has been obtained by the calcination of a previously treated
quantity of bicarbonate of soda, and which, before being employed to effect the
said calcination, has been beated to the necessary temperature for the special
purpose stated.
From the furnace or apparatus in which this method of effecting the calcination
of bicarbonate of soda is performed there passes off, not only the carbonic acid sent
into that apparatus as heated gas, but also the further quantity which is liberated in
that apparatus itself from the bicarbonate treated therein by the heat communicated
to that bicarbonate by the heated carbonic acid gas sent over and through it as afore-
said. With the carbonic acid gas which passes off from the said apparatus, and which
is thus partly carbonic acid gas which went into the apparatus as such, and partly
gas which has been liberated from bicarbonate in the apparatus itself, there also passes
off vapour of water and vapour of ammonia, which have also been driven off from
the bicarbonate by the heat of the gas sent into the apparatus as such. From the said
apparatus, therefore, the said mixture of gas and vapours passes first to a
refrigerator, in which water and ammonia are condensed out from it. What passes
off from the refrigerator is then pure, or nearly. pure carbonic acid gas, which then
passes on into a reservoir of the nature of a gasometer. From this reservoir a part
of the carbonic acid gas which is continually entering it is pumped or otherwise
forced into apparatus in which it is employed for the formation of more bicarbonate,
and the other part of it is pumped or otherwise forced into an apparatus in which
it is again heated in order to be then used for the calcination of more bicarbonate.
The heating apparatus employed may be of any of the kinds which are used for
beating air supplied to blast-furnaces.
An apparatus suitable for the performance of the said method of effecting the
calcination of bicarbonate of soda is represented in the accompanying Sheet of
Drawings, in which A, A1, A2, A3, Figures 1 and 3, are four chambers of brickwork,
enclosed in and bound together by an iron envelope. P, Figure 2, is a pivot,
resting upon the piston of a hydraulic press. The dispositions are such that, as
shown in Figure 2, when the piston P' is raised the whole system of chambers is
supported by the pivot P. The case containing the four chambers is then
susceptible of a movement of rotation.
Near the bottom of each of the four chambers A, A1, A2, A3, is a grate, upon which
the bicarbonate is placed in lumps or cakes; in the top of each chamber is a door
by which the chamber is charged with bicarbonate; and in one of the sides of each
chamber is another door by which it is discharged. The positions of the grates
and doors will be sufficiently understood from Figures 1 and 3.
The current of carbonic acid gas, sufficiently heated to be capable of effecting the
calcination of the bicarbonate, arrives by the tube or flue B, Figures 1, 3, and 4, and

page_text: passes upwards through the mass of the carbonate resting on the grate of the
chamber A. From the top of the chamber A it passes downwards by the channel C
into the curved tube or flue B¹, Figures 1 and 4, and thence into the chamber A¹.
Having passed upwards through the chamber A¹, it next passes downwards by the
channel C, Figure 3, which is similar to C, and then by the tube or flue B³, which
is curved like B', and the two extremities of which are shown in Figure 4, into the
bottom of the chamber A. Having passed upwards through the chamber A, it
• passes from the top of that chamber, by the channel C2, into the tube or flue B³, by
which it passes to the refrigerator aforesaid.
When the calcination of the charge in the chamber A has been completed, the case
containing the four chambers is lifted up by the piston P¹, and a quarter of a
revolution is given to it. The piston P¹ is then lowered to its normal position, and
with it the case containing the four chambers also. The chamber As, which was
not previously included in the circuit of the current of heated carbonic acid gas,
has now become included in that circuit; while the chamber A, which before was
the first of the three chambers traversed by the current of heated gas, is now
removed out of that current to permit of its being discharged and re-charged. The
current of heated gas now passes from B into the bottom of A', from the top of A'
by C and B¹ into the bottom of A2, from the top of A² by C² and B2 into the
bottom of As, and from the top of A³ by Cs and B³ as before.
When the charge in the chamber A¹ is finished another quarter turn is given to the
system, whereby A' is isolated, and A² made the first and A the last of the three
chambers traversed by the current of heated carbonic acid gas. Of the four
chambers, three are thus always being traversed by the currents of heated carbonic
acid gas, except during the brief periods during which the case containing the four
chambers is being raised, turned, or lowered, while one chamber is always isolated
from the current to permit of its being emptied and re-filled. The course of the
current of heated gas is thus successively A, A1, A2, A³ being isolated; then
A1, A2, A3, A being isolated; then A2, A3, A, A' being isolated; and lastly
A³, A, A1, A2 being isolated, from which point the order of the successive series
recommences.
Instead of using heated carbonic acid gas for the calcination of bicarbonate of
soda as above described, heated air or other gas or mixture of gases may be used.
What is claimed as the Invention to be secured by the hereinbefore in 'part
recited Letters Patent is as follows:-
Firstly. The method of driving off from the bicarbonate of soda produced in tho
ammonia process its second equivalent of carbonic acid, its water, and any
ammoniacal compounds associated with it, which consists in passing over and
through the mass of the bicarbonate, charged in lumps or cakes in a suitable
apparatus, carbonic acid gas which has been driven off from a previously treated
quantity of bicarbonate, such carbonic acid gas, before it is so passed over and
through the mass of the bicarbonate from which it is to drive off carbonic acid,
water, and ammonia, being first heated to the requisite temperature, specially in
order that it may be so employed; and,
Secondly. Apparatus in which to perform this treatment of bicarbonate by heated
carbonic acid or other gas, substantially such as is described in the foregoing
Specification.
In witness whereof, I, the said Walter Weldon,-have hereunto set my hand
and seal, this Eighteenth day of November, in the year of our Lord: One
thousand isht hundred and nighter
WALTER WELDON.... (L.S.)