Improvements in Apparatus for the Manufacture of Monohydrated Sulphuric Acid.
Year: 1887

page_text: Date of Application, 24th Mar.. 1887
Complete Left, 17th Dec.. 1887
Complete Accepted, 27th Jan.. 138
Improvements in Apparatus for the Manufacture of Monohydrated
Sulphuric Acid.
I, JOHN BROCK of the British Alkali Works, Widnes, in the County of Lancaster,
Alkali Manufacturer (partly communicated to me from abroad by Professor George
Lunge, of Zürich, Switzerland) do hereby declare the nature of this invention to le
as follows:
On January 3rd 1888 Letters Patent numbered 96 were granted to Walter Weldon as
a communication from the said Professor George Lunge of Zürich Switzerland for a
process for obtaining monohydrated sulphuric acid from ordinary "rectified oil of
vitriol" by means of artificial cold.
The present invention relates to an improved apparatus for carrying out that
process.
Commercial sulphuric acid is first concentrated by evaporation in vessels of glass,
platinum or iron or in any other suitable manner up to the strength which can be
technically obtained in this manner without special difficulties. Sulphuric acid at.
this degree of concentration is usually called rectified oil of vitriol or else "sul-
phuric acidat 170 degrees of Twaddell's hydrometer," although it shows only
165 degrees with a properly constructed hydrometer at ordinary temperatures. Such
acid varies in strength from 93 to 97 per cent. of real monohydrated acid H, SO.. or
thereabouts. Most usually it contains from 94 to 96 per cent. of H, SO, but it is
preferable to get it up to 97 per cent., or even higher, because in that case the mother
liquors from the manufacture of monohydrate still contain from 94 to 95, or at least
93 per cent. of H, SO,, and therefore can be sold as ordinary rectified oil of
vitriol."
The concentrated acid, after having been cooled down in the usual manner in a
refrigerator attached to the still is conveyed, by means of air-pressure or in any other
suitable manner,
to a store tank placed at a somewhat higher level than the "charging
box"
of the freezing-machine. It is preferable, instead of running the acid
directly from the store tank into the charging box to let it descend to the ground
level in a conduit in which is interposed a worm cooled by cold water, or other
suitable refrigerating contrivance. The acid is then again raised in another pipe to
a little above the top of the charging box and then again descends in a short pipe
inserted into the top of the charging box. A tap is interposed in some suitable

page_text: place in the conduit, in order to shut off the communication between the store-tank
and the charging box during the time a charge is being blown out of the latter.
The charging box" is preferably made of iron and of such a shape that it
stretches from side to side right across the tank containing the freezing cells. It is
divided by vertical partitions into the same number of divisions as that of the freezing
cells and each of these divisions is made of such size that on blowing out its contents
it exactly fills one of the freezing cells to a suitable height. The partitions do not
reach quite up to the lid of the charging box, so that all the divisions are filled by
the supply pipe from the store tank and their contents are forced out at the same time
by means of the compressed air, acting through a pipe inserted into the lid of the
charging box. This compressed air pipe rises to a higher level than the top of the
store tank before descending to the air pump; consequently when the charging box
is put into communication with the store tank the acid fills the entire charging box
and rises in the air pipe up to the level of the store tank but it does not overflow
into the air pump. The air pipe is provided with two taps one of them communicating
with the air pump, the other with the open air; the latter tap is opened while the
box is being charged with acid and is shut immediately afterwards.
Each of the divisions of the charging box is provided with a discharge pipe which
begins just above the bottom (preferably curved) of the box and passes out of the lid
and rises upwards above the top of the store tank so that no acid can overflow during
the charging of the box from the store tank. The discharge pipes then descend side
by side, so that the lower end of each is just above one of the freezing cells. Thus,
as soon as the compressed air begins to act upon the surface of the acid contained in the
box all the discharge pipes begin to play simultaneously, and all the freezing cells
belonging to that particular row are filled at the same time. When this has been
lone a leaden dish is brought underneath the ends of the pipes, in order to catch the
acid draining out of them and convey it away. The row of freezing cells which is
suspended in an iron frame is moved by means of a travelling crane to the other end
of the freezing tank which contains a number, say 10 or 15 of such rows of freezing
cells, the space between the cells being filled with a solution of chloride of calcium
kept at a low temperature, say-20° Centigrade, or somewhat more or less, by
means of any convenient cold producing machine. Each time a fresh row of cells
nas been filled the frames containing the other rows, which rest on pulleys, are moved
towards the other end of the tank so as to allow of the last filled row of cells being
owered into the freezing tank.
When the row of cells which has been longest in the freezing tank has been sufli-
ciently cooled down, it is lifted out by means of the travelling crane. The cells are
then dipped for a few seconds in a vessel containing warm water, in order to detach
the frozen mass from the sides of the cell by superficial fusion, and when this has been
effected the cells are lifted out and are tilted into a spout or shoot, care being taken
to prevent any of the water adhering to the outside of the cell getting into the spout.
The spout contains an Archimedian screw which crushes up the frozen mass and
conveys it into a centrifugal machine, placed beside the apparatus. The cells are then
righted again and are ready to receive another charge of rectified oil of vitriol. By
the action of the centrifugal machine the frozen mass is rapidly separated into a white
crystallized mass of monohydrated sulphuric acid and a mother liquor consisting of
less concentrated acid. The latter is either sold in that state or is brought up to full
strength by the ordinary processes of concentration. The solid monohydrate is
scooped out of the centrifugal machine into a pan preferably made of iron enamelled
inside, and surrounded by a warm water jacket; here it is melted and is by means of
a tap run out into carboys or other vessels intended for storing and carrying the
product.

page_text: Improvements in Apparatus for the Manufacture of Monohydrated
Sulphuric Acid.
I, JOHN BROCK of the British Alkali Works, Widnes, in the County of Lancaster,
Alkali Manufacturer (partly communicated to me from abroad by Professor George
Lunge, of Zürich, Switzerland) 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 :—
On January 3rd 1883 Letters Patent numbered 96 were granted to Walter Weldon
as a communication from the said Professor George Lunge of Zürich Switzerland for
a process for obtaining monohydrated sulphuric acid from ordinary rectified oil of
vitriol" by means of artificial cold.
The present invention relates to an improved apparatus for carrying out that
process.
Commercial sulphuric acid is first concentrated by evaporation in vessels of glass,
platinum or iron or in any other suitable manner up to the strength which can be
technically obtained in this manner without special difficulties. Sulphuric acid at
this degree of concentration is usually called rectified oil of vitriol
::
or else sul-
phuric acid at 170 degrees of Twaddell's hydrometer," although it shows only
168 degrees with a properly constructed hydrometer at ordinary temperatures. Such
acid varies in strength from 93 to 97 per cent. of real monohydrated acid H₂ SO,
or thereabouts. Most usually it contains from 94 to 96 per cent. of H, SO, but it
is preferable to get it up to 97 per cent., or even higher.
;
The concentrated acid, after having been cooled down in the usual manner in a
refrigerator attached to the still is conveyed, by means of air pressure or in any
other suitable manner, to a store tank placed at a somewhat higher level than the
charging box" of the freezing-machine. It is preferable, instead of running the
acid directly from the store tank into the charging box to let it descend to the ground
level in a conduit in which is interposed a worm cooled by cold water, or other
suitable refrigerating contrivance. The acid is then again raised in another pipe to a
little above the top of the charging box and then again descends in a short pipe
inserted into the top of the charging box. A tap is interposed in some suitable place
in the conduit, in order to shut off the communication between the store-tank and the
charging box during the time a charge is being blown out of the latter.
The charging box" is preferably made of iron and of such a shape that it
stretches from side to side right across the tank containing the freezing cells. It is
divided by vertical partitions into the same number of divisions as that of the freezing
cells and each of these divisions is made of such size that on blowing out its contents

page_text: it exactly fills one of the freezing cells to a suitable height. The partitions do not
reach quite up to the lid of the charging box, so that all the divisions are filled by the
supply pipe from the store tank and their contents are forced out at the same time
by means of the compressed air, acting through a pipe inserted into the lid of the
charging box. This compressed air pipe rises to a higher level than the top of the
store tank before descending to the air pump consequently when the charging box
is put into communication with the store tank the acid fills the entire charging box
and rises in the air pipe up to the level of the store tank but it does not overflow into
the air pump. The air pipe is provided with two taps one of them communicating
with the air pump, the other with the open air the latter tap is opened while the
box is being charged with acid and is shut immediately afterwards.
Each of the divisions of the charging box is provided with a discharge pipe which
begins just above the bottom (preferably curved) of the box and passes out of the
lid and rises upwards above the top of the store tank so that no acid can overflow
during the charging of the box from the store tank. The discharge pipes then
descend side by side, so that the lower end of each is just above one of the freezing
cells. Thus, as soon as the compressed air begins to act upon the surface of the acid
contained in the box all the discharge pipes begin to play simultaneously, and all the
freezing cells belonging to that particular row are filled at the same time. When this
has been done a leaden dish is brought underneath the ends of the pipes, in order to
catch the acid draining out of them and convey it away. The row of freezing
cells which is suspended in an iron frame is moved by means of a travelling crane
to the other end of the freezing tank which contains a number, say 10 or 15 of such
rows of freezing cells, the space between the cells being filled with a solution of
chloride of calcium kept at a low temperature, say-20° Centigrade, or somewhat
more or less, by means of any convenient cold producing machine. Each time a
fresh row of cells has been filled the frames containing the other rows, which rest on
pulleys, are moved towards the other end of the tank so as to allow of the last filled
row of cells being lowered into the freezing tank.
When the row of cells which has been longest in the freezing tank has been suffi-
ciently cooled down, it is lifted out by means of the travelling crane. The cells are
then dipped for a few seconds in a vessel containing warm water, in order to detach
the frozen mass from the sides of the cell by superficial fusion, and when this has
been effected the cells are lifted out and are tilted into a spout or shoot, care being
taken to prevent any of the water adhering to the outside of the cell getting into the
spout. The spout contains an Archimedian screw which crushes up the frozen mass
and conveys it into a centrifugal machine, placed beside the apparatus. The cells are
then righted again and are ready to receive another charge of rectified oil of vitriol.
By the action of the centrifugal machine the frozen mass is rapidly separated into a
white crystallized mass of monohydrated sulphuric acid and a mother liquor consisting
of less concentrated acid. The latter is either sold in that state or is brought up to
full strength by the ordinary processes of concentration. The solid monohydrate is
scooped out of the centrifugal machine into a pan preferably made of iron enamelled
inside, and surrounded by a warm water jacket; here it is melted and is by means
of a tap run out into carboys or other vessels intended for storing and carrying the
product.
Dusan
The drawing shows an end view of an apparatus constructed according to my
invention A is the reservoir of acid-B is the cooling worm-C is the charging box
it is divided into a number of equal compartments (one for each freezing cell) by
partitions parallel to the plane of the paper-D is one of the freezing cells-E is an
air cock is the compressed air cock-G is a stop cock-H H are the acid pipes
JJ the compressed air pipes and K K the discharge pipes.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The closed charging or measuring box which is filled by gravitation and
emptied by air pressure substantially as described.
2. The combination of the store chamber the charging box and the pipes
substantially as described.
3.—The apparatus substantially as described and shown in the drawings.