Improved Method of and Apparatus for Concentrating. Sulphuric Acid.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improved Method of and Apparatus for Concentrating. Sulphuric
Acid.
I, MAURICE SCHWAB, of 96, Deansgate, Manchester, in the County of Lancaster,
Gas Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to the concentration of sulphuric acid, and has for its
object to avoid certain disadvantages and nuisances hereinafter referred to as
incidental to the process as heretofore practised, and to effect with greater
economy, rapidity, and efficiency the concentration of the acid.
In apparatus hitherto employed for the purpose closed chambers containing the
necessary furnaces, flues, and terrace-like settings for supporting spacious
evaporating vessels affording a large heating surface have been employed; in
these spacious vessels the weak acid is boiled in large quantities or volumes until
by evaporation the required strength is obtained, the heat being applied to same
either from below or above, or both.
In all such systems however, so far as I know, owing to the vibration due to
boiling large volumes of acid in comparatively large vessels and other working
conditions, the settings become leaky sooner or later, the gases or vapours from the
evaporating vessels permeate, and as the furnace gases have the greater draft the
two gases mingle and travel together through the flue to the exit of the apparatus.
Also for same reason there has not been absolute control over the deleterious
fumes produced by evaporation, except such portions of same as find their way to
the scrubber or condenser, and hence injurious gases have been continuously
emitted into the atmosphere through the chimney. Neither has there existed any
special means or provision for cleaning the vessels without partly breaking down
and rebuilding the setting and so temporarily stopping the process.
By my invention I obviate such defects, and I prevent vibrations and deteriora-
tion of the apparatus, and I ensure that the acid gases do not pass into the furnace
flue, further I provide for cleaning out when required without stopping the process,
and generally I improve upon existing arrangements.
According to my improvements the apparatus is self-contained and the auxiliary
plant is adjacently disposed; the furnace is in the lower part and I form and
employ for each "run" or straight length of evaporating or concentrating vessels
separate chambers for the furnace gases and the gases of evaporation, separated
from one another by an arrangement of specially constructed shallow trays and
dishes forming together a pas tight diaphragm; thus an upper and a lower flue
are provided in each "run" and each has a separate exit, the one leading the
furnace gases direct to the chimney, and the other leading the gases of evaporation
direct to the condenser, scrubber, or other destination.
The result of using shallow or flat dishes containing but a small volume of acid
at a time is that no considerable vibration or bumping is caused as in the boiling
process with spacious vessels, and hence there is no cracking of dishes, no parting

page_text: of the settings, and the two kinds of gases remain and are conducted separately
to their respective destinations.
The flat dishes 1 employ are of a flattened V shape, having a plain base inclining
upwardly from a vertical rear wall to a curved or curled lip at the front or dis-
charging end, and each is or may be provided with one or more removable
transverse baffle plates beneath which te acid passes. The rear and side walls
of these dishes may be curled or turned over inwardly at their edges to prevent
the creeping" of the acid. The dishes are made of acid-proof material, and
they fit into and are supported by cast iron trays or other suitable supports bedded
on the side seatings and forming the roof of the furnace flues, the areas being
disposed so as to ensure the greatest area of evaporating surface with a minimum
volume of liquid for the purpose of more rapidly and efficiently evaporating the
moisture from the acid. The dishes discharge one into the next lower one from
the top to the foot of the "run."
Further I employ or may employ controllable air passages formed in the
apparatus such as cast iron pipes arranged in the flue and adapted to supply a
suitable current of hot air for the purpose of facilitating the more rapid removal
of the gases of evaporation through their flue to the scrubber or condenser, the
draft of either flue being either natural or suitably forced as occasion requires.
In my improved apparatus I may have but one straight "run" or may form
any desired number of oppositely inclined runs. To the uppermost dish of the
first run somewhat heated acid is admitted and flows over and through the various
dishes to a distributing vessel at the lower end thereof, thence it flows through
the succeeding runs (if any) and finally passes in a highly concentrated state
through conveniently arranged pipes and cocks to a cooler of any suitable type.
To enable the apparatus to be easily cleaned, and also for testing when desired,
and so forth, in the setting over each dish I place a suitably supported covering
fireclay slab or plate adapted to be raised for inspecting the dishes when required,
forming at the same time the roof of the flue for acid vapours.
In order to clean out the deposits from any dish whilst at work I provide in
conjunction with my improvements in the side walls openings fitted with gas
tight doors leading to the dishes.
By the above described invention the greatest furnace heat first meets the most
concentrated acid whence great efficiency results. The shallowness of the dishes
prohibits vibration and its ill results.
Dated this 10th day of October 1896.
J. C. CHAPMAN,
Agent.
COMPLETE SPECIFICATION.
Improved Method of and Apparatus for Concentrating Sulphuric
Acid.
I, MAURICE SCHWAB, Gas Engineer, of 96 Deansgate, Manchester in the County
of Lancaster, 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 concentration of sulphuric acid, and has for its
object to avoid certain disadvantages and nuisances hereinafter referred to as
incidental to the process as heretofore practised, and to effect with greater
economy, rapidity, and efficiency 'the concentration of the acid.
In apparatus hitherto employed for the purpose; closed chambers containing the

page_text: necessary furnaces, flues, and terrace-like settings for supporting capacious
evaporating vessels affording a large heating surface have been employed; in
these capacious vessels the weak acid is boiled in large quantities or volumes,
until by evaporation the required strength is obtained, the heat being applied to
same either from below or above, or both.
In all such systems, however, so far as I know, owing to the vibration due to
boiling large volumes of acid in comparatively large vessels, and other working
conditions, the settings become leaky sooner or later, the gases or vapours from
the evaporating vessels permeate the setting, and as the furnace gases have the
greater draught the two gases mingle and travel together through the flue to the
exit of the apparatus. Also for same reason there has not been absolute control
over the deleterious fumes produced by evaporation, except such portions of same
as find their way to the scrubber or condenser, and hence injurious gases have been
continuously emitted into the atmosphere through the chimney.
Neither has there existed any special means or provision for cleaning the vessels
without partly breaking down and rebuilding the setting and so temporarily
stopping the process.
By my invention I obviate such defects, and by the use of specially formed
shallow evaporating dishes hereinafter described I prevent vibration and
deterioration of the apparatus, and I ensure that the acid gases do not pass into
the furnace flue or the furnace gases into the acid flue, also I provide controll-
able air passages formed in the flues of the apparatus; further I provide means
for easy inspection, testing and so forth and also for cleaning out when required
without stopping the process, and generally I improve upon existing arrangements.
In order that my invention may be fully understood I will describe the same
with reference to the accompanying drawings in which Fig. 1 is a longitudinal
section through one run of an apparatus constructed in accordance with my said
invention, and Fig. 2 is a transverse section on the line -y of Fig. showing
the specially constructed shallow evaporating dishes or trays suitable for use in
carrying out my invention.
According to my improvements the apparatus is self-contained and the auxiliary
plant is adjacently disposed; the furnace A is arranged in the lower part and I
form and employ for each "run" or straight length (of evaporating or concentrat-
ing vessels) separate chambers, one F for the furnace gases and one E for the
gases of evaporation; these chambers are separated from one another by an
arrangement of specially constructed shallow trays and dishes forming together
a gas tight diaphragm; thus an upper and a lower flue are provided in each
run and each has a separate exit, the one F leading the furnace gases direct to
the chimney C, and the other E leading the gases of evaporation direct to the
condenser, scrubber or other destination through the outlet O, and each outlet
is or may be provided with a suitable regulating valve or damper for controlling
the outflow of the respective gases.
"
"
As shown in the figure the special dishes D are arranged in a series of steps
inclining up toward the chimney C; and the acid flows from top to base of the
run."
The advantage of using shallow or flat dishes, which contain but a small
volume of acid at a time, is that no bumping and consequently no considerable
vibration is caused as in the boiling process when capacious vessels are used,
and hence there is no cracking of dishes, no parting of the same from their
settings, or parting of the settings, consequently the furnace gases and the gases
evaporated remain separate and are separately conducted to their destinations.
The flat dishes I employ may be of variously modified constructions and shapes.
The form of evaporating dish shown, is of flattened V shape in. longitudinal
section, having a plane base or floor inclining upwardly from a vertical rear wall
towards the front or discharging end, where it is provided with a curved or curled
lip extending across the width of the dish 1) over which the acid can flow into the
next lower dish, and by which any tendency to creeping of the acid is avoided.

page_text: Each dish may be provided with transverse baffle plates beneath which the acid
passes, and to still further ensure the prevention of creeping, the vertical rear and
side walls of each dish are or may be curled, ribbed or turned inwardly as shown
at c.
The dishes D are preferably made of stoneware or other acid-proof material and
they fit into and are supported by trays T preferably of cast iron which are bedded
on the seatings S set in the side walls of the run, the said trays T forming the
roof of the furnace flue F.
The heating surfaces are so disposed as to secure the greatest evaporation with
a minimum volume of liquid for the purpose of more rapidly and efficiently
concentrating the acid.
The acid to be concentrated, preferably slightly heated, enters the apparatus by
the pipe P, flowing first into the highest dish I which it fills to the level of the
lip, then flowing over this lip into the next lower dish and so on down the run
until the trough G is reached, from which it flows by way of the pipe p.
In order to facilitate the rapid removal from the flue E of the vapour or fumes
resulting from the evaporation of the liquid, I employ or may employ in the
apparatus controllable means for supplying a current of hot air to the evaporating
chamber E as shown. Such means consist of cast iron pipes by which air is led
from the atmosphere. In Fig. 1 air passes through a cock or valve r at the rear
of the run into a cylindrical pipe or heater H placed in the flue I and surrounded
by the products of combustion passing upward to the chimney C. The air heated
in its passage downward by contact with the internal side of this heater is admitted
to the front end of the chamber E by way of a pipe or tube t and its flow regulated
by means of the cock or valve vl.
By this arrangement the vapours or fumes may be caused or allowed to leave the
chamber E at any suitable rate, according as the air is induced by natural or
assisted draught, and incoming air is admitted as required from the heater H.
In order to enable the apparatus to be easily cleaned and also for testing when
desired and so forth, in the setting, above each dish D and supported by the side
walls of the run in such a manner as to form a roof for the evaporation chamber
or flue E, I arrange plates or slabs S of fire clay or other suitable material, any
or several of which may be removed when required. Gastight doors may be
provided in the side walls to permit of cleaning out the deposits from any "dish
during working.
To
In my improved apparatus I may have but one straight run" such as is
illustrated or I may form any desired number of oppositely inclined runs.
the uppermost dish of the first ruu somewhat heated acid is admitted and flows
over and through the various dishes to a distributing vessel G at the lower end
thereof as described, thence it flows through the succeeding runs (if any) and
finally passes in a highly concentrated state through conveniently arranged pipes
and cocks to a cooler of any suitable type..
By the above described invention the greatest furnace heat first meets the most
concentrated acid whence great efficiency results. The shallowness of the dishes
prohibits vibration and its ill results.
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 herein described method of concentrating sulphuric acid which consists
in allowing the acid to flow down over and through a plurality of heated shallow
vessels or dishes from the coolest. to the hottest, the furnace gases flowing in the
opposite direction and the said "run" of evaporating dishes forming a gastight
diaphragm between and separating the two sets of gases, substantially as and for
the purpose above set forth.
2. An apparatus for concentrating sulphuric acid comprising one or more
inclined gastight runs of shallow evaporating dishes such as above described, a

page_text: furnace situated beneath the lower part of such run or runs, with flue rising to the
upper end thereof, and an upper chamber for the gases of evaporation,
substantially as described and illustrated.
3. In apparatus such as above referred to, the use of flattened V shaped
evaporating dishes with plane bases inclining upwardly from a vertical rear wall
to a curved lip at the discharging end, the walls being curled, ribbed or turned
inwards to prevent creeping of the acid and the areas being arranged to secure
the greatest area of evaporating surface with a minimum volume of liquid,
substantially as described.
4. The arrangement and use in combination with the apparatus above referred
to of controllable air passages such as the heater H and its connections, adapted to
supply a current of hot air for the purpose of facilitating the more rapid removal
of the gases of evaporation from the evaporating chamber to the scrubber or
ccndenser.
5. The hereinabove described apparatus for concentrating sulphuric acid pro-
vided with means for inspection, testing and cleansing, all arranged or adapted to
operate substantially as set forth.
Dated this 10
day of August 1897.
For the Applicant,
J. C. CHAPMAN,
70 Chancery Lane, London, W.C., Chartered Patent Agent.