IMPROVEMENT IN THE PRODUCTION OF SULPHURIC ACID and
Year: 1886

page_text: I, HERMANN JOHANN PHILIPP SPRENGEL of the National Safe Deposit Company,
No 1, Queen Victoria Street in the City of London do hereby declare the nature
of my invention for AN IMPROVEMENT IN THE PRODUCTION OF SULPHURIC ACID
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
:-
'
Mechanical operations, such as the pumping of water and the compressing of
air, absorb in Sulphuric Acid Works which possess Gay-Lussac- and Glover-
towers a not inconsiderable amount of steam-and consequently of fuel This
steam, after having spent its energy in the engines, is (as a rule) allowed to escape
into the open air. It is obvious, that this escaping steam, the so-called "exhaust-
steam might render a second service by virtue of its chemical properties, if it
could be made to substitute, without much trouble and expense, a part of another
quantity of steam, which in Sulphuric-Acid-Works has to be raised almost entirely
for the sake of a chemical operation viz. the formation of acid inside the leaden
chambers.
"
This problem I have solved in the following manner.
Be it remembered, that the work done by a steamengine is the result of the
difference of pressure which exists alternately on the two sides of its piston.
Supposing this pressure be 30 lbs. per square inch on the one side and nil on the
other, the work done will be due to the difference of these 30 lbs. per square inch.
Hence the same work may be done by the same engine, if the pressure be kept
at 40 lbs. per square inch on the one side of its piston and at 10 lbs. per square
inch on the other, for the difference of pressure remains unaltered or 30 lbs. per
square inch.
In factories of an average size not more than one steamboiler serves, as a rule, to
supply steam of a uniform pressure of about 30 lbs. per square inch both to the
engines and to the chambers. As, however, a pressure of 10 lbs. per square inch is
ample and to spare for the steam entering the chambers, I now in harmony with
the above view :-
1) raise the pressure in such a steamboiler by 10 lbs. per square inch, i̟.e. in this
case from 30 lbs.. to 40 lbs,

page_text: 3) make the exhaust-steam from the engines enter the chambers at a pressure of
10 lbs. per square inch and
4) supplement, when needed, any deficiency of steam in the chambers by another
quantity of steam of the same pressure i.e. steam of 10 lbs. per square inch, drawn
from this very boiler which is kept at a constant and regular pressure of 40 lbs.
per square inch.
How this may be done in a convenient and inexpensive manner, will be readily
understood by referring to the annexed diagrammatic sketch.
A represents a steamboiler and B a pump, supplied with steam of a constant
pressure of 40 lbs. per square inch by the pipe a b. The exhaust-steam of this
pump escapes through c d into the main steam-pipo ef, which carries steam of a
pressure of 10 lbs. per square inch to the chambers. This main steampipe e fis
connected with the steam boiler A and is provided with two valves :
1) a reducing-valve R and
2) a safety or escape-valve S.
These two valves are weighted in such a manner, that as soon as the pressure
in of becomes less than 10 lbs. per square inch, the valve R will admit steam from
the boiler until a pressure of 10 lbs. is re-established in ef; while as soon as the
pressure in ef becomes more than 10 lbs. per square inch, the valve S will allow
an escape of steam into the open air until a pressure of 10 lbs. is re-established
in ef. In other words and by way of an example a 40 lbs.-pressure in the boiler
will lift and overcome a 30 lb.-weight plus a 91 lb.-counter-pressure of steam at R,
while a 10 lb.-pressure in ef will lift a 10 lb.-weight at S.
Thus it will be seen, that one boiler and one system of pipes are sufficient to
supply simultaneously both the engines with high-pressure-steam and the chambers
with low-pressure-steam.
To ensure, what is much to be desired, an even, constant and regular pressure
in ef, it is essential, that these valves R and S should be sensitive or in technical
language not be liable to "stick."
M and M represent manometers for indicating the pressure inside the boiler A
and the pipe e f; while a represents a steam-trap and an outlet for condensed steam
which in the form of water will collect in the pipes above x.
In the same way as the exhaust-steam from only one pump is shown here to be
utilised, so the exhaust-steam from two or more pumps may be utilised by con-
necting the same with ef, for instance at o.
As an experimental proof it may be mentioned, that by utilising in this manner
the exhaust-steam from 4 small engines attached to the water-pumps and air-
compressers at the Works of the Lawes' Chemical Manure Company, Creek's Mouth,
Barking, Essex, I have been able to dispense with one of two steamboilers formerly
in use, thus reducing the consumption of coal 34 per cent; the quality of coal and
the amount of work done remaining unaltered.
⚫ Though this invention relates in the first instance to the utilisation of exhaust-
steam of engines which are to be met with in every Sulphuric-Acid-Works
possessing Gay-Lussac- and Glover-towers, it is obvious, that the exhaust-steam
from any other engine, which happens to be discharged into the open air in the
vicinity of sulphuric-acid-chambers, may be utilised as before described, even if
this exhaust-steam should be derived from an engine supplied with steam from a
different boiler at a different pressure, for the regularity of pressure needed in the
chamber-steam-pipes will thereby not be affected, but will still be maintained by
the valves R and S. In fact, the use of exhaust-steam in the manufacture of
sulphuric acid may be carried with advantage to the point, at which the sum total
of the thus collected quantity of exhaust-steam equals the total quantity of steam
needed in the chambers.
Hence, only after this point has been passed, is there good reason to employ in
the vicinity of sulphuric-acid-chambers engines, from which there is no escape of
exhaust-steam properly speaking, e.g. the so-called condensing-engines.

page_text: Finally I beg to state, that I do not restrict myself to the above stated pressures
of 40 and 10 lbs. per square inch as the only ones which may be used. I merely
have mentioned these pressures as those, at which I have obtained very satisfactory
results.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
The utilisation of so-called exhaust-steam, when escaping from steamengines
near sulphuric-acid-chambers in the manufacture of sulphuric acid in the manner
herein before described.