Improvements in the Manufacture of Sulphur Trioxide (Sulphuric Anhydride).
Year: 1898

page_text: Date of Application, 4th July, 1898
Complete Specification Left, 4th Apr., 1899-Accepted, 6th May, 1899
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Sulphur Trioxide (Sulphuric
Anhydride).
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, Chan-
cery Lane, in the County of London, Chartered Patent Agent, do hereby declare
the nature of this invention (as communicated to me from abroad by The Farbwerke
vormals Meister Lucius & Brüning, of Hoechst "/Main, in the Empire of Germany,
Chemical Manufacturers) to be as follows:
My, foreign correspondents have found, that in the process described in the
Specification No. 6057 of 1898, for producing sulphur trioxide (sulphuric anhy-
dride) by heating sulphurous anhydride (sulphur dioxide) with oxygen and con-
ducting the hot mixture over a contact body, the following alterations may be
made with advantage, especially if the produced sulphuric acid anhydride is
afterwards to be used for the manufacture of fuming sulphuric acid (commonly
called "oleum.")
Immediately before the gases containing SO2 come into the contact body or
better still, as soon as the gases after forming S03 have left the contact body,
steam, preferably in a superheated state, is introduced into the reaction-gases.
By this, firstly, the temperature of the gas mixture can be raised as desired by
maintaining at a high degree the temperature of the superheated steam thus intro-
duced; secondly the gas mixture has imparted to it by the introduction of steam
a very high capacity for heat and what is particularly of importance even for a
considerable difference of temperature so long as it is above the condensation
point of the sulphuric acid. At a temperature not exactly known, but still con-
siderably above the condensation point, the combination of S03 and H₂O begins
for these as is known, can exist side by side absolutely uncombined at high tem-
peratures. The heat set free by the combining of SO3 and H, opposes cooling.
The temperature of the hot gas current issuing from the contact body and con-
taining SO, is therefore, in the presence of steam notwithstanding an equal
transference of heat, not lowered nearly so much, as would be the case without
introduction of steam; for, in proportion as transference of heat takes place, the
combining of SO, and H₂O to produce vapour of H₂ SO, takes place and the heat
thus evolved prevents rapid fall of temperature.
The advantage which is obtained by the increased formation of H, SO, due
to the introduction of superheated steam (which formation takes place in a pro-
gressive manner according as heat is transferred to the inflowing gas-current) or
to the heat thereby evolved, is such, that the difference in the temperature at the
combination-zone of the two gas-currents is considerably higher and consequently
a very much smaller plant is required for the transference of the same quantity of
heat in a given time.
The process may be illustrated by the following example:
Suppose that a current of gas enters a heat transferring apparatus at 0° C.
and has to be heated to 400° C bv a current moving in the annosite direction

page_text: then this second current, supposing it to enter the 500° C. provided both currents
have the same capacity for heat, will leave the apparatus at a temperature of 100°.
At both the ingress and egress the two currents have a difference of temperature
of 100°. On this difference of temperature depends, as is known, the rapidity of
transference or the extent of surface requisite for transferring a given quantity
of heat. The greater the difference of temperature, the less time or the less sur-
face of contact is required for transferring the heat.
If superheated steam at about 500° is allowed to enter the current which trans-
fers heat, the following results will ensue.
As soon as a certain quantity of heat is transferred from the outgoing current to
the incoming current, the reaction H2O + SO, H, SO, takes place and the
heat which is thus evolved prevents a rapid fall of the temperature and the cur-
rent which passes away will, after the same transference of heat as in the first case,
retain a temperature say 400° much nearer that which it had at first.
The average difference of temperature is therefore in this case about 250° in-
stead of 1000 as in the first case. Consequently with an equal surface for trans-
mission in this latter case, the transference of heat is nearly 3 times as rapid
as in the first case, and it follows, that in applying this modified method for pro-
ducing the same quantity as would be produced by the process described in the
Specification No. 6057 of 1898, the surface for transference of heat that is to say,
the greater part of the plant may be reduced to nearly one third.
Dated this 4th day of IT.... 1000
ABEL & IMRAY,
Agents for the Applicant.
Improvements in the Manufacture of Sulphur Trioxide (Sulphuric
Anhydride).
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, Chan-
cery Lane, in the County of London, Chartered l'atent Agent, do hereby declare
the nature of this invention (as communicated to me from abroad by The Farbwerke
vormals Meister Lucius & Brüning, of Hoechst "/Main, in the Empire of Germany,
Chemical Manufacturers) and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement;-
--
My foreign correspondents have found that in the process described in the
Specification No. 6057 of 1898 for producing sulphur trioxide (sulphuric anhy-
dride) by heating sulphurous anhydride (sulphur dioxide) with oxygen and con-
ducting the hot mixture over a contact body, the following alterations may be
made with advantage, especially if the produced sulphuric acid anhydride is
afterwards to be used for the manufacture of fuming sulphuric acid (commonly
called "oleum.")
Immediately before the gases containing SO, come into the contact body or
better still, as soon as the gases after forming SO, have left the contact body,
steam, preferably in a superheated state, is introduced into the reaction gases.
By this, firstly, the temperature of the gas mixture can be raised as desired by
maintaining at a high degree the temperature of the superheated steam thus intro-
duced; secondly, the gas mixture has imparted to it by the introduction of steam
a very high capacity for heat, so that there is a considerable difference of tem-
perature between the two gas currents so long as the temperature is above the
condensation point of the sulphuric acid. At a temperature not exactly known,
but still considerably above the condensation point, the combination of SO, and H₂O

page_text: begins, for these as is known can exist side by side absolutely uncombined at
high temperatures.
The heat set free by the combining of SO, and H2O opposes cooling.
The temperature of the hot gas current issuing from the contact body and con-
taining SO is, therefore, in the presence of steam, notwithstanding an equal
transference of heat, not lowered nearly so much, as would be the case without
introduction of steam; for, in proportion as transference of heat takes place, the
combining of SO, and H₂O to produce vapour of H₂SO, takes place and the heat
thus evolved prevents rapid fall of temperature.
The advantage which is obtained by the increased formation of H2SO4, due
to the introduction of superheated steam, (which formation takes place in a pro-
gressive manner, according as heat is transferred to the inflowing gas current) or
by the heat thereby evolved, is such, that the difference in the temperature at the
place where the two gas currents first pass each other is considerably higher and
consequently a very much smaller plant is required for the transference of the
same quantity of heat in a given time.
The process may be illustrated by the following example:
Suppose that a current of gas enters a heat transferring apparatus at 0° C.,
and has to be heated to 400° C. by a current moving in the opposite direction,
then this second current, supposing it to enter at 5008 C. provided both currents
have the same capacity for heat, will leave the apparatus at a temperature of 100° C.
At both the ingress and egress the two currents have a difference of temperature
of 100° C. On this difference of temperature depends, as is known, the rapidity
of transference or the extent of surface requisite for transferring a given quantity
of heat. The greater the difference of temperature, the shorter time or the
smaller surface of contact is required for transferring the heat.
If superheated steam at about 500° C. is allowed to enter the current which trans-
fers heat, the following results will ensue.
-
As soon as a certain quantity of heat is transferred from the outgoing current to
the incoming current, the reaction H₂O + SO, H, SO, takes place and the
heat which is thus evolved prevents a rapid fall of the temperature and the cur-
rent which passes away will, after the same transference of heat as in the first case,
retain a temperature say 400° much nearer that which it had at first.
The average difference of temperature is therefore in this case about 250° in-
stead of 1000 as in the first case. Consequently with an equal surface for trans-
mission in this latter case, the transference of heat is nearly 3 times as rapid
as in the first case, and it follows, that in applying this modified method for pro-
ducing the same quantity as would be produced by the process described in the
Specification No. 6057 of 1898, the surface for transference of heat that is to say,
the greater part of the plant may be reduced to nearly one third.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is:-
In the process described in the Specification No. 6057 of 1898 for manufacture
of sulphur trioxide (sulphuric anhydride) the introduction of steam into the
issuing sulphur trioxide gases, so as more rapidly to transfer their heat to the
gases entering the contact substance substantially as described.
Dated this 4th day of April 1899.
ABEL & IMRAY,
Agents for the Applicant.