Year: 1899

page_text: Date of Application, 1st June, 1899
Complete Specification Left, 20th Feb., 1900-Accepted, 30th June, 1900

page_text: by the use of mercury for the thermodynamic medium by carrying out the
principle of using a one-atomic gas which during expansion does not devolve
intra-molecular power for effecting the working. The proportion n of the two
specific heats for mercury is 166, for air 141 and for superheated steam 1301,
therefore
becomes 04. 0·29. and 6:23 respectively and the formule
n- I
From these data it follows that the ratio of expansion for mercury is 15°19
instead of 44:16 for air, or 1035 for gases which follow the laws relating to
steam. For the boiling temperature of mercury (357° C.) at which already
52% of the heat has been converted into mechanical work, and using the mercury
as vapour, a ratio of expansion of 63 only is required.
The use of mercury as a thermodynamic medium has still further advantages
as will be clearly understood from the following description which by way of
an example fully explains the principle here involved.
In carrying this invention into effect I utilise a turbine the shaft of which is
located in an air tight chamber. The driving medium for the turbine is vapour
of mercury which is admitted through a suitable cock. The mercury vapour
is produced in a vapourizing coil capable of yielding to alterations in temperature
and located in the downwardly arranged flue of a furnace. The said coil being
supplied from a longitudinally flanged pipe by opening a valve. The said flanged
pipe is located in an upright flue and is moreover connected with the turbine
chamber by a condensing coil. In order to avoid loss in mercury while feeding,
it is advantageous to surround the flanged pipe by a shell communicating with
an empty vessel. A suitable device in the form of a barometer chamber for
example is also provided for regulating the valve of the flanged pipe, said device
being arranged near and communicating with the upper portion of the vapourizing
coil and through the intervention of a rod effects the opening or closing of the
said valve automatically on the pressure rising to I atmosphere. The driving
power of the shaft of the turbine is transmitted to another shaft through the
medium of suitable gearing, the said shaft passing through a mercury vessel
provided with a stuffing box and power being transmitted to said shaft in any
suitable manner.
The operation of the apparatus is as follows:-
Mercury being admitted in an atomized condition from the flanged tube through
the valve enters the vapourizing coil where it becomes vapourized, the vapour
passing through the admission cock into the turbine which it drives as will be
hereinafter described. The mercury vapours on leaving the turbine pass into
the lower portion of the enclosing chamber and then into the condensing coil where
the mercury condenses and finally enters the flanged or supply tube.
enclosing chamber of the turbine communicates with the condensing coil which
As the
according to the previously assumed calculations has a temperature of about
27° C., it will be evident that a nearly complete vacuum is created in the chamber;
the pressure being about 1/2000 Atm. The vaporizing coil is arranged to have 4
a temperature of 627° C. with a pressure of 1 Atm. This will effect a ratio of
expansion more than that of 15'6 as found by the foregoing calculations even when
the starting pressure is below 1 atm. Thus it is possible to utilize a vapourizer
without internal pressure and the vapourizing coil, which may by preference he
made of iron or nickel, may be of the thickness of paper and therefore require 5

page_text: very little heating surface. The coil may furthermore be covered by suitable
means and yet be as easily heated as an enamelled cooking utensil."
There is no fear of the poisonous and costly mercury vapours escaping in as
much as the smallest opening in the coil would enable air to enter and so destroy
the vacuum in the turbine chamber. Moreover as the calculated ratio of expan-
sion (156) is greatly surpassed there is the one advantage, notwithstanding any
resistances arising from the expansion in the turbine, that a final temperature
of 27° C. is obtained. The prevailing conditions of temperature are those at
which amalgams decompose and therefore there is no danger of an amalgam being
formed by the mercury vapours and the metal of the vaporizer even if the metallic
surface of the latter were oxidized or coated.
The highly superheated mercury vapour of 627° C., compared with the ordinary
temperature of mercury vapour of 357° C., acts somewhat like a gas from which
its speed at the discharge can be calculated. This speed must be kept low as
compared with air under the same conditions because mercury vapour is known
to be 685 times heavier than air. In assuming that the mercury vapour is
admitted into the turbine after having been allowed to expand to 1/16th of an atm.
a speed for this highly superheated vapour which may be taken as a gas, of
356 m. per second can be relied upon. Even with an expansion bringing the
pressure nearly down to zero the speed is only 436 m. The corresponding peri-
pheral speeds for steam turbines are quite within the normal.
Thus the turbine driven by mercury vapour runs at a moderate and favourable
speed, while steam turbines have to work with steam flowing at the rate of
1000 m., and more.
The arrangement above described requires no feed pump because of the pressure
in the vaporizer being hardly one atin. the feed valve need only be weighted
by a mercury column of 760 m/m in order to open. However on thermodynamic
principles the engineer will preferably use a column of mercury of 4 m., or more.
The manner of feeding has also several advantages accruing from the use
of mercury.
In the feeding of steam boilers there are certain defects allowed to exist with
regard to thermodynamical principles due to 'the use of the feed pump instead of
a Zeuner feed cylinder for adiabatic compression and heating of the mixture of
steam and water derived from the condenser (see Zeuner's Techn. Thermodyn.
Vol. II page 371).
This defect arises in consequence of the heat in the feeding liquid being often
much below the limit T₂ of temperature; and with superheated steam the evaporat-
ing heat from boiling point to T, must be added. Taking the specific heat as
the same as water-1 a loss of 10% in the first instance occurs with the narrow
limits of temperatures of a steam engine. The feeding of a boiler of 627° C.
with the liquid having a specific heat of 1 would entail a great loss of heat. The
specific heat of mercury is 1/30 and thus the above mentioned defect in the feeding
is reduced to a minimum. Furthermore the loss in vapourizing mercury is
but small say 60° to 70° as against 540° for steam which of course from a
mechanical view is an advantage with regard to the method of superheating.
As the heat of liquid mercury is low and liquid mercury is a good heat con-
ductor it is possible to obtain the required heat from the flue or chimney gases
which it is impossible to do when water is used. In the arrangement as herein-
before set forth the feeding liquid flows through the aforesaid flanged pipe which
for that purpose is made as long as possible and in this the mercury is heated
ither under its own pressure or under the pressure from a feed pump. Even
with a minimum length of pipe, viz. 76 cm., the absorbed vaporizing heat by
3570 C., gives a working effect of 52 %. If the valve of the said flanged pipe is
oaded to equal a column of 4 m. mercury by additional liquid or by pressure from
piston, the mercury will still remain liquid at 470° C., corresponding to 5 atm.,
team pressure, and the vaporising heat then applied would give a useful effect
of 60% in the Carnot cycle. It is quite possible with the flanged feeding pipe

page_text: to keep the mercury liquid up to 627° C. and thus spray it into the vapour
chamber.
The above arrangement given by way of an example has demonstrated the advan-
tages possessed by mercury for use as a medium in thermodynamic apparatus, the
same advantages are also noticeable in connection with other arrangements, such as
cylinder engines as will he understood by those skilled in the art without requiring
further description.
Improvements in and relating to Vapour Engines.
I, REGINALD HADDAN, of the Firm of Herbert Haddan & Co., of 18, Bucking-
ham Street, Strand, London, W.C., Patent Agent, do hereby declare the nature of
this invention, a communication to me from abroad by Paul Rahmer, Merchant, of
Schoneberg, Berlin, in the Empire of Germany, and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:
-
is
power
In vapour engines, that is to say, in engines in which the motive
generated by heat, it has not hitherto been possible to carry out the requirements
governing the ideal Carnot cycle. This invention has for its purpose to make
the technical proposition in question nearer attainable than has heretofore been
possible.
In order to obtain favorable results when converting heat into mechanical
work it is necessary to obtain great differences in temperature and where this
has been properly carried out, another equally important condition presents itself,
viz. high pressures and this latter condition is the most difficult condition to
deal with. The following example will clearly demonstrate this.
1=
300
A motor being required to work between the extreme temperatures T₁
(= 27° C) and T, = 3 × 300 (= 627° C) wl en the loss of lieat will be found to
be of the heat introduced and the theoretical useful effect is 66% or 2/3 presum-
ing adiabatic expansion of the thermodynamic medium, say air for example, in
connection with a Carnot cycle, the expansion of such air being ascertained by
the formula
in which P indicates the pressure and the ratio between the two specific heats,
(T, and T, are the technical symbols applied to the absolute temperatures between
which a hot air engine works). Under these circumstances the ratio of expansion
P2 would be 44.16. For higher temperatures the result is still more unfavorable
because the entire heat of the gas must be consumed by the work of expansion,
while at the same time the work produced by the expansion decreases constantly
and quickly on account of the rapid decrease in pressure. Such ratio of expansion
as above referred to presents great difficulties to the engineer.
P₁
It is difficult to erect a cylinder engine calculated to have a pressure of admission
44 times higher than the exhaust pressure and to have a true adiabatic line in
the indicator diagram, immaterial whether the work be performed at one or
more phases. A turbine for the same purpose ought to be constructed so as to
have a peripheral speed corresponding to the velocity of at least 1000 m. per second

page_text: Steam at
of the entering or inflowing gas: but a turbine wheel with such velocity of circum-
ference (about 500 m. per sec.) will explode by the centrifugal force.
a temperature of 600° C. cannot be employed at all on account of its destructive
chemical action without taking into consideration the ratio of expansion.
It is however not necessarily always the case that favourable temperatures
should result in a mechanically unfavourable ratio of expansion.
T₂
T₁
represents
a power of 2 From this it is clear that P2 may become less if the exponent
is larger.
Pi
•
According to this invention the solution of the present problem is found in the
use of a mono-atomic gas such as mercury for the thermodynamic medium, that
is to say, a gas which during expansion does not generate intra-molecular action
in converting heat into mechanical work. The proportion n of the two specific
heats for mercury is 166, for air 141 and for superheated steam 1301, therefore
n- 1 1
0.00
nnnativals and the formula
From these data it follows that the ratio of expansion for mercury is 15'6
instead of 44 16 for air, or 1185 for gases which have the same proportion as
steam. For the boiling temperature of mercury (357° C.), at which temperature
52% of the heat may, in theory, be converted into mechanical work assuming
the mercury to be in a vapoury state, a ratio of expansion of only 63 is required.
The use of mercury as a thermodynamic medium has still further advantages
as will be clearly understood from the following description which by way of
an example fully explains the principle here involved.
The accompanying drawing shows a vertical section of an apparatus, by which
this invention may be carried into practice.
A represents a turbine the shaft W of which is located in a vacuum chamber M.
The driving medium for the turbine is vapour of mercury which is admitted
through a suitable cock H. The mercury vapour is produced in a vapourizing
coil R capable of yielding to alterations in temperature and located in the down-
wardly arranged flue of a furnace B. The said coil is supplied by opening a
valve F from a pipe J having longitudinal ribs or flanges on its outer side. The
said pipe J is located in a vertical flue 1 and is connected with the turbine
chamber M by a condensing coil E. In order to avoid loss in mercury while
feeding, it is advantageous to surround the pipe by a shell K communicating
with an empty vessel S. A suitable device in the form of a barometer chamber G
for example is also provided for regulating the valve F, said device being arranged
near to and communicating with the upper portion of the vapourizing coil R, in
such way that the intervention of a rod effects the closing of the said valve F
automatically on the pressure rising to 1 atmosphere. The driving power of
the shaft W of the turbine is transmitted to another shaft. 1 through the medium
of suitable gearing T, the said shaft passing through a mercury vessel L provided
with a stuffing box and power being transmitted to said shaft in any suitable
manner.
The operation of the apparatus is as follows:
Mercury having been admitted in a state of fine spray from the tube J through
the valve F it enters the vapourizing coil R where it becomes vapourized, the

page_text: vapour passing through the admission cock H into the turbine A which it drives
as will be hereinafter described. The mercury vapour on leaving the turbine A
passes into the lower portion of the vacuum chamber M and then into the con-
densing coil E, where it is condensed to finally enter the supply tube J. As the
vacuum chamber M of the turbine A communicates with the condensing coil E
which according to the previously assumed calculations has a temperature of
about 27° C., it will be evident that a nearly complete vacuum is created in the
chamber, the pressure being about 1/2000 atm. The vapourizing coil R is
arranged to have a temperature of 627° C., at a point marked C in the drawing
with a pressure of 1 atm. This will effect a ratio of expansion more than that
of 166 as found by the foregoing calculations even when the starting pressure is
below 1 atm. Thus it is possible to utilize a vapourizer without internal pressure
and the vapourizing coil, made preferably of iron or nickel, may be of the thick-
ness of paper and therefore requires very little heating surface.
There is no fear of the poisonous and costly mercury vapour escaping, inasmuch
as the smallest opening in the coil would enable air to enter and so destroy the
vacuum in the turbine chamber. Moreover as the calculated ratio of expansion
(156) is greatly surpassed there is the one advantage, notwithstanding any
resistances arising from the expansion in the turbine, that a final temperature of
27° C. is obtained. The prevailing conditions of temperature are those at which
amalgams decompose and therefore there is no danger of an amalgam being
formed by the mercury vapour and the metal of the vapourizer.
The highly superheated mercury vapour of 627° C., may in comparison with
the ordinary temperature of mercury vapour of 357° C., be considered as a gas
from the speed of which the speed of the mercury jet may be calculated. This
speed must be kept low as compared with air under the same conditions, because
mercury vapour is known to be 685 times heavier than air. Assuming for
instance that the mercury vapour, after it has been allowed to expand so as to
have 1/16th of an atm. pressure, is admitted into the turbine the speed of this
highly superheated gaseous vapour will be about 356 m. per second. Even with
an expansion bringing the pressure nearly down to zero the speed is only 436 m.
As the peripheral speed corresponding to these velocities would be about 200 m.
and as a peripheral speed of 400 m. is obtained already in steam turbines, the
constructive requirements for the arrangement hereinbefore described is quite
within the normal.
The arrangement above set forth requires no feed pump, because of the pressure
in the vapourizer being hardly 1 atm. the feed valve F need only be weighted by
a mercury column of 760 m/m in order to open. However on thermo-dynamic
principles a column of mercury of 4 m. or more is preferably used.
The manner of feeding has also several advantages accruing from the use of
mercury.
In the feeding of steam boilers there are certain defects allowed to exist with
regard to thermodynamical principles due to the use of the feed pump instead of
a Zeuner feed cylinder for adiabatic compression and heating of the mixture
of steam and water derived from the condenser.
==
This defect arises in consequence of the heat in the feeding liquid being often
much below the limit T₂ of temperature; and with superheated steam the evaporat-
ing heat from boiling point to T, must be added. Taking the specific heat as
the same as water 1, a loss of 10% in the first instance occurs with the narrow
limits of temperatures of a steam engine. The feeding of a boiler of 627° C.
with the liquid having a specific heat of 1 would entail a great loss of heat.
The specific heat of mercury is 1/30 and thus the above mentioned defect in the
feeding is reduced to a minimum. Furthermore the heat required for vapourizing
mercury is but small, say 60 to 70 calories as against 540 for steam which of
course from a mechanical point of view is an advantage with regard to the method 5
of superheating. As the heat of liquid mercury is low and while liquid mercury
is a good heat conductor, it is possible to obtain sufficient heat from the flue or

page_text: chimney gases which it is impossible to do when water is used. In the arrange-
ment shown the feeding liquid flows through the aforesaid supply pipe J which
for that purpose is made as long as possible and in which the mercury is heated
either under its own pressure or under the pressure from a feed pump. If the
valve is loaded to equal a column of 4 m. mercury by additional liquid or by
the pressure from a piston, the mercury will still remain liquid at 470° C. corre-
sponding to 5 atm. steam pressure, and the vapourizing heat then applied would
give a thermic useful effect of 60% in the Carnot's cycle. It is quite possible
with the feed pipe J to keep the mercury liquid up to 627° C. and thus spray it
into the vapourizing coil.
The above arrangement given by way of an example has demonstrated the
advantages possessed by the mercury for use as a medium in thermo-dynamic
apparatus, the same advantages being also noticeable in connection with other
arrangements, such as cylinder engines, as will be understood by those skilled
in the art without requiring further description.
The mercury vapour, as herein before described, has merely for its purpose
to serve as an example, it being obvious, that other mono-atomic gases may be
employed in accordance with the leading thermo-dynamic principles of this inven-
tion: the use of mercury vapour however is preferable.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. A thermo-dynamic process for better realizing the cycle of Carnot, con-
sisting in using, as a themo-dynamic medium, a gas having a higher ratio between
the two specific heats than air, such as mercury vapour or other mono-atomic gas,
substantially as described.
2. A method of carrying out the process as set forth in Claim 1, consisting
first in effecting the vapourization of mercury, second in utilizing the vapour to
drive a mechanical element, such as a turbine, third in condensing the vapour
and fourth in heating under pressure the products of condensation and returning
the same to the vapourizer, substantially as described.
3. An apparatus for carrying out the process as set forth in Claims 1 and 2,
consisting in a furnace, a vapourizer located within said furnace, a vacuum chamber
a motor within said chamber actuated by the vapour from the vapourizer, a con-
denser in communication with said vacuum chamber, and a pipe communicating
with the condenser and leading to the vapourizer, substantially as described.
Dated this 19th day of February 1900.