Improvements in the Generation of Steam and in the Apparatus therefor.
Year: 1893

page_text: Date of Application, 10th Jan., 1893-Accepted, 13th May, 1893
COMPLETE SPECIFICATION.
Improvements in the Generation of Steam and in the Apparatus
therefor.
I, WILHELM SCHMIDT of Villa Henkel, Wilhelmshöhe near Cassel, in the
Province of Hesse-Nassau, German Empire, Civil Engineer do hereby declare the
nature of my said 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 a new or improved method of generating steam and is
distinguished by the advantages first of reducing to a minimum the formation of
boiler scale and secondly of permitting to construct horizontal boilers with spiral.
tubes, which was not possible hitherto.
My improved method consists in generating a part of the steam in a first small
boiler heated direct by a furnace, and in generating the other part of the steam by
causing the steam evolved in the first boiler to enter a second boiler formed by
tubes wound around in spiral, this first steam being also made to take up water
on its way and to carry it along to the second boiler where this water is vaporized.
In the accompanying drawings
Fig. 1 is a sectional elevation of my improved steam generating apparatus, with
an upright tubular boiler.
Fig. 2 is a longitudinal sectional elevation of my improved apparatus with a
horizontal tubular boiler, and
Fig. 3 is an end elevation partly in section of the same.
Similar letters refer to similar parts throughout the different figures.
In carrying out my invention as illustrated by Fig. 11 employ a small boiler a
in which the water to be vaporized is contained. The steam evolved in this boiler
is conveyed to the spiral tubes cele² by the pipe b, and on its way to said tubes is
made to pass through a nozzle d, and thus to drive water out of boiler a, said
water flowing out through pipe e. In consequence thereof a mixture of steam and
water will enter the spiral tubes c c¹ c².
If the amount of water carried away by the steam is such as may be brought to
perfect vaporization by the steam at the temperature which the latter has required,
the mixture of water and steam entering the spiral tubes will gradually be changed
more and more into steam, so that the steam conveyed to the engine through the
pipe (shown in dotted lines) will be pure steam without any particles of water
suspended therein.
The quantity of steam issuing from boiler a can be regulated by means of the
screw 9 which is adapted to lessen or to increase the area of the nozzle d, through
which steam may pass ; similarly the amount of water fed to the nozzle to be
carried away by the steam may be varied by turning the cock /.
Now it will be obvious that if only such a quantity of water is carried away by
the steam as can be gradually vaporized by the steam in consequence of its high
temperature, the volume of steam will be considerably larger than that of water
and the spiral tubes e c'e² might be subjected to a too excessive heating as their
walls are cooled almost only by the steam.
In order to obviate this the steam may be caused to carry along with it a larger
quantity of water than it is capable of vaporizing. In this case the construction of
the apparatus must be somewhat altered in order to separate this additional water
from the steam and to convey it back to the boiler a.
For this purpose I do not lead the mixture of water and steam having passed
through the spiral tubes cc¹ c² directly to the engine through the pipe, but cause
said mixture to travel through pipe f¹ into a trap k which is constructed in usual
manner and where the water collects at the bottom and is thus separated from the
The latter leaves the trap by the tube whence it is conveyed to the
same.

page_text: engine. The water collecting in the trap k is pumped back through pipe 7 by
means of the pump m.
C
By this arrangement the walls of the spiral tubes c¹² are effectively cooled by
the water conveyed through the same together with the steam.
I also insert into the tube for a metallic thermometer which allows the
temperature of the steam or the mixture of steam and water to be ascertained
whereby the generation of steam may be readily passed, and if necessary the right
semperature is obtained by turning the cock or the screw .
Experiments which I have made with highly heated steam have yielded the
result, that even in superheated steam water may be contained in the form of
suspended particles and I am enabled to ascertain the preparation of such suspended
water by simply determining the temperature of the mixture as I have found, that
to each temperature corresponds a definite proportion of suspended water.
I wish to point out that it is not necessary to provide a mechanical contrivance
such as the nozzle or injector for carrying the water along by the steam, but this
may also be effected by the simple means which are shown in dotted lines on the
left of Fig. 1. The steam in this case leaves the boiler a by the pipe n at the
upper end of which the diameter for the passage of steam is reduced.
By this means I cause the steam jet to be contracted to a reduced cross-sectional
area, so that the pressure of steam is greater before the reduced portion than after
the same; in consequence thereof the pressure in the small chamber p will be
smaller than in the boiler a and as the water in the boiler is subjected to a stronger
pressure, it will be driven into the chamber p through the pipe and the steam
passing through the chamber p will carry this water further through the spiral
tubes. The amount of water which is thus driven out of the boiler can be regulated
by means of the cock r.
It will be readily understood that the formation of incrustations or boiler scale
is practically impossible in the spiral tubes ce cas the proportion of non vaporized
water carried along with the steam is quite small, and as the mixture of steam and
water is propelled through the spiral tubes by the full pressure of steam in boiler a;
thus the compounds capable of forming incrustations will have no time to be
deposited on the walls of the tubes.
If the fire in the furnace is extinguished, only pure steam ummixed with water
will be conveyed through the spiral tubes as the nozzle d is placed above the level
of water in boiler a. Thus it will be seen that each time the fire is extinguished,
the spiral tubes cc 2 will be cleaned by pure steam. A formation of boiler scale
cannot ensue even when the tubes get cool and cause the steam to be condensed as
this condensation water is perfectly pure.
The formation of the boiler scale will only occur in the small boiler a but as this
boiler is of small dimensions and of a simple construction, its inner walls are easily
accessible and may be readily cleaned from incrustations.
In Figs. 2 & 3 I have shown the application of my improved method to
horizontal boilers; I have also shown in these figures that, even when the steam is
caused to carry along with it, more water than it can vaporize (which I prefer to
do) a pump for driving the superfluous water back into the boiler is not necessary.
a is the first boiler containing the water and the steam evolved from the same
rises in the pipe to the nozzle of any injector. In this case the water carried
away with the steam is not taken from the boiler a' but from a special water
reservoirt by means of a tube s. The pressure in reservoir t must be somewhat
less than that in boiler a' in order that the steam passing through a nozzle d' may
be able to draw off water from reservoir t through pipe s. This water gets mixed
to the steam and the mixture is conveyed to the spiral tubes c3 c c which in this
case have been arranged in such manner that they form a cylinder, the axis of
which lies horizontal. The mixture of water and steam which is heated in the
spiral tubes by the furnace, enters the reservoir by the pipe i¹, and the water is
separated in this reservoir from the steam which latter is conveyed to the engine
through the socket v.

page_text: I wish especially to point out this peculiarity which constitutes a great advantage
of my invention viz. that the spiral tubes may be arranged so as to form a
horizontal cylinder whereas hitherto such an arrangement could not be employed
practically owing to the water collecting at the bottom of the spiral tubes and
causing the same to be shaken during the passage of steam or even obstructing the
same entirely.
In my improved method these inconveniences cannot occur as the proportion of
water carried away with the steam is quite small and as this water moves along
with considerable speed.
I do not confine myself to the exact form of construction as shown in the
drawings but the same may be modified without departing from the nature of my
invention, for instance I may employ other forms of tubes instead of spiral tubes
and I may also substitute a tubular boiler for the first boiler a (Fig. 1) or a¹
(Fig. 2).
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 :-
1. The herein described method of generating steam, consisting in a generating
part of the steam directly in a first boiler heated by a furnace, and the other part
of the steam in a second boiler, preferably formed of tubes or spirals, by causing
the water necessary for the generation of this second portion of the steam to be
carried along by the steam generated in the first boiler whereby the second boiler
is cooled at the same time, for the purpose set forth.
2. An apparatus for performing the method claimed under head 1: consisting of
two boilers combined in such a manner that the steam generated in the first boiler
effects the cooling of the second boiler formed of tubes or spirals carrying water
along with it, the quantity of this water being either only such, as is necessary for
the generation of steam or somewhat in excess thereof, substantially and for the
purpose set forth.
3. In the combination of the parts claimed under head 2: the insertion of a water
reservoir in which a suitable pressure is maintained, between the two boilers, the
water carried along by the steam being taken out of this reservoir and conveyed
back into the same, for the purpose set forth.
4. In the combination of the parts claimed under head 2: providing a trap
through which the mixture of steam and water travels after leaving the second
boiler and out of which the separated superfluous water is conveyed back to the
first boiler by means of a pump, for the purpose set forth.
5. In the combination of the parts claimed under head 2 and especially in the
arrangement as claimed under head 3, providing an ejector for drawing the water
out of the first boiler or out of the separate water reservoir, for the purpose set
forth.
6. In the combination of the parts claimed under head 1, inserting, in the second
boiler or in the pipe leading therefrom to the engine, an indicator, such as a
thermometer or the like, by means of which the temperature of the steam or
mixture of steam and water may be measured, for the purpose set forth.
T
1002
WILHELM SCHMIDT.
Geo. H. Rayner,
37, Chancery Lane, London, W.C., Agent for the Applicant.