Improvements in Apparatus for Superheating Steam.
Year: 1891

page_text: te of Application, 2nd Apr., 1891-Accepted, 9th May, 1891
COMPLETE SPECIFICATION.
Improvements in Apparatus for Superheating Steam.
I, WILHELM SCHMIDT of 8, Plantagen Strasse, Halberstadt, in the German
Empire, Engineer, 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 :-
Many and long trials have led to the conviction, that superheating steam for
steam-engines will only prove an essential success, when the steam be heated to
300° and above. But in making use of such high temperature many defects may
arise thereof. The heater itself may be severely injured by becoming red-hot and
even may be burnt and on the other hand diffusion and a great waste of heat takes
place in apparatus of the common type. I have therefore found it necessary to
arrange in advance of the main heating-apparatus a fore-superheater, in which the
steam shall be thoroughly dried and which absorbs the first and greatest heat
coming directly from the furnace and thus renders the blasts harmless for the main-
superheater which may be acting on the principle of counter-draft.
It is evident
that it will never do to allow the blast to flow reverse to the direction of the steam
the whole length of the heater, since in this case the height of the temperature is
limited by the apparatus getting red-hot, and then this highest temperature will not
only have to heat the steam but also to evaporate the water contained therein.
The evaporation will absorb an amount of the heat applied and not enough remains
for heating the steam to the requisite temperature.
It is a well-known fact, that any seether, evaporating-pan, superheater, or the
like, will stand by far higher a temperature as long as there is water yet contained
in the steam. Because, since the evaporation consumes the heat rapidly and since
the temperature of steam cannot rise during the vaporisation, the fall of temperature
will remain constant until the evaporation is completed. The tubes will not become
red-hot even if the blasts have a temperature of 700° and when the moisture of the
steam is evaporated the blasts will be cooled down to such a temperature as every
pan or tube containing dry steam will bear. The heat being reduced to about 400°
may now be applied solely to superheat the steam without fear of destroying the
heater-tubes and without fear of diffusion. The super-heating will be vigorous and
energetic, by far more so, as is the case in superheating-apparatus working merely
on the principle of counter-drafts and which, as has been mentioned above, admit no
higher temperature.
In carrying my invention into effect I subdivide the complete apparatus into two
main-parts, in such a manner that in between the tubes, receiving the steam directly
from the boiler and forming the fore-superheater, the hottest blasts shall circulate,
and hereafter in the main-superheater the steam will flow in a direction reverse to
that of the blasts, thus permitting gases of extremely high temperature to be made
use of and the fall of the same will be such, as to permit a complete utilization of
the heat applied.
In order to make my invention more clear, I refer to the accompanying drawing,
in which similar letters denote similar parts throughout the several views, and in
which :-
Fig. 1 illustrates a superheater of a most simple construction.
tt tare tubes inside of which the steam blows through and which have the
shape of an U. They are arranged in a chamber divided into two by the plate s.
The entrance of the steam is at a and is indicated by the arrows; the blasts coming
from the furnace will first circulate round that part t of the tube which is nearest a,

page_text: thus for a short distance the blasts and the steam flow in the same direction, but
inside of the chamber the currents of the two are reverse to each other. The
exit of the steam is at n and that of the blasts at m.
It need scarcely be explained that the wet steam absorbing the first and greatest
heat while passing thus being kept cool, will rapidly dry. The blasts, being also
cooled down as quickly, will now enter the chamber u and circulate here round the
tubes 2 on the principle of counter-drafts thus superheating the steam in the most
effective manner.
Fig. 2 is a modification of the first. Here the chamber u is provided with a
partition into which the tubes and are led thus obviating the semi-circular
curve, and forming an intermediate chamber between the two legs of the U.
Fig. 3 shows an arrangement similar to that of the Field-boiler-system in com-
bination with a vertical steam-boiler A. The blasts enter the chamber R at c, and
into the smaller chamber d the steam enters at a'. The tubes e being closed on top
open out below into the same chamber d. The steam will rise inside of these tubes
and be led off into the chamber by the central-tubes. From the chamber d'
the steam blows into the pipe g being the first of the system W in the chamber R',
which it leaves at 7. Inside of the chamber R the blasts are guided by the
midfeathers to firstly circulate between the tubes on the left-hand side and after
this between those on the right, then they are led into the chamber R¹ by the
pipe, flow here along the outside of the tubes W, reverse to the direction of the
steam, guided by the midfeather-plates s¹ and finally leave the chamber at 1.
In the apparatus illustrated in Figs. 4 & 5, provisions are made, to force the
blasts to stream over the tubes only partly according to the consumption.
Fig. 4 is merely a modification of Fig. 3, in which the midfeather s2 is provided
below with a hole m', which will allow part of the blasts to go directly from the
left hand side into the right, without having to take the longer way over the
plate s². In the ordinary course of work the gases will take the shorter way
through this same hole, however, when it is required to superheat especial large
quantities of steam, the firing would be enforced and the blasts thereby becoming
too great or powerful to go through the said hole (the same being too small
therefor) the greater part of said blast would take the longer route and circulate
between the pipes for the whole of their length. Of course the increase of energy
developed in superheating the steam will be proportional to that of the firing.
The apparatus illustrated in Fig. 5 is provided with a damper or slide-valve S to
regulate the access of the blasts in opening or covering, partly or fully the
apertures o o¹³. The same may be actuated by hand outside of the apparatus.
In our figure the damper is shown in its highest position, thus permitting the blasts
merely to enter by o2, which shall be of sufficient size requisite for the ordinary run
of work. This arrangement permits a precise and handy regulation of surface
presented unto the blasts. I may also replace the slide by doors or clack-valves,
also regulated from outside.
The
It is obvious that frequently these regulating devices will be necessary.
greater the quantity of steam, or mixture of steam and air is, the greater is the
quantity of water contained therein, which of course requires a proportional amount
of heat for evaporation, and the stronger the firing the more surface may be offered
to the blasts. On the other hand if there be only a small quantity of water to be
evaporated, the firing has to be diminished in order to avoid a burning of the pipes,
and only a smaller part of the existing surface may be offered to the blasts.
I particularly point out, that my invention may be made use of for superheating
a mixture of steam and air as well as steam alone.
.
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 An annostus for surenheatin
aun dansisting of a forerunarheater receiving

page_text: the direct steam and blasts for sake of drying the first, and a main-superheater
through which latter the steam blows in a direction reverse to that of the heating
gases, as described.
2. In an apparatus for superheating steam, a main superheater, through which
the steam blows in a direction reverse to that of the heating blasts, in combination
with a fore-superheater, both chambers being separated by a partition-plate », for
the purpose set forth.
3. In an apparatus for superheating steam, a main superheater through which
the steam blows in a direction reverse to that of the heating blasts, in combination
with a fore-superheater being provided with two or more inlets for the purpose of
varying the heating surface according to the consume of gases, as described.
4. In an apparatus for superheating steam. a main-superheater through which
the steam blows in a direction reverse to that of the heating blasts, in combination
with a fore-superheater being provided with two or more inlets and regulating
valves, as for the purpose set forth.
אהנה
*1100
WILHELM SCHMIDT.
By Geo. Thos. Hyde,
4, Moorfields, E.C., Agent for Applicant.
WILHELM SCHMIDT.
By Geo. Thos. Hyde,
4, Moorfields, E.C., Agent for Applicant.