Improvements in Steam Superheaters.
Year: 1899

page_text: Improvements in Steam Superheaters.
I, CARL JACOBI, of 14, König Strasse, Wannsee, near Berlin, in the Empire of
Germany, Engineer, do hereby declare the nature of this invention to be as
follows:-
The steam superheating apparatuses hitherto employed as proved by numerous
tests under quite similar circumstances as regards construction, size and insulation
of the apparatus and also as regards furnace gases, show losses of temperature
in the superheater tubes, which amount to about 4° to 5° and still more per
metre of the steam tube run with superheated steam of about 330° C. In practice
a diminution of temperature may be described as normal which amounts on an
average to about 1° per metre of steam tube run. Practice shows further the
circumstance that two similar apparatuses working in conjunction exhibit con-
siderable differences in the temperature of the steam already at its entrance into
the common steam pipe, and the necessary superheating is only insufficiently
attained in spite of sufficiently great heating surfaces. These appearances can
therefore have their ground only in the fact that the superheated steam has
not an equal temperature in all parts, but that quantities of steam exist which,
when the steam leaves the apparatus, cause a loss of temperature.
This loss of temperature is necessarily to be ascribed to displacements in the
zones of temperature of the furnace gases surrounding the superheater tubes, and
these displacements appear more or less strongly according to the kind and
position of the flues and the condition of the same. The heating surface of the
superheater is therefore only partially encountered by the furnace gases which
have the necessary temperature and which are intended to encounter the whole
heating surface.
In order therefore to avoid such loss of temperature a thorough mixture of
the quantities of steam contained in the pipes or tubes of the superheater appara-
tus must take place, but the superheating apparatuses hitherto employed are in-
sufficient and unsuitable for such a mixing of the steam.
In the apparatuses hitherto employed the steam to be superheated flows through
the superheater tubes in either a similar or opposite direction or even in both
a similar and opposite direction, to that of the heating fire gases. By this means
a gradually increased superheating may indeed be obtained without however the
separate quantities of steam being mixed in each case with one another in such
a way that the steam on quitting the superheater has in all its molecules the same
temperature.
The abnormal drop in the temperature as well as the insufficient superheating
even with sufficiently highly heated furnace gases and large heating surfaces
is therefore to be ascribed to the fact that the superheater has delivered super-
heated steam of different degrees.
In order to avoid all these losses of temperature of the steam in the super-
heater apparatus, as well as on leaving the same, the steam is conveyed through

page_text: the series of heating tubes according to the position of the zones of temperature
either (in combination with a similar or opposite flow to the gases) in a simple
alternating manner, or (if in pure alternating flow) in multiple alternating
manner, that is to say, in a current in which the steam is forced to traverse the
full height, breadth and also depth of the heating zones, that is to say, from a
less heated zone into a hotter one, and vice versa from a hotter zone into a less
hot one, and then again into a hotter temperature zone in order to finally reach
the engine cylinders or like points of utilisation from the apparatus fully mixed
and with an even temperature of superheating,
The arrangement supplies with absolute security a mixture of the formerly
irregularly superheated steam and further a steam superheated through and
through in the apparatus in all parts equally with the highest utilization of
the furnace gases. If it were desired to employ the pure alternating flow prin-
ciple no inconsiderable losses of temperature would result in spite of the good
mixture of the steam, as the steam alternates between the hottest and coldest zones
of the furnace gases.
What heat therefore the furnace gases on the one hand
impart to the steam is on the other hand again absorbed from the steam by the
furnace gases at the zone where the furnace gases are coldest.
A form of construction for alternating flow in combination with a flow in the
opposite direction to that of the gases will now be described.
Above and outside the wall of the furnace flue there are provided two inlet
pipes connected with a common feed pipe, and below two current diverting pipes
which are connected with the inlet pipes by means of alternating sinuous or
zigzag pipes serving for the superheating, and beneath the diverting pipe a
discharge pipe is arranged, which communicates with the lower chamber of the
diverting pipe by means of other superheating tubes.
The two sets of superheating tubes are connected with the inlet diverting and
discharge pipes by means of easily accessible flanges.
The upper part of the alternating pipes lies for example in the upper zone
of the heating zones formed by the furnace gases, that is to say in a usually less
hot zone, the steam diverting pipe lies in a usually hotter (lower) zone, and the
fire gases play round these pipes.
Each inlet pipe is divided by transverse partitions into a series of chambers.
Each diverting pipe is divided by means of a longitudinal partition into an upper
compartment and a lower compartment, the first compartment being again divided
by transverse partitions, into chambers.
The alternating pipes connect the chambers of the inlet pipes with the
chambers of the diverting pipes in such a way that the steam from each inlet
pipe passes down through one alternating pipe to one chamber of the diverting
pipe, and then up from the said chamber through another alternating pipe to the
next chamber of the inlet pipe and from there down through another alternating
pipe to the next chamber of the diverting pipe and so forth.
These alternating pipes extend in planes at right angles to the inlet and divert-
ing pipes in a spiral or sinuous form in order to afford as large as possible a heat-
ing surface to the furnace gases passing over them. From the last chamber of
the inlet pipe the steam after it has traversed the full height and width of the
heating zones, that is to say, the different zomes of temperature, and thereby is
preliminarily dried and thoroughly mixed, passes through an alternating pipe
into the larger bottom chamber of the diverting pipe. This chamber is connected
with the discharge pipe by pipes inserted in parallel, through which discharge
pipe the steam after quitting the apparatus reaches the cylinder of the steam
engine with an equal temperature of superheating and without loss of tem-
perature.
In order to obtain a larger total section of passage, instead of the two systems
of alternating pipes hereinbefore described, a larger number of the same may be
connected with the common feed pipe. Instead of the diverting pipe with alter-
nating chambers and large bottom chamber a separate tube with alternating

page_text: chambers may be employed and another separate tube inserted, which forms the
larger or carrying off chamber.
An example for double purely alternating flow for superheating will now be
described. The inlet pipe here lies in the colder zone diverting the pipe in
the median hot zone and the discharge pipe in the hottest zone. The said pipes
are all connected with one another by means of alternating pipes. This arrange-
ment affords slight superheating as the steam passes only in the last part of its
course through the hottest zone.
Finally in another example the alternating flow may be combined with similar
direction of flow to that of the gases. The steam in such case enters the inlet
pipe, passes through alternating pipes, reaches the under chamber of the diverting
pipe and is conveyed from the latter through similar current pipes to the dis-
charge pipe.
In this case therefore the steam is preliminarily dried by alternating flow
and thoroughly mixed, so that abnormal drops in temperature in the steam pipe
of the superheated steam need not be feared.
Of course the reverse may easily be attained, namely the preliminary drying
by similar flow (or even opposite flow to that of the gases) and the actual super-
heating by alternating flow. It only requires for this a suitable reversal of the
arrangement.
Dated this 23rd day of December 1899.
W. P. THOMPSON & Co..
Of 6, Lord Street, Liverpool,
Agents for the Applicant.
Improvements in Dream Supermeaters.
i
I, CARL JACOBI, Engineer, of 14, Königstrasse, Wannsee, near Berlin, in the
Empire of Germany, 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 :---
Steam superheating apparatus as hitherto used shows as has been confirmed by
numerous tests, that under exactly similar circumstances as regards management
size and position of apparatus and also as regards the supply of furnace gases
there is a considerable loss or variation of temperature in the tubes of the super-
heater which loss can easily be measured by the temperature of the superheated
steam in the pipes from the superheater and amounts to 4° or 5° C. per meter
of length of the superheater tubes or even more. As a proper fall in temperature
of superheated steam at about 30° C. it is usual in practice to allow 1° per
meter of length of the steam piping. Experience also proves the fact that with
two similar sets of apparatus working in conjunction notable differences of tem-
perature become apparent immediately on the entrance of the steam into the
common steam pipe and the requisite amount of superheating is not obtained
satisfactorily in spite of there being a quite adequate extent of heating surface.
This phenomenon can only have its source in the fact that the superheated steam
has not the same temperature in all parts, but that rather there are portions
of steam present which when the steam leaves the apparatus cause the loss of
temperature.
This loss of temperature must of necessity be attributed to the shifting of the
zones of temperature of the furnace gases passing over the surface of the super-
heater tubes and this shifting takes place more or less vigorously according to

page_text: the arrangement and position of the currents of the furnace gases and the way in
which they are sustained. The heating surface of the superheater is therefore
only partially brought into contact with the furnace gases which have the
requisite temperature and which ought to come into contact with the whole of
the heating surface. In order therefore to prevent such loss of temperature a
thorough mixing of the portions of steam contained in the superheating apparatus
must be effected but for such mixing the superheating apparatus hitherto used are
insufficient and unsuitable. In the apparatus hitherto used the steam to be
superheated flows through the superheater tubes in the same or in the contrary
direction or sometimes in both the same and the contrary direction as the current
of furnace gases which heat it. In this way a gradually increasing amount of
superheating can perhaps be attained without the different portions of steam being
in every case so mixed together, that on leaving the superheater there is the same
température in all the molecules of steam.
· The abnormal fall of temperature as well as the insufficiency of the superheat-
ing although with abundance of highly heated furnace gases and large heating
surface are to be attributed to the fact that the superheater has produced steam
which is superheated to different degrees.
In order to prevent all these losses of temperature of the steam in the superheat-
ing apparatus as well as after leaving it the steam is led through a system of
heating tubes which, according to the positions of the zones of temperature are
combined so as to give the steam a direction either with or contrary to that of
the furnace gases, along with either a simple zig-zag course or a repeated zig-zag
course, that is, in a stream which compels the steam to pass through the entire
height breadth and depth of the heated zones for example out of a zone which is
less heated into one which is more heated and vice versa out of a hotter zone into
one that is less hot and then again back into one at a higher temperature so that
it ultimately leaves the apparatus thoroughly mixed and with a uniform super-
heat temperature to pass on to the cylinders of the engine or for any other
purpose. This arrangement supplies with absolute certainty a mixture of the
portions of steam which would otherwise be unequally superheated and further
the steam is superheated uniformly and thoroughly in all parts of the apparatus
without waste of the furnace gases.
If use is made simply of the zig-zag arrangement, there would result also in
this case in spite of the thorough mixing of the steam a not inconsiderable loss
of temperature because the steam passes backwards and forwards between the
hottest and coldest zones of the furnace gases; what heat the furnace gases give
up in one place to the steam will conversely in another place, that is in a colder
zone of the furnace gas, be again withdrawn from the steam by the furnace gases.
An example of the construction for a zig-zag course combined with a course in
the opposite direction to the furnace gases is shown in Figs. 1, 2 and 3,-an end
view, a side view, and a ground plan respectively.
By the dotted lines w the external side wall of the flue is indicated. Outside
this at the top in the example illustrated there are two entrance tubes « con-
nected to a common supply tube f, Fig. 3; further down there are two transfer
tubes which are connected with the tubes a by the zig-zag tubes d in which the
steam is superheated and under the tube is placed the exit tube which
communicates by the superheating tubes e with the lower compartment of the
tube b. The superheating tubes and are attached to the tubes a, b and c
by easily accessible flanges.
The upper part of the zig-zag tubes & lies in the example here illustrated in
the upper zone of the zones..y = formed by the furnace gases and thus in the
zone which is in general least heated. The steam transfer tube b is situated in
a zone which is usually hotter. The furnace gases pass over the tubes d
"ande in the direction of the arrow Fig. 1.
Each of the tubes a is divided into compartments by transverse partitions "a¹
Each of the transfer tubes is divided by a longitudinal partition

page_text: into an upper portion and a lower compartment 6. The first portion is divided
by transverse partitions into compartiments 1 b².
The zig-zag tubes & connect the compartments a² of the entrance tubes a
with the compartments 62. of the transfer tube so that the steam out of
each of the tubes a flows through a tube d to the compartment out of the
compartment 61 of each of the tubes through a tube to the compartment al,
from a through a tube d into 2, out of 2 into a², and so on as is indicated in
Fig. 2 by the full-lined arrows.
These tubes take a winding course as is shown in Fig. 1, in planes which are
supposed to be vertical and to stand across the tubes and b in order to offer to
the impinging furnace gases as great a heating surface as possible, After the
steam has traversed the entire height and breadth of the heated zones and been
exposed to the various temperatures so as to be well dried and completely mixed,
it passes out of the last compartment of the tube a through a tube d into a larger
compartment of the transfer tube 6. This compartment is connected by
intervening parallel tubes g to the exit tube through which the steam escapes
from the apparatus with a uniform temperature of superheat and without loss of
temperature, to the cylinder of the steam engine. In order to obtain a greater
sectional area of tubes one may use instead of the two systems of zig-zag
tubes a, d, b here illustrated, a larger number of them connected to the common
supply tube f.
.
and
Instead of the transfer tube with alternating compartments
exit chamber a special tube might be used with alternating compartments and
a separate tube which constitutes the exit chamber.
Fig. 4 shows an example for heating with a simple zig-zag course.
entrance tube is here placed in the colder zone, the transfer tube
moderately heated zone y, and the outlet tube in the hottest zone ..
む
The
in the
By the zig-
zag tubes d, a is connected with as well as b with c. This arrangement produces
a high degree of superheating since the steam comes into the hottest zone only in
the last part of its course.
Finally Figs. 5 and 6 show by an end view and a side view respectively an
example in which a zig-zag course is combined with one in the direction of that
of the furnace gases.
The steam enters into the tube, traverses the zig-zag tube d, enters the lower
compartment of the lower transfer tube and is conducted out of the latter by
tubes in the same direction as the furnace gases to the outlet tube c.
Thus the steam is here dried by the zig-zag course and thoroughly mixed so
that abnormal falls of temperature of the superheated steam in the steam supply
pipes need not be feared.
Of course the converse of this may also be arranged, that is the drying may be
effected by a course in the same direction as the furnace gases (or also in the
opposite direction), and the real superheating of the steam by the zig-zag course.
It is only needful for this purpose to reverse the order of the arrangement.
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 steam superheater characterised by having in one or more portions of the
hot flue, tubes through which the steam to be superheated passes, so that in one
portion of the flue some tubes d which conduct the steam in the opposite direc-
tion to the furnace gases alternate with tubes & which conduct the steam in
the same direction placed side by side and in another portion of the flue the
course of the steam is partly in the same direction as and partly in the opposite
direction to the furnace gases in such a way that the steam arrives alternately
now from a colder to a hotter and again from a hotter to a colder zone for the
purpose of bringing it in all its parts to a uniform final temperature and having
it thoroughly mixed.

page_text: 2. A steam superheater having the several parts constructed and arranged in
combination substantially as and for the purpose described and shown in either of
the figs. of the drawings.
Dated this 19th day of September 1900.
WM. P. THOMPSON & Co.,
Manchester, Liverpool, London, & Birmingham,
Patent Agents.