An Improved Process of and Means for Heating and Evaporating Liquids, also applicable to the Heating of Vapours and Gases, Steam Raising and Superheating.
Year: 1898

page_text: PROVISIONAL
SPECIFICATION.
An Improved Process of and Means for Heating and Evaporating
Liquids, also applicable to the Heating of Vapours and Gases,
Steam Raising and Superheating.
We, ADOLF GEORG HOFFMANN, of Johanniterstrasse 2, Engineer, and AUGUST
SCHWARZ, of 59, Ritterstrasse, Merchant, both of Berlin, in the Kingdom of
Prussia, Empire of Germany, do hereby declare the nature of this invention to be as
follows:-
The means for and mode of heating and evaporating liquids, heating vapours
and gases, as hitherto used, are still imperfect, for the reason—as experiments have
proved that the areas heated by the fire-gases and the areas that are in contact
with the liquids are not in such proportion to each other as to be able to obtain
the highest useful effect of the fire gases.
No mode of heating, heretofore carried out, enables, as the present invention
does, to really utilize the heat introduced to the areas or surfaces heated by the
fire or other heating gases in the time in which the said heat is produced; that is
to say, so that all the heat produced is almost in statu nascendi led over to the
liquid, or gases, whereby the heating surfaces uninterruptedly receive new
heating effects.
This, however, is obtained by arranging within a tubular vessel a system of
narrow spaces or chambers (cells) independent one from the other, in such a manner
that the walls of each space are directly and conductively combined with the
source of heat, and that a channel common to all said spaces communicates with
them in such a manner as to lead off the vapours or heated gases at the time of
their development or formation, while the remaining liquid is retained in the
spaces or cells and is so prevented from being swept away by the vapours or
gases.
Said narrow spaces or cells may be formed by inserting suitable plates, discs,
spirally wound strips of sheet metal, or the like, in the tubular vessel, the outer
Burface of which is subjected to the heat, care being taken that these inserted
bodies always maintain an intimate and extended contact with the heated surface,
so as to constitute one single metallic piece with the surrounding vessel, whereby
the heated surface of the same is considerably enlarged. Thus the what we may
call "inner heating surface" formed by the walls of the narrow spaces enclosing
the liquid to be treated, is divided into a great number of little cells
communicating with each other and each of which is conductively connected with
the heat receiving surface of the vessel.
The vessel preferably may consist of a tube, within which the narrow spaces or
cells are formed by superposed plates with projecting or turned up edges determining
the distances between the plates. The diameter of said edges or borders
corresponds to that of the enclosing tube, so that on inserting the plates, in the
tube, a certain pressure is to be exerted, in order to maintain a good contact
between the corresponding surfaces of the plates and the tube. The plates will

page_text: in this way, in consequence of the conductivity of the metal, receive the same
temperature as the surrounding vessel when this is heated by an external source of
heat, and will thus enable the heat to be immediately transmitted to the fluid
contained in the spaces or cells.
The height of the above mentioned edges or borders is so small as to form
capillary cells in the whole length of the tube, whereby any spheroidal condition of
the liquid conducted in the cells when heated is prevented.
To secure a good contact of the plates amongst themselves and of the plates with
the enclosing vessel, contrivances such as screw-plates are provided at the ends of
the tubular vessel or vessels.
Apertures are provided in the plates, for the purposes of feeding liquid or another
medium to be heated into the cells, of maintaining a certain circulation between
each cell and of leading off the vapours or gases produced or heated therein. The
plates may be made of a conical shape whereby they impart to the arising vapours
an upward direction and offer better means for preventing bubbles of steam from
remaining within the cells than in case of dish-like shaped cells.
In a modified form of our invention the plates are so arranged as to surround the
tube and the heating medium is conducted through the interior of the tubes, instead
of acting on the external surface of the same.
When several tubular vessels are combined so as to form a boiler or superheating
apparatus one vessel of greater diameter containing several tubes of a kind as
described above - conically shaped plates may be employed in combination with
some of the tubes and dish-like plates with others, but it may be left to the
constructor to use plates of any suitable form. The spaces remaining between the
columns of plates, when a number of tubular vessels are combined to form a boiler,
serve as channels for leading off the produced steam or gases.
It is a matter of course that boilers, superheaters or the like, arranged according
to this invention, are provided with the requisite accessories, such as feed and
discharge pipes, safety valves, pressure gauges, steam collector and so on, parts
which are well known to those skilled in the art.
For describing the operation of our apparatus for heating and evaporating liquids
or for heating vapours or gases it may be supposed that the tubular vessel is filled
for instance with water or another liquid and that a heating medium acts upon the
one surface of the same vessel. From said surface the heat taken up from the fire
gases or other heating agent is immediately conducted to the other surface and the
edges of the plates being in contact with this surface, to the plates themselves and
to the liquid enclosed in or surrounded by the cells formed by said plates. In
consequence thereof an extremely quick and vigorous circulation takes place within
said narrow spaces or cells, and with a sufficient amount of heat an instantaneous
evaporation of the liquid is produced. The steam enters the main channel formed
by the apertures or holes of the plates and is conducted to the steam collector, thus
enabling fresh liquid to enter the cells of the apparatus. The heat required to
evaporate instantaneously this new charge of liquid, is again furnished by the tube
or tubes and by this constant demand of new heat, the heat supplied to the tubes is
so fully utilised as to exclude the surfaces receiving the first heat to get super-
heated. Moreover owing to the capillary arrangement of the cells no spheroidical
condition of the liquid can take place even if a very great amount of heat is supplied
to the tubes.
Any parts of the liquid that may be swept away by the vapours settle down on
the following plates or fall back into the cells and are retained there, by adhesion,
until the heat exerted has brought them to evaporation.
In exactly the same manner wet vapours are treated with the view of drying
them. This is effected quickly and completely within the cells of my apparatus,
which is also applicable for superheating steam or gases.
The quick transmission of the heat of every temperature prevents the walls of
the superheater, that are directly exposed to the heating agent, from glowing or
burning.

page_text: An essential merit of my invention consists in the possibility of constructing
steam boilers which, owing to the immediate utilisation of all the heat taken up
from the heating agent, are of extremely compendious form. The rapid circulation
of the liquid within the cells and the quick evaporation of said liquid prevent any
foreign material suspended in the liquid from depositing in the cells and from
leading to incrustation such material is swept away by the steam leaving the cells
and settles down in the steam receiver, from whence it can easily be removed.
In consequence of the positive conduction of the heat taken up by the tube or
tubes to the liquid contained in the cells, and owing to the small amount of super-
heated liquid within the apparatus, constructed according to our invention, any
danger of explosion is completely excluded.
As compared with the arrangements at present in use, an apparatus constructed
according to our invention presents the advantage of being for equal capacity of
nuch smaller size and less weight, of warranting a great economy in fuel and of
requiring much less time for getting steam.
An Improved Process of and Means for Heating and Evaporating
Liquids, also applicable to the Heating of Vapours and Gases,
Steam Raising and Superheating.
We, ADOLF GEORG HOFFMANN, of 2, Johanniterstrasse, Engineer, and AUGUST
SCHWARZ, of 59, Ritterstrasse, Merchant, both of 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: —
The means for and mode of heating and evaporating liquids, heating vapours
and gases, as hitherto used, are still imperfect, for the reason-as experiments
have proved that the areas heated by the fire-gases and the areas that are in
contact with the liquids are not in such proportion to each other as to be able to
obtain the highest useful effect of the fire gases.
No mode of heating, heretofore carried out, enables, as the present invention
does, to really utilize the heat introduced to the areas or surfaces heated by the fire
or other heating gases in the time in which the said heat is produced; that is to
say so that all the heat produced is almost in statu nascendi led over to the liquid,
or gases, whereby the heating surfaces uninterruptediy receive new heating
effects.
To carry out our invention, we arrange within a tubular vessel a system of
narrow spaces or chambers (cells) independent one from the other, in such a
manuer, that the walls of each space are directly and conductively combined with
the source of heat, and that a channel common to all said spaces communicates
with them in such a manner as to lead off the vapours or heated gases at the time
of their development or formation, while the remaining liquid is retained in the
spaces or cells and is so prevented from being swept away by the vapours or
gases.
Said narrow spaces or cells may be formed by inserting suitable plates, discs,
spirally wound strips of sheet metal, or the like, in the tubular vessel, the outer
surface of which is subjected to the heat, care being taken that these inserted

page_text: bodies always maintain an intimate and extended contact with the heated surface,
so as to constitute one single metallic piece with the surrounding vessel, whereby
the heated surface of the same is considerably enlarged. Thus the what we call
"inner heating surface" formed by the walls of the narrow spaces enclosing the
liquid to be treated, is divided into a great number of little cells communicating
with each other and each of which is conductively connected with the heat
receiving surface of the vessel.
The means and arrangements of parts by which the described result is obtained,
are illustrated in the accompanying drawing by way of example, in which
Figure 1 is a longitudinal section of a part of our heating device;
Figure one of the bodies in section by which the cells are formed;
Figure 3 a cross section of the device shown in Figure 1;
Figures 4 to 6 are corresponding figures referring to a modified form of the
bodies forming the chambers or cells;
Figures 7 to 9 represent a heating apparatus consisting in a combination of
several devices of the kind shown in the former figures, Figure 7 illustrating a
section following the line 7-7 in Figure 9, Figure 8 another section on the
line 8-8 in Figure 9, and Figure 9 a cross section of the apparatus.
Similar letters refer to similar parts throughout the several views.
As illustrated in the drawing, the outer vessel preferably consists in a tube A,
within which the narrow spaces or cells are formed by superposed plates a with
projecting or turned up edges b. This border or edge b is slightly conically
enlarged and of a diameter corresponding to that of the tube A, but so, that on
inserting these plates (one of which being represented in Figure 2) in the tube, a
certain pressure is to be exerted, in consequence whereof a good contact between
the corresponding surfaces of the plates and the tube is maintained.
inventors have found, that, when the vessel is heated, the plates a are of the same
temperature, as the tube A and thus enabled to transmit the heat immediately
unto the fluid contained in the spaces or cells.
The
The distances between the plates a enclosed in the vessel A are determined
by the borders b, the height of the latter being so small, as to form capillary cells
in the whole length of tube A, whereby any spheroidal condition of the liquid
when heated is prevented. At the ends of the tube A or the connections of such
tubes (in case several tubes are combined to form a boiler, as shown in
Figures 7 to 9) contrivances, such as screw plates or collars e, are provided for to
press the edges b together, in order to secure a good contact of the plates a amongst
themselves and of the plates with the enclosing tubular vessel A.
An aperture c or several apertures c, d, are provided in the plates a, for the
purpose of feeding liquid into the cells and leading off the vapour produced therein.
The main communication is effected by the aperture c preferably arranged in the
centre of the plates a, whereas the smaller apertures d, arranged at or near the
periphery of the plates maintain a sufficient circulation within each space or cell
and prevent bubbles of steam from remaining within the cells. A still better
means for the purpose than the dish-like plates shown in Fig. 1, 2, is illustrated by
Figs. 4 to 6. The plates a made in a conical shape offer a natural way for the
vapour upward to the main communication c.
Figures 7 to 9 represent, by way of example, a mode of combining several tubular
vessels A to form a boiler or superheating apparatus and show a modified form of
arranging the plates a in regard to the tube A, in as much, as the former are sur-
rounding the tubes and the heating medium is conducted through the interior of
said tubes, instead of being led around the same, as this is presumed in the
arrangements described above. As shown in Figures 7 and 8, conically shaped
plates may be employed in combination with some of the tubes and dish-like plates
in combination with others; but it is left to the constructor, to use plates of the
form shown in Fig. 2 exclusively, or only such as shown in Fig. 5. The remaining
spaces between the columns of plates form the channels for leading off the
produced steam or gases.

page_text: It is a matter of course, that boilers, superheaters or the like, arranged according
to our invention, are provided with the requisite accessories, such as feed and
discharge pipes, safety valves, pressure gauges, steam collector and so on, parts
which being well known to all those skilled in the art need no peculiar description
and drawing.
Now to describe more exactly the new mode of heating and evaporating liquids,
heating of vapours and gases, it may be supposed that the tubular vessel A.
(Fig. 1-6) or the vessel containing several tubes A. (Figures 7-9) be filled with
liquid and a heating medium acting upon the one surface C of the tabular vessel or
vessels. From said surface the heat taken up from the fire gases or other heating
agent is immediately conducted to the other surface B, the edges b of the plates.
being in contact with this surface, to the plates themselves and to the liquid enclosed.
in or surrounded by the cells formed by said plates. In consequence thereof an
extremely quick and vigorous circulation takes place within said narrow spaces or
cells, and with a sufficient amount of heat an instantaneous evaporation of the
liquid is produced. The steam enters the main channel formed by the apertures or
holes c and is conducted to the steam collector, thus enabling fresh liquid to enter
the cells of the apparatus. The heat required to evaporate instantaneously this now
charge of liquid, is again furnished by the tube or tubes A and by this constant
demand of new heat, the heat supplied to the tubes is so fully utilised as to exclude.
the surfaces receiving the first heat to get superheated. Moreover owing to the
capillary arrangement of the cells no spherical condition of the liquid can take place.
even if a very great amount of heat is supplied to the tubes.
Any parts of the liquid that may be swept away by the vapours settle down on the
following plates or fall back into the cells and are retained there, by adhesion, for
so long until the heat exerted has brought them to evaporation.
In exactly the same manner wet vapours are treated with the view of drying
them. This is effected quickly and completely within the cells of my apparatus,
which is also applicable for superheating steam or gases.
The quick transmission of the heat of every temperature prevents the walls of
the superheater, that are directly exposed to the heating agent, from glowing or
burning.
An essential merit of our invention consists in the possibility of constructing
steam boilers which, owing to the immediate utilisation of all the heat taken up
from the heating agent, are of extremely compendious form. The rapid circulation
of the liquid within the cells and the quick evaporation of said liquid prevent any
foreign material suspended in the liquid from depositing in the cells and from
leading to incrustations, such material is swept away by the steam leaving the cells
and settles down in the steam receiver or collector, and where it can easily be
removed.
In consequence of the positive conduction of the heat taken up by the tube or
tubes to the liquid contained in the cells, and owing to the small amount of
superheated liquid within the apparatus, constructed according to our invention,
any danger of explosion is completely excluded.
As compared with the arrangements at present in use, an apparatus constructed
according to our invention presents the advantage of being for equal capacity of
much smaller size and less weight, of warranting a great economy in fuel and of
requiring much less time for getting steam.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is :-
1. In an apparatus for heating and evaporating liquids, heating vapours and
gases, the combination of a tube or tubes acted upon by the heating agent,
with a number of independent perforated plates forming small cells communi-
cating with each other, and so combined relatively to the tubes, that one of the
circuinferences of each of the perforated plates is in direct contact with the tube,

page_text: so that the heat taken up by the tube is positively conducted by the plates to the
liquid or vapour contained in the cells formed by such plates, substantially as
described.
2. In an apparatus for heating and evaporating liquids, heating vapours and
gases, the combination of a tubular vessel A acted upon by the heating agent, with
perforated plates a having turned up edges or borders b and apertures c, d,
and so combined relatively to the tubes A, that the edges of the plates are in direct
contact with the tubes, the said edges serving to space the plates in proper distance,
essentially as set forth.
3. In an apparatus for heating and evaporating liquids, heating vapours and
gases, the combination of a tubular vessel A acted upon by the heating agent,
with perforated plates a of conical shape having edges or borders b and
apertures c, d, and so combined relatively to the tubes A, that the edges of the
plates are in direct contact with the tubes, essentially as set forth.
4. In combination the vessel A and the series of separate plates inserted therein
each having a perforation and having also turned up edges to space the plates apart,
substantially as described.
5. In combination the vessel A and the series of plates extending across the same
having the central perforations and the perforations near the borders of the plates,
substantially as described.
6. In an apparatus for heating and evaporating liquids, heating vapours and
gases, the combination of a tubular vessel A acted upon by the heating agent, with
perforated plates a forming small cells communicating with each other and so
combined relatively to the tubes, that one of the circumferences of each of the
perforated plates is in direct contact with the tube, means being provided to
press said plates together and against the surface of the tube, essentially as
described.