Method of Highly Superheating Wet Steam.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Method of Highly Superheating Wet Steam.
I, WILHELM SCHMIDT of Ballenste it on the Harz, in the Duchy of Anhalt,
German Empire, Civil Engineer do hereby declare the nature of this invention to
be as follows:-
It is well known that to superheat steam several methods have already been
employed, but it is as well known that none of them has up to now met with a
satisfying result. There are a number of difficulties, that must all be overcome,
if the result is to be a satisfying one. The furnace gases should be exhausted
down to a comparatively very low temperature; said exhaustion should be
performed by surfaces of a comparatively small extent, and said surfaces should be
protected against letting the steam diffuse. If the steam to be superheated is led
in a direction equal with that of the furnace gases the latter cannot even approxi-
mately be exhausted in an economical degree, in that they escape with a temperature
of about 450°. To obviate this high ultimate temperature the steam to be super-
heated has been led in a direction opposite to that of the furnace gases, but then
the superheater proper situated in the hottest zone of the waste gases got very
liable to diffusion, and a large area of surface was requisite for said superheater.
A remarkable progress was made by first drying the steam by leading it in a
direction equal with that of the furnace gases, and then superheating the dried
steam by leading it in a direction opposite to that of the furnace gases, said super-
heating being effected by said gases after these latter had effected the said drying
of the wet steam; still, large heating surfaces are requisite for that method and the
degree of exhaustion of the waste-gases is not yet such as demanded.
My present invention forms an improvement upon the method last mentioned,
and is based on the cognizance, that a given quantity of heat is more easily taken
up by liquors than by gases. The drying of wet steam may, therefore, be attained
even if, first, the difference of temperature between that steam and the furnace
gases is but small, and, second, also but small surfaces of contact are employed.
The superheating of dried steam by leading it in a direction equal with that of the
furnace gases is to be preferred to any other method if one succeeds in economically
exhausting the heat remaining with the furnace gases after having effected said
superheating of the dried steam. That economical exhaust may fully be attained
by using the remaining heat up for the drying of the wet steam.
My improved method consists, therefore, in leading wet steam first in a direction
opposite to the furnace gases, so as to get dried, and then in an equal direction with
said gases so as to become superheated. The wet steam is acted on by those gases.
that have already effected the superheating, and is led opposite to the furnace gases
for such length of way that the water contained within the steam is completely
evaporated. The dried steam that concerning its atmosphere possesses only the
comparatively low temperature corresponding to its tension is then suddenly
exposed to the hottest gases, or enters those portions of the superheater that are
exposed to said hottest gases, respectively. Said portions of the superheater are
intensely cooled by the steam, and, therefore, very effectively prevented against
becoming glowing, and letting the steain diffuse.
The superheater for carrying my improved method into practice consists
preferably of coiled pines, or of a column of coils or spirals respectively. One

page_text: form of construction of such a superheater is represented in the accompanying
drawing, that shows the superheater combined with an ordinary flame tube boiler,
both parts being in vertical section. The superheater is composed of two super-
posed columns of coils A. A', the upper of which A is at its lower end a 3 connected
with the lower end a 4 of the lower column A¹ by the mediation of a piece of
tube c. Said end a 4 is in truth the commencement of the column A', whereas
a5 is the end proper of said column. The commencement a 2 of the upper column A
is connected with the steam-space of the boiler B by the pipe b'. 62 are curved
shields that are situated above the flame tube b 3 in a short distance thereof; the
purpose of said shields is to make the evolvement of the steam violent so as to
obtain steam with a great contents of water.
The wet steam generated within the boiler B passes through the pipe b', and
enters at a 2 the superheater A A', or more precisely the drying coils A of the
same. Flowing downwards in a direction opposite to the furnace gases, the steam is
dried when arriving at a 3, and the dried steam is led through the piece of tube c
into the superheating coils A'. The fire-gases streaming forth from the furnace D
may pass into the vertical end conduit d 5 either through the conduits d' d 2 and d 3,
or directly through the intermediate conduit d 4. The latter is furnished with any
suitable regulating device, for instance with a slide f, the purpose of which is to
regulate the temperature of the gases passing away to the coils A A¹.
Dated this 21st day of January 1896.
WILHELM SCHMIDT,
By Charles T. Powell,
Agent for the Applicant.
gay superneating wet Steam.
I, WILHELM SCHMIDT of Ballenstedt on the Harz, in the Duchy of Anhalt,
German Empire, Civil 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 :-
It is well known that to superheat steam several methods have already been
employed, but it is as well known that none of them has up to now met with a
satisfying result. There are a number of difficulties, that must all be overcome, if
the result is to be a satisfying one. The furnace gases should be exhausted down
to a comparatively very low temperature; said exhaustion should be performed by
surfaces of a comparatively small extent, and said surfaces should be protected against
letting the steam diffuse. If the steam to be superheated is led in a direction equal
with that of the furnace gases the latter cannot even approximately be exhausted
in an economical degree, in that they escape with a temperature of about 450°. To
obviate this high ultimate temperature the steam to be superheated has been led
in a direction opposite to that of the furnace gases, but then the superheater proper
situated in the hottest zone of the waste gases got very liable to diffusion, and a
large area of surface was requisite for said superheater.
A remarkable! progress was made by first drying the steam by leading it in
a direction equal with that of the furnace gases, and then superheating the dried
steam by leading it in a direction opposite to that of the furnace gases, said
superheating being effected by said gases after these latter had effected the said
drying of the wet steam; still, large heating surfaces are requisite for that
method and the degree of exhaustion of the waste gases is not yet such as demanded.
My present invention forms an improvement upon the method last mentioned,
and is based on the cognizance, that a given quantity of heat is more easily taken

page_text: up by liquors than by gases. The drying of wet steami may, therefore, be-
attained even if, first, the difference of temperature between that steam and the
furnace gases is but small, and, second, also but small surfaces of contact are
employed. The superheating of dried steam by leading it in a direction equal
with that of the furnace gases is to be preferred to any other method if one-
succeeds in economically exhausting the heat remaining with the furnace gases.
after having effected said superheating of the dried steam. That economical
exhaust may fully be attained by using the remaining heat up for the drying
of the wet steam.
My improved method consists, therefore, in leading wet steam first in a direction
opposite to the furnace gases, so as to get dried, and then in an equal direction
with said gases so as to become superheated. The wet steam is acted on by those
gases that have already effected the superheating, and is led opposite to the
furnace gases for such length of way that the water contained within the steam.
is completely evaporated. The dried steam that concerning its temperature
possesses only the comparatively low temperature corresponding to its tension is
then suddenly exposed to the hottest gases, or enters those portions of the super-
heater that are exposed to said hottest gases, respectively. Said portions of the
superheater are intensely cooled by the steam, and are, therefore, very effectively
prevented against becoming glowing, and letting the steam diffuse.
The superheater for carrying my improved method into practice consists
preferably of coiled pipes, or of a column of coils or spirals respectively. One
form of construction of such a superheater has been represented in the drawing
filed with the Provisional Specification, which said drawing is further used for
illustration and reference in this my Complete Specification. Said drawing shows
the superheater combined with an ordinary flame tube boiler, both parts being
in vertical section. The superheater is composed of two superposed columns
of coils A A', the upper of which A is at its lower end a 3 connected with the
lower end a 4 of the lower column A' by the mediation of a piece of tube c..
Said end a 4 is in truth the commencement of the column A', whereas a 5 is
the end proper of said column. The commencement a2 of the upper column A
is connected with the steam-space of the boiler B by the pipe 6. 62 are curved
shields that are situated above the flame tube 63 in a short distance thereof;
the purpose of said shields is to make the evolvement of the steam violent so as
to obtain steam with a great contents of water.
The wet steam generated within the boiler B passes through the pipe b, and
enters at a 2 the superheater A A', or more precisely the drying coils A of the
same. Flowing downwards in a direction opposite to the furnace gases, the steam
is dried when arriving at a 3, and the dried steam is led through the piece of
tube c into the superheating coils A. The fire-gases streaming forth from the
furnace D may pass into the vertical end-conduit d5 either through the
conduits dd 2 and d 3, or directly through the intermediate conduit d 4. The
latter is furnished with any suitable regulating device, for instance with a
slide f, the purpose of which is to regulate the temperature of the gases passing
away to the coils A A'.
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 :-
The method of drying and superheating steam, consisting in first letting a
mixture of water and steam passing through a coil be acted on, and get dried,
or dried and slightly superheated, by the coolest portion of the waste gases of
a furnace, whilst flowing in opposite direction to said gases, and then letting the
dried steam or the dried and slightly superheated steam be acted on, and get
properly superheated, by the hottest portion of the said waste gases, whilst
flowing in equal direction with the same, for the purpose of exhausting furnace

page_text: waste gases by means of superheaters with heating surfaces of smallest area,
and for the purpose of preventing the superheaters against being burnt.
Dated this 14th day of October 1896.
WILHELM SCHMIDT,
By Charles T. Powell,
Agent for the Applicant.