Year: 1887

page_text: Date of Application, 6th Sept., 1887
Specification Accepted, 25th Oct., 1887
I, JOSEF VON EHRENWERTH Professor at the School of mines of Leoben Styria in
the Austrian Empire, 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 :-
With furnaces having periodical action, i.e. those in which, after operating upon a
charge, the furnace chamber has to be cooled down for the removal of the charge and
the introduction of a fresh one, the regenerative system has not been hitherto
applicable on account of such cooling down. Such furnaces, as for instance pottery
Kilns &c., are not only too much cooled down after the introduction of the fresh
charge to effect the ignition of the entering mixture of gas and air, but also the
gaseous products of combustion that first pass off are so cool, and in many cases so
charged with moisture that their passage through the regenerators would rather
reduce than raise the temperature of these, and would also charge these with
moisture.
According to my present invention the regenerative principle is rendered applicable
to such furnaces having periodical action, by providing at least at one end of the furnace
a fore-fire which has for its object to heat the furnace, at least at this end, to the
temperature necessary for igniting the mixture of air and gas or to maintain the
combustion of the mixture until the furnace has attained the required heat, the other
end (or both ends) of the furnace being provided with a direct connection with a
chimney that is capable of being closed, and through which the gaseous combustion-
products are allowed to escape until their temperature has attained the required
degree.
As, in arranging only a single such furnace with a set of regenerators, these would
cool down too much during the time the furnace was being cooled down emptied,
recharged, and heated up again, it is advantageous to connect with the air and gas

page_text: passages of one and the same set of regenerators several furnaces capable of being
inade to communicate therewith and to be cut off therefrom, the number being
preferably such that at least one of the furnaces can, in rotation, always be main-
tained in action thereby, while the others are in rotation, cooling, discharging, and
being charged afresh.
From the foregoing it will be seen that the invention, in its most perfect form,
consists in the combination of several furnaces with one set of regenerators, each
furnace having a connection with a chimney that can be cut off, and the set having
at least one fore-fire, that can either be cut off or converted into a gas generator.
The invention however also includes.
The combination of a single furnace arranged as above described with a set of
regenerators.
If the air required for combustion is alone to be heated, the gas regenerators are of
course dispensed with, without otherwise altering the arrangement.
The invention is applicable as well for furnaces operating with continuous currents
as with those having alternately reversed currents. In the former case the generator
for the combustible gas may also be used as the fore-fire.
Fig. 1 of the accompanying drawings shews a sectional plan of a set of three
furnaces arranged as above described operating with alternately reversed currents.
Fig. 2 shews a longitudinal section to an enlarged scale of one of the three furnaces.
Fig. 3 shews a vertical section of a furnace operating with continuous currents, with
fore-fire serving also as generator for combustible gas. In the arrangement shewn at
Figs. 1 and 2 the gas and air regenerators G G and L L are connected at one end
firstly by means of the reversing valves V V₁ in the usual manner with the gas
generator at A and at B with the outer air and on the other hand with the chimney E',
while from the other end passages L¹ L and G₁ G₁ lead beneath the furnaces for
conducting alternately combustible gas and air to the latter and hot combustion gases
from these to the chimney through the regenerators.
The passages G¹ and L' are connected to the furnaces by small flues g and that can
be closed by slides and the parts of which within the furnace may be termed burners.
As already stated, each furnace (or, whero several furnaces are connected to one set
of regenerators, one of the furnaces) is provided at one end with a fore-fire F that can
be cut off by means of a slide S, the flues of which, in this arrangement open into the
passages, but which may also communicate with the passages g or directly with the
furnace chamber.
In addition there is provided a flue E at the opposite end which, in the arrangement
shewn, communicates with the chinney E' and with the furnace chamber by flues e
capable of being closed by slides S². In place of the flue E the flues G¹ & L¹ of all
the furnaces or of one of them, may be connected directly to a chimney, in which case
the fore-fire may be arranged at the middle of the furnace.
As the furnaces also communicate with each other through the flues L' G', it is
possible to cause a portion of the combustion gases to pass from the furnace in
action into a freshly charged furnace, or to heat this by means of a portion of the
heated air and gas supply.
In this way with a set of furnaces that are brought into action in rotation or of
which one or more are continuously in action, only a single furnace need be provided
with a fore-fire F, this being put in action when the group is first set to work, while
for the subsequent change from one furnace to another, its action is replaced by the
above described mode of preliminary heating either by a portion of the combustion
gases or by the combustion of a portion of the gas and air supply.
The gases passing away from the furnace that is subject to the preliminary heating
will of course pass off to the chimney E¹ through the passages e and E.
In the modification shewn at Fig. 3 for continuous currents, F¹ is the gas
generator, constructed in this instance as a fire place with step-grate, and connected
directly to the furnace, and serving also as fore-fire.
In order to use it for this purpose it is only necessary to maintain on the grate a

page_text: layer of fuel of approximately such thickness, that complete combustion is effected.
For this purpose the charging hopper is provided with a slide f by which the
sectional area of the inlet can be suitably altered.
O is the furnace chamber, a the discharge flue for combustion gases which has a
double branch of which one a' communicates at top with a chimney, such as the
main chimney E¹, while the other a communicates at bottom through a reversing
valve V' with the regenerators, which again communicate through a second reversing
valve V³ on the one hand with the chimney E, and on the other hand with the air
(or gas) inlet. On the other hand the air heated in the regenerators is led by the
reversing valve V2 and the passages L' into the furnace chamber.
Suitable means for closing the communications, such as slides S, S,, enable each
current to be regulated or cut off.
If the combustible gas is also heated in the regenerators, this is effected in just
the same way as with the air, namely by means of a pair of regenerators introduced
between the discharge flue of the furnace and the chimney, these being connected on
the cold side with the gas flue and on the hot side with the combustion gas flue to
the furnace. In cases where the gas generator is removed from the furnace and
placed nearer to one end of the regenerators the above purpose is accomplished by
providing at the furnace a fore-fire which may also consist of a fire arranged directly
in the furnace chamber.
If several furnaces are combined with one set of regenerators, this being assumed
in the drawing, the discharge flues of these lead both upwards at a and downwards
at a² into common flues A' A' which, on the other hand, as before described,
either communicate directly with the chimney, as at A', or through the regenerators
as at A. In this case the hot air flues also communicate with a common hot air
flue L
In addition it is advisable to connect the hot air flue L³ of the furnace directly
with the chimney E₁..
Suitable means such as slides S, are provided for regulating all currents.
By the direct connection of the hot air flues L, of each furnace with the chimney E¹
the conduction of a portion of the combustion gases of a furnace into a second
furnace requiring preliminary heating is effected through A, a O L, e̟.
With this arrangement each furnace may either have its own generator, or several
furnaces (say 3) may be connected to one generator.
The above described method of heating is applicable as well to vertical as to
horizontal furnaces, and in the former caso as well with an upward as with a down-
ward current ; it is also applicable to a row of independent furnaces connected to the
same set of regenerators, the working of which is only in so far periodical as each
furnace is capable of being put in or out of action as may be required, without
interfering with the action of the others, such for instance as furnaces for annealing
wire, steam boilers &c. In such cases the direct discharge of the combustion gases
into the chimney is advisable but not absolutely necessary.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I claim is :-
:-
1. The construction of regenerative gas furnaces which are provided at least at
one end with a fore-fire, that can be cut off, the other end being provided with a
direct connection with the chimney that can also be cut off, so that by means of the
fore-fire, the furnace chamber can be heated to the degree necessary for the ignition
of the mixture of combustible gas and air, or the combustion of the said mixture
can be maintained thereby, while the combustion-gases can be allowed to pass away
directly to the chimney so long as they are not suited for heating the regenerators,
the gas and air passages being also capable of being cut off.
2. The combination of a number of regenerative gas furnace arranged as set forth
in the preceding claim with a single set of regenerators, substantially as herein
described.

page_text: 3. With furnaces arranged as set forth in the preceding claims, providing a single
furnace with a fore-fire so that this only requires to be used when starting the
furnaces, the second and other furnaces being subjected to preliminary heating either
by the hot combustion gases of the furnace in action, or by the combustion of a
part of the heated combustible gas and air supply.
4. In regenerative gas furnaces with continuous currents operating as set forth
in the first clain, arranging the combustible gas generator in such manner that it
can, when required be made to serve as a fore-fire for preliminary heating by so
adjusting the supply of fuel as to effect complete combustion..
5. In regenerative gas furnaces with continuous currents operating as set forth
in the first claim, without regenerators for the combustible gases, arranging the gas
generator F near the inlet end of the furnace, and in case of a step-grate, providing
a regulating slide for regulating the area of the inlet for fuel, so that the gas
generator nay, as required, be made to serve as fore-fire or as gas generator.
Dated this 6th day of September 1887.
ABEL & IMRAY,
Agents for the Applicant.