IMPROVEMENTS IN THE MEANS FOR EFFECTING THE COMBUSTION OF FUEL, AND IN THE CONSTRUCTION AND ARRANGEMENT OF FIRE-PLACES AND FURNACES FOR THAT PURPOSE
Year: 1880

page_text: LETTERS PATENT to Gerard Wenzeslaus von Nawrocki, of the Firm of
J. Brandt and G. W. von Nawrocki, Patent Solicitors and Civil Engineers, of
No. 124, Leipziger Strasse, Berlin, in the German Empire, for an Invention
of "IMPROVEMENTS IN THE MEANS FOR EFFECTING THE COMBUSTION OF
FUEL, AND IN THE CONSTRUCTION AND ARRANGEMENT OF FIRE-PLACES AND
FURNACES FOR THAT PURPOSE." A communication by Rudolf Müller, of
Berlin, in the German Empire.
PROVISIONAL SPECIFICATION left by the said Gerard Wenzeslaus von
Nawrocki at the Office of the Commissioners of Patents on the 1st April
1880.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and Q. W. von
Nawrocki, Patent Solicitors and Civil Engineers, of No. 124, Leipziger Strasse,
Berlin, in the German Empire. "IMPROVEMENTS IN THE MEANS FOR EFFECTING
THE COMBUSTION OF FUEL, AND IN THE CONSTRUCTION AND ARRANGEMENT OF
FIRE-PLACES AND FURNACES FOR THAT PURPOSE." [A communication by Rudolf
Müller, of Berlin, in the German Empire.]
The conditions necessary for applying fuol with the greatest economy for heating
purposes are, firstly, that the combustion thereof shall be effected in the most
perfect manner; secondly, that the heat produced shall be imparted to the object
or locality to which it is to be applied with the least possible loss by radiation or
conduction through tho walls of the flues through which the flames and gases are
made to pass in order to reach such parts, and for the purposo of producing the
necessary draught; and, lastly, the arrangements should be such as to admit of
casy regulation of the combustion and of the heat desired to be produced.
In furnaces and fire places of ordinary construction these conditions are but very
imperfectly complied with, and oven in the best known mode of effecting combus-
tion, namely, that wherein the solid fuel is first converted into gaseous fuel in a
gas generator, and is then conveyed to the locality where it is burnt by admixture
with atmospheric air, certain imperfections exist owing to the manner in which tho
combustible gases are produced, and to the fact that the generator is separate from
the place where the combustion is effected, whereby loss of beat is caused in
conducting the gases from the ono place to the other.

page_text: According to the present inv
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employment of means whereby, firstly, the production of the gaseous fuel is effected
at the same locality where heat is to be produced by its combustion; and, secondly,
the production and combustion of the gases are effected in such a manner that little
or no complete combustion is produced in the body of the fuel, the volatile consti-
tuents of this being first distilled off and made to enter into combustion with a
heated air supply introduced at a certain height above the fuel, after which
sufficient air is admitted to the fuel to produce by imperfect combustion carbonic
oxide gas only, which in rising up to the said heated air supply in its turn enters
into combustion therewith; lastly, instead of producing draught by the use of high
chimnies, as is necessary with tho ordinary mode of burning fuel, and which
_ involves the loss of a considerable amount of heat for producing the rarefied column
in the chimney, such draught is-according to the present Invention almost entiroly
dispensed with, the combustion being made to take place under moro or less-
perfectly quiescent conditions of the gases in the combustion chamber, and the
heavy gaseous products of combustion in descending in the combustion chamber
being conducted away through openings at the bottom thereof, while the lighter
products are allowed to escape from time to time at the top of the chamber.
The general arrangements of furnaces and fire places for carrying out the above
described improved mode of effecting combustion are as follows:-
The grate, which is in most cases by preference formed of porous fire brick, has
comparatively small interstices, serving for a very limited passage of air from below
and for the discharge of ashes. The ash pit is closed hermetically by doors having
small apertures regulated by slides for the inlet of air. At the level of the fire
grate is another small opening for the inlet of air, and above this is the fire door
for charging the fuel, and if necessary other openings or passages are provided at
the sides and top of the fire door for the inlet of air at the level of the body of fuel.
Other air passages extend upwards in the walls of the combustion chamber, into
which they open at points some height above the fuel, these passages serving for
the introduction of heated air for effecting the combustion of the gaseous fuel.
With this arrangement the process of combustion is carried out as follows:-A
charge of fuel having been introduced on the grate this is burnt in the first instance
in the ordinary manner by the free inlet of air from the ash pit in order to produce
vivid combustion. As soon as by this means an incandescent layer of fuel has been
attained a fresh charge is introduced, and the ash pit door is closed, leaving the air
holes therein slightly open in order to admit only sufficient air for maintaining the
incandescence of the fuel and of the fire brick grate. All the lower air holes being
closed the volatile constituents of the fresh fuel are now distilled off by the heat of
the fuel on the grate, and in rising enter into combustion with the heated air
entering through the upper air holes, such air becoming heated by contact with the
hot surfaces of the flue as it passes in. When the whole of the volatile constituents
have thus been distilled off and burnt the lower air holes are opened more or less
so as to allow only sufficient air to enter among the incandescent fuel to produce
carbonic oxide gas by imperfect combustion therewith. This gas in rising also
enters into combustion with the heated air supply above, and this is continued
until the fuel on the grate is reduced to a comparatively thin layer again, where-
upon a fresh charge of fuel is introduced, and the above described operation is
repeated.
The heavy gaseous products of combustion are, as beforo stated, led off through
openings in the side walls of the chamber near the level of the grate, such openings
communicating with flues leading upwards to a moderate height, while the lighter
products are led off from time to time through openings provided with slides or
valves at the top of the chamber, and either leading directly into the open air or
through passages communicating with the flues through which the heavy gases
pass off. In order to cause the latter gases which descend along the walls of the
combustion chamber to pass off undisturbed the exit apertures are by preference

page_text: formed in a special channel formed at the side of the fire grate, or sunk somewhat
below the level thereof.
The above described improved means of effecting combustion may be employed
in all descriptions of furnaces, kilns, or ovens, excepting those furnaces or kilns in
which the fuel and the material to be acted upon are charged in alternate layers in
vertical shafts, as in blast furnaces. It is also applicable for domestic stoves and
for steam boilers; in the latter case, if the boiler has internal flues, the before
described combustion chamber may be constructed in front of the boiler, with the
flucs of which the said chamber communicates.
In those furnaces or fire places where the combustion chamber or the flues or
passages in which the combustion of the gascous fuel is effected is or are com-
paratively wide or long; the air supply for the combustion is conducted through
passages formed in the bottom, sides, or top of the chamber or flue and leading to the
more distant parts thereof, where the heated air in issuing into the chamber enters
into combustion with the gases at such points, and thus insures a uniform combustion
throughout the chamber or flue.
In the application of the Invention to kilns or ovens the chamber containing
the material to be calcined or burnt may itself constitute the combustion chamber;
or the combustion chamber may be forined beneath a perforated floor of the kiln,
which floor is in some cases raised conically in the centre in order to allow a
similarly raised central part of the combustion chamber to be formed beneath it, in
the upper part of which open the channels for the hot air supply.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Gerard Wenzeslaus von Nawrocki in the Great Scal Patent Office on
the 30th September 1880.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and G. W. von
Nawrocki, Patent Solicitors and Civil Engineers, of No. 124, Leipziger Strasse,
Berlin, in the German Empire. "IMPROVEMENTS IN THE MEANS FOR EFFECTING
THE COMBUSTION OF FUEL, AND IN THE CONSTRUCTION AND ARRANGEMENT OF
FIRE PLACES AND FURNACES FOR THAT PURPOSE."_A_communication by Rudolf
Müller, of Berlin, in the German Empire.
The conditions necessary for applying fuel with the greatest economy for heating
purposes are, firstly, that the combustion thereof shall be effected in the most
perfect manner; secondly, that the heat produced shall be imparted to the object
or locality to which it is to be applied with the least possible loss by radiation or
conduction through the walls of flues, through which the flames and gases are
made to pass in order to reach such parts, and for the purpose of producing the
necessary draught; and, lastly, the arrangements should be such as to admit of
easy regulation of the combustion and of the heat desired to be produced.
In furnaces and fire-places of ordinary construction these conditions are but very
imperfectly complied with, and even in the best known mode of effecting com-
bustion, namely, that wherein the solid fuel is first converted into gaseous fuel in a
gas generator, aud is then conveyed to the locality where it is burnt by admixture
with atmospheric air, certain imperfections exist owing to the manner in which
the combustible gases are produced, and to the fact that the generator is separate
from the place where the combustion is effected, whereby loss of heat is caused in
conducting the gases from the one place to the other.
According to the present Invention these imperfections are obviated by the
employment of means, whereby, firstly, the production of the gaseous fuel is effected
at the same locality where heat is to be produced by its combustion; and secondly,
the production and combustion of the gases are effected in such a manner that little
or no complete combustion is produced in the body of the fuel, the volatile
constituents of this being first distilled off, and made to enter into combustion
with a heated air supply introduced at a certain height above the fuel, after which
sufficient air is admitted to the fuel to produce by imperfect combustion carbonic
oxide gas only, which in rising up to the said heated air supply in its turn enters
into combustion therewith; lastly, the use of high chimnies, such as are necessary
with the ordinary mode of burning fuel, and which involves the loss of a considerable
amount of heat, is by the present Invention dispensed with, as the requisite
draught is produced with much less expenditure of power.
The general arrangements of furnaces and fireplaces for carrying out the above
described improved mode of effecting combustion are as follows:-
The grate, which is in most cases by preference formed of porous fire brick, has
comparatively small interstices, serving for a very limited passage of air from below,
and for the discharge of ashes. The ash pit is closed hermetically by doors having
small apertures regulated by slides for the inlet of air. At the level of the fire
grate is another small opening for the inlet of air, and above this is the fire door
for charging the fuel, and if necessary other openings or passages are provided at
the sides and top of the fire door for the inlet of air at the level of the body of the
fuel. Other air passages extend upwards in the walls of the combustion chamber,
into which they open at points some height above the fuel, these passages serving
for the introduction of heated air for effecting the combustion of the gaseous fuel.
With this arrangement the process of combustion is carried out as follows:-A
charge of fuel having been introduced on the grate this is burnt in the first instance

page_text: combustion chamber at a suitable height, the openings of m¹ being rather higher
than those of m, as shewn more clearly at Fig. 4. The two passages n next the
charging passage b converge towards each other, and open partly into the charging
passage, as shown at Fig. 2. The passages n¹ run first horizontal and then rise in
the front wall and open into the combustion chamber at about the same height as
the passages m¹. Lastly, a passage p is provided immediately over each firedoor of
somewhat larger diameter than the others, which passage serves both for the
admission of air and as eye hole for observing the state of the combustion. All the
passages can be closed hermetically by slides or doors. It may be stated that
the passages serve principally for introducing the necessary air for igniting the
gases, for which purpose they may be made somewhat smaller thau the others.
The passsges may be formed directly in the brick work, or they may be made of
earthenware or other pipes. The-arrangement, it will be secu, admits of the com-
bustion being carried on in the ordinary manner as is necessary during-the-first
part of the firing operation. For conducting away the gaseous products of com-
bustion formed during this part of the process serve the draught holes o in the top
of the kiln. When such preliminary firing has been completed, which is after about
24 to 48 hours, the combustion with the gaseous fuel is commenced, [for which
purpose all draught holes o are in the first place closed by clay stoppers. I will
now describe the mode of operating with this kiln, which description will serve
generally to explain the method as applicable to all the other arrangements to be
presently described. Nearly all the openings o having been hermetically closed
and the firegrates provided with a layer of coke about 3 to 5 inches thick, the-ash
pit door is completely closed and the small slide i is opened only sufficiently to
maintain the coke on the grate incandescent. The fuel, which may be coal, peat, or
wood, is introduced on the latter, and the fire door d, as also the slides g, are closed
air tight. The volatile constituents are now rapidly distilled off, and sufficient
air is introduced into the combustion chamber through the passages m, m, n,
n', and p, for effecting the quiet combustion of the gases produced. As the gases
are at once burnt without being cooled by passing through long conducting
channels, and the air is conducted to them in a heated condition by contact with
the hot oven walls, the heat produced by the combustion is very considerable.
After a certain time the distilling off of the volatile constituents being completed
the conversion of the remaining carbonaceous matter into combustible gas is com-
menced by the introduction of a limited air supply thereto. For this purpose the
slides g are opened. The carbonic oxide gas thus formed rises in the combustion
chamber and centers into combustion in the same manner as the volatile constituents.
The slide in the ash pit door may during this time be opened somewhat more, but
the air supply must always be so limited that only imperfect combustion takes
place on the hearth. After about to 1 hour the charge of solid fuel will have been
in great measure converted into gas, whereupon a fresh charge is introduced and
the above described combustion process is repeated. If after repeated charges of
fuel the accumulation of coke on the grate should have become too great, the ash
pit door and the slide are fully opened so as to admit sufficient air to effect
complete combustion until the layer of coke has been again reduced to a thickness
of from 3 to 5 inches, and the conditions favourable for the production of carbonic
oxide are restored.
This systein of firing can of course be employed in kilns or ovens having any
number of separate compartiments, as indicated at Fig. 5, which shews a sectional
plan of a kiln with eight compartments. The passages shewn are those for the
admission of air. The heated gaseous products may be utilized in the well
known manner practised in kilns with compartments for the preliminary drying
and heating of the green goods, by forming immediately over the floor of the kiln
connecting passages between the compartiments, which can be closed or opened
from the outside by slides. If the goods in compartment 11. are to be heated by
the gases coming from compartment I., the said connecting passages in the wall?
are opened, as are also the draught holes in the roof of II., so that the gaseous

page_text: products pass from I. through the goods in II., and after imparting their heat theroto
escape through the draught holes.
Figs. 6 and 7 shew the arrangement of the passages in an ordinary limo kiln;
Fig. 6 is a vertical section, and Fig. 7 a part sectional plan on line C, D, Fig. 6.
The lime rests upon the perforated floor A; a aro the fireplaces in which the
distillation and imperfect combustion of the fuel and also the partial combustion
of the gases is effected. The complete combustion however only takes place in the
chamber B. In the middle of the kiln is the conical projection D, above which tho
floor is raised in a corresponding conical shape. For continuous lime and cement
kilns the arrangement is not so applicable, as the firing is effected in a similar
manner to blast furnaces. It is however applicable with great advantage for
porcelain ovens, baking ovens, domestic stoves, and drying stoves.
Figs. 8 and 9 shew, by way of example in sectional elevation and sectional
plan, a porcelain oven arranged according to this Invention, to bo heated directly
by gaseous fuel without special generator. The production and partial com-
bustion of the gaseous fuel is here effected in the firing chambers F, which have
precisely the same passage as described with reference to Figs. 1 to 4. Tho
complete combustion of the gases however takes place in tho combustion
chambers G and H, which are provided with air supply passages m, n.
Fig. 10 shews a baker's oven with two baking chambers having the above
described method of firing applied to it; Figs. 11 and 12 shew a domestic stovo;
and Figs. 13 and 14, a drying stove arranged according to the same system.
The application of the system to steam boilers is shewn at Figs. 15 to 20; in
the arrangement shewn in longitudinal and cross section and front view at Figs. 15,
16, and 17 the boiler is assumed to be one with internal flues that has been
previously provided with an ordinary grate, as indicated by dotted lines. In order
to adapt the boiler for the use of gaseous fuel without separate gas generator, a
brickwork combustion chamber is built in front thereof. Fig. 17 shews the
arrangement of the front wall with the fire doors , the ash pit door with the
slide i, and the slides g, which are all of the same arrangement and serve the samo
purpose as the slides i and g in Fig. 1. The air supply passages n in this case
also lead from the front wall, the openings thereto being regulated by slides p.
The gases here are generated in the same manner as described with reference to
the brick kiln; they are partly burned in the combustion chamber directly over
the fuel, but mainly they are burnt in the flues. For this purpose the air necessary
for combustion is introduced in a heated state at suitable points by the passages 8.
The combustion takes place perfectly quiescent, so that such arrangements require
no tall chimnies, as little draught is required for leading off the gaseous products
and maintaining combustion. In existing constructions it will therefore be
necessary to close the chimnoy almost entirely by dampers in order to maintain
quict combustion.
In addition to the advantages enumerated at the beginning hereof, the described
system has, for steam boilers, the further advantage that when no steam is required
and the whole of the apertures are closed, so high a temperature is maintained in
the combustion chamber and flues that the burning of the gaseous fuel can be at
once resumed when the boiler is required for use; such a stoppage may last as long
as 24 hours without interfering with the working.
Having thus described the nature of this Invention and in what manner the
same is to be performed, as communicated to me by my correspondent, I wish it
to be understood that I do not claim the several separato parts of the before
described means of producing and effecting the combustion of gaseous fuel, and
of apparatus therefor when taken by themselves, as constituting the present
Invention, but I claim,―
First. The herein described method of effecting the production and combustion
of gascous fuel without separate gas generator, whereby an incandescent layer of
fuel or an incandescent porous grate is caused, by a regulated admission of air, to
effect, first, the distillation of the volatile constituents of a charge of solid fuel,

page_text: and then the conversion of the residue thereof into combustible gases, the gases
so produced being directly afterwards made to enter into combustion with heated
air admitted at a certain distance from the layer of solid fuel.
Second. The use of apparatus for effecting the production and combustion of
gaseous fuel, consisting of a combustion chamber wherein a restricted quantity of
air is supplied to the firegrato through apertures below and at the level thereof,
such apertures being provided with regulating slides or valves, while a further air
supply is caused to pass through other passages so as to issue in a heated state
into the upper part of the combustion chamber for effecting the combustion of the
gaseous fuel, substantially as herein described with reference to the accompanying
Drawings.
Third. In apparatus for effecting the production and combustion of gascous
fuel, the-combination_of_the_combustion chamber A, firegrate a, ash pit door b,
with air holes i, and all or any of the air passages m, m, n, n',-and-p,-all..
arranged and operating substantially as herein described and shewn on the
Drawings.
In witness whereof, I, the said Gerard Wenzeslaus von Nawrocki, have
hereunto set my hand and seal, this Twenty fifth day of September, in
the year of our Lord One thousand eight hundred and eighty.
GERARD WENZESLATIS VON NAWROCKI. (L.S.)