Improvements in Furnaces for Locomotive, Marine, and other Steam Generators.
Year: 1895

page_text: Date of Application, 14th Aug., 1895-Accepted, 14th Sept., 1895
COMPLETE SPECIFICATION.
1
Improvements in Furnaces for Locomotive, Marine, and other Steam
Generators.
I, WILHELM LÖNHOLDT, Architect, of Wichmannstrasse 24, Berlin, W., 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 :-
This invention relates to the decomposition of a thick layer of fuel by the
introduction of air mixed with steam, into carbonic oxide and hydrogen gases,
and then to convert these gases by combustion with heated air into carbonic acid
gas and water.
This method avoids excepting as regards the accurate measurement of the
volume of air supplied, all the disadvantages of the direct combustion of the
solid fuel, especially because the excess of air, over the quantity theoretically
required to supply the oxygen required, can be reduced to a minimum, whereas
with direct burning about double the necessary quantity of air must be introduced
to the furnace, if it be desired to prevent the far greater loss by the escape of
unconsumed waste gases through the chimney; the entire excess of the air
supplied is moreover heated and 15 per cent. of the generated caloric is carried
away to waste by the chimney.
If however, on the contrary, only the theoretic quantity of air, necessary to
convert the carbonic oxide into carbonic acid, be supplied then the direct loss by
unconsumed or imperfectly consumed gases alone, amounts to 18 per cent. while
furthermore the incomplete conversion into carbonic oxide in lieu of carbonic acid
leaves 60 per cent. of the heating power contained in the coal entirely undeveloped.
In confirmation of these theoretical considerations, it has been shown by carefully
conducted practical experiments in combustion that about 40 per cent. of the total
heating value of the coal is lost.
In the furnace which forms the subject of this invention these enormous losses
are as much as possible reduced to a minimum, and particularly by supplying the
nearest possible approximation of the quantity of air to that theoretically
necessary; and further the disadvantages of the smell and fumes of smoke and
development of sparks of the irregular combustion and consequent unequal
generation of steam, of the wear and loosening of fire-tube connections in the
firebox and other parts of the boiler, as well as of the concretion of cinder and
slag on the firegrate, are all avoided by the working of the apparatus being
rendered more or less independent of the attention and care in firing of the
stoker.
In order to keep down the temperature above the firegrate and in the primary
combustion chamber, the fuel is heaped up high on the grate inasmuch as no more
air should be admitted than is necessary for the production of carbonic oxide and
further from the water contained in the water-tight enclosed ashpan steam is
developed, which from its conversion into hydrogen takes up so inuch caloric, that
not only are the grate-bars kept cool, but also the temperature is not high enough
to smelt the cinder and slag and form clinkers.
From 9 kilos. of water is evolved 1 kilo. of hydrogen, taken up by the decom-
position 34180 calories (heat units): 1 kilo. of pure carbon, burnt to carbonic
oxide, gives 2473 calories, which are thus competent to supply the heat necessary

page_text: to convert 0.65 kilos. of water into 0072 kilos. of hydrogen; but inasmuch as in
that case the burning power of the fuel would be exhausted, it is evident that the
evolution of steam can never attain those limits for otherwise the fire would very
soon be extinguished.
In the furnace in question the admission of steam is so regulated that when too 5
much steam has access and is decomposed, the temperature on the firegrate is
lowered and the evolution of steam at once drops.
The calories absorbed by the hydrogen are not lost, but are given out and
become again available, for the production of heat by the subsequent combustion
of the hydrogen; but this development of heat is transferred from the firegrate 1
(where it is unfavourable) to the combustion-chamber (where it is advantageous)
in front of the firetubes and even by the elongated flames which in consequence of
the disassociation or breaking-up processes resulting from the admixture of carbonic
acid, hydrogen and heated air is extended right into the interior of the fire-tubes. In
this manner are completely consumed the volatile hydrocarbons, which are specially
injurious to the materials of the boiler and which with other residual products
form solid crusts and hard scale in the interior of the fire-tubes etc.
The air for combustion becomes heated by its passage, flowing right and left
from below, through two pipes laid in the heated brickwork or masonry sides of
the fire-box into an air-collecting chamber constructed of fire-bricks, whence it flowe
into the highest and hottest point of the combustion chamber, and thence, in two
directions, through alternate apertures, of such kind and construction, that the
combustion-gases are most thoroughly and intimately mingled with the heated air,
while the latter forms a veil or curtain over the entire breadth of the firebox which
must be traversed by the combustion gases. This perfect and intimate admixture
of the elements which is indispensable to perfect and thorough combustion and the
most favourable results, is essentially promoted by a change in the direction of the
flames.
The masonry or brickwork chambers constitute a heat accumulator most admirably
adapted to perfect and complete combustion.
It is obvious that the quantity of heated air supplied for combustion must be
capable of being adjusted and regulated by hand by suitable throttle-valves.
After these valves have been set the regulation of the air supply takes place
automatically according to the higher pressure of the in-streaming air propor-
tionately to the velocity of the draught and to the extended or contracted
evolution and use of steam and the consequent requirements of the more or less
lively combustion.
On the accompanying drawings I have illustrated my new invention which
consists essentially in the division of the firebox into four different chambers, viz.—
1. The gas-producing chamber for the evolution of the heating gases;
2. The fire chamber for the free development of the flame;
3. The combustion chamber for thoroughly mixing and uniting the flames ;
4. The flame collecting chamber for retarding and complete utilisation of the
heat-development.
The action of these chambers is aided by the arrangements and apparatus
illustrated in the accompanying drawings in which
Figure 1 is a longitudinal central section through the fire box of a locomotive
boiler constructed according to my invention.
Figure 2 is a transverse section the left hand half taken on the line A B of
Figure 1 and the right hand half on the line C D of that figure.
Figure 3 is a sectional view through the air heater, this view showing in plan
the underside of some of the air outlets, and
Figure 4 is a horizontal section on the line E F of Figure 1.
In the rear portion of the fire-box is constructed a vaulted arch c made of
refractory materials. The arch is continued by lateral cheeks, also of fire-proof
material, which for the purpose of obtaining a broader base for the arch are
made to project laterally forwards.

page_text: Beneath this arch lies the gas-producing chamber whence the heated gases:
enter the fire-chamber wherein under the action of the steam evolved in the
ash-box they are decomposed into carbonic oxide and hydrogen. In locomotives,
for this purpose, the ash-box must be carefully made tight, as it serves at the same.
tine as a water reservoir. In marine engines this arrangement already exists.
The ascending heated gases or combustion products then come in contact with
the sloping upper part or bridge G H on the arch c, which bridge inclines in the
direction of the fire-door. This bridge as shown in Figure 2 has somewhat the
appearance of a comb or cress; and its object is to prevent any of the broken-up.
cinder or slag getting into the combustion chamber on to the arch c, during stoking
operations. Furthermore, owing to its comb-like construction the gases are
subdivided into separate currents, or so to say, filaments, whereby the bridge
becomes extremely hot and incandescent, thus already promoting to the utmost
possible degree the consumption of smoke in the fire-space itself.
Passing away over the bridge G H the gases enter the combustion chamber-
through a contracted conical passage formed by the bridge G H and the arch E F.
This latter is constructed of fire-bricks or refractory material and resting on
lateral checks has a considerable depth or thickness, so as to allow of the
formation of an air chamber inside of it. To this inner air chamber lead the
pipes e which are arranged in the angles of the fire-box and protected by any
suitable coating from direct contact with the fire-gases. The air from outside
is preliminarily heated to a considerable temperature in these pipes and finally
heated to a very high degree inside the air-receptacle; after which the highly-
heated air flows through narrow slots or apertures ƒ and g into the combustion
chamber the former (f) sloping towards the fire-door and the latter (g) being
directed vertically downwards, so that the issuing air forms two veils or curtains
at an angle to each other, in such manner as to take in the entire width of the
firebox whereby every portion of the heated gases must pass through some part of
the veil of hot-air before reaching the fire-tubes.
The regulation of the air-supply through the pipes e is effected from the driver's
footplate by means of any suitable appliances.
Out of the combustion chamber the heat-gases now being completely burnt and
converted into carbouic acid and water pass into the flame-collecting chamber, and
thence further into the fire-tubes of the boiler.
In the flame-collecting chamber any small pieces of cinder and other residuals
are separated and drop through the cross-slots provided for the purpose in the
arch c at its lowest point back into the generator chamber. In order to prevent
all possibility of the flames coming directly from the flame-collecting chamber
through the above-named slots h which would prejudicially affect the fire-tubes,
the lowest point of the arch c is not located close to the rear wall of the boiler,
i.e. the front wall of the fire-box but about the breadth of a brick away therefrom.
By the construction above described one can dispense with the inspection
brick or tile which however if still desired may be set in asbestos in the usual way.
All that is needed, for the purpose of inspection is to remove separate bricks of
the bridge G H or indeed the entire bridge by which the fire-tubes are readily
accessible.
All the parts may be constructed of metal or of fire-clay chamotte, firebricks, etc.
and coated so as to withstand alike the mechanical and chemical action of heat.
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. In a gas-producing furnace for a locomotive marine or other steam generator
the arrangement of an arch c with a sloping comb-shaped bridge or protector G H
placed thereon both formed of refractory material and both acting in combination
with an arch E F arranged on the cover or top of the firebox to divide the same
into a gas producing chamber a fire-chamber a combustion chamber and a flame-

page_text: collecting chamber substantially as described and illustrated in the accompanying
drawings.
2. In a gas-producing furnace such, as described in Claim 1 an arch such as c
which resting upon laterally forwardly projecting cheeks with or without inspection
bricks presents a number of openings such as h arranged at a distance from the
wall of the boiler at the lowest point in order to permit portions of ash or other
residuals to drop from the flame-collecting chamber into the generator chamber
substantially as described and illustrated in the accompanying drawings.
3. In a gas-producing furnace such as described in Claim 1 an arch such as E F
having within it an air-chamber wherein the air passing through tubes such as e
and already therein preliminarily warmed is heated to a high degree and from which
it passes through slots or apertures such as fand 9 into the combustion chamber
and there forms a double veil or curtain (in directions at an angle to each other)
which occupies the entire breadth of the fire-box substantially as described and
illustrated in the accompanying drawings.
4. In a gas-producing furnace such as described in Claim 1 for locomotives the
arrangement of a watertight ash-box and water-holder to receive the necessary
water to produce the steam requisite to support the combustion as well as the
ashes which drop through the grate substantially as described and illustrated in
the accompanying drawings.
Dated this 14th day of August 1895.
BOULT & WADE,
Agents for the Applicant.