Year: 1867

page_text: perfect combustion of the fuel is effected, the maximum meat developed, and
smoke entirely superseded, Now according to these improvements the fuel
undergoes or is subject to two states of combustion during its consumption in
furnaces of this improved construction by passing through two combustion
chambers, the first being that where the solid coal or other fuel is ignited and
carbonized and the gases set free, the second combustion chamber being arranged
to receive and burn the combustible gases so driven off, aided by the intro-
duction of a given volume of air, the heat and products of combustion passing
off from the combustion chambers through suitable flues to the boiler or other
purpose to which the heat derived from the combustion of the fuel is required
to be applied. For this purpose the furnace is constructed with a feeding
or carbonizing passage or chamber, by preference of conical form, composed
of fire-brick or other suitable material, and under which is arranged a fire-grate
with moveable fire-bars capable of having movement imparted thereto in order
to agitate the fuel and discharge the ashes from time to time as required,
The charging chamber acts as a coking oven to the fuel, and has openings
formed in it through which the gases escape, the incandescent fuel
gradually
descending on to the grate below, which is of much larger area than the base
of the charging chamber. Openings are arranged in the front and sides of
the furnace for the introduction of a poker to stir and separate the coke when
required. A steam pipe is introduced under the fire-grate perforated with
small holes, through which the steam escapes to lower the temperature of the
furnace, and thus prevent the vitrification of the ashes from time to time as may
be required. The entrance to the second combustion chamber is of suitable
capacity to admit of the complete admixture of the gases and air before passing
over the fire bridge into the chamber of combustion, from which the heat and
products are conducted to the boiler or other place where the heat is required
to be applied. The charging is effected by means of a hopper closed by a
cover, a pipe from the hopper passing to a draft hole or passage into the furnace
through which the fumes which may occasionally escape from the hopper are
drawn. The draft hole is covered by a valve so as to regulate the admission
of the air passing through it. The fuel may be pressed down the hopper into
the charging chamber if necessary by means of a weight acting as a piston
suspended by a chain above the hopper and passing downwards over a barrel
actuated by a winch.
The action of the furnace is as follows:-The charging chamber being
filled with coal or other fuel and the cover to the hopper closed the flames
which rise from the fire on the grate below heat the sides of the charging
chamber, maintaining the same at a red heat; the fuel therein undergoes

page_text: ¡ are
part with all the vapours and gases it
contains, which then descend into the hottest part of the furnace, where
all the bituminous matters and hydrocarbons rich in carbon are decomposed
the high temperature, being partly burnt and mixed with the gases which
continuously produced at this point. The combustion which takes place
upon the fire-grate is incomplete, owing to the exce-s of combustible material
at that point, and which acts to transform a considerable portion of the
carbonic acid first produced into oxide of carbon. The products of this
combustion and of the carbonized fuel (after having in their passage heated
the sides of the charging chamber) are intermixed with a current or currents
of air, and pass over the fire-bridge into the second combustion chamber for
the gases and air thus combined. The large area of this chamber has the
effect of retarding the speed and producing disturbances in the gaseous body,
which favours the intimate mixture of the combustible gases at the same time
that the retardation of the speed of the current prolongs the time of admixture
and the contact of the gases with the sides of the chamber, which are at a
very high temperature, thus favouring their complete combustion.
capacity of the combustion chamber should be as large as possible consistent
with the size of the furnace, and the gases should remain a sufficient time
therein to admit of their complete combustion, and the capacity of the com-
bustion chambers should be equal to the volume of air passing through the
furnace during a given time, by preference from four to five seconds. It
is preferred to form the grate with moveable fire-bars which may be readily
taken out and cleaned when required, and there is no objection to the grate
being comparatively large, as the gases which do not burn at this point are
burnt in the second combustion chamber by the aid of the draft hole or holes.
In order to enable the fire-grate to be temporarily removed or withdrawn a
false
The
grate may be interposed between it and the fuel, so as to support the
combustible materials in the furnace, and thus admit of the grate being
lowered and removed for the purpose of cleaning; or the fire-grate may be
placed upon a truck so as to move in and out upon rails arranged in the
ash-pit.
From the previous description it will be seen that the fuel introduced to the
furnace through the cbarging chamber is subjected to a heating and carbonizing
process; the gas is evolved, being conducted into the hottest part of the
furnace to effect their decomposition. The heated and carbonized fuel is fed
uniformly to a grate of fire-bars of considerable extent, from which the
products are liberated upon the inner surfaces of the chamber, thus equalizing
the combustion upon the grate, at the same time heating and carbonizing the
gaseous

page_text: new fuel previous to its more perfect combustion in a second furnace where
all the conditions are combined for obtaining the perfect combustion of all
the gases, the consumption of smoke being also by these means effectually
accomplished.
Furnaces constructed in accordance with the improvements previously
described may be adapted and applied to various purposes; as, for instance,
to marine, locomotive, and other boilers, the parts being modified in form and
construction to suit the particular purpose for which the furnace is required,
and the description of fuel consumed therein. Puddling, reheating, and
other furnaces employed in metallurgical processes may also be constructe
in accordance with these improvements, being also applicable to furnaces
for melting glass, annealing porcelain, pottery, soldering and other ovens,
to gas retorts, and to various other manufacturing and chemical processes and
purposes wherein furnaces are required for the application of the heat generated
therein.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Garrett Tongue in the Great Seal Patent Office on
the 20th November 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
GARRETT TONGUE, of the Firm of Tongue and Birkbeck, Patent Agents
and Engineers, of 34, Southampton Buildings, Chancery Lane, in the County
of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of May, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Garrett Tongue, Her special licence that I, the said
John Garrett Tongue, my executors, administrators, and assigns, or such
others as I, the said John Garrett Tongue, my executors, administrators,
and assigns, should at
any time
any
agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
Jawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN THE ARRANGEMENT AND CONSTRUCTION OF FURNACES FOR
STEAM BOILERS AND VARIOUS OTHER USEFUL PURPOSES," a communication to me
from abroad by Emmanuel Minary, Engineer, of Besançon, in the Empire of

page_text: or
urnaces.
France, upon the condition (amongst others) that I, the said John Garrett
Tongue, my executors or administrators, by an instrument in writing under my,
, or one of their hands and seals, should particularly describe and ascer-
tain the nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said John Garrett Tongue, do hereby
declare the nature of the said Invention, and in what manner the same is
0 to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
The conditions it is proposed to realize for the perfect combustion of and
production of the maximum of beat from fuel (and which have led to these new
and improved arrangements of a double combustion smoke-consuming furnace
which forms the object for the grant of these Letters Patent) result from the
following statement of facts :-Fuels are composed in different proportions of
two bodies, hydrogen and carbon, with which are found associated inert
bodies fusible or not, as the case may be, which form the ashes. Hydrogen
and carbon are nearly the only combustible elements of these materials, and are
0 the only ones which admit of utilization. The combustion of hydrogen only
takes place in one way, that is to say, it forms in its combination with the
oxygen of the air but one stable combination which is the vapour of water.
Carbon on the contrary is capable of two distinct combustions, that is to say,
it forms with oxygen two combinations as one or other of these bodies is
5 furnished in greater abundance (during the process of combustion), these
are the oxide of carbon and carbonic acid. If air is supplied in excess to
the ignited carbon it forms carbonic acid, a different result takes place if the
body of fuel is of considerable depth when oxide of carbon is formed owing
to an excess of carbon. The carbonic acid traversing or passing through the
30 incandescent carbon is decomposed by it and transformed into oxide of carbon.
The same phenomenon is produced with aqueous vapour, which under similar
circumstances is decomposed and takes the form of hydrogen and oxide of
carbon. From an examination of these chemical properties it may be con-
cluded that all the combustibles cannot be completely consumed without
35
passing
successively
through two combustion chambers or furnaces, the first
being that where the solid fuel is ignited and where its presence in a solid
state always results in the partial transformation of the aqueous vapour and
of the carbonic acid (resulting from the combustion of the lower bed) into
hydrogen and oxide of carbon gases highly combustible and of great heating

page_text: power.
The second combustion chamber or furnace having no other object
than the burning of the combustible gases arising from the first by the
introduction of a suitably proportioned volume of air and allowing the burnt
gases to pass away, and these exhausted gases not being again brought in
contact with the incandescent carbon are no longer liable to be again decom- 5
posed. Independently of these theoretical considerations there are others
which from a practical point of view have a real importance, and it is hereby
sought to find a rational solution to the problem of perfect combustion,
satisfying the following conditions:
Firstly, to obtain from the fuel all the caloric which it is capable of yielding
by its perfect combustion, consequently to cause it to undergo the two con-
bustions to transform the hydrogen into aqueous vapour, the carbon into
carbonic acid, to profit by the heat emitted in these two cases, and in consequence
to obtain the suppression or prevention of smoke.
Secondly, to arrange a furnace which it will not be necessary to open when
charging in order not to lose heat by radiation, not to introduce useless and
cold air by the opening, and not to throw cold and damp fuel upon that which
is incandescent, for that purpose to arrange a furnace with a grate of bars of
which the charging shall be regular, that is to say, in constant proportion to
the rate of combustion, and which shall bring the fuel constantly into the
furnace in one even state of preparation and temperature, so as to maintain
the combustion under absolutely identical and constant conditions.
Thirdly, to arrange the apparatus so as to first carbonize the fuel, that is to
say, in the first place disengage the vapours and gases which are contained
in it before the fuel arrives at the point of ignition; to direct these gases and
vapours into the hottest part of the furnace in order to decompose them and
render them easier of combustion, and afterwards to pass away with the other
products of combustion.
Fourthly, to avoid the formation of clinker or slag caused by the vitrification
of ashes by the high temperature of a too-active combustion upon the grate
bars by increasing the bar surface of the grate so as to reduce the volume of
air passing through each square inch, and thus diminishing the activity of the
combustion.
The lowness of the temperature resulting from this increase of surface
tends to prevent the scorification of the mineral matters contained in the
fuel.
And in order that the nature of the said Invention may be most fully
understood and readly carried into practice I will proceed to describe the
Drawing hereunto annexed.

page_text: Figure
furnace as
IN THE DRAWING.
section taken through the centre of this improved
applied to the heating of a steam boiler; Figure 2 is a transverse
section; Figure 3 is a plan, and Figure 4 is a horizontal section taken at
5 the line 1, 2, (Figures 1 and 2).
A is a charging and carbonizing receptacle or chamber of fire-brick under
which is arranged the grate B, the fire-bars of which are moveable by means
of the levers C¹ fixed upon the axes c, upon which are fixed the small arms c',
and these arms c act to raise the bars a short distance and so cause the ashes
charging column A is in eff et a coking oven pierced with
10 to fall; this
openings a, a', in the sides so as to communicate with the flues D and D¹ in
order to facilitate the disengagement of the distilled gases, and which otherwise
would be obliged to descend to escape below. This arrangement by hastening
the conversion of the coal into coke preserves its permeability when upon
5 the grate. The conical form of the coking oven is adopted because the
descent of the combustible may not be too rapid, and that it may not by
consequence sink into a heap upon the grate; this resuit is obtained by
making the base four-ninths of the size of the area of the furnace bars, that is to
say, for example, a grate of oths of a yard in the sense of the length of the
0 bars; the interior measurement of the coking oven at the higher line of the
flues should only be ths of a yard. The openings d arranged in front of
the furnace admit of the introduction of a poker, by means of which the coke
can be divided and fall uniformly upon the grate when required. To lower
the temperature of the furnace, and also to prevent the vitrification of the
5 ashes, and the destruction of the interior, a small jet of steam is introduced
under the fire-bars by the iron pipe e, Figure 1; this pipe is pierced with
small holes through which the steam escapes. The decomposition of the
steam by coming in contact with the incandescent coke produces a sufficient
lowering of the temperature, and this can be regulated by the opening of
is hindered by this cooling, and
tap. The scorification or formation of slag is hindered
the combustible gases which result from the sudden enlargement of the
entrance of the chamber of combustion effect sufficiently the mixture of the
air and the combustible gases. It suffices then to give to this chamber
5 time for their complete combustion. At the outlet of the collec tn g
sufficient capacity for the gases to remain four or five seconds to give
flues D the gases pass over the bridge D', and from thence into the
combustion chambers E and E¹, and from thence under the boilers; the
furnace is charged by means of the cast-iron hopper F, which is closed
0

page_text: by means of the cover F¹. In the higher part is a pipe F, the opening of
which is near the opening g, through which may be drawn into the furnace
the fumes which otherwise may escape by the hopper. The opening of
the draft hole ("combinateur") is covered by the cast-iron closing
apparatus g', which is actuated by means of the hand lever G in such manner
as to vary at will the size of the aperture by which the air is introduced into
the apparatus. The arrangement of this charging hopper above described
serves for large apparatus, but for small ones it would be useful to add the
apparatus indicated by red lines, particularly in cases when coal is used of a
bituminous character and liable to cake up into a mass. This apparatus 1
consists of a kind of piston P suspended by the chain p coiled around the
small barrel T, upon the axis of which is mounted the winch handle M, and
if by the aid of this winch the pistou is made to descend into the charging
hopper pressure is produced upon the fuel which causes it to descend. It
will be readily understood that the weight of this piston must be determined
by experience in the various cases in which it is applied.
The following is a description of the operation of the apparatus :-
The fuel, coal, coke, turf, lignite, or other combustible material is intro-
duced into the charging box F until it is filled, when the hopper is closed by the
cover F. The flames which rise from the fire upon the grate B by the flues D
heat the sides of the charging chamber or coking oven, and maintain them at a
red heat; the new fuel introduced is heated and undergoes carbonization,
which causes it to part with all the vapours and gases which it contains,
these vapours and gases which can only escape from below being obliged to
take the direction which tends to favour the descent of the tar which lubricates
the surfaces; these gases and vapours then descend into the hottest part of
the furnace, where all the bituminous matters and the hydrocarbons rich in
carbon are decomposed by the high temperature partly burnt and mixed with
the gases which are continuously produced at this point. The combustion.
which takes place upon the grate bars is incomplete in consequence of the
amount of the fuel at that point, and which transforms a considerable portion
of the carbonic acid first produced into oxide of carbon. The products of
this combustion and those of the carbonization after having in their passage
in the flues heated the charging chamber passing over the fire-bridge D¹ are
intermixed with the current of air introduced through the air passage g
with which they interinix in circulating in the chamber of combusti on E.
The large area offered by this chamber for the circulation of the gases has
the immediate effect of retarding the speed and producing disturbances in the
gaseous body which favours the intimate mixture of the air and the combustible
and

page_text: gases
at
Same
the retardation of the speed of the current
prolongs the time of admixture and the contact with the sides of the chamber
which is at a very high temperature and eminently favors the complete combus-
tion. The capacity of the combustion chambers should be as large as possible;
s should remain in them a sufficient time to be completely burnt, for the
5 the gases
process of combustion requires a certain time for its perfect accomplishment.
The necessary conditions for the perfect combustion of bodies are not
generally known, but it is supposed that if mixed without precaution with
the necessary volume of air, and then ignited, they will be completely burnt;
0 it is a great error, for the inflamed gases are easily extinguished, that this
is so easily demonstrated by placing a lighted jet of gas a glass tube large
enough for the draught caused by the heat of the flame to enter it with
one from the atmosphere the gas is extinguished and smoke immediately
appears above the tube; the contiguity or contact of cold bodies extinguishes
them, the increase of speed of circulation exercises the same influence;
probably because the mixtures are made with more difficulty; it is evident
by this that the combustion of these bodies requires precautions and conditions
which ordinary furnaces do not present. The combustion chambers are
intended to realize these conditions, and in order that they may be successful
the capacity of these chambers must be equal to the volume of air which
passes through the furnace during four or five seconds of time, in other words,
for a furnace which burns twenty-five "grammes" per second with two
hundred " litres" of air the chamber of combustion must be given a capacity
of a cubic metre." It is also evident that the undue enlargement of this
capacity would result in the augmentation of the exterior cooling surfaces to
a useless degree, it is therefore desirable to effect the complete combustion
and not to exceed what is necessary. The grate composed of moveable
fire-bars which can be taken out and replaced at will allows the apparatus to
be readily cleaned. In the ordinary furnaces the grate cannot be made of
large dimensions, because at the moment of firing it produces abundance of
smoke by reason of the large surface over which the coal is distilled, a
considerable quantity of gas is liberated, and there is consequently an
insufficient draught which is always the result of the enlargement of the
grate. The chimney requires a supply of air in accordance with its section,
its height, and its interior temperature. Of the volume of airp
larger grate the current is weak; if, on the contrary, the grate is small the
current is rapid, but in the latter case the intensity of the heat is augmented
the ashes which are not broken up even upon a large grate vitrify upon the
66
passes through a

page_text: ender
fire-bars of a small one and
wasteful by reason of the cooling which is the consequence. By this improved
system there is no objection to making a large grate. The gases which do
not burn at this point are burnt in the combustion chamber by the aid of
the draft hole g; with large grates in furnaces of this construction no vitrification
and no more clinkers will be formed, the ashes falling in powder, whereby the
cleaning will be seldom required and the necessary attendance but trifling;
this furnace is applicable to all purposes where heat is required, and
particularly to the marine service and to locomotives, but it will be evident
that its arrangement and construction will have to be adapted to the actual
requirements; thus, in locomotives the coking oven for coke will have to be
modified, the coniety or the inclination of the sides would have to be arranged
inversely, the vibration accelerating the descent of the fuel in this part; it
would become necessary to counteract this effect by an inclination which
will require to be determined by circumstances. The grates will likewise be
subject to modifications by reason of the nature of the fuel to be consumed,
for instance, for consuming coal of very inferior quality containing about
twenty-five per cent. of ashes the iron plate upon which the furnace is built
is so arranged that a false grate composed of iron bars indicated by red
lines in Figure 1 can be introduced to support the fuel in the furnace and
allow of the lowering of the grate and its complete cleaning; this false set
of grate bars allows of a still better arrangement, which is to place the ordinary
grate upon a truck moving on rails placed under the ash-pit, and by bringing
out this grate from under the false grate its rapid and easy cleaning can be
effected. After cleaning the grate may be replaced under the furnace and
the bars of the false grate be withdrawn. It may also be observed that the
combustion will be retarded during the cleaning, and that consequently this
operation may be effected with all the care desirable, since there is no fear of
lowering the temperature while it is conducted.
as,
It will be seen by the previous description that the improved arrangement
of double combustion furnace (which is the subject of the grant of these
Letters Patent) has for its object,
First, to submit the fuel or combustible bodies (which are introduced first
by a charging apparatus) to a heating and carbonizing process, and to conduct
the resulting gases into the hottest part of the furnace in order there to effect
their decomposition as herein described.
Second, to feed uniformly the heated and carbonized fuel to a grate of
large surface from which the gaseous products are liberated upon the two

page_text: пасея.
er, the combustion upon the grato surface being
equalized, the products acting to heat and carbonize the new fuel, and after-
wards being consumed in a second furnace, where all the conditions are united
for obtaining the perfect combustion of all the gases; smoke being the result
of the condensation of the non-decomposed products from the distillation of
coal, and other combustible bodies imperfectly burnt in the furnace, such
smoke will not be produced in the improved apparatus previously described.
These furnaces are applicable to heating steam boilers of all descriptions in
metallurgy, to puddling and reheating furnaces, to glass annealing ovens, to
procelain and pottery ovens, to gas retorts, and to all other purposes whero
heat is required and by which it is possible to obtain at will oxidizing or
reducing flames, a valuable property in the puddling of iron and in the baking
of pottery ware coated with fusible enamel. This furnace will require modi-
fications according to the purpose for which it is applied, and for example
that the combustion chamber may be considerably reduced when the coking
chamber is required to be at a very high temperature, as in a soldering oven
for example, may serve itself for the combustion chamber,
In witness whereof, I, the said John Garrett Tongue, have hereunto
set my hand and seal, this Twentieth day of November, in the year
of our Lord One thousand eight hundred and sixty-seven.
JOHN GARRETT TONGUE.