IMPROVEMENTS IN GAS-PRODUCING FURNACES FOR BOILERS
Year: 1875

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN GAS-PRODUCING FURNACES FOR BOILERS." -A com-
munication from abroad by Zobeth Sherman Durfee, of New York,
in the Timited abo
PROVISIONAL SPECIFICATION left by the said John Imray at the
Office of the Commissioners of Patents, with his Petition, on the
22nd September 1875.
I, JOHN IMRAY, of No. 20, Southampton Buildings, Ohancery Lane, in
the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN GAS-PRODUCING FURNACES FOR BOILERS," to be
as follows:-
This Invention relates to boiler furnaces in which gas is produced
from the fuel, and the gas being afterwards mingled with air its com-
) bustion is applied to heat the boiler. For this purpose the fire-boxes or
fuel chambers are made of more than usual size and depth so as to

page_text: contain a large body of fuel under slow distilling combustion, and tho
depth being sufficient to ensure the production of carbonic oxide and
hydrocarbons for final combustion; the grates are constructed so as to
give a very large distribution of air within a moderate area of grate.
The fuel chambers or fire-boxes are separated from the compartments
where heat is applied to the boilers by water partitions or fireproof
diaphragms provided with valves for regulating the outflow of the
combustible gases, and between these diaphragms and the combustion
chamber in which the gases are finally burned is placed a combustion
diaphragm of iron or brick or any suitable fire-resisting material, at
such a distance beyond the diaphragm previously mentioned as to allow
the gases issuing from the fuel chamber to pass over and through the
whole surface of the combustion diaphragm which is perforated for
that purpose, and which is placed in such a position with relation to the
surfaces to be heated that there is formed beyond it a combustion
chamber large enough for the complete combustion of the gases passing
through it. These gases are mixed with air in their passage in the
following manner:-The combustion diaphragm is made with tubes
through it for the passage of the combustible gases, these tubes being
surrounded by air spaces or tubes to which air is admitted by suitable
valves, and the air so let into the diaphragm when it is made of iron
prevents it from being overheated, whilst at the same time the air itself
is heated so as to produce rapid combustion when mingled with the
gases.
The air tubes are preferably made to converge towards the gas tubes
so as to produce a focussing of the streams of air and gas, and thereby
ensure a more complete combustion. The supply of air being controlled
by valves, the management of the apparatus is rendered easy.
In some forms of boilers it is advantageous to divide the fuel
chambers into two separate compartments by water diaphragms so
arranged that either of these compartments can be put into com-
munication with the gas distributing chamber at will, and this form is
especially useful when wood, peat, or sawdust, or fuel of like kind is
employed. Boilers thus arranged can however with slight modification
of the grates be applied to burn either wood or coal.
Locomotive boilers may have the diaphragm separating the fuel com-
partment forked, so that an axle can be accommodated in the fork.

page_text: This diaphragm may be made with a valve to shut off from the
front compartment the gases produced in the back compartment, and
thus a constant charge of fuel can be kept in the back compartment
under gas producing condition, but so shut off from the draught as not
5 to produce gas though it retains its heat while the front compartment
is being cleaned.
The valves used in the several diaphragms may be of soapstone, fire-
brick, or other refractory material, or they may be made of iron with a
water circulation through them. The fuel chambers are fed by hoppers
O like the gás producers used for metallurgical furnaces, and have suitable
hand holes for reaching the fuel and stirring it.
As for the distillation of fuel to produce gases for final combus-
tion in a separate chamber it is not necessary to maintain a high heat
in the fuel chamber; it is desirable to use in combination with ordinary
5 grate bars a system of vertical grates with minute perforations in their
sides. These bars may be made of iron or of fire-brick perforated, or, of
fire-bricks made with a mixture of charcoal dust or other combustiblo
matter, so that when burned they become generally porous and give
passage for air over their whole surface. Though this increase of grate
0 surface is necessary on account of the slower combustion of the coal,
yet the complete combustion of the gases afterwards very much reduces
the amount of fuel required.
Gas furnaces of the kind described are applicable to all kinds of boilers,
but most advantageously to tubular boilers, because the purity of the
5 flame developed, its freedom from dust, sulphurous and silicious matter,
and what may be termed its softness and uniformity permit the use of
very small tubes, and no sudden draughts of cold air can pass through
or over the tubes so as to produce strains by their sudden cooling
action.
30 SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Imray in the Great Seal Patent Office
on the 21st March 1876. .
· TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
IMRAY, of No. 20, Southampton Buildings, Chancery Lane, in the County
85 of Middlesex, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of September, in
the year of our Lord One thousand 'eight hundred and seventy-five, in
the thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Imray, Her special 5
license, that I, the said John Imray, my executors, administrators,
and assigns, or such others as I, the said John Imray, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time, and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, 1
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
GAS-PRODUCING FURNACES FOR BOILERS," a communication to me from abroad
by Zoheth Sherman Durfee, of New York, in the United States of
America, upon the condition (amongst others) that I, the said John 1
Imray, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
describe and ascertain 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 2
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Imray, do hereby declare
the nature of the said Invention, and in what manner the same is to bo
performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying 2
Drawings, and to the figures and letters marked thereon, that is to
say :-
This Invention relates to boiler furnaces in which gas is produced
from the fuel, and the gas being afterwards mingled with air, its com-
bustion is applied to heat the boiler. For this purpose the fire-boxes or g
fuel chambers are made of more than usual size and depth so as to
coutain a large body of fuel under slow distilling combustion, and the
depth being sufficient to ensure the production of carbonic oxide and
hydrocarbons for final combustion. The grates are constructed so as to
give a very large distribution of air within a moderate area of grate. a
The fuel chambers or fire-boxes are separated from the compartments
where heat is applied to the boilers by water partitions or fireproof
diaphragms provided with valves for regulating the outflow of the

page_text: combustible gases, and between these diaphragms and the combustion
chamber in which the gases are finally burned is placed a combustion
diaphragm of iron or brick or any suitable fire-resisting material, at
such a distance beyond the diaphragm previously mentioned as to allow
the gases issuing from the fuel chamber to pass over and through the
whole surface of the combustion diaphragm which is perforated for
that purpose, and which is placed in such a position with relation to the
surfaces to be heated, that there is formed beyond it a combustion
chamber large enough for the complete combustion of the gases passing
through it. These gases are mixed with air in their passage in the
following manner :-The combustion diaphragm is made with tubes
through it for the passage of the combustible gases; these tubes being
surrounded by air spaces or tubes to which air is admitted by suitable
valves, and the air so let into the diaphragm when it is made of iron
prevents it from being over heated, whilst at the same time the air itself
is heated so as to produce rapid combustion when. mingled with the
.gases.
The air tubes are preferably made to converge towards the gas tubes
so as to produce a focussing of the streams of air and gas, and thereby
ensure a more complete combustion. The supply of air being controlled
by valves, the management of the apparatus is rendered easy.
In some forms of boilers it is advantageous to divide the fuel
chambers into two separate compartments by water diaphragms so
arranged that either of these compartments can be put into com-
munication with the gas distributing chamber at will, and this form is
especially usefuel when wood, peat, or sawdust, or fuel of like kind is
employed.. Boilers thus arranged can however with slight modification
of the grates be applied to burn either wood or coal..
Locomotive boilers may have the diaphragm separating the fuel com-
partment forked, so that an axle can be accommodated in the fork.
This diaphragm may be made with a valve to shut off from. the front
compartment the gases produced in the back compartment, and thus a
constant charge of fuel can be kept in the back compartment under
gas producing condition, but so shut off from the draught as not to
produce gas though it retains its heat while the front compartment is
being cleaned.
The valves used in the several diaphragms may be of soapstone, fire-
brick, or other refractory material, or they may be made of iron with a

page_text: water circulation through them. The fuel chambers are fed by hoppers
like the gas producers used for metallurgical furnaces, and have suitable
hand holes for reaching the fuel and stirring it.
As for the distillation of fuel to produce gases for final combustion in
a separate chamber it is not necessary to maintain a high heat in the
fuel chamber, it is desirable to use in combination with ordinary grate
bars a system of vertical grates with minute perforations in their sides.
These bars may be made of iron or of fire-brick perforated, or of fire-
bricks made with a mixture of charcoal dust or other combustible
matter, so that when burned they become generally porous and give
passage for air over their whole surface. Though this increase of grate
surface is necessary on account of the slower combustion of the coal,
yet the complete combustion of the gases afterwards very much reduces
the amount of fuel required.
Gas furnaces of the kind described are applicable to all kinds of
boilers, but most advantageously to tubular boilers, because the purity
of the flame developed its freedom from dust, sulphurous and silicious
matter, and what may be termed its softness and uniformity permit the
use of very small tubes, and no sudden draughts of cold air can pass
through or over the tubes so as to produce strains by their sudden
cooling action.

page_text: Fig. 5 shews a vertical section of the aforesaid fuel valve at right
angles to the axis of the boiler, and on line I, J, in Fig. 4.
Fig. 6 shews enlarged vertical sections (taken at right angles to the
axis on the boiler) on lines O, P, and Q, R, in Fig. 7, of a portion
of the grates G.
Fig. 7 shows enlarged vertical sections (taken parallel with the axis
of the boiler) on the lines E, Z, and M, N, in Fig. 6, of a portion of
the grates G.
The fuel used in a locomotive constructed according to this Invention,
as represented in Sheet I., is originally placed in the hoppers H, H, and
the upper lids 1, 2, of the said hoppers, being closed the fuel is admitted
to the interior of the fuel chamber F from time to time as it is required
by raising the valves V, V. The fuel after arriving in the fuel chamber F
in the way and manner aforesaid rests upon the grate G, which consists
of two separate parts, viz., the small grate bars 8, 8, 8, 8, which are
placed in groups, as shown in Figs. 1 and 3, and serve to sustain the
weight of the fuel, and by their removal afford a ready means of
extracting clinkers, ashes, and other refuse remnants of the combustion
of the fuel.
"
The upright portions of the grate G marked in Figs. 1, 2, and 3,
9, 9, 9, serve as distributors of air which is conveyed to them through the
hollow bars or girders on which they rest. These bars have two passages
running their entire length; these passages are separated one from
another by a diaphragm d, as shown in Figs. 2, 3, 6, and 7, and the air
enters the lower passages from the ash pan a through an opening o in
the under side of the said bar, and after traversing the length of the bar
it enters the upper passage in the said bar or girder by passing around
the end of the diaphragm d which divides the bar; the air then enters
the upright air distributors g, g, g, through holes in the upper part
of the bar or girder and corresponding holes in the bases of the air
distributors g, g9, 9, aforesaid. These air distributors are made either of
perforated earthenware, tile, or of any fire-resisting material, sufficiently
porous to air by having some fine combustible material mixed with
their substance when they are moulded, and which subsequently burns
out when the tile is being baked.
The aforesaid tiles are held in the dovetailed groove formed in the
top of the air bars or girders, either by a dovetailed tennon formed

page_text: upon the tile itself, or by a similar tennon formed on a cast-iron frame
over which the tile is placed, and which serves to strengthen the tile as
well as to keep it in place, both of the tennons aforesaid being made
to fit in the dovetailed groove formed in the upper surface of the bar or
girder, as shown in Fig. 6, at x, y. The fuel in the fuel chamber F is
gradually changed into a combustible gas or mixture of gases, by the
heat arising from the combustion of its lower portion, and these gases
pass through the regulating valve R' in the water diaphragm D', into the
space S¹, and thence through apertures in the combustion diaphragm D
to the combustion chamber C.
The combustion diaphragm D is made of fire-brick or other fire
resisting material, and the apertures aforesaid through which the gas
passes are placed between other apertures or passages through which
air is admitted to the combustion chamber C; the amount of air admitted
by the said air passages is regulated by the valve v¹ at the lower end of
the air passage p. Now when a proper combination of the gas and
air takes place in the combustion chamber C (and the proportions of
the gas and air are easily regulated by means of the gas regulating
valve R³, and the air regulating valve o' aforesaid) a perfect combustion
of the gas ensues, attended with the evolution of great heat, which in its
passage through the tubes T is transmitted to the water in the boiler,
resulting in a rapid and economical generation of steam.
The Drawings on Sheet II. represent the said Invention as applied to
a locomotive boiler in a different manner to that just described. Fig. 1
of the said Sheet II. represents a vertical cross section at right angles
to the axis of the boiler taken through the fuel box F" and grates G' on
line G, H', in Fig. 4.
Fig. 2 represents a half plan of the boiler as seen from above, and
also a half horizontal section of boiler taken on the line A, B, in
Fig. 4.
Fig. 3 represents a vertical cross section at right angles with the axis
of the boiler taken through the fuel box F¹ and grates G³, in Fig. 4.
Fig. 4 represents a vertical longitudinal section through the axis of
the boiler, showing the tubes T, combustion chamber C, combustion
diaphragm D, fuel boxes F1 and F", with their dividing water partition
P and its gas regulating valve and the fuel hoppers H', H". In this

page_text: arrangement the fuel used is originally placed in the fuel hoppers
H³, H", which are provided with hinged lids at their tops and with
bottoms b, b, which may be opened or closed by turning about an axis
situated at or near one of their edges. These bottoms are by preference
made hollow in order to keep them cool by means of a current of cold
water which traverses the axis on which they turn, and circulates through
the interior of the hollow bottom.
By means of the moveable bottoms. b, b, of the hoppers H², H", the
fuel can be supplied to either of the fuel boxes F¹, F", as occasion
requires. The fuel in each of the said fuel boxes F¹, F", is sustained
upon the small grate bars 8, 8, 8, 8, Figs. 1, 3, and 4, and covers the air
distributing bars 9, 9, I.
The construction of the grates 8, 8, 8, 8, and the air distributing bars
9, 9, 9, aforesaid is more clearly represented in Figs. 1, 2, and 3 on
Sheet III., in which it will be seen that the smaller grates 8, 8, 8, are
made in sections, each section being hung in recesses or bearings formed
in the air distributing bars 9, 9, 9, by trunnions t, t, t, cast or otherwise
attached to the sides of the sections of the small grates 8, 8, 8. The
sections of the small grates 8, 8, 8, aforesaid can be made to oscillate on
the trunnions t, t, by means of bars attached to eyes e, e, e, on the
under sides of the several sections of small grates 8, 8, 8, as shewn in
Fig. 2, Sheet III., and which bars are represented in their proper place
at b³, b¹, b', in Sheet II., Figs. 1, 3, and 4.
.
By means of the oscillating or tilting motion of the small grates as
aforesaid they can be cleared of ashes and all solid waste products of the
combustion of the fuel resting upon them. ·
The air distributing grates or bars 9, 9, 9, Figs. 1, 2, and 3, Sheet II.,
are more clearly represented in Sheet III. by Figs: 1, 2, and 3, and
consist of hollow bars of cast iron whose interior is in direct com-
munication with the air in the ash pan of the locomotive by means of
an opening or openings in the lower edge of the bars, as shown. This
air finds its way to the fuel through perforations in the sides of the
hollow bar or girder, as shown at p, p, in Figs. 2 and 3 of Sheet III.
The gases are driven off from the great mass of the fuel by the heat
evolved in the combustion of its lower portion which rests upon the
grates 8, 8, 8, aforesaid, and that part of the said gases which is evolved.

page_text: from the fuel in the rear fuel box F" (Fig. 4, Sheef II.), pass through
the openings V in the water partition P, which opening can be graduated
or entirely closed by a regulating valve, as shewn in the Drawing. The
gases from the rear fuel box F", after passing through the opening V in
the water partition P, commingle with the gases generated in the fuel
box F, and the mixed gases then pass through the combustion
diaphragm D; or in case the opening V in the water partition P is
entirely closed, then the gases produced in the front fuel box F¹ pass
alone through the combustion diaphragm D.
The object contemplated by dividing the fuel into two portions by
means of the water partition P is as follows, namely, that when the
engine is standing unemployed for any length of time the opening V
may be entirely closed by the valve c, shown in Fig. 4, Sheet II., thus
checking the rapidity of combustion and consequently the generation of
gas in the fuel box F", and permitting the entire removal of the fuel
from the fuel box F¹ which may then have a fresh fire laid ready for
starting at any time when it is desired to put the engine into service,
the fuel and fire remaining in the fuel box F" being sufficient to start a
rapid generation when desired by opening the valve c which closes the
opening V in the water partition P, thus allowing the gas generated in
the fuel box F" to pass through the fuel box F¹ to the combustion
diaphragm D. In this diaphragm the passages for the gas are placed
between those for the air and the surface of the cast iron portion of the
said combustion diaphragm which is next the combustion chamber C is
provided with a protection of fire-brick or other fire resisting material:
m, in and through which are passages for the gas and the air, which is
introduced into the hollow iron portion of the combustion diaphragm
through the opening o and passage p in the front part of the fuel box
F', the opening o being capable of regulation by means of a hinged
valve »', as shewn in Fig. 4, Sheet. II.
The construction of the combustion diaphragm aforesaid is represented
with more clearness in Figs. 4, 5, and 6, of Sheet III. in which Fig. 4
shows in its upper half the plan of the lower side of the combustion
diaphragm, and in its lower half a sectional plan of the iron portion of
said combustion diaphragm taken parallel with its under side.
Fig. 5 shows a cross section of the combustion diaphragm taken on
line A, B, of Fig. 4, and exhibits the arrangement of the gas passages

page_text: combustion chamber C resulting in the generation of great heat, the
ignited and highly heated gases passing through the tubes T on their
way to the chimney.
Figs. 4, 5, and 6, Sheet V., represents the Invention as applied to
another form of upright tubular boiler of a different construction.
Fig. 4 represents two vertical half sections through the axis of the
boiler, the left-hand half section being taken along the line A, B, in
Fig. 6, and the right half section being taken along the line C, D, in
Fig. 6. These sections shew the tubes T, the combustion chamber O',
the combustion diaphragm D¹, the water diaphragm W', with its
opening O regulated by the sliding valve V; they also show the fire
or fuel box F', and the grates G, the fuel hoppers H³, and water
space W, W.
Fig. 5 shows two horizontal half sections at right angles to the axis
of the boiler, the upper half of the Figure being a section taken along
line G, H, in Fig. 4, and the lower half being a section taken along the
line I, J, in Fig. 4. These section show the hopper H', the door D",
the water space W, and the water diaphragm W₁, the gas regulating
valve V, and the grate G¹.
Fig. 6 shews in its upper half a half plan of the boiler, and in its
lower half a half horizontal section on line E, F, Fig. 4, and exhibits
the tubes T, the fuel hoppers H', H', and the water space W, W, and
the combustion diaphragm D', whose construction and function is sub-
stantially the same as that shewn on Sheets I. and IV., it being composed
of fire-brick or other fire-resisting material, having perforations for the
passages of the gas placed between similar perforations for the passage of
air. In this arrangement the fuel being put in the fuel hoppers H¹ is
introduced into the fuel or fire-box F³, where it is supported by the
grates G³, and the combustible gases generated from the great mass of
the fuel in the fuel box F1 pass through the opening O in the water
diaphragm W' (the amount so passing being regulated by the sliding
valve V), and through apertures in the combustion diaphragm D', which
apertures are placed between other apertures for the admission of air,
and the comparatively minute streams of gas- and air combine in the
combustion chamber O', and when this mixture of gas and air is ignited
the result is the evolution of great heat, which is transmitted to the
water in the boiler by means of the tubes T.
"

page_text: There are many advantages peculiar to this Invention, such as
diminished wear and tear of the boiler, more rapid and manageable
generation of steam, a greater economy in the use of fuel, and con-
sequent economy in steam production, and the ability to use any kind
of.solid fuel for the production of the gases used, and in the carrying of
this Invention into practice it will be found possible to use much smaller
tubes than are usually employed in boilers of large size; these tubes,
owing to their small size, can be made thinner, and will transmit heat to
the water in the boiler from the burning gases with greater rapidity than
tubes of ordinary size and thickness, and because of the absence of any
cutting action from dust or fragments of fuel the tubes can be made of
copper or brass, which are well known to be better conductors of heat
than either iron or steel.
Among the various kinds of solid fuel available for use in connection
with this Invention is that known as
"
slack
66
or small coal," such as
is produced at the mines in the process of preparing coal for the market,
and which can be obtained in large amounts at small cost.
Having thus described the nature of this Invention, and in what
manner the same is to be performed, as communicated to me by my
foreign correspondent, I claim,-
First. The construction of gas-producing furnaces for boilers with
fuel and combustion chambers contained within the water walls of the
boiler divided by diaphragms, through which all the gases generated
in the fuel chambers, as well as the air for effecting their combustion,
pass into the combustion chamber, and are there consumed, substan- 1
tially as herein described.
Second. The construction of gas producing furnaces, such as arc
referred to in the first claim, with gas distributing chambers between
the fuel chambers and the gas burning diaphragms, substantially as
herein described.
Third. In gas producing furnaces, such as are above referred to, tho
use of hollow metal diaphragms having transverse passages, through
which the combustible gases pass from the fuel chamber into the com-
bustion chamber, while the air for effecting their combustion circulates
round the said passages inside the diaphragm, so as to become heated &
before issuing through openings in close contiguity to the opening of
the gas passage, substantially as herein described.

page_text: Fourth. Constructing gas producing furnaces, such as are referred to
in the first claim, with two or more fuel chambers separated by water or
other heat resisting diaphragms provided with valves, whereby the fuel
chambers may either be entirely separated or allowed to communicato
with each other and with the combustion chamber, substantially as and
for the purposes herein described.
Fifth. The use of the water partition, shewn in Fig. 4, Sheet II., at P,
whereby a large area of grate surface can be provided in gas producing
furnaces for locomotive boilers without increasing the wheel base of said
locomotives.
Sixth. The construction of combustion diaphragms for gas producing
furnaces for boilers, either entirely of fire-brick or other fire resisting
material, or of a combination of iron and fire-brick or other fire
resisting material, substantially as shewn in the several accompanying
Drawings.
Seventh. The use in gas. producing furnaces for boilers of porous
grates for generating gas for fuel, and for consuming or distilling fine
coals and other finely comminuted fuel made from fire-brick or other
suitable refractory materials, substantially as herein described and shewn
on the Drawings.
on the Drawings.
Eighth. The combination with ordinary grate bars of vertical porous
or perforated grates running parallel to each other through gas pro-
ducing furnaces, substantially as and for the purposes herein
described.
In witness whereof, I, the said John Imray, have hereunto set
my hand and scal, this Twentieth day of March, in the year of
our Lord One thousand eight hundred and seventy-six.