Improvements in and relating to Steam Boilers and Chimneys.
Year: 1894

page_text: Date of Application, 25th Apr., 1894-Accepted, 11th Aug.,
1894
COMPLETE SPECIFICATION.
Improvements in and relating to Steam Boilers and Chimneys.
I, ALFRED ROSLING BENNETT, of 22 St. Alban's Road, Harlesden, in the
County of Middlesex, Engineer, 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 steam boilers and chimneys and comprises the
improvements hereinafter described.
An important feature of my invention relates to the provision of a supplementary
furnace intermediate of the ordinary or main furnace or fire-box and the smoke-box
or chimney, and I so arrange that the gases from the main furnace pass through
such supplementary furnace in such a way that in some of the forms of construction
hereinafter described they do not mingle at all and in some other forms of con-
struction mingle but slightly with the gases resulting from combustion in the said
supplementary furnace.
Another important feature of my invention relates to the provision of two or
more blast pipes discharging through two or more chimneys and in some cases
I divide the smoke-box into two or more compartments, in order to obtain a more
efficient blast for the furnace or furnaces.
My invention also comprises an improved apparatus for rendering and
maintaining homogeneous and constant in quantity the fuel supplied to the
furnace.
In steam boilers of the type known as locomotive in which the greater part
of the heating surface consists of flues or tubes surrounded by water through
which tubes the products of combustion in the furnace are conducted to a
smoke-box or outlet, the evaporative efficiency of the heating surface diminishes
rapidly as the distance from the furnace or fire-box increases since the gases
become cooled during their passage through the flues or tubes. According to my
present invention the more distant parts of the flues or tubes are made to transmit
a greater proportion of the total heat to the water than has hitherto been the case
and I can thereby construct a boiler which has a greater evaporative power in
proportion to its weight and size than the boilers now in general use.
In carrying out the first part of my invention I make a boiler having flues or
tubes divided into two lengths, sets or sections and having interposed between such
sections an intermediate chamber. The gases from the furnace enter this inter-
mediate chamber by the first section of flues or tubes leading from the fire-box to
the intermediate chamber and leave by a second section of flues or tubes leading
to the smoke-box. Such intermediate chambers have been used on the London
and South Western and the London and North Western Railways and are well
known to engineers by the name of combustion chambers. Instead of one
intermediate chamber there may be two or more.
According to my invention I so construct the intermediate chamber that it
becomes in part a second or supplementary furnace. In addition to constituting a
flue or passage for the main fire gases as in locomotives on the aforesaid railways
it contains, or is in connection with, a seat of independent combustion the gases
from which do not mix or mingle intimately with the gases from the main furnace
or fire-box. In some of the forms of construction hereinafter described the two
sets of gases do not come in contact at all and in some other forms of construction
they come in contact but mingle only slightly, and in all cases each set of gases
follows an independent route through different flues or tubes in escaping from the
intermediate chamber to the smoke-box or chimney.

page_text: This separation of the two sets of gases is essential to my invention since were
they permitted to mix the carbonic acid and carbonic oxide of the main fire gases
would prevent the maintenance, or materially reduce the efficiency, of the com-
bustion in or in connection with the intermediate chamber.
When the two sets of gases are kept apart the 'object of my invention, which is
to increase the evaporative efficiency of the heating or tube surface furthest
removed from the fire-box, is attained in the following manner. By the time the
main fire gases have passed through the first section of tubes and have reached the
intermediate chamber they have parted with a large portion of their original heat
and are therefore reduced in volume. In this cooled and contracted state they do
not require the same amount of flue or tube area and it will suffice if only a portion
of the tube area between the intermediate chamber and the smoke-box is reserved
for their passage.
In this cooled state the amount of evaporation produced in
passing through the tubes intervening between the intermediate chamber and the
smoke-box is vastly less than that already obtained in traversing the tubes between
the fire-box and the intermediate chamber.
Now if a seat of independent combustion is maintained in or in connection with
the intermediate chamber the conditions will be greatly modified inasmuch as the
interior surfaces of the intermediate chamber and the surfaces of its deflectors will
be kept at a high temperature by this combustion and in passing over the said
surfaces the cooled main fire gases will be re-heated and rendered capable of
producing a better evaporative effect in the tubes between the intermediate
chamber and the smoke-box.
The gases from the secondary seat of combustion are intended to be conveyed to
the smoke-box or chimney either by the tubes not required by the main fire gases
or by additional tubes. In either case the said secondary furnace gases will
produce a powerful evaporative effect in the second or distant section of the boiler
which according to present modes of construction is always the least effective..
Especially will this be the case if the gases from the second furnace are made to
traverse tubes situated below those conveying the comparatively cool main fire
gases owing to the rapid circulation of water in the boiler which will be then set
up and to the sweeping of the upper tubes by steam liberated from the lower.
In those forms of construction hereinafter described in which separate com-
partments, channels or.tubes are not provided for the conveyance through or across
the supplementary furnace of the main fire gases without mixture or mingling with
the gas generated in the supplementary furnace an essential part of my invention
is the provision of deflectors or baffle plates in the supplementary furnace by means
of which the gases from the main furnace are directed so that they do not mix to
any great extent with the gases arising from the combustion in the supplementary
furnace. In some forms of construction 'I provide tubes or flues in the supple-
mentary furnace through which tubes or flues the main furnace gases pass. When
this is not done, the two sets of gases are compelled by the said deflectors and
baffle plates and by the influence of the draughts maintained through the respective
furnaces and through the boiler to travel in two independent layers touching only.
at their inner surfaces. Fuel is supplied to the supplementary furnace by injecting
thereinto, preferably against suitable fire-brick walls or surfaces, jets or sprays of
oil, petroleum, tar or naphtha refuse, coal-dust, gas, or other suitable inflammable
or combustible liquid, solid or gaseous matter together with as much atmospheric
air or oxygen as inay be necessary for its combustion. The injection of the fuel
may be performed by suitable injection apparatus, such as the so-called spray
injectors employed by Mr. Thomas Urquhart on the Grazi and Tsaritsin Railway
of Russia and by Mr. James Holden on the Great Eastern Railway of England
for injecting similar combustible matter into the main furnaces or fire-boxes of
locomotive steam boilers. I do not, however, confine myself to such methods as
the mode of injecting combustible matter may be greatly varied. The air or
oxygen supplied with the combustible matter may be with advantage led to the

page_text: injecting apparatus magpipes pie
or in the smoke-box so that it may be heated on its way as is well understood.
A boiler constructed according to my invention with a supplementary furnace
fitted with spray injectors may consume ordinary fuel'such as coal, coke or wood
in its main furnace or fire-box. Or both furnaces may be fed with liquid or
powdered fuel by injectors as hereinabove described.
The injectors are controlled by means of suitable cocks or taps so that the
production of steam may be adapted to the work to be done.
In order that my invention may be more clearly understood I will now proceed
to describe the accompanying drawings, in which
Figure 1 is a sectional side view of a locomotive boiler constructed in accordance
with my invention, the section being taken on the line, of Figure 2.
Figure 2 is a sectional plan taken on the lines x, x of Figure 1.
Figure 3 is a transverse section on the line y y, Figure 1.
Figures 4 to 7 are views hereinafter more particularly described shewing various
modified forms of boiler.
Figures 8 to 10 are longitudinal sections shewing portions of boilers furnished
with divided intermediate furnaces..
Figure 11 is a section of a hopper designed for use in supplying fuel to
furnaces.
Figure 12 is a cross section of a fuel reservoir fitted with a stirrer or paddle as
hereinafter explained.
Figures 13 and 14 are cross sections through the smoke-box of boilers provided
with two chimneys, according to the second part of my invention.
Like letters denote similar parts in all the drawings.
A is the boiler barrel; B the main fire-box; C the second or supplementary
fire-box; D, D the first set or section of tubes, connecting the main fire-box with
the supplementary fire-box; E the smoke-box and F, F the second set or section
of tubes, connecting the second or supplementary fire-box with the smoke-box.
:
The second fire-box C is provided with a fire-brick hearth G on which the
sprays or jets of liquid or powdered fuel are received and consumed. The drawing
shews only one of the many efficient forms of hearth that may be designed and I
do not here restrict myself to this particular form. The air necessary for the
combustion of the fuel is supplied to the second fire-box in two ways, firstly, by
means of the tubes H, H which, starting from the bent funnels I, I pass through
the main or ordinary fire-box B and communicate with the casings J, J which
open into the hearth G of the second fire-box; secondly, by the opening.K and
upward passage K' which communicates with the hearth G by the two downward
passages L, L as shown by the arrows in Figure 3.
In this latter case the air passes in through the opening K and ascends the
passage K, the air current then divides and passes down through the channels L, L
as shewn in Figures 2 and 3, rearwardly along the horizontal passages L'; L' then
upward and out by the mouths L', L, as shewn by the arrow in Figure 1.
The passages K' and L, L and Li, L' are made in fire-brick in the hearth G
so that the air in passing therethrough becomes heated before it finally reaches
the seat of combustion. Both of the air channels or entries are provided with
suitable valves or dampers such as shewn at k, k for example by means of
which the amount of air gaining, access to the second fire-box can be controlled.
The air-tubes H, H are taken through the main fire-box with the special design of
ensuring that air at a temperature sufficient to ignite the injected fuel can always
be supplied to the second fire-box. The tubes H, H are preferably protected
by a coating of fire-clay inside the main fire-box B and by non-conducting
composition / or other means for preventing loss of heat between the two.fire-
boxes. One or both of the air supplies for the second fire-box may be heated by
being led through tubes placed in the smoke-box or in the boiler instead of in the
main fire-box if desired, but it will be understood that the beating of the air
supply is not essential. The hearth G is built in a suitable frame or pan U which

page_text: is secured to the bottom of the fire-box. A section or flap U' of this pan is made
movable being pivoted at W and secured at X with a suitable fastening, the release
of which allows the flap to fall so affording access to the hearth and fire-box. The
width of the flap is preferably equal to the width of the up-cast air passage K¹ as
shown in Figure 3.
The liquid fuel is supplied to the nozzles M, M from a reservoir N conveniently
placed. In Figure 1 this reservoir is shown as a saddle-tank carried above the
boiler. The supply of liquid fuel and of the steam or compressed air used to inject
it is controlled by taps, cocks or valves which may be of the types employed by
Messrs. Urquhart and Holden or of other suitable form and which are controlled
by means of the rods and lever O, O.
In locomotive engines the second furnace is thus controllable from the foot-plate
without the men leaving their usual places. I do not confine myself, however, to
the methods of injection mentioned as any efficient system can be employed.
The second fire-box is fitted with. a deflector P made of fire-brick or of iron
cased in fire-clay the function of which is to deflect or direct the gases from the
main fire-box through the upper rows of the tubes or flues F, F of the second
section of the boiler. Said deflector is hinged at Q and made movable and
adjustable so that the number of tubes F, F directly opened to the main fire gases
may be varied in conformity with the conditions under which the boiler is working.
When the second fire-box is not required the deflector P is lowered until it rests
on the fixed brick arch or deflector R and the valves or dampers controlling the
air supplies H, H and K being closed the boiler then acts with an ordinary single
furnace. The movements of the deflector P are controlled by a winch S in the
smoke-box operating chains or rods passing through one or more of one of the
upper. rows of tubes F.
Said winch S may also be placed on the foot-plate in rear of the main fire-box
as shewn for example in Figure 7 in which case the operating rods or chains pass
through one or more of the tubes D, D as therein shewn. When the winch S is
placed in the smoke box a roller or guide S¹ must be provided in the second
fire-box as shewn in Figure 1.
The main fire gases are directed through the upper tubes or flues F, F in order
that they may not mix with and extinguish the flame resulting from the combustion
on the hearth G which flame will pass between the deflectors P and R and enter
the lower rows of the tubes F, F of the second section. At the same time the
main fire gases which have become cooled in passing through the tubes D, D in
passing over the deflector P and through the upper part of the second fire-box
which will be kept at a high temperature by the combustion on the hearth G
below, will become re-heated and capable of producing a better evaporative effect
in passing through the tubes F, F of the second section than would have been the
case had there been no second fire-box.
As however, the main fire-gases cannot be re-heated to their original temperature
they will occupy as is well understood, when passing through the tubes F, F less
space than they did when passing through the tubes D, D consequently it will
suffice ordinarily to reserve for their passage only such of the tubes F, F of the
second section as will furnish a flue area proportionate to the reduced volume of
the gases. If this be estimated approximately at two-thirds of the original
volume the deflector P may appropriately be adjusted to reserve two-thirds of the
tubes F, F for the main fire gases. This plan limits the amount of fuel that can
be burnt in the second fire-box since only one-third of the tube area F, F is
available for the passage of the gases arising from the combustion of that fuel.
When a larger consumption of fuel than is attainable by this plan is desired in
the second fire-box the diameter of the second section of the boiler may be enlarged
as shown in Figure 4, so that room may be afforded for a larger number of
tubes F, F and a corresponding increase of flue area in the second section of the
boiler. The plan shown in Figure 4 may also be followed when it is desired to
produce a boiler of ordinary evaporative power but fitted so as to divide the work

page_text: between two furnaces in accordance with my invention. In this case the second
section of the boiler containing the tubes F, F would be of the norinal diameter
whilst the first section containing the tubes D, D would be about two-thirds of that
diameter only.
Since the products of liquid fuel combustion are more effective with flue tubes of
small diameter, the lower rows of the tubes F, F when such fuel is used, may be of
smaller diameter than the upper rows which are reserved for the passage of the
main fire-gases. For example, the total number of rows being fifteen the seven top
rows may be tubes 1 inches in internal diameter while the eight lower rows may
be of tubes measuring 1 or 18 inches in internal diameter. This is shown in
Figure 3.
Referring now to Figure 5, a second fire-box is shewn fitted with a shallow fire-
brick hearth G built in a frame or pan U which has a removable Hap U' pivoted
at W and which on the release of a fastening at X falls as indicated by the dotted
line. In this case the second air supply is taken through an aperture which may
be in the form of a bent funnel as shown at K and which is controlled by a damper k
and through numerous channels of small diameter marked L in the back of the
fire-brick hearth. The other portions of the fire-box are similar to those herein
above described with reference to Figure 1.
Another alternative form of hearth is shown in Figure 6. The furnace chamber C
is contained within the barrel of the boiler A, A and communicates by the
tubes D, D with the main fire-box and by the tubes F, F with the smoke-box.
Within the furnace-chamber are built two fire-brick arches or deflectors P, P. A
frame or pan U is suspended from the boiler barrel by suitable attachments. The
bottom of the pan U is detachable and is kept in position by iron bars which pass
underneath it and are fastened by nuts to bolts attached to the sides of the pan.
When the nuts are unscrewed the bars and the bottom of the pan U may be
detached and with them the hearth G and deflector R which are supported entirely
on the detachable bottom. When the bottom is dropped, access is bad to the
furnace chamber by apertures in the boiler barrel and the bottom of the said
chamber. The fastenings are indicated at X, X; the injector at M in a casing or
channel supplied preferably with warmed air in the manner shown in Figure 1.
Supplementary air supplies with dampers are shown at Z, Z.
In some circumstances it is advantageous to provide the second fire-box with a
chimney through which some or all of the main fire-gases may be diverted so as to
leave the whole of the tubes or flues F, F of the second section of the boiler free
for the passage of the gases produced in the second fire-box. Such an arrangement
is shown in Figure 7 in which the second fire-box C is provided with a chimney X'
leading from its roof through the barrel of the boiler A, A to the open air. A
portion of the exhaust steam from the cylinder or a jet of live steam from the
boiler may be directed up the chimney X by the pipe and nozzle Z' as indicated
in the drawing. The steam jet is controlled by a suitable valve V. The movable
deflector P which is adjustable as hereinbefore described may be set at any angle
and so divert any desired quantity of the main fire-gases through the chimney X'.
In the position shown in the drawing the maximum quantity of the main furnace
gases is being diverted and the boiler is acting with two independent sets of furnaces
and tubes. When the chimney X' is not required it is closed by the damper Y.
Referring now to Figures 8 to 10, P in Figure 8 is a fire-brick arch extending
from side to side of the furnace chamber dividing it into two compartments C and C.
The gases from the main fire-box B pass through C' above P and into the upper
rows of the tubes F, F without coming in contact with the gases resulting from the
combustion on the hearth G which pass through the part C below the arch P and
into the lower rows of the tubes F, F. The fire-brick arch P is heated by the
combustion beneath it and communicates heat to the main fire gases above it.
In Figure 9 is shown a method of conveying the main fire gases across the
intermediate furnace chamber by means of tubes. P¹, P' are two fire-brick arches
extending across the furnace chamber one adjoining each tube plate. Upon these

page_text: arches are built two walls P, P extending to the roof of the furnace chamber,
so as to leave spaces or compartments D, F between the walls and the tube-
plates. Tubes of fire-clay or metal cased in fire-clay of which three, for example,
are indicated at T1, T2, T3, extend between and through the walls P³, P. The
gases from the tubes D enter the space D', divide between the tubes T1, T2, T3
combine again in the space F and pass away by the upper rows of the tubes F, F.
The gases due to combustion on the hearth G pass under the arch P' and away by
the lower rows of the tubes F, F. The outsides of the cross or intermediate
tubes T1, T2, T3, as well as of the bridges and walls P1 P2 P3 and P are exposed
to the heat generated in the furnace chamber C and a portion of the heat is
-communicated to the main fire gases passing inside them.
In Figure 10 is shown a modification in which the tubes T', T" are conoidal in
form and made of fire-clay being supported in walls D2, F' built on brick
arches PP.in the intermediate furnace chamber similar to those shewn in Figure 9.
In this case some of the upper rows of the tubes F, F are left open to the gases
generated in the furnace C and the outside of the cross tubes T', T' are exposed to
greater heat than is the case when the design shown in Figure 9 is used.
In the Figures 8 to 10 above described the first section of the boiler containing the
tubes D is shown smaller in diameter than the second section containing the tubes F.
The two sections may, however, be of the same diameter in which case the fire-
brick arch or partition P Figure 8, would slant upward from the bottom of the first
.section of tubes to about the position shown at the second section so that the gases
coming through the tubes D will be diverted through the upper rows only of the
tubes F.
Similarly the construction shown in Figure 9 would be modified, the wall P' and
space D' would be extended downward to the bottom of the first section so that
gases coming through the tubes D would be directed upward through D' and
thence through the tubes T1, T2, T3, to the space F1 and the upper rows of the
tubes F. Some, or all of the tubes. T1, T2, T', could be made to slant upward
from the bottom of the wall P to the wall P, if desired.
When the boiler section containing the tubes D is of smaller diameter than that
containing the tubes F as in Figures 8 to 10, the arrangement of the tubes may be
further modified by making the upper tubes F and the tubes D in one length so
that being introduced by the smoke-box they would thread through both tube-plates
of the intermediate chamber, where they would be made tight, by suitable ferrules,
and terminate at the fire-box, thus extending in one unbroken length from the
smoke-box to the fire-box tube-plates. Or they may be made in two lengths so as
to meet and be jointed in the intermediate chamber. The main fire-gases would
then pass through uninterrupted metallic tubes, giving up heat to the water at D,
receiving heat from the second furnace at C and giving up heat again to the water
at F.
When passing through C the metallic tube should be coated with fire-clay.
In this mode of construction the deflectors or divisions P are dispensed with.
When the first section of the boiler as in Figures 8 to 10 is of smaller diameter
than the second section the numerous small tubes D, D may be replaced by one or
two large tubes or flues preferably of the corrugated type.
I have hitherto described the invention as used with liquid fuel. When coal
-dust or other powdered fuel is employed the injecting apparatus must be modified,
the oil reservoir being replaced by one or more boxes or hoppers to contain the
dust, which should be finely divided and dry. The injection of the coal dust into the
fire-box may be effected according to the plan introduced by the late Mr. Crampton,
as is well understood, or by apparatus similar to that employed for sanding rails
to improve the adhesion of locomotive driving wheels, which is known as the
"Band-blast" and is well understood. A suitable form of hopper and feeding
apparatus which I have designed for use in connection with the boilers of locomotive
engines is shown in Figure 11, in which M' is the hopper with a pipe or channel M*
leading to the injector M which is provided with a compressed air or steam
pipe M'.
m is a horizontal wheel or screw upon which the dust falls by gravitation

page_text: and which is revolved by a pulley and bevel-wheel from some part of the machinery.
Said wheel m thereby acts as a stirrer, and feeds the dust into the channel Mt.
One or more additional stirrers may be fixed higher up in the hopper if necessary.
to prevent caking. m³ is a door above the level of the stirrer m.
In some cases I use a fuel composed of coal-dust, coke-dust or other refuse
fuel in the forms of grains, or powder, mixed with oil or other liquid fuel, and
fed or injected by any suitable method. In this case the fuel reservoir should be
provided with a paddle-wheel or stirrer driven preferably from the engine so ns.
to ensure efficient mixing of the fuel constituents and the equality and homogeneity-
of the fuel.
Such a reservoir is shown for example in Figure 12 where N' is a vertical
shaft which is driven from the engine by suitable gearing. Said shaft is provided.
with paddles or vanes n n which rotate and constantly stir the liquid and powdere.l:
fuel shewn at N°.
In some circumstances I find that the supplementary furnaces may advantageously
be provided with ordinary fire-doors and fired by hand or by mechanical stokers.
with any ordinary fuel, such as coal, coke or wood. The fire-brick hearth G shown.
in the accompanying drawings is then replaced by an ordinary grate through which
the air necessary for combustion is drawn in the usual way. The supplementary
furnace C then resembles in all its essentials a fire-box of the ordinary or other
efficient type. The fire-door for feeding coal, or other fuel into the furnace C
may be in the side of C or in its back or front as may be most convenient.
In steam boilers in which evaporation is promoted by the action of a blast of
exhaust steam from the engine cylinders, as in locomotives, it is customary to
discharge the exhaust steam into the air through one aperture or chimney only.
With boilers fitted with supplementary furnaces such as are described in these
presents a more efficient blast than is ordinarily employed may be found desirable.
In such a case 1, according to another part of my invention, provide the boiler
with two chimneys and direct a blast of steam through each. If the engine has
two cylinders, each may exhaust up a separate chimney; if the engine has only
one exhausting cylinder the exhaust pipe may be divided into two branches, one for
each chimney. In the first case the exhaust blasts will not be quite simultaneous.
and the smoke-box should be preferably divided by a plate or diaphragm into two
compartments one for each chimney, so that half the flues or tubes will be acted
on by the one chimney and the other half by the other. When the exhaust is.
from one cylinder only the blasts in the two chimneys will be simultaneous and a
diaphragm will not be necessary, The division of the blast between the exhaust
orifices and two chimneys increases the area of the escaping steam and enables it to
act usefully on a greater area of the gases, moreover, the joint area of the two
exhaust orifices being greater than that of the one orifice generally used, back
pressure in the cylinder is reduced.
Referring now to Figure 13, U, U are the cylinders of an engine having two
exhausting cylinders and V is a plate or diaphragm which divides the smoke-box into
two portions, V'and V. Said plate extends from the top to the bottom of the smoke-
box and from the tube plate to the smoke-box door, against the inside of which it
is shaped to fit. The plate or diaphragm is preferably constructed so as to be
able to be readily taken out when access to the tubes is required. This may be
accomplished by causing it to slide in a groove or guide on the bottom of the
smoke-box as shewn at V and to rest against and be bolted to a piece of angle
iron Vattached to the roof of the smoke-box. The cylinder U' exhausts up
blast-pipe U and chimney W and cylinder U' up blast-pipe U and chimney Wi
as indicated by the arrows.
The diaphragm V, Figure 13, may be dispensed with by causing the exhaust
port of each cylinder to open into a common receptacle or chamber from which the
last-pipes U U both spring. Or the exhaust ports may empty into one pipe
which is afterwards forked or branched so as to discharge the steam equally
Letween the chimneys W W₁

page_text: .
In Figure 14 the arrangement when the engine has but one cylinder exhausting
to the air, is shown. No diaphragm is necessary and the exhaust port of the
cylinder U is made to divide its steam equally between the blast-pipes U³ and U*,
80 creating a simultaneous blast through the chimneys W and W₁, as indicated by
the arrows.
If the two blast orifices are made to discharge at different levels in the
smoke-box it will be possible to equalize, approximately, the velocity of the
gases through the upper and lower rows of tubes, a desirable object which is
difficult of attainment in ordinary boilers. In this case one blast orifice should be
situated on or near the level of the top row of tubes and the other at or near the
level of the middle row of tubes, the mouth or lower extremity of the chimney into
which this latter blast orifice exhausts being lowered a corresponding distance.
A horizontal diaphragm dividing the smoke-box into an upper and lower com-
partment may be fitted at the level of the mouth of the extended or lower chimney
so that this chimney will draw air from the lower compartment only while the
other will exhaust from the upper compartment only. This arrangement is specially
applicable in the case of a boiler with two furnaces, such as is hereinbefore
described, in which the gases from the two furnaces are required to traverse
different rows of tubes without mixing.
By constructing the blast nozzles of separate lengths of pipe of slightly larger
diameter than the exhaust pipes proper the best levels for equalizing the flow of
gases may be found by sliding the nozzle pipes on the others and then fixing with
clamps or screws.
I do not confine myself to two chimneys or two blast orifices as the exhaust
steam may be divided in the same manner between three or more chimneys or
orifices although not so conveniently. This device of a divided blast may be
applied to any forms of boiler in which exhaust steam is employed to create or
augment the draught.
It is obvious that my invention provides a double furnaced boiler which is
rapidly adapted to changed conditions of load or work, by reason of the fact that
one of its two furnaces may be lit or extinguished instantly without in the case of a
locomotive necessitating the engineman leaving the cab.
Although my invention is more particularly applicable to boilers of the
locomotive type with reference to which it is hereinabove described yet it may be
adapted to boilers of other forms in which intermediate or combustion chambers
exist or are capable of being added.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it to be understood
that I do not claim as my invention the use of intermediate or combustion chambers
in steam boilers when such chambers are not used as seats of independent
combustion resulting from the introduction into such chambers of fresh fuel and air,
nor the broad use of brick hearths, injected fuel and heated air supply in steam
boilers, but I declare that what I claim is :-
1. A steam boiler, having a second or supplementary furnace or fire-box
connected by one set of tubes or flues with the ordinary or main furnace and
fire-box and by another set of tubes or flues with the smoke-box or chimney, with
or without a second chimney, and with deflectors in the said supplementary furnace,
substantially as, and for the purposes, specified.
2. In such a steam boiler, the combination with the supplementary furnace of
means for injecting liquid, gaseous or powdered fuel thereinto, substantially as
described.
3. In such a boiler heating the air supply for the supplementary furnace by
passing the same through tubes or the like in the main furnace, substantially as
described, for the purpose specified.
4. A steam boiler fitted with a second or supplementary furnace and in which
the second section of the boiler between the smoke-box and such second furnace is

page_text: increased in diameter for the purpose of affording additional flue-way for the
gases, substantially as described.
5. In a steam boiler, re-heating the main furnace gases by heat generated in a.
second or supplementary furnace without mixing the gases of the two furnaces,.
substantially as described.
6. In a steam boiler, re-heating the main furnace gases by causing them to pass-
over and come in contact with surfaces which constantly derive heat from a second.
furnace, substantially as specified.
7. In a steam boiler, causing, by means of deflectors and arrangement of
draughts, the gases from the main and second furnaces respectively to remain
unmixed although in contact at their surfaces and to follow independent routes.
through the tubes between the second furnace and the smoke-box, substantially as.
specified.
8. A steam-boiler furnished with means such as hereindescribed for increasing
the evaporative effect of the heating surface furthest from the fire-box.
9. A steam boiler having a second or supplementary furnace or fire-box divided:
into two or more compartments through one or more of which compartments the
gases generated in the first furnace are led without mixing or contact with the
gases of the second furnace, substantially as described.
10. The modification wherein the products of combustion from the first furnace
are passed through tubes or the like in the second furnace, substantially as.
described.
11. The improved steam boiler constructed substantially as described with.
reference to Figures 1, 2 and 3 or to either of Figures 4 to 10 of the accompanying
drawings and operating as specified.
12. In a steam boiler an intermediate furnace constructed substantially as herein.
described for the purpose specified.
13. The combination, with a steam boiler which is fired with a mixture of
powdered and liquid fuel, of a reservoir for containing the fuel, and a paddle-wheel
or other suitable stirrer, for ensuring the equality and homogeneity of the fuel,.
substantially as described.
14. In a steam boiler wherein the exhaust steam or a portion thereof is used to
produce, a draught, the provision of two or more chimneys, between which the
exhaust steam is divided, substantially as described, for the purpose specified.
15. In a steam boiler for use with non-condensing steam-engines, the construction,.
combination and arrangement of two blast pipes and chimneys substantially as
described with reference to Figure 13 or to Figure 14, of the accompanying
drawings, for the purpose specified.
16. In a steam boiler wherein the exhaust steam or a portion thereof is used to
produce a draught and which is fitted with two or more chimneys in accordance
with my present invention, the provision of two or more blast-pipes with orifices at.
different levels and with or without horizontal diaphragms, substantially as, and
for the purpose, specified.
Dated this 25th dex of Ancil 1804
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.