Improvements Plating in the Consumption of Fuel Employed therefor.
Year: 1887

page_text: Date of Application, 3rd Mar., 1887
Complete Left, 3rd Dec., 1887
Complete Accepted, 13th Jan., 1888
Improvements Plating
in the Consumption of Fuel Employed therefor.
I, JAMES CARLTON STITT, of 17 Water Street, Liverpool, in the County of
Lancaster, Engineer, do hereby declare the nature of the said invention to be as
follows:-
Steam generators provided with improvements according to this Invention consist
as follows:-The fuel is placed upon a convenient construction of grate placed in the
furnace and is provided with a bridge and air is caused to pass through the fuel,
preferably by an induced draught. This may be done naturally, or artificially. The
air may be conveniently supplied by an exhausting fan placed in the funnel.when the
draught is to be artificially caused. A second and independent supply of pure air is
delivered preferably at, or near the bridge for the purpose of effecting the consumption
of the combustible gases evolved from the fuel. This air is supplied by an inde-
pendent engine, fan, or other blowing, or exhausting apparatus capable of providing a
measured, or measurable quantity of pure air as distinguished from air supplied by
steam jet apparatus which is necessarily difficult to compute and is moreover charged
with vapour and consequently ill adapted for consuming gases rising from a furnace
in which the heat of the flames and gases are being very quickly dissipated and falling
to such a temperature at which combustion becomes more difficult. The secondary
supply of air may be led by a duct, or ducts to a chamber in, or near the bridge.
The duct passes below the fire. The chamber may be constructed so as to deliver,
or distribute the air in small jets, or sprays. The air will to some extent be heated in
passing along the duct to the chamber and may if desired be previously heated by
any suitable means.
To facilitate the complete combustion of the fuel gases, 1 provide a quantity of
surface or a body of non conducting material such as refractory fire bricks over
which the flame and gases from the fire pass and whereby it is made incandescent.
This may consist of an inclined arch against which the flames are caused to impinge.
The secondary supply of air may be caused to flow towards this surface and hence the
flames and gases would flow between the secondary air chamber, or supply and the
surface of the incandescent non conducting material. The secondary air supply may
be controlled by a suitable valve, or valves, or equivalent device.

page_text: The gases after leaving the steam generator proper are passed through a feed
water heating apparatus preferably consisting of a tubular vessel or vessels in which
the hot gases pass through the tubes of the same. The feed water enters the said
vessel or vessels near where the gases leave the same and leave near where the hot gases
enter. After leaving the heating apparatus the feed water is passed into the steam
generator. The above heating apparatus is so constructed and arranged as to cause
the feed water to pass regularly from where it enters to where it leaves the tubular
vessel or vessels, so that the cooler water shall at the commencement come in contact
with the cooler portions of the heating surfaces and finally pass over the hotter
portion of the heating surface. This may be effected by direction plates, or weirs
suitably arranged in the apparatus.
The duct which conveys the gases from the steam generator proper is provided
with a valve, or damper by means of which the hot gases may be directed either
through the apparatus, or directly up the funnel.
My Invention provides a means, or method by which the volume, or quantity of air
supplied to pass through the fuel and the quantity, or volume of air for the secondary
supply can be independently regulated and controlled; whereby, ceteris paribus, the
greatest economy in the consumption of fuel for the generation of steam can be
obtained.
1

page_text: in the Consumption of Fuel Employed therefor.
I JAMES CARLTON STITT of 17 Water Street, Liverpool, in the County of
Lancaster, Engineer, do hereby declare the nature of iny said invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
Steam generators provided with improvements according to this Invention consist
as follows:-The fuel is placed upon a convenient construction of grate placed in the
furnace and is provided with a bridge, and air is caused to pass through the fuel,
preferably by an induced draught. This may be done artificially. The air may be
conveniently supplied by an exhausting fan placed in the funnel. A second and
independent supply of pure air is delivered preferably at, or near the bridge for the
purpose of effecting the consumption of the combustible gases evolved from the fuel.
This air is supplied by an independent engine, fan, or other blowing, or exhausting
apparatus capable of providing a measured, or measurable quantity of pure air as
distinguished from air supplied by steam jet apparatus which is necessarily difficult
to compute, and is moreover charged with vapour and consequently ill adapted for
consuming gases rising from a furnace in which the heat of the flames and gases is
being very quickly dissipated and falling to such a temperature at which combustion
becomes more difficult. The secondary supply of air may be led by a duct or ducts
to a chamber in, or near the bridge. The chamber may be constructed so as to
deliver, or distribute the air in small jets, or sprays. The air will to some extent be
heated in passing along the duct to the chamber and may if desired be previously
heated by any suitable means.
To facilitate the complete combustion of the fuel gases, I provide a quantity of
surface or a body of non conducting material such as refractory fire bricks over which
the flame and gases from the fire pass and whereby it is made incandescent. This
may consist of an inclined arch against which the flames are caused to impinge. The
secondary supply of air may be caused to flow towards the surface and hence the
flames and gases would flow between the secondary air chamber, or supply and the
surface of the incandescent non conducting material. The secondary air supply may
be controlled by a suitable valve, or valves, or equivalent device.
The gases after leaving the steam generator proper are passed through a feed water
heating apparatus preferably consisting of a tube filled vessel in which the hot gases
pass through the tubes of the vessel. The feed water enters the said vessel near that
part at which the gases leave it and leave it near that portion at which the hot gases
enter. After leaving the heating apparatus, the feed water is passed into the steam
generator. The above heating apparatus is so constructed and arranged as to cause
the water to pass regularly from the portion it enters to that part where it leaves
whereby the cooler water shall at the commencement come in contact with the cooler

page_text: through the apparatus
My Invention provides a means, or method by which the volume, or quantity of
air supplied to pass through the fuel and the quantity, or volume of air for the
secondary supply can be independently, regulated and controlled and with certainty ;
whereby ceteris paribus the greatest economy in the consumption of fuel for the
generation of steam can be obtained.
The above sets forth generally the nature, object, or objects of this Invention, but to
set forth the same more clearly and exactly I will now proceed to describe the same
with the aid of the accompanying Drawings which form a part of this Specification.
Like letters are used throughout the various views to denote like, or corresponding
parts.
DESCRIPION OF THE DRAWINGS.
Figure 1 shows in sectional elevation an example of a steam generator of the
marine return multitubular type with improvements according to this Invention
applied thereto.
Figure 2 is an end view of same.
Figure 3 illustrates in sectional elevation a modification of the apparatus shown
in Figures 1 and 2, and
Figure 4 is an end view of same.
Figure 5 is a detail of furnace fittings and secondary air supply devices applied to
the ordinary marine multitubular type of boiler.
Figure 6 is an end section at X X Figure 5 of the furnace looking to the left
hand.
Figure 7 is a cross section at Y Y Figure 5 looking to the right hand.
Figure 8 shows a modified arrangement of furnace fittings, and Figure 9 shows a
for cod blast arrangement of apparatus.
With reference in the first instance to Figures 1 and 2, A designates the steam
generator, B are its furnaces and C the combustion chambers. D is the feed water
heater of a tubulous form. E is an exhaust fan placed in the uptake F. Gare
valves by which the gasos can be either caused to pass through the feed water
heater D, or direct up the funnel. d is a diaphragm for causing the water to circulate
in the feed heater in the opposite direction to the flow of gases through the tubes
thereof. The secondary air is supplied at the bridge from the chest H and is led
thence by the duct I. K is an arch of fire brick.
With reference to Figures 3 and 4 it will be observed that the feed water heater is
of rectangular shape, instead of circular form as in Figures 1 and 2. and is provided
with diaphragms for causing the water to circulate forwards and backwards through
the apparatus. It will also be observed that the feed heater in this example is placed
in the uptake in lieu of above the generator as in Figures 1 and 2.
In Figures 5, 6 and 7 details of the secondary air supply device and fire brick
arch are shown. The air is led from the duct I to the the chest H by wing
passages i. is a door for gaining access to the space beyond the bridge L from the
front of the boiler. The chest H is independent of the bridge L, that is, it is not
connected to it and is therefore free of the weight and stresses due to the fuel and
grate. The front of the chest H is perforated with a number of holes h, so arranged
that jets of air are directed upwards the holes being of such a size that the quantity
of air to be supplied shall be delivered at such a velocity that it will penetrate the
flames and mix thoroughly with them. To secure this end small holes or slits of say
a quarter to half inch diameter or width are preferred. The arch K is disposed so
that the unconsumed gases coming over from the fuel on the grate are supplied with
the necessary amount of air to consume them in the presence of a heated surface,

page_text: or body of fire brick and before their heat has fallen to such a degree as to
render the union of the air and gases difficult, or impossible. The disposition of
the arch K is such, and its function in generators of the type shown is similar to
that of the brick arch employed in locomotive furnaces and effects in combination
with the secondary supply of air from the chest H substantially the same ends. The
air is supplied to the chest H by a fan by which means a measurable and practically
certain quantity of air can be delivered and at a conveniently high pressure to secure
the required velocity of efflux and for the purposes already described.
In combination with the volume of air supplied at the bridge there is also delivered
by the fan E a measurable quantity. Thus the two volumes of air, the one for
distilling the gases from the fuel and burning it, and the second for burning the
unconsumed gases coming over from the fuel, are supplied from separate and inde-
pendent fans, each capable of being worked to deliver specified, or desired quantities
of air and at varying pressures. For instance the pressure exerted by the fan E will
in some cases be found sufficient to be equivalent to an elevation of inch in the
water barometer whilst that of the air in the chest might be advantageously 2 inches.
Thus this Invention provides a means whereby about just the theoretical quantity of
air may be supplied to the fuel through the fire bars to effect the complete combustion
of it and the surplus found by practice to be necessary to effect practical perfect com-
bustion may be supplied at the bridge. For example 12 pounds of air may be
supplied per pound of coal by the fan E, through the bar, and 3 pounds of air per
pound of fuel may constitute the surplus air supplied at the bridge at sufficient
velocity to thoroughly mix with flames and effect the complete combustion of the
fuel. Hence this means renders it possible to obtain higher temperature in the
furnaces of steam generators than is usually done, and thereby secures a greater
evaporative efficiency from a given weight of coal consumed. The effect of the
greater initial temperature of the gases of combustion in the furnaces of the generator
will be, that the gases escaping from the tubes of a boiler of ordinary construction
will be of higher temperature than that when fired by the usual methods, and with a
large excess of air over that theoretically necessary to completely burn the fuel; and
consequently a further efficiency is obtainable from the boiler by the employment of
a feed water heater by which some of the heat of the gases after having left the boiler
proper may be absorbed by the "feed water." The water is passed through the feed
heater in the manner herein before specified.
It will be seen in Figure 5 that the air chest is placed behind the bridge and
shielded from the direct action of the flames and therefore is preserved from the
destructive action of them, also the chest and fire brick arch K are so placed
relatively to one another that the secondary air mixes with the fire gases when
passing over the arch, at the same time it causes no obstruction to the gases and
leaves a clear passage through which a man may get into the combustion chamber in
the usual way without disturbing the fittings.
In Figure 8 the chest is set in the arch K and is shielded from the flames by the
brickwork as shown. Apertures are formed in the brickwork to allow the air
from the holes to pass. In this case the air main I is shown coming through
the bottom of the boiler instead of through the ash pit as in Figure 5 but I do
not confine myself to any fixed part of the generator at which it may be intro-
duced as it is obvious that circumstances may render it necessary to introduce it
at various points. For instance it may in "single fired" boilers be brought in
through the back end through a "manhole," or in double fired boilers it may bo
brought in at the bottom or side and a duct led right and left to each chest, as
shown in dotted lines and marked I in Figure 8. In this case an arch K would
be provided for each furnace.
In lieu of introducing the main supply of air through the fuel on the grates by
the exhausting fan E it may be introduced by a compression, or forcing fan into a
closed ashpit in any known way. An example of such an arrangement is shown
in Figure 9 in which M is an air casing into which the air is forced by a fan.
A valve G in this case is also provided to direct the gases after leaving the boiler

page_text: oither through the feed heater, or direct up the funnel. In this way a measurable
and constant supply of air can be supplied as can be done when using the exhausting
fan.
In conclusion I would state that I am aware that it is a common practice to pass
the gases leaving the flues, or tubes of steam generators through a feed water heater
and that the use of fans as a means of causing artificial draught either by exhausting
or compressing is not new and I therefore make no claim generally to these means,
or apparatus but what I claim in respect of the Invention herein before
specified is :-
First. In steam generators the mode substantially herein described of burning the
fuel, which consists in the combination of the sub-methods of supplying the air
as follows; that is to say, (1) delivering the air to the ashpits of the furnaces by a
fan, or fans, and (2) delivering the secondary supply of air at, or near the bridges of
the furnaces by a separate fan, or fans as and for the purposes set forth.
Second. The introduction of air at or near the bridge of steam generator
furnaces in small, or thin jets in combination with a body of fire brick (such as
the arch K) the said jets being delivered under pressure as, or substantially as set
forth.
Third. The combination of air chest H and arch K arranged and constructed
substantially as set forth with reference to Figures 5, 6 and 7 of the Drawings for the
purposes specified.
Fourth. The combination of air chest H and and arch K arranged and constructed
substantially as set forth with reference to Figure 8 of the Drawings.
Fifth. The combination of parts as set forth with reference to Figures 1 and 2 of
the Drawings consisting essentially of the air chest H arch K, feed water heater D
fan E all arranged and operating substantially as described.
Dated this Second day of December 1887.