Improvements in Accelerating and Controlling the Supply of Air to Steam-boiler Furnaces, and in Utilising the Heat of the Waste Fire Gases.
Year: 1892

page_text: Date of Application, 14th Oct., 1892
Complete Specification Left, 5th July, 1893--Accepted, 5th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements in Accelerating and Controlling the Supply of Air to
Steam-boiler Furnaces, and in Utilising the Heat of the Waste
Fire Gases.
I, JAMES HOWDEN, of 8, Scotland Street, Glasgow, in the County of Lanark,
North Britain, Engineer, do hereby declare the nature of this invention to be as
follows, that is to say:-
:-
My said invention has for its object to increase the efficiency of steam boilers by
means of improved arrangements and apparatus for accelerating or controlling the
ordinary rate of combustion, for regulating the quantities of air supplied above and
below fire bars and for heating the air by the waste gases from the furnaces.
In carrying out my invention in the case of a marine boiler of ordinary type, in
one modification I arrange in a casing or casings placed above the smoke boxes,
vertical tubes through which the waste gases from the boiler pass in their way to
the uptake or chimney. The air for combustion is admitted to the casing or casings
from the boiler room or from other parts of the ship or from the outside atmosphere,
and passes in contact with the outside surfaces of the tubes, preferably at right
angles to the direction of the waste gases inside and in more than a single course.
When the air for combustion has a double circulating course through the casing
horizontal diaphragms divide the casing into upper and lower portions and the air
passes first across the upper halves of the heating tubes from the outer ends of the
casing to the centre where it descends in two currents and returns to the sides
through the lower part of the casing from which it passes downwards through
passages at each side of the smoke boxes to the common air reservoir encompassing
the furnace fronts whence it is admitted by regulating valves above and below the
fire bars of the furnaces as required.
When the air for combustion has only a single circulation or traverse through
the air heating casing with vertical heating tubes it is admitted by an opening at
the middle of the casing of sufficient width and nearly the whole height of the
casing tubes. The air passes to each side horizontally across the tubes and
downwards to the common air reservoir encompassing the furnace fronts as already
described.
In another modification the air heating tubes are placed horizontally in two
divisions in the casings or chambers in front of the boiler above the smoke boxes.
The waste gases from the furnaces after leaving the boiler pass around the air
heating tubes in their course to the uptake or chimney.
The air for com-
bustion passes through the tubes and downwards to the common air reservoir
encompassing the furnace fronts.
When a double circulation or traverse of air through the heating tubes is used
in this modification each of the two divisions of horizontal tubes is sub-divided into
upper and lower sections. The air enters at each side of the upper sections of tubes
and passes into a common chamber at the middle of the casing between the two
divisions of tubes and therefrom enters the tube ends of the lower sections returning
to the sides and to the passages leading downwards by the sides of the smoke boxes
to the common air chamber encompassing the furnace fronts.
When this modification with a single circulation or traverse of air is used, the
air passes into the chamber at the middle of the casing which separates the heating
tubes into two divisions. The inlet chamber or space is of sufficient width and of
the height of the casing containing the tubes. The air passes through the tubes to
each side of the boiler and downward thence to the furnaces as already described.
The air is made to pass through the air-beating apparatus and through the

page_text: furnaces by the action of the natural draught of the funnel or chimney assisted by
a fan or fans which take in the fire gases after they have passed through the
air-heating apparatus and discharge them into the funnel or chimney.
In the case of one single-ended boiler or in the case of two or more single-ended
boilers having one funnel or chimney, a single fan may be employed; but when two
or more double-ended boilers are arranged with one funnel or chimney I prefer to
employ separate fans for the opposite ends of the boilers. I place each fan in a
casing together with a small steam engine for driving it; and I place the fan casing
close to the bottom of the funnel or chimney with the fan inlet on one side and
communicating directly with the interior of the funnel or chimney. The discharge
passage of the fan I lead into the funnel or chimney at a higher point; and between
the fan inlet and discharge I arrange within the funnel or chimney a damper or valve
which in one position prevents the fire gases from proceeding directly upwards and
makes them pass through the fan, whilst in another position it shuts off the fan and
allows the fire gases to go directly upwards.
The arrangement described is suitable for a centrifugal fan having a horizontal
shaft, the fan may, however, be of any suitable known kind; and in some cases in
which the arrangement of the uptake or uptakes and funnel of the boiler or
combined set of boilers will admit of it the fan may be of the screw-propeller type
with a vertical shaft, and be placed at or in the bottom of the funnel.
Dated this Thirteenth day of October 1892.
EDMUND HUNI,
Applicant's Agent.
COMPLETE SPECIFICATION.
Improvements in Accelerating and Controlling the Supply of Air to
Steam-boiler Furnaces, and in Utilising the Heat of the Waste
Fire Gases.
I, JAMES HOWDEN, of 8, Scotland Street, Glasgow, in the County of Lanark,
North Britain, 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, that is to say :-
My said invention has for its object to increase the efficiency of steam boilers
by means of improved arrangements and apparatus for accelerating or controlling
the ordinary rate of combustion, for regulating the quantities of air supplied above
and below the fire bars and for heating the air by the waste gases from tlie furnaces.
In carrying out my invention in the case of a marine boiler of ordinary type, in
one modification I arrange in a casing or casings placed above the smoke boxes,
vertical tubes through which the waste gases from the boiler pass on their way to
the uptake or chimney. The air for combustion is admitted to the casing or casings,
and has either a double or single circulation or traverse, in contact with the outside
surfaces of the tubes, to a common air reservoir encompassing the furnace fronts,
whence it is admitted by regulating valves above and below the fire bars of the
furnaces as required.
In another modification the air heating tubes are placed horizontally in two
divisions in the casings or chambers in front of the boiler above the smoke boxes.
The waste gases from the furnaces after leaving the boiler pass around the air
heating tubes in their course to the uptake or chimney. The air for combustion
passes with either a double or single traverse through the tubes, and downwards to
the common air reservoir encompassing the furnace fronts. The air is made to pass
through the air-heating apparatus and through the furnaces by the action of the
natural draught of the funnel or chimney assisted by a fan or fans,
which take in the fire gases after they have passed through the air-heating
apparatus, and discharge them into the funnel or chimney.
And in order that my said invention and the manner of performing the same

page_text: may be properly understood, I hereunto append a sheet of explanatory drawings,.
to be hereinafter referred to, and showing two modifications of my improved
apparatus.
Figures, 1, and, 2, of the drawings are sectional elevations as at right angles to.
each other of one modification of my improved apparatus as fitted to an ordinary
marine boiler, Figures, 3, and, 4, being similar views of a second modification. In
these drawings the same reference letters are used to mark the same or like parts.
wherever they are repeated.
In the case of a marine boiler of ordinary type I arrange, according to the
modification shown in Figures, 1, and, 2, of the drawings, in a casing, A, placed
above the smoke boxes, B, vertical tubes, C, through which the waste gases from the.
boiler, D, pass on their way to the uptake or chimney, F. The air for combustion
is admitted to the casing, A, from the boiler room, or it might be through one .or
more tubes or ducts from other parts of the ship, or from the outside atmosphere,.
and passes in contact with the outside surfaces of the tubes, C, preferably at right
angles to the direction of the waste gases inside and in more than a single course.
The air for combustion has a double circulating course through the casing, A,.
owing to horizontal diaphragms, G, which are fixed in and divide the casing into
upper and lower portions. The air passes first across the upper halves of the
heating tubes, C, from the atmosphere through openings, H, in the outer ends of
the casing, A, to the centre where there is a vertical partition, J, in the casing; and
it descends in two currents, and returns to the sides through the lower part of the
casing, from which it passes downwards through passages, K, at each side of the
smoke boxes, B, to a common air reservoir, L, encompassing the furnace fronts, M,.
whence it is admitted by regulating valves (not shown) above and below the fire
bars of the furnaces as required.
.
When it is desired to employ a single traverse only of the air for combustion.
through the air heating casing, A, with vertical heating tubes, C, the air may be
admitted by an opening at the middle of the casing of sufficient width and nearly
the whole height of the casing tubes. There being no diaphragms, G in this case
the air passes to each side horizontally across the tubes, C, and downwards to the
common air reservoir, L, encompassing the furnace fronts, M, as already described.
In another modification shown in Figures, 3, and, 4, the air heating tubes, C,
are placed horizontally in two divisions in a casing or chamber, A, in front of the
boiler, D, above the smoke boxes, B. The waste gases from the furnaces after
leaving the boiler, D, pass up around the air heating tubes, C, in their course to
the uptake or chimney, F. The air for combustion passes through the tubes, C,.
and downwards to the common air reservoir, L, encompassing the furnace fronts, M.
In this modification the apparatus as delineated in the drawings, is arranged for
using a single traverse of air through the tubes, C. The air enters a common
chamber, N, at the middle of the casing, A, between the two divisions of heating
tubes, C, the inlet chamber or space, N, being of sufficient width and of the height
of the casing, A, containing the tubes, C. The air passes through the tubes, C, to
each side of the boiler, D, and downwards by the sides of the smoke boxes, B, to
the common air chamber, L, encompassing the furnace fronts, M.
When it is desired to make the air traverse twice through heating tubes, C,
each of the two divisions of horizontal tubes is subdivided into upper and lower
sections. The air may be arranged to enter at each side of the upper sections of
tubes, C, and to pass into the common chamber, N, at the middle of the casing, A,
between the two divisions of tubes and therefrom enters the tube ends of the lower
sections returning to the sides, and to the passages, K, leading downwards by the
sides of the smoke boxes, B, to the common air chamber, L, encompassing the
furnace fronts, M.
The air is made to pass through the air-heating apparatus and through the
furnaces by the action of the natural draught of the funnel or chimney, F, assisted
by a fan, P, which takes in the fire gases after they have passed through the
air-heating apparatus and discharges them into the funnel or chimney.

page_text: In the case of one single ended boiler, D, as shown in the drawings, or in the
case it might be of two or more single-ended boilers, having one funnel or chimney,
a single fan, P, may be employed; but when two or more double-ended boilers are
arranged with one funnel or chimney I prefer to employ separate fans for the
opposite ends of the boilers. I place the fan, P, in a casing together with a small
steam engine, Q, for driving it; and I place the fan casing close to the bottom of
the funnel or chimney, F, with the fan inlet, R, on one side and communicating
directly with the interior of the funnel or chimney. The discharge passage, S, of
the fan, P, I lead into the funnel or chimney, F, at a higher point; and between
the fan inlet, R, and discharge, S, I arrange, within the funnel or chimney, a
damper, or valve, T, which in the position shown in the drawings prevents the fire
gases from proceeding directly upwards, and makes them pass through the fan, P,
whilst in another position it shuts off the fan and allows the fire gases to go directly
upwards.
The arrangement described is suitable for a centrifugal fan having a horizontal
shaft, the fan may, however, be of any suitable known kind; and in some cases
in which the arrangement of the uptake or uptakes and funnel, F, of the boiler, D,
or of a combined set of boilers will admit of it, the fan may be of the screw-
propeller type with a vertical shaft, and be placed at or in the bottom of the funnel.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :--
1. The application to a marine or other steam boiler of vertical tubes arranged
in a casing or casings placed above the smoke boxes through which tubes the waste
gases from the boiler pass to the uptake or chimney, the air for combustion being
admitted to the casing or casings and being drawn or passed, with either a double
or single traverse, in contact with the outside surfaces of the vertical tubes to a
casing encompassing the furnace fronts, by the natural draught in the uptake or
chimney assisted by a fan or fans, the parts being arranged and operating
substantially in the manner hereinbefore described with reference to Figures, 1,
and, 2, of the accompanying drawings.
2. The application to a marine or other steam boiler of tubes arranged in
two sets, with an air chamber between them, in a casing or casings placed above
the smoke boxes around which said tubes the waste gases from the boiler furnaces
pass to the uptake or chimney, the air for combustion being drawn through the
tubes with either a single or double traverse to a casing encompassing the furnace
fronts by the natural draught in the uptake or chimney assisted by a fan or fans,
the parts being arranged and operating substantially in the manner hereinbefore
described with reference to Figures, 3, and 4, of the accompanying drawings.
Dated this Fourth day of July 1802
EDMUND HUNT,
Applicant's Agent.