Improvements in or relating to Boiler and other Furnaces.
Year: 1896

page_text: Date of Application, 27th Nov., 1896
Complete Specification Left, 23rd Mar., 1897-Accepted, 15th May, 1897
PROVISIONAL SPECIFICATION.
Improvements in or relating to Boiler and other Furnaces.
I, WILLIAM DAVID HAMILTON, of 8 Park Drive, Whiteinch, in the County of
Renfrew, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to boiler and other furnaces and it has for its object by
suitable construction of the fire door or other parts of the furnace to ensure that.
the inflowing air will be thoroughly mixed with the gaseous products of the fuel
and that complete combustion will take place before the fire gases come in contact
with the heating surfaces.
To that end under one modification I form a slot or other opening in the lower
or other side of the fire door for the admission of air which passes between the
door and a baffle plate secured thereto until it reaches the upper side of said
door, whence it enters the furnace by orifices communicating with tuyeres of which
there are preferably two, one at each upper corner of and formed integral with the
fire door frame. These tuyeres are preferably made conical and may have either
their narrow or wide ends towards the fire door according to the conditions of
natural draught and they may be inclined or otherwise formed in relation to the
crown of the fire door frame the object being to direct the inflowing air down upon
the gaseous products as they rise from the fuel, and to admit the air entering
through the door at a velocity fully sufficient to overtake the air, entering between
the fire bars, and the rising fire gases. This arrangement permits of the furnace
being fired practically in any manner and close up to the fire door.
Between the orifices in the baffle plate communicating with the fire door I may
form when desirable a number of smaller orifices which permit a portion of the
inflowing air to enter the furnace by way of the channel formed by the fire door
frame, these orifices being formed at the same height as the tuyeres, and the object
being to direct this portion of the inflowing air down upon the fuel lying in the fire
door frame for the purpose already described.
A special feature of the invention is the provision for concentrating the air
admission at the upper corners of the fire door in order to ensure a swirling action
on the fire gases as they commingle with the air.
When steam is used to assist the natural draught I make the fire door frame
hollow and cause the steam first to traverse backwards and forwards. within the
door frame thereby drying or superheating it before it is led into the space between
the door and its baffle plate or into a breeches pipe situated in said space and
connected to the tuyeres, whence it passes together with the air to the interior of
the furnace.
As an alternative to the above I may lead two pipes up through the dead plate
at opposite sides of the fire door frame or carry two tuyeres through the front or
side furnace walls immediately above and close to the fire door, these tuyeres or
pipes being so situated as to direct their air currents upon the fuel and cause the
air currents to be thoroughly mixed with the gaseous products rising from the fuel ;
or the tuyeres may be carried directly through the door.
Dated this ofth day of November 1806
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
St. Vincent Street, Glasgow, Agent for the Applicant.

page_text: Improvements in or relating to Boiler and other Furnaces.
I, WILLIAM DAVID HAMILTON, of 8 Park Drive, Whiteinch, in the County of
Renfrew, 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 boiler and other furnaces and it has for its object by
suitable construction of the fire door or other parts of the furnace to ensure that
the inflowing air will be thoroughly mixed with the gaseous products of the fuel
and that complete combustion will take place before the fire gases come in contact
with the heating surfaces.
The invention is illustrated by the accompanying drawings,
Fig. 1 being a trausverse vertical section of the improved furnace fire door and
frame,
Fig. 2 a vertical section at right angles to Fig. 1 of the door frame, and
Fig. 3 a front view of the door,
Fig. 4 is a longitudinal section and Fig. 5 a front view of part of a Babcock &
Wilcox boiler with the improved fire door fitted thereto;
Figs. 6 and 7 are similar views respectively shewing the door as applied to an
ordinary Lancashire boiler, and
Figs. 8, 9, 10, 11 and 12 are details and modifications hereinafter referred to.
In carrying out the invention and as illustrated by the drawings under one
modification at Figs. 1, 2 and 3, I form a slot or other opening A in the lower or
other side of the fire door B for the admission of air which passes between the door
and a baffle plate C secured thereto until it reaches the upper side of said door B,
whence it enters the furnace D by orifices E in the baffle plate C communicating
with two or more tuyeres F along the line v shewn on Fig. 2 close to the top of the
fire door frame; but when two tuyeres only are used I prefer to place one at each
upper corner of and formed integral with the fire door frame or fitted therein as
shewn. These tuyeres F are preferably made conical and may have either their
narrow or wide ends towards the fire door B according to the conditions of natural
draught and they may be inclined or otherwise forined in relation to the crown of
the fire door G, the object being to direct the inflowing air down upon the gaseous
products as they rise from the fuel, and to admit the air entering through the
door B at a velocity fully sufficient to overtake the air entering between the fire
bars H, and the rising fire gases. The admission of air may be further regulated
by means of a damper B between the outer plate of the door B and the baffle
plate C. The above described arrangement permits of the furnace D being fired
practically in any manner and close up to the fire door. The tuyeres may be fitted
with liners F as shewn at Fig. 1 when it is desired to decrease the volume of
entering air; and the tuyeres may either be open at their ends nearest the furnace
as shewn or be closed and have a series of perforations formed therein.
A special feature of the invention is the provision for concentrating the air
admission at the upper corners of the fire door in order to secure a swirling action
on the fire gases as they commingle with the air.
The tuyeres instead of being formed with a straight cylindrical, conical or other
bore may have a spiral twist on the bore for the purpose of still further imparting
a swirling action to the entering air or air and steam."
Between the orifices E in the baffle plate C communicating with the fire door B,
1 may form when desirable a number of smaller orifices or a slit permitting a
portion of the inflowing air to enter the furnace by way of the channel formed by

page_text: the fire door frame G, these orifices E being formed at the same height as the
tuyeres F, and the object being to direct this portion of the inflowing air down upon
the fuel lying in the fire door frame B for the purpose already described; or the-
tuyeres may be converted into a single tuyere K delivering a sheet of air through-
the fire as shewn at Fig. 9 or a sheet of air with increased volume at the corners
as shewn at Fig. 9.
In order to regulate the air admission by way of the ashpit, I may when
desirable close this, excepting at two points which admit of tuyeres L being inserted
as shewn at Figs. 4 and 5, and these tuyeres may be further fitted with liners.
according to circumstances for the purpose of perfectly regulating the admission of
air underneath the fire bars H.
When steam is used to assist the natural draught I make the fire door frame G
bollow as shewn particularly at Figs. 1, 2, 4, 5, 6 and 7, and cause the steam,
which is admitted at Y, first to traverse backwards and forwards as indicated by
the arrows within the door frame G thereby drying or superheating it before it is
led, at X, into the space between the door B and its baffle plate C or into a
breeches pipe I situated in said space as shewn in dotted lines at Fig. 7 and
connected to the tuyeres F, whence it passes together with the air to the interior
of the furnace D. When steam is introduced through the bottom of the door
I may place a cock on the steam pipe in proximity to the fire door and gear this
enck to the hinge as shown at W, Fig. 7, so that the steam is shut off automatically-
by the opening of the door.
The steam instead of being caused to travel between the door B and the baffle
plate C may be led directly into the tuyeres F by means of pipes M led through
the fire door frame G as shewn at Fig. 10.
When forced draught by fan or blower is used as indicated at Fig. 11, I may
form the bottom of the door with an angle having sufficient bearing surface round
the inlet to ensure that the door will be practically tight when closed in the usual
manner, and the pipe by which the air is forced into the hollow door may also be
provided with a damper or throttle valve.
As an alternative to the above I may lead two pipes up through the dead plate .J
at opposite sides of the fire door frame G as shewn at Fig. 8, or carry two tuyeres
through the front or side furnace walls immediately above and close to the fire
door B these tuyeres or pipes being so situated as to direct their air currents upon
the fuel and cause the air currents to be thoroughly mixed with the gaseous.
products rising from the fuel; or the tuyeres may be carried directly through the
door.
The hollow door may be baffled in order to cause the inflowing air to traverse.
in zig-zig fashion between the door B and its baffle plate C before entering the
tuyeres and this is attained by forming the baffle plate C with projecting vertical
or horizontal radiating ribs on the side nearest the door B which take up the heat
from the baffle plate C and impart it to the entering air.
When the invention is applied to a furnace fitted with a mechanical stoker the
tuyeres F may be arranged to pass through the stoker N as shewn at Fig. 12.
Having now particularly described and ascertained the nature of my snid
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. In a boiler or other furnace the arrangement in combination with the fire
door and its frame of tuyeres situated at or near the upper corners of the door
frame and adapted to direct air or air and steam into the Hame space of the furnace
substantially as and for the purpose set forth.
2. In a boiler or other furnace the combination with a fire door having an air
space formed within it and an orifice for admission of air under natural or forced
draught, of a fire door frame having tuyeres at or near its upper corners
communicating with the air space of the door substantially as described.
3. In a boiler or other furnace a hollow fire door containing within it a breeches

page_text: pipe having an air admission orifice below and outlets above adapted to discharge
through tuyeres in the fire door frame, substantially as described.
Dated this 16th day of March 1897.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62 St. Vincent Street, Glasgow, Agent for the Applicant.