Improvements in or connected with Heating Furnaces or Stoves.
Year: 1899

page_text: Date of Application, 12th June, 1899
Complete Specification Left, 7th Apr., 1900-4ccepted, 2nd June, 1900
PROVISIONAL SPECIFICATION.
Improvements in or connected with Heating Furnaces or Stoves.
I, WILFRID L. SPENCE, of 241, Tettenhall Road, Wolverhampton, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to air-heating furnaces or stoves in which the gases of
combustion are mixed with a supply of fresh air before passing away to be
utilised. The cold air is preferably supplied under a slight pressure as the hot
gases may be carried away under a corresponding suction draught or both
methods may be combined. Such stoves have their principal application in the
drying of animal or vegetable matters, grain, timber, sand moulds and like
operations but their use is not confined thereto.
The improvements herein described consist firstly in a certain arrangement
and general disposition of parts whereby perfectly controlled combustion and
graduated heating can be ensured with the least possible radiation losses, secondly
in the use of a form which lends itself to compactness and portability if desired
and which may consequently be cheaply constructed, and thirdly in arrangements
for facilitating rapid cleaning, repairs and renewals.
The invention also contemplates certain general arrangements of cold air supply
pipes or ducts by means of which semi-portable stoves can be placed in a limited
number of positions to furnish hot air from each of these over a defined area
limited by the length of flexible or jointed hot air pipes connected to the stove
outlet.
My improved air-heating stove may be constructed somewhat as follows-
but the form can be modified in various ways without departing from the spirit
of the invention.
A thin sheet or cast metal container of cylindrical form provided with suitable
legs is fitted with fireclay linings. The bottom liner is a circular disc with a
central outlet hole, the top is similar and preferably fitted in a metal lid. The
side liner may be a single cylinder or it may be in sections. Standing on the
lower end disc and raised slightly above it is a cast iron air-box or chamber con-
nected with the cold air supply by a suitable pipe passing through the fireclay
cylindrical lining to the outside. This pipe is fitted with an air regulating
admission valve.
The upper face of the box, which may be separable from the remainder, forms
a circular fire-grate and it is suitably perforated or slotted for the purpose. The
firegrate is surrounded by an inner fireclay cylinder, having longitudinal per-
forations through its walls, and standing on the grate. The inner cylinder forms
a container for the coke or other fuel and it becomes hot in use.
Part of the air for combustion passes up through the grate directly into the
burning fuel and a further supply of heated air to continue the combustion is
given by the longitudinal perforations already referred to whose outlet is at or
near the top of the fire. Perfect combustion, which is completed in the annular
passage between the inner and outer fireclay cylinders while the gases are passing
down to the outlet, is thus ensured.

page_text: As it is necessary or usual to mix with these gases a considerable volume of
fresh air, and in order to keep the cast iron air box from being burned a set of
small holes or passages is provided just under or over the firegrate and discharging
directly into the base of the annular combustion chamber, these passages should
point downward in the direction of the escaping gases. By this arrangement
the entrance of cold air at the lower end of the combustion chamber does not
tend to cool the latter-a defect existing in some types of hot air stove.
The base of the air box which is liable to get filled up with dust and ashes
from the fire above is provided with an outlet controlled by another valve. The
outlet is formed into a conical nozzle discharging downwards centrally into the
hot air pipe with which it forms a kind of ejector, so that any cold air blown
through the opened valve tends to draw with it the hot gases from the stove.
By closing the valve the major portion of the air having to pass through the
fire the rate of combustion can be greatly increased and the degree of heating
is thus under good control. This valve is preferably operated by a connection
passing through or just under the cold air inlet so that the handle remains com-
paratively cool.
When it is desired to clean the stove after use the cover is removed the valve
closed and the dust blown out by turning on the air blast, ashes may be raked
through the grate and dropped through the opened valve into the discharge.
The arrangements above described are those generally to be preferred where
the stoves should be light and portable. Modifications in the outline as also in
the internal disposition can readily be made to suit other conditions. For instance
a triangular stove standing on three legs, of which the outlet pipe may form
one, can be used; the perforated cylinder may be substituted by two separate
concentric cylinders, and one or more side outlets for the hot air may replace
the single vertical one.
A convenient arrangement where numerous small chambers or moulds are to
be dealt with is to have a main cold air duct with fixed stand pipes at intervals
upon any one of which an air heater may be placed and to convey the hot gases
short distances from the stoves by one or more flexible or jointed pipes. This
enables one stove of medium capacity to do the work of a number of smaller
ones.
Date this 10t
1000
COMPLETE SPECIFICATION.
Improvements in or connected with Heating Furnaces or Stoves.
T, WILFRID L. SPENCE, formerly of 241, Tettenhall Road, Wolverhampton,
now of Waterloo ('hambers, 19, Waterloo Street, Glasgow, Civil 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 follow-
ing statement:—
This invention relates to air heating furnaces or stoves in which the gases of
combustion are mixed with a supply of fresh air before passing away to be
utilised.
The cold air is preferably supplied under a slight pressure or the hot gases
may be carried away under a corresponding suction draught or both methods
may be combined.
My improved air heating stove, which has its principal application in the
drying of animal or vegetable matters, grain, timber, sand moulds and like
operations, although its use is not confined thereto, may be constructed somewhat