Improvements in the Means for Effecting the Combustion of Fuel in the Furnaces of Steam Generators or analogous appliances.
Year: 1891

page_text: Date of Application, 11th Mar., 1891
Complete Specification Left, 11th Dec., 1891-Accepted, 30th Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Means for Effecting the Combustion of Fuel in
the Furnaces of Steam Generators or analogous appliances.
THE GASEOUS AND LIQUID FUEL SUPPLY COY. LIMITED of 25 Market
Street Manchester in the County of Lancaster and BENJAMIN HOWARTH
THWAITE of 37 Victoria Street Liverpool in the same County Civil Engineer do
hereby declare the nature of this invention to be as follows:-
Our invention is intended for effecting the combustion of fuel in the furnaces of
steam generators or analogous appliances.
Our invention partly relates to improvements in a former invention for which
Letters Patent have already been granted to us, numbered 10,224 A.D. 1888.
This invention is intended to overcome one serious difficulty associated with
steam boiler furnaces working under natural draft conditions.
When fuel containing any proportion in its combustion of hydrocarbons of a
highly volatile character is thrown onto the bed of fire, the volatile gases are
evolved under conditions that preclude their receiving their adequate equivalence
of atmospheric oxygen to completely oxidise them, consequently these gases pass
away to the chimney unburnt.
In the existing arrangements the exhaust effect of the chimney is entirely
absorbed by the firegrate area, there being no independent supply of air to consume
the gas because if air was allowed to flow through the door it would reduce in a
serious degree the rate of fuel combustion on the grate.
The essential features of our invention are comprised in the following state-
ment
The provision in the ordinary firebridge, carrying the fire bars, of an opening
for the passage of a secondary supply of air, for the combustion of the unoxidised
combustible gases, we cover such opening with a porous material that shall offer
to the passage of the air permeating through it, the same resistance as that which
the fuel on the grate offers to the flow of the air, so that although such an opening
is provided for a secondary flow of air, this does not destroy the effect of the
chimney draft on the aspiration of air through the fuel on the grate, to support
combustion thereof.
We prefer for the porous covering of the air opening in the bridge, to use
metallic wire gauze of a sufficiently fine gauge, as to set up resistance to the
passage of the air through it.
We insert one two or more sheets of this gauze fixed in a cast or wrought iron
frame, this frame we make with taper sides, we also provide a corresponding but
larger frame which we build in the bridge in such a way that the movable gauze
frame can be easily fixed or removed therefrom, from the front end of the boiler.
We may provide the front part of gauze frame, with an additional covering by
providing a hanging door, of wire gauze and a perforated plate, the opening of which
can be regulated as desired, such regulation can be effected by mechanical means
from the front end of the boiler or stoke hole.
We prefer to lower the firebars as described in our former invention, so as to
obtain a thick bed of fuel, and we may employ either a steam jet method of inject-
ing air, or use a fan or blower for injecting the air under the grate; when we use
the former we hinge the ashpit door on the same centre as the movable steam jet
elbow pipe, and we provide on the ashpit. door, internal cones, to the centre of
which the steam jet nozzles are adjusted. In order to more completely promote
diffusion of the secondary air supply with the combustible gases, we provide, a short.

page_text: distance beyond the fire bridge, a drop or suspended refractory arch wall, the soffit
of which is about level with the level of the firebars. This arch diverts the flow
of the combustible gases beyond the bridge in a downward direction, thus, in their
flow, sweeping past the face of the wire gauze, and secondary air supply. The air
in permeating through the wire ganze is warmed, and instead of cooling the gases
it is in the best condition for promoting combustion. For the ignition we may in
some instances provide a small gas jet which we place in such a way that the flame
passes in front of the secondary air supply opening. We may build beyond the
drop arch a nest or wall of baffler bricks, which by combustion becomes heated to a
condition of incandescence, and thus assist in igniting the secondary mixture of
gas and air.
By the facile removal of the gauze covered opening we can easily remove the
dust deposited beyond the bridge.
Dated this Tenth day of March 1891.
THE GASEOUS AND LIQUID FUEL SUPPLY
COY., LIMD.,
Per David H. Noar, Secretary.
н
COMPLETE SPECIFICATION.
Improvements in the Means for Effecting the Combustion of Fuel in
the Furnaces of Steam Generators or analogous appliances.
THE GASEOUS AND LIQUID FUEL SUPPLY COMPANY LIMITED of 25 Market
Street Manchester and BENJAMIN HOWARTH THWAITE of 37 Victoria Street
Liverpool 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 following statement :—
Our invention relates to an improved means for effecting the combustion of fuel in
the furnaces of steam generators or analogous appliances.
We will now describe the nature of our said invention by the aid of the accom-
panying drawings which more clearly elucidate the character of our invention. But
before referring to the drawings we wish it to be distinctly understood that we do
not desire to be confined to the employment of the exact details shewn as these
may be modified without departing from the nature of our said invention.
Referring to the drawings Figures 1, 2 and 3 represent respectively a longitudinal
section, a plan in section and a cross section of our invention in one of its modifi-
cations.
The essential elements are the secondary air supply arrangement A, constituted
of a special rectangular frame B having an internal movable box C, covered in the
front and occasionally in the rear with fine wire gauze, say of 12 mesh, or of such
a mesh that it offers considerable frictional resistance to the passage of the air
through it,
Such a resistance for instance as the fuel in the grate offers to the passage of
the air.
The frame B is built in the bridge E, and the gauze covered box C, which fits
loosely in the frame and can be withdrawn any time by means of a hooked bar, by
which the box can be removed from the frame.
Beyond the bridge we construct a drop arch F which becomes heated to such an
extent that it ignites the gases (volatile hydrocarbons) when they are ignitable and
deflecting the gases over the front of the secondary air supply arrangement A.
When required we may place a hanging door over the front of the wire gauze,
which door can be raised or lowered as required by means of a bar workable from
the front.

page_text: The second modification of our invention is shewn by Figures 4, 5 and 6 of
which Figure 4 is a longitudinal section Figure 5 is a part detail section of the
arrangement, and Figure 6 is a front view.
In this modification, and attached to the front of the secondary air inlet arrange-
ment A, there is a box casting G, to which is connected three or more pipes or
tubes H, terminating at the front end of the boiler, and in a main pipe I below
furnace level.
This main pipe may terminate with a coned and steam jet air injector arrange-
ment J.
The air may be shut off by the slide valve K by this arrangement the dust and
ashes from the fire are prevented from choking up the gauze and the control of the
proportion, and time, of air introduction is complete.
The pipes or tubes H are covered over by means of a cast or wrought iron
plate L, which does not interfere with the withdrawal of the ashes, but protects the
pipes which however become heated by the supply of air.
This invention enables a secondary supply of air to flow behind the bridge to
consume the hydrocarbons without seriously impairing the chimney draught
efficiency on the grate, and in such a way that such hydrocarbons are ignited and
their combustion is supported by this secondary air supply.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same may be performed we declare that what we
claim is included in the following.
First. The arrangement of fixing a wire gauze covered secondary air supply
device in the bridge of a steam or other furnace, substantially and for the purpose
described.
Second. The fixing of a drop arch beyond the bridge in conjunction with such
secondary air supply device, substantially and for the purpose described.
Third. The method of supplying such secondary air device, with air from the
front of boiler such air being free from dust or ashes, with the controllable
supply of air arrangement substantially and for the purpose described.
Dated this 9th day of December 1891.
THE GASEOUS AND LIQUID FUEL SUPPLY
COY., LIMD.,
Per D. H. Noar, Secretary.
B. H. THWAITE.
THE GASEOUS AND LIQUID FUEL SUPPLY
COY., LIMD.,
Per D. H. Noar, Secretary.
B. H. THWAITE.