Improvements in Incandescent Gas Lighting.
Year: 1898

page_text: Date of Application, 30th June, 1898-Accepted, 18th Feb., 1899
COMPLETE SPECIFICATION.
Improvements in Incandescent Gas Lighting.
I, PAUL GREYSON DE SCHODT, of 15, Rue de la Station, Namur, in the King-
dom of Belgium, 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 improvements in incandescent gas lighting.
In the Specification of prior Patents Nos. 8509, 125297, 1893 granted to me
in respect of inventions relating to this subject I have described and shown means
for obtaining a combustion beneath the mantle imparting the maximum of heat:
these arrangements comprising a suction mixing device, serving to draw in the
requisite quantity of air and to intimately mix this air with the gas, and a burner
intended to conduct the mixture to the point where ignition is to take place.
This burner consisted of a truncated cone; the prolongation of the generating lines
of which terminated at the outlet of the injector, and which was surmounted by
a sheet of metallic gauze above which combustion took place.
The main object which I sought to attain was to effect an intensified illumi-
nation; and for this purpose I admitted that it was essential, in order to ensure
efficient working, to provide a greater pressure than usually exists in the service
pipes, this pressure being produced, if necessary, by means of an auxiliary appli-
auce: the compressor.
I have since discovered that this pressure can be considerably reduced if greater
facility be given to the mixture of gas and air for passing out of the burner, by
increasing the size of the mesh of the metallic gauze arranged above such burner,
the other arrangements and the form of the parts remaining as before. It was
found, however, that the results obtained were less favourable with burners not
working under high pressure, and that the mantles were not rendered so brilliantly
incandescent, as they were when gas at a certain degree of pressure was em-
ployed, although it was obvious that the flames were equally hot and homoge-
neous. The fault did not lie therefore with the arrangements employed, but with
the utilisation of the flame obtained.
These considerations led me to endeavour to discover conditions of utilizing
the flames which should give the maximum result, and to devise special arrange-
ments for realising such conditions, the flames being, besides, the result of the
intimate mixture of elements combined in suitable proportions, in accordance
with the processes described in the Specification of my aforementioned prior
Patents.
The maximum amount of heat that a flame is capable of developing is obtained
with an explosive mixture; with the arrangements claimed, sufficiently oxygen-
ated flames may be readily obtained, but these flames are short and the external
surface, which alone is actually utilised for producing incandescence, does not
reach a development commensurate with the quantity of gas used. On the other
hand, if the mixture contains its maximum of oxygen a cooling is produced at
the actual place of utilisation, as a result of the comburant in excess. It is not

page_text: necessary therefore that the flame should contain its maximum of oxygen if it
is desired that the temperature should reach its maximum at the points of con-
tact with the mantle, but it is requisite that at these points the mixing between
the first mixture and the outer air may be efficiently effected, in such a manner
as to produce a second intimate combination, and consequently an intense degree
of incandescence.
Various methods may be employed for effecting this secondary intimate mix-
ing; amongst these is that which I employed for my high pressure system. The
flame, issuing vigourously from the burner, produces around it a vacuum which
causes the outer air to reach the mantle with sufficient force for the mixture to
be complete at the point at which it is to be utilized. Penetration or intermixing
of the elements of the primary mixture and of the molecules of air takes place
precisely at the place at which the mixture is to be used, and consequently a
high temperature is developed at the surface of the mantle with the production
of a corresponding degree of brilliancy.
A second method consists in the employment of a chimney which directs the
outer air (whether heated or not) towards the streams of the mixture.
With regard to the first method it will be only necessary to mention that the
burner employed is merely surmounted by a metallic gauze, the meshes of which
are more or less close and which is made more or less convex according to the
pressure, in such a manner as to obtain flames large enough to fill the mantle.
The secondary mixing and consequently the brilliancy, increases with the stead-
iness of the flame. When the pressure is low, this steadiness diminishes and the
secondary mixing cannot take place with equal energy. It is then useless to in-
crease the quantity of primary air. If this supplementary primary air is not
itself injected at a certain pressure it only renders the flame heavy, and this
latter approaches the metallic sheet, rapidly brings it to a red heat and thus
produces a danger of backward ignition without in any way increasing the light
emitted by the mantle.
With the object of obviating this defect I have devised a third method, which
I will now describe.
This third method is capable of application to burners consuming small quan-
tities of gas and at ordinary pressures. It consists in giving, by means of special
arrangements, a certain degree of steadiness to the flame and in directing it ob-
liquely towards the surface of the mantle. It is there that the primary mixture
penetrates the secondary air at the desired point and causes the development of
of a high temperature.
In the accompanying drawings:
Figure 1 is a diagrammatic view of the arrangement adopted, and
Figure 2 is an elevation, partly external and partly in section, of the appara-
tus I prefer to employ for carrying my invention into effect.
Issuing from the injector A (Figures 1 and 2) the stream of gas carries with
it an enveloping stream of air which enters normally through apertures O in the
wall of the burner. The ascending stream, in passing the adjustable apertures 0¹,
carries with it, in its turn, a second enveloping stream of air which participates
in the upward movement and impinges upon the parabolic surface P (formed by
a parabola having a horizontal generating line and a focus at the point F upon
the vertical axis of the suction mixer). The external aeriform streams are re-
flected at by the action of the parabolic surface, and a penetration of the masses
(air and gas) is produced at this point which causes eddies and which ensures
intimate mixing in the manner described in the Specifications of my former
Patents. The loss of pressure which results from these eddies is compensated
for by the acceleration caused by the reduced portion of the channel R. The air
and gas thus enters the burner S in a state of exceedingly intimate mixture and
undergoes no appreciable retardation. It is indispensable, if it is desired that
the properly directed flame should be sufficiently steady, to cause this mixture
to issue with the smallest possible loss of pressure; for this purpose there is ar-

page_text: ranged at the upper part of the burner a special part M. This part leaves,
between itself and the outer edge of the truncated conical burner, an annular
aperture the size of which varies according to the consumption for which the
burner is to be regulated.
This part M constitutes a cone the inclined surface of which is formed by the
rotation around the axis XY of a segment of a parabola V, W. The parabola Z
VW the axis of which passes through the centre of the aperture existing between
the special part and the external portion of the burner, has its focus at G at a
very small distance from the aperture. The axis of the parabola is parallel to
the mean stream giving the direction of the movement of the mixture in each
semi-section of the burner.
It follows from this arrangement that all the mixing streams which impinge
upon the surface VW are deflected to the focus G and then pass through the
lateral aperture H with the minimum loss of pressure, the impingement upon
the surface VW taking place at the smallest possible angle. These deflected
streams are joined by the direct streams which follow the external surface of the
burner, and there thus exists at the outlet of the burner a sheet or stratum direc-
ted obliquely outwards and possessing the maximum pressure. The combustion
of this stratum gives a steady and hollow flame, which is particularly well adap-
ted to produce incandescence of the mantle without the use of a metallic gauze.
Notwithstanding the obliquity of the deflected streams, the flame does not
become infected as it might be thought would be the case. There is formed, in
fact, above the cone M in the hollow portion of the flame, a vacuum which the
external atmospheric pressure seeks to fill. It follows that there takes place
between the primary streams of mixture and the incoming outer air, a collision
or disturbance which results in a secondary mixture of the most intimate des-
cription and a steady and almost vertical Hame. If then this flame is covered
with a mantle, an intense incandescence is produced with a very small consump-
tion of gas.
It will of course be understood that I may construct my improved burner of
any desired size, according as it is intended to be employed with large or small
consumption of gas.
It is also obvious that, without departing from the nature of my invention,
the proportion and arrangement of my improved apparatus may be varied accord-
ing to requirements, it being necessary that suitable mantles following the con-
tour of the flames be employed. The cone M having a parabolic generating line
might also be combined in such a manner that the streams issue without friction
through a slot formed in the external and upper portion of the mantle holder.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. The combination with a gas burner provided with a suction mixer, of the
modifications introduced in the truncated cone burner with the object of permit-
ting a secondary intimate mixture at the points at which the flame comes in con-
tact with the mantle, consisting in the employment, in place of the metallic gauze
and for the purpose of enabling this latter to be dispensed with, of a cone shaped
part having a parabolic generating line, for the purpose of deflecting, with a
minimum loss of pressure, the whole of the streams of the primary mixture
through an aperture formed between the parabolic cone and the exterior of the
large base of the burner, so that a hollow flame is obtained having the maximum
of pressure and capable of resisting the atmospheric pressure which tends to
flatten it obliquely, and thus producing a secondary and very energetic mixing
where the mantle covers the flame.
2. The burner, herein described with reference to the accompanying drawings,
for the purpose of ensuring the secondary intimate mixing, whether the arrange-

page_text: ments of this burner are employed with the devices already devised by me, in
order to obtain the primary mixing, or whether they are utilized in combination
with other known devices for obtaining a primary mixing.
Dated this 30th day of June 1898
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.