Improved Process for Mixing Combustible Gases with Air.
Year: 1898

page_text: Date of Application, 12th May, 1898-Accepted, 23rd Dec., 1898
COMPLETE SPECIFICATION.
Improved Process for Mixing Combustible Gases with Air.
I, GEORG ROTHGIESSER, of 7, Bayrentherstrasse, Berlin, W., Engineer, in the
Empire of Germany, 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; -
For many heating and lighting purposes it is of great importance as regards
economy that the mixture of gas and air-or oxygen-for combustion should not
only be brought together in proper proportions, but be as intimately mixed as
possible.
This intimate mixing is specially advantageous, when it is necessary to obtain
a high temperature, that is to obtain a great development of heat in a small
space and in a short time: thus particularly in connection with incandescent gas
burners, melting furnaces for high temperatures and gas motors.
The simplest way of effecting a thoroughly intimate mixture is to allow the
different component parts thereof time to completely permeate one another, but
this can scarcely ever be adopted in practice on account of the danger from
explosion connected therewith, however, the apparatus must be so contrived, that
a continuous conflux of the component parts of the mixture to the seat of com-
bustion is effected.
In open burners, a sure guide for determining the extent to which the mixing
has been intimately effected is afforded by the size of the flame that is, the space
occupied by the gases of especially high temperature; the more intimate the
mixing, the smaller the flame, which shows that every mechanical mixing appa-
ratus is incomplete, as gas streams of proportionally large cross-section remain
containing a large number of gas molecules lying one on the other, which are not
permeated by molecules of air, and the combustion of all those particles of gas,
which do not lie immediately adjoining corresponding particles of oxygen, but
are surrounded by other particles of gas, only occurs after the burning of the
surrounding gas particles. The longer the time taken for the combustion of the
whole mixture that is the particles of gas first burned (of those which simul-
taneously reach the combustion chamber) and those which are burned last (these
being surrounded by other particles of gas), the more time there will be for the
expansion of the burning gases through the development of heat, thus the space
they occupy will be greater and the intensity of the heat of the flame reduced
accordingly. Conversely, by shortening the period of time in which the particles
of gas entering the combustion chamber arrive at combustion, a diminution of
the flame and an increase of intensity of heat, that is an increasing of the tem-
perature of the flame, can be effected.
In order to secure this result, the following process forming the subject of
this invention is employed.
In the conduction of the combustible gases a proportionately small quantity
of air is added, and in fact so little (about 5 to 30 per cent.), that an explosive
mixture is not produced thereby. This addition of air is effected at a certain
distance from the burners or other seats of combustion, in such a manner that,

page_text: in the conduction of the mixture so produced, there is a necessary period of at
least several seconds, or better still, at least half a minute, for bringing the mix-
ture to the seat of combustion, which period is sufficient to effect a thorough
mixing, in consequence, of the known tendency of the gases to permeate each
other.
In this way, all oxygen which is conveyed to the gas with the air, is separated
into the smallest particles, uniformly distributed in the combustible gas, and in
consequence of the high temperature prevailing in the burner flame, or, as soon
as the ignition point of temperature is reached, each of these intermixed particles
of oxygen must enter into chemical combination (this being implied by the com-
bustion) with a correspondingly large particle of gas. Thus, within the several
streams of gas, or gas bodies, innumerable exceedingly small uniformly distri
buted explosions must simultaneously occur, and this circumstance produces in
an extremely short time a mixture which brings all the gas molecules that are
present together with the molecules of oxygen and leads to their chemical com-
bination.
The accompanying drawing gives an idea of the difference between the ordinary
combustion and that effected by the present new process, the cross-section of the
gas and air mixture entering the combustion chamber of an open burner being
shown, the component parts of air appearing in black and the combustible gas
in white.
Fig. 1 relates to the ordinary combustion, and here the streams of gas are not
permeated with air, whilst
Fig. 2 relates to the new combustion, in which the streams of gas are permeated
with component parts of air, of which a portion are molecules of oxygen.
Figs. 3 and 4 are longitudinal and transverse sectional elevations respectively
of one form of apparatus for carrying out the process described.
In the case a, a pair of drums cd, capable of being easily rotated, are mounted
on the fixed shaft 66. The bearings e e¹ of suitable construction, ensure that the
drums may be at all times uniformly rotated, and with the greatest ease.
The shaft bis hollow, and furnished with a partition f at each side of which
it is provided with outlets gg¹.
For the drawing off of the mixture of gases the case a is furnished at the top
with an outlet pipe h. Both drums are furnished with partitions, as will be seen
from Fig. 4, and the case is filled with water to a point somewhat above the
shaft.
The gas enters through the end 6 of the pipe, passes out at g¹ and impinging
on the partitions rotates the drum c. The drum c however carries the drum d
along with it, and in this latter, the partition walls, in consequence of their
peculiar position effect a suction action in an inverted manner, whereby again,
air is drawn in through the opening g. The mixture of gas and air is carried
away at the point h―to the spot where it is to be used.
It is to be seen, that in consequence of the direct dependence of the drums on
one another, in relation to the rotation, the quantity of air can be introduced in
a determined proportion to the quantity of gas consumed, by an alteration in the
inlet opening at b, whereby an uniform mixture of gas and air is secured and
retained at all times.
The carrying out of the process, as a matter of course, is not restricted to the
above described machine, but any other apparatus, provided that it fully meets
the required purpose, can be employed at any time for the production of the
mixture of gas and air.
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:-
Process for the intimate mixing of combustible gases with air, the distinguish-

page_text: ing feature being that a preliminary mixing of the gas with 5 to 30 per cent. of
air is effected in the conduction tubes at a distance from the burners, which cor-
responds to a sufficient time for complete permeation, and that the necessary
further quantity of air for the complete combustion is added in the burning
apparatus.
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