Improvements in Apparatus for Inducing Draught in Steam-boiler Furnaces.
Year: 1890

page_text: Date of Application, 31st Dec., 1890
Complete Specification Left, 28th Sept., 1891-Accepted, 31st Oct., 1891
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Inducing Draught in Steam-boiler
Furnaces.
We DAVID CROLL, Engineer, and CARL HOHN, Draughtsman, to the
Nederlandsche Stoomboot Maatschappij of Rotterdam, in Holland, do hereby
declare the nature of this invention to be as follows, that is to say:―
My said invention has for its object to increase the efficiency of steam-boiler
furnaces by applying improved apparatus to induce an increased supply of air
beyond that given by natural draught, when, as in the case of marine boilers,
the chimneys or funnels are of only moderate height.
a
In carrying out my invention, in the case of a steam boat for example, I employ
an air compresser driven either from the main engines, or, as I prefer, by steam-
engine mechanism combined with the air compressing mechanism. The compressed
air is led into a receiver from which it passes by pipe or pipes to induction
apparatus placed inside the funnel or chimney or in each funnel or chimney when
there are more than one. The induction apparatus which I prefer to use com-
prises a long upper conical shell having at its lower and smaller end a short
reversed cone, within and below which latter are a series of nozzles of graduated
sizes each lower one being smaller than the one next above it. A jet of the
compressed air is directed into the smallest and lowest nozzle, and causes the
fire gases to be drawn upwards in between the several nozzles, the current thus
produced depending on the pressure and supply of compressed air which can be
regulated as found desirable in practice.
Dated this Thirtieth day of December 1890.
EDMUND HUNT,
Applicants' Agent.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Inducing Draught in Steam-boiler
Furnaces.
We, DAVID CROLL, Engineer, and CARL HOHN, Draughtsman, to the
Nederlandsche Stoomboot Maatschapij of Rotterdam, in Holland, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement that is to say :-
This invention has for its object to increase the efficiency of steam-boiler furnaces
by applying improved apparatus to induce an increased supply of air beyond that
given by natural draught, when as in the case of marine boilers, the chimneys or
funnels are of only moderate height.
In carrying out the invention in the case of a steam boat for example, we employ
an air compresser driven either from the main engines, or, as we prefer, by steam-
engine mechanism combined with the air compressing mechanism. The compressed
air is led by a pipe or pipes to induction apparatus placed inside the funnel or
chimney, or in each funnel or chimney when there are more than one.
And in order that the said invention and the manner of performing the same may
be properly understood, we hereunto append a sheet of explanatory drawings to be
hereinafter referred to, and representing a marine boiler as fitted with the improved
apparatus.
Figure, 1, on the sheet of drawings is a vertical section showing the interior of

page_text: the boiler and funnel but with the draught induction apparatus in elevation; and
Figure, 2, is a sectional elevation as at right angles to Figure, 1, with the draught
induction apparatus in vertical section. In these drawings the same reference
numerals are used to mark the same or like parts wherever they are repeated.
The induction apparatus which we prefer to use, comprises a long upper conical
shell, 3, fixed to the funnel, 4, by means of upper and lower angle-iron rings, 5, 6,
and having at its lower end a short reversed cone, 7, within and below which latter
are a series of nozzles, 8, 9, 10, 11, of graduated sizes, each lower one being smaller
than the one next above it. A jet of compressed air is directed into the smallest
and lowest nozzle, 11, and causes the fire gases to be drawn upwards in between
the several nozzles, the current thus produced depending on the pressure and
supply of compressed air which can be regulated as found desirable in practice.
The space, 12. between the upper conical shell, 3, and the shell, 4, of the funnel,
is utilised as a reservoir into which the compressed air is led by a pipe, 13, from the
air-compresser 14; and from this space, 12, the air passes by a pipe, 15, to the
lowest nozzle, 11.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what
claim is :-
In apparatus for inducing draught in steam-boiler furnaces, the employment
of compressed air in connection with a set of nozzles of graduated sizes arranged
in the funnel or chimney substantially as hereinbefore described.
Dated this Twenty-sixth day of September 1891.
EDMUND HUNT,
Applicants' Agent.