Improvements in or relating to the Air Supply or Draught for Furnaces.
Year: 1899

page_text: Date of Application, 30th Dec., 1899-Accepted, 10th Feb., 1900
COMPLETE SPECIFICATION.
Improvements in or relating to the Air Supply or Draught for
Furnaces.
I, ALFRED FRIEDEBERG, Civil Engineer, of Schulzendorferstrasse 26, Berlin,
N., Empire of Germany, do hereby declare the nature of the said invention, and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement: —
Furnaces in which a draught is introduced under the grate as constructed at
present, including those which are worked by means of a steam blast, or those
worked by a ventilator in combination with a steam blast for the purpose of
cooling the grate, all suffer from the drawback that the currents entering the
furnace are uneven both with regard to pressure and the mixture of steam and
air, while on the other hand the distribution of the blast within the ash-pit is also
not uniform, both the pressure and the quantity of the current passing through
the grate at different places varying to a great extent. These conditions result
in the very great drawback that, according to the uneven draught admission the
process of combustion of the fuel is also very uneven, for instance, the fuel at the
back part of the grate is quickly consumed, while that at the front is consumed
only partially and slowly. Further in those parts of the grate, where the pressure
of the current happens to be small, the combustion gases are liable to be driven
into the ash-pit where, mixing with an excess of air they form compounds which
frequently cause explosions.
The present invention relates to an arrangement which is calculated to avoid
all the above drawbacks.
The object of this invention consists in evenly mixing the air and steam cur-
rents or air currents coming from any suitable generator or source in a mixing
chamber before they are admitted to the grate itself, and to divide the mixture
thus rendered uniform in the ash-pit by means of special air dividers for the
purpose of rendering the draught in all parts of the grate of equal quantity and
equal pressure.
In the accompanying drawing such an arrangement is represented, in Figure 1
in longitudinal section, and in front sectional view in Figure 2.
The air current is introduced or forced into the ash-pit H of the steam boiler
or generator K through a pipe system G, the latter communicating with a closed
mixing chamber A, which may be constructed of any suitable material such as.
for instance, sheet iron or the like, or as represented in the drawing, of masonry
arranged beneath the floor of the boiler house. The currents enter the mixing
chamber A through an injector or steam blast device B, to which steam is sup-
plied through the steam pipe C, or to which air is supplied by a ventilator D
and pipe E. When working with several steam blast devices it is exceedingly
difficult to obtain from them an equal pressure of the air-steam current and the
proportion of air and steam forming such current. These currents are thoroughly
mixed in the mixing chamber. A special advantage is that it is possible to com-
bine the work by passing the currents coming from the ventilator or other air
supply and the steam and air mixture of the steam injector into the mixing

page_text: chamber. In the same manner it is possible to combine a current of pure steam
with the air current. In every case the air and steam currents are thoroughly
mixed in the mixing chamber whereby a mixture is produced thoroughly uniform
as regards composition and pressure. Under such conditions it is possible to so
regulate the current with regard to the proportion of air and steam that the cur-
rent passing through the conduit G to the grate is of even pressure and constant
composition.
The current passing through the conduit G passes before its entry into the
ash-pit H through the branches N directly connected with the conduit G. These
branches consist of tubes the orifices of which are directed against or across each
other in such a manner that the currents cross each other in entering the ash-pit.
The currents entering the ash-pit with great speed lose their speed in consequence
of such crossing and become thoroughly divided in consequence of which the
medium of combustion in the ash-pit is perfectly even as regards quantity and
pressure and hence the process of combustion is equally even, and can be carried
out in the most perfect manner.
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. In connection with furnaces the method of introducing air and steam cur-
rents through a steam injector or the like (or in combination with other mechani-
cally produced air currents, or the latter in combination with a current of pure
steam) into a mixing chamber before entering the place of combustion, in which
chamber they are regulated and evenly mixed as regards pressure, and com-
position of air and steam, being thence led to the furnace through a branched
conduit the orifices of which are directed downwards and inwards in such a man-
ner that the currents entering the ash-pit strike against and cross each other
substantially as described.
2. An arrangement of mixing chamber and draught inlet for furnaces substan-
tially as described or illustrated in the accompanying drawings.
Dated this 30th day of December 1899.
BOULT, WADE & KILBURN,
Agents for the Applicant.