June 6, 1913.

THE COLLIERY GUARDIAN.

1159

Reprinted from the “Colliery Guardian.”

The BENNIS Self=Cleaning Compressed=Air Furnace.

THE bulk of the readers of the Colliery Guardian are
keenly interested in the question of obtaining
cheap steam and a smokeless chimney, and it
was with a view to examining the installation
of two of the Bennis furnaces, installed at a Wakefield
Colliery, that we recently made a visit there. With
this particular installation the furnaces were hand-fed,
though we know that the Bennis mechanical stokers
also have met with very considerable success in the
large number of industrial works where they are
in use.

In general terms the Bennis patent self-cleaning
compressed-air furnace consists, as shown in fig. 1, and
in the photograph of its interior, fig. 2, of a large
number of tubular fire troughs placed close together

source of power, and the motion is so arranged that the
whole of the bars advance together with the furnace,
thus carrying with them the ash and clinker, but they
are withdrawn independently. Special provision is made
to take up the wear of the cams on the compressed-air
bars, and takes the form of highly-chilled east iron
wedge wearing pieces dovetailed into sockets in the
bars. These wedges are easily renewable, and take off
any wear and tear on the bars.

The clinker and ash are slowly carried forward to the
end of the bars, where they fall over into a closed chamber,
and after giving off their heat to the boiler are removed
as required by pulling the chain shown in fig. 1, which
raises a door, also shown, when the ashes, &c., can be
raked out.

Fig. 1.



Fig. 2.

a



Fig. 3.

J?

A.
rvr

I

■> I

• ,

/.• / ■

* ***

•

ft *. t

; *<





and shielded from the direct action of the heat by means
of easily replaceable interlocking grate bars. The
tubular bars, where they emerge from the furnace, are
cone-shaped, and into these cones a fine jet of super-
heated steam is made to play, on the principle of an air
injector. Air is thus forced in under considerable
water-gauge pressure, and the air and steam, issuing
between the bars, maintain a clear bright bed of fire,
which can be easily regulated by simply turning the
steam on or off as required. The spaces between the
firebars are very narrow, but are always free and open,
so that the draught is evenly distributed over the whole
bed of fire, which ensures the satisfactory combustion
of breeze, dust coal and low class fuel generally.

The mechanism for moving the firebars or troughs is
arranged on the front of the boiler and is thus easily
accessible. The shaft carrying the cams, which
operate the bars, can be driven from any convenient

The general arrangement of the interior is better
shown in fig. 2, where it will be seen that the side
bars are made toothed so that they can be chipped
and adapted to any irregularities on the inside of the
flue. There are two means of control—the one which
regulates the movement of the firebars, and the other
which governs the admission and exclusion of air, and
so the combustion of the fuel, by means of steam taps to
each nozzle, both being easily and almost instantaneously
accessible, and within reach of the stoker in charge. The
type of the Bennis furnace which we have just described
is shown in fig. 3, which is a photograph of a long range
of furnaces at another well-known colliery, but on a
larger scale.

Write for “ The Reduction of Working Costs in Steam
Collieries pamphlet to Ed. Bennis and Co. Limited,
Little Hulton, Bolton, or 28, Victoria Street, S.W.