Improvements in Forced Draught Apparatus for Boiler and other like Furnaces.
Year: 1896

page_text: Date of Application, 23rd May, 1896
Complete Specification Left, 10th Dec., 1896-Accepted, 6th Mar, 1897
PROVISIONAL SPECIFICATION.
Improvements in Forced Draught Apparatus for Boiler and other
like Furnaces.
1, JOSEPH KNOWLES BROADBENT of 4 Islington Square, Salford in the County
of Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to that type or class of apparatus for producing forced
draught for steam generator and other furnaces, in which there is a closed ash-pit
containing steam jet blowers. When such apparatus, as at present constructed, is
used, it is necessary, in order to prevent risk of the flame passing into the stoke
hole, to shut off the steam supply from the blowers before opening the furnace
door, and to move the air damper by hand. The object of these improvements is to
obviate these defects and to cause the supply of air to be regulated automatically.
For the purpose of my invention I employ the existing steam pipe and steam blower
or blowers in the closed ash-pit but dispense with the damper. Just within the
furnace door, I arrange a semiannular air box the face of which next the furnace
is perforated with holes through which air from the ash-pit can be supplied to the
fire. The two bases of this air box, which forms a kind of arch over the dead plate,
are closable by dampers which control corresponding passages communicating with
the closed ash-pit. It is arranged that upon the door of the furnace being opened,
these dampers shall be opened, thus admitting a full supply of air under pressure
from the ash-pit, to enter the front part of the furnace, in addition to the supply
through the grate. When the door is closed, the dampers are left open, and
immediately commence to close by the action of gravity. As however it is
undesirable that they should close quickly, I connect them with a timing device,
such as that described and illustrated in and by the Specification of Letters Patent
granted to me No. 15095 dated the 22nd August 1892.
Deted this 22nd day of May AD 1906
COMPLETE SPECIFICATION.
Improvements in Forced, Draught Apparatus for Boiler and other
like Furnaces.
I, JOSEPH KNOWLES BROADBENT, of 4 Islington Square, Salford in the County
of Lancaster, 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 that type or class of apparatus for producing forced
draught for steam generators and other furnaces, in which there is a closed ash-pit
containing steam jet blowers. When such apparatus, as at present constructed, is
used, it is necessary in order to prevent risk of the flame passing to the stoke-hole,

page_text: to shut off the supply of steam to the blowers before opening the furnace door, and
to move the air damper by hand. The object of these improvements is to obviate
the cessation of the steam jets, and the movement of the damper, and to cause the
supply of air to be regulated automatically.
I will describe my said invention with reference to the accompanying drawings in
which-
Figure 1 represents a front elevation:
Figure 2, a cross section:
Figure 3, a longitudinal section: and
Figure 4, a sectional plan.
For the purpose of my invention, I may employ the existing steam pipe A, and
the steam blowers B B, in the ash-pit C, but I dispense with the existing damper,
in the dead plate or bridge. Just within the furnace door C, I arrange a semi-
annular or similarly shaped air-box D, the face of which next to the furnace is
perforated with holes E, through which air under pressure from the ash-pit, can be
supplied to the fire. The two bases of this air box, or only one of them, which
rest upon the dead plate F, are or is closable by a damper or dampers G, which
control passages leading from the closed ash-pit to the air box. These dampers are
arranged to be opened simultaneously with the furnace door and to be gradually
closed after the furnace door is again closed. This operation of the dampers is
effected by means of a cranked arm H on or near the hinge of the furnace door.
This arm communicates by the links I, with the arm J, which is fixed upon the
rocking shaft K, upon which the damper G, or both the dampers, is or are fixed.
Thus, when the furnace door is opened, the dampers are also opened, and the air
from the ash-pit passes into the furnace through the perforations in the box D. If
the dampers should be closed at the same time with the furnace door, after stoking,
combustion would be incomplete for some time, and smoke would be produced.
I obviate the production of smoke from this cause by the adoption of appliances
whereby the dampers are gradually closed. There is a variety of such appliances
which are quite well known, but I prefer to use that which is described and
illustrated in and by the Specification of Letters Patent granted to me No. 15095
dated the 22nd day of August A.D. 1892. This apparatus M, is also set in action
on the opening of the furnace door, by the crank arm H, through the slotted
angular lever N and the chain O. The opening of the furnace door winds up the
clock work in M. The weight of the open dampers then acts upon the clock-work
which delays and regulates their descent to the closed position.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is-
1. In forced draught apparatus for boiler and other like furnaces, an air box
within the front part of the furnace, through which air can be supplied to the
furnace from the ash-pit, constructed and arranged substantially as hereinbefore
described and as illustrated by the accompanying drawings.
2. In forced draught apparatus for boiler and other like furnaces, an air box
within the front part of the furnace through which box air can be supplied to the
furnace from the ash-pit, a damper or dampers controlling the admission of air from
the ash-pit to the air box, and appliances for opening the dampers when the furnace
door is opened and for closing them slowly after the furnace door is closed,
constructed and arranged substantially as herein before described with reference to
the accompanying drawings.
Dated this Ninth dox of Dossenhas A D 1000
W. E. HEYS & SON,
Agents for the Applicant.