Improvements in Forced or Induced Draught Apparatus for Steam Boiler or other Furnaces.
Year: 1899

page_text: Date of Application, 1st Nov., 1899
Complete Specification Left, 1st Aug., 1900-Accepted, 8th Sept., 1900
Improvements in Forced or Induced Draught Apparatus for Steam
Boiler or other Furnaces.
I, ROBERT HARRISON LONGWORTH, of 19, Mildmay Road, Bootle, in the County
of Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has for its object an arrangement whereby a forced or induced
draught can be instituted without the usual noise of the air jet, and be more
effective and economical than any forced draught at present known to me.
I bring the air from the front of the fireplace by one or more flues, or from
the outside in any other convenient manner to a heating chamber in the flue or
furnace or preferably itself forming the bridge or the back of the bridge, or
forming the base of the bridge, but in all instances having a large amount of
heating surface. From this chamber a short tube projects back into the ash-
nit. In the combustion chamber or other portion of the heating space I place a
superheater for steam and bring a jet of superheated steam into the centre of
this backward pointing tube. This jet is preferably of pepper box top form
with three, four or more orifices formed of 16 holes delivering superheated
steam jets at an angle or cone whose base is the periphery of the delivering tube
in the ashpit. There may be several of these delivering tubes if desired,
instead of one, and with corresponding jets. I may also deliver air from the
heating chamber up the bridge, and place orifices in the back of the bridge
so as to assist the force of the current over the bridge, and also to supply oxygen
at this point so as to assist the burning of the smoke. These orifices can be
supplied with superheated steam jets or not, as desired. A suitable valve can
be used to regulate the exit at this point as required. By arranging the main
supply of air with its jet at the back of the furnace, instead of at the front,
the usual disagreeable noise caused by this jet is almost or quite drowned, and
is therefore hardly heard at the stoke hole, or at least is very much deadened
in sound. In order further to deaden this sound and to strengthen the air
tubes, I form them of cast iron with longitudinal ridges or flanges preferably
of about of an inch in thickness.
Improvements in Forced or Induced Draught Apparatus for Steam
Boiler or other Furnaces.
I, ROBERT HARRISON LONGWORTH, of 19, Mildmay Road, Bootle, in the County
of Lancaster, Engineer, do hereby declare the nature of this invention and in
D' dl

page_text: what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
'
This invention has for its object an arrangement whereby a forced or induced
draught can be instituted without the usual noise of the air jet, and be more
effective and economical than any forced draught at present known to me.
The invention is best described by aid of the accompanying drawings, in
which
Figure 1 shows a vertical section through the line X X; Figure 2 a horizontal
section through the line Y Y and Figure 3 a part front view and part-section of
boiler furnace made in accordance with my invention.
In these A A are two flues bringing air from the front of the fire place
through the ashpit to a chamber B in or below the bridge; Ca central nozzle
on this chamber pointing backward into the ashpit. There can be several of
these nozzles if desired but this is unnecessary, also only one or several air
tubes A. D is a steam pipe passing along under the furnace, it could however
with advantage be placed on and passing the whole length of the furnace or
through the Hlues or coiled round in the furnace or other heating space so as to
superheat the steam. This superheating is not absolutely necessary but is
desirable. The drawing shows my experimental apparatus which I have
hitherto followed, in which the steam pipe passes through the ashpit to a super-
heater in the flue. I only show this arrangement as it is the only one I have
tried in practice and found effective, the others (passing the pipe through the
furnace &c) I have not tried. E is the superheater which can be of any form
and can be dispensed with if the pipe D be coiled in the heating space or passed
through the furnace. F, a nozzle carrying the superheated steam from the
superheater and emitting it in several diverging jets at the nozzle C so as to
force a current of air out of C into the ashpit. The jet is preferably of pepper box
top form with three, four or more orifices formed of 16 holes delivering super-
heated steam jets at an angle or cone whose base is the periphery of the delivering
tube in the ashpit. There may be several of these delivering tubes if desired,
instead of one, and with corresponding jets. I may also deliver air from the
heating chamber up the bridge, and place orifices in the back of the bridge
so as to assist the force of the current over the bridge, and also to supply oxygen
at this point so as to assist the burning of the smoke. These orinces can be
supplied with superheated steam jets or not, as desired. A suitable valve can
be used to regulate the exit at this point as required. By arranging the main
supply of air with its jet at the back of the furnace, instead of at the front,
the usual disagreeable noise caused by this jet is almost or quite drowned, and
is therefore hardly heard at the stoke hole, or at least is very much deadened
in sound. In order further to deaden this sound and to strengthen the air
tubes, I form them of cast iron with longitudinal ridges or flanges preferably
of about 3 of an inch in thickness, and either internal external or both. In
the drawing the bridge and chamber B are shown distinct and separate in which
case they are connected by a suitable pipe with or without a valve or damper
but they can be made all in one piece if desired.
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:-
The several improvements in forced or induced draught apparatus for steam
boiler and other furnaces which consists-
(a) In placing the injection nozzle at the back of the ashpit in place of the
front as heretofore whereby the noise is greatly lessened;
(b) Bringing the air to the nozzle from the front in ribbed pipes;
(c) In combination with the nozzle pointing into the ashpit from the rear a
superheated steam jet or jets and

page_text: (d). In combination with a forced draught system having the aforesaid
improvement (a), a hollow bridge with regulated opening for the admission of
air at this point, and a steam jet device for forcing same--each substantially
as and for the purposes described.
T
WM. P. THOMPSON & Co.,
Patent Agents, of Liverpool, Manchester, Birmingham, & London.