VISIONAL DIETITIA
Year: 1897

page_text: PROVISIONAL DIETITIA
Improvements in connection with the Application of Forced Draught
to Steam Boiler and other Furnaces, and in Apparatus and
Appliances employed therein.
I, WILLIAM HARMAN, of Hume Street, Stockton-on-Tees, in the County of
Durham, Engineer, do hereby declare the nature of this invention to be as
follows:
-
This invention relates to the application of forced draught to steam boiler and
other furnaces.
The object in view is to raise the temperature of the forced draught by heat
absorbed from the waste gas escaping up the furnace funnel or uptake, and the
means used are a free intermixture of the air and the said waste gases before
delivery into the said furnace.
I will in describing a suitable apparatus for the purpose of my invention refer
to its application to a marine boiler as representing its utility generally and in
what manner it can be advantageously applied to other furnaces worked by forced
draught. In the case of a marine boiler a fan of the usual construction is
attached to the smoke box in such a manner that by means of a slide or some
equivalent device air from the outside and the heated waste gases within the
smoke box are drawn into the fan in regulated proportions so that the air absorbs
heat from the said waste gases without risk of premature combustion being set
up before the furnace is reached. The fan rotates within a drum the openings
or inlets into which are partly within and partly without the smoke box casing
or are otherwise arranged to effect the same purpose. An adjustable slide works
in front of and controls each of these said openings after the fashion of an
ordinary ventilator slide, so that the opening within or leading to the smoke box
to
relatively
the
outside
is enlarged
opening
the
casing according to the relative proportion in which waste gases are to
be mixed with the air. If found desirable a baffle plate or hood projects
into a smaller box to collect and intercept hot waste gases for the supply
of the fan. In the case of boilers having the usual arrangement of tubular flues,
I prefer to insert crescent shaped ferrules into the ends thereof with the thick
part upward, thereby contracting the said tubes in area in a manner that will
not intercept the clearance of deposit therefrom the said ferrules being removable
when the forced blast apparatus is not in use.
or
contracted

page_text: Improvements in connection with the Application of Forced Draught
to Steam Boiler and other Furnaces, and in Apparatus and
Appliances employed therein.
I, WILLIAM HARMAN, of 15, Hume Street, Stockton-on-Tees, in the County of
Durham, 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 the application of forced draught to steam boiler and
other furnaces.
The object in view is to raise the temperature of the forced draught by heat
absorbed from the waste gases escaping up the furnace funnel or uptake, and the
means used are a free intermixture of the air and the said waste gases before
delivery into the said furnace.
I will in describing a suitable apparatus for the purpose of my invention refer
to its application to a marine boiler as representing its utility generally and in
what manner it can be advantageously applied to other furnaces worked by forced
draught. In the case of a marine boiler a fan of the usual construction is
attached to the smoke box in such a manner that by means of a slide or some
equivalent device air from the outside and the heated waste gases within the
smoke box are drawn into the fan in regulated proportions so that the air absorbs
heat from the said waste gases without risk of premature combustion being set
up before the furnace is reached.
In combination with such apparatus I also prefer to insert ferrules or plug
shaped retarders into the ends of the boiler tubes for strengthening and con-
tracting the said tubes in area in a manner that offers no obstruction to the soot
and will not intercept the clearance of deposit therefrom.
Having so far described the nature and utility of my invention,
will now
proceed to further explain the same by referring to the drawing hereto annexed,
which is intended to illustrate a convenient manner in which my improvements
are to be carried out in practice.
Referring to the drawing in which is illustrated a marine boiler fitted with my
improved forced draught apparatus, Fig. 1 is a sectional view of the smoke box
taken on line xx of Fig. 2 which is a corresponding end view of same. Fig. 3
is an enlarged end view and Fig. 4 a corresponding sectional view of a ferrule or
plug shaped retarder constructed according to my invention. The fan a of the
usual construction rotates within a drum b the oval openings or inlets 6163 into
which are partly within and partly without the smoke box casing c.
In the con-
struction shown an adjustable slide d furnished with a circular opening d works
in front of and controls each of these said openings 616 after the fashion of an
ordinary ventilator slide so that the openings within or leading to the smoke
box are enlarged or contracted relatively to the openings outside the casing
according to the relative proportion in which waste gases are to be mixed with
the air. Each slide d is controlled by a hand lever e so that by moving the slide
inwardly until the opening extends within the smoke box casing as shown in
Fig. 1, an inlet is formed for the waste gases to pass from the smoke box into
the fan and then delivered by the pipe f to the furnace. By drawing the slide d
out until the opening d is clear of the smoke box casing the gases are shut off
from the fan and only outside air is delivered to the furnace. It will now be
seen that the fan can be adjusted to draw in both gas and air in any regulated
proportion to be freely intermixed and discharged through pipe f which is fur-

page_text: nished with two check valves gg to control the forced draught to either of the
furnaces as shown. h is a baffle plate or hood projecting over the fan into the
smoke box to collect and intercept hot waste gases for the supply of the fan.
In the case of boilers having the usual arrangement of tubular flues I prefer
to insert ferrules or plug shaped retarders ; as shown in Figs. 3 and 4 into the
ends thereof with the large diameter inward, thereby strengthening and con-
tracting the said tubes in area in a manner that offers no obstruction to the soot
These ferrules or
and will not intercept the clearance of deposit therefrom.
retarders are readily stamped from a flat plate so as to form the fin shaped exten-
sion on the back thereof, and are simply inserted into the ends of the tube and
rigidly held in position by their own elasticity, the said ferrules or retarders
being removeable when the forced draught apparatus is not in use. By making
them of the form shown that is tapering from a larger to a smaller end they tend
to deflect the escaping currents of waste gases into line with the hood h.
But the tubes can be similarly contracted in area by the insertion of crescent
shaped ferrules with the thick part upward.
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. The arrangement and combination of parts which enables the waste gases
from the flues of a furnace to be mixed in any regulated proportion with the
outside air to be supplied to the furnaces as forced draught substantially as and
for the purpose as hereinbefore described and illustrated by way of example in
the accompanying drawing.
2. In connection with furnaces of the kind herein before referred to an improved
forced draught apparatus in which a fan placed partially within the smoke box
is furnished with adjustable slides for regulating the admission thereinto in suit-
able proportions of the hot waste gases from the furnace flues and air from the
outside thereby raising the temperature of the forced draught the said apparatus
being arranged constructed and operating substantially as herein before described
with reference to the accompanying drawing.
3. As a means of throttling the flue tubes of a furnace when used for forced
draught the use of a plug shaped ferrule or retarder as shown in Figs. 3 and 4
or of other equivalent device such as a crescent shaped ferrule set with the thick
part upwards, the ferrule or retarder being adapted for its purpose substantially
in the manner herein before described.
D
1 1
01.
T
1000