IMPROVEMENTS IN STEAM BOILERS to be as follows:-
Year: 1884

page_text: I, GEORGE FENWICK, of 3 Regent Terrace Gateshead in the County of Durham,
Engineer, do hereby declare the nature of said invention for "IMPROVEMENTS IN
STEAM BOILERS to be as follows:-
"
My invention relates to certain improvements applicable especially to marine or
other boilers of multitubular type, or such boilers in which the flame and heated
gases, after passing from the furnace through the combustion chambers and tubes
or flues; can be afterwards in the chimney or uptake, made to impart heat to
external air, in its passage through a chamber or vessel surrounding (or partly
surrounding) the uptake or chimney at the hottest part; such air (after being so
heated) being used for the purpose of supplying the furnaces to increase the
evaporative power of the boiler and to economise fuel.
As applied to a return tube boiler, of the ordinary marine type, I construct
around the lower portion of the chimney an annular chamber open at top, to admit
the external air, and at bottom, in communication, by suitable chambers or passages,
with the lower portion or "ash-pits" of the furnaces which are entirely closed in,
up to the level of bars, excepting gratings fitted with slides by means of which air
may be admitted, when necessary, in certain régulated quantities.
The bars which I propose to use are of the hollow or tubular kind, but in
connection with such hollow bars, I use a "dead plate" having air passages
corresponding with and leading to the air passages in the bars, so as to convey
the external air through the bars to a hollow bridge and there to mix with the
gases at back of furnace. The heated air, brought from the chamber surrounding
the chimney, or uptake, is drawn into the furnace, by the induced draft of the
furnace itself, under the bars,' and has no outlet except through the bars, and
through the fuel on the bars and thence to meet the air which has passed through
the hollow dead plate and hollow bars to back of "bridge."

page_text: I GEORGE FENWICK of 3 Regent Terrace Gateshead in the County of Durham,
Engineer, do hereby declare the nature of my invention for "IMPROVEMENTS IN
STEAM BOILERS" and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
My invention relates to certain improvements applicable especially to marine
or other boilers of multitubular type, or such boilers in which the flame and heated
gases, after passing from the furnace through the combustion chambers and tubes
or flues can be afterwards, in the chimney or uptake made to impart heat to
external air, in its passage through a chamber or vessel surrounding (or partly
surrounding) the uptake or chimney at the hottest part; such air (after being so
heated) being used for the purpose of supplying the furnaces to increase the
evaporate power of the boiler and to economise fuel.
As applied to a return tube boiler, of the ordinary marine type, I construct
around the lower portion of the chimney an annular chamber open at bottom and
at top which is covered with a hood to admit the external air, and at bottom in
communication, by suitable chambers or passages, with the lower portion or
"ash-pits" of the furnaces which are entirely closed in, up to the level of bars,
excepting gratings fitted with slides by means of which air may be admitted, when
necessary, in certain regulated quantities.
"
The bars which I propose to use are of the hollow or tubular kind, but in
connection with such hollow bars, I use a dead plate" having air passages
corresponding with and leading to the air passages in the bars, so as to convey
the external air from "stoke-hold" through the bars to a hollow bridge and there
to mix with the gases at back of furnace. The heated air, brought from the
chamber surrounding the chimney, or uptake, is drawn into the furnace, by the
induced draft of the furnace itself, under the bars and has no outlet except through
the bars and through the fuel on the bars and thence to meet the air which has
11
halla ham to book of bridge

page_text: The Full Arrows indicate the course of the air from stoke-hole through dead
plate, hollow bars and bridge.
The Dotted Arrows indicate the course of the heated air from chambers (3. 3)
down air-boxes (4. 4) into closed ashpits (5. 5) under fire bars and through spaces
between bars, through and over fuel to bridge.
Although I have illustrated my invention as applied to a Marine Boiler of the
ordinary type it is applicable to any form of boiler with certain modifications by
which the flame or gases after leaving the boiler can be made to heat the external
air to be conveyed into closed ash pits while external air is admitted through a
perforated dead plate and hollow bars behind the bridge to mix with the air
heated by waste flame or gases.
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. Heating the external air by means of waste heat passing from boiler through
an uptake or chimney and drawing the heated air into closed ash-pits to pass
through spaces of bars and through and over the fuel by natural draft: combined
with the introduction of external air through a perforated dead-plate to hollow fire
bars conducting it to back of bridge to mix with the heated air substantially as
shewn and described.
2. For the purpose of heating external air by means of waste heat passing from
a boiler through a chimney or uptake and drawing said heated air into closed ash-
pits to pass through the spaces of bars and through and over the fuel by natural
draft combined with the introduction of external air through a perforated dead-
plate to hollow fire bars conducting it to the back of bridge to mix with the heated
air; the application of the various parts comprising air casing (2) chambers (3. 3)
air-boxes (4. 4) (closing in the ash-pits (5. 5)) perforated dead plate (7) hollow
bars (6. 6) and hollow bridge (8) arranged, constructed and operating substantially
as shewn and described.