IMPROVEMENTS IN THE MEANS OF AND APPARATUS FOR GENERATING AND HEATING STEAM IN STEAM BOILERS AND OTHER VESSELS, AND FOR HEATING THE LIQUID CONTENTS THEREOF
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Owen Murrell at the Office of
the Commissioners of Patents, with his Petition, on the 30th April
1870.
I, OWEN MURRELL, of Bethnal Green Road, in the County of
Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MEANS OF AND APPARATUS FOR GENERATING AND HEATING
STEAM IN STEAM BOILERS AND OTHER VESSELS, AND FOR HEATING THE LIQUID
CONTENTS THEREOF," to be as follows:-
-
This Invention relates to certain improvements in the method of
generating steam and heating water in steam boilers and other vessels,
and consists chiefly of improved arrangements of hollow fire-bars and
apparatus connected therewith. I am aware that hollow fire-bars have
heretofore been used in furnaces in various ways.
According to my Invention I take a series of lengths of the tubular
bars and connect their extremities by means of double elbow joints or
screw sockets, such elbows forming junctions to the tubes in similar
sequence as though the tubes were made in one length and bent in a
serpentine form. Now these bars being set in the furnace it follows that

page_text: the extreme heat of the fire will act on them and not on the boiler
surface alone. The pipes extend from end to end of the furnace hori-
zontally, and are supported on bearing bars at each end, and if necessary
on an intermediate bearing bar, as hereafter described.
The water in steam boilers or other vessels passes through the entire
series of bars, and a connecting pipe set outside the front of the boiler,
or in some other suitable position, serves to convey the water heated by
the tubes upwards and into the boiler. The feed pipe from the boiler
to the bars first bends downwards, and then like an inverted syphon
ascends upwards to form the necessary junction with the bars. The 1
importance of this arrangement depends on the fact that by the cir-
culation of water thus afforded the throttling in the furnace tubes is
altogether avoided, thus preventing the destruction of the bars from
such cause. Suitable cocks or valves are applied for feeding, stopping,
blowing off, guaging and testing, as required.
I now proceed to describe the arrangement of the tubular fire-bars in the
furnace. These bars being first connected together by the double elbow
joints are laid on the bearing bars at each end of the furnace, and if
necessary supported also by an intermediate bearing bar. The bearing
bars at each end are formed of cast iron or plates with flanges secured
thereon, and ribs or vertical plates are fixed to form partitions and
recesses to receive the elbow joints, which do not make contact with the
backs of the bearing bars or with the ribs, spaces being left for expansion
and for a vertical draft of air at the back of cach elbow between it
and the flange of the bearing bar. Not only does this space permit of
expansion, but by cutting out or casting slots in the horizontal surface,
corresponding or nearly so with such space, the draft is increased, and
the accumulation of dirt avoided: Each tube is protected with a shield
throughout its length in which the tube rests, its internal surface fitting
or nearly so the external surface of the circular tube, the outside section :
presenting vertical flanges terminating in angles meeting at a point
beneath the centre of the shield, each end of which has an enlarged or
shouldered bearing surface. But the sides of the shields are formed with
a series of projections and recesses or air spaces of tapering shapes, tho
body of the shield being about ½ inch thick and the projections about
% inch; or other sizes may be used if required. It thus follows that
when the bars and shields are arranged in the furnace double the
quantity of air will pass up between the shields and spaces than would

page_text: otherwise pass if plain shields only were used; thus combustion will
be aided, smoke avoided, and an increase of heating power obtained.
In furnaces where a sluggish draft exists I apply between each shield
an intercepting or intermediate solid bar containing on cach side a
similar series of projections and air spaces, which may be made to
correspond in position opposite cach other; or the projection on one side
may correspond with a space on the other throughout the length of the
bar. So also these spaces and projections may be made to correspond
with those on the shields, so that a projection and space shall always be
presented to each other. The thickness of the body of the bar should be
about / inch and the projections ¾ inch; or any other proportions may
be used to suit different descriptions of furnaces.
Now in order to secure the tubes, shields, and bars firmly to the bear-
ing bars, instead of using band clips, as formerly practised, I propose to
employ a series of short, hollow, cast-iron stems, having tapering curved
heads, the tops of which present an oblong square surface; the curved
under surfaces of the heads corresponding with the upper portions of
the tubular bars; these stems are placed on the bearing bars over holes
made therein, and then a bolt is passed through the countersunk cavity
on the surface of the stem and pillar, and through the bearing bar,
when a nut screwed to the bolt beneath the bar tightens the wholo
together, and clips the tubes and shields, thus giving a nearly flat or
flush surface to the series of bars, no projections shewing above the
tubes to interrupt the firing or stoking, and thus avoiding an incon-
venience hitherto felt from that cause.
In furnaces where coke is used as fuel, or where the draft is extra-
ordinarily quick, I propose to use a cast-iron shield on the upper side of
cach tube bar, the sides of which are provided with air spaces or pro-
jections similar to those formed on the shields for the under sides. These
air spaces may also be continued diagonally across the top of the shields.
By the use of these top shields, which can easily be removed and replaced
without disconnecting the tubular bars, the tubes are protected from
the destructive action of the fire.
Now, the application and use of the upper and lower shields, con-
structed with grooves and projections as described, in combination with
tubular bars, and also the grooved or corrugated solid bars in combina-
tion with tubular bars for admitting an extra supply of air, together with
the improved methods of clipping the whole and securing them in posi-

page_text: tion, and effecting draught behind each elbow junction, and preventing
accumulation of dirt, and the arrangement to allow for expansion, form
the special features of this Invention. These arrangements are ap-
plicable not only to steam boiler furnaces, but to various forms of boilers
or vessels for heating water or other liquid contents thereof. It will be
evident that by the application of the grooved shields the area for
draught will be doubled, and the intensity of the furnace correspond-
ingly increased, while the tubular bars will be protected from the action
and effect of cold air on their under sides; their rapid absorption of heat
enabling them to generate steam and deliver the same into the boiler;
and as provision is made for expansion and contraction all liability
to leakage is obviated. The bars may readily be removed from the
furnace, in order to clean the flues and perform repairs, because it is
only necessary to unscrew two union joints to detach the whole series
from the boiler. So also in regard to those furnaces where there is only
a sluggish draught, the intervention of the solid grooved bar between
the tubes will remedy the disadvantage, and although a less number of
tubes would result on account of the distance of their intervals, yet the
increase of heat caused by the more complete combustion of the fuel
would to a great extent compensate for the decrease in the number of the
tubular bars.
Where an extra bearing bar running transversely under the middle of
the tubes is used, I also apply my improved clips to keep the shields
and tubes firmly in position, but of course these clips would be of a less
superficial area than those at each end of the tubes and end bearing bars,
because these latter extend from the back flanges of the bearers, within
the wings or divisions equal in length thereto, whereas the clips of the
middle bearing bar need only be of small superficial dimensions as
regards the longitudinal direction of the tubes on which they act as
clamps. The general arrangement of the bars and appurtenances are in
themselves sufficient to generato steam for some purposes, the boiler
being placed at a distance therefrom in a separate part of a building, and
not exposed to the direct action of the fire.