IMPROVEMENTS IN STEAM GENERATORS."
Year: 1876

page_text: LETTERS PATENT to David Midgley, of Stanningley, near Leeds, in the County
of York, for the Invention of "IMPROVEMENTS IN STEAM GENERATORS."
PROVISIONAL SPECIFICATION left by the said David Midgley at the Office
of the Commissioners of Patents on the 2nd February 1876.
DAVID MIDGLEY, of Stanningley, near Leeds, in the County of York. "IM-
PROVEMENTS IN STEAM GENERATORS.'
"
My Invention is designed to produce a compact and economical steam generator
readily accessible for examination, cleaning, and repair.
My improved generator is so constructed that the products of combustion are
caused to act first upon the surface of a fire-box surrounded by a water casing, the
lower portion of the fire-box presenting in the fire-box itself an inclined surface
against which the products of combustion impinge, and within the water casing a
surface so inclined as to facilitate the escape upward of the particles of steam
generated. From the fire-box the products of combustion pass laterally by radial
fire-tubes through the water casing into an annular flue surrounding the external
shell of the boiler in such manner as to cause the upper or steam containing portion
of the shell to be heated by the accumulation of heated air without the direct
contact with such upper portion of the highly heated products of combustion or
currents which have passed through the tubes into the annular flue. These highly
heated currents are caused to pass over or around the outer lateral portion of the
upper part of the water casing towards an opening in an annular division which
separates the flue into which the fire-tubes lead from a lower flue surrounding the
lower outer portion of the water casing. At this opening the currents meet, and by
it they descend into the lower annular flue wherein the heated products are again
divided, so as to pass in two directions around or over the lower outer lateral
surface of the water casing; they escape by a common opening into the uptake or
chimney regulated by a damper. The lower outer lateral surface of the water
casing is inclined or shaped like the frustum of an inverted cone to present a
better heating surface, and to facilitate the escape from its inner surface of the
steam there generated.
The water casing is provided with mud holes and doors, in conjunction with
which I arrange protecting tubes passing radially across the outer annular flue,
D

page_text: these tubes being so applied as not only to protect the mud holes from the action
of the heated products of combustion, but also, to allow of the mud hole doors being
seen, and their joints being made tight, or the doors removed for cleaning when
requisite from the outside of the boiler. The protecting tubes can also be removed
for cleaning the bottom annular flue from soot when required.
The lateral fire-tubes passing through those portions of the water casing situated
near the exit opening from the top annular flue may be made of smaller diameter
than the more distant tubes to promote equal distribution of the products of
combustion.
Access is provided to the flues and boiler for examination, cleaning, and repairs,
that portion of the outer iron casing (lined with fire-brick) opposite the lateral fire-
tubes being made in segments, and the fire-brick lining built within these segments,
all are removeable together.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Midgley in the Great Seal Patent Office on the 29th July
1876.
DAVID MIDGLEY, of Stanningley; near Leeds, in the County of York. "IM-
PROVEMENTS IN STEAM GENERATORS,'
"
My Invention is designed to produce a compact and economical steam generator
readily accessible for examination, cleaning, and repair.
My improved generator is so constructed that the products of combustion are
caused to act first upon the surface of a fire-box surrounded by a water casing, the
lower portion of the fire-box presenting in the fire-box itself an inclined surface,
against which the products of combustion impinge, and within the water casing a
surface so inclined as to facilitate the escape upward of the particles of steam.
generated. From the fire-box the products of combustion pass laterálly by radial
fire-tubes through the water casing into an annular flue surrounding the external
shell of the boiler in such manner as to cause the upper or steam containing portion
of the shell to be heated by the accumulation of heated air without the direct
contact with such upper portion of the highly heated products of combustion or
currents which have passed through the tubes into the annular flue. These highly
heated currents are caused to pass over or around the outer lateral portion of the
upper part of the water, casing towards an opening in an annular division which
separates the flue into which the fire-tubes lead from a lower flue surrounding the
lower outer portion of the water casing. At this opening the currents meet, and
by it they descend into the lower ánnular flue, wherein the heated products are
again divided, so as to pass in two directions around or over the lower outer lateral
surface of the water casing; they escape by a common opening into the uptake or
chimney regulated by a damper. The lower onter lateral surface of the water
casing is inclined or shaped like the frustum of an inverted cone to present a better
heating surface, and to facilitate the escape from its inner surface of the steam there
generated.
The water casing is provided with mud holes and doors, in conjunction with
which I arrange protecting tubes passing radially across the outer annular flue,
these tubes being so applied as not only to protect the mud holes from the action
of the heated products of combustion, but also to allow of the mud hole doors being
seen, and their joints being made tight, or the doors removed for cleaning when
requisite from the outside of the boiler. The protecting tubes can also be removed
for cleaning the bottom annular flue from soot when required.
The lateral fire-tubes passing through those portions of the water casing situated
near the exit opening from the top annular flue may be made of smaller diameter
than the more distant tubes to promote equal distribution of the products of
combustion.

page_text: Access is provided to the flues and boiler for examination, cleaning, and repairs,
that portion of the outer iron casing (lined with fire brick) opposite the lateral fire-
tubes being made in segments, and the fire-brick lining built within these segments,
all are removeable together.
попо
elevation of the same.
Fig. 3 is a sectional half plan taken at B, Fig. 4.
Fig. is a half sectional elevation.
Fig, 5 is a full sectional plan taken in the line A, A, Fig. 4.
Fig. 6 is a half sectional plan taken at C, Fig. 4, and shewing tubes.
Fig. 7 is a half sectional plan taken at D (Fig. 4), and shewing the top row of
tubes."
Fig. 8 is a side view shewing elevation of chimney and connections, also the
application of outside case in a steam generator of smaller size than that shewn in
the preceding Figures."
In each of the several Figures the same letters indicate like parts.
a is the inclined lower portion of the fire-box, at the bottom of which the fire is
contained upon grate bars a¹; b is the parallel sided upper portion of the fire-box,
which serves as a combustion chamber for the heated products prior to their passage
through the radial tubes; c, c, are the radial fire-tubes which pass from the upper
portion of the fire-box through the annular water space. Some of these tubes,
that is to say, those nearest the exit opening in the top annular flue, are of smaller
diameter than the others, for the purpose herein-before mentioned. d is the upper
portion of the first or upper annular flue, being storage room for heated air or gases
arising from the flame or products of combustion passing from the radial fire-tubes
below; e is the lower portion of the first or upper annular flue which receives the
highly heated products of combustion, and conducts the same around the boiler
shell to the opening f over the fire hole; f (see Fig. 3) is the opening leading from
the upper annular flue to the lower annular flue. The position of this opening may
be varied to suit circumstances, but it is preferable to place it over the fire hole;
and it must in all cases be directly opposite to the chimney. g is the lower annular
flue which conducts the partly exhausted flame or gases around the inclined lower
portion of the water casing to the chimney, the angular shape of this flue resulting
from the inclination of the outer lateral surface of the water casing towards the
bottom of the fire-box has the effect of creating in this flue a greater current or
draught, and preventing any choking or diminution in the draught from the fire-
box into the annular flue c, and onward to the chimney; h is the chimney, which
in all cases commences at or near to the bottom of the boiler, and the draught is
regulated by a damper h¹; i is an opening through the outer iron and brick casings,
into which is inserted a flanged plate j, whose inner edge fits against the outer
water casing to make up the flue, and maintain the opening necessary for admission
to the fire hole . This is connected by means of studs screwed into a strengthening
plate, which is rivetted around the opening in the iron casing, and nuts put thereon
can be removed at will for cleaning the front portion of the lower annular flue g.
is the lower and lesser annular water space, whose width increases gradually as it
proceeds upwards to the first joint immediately above the fire hole, and which con-
tains the mud holes for cleaning out at the bottom of the boiler; m is the wider
portion of the annular water space through which the radial fire-tubes pass; n is
the steam space, which is surrounded by the part of the upper annular flue;
o, o, are vertical stays connecting the crown of the fire-box to the crown of the
shell, the attachment being made by means of angle irons and pins, as shewn; p, p,
are the protecting tubes, which protect the mud holes and doors from the action of
the flame, and allow of the doors being seen while the boiler is at work. These
protecting tubes pass through the outer iron and brick casings; the inner ends of

page_text: the tubes fit against the outer water casing, and the outer ends are flanged and
connected to the outer iron casing by means of strengthening plates and studs with
nuts. The tubes can be readily removed when required for clearing soot and other
deposits from the lower annular flue. q is the outer wrought-iron plate casing,
which is made up in segments of any required sizes with flanges projecting inwards
and outwards, both vertically and horizontally, as shown at band b, in Figures 2,
4, 6, and 7, and at 63, in Figures 2 and 5; these flanges are made of T shaped iron,
one flange being connected by rivetting to the outside of the plate. The flanges
projecting outward are connected by bolts to allow for taking asunder when
required, and the flanges projecting inward form frames which surround and support
each segment of the inner fire-brick casing, which I fix in place by means of
wrought-iron pins of about half an inch in diameter passing through the flanges-
.into the fire-brick, as shewn at 6, Fig. 3, and 6, Figs. 6 and 7, and c¹, Fig. 4; the
ends of the pins are flush with the outer lateral surfaces of the iron flanges. The
several portions of fire-brick intended to form each segment of lining are secured
together before being inserted into the frame formed by the projecting inner flanges
of the metal segment. The vertical edges of the fire-brick segments nearest the
vertical iron flanges are made parallel to each other, so as to readily enter the
frame, and before inserting the fire-brick seginent I fill the angular space at each
side of the inner part of the metal segment with fire-clay, so that the fire-brick
seginent when inserted shall be nicely bedded in the frame, the angular layer of
fire-brick with which the two vertical flanges are lined presenting to the fire-
brick segment surfaces parallel to its own vertical edges. Thus the fire-bricks
are held firmly after having been placed tightly and fixed, as described, within
the frame formed by the flanges. Holes and pins may also be provided through
the horizontal flange of the top part of each segment, the pins passing into corre-
sponding holes in the bricks if thought requisite. To make the pins through the
inner flanges effective I unite all the bricks together as one piece within each frame
by means of the same method, namely, two holes are formed in each brick, as shewn
at e, Fig. 4, these holes being about one and a half inches in depth, and the bricks
are united by iron pins, as shewn at 63, Fig. 3; a sufficient number of fire-bricks to
fill the frame of the segment are fastened together by these pins, and then lifted
into the segment frame as one whole brick, and the pins are afterwards inserted
through the iron flanges. Every segment having these surrounding flanges each
can be lined with bricks before putting together or building up the two outside
casings of brick and iron, or any one of the segments can be removed for cleaning,
examination, or repairs to the boiler by taking out the bolts of the horizontal and
vertical flange joints, and removing the proper segment without disturbing the
other segments. I prefer making that portion of the outer casing directly opposite
the ends of the radial fire-tubes with a greater number of segments in its circum-
ference than the bottom or other portions of the casing, as shewn in contrast at b²,
Figs. 6 and 7, and b, Figure 5, on account of their being oftener removed for
cleaning than the other portions of the casing.
It will be obvious that the number of rings employed according to my Invention
will vary to suit the generator to which they are applied.
In Fig. 8 I show the application of the outside case in a steam generator of
smaller, size, The casing is in a lesser number of segments than the one shewn in
Fig. 2; but in all cases those segments opposite the ends of the radial tubes will be
smaller than the other segments. This alteration may also be embodied in the
casings of larger generators having a greater number of rings than shewn in Fig. 2.
are sections of fire-brick, which are of a uniform thickness throughout; they are
of section, so that they form a lining for the segments in top and bottom rings of
iron casing, and form the flue covers, as shewn at Figs. 3 and 4; s are circled fire-
bricks of a uniform thickness throughout, and without the angle or cover, as in 1, 1.
These are used for lining the bottom part of the top ring of segments, also the
iniddle segments, as shewn in Figs. 4, 6, and 7.
The arrows shew the progress of the products of combustion from the fire-place..

page_text: Having described the nature of my said Invention of "Improvements in Steam
Generators," and explained the manner of carrying the same into practical effect, I
desire to have it understood that save and except, as herein-after mentioned, I do
not intend to claim any of the parts of the generator herein shewn and described
when taken separately and apart from the combination or application thereof in
manner and for the purposes herein described.
I am aware that it is not new to construct a boiler with a fire-box tapered at its
lower part to give increased grate surface, that fire-box being surrounded by a water
casing.
I also know it has been proposed to use in a steam generator a water casing
having radiating fire-tubes through it, and a lined outer casing forming a flue
around the outside of the boiler shell, such flue extending upward around the steam
space; but I am unaware of this having been done in the peculiar way proposed
by me.
Furthermore, I do not claim per se the use of annular flues surrounding the shell
of a boiler having a water casing, so that the products of combustion pass through
a tube crossing the said water casing, thence into one of the flues, and from it into
a second flue; but I believe the arrangement proposed by me, whereby the products
of combustion are caused to pass in a downward direction from one annular flue to
another, and thence to the chimney, so as to prevent excessive heating of the steam
space, and also of the lower part of the water casing to be new.
By my Invention the products of combustion, entering the flue at the back part
of the boiler, have to pass (divided) over practically the entire circumference of the
upper portion of the water containing part of the shell before proceeding into the
lower Hue, and in that flue have to return to the back of the boiler, thereby keeping
the products long in contact with the heating surface of the boiler, and so thoroughly
utilizing the heat.
Also my peculiar arrangement of the flues, providing as it does for the accumu-
lation of heated air around the steam space, enables me to superheat the steam
economically without danger of overheating the boiler plates.
By constructing the water casing at its lower part with two cones extending to
a common level, namely, to about the level of the first joint in the outer iron case
and below the radial fire-tubes, I obtain not only a considerable length of tube-
heating surface and water space, but also a large area of fire-grate surface below,
besides presenting heating surface of a more effective character; and by this
arrangement I also obtain the angular form of the lower flue, the advantages of
which I have herein-before explained.
Another feature is the arrangement of the smaller tubes at or over the opening
in the annular flue to equalize the distribution of the products of combustion.
Also the peculiar construction of the segmental casing, whereby I ain enabled to
readily remove any segment or segments with its or their lining constitutes a
feature the value of which will be at once realized by persons conversant with the
practical working of steam generators.
And having thus indicated some of the leading peculiarities of my Invention, I
desire in conclusion to have it understood that what I consider to be novel and
original and therefore claim as the Invention secured to me by the herein-before
in part recited Letters Patent is, the combination of parts forming the improved
steam generator constructed, arranged, and operating as shewn in and described
with reference to the accompanying Drawings.
In witness whereof, I, the said David Midgley, have hereunto set my hand
and seal this Twenty-seventh day of July, in the year of our Lord One
thousand eight hundred and seventy-six.
DAVID MIDGLEY. (L.S.)