IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES
Year: 1877

page_text: LETTERS PATENT to William Welch, of Aston, near Birmingham, in the County
of Warwick, Mechanical Engineer, for the Invention of "IMPROVEMENTS IN
STEAM BOILER AND OTHER FURNACES."
Sealed the 18th January 1878, and dated the 23rd July 1877.
PROVISIONAL SPECIFICATION left by the said William Welch at the Office
of the Commissioners of Patents on the 23rd July 1877.
WILLIAM WELCH, of Aston, near Birmingham, in the County of Warwick,
Mechanical Engineer. "IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES."
My said Invention consists in forming the grate or fuel-carrying part of the said
furnaces of a series of endless chains constructed and arranged and worked in the
manner herein-after described.
In constructing a furnace according to my Invention I dispense with the ordinary
fire-bars, and I arrange a series of parallel rollers at a short distance below the
plane in which the fire-bars are ordinarily situated. These rollers are arranged
transversely, the ends of their axes working in bearings situated at the sides of the
furnace. A series of four of the said rollers, one at the front, another at the back
of the furnace, and two intermediate ones, are ordinarily sufficient, but I do not
limit myself to any particular number.
In addition to the rollers described another roller is situated at the front of the
furnace at a lower level than that in which the series of rollers described is
situated.
The front roller of the series and the front roller at the lower level are chain
rollers, that is, rollers having teeth or projections, which engage with chains passing
over them, and prevent the chains from slipping, the chains travelling with the
rollers.
The chain or toothed rollers are driving rollers, motion being communicated to
them by steam or other power. The other rollers are bearing rollers.
A series of endless chains pass over the rollers, each of the chains forming a loop
of such a length that between the two driving rollers a portion hangs loosely, the
bottom of the loop dipping in a trough filled with water. The chains are parallel
[Price fid]

page_text: and close to one another, and constitute the support for the fire, forming, as it were,
a series of flexible or chain bars.
The fuel is fed from a hopper or otherwise at the front of the furnace, and a slow
motion being communicated to the chains by the driving rollers, the fuel is slowly
conveyed to the back of the furnace, its combustion being completed by the time it
has arrived there. The ash falls over the roller at the back of the furnace.
Those portions of the chain bars on which the fuel is supported are kept tight
by the chain rollers, the hanging loop described being formed by those portious of
the chains which, having left the furnace, are about returning. By the dipping of
the said loops into the water troughs described the chains are thoroughly cooled
after leaving and before re-entering the furnace.
Very free access of air to the burning fuel is permitted by the said chains, and a
vigorous and complete combustion is thereby secured.
My Invention is especially applicable to the furnaces of steam boilers, but is also
applicable to other furnaces.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Welch in the Great Seal Patent Office on the 19th January
1878.
WILLIAM WELCH, of Aston, near Birmingham, in the County of Warwick,
Mechanical Engineer. "IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES."
My said Invention consists in forming the grate or fuel-carrying part of the said
furnaces of a series of endless chains constructed and arranged and worked in
the manner herein-after described.
In constructing a furnace according to my Invention I dispense with the ordinary
fire-bars and bearers, and I arrange a series of parallel rollers at a short distance
below the plane in which the fire-bars are ordinarily situated. These rollers are
arranged transversely, the ends of their axes working in bearings situated at the
sides of the furnace. A series of four of the said rollers, one at the front, another
at the back of the furnace, and two intermediate ones, are ordinarily sufficient, but
I do not limit myself to any particular number.
In addition to the rollers described another roller is situated at the front of the
furnace at a lower level than that in which the series of rollers described is
situated.
The front roller of the series and the front roller at the lower level may be chain
rollers, that is, rollers having teeth or projections, which engage with chains passing
over them, and prevent the chains from slipping, the chains travelling with the
rollers.
The chain or toothed rollers are driving rollers, motion being communicated to
them by steam or other power. The other rollers are bearing rollers.
A series of endless chains pass over the rollers, each of the chains forming a loop
of such a length that between the two driving rollers a portion hangs loosely, the
bottom of the loop dipping in a trough filled with water, or the hanging loop may
be kept tight by a roller in the water trough. The chains are parallel and close to
one another, the upper layer constituting the support for the fire, forming, as it
were, a series of flexible or chain bars.

page_text: The fuel is fed from a hopper or otherwise at the front of the furnace, and a slow
motion being communicated to the chains by the driving rollers the fuel is slowly
conveyed to the back of the furnace, its combustion being completed by the time it
has arrived there. The ash falls over the roller at the back of the furnace.
Those portions of the chain bars on which the fuel is supported are kept tight by
the chain rollers or by the roller in the water trough, the hanging loop described
being formed by those portions of the chains which having left the furnace are
about returning. By the dipping of the said loops into the water trough described
the chains are cooled after leaving and before reentering the furnace.
Very free access of air to the burning fuel is permitted by the said chains, and a
vigorous and complete combustion is thereby secured.
My Invention is especially applicable to the furnaces of steam boilers, but is also
applicable to other furnaces.
Having explained the nature of my Invention I will proceed to describe, with
reference to the accompanying Drawing, the manner in which the same is to be
performed.
Figure 1 represents in longitudinal vertical section the furnace of an externally
heated steam boiler, the grate or fuel-carrying part of the said furnace being
constructed and arranged according to my Invention; Figure 2 is a plan of the said
grate or fuel-carrying part of the furnace; and Figure 3 is an end élevation of the
same taken at the front of the grate.
Figures 4 and 5 represent two of the carrying or supporting rollers of the grate.
The same letters of reference indicate the same parts in the several Figures of the
Drawing.
a, a, a, are the series of endless chains constituting the grate or fuel-carrying part
of the furnace. The said endless chains are supported and guided by the carrying
and guiding transverse rollers represented. Three rollers, marked respectively b, c,
and d, are situated at the front of the furnace, the roller & being near the bottom
of the furnace, and one roller, marked e, is situated at the back of the furnace
immediately under the bridge g. Two small intermediate rollers f, f, are also
arranged to support the upper layer of the endless chains, the said endless chains
being stretched tightly between the rollers b, e, c, and d. The several rollers, with
the exception of the roller d, turn in bearings in the sides of the furnace, as repre-
sented. The two front rollers b, c, are the driving rollers by which the endless
chains a, a, a, are moved, the said rollers b, c, being coupled together by the
pinions h, i.
By an examination of Figure 1 it will be seen that the endless chains a, a, a, pass
over the upper driving roller b, over the small intermediate rollers f, f, around the
rear end roller e, and from thence over the lower driving roller c. The chains then
pass down vertically to the bottom roller d, under which they pass and ascend to
the upper driving roller b. The bottom roller d, under which the depending parts.
of the chains a, a, a, pass, is situated in the water trough k, so that as the said
chains travel under the said roller they dip into the water in the said trough k, and
are thereby cooled. The rollers b, c, d, e, f, are grooved with a series of parallel
grooves or guides, as best seen in the detached views of two of the said rollers
represented in Figures 4 and 5. These grooves or guides are at a distance apart
equal to that of the series of parallel endless chains a, a, a, forming the grate or
flexible fire-bars.
The vertical links of the endless chains engage with the grooves in the rollers,
while the horizontal or alternating links bear upon the cylindrical surface of the
rollers as the said chains pass over them.
By causing the vertical links of the endless chains to engage with grooves or
guides in the driving and bearing rollers, and the horizontal or alternating links to
bear upon the cylindrical surface of the rollers, as described and represented, the
alternate links of the chains are preserved in their proper relative positions; that
is, in planes at right angles to one another as they pass over the rollers. The said

page_text: grooves or guides also preserve the chains parallel to one another, and at the
required distances apart.
The driving rollers b, c, may have teeth or projections upon them to engage in
the alternate links which present their openings to the rollers. The said teeth or
projections may, however, be dispensed with, and the required tension put upon the
chains by means of the roller d, the bearings of which are made capable of being
raised and lowered for that purpose.
The fuel may be fed on to the flexible or chain bars or grate a, a, a, through the
hopper at the front of the furnace; or the said fuel may be hand-fed through the
fire-door m...
The upper driving roller b is driven by worm gearing or otherwise, so as to cause
the driving rollers b, c, to cominunicate a slow motion to the endless chains a, a, a,
in the direction of the arrows, Figure 1. By the travelling motion of tho said
endless chains or flexible grate a, a, a, the fuel fed to the front part thereof is slowly
carried to the back of the furnace, its combustion being completed by the time it
has arrived at the back of the said furnace. The ash falls over the end p of the
grate at the back of the furnace on to the inclined bed q, down which it passes to
As the heated
the ash-pit r, from which it may be removed through the door at 8.
travelling endless chains a, a, a, pass through the trough k they are cooled by the
water contained therein. By this arrangement the chains are cooled before they
reenter the furnace. A current of cold water may be arranged to pass through the
trough k.
Although I have only represented my Invention as applied to the furnace of an
externally heated steam boiler, yet my said Invention may also be applied to the
furnaces of Cornish or internally heated boilers and tubular or other boilers, and to
other furnaces.
The application of my Invention to the furnaces enumerated and other furnaces
differs in no material respect from its application to the steam boiler furnace
described and represented.
Having now described the nature of my Invention and the manner in which the
same is to be performed, I wish it to be understood that I claim as my Invention,―
The improvements in steam boiler and other furnaces herein-before described and
illustrated in the accompanying Drawing; that is to say, forming the grate or fuel-
carrying part of the furnace of a series of travelling endless chains stretched
between and working over guiding grooved rollers, or rollers having teeth or
projections on them, substantially as described and illustrated.
Also cooling the travelling endless chains by causing the hanging loops of the
said endless chains to dip into water after leaving and before reentering the furnace,
substantially as described and illustrated.
In witness whereof, I, the said William Welch, have hereunto set my hand
and seal, this Twelfth day of January, in the year of our Lord One thousand
eight hundred and seventy-eight.
Witness,
GEORGE SHAW.
WILLIAM WELCH. (L.S.)