Improvements in Steam and Hot Water Grates and Generators.
Year: 1898

page_text: Date of Application, 17th May, 1898-Accepted, 6th Aug., 1898
COMPLETE SPECIFICATION."
Improvements in Steam and Hot Water Grates and Generators.
I, JOSEPH CRAWHALL CHAPMAN, Chartered Patent Agent, of 70, Chancery Lane,
in the County of London, do hereby declare the nature of this invention (which has
been communicated to me from abroad by FRANKLIN GREENAWALT SAYLOR,
Chemist, of 25, Edgewood Street, Roxbury, Boston, Massachusetts, United States
of America) 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 generators for either steam or hot water, and has more
particular reference to a water grate and connections for promoting the circulation
and the combustion and the objects of my invention are to make a generator which
shall consume the smoke and other products of combustion, expose a large surface
area of the water wall to the most intense heat of the furnace, and to so construct
the water grate and connections, and the walls and settings of the generator as
to both economize fuel and intensify the heat obtained. My invention consists
in a box or pocket grate with walls formed in whole or in part of water legs having
connections through which water circulation is maintained from the boiler to and
through the water grate and return to the boiler, and in the other novel features
which will be fully described in the specification and particularly pointed out in
the claims at the end thereof.
In the drawings I have illustrated my invention as applied to a return fire tube
boiler, but it may be applied to various other forms of boilers. Fig. 1 is a plan
of a grate and its supports and of the mud drum in front and the connections of
the water legs therewith, and the rear connections with the bridge tank which is
broken away, the grate bars being omitted from the left hand section to clearly
show the side rests, and the end blocks which should go between the ends at front
and rear of the right hand pair of water legs to close the ends of the trough being
omitted to show the lugs on which the blocks are supported. Fig. 2 is a cross-
section on line 2, 2, of Fig. 1, looking toward the rear, but with the left hand grate
in position. Fig. 3 is a side elevation partly in section on line 3, 3 of Fig. 1
illustrating the connections of the water leg with the boiler, the hot air passages
through the bridge wall tank and the baffle wall. Fig. 4 is a section on line 4, 4,
of Fig. 3, looking toward the front. Fig. 5 is a section on line 5, 5, of Fig. 3
looking toward the rear, the bridge tank wall being cut away to more clearly show
the tank. Fig. 6 is a side elevation of one of the water legs and connections, partly
in section, on a larger scale, the end blocks being omitted. Fig. 7 is a plan of a
portion of one of the water legs and the extension lip which is to rest on the end
resting bar. Fig. 8 is an end view of Fig. 7. Fig. 9 is a side elevation of Fig. 7.
Fig. 10 is an isometric illustration of a modified form of water leg and showing
connection with the front mud drum. Fig. 11 is a side elevation, partly in section,
illustrating another modified form of water leg. Fig. 12 is an end view of the
water leg of Fig. 11 detached. Fig. 13 is a plan of still another modified form of
water leg. Fig. 14 is a section on line 14, 14, of Fig. 13, and Fig. 15 is a section

page_text: on line 15, 15, of Fig. 13. Figs. 16, 17 and 18 illustrate yet another modifica-
tion of water leg. Figs, 19, 20 and 21 illustrate the application of my invention
to a water leg boiler.
1 designates a boiler, 2 the side wall setting, 17 the front wall, 18 the doors to
the fire box and 19 the doors to the ash-pit, 3 the front circulating pipes and 4 the
rear circulating pipes. The grates represented are of the so-called box or pocket
or trough-grate type, in which the grates are alternately on different levels, the
drawings showing five grates, the first third and fifth of which are surface grates,
each being designated by the numeral 5, and the second and fourth are lower
grates, each designated by the numeral ( and forming the bottoms of the boxes
or pockets. The two side carrying bars for the grates are marked 7, the two end
rests are marked 8, and the center rest 9. The grate bars 10 are operated by the
levers 11 to shake and turn the lower grates. The rear circulating pipes 4, which
are virtually water legs, lead from the boiler I to the bridge wall tank or rear
mud drum 12, and the front circulating pipes 3 lead from the front mud drum 13
back to the boiler, the circulation from the bridge wall tank to the front mud drum
being through the hollow water grate walls or legs 14, as will be more particularly
described hereinafter. A blow-off pipe 20 leads from the mud drum 13 and a
blow-off pipe 21 leads from the bridge wall tank 12. The circulating pipes may
stand at any angle, as shown by the dotted lines marked 28 in Fig. 3. With the
box or pocket type of grate a much more complete combustion and more intense
heat is obtained than by use of an ordinary flat top grate, and one of the
objects of my invention is to utilize and economize this heat by having the
water circulate through conductors which are directly and closely exposed to this
heat at the location of greatest intensity. The side walls of the boxes or pockets
as heretofore made have usually been either solid or perforated for air circulation.
I make these side walls 14 hollow with tubular connections 15 with the mud
drum 13 in front, and connections 16 with the bridge wall tank 12 at the rear for
the circulation of the water. These side water walls or legs are preferably oblong
in cross-section, as clearly shown in Figs. 2 and 5, partly because it is undesirable
to have too thick a wall between the prates to obstruct the air circulation but
mainly because a thin wall of water will heat better. With the circulating pipes
arranged as shown in Figs. 3, 4 and 5, the circulation will start from the rear
circulating pipes and go through the water grates from rear to front, as the rear
circulating pipes connect with the boiler at a higher level than do the front circulat-
ing pipes. The tubular connections 15 and 16 are preferably of smaller sectional
area than the water legs whereby the water which has reached a high degree of
heat in the water legs is forced rapidly out and an active circulation is maintained
throughout the entire system. On one side of each of the water walls or legs 14
are lugs 22, and on the side of the side carrying bars 7 are also similar lugs,
which form rests for the upper grates, said upper grates being removable. On
the ends of the said water legs at both front and rear are extension lips 23 which
rest on the end bars S. Crosswise of the water legs are inside braces 24. End
blocks 25 of fire brick or other suitable material close the ends of the trough
between the water legs, or as shown in some of the modifications hereinafter
described, each pair of water legs has a water connection between the two legs at
the ends. The fuel fills the troughs to the level of the surface grates and then
a thin layer is spread over the whole top so that there is burning fuel in the trough
in direct contact with one side of each water leg and also on the top surface of
the water legs. The thick body of fuel in the troughs, owing to its depth, burns
more slowly than the thinner body on the surface grates, and is more of a gas
generator, the gases which arise therefrom mingling at the surface with the fresh
air which comes up through the surface grates.
The bridge wall tank 12 is supported on the wall 26 and preferably has a
facing 27 of fire brick for protection. The bridge wall and tank form a partition
between the fire box and combustion chamber, rising to some distance above the
grate but not entirely to the top of the chamber, thus allowing a passage over the

page_text: top of the wall for the smoke, and other products of combustion, into the combus-
tion chamber. Extending from front to rear through the facing 27 and bridge
tank 12 are a series of hot air passages 29 to take the air at its extreme heat near
the surface and conduct it into the rear part of the combustion chamber where it
comes into contact with the smoke and other unconsumed products of combustion
and ignites them. In this kind of grate the fire just above the surface grates has
the greatest intensity. These hot air ducts are preferably arranged one for each
grate, and starting alternately at different levels, as shown in Fig. 5, being
upwardly inclined from front to rear through the tank, but all coming out on the
rear side on the same level with each other. See Figs. 3 and 5, in which the
passages are shown in dotted lines. The entrance ends of the ducts for the surface
grates are a little lower than the ducts from the trough grates, so as to afford
passage for fresh air from below the grates which mingles with the highly heated
air taken from the surface. The exact location of these ducts and the angle will
vary somewhat according to the boiler and the conditions of use.
The ducts may
be horizontal.
A baffle wall 30 extending crosswise of the combustion chamber at the upper
part thereof hangs downward below the level of the top of the bridge wall tank
80 that the current of hot air will be deflected and retarded after it passes over the
top of the bridge tank before it can pass to the rear part of the chamber and gain
entrance to the return fire tubes of the boiler so as to make the combustion more
complete. It is desirable, however, not to contract the passage, and therefore the
horizontal distance from the baffle wall to the bridge wall tank should be about
the same as the vertical distance from the bottom of the baffle wall to the bottom
of the chamber.
By means of the water leg grate and the active circulation of water obtained,
the sediment which always tends to collect at the bottom of the boiler, is carried
down through the rear circulating pipe to the bridge wall tank, and from thence
the bulk of it will also be carried on through the water legs to the front mud
drum where it will be deposited until blown off.
In the modification shown in Fig. 10, the water legs forming the walls of the
trough are composed of a coil of pipe 41, one end 42 of the coil being connected
with the front mud drum, and the other end, broken away in the drawings, being
connected with the bridge wall tank. In this way there is a circulation of the water
through both walls of the trough and entirely around the same and through the
entire coil before it can reach the mud drum. There is a bottom grate to this
trough as in the form previously described, the grate being omitted in the drawing
of Fig. 10 to more clearly illustrate the form of water leg.
In the modification shown in Figs. 11 and 12 the water leg still retains the
same general form of greater depth than thickness as already described, and also
the contracted connections with the mud drum and with the bridge wall tank.
The water leg in this form is a flattened pipe with contracted ends integral there-
with to make the connections instead of separate pipe connections.
In the modification shown in Figs. 13, 14, and 15, each pair of water legs are
connected together at each end by a hollow cap or head 51 which has an opening 52
to receive the pipe connections 15 and 16 with the mud drum and bridge wall tank
respectively. The legs are illustrated in this form as composed of an inverted
U-shaped upper portion 53 set into a flanged lower portion 54, the two portions
being riveted together and the oblong shaped tube thus formed then having the
caps or heads put on the ends and riveted, the single connection of each head with
the mud drum and tank serving for both legs of each pair. In this form of con-
struction the connections are more easily made than when made in one single piece.
Lugs 22 for supporting the grates are secured to the sides of the legs.
In the modification shown in Figs. 16, 17 and 18 there is a union of each pair
of legs at the end, there being common inlet and outlet openings 62 for connec-
tion with the mud drum and bridge wall tank, the head 61 in this case being
integral with the legs 63. The legs are also made in series, the front pair being

page_text: connected together at their rear ends by a connecting portion 64 which is connected
by a pipe 65 with the head 66 of the next pair 67, thus forming a series of pockets
connected together, the rear pocket being connected with the bridge wall tank.
71 is
In the modification shown in Figs. 19, 20 and 21 in which my invention is
represented as applied to a water leg boiler, Fig. 19 is a cross-section through the
water legs of the boiler, showing in interior plan only so much as is necessary to
properly illustrate the invention. Fig. 20 is a vertical section and Fig. 21 is a
detail of the dumping part of the grate in the bottom of the pot or pocket.
the water leg of the boiler. Inside of the chamber formed by said water leg 71
is a smaller ring-shaped water leg 72 supported on carrying bars 73. Pipes 74
connect this water leg with water leg 71 of the boiler. At the bottom of the
central opening through the water leg 72 are dump grates 80 operated by the grate
bars 75, thus forming a pocket the water leg 72 forming the side walls of the
pocket. The surface grates 76 are supported at the inside edge by lugs 77 on the
side of water leg 72 and at the outer edge are supported on the rail 78 resting on
the lugs 79 on the inside of the boiler leg. A portion only of the surface grate
is shown for clearness of illustrating the other parts. Instead of a single pocket
and water leg 72 there may be several connected together.
Having now particularly ascertained and described the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. A box or pocket grate consisting of grates of alternating level, the grates on
the lower level forming the bottom of the box or pocket, and having water legs
which form the sides of the box or pocket, substantially as described.
2. In combination with a boiler or hot water reservoir, a box or pocket grate
consisting of grates of alternating level, the grate on the lower level forming the
bottom of the pocket and having water legs which form the sides of the pocket,
and water way connections between the boiler or reservoir and said water legs
whereby circulation is completed from the boiler or reservoir to the water legs,
thence through the water legs and return to the boiler or reservoir by another way,
substantially as described.
3. In combination with a boiler or hot water, reservoir a box or pocket grate
consisting of grates of alternating level, the grate on the lower level forming the
bottom of the pocket and having water legs which form the sides of the pocket, a
bridge wall tank at the rear of the grate and water pipe connection between the
boiler or reservoir, and said tank, and between the said tank and the water legs,
a mud drum at the front end of the grate, and water pipe connections between said
water legs and said mud drum and between said mud drum and the boiler or
reservoir whereby a complete circulation is made, substantially as described.
4. In combination with a boiler or hot water reservoir, a box or pocket grate
consisting of grates of alternating level, the grates on the lower level forming the
bottom of the pocket and having water legs which form the sides of the pocket,
a bridge wall tank at the rear of the grate and water pipe connection between the
boiler or reservoir and said tank and between the said tank and the water legs, a
mud drum at the front of the grate and water pipe connections between the water
legs and the mud drum, and between the mud drum and the boiler or reservoir,
the outlet from the water legs being of smaller sectional area than the sectional
area of the water legs, substantially as and for the purpose described.
5. In combination with a boiler or hot water reservoir and grate, a bridge wall
tank at the rear of the grate, a partition between the fire box and combustion
chamber but not extending to the top of the chamber and having a series of hot
air ducts leading from the fire box to the combustion chamber, substantially as
described.
6. In combination with a boiler or hot water reservoir and grate, a bridge wall
tank at the
rear of the grate rising above the level thereof but not
the top of the chamber and having a series of hot
extending to

page_text: air ducts from the fire box through the tank to the combustion chamber, the open-
ings to said ducts being in part above and in part below the surface of the grate,
substantially as described.
7. In combination with a boiler or hot water reservoir, a box or pocket grate
consisting of grates of alternating level, the grate on the lower level forming the
bottom of the pocket and having water legs which form the sides of the pocket,
a bridge wall tank at the rear of the grates and water conduits from the boiler
or reservoir to the tank, from the tank to the water legs, and from the water legs
to the boiler or reservoir, said bridge wall tank forming a partition back of the
fire box part way to the top of the chamber and having a series of hot air ducts
leading from different levels through the tank to the combustion chamber, the
entrances to some of the ducts being so located as to conduct fresh air from below
the surface grates as well as the hot air from above the surface, and other ducts
conducting the gases which rise from the box part of the grate, substantially as
described.
8. In combination with a boiler or hot water reservoir and grate, a bridge wall
tank at the rear of the grate rising part way above the level thereof, hot air ducts
leading from the fire box through the tank and into the combustion chamber, a
baffle wall within the combustion chamber at some distance back of the tank and
projecting from the roof part way to the bottom of the chamber, substantially as
described.
9. In combination with a boiler or hot water reservoir and grate, a bridge wall
tank at the rear of the fire box, and a series of hot air ducts from the fire box through
said tank and into the combustion chamber, the said ducts starting at alternating
levels and opening into the said combustion chamber at a higher level than the
entrance ends, substantially as described.
10. In a box or pocket grate consisting of grates of alternating level, a series of
pockets of which the walls thereof are composed of water legs, the water legs of one
pocket being connected by a water conduit with the water legs of another pocket,
substantially as described.