Year: 1895

page_text: Date of Application (in United Kingdom), 30th Aug., 1895
Complete Specification Left, 30th Aug., 1895-Accepted, 14th Dec., 1895
I, ALFRED METCALF HEWLETT, Manufacturer, of Kewanee, in the County of
Henry and State of Illinois, United States of America, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
In the accompanying drawings,
Figure 1 is a front elevation of a furnace such as is used for puddling, busheling
or other purposes;
Figure 2 is a longitudinal vertical section of the same;
Figure 3 is an end view of the rotary grate ;
Figure 4 is a side elevation thereof;
Figure 5 is an end view of the part shown in Figure 4, looking to the left;
Figure 6 is a vertical section on line 6-6 of Figure 3;
Figure 7 is a front elevation of a steam-boiler furnace having in combination a
mechanical stoker;
Figure 8 is a partial vertical section on line 8-8 of Figure 7;
Figure 9 is a front elevation of a gas producer;
Figure 10 is a vertical section on line 10-10 of Figure 9 ;
Figure 11 is a partial longitudinal vertical section, showing a modified arrange-
ment of the grate;
Figure 12 is a vertical cross section showing a modified arrangement of the air
or steam blast pipe; and
Figure 13 is a longitudinal vertical section showing another modification of
the grate
Heretofore many attempts have been made to produce a furnace adapted for
puddling, busheling or melting metal, or for producing gas, which would satisfactorily
burn ordinary bituminous coal under a blast, but so far as I am aware none of such
attempts have proved successful. Such failure has been due principally to the fact
that in the furnaces heretofore constructed for the use of soft or bituminous coal, it
has been impossible to properly consume the fuel, as with soft coal the blast caused
a running together or packing of the fuel into a solid mass of clinkers, thereby
seriously interfering with the draft, the result being that the necessary temperature
could not be maintained. Another reason for such failure is that such furnaces
have not been provided with adequate means for loosening and removing the
clinkers, as is frequently necessary, thereby occasioning considerable delay ard
reducing the tonnage.
By reason of the objections above pointed out the use of soft-coal furnaces for
puddling, busheling, &c., has been practically abandoned, crude petroleum being
used instead with satisfactory results. Recently, however, owing to the diminished

page_text: supply of petroleum, and its consequent increased cost, as well as to the much
greater cheapness of soft coal, in certain localities it has become extremely
desirable if not absolutely necessary-to substitute soft coal for oil as fuel; and
to provide a furnace which will produce satisfactory results by the use of such coal
is the object of my present invention.
I have discovered that by providing suitable means for facilitating the removal
of what clinkers are formed without permitting the furnace to cool, and at the
same time securing a much higher temperature than heretofore by generating
combustible gases for combustion in the furnace, and thereby preventing to a great
extent the formation of clinkers and the packing of the coal upon the grate, all
such objections may be avoided and an intensely hot fire which will give very
satisfactory results be produced by the use of bituminous coal.
In the drawings I have illustrated several forms of furnaces involving my
invention, as will hereinafter be described in detail.
Referring to the drawings,
In Figs. 1 & 2, 14 indicates the front wall of a puddling or busbeling furnace.
15 indicates the bridge wall. 16 indicates the ash-pit. 17 indicates the front wall
of the ash-pit, which, is inclined and projects forward of the front wall of the
furnace, so that access may be had to the ash-pit. 18 indicates a door in the front
wall of the furnace. 19 indicates a door through which fuel is introduced into the
fire box of the furnace. 20 indicates a door through which the furnace is
charged with the metal. 21 indicates a revolving grate, which is mounted on
trunnions 22-23 journaled in opposite sides of the furnace. The trunnion 23
carries a gear 24 see Fig. 4. 25 indicates a pinion, which is suitably supported
and meshes with the gear 24, as shown in Figure 5. 26 indicates a crank for
rotating the pinion 25. By this construction the grate 21 may be rotated by hand.
If desired, instead of using the crank 25, the grate may be rotated by power, as
will be hereinafter described.
As best shown in Figures 3, 4 and 5, the grate 21 is made up of a number of
sections 27 secured to end disks 28-29, such sections being preferably secured in
place by bolts 30 through which pass keys 31, as best shown in Figure 6, the bolts
passing through flanges 32 on the end plates 28-29. Each of the sections 27 is
provided with a number of perforations or air passages 33, as best shown in
Figures 2 and 4. The exterior surfaces of these sections 27 are such that the grate
will
present a roughened or corrugated appearance, sufficiently so to adapt the grate
to retain and carry around with it as it is rotated, the clinkers as they are formed.
Such corrugations or depressions may be of various forms, and I therefore do not
desire to restrict myself to the specific form shown. As best shown in Figure 2,
the grate 21 is mounted between the bridge wall and the front wall of the furnace,
aud its diameter is such as to almost fill the space between such two walls, the
object of which is to prevent the coal being carried down with the clinkers.
also shown in Figure 2, the ash-pit is partially filled with water, the depth of the
water being sufficient to partially submerge the grate and to extend slightly above
the lower edge of the front wall 14. The clinkers and ashes, being delivered from
the grate by its rotation, fall into the ash-pit. They may then be raked forward, and
removed by the operator standing in front of the furnace, owing to the projecting
front wall 17 of the ash-pit, as best shown in Figure 2.
As
The air or steam blast is admitted to the furnace below the bed of fuel on the
grate through a pipe 34, which opens into the upper part of the ash-pit opposite
the disk 28, which is in close proximity to the wall of the furnace. In order to
permit the air or steam to pass into the grate 21 openings 35 are provided in the
disk 28 at suitable intervals, so that as the grate rotates the air or steam will be
permitted to pass into it, and thence it passes upward through the openings 33 to the
fire. The escape of air in any other direction from the ash-pit will, however, be
prevented by the water therein.
Should it be desired to remove any or all of the sections of the grate this may be
accomplished by opening the door 18, when ready access will be given to said sections.

page_text: The doors 18 are lined with fire brick to protect them from the intense heat of the
furnace.
When the furnace is in operation, at suitable intervals, preferably just after each
charge of metal is withdrawn, the grate is partially rotated, thereby causing what
clinkers have been formed upon it to be discharged into the ash-pit. This is
facilitated by the water therein, which softens the clinkers so that they drop off
more readily. By thus rotating the grate a substantially clean active grate area
is presented, thereby permitting the air or steam blast to pass freely through it.
After thus removing the clinkers a fresh supply of fuel is thrown upon the grate
and the furnace is again charged with metal.
As will appear from an inspection of the drawings, the air or steam blast enters
below the upper or active surface of the grate, which in furnaces of this description
carries a bed of fuel of from 12 inches to 16 inches in depth, and it has free
communication with the water in the ash-pit, that is to say, the blast and the water
are not cut off from each other. The result is that the grate, being highly heated,
generates steain under the bed of fire from the water in the ash-pit, and such steam
is forced by the suction of the blast up through the grate into the furnace, being
decomposed in its passage into its elements, aud forining with the cacbon of the
fuel, certain combustible gases, the combustion of which produces a most intense
beat, the fire being one which is especially adapted for treating iron. Further-
more, the steam rising from the water in the ash-pit being carried up by the blast,
dampens the clinkers upon the grate, and softens them, so that when the grate is
rotated they become detached more readily.
With my improved furnace I have thus been able to utilize the dirtiest slack coal
without any difficulty whatever, and without stopping the furnace, the clinkers being
continuously disposed of without the necessity of cooling the furnace, the result being
that the tonnage produced has been greatly increased.
If desired, the waste heat inay be conducted from the furnace illustrated in Figure 2
to a boiler so that it may be utilized in making steam.
In Figures 7, 8, I have shown a modified arrangement of furnace, the furnace
The furnace is also
being there shown as arranged to generate steam in a boiler 36.
provided with a mechanical stoking device, consisting of a chute 37 through which
the coal is fed. The grate 21, instead of being driven by a gear 24, is provided
with a sprocket wheel 38 around which passes a link belt 39 driven by a sprocket
wheel 40 mounted upon a shaft 41. The shaft 41 may be rotated by any convenient
power. The grate 21 rotates in the direction indicated by the arrow in Figure 8,
carrying the fuel over towards the bridge wall. By this arrangement the grate is
continuously moved at a slow rate of speed, it being desirable to regulate the speed
so that by the time the coal is carried from the front of the furnace to the bridge
wall it will have been burned to a clinker or ash, and will be ready to be dropped
into the water by the action of the grate.
The chute 37 is formed by two doors 42-43, hinged to the front of the furnace
and so arranged that when closed they will form a hopper or chute for the passage
of the coal. By this arrangement of the fuel supply and grate the smoke is almost
entirely consumed.
Instead of using an air blast under the boiler in this construction, I prefer to
introduce steam into the furnace, the steam being introduced in substantially the
same way as the air blast above described in connection with Figure 2. I prefer
to use steam in this connection because it carries with it sufficient air to give all the
draft necessary, and it is more economical than air for the purpose of making steam
or heating the water in the boiler, as the air blast would make the heat too intense and
would burn out the boiler.
In Figures 9 and 16, my modified grate is shown as being used in connection with
a gas producer, 44 being the front wall of the producer, 45 the rear wall, 46 the
ash-pit, 47 the front wall of the ash-pit, and 48 the doors of the producer. The
operation of the grate is substantially the same in this connection as in the arrangement
above described.

page_text: In Figure 11 I have shown a modified arrangement of my improved grate
designed more particularly for use in boiler furnaces; 49-50 indicating two rotary
grates, the outer surfaces of which are formed in sections, as above described, said
sections having toothed surfaces, the direction of the teeth being toward the rear.
The grates 49-50 rotate in the direction indicated by the arrow in Figure 11, the
fuel being deposited upon the grate 49 from a chute 51, and being deposited by the
grate 49 upon the grate 5", which carries it over to the bridge wall 52. 53 indicates.
the boiler. The advantage of this construction is that the coal is caused to travel
a greater distance, thereby insuring its consumption before it reaches the bridge
wall.
Instead of arranging the air or steam blast pipe as shown in Figure 2, it may be
made to extend through the furnace, forming a shaft for the grate, as shown in Figure 12,
54 indicating the air or steam pipe, 55 the grate mounted thereupon by means of
sleeves 56-57, having a sprocket wheel 58 or other suitable device whereby it may be
driven. The pipe 54 is perforated, preferably at its upper portion only, to permit
air or steam to discharge into the grate. 59-60 indicate the side walls of the
furnace.
Figure 13 illustrates a still further modification of the furnace, consisting of an
endless belt 61 of suitable material, said belt being in the nature of a conveyor
belt, and being mounted upon wheels or pulleys 62-63 arranged at the opposite
ends of the fire box upon shafts 64-65 respectively. 66 indicates the air or steam
blast pipe. The operation of the grate 61 is substantially the same as that of the
grates shown in Figures 2 and 11.
I am aware that to provide a furnace with an ash-pit adapted to contain water
and having an opening to permit of the withdrawal of the ashes and clinkers from
such ash-pit is not new, and also that a water-sealed ash-pit in itself is not new; but
so far as I am aware no one heretofore produced a furnace having a rotary grate, a
water-sealed ash-pit thereunder, arranged so that the steam rising from the water in
the ash-pit under the influence of the blast may permeate and loosen the clinkers so
that they may readily drop off when the grate is rotated, as above described; neither
has any one heretofore produced a furnace having a grate, a water-sealed ash-pit
arranged thereunder, and means for conducting a blast into the ash-pit under the
active surface of said grate and in communication with the water in the ash-pit;
so that the steam generated from such water will be forced through the bed of fuel
and be decomposed producing a most intense heat, as above described.
Having now particularly described and ascertained 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. In a furnace, the combination with a water-sealed ash-pit, of a rotary grate,
and means for introducing a blast into the furnace below the active surface of the
grate, said blast having communication with the water in the ash-pit, whereby
the steam generated from such water will be carried through the bed of fuel with the
blast, substantially as described.
2. In a furnace, the combination with a water-sealed ash-pit, of a cylindrical
rotary grate partly submerged in the water in the ash-pit, said grate being provided
with perforations, and means for introducing a blast of air into said grate and in
communication with the water in the ash-pit, whereby the steam generated by the
heated grate will be carried with the blast through said grate," substantially as
described.
3. In a furnace, the combination with a rotary grate, of a water-sealed ash-pit
arranged thereun ler, said ash-pit having an external opening whereby the asbes
may be removed without interrupting the operation of the furnace, and means for
introducing a blast into the spaer between the upper surface of the grate and the
water in the fire-box, such blast having access to such water, whereby the steam
generated by the heated grate will be carried with the blast through said grate,
substantially as described.

page_text: 4. In a furnace, the combination with a bridge wall and a front wall forming a
fire-box, of a rotary cylindrical grate in said fire-box, said grate having perforations
in its surface, a water-sealed ash-pit under said grate, said ash-pit having an external
opening, and means for introducing a blast into said grate, said blast having access to
the water in the ash-pit, substantially as described.
5. In a furnace, the combination with a water-sealed ash-pit, of a grate, and
means for introducing a blast into the furnace below said grate, said blast having
communication with the water in the ash-pit, whereby the steam generated from such
water will be carried through the bed of fuel with the blast, substantially as
described.
1
ALFRED METCALF HEWLETT.
Haseltine, Lake & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.