Improvements in the Method of and Apparatus for Producing Gas.
Year: 1893

page_text: Date of Application, 17th Oct., 1893-Accepted, 16th Dec., 1893
COMPLETE SPECIFICATION.
Improvements in the Method of and Apparatus for Producing Gas.
I, ARTHUR KITSON, Engineer, of W. Upsal Street, Germantown, Philadelphia
County, Pennsylvania, U.S.A. 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:-
This invention relates to improvements in method of and apparatus for producing
gas.
Heretofore the chief difficulty in the way of carrying out the process of manu-
facturing gas without interruption and without variation in the quality of gas
produced has been the impracticability of maintaining the body of fuel in the
uniform condition which is essential. As the fuel is consumed not only is there a
constant tendency to form clinkers which interfere with the proper and economical
production of gas and soon compel radical cleaning of the fire but a coating of ash
is formed upon the exposed surface of the fuel and prevents proper contact of the
vapors which are passed through the mass of incandescent fuel.
The present invention overcomes this difficulty. The mass of fuel is kept in a
uniform state of compactness, incipient formation of clinker is prevented, and the
surface of the fuel is kept clean, by maintaining a moderate yet general and con-
tinuous agitation of the whole mass of fuel, at the same time removing the ash as
fast as it is formed. A uniform stream of vapor is simultaneously and continuously
projected into the uniformly compacted mass of incandescent fuel.
The jet of steam employed may be generated by the same fuel and the latter fed
regularly and automatically into the furnace.
Fig. 1 is a sectional elevation of the apparatus taken on line X X of Fig. 3.
Fig. 2 is a similar view taken on line Y Y Fig. 2.
Fig. 3 is a plan view of the furnace plate, grate bars and ash pit with the hearth
removed.
The fuel chamber A. of the furnace is enclosed by firebrick walls A' with an iron
jacket as usual, resting upon a furnace plate B which is in turn supported by means
of suitable legs from a base plate C. To the under side of the furnace plate are
secured vertical grate bars D arranged in a circle within which the hearth E of the
furnace is adapted to move freely. The iron ash pit F is freely supported from
the furnace plate and is formed with an inclined bottom F¹ the lowest portion of
which extends nearly to the base plate C near which a cleaning door f is
provided.
The grate or hearth E consists of a circular plate of iron having a circular
flange E¹ of gradually increasing height, which encloses and supports the firebrick
portion of the hearth. The upper surface E" upon which the fuel rests, thus forms
an oblique plane considerably inclined from the horizontal. The hearth is
supported upon a central hollow shaft G communicating with the central opening e
in the hearth through a grating or bars e¹ by means of which a chamber is
formed for the reception of suitable materials, such as asbestos wool and ashes
or pieces of fire brick through which the blast is admitted to the fuel as will
be described later. The hollow shaft G which is preferably formed in two
parts as shown, passes through an opening in the inclined bottom F¹ of the ash
pit, a stuffing box being provided to maintain a tight ash pit while permitting
free movement of the shaft. The lower end of the shaft is provided with a
screw thread g which engages the internally screw-threaded hub or nut H
fastened to the bed plate below and outside of the ash pit, and a gear wheel I,
which is feathered on the shaft, serves to convey rotating power to the latter

page_text: through any suitable hand or power mechanism. The rotation of the shaft in
one direction turns the hearth and at the same time raises it by means of the
screw threaded end and hub, the gear wheel 1 being held upon the hub by
means of a collar; while rotating in the opposite direction in like manner lowers
the hearth. A sleeve f" fastened to the inclined bottom of the ash pit extends
upward within it enclosing the shaft and a corresponding sleeve g' of somewhat
larger diameter, secured to the under side of the hearth, is moved up and down
with the latter, overlapping the fixed sleeve f" in telescope fashion; and serving
to protect the shaft and stuffing boxes from the ashes dropping into the pit from
the fuel chamber; thus ensuring the perfectly satisfactory operation of the movable
hearth.
The water circulating coils J' extending around the fuel chamber are connected
as heretofore to the boiler or reservoir J, as is also the superheating coil K. I
provide in addition an oil vaporizing coil L, one end of which is connected with
an oil supply pipe L' and also with an intercepting steam pipe supplied from the
superheating coil K; by means of this steam jet the oil is driven through the
coil L, in which it is simultaneously subjected to the furnace heat, and through
suitably located openings " or " at the other end of the coil into the fuel chamber.
These openings are arranged at different points circumferentially and at different
heights above the grate and are provided with regulating valves as indicated for
regulating or entirely closing them so as to permit the vaporized oil and steam to
be admitted at proper points into the incandescent fuel as will be described later.
To provide for thoroughly heating the air blast which is conveyed to the furnace
through the hollow central shaft G of the hearth and through the blast pipe H¹
connecting with the fixed hub H, I surround the gas take-off pipe M from the
furnace with a casing N thus forming an annular air passage having a supply
opening n at one end and terminating in a chamber M from which the air thus
heated by contact with the surface of the take-off pipe is drawn into the blast
pipe H and driven through the same in the usual manner into the furnace by
means of the injector O, which is also supplied with steam from the superheating
coil K; the lower end of the take off pipe M is seated in the water box M".
To provide for more conveniently removing clinker from the hearth one or more
sections d of the pendent grate bars are formed with lugs d' by means of which
they are hinged to the furnace plate adjacent to a side door F in the ash pit, so
as to permit of their being swung entirely out of the way during the cleaning
operation and readily returned to normal position thereafter, any suitable means
being provided to lock them.
My mechanism for conveniently feeding fuel to the furnace as it is required,
without allowing any escape of gas therefrom, consists of an ordinary hopper P
which is mounted upon a cylindrical valve casing Q arranged horizontally and
having opposite openings communicating respectively with the hopper and with the
goose neck passage way R to a central opening in the furnace. This casing is
provided with end heads q and q' through one of which the stem s¹ of a hollow
valve S fitted to the casing, projects, whereby through suitable mechanism, the
valve is rotated during the operation of the furnace. The valve itself is a hollow
cylinder having a single openings which registers alternately during rotation, with
the hopper and furnace openings, of the casing, the valve chamber being filled with
fuel from the hopper when in communication therewith and the contents discharged
into the furnace as the opening s reaches its lowest position in the casing, while
escape of gas is at all times prevented.
In practice I have found that the proper action of the rotary valve is apt to be
interfered with by the passage of the openings across the hopper opening, during
which passage the column of fuel from the hopper is cut off from the portion in the
valve; the crowding of the fuel during this movement ordinarily forces it between
the valve and casing thus cutting grooves which allow the escape of gas.
This
difficulty I have overcome by constructing the valve with an overhanging flange s
which enables the column of coal above the valve to be easily cut off, the fuel being

page_text: crowded into the unfilled space below said flange instead of between the valve and
casing as described.
Both the valve controlling the supply of fuel to the furnace, and the hearth
mechanism are preferably operated continuously; the alternate up and down
movement of the hearth being effected by means of two sets of pulleys arranged to
be run in opposite directions, with an automatic belt shifting mechanism, such as is
commonly used in similar cases. During the operation of the furnace the fuel is
kept constantly agitated not only by the up and down movement of the hearth but
by the positive turning or rotation of practically the whole mass of fuel with the
rotating hearth. This positive rotation of the fuel which I have found to be
essential to the satisfactory breaking up of any bridges or arches forming above
the hearth, is effected by the peculiar form of the latter which is considerably
higher at one side than at the other so that it is impossible for it to rotate
independently of the body of fuel supported on it as is the case with rotating grates
heretofore used. The top portion of the fuel may not be rotated as rapidly as the
lower portion which is directly supported upon and positively rotated by the hearth
but it is so effectually agitated throughout that neither holes nor clinkers can be
formed nor caking of coal (when soft coal is used) occur to any appreciable extent.
The blast of heated air and steam enters the furnace through the hearth passing
through the asbestos wool or equivalent material in the chamber e, the presence of.
which prevents any clogging of the passage as effectually as the form of the
rotating grate prevents any unequal resistance to the passage of the blast through
the mass of fuel, thus insuring thorough distribution and decomposition of the
steam. The vaporized oil is blown into the incandescent fuel sufficiently below the
surface to insure a proper decomposition of the same in passing upward through it
but not sufficient to cause the breaking up of the heavy hydrocarbons into lighter
gases with the result of impairing its illuminating qualities, one or other of the
different series of inlets being used depending upon the heat of the fuel in the
chamber. The ashes which are sifted through the pendent grate bars into the ash
pit practically as fast as formed, can have no effect whatever on the hearth operating
gear which is effectually protected, and they are removed with the greatest ease
owing to the inclined form of the pit.
In my complete operation of manufacturing gas a constant stream of blended air
and steam is projected into and passes upward through the entire mass of
incandescent fuel while at the same time continuous streams of blended steam and
oil are projected into at a properly adjusted distance below the surface to insure
sufficient but not too prolonged action of the heat upon the vaporized oil; these a
streams of steam and air and steam and oil are maintained by the constant
generation of steam and the constant vaporization of oil by means of the same
combustion which serves to generate the gas. The fuel which is fed in regularly
and automatically instead of being intermittently or periodically agitated or stirred,
as is ordinarily done with the result of producing gas of varying quality, is .
continuously, automatically and uniformly agitated so as to maintain the fuel in a
uniformly loose yet compact mass which insures uniform action upon the oil and the
consequent production of a uniform quality and maximum quantity of gas, at the
same time avoiding all necessity for interfering with the continuous operation of
the furnace.
If desired a down draft may be employed instead of an up draft in the manner
indicated in dotted lines in Figure 2; the blended steam and air in this case being
blown in at the top of the furnace and the gas taken off through the hollow shaft
of the grate and the bottom take off pipe.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same may be performed I declare that what I
claim is:
1. In a gas generating furnace the combination with the fuel chamber, of the
movable circular grate or hearth having its plane upper surface upon which

page_text: the body of fuel rests a plane surface inclined from the horizontal, and mechanism
for imparting a rotary motion to said hearth, substantially as set forth.
2. In a gas generator the combination with the fuel chamber and the ash pit
below the same, of the movable grate or hearth having a central opening and a
hollow shaft extending downward through the bottom of the ash-pit, the fixed hub
or nut below said ash pit internally screw threaded to receive the threaded end of
the hollow shaft, the blast pipe connected to said fixed hub, and a rotating
mechanism for operating said shaft, substantially as set forth.
3. In a gas generator the combination with fuel chamber, of a circular grate or
hearth having a central opening, a hollow supporting shaft extending downward
therefrom, a pipe connected with the hollow shaft, the said central opening in the
grate being arranged to form an open chamber and having loosely packed therein
porous or broken refractory material through which the blast passes, substantially
as and for the purpose set forth.
4. In a gas generator the combination with the fuel chamber of a coil of pipe
surrounding the same and having one end connected with an oil supply pipe and
with a steam jet for projecting the oil through said coil, and the opposite end
provided with two or more series of inlets into the fuel chamber arranged at
different heights from the hearth and provided with independent regulating valves,
substantially as set forth.
5. In a gas generator the combination with the fuel chamber and the grate, of
the steam generating and oil vaporizing coils surrounding said fuel chamber, a
blast conduit entering said chamber through the grate and suitable connections
between said steam coil and vaporizing coil, between the steam coil and the blast
conduit and between the vaporizing coil and the generator whereby blended steam-
and-oil and steain-and-air are separately and simultaneously projected into the fuel
chamber, substantially as set forth.
6. The combination with the generating chamber and the vertically movable
rotary hearth, of the vertical grate bars enclosing the movable hearth and mainly
fixed to the furnace plate but having one or more sections hinged to said plate and
arranged to swing outward from the hearth to allow free access thereto for
cleaning, substantially as set forth.
7. The improvement in the art of manufacturing gas which consists in
automatically maintaining the body of incandescent fuel in a state of uniform and
continuous agitation, thereby preventing incipient clinker and caking formations
and simultaneously projecting into it a continuous stream of vapor, substantially as
Bet forth.
8. The improvement in the art of manufacturing gas which consists in
automatically maintaining the body of incandescent fuel in a state of uniform and
continuous agitation and simultaneously projecting into it separate and continuous
streams of blended steam-and-air and steam-and-oil respectively, substantially as
set forth.
9. In a gas generator the combination with the fuel chamber of a feed mechanism
therefor consisting of a hopper and a hollow rotary valve formed with an opening s
with overhanging ledge s' said opening communicating alternately with the hopper
and with the fuel chamber, substantially as set forth.
1002
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.