US2210720A - Apparatus for igniting solid fuel - Google Patents

Description

Aug. 6, 1940. A. J. JOHNSON ET AL APPARATUS FQR IGNITING SOLID-FUEL Filed Jan. s, 1958 Patented Aug. 6, 1940 UNITED STATES PATENT OFFICE K. Staley, Morton, Industries, Inc., tion of Delaware Pa., assignors to Anthracite New York, N. Y., a corpora- Application January 3, 1938, Serial No. 182,960

6 Claims.

The present invention relates to ignition devices and more particularly to a means for starting a fire in a body of solid fuel.

While it has heretofore been proposed to employ electrical ignition means for small units, such for example, as incense burners and the like, there has been insofar as applicant is aware no successful type of electrical or other ignition means for use with boilers or heaters operated by a bed of solid fuel, such as coal, coke, charcoal or like fuel products. In starting such fuel beds it is still customary and necessary to lay a bed of readily inflammable material, light it with a match, and thereafter gradually supply coal or the other main combustible material until the fire is started. Such starting operations are tedious and troublesome enough with hand fired boilers and heaters but where the main combustible is automatically fed, as in stoker operation, the time and trouble are multiplied. This is because great care must be used not to smother the lighted material by manually throwing in too much fuel. Hence the initial ignition has tobe watched continuously not only to prevent smothering but to see that the automatically propelled fuel reaches the ignited bed at the proper time in the cycle.

Some of the objects of the present invention are to provide an electrical device by which a bed of solid fuel can be ignited initially so that thereafter combustion can be continued under normal operating conditions, be it natural or forced draft; to provide an apparatus for automatically firing a mass of solid fuel; to provide an apparatus for automatically firing a mass of solid fuel which travels from a source of supply to a re pot; to providea novel method of igniting a fuel bed which is automatically fed from a source of supply; and to provide other improvements as will hereinafter appear.

In the accompanying drawing Fig. 1 represents a sectional elevation of the fire pot and associated air and fuel feeds of a stoker equipped with one form of the present invention; Fig. 2 represents a section on line 2 2 of Fig. 1; Fig. 3 representsl a section similar to Fig. l but employing a modified form of the invention; and Fig. 4 represents a section on line 4-4 of Fig. 3.

' Referring to the drawing the present invention is shown by way of example as applied to the igniting ofthe bed of fuel of a mechanical stoker. Thus, as shown in Figs. 1 and 3, a fire pot I0 provided with tuyres is arranged to receive a body of coal or other suitable combustible which is fed thereto by a power driven worm I2 located ignite.

(Cl. -1) i in the fuel feed pipe I3. The inlet end of the feed pipe I3 terminates in a source of supply as will be understood. The discharge end of the pipe I3 is located in coaxial relation to the lower end of the fire pot I0, and the latter flares upwardly and outwardly therefrom in the shape which has now become more or less conventional. The tuyres I I provide passages for air which is supplied under pressure by a pipe I4 to a chamber I5 formed by an annular housing I 6 encircling the aforesaid re'pot I0. As shown the upper marginal portion of the fire pot seats on the housing I6 as a support and also as a seal to prevent improper discharge of air.

In the form of the invention shown ln Fig. 1 the discharge end of the feed pipe I3 terminates in spaced relation to the inlet end of the fire pot I0, the annular space so formed being closed by a heating coil I'I of the type which can be brought to a state of incandescence by an electric current. Thus conductors I8 and 20, lead from a source of current through the housing to the coil I1, and control may be had by a suitably located switch 2 I. While the preferred construction is to position the heating coil Il as shown between the fire pot III and the feed pipev I3, this is not necessarily its essential location, the desideratum being that its heating effect take place before the forced draft air contacts the fuel.

In the form of the invention shown in Fig. 3, the fire pot I0 forms a direct continuation of the feed pipe I3 and the joint between the two is en circled by a coil 22 of greater capacity than the coil II in that -its function is to heat the wall about the fuel and thus transmit heat to the fuel. Current is supplied to the coil 22 by conductors 23 and 24 under control of a conveniently'positioned switch 25.

In both forms of the invention it should be noted that the heating coil is relatively close to the zone of heat radiated from the retort but is also exposed to the stream of air flowing in the air conduit. This construction insures the heating coil being maintained relatively cool when not in use and thereby lengthens its life.

In the operation of the device as shown in Fig. 1, the mechanical Stoker is started and feeds a column of fuel to the point where its end is in the zone of heat from the coil I1. At this time the stoker feed and the forced draft are stopped and the fuel thus remains in the hot zone until it reaches such a temperature that by exposing itrto a stream of fresh air Will cause it to actually A temperature of approximately 1000 F. has been found to give satisfactory results for the purpose intended. When such' a temperature has been reached the stoker feed and forced draft are again started, whereupon the heated fuel 'moves into the path of the stream or streams of air where it reaches a state of incandescence.

The operation of the modified form of the invention shown in Fig. 3 is substantially the same with the exception that the fuel is in contact wth the heated wall of the conduit instead of direcly against the coil. l

From the foregoing it will be seen that the apparatus carries out a new and novel method of igniting coal or other combustible material. The

method consists in subjecting a portion of a stationary mass of combustible material to heat until it reaches a predetermined temperature such for example as l000 F., then circulating air through the heated portion of the mass to bring the material to a state of incandescence namely actual combustion. In the apparatus as shown the method includes the step of bodily shifting v the heated material from a zone of heat to an as heater.

area in the path of a stream of air. With the 1 incandescence of the heated portion all contigu- 1. An apparatus for igniting solid fuel consist-` ing of a repot having openings for air therethrough, means for causing a stream of air to pass through lsaid openings, a fuel inlet below and discharging into said i-lre pot arranged to confine a body of fuel out of contact with said stream of air, an electric heater located to heat fuel in said inlet, and underfeed means to feed the heated fuel into said stream of air in said fire pot, whereby combustion is started in the heated fuel.

2. An apparatus for igniting solid fuel consisting of a fire pot having openings for air therey, through and a fuel inlet below said openings, a

fuel feed pipe communicating with said inlet, an

electric heater coil encircling a portion of the fuel in said pipe adjacent said inlet, means for causing a stream of' air to pass through said openings, and means to feed heated fuel from said pipe into said stream of air in said re pot, whereby combustion is started in the heated fuel.

3. An apparat-us for igniting solid fuel. consisting of a retort having an opening in the bottom thereof, an electric heater of substantially tubular form arranged below and in relatively close.proximity to said opening to form a zone of heat when energized, conveyor means for feedlng fuel through said heater and zone of heat into said opening, and into said retort, and means exposing the heated fuel to a stream of air after it passes said opening.

4. An apparatus for igniting solid fuel consisting of a retort provided with tuyres and having a fuel inletl in the bottom thereof, an electric heater' of substantially tubular form arranged in relatively close proximity to said inlet and forming a zone of heat, conveyor means for feeding fuel through-said heater and zone of heat to said inlet, and a conduit exterior of said retort for directing a stream of air into contact with said heater to cool said heater when deenergized and through said tuyres to ignite and support combustion of the previously heated fuel.

5. An apparatus for igniting solid fuel consisting of a retort provided with tuyres and havlng a fuel inlet, means forminga fuel conduit and an open air conduit, said fuel conduit leading to said inlet and said air conduit encircling said fuel conduit and leading to said tuyres, and an electric heater associated with said fuel conduit to heat fuel therein and exposed to the stream of air in said air conduit to be cooled thereby after said heater is deenergized.

6. An apparatus for igniting solid fuel consisting of a retort provided with tuyres and having a fuel inlet, means forming a fuel conduit and an air conduit encircling said fuel conduit, said fuel conduit leading to said inlet and said air conduit leading to said tuyres, and an electric heater located to heat fuel in said fuel conduit and exposed to the stream of air in said air conduit,y

whereby said heater is continuously cooled after ignition has been accomplished.

ALLEN J. JOHNSON.

K. STALEY.

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