US2423410A

US2423410A - Ignition apparatus fob liquid

Info

Publication number: US2423410A
Authority: US
Publication date: 1947-07-01
Anticipated expiration: 1964-07-01

Description

July 1,1947.

E. G. SIMMONS IGNITION APPARATUS FOR LIQUID FUEL FIRED FURNACES Filed May 19', 1944 2 Sheets-Sheet l F/GZ In ventor 56. (Simmons A Horneys July 1, 1947.

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2%. e a m m P mm m mmm. SLR TR 6mm n u m N Atlomew Patented July 1, 1947 UNITED. sm'n-z PATENT. OFFICE IGNITION APPARATUS FOR LIQUID FUEL FIRED FURNACES Edward George Simmons, Chiswick, London, England Application May 19, 1944, Serial No. 536,355 In Great Britain May 26, 1943 4 Claims.

This invention relates to ignition apparatus for liquid fuel-fired furnaces in which the liquid fuel is sprayed into the furnace combustion space from a fuel spraying or jet device.

A convenient method of igniting the oil used in such a furnace is to use an electrical'sparking plug,-but this leads to difliculty if the sparking plug is placed in the direct line of travel of the liquid fuel spray because it is very liable to become wetted by the liquid and, therefore, it will not give a, spark. On the other hand, if the sparking plug is mounted in a position clear of tube, so as to divide the latter into a channel for ingoing liquid-laden air and a channel for outgoing flame and products of combustion,

the liquid spray path, ignition of the oil becomes very uncertain if not impossible.

The object of the present invention, therefore,

is to provide means whereby the said difliculty the member is outside the zone or path of the liquid fuel spray while the inner and open end of said member, which is formed to act in the manner of a scoop, projects into or adjacent to the said zone or path, the arrangement being I such that while the spray or liquid-laden air is picked up by, or at, the open end of said member,

the spray or liquid content is quickly deposited on the walls leaving only an inflammable vapour in the air. Thus, since no liquid is conveyed to the points of the sparking plug, the latter is not rendered ineffective but sufficient vapor-laden air is conveyed to the points of the sparking plug to provide an inflammable mixture which allows ignition to take place.

The said hollow member may consist of a short tube, one end of which is arranged to act like a scoop in the liquid fuel spray path or zone while the opposite end, which is kept outside the spray path or zone, is closed by the sparking plug.

The open end of thescoop tube, which projects into the liquid fuel spray P th or zone, i arranged in such a manner as to catch a small amount of the liquid fuel spray together with some of the entrained air. The closed opposite end of the tube, carrying the sparking plug is arranged out of the liquid fuel spray path or zone.

The scoop tube may be straight or curved and curved end.

may be cut either square (i. e., so that it is subconstructional forms of the invention applied to oil-fired furnaces are shown, by. way of example, on the accompanying sheets of drawings, whereon:

' Fig. l is a fragmentary sectional view of the combustion space of an oil-fired furnace provided with ignition apparatus comprising a short curved scoop tube which is arranged wholly within the container space and is supported by a pivoted bracket.

Fig. 2 shows a modification in which the scoop tube is straight and is arranged partly within and partly outside the combustion space;

Fig. 3 is a view, partly in section, of the short, straight scooptube of a modified-ignition apparatus, which is fitted with a division plate, the open end of the tube being shaped to act as a scoop for the spray or liquid-laden air;

Fig. 4 is a view corresponding to Fig. 3, but shows a modification in which the division plate acts as a scoop for the spray or liquid-laden air;

Fig. 5 is a fragmentary sectional view of a scoop tube which is similar to, and is arranged like, the tube shown in Fig. 3, but which has an inwardly-curved end; and

Fig. 6 is a fragmentary sectional view of a scoop tube which is similar to, and is arranged like, the tube shown in Fig. 4, but which has an inwardly- Referring to Fig. 1;

The furnace comprises a circular combustion chamber l into which a fuel spraying device or jet 2 injects liquid fuel in a conical shaped spray 3. In the upper part of the spray, whollyy'within the combustion chamber, a curved scoop} tube 4 is arranged with its open end just in the edge of the spray path and facing'the direction of the spray. Theinner, open end of the scoop tube stantially' parallel to the axis of the spray) or, as shown at 5, Fig. 1, at an angle tothe axis of the spray but, in any case, such that it will act in the manner of a scoop. The other end ofthe In either case, the liquid fuel caught in the open end 5 or 1 of the tube I eventually drops out again in the form of large drops rather than fine;

particles. These drops, however, merely drop back into the flame and are consumed without causing any serious amount of smoke.

The scoop tube 4 and sparking plug .assembly,--

terminates short of the said spray. The division plate acts to divide the tube into an inlet chan- 6 may be mounted on a bracket 8- pivotally ar-.

ranged at 9 in the combustion chamber I so that once ignition of the main furnace has been obtained, the tube may be swung out of the actual path of the liquid spray. The removal of the tube out of the spray path may'either be performed by hand or thermostatically. In. the latter case, the bracket 8 may be made of thermostatic b i-metal strip and .may be fixed at its end remote from the scoop tube instead of being hinged. Thus, as soon as ignition of the fuel takes place and combustion commences, the heat radiated back on to the bi-metal stri causes it to flex and withdraw the open endof the tube from the actual spray path.

In a further modification, in order to promote a, more positive circulation of vapour-laden air to the sparking plug points, a division plate is fitted into the tube in such a manner as to form two longitudinal passages, one for ingoing spray or liquid-laden air and one for out-going flame and products of combustion. The arrangement at the open end may either be as described above, in which the tube forms a scoop, or the dividing plate itself may be shaped to do so.

The length of the division plate will depend on circumstances, but in no case should it extend right up to the sparking plug as it is necessary to leave a cross passage so that the flame and products of combustion air can find their way out through the outgoing passage.

Thus, as shown in Fig. 3, the scoop tube 43 is straight and is fitted with a division plate 9 which extends centrally of the tube and terminates short of the points of the sparking plug 6A. The outer end of the division plate projects out of the sloping inner end HI of the tube 43, the projecting end of the plate being curved towards the fuel spraying device or jet (not shown) but arranged outside the fuel spray path or zone.

or liquid-laden air. The division plate 9 thus forms within the tube an inlet channel l2 for the vapour ladenair, which latter flows inwards of the tube to the back of the division plate and, then through the space between the inner end of the. plate and the sparking plug points. The flame and products of combustio pass outwards through the outlet channel 13 on the opposite side of the plate. In this case, the division plate itself does'not act as a scoop. I w

The construction shown in Fig. 4 is similar to that shown in Fig. 3 but it difiers therefrom in that the inner end IA of the scoop tube 4C is square to the axis of the tubeand penetrates only slightly, if at all, into the fuel spray 33 while the curved outer end of the division plate 9A projects into the fuelspray and thus acts as a scoop.

In this construction, the plate divides the tube into an inlet channel IZA for the spray or liquidladen air and an outlet channel ISA for the flame and products of combustion. I

In the constructions shown in Figs. 5 and 6, the inner ends of the scoop tubes are curved towards the fuel spraying or Jet device. In Fig. 5, the part, HA of the angled end IIIB of the tube projects into the path 30 of the fuel spray and thus acts as ascoop, while the curved end of the division plate 93, which projects out of the tube,

ne1.I2 B for the spray or liquid-laden air and an outlet channel MB for the flame and produ'cts'of combustion but it does not act as a scoop.

In the construction shown in Fig. 6 the inner end of the scoop tube 4D is also curved and the curved end of the division plate 90, which divides Part of the length of the tube into inlet and outlet channels 120 and I30 for the spray or liquidladen air and theflame and products of combustion respectively projects out of the scoop tube into the path 31) of the spray. The plate thus acts as 'a scoop for the spray or liquid-laden air.

1. Apparatus for use in igniting electrically the sprayed liquid fuel of liquid'fuel-fired furnaces, which comprises in combination, a tubular memb'en'means mounting said tubular'member in the furnace whereby the inner end at least of the tubular member will be within the combustion space of the furnace, a sparking plug supported in. the outermost end of said tubular member and acting as a closure for said end, the tubular member being of such a length that the points of the sparking plug are enclosed within the tubular member and thus shielded from the liquid fuel spray, the inner end of said tubular member being open and intersecting the fuel spray, and a division plate being disposed length-g wise and within said tubular member and disposed inspaced relation from said sparking plug, whereby while the spray or liquid laden air is picked up at the inner open end of said member, the spray or liquid content is quickly deposited on the walls of said member leaving only an inflammable vapor in the air and, since no liquid is conveyed to the points of the said sparking plug, the latter is not rendered ineifective, but sufficient vapor-laden air is conveyed to the points of the sparking plug to provide an inflammable mixture which allows ignition to take place.

2. The apparatus claimed in claim 1, wherein the inner end part of said tubular member is curved inwards towards the axis of the fuel spray.

3. The apparatus claimed in claim 1, wherein the said tubular member is secured to and supported by a bracket which is fixed at its end remote from said member and consists of a thernition of the fuel has taken place, the heat radiated back on to the'strip causes it to flex and withdraw the open end of the said tubular memher away from the fuel spray path.

4. The apparatus claimed in claim 1, wherein sajid'division plate is fitted in said tubular member in such a position that two longitudinal channels are therebyformed in the tube, one for ingoing sprayv or liquid-laden air andthe other for outgoing flame and products of combustion, md a cross passage adjacent to the sparking plug :onnecting these two channels, the division plate oeing extended from the inner end of said tube and shaped to act as a scoop.

EDWARD GEORGE SIMMONS.

I REFERENCES CITED The following references are of record in the file of this patent:

Number Huntington et a1. Jan. 17, 1928