US2032332A - Liquid fuel burner - Google Patents

Description

Feb. 25, 1936.- R. M. SHERMAN LIQUID FUEL BURNER Filed Nov. 24, 1928 Patented Feb. 25, 1936 UNH'E'EE SKATES LIQUID FUEL BURNER Itallston M. Sherman,

signer to tion, neoticut Glastonbury, Conn, as-

The Silent Glow Oil Burner Corpora- Hartford, Conn, a corporation of Con- Application November 24, 1928, Serial No. 321,624

33 Claims.

My invention relates to that class of burners more particularly employed in connection with oil stoves, and an object of my invention, among others, is to provide a burner that shall be simple in construction, that may be readily cleaned, and that shall be particularly efiicient.

One form of burner embodying my invention and in the construction and use of which the objeots herein set out, as well as others, may be attained, is illustrated in the accompanying drawing, in which- Figure 1 is a view in side elevation of my'improved burner, with parts broken awayto show construction.

Figure 2 is a top View of the base of my improved burner.

Figure 3 is a top view of the device with the burner ring in place.

Figure 4 is a detail View in section through a portion of the burner on a plane denoted by the dotted line 45 of Figure 3.

Figure 5 is a similar view on a plane denoted by the dotted line 55 of Figure 3.

Figure 6 is a detail top view of a fragment of a burner base showing a modified form of construction.

Figure 7 is a similar View, but showing a burner ring and duct cover adapted to this form of construction.

Figure 8 is a view in section on a plane denoted by the dotted line 82 of Figure 7.

Figure 9 is a View in section on a plane denoted by the dotted line 9-5 of Figure 7 and showing the manner of supporting the burner shells.

Figure 10 is a view similar to Figure 9, but on a plane denoted by the dotted line lfilli of Figure '7.

In the accompanying drawing the numeral H denotes the base or bottom plate of my improved burner that may be supported in any suitable manner as by means of a rod l2. On its under surface the bottom plate has a boss 13 for the attachment of a fuel supply pipe M. As herein shown one-half of the structure only is apparent, the structure shown being duplicated on the opposite side of the rod 82. The plate H is provided with a series of upright, spaced, concentric flanges which form in the upper surface of the plate a relatively broad, inner, annular channel or fuel compartment I5 surrounded by an outer, relatively narrow channel or fuel groove It, there being provided open ducts ll connecting said compartment and groove. A central air supplyopening I8 is formed through the bottom of the base with the inner flange surrounding said opening, said flange forming one side. of the compartment IS. The outer flangeof the fuel groove !5 and the inner flange of the fuel groove it form in eifect a comparatively thick rib l9 separating the two grooves, the ribbeing cut through laterally at certain points to create the ducts ll. This rib is also out through vertically to provide a series of arc-shaped slots 20 for the supply of air to the burner, as shown in Fig. 2 of the drawing.

A burner ring or cover plate 2| is formed to fit over the base M. This ring has burner- slots 22 and 23 positioned to register respectively with the fuel grooves l5 and It in the base. This ring also has a series of arc-shaped vair slots, 24 to register with the slots 20 in the base and has also a central air opening to register with .the 'air supply opening l8 in the base.

In burners of this type prior to my construction concentric oil grooves have been connectedby a closed duct or ducts formed through the walls dividing said grooves. These ducts in time'become clogged with carbon or other material which has been diflicult to remove, owing to inaccessibility of the oil ducts. My invention provides a construction of such ducts whereby access to them from above may be readily gained and whereby they may be easily cleaned of any obstruction. In the structure shown these ducts! l are notches cut through the rib 19, the ring 2| bEiIIgrpIO-v vided with bridges 25 located between the slots 24, (Figure 3 of the drawing) these bridges cover ing and completing the formation of the ducts ll. Ties 26 are formed at intervals in the ring 2! to connect and support dilferent sections of said ring.

The inner portion of the ring or cover plate2l is provided with a flange 2'! which forms a cover for the inner part of the compartment I 5, as shown in Figs. 3, 4, and 5 of the drawing. The flange 21 partly covers the compartment l5 but has its outer peripheral edges spaced from the outer flange of the compartment so that the ,un: covered part of the compartment I5 is narrowed to correspond to and substantially align with-the overhead combustion chamber, hereinafter referred to.

The ring 2! 28 of a size to H, and this flange has'a positioning notch 29 to receive a positioning pin 38 projecting from the base I I, and as shown in Figure 1' of the drawing. This is for the purpose of causingthe bridges 25 to be positioned over the ducts l1 and alsoto is provided with a peripheral flange fit over the upper edge of the base cause the several slots and openings in the rings and base to register one with another.

Ribs 3| are concentrically located on the upper surface of the ring r cover 2|, these ribs being for the purpose of relatively positioning burner shells 32 that are preferably about evenly spaced.

' 'The shells 32 comprise outer and inner pairs of spaced, horizontally continuous, perforated, annular, tubular walls presenting between each pair a burner or combustion chamber 33 which registers respectively with the slots 22 and 23. A space 34 between the shells comprises an air chamber registering with the slots 24, and the hole I8 communicates with the space in the interior of the innermost shell also for supplying air to the burner. These air spaces are closed by covers 35-36. It will be understood that the shells 32 are perforated to such extent as may be desired, a portion only of the perforations being shown in Figure l of the drawing.

In the described form of burner, the base presents a system of vaporizing and vapor distributing passages which includes an effective vaporizing portion comprising the space or chamber at the inner part of the wide groove or channel l beneath the cover plate 2 I. This provides a relatively broad area over which liquid oil is adapted to flow and in which it is brought into close association with the overlying wall of the removable cover plate, the latter underlying a part of the inner air chamber and supporting and having direct contact with the inner combustion tube. When the burner is first started up, as by the common use of starting wicks positioned in the grooves beneath the combustion chambers, the burner shells heat rapidly and the cover plate takes up and acquires heat from the hot inner shell and the inner air chamber, becoming an active agent in transmitting heat to the oil beneath.

' Soon after the burner is started, the oil tends to become wholly vaporized as soon as it reaches the vaporizing chamber, and fuel in vaporized form is supplied to both the combustion chambers in the covered vapor distributing channels l5 and the ducts I1 and the outer channels I6. The inner covered part of the wider channel thus furnishes an efficient vaporizing chamber, materially reducing the time required for bringing the burner to full fire conditions, and also tends to reduce the accumulations of unconsumed carbon and confine such'accumulations as occur to the covered vaporizing chamber where they may be readily removed when the cover is withdrawn.

In that form of the structure shown in Figures 6 to the base II is of the same general form as that hereinbefore described. Instead of forming a cover for extending over the entire upper surface of the base, however, a cover 31 is pro vided extended partially across the compartment I5, the outer edge of this cover forming one edge of the burner slot 38, extending into the compartment I5. A peripheral flange 39 on this cover receives and holds the inner burner shell 32.

"Inthis form of construction intermediate shells 32 are held at their lower edges by flanges 40 on opposite sides of the slots through the ribs IS. The outer shell 32 is held at its lower edge by a peripheral flange 4| extending upwardly from the base H. I

In this form of the burner a duct cover 42 is made for each of the ducts I1, each cover having lips 43 which rest upon shoulders 44 located at opposite sides of the duct and formed by inter rupting or terminating the flanges 40 short of the duct. This is shown in Figs. 6, 7, and 8 of the drawing. Each cover is formed to removably flt between the concentric flanges 40 overlying and resting upon the side walls of the duct, the lips 43 extendingbetween the separated or interrupted portions of the flanges 40, as shown in Fig. I.

Features which characterize the construction shown in Figs. 6 to 10, inclusive, form the subjectmatter of my co-pending divisional application, Serial No. 516,306, filed February 17, 1931.

In accordance with the provisions of the patent statutes I have described the principles of operation of my invention together with the device which I now consider to represent the best embodiment thereof; but I desire to have it understood that the device shown is only illustrative and that the invention may be carried out by other means and applied to uses other than those above set out.

I claim- 1. A liquid fuel burner comprising a burner base having inner and outer fuel grooves therein, an open duct connecting said grooves, means for supplying fuel to said grooves, said base having air supply openings between said fuel grooves and also an air supply opening within said inner groove, a removable cover for said base having openings registering with said air openings and said fuel grooves and adapted to cover said duct, and pairs of spaced, perforated, continuous walls presenting between them a combustion chamber registering with each of said fuel grooves, said walls being supported by said removable cover.

2. A liquid fuel burner comprising a burner base having open fuel compartments therein, an open duct connecting said compartments, means for supplying fuel to one of said compartments, said base having air supply openings between said fuel compartments, a removable cover for said base having openings registering with said air openings and said fuel compartments and adapted to cover said duct, and means for forming combustion chambers communicating with said fuel compartments.

3. In a burner of the type described, a burner base having a central air conduit, an outer wall and a series of intervening concentric walls, the same presenting an outer fuel compartment and an inner fuel compartment connected by a duct, said base having air passages located between said inner and outer fuel compartments, concentric burner tubes forming combustion chambers and air supply chambers, and a cover plate for said I base providing openings through which communication. is had between said fuel compartments and combustion chambers and other openings through which communication is had between the air pas.- sages in said base and said air chambers, said cover plate providing a support for said several burner tubes on which the tubes are detachably mounted.

4. In a combustion tube burner, a base having laterally spaced inner and outer fuel channels, the inner channel being wider than the outer channel and the outer channel being in surrounding relation to the inner channel, means for supplying liquid fuel to the inner channel, a fuel supply upstanding, perforated walls providing combustion chambers, one communicating with the outer channel and the other with the inner channel and forming an intermediate air chamber between the combustion chambers and also forming an inner air chamber means for supplying air to said air chambers, and a wall overlying and partly coverduct between said inner and outer channels,

ing th'einner channel-' and between the latter and the inner air chamber, said'wall-providing a-relatively narrow opening for communication with the combustion chamber.

5. combustiontube burner having a-base provided' with laterally spaced inner and outer fuel chambers one of which is relatively broad to provide a; vaporizing space and the other of which is relatively narrow'andsurrounds the first chamber, inner and outer sets of perforated walls formingbetween them a plurality of combustion chambers in communication with and upstanding relation one above each of said fuel chambers, and forming also an intermediate air chamber between said combustion" chambers and an inner airchamber within the'inner combustion chamber means for supplying air to said air chambers, aremovable cover plate covering a part of the inner fuel chamberbut leaving a relatively narrow aperture at the outer side thereof opening into the overhead combustion chamber, said cover plate underlying one of saidair chambers between the'latter and the inner fuel chamber, means for supplying liquid fuel to the inner fuel chamber, anda fuel supply connection between the two fuel chambers. v

6. A combustion tube burner having a base provided with upstanding walls defining an outer annular fuelchamber and a laterally spaced inner annular fuel chamber, said base having an open duct connecting the two chambers, pairs of spaced" annular concentric combustion tubes forming combustion chambers in upstanding relation to and opening each into one of said fuel chambers and forming an air supply chamber intermediate the combustion chambers, said base having an opening intermediate the fuel chambers for a supply or" air to the intermediate air chamber, and a removable plate closing the open top of said duct and engaged along the circumference of an upstanding wall of said base and held against radial movement by such engagement.-

7. A-combustion tube burner having a base provided with two laterally spaced fuel chambers, an open duct connecting said chambers, pairs of spaced combustion tubes forming combustion chambers above and communicating with said fuel chambers, an air supply chamber between the combustion chambers, said base having an opening to the air chamber between the fuel chambers, and aremovable plate for the base provided with means to support and position the ad- Jaoent combustion tubes on opposite sides of the air chamber, said plate closing the open top of the duct and having an opening registering with the intermediate air opening in the base.

8. A combustiontube burner having combustion tubes and provided with a base having an inner fuel chamber, a separate and laterally spaced open outer fuel chamber surrounding said inner chamber, ducts connecting said inner and outer chambers, means for delivering liquid fuel to said inner chamber, and a removable cap for the base extending partially over said inner chamber and having means on its periphery to support and position a combustion tube.

9. A burner including a base having a plurality of concentric radially-spaced annular open-top fuel channels one of which is large and the other of which is small in radial width and surrounds the radially large channel, means to introduce liquid fuel into the bottom of the large channel only, a plurality of covered ducts connecting the channels, spaced combustion tubes surrounding the tops of the channels and extended upwardly thereabove to form a combustion chamber above each channel, and a plate which rests removably on said base and overlies the top of said large channel While leaving a passage communicating with the overhead combustion" chamber, said plate constituting a support for one of said tubes, said plate having an air passage therethrough which communicates with the interior of the tube thereon.

10. A liquid fuel burner including a base having a plurality of radially-spaced concentric open-top fuel channels therein, one of which is wide and the other of which is narrow and surrounds the radially large channel, said base having air passages between the channels and also within the innermost channel, concentric spaced combustion tubes surrounding the tops ofand extended above said channels to form combustion chambers in communication with said channels, means to admit liquid fuel into the bottom of the wide channel, a plurality of covered vapor passages connecting said channels at the bottoms thereof, and a plate which rests removably on top of said base and overlies the top of said large channel and constitutes a support for the innermost tube, said therethrough which registers with the air passage in said base that is within said innermost channel whereby to admit air to the interior of said innermost tube.

11. A combustion tube burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a burner base provided with an outer annular fuel chamber and an inner concentrically related fuel vaporizing chamber, a plurality of open ducts connecting said annular fuel chambers, said base having air supply openings between the fuel chambers and between the ducts, and a removable plate for the base covering said vaporizing chamber and exposed directly to the heat from the walls of the combustion tube surrounding said inner air chamber, said plate having provision for covering said ducts and having openings registering with the air openings in the base and said plate leaving uncovered delivery spaces for delivering fuel vapor from said vaporizing chamber to said combustion chambers.

12. A burner of the class described having a base provided with inner and outer annular fuel grooves connected by an open duct, pairs of spaced combustion tubes presenting between the tubes of each pair a combustion chamber aligned with and opening into one of the fuel grooves, said base having air passages between said inner and outer fuel grooves, and a removable plate comprising an annular structure resting on the base covering said open duct and having openings aligned with the air passages between said fuel grooves, structure having upstanding annular flanged walls serving as a support for the combustion tubes on opposite sides of said air passages.

13. A combustion tube burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, the burner base having relatively thin upstanding walls forming an annular fuel chamber and an inner,

plate having an opening laterally spaced, shallow fuel vaporizing chamber concentrically related to said fuel chamber, said base having formed therein a plurality of open ducts connecting the two chambers at spaced'intervals and having air supply openings intervening between the two chambers and between the adjoining walls of the ducts, and a removable plate extending over said vaporizing chamber resting on the walls of said base and exposed directly to the heat from the walls of the combustion tube surrounding said inner air chamber, said plate having radial extensions covering said ducts but spaced to leave uncovered the air openings between the ducts and said plate leaving uncovered delivery spaces for delivering fuel vapor from said vaporizing chamber to said combustion chambers.

14. A combustion tube burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a base provided with concentric, laterally spaced, fuel compartments comprising an inner shallow vaporizing compartment and a surrounding communicating annular vapor distributing compartment connected with said vaporizing compartment by open fuel passages, a tube-supporting platelike structure resting on the walls of the base comprising an outer ring structure having upstanding walls to support and position a combustion tube, an inner, laterally spaced, cover portion overlying said inner fuel compartment, said cover portion being connected with said outer ring structure by radial extensions overlying said open fuel passages, and means for supplying liquid fuel to said last named compartment said platelike structure leaving uncovered delivery spaces for delivering fuel vapor from said last named compartment to said combustion chambers. '15. A combustion tube burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a base provided with concentric, laterally spaced, fuel compartments connected by open fuel passages, a tube-supporting platelike structure resting on the walls of the base comprising an outer ring structure, a laterally spaced cover portion overlying one of said fuel compartments, said. portion being connected with said outer ring structure by radial extensions overlying said open fuel passages, and means for supplying liquid fuel to said last named compartment said platelike structure leaving uncovered delivery spaces for delivering fuel vapor from said last named compartment to said combustion 'chambers.

16. A combustion tube burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediateair chamber between the said combustion chambers and an inner air chamber within the inner tube, a burner base provided with two laterally spaced, concentrically located, open fuel compartments with open ducts connecting said compartments and having an air supply opening between the ducts, and a removable cover plate resting on the walls of said base underlying said inner air chamber and covering said open ducts and extending over one of said fuel compartments to partially cover the'same but leaving an opening therefrom aligned with said combustion chamber.

17. A liquid fuel burner having combustion tubes forming a combustion chamber and an inner air chamber adjacent thereto, a base having a broad horizontally arranged endless fuel channel, a removable cover plate resting on the base and having its walls extending from the inner side of said channel to partially cover the same, its extending walls being spaced from the underlying walls of the channel and underlying said inner air chamber and directly exposed to heat from the. tube separating said combustion chamber from said inner air chamber and lying in quick vaporizing proximity to the underlying walls of the channel to provide a vaporizing space beneath the cover plate at the inner part of said channel and separated from said air chamber by said plate, said extending walls of said cover plate leaving an opening registering with said combustion chamber and with the outer portion of the channel to provide a surrounding vapor distributing space in the outside of the channel beneath and opening into the combustion chamber and providing a support for the tube separating said combustion chamber from said inner air chamber, and means for introducing the liquid fuel to said burner at the bottom of the covered vaporizing space at the inner part of said channel that heat transmitted from the quick heating walls of said air chamber directly into proximity to said liquid fuel by said cover plate may expedite vaporization of the fuel thus to increase rapidity of starting of the burner and to concentrate vaporization under said cover plate during full operation of the burner and thereby localize carbon deposits where theyv may be readily removed.

18. A burner of the class described having pairs of concentrically spaced combustion tubes forming between them inner and outer combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a base surmounted by said combustion tubes and having openings for admitting air to said air chambers, said base presenting laterally spaced, interconnected, open, vapor distributing channels terminating in delivery portions, one surrounding the other, said portions being beneath and registering one with the outer and the other with the inner combustion chamber and opening into said chambers, one of said channels being of greater width than the other channel to form 'a vaporizing portion positioned laterally within and communicating with the delivery portion of said wider channel and extending beneath one of said air chambers,'a removable plate resting on the walls of the base to overlie a part of the wider channel, said plate covering said vaporizing portion and underlying said last-named air chamber and exposed to heat from the walls thereof, and means for supplying liquid fuel to said vaporizing portion.

19. A burner of the class described having pairs of concentrically spaced combustion tubes form'- ing between them inner and outer combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a

base surmounted by said combustion tubes and having openings for admitting air to said air chambers, said base presenting laterally spaced, interconnected, open, vapor-distributing channels terminating in delivery portions, one surrounding the other, said portions being beneath andlregistering-one with the outer and the other with the inner combustion chamber-and opening into said chambers, said inner delivery channel being of greater width than the other channel to form a vaporizing portion positioned laterally of and communicating with the delivery portion of said wider channel and extending beneath one of said :air chambers, a removable plate resting on the walls of the base to overlie a part of the wider channel, said platecovering said vaporizing portion and underlying said last-named air chamber and exposed to heat from the walls thereof, andmeans for supplying liquid fuel to said vaporizing portion.

20. A combustion tube burner having-pairs of concentrically spaced combustion tubes forming between them'a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner airchamber within the inner tube, a burner base provided with an annular fuel channel and a separate inner fuel vaporizing channel concentrically related thereto, said base having a plurality of open ducts connecting the two fuel channels and having a plurality of air supply openings between said ducts and between said two fuel channels, removable plate means carried 'bythe base comprising a first portion constituting atop for the said vaporizing channel underlying one of said air chambers and exposed directly to heat from the walls thereof, a second, annular portion resting at the top of one of said annular fuel-channels and providing a support for a com- *loustion tube thereabove with the combustion space adjacent the thus supported combustion tube communicating with said-annular fuel channel, and intermediate portions lying between said first and second portions for closing the top of each open duct.

21. A combustion tube burner as defined in claim 20in which said intermediate portions are connected, respectively, to at least one of said first and second portions of the removable'plate means.

' '22. A burner of the class described having a base provided with upstanding flanged walls and presenting an outer annular fuel channel and a laterally spaced inner annular fuel channel surrounded by said outer channel, said base being provided with air openings between said channelsand with an open duct connecting said channels, a removable covering means for said duct, and an annular structure concentric with said fuel channels resting on'and interfitting with the "flanged walls ofthe base and united to said ductcoveringmeans, whereby placing and removal of said annular structure effects placing and removal of said duct covering means.

23. A burner of the class described having a base provided'with an outer annular fuel chamberand a laterally spaced, inner, annular fuel chamber surrounded by said outer chamber, said base having formed therein a "plurality of open ducts connecting said chambers at spaced inter- 'vals and having air openings intervening between the two chambers and between the walls of the adjoining ducts, removable covering means for each of said ducts, and an annular structure uniting said covering means and resting on the walls of the base and'interfitting therewith to retain said covering means in position and to provide forremoval of said structure and covering means asa unit.

'24. A liquid fuel burner having spaced, concentric-combustion tubes forming inner and outer combustion chambers with an intermediate air chamber and an inner air chamber enclosed within the inner tube, a base surmounted by said combustion tubes and comprising an inner, radially broad, annular base portion and an outer, relatively narrow, annular base portion spaced from and surrounding said inner base portion and having connections thereto at intervals, said base having openings between said connections for supplying air to said intermediate air chamber and an opening within said inner base portion for supplying air to said inner air chamber, saidinner and outer base portions having vaporizing and distributing passages including annular, inner and outer, vapor distributing portions insaid respective base portions beneath and opening into said inner and outer combustion chambers, respectively, and said connections having ducts connecting said vapor distributing portions, said vaporizing and distributing passages including also an open vaporizing portion in said broad inner base portion and communicating with said vapor distributing portions, a removable cover plate resting on said base beneath said inner air chamber and exposed to the heat from the walls thereof, said plate covering said open vaporizing portion to form therewith a vaporizing chamber, and means tointroduce liquid fuel to said burner.

25. A combustion burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a base provided with laterally spaced, concentrically-located, inner and outer open fuel channels, one beneath and opening into each of said combustion chambers, said base having means for admitting air to the said air chambers and having diametrically opposite open ducts connecting said inner and outer fuel channels, said channeled base presenting also a vaporizing portion and Ta removable cover plate covering said vaporizing portion and having extensions crossing the inner.

fuel channel and covering. said ducts.

26. A combustion tube burner .having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, abase provided with laterally spaced, concentrically-located, inner and outer open fuel channels, one beneath and opening into each of said combustion chambers, said base having means for admitting air to the said air chambers, and an open duct connecting said fuel channels, said channeled base presenting also a vaporizing portion and a. removable cover plate covering said vaporizing portion and said open duct.

2'7. A combustion tube burner having a base provided with upstanding walls defining an outer annular fuel chamber and a laterally spaced inner annular fuel chamber, said base having an open duct connectingthe two chambers, pairs of spaced annular concentric combustion tubes forming combustion chambers in upstanding-relation to and opening each into one of said fuel chambers and forming an air-supply chamber intermediate the combustion chambers, said base having an opening intermediate the fuel chambers for a supply of air to the intermediate air chamber, and an annular, removable plate concentric with the annular fuelchambers closing the opentopof said duct'and having an opening registering with the intermediate air opening in the base.

28. A combustion tube burner comprising pairs ofspaced, cylindrical, combustion tubes forming between them inner and outer annular combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within said inner tube, a base having walls forming an outer annular fuel channel below and communicating with the outer combustion chamber and a laterally spaced inner annular fuel channel below and communicating with the inner combustion chamber, the walls of said base being also formed to provide openings intermediate said fuel channels for admitting air vertically to the intermediate air chamber and an opening for admitting air vertically to said inner air chamber, said base further presenting fuel passages open at the top interconnecting said innereand outer annular fuel channels and positioned between the air admission openings for said intermediate air chamber, an annular cover plate separate from but resting on said base and concentric with said annular fuel channels, said plate covering said fuel passages and closing them to the intermediate air chamber, said plate further having openings registering with the air supply openings between said channels and said plate presenting walls interengaging with and supporting the adjacent combustion tubes on opposite sides of said intermediate air chamber, and means for supplying liquid fuel to said fuel channels. A a e r a ,29. A combustion tube burner comprising pairs of spaced, cylindrical, combustion tubes forming between them inner and outer annular combustion, chambers and providing an intermediate air chamber. between said combustion chambers and an inner air chamber within said inner tube, a base having walls forming an outer annular fuel channel'below and communicating with the outer combustionrchamber and a laterally spaced inner 'annular fuel channel below and communicating with theinner combustion chamber, the walls of said base being also formed to provide openings intermediate said fuel channels for admit- .ting air vertically to the intermediate air chamberand an opening for admitting air vertically to said inner air chamber, said base having further formed therein a duct open at the top connecting said fuel channels andpositioned between adjacent air admission openings for said intermediate air chamber, an annular cover plate separate from but resting on said base and concentric with said annular fuel channels, said plate covering the open top of said duct and closing it to the intermediate air chamber, said plate further having openings registering with the air supply openings between said channels and presenting walls interengaging with and supporting the adjacent combustion tubes on opposite sides of said intermediate air chamber, and means for supplying liquid fuel to said fuel channels.

30. A combustion tube burner having pairs of concentrically spaced combustion tubes forming between them a plurality of combustion chambers and providing an intermediate air chamber between said combustion chambers and an inner air chamber within the inner tube, a burner base having an annular vapor distributing chamber andan inner, laterally spaced, shallow fuel vaporizing chamber concentrically related thereto, said base having formed therein an open duct between the two last named chambers and hav- "ing an air supply opening formed by the space between the two chambers, and aremovable plate extending over said vaporizing chamber restin on the walls of said base and exposed directly to the heat from the walls of the combustion tube surrounding said inner air chamber, said plate having an extension covering the open duct and said plate leaving uncovered delivery spaces for delivering fuel vapor to said combustion chambers.

31. A liquid fuel burner having pairs of spaced, concentric, combustion tubes forming spaced, in ner and outer combustion chambers with an intermediate air chamber and an inner air chamber enclosed within the inner combustion tube, a base surmounted by said combustion tubes having openings for supplying air'to said air chambers, said base having interconnected fuel vaporizing and distributing passages comprising laterally spaced, inner and outer, open, vapor distributing portions beneath and opening into said inner and outer combustion chambers, respectively, said vaporizing and distributing passages comprising also an open vaporizing portion beneath said in-' ner air chamber and further comprising means establishing communication between said vaporizing portion and said vapor distributing portions including an open channel formed in the walls of the base, a removable cover plate covering said vaporizing portion and said open channel and separating said vaporizing portion from the inner airchamber, said cover plate being exposed directly to the heat from said-inner combustion tube and said inner air chamber, and means for supplying liquid fuel to said passages, the walls of the base forming such vaporizing and vapor distributing portions being of such height'and said open channel being of such depth as to permit the liquid fuel entered into said vaporiz ing portion in starting the burner to pass through the vapor distributing passages into the vapor distributing portions and to be there maintained at a level below the tops of said walls.

32. A liquid fuel burner having spaced, concentric, combustion tubes forming spaced, inner and outer combustion chambers with an intermediate air chamber and an inner air chamber within the inner combustion tube, a'base surmounted by said combustion tubes having openings for admitting air to said air chambers, said base having interconnected fuel vaporizing and distributing passages, including laterally spaced, inner and outer, open, vapor distributing portions beneath and opening into said inner and outer combustion chambers, respectively, and an open duct connecting said inner and outer vapor distributing portions, said vaporizing and distributing passages including also an open vaporizing portion in the base beneath said inner air cham-' openings for supplying air to said air chambers, 1

said base having interconnected fuel vaporizing and distributing passages comprising laterally spaced, inner and outer, annular, open, vapor distributing portions beneath and opening into said inner and outer combustion chambers, re-

spectively, said vaporizing and distributing passages comprising also an open vaporizing portion beneath said inner air chamber and further comprising means establishing communication between said vaporizing portion and said vapor distributing portions including an open channel formed in the Walls of the base, a removable cover covering said vaporizing portion, separating said vaporizing portion from the inner air chamber and having an extension covering the open channel, said plate being exposed directly to the heat from said inner combustion tube and said inner air chamber, and means for supplying liquid fuel to said passages.

RALLSTON M. SHERMAN.

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