US3723052A

US3723052A - Liquid fuel burner apparatus

Info

Publication number: US3723052A
Application number: US00194246A
Authority: US
Inventors: A Nakashima; M Imajima; S Murase
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1970-11-13
Filing date: 1971-11-01
Publication date: 1973-03-27
Anticipated expiration: 1990-03-27
Also published as: BE775236A; NL168602B; DE2156374A1; GB1356608A; NL168602C; CH546922A; NL7115571A; AU432788B2; IT944911B; AU3536771A; DE2156374B2; CA929097A; FR2114621A5; DE2156374C3

Abstract

A substantially flat type liquid fuel burner apparatus comprising a chamber for gasifying liquid fuel, a second chamber above the gasifying chamber for mixing the gasified fuel with an amount of air, and a combustion zone above the mixing chamber into which the gaseous mixture and an additional amount of air are introduced for the complete combustion of the gasified fuel. The air supplied to the gasifying chamber is limited to such an amount to burn only a part of the liquid fuel fed to the gasifying chamber so as to heat a heating element disposed therein. The heated heating element is operative to pyrolyze the remaining part of the fuel into gasified fuel to thereby facilitate blue flame complete combustion of the fuel in the combustion zone.

Description

"atent 1 Unite States Nakashima et al.

[ 51 Mar. 27, 1973 [54] LIQUID FUEL BURNER APPARATUS Takatsuki, all of Japan [73] Assignee: Matsushita Electric Industrial Co.,

Ltd., Kadoma-shi, Osaka, Japan [22] Filed: Nov. 1, 1971 [21] Appl. No.: 194,246

[58] FieldoiSearch 431/196,l98,262,33l,333, 431/339, 341, 342

[56] References Cited UNITED STATES PATENTS Slezinsky ..43l/333 X Waits et al ..43l/262 2,756,811 7/1956 Little ..43l/262 FOREIGN PATENTS OR APPLICATIONS 1,490,734 6/1967 France ..431/331 Primary Examiner-Carroll B. Dority, Jr. Attorney-Richard K. Stevens et a1.

[57] ABSTRACT A substantially flat type liquid fuel burner apparatus comprising a chamber for gasifying liquid fuel, a second chamber above the gasifying chamber for mixing the gasified fuel with an amount of air, and a combustion zone above the mixing chamber into which the gaseous mixture and an additional amount of air are introduced for the complete combustion of the gasified fuel. The air supplied to the gasifying chamber is limited to such an amount to burn only a part of the liquid fuel fed to the gasifying chamber so as to heat a heating element disposed therein. The heated heating element is operative to pyrolyze the remaining part of the fuel into gasified fuel to thereby facilitate blue flame complete combustion of the fuel in the combustion zone.

12 Claims, 2 Drawing Figures PATENTEDHARZYIHYK SHEET 2 [1F 2 FIG. 2

LIQUID FUEL BURNER APPARATUS BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to a burner apparatus and, more particularly, to a flattened or thinned liquid fuel burner apparatus.

2. DESCRIPTION OF THE PRIOR ART Portable oilstoves of the type that directly exhausts combustion products are recently conveniently used. This type of oilstoves requires ventilation of the rooms because recent house is improved in air-tightness of the house structure and particularly of the door and window constructions. In addition, recent housing fashion and the arrangement of room furniture require a flattened or thinned household heating apparatus which can be disposed in a room close by the wall thereof. A heating apparatus which produces soot requires frequent cleaning of the apparatus and thus is disliked. A noisy heating apparatus is also objectionable. Thus, a demand has been made for a heating apparatus having a burner which is of substantially flattened style rather than circular style and is operative to provide sootless and noiseless combustion.

For the complete combustion of a liquid fuel, it is absolutely necessary that the contact of air with the molecules of the fuel take place throughout the interior of each of the particles of the fuel. This requires that the fuel be provided with surface of as greater area as possible. For this purpose, some of the prior art burners are designed such that a liquid fuel is preliminarily atomized for combustion. Gasification of the liquid fuel by pyrolysis has been known to be more advantageous for the purpose than the atomization. It is, however, very difficult to keep the burner at a substantially constant elevated temperature sufficient to pyrolyze a liquid fuel. In addition, pyrolysis of the liquid fuel accompanies disadvantageous production of carbon and tar.

If gasification of liquid fuel and uniform mixture of the fuel with air are not obtainable, the fuel is burnt to provide an unstable and incomplete combustion which accompanies production of soot which in turn causes clogging of burner holes and dis-uniform mixture of the fuel with air with resultant worsening of the combustion and decrease in the thermal efficiency of the burner. In addition, the production of soot requires frequent cleaning of the burner. Attempts have been made to eliminate the production of soot but have not resulted in successful solution of the problem. This is partly because the burner developed so far before the present invention is of such a design that the gasification of a liquid fuel and supply of air to the gasified fuel take place at different zones of the burner with a resultant disadvantage that the gasified fuel is not uniformly mixed with air.

Moreover, a flattened type burner is less practicable than a circular or so-called pot type burner because a burner of the former type suffers from a heat deformation due to temperature differential of more than about 400 C between the upper and lower parts of the burner. It is a matter of course that an extremely thinned burner is further less practicable and, therefore, it is impossible to obtain such an extremely thinned practical burner unless the problem of heat deformation is solved.

In an attempt to solve the problem above-discussed, there has been deviced a burner of diamond cross-section. Another attempt has been made to employ a sheet metal of an increased thickness to form a burner. A further attempt has been directed to the utilization of a reinforcing mechanism of a complicated structure for a burner. These attempts, however, have resulted in a bulky burner and the increase in the cost of manufacture, but not in the provision of a successful and satisfactory extremely thinned burner apparatus.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved liquid fuel burner apparatus comprising a burner which is divided into substantially separated two chambers and an upper zone, each partially defined by at least one perforated wall, for gasifying the liquid fuel, for mixing the gasified fuel with air and for the combustion of the gasified fuel, respectively, whereby a sootless, blue flame complete combustion of the fuel is obtained.

It is another object of the present invention to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the gasifying chamber is provided with a heating element disposed centrally of the chamber so that the space of the chamber is advantageously utilized and that the heating element receives and deals with the streams of air passed inwardly through air supply apertures in a pair of opposite walls of the chamber so as to improve the combustion of the fuel by the avoidance of a turbulence of the air flow and to maintain a little combustion within the chamber by the restrained air flow.

It is a further object of the present invention to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the heating element is made of a heat-resistant oil-permeable porous material disposed in a position to divide the gasifying chamber into two sub-chambers so that combustion flames are directed to the surfaces of the heating element to heat the same to an elevated temperature sufficient to advantageously pyrolyze the liquid fuel within or on the heating element and that the upward development or growth of the combustion is facilitated.

It is a further object of the present invention to provide an improved liquid fuel burner apparatus of the class specified in the above and in which a passage means is provided between the two sub-chambers to facilitate the passages of the gaseous material, air and combustion flames from one of the sub-chambers to the other or vice versa so that the development or growth of the combustion on the heating element and the burning operation of the burner are improved.

It is still a further object of the present invention to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the heating element in the gasifying chamber is of such a height as to enable the upper part of the heating element to receive and deal with the streams of air introduced through the uppermost air supply apertures so that a little constant combustion is maintained on the surfaces of the heating element and that the liquid fuel is sucked upwardly by the heating element to improve the development or growth of the combustion on the heating element and the burning operation of the burner.

A still further object of the present invention is to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the top of the gasifying chamber is partially closed by a pair of baffle plates which define therebetween a throat and which cooperate with the top of the heating element to define therebetween restricted gaps which function to cause the gasifying chamber to be filled with thick gasified fluid and restrain the flows of air so that a little combustion is maintained in the gasifying chamber to an extent sufficient to pyrolize the liquid fuel and that upward streams of unburnt gasified fuel from the two subchambers are gathered at the throat into a combined or united stream.

A still further object of the present invention is to provide an improved liquid fuel burner apparatus of the class specified in the above and in which air supply apertures for the mixing chamber are arranged in such a fashion as to facilitate uniform mixture of the gasified fuel with air.

A still further object of the present invention is to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the corn bustion zone is partially defined by a pair of upwardly diverging perforated walls between which is provided a combustion-assisting member of a circular or polygonal cross-section so that a large amount of air fed through the air supply apertures in the walls advantageously flows around the combustion-assisting member and is advantageously mixed with the upwardly flowing gaseous mixture from the mixing chamber to facilitate easy and uniform combustion reaction whereby a sootless, noiseless, blue flame complete combustion takes place in the combustion zone.

It is a still further object of the present invention to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the heating element of a heat-resistant oil-permeable porous material is also operative to prevent an excessive combustion of the fuel caused by excessive fuel supply due to accidental trouble in the flow regulation valve and prevent an unequal or unbalanced combustion due to an accidental inclination of the apparatus for thereby eliminating a dangerous operation of the apparatus.

It is still further object of the present invention to provide an improved liquid fuel burner apparatus of the class specified in the above and in which the abovediscussed separated three-stage arrangement and the unique gasifying feature of the apparatus provide substantially equalized temperature differential among the combustion zone, the mixing chamber and the gasifying chamber to minimize the heat deformation of the burner whereby the burner apparatus is permitted to employ an extremely thinned and flattened burner.

According to the present invention, there is provided a liquid fuel burner apparatus comprising a gasifying chamber defined by walls at least one of which is formed with a plurality of air supply apertures therein, means for supplying liquid fuel into said gasifying chamber, a heating element of a heat-resistant porous material disposed in said gasifying chamber, said air supply apertures being adapted to feed an amount of air just sufficient to burn a part of the liquid fuel supplied to said gasifying chamber so that said heating element is heated to an elevated temperature sufficient to pyrolyze the remaining part of the liquid fuel into gasified fuel, baffle plates partly closing the top of said gasifying chamber and cooperating together to define a throat therebetween and above said gasifying chamber, a mixing chamber above said gasifying chamber and being in communication with the latter through said throat so that said gasified fuel is passed through said throat into said mixing chamber, the latter having a volume greater than that of said gasifying chamber and having a plurality of air supply apertures for supplying an additional amount of air to said gasified fuel in said mixing chamber to produce a gaseous mixture, a combustion zone above said mixing chamber, a second throat between said mixing chamber and said combustion zone for passing said gaseous mixture thereto, said combustion zone being partially defined by a pair of opposite walls having formed therein a plurality of apertures for supplying a further amount of air to said gaseous mixture, the total of said additional and further amounts of air being sufficient for the complete combustion of said gasified fuel, and a combustion-assisting member disposed between said opposite walls of said combustion zone in substantially opposite relationship with said air supplying apertures in said opposite walls.

Other objects, features and advantages of the present invention will be made more apparent by the following description with reference to the accompanying drawings which illustrate embodiments of the invennon.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a fragmentary perspective view of an embodiment of the burner apparatus according to the present invention with a part of the apparatus being removed to show the inner structure thereof; and

FIG. 2 is a vertical sectional view of a slightly modified embodiment of the apparatus of the inventron.

Same reference numerals are used to indicate similar parts of the apparatuses in FIGS. 1 and 2.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIGS. 1 and 2 of the drawings, there are shown

burner apparatuses

10, 10 according to preferred embodiments of the invention. Since both embodiments of the invention are substantially identical except a part to be described later, the invention will be described hereunder mainly with reference to FIG. 1 of the drawings.

The burner apparatus 10 shown in FIG. 1 comprises a generally box-like housing 11 having a longitudinal dimension normally larger than the vertical dimension of the housing which is larger than the widthwise dimension so that the housing has a generally rectangular shape in cross-section as will be seen in the drawings. The housing has four vertical walls (only two of which are shown at 12 and 13), a top wall 14 and a bottom wall 15. The top and

bottom walls

14 and 15 are formed therein with

elongated openings

16 and 17 substantially coextensive with the longitudinal dimension of the housing 11, respectively.

The walls of the housing 11 define a space in which is disposed a burner body 20 of substantially symmetrical profile with respect to a vertical plane which includes the longitudinal axis of the housing 11. Namely, the burner body 20 has a pair of downwardly tapered or converging

upper wall portions

21 and 22 connected at the upper ends to the peripheral edge of the opening 16 in the top wall 14 of the housing 11. Rows of

apertures

23 and 24 are formed in the

wall portions

21 and 22, respectively, adjacent the peripheral edge of the opening 16 for the purpose to be made apparent later.

The

upper wall portions

21 and 22 are connected at their lower ends with downwardly diverging (or upwardly converging)

wall portions

27 and 28, respectively, which in turn are connected at their lower ends with substantially

vertical wall portions

31 and 32, respectively, which are spaced inwardly from the

side walls

12 and 13 of the housing 11, respectively.

In the preferred embodiment of the invention, a plu rality of apertures 33 are formed in one of the vertical wall portions 32 for the purpose to be described later.

The

vertical wall portions

31 and 32 are connected at their lower ends with substantially horizontal inwardly extending

wall portions

35 and 36, respectively. The

horizontal wall portions

35 and 36 are then connected at their inner ends with substantially vertically extending

lower wall portions

37 and 38, respectively, which are connected at the lower ends with a downwardly concave bottom wall 39 disposed above the opening 17 in the bottom wall of the housing 11.

The lower

vertical wall portions

37 and 38 are formed therein with rows of a plurality of

apertures

41 and 42, respectively, for the purpose to be described later. A pair of baffle plates 35a and 360 are mounted on the

horizontal wall portions

35 and 36 in such a manner that the baffle plates extend inwardly beyond the inner edges of the

horizontal wall portions

35 and 36 to cooperate to define therebetween a first throat 43 which is narrower than a second throat 29 defined between the lower ends of the downwardly converging upper wall portions 21 and 22 (upper ends of the downwardly diverging wall portions 27 and 28).

The lower

vertical wall portions

37 and 38, the baffle plates 35a and 36a and the bottom wall 39 of the burner body cooperate to define a space 45 which will be termed gasifying chamber for the reasons to be described later. A heating element 46 of a heat-resistant porous material, which is formed with a cutout 460 in the bottom end thereof, is disposed centrallyof the gasifying chamber 45 in such a manner that the heating element 46 substantially laterally divides the gasifying chamber 45 into two spaces or sub-chambers 45a and 45b which communicate each other through a passage provided by the cutout 460 in the heating element 46.

in place of the cutout 460, the bottom wall 39 of the burner body 20 may alternatively be formed with a recess (not shown) to provide a passage between the sub-chambers 45a and 45b. The sub-chamber 45a is communicated with the throat 43 through a gap 46a defined between the top edge of the heating element 46 and the inner edge of the baffle plate 36a while the subchamber 45b is communicated with the first throat 43 through a gap 46b defined between the top edge of the heating element 46 and the inner edge of the baffle plate 35a.

An ignition heater 47 having an ignition filament 47a and an ignition wick 47b extends inwardly through the side wall 37 of the gasifying chamber 45 into the subchamber 45b so that the ignition filament and

wick

47a and 47b are disposed adjacent the cutout 460 of the heating element 46. The latter is preferably made of a heat-resistant oil-permeable porous material selected from a group including particles of carborundum (Trade Name) bound by means of a binder and heat, a sintered metal, an earthenware material, a ceramic material and the like.

A fuel supplying conduit 48 from a liquid fuel supply source (not shown) extends through the side wall 13 of the housing 11 and through the lower vertical wall 38 into the sub-chamber 45a.

The side wall 12 of the housing 11 and the

wall portions

21, 27, 31, 35 and 37 of the burner body 20 cooperate to define an air passage 51 communicating with the atmosphere through the opening 17 in the bottom wall 15 of the housing 11 while the side wall 13 of the housing and the

wall portions

22, 28, 36 and 38 of the burner body 20 cooperate to define an air passage 52 communicating with the atmosphere through the opening 17.

With the afore-described structure, when a liquid fuel is fed through the fuel supply conduit 48 to the gasifying chamber 45, the lower part of the chamber is filled with a quantity of the fuel a part of which is sucked into the mass of the heating element 46. Air is fed from the

air passages

51 and 52 through the

apertures

41 and 42 into the gasifying chamber 45. When an electric current is passed to the ignition heater 47, the heater coil 47a is red-heated to ignite the fuel on the ignition wick 47b which in turn ignites the liquid fuel on the surface of the heating element 46 adjacent the cutout 46c. The heating element 46 acts as a kind of wick along which the combustion of the fuel develops upwardly to heat the heating element to an elevated temperature for thereby vaporizing the liquid fuel on the heating element. The vaporized fuel is burnt to form flames adjacent the

apertures

41 and 42 in the

walls

37 and 38 to heat the gasifying chamber 45. The flames 56 and the elevated temperature in the chamber 45 further heat the heating element 46 to a further elevated temperature ranging from about 450 C to about 500 C which is sufficient to pyrolyze or decompose by heat the liquid fuel sucked into the heating element 46. At the same time, the liquid fuel supported on the bottom 39 is vaporized. The vaporized fuel moves upwardly into contact with the heating element 46 and is also pyrolyzed by the heated heating element to produce a heated gasified fuel which is appropriate for uniform mixture with air and for the facilitation of combustion. Moreover, the air supplied from the

air passages

51 and 52 is moved into contact with the heating element 46 and thus is heated thereby to an elevated temperature. Within the sub-chambers 45a and 45b, therefore, the heated gasified fuel and the heated air are well mixed together to keep a small blue flame combustion. This is because air is introduced through the

apertures

41 and 42 into the mass of heated gasified fuel so that the air and the gaseous fuel are appropriately mixed together to facilitate easy and prompt combustion or oxization while the heating plate 46 and the baffle plates 35a and 35b serve to restrain the flow of air.

it will be appreciated that only a part of the fuel is burnt in the gasifying chamber 45 to produce heated gasified or atomized fuel. For this purpose, the total area of the

air supply apertures

41 and 42 is preferably determined to be as large as 10 to 25 percent of the total area of air supply apertures of the burner body 20 required for the complete combustion of the fuel.

The lower-most aperture 41 and 42' in the

vertical wall portions

37 and 38 are positioned above the liquid fuel level H in the gasifying chamber 45 which is determined by a fuel flow regulator (not shown) so as to prevent an accidental overflow which would otherwise take place in the case of miss-ignition. In addition, the top of the heating element 46 is positioned at such a level as to enable the upper part of the heating element 46 to surely receive and deal with the flow of air fed through the uppermost rows of

apertures

41 and 42.

The unburnt quantity of gasified fuel moves from the sub-chambers 45a and 45b of the gasifying chamber 45 through the gaps 46a and 46b and through the throat 43 into a mixing chamber 55 which is defined by the

wall portions

27, 28, 31, 32, 35, 36 and the baffle plates 35a and 36a. As will be seen in FIG. 1, the mixing chamber 55 is of a volume greater than that of the gasifying chamber 45. The flow of unburnt gasified fuel from the gasifying chamber 45 is rectified by the cooperation of the baffle plates 35a and 360 into a relatively thinner wall-like stream which is passed into the mixing chamber 55 in which the unburnt gasified fuel is further mixed with an amount of air fed through the apertures 33 in the vertical wall portion 32. it will be appreciated that, since the air supply apertures 33 for the mixing chamber 55 are formed in only one of the vertical walls 32 of the chamber 55, the wall-like stream of the unburnt gasified fuel is biased toward the other wall portion 31 having no air supply aperture formed therein, with a result that the mixture of the gasified fuel and the air is caused to have its concentration varied in different zones in the mixing chamber 55. More specifically, the mixture is of a too lower concentration for the mixture to be burnt in the zone adjacent the vertical wall portion 32 having air supply apertures 33 formed therein while the mixture is of a too higher concentration for the mixture to be burnt in the zone adjacent the other wall portion 31. In addition, since the mixing chamber 55 has a larger volume than the gasifying chamber 45, the mixing chamber 55 has an increased capacity to allow the air to flow therethrough. Of course, the part of the air-fuel mixture which is of a concentration appropriate for the combustion is burnt in the zone of the mixing chamber 55 adjacent the wall portion 32, but it will be appreciated that the combustible part of the mixture is only a part of the amount of the mixture contained in the mixing chamber.

In stead of only one vertical wall portion 32 being formed with air supplying apertures such as 33, the opposite

vertical wall portions

31 and 32 may both be formed with such apertures. In such modification, the air supply apertures may be of smaller size or may be so arranged as not to face one another for thereby eliminating or at least minimizing the collision of opposite air streams from the apertures in the

opposite wall portions

31 and 32. However, one-sided air supply as employed in the preferred embodiments of the invention more advantageously achieves the object of the invention.

The total area of the air supply apertures in the vertical wall portion 32 of the mixing chamber 55 is preferably as large as 10 to 25 percent of the total area of air supply apertures for the burner body 20 required for the complete combustion of the fuel.

The thinner and thicker streams of the air-fuel mixture are gathered by the upwardly converging

wall portions

27 and 28 into a combined stream in which air and gasified fuel are uniformly mixed. The combined stream is passed through the throat 29 into a combustion zone which is partly defined by the downwardly converging

upper wall portions

21 and 22 of the burner body 20. The

apertures

23 and 24 in the

wall portions

21 and 22 pass an additional amount of air sufficient for the complete combustion of the gasified fuel fed upwardly through the throat 29 into the combustion zone of the burner. Preferably, the total area of the

air supply apertures

23 and 24 is as large as 50 to percent of the total area of the air supply apertures in the

walls

21, 23, 32, 37 and 38.

In the illustrated embodiments of the invention, the

apertures

23 and 24 are arranged in a pair of opposite substantially straight rows, respectively. The apertures, however, may alternatively be arranged such that the sets of

apertures

23 and 24 are arranged in' a plurality of rows, respectively. In such modification, the

apertures

23 and 24 may preferably be arranged zigzag in the

wall portions

21 and 22, respectively, so that each of the apertures 23 in the wall portion 21 is substan tially laterally aligned with or faces the corresponding one ofthe apertures 24 in the other wall portion 22.

The combustion zone is advantageously provided with a combustion-assisting member 57 of a heat-resistant material such as porcelain or iron having a circular or annular cross-sectional configuration. The combustion-assisting member 57 is mounted at the opposite ends on the housing 11 in such a position as to produce a turbulence in the upwardly flowing unburnt gaseous mixture from the throat 20 so that the air fed through the

apertures

23 and 24 in the

wall portions

21 and 22 is advantageously mixed with the unburnt gaseous material from the throat 29, with an advantageous result that the gasified fuel is substantially completely burnt to form sootless, clear blue flames 58 adjacent the

air supply apertures

23 and 24 and the combustionassisting member 57.

The burner apparatus 10 of the modified embodiment shown in FIG. 2 is substantially identical with the embodiment shown in FIG. 1 except a combustionassisting member 57 which has diamond cross-sectional configuration as shown. The member 57', however, is not limited to the configuration shown and may be of any other polygonal cross-section (not shown). In addition, the combustion-assisting members 57 and 57' may be provided thereon with fins (not shown) which provide increased heat radiation surface areas andreinforcing strengths for the members.

As an example, the burner body 20 of the liquid fuel burner apparatus according to the present invention may have a size as follows:

Widthwise dimension 8 cm Longitudinal dimension 35 cm Height (vertical dimension) 18 cm The burner apparatus employing a burner body 20 of the above exemplified size may generate a thermal energy as large as about 8000 KCal/hr. The burner body 20 may have an increased longitudinal dimension with other dimensions unchanged to generate an increased amount of thermal energy. A burner body having a longitudinal dimension two times the above exemplified longitudinal dimension will generate a thermal energy of an amount substantially two times the above-mentioned amount of thermal energy.

The burner apparatus of the present invention may be operated in such a manner that a heat exchanger (not shown) is placed on or above the top of the apparatus so that the heat exchange medium in the heat exchanger is heated by the apparatus of the invention. The heated heat exchange medium may be brought into heat exchanging relationship with atmospheric air.

What is claimed is:

1. A liquid fuel burner apparatus comprising a gasifying chamber defined by walls at least one of which is formed with a plurality of air supply apertures therein, means for supplying liquid fuel into said gasifying chamber, a heating element of a heat-resistant porous material disposed in said gasifying chamber, said air supply apertures being adapted to feed an amount of air just sufficient to burn a part of the liquid fuel supplied to said gasifying chamber so that said heating element is heated to an elevated temperature sufficient to pyrolyze the remaining part of the liquid fuel into gasified fuel, baffle plates partly closing the top of said gasifying chamber and cooperating together to define a throat therebetween and above said gasifying chamber, a mixing chamber above said gasifying chamber and being in communication with the latter through said throat so that said gasified fuel is passed through said throat into said mixing chamber, the latter having a volume greater than that of said gasifying chamber and having a plurality of air supply apertures for supplying an additional amount of air to said gasified fuel in said mixing chamber to produce a gaseous mixture, a combustion zone above said mixing chamber, a second throat between said mixing chamber and said combustion zone for passing said gaseous mixture thereto, said combustion zone being partially defined by a pair of opposite walls having formed therein a plurality of apertures for supplying a further amount of air to said gaseous mixture, the total of said additional and further amounts of air being sufficient for the complete combustion of said gasified fuel, and a combustion-assisting member disposed between said opposite walls of said combustion zone in substantially opposite relationship with said air supplying apertures in said opposite walls.

2. A burner apparatus as defined in claim 1, in which said heating element is disposed in said gasifying chamber in a position substantially to divide the same into two sub-chambers, the top of said heating element cooperating with said baffle plates to define gaps therebetween.

3. A burner apparatus as defined in claim 2, in which the top of said heating element is positioned at such a level as to enable the upper part of said heating element to receive and deal with the streams of air fed through the uppermost air supply apertures in the walls of said gasifying chamber.

4. A burner apparatus as defined in claim 2, in which means are provided for communicating one of said subchambers with the other.

5. A burner apparatus as defined in claim 4, in which said communicating means is a cutout formed in said heatin element.

6. A urner apparatus as defined in claim 4, in which said communicating means is a recess formed in one of the walls which define said gasifying chamber.

7. A burner apparatus as defined in claim 2, in which the air supply apertures for said mixing chambers are formed in only one of the walls which define said mixing chamber.

8. A burner apparatus as defined in claim 2, in which said opposite walls of aid combustion zone are upwardly diverging.

9. A burner apparatus as defined in claim 8, in which said combustion-assisting member has a polygonal cross-sectional configuration.

10. A burner apparatus as defined in claim 8, in which said combustion-assisting member has a circular cross-sectional configuration.

11. A burner apparatus as defined in claim 7, in which the top of said mixing chamber is partially closed by a pair of upwardly converging walls which cooperate to define said second throat therebetween.

12. A burner apparatus as claimed in claim 2, in which the total area of said air supply apertures for said gasifying chamber is as large as 10 to 25 percent of the sum of the area provided by all of the air supply apertures for said gasifying and mixing chambers and said combustion zone, the total area of said air supply apertures for said mixing chamber is as large as 10 to 25 percent of said sum of area and the total area of said air supply apertures for said combustion zone is as large as 50 to percent of said sum of area.

Claims

1. A liquid fuel burner apparatus comprising a gasifying chamber defined by walls at least one of which is formed with a plurality of air supply apertures therein, means for supplying liquid fuel into said gasifying chamber, a heating element of a heatresistant porous material disposed in said gasifying chamber, said air supply apertures being adapted to feed an amount of air just sufficient to burn a part of the liquid fuel supplied to said gasifying chamber so that said heating element is heated to an elevated temperature sufficient to pyrolyze the remaining part of the liquid fuel into gasified fuel, baffle plates partly closing the top of said gasifying chamber and cooperating together to define a throat therebetween and above said gasifying chamber, a mixing chamber above said gasifying chamber and being in communication with the latter through said throat so that said gasified fuel is passed through said throat into said mixing chamber, the latter having a volume greater than that of said gasifying chamber and having a plurality of air supply apertures for supplying an additional amount of air to said gasified fuel in said mixing chamber to produce a gaseous mixture, a combustion zone above said mixing chamber, a second throat between said mixing chamber and said combustion zone for passing said gaseous mixture thereto, said combustion zone being partially defined by a pair of opposite walls having formed therein a plurality of apertures for supplying a further amount of air to said gaseous mixture, the total of said additional and further amounts of air being sufficient for the complete combustion of said gasified fuel, and a combustion-assisting member disposed between said opposite walls of said combustion zone in substantially opposite relationship with said air supplying apertures in said opposite walls.

4. A burner apparatus as defined in claim 2, in which means are provided for communicating one of said sub-chambers with the other.

5. A burner apparatus as defined in claim 4, in which said communicating means is a cutout formed in said heating element.

6. A burner apparatus as defined in claim 4, in which said communicating means is a recess formed in one of the wallS which define said gasifying chamber.

12. A burner apparatus as claimed in claim 2, in which the total area of said air supply apertures for said gasifying chamber is as large as 10 to 25 percent of the sum of the area provided by all of the air supply apertures for said gasifying and mixing chambers and said combustion zone, the total area of said air supply apertures for said mixing chamber is as large as 10 to 25 percent of said sum of area and the total area of said air supply apertures for said combustion zone is as large as 50 to 80 percent of said sum of area.