US3428407A

US3428407A - Pot-type liquid fuel burners

Info

Publication number: US3428407A
Application number: US579249A
Authority: US
Inventors: Juichi Honda; Kimio Matsumura; Sadao Yoshida; Ryutaro Mori
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1965-12-24
Filing date: 1966-09-14
Publication date: 1969-02-18
Anticipated expiration: 1986-02-18
Also published as: DE1501845B2; DE1501845A1; GB1118376A

Description

.Feb. 18, 1969 JUlCHl HONDA ET POT-TYPE LIQUID FUEL BURNERS I ofP,

Sheet Filed Sept. 14, 1966 W. O 7 a 2 a o a 6 a r. 2 fig. y m ,A m A J IN VENT 0R3 Tue! Hanan ATTORNEY Feb. 18, 1969 JUICH] HONDA ET AL 3,428,407

POT-TYPE LIQUID FUEL BURNERS Filed Sept. 1.4, 1966 Sheet 2 of 2 INVENTORS JoueH Hon/0n K/m/o Maraumfin v snono Yasman levurneo M0!!! ATTORNEY United States Patent Office 3,428,407 Patented Feb. 18, 1969 3,428,407 POT-TYPE LIQUID FUEL BURNERS Juichi Honda, Kimio Matsumura, and Sadao- Yoshida,

Tochigi-ken, and Ryutaro Mori, Mitaka-shi, Japan, assignors to Hitachi, Ltd., Tokyo, Japan, a corporation of Ja an P Filed Sept. 14, 1966, Ser. No. 579,249 Claims priority, application Japan, Dec. 24, 1965,

40/79,301, 40/ 79,302, 40/ 79,303 US. Cl. 431-249 4 Claims Int. Cl. F23d /04 ABSTRACT OF THE DISCLOSURE A liquid fuel pot burner having a liquid charged vaporizing plate with an outer cylindrical peripheral wall extending vertically therefrom, an open ended inner cylinder providing fluid communication through the center of the plate and being surrounded by an outer cylindrical cover provided in its lower portion with air supply holes only within a quadrant thereof. An auxiliary burner provided with a wick is mounted radially opposite the air supply holes between the plate and a pilot ring, which is between upper secondary air supply holes and lower primary air supply holes extending through the outer peripheral wall.

BACKGROUND OF THE INVENTION Pot-type burners of the type specified are provided with a burner pot composed of a bottom plate in which a liquid fuel is to be charged and an outer peripheral wall upwardly extending from the periphery of the plate and having air supply holes formed therein, so that the liquid fuel introduced in the bottom plate is vaporized and mixed with air fed through the air supply holes for combustion.

In this type of burner, the lower end of a kindling wick is dipped in the liquid fuel introduced in the bottom of the burner pot to accelerate the vaporization of fuel at the top thereof where the combustion initially takes place.

The bottom of the burner pot is heated by the combustion of the fuel at the kindling wick portion, thus accelerating the vaporization of fuel thereon and as a result the combustion is expanded from the combustion localized at the kindling wick portion over the entire surface of the bottom of the burner pot. The bottom of the burner pot is further heated by the combustion of fuel over the entire surface thereof, with more fuel vaporizing thereon, and finally the combustion proceeds into normal combustion.

When the combustion is not required, a small amount of fuel is burnt on an ignition wick which is provided as a substitution for the kindling wick and thereby an automatic intermittent operation of the burner is possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a burner of the type which ensures complete combustion of a fuel during normal operation of the burner with no generation of free carbon or soot and in which the combustion is stable even when the fuel quantity and/or draft are changed.

Another object of the invention is to provide a burner of the type in which transition of combustion from the combustion on an ignition wick or a kindling wick to normal combustion is effected smoothly.

Still another object of the invention is to provide a burner of the type in which generation of soot due to the combustion of a fuel on an ignition wick or a kindling wick is minimized and a tolerable range of fuel supply quantity is wide.

BRIEF DESCRIPTION OF THE DRAWING Other objects and advantages of the present invention will become apparent from the detailed description provided hereinafter with reference to the accompanying drawings illustrating an embodiment thereof, in which:

FIG. 1 is a cross section through the axis of a pot-type liquid fuel burner according to the present invention;

FIG. 2 is a fragmentary cross section taken on the line A-A of FIG. 1;

FIG. 3 is a top view of the burner shown in FIG. 1; and

FIG. 4 is a perspective view in enlargement of an ignition or kindling auxiliary burner of the inventive burner to illustrate the construction thereof in detail.

DETAILED DESCRIPTION OF THE DRAWING The pot-type burner of the invention has a burner pot, which comprises a vaporizing plate 3 composing a bottom and a lower portion of an outer peripheral wall of the burner, an outer peripheral wall 2 extending upwardly from said vaporizing plate 3 and a combustion ring 1 mounted on the top end of said outer peripheral wall 2. The vaporizing plate 3 is formed at a portion of its outer peripheral wall with a fuel supply port 4 which is communicating with a suitable fuel supply source, e.g. a fuel tank. The bottom surface of the vaporizing plate 3 is sloped upwardly towards the center thereof. The vaporizing plate 3 is also formed with an oil groove 18 at a portion of the bottom where the liquid fuel is first introduced through the fuel supply port 4.

In the outer peripheral wall 2 of the burner pot are formed air supply holes 6, 7, 8, 9, 10' and 11, of which 6 and 7 are directed upwardly for supplying the secondary air therethrough; 8, 9 and 10 are directed horizontally for supplying the primary air therethrough; and 11 is directed downwardly for supplying the primary air therethrough.

Between said air supply holes 10 and 11 there is disposed a pilot ring 25 whose outer diameter is slightly smaller than the inner diameter of the outer peripheral wall 2 of the burner pot and which rests on pins 25a projecting inwardly from said outer peripheral Wall 2. An outer cylindrical cover 13 is mounted at the center of the vaporizing plate 3 to extend through a central opening 25b in said pilot ring 25 to a level substantially equal to the level of said air supply holes 6 and 7. The outer cylindrical cover 13 has formed in the entire periphery of the top end portion thereof secondary

air supply holes

14, 15, 16 and 17 and also formed in. a portion at most within a quadrant thereof below the pilot ring 25 air supply holes 20. An inner cylinder 12 having both ends open is disposed interior of the outer cylindrical cover 13, with the bottom end thereof welded to the peripheral edge of a central opening 3a, formed within a fitting for the outer cylindrical cover 13 provided on the vaporizing plate 3, in such a manner that the portion of the open ended inner cylinder 12 projecting upwardly from the vaporizing plate 3 is enclosed in the outer cylindrical cover 13.

The kindling wick or ignition wick 19 has its lower end dipped in the oil present in the oil groove 18, said wick 'being composed of a heat-resistant material, such as stainless steel, knitted into the shape. The air supply holes 20 are provided in opposed relation to the ignition wick 19. The auxiliary burner comprising the ignition or kindling wick is formed of an upper partition wall 21 covering the top end of the wick 19 and

side partition walls

35, 35, and is located below the pilot ring 25. The

side partition walls

35, 35 are disposed radially to form an outwardly facing opening 22 in the proximity of the outer peripheral wall 2 of the burner pot, and have small holes 24 and 26 formed in portions thereof. The ignition or kindling wick 19 is secured to the upper partition wall 21 by means of radially disposed guide members 23 and an ignition opening 5 is provided in the outer peripheral wall 2 in opposed .relation therewith.

With the construction described, air around the burner pot is constantly introduced into said burner pot through the air supply holes 6, 7, 8, 9, and 11 in the outer peripheral wall 2 and also through the open ended inner cylinder 12 and thence through the

air supply holes

14, 15, 16, 1-7, and in the outer cylindrical cover 13, by means of the draft produced by a chimney or air blower.

When a small amount of liquid fuel is introduced through the fuel supply port 4, the fuel flows in the oil groove 18 to soak into the wick 19 and is vaporized vigorously from the surface thereof. The fuel gas thus vaporized is mixed with air around the wick or the air supplied through the air supply holes 20, so as to be readily ignited through the ignition opening 5.

The air introduced through the air supply holes 20 flows in the right and left directions :and, by disposing the wick 19 at a point where said flow of air is diverged, the wick may be ignite-d positively by a lighted match through the ignition opening 5. This ignition may further be ensured since said bidirectional flows of air are guided by guide members 23. The fuel combustion on the wick 19 elevates the temperature of the liquid fuel present in the oil groove 18 to cause the vaporization thereof and thus the combustion is extended over the entire area within the auxiliary burner. In this case, since the flame of the burning fuel on the wick 19 is directed towards the outer periphery of the burner, the vaporizing plate 3 is heated in an efficient manner, which will enhance the smooth extension of combustion in the auxiliary burner. When the fuel is supplied in a small quantity, the comhustion in the auxiliary burner takes place only in the vicinity of the small holes 20 in the outer cylindrical cover 13, presenting the appearance as if the flames are injected through the small holes 20, but as the supply of liquid fuel increases, the combustion moves in the direction in which air is supplied through the holes 20, i.e. in the direction of the

holes

22, 22 in the auxiliary burner. Since, in this case, the flow of air fed through the holes 20 is diverged bidirectionally in the right and left directions, the combustion also proceeds in the right and left directions accordingly. The transition of such combustion is eased by the guide members 23. As such, the transition of the combustion within the auxiliary burner may be optionally adjusted by the amount of liquid fuel supplied therein, and therefore the tolerable range of fuel supply quantity is rendered wide. It is also to be noted that a uniform flow of air into the auxiliary burner may be obtained by arranging the small holes 20 in the outer cylindrical cover 13 in a symmetrical relation lateral ly and in uniformly spaced relation vertically as shown in FIGS. 1 and 2, whereby the air is mixed with the fuel vaporizing on the surface of the oil groove 18 homogeneously so as to minimize the generation of soot upon combustion. In addition, the side partitions 35, do not constitute 1. resistance to the combustion extending within the auxiliary burner because they are disposed radially with the interspace expanding progressively outwardly from the outer cylindrical cover 13 towards the outer peripheral wall 3 and thereby it is possible to obtain a stable combustion without being subjected to disturbance. This also contributes to a stable combustion with a minimum soot.

The high temperature combustion gas generated in the auxiliary burner contacts the outer

peripheral walls

2, 3 of the burner pot to heat the vaporizing plate 3 at high efficiency. The vaporizing plate 3 may be heated most efliciently when the combustion takes place at the opening 22 directly heating said plate. As a result, the vaporizing plate 3 can be preheated in a short period of time. Therefore, when the liquid fuel is supplied in a large quantity thereafter, it is vaporized completely and quickly from the entire surface of the vaporizing plate 3, providing for a quick expansion of the combustion over the entire area of the burner pot. This combustion further heats the vaporizing plate 3 and as a result the combustion proceeds into normal combustion. It will be appreciated from the foregoing that, in the inventive burner, the transition of combustion from the combustion on the ignition wick 19 to normal combustion of the burner is effected in a highly satisfactory manner.

The surface 26 of the vaporizing plate 3, as shown in FIG. 1, is sloped upwardly towards the center. This not only reduces the quantity of fuel dumped thereon but also increases the strength of the plate. Still further, the sloped surface enables the heat to be transmitted from the outer peripheral wall 2 to the oil effectively and provides for the formation of a uniform film of the oil thereon due to the surface tension, which will promote the vaporization of the fuel and thus render the concentration of fuel gas uniform.

During normal combustion in the burner, a part of the primary air is caused to flow through the open ended inner cylinder 12, disposed at the center of the burner pot, by the burning flame and discharged outwardly through the small holes 20 in the outer cylindrical cover 13 to be introduced into the fuel gas vaporizing from the surface 26 of vaporizing plate 3. That part of the primary air is then diverged to the right and left at the outer peripheral wall 2 and accelerates the vaporization of fuel together with the other part of the primary air introduced through the air supply holes in the outer peripheral wall 2, producing a satisfactory mixture of the fuel gas and air.

In the embodiment illustrated herein, a part of the primary air, which is introduced through the opening 22 of the auxiliary burner and flows along the outer peripheral wall 2, is caused to swirl centrally by the other part of the primary air being fed through the air supply holes 11 in the outer peripheral wall, so that the fuel is mixed with the primary air more thoroughly. Such a mixing of fuel gas and primary air takes place below the pilot ring 25 which is sloped, most preferably at an angle of 15 The inner diameter of the pilot ring 25 is most critical for satisfactory combustion of fuel and should therefore be determined so as to be optimum.

The resultant mixture of vaporized fuel oil and air, somewhat turbulent, then ascends through the space between the pilot ring 25 and the outer cylindrical cover 13, during which period it is diluted progressively and homogeneously with the primary air supplied through the air supply holes 10, 9 and 8, formed in the outer peripheral wall 2, in the order mentioned. The mixed gas flows upwardly along the outer wall of the outer cylindrical cover 13 since said outer wall does not have holes therein and the primary air is supplied only unidirectionally from the outer peripheral wall 2 towards the center of the burner.

The gas thus mixed with air homogeneously thoroughly is further supplied with a large amount of the secondary air introduced through the

small holes

17, 16, 15 and 14 formed in the upper end portion of outer cylindrical cover 13 and also through the small holes 7 and 6 formed in the upper end portion of the outer peripheral wall 2, so that it burns completely with a short flame length while maintaining high combustion temperatures. Even when there is some variation in the fuel rate supplied and/or in the state of air draft, it is possible to obtain a satisfactory combustion constantly, owing to the thorough mixing of the fuel with the primary air and the supply of a large amount of the secondary air as mentioned above. Accordingly the tolerable range of the fuel quantity is rendered wide and generation of free carbon or soot is kept to minimum.

The joint of the outer cylindrical cover 13 with the vaporizing plate 3 is the area which is most critical relative to obtaining a satisfactory proportion of the quantity of the primary air and the secondary air supplied to the quantity of the fuel gas. In this view, the outer cylinder is preferably connected to the vaporizing plate completely, either by means of welding or by the use of a heatresistant sealing material, so as to ensure no air leakage therethrough. Such air-tight connection may also be achieved by forming an upwardly extending projection 27 on the vaporizing plate 3 and a flange 28 at the bottom end of the outer cylindrical cover 13 as shown for scalable engagement with each other.

The height of the open ended inner cylinder 12 should be determined such that a satisfactory proportion of the amount of air required for the ignition combustion or the kindling combustion as will be described later to ,the amount of air required for normal combustion at high fuel rate can be maintained. A further minor adjustment may be effected either by changing the size of the guide members 23 or by the provision of a metal net on said guide members.

In use of the pot-type burner described herein with a water-heater in which water is to be kept hot constantly, the burner is required to be operated intermittently. Such intermittent operation may be achieved automatically by using the ignition wick in place of the kindling wick and maintaining the combustion within the auxiliary burner by means of the kindling wick with the supply of low or pilot fuel rate when normal combustion of the high fuel rate is not required. This combustion proceeds in the similar manner as in the case of ignition and it is, therefore, possibly to obtain a wide tolerable range of the fuel supply quantity and to minimize the generation of soot.

It should be noted that, while the description herein is given on an embodiment, the present invention is not restricted thereto but many modifications and changes are possible for the detailed portions without deviating from the spirit and scope of the claims of the invention.

What is claimed is:

1. A pot-type liquid fuel burner having a burner pot, which pot comprising a vaporizing plate on which a liquid fuel is to be charged, an outer peripheral wall upwardly extending from the periphery of the plate and having a number of air supply holes formed therein, an open ended inner cylinder vertically mounted on said vaporizing plate and communicating with the lower space below the plate and an outer cylindrical cover upwardly extending from the upper surface of the plate and enclosing said inner cylinder and communicating with said inner cylinder at the upper portion thereof, said outer cylindrical cover being imperforate in a lower portion thereof except within a quadrant thereof which is provided with holes for supplying air outwardly therethrough towards the space between the outer cylindrical cover and said outer peripheral wall.

2. A pot-type liquid fuel burner having a burner pot, which pot comprising a vaporizing plate, an outer peripheral wall extending from the periphery of the plate and having formed therein a number of secondary air supply holes at the upper portion and a number of primary air supply holes at the lower portion thereof, a pilot ring adapted to divide the interior of the burner pot vertically at a point below said secondary air supply holes, said burner pot being composed of said vaporizing plate and said outer peripheral wall, an open ended inner cylinder vertically mounted on said vaporizing plate and communicating with the lower space below the plate, and an outer cylindrical cover upwardly extending from the upper surface of the plate and enclosing a portion of said inner cylinder and communicating with said inner cylinder at the upper portion thereof, said outer cylindrical cover being imperforate in a lower portion thereof except within a quadrant thereof which is provided with holes for supplying air outwardly therethrough towards the space between the outer cylindrical cover and said outer peripheral wall and having secondary air supply holes at the upper end portion thereof.

3. A pot-type liquid fuel burner having a burner pot, which pot comprising a vaporizing plate for burning a liquid fuel thereon, a burner pot outer peripheral wall upwardly extending from the periphery of the plate and having a number of air supply holes formed therein, an open ended inner cylinder mounted on said vaporizing plate in communication with the lower space below the plate thereof and an outer cylindrical cover upwardly extending from the upper surface of the plate and enclosing a portion of said inner cylinder and communicating with said inner cylinder at the upper portion thereof, said outer cylindrical cover being imperforate in a lower portion thereof except within a quadrant thereof which is provided with holes for supplying air outwardly peripherally therethrough, or a wick disposed within an auxiliary burner at a point where the air introduced through the holes in said outer cylindrical cover is diverted and having the lower end thereof dipped in the liquid fuel present in said vaporizing plate, said auxiliary burner being composed of side partition walls extending radially from both sides of the air supply holes in said outer cylindrical cover towards the space between the outer cylindrical cover and said outer peripheral wall and defining an opening in the proximity of said outer peripheral wall and an upper partition wall covering the top ends of said side partition walls, and an ignition opening formed in said burner pot outer peripheral wall in opposed relation to said wick.

4. A pot-type liquid fuel burner having a burner pot, which pot comprises a vaporizing plate on which a liquid fuel is to be charged, a burner pot open ended outer peripheral wall upwardly extending from the periphery of the plate and having a number of secondary air supply holes formed in the lower portion and a number of primary air supply holes formed in the lower portion thereof, a pilot ring adapted to divide the interior of the burner pot vertically at a point below said secondary air supply holes, said burner pot being composed of said vaporizing plate and said outer peripheral wall, an open ended inner cylinder vertically mounted on. said vaporizing plate and communicating with the lower space below the plate, an outer cylindrical cover upwardly extending from the upper surface of the plate and enclosing a portion of said inner cylinder which is extending upwardly from said evaporating plate and communicating with said inner cylinder at the upper portion thereof, said outer cylindrical cover being imperforate in a lower portion thereof except within a quadrant thereof which is provided with holes for supplying air outwardly therethrough towards the space between the outer cylindrical cover and said outer peripheral wall, a wick disposed within an auxiliary burner at a point where the air introduced through the holes in said outer cylindrical cover is diverged and having the lower end thereof dipped in the liquid fuel present in said vaporizing plate, said auxiliary burner being composed of side partition walls extending radially from both sides of the air supply holes in said outer cylindrical cover towards said outer peripheral wall and defining an opening in the proximity of said outer peripheral wall and an upper partition wall covering the top ends of said side partition walls, and. an ignition opening formed in said burner pot outer peripheral wall in opposed relation to said wick.

References Cited UNITED STATES PATENTS 2,388,908 11/ 1945 De Lancey. 2,535,923 12/1950 Hill. 2,688,999 9/ 1954 Van Tubergen. 2,822,866 2/1958 Miller et al. 3,017,924 1/ 1962 Jenson.

FREDERICK KETTERER, Primary Examiner.

US. Cl. X.R.