US3802414A

US3802414A - Agricultural heating devices

Info

Publication number: US3802414A
Application number: US00309921A
Authority: US
Inventors: C Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-05-13
Filing date: 1972-11-27
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09

Abstract

A natural-draft space heater, having a conventional fuel jet which produces a hollow fuel cone when fed with pressurized fuel oil or compressed gas. The jet is spaced below a base plate having a central hole therethrough and is disposed centrally within the hole with the axis of the fuel cone perpendicular to the base plate. The heater also comprises an upright chimney, having a preferred height of 24 inches, which is disposed on the base plate, and a dispersal plate, of the same size as the central hole, spaced thereabove, aligned therewith, and spaced therefrom so that it intercepts the tulip-shaped hollow cone to produce a wet ring (before ignition) about 1/8 inch to 1/16 inch in thickness adjacent to its circular edge. The preferred diameter of the dispersal plate is about 3 1/2 inches, and the preferred interplate spacing is about 3 inches. The intercepted cone is reflected outwardly and downwardly and may be ignited with a 6-volt ignition device attached to the base plate. After ignition, the deflected flame extends radially from the circular edge but does not exist between the orifice and the circular edge. With fuel oil at 70 psig, the flame is about 4 inches long; with pressurized gas at 0.5 psig, the flame is about 3 inches long, 0.5 gallons per hour of each fuel being burned at these conditions. Tested particulate emissions were 0.2 grams per minute for diesel fuel and 0.005 grams per minute for propane gas at these conditions.

Description

United States Patent [1 91 Lee [451 Apr. 9, 1974 AGRICULTURAL HEATING DEVICES [76] Inventor: Curtis John Lee, Po. Box 127,

Wimauma, Fla.

[22] Filed: Nov. 27, 1972 [21] Appl. No.: 309,921

Related US. Application Data [63] Continuation-impart of Ser. Nov 143,161, May [3.

l97l, abandoned.

Primary Examiner-William E. Wayner Assistant Examiner-William E. Tapolcai,..lr. Attorney, Agent, or FirmLowe, King & Price 57 4 ABSTRACT A natural-draft space heater, having a conventional fuel jet which produces a hollow fuel cone when fed with pressurized fuel oil or compressed gas. The jet is spaced below a base plate having a central hole therethrough and is disposed centrally within the hole with the axis of the fuel cone perpendicular to the base plate. The heater also comprises an upright chimney, having a preferred height of 24 inches, which is disposed on the base plate, and a dispersal plate. of the same size as the central hole, spaced thereabove, aligned therewith, and spaced therefrom so that it intercepts the tulip-shaped hollow cone to produce a wet ring (before ignition) about Va inch to ill 6 inch in thickness adjacent to its circular edge. The preferred diameter of the dispersal plate is about 3% inches, and the preferred interplate spacing is about 3 inches. The intercepted cone is reflected outwardly and downwardly and may be ignited with a 6-volt ignition device attached to the base plate. After ignition, the deflected flame extends radially from the circular edge but does not exist between the orifice and the circular edge. With fuel oil at 70 psig, the flame is about 4 inches long; with pressurized gas at 0.5 psig, the flame is about 3 inches long, 0.5 gallons per hour of each fuel being burned at these conditions. Tested particulate emissions were 0.2 grams per minute for diesel fuel and 0.005 grams per minute for propane gas at these conditions.

10 Claims, 12 Drawing Figures 1 AGRICULTURAL HEATING DEVICES CROSS-REFERENCES TO RELATED APPLICATIONS The present application is a continuation-in-part of co-pending application Ser. No. 143,161, filed May 13, 1971, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fuel-burning devices and particularly relates to radiation-convection heaters. It especially relates to space heaters of the natural-draft or blowerless type which operate on pressurized fuels and are intended forraisingthe temperature of the air over large areas during temporary frost conditions.

Fuel-burning devices which occupy a minimum of space are useful in stoves, ovens, heaters, and the like, and space heaters having versatility, simplicity, and

economy of fuel consumption are widely useful, particoils, rubber, and the like), and in recent years bymech'anical delivery of combustibles to the area of need for burning in specialized space heating deviceswhich generally produce considerable visible pollution of the environment.

2. Review of the'Prior Art Many ingenious devices have been developed for burning of such mechanically delivered combustibles. For example, U.S. Pat. No. 3,409,000 of Brader et al. describes a heater having a flame-constraining heatradiant shroud or chimney which is closed at both ends exceptfor central holes therein, a specially "designed oil-mist generating nozzle being disposed inthe lower hole and numerous small air inlet openings being in the side walls of the shroud so that the entire volume of the shroud is filled with flames 'upon ignition of the oil mist.

U.S. Pat. No. 3,502,066 of l-lurd also describes a blowerless natural-draft heater which uses a vertically disposed cylindrical chimney having a closed bottom through the inlet hole and against a horizontally disposed baffle disposed thereabove.

Although these devices have greatly facilitated base heating of industrial construction areas, orchards, citrus groves, truck croplands, and the like, they are subject to numerous disadvantages. One widely used heater, for example, has a small baffle plate over and around which the fuel squirts so that it seems to be about 50 percent effective. Anothegpopular sp ice fi'eatfisifig, heavy, and expensive, burns 2.5 gallons per hour of fuel at 200 psig, and produces a big flame which seems to climb high in the sky yet requires 35 heaters per acre to protect a central Florida citrus grove where two frosts per year can be expected. Using another space heater, 60 heaters per acre are 'required in the same area.

Furthermore, most commonly used space heaters of the pressurized-fuel type require a minimum of 125 psig fuel pressure and consequently incur higher piping costs because polyvinyl chloride pipe comes in an inexpensive weight for 0-100 psig and an expensive weight for over psig. This heavier weight pipe is also harder to handle, more difficult to seal against leaks, and onerous to move to other locations after burying in the ground. A S-horsepower motor is also necessary to supply the same quantity of oil at psig fuel pressure as a 3-horsepower motor supplies at 70 psig through pipe of equal size. Each heater in the prior art additionally requires a stainless-steel clamp for every connection of PVC pipe to PVC tubing and of PVC tubing to a heater fuel inlet pipe.

When a citrus grove must be protected against an incoming cold wave, space heaters are usually concentrated along the first two rows of trees on the windward side of the grove, and others are dispersed therebehind. Attendants range the grove during the night, checking for heaters that have gone out and watching for overturned heaters that could cause fires.

The large, heavy, natural-draft space heaters now available additionally have no storage means for minimizing storage space requirements during the summer months. Although many have means for flattening or stacking of cylindrical shapes, none are satisfactory because of metal-to-metal contact under pressure, creating corrosion and freezing. Consequently, they must be left in place during the entire year while exposed to the weather or' must be gathered and stored in a relatively large storage facility.

As a further disadvantage of present-day naturaldraft heaters, their large flames and high fuel consumption create an ever-present fire hazard whenever high winds overturn a heater or a delay occurs in igniting the heaters after admitting the high-pressure fuels thereto. The high fuel pressure, large flames, and heated structure prevent the flame from being extinguished if the heater is knocked over, and because of the high fuel pressure and large output of fuel, large quantities of unburned fuel can quickly accumulate on the ground before ignition of the fuel. A fire under such conditions among the dry winter cover of an orchard or citrus grove can result in losing many of the bearing trees and must be avoided at all costs.

An increasingly important handicap to natural-draft heaters now on the market, in view of the recent ecological furor, is the quantity of visible smoke and flame that'is emitted from each heater because of incomplete combustion therein. A grove that is located in a state having strict enforcement of pollution regulations consequently must attempt to use a minimum of fuel and obtain complete combustion thereof.

Yet the fruit has its own imperative demands. For example, oranges freeze at 27 F. if exposed for a sufficiently long time. At 25 F., 6 hours is enough for the cold to destroy the fruit, but at 26 F., the same amount of time is enough for thecold to destroy bark of bearing trees; obviously loss of the trees is far more serious. Regardless of the pollution which may result, therefore, the manager of a citrus grove must somehow provide at least a minimum of an 8 F. rise in temperature if the cold wave temperature is expected to drop to 19 F.

These disadvantages could clearly be overcome if extremely efficient burning of relatively low-pressure fuel could be provided in a simple, inexpensive, natural-draft heater having a storage-space economizing means and producing no outwardly visible flame or signiflcant atmospheric pollution.

SUMMARY OF THE INVENTION The object of this invention is to provide a naturaldraft fuel burning means that efficiently consumes relatively low-pressure fuel and produces a small, radially attenuated flame.

An accompanying object is to provide a natural-draft fuel having means and method for efficient space heating while creating negligible particulate emission.

Another object is to provide a natural-draft space heater which utilizes fuels at pressures below 100 psig.

An additional object is to provide a natural-draft space heater which efficiently consumes relatively small quantities of pressurized fuels and emits negligible quantities of particulate matter.

A further object is to provide a natural-draft space heater which lacks fire-starting characteristics because of its small, radially emitted flames, relatively cool heater structure, and relatively small fuel consumption.

Still another object is to provide a natural-draft space heater having a storage-space economizing means.

In satisfaction of these objects and in accordance with the spirit of this invention, a natural-draft fuel burning means is provided herein which includes a base plate having a central hole therethrough; a dispersal plate of the same size and shape as the central hole which is aligned with and spaced therefrom; a fuel jet to receive pressurized fuel and emit a hollow fuel cone which is coaxially aligned with the dispersal plate and the central hole and is so spaced from the dispersal plate that the hollow fuel cone, without contacting the base plate, strikes the dispersal plate in a ring which is adjacent to the circular edge thereof; and a barrier means which prevents suction air from making a sidewise approach to the dispersal plate.

In further satisfaction of these objects, a natural-draftfuel burning space heater is provided herein that includes this natural-draft fuel burning means and, as the barrier means thereof, an interchangeably ended, elongated chimney, which has means for disassembly and loose-fltting storage thereof as a storage-space economizing means that eliminates metallic corrosion.

This fuel burning means operates by radial attenuation of its flames so that an open-buming flame is greatly shortened in length and attendant black smoke emission is substantially eliminated. It does so by utilizing the concept of intercepting and deflecting a thin, hollow, vertically disposed, tulip-shaped fuel cone with a horizontally disposed baffle plate so that the fuel creates a wet ring of pre-ignition fuel adjacent to its circular edge and approximately l/l6 to inch inwardly thereof. The pre-ignition fuel is thereby dispersed and reflected downwardly toward a base plate and radially outwardly. The base plate is disposed in parallel to the dispersal plate and perpendicularly to the fuel cone.

When deflected fuel is ignited, as can be done with a match or preferably with an electrical igniter attached to the base plate, incoming air rushes diagonally upwardly toward the dispersal plate and radially outwardly toward its circular edge from a central hole in the base plate which is of the same size and shape as the dispersal plate and is aligned therewith. On striking the plate-deflected and ignited fuel while moving diagonally from the central hole to the circular edge, the air further disperses and mixes with the fuel, urges it radially outwardly and away from the base plate, and causes the resulting flame to mix with an excess of air and become rapidly attenuated outwardly so that complete combustion occurs before the flame is cooled below its flash point by striking the heater structure.

No flame exists between the exit orifice of the fuel jet and the circular edge of the dispersal plate.

By a design bringing 200 percent excess air while using a chimney so short as to be essentially a sidebarrier means, the natural-draft space heater of this invention burns the available fuel very rapidly and completely while diluting the combustion gases so that only the chimney portion of the heater structure becomes hot. The base of the heater is cool enough that it can be picked up with bare hands and held for an appreciable time while it is operating.

However, the size of the central hole and the length of the chimney are inter-related to a limited extent because, as in all natural-draft burning devices, the chimney acts to create a differential air pressure between the two sides of the base plate. Consequently, a sidewise barrier to air movement toward the dispersal plate in combustion with a pressurizing or vacuumizing means can be substituted for the chimney.

If knocked over, the fuel jet is readily disengaged from the base plate. The hollow fuel cone is then extinguished so that fuel is merely wasted without causing fire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of the naturaldraft space heater of this invention.

FIG. 2 is a perspective view of the slide fastener used for the chimney.

FIG. 3 is an inset view of a slide fastener holding the backturned ends of sheet metal plate and thereby forming the chimney.

FIG. 4 is a perspective view of a plurality of metal sheets used for the chimney to illustrate stacking thereof.

FIG. 5 is a perspective view of a dispersal plate.

FIG. 6 is a persepctive view of the dispersal plate supporting means.

FIG. 7 is a perspective view of the fuel jet support means.

FIG. 8 is a perspective view of the igniter cover which is attached to the base plate.

FIG. 9 is a perspective view of the igniter which flts within the igniter cover of FIG. 8.

FIG. 10 is a side elevation view of the igniter shown in FIG. 9.

FIG. 11 is an idealized partial sectional view of the dispersal plate, support means, base plate, fuel jet support means, fuel jet, and fuel inlet pipe for a liquid fuel, such as diesel fuel.

FIG. 12 is an idealized sectional view, similar to FIG. 11, which shows the fuel jet and inlet pipe for a pressurized gas, such as propane.

DESCRIPTION OF THE PREFERRED EMBODIMENT The natural-draft space heater shown in the drawings comprises a base plate 4 having a central hole with sides 18 therein, a collar 3 attached thereto in annular relationship to the central hole on the upper or flame side thereof and functioning as a chimney alignment means, a dispersal plate 5, a U-shaped fuel jet support means 9 which is attached to the base plate 4 on the opposite side to the collar 3 (herein designated the fuel side thereof), a fuel jet 7 which is attached to the fuel jet support means 9 in coaxial alignment with the central hole and with the dispersal plate 5, and a chimney 1 having a slide fastener 2 for formation of a cylinder from a bendable metal plate having backturned edges 15. The central hole in the base plate 4 has sides 18. The dispersal plate 5 is disposed in parallel to the base plate 4, has a circular edge 19, and is annularly aligned therewith.

Fuel jet support member 9 has a square hole therein through which either of the fuel jets 7b, 70 may be inserted. They are commercially available units. The fuel jet 7b is a fuel burner nozzle, identified as 0.75 gallons-85 hollow cone for diesel fuel, which sprays 0.5 gallons of atomized fuel per hour. The fuel jet 'Zc is a petroleum gas nozzle with a 1/64-inch orifice which sprays the vaporized gas obtained from 0.5 gallons of compressed fuel per hour. Either fuel jet 7b, 7c is screwed into the square, elbow-shaped nozzle adapter 8, as is clearly shown in FIGS. 11 and 12, which is a standard pipe elbow having a bastard thread for adaptation to the fuel jet 7b, except that a thin support slot 21 is milled into the square sides whereby the adapter 8, having the inlet pipe screwed thereinto, can be fitted upwardly into the square hole up to the slot and then turned about A of a turn so that the inlet pipe 10 is slipped into the base slot having edges 16in one of the downturned corners 17 of the base plate 4.

The slightest tipping movement of this space heater, such as overturning thereof by wind, causes rotational movement of the inlet pipe 10 out of the base slot so that the elbow adaptor 8 falls out of the square hole in the fuel jet support member 9. When this happens, the flame is extinguished because in the open air the hollow gas cone cannot be ignited and the oil cone will not bring any flame with it when detached from the base while burning at 50 to 85 psig. The support slot 21 thus operates as a safety release means.

The insulator 12 is a molded ceramic device having a pair of electrodes 14 which are connected to a 6-volt source and a nichrome heating wire 13 which becomes red hot when a 6-volt current is sent therethrough. Even though the nichrome heating wire 13 is beneath the cover 11, it easily ignites deflected fuel from the dispersal plate 5. However, after ignition and while air is rushing diagonally from the central hole toward the circular edge 19 and re-deflecting thedeflected fuel into radially extending flames, the insulator 12 is not subject to direct heat except for radiation which is intercepted by the top of the cover 11. Consequently, the insulator l2 and nichrome heating wire 13 are useable for long periods of time.

For natural-draft heating, the flame side of the base plate 4 is uppermost, and the fuel side thereof is lowermost. However, for use in ovens, for example, wherein the fuel jet support means 9 can be a part of and be attached to a pressurized air supply duct, a plurality of central holes and edge-aligned dispersal plates can be spaced in close proximity and in upside-down position with a communal air barrier for preventing sidewise access of air to the fuel being radially dispersed from the edges of each dispersal plate. Of course, if the air supply duct is at atmospheric pressure, the necessary pressure differential can be achieved by using a slight vacuum within the oven.

At 85 psig fuel pressure, when using a chimney l having a diameter of 12 inches and a height of 24 inches, a dispersal plate 5 and a central hole in the base plate 4 of about 3% inches in diameter, a spacing of about 3 inches between the flame side of the base plate 4 and the dispersal plate 5, and a location of exit orifice of the fuel jet 7 at about 5 1 inch below the fuel side of the base plate 4, the radially attenuated flames begin to lick the sides of the chimney 1. If the wet preignition ring is not closely adjacent to the circular edge 19 of the dispersed plate 5, mixing is inadequate and the flame becomes smoky.

At psig for No. 2 diesel fuel, when using the same dimensions for components and the same spacings, the flames are about 4 inches in length; at 0.5 psig for pressurized propane gas, the flames are about 3 inches in length. The exhaust gas is at a temperature of approximately 1,450 E; yet the chimney 1 does not become red hot at any place.

The exit orifice can be disposed from about A inch to about inch below the fuel side of the dispersal plate 5. The chimney 1 can be approximately 16 to 30 inches in length. The fuel jet 7 can be selected to produce a cone varying from about to about Air flow tends to close the cone to a tulip shape after 1 to 1% inches of flow. At 70 psig, the fuel consumption is 0.5 gallons per hour per heater and is sufficient to raise the temperature in a space thereabove by 18 P. if placed at a spacing of 20 feet by 24 feet. Moreover, at pressures of 50-85 psig, this heater does not require a tubing clamp to secure flexible tubing to the inlet pipe 10, nor is a clamp required to attach such tubing to the pipe risers at ground level which are connected to the underground pipe system.

When this heater is operated at a fuel pressure of 50 psig, it will not raise the temperature of a space thereabove by 18 F., when scattered at 90 heaters per acre, but by a considerably lesser temperature. Thus it functions as a frost protector rather than a freeze protector.

When the space heater of this invention is operated at 50-85 psig fuel pressure, the flames do not contact the side of the chimney 1. Within this range of fuel pressure, the flame burns cleanly. However, the flame will start to smoke at inlet pressures above about psig and also at inlet pressure below about 50 psig. Moreover, the fuel will not ignite properly at fuel inlet pressures below 50 psig.

When the downturned corners 17 of the base plate 4 are thrust into soil, the elbow adaptor 8 is generally spaced from the underlying ground-and there is abuncifically, the fuel side of the base plate 4 should be about 2% inches above the ground, but the support member 9 will maintain sufficient distance to operate the heater under unusual circumstances as a spacer means.

In a citrus grove having an average concentration of 30 of these natural-draft space heaters per acre, the surrounding air is readily raised by 8 F. in temperature when 0.5 gal/hr of liquid fuel is consumed at a dieseloil fuel pressure of 70 psig or a gas pressure of 0.5 psig. Moreover, because the radiant temperatures are relatively low, radiant heat seems to move horizontally, about 18 inches above the ground, and apparently climbs upwardly along the trunks of nearby citrus trees into the canopy of branches and leaves where all too often cold air seems to become entrapped and cause damage to or loss of the valuable trees when a grove is heated by relatively high-temperature space heaters that send flames roaring high into the air.

In an outdoor test by an independent testing agency in Florida, it was noted that the plume was barely visible and would waver and waft out of the chimney because of its low velocity and that combustion occurred within the bottom few inches of the chimney. Test methods followed the Florida Standard Sampling Techniques published by the Department of Pollution Control in January, 1971. Flue gas volumes were measured directly, using a pitot tube and a low-range draft gage, plus thermoanemometers, and indirectly using Orsat measurements with percent excess air related to theoretical air.

The result of the two tests were averaged as 0.2 grams per minute with standard (No. 2) diesel fuel and 0.005 grams per minute with propane gas. Calculations from Orsat analyses gave 197 percent excess air.

The method of this invention is clearly dependent upon the differential in air pressure between the fuel side and the flame side of the base plate 4. This fuel pressure can be created by pressurizing an enclosed space on the fuel side of the base plate, by varying the height of the chimney, or by vacuumizing the space on the flame side of the base plate without using a chimney except as a barrier for sidewise air movement.

The semi-flattening storage means of this invention comprises the slide fastener 2 and back-tumed edges of the chimney 1. When the slide fastener 2 is slideably removed from the edges 15, the chimney 1 springs partially into flattened shape. The storage method of this invention comprises: slideably removing the slide fastener 2 from nine chimney units; nesting the nine released chimneys; and inserting the nine nested chimneys l and the nine slide fasteners 2 into a tenth chimney in cylindrical condition for storage, whereby the natural springing of the metal during storage inhibits electrolysis effects and prevents corrosion.

As stated hereinbefore, devices constructed according to the principles of this invention can operate without a closely disposed chimney. For example, a plurality of holes can be symmetrically located in a large base plate having side barrier means and a pressurized space on the fuel side thereof or a vacuumized space on the flame side thereof. Such a plurality of heaters is useful in industrial furnaces, particularly because such heaters occupy very little transverse distance and, by suitable control of differential air pressure, can be used with the base plate in other than a horizontal position.

The beneficial effects of this invention are achieved by radial attenuation of the flames to obtain a greatly shortened flame and by admixture of sufficient excess air that complete combustion is obtained, thereby moderating radiation effects, minimizing convective updrafts, and balancing bottom intake air with chimney discharge air so that a heating effect seems to flow in all directions from each heater, at a height of about 18 inches above the ground, and climb into the foliage when intercepted by tree trunks.

This invention is also useful in cooking devices. For

example, a natural-draft space heater as described hereinbefore was placed in the bottom of a cast aluminum round stove having lava rock as a heating bed therein. After about 3 minutes of heating with this space heater, the rocks became hot enough that steaks thereabove began to drip. The heater was then turned off, and the heat of the stones cooked the steaks uniformly and adequately.

This invention is additionally useful as a camp stove.

It can be modified by substituting a smaller fuel jet connected to a small propane tank, and by using a proportionally smaller central hole and dispersal plate.

Because it will be readily apparent to those skilled in the art that innumerable variations, modifications, applications, and extensions of these embodiments and principles can be made without departing from the spirit and scope of the invention, what is herein defined as such scope and is desired to be protected should be measured, and the invention should be limited, only by the following claims.

What is claimed is:

l. A natural-draft space heater, comprising:

A. a flat base plate having a flame side, a fuel side,

and a central hole therethrough;

B. a collar attached to said base plate in annular relationship to the said central hole and on the flame side of the base plate, and acting as a chimney alignment means;

C. a removable chimney, having open ends, which is disposed with one end perpendicularly adjacent to said flame side of the base plate and aligned by said collar and in surrounding relationship to said central hole; said chimney being formed from a bendable metal plate having backwardly bent edges which are engaged by a C-shaped slide fastener, said chimney being interchangeable end for end and removable for storage;

D. a substantially U-shaped fuel jet support means attached to said base plate on the fuel side thereof;

E. a fuel jet, having a fuel inlet opening for pressurized fuels and an exit orifice capable of ejecting a hollow fuel cone, which is attached to said fuel jet support means and disposed so that said fuel cone is in coaxial alignment with said central hole and does not contact said base plate;

F. a dispersal plate support means; and

G. a circular dispersal plate attached to.said dispersal plate support means which is aligned with and has substantially the same diameter as the diameter of said central hole in said base plate and which is disposed in parallel relation to and spaced from the flame side of the base plate so that said dispersal plate intercepts said hollow fuel cone adjacent to said circular edge; whereby, in operation of said heater, the flame is attenuated outwardly j by the dispersal plate but without a substantial portion of the flame contacting the side of the chimney, and with such substantially complete combustion occurring in the lower portion of the chimney that emission of combustion particulates is substantially eliminated.

2. The natural-draft space heater of claim 1 wherein said dispersal plate is disposed in relation to said exit orifice so that said hollow fuel cone creates a ring of wet fuel adjacent to said circular edge before ignition thereof.

3. The natural-draft space heater of claim 2 wherein said ring of wet fuel extends 1/16 to A of an inch inwardly of said circular edge.

4. The natural-draft space heater of claim 3 wherein said exit orifice is spaced approximately one-fourth to 1% inch away from said fuel side.

5. The natural-draft space heater of claim 4 wherein said dispersal plate is spaced away from said flame side at a distance approximately equalling the diameter of said central hole.

6. The natural-draft space heater of claim 5 wherein:

A. said central hole and said dispersal plate each have diameters of approximately 3% inches;

B. said hollow cone of fuel measures 8095; and

C. said chimney has a diameter of approximately 12 inches and a length of approximately 24 inches.

7. The natural-draft space heater of claim 6 wherein 0.5 gallons of fuel oil are ejected from said orifice per hour at psig fuel pressure and wherein a clean flame having a length of about 4 inches is obtained after ignition of said fuel oil.'

8. The natural-draft space heater of claim 6 wherein said orifice is a l/64-inch orifice which ejects 0.5 gal lons of compressed gaseous fuel per hour at 0.5 psig fuel pressure and wherein a clean flame having a length of about 2 inches is obtained after ignition of said gaseous fuel.

9. The natural-draft space heater of claim 6 wherein said U-shaped plate is thin and has a square hole therethrough, and said fuel jet is attached to an elbow having a square cross-section into which a thin slot is milled, whereby said elbow is rotatably attachable to said U-shaped plate and operates as a safety release means when said space heater is overturned.

10. The natural-draft space heater of claim 1 wherein a spacer means that spaces said fuel side sufficiently far from an underlining support surface that an adequate quantity of combustion air enters said central hole, is formed by bending the comers of said base plate at right angles to said fuel side and away from said flame side.

Claims

1. A natural-draft space heater, comprising: A. a flat base plate having a flame side, a fuel side, and a central hole therethrough; B. a collar attached to said base plate in annular relationship to the said central hole and on the flame side of the base plate, and acting as a chimney alignment means; C. a removable chimney, having open ends, which is disposed with one end perpendicularly adjacent to said flame side of the base plate and aligned by saiD collar and in surrounding relationship to said central hole; said chimney being formed from a bendable metal plate having backwardly bent edges which are engaged by a C-shaped slide fastener, said chimney being interchangeable end for end and removable for storage; D. a substantially U-shaped fuel jet support means attached to said base plate on the fuel side thereof; E. a fuel jet, having a fuel inlet opening for pressurized fuels and an exit orifice capable of ejecting a hollow fuel cone, which is attached to said fuel jet support means and disposed so that said fuel cone is in coaxial alignment with said central hole and does not contact said base plate; F. a dispersal plate support means; and G. a circular dispersal plate attached to said dispersal plate support means which is aligned with and has substantially the same diameter as the diameter of said central hole in said base plate and which is disposed in parallel relation to and spaced from the flame side of the base plate so that said dispersal plate intercepts said hollow fuel cone adjacent to said circular edge; whereby, in operation of said heater, the flame is attenuated outwardly by the dispersal plate but without a substantial portion of the flame contacting the side of the chimney, and with such substantially complete combustion occurring in the lower portion of the chimney that emission of combustion particulates is substantially eliminated.

3. The natural-draft space heater of claim 2 wherein said ring of wet fuel extends 1/16 to 1/8 of an inch inwardly of said circular edge.

4. The natural-draft space heater of claim 3 wherein said exit orifice is spaced approximately one-fourth to 1/2 inch away from said fuel side.

6. The natural-draft space heater of claim 5 wherein: A. said central hole and said dispersal plate each have diameters of approximately 3 1/2 inches; B. said hollow cone of fuel measures 80*-95*; and C. said chimney has a diameter of approximately 12 inches and a length of approximately 24 inches.

7. The natural-draft space heater of claim 6 wherein 0.5 gallons of fuel oil are ejected from said orifice per hour at 70 psig fuel pressure and wherein a clean flame having a length of about 4 inches is obtained after ignition of said fuel oil.

8. The natural-draft space heater of claim 6 wherein said orifice is a 1/64-inch orifice which ejects 0.5 gallons of compressed gaseous fuel per hour at 0.5 psig fuel pressure and wherein a clean flame having a length of about 2 inches is obtained after ignition of said gaseous fuel.

10. The natural-draft space heater of claim 1 wherein a spacer means that spaces said fuel side sufficiently far from an underlining support surface that an adequate quantity of combustion air enters said central hole, is formed by bending the corners of said base plate at right angles to said fuel side and away from said flame side.