US3033279A - Vaporizer for horizontal vaporizing burner - Google Patents

Description

May 8, 1962 M. D. HUSTON VAPORIZER FOR HORIZONTAL VAPORIZING BURNER Filed May 11, 1959 atnt Patented May 8, 1962 3,033,279 VAPGRIZER FOR HORIZONTAL VAPURIZING BURNER Milton D. Huston, Santa Fe, N. Men, assignor to Controls Company of America, Milwaukee, Wis., a corporation of Delaware Filed May 11, 1959, Ser. No. 812,493 Claims. (Cl. 158-91) My invention relates to an improvement in burners and, particularly, to an improvement in ignition and vaporizing means for burners.

One purpose is to provide an electric ignition and vaporizing assembly for burners which operate on liquid hydrocarbon fuel.

Another purpose is to provide a burner of the type described which will reach the high fire condition of operation with a minimum time lag after ignition.

Another purpose is to provide means for employing stored heat for the initial vaporization of a substantial volume of liquid hydrocarbon at the starting stage.

Another purpose is to provide improved means for supplying air for ignition and for combustion, to a burner of the type herein described.

Still another object is to provide means for supplying a protective curtain or screen of air about a burner pot of the type described which increases the efliciency of the burner and minimizes the heat losses.

Another purpose is to provide an improved ignition and vaporizing assembly for such burners which is eflicient in operation and easily removed for cleaning and repair when necessary.

Another purpose is to provide such an assembly in combination with a so-called horizontal pot type burner.

Other purposes will appear from time to time in the course of the specification and claims.

I illustrate the invention more or less diagrammatically in the accompanying drawings wherein:

FIGURE 1 is a vertical section taken along the axis of the burner;

FIGURE 2 is a partial end elevation of the structure of FIGURE 1, with the vaporizing assembly shown, and the electric ignition element removed; and

FIGURE 3 is a section on the line 33 of FIGURE 1.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings, FIGURE 1 illustrates a horizontal pot type burner which may be applied to any suitable heater, stove, or furnace, not herein shown. The mounting means for mounting the burner on the heater may be widely varied and do not, of themselves, form part of the present invention and, therefore, are not illustrated in detail. It will be understood, however, that the burner assembly of FIGURE 1 may be suitably positioned on or in relation to a heater or stove in such fashion that the tlame from the burner is directed into the heater or stove, or to a suitable heat exchange space or assembly.

With reference to the general organization of the burner, it has at one end an ignition structure, generally indicated at A in FIGURE 1. This ignition structure carries an ignition device which will later be described in detail and which is located in a space in communication with the interior of a vaporizer located generally along the horizontal axis of the spot, but is itself in a relatively cool zone. It will be understood that the fuel to be burned is delivered from a liquid fuel inlet 140 to the interior of the ignition space. The ignition space includes a bottom wall 14a and a dam or weir 14b which forms a puddle of liquid fuel adjacent the below to be described ignition means. Fuel overflows the dam 14b and flows out upon the bottom 12 of the vaporizing device. The liquid fuel is vaporized in the vaporizer, flows outwardly through its top opening into the interior of the pot and burns within the pot.

As will later appear, ignition is started by the flow of liquid fuel through the inlet 140. The details of the control of the liquid fuel do not of themselves form part of the present invention and need not be described herein. It will be understood, however, that means, manual or automatic, may be employed for initiating a flow of liquid fuel to the space back of the dam 14b, when heat is desired.

As will later appear, I provide a heating element or resistance 25 which is normally constantly energized, but which calls for a low output of energy. However, it is eifective to store heat in the adjacent parts of the burner, including the wick 22 and its tubular support 21. The parts are so proportioned that when liquid fuel begins to flow and forms a shallow puddle back of the weir 14b, the stored heat vaporizes the liquid hydrocarbon, and the resistance 25 ignites it. This ignition system will later be described in greater detail. It will be understood, however, that within a very short space of time the burner can reach the high fire stage, and the lag between the instant of ignition and high fire can practically be made as short as 45 seconds or less.

The burner structure of FIGURE 1 includes an outer housing which may be cylindrical or generally cylindrical and is indicated at 1. Within it are a plurality of spacers which I indicate at M, in the form of strips which may be welded or otherwise secured to the inner surface of the housing I. Extending from these strips are spacing projections 1b. Within the housing 1 and spaced inwardly therefrom is the wall of the burner proper generally indicated at 2. Positioned between it and the outer housing 1 is an intermediate baflie or shield 8 which is held centered in its desired position, for example, by the projections 1b of the spacer strips 1a. The strips 1a, after the intermediate bafiie or shield 8 has been slipped into the position in which it is shown in FIGURE 1 may be used to hold the assembly together. Thus, for example, ends of the strip as at 1c may be bent into the holding position in which they are shown in FIGURE 1. The sleeve or pot 2 is outwardly flanged at its open end, as at 2a, in opposition to a corresponding inwardly extending flange If of the outer housing. 3 indicates a burner supporting ring having a cylindrical flange 3a extending about the outer edge of the sleeve 1. Any suitable gasket 4 may be employed, and suitable securing members 5, which extend through the flange 2a. Any suitable means for holding the pot parts together in the position in which they are shown in FIGURE 1 may be employed. An outer supporting ring 6 is shown as held against endwise movement to the right by bead 1e but as the details of securing the above described assembly to a suitable heater are not of themselves part of the present invention, they are not herein shown.

The wall of the inner burner sleeve 2 is shown as provided with a plurality of primary air inlet apertures, indicated at 2b. Through these apertures, shown as arranged in a plurality of circumferential rows spaced at various distances from the end of the pot, a primary air supply is admitted. It will be understood that in this type of burner a rich mixture is formed by the evaporation of a liquid hydrocarbon by combustion already going on in the burner. This rich mixture is then burned by adding to it a suitable supply of secondary air. In the structure herein illustrated the secondary air is shown as admitted by a row of secondary air inlets 20, arranged near the open end of the pot thus formed.

The air supply for the burner may be thought of in connection with flow from an initial circumferential plenum chamber X to which air may be admitted, through an air inlet 7 from a motor driven fan or otherwise. This plenum chamber X extends about a generally cylindrical baffle 16 which is provided with one or more relatively small apertures 16a through which flows the supply of air for the ignition stage of the burner. In order to provide air for the body of the burner and for the primary air inlets 2b and secondary inlets 20 I deliver air about the exterior of the earlier described intermediate battle or shield 8 to a second circumferential plenum chamber indicated at Y. The second chamber surrounds the exterior of the pot wall 2 and communicates directly with the secondary air inlets 2c. The air supply for the primary air inlets 2b flows in an opposite direction in the space between the intermediate shield or baffle 8 and the exterior of the pot wall 2.

Thus, at the high fire stage of combustion, a rich mixture of vaporized hydrocarbon and primary air flows past the secondary air inlets 2c, and combustion takes place at or beyond the secondary air inlets, the flame passing through the central aperture of a suitable flame ring 9 suitably mounted on the supporting ring 3. I may find it advantageous to direct an impinging movement of air toward the secondary air inlets 2c. I illustrate, for example, a deflecting ring 10 with a directing flange 10a in line with supplemental air inlets 2d in the pot side wall or inner sleeve 2.

The pot structure at the opposite end, at the left of FIGURE 1, is completed by a combined end plate and evaporator assembly. The end plate is illustrated at 11 and is shown as having secured to it an evaporator element or trough 12 shown in cross-section in FIGURE 3. Its end is closed as at 12a, but it has an upward opening surrounded by an intermediate Wall 1217 and side walls 120 which extend back from the wall 12b to the rear or closure plate 11. It will be noted that the clearance between the pot and the edges of the side walls 120 increases toward the rear or left end of the pot. The evaporator assembly defines a chamber in part formed by an outward extension 14 from the back plate 11. This extension 14 is shown as having a bottom wall 14a with a limiting ledge 14b which forms a dam for liquid fuel admitted through the aperture 14s by any suitable fuel delivery duct, the end of which is shown at 14d. The top wall of the member 14 is shown as provided with forwardly inclined air inlets 14a which deliver air downwardly and forwardly toward a subsequently described igniter. One or more additional air inlets may be provided, as at 14g, whereby air passes through the rear or back plate 11 and downwardly and forwardly into the vaporizing chamber through the opening surrounded by walls 12b and 12c. The extension 14 of the back plate 11 is provided with an open-ended, upwardly inclined, tubular portion 15 formed to receive the ignition unit below described. The evaporator unit is also surrounded by a shield 16, with one or more air inlet apertures 16a, and the rear or left end of the outer sleeve is closed by the previously mentioned end cap 1a. having a tubular portion 18 surrounding and spaced from the tubular extension 15 of the evaporator assembly or rear plate 11. Any suitable means may be provided for securing the back plate. I illustrate, for example, a clamping ring 19 which is secured to the back plate, for example, by suitable bolts 20, and which grips a suitable bottom flange 22 of the inner sleeve or pot side wall 2. Thus the back plate 11 may be bodily removed from the pot, once the igniter and outer end cap 101 is removed. The removable assembly thus includes the back plate 11, the below described ignition element, and the entire vaporizing chamber. As will later appear, the ignition element or assembly is also independently removable from the vaporizing assembly after the end cap 1d and before the vaporizing assembly are removed from the burner. The parts are so proportioned that the wall 12b of the vaporizing assembly may be withdrawn through the ring 19. The ring 19, in turn, is maintained in position, when the assembly is removed, for example, by a suitable bead 2g. The bolts 20 may be permanently secured to the ring 19 and any suitable nuts 20a employed, which are exteriorly accessible, once the closure 1d has been removed. It will be understood that the fuel supply duct 14d may be connected to any suitable source of liquid fuel supply, not herein shown. It is preferable to form or arrange the duct 14d with some measure of flexibility, to permit the vaporizing assembly to be readily removed from the burner.

In order to ignite the burner I provide a unit which includes the generally cylindrical sleeve 21, at the bottom of which is any suitable wick, generally indicated at 22. The details of the ignition unit do not of themselves form part of the present invention. It is advantageous, however, that some means be provided for igniting the liquid fuel supply to the burner, either electrically or manually.

As an illustration of a practical ignition member I may employ a pair of spaced, electrically conductive pieces 23 and 24 connected to any suitable source of electric power. These conduct electrical energy to any suitable resist ance heating element, which may be in the form of a coil 25. The poles 23 and 24 may be supported by any suitable insulating members, such as 26, 27. The wick element 22 may, for example, be in the form of a spirally wound, stainless steel strip which provides a discharge space between the convolutions of the spiral. Air may be supplied to the interior of the housing or tube 21, for example through a suitable air inlet or inlets 21a. The tube 21 has secured to it a circumferential shield 28 which is shown as fitting loosely about the end edge of the tubular portion 13 of the end cap 1d. Thus air may flow through the space provided; or air may be otherwise admitted through the shield 28.

I find it advantageous to provide a vaporizing assembly which can be bodily and unitarily removed from the burner, without removing the burner from the heater to which it is attached or without removing the constant level fuel supply gage and from which, in turn, the ignition element may also be separately removed.

It will be realized that whereas I have described and illustrated a practical and operative device, nevertheless, many changes may be made in size, shape, number and disposition of parts without departing from the spirit of my invention. I therefore wish my description and drawings to be taken as in a broad sense illustrative or diagrammatic rather than as limiting me to my specific disclosure herein.

The use and operation of the invention are as follows:

I illustrate a known type of burner in which a liquid fuel is vaporized and burned. As above mentioned, I illustrate my invention as applied to a burner in which a rich mixture is first formed by combining a primary or limited air supply with vaporized hydrocarbon, the rich mixture being converted to a final and thinner combustible mixture by the addition of a so-called secondary air supply.

Referring for example to FIGURE 1, which shows the air supply as going first to the circumferential plenum chamber X, that part of the air supply necessary for the initiation of combustion flows through one or more apertures 16a in the ring or baffle 16. Part of this air flows through the aperture 21a or its equivalent into the preliminary or initial combustion space about the normally hot ignition coil or wire 25. More air flows to the space about the exterior of the wick 22, for example through the inlets Me. Additional air may be directed by inlets 14g through the wall 11 and downwardly into the vaporizer structure 12. Additional air is also supplied through the second circumferential plenum chamber Y directly to the secondary air inlets 2c and also, between the burner wall 2 and the baflle 8, to the primary air inlets 2b.

Assume that the burner control is calling for heat. A suitable motor driven fan (if a forced draft is desired) begins to operate through the closing of a suitable motor switch, and air is delivered therefrom to the plenum chamber X and thence through the various passages and inlets above mentioned, both to the ignition space and to the interior of the burner proper.

A primary purpose of the present structure and method is to produce high fire conditions with as little delay as possible. As a matter of practical example, I find it possible to reach the high fire stage in as little as 45 seconds after ignition. This quick operation and rapid actuation is obtained substantially as follows.

With a relatively small input of electric energy the resistance 25 or its equivalent has been giving out heat. It may be left permanently on if desired. Heat is stored in the wick 22 and in the lower end of the wick support or tubular passage 21. Some heat is also stored in adjacent parts of the burner, for example, in the relatively thick side and bottom portions 14 and 14a of the ignition part of the device.

Assume that when heat is called for, a liquid hydrocarbon begins to flow from any suitable source through the inlet 14c. This liquid fuel is dammed by the dam or weir 14b and the result is the quick formation of a relatively shallow pool of liquid fuel. It may for example be as shallow as one-sixteenth of an inch in structure of the type shown in FIGURE 1 in which the burner pot has a diameter of seven inches. I employ the heat stored in the wick and its support and adjacent parts of the burner to vaporize the puddle of liquid hydrocarbon which thus forms. It is important that the parts be so proportioned that this stored heat will be drawn otf at an optimum rate. If the puddle were too deep it would be drawn off quickly in a flash of flame. If it is not deep enough the vaporization of the liquid hydrocarbon proceeds at too slow a rate. I consider it best to so proportion the parts that, upon the initiation of flow of the liquid hydrocarbon there is an almost immediate vaporization of a greater gaseous volume than will be burned about the wick or in the vaporizer. With a proper relation between the stored heat and the initially dammed volume of liquid hydrocarbon, the excess vaporized hydrocarbon flows throughout the interior of the vaporizer 12 and out to its upper opening into the interior of the pot which surrounds it. In effect and within a span of time as short as forty-five seconds I find that the pot proper is filled with vaporized hydrocarbon, and that this hydrocarbon is mixing with primary air flowing to the inlets 2b. This primary mixture is further flowing past and being mixed with air admitted through the secondary air inlets 2a. In other words, within substantially less than a minute after the ignition the burner may be made to burn at high fire conditions.

It should be kept in mind that in my burner and method, what controls ignition is notthe closing of an electric circuit to heat an ignition member. On the contrary, the ignition member may be constantly heated. What controls my ignition is timing of the delivery of a liquid hydrocarbon to an ignition zone where it is vaporized by stored heat and is actually ignited by a hot wire or its equivalent.

I make provision for propagating the ignition throughout the burner immediately following the initial ignition stage. The air supply through 142 provides for a combustible mixture exterior to the wick 22. Additional air inlets 14g direct a supply of air downwardly into the top of the vaporizer 12 and finally, the volume of liquid hydrocarbon vaporized by this rapidly spreading combustion promptly flows out of the vaporizer and through out the interior of the pot and, receiving its primary air through inlets 2b and its secondary air through the inlets 2c, burns at the desired high fire stage. The flame then extends through the aperture in the flame ring 9 and into the combustion space not shown.

In considering specifically the flow of air during the normal operation of the device, air is first supplied through the inlet 7. Any suitable means may be employed for maintaining the desired pressure differential, for example, I may use a motor driven fan or the like.

As indicated generally by X in FIGURE 1 the air is within the left or outer end of the outer housing 1, within the rear closure cap structure, generally indicated as 11, and exterior to the cylindrical sleeve 16. Some of the air flows however through inlets 16a to the space within the sleeve 16, and the rest of the air in the circumferential space or plenum chamber X escapes to the right, referring to the position of the parts of FIGURE 1 and flows about the exterior of the intermediate baffle or sleeve 8. The air thus reaches a circumferential space about the right hand end of the inner housing 2. referring to the position of parts as shown in FIGURE 1. This end space is indicated at Y in FIGURE 1 and communicates directly with the secondary air inlet 20. Primary air is supplied to the inlets 2b in the wall of the sleeve 2 by the flow of air inwardly between the sleeve or bafile 8 and the inner wall 2, this flow being to the left referring to the position of the parts as shown in FIGURE 1. Thus the primary and the secondary art is supplied to the burner proper by air flowing first outwardly along the exterior of the baflle 8 and then inwardly between the balfle 8 and the wall 2.

Thus there is in effect a screen of flowing air flowing about the exterior of the baffle 8 and another screen of air flowing between the interior of the bafile 8 and the wall 2. In effect this insulates the outer Wall or housing 1 and much limits the escape of heat from the burner and protects the exterior of the burner assembly from undue heating, destruction of the pigment, etc. Above all, and far more important than any such supplemental advantage, is the fact that the sleeve or baffle 8 serves to conserve reused heat to prevent heat loss from the burner and to provide a more eflicient and economical operation of the burner.

It is a characteristic of the burner that a relatively small vaporizer must be used, the structure of 12 and following, and in connection with the smaller vaporizer the burner must be operated at a higher temperature. The structure above described enables the burner to operate efliciently with a relatively small vaporizer, without difiiculties and without exterior overheating. If the bafile 8 were removed the efliciency of the operation would be greatly reduced and a vaporizer of the size indicated might actually have substantial difliculty in vaporizing the supply of fuel which normally would have to be fed to it.

It should be noted that the vaporizing and ignition assemblies can each be bodily and quickly withdrawn from the burner. It should be noted, also, that the electric ignition element, while it is in communication with the space of the vaporizer unit, is actually outside of the burner. It is thus possible to remove the ignition element, end cap, and vaporizer or the ignition element alone for inspection and replacement without disturbing the remainder of the burner pot.

In addition, the outer housing 1 and 1d is important because it forms a pressure chamber about the pot proper to insure a greater pressure above the upper end extension 15 of the vaporizer than inside the vaporizer. Thus, noxious vapors and odors, including formaldehyde, that are present in any burner using liquid hydrocarbon fuel are not allowed to escape to atmosphere between the igniter tube 21 and the extension 15.

I claim:

1. In a horizontal pot-type burner and vaporizer assembly, a pot having a plurality of air inlets spaced along its axis and about its circumference and a vaporizer assembly closing one end of the pot and having a chambered fuel receiving portion extending within the pot and generally along its axis, a fuel inlet connected to the assembly at a point exterior to the pot to provide a flow of fuel along the bottom of the assembly, ignition means in- 7 eluding Wicking positioned in a portion of the assembly exterior to the pot, said Wicking being positioned to contact said flow of fuel, and a hot wire adjacent said wicking to heat it, that portion of the assembly extending Within the pot comprising a confined vaporizing zone which is in communication with the pot,

2. The structure of claim 1 further characterized by and including means for delivering air to the space about said hot wire and wicking.

3. The structure of claim 1 further characterized in that the chambered fuel receiving portion includes a housing having closed bottom and side walls and a defined opening at the top, said defined opening being remote from the open end of the pot.

4. The structure of claim 3 further characterized by means for directing air downwardly toward said defined opening.

5. The structure of claim 1 further characterized in that said assembly includes heat storage means adjacent the fuel inlet.

References (Jited in the file of this patent UNITED STATES PATENTS

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