US2817696A - Thermoelectric generator - Google Patents

Description

Dec; 24, 1957 R. D. BECK 'THERMOELECTRIC GENERATOR Filed Sept. 2, 1953 I INVENTOR.

ROLAND o. BECK ATTORNEY TMRMGELECTRIC. GENERATOR Roland 1). Beck, Inglewood, Califi, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application September 2, 1953, Serial No. 373,114

Claims. (Cl. 136-4) This invention relates to thermoelectric generators of the type wherein a thermocouple is heated by a burner having a plurality of ports therein, one for heating the thermocouple and one or more others for igniting a main burner or burners.

While generators of this type are well known in the art, the manufacturers thereof are constantly striving to improve their operation, reduce their costs and to keep to a minimum a number of different models thereof that are required to be usable in the numerous types of burner installations.

It is a primary object of this invention to provide a thermoelectric generator of the above mentioned type wherein a single burner construction and mounting means for an associated thermocouple may be used with either natural gas, liquid petroleum gas or manufactured gas by selectively using one of three difierent spud designs.

Another object of the invention is to provide a power generator which quickly reduces power output upon pressure drop, is of inexpensive construction, yet reliable in operation, and is usable in various burner installations.

Still another object of the invention is to provide a pilot burner having a plurality of flame supporting ports which gives superior flame stability, flame intensity, flame carry over and draft resistance and which eliminates flashback and reduces the tendency of a flame to lift from the burner, over prior art burners.

Another object of the invention is to provide a spud construction which allows for considerable manufacturing tolerances.

Other objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying drawing wherein:

Figure 1 is an elevational view of the thermoelectric generator with portions thereof broken away;

Figure 2 is a cross-sectional view of the generator taken along the line 2-2 of Figure 1;

Figure 3 is a plan view of a modification of the spud of Figure 1;

Figure 4 is a vertical sectional view of the spud Figure 3;

Figure 5 is a plan view of a second modification of the spud of Figure 1;

Figure 6 is a vertical sectional view of the spud of Figure 5;

Figure 7 is a plan view of the burner tip, with portions thereof broken away; and

Figure 8 is a view of a modification of the burner tip of Figure 1.

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As can best be seen in Figure 1 of the drawing, the thermoelectric generator consists of a mounting frame 11 of U-shaped construction in cross section with an end extension 11a bent at right angles thereto to substantially close one end of the U or channel-shaped frame, a bracket member 12,secured to the frame 11 by rivets 13 or by any other suitable means, and a burner body or tube 14 extending through an opening in the top leg of the frame 11 and brazed thereto at 15. Pairs of mounting holes 16, 17 and 18 are provided in the main body portion of the frame 11, extension 11a of the frame, and the bracket 12, respectively. Bolts (not shown) extending through the holes, selectively, enable the generator unit to be mounted on practically all types of burner installations.

The burner body or tube 14 has an outwardly flared portion 19 that is spaced from a lower leg of the frame 11 and from the bridging portion of the frame 11, and can best be seen in Figure 2 of the drawing. This provides an inlet for both gas and air that will pass upwardly through the burner tube. Welded or otherwise secured to the burner tube at the upper end thereof, is a burner tip generally designated by the reference numeral 20. The tip consists of an inverted generally cup-shaped member 21 that extends downwardly over the upper end of the burner tube 14 so that the bottom of the member is spaced only a portion of the depth of the member from the upper end of the burner tube, for a purpose to be described hereinafter. The cup-shaped member has a plurality of large openings 22, 23 and 24 connected by a horizontally extending slot 25. The slot 25 supports a runner flame between the openings 22, 23 and 24 for igniting and reigniting purposes. The member 21 has an outwardly extending annular flange 21a and welded or otherwise secured to the burner tube.

Also secured by welding or other means to the outer sur- 1 face of the closed end of the member 21, is a draft shield 27 that extends horizontally beyond the side walls of the cup-shaped member 21 entirely around the periphery thereof except over the opening 22, the opening which is to support a flame for heating a thermocouple unit,

frame 11 is a spud 29 having a stepped bore extending axially therethrough. The bore consists of a wide threaded inlet portion 30, an intermediate portion 31, and upper outlet portion 32 which is about -one and onehalf times as long as its diameter which is approximately 0.120 inch wide. An inverted cup-shaped orifice member 33 is secured in the intermediate portion 31 by a pressed fit against a shoulder provided by the junction of the portions 32 and 31. The overall length of the spud 29 is .750 of an inch and an orifice 34 in the member 33, coaxial with the bore through the spud, is .016 of an inch. It was discovered that the distance between the orifice 34- and the upper end of the bore 32 is critical and was between 0.170 of an inch to 0.220 of an inch. The upper end of the spud extends only a short distance into the flared end 19 of the burner body 14. The orifice 34 meters the gas flow to the burner while the bore 32 provides the right amount of flow spoilage" to reduce the asperating effect of the gas flowing from the spud into the burner. This reduces the amount of primary air that would otherwise be drawn into the burner through the annular passage formed between the upper end of the spud 29 and the flared lower end 19 of the burner, if the orifice member were at the upper end of the bore 32.

A thermocouple 35 of the concentric thermocouple elements and concentric lead type,-well known in the art, extends slidably through a small diameter hole 36 in the upper arm of the frame 11 and through a larger diameter, threaded hole 37 in the lower arm of the frame 11 and is secured in the frame 11 by means of an externally threaded sleeve bolt 38 screw threaded in the opening 37 and bearing against an annular rib 39 on the thermocouple. A similar annular rib 39 on the thermocouple bears against the inner surface of the upper arm of the frame 11 so as to rigidly clamp thermocouple 35 in the frame 11, with the upper end of the thermocouple positioned to be heated by a flame from the opening 22 in the pilot burner tip.

The thermoelectric generator described above is adapted to control a safety device for a main burner, which is also to be ignited by one or more of the pilot burner openings 23 and 24, by connecting the concentric leads of thermocuples to said control and the spud 29 to a source of fuel supply for the main burner. The spud illustrated in Figure l of the drawing is particularly adapted for burning natural gas while the spuds in Figures 3 and 4 and Figures 5 and 6 are particularly suitable for burning liquid petroleum gas and manufactured gas, respectively.

The modification shown in Figures 3 and 4 has an overall spud length of .828 of an inch. It will be noted however that the cup-shaped orifice member 33a of this modification, while being of the same size and shape as that of 33 in the modification of Figure 1, has an orifice 34a of .010 of an inch in diameter and fits externally over a reduced diameter extension 40 of the spud with a pressed fit.

It will be noted that when the spud 29a is substituted for the spud 29, the upper end of the spud 29a will extend further into the flared opening 19 of the burner body and the orifice 34a will be right at the upper end of the spud so that the gas issuing from the orifice 34a will be at its highest velocity and will produce a much greater asperating effect than spud 29, to induce the flow of a greater ratio of primary air than would be induced by the spud 29 with the same sized orifice. This is necessary to provide the proper ratio of air to gas for this type of gas, namely, liquid petroleum gas.

A modification of Figures 5 and 6 is generally similar to that of Figures 3 and 4, in that the orifice member 34b is secured over an extension 3312 of the spud 29b with a pressed fit. However, the orifice 34b in this modification has a diameter of .0225 of an inch and the overall length of this spud is .947 of an inch. This spud, which is used to burn manufactured gas, has its orifice member 34b extending even further into the burner 14 than the modification of Figures 3 and 4 to the extent that the top of member 33b is above the flared portion 19. Due to this arrangement a smaller amount of air will be asperated, due to the throttling of the air passage in burner tube 14 by the member 33b, than that of Figures 3- and 4. This arrangement also allows for manufacturing tolerances due to the fact that extent of projections of the member 33b into the tube 14 is.- not critical.

From the above description of the invention, it will be noted that a single burner and thermocouple assembly may be used for all types of burner installations, regardless of the above mentioned type of gas being burned therein, bymerely selectively using any one of three dif ferentspud constructions. arrangement is; made;

possible due to the fact that the novel spud construction of Figure 1 for the burning of natural gas enables a generally similar external spud construction to be used for burning liquid petroleum and manufactured gases. The problem of supplying just the right amount of air for the amount of gas that has to be used in the spud construction of Figure l, and still be usable in the same burner and thermocouple assembly that can be used for burning liquid petroleum and manufactured gases, has been solved by the new spud design of Figure 1. Also, the burner tip 20 has a novel construction which also aids the overall combination to operate with substantially all types of gases, in that a fuel mixture from the burner tube 14 maintains its velocity through the burner tip to prevent flashback and generally improves the quality of the flame.

With the generator installed on a main burner and with the thermocouple connected to a safety pilot, a flame supported at the opening 22 in the burner tip will bend upwardly and disengage from thermocouple 35 when an unsafe burner-operating low pressure occurs in the supply line. This is due to the fact that the draft shield 27, that improves the draft resistance of the generator as a whole, does not extend over the flame that heats the thermocouple. This construction enables a quick safety shutdown of the main burner resulting from a quick deenergization of the safety pilot when the unsafe low pressure occurs. It'is thus seen that the novel tip and spud constructions of Figure 1 of the drawing cooperate to enable the thermoelectric generator disclosed herein to be selectively adapted for use in substantially all burner installat ions, regardless of the type of gas burned therein.

The modification of Figure 8 is the same as the tip of Figure I as far as operation of the burner is concerned but diflers therefrom in structure. It will be noted that the bottom 26a of the burner tip is inwardly flared at its central opening and rests in an annular groove at the upper end of the burner tube 14a to which it is brazed.

While modifications of the invention may be made by those skilled in the art without departing from the spirit thereof, it is to beun'derstood that the scope of the invention is to be determined solely by the appended claims.

I claim as my invention:

1. In a thermoelectric generator, having a thermocouple unit and a pilot burner for heating a portion of said unit, the combination comprising a burner tube, a

flange around said tube and spaced inwardly from an end thereof, an inverted dish-shaped cap secured to the flange on said burner tube, a plurality of ports in the side walls of said cap, and a shield on said cap extending laterally therefrom over all of said ports except one, said one port being arranged to direct a flame onto said thermocouple unit.

2. In a thermoelectric generator, having a thermocouple unit and a pilot burner for heating a portion of said unit, the combination comprising a burner tube, a flange around said tube and spaced inwardly from an end thereof, an inverted dish-shaped cap having a flange thereon secured to the flange on said burner tube, a plurality of ports in the side walls of" said cap, said ports being connected by slots in said side walls, and a shield on said cap extending laterally therefrom over all of said slots and all of said ports except one, said one port being arranged to direct a flame onto said thermocouple unit.

3. A pilot burner comprising a burner tube, a flange around said tubeand spaced inwardly from an end thereof, an inverted dish-shaped cap secured to the flange on said burner'tube, a plurality of ports in the side walls of said cap, and a shield on said cap extending laterally therefrom over all of said ports except one, said one port being arranged to direct a flame onto an object to be heated thereby.

4. A pilot burner comprising a burner tube, a burner tip, thereon having: an annular flange around its inner end and spaced inwardly from the outer end of said tip, a

plurality of ports in the side walls of said tip, and a shield extending from the outer end of said tip radially outwardly over all but one of said ports.

5. The combination comprising a burner tube, a burner tip thereon having an annular flange around its inner end and spaced inwardly from the outer end of said tip, a plurality of ports in the side walls of said tip, a'shield extending from the outer end of said tip radially outwardly over all but one of said ports, and flame responsive means positioned with respect to said tip as to be heated by a 10 flame from said one port.

References Cited in the file of this patent UNITED STATES PATENTS Kreiger et al May 17, 1898 Ludlow Aug. 15, 1916 Brown Jan. 15, 1918 Guelson Aug. 8, 1944 Weber et a1. Sept. 16, 1952 James Oct. 28, 1952 Paille Apr. 28, 1953 Flagg Jan. 5, 1954 FOREIGN PATENTS France July 29, 1929 France Feb. 16, 1931

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