US2936751A - Gas burners - Google Patents

Description

P. M. FORNITI May 17, 1960 GAS BURNERS 3 Sheets-Sheet l Filed Aug. 10, 1956 P. M. FQRNITI May 17, 1960 GAS BURNERS 3 Sheets-Sheet 2 Filed Aug. l0, 1956 ATTORNEYS May 17, 1960 P. M. Foam-rl 2,936,751

GAS BURNERS Filed Aug. 10, 1956 3 Sheets-Sheet 3 O lh G IIN@ IMI H BY y My/77,4%

ATTORNEYS United States Patent C) I GAS BURNERS Philip M. Fomiti, Cleveland, Ohio, assignor to Hupp This invention relates to burners and more particularly to gas burners.

,While the invention is, in certain aspects, of broad utility and application, for kpresent purposes it will be disclosed as applied to improved burners for the generation of infra-red heat of the so-called tlameless type in which combustion of gaseous fuel and air takes place in the outer surface of the burner element.

For maximum eiciency such burners should operate in'substantially still air and Vtheefliciency of such heaters is seriously reduced when the burner surfaces are exposed to currents of moving air. For example, particularly in outdoor installations, gusts of wind blowing against the combustion surface will cause eruptions of llame from the surface, lowering the temperature of the burner surface thereby seriouslyr reducing the rate of emission of radiant energy. Even indoors such burners are often subject to such currents of air which may 'be produced by ventilators, open doors'or other sources.

In lmany cases radiant burners or heaters of this type are provided with a duct leading away from the burner surface to confine and direct the radiant energy. Such a duct, if it is imperforate and leads directly from the burner surface, will provide substantial protection against `air currents. However, experience has shown that the combustion products cannot be satisfactorily evacuated if suchl an imperforate shieldor duct is used particularly in view of the fact that in most cases -the burners are positioned overhead, with the burner surface` can'also adversely aiect the combustion efficiency of burners of this type if they are allowed to'enter the region of the burner adjacent the air intake. While various shields have been proposed in the past to protect the air inlet from' random air currents and Varying wind pressures, nevertheless, no satisfactory solution ofwthis problem has been proposed prior to the present in ven` tion.

Y cessive air currents.

2,936,751 Patented May 17, 1960 Y 2 surfaces and the opposite duct wall comprises an imperforate sheet of material which is transparent to the radiant energy which it is desired to transmit in a given application. The present invention further contemplates the provision of a novel shield assembly surrounding the combustion air intake to protect the latter against ex- The shield and the secondary duct system cooperate in a novel manner to provide a fully windproof burner assembly.

VIt is accordingly a further object of the present invention to provide improved radiant heat burners which may be used outdors and under conditions where previous burners of this type have proved to be unsatisfactory,

It is also an object of the present invention to provide" novel shield assemblies for radiant heat burners which effectively neutralize varying wind pressures vfrom 'all directions and provide substantially constant `pressure at the air inlet so that the combustionair is entrained at a uniform rate for maximum combustion efficiency.

It is a further object of the present invention to provide novel shield assemblies for radiant heat burners which are of simple, durable construction and which Figure 3 lis a transverse section ofthe burner taken along line 3-3 of Figure 1;

Figure 4 is a 4fragmentary section taken along line 4-f4 of Figure 1;v

FigureS is a `section taken alongline 5.--5 of Figure y l and showing details Aof the air intake shield; and

With the foregoing considerations in mind it i'slthe:

principal purpose' and 'object of the present invention toprovide Iimproved radiant heat burners which Aare fully protected against wind currents and which operate with near optimum eiciency even-in high winds."""

.In accomplishing this and other lobjects the invention contemplates the provision of a heatdirecting duct assembly leadingaway from the surfacel'of the burner and a secondary duct system extending transversely across the-primary'fheat directing duct assembly which permits eiective vevacuation of the combustion productsI @and yet fully protects the surfaces of. the burner against wind' currents. In the preferred from of theinvention, 'one Wallvof the secondary duct comprises the radiant-burner Figure 6 is Ia side elevation of the shield assembly shown in Figure 5,

Referring now more particularly to the drawings, the principal components of the burner therein shown are the burner heads 20 and 22, the main heat directing ductl assembly 24 including a duct member 25, the secondary ventilation duct assembly 26 which extends across and forms a part of the duct assembly 24 and the air intake shield assembly 28. The burner heads 20 and 22` are secured by a plurality of bolts 30 to a frame struc-V 4ture 32 which extends around the periphery of the two burnerheads and between the two burner heads. Pref- -erably an attaching bracket 34 is secured to the frameassembly Y32v between the adjacent edges of the two burners. p v l Each of the burner heads 20 and V22 comprises a.

housing 36 which forms a mixing chamber 38 open i ylength of the passages 42 is such that combustion of the fuel-air mixture occurs on the outer surfaces of the burner blocks. 'e

At one end the housing members 36 are provided with integral Yfuel-air inlet sections 44 which are pref.

erably open at their top surfaces. An opening is provided in therear wall of each of the sections 44 to accommodate a gas nozzle 45l which is connected by 'suitable piping to a source of gas under pressure and directs a jet` ofgas into the chamber'SS entraining air which enters the section 44 through its open top surface;

In operationa mixture of gas and primary air -is forced through the passages 42 and burned in or`on vtlielciuter 'l1 surface of the blocks 40. Almost immediately'after Athe' operation of the burners is initiated the lower surfaces of .the ceramic blocks are heated to incandescenceV and emit radiant energy in the infra-red spectrum which is directed to -the area to be heated bythe duct assembly 24. It is a characteristic of burners of this type that the substantially flarneless combustion appearing on or in the surface of the ceramic blocks is effectedrwithout secondary air supplied to the surface of the ceramic blocks. In fact it has been discovered in practice that random currents of secondary air supplied to the lower surface of the ceramic blocks may actually interfere with the combustion process and lower the temperature of the surface of the blocks thus materially reducing the efficiency of the burner. In recognition of this fact the present invention provides the duct assembly 26 which extends across the duct assembly 24 and which isA effective to permit satisfactory evacuation of the products of combustion from the area at the lower surface of the ceramic blocks 40 while preventing the impingement of excess air currents on the combustion surfaces.

Ihe rear wall and two side walls of the duct assembly 26 are formed by a sheet metal U-shaped channel 46 (Figure 3), the rear wall portion 48 being notched at 50 and 52 adjacent its opposite ends to permit the sidewall portions 54 and 56 to be bent at right angles to the rear wall portion 48. An evacuation flue assembly 58 comprising a duct of rectangular section forms the front Wall of the duct assembly 216 and is welded or otherwise suitably secured to the free ends of the duct end side walls 5.4 and 56. As shown particularly in- Figure l the ue assembly 58 is bent upwardly to promote the flow ofthe hot combustion products out of the .duct assembly 26 by convection. Y

Secured to the upper end of the flue assembly 58 by two spaced pairs ofrstraps 60 is an arcuate Vshieldr62. The `shield permits substantially unrestricted ilow of combustion products out of the ilue assembly while preventing or substantially restricting the inward flow of air through the flue assembly and the entrance of rain or snow. The open end of the ueassembly 58 is further protected against the entry of `air currents byshields 64 and 66 which are suitably secured to the top and bottom walls of the ue assembly 58 and project outwardly therefrom to points opposite the lateral edges of the shield 62. As best shown -in Figure 3 all of the shield members 62, 64, and 66 extend the full length of the flue assembly 58 to provide maximum protection.

As best shown in Figure 4 a plurality of openings 68 are provided in the rear wall 48 of the duct assembly 26 to promote ventilation of the area around the burner elements by convection. from air currents by a sheet metal shieldl assembly 70 which extends the full length of the rear wall 48 of .the duct assembly 26 and is secured along its lower edge to the duct member 25 and at'its upper edge is bolted orV yotherwise detachably secured to a pair of straps 71 and 72 preferably welded to the wall 48. The opposite ends of the shield 70 are spaced a substantial Vdistance outwardly of the shield assembly 28. Accordingly, if reverse low occurs within the duct assembly 26 due to the positioning of the burnerrassembly, or other factors the products of combustion will be vented outwardly of the ends of the shield assembly 28 so as to avoid Vcontamination of the incoming primary air flowing into the burner. ItV will also be noted that under normal conditions all of the combustion products will be vented from the outlet of the llue assembly 58 so that there is no possibility of contamination of the primary air with combustion products. A

The duct assembly 26 is completed by an access plate 76y pivotally mounted on the side Wall 56 as at 78 over an access opening 80 to permit manual ignition of the burner. Where automatic ignition of the unit is provided for, the igniter assembly is preferably mounted in the opening 80.

These openings are protected It is an important feature of the invention that the duct assembly 26 is substantially entirely enclosed. In accordancewith the present invention the bottom wall of the duct assembly is formed by a sheet of'glass 82 which shields the combustion surface from air movements within the heat duct member 25. The glass panel 82 is preferably held in place by a plurality of clips 84 suitably spaced around the periphery of the panel. f Ordinary lead borax glass, such as window glass, is quite transparent to infra-red radiation in the visible spectrum where wave lengths are less than `one micron but becomes increasingly translucent to infrared radiation in the longer wave lengths. In practice it has been found that most applications require the emission and transmission of infra-red radiation in wave lengths of approximately 3 microns to more than 8 microns. Accordingly ordinary window glass cannot be used in the burner without serious loss of elliciency. ln accordance with the invention a silicon glass sold under the trade name of Vycor is utilized for the panel 82 since it has been found that this glass permits substantially complete transmission of radiant energy in the desired wave lengths.

The primary heat duct member 25, secondary venti Vlation duct assembly 26 and the burner assemblies are preferably secured together by a plurality of bolt and nut assemblies 86 located at points suitably spaced around the periphery of the assemblies. Substantial sealing of the duct 26 is effected by asbestos gaskets 88 and 90 which are clamped respectively between the upper' surface of `the Vduct assembly 26 and the frame structure 32 and between the lower surface of the duct assembly 26 and the flanged upper end of the heat directing duct member 2S.

To provide a completely windproof burner assembly the inlet area through ywhich the primary combustion air enters the burner must be fully protected against winds approaching the burner from all direction to provide a constant pressure in the area surrounding the air inlet to thereby assure'entrainment of combustion air by the gas nozzles 45 at a substantially uniform rate.

Shield assembly 28 which has been provided for this purpose will now be described in detail with particular reference to Figures V5 and 6. As there shown shield 28' is preferably disposed substantially directly over the rear` edge of the air inlet assemblies 44 when the shield assembly is -installed in the burner. Spaced from and substantially parallel to the free edge of the shield 94 are a pair of bales 96 and 98 welded to the cover plate 92.

A second pair of baffles 100 and 102 are also welded to the interior of the cover plate 92 and extend late-rally of the cover plate from the forward edge thereof to a point, approximately at the` mid-point of the longitudinal bales 96 and 98. As best shown in Figure 6 the bottom edges of the respective bailles 96, 98, 100 and 102 are coplanar and are spaced substantially above the lower edge of the cover Aplate 92. The shield assembly isY completed by' corner plates 104 and 106 which extend around the front corners of the shieldsubstantially from the ends of the baffles 10096 and 102-98 and project below Athe lower edge ofthe cover plate 92. Shield-assembly 28 is preferably heldin place byl a pair of screws 108 threaded directly into the burner castings. v

The T-shaped assemblies formed by the respective baffles 96 and 100, and bafes 98 and 102, serve in operaair inlet sections 44.

primary air is effected.

The bae 94 seals the space in .the region of; the rear`v` ward lateral edge of the shield assembly 28. It prevents the establishment of a vacuum within this area of the shield which actual experiments have shown is otherwise caused by wind blowing parallel tothe lower edge of the cover plate 92. The bafes 104'and 106 serve essentially the same purpose as the balles 96-102, and are particularly eiective when the ambient wind blows diagonally across the corners of the cover plate 92.

Together the bales p-revent turbulence in the region of the primary area intake and establish and maintain substantially uniform air pressures in this region to promote uniform and non-turbulent inspiration of primary air thereby maintaining high burner eiiiciencyV even unde Y adverse ambient conditions.

From the foregoing it will be apparent that the abovestated objects and advantages of the invention have been attained by the provision of' improved burner assemblies which are substantially completely windproof and are thus operable with good eiciency under conditions which preclude the satisfactory operation of prior burners.

The invention may be embodied in other speciicvforms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered lin all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claim rather than by the foregoing description,

direction generally normal to the surface of said burner element, an additional duct assembly extending generally parallel to the surface of said burner element across said .heat directing `duct assembly adjacent said burner elecomprising a dishshaped member extending over said air inlet opening, the open side of which-faces said air inlet opening, a baie having one edge secured to one lateral edge of said dish-shaped member and extending inwardly i therefrom parallel to the bottom wall of said dish-shaped I Y member, la pair of baies extending around the respective and all changes which come within the meaning and v,

corners of said dish-shaped member and projecting from the lower edge of said dish-shaped member, and air directing vanes projecting from said bottom wall of said dish-shaped mamber .toward said air -inlet opening.

References Cited in the file of this patent UNITED STATES PATENTS 792,323 Dudgeon June 13, 1905 1,677,156 Vaughn July 17, 1928 2,051,213 Hamilton Aug. 18, 1936 2,379,766 Tweeddale July 3, 1945 2,517,071 Wyatt Aug, 1, o 2,531,139 Lilly et al. Nov. 21, 1950 2,551,823 Buttner et al May 8, 1951 2,806,465V Hess a Sept. 17, 1957 FOREIGN PATENTS 1,070,317 France Feb. 17, 1954 1,134,715 France Dec. 3, 1956 545,339 Great Britain May 20,y 1942 621,611 Great Britain Apr. 13, 1949

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