Patent Abstract:
A burner for use on a gas range top in which the burner combustion products heat the bottom surface of a ceramic-glass plate. My stoichiometric burners provide optimum performance when they are used to heat surfaces which operate at low temperatures such as a water heater or a steam boiler. 
     There are, however, other applications wherein the surfaces to be heated must operate at high temperatures such as a broiler for a gas range. 
     A new principle stoichiometric equation is provided for the spacing of the apertures in the top surface of the burner chamber when the stoichiometric burner is exposed to a thermal radiation field. 
     A new principle blower for forcing the combustion air through a heat exchanger is now described in U.S. Pat. No. 3,859,009.

Full Description:
This is a continuation-in-part of my application Ser. No. 654,113, filed Feb. 2, 1976, which, in turn, is a continuation-in-part of my application Ser. No. 518,473, filed Oct. 29, 1974 the latter two applications having been abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The glass-top electric range has experienced wide market acceptance and is destined to become a larger factor in the gas range market, because the housewife has found that it is very easy to clean. There is also a reduced fire hazard. The sales of gas ranges have decreased in the same ratio as marked penetration of the glass-top range sales. 
     Stoichiometric burners are described in various configurations in my applications Ser. No. 419,514, filed Nov. 28, 1973 and Ser. No. 687,663, filed May 19, 1976, abandoned but continued in my application Ser. No. 727,578, filed Sept. 28, 1976, and; Ser. No. 687,682, also filed May 19, 1976. 
     My new stoichiometric burner for operation in a radiation is entitled IMPROVED GAS BURNER, was filed June 16, 1976, Ser. No. 696,792, which is a Continuation-in-Part of an application filed Sept. 5, 1975, Ser. No. 610,562, which in turn is a continuation-in-part of my application Ser. No. 580,544, filed May 27, 1975 the latter, two applications have been abandoned. 
     A new ceramic glass burner is disclosed also in said continuation-in-part application of the above-identified application, Ser. No. 518,473. 
     DESCRIPTION OF THE INVENTION 
     I have discovered that, for example, in radiation field the particular linear spacing of the apertures through which gaseous fuel is discharged in free turbulent jets must be modified if the gas and fuel temperature differ. This is particularly true in ceramic glass burners; therefore, my ceramic-glass burner is an integration of several unique components as follows: 
     I. A stoichiometric burner constructed as burner-absorber-exchanger in which apertures are arranged in accordance with the following relation: 
     
         D.sub.s = 2.4 to 2.5 R d.sub.o [T.sub.RG /T.sub.RA ] 
    
     where 
     D s  is the stoichiometric aperture spacing 
     R = the air-gas ratio (about 10:1) 
     d o  = the aperture diameter 
     T RG  = the Rankine temperature of the gaseous fuel 
     T RA  = the Rankine temperature of the combustion air 
     Whereby preferably the apertures are arranged in arrays establishing septor burners. The space above this unit is limited by a ceramic-glass plate which radiates in down direction. 
     II. The space above the burner&#39;s stoichiometric plane of demarcation but below the ceramic-glass plate is the combustion chamber wherein the products of combustion have reached their maximum temperature. 
     III. The space above the &#34;burner-absorber-exchanger&#34; but below the plane of demarcation is a mixing chamber wherein the combustion air flows through the lower section of the counter-flow recuperator. 
     IV. The space above the combustion chmaber, but below the ceramic-glass plate, includes another heat exchanger, wherein the products of combustion flow in opposite directions along the bottom surface of the ceramic-glass plate and then flow downward into the upper section of the counterflow recuperator. These combustion products transfer their heat to the fins in the lower section of the counterflow recuperator whereby the combustion air is heated by the fins. 
     V. The chamber below the counterflow recuperator contains my centrigufal blower which forces the combustion air and subsequently the products of combustion through the lower and upper sections of the two recuperators. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, its objects and features, and advantages thereof will be better understood from the following description, which merely illustrates exemplary preferred embodiments of structure which may be utilized to practice the invention, taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a sectional elevation of the ceramic-glass top burner; 
     FIG. 2 is a top view of the heat exchange chamber; 
     FIG. 3 is a sectional view of the element defining the combustion chamber; 
     FIG. 4 is a sectional side elevation of the ceramic-glass top burner; 
     FIG. 5 is a top view of the combustion chamber which also shows the upper section of the counter ow recuperator; 
     FIG. 6 is a top view of the rectangular &#34;burner-absorber-exchanger&#34;; 
     FIG. 7 is a cross-sectional elevation of the &#34;burner-absorber-exchanger&#34;; 
     FIG. 8 is a quadrature cross-sectional elevation of the &#34;burner-absorber-exchanger&#34;; 
     FIG. 9 is a top view of my circular &#34;burner-absorber-exchanger&#34;; and 
     FIG. 10 is a cross-section of my circular &#34;burner-absorber-exchanger&#34;. 
    
    
     Turning first to FIG. 1, reference numeral 1 is the ceramic-glass plate which has a uniform thickness of about 3/16 inch. 2 is the wall of the heat exchange chamber 2&#39; which also supports the ceramic-glass top plate 1. The wall 2 is cemented to the bottom of the ceramic-glass plate 1, and is shown in detail in FIG. 2. The chamber 2&#39; is supported by an element 3 defining a combustion chamber 3&#39;, and is shown in detail in FIGS. 3 and 5. The cumbustion chamber defining element 3 is supported by a plate 6. Plate 6 has an opening which is identical to the bottom opening in FIG. 3. Plate 6 has the same internal peripheral dimensions as the heat exchange chamber 2&#39; as shown in FIG. 2. However, plate 6 also has slots which are identical with fins 4 and fins 5 in FIG. 4. The fins 4 and 5 are supported by a housing 7. The housing 7 also provides a mixing chamber 8 which contains the &#34;burner-absorber-exchanger&#34;, as described in FIGS. 6, 7, 8 or 9 and 10, and which I label as B-A-E. 
     FIG. 4 is a sectional end view of the ceramic-glass top burner. The fins 4 and 5 are positioned in the recuperator cavities as shown in FIGS. 3 and 4. The electric motor 10 is supported by the blower housing 11. The supports are not shown. The blower impeller 12 is mounted on the motor shaft 13. The combustion air enters through the fins 4 of the counterflow recuperator along arrows 15. The combustion products leaving the combustion chamber 2&#39; discharge through the fins 4 and fins 5 of the counterflow recuperator and flow along path 16 to the rear of the range top and then into the room. The combustion air flows radially from the impeller 12 in the plenum 14 as shown by arrows 15. The air enters the fins 4 and flows into the mixing chamber 8, as shown in FIG. 4. The combustion air then flows in the mixing chamber cavity 8 and up into the combustion chamber 3&#39;. The combustion products flow radially out from heat exchange chamber 2&#39; and enter the recuperator fins 4 and 5 as shown by arrows 16. Finally, the combustion products leave the recuperator fins 4 and 5 in 45° change in direction in a quasi-radial flow. 
     FIG. 6 is a top view of a first example for a &#34;burner-absorber-exchanger&#34; (B-A-E) which is made entirely of steel. 
     The gaseous fuel enters coupling 30 and then flows in opposite directions between the outer casing 31 and the exchanger wall 32. The width of the passage between the two walls is 1/16 inches. 
     The top surface 33 is welded to the outer casing 31. The inner liner 32 is welded to the top surface 33 also. Thus, the gaseuous fuel has a long path in the exchanger passages before it enters the chamber 35 through the aperture 30a. The gaseous fuel thus flows along the top surface 33 to the orifices 36 from all directions and is thus further heated by the top surface 33 which absorbs the radiation from the ceramic-glass plate 1. The top surface 33 is also coated with a colloidal graphite which has a high absorptivity. The tube 34 receives the electric igniter which consists of the igniter resistor 39 which is supported by the porcelain ceramic 37, which in turn, is supported by a clamp. 
     FIG. 7 is a cross-sectional elevation of the &#34;burner-absorber-exchanger&#34;. The exchanger flange 32 is welded to the top surface 33. The exchanger flange 32 has a high temperature and a long path and is most effective in heating the gaseous fuel which flows between the outer casing 31 and exchanger wall 32. 
     FIG. 8 shows a cross-sectional elevation of the &#34;burner-absorber-exchanger&#34;. FIG. 8 also shows a cross-sectional elevation of the tube 44 and in addition shows the electric igniter 39, which is positioned partly within the tube 44. The igniter ceramic base 37 is supported by a clamp which is not shown. The spade terminals 38 will fit into the socket which is not shown. 
     My new &#34;burner-absorber-exchanger&#34; (FIGS. 9 and 10) produces outstanding performance. The gaseous fuel is heated to a temperature of 725° F and the combustion air is heated to a temperature of 550° F. These temperatures determine the Rankine temperature ratio in the formula for the aperture spacing. The heat output of my stoichiometric burner at a gas pressure of 4 inches w.c. is 9500 BTU/hr. initially and then decreased to 6300 BTU/hr. The burner cycled at a rate of 10 seconds off and 20 seconds on. The ceramic plate reached a temperature of 1085° F in 5 minutes and stabilized at a temperature of 1100° F ± 25° F. Since the gaseous fuel flow was two-thirds of the time with a heat output of 6300 BTU/hr., the actual gas consumption would produce a heat output of 4200 BTU/hr. The combustion was perfect with no deposition of carbon on the ceramic plate. 
     This new component is shown in FIGS. 9 and 10. Gaseous fuel enters coupling 40 and then flows in opposite directions between the outer casing 41 and the exchanger wall 42. The width of the passage between the two walls in 1/16 inches, and that space defines an annular flow path for the fuel gas. 
     The top surface 43 is welded to the outer casing 41. The inner liner 42 is welded to the top surface 43 also. Thus, the gaseous fuel has a long path in the exchanger passages before it enters the chamber 45 through the aperture 40a which is located opposite inlet 40. 
     The gaseous fuel thus flows along the top surface 43 to the orifices 46 from all directions and is thus further heated by the top surface 43 which absorbs the radiation from the ceramic-glass plate 1. The top surface 43 is also coated with colloidal graphite which has a high absorptivity. The tube 44 receives the electric igniter which consists of an igniter resistor which is supported by the porcelain ceramic, which in turn, is supported by the clamp. 
     The unit as shown in FIGS. 9 and 10 constitutes a second example of the above mentioned three combination units A-B-E. The top surface of plate 43 is a vigorous absorber of radiation which is used to preheat the fuel gas as flowing in the annular space between flanges 41 and 42. The two septor burners 46 constituted by seven apertures, spaced as per the rule outlined above, constitute the burner. The flange 42 actually is the prime element of the heat exchanger. 
     In a typical example, the Rankine temperature of the fuel as so preheated is about 1185 and the Rankine temperature of the combustion air, after having been preheated by the combustion gases, is about 1010, so that T RG  /T RA  is about 1.173 For a diameter d o  of the apertures 46 of 16/1000 inches, a spacing of D s  = 0.454 is the proper value. 
     Turning now to certain particulars of my construction, the combustion chamber 2 is produced as a single ceramic component which is molded out of fused fibrous potassium aluminum silicate which can operate at 2300° F. The material will henceforth be designated as CERROFORM. The other molded form contains a central rectangular opening which is the mixing chamber and openings at each end which encase the counterflow recuperator fins. Cerroform has an emissivity of 93% of a black body radiator. Thermodynamics requires that the emissivity and absorptivity must be identical at the same termpature. Cerroform has a relatively low thermal conductivity. I have discovered that the heat losses from the combustion chamber can be greatly reduced by spraying molten aluminum on the surfaces of the Cerroform. The absorptivity of aluminum in the temperature range of 440° F to 1070° F is 0.039 to 0.057. Thus, about 94% of the radiation from the ceramic top plate is reflected and therefore contained in the combustion chamber, excluding the radiation from the ceramic top plate which passes through the opening to the mixing chamber. 
     The ceramic glass material has some very unusual characteristics. I believe that the material is polarized in an electric field during solidification since the lateral thermal conductivity is very low and the normal radiant transmissivity is very high. The emissivity of the material, like most ceramics, is very high. The surface area for cooking which is heated by the burner combustion products is about 56 in. 2 . Thus, the temperature of the combustion products after leaving the surface to be heated is very high. In order to obtain satisfactory efficiency, it is necessary to transfer a portion of this heat to the combustion air required by the stoichiometric burner. I have found that a form of counterflow recuperator which uses fins which pass through slots in the wall between the combustion products in the wall between the combustion products and the combustion air is quite efficient. 
     The counterflow recuperator requires a much greater pressure drop than can be produced by burner. The burner head is substantially lost when the burner combustion products impinge normally on the bottom surface of the ceramic top plate. For this reason, I provide a small supplementary blower to force the combustion air and combustion products through the various passages. 
     The radial flow blower wheel has a high static efficiency and operates without a scroll. Since the blower wheel is in the plenum chamber with the controls, there is a substantial saving in the space required. The radial flow blower impeller discharges air at a uniform velocity in all directions. The prior art blowers with a scroll discharge only in one direction and are quite bulky. The velocity of flow from the scroll exit is very nonuniform with the highest velocity near the cut-off and the lowest velocity at the scroll periphery. 
     A control system for this burner is disclosed in my copending application Ser. No. 645,112, filed Feb. 2, 1976 now U.S. Pat. No. 3,969,064, the content of which is incorporated by reference in this application.

Technology Classification (CPC): 5