US3681002A

US3681002A - Self-igniting burners

Info

Publication number: US3681002A
Application number: US867480A
Authority: US
Inventors: Esher R Weller; William R Staats; Robert B Rosenberg
Original assignee: ESHER R WELLER; ROBERT B ROSENBERG; WILLIAM R STAATS
Current assignee: ESHER R WELLER; ROBERT B ROSENBERG; WILLIAM R STAATS
Priority date: 1969-10-20
Filing date: 1969-10-20
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01

Abstract

A self-igniting gas burner which includes, generally, an oxidation catalyst which is supported by means of a gas-permeable catalyst support plate. A mixture of gaseous fuel is supplied to and permeates through the catalyst support plate. In doing so, the gaseous fuel is oxidized to cause combustion. The combustion of the gaseous fuel heats the catalyst support plate which then radiates heat to a load. The hot products of reaction also pass through the catalyst support plate, to heat the load.

Description

United States Patent Weller et al.

[ 51 Aug. 1, 1972 [54] SELF-IGNITING BURNERS [72] Inventors: Esher R. Weller, 7616 William Ave., Downers Grove, 111. 60515; William R. Stats, 3100 Wabash Ave., Chicago, 111. 60616; Robert B. Rosenberg, 9138 Mozart, Evergreen 3,191,659 6/1965 Weiss ..431/328 3,245,458 4/1966 Patrick et al.. 3,255,802 6/1966 Browning 3,518,036 6/1970 Statts et al. ..431/268 1,225,381 5/1917 Wedge ..431/328 Primary Examiner-Frederick L. Matteson Assistant Examiner-Harry B. Ramey Attorney-Dominik, Knechtel & Godula [5 7] ABSTRACT A self-igniting gas burner which includes, generally, an oxidation catalyst which is supported by means of a gas-permeable catalyst support plate. A mixture of gaseous fuel is supplied to and permeates through the catalyst support plate. In doing so, the gaseous fuel is oxidized to cause combustion. The combustion of the gaseous fuel heats the catalyst support plate which then radiates heat to a load. The hot products of reaction also pass through the catalyst support plate, to heat the load.

2 Claims, 7 Drawing Figures PATENTED B 1 I973 .FIG. 1

SOURCE GASEOUS FUEL 5 FIG. 2

OF GASEOUS FUEL l5 INVENTORS Esher R. Kwe/ler William R Sfaafs BY R006 8. Rosenberg ATTYS.

SELF-IGNITING BURNERS This invention relates to improved self-igniting gas burners and, more particularly, it relates to improved self-igniting gas burners which operate on natural gas rather than manufactured gas and which are flameless.

Presently, most, if not all gas applicances operate on natural gas rather than manufactured gas, and natural gas contains mostly methane. Numerous attempts have been made by' those skilled in the art to construct a true catalytic igniter for natural gas, however, none of these attempts have been successful. In fact, the reports given on these prior attempts generally conclude that methane cannot be catalytically ignited by a solid catalyst below approximately 200 F.

In a copending application, there is disclosed an improved apparatus and true catalytic ignition process for igniting natural gas, using a cold catalyst. This process includes, generally, the steps 03 mixing a small amount of hydrogen with natural gas, impinging this mixture of hydrogen and natural gas onto a cold solid catalyst, that is, one at ambient temperatures, to cause the latter to heat up to a high enough temperature to ignite the mixture, and stopping the flow of hydrogen which is mixed with the natural gas after ignition has occurred. v

It has been found that the same general principle can be used to provide a self-igniting flameless gas burner. Presently, there are available various different types of gas burners which are generally referred to as flameless." However, it is only after the stream of gaseous fuel supplied thereto is ignited by means of some external ignition source and this flame heats the burner plate to a sufficiently high temperature to support combustion on its surface that the gas burner is flameless. That is, when the surface of the burner plate is sufficiently hot to support combustion, the flame is drawn onto the surface of the burner plate and combustion continues in a flameless fashion. The self-igniting flameless gas burner of the present invention, on the other hand, provides for ignition without the need for any external ignition source such as a pilot flame, a glow coil ignited pilot, or a spark ignited pilot or main burner flame, and without the need for first producing a gas flame.

In addition to providing a self-igniting flameless gas burner which operates on natural gas, a low tempera ture (200-500 F.) burner which requires no venting can be provided, simply by employing a gaseous fuel mixture of hydrogen and an inert gas such as nitrogen. Such a low temperature burner has particular applica- I tion as a warming tray or as a radiant wall panel.

Accordingly, it is an object of the present invention to provide improved self-igniting gas burners.

A more particular object is to provide improved selfigniting gas burners which operate on natural gas.

Another object is to provide improved self-igniting gas burners which operate on natural gas and which are flameless.

Still another object is to provide improved self-igniting flameless gas burners which operate on natural gas and are of a design such that the need for any external ignition source, such as a pilot flame, a glow coil ignited pilot or a spark ignited pilot or main burner flame, is eliminated.

A still further object is to provide improved self-igniting flameless gas burners of the above-described type of a design such that they may be ignited without the need for first producing a gas flame.

Still another object is to provide improved self-igniting flameless gas burners of the above-described type wherein ignition is provided by catalysis of an initially cool surface.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The above objectives are accomplished by means of a self-igniting gas burner which includes, generally, an oxidation catalyst which is supported by means of a gas-permeable catalyst support plate. A mixture of gaseous fuel is supplied to and permeates through the catalyst support plate. In doing so, the gaseous fuel is oxidized to cause combustion. The combustion of the gaseous fuel heats the catalyst support plate which then radiates heat to the load. The hot products of reaction also pass through the catalyst support plate, to heat the load. I

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others and the apparatus embodying features of construction, combination of elements and arrangement of parts which are adapted to effect such steps, all as exmplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a side plan view, partly sectionalized, of a self-igniting flameless gas burner exemplary of the invention;

FIG. 2 is a top plan view of the burner of FIG. 1;

FIGS. 3 and 4 are a top plan view and a sectional view, respectively, of a catalyst support plate;

FIGS. 5 and 6 are a top plan view and a sectional view, respectively, of another catalyst support plate; and

FIG. 7 is a plan view of a self-igniting flameless gas burner including means for generating hydrogen and oxygen.

Similar reference characters refer to similar parts throughout the several views of the drawings. 1

Referring now to the drawings, in FIGS. 1 and 2 there is illustrated a self-igniting flameless gas burner 10 including a catalyst support plate 1 1 which is affixed to and supported by a burner body 12. The burner body 12 has an inlet 13 for admiting gaseous fuel supplied thereto through conduit means 14, from a source of gaseous fuel 15. The burner body 12 also has a section 16 forming a venturi, so that the gaseous fuel passing through the inlet 13 and the venturi section 16 inspirates air and thoroughly mixes it with the gaseous fuel. A control valve 17 is included in the conduit means 14, for controlling the flow of gaseous fuel from the source 15 to the burner 10. The catalyst support plate 11 is impregnated with a catalyst that is active with hydrogen, such as for example, platinum or palladium, in the manner described more fully below.

The catalyst support plate 11 is affixed to the open top of the burner body 12 so as to close the same, and can be of any suitable shape, such as circular, as illustrated. It is essential to the operation of the burner 10 that the catalyst support plate be of a gas-permeable refractory material such as alumina, silica, zirconia, thoria or a mixture of refractory material such as a zircon mullite composition, so that the mixture of gaseous fuel can permeate through it.

The source of gaseous fuel 15, in accordance with a first embodiment of the invention, is a mixture of natural gas and hydrogen, the latter being necessary to provide the self-igniting character to the burner 10. Hydrogen can be used as the sole fuel, however, it presents at least two disadvantages: (1) it has a low heating value, and thus it is difficult to get the catalyst support plate 11 sufficiently hot and (2) when the rate of flow of hydrogen is altered, an explosive range resulting in ,flashback is encountered. Accordingly, it is necessary to use a mixture of natural gas and hydrogen to eliminate this undesirable feature. In particular, if the natural gas is methane, a mixture containing at least 30 percent hydrogen is critical to obtain ignition and less than 70 percent hydrogen is critical to avoid flashback. If butane, propane or other combustible gas is used the percentage of hydrogen in the mixture is appropriately adjusted to assure ignition and to avoid flashback.

When the control valve 17 is operated to permit natural gas to flow from the source to the burner 10, the natural gas flowing through the inlet 13 inspirates air and the latter is thoroughly mixed with the natural gas as it passes through the venturi section 16. As this mixture of gaseous fuel impinges on the underside of the catalyst support plate 11, the hydrogen reacts with the catalyst impregnated in the catalyst support plate 11 and generates heat. As the catalyst support plate 11 gets hot, the natural gas also reacts on the catalyst support plate and the latter is rapidly heated. The catalyst support plate 11 can be completely impregnated with the catalyst, in which case, combustion will occur on its underside. The catalyst support plate 11 will glow red hot when the burner 10 is operating at its maximum fuel input so that its operation can be visibly observed. However, at lower temperature ranges, this glow may not be observed, since combustion occurs on the underside of the catalyst support plate 1 1.

In many cases, it is preferable to have combustion occur at the top surface of the catalyst support plate 11 so that the operation of the burner can be observed at the low fuel inputs. This is accomplished by impregnating only the top surface of the catalyst support plate 11 with the catalyst, to a depth of approximately oneeighth inch.

The heated catalyst support plate radiates heat to the load. The hot products of reaction (CO and water vapor) also pass through the permeable catalyst support plate 11 to heat the load. The load may be a pot or pan supported above the catalyst support plate 11 in a range top burner application or it could be, for example, a water heater.

A burner constructed and operated in the abovedescribed manner is flameless, and has a temperature range of approximately 4001,400 F. In addition, the burner has a high turndown ratio. Too great a flow rate of the gaseous fuel supplied to the burner will not cause ignition of the gaseous fuel so as to produce a gas flame, however, the gaseous fuel may permeate through the catalyst support plate and escape to the atmosphere. It, therefore, is desirable to control the flow rate to avoid such an occurrence.

The burner 10 also can be operated as a low temperature in a range of 200-500 F., burner simply by providing a source of gaseous fuel comprising a mixture of hydrogen and an inert gas such as nitrogen. A burner of this type has the same advantages as the abovedescribed high temperature burner and, in addition, offers the advantage of a controlled low temperature burner as well as the further advantage that no venting is required since the only combustion product is water vapor. Such aburner therefore is particularly applicable for use as a warming tray, or a radiant wall panel.

Normally, the load is supported atop the burner 10 by means such as a grate or the like, however, the load can be seated directly on the catalyst support plate. In some applications, particularly with the low temperature burner, a catalyst support plate such as the catalyst support plate 20 shown in FIGS. 3 and 4 can be provided. This catalyst support plate 20 has a number of parallel, recessed grooves 21 formed in its top surface, and only the bottom walls 22 (FIG. 4) of the grooves 21 are impregnated with the catalyst. Also, the top surface of the catalyst support plate 20 with the exception of the area defined by the bottom walls 22 preferably is sealed in an appropriate manner, to prevent the gaseous fuel from permeating through it and escaping to the atmosphere.

Alternatively, a catalyst support plate .30 having a number of support pins 31 extending through it, as illustrated in FIGS. 5 and 6,"can be provided. In this case, the support pins 31 project beyond the top surface of the catalyst support plate, and form a support for the load. While only a number of individual pins 31 are illustrated, it will be appreciated that a number of these pins can form a support for a grill or grate above the top surface of the catalyst support plate 30.

In FIG. 7, there is shown a self-igniting flameless gas burner 40 which is fueled with natural gas (methane) from a source generally found in the home and elsewhere, and which includes an electrolytic cell 41 for generating hydrogen and oxygen. This hydrogen and oxygen is used to initiate combustion in the manner described below.

More particularly, the burner 40'includes a catalyst support plate 42 which is affixed to and supported by a burner body 48, both of which may be of the same general construction of the burner 10. The electrolytic cell 41 includes a pair of

electrodes

43 and 44 which are affixed within a reservoir 45, preferably in vertically disposed spaced relationship. The reservoir 45 includes means (not shown) replenishing and maintaining the supply of electrolytic material disposed within it, and has an opening 46 coupled to a pilot gas supply line 47. The electrolytic material preferably and advantageously comprises water, but can be any suitable aqueous solution of acids, alkalis or salts.

The

electrodes

43 and 44 are electrically coupled to respective ones of the output terminals of a secondary winding 49 of a transformer 50, the primary winding 51 of which is coupled to a source of power 52 which may be a volt source normally found in the home. A normally open switch 54 is included in the electrical coupling between the primary winding 51 and the source of power 52 and is operative to control the energization of the transformer 50, and hence the electrolytic cell 41, in a manner described more fully below.

A main gas line 56 is coupled to a source of natural gas, (not shown), and includes a control valve 57 for controlling the flow of natural gas from the source to the conduit 58 and to the pilot gas supply line 47. The burner body 43 has an inlet 59 for admitting gaseous fuel supplied thereto through the conduit means 58. The one end of the pilot gas supply line-47 extends through the burner body 48 and terminates in close proximity to the underside of the catalyst support plate 42. I

The control valve 57 has three positions, an off position, an ignition position and a burner position, and further is coupled to and operative to operate the switch 54. Its operation is as follows. When in its off position, the flow of natural gas to the burner is cut off, and the switch 54 is opened. When it is operated to its ignition position, natural gas is permitted to flow through the pilot gas supply line 47, and the switch 54 is closed to thereby energize the transformer 50 and hence the electrolytic cell 41. Ignition is initiated, in the manner described more fully below, and the control valve 57 is then operated to its burner position. In this position, the flow of natural gas through the pilot gas supply line is cut off and is directed through the conduit 58. Also, the switch 54 is again opened.

The operation of the self-igniting flameless gas burner 40 therefore is as follows. The control valve 57 is operated to its ignition position to close the switch 54 to energize the electrolytic cell 41 and to direct the flow of natural gas through the gas pilot supply line 47. In the electrolytic cell 41, electrolysis occurs and hydrogen and oxygen are produced. This hydrogen and oxygen is swept up by the flow of natural gas through the gas pilot supply line 47, and is mixed with and carried by it through the gas pilot supply line 47. This mixture of natural gas, hydrogen and oxygen is impinged on the underside of the catalyst support plate 42. The hydrogen, with oxygen, reacts with the catalyst impregnated in the catalyst support plate 42 and causes the latter to heat up. After a short period, approximately 30 seconds, the area of the catalyst support plate immediately surrounding the end of the gas pilot supply line 47 becomes sufficiently hot, as evidenced by its reddish glow, to support and maintain combustion of the natural gas and air mixture delivered to the burner through the conduit 58 and the burner body 48.

Accordingly, at this time, the control valve 57 is operated to its burner position where, as described above, the switch 54 is again opened to de-energize the electrolytic cell 41 and the flow of natural gas is now directed through the conduit 58 rather than through the gas pilot supply line 47. As the natural gas flows through the inlet 60, it inspirates air and the latter is mixed with the natural gas as it flows through the venturi section 61 of the burner body 48. This combustible air-gas mixture reacts on the hot area of the catalyst support plate 42, and the latter is rapidly heated from this hot area outwardly.

The catalyst can be impregnated completely through the catalyst support plate 42, in which case, combustion will occur on the underside of the catalyst support plate. If combustion on top of the catalyst support plate 42 is desired so that operation of the burner can be easily visibly observed, only the top surface thereof is impregnated with the catalyst to a depth of approximately one-eighth inch.

To turn off the burner 40, the control valve is merely operated to its off position. In this position, the switch 54 remains open so that power is cut off from the elec trolytic cell and the flow of natural gas from the source is cut off.

It will thus'be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and certain changes may be made in carrying out the above method and in the construction set forth. Accordingly, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Now that the invention has been described, what is claimed as new and desired to be secured by Letters Patent is:

l. A self-igniting flameless gas burner comprising, in combination: a burner body having an outlet; a gas permeable catalyst support plate which is impregnated with a catalyst which is active with hydrogen affixed to said burner body so as to close said outlet therein; a source of gaseous fuel coupled into said burner body, control means for controlling the flow of gaseous fuel from said source into said burner body, a source of hydrogen for providing and mixing hydrogen with the flow of gaseous fuel into said burner body, said source of hydrogen comprises an electrolytic cell, means for controlling the flow of hydrogen from said source comprising a source of power coupled to said electrolytic cell, a normally open switch means electrically included in said coupling between said source of power and said electrolytic cell, said control means for controlling the flow of gaseous fuel being operable to open and close said normally open switch means, said gaseous fuel and hydrogen permeating through said catalyst support plate from the underside thereof and said hydrogen in doing so reacting with said catalyst impregnated therein and heating said catalyst support plate to a temperature sufficient to cause combustion of said gaseous fuel to further heat said catalyst support.

2. A self-igniting flameless gas burner comprising, in combination: a burner body having an outlet; a gas permeable catalyst support plate forming a support for a load and being impregnated with a catalyst which is active with hydrogen affixed to said burner body so as to close said outlet therein, said catalyst support plate having a number of parallel, recessed grooves formed in its top surface, the bottom walls only of said recessed grooves being impregnated with said catalyst, the top surface of said catalyst support plate with the exception of the area defined by said bottom walls of said recessed grooves being sealed to prevent fuel gas from permeating through it and escaping to the atmosphere; a source of fuel gas coupled into said burner body, control means for controlling the flow of fuel gas from said source into said burner body, a source of hydrogen for providing and mixing hydrogen with the flow of fuel gas into said burner body, and means for controlling the flow of hydrogen from said source of hydrogen, said fuel gas and hydrogen permeating through said catalyst support plate from the underside thereof and said hydrogen in doing so reacting with said catalyst impregnated therein and heating said catalyst support plate to a temperature sufficient to cause combustion of said fuel gas to further heat said catalyst support, whereby combustion of said fuel gas is initiated without the need of any external ignition source and without the need for producing a flame.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,681,002 Dated August '1, 1972 Esher R. Kweller, William R. Staats, Robert B. Rosenberg Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The name of the first-listed inventor is incorrectly spelled. It should be "Esher R. Kweller".

The assignee of record is not listed in the patent. According to the Assignment document recorded in the Patent Office on May 19, 1972, Reel 2851, Frame 053, the assignee is as follows:

-Assignee: The Institute of Gas Technology, Chicago, Illinois-- (a not-for-profit corporation) Signed and sealed this 23rd day of January 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM po'wso uscoMM-oc scam-ps9 U45. GOVERNMENT PRINTING OFFICE: 568 0*366'334